ANTIPHOSPHOLIPID ANTIBODIES AND VASCULAR THROMBOSIS IN PATIENTS WITH THE MOST SEVERE FORMS OF COVID-19

BackgroundThe presence of antiphospholipid antibodies (aPL) has been observed in patients with COVID-19 (1,2), suggesting that they may be associated with deep vein thrombosis, pulmonary embolism, or stroke in severe cases (3). Antiphospholipid syndrome (APS) is a systemic autoimmune disorder and the most common form of acquired thrombophilia globally. At least one clinical criterion, vascular thrombosis (arterial, venous or microthrombosis) or pregnancy morbidity and at least one laboratory criterion- positive aPL two times at least 12 weeks apart: lupus anticoagulant (LA), anticardiolipin (aCL), anti-β2-glycoprotein 1 (anti-β2GPI) antibody, have to be met for international APS classification criteria(4). Several reports also associate anti-phosphatidylserine/prothrombin antibodies (aPS/PT) with APS.ObjectivesTo combine clinical data on arterial/venous thrombosis and pregnancy complications before and during hospitalisation with aPL laboratory findings at 4 time points (hospital admission, worsening of COVID-19, hospital discharge, and follow-up) in patients with the most severe forms of COVID-19 infection.MethodsPatients with COVID-19 pneumonia were consequetively enrolled, as they were admitted to the General hospital Pancevo. Exclusion criteria were previous diagnosis of inflammatory rheumatic disease and diagnosis of APS. Clinical data were obtained from the medical records. Laboratory results, including LA, aCL, anti-β2GPI, and aPS/PT antibodies were taken at hospital admission, worsening (defined as cytokine storm, connection of the patient to the respirator, use of the anti-IL-6 drug- Tocilizumab), at hospital discharge and at 3-months follow-up and sent to University Medical Centre Ljubljana, Slovenia for analysis. Statistics was performed by using SPSS 21.Results111 patients with COVID-19 pneumonia were recruited;7 patients died during hospitalisation (none were aPL-positive on admission and at the time of worsening), 3 due to pulmonary artery embolism. All patients were treated according to a predefined protocol which included antibiotics, corticosteroids, anticoagulation therapy and specific comorbidity drugs;patients with hypoxia were supported with oxygen. During hospitalisation, pulmonary artery thrombosis occurred in 5 patients, one was aPL-positive at all time points (was diagnosed with APS), others were negative. In addition, 9/101 patients had a history of thrombosis (5 arterial thrombosis (coronary and cerebral arteries), none of whom was aPL-positive on admission and at follow-up, and 4 venous thrombosis, one of which was aPL-positive at all time points and received an APS diagnosis). Among 9/101 patients with a history of thrombosis, 55.6% were transiently positive at the time of discharge, compared to patients without prior thrombosis, in whom 26.1% were transiently positive at the hospital release (p=0.074). Two patients had a history of pregnancy complications (both had miscarriage after 10th week of gestation), but did not have aPL positivity at any time point.ConclusionAlthough aPL was expected to be associated with vascular disease in the most severe forms of COVID-19, all patients that have died in our cohort were aPL negative. At hospital discharge, 56% of patients with a history of arterial or venous thrombosis had positive aPL that became negative at the 3-months follow-up (were transienlty positive), which should be considered when prescribing therapy after hospitalisation.References[1]Trahtemberg U, Rottapel R, Dos Santos CC, et al. Anticardiolipin and other antiphospholipid antibodies in critically ill COVID-19 positive and negative patients. Annals of the Rheumatic Diseases 2021;80:1236-1240.[2]Stelzer M, Henes J, Saur S. The Role of Antiphospholipid Antibodies in COVID-19. Curr Rheumatol Rep. 2021;23(9):72-4.[3]Xie Y, Wang X, Yang P, Zhang S. COVID-19 complicated by acute pulmonary embolism. Radiology: Cardiothoracic Imaging 2020: 2: e200067.[4]Miyakis S, Lockshin MD, Atsumi T, Branch DW, Brey RL, et al. J.Thromb.Haemost. 2006;4: 295-306.Acknowledgements:NIL.Disclosure of nterestsNone Declared.

AUTOANTIBODIES RELATED TO RHEUMATIC DISEASES AFTER COVID-19 INFECTION

BackgroundSARS-CoV-2(Severe acute respiratory syndrome coronavirus 2) has been circulating worldwide for three years. It mainly causes upper respiratory tract infection, which can manifest as pulmonary infection and even respiratory distress syndrome in severe cases. Different autoantibodies can be detected in patients infected with COVID-19.ObjectivesTo explore autoantibodies related to rheumatic diseases after COVID-19 infection.MethodsNinety-eight inpatients were tested for antinuclear antibodies (ANA), antibodies to extractable nuclear antigens(ENA), anti-neutrophil cytoplasmic antibodies（ANCA), anticardiolipin antibodies,a-β2GPI (IgG/IgM). They were from a tertiary hospital in Guangzhou during the COVID-19 epidemic. Data were described statistically.ResultsNinety-eight hospitalized patients were tested for relevant antibodies. The average age was 50.64±19.54;67 (68.4%) were male, 64 (65.3%) were COVID-19 positive, 90 (90.9%) had rheumatic diseases, and 56 of them were COVID-19 positive patients with rheumatic diseases.There were 76 patients tested for antinuclear antibodies;29 （38.16%）were negative, 18 （23.68%）had a 1/80 titre, and 29（28.16%） had a titre greater than 1:80. The 31 covid patients were positive for ANA. In the high-titer group, 19 patients with rheumatic diseases were positive for COVID-19, and 12 patients had an exacerbation of the rheumatic diseases (6 of whom had previously had pulmonary fibrosis). Of 31 covid patients, only two were non-rheumatic patients, and both were elderly, aged 85 and 100, respectively.Fifty-six patients had ENA results, and 29 for positive antibodies, 8 for ds-DNA antibodies, 2 for anti-Sm antibodies, 6 for anti-nucleosome antibodies, 12 for anti-U1RNP antibodies, 2 for anti-Scl-70 antibodies, 12 for anti-SS-A antibodies, 3 for anti-mitochondrial M2 antibodies, 2 for anti-centromere antibodies, 1 for anti-Po antibodies, and one for anti-Jo-1 antibody. All 56 patients had rheumatic diseases, and no new patients were found.There were 62 patients with ANCA data. P-ANCA was positive in 12 cases(19.35%), and MPO-ANCA was positive in 2 cases. An 85-year-old non-rheumatic COVID-19 patient was P-ANCA positive. She had a history of hypertension, colon cancer, CKD3, coronary heart disease, and atrial flutter.In the anticardiolipin antibodies group, there were 62 patients;only 6 were positive, and 2 were rheumatic patients infected with COVID-19. Antiphospholipid antibodies were detected in 33 patients, and a-β2GPI was tested in one patient, an 82-year-old COVID-19 patient with gout, diabetes, and cerebral infarction in the past. We did not find a statistical difference in the above results.ConclusionWe have not found a correlation between SARS-CoV-2 and serum autoantibodies of rheumatic immune diseases. It needs large samples and an extended follow-up to research.AcknowledgementsThis work was supported by Scientific and Technological Planning Project of Guangzhou City [202102020150], Guangdong Provincial Basic and Applied Basic Research Fund Project [2021A1515111172], National Natural Science Foundation of China Youth Fund [82201998] and Third Affiliated Hospital of Sun Yat-Sen University Cultivating Special Fund Project for National Natural Science Foundation of China [2022GZRPYQN01].Disclosure of Interestsone declared.

PROSPECTIVE EVALUATION OF THE EFFECT OF THE VACCINE AGAINST SARS-COV-2 IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS: DATA FROM SAFER STUDY

BackgroundSystemic lupus erythematosus (SLE) is an autoimmune disease, which presents an immune disorder that leads to the production of autoantibodies with potential involvement of multiple organs. Infections are one of the most frequent causes of hospitalization and death in lupus patients, and SARS-CoV-2 infection has been a global threat since March 2020. Immunization of these patients has been strongly recommended, although vaccine evaluation studies have not included this profile of patients.ObjectivesTo evaluate the immunogenicity and safety after 2 doses of the vaccine against SARS-CoV2 in patients with SLE.MethodsSubgroup of SLE patients from the prospective multicenter cohort of patients with immune-mediated diseases "SAFER” – Safety and Efficacy on COVID-19 Vaccine in Rheumatic Disease, a phase IV study. Vaccination against SARS-CoV-2 took place with vaccines approved by Brazilian regulatory bodies CoronaVac (Inactivated SARS-CoV-2 Vaccine), ChadOx-1 (AstraZeneca) and BNT162b2 (Pfizer-BioNTech) and this project followed in line with the guidelines of the National Immunization Plan in Brazil. Patients aged 18 years or older with a previous diagnosis of SLE (according to the 2019 ACR/EULAR criteria) were included. Patients were evaluated by telephone contact and in a face-to-face visit on the 28th day after each dose. Patients were followed up by means of blood collection for measurement of IgG antibody against SARS-COV-2 by chemiluminescence and disease activity assessed using SLEDAI-2K score.ResultsA total of 367 individuals with SLE were included, of whom 207 received 2 doses of CoronaVac, 128 received 2 doses of ChadOx-1 and 32 received 2 doses of BNT162b2. 90% of the subjects were female with a mean age of 37 years. About 42% (154) of the individuals included did not have any other associated comorbidity. 50% (182) of patients were using oral glucocorticoids and azathioprine was the most frequent immunosuppressive therapy. Regarding disease activity parameters, 38% (140) of patients had zero SLEDAI-2K at baseline and 41% (147) had zero SLEDAI-2K 28 days after the 2nd dose. Anti-DNA positivity was 30.7% (16/52) at inclusion and 32.6% (17/52) 28 days after the 2nd dose. Complement consumption was present in 18% (10/55) at inclusion and in 14.5% (8/55) 28 days after the 2nd vaccine dose. The geometric mean titers of IgG antibodies against SARS-COV-2 increased in the different vaccine groups, log 2.27 BAU/mL at inclusion and log 5.58 BAU/mL 28 days after the 2nd dose. Antibody titers after second dose varied between different vaccines, 4.96 BAU/mL CoronaVac, 6.00 BAU/mL ChadOx-1 and 7.31 BAU/mL BNT162b2 vaccine, p < 0.001. Only 3.54% (13/367) patients had covid-19 infection after the 15th day of the second dose of immunization, 9 of them having received 2 doses of CoronaVac, 4 of them of ChadOx-1 and none of them receiving BNT162b2, with p-value of 0.63.ConclusionThis study suggests that vaccines against SARS-COV-2 are safe in SLE patients. Induction of immunogenicity occurred in different vaccine regimens. Only 3.5% of individuals had COVID-19 infection with no difference between the types of vaccines evaluated. Future analyzes to explore the association of the effect of immunosuppressive medication, as well as the impact of booster doses and longer follow-up on clinical outcome will be performed.References[1]Mason A, et al. Lupus, vaccinations and COVID-19: What we know now. Lupus. 2021;30(10):1541-1552.[2]Furer V, Eviatar T, Zisman D, et al. Immunogenicity and safety of the BNT162b2 mRNA COVID-19 vaccine in adult patients with autoimmune inflammatory rheumatic diseases and in the general population: A multicentre study. Ann Rheum Dis. 2021;80(10):1330-1338.[3]Izmirly PM, Kim MY, Samanovic M, et al. Evaluation of Immune Response and Disease Status in SLE Patients Following SARS-CoV-2 Vaccination. Arthritis Rheumatol. Published online 2021.Acknowledgements:NIL.Disclosure of InterestsNone Declared.

CLINICAL AND IMMUNOLOGICAL PROFILES OF PATIENTS WITH ANTI-SYNTHETASE SYNDROME: A RETROSPECTIVE COHORT STUDY FROM A TERTIARY CENTRE

BackgroundAnti-synthetase syndrome (ASS) is a rare auto-immune condition that combines autoantibodies and specifics clinical manifestations, including myositis, interstitial lung disease (ILD), polyarthritis, mechanic's hands, Raynaud's phenomenon, and unexplained fever. The hallmark of this syndrome is the presence of anti-aminoacyl-tRNA-synthetase (ARS) antibodies. Several anti-ARS antibodies have been described, anti-Jo1 being the most common, followed by anti-PL7, anti-PL12, anti-OJ, anti-EJ, anti-KS, anti-YRS, and anti-Zo. According to a recent epidemiological survey, the rising number of patients with autoimmune diseases, including idiopathic inflammatory myopathies (IIM) coincides with the COVID-19 pandemic.ObjectivesTo evaluate the clinical characteristics of ASS patients with different anti-ARS antibodies from a tertiary rheumatology center.MethodsWe conducted a retrospective, single-centered study on consecutive patients diagnosed with ASS from 1 January 2015 to 31 December 2022. Clinical and serologic data were obtained by medical records review from hospital database. Myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) were tested using commercial ELISA kits. We included all patients fulfilling Connor's criteria for ASS.ResultsSixty-one patients (44 females) with mean age 54.4 (13.8) years were included. The most frequently reported clinical manifestation was arthralgia (68.8%), followed by Raynaud's phenomenon (67.2%), ILD (65.6%), myositis (46%), mechanic's hands (44.3%), arthritis (39.3%), and fever (18.0%). The typical triad for ASS, including myositis, arthritis and ILD was present in 17 patients. Twenty-eight (45.9%) patients were PL7+, 21 (34.4%) were Jo1+, 3 (4.9%) were PL12+, and 2 (3.2%) were OJ+. Seven patients were positive for more than two anti-ARS antibodies. The most frequently found MAA was anti-Ro52 (n=23, 37.7%). Of the 61 patients included, 41 (67.2%) patients were diagnosed in the last 3 years (COVID-19 pandemic). The most frequently detected MSA in ASS patients diagnosed during COVID-19 pandemic was anti-PL7 (25/28), while anti-Jo1 was the most common MSA in ASS patients diagnosed before 2020 (p<0.05) (Fig 1).The anti-Jo1+ patients were younger, have significantly more frequent muscle involvement and significantly higher levels of CK than anti-PL7+ patients (p<0.05). The co-occurance of anti-Ro52 antibodies was more frequently observed in anti-Jo1+ patients (n=11, 52.4%) than in anti-PL7+ patients (n=6, 21.4%) (p<0.05). We did not find statistically significant differences between ASS groups regarding sex, disease duration, clinical manifestations including dermatologic lesions, Raynaud's phenomenon, arthralgia/arthritis, ILD, fever, and cancers (all p>0.05).ConclusionASS patients have heterogenous manifestations, and different types of anti-ARS antibodies are associated to distinct clinical and immunological features. The COVID-19 pandemic led to increase prevalence of ASS cases and to a remarkable shift in the anti-ARS antibodies profile, with increased frequency of anti-PL7 antibodies. Further studies are needed to investigate the link between SARS-CoV-2 infections and myositis.References[1]Witt LJ, et al. The Diagnosis and Treatment of Antisynthetase Syndrome. Clin Pulm Med. 2016 Sep;23(5):218-226.[2]Gracia-Ramos AE, et al. New Onset of Autoimmune Diseases Following COVID-19 Diagnosis. Cells. 2021 Dec 20;10(12):3592.[3]Connors GR, et al. Interstitial lung disease associated with the idiopathic inflammatory myopathies: what progress has been made in the past 35 years? Chest. 2010 Dec;138(6):1464-74.[4]García-Bravo Let al. Association of anti-SARS-COV-2 vaccine with increased incidence of myositis-related anti-RNA-synthetases auto-antibodies. J Transl Autoimmun. 2022 Jun 30;5:100160.Figure 1.ASS patients with positive anti-ARS antibodies per year (from 2015 to 2022). The green line shows the PL7+ patients;and the orange line shows the Jo1+ cases.[Figure omitted. See PDF]AcknowledgementsI have no acknowledgements to declare.Disclosure of Inter stsNone Declared.

PREDICTION OF MORTALITY USING CLUSTERS BASED ON CLINICAL AND LAB PARAMETERS: DATA FROM 2072 PATIENTS FROM INSPIRE COHORT

BackgroundLupus is a heterogenous diseases which results in significant premature mortality. Most studies have evaluated risk factors for lupus mortality using regression models which considers the phenotype in isolation. Identifying clusters of patients on the other hand may help overcome the limitations of such analyses.ObjectivesThe objectives of this study were to describe the causes of mortality and to analyze survival across clusters based on clinical phenotype and autoantibodies in patients of the Indian SLE Inception cohort for Research (INSPIRE)MethodsOut of all patients, enrolled in the INSPIRE database till March 3st 2022, those who had <10% missing variables in the clustering variables were included in the study. The cause of mortality and duration between the recruitment into the cohort and mortality was calculated. Agglomerative unsupervised hierarchical cluster analysis was performed using 25 variables that define SLE phenotype in clinical practice. The number of clusters were fixed using the elbow and silhouette methods. Survival rates were examined using Cox proportional hazards models: unadjusted, adjusted for age at disease onset, socio-economic status, steroid pulse, CYC, MMF usage and cluster of the patients.ResultsIndian patients with lupus have significant early mortality and the majority of deaths occurs outside the hospital setting.Out of 2211 patients in the cohort, 2072 were included into the analysis. The median (IQR) age of the patients was 26 (20-33) years and 91.7% were females. There were 288 (13.1%) patients with juvenile onset lupus. The median (range) duration of follow up of the patients was 37 (6-42) months. There were 170 deaths, with only 77 deaths occurring in a health care setting. Death within 6 months of enrollment occured in in 80 (47.1%) patients. Majority (n=87) succumbed to disease activity, 23 to infections, 24 to coexisting disease activity and infection and 21 to other causes. Pneumonia was the leading cause of death (n=24). Pneumococcal infection led to death in 11 patients and SARS-COV2 infection in 7 patients. The hierarchical clustering resulted in 4 clusters and the characteristics of these clusters are represented in a heatmap (Figure-1A,B). The mean (95% confidence interval [95% CI] survival was 39.17 (38.45-39.90), 39.52 (38.71-40.34), 37.73 (36.77-38.70) and 35.80 (34.10-37.49) months (p<0.001) in clusters 1, 2, 3 and 4, respectively with an HR (95% CI) of 2.34 (1.56, 3.49) for cluster 4 with cluster 1 as reference(Figure 1C). The adjusted model showed an HR (95%CI) for cluster 4 of 2.22 (1.48, 3.22) with an HR(95%CI) of 1.78 (1.29, 2.45) for low socioeconomic status as opposed to a high socioeconomic status (Table 1).ConclusionIndian patients with lupus have significant early mortality and the majority of deaths occurs outside the hospital setting. Disease activity as determined by the traditional activity measures may not be sufficient to understand the true magnitude of organ involvement resulting in mortality. Clinically relevant clusters can help clinicians identify those at high risk for mortality with greater accuracy.Table 1.Univariate and multivariate Cox regression models predicting mortalityUnivariateMultivariateVariablesHazard ratio (95% Confidence interval)P valueHazard ratio (95% Confidence interval)P valueCluster1Reference-Reference-20.87 (0.57, 1.34)0.5320.89 (0.57, 1.38)0.59831.22 (0.81, 1.84)0.3371.15 (0.76, 1.73)0.51342.34 (1.56, 3.49)<0.0012.22(1.48, 3.22)<0.001Socioeconomic statusLower1.78 (1.29, 2.45)<0.001Pulse steroidYes1.6 (0.99, 2.58)0.051MMFYes0.71 (0.48, 1.05)0.083CYCYes1.42 (0.99, 2.02)0.052Proliferative LNYes0.99 (0.62, 1.56)0.952Date of birth age0.99 (0.98, 1.01)0.657CYC- cyclophosphamide, MMF- Mycophenolate mofetilFigure 1.A. Agglomerative clustering dendrogram depicting the formation of four clusters. B.Heatmap depicting distribution of variables used in clustering C. Kaplan-Meier curve showing the survival function across the 4 clusters[Figure omitted. See PDF]REFERENCES:NIL.Acknowledgements:NIL.Disclosure of InterestsNone eclared.

DETECTION OF SARS COV-2 ANTIBODIES FOLLOWING VACCINATION IN PATIENTS WITH RHEUMATIC MUSCULOSKELETAL DISEASE (DECODIR) – A REPORT FROM A DANISH PROSPECTIVE COHORT STUDY

BackgroundThe COVID-19 pandemic caused concerns whether patients with rheumatic musculoskeletal disease (RMD) treated with conventional (cs) or biologic (b) disease modifying drugs (DMARDs) and/or prednisolone exhibit an adequate immune response to the applied SARS-CoV2 vaccines.ObjectivesWe established the DECODIR study to assess and compare the efficacy of the SARS-CoV2 vaccines administered as part of the national vaccine roll-out: BNT162b2 vaccine (Pfizer/BioNTech) and mRNA-1273 vaccine (Moderna). The vaccines were offered as two doses four weeks apart;followed by a booster vaccination six months later. This national regimen included inflammatory rheumatic patients regardless of their respective anti-inflammatory treatment. We used patients' SARS-CoV2 IgG serum level as proxy for vaccination response (1).MethodsThe study was conducted as a longitudinal prospective cohort study. Patients with rheumatoid arthritis (RA), spondyloarthropathies (SpA) or psoriatic arthritis (PsA) receiving their outpatient treatment at the Danish Hospital for Rheumatic Diseases, Sonderborg, and monitored in the Danish DANBIO registry, were included.Blood samples, Disease activity and treatment information (cs/bDMARD, prednisolone) were collected at baseline (i.e. prior to vaccination), after six weeks, six and twelve months. SARS-CoV-2 IgG levels in serum were assessed by ELISA (Thermo-Fischer), and manufacturer's cut-off (>=10 EliA U/mL) selected as definition of sufficient IgG response. Antibody response was measured and compared at all four time points.Associations between antibody response, age, gender, disease (RA/PsA/SpA), treatment (none, cs/bDMARD or prednisolone) and disease activity were tested using proportional odds regression and bootstrapped tests of medians. Results were reported using mean, median (IqR) and bootstrapped 95% confidence interval (CI) of the median.ResultsA total of 243 patients were included at baseline and all were followed-up after six weeks;data from 233 patients were available at six months and for 229 patients at twelve months' follow-up. Those 229 patients had completed the national vaccination programme.The measurements performed 6 months after baseline demonstrated a per se decrease of IgG levels for the whole study population (median of 2.08 EliA U/mL at 6 months vs. 16 EliA U/mL at 6 weeks). The final measurements performed after twelve months demonstrated a significant increase of IgG levels. Thus, the completed vaccination programme, was followed by a significant increase in IgG levels (median of 100 EliA U/mL at twelve months vs. 16.5 EliA U/mL at six months, p < 0.001).Sufficient response rates were now recorded in all treatment scenarios, also in patients treated with prednisolone or combination of csDMARD and bDMARD. These two groups were at 6 months characterized by significant lower response rates, when compared with patients without any DMARD treatment.ConclusionCompleted vaccination programme defined as two doses plus booster vaccination resulted in a sufficient vaccination response as measured by IgG levels regardless of RA treatment.It is noteworthy that IgG levels increased markedly in patients treated with a combination of cs/bDMARD or oral prednisolone, who had low IgG levels (below manufacturer's cut-off >=10 EliA U/mL) after 6 months. Our results strongly support the efficacy of the complete vaccination programme including the 3rd booster vaccine in patients with inflammatory rheumatic diseases.Figure 1.Serum IgG-levels at baseline, 6 weeks, 6 months and 12 months;stratified by antirheumatic treatment. (Box plot showing median and interquartile range).[Figure omitted. See PDF]Reference[1]Schreiber K. et al. Reduced Humoral Response of SARS-CoV-2 Antibodies following Vaccination in Patients with Inflammatory Rheumatic Diseases— an Interim Report from a Danish Prospective Cohort Study. Vaccines 2022, 10(1), 35;https://doi.org/10.3390/vaccines10010035AcknowledgementsWe acknowledge all patients contributing to the DANBIO registry.The Danish Rheumatologic Biobank is a knowledged for handling and storage of biological material.Lab chieftechnician Charlotte Drachmann is acknowledged for her assistance.Disclosure of InterestsChristine Graversgaard: None declared, Karen Schreiber Speakers bureau: Lilly, UCB, Henning Jakobsen: None declared, Randi Petersen: None declared, Anders Bo Bojesen: None declared, Niels Steen Krogh: None declared, Bente Glintborg Grant/research support from: Pfizer, AbbVie, BMS, Sandoz, Merete Lund Hetland: None declared, Oliver Hendricks Speakers bureau: Pfizer, Lilly, Novartis.

Characteristics and Clinical Implications of Anti-IFN-alpha cytokine antibodies in partial Recombinase Activating Gene Deficiency patients before and during the COVID-19 Pandemic

Introduction: With the onset of the COVID-19 pandemic, there was increased attention on anti- IFN-alpha autoantibodies and its correlation with severe clinical outcomes in a large group of patients. However, this correlation has not been extensively investigated in patients with partial Recombinase Activating Gene Deficiency (pRD) who are known to have increased prevalence of anti- IFN-alpha autoantibodies. Therefore, there is a need to assess the presence of anti- IFN-alpha antibodies in pRD patients before and after the COVID-19 pandemic and explore the relationship between anti- IFN-alpha antibody presence and clinical outcomes. Method(s): Sera was collected from the whole blood after informed consent and Enzyme-Linked Immunosorbent Assay was conducted to confirm the presence of IgG-specific anti- IFN-alpha autoantibodies. Positive samples were determined as OD values above 3 standard deviations of the healthy donor OD mean. Result(s): Our cohort included both adult (n = 13) and pediatric (n = 9) patients with variants in RAG1 and RAG2. Eleven patients (50%) out of the 22 showed elevated anti- IFN-alpha autoantibodies levels. Five patients (23%) were defined as low positive for anti- IFN-alpha autoantibodies, and 6 patients had no autoantibody titers. Of the 22 patients, 16 were symptomatic with infectious and non-infectious complications including recurrent viral and/or bacterial infections, autoimmune cytopenias, and lymphoproliferation. Ten (63%) of the symptomatic patients demonstrated high anti-IFN-alpha autoantibodies titers. Of the 11 patients with no or low neutralizing anti- IFN-alpha autoantibodies levels, 5 were asymptomatic. In temporal comparison, 16 samples were collected pre-COVID-19 pandemic;8 samples were collected during the pandemic, 2 of which belonged to patients with samples collected before and during the pandemic. In the pre-pandemic cohort, 66% had anti- IFN-alpha autoantibodies. Conversely, during the COVID-19 pandemic, 89% had anti- IFN-alpha autoantibodies. Of note, one patient who had neutralizing anti- IFN-alpha autoantibodies remained positive both before and during the pandemic despite HSCT. Patient also had a SARS-CoV-2 infection in summer of 2022 with a mild clinical course. Conclusions & Next Steps: We observed persistence of anti-IFN-alpha autoantibodies in our cohort post-pandemic and even post-HSCT. It is unclear whether the presence of anti-cytokine antibodies are risk factor for severe COVID-19.Copyright © 2023 Elsevier Inc.

Anti-interferon-alpha autoantibodies in patients with inborn errors of Immunity and rheumatic diseases before and during the COVID-19 pandemic

Introduction: Type 1 interferon (IFN) autoantibodies, such as anti-IFNalpha, have pathogenic significance in life-threatening COVID-19 pneumonia. Ten to twenty percent of severe COVID cases are associated with type I IFN autoantibodies. These autoantibodies likely pre-exist while others arise de novo relative to SARS-CoV-2 infection. It is unclear to what extent type I anti-IFN autoantibodies are induced by SARS-CoV-2 infection and contribute to COVID-19 severity. We investigated these phenomena in those with inborn errors of immunity (IEI) and rheumatic disease (RHE). Aim(s): We aim to compare the prevalence and neutralization ability of anti-IFNalpha autoantibodies in IEI and RHE patients using archived blood samples before and after the COVID-19 pandemic began. Method(s): We determined the presence of autoantibodies against IFNalpha in plasma samples by enzyme linked immunosorbent assay in 453 patients with IEI or RHE who were testing either before or after the COVID-19 pandemic began in March 2020. Using flow cytometry, we determined the function of IFNalpha autoantibodies in plasma to block CD4T cell activation by inhibiting STAT-1 phosphorylation. Result(s): We found that 25 patients with IEI or RHE were positive for anti-IFNalpha autoantibodies. 10 out of 229 patient samples collected before the pandemic (4.2%) tested positive whereas 15 out of 224 patient samples collected after the pandemic began (7.0%) were positive. Seven of the 25 patients (28%) who tested positive had neutralizing antibodies in plasma, which prevented STAT-1 phosphorylation in CD4T cells;all of these patients had partial recombination activating gene deficiency (pRD) except for one patient with autoimmunity, leukemia and selective IgA deficiency. One pRD patient had anti-IFNalpha autoantibodies with neutralization capacity before the pandemic, which persisted after hematopoietic stem cell transplantation (HSCT) with full immune reconstitution. The patient was immunized for SARS-CoV-2 before and after HSCT and acquired COVID-19 infection a year after HSCT. The patient was symptomatic but never hospitalized and fully recovered despite having anti-IFNalpha autoantibodies. Conclusion(s): Anti-IFNalpha autoantibody levels were comparable before and after the start of the COVID-19 pandemic in IEI and RHE patients but only 28% of cases were neutralizing. The clinical implications of these autoantibodies are yet to be determined.Copyright © 2023 Elsevier Inc.

RISK OF APS AND aPLs POSITIVE PATIENTS FOR THROMBOSIS WITH COVID-19

BackgroundCoagulopathy, thromboembolic events and DIC during COVID-19 infection has been reported. Antiphospholipid antibodies (aPLs), present in 1–5 % of healthy individuals. aPLs are associated with the risk of antiphospholipid syndrome (APS) which is associated with higher risk of thrombosis.ObjectivesWe wanted to see if patients with known APS or aPLs only are at higher risk of a thrombotic event compared to control when developed COVID-19. We retrospectively review EMR for over a year for thrombotic events in patients with COVID and prior history of APS or aPLs only and matched them to control.MethodsPatient characteristics and laboratory testing were summarized according to the following groups: APS, aPLs detected or control. The control were matched according to age and gender for each group. Continuous variable were summarized as median (range) and mean (standard deviation), while categorical variables were reported as frequency (percentage). The binary patient outcome of thrombotic event, hospitalization for COVID, death, and composite event (the combined occurrence of thrombotic events, hospitalization, death) were calculated and interpreted as the multiplicative increase in odds of the given outcome for aPL group compared to control group. Multivariable logistic regression models were adjusted for potential risk factors (immobilization, hypertension, coronary artery disease, diabetes mellitus, and smoking) one at a time due to the rare occurrences of events studied.ResultsIn single variable analysis (unadjusted) the odds of the patient having a thrombotic event was approximately 27 times higher in patients with aPL only compared to Controls (P<0.001). We see similar results in multivariable analyses (adjusted) adjusting for the following variables one at a time: immobilization, hypertension, coronary artery disease, diabetes mellitus, and smoking. In each of the multivariable analyses, the adjusted odds of a thrombotic event was between approximately 24 and 29 times higher in patients with aPL Antibody Only compared to Controls (all P<0.001) indicating that association of aPL Antibody Only with thrombotic event was independent of immobilization, hypertension, coronary artery disease, diabetes, and smoking. There was no statistically significant risk of thrombosis in APS group vs control. Majority of patients with APS were on chronic anticoagulation.ConclusionWe found a statistical significantly difference in patient with aPLs only versus control regarding risk of thrombosis when developed COVID-19. No statistically significant risk was noted in patients with APS. While chronic anticoagulation in APS patients is protective it seemed that patient with aPLs only do carry a high risk of thrombosis if any inciting factors like COVID-19.References[1]C. Huang, Y. Wang, X. Li et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China, Lancet 395 (2020)[2]A. Jayarangaiah, P.T. Kariyanna, X. Chen, A. Jayarangaiah, A. Kumar, COVID-19- Associated coagulopathy: an exacerbated immunothrombosis response, Clin. Appl. Thromb. 26 (2020)[3]Y. Zhang, M. Xiao, S. Zhang et al. Coagulopathy and antiphospholipid antibodies in patients with Covid-19, N. Engl. J. Med. 382 (2020)[4]K.J. Lackner, N. Müller-Calleja, Pathogenesis of antiphospholipid syndrome: recent insights and emerging concepts, Expert Rev. Clin. Immunol. 15 (2019)Acknowledgements:NIL.Disclosure of InterestsNone Declared.

RELATION BETWEEN COVID-19 AND ANCA VASCULITIS. STUDY IN A SINGLE UNIVERSITY HOSPITAL

BackgroundAnti-neutrophil cytoplasmic antibodies (ANCA) associated vasculitis (AAV) is a small vessel vasculitis. Hallmarked by the presence of antibodies against antigens in cytoplasmic granules of neutrophils. Different microbiological agents and vaccines can trigger an AAV, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection and Coronavirus disease 2019 (COVID-19) vaccine.ObjectivesTo compare: a) proportion of positive ANCA (+ANCA) test in 2019 (COVID-19 pre-pandemic) vs 2021 (COVID-19 pandemic), b) clinical features and c) vasculitis activity between vasculitis related to COVID 19 vaccination vs non-related.MethodsAll ANCA tests performed in 2019 and 2021 in a referral hospital were reviewed. Additionally, we studied 18 +ANCA patients diagnosed in 2021 and accepted to participate in present study. The patients were divided in two groups: a) +ANCA after SARS-CoV-2 mRNA vaccine (COVID-related) and +ANCA before COVID-19 vaccine (COVID-nonrelated). Diagnosis of underlying AAV was based on ACR/EULAR 2022 criteria. Disease activity was assessed with Birmingham Vasculitis Activity Score (BVAS). ANCA testing was done by chemiluminescence assay using IO-FLASH (Inova, San Diego, CA) according to the instructions of the manufacturer.ResultsANCA tests were positive in 14 of 1287 cases (1.1%) and in 32 of 1434 (2.2%) cases in 2019 and 2021, respectively (figure 1, the differences were statistically significant (p=0.020). The main features of 18 ANCA+ patients diagnosed in 2021 are summarized in table 1. COVID-19 related patients showed a median of 7 points on BVAS score compared of the median of 5 points on BVAS score on not related patients.ConclusionThere seems to be an increase of +ANCA at the expense of anti-PR3 antibodies following the COVID-19 vaccine. In patients with +ANCA following vaccination there seems to be an increased disease activity according to BVAS score without reaching statistical significance.References[1]Damoiseaux, J., et al Autoimmunity Reviews.2021. PMID 34896650.[2]Irure-Ventura, et al. IScience.2022. PMID 35937087.Table 1.Main general features of 18 patients with ANCA+ test diagnosed in 2021.FEATURESAll cases n= 18Related n= 13Non-related n= 5p*Age (years), mean±SD62±1767±15.352±16.50.167Male/ Female n, (% male)10/8 (55.6)9/4 (69.2%)1/4(20)0.067ANCA-test specificity, n (%)MPO-ANCA9 (50)7 (53.8)2(40)0.609PR3-ANCA8 (44.4)5 (38.5)3(60)0.423Both1 (5.6)1 (7.7)0-CRP (mg/dL), median [IQR]2,4 [0.4-10.7]3.8 [0.4-10.1]1 [0.4-10.9]0.802ESR, mm/1st hours, median [IQR]50 [25-104]47 [25.3-71.8]50 [25-120]0.634BVAS, median [IQR]6.5 [4.2-8]7 [4-8]5 [5-8]0.842FFS, n (%)03 (16.7)2 (15.4)1 (20)0.819≥115 (83.3)11 (84.6)4 (80)0.819ENT involvement, n (%)12(66.7)10 (76.9)2 (40)0.148MSK involvement, n (%)11(61.1)7(53.8)4 (80)0.322CNS/PNS involvement, n (%)10 (55.6)7 (53.8)3 (60)0.819Lung involvement, n (%)9 (50)6 (46.2)3 (60)0.609Kidney involvement, n (%)8 (44.4)7 (53.8)1 (40)0.208Ocular involvement, n (%)2 (11.1)2 (15.4)00.366Cutaneous involvement, n (%)2 (11.1)02 (40)0.019*p values according to Man Whitney test.Abbreviations (in alphabetical order):AAV: anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis;ACR: American college of Rheumatology;ANCA: Antineutrophil cytoplasmic antibody;BVAS: Birmingham Vasculitis Activity Score;CNS: central nervous system;CRP: C-Reactive protein;dL: deciliter;ENT: ear, nose, throat;ESR: erythrocyte sedimentation rate;FFS: Five-Factors Score;g;IQR: Interquartile range;mg: milligram;MSK: musculoskeletal;MPO-ANCA= ANCA specific for myeloperoxidase;n=Number;PNS: peripheral nervous system;PR3-ANCA= ANCA specific for proteinase 3;SD: Standard DeviationFigure 1.Comparison of ANCA test in 2019 and 2021.[Figure omitted. See PDF]Acknowledgements:NIL.Disclosure of InterestsFabricio Benavides-Villanueva: None declared, Vanesa Calvo-Río Speakers bureau: Dra V. Calvo had participation in company-sponsored speaker´s bureau from Roche, Novartis, Galápagos, UCB Pharma, MSD, Celgene, and Grünenthal and received support for attending m etings and/or travel from Janssen, Abbvie, Roche, Novartis, MSD, UCB Pharma, Celgene, Lilly, Pfizer, Galápagos., J. Loricera Speakers bureau: Dr. J. Loricera had participation in company-sponsored speaker´s bureau from Roche, Novartis, Galápagos, UCB Pharma, MSD, Celgene, and Grünenthal., Consultant of: Dr. J. Loricera had consultation fees in company-sponsored speaker´s bureau from Roche, Novartis, Galápagos, UCB Pharma, MSD, Celgene, and Grünenthal and received support for attending meetings and/or travel from Janssen, Abbvie, Roche, Novartis, MSD, UCB Pharma, Celgene, Lilly, Pfizer, Galápagos., Juan Irure-Ventura: None declared, Marcos Lopez-Hoyos: None declared, Ricardo Blanco Speakers bureau: Dr. R. Blanco had participation in company sponsored speaker´s bureau from Abbvie, Pfizer, Roche, Bristol-Myers, Janssen, Lilly and MSD., Consultant of: Dr. R. Blanco had consultation from Abbvie, Pfizer, Roche, Bristol-Myers, Janssen, Lilly and MSD., Grant/research support from: Dr. R. Blanco received grants/research supports from Abbvie, MSD and Roche.

Autoantibodies Neutralizing Type III Interferons Are Uncommon in Patients with Severe Coronavirus Disease 2019 Pneumonia.

Autoantibodies (AABs) neutralizing type I interferons (IFN) underlie about 15% of cases of critical coronavirus disease 2019 (COVID-19) pneumonia. The impact of autoimmunity toward type III IFNs remains unexplored. We included samples from 1,002 patients with COVID-19 (50% with severe disease) and 1,489 SARS-CoV-2-naive individuals. We studied the prevalence and neutralizing capacity of AABs toward IFNλ and IFNα. Luciferase-based immunoprecipitation method was applied using pooled IFNα (subtypes 1, 2, 8, and 21) or pooled IFNλ1-IFNλ3 as antigens, followed by reporter cell-based neutralization assay. In the SARS-CoV-2-naive cohort, IFNλ AABs were more common (8.5%) than those targeting IFNα2 (2.9%) and were related with older age. In the COVID-19 cohort the presence of autoreactivity to IFNλ did not associate with severe disease [odds ratio (OR) 0.84; 95% confidence interval (CI) 0.40-1.73], unlike to IFNα (OR 4.88; 95% CI 2.40-11.06; P < 0.001). Most IFNλ AAB-positive COVID-19 samples (67%) did not neutralize any of the 3 IFNλ subtypes. Pan-IFNλ neutralization occurred in 5 patients (0.50%), who all suffered from severe COVID-19 pneumonia, and 4 of them neutralized IFNα2 in addition to IFNλ. Overall, AABs to type III IFNs are rarely neutralizing, and do not seem to predispose to severe COVID-19 pneumonia on their own.

Autoantibodies to Interferons in Infectious Diseases.

Anti-cytokine autoantibodies and, in particular, anti-type I interferons are increasingly described in association with immunodeficient, autoimmune, and immune-dysregulated conditions. Their presence in otherwise healthy individuals may result in a phenotype characterized by a predisposition to infections with several agents. For instance, anti-type I interferon autoantibodies are implicated in Coronavirus Disease 19 (COVID-19) pathogenesis and found preferentially in patients with critical disease. However, autoantibodies were also described in the serum of patients with viral, bacterial, and fungal infections not associated with COVID-19. In this review, we provide an overview of anti-cytokine autoantibodies identified to date and their clinical associations; we also discuss whether they can act as enemies or friends, i.e., are capable of acting in a beneficial or harmful way, and if they may be linked to gender or immunosenescence. Understanding the mechanisms underlying the production of autoantibodies could improve the approach to treating some infections, focusing not only on pathogens, but also on the possibility of a low degree of autoimmunity in patients.

Post-Acute COVID-19 Joint Pain and New Onset of Rheumatic Musculoskeletal Diseases: A Systematic Review.

As the number of reports of post-acute COVID-19 musculoskeletal manifestations is rapidly rising, it is important to summarize the current available literature in order to shed light on this new and not fully understood phenomenon. Therefore, we conducted a systematic review to provide an updated picture of post-acute COVID-19 musculoskeletal manifestations of potential rheumatological interest, with a particular focus on joint pain, new onset of rheumatic musculoskeletal diseases and presence of autoantibodies related to inflammatory arthritis such as rheumatoid factor and anti-citrullinated protein antibodies. We included 54 original papers in our systematic review. The prevalence of arthralgia was found to range from 2% to 65% within a time frame varying from 4 weeks to 12 months after acute SARS-CoV-2 infection. Inflammatory arthritis was also reported with various clinical phenotypes such as symmetrical polyarthritis with RA-like pattern similar to other prototypical viral arthritis, polymyalgia-like symptoms, or acute monoarthritis and oligoarthritis of large joints resembling reactive arthritis. Moreover, high figures of post-COVID-19 patients fulfilling the classification criteria for fibromyalgia were found, ranging from 31% to 40%. Finally, the available literature about prevalence of rheumatoid factor and anti-citrullinated protein antibodies was largely inconsistent. In conclusion, manifestations of rheumatological interest such as joint pain, new-onset inflammatory arthritis and fibromyalgia are frequently reported after COVID-19, highlighting the potential role of SARS-CoV-2 as a trigger for the development of autoimmune conditions and rheumatic musculoskeletal diseases.

The chemokine landscape: one system multiple shades.

Leukocyte trafficking is mainly governed by chemokines, chemotactic cytokines, which can be concomitantly produced in tissues during homeostatic conditions or inflammation. After the discovery and characterization of the individual chemokines, we and others have shown that they present additional properties. The first discoveries demonstrated that some chemokines act as natural antagonists on chemokine receptors, and prevent infiltration of leukocyte subsets in tissues. Later on it was shown that they can exert a repulsive effect on selective cell types, or synergize with other chemokines and inflammatory mediators to enhance chemokine receptors activities. The relevance of the fine-tuning modulation has been demonstrated in vivo in a multitude of processes, spanning from chronic inflammation to tissue regeneration, while its role in the tumor microenvironment needs further investigation. Moreover, naturally occurring autoantibodies targeting chemokines were found in tumors and autoimmune diseases. More recently in SARS-CoV-2 infection, the presence of several autoantibodies neutralizing chemokine activities distinguished disease severity, and they were shown to be beneficial, protecting from long-term sequelae. Here, we review the additional properties of chemokines that influence cell recruitment and activities. We believe these features need to be taken into account when designing novel therapeutic strategies targeting immunological disorders.

SARS-CoV-2 Positive Serology and Islet Autoantibodies in Newly Diagnosed Pediatric Cases of Type 1 Diabetes Mellitus: A Single-Center Cohort Study.

Acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, although presenting less severe forms of the disease in children, seems to play a role in the development of other conditions, including type 1 diabetes mellitus (T1DM). After the beginning of the pandemic, an increase in the number of T1DM pediatric patients was observed in several countries, thus leading to many questions about the complex relationship between SARS-CoV-2 infection and T1DM. Our study aimed to highlight possible correlations between SARS-CoV-2 serology and T1DM onset. Therefore, we performed an observational retrospective cohort study that included 158 children diagnosed with T1DM in the period April 2021-April 2022. The presence or absence of SARS-CoV-2 and T1DM-specific antibodies and other laboratory findings were assessed. In the group of patients with positive SARS-CoV-2 serology, a higher percentage had detectable IA-2A antibodies, more children were positive for all three islet autoantibodies determined (GADA, ICA, and IA-2A), and a higher mean HbA1c value was found. No difference existed between the two groups regarding DKA presence and severity. A lower C-peptide level was found in the patients presenting diabetic ketoacidosis (DKA) at T1DM onset. When compared to a group of patients diagnosed before the pandemic, an increased incidence of both DKA and severe DKA, as well as a higher age at diagnosis and higher levels of HbA1c were present in our study group. These findings have important implications for the ongoing monitoring and management of children with T1DM after the COVID-19 pandemic and highlight the need for further research to better understand the complex relationship between SARS-CoV-2 infection and T1DM.

Impact of SARS-CoV2 infection on anti-apolipoprotein A-1 IgG response in inflammatory rheumatic diseases.

Objectives: To investigate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection on anti-apolipoprotein A-1 IgG (AAA1) humoral response in immunosuppressed inflammatory rheumatic diseases (IRD) patients. Methods: This is a nested cohort study from the prospective Swiss Clinical Quality Management registry. A total of 368 IRD patients for which serum samples were available before and after the SARS-CoV2 pandemic were included. Autoantibodies against ApoA-1 (AAA1) and its c-terminal region (AF3L1) were measured in both samples. The exposure of interest was anti-SARS-CoV2 spike subunit 1 (S1) seropositivity measured in the second sample. The effect of SARS-CoV2 infection (anti-S1 seropositivity) on becoming AAA1 or AF3L1 positive and on the change of AAA1 or AF3L1 optical density (OD) between the two samples was tested with multivariable regressions. Results: There were 12 out of 368 IRD patients who were seroconverted against S1. The proportion of patients becoming AF3L1 seropositive was significantly higher in anti-S1-positive patients, compared with anti-S1-negative patients (66.7% versus 21.6%, p = 0.001). Adjusted logistic regression analyses indicated that anti-S1 seroconversion was associated with a sevenfold increased risk of AFL1 seropositivity (odds ratio: 7.4, 95% confidence interval (95% CI): 2.1-25.9) and predicted median increase in AF3L1 OD values (+0.17, 95% CI: 0.08-0.26). Conclusions: SARS-CoV2 infection is associated with a marked humoral response against the immunodominant c-terminal region of ApoA-1 in IRD patients. The possible clinical impact of AAA1 and AF3L1 antibodies on disease progression, cardiovascular complications, or long COVID syndrome deserves future investigations.

Autoantibodies against type I interferons in COVID-19 infection: A systematic review and meta-analysis.

OBJECTIVES: In this study, we aimed to study the rate of autoantibodies against type I interferons (IFNs) in patients with COVID-19 and analyze its dependence on severity of infection and some other variables. METHODS: A systemic review with the search terms: "COVID-19" or "SARS-CoV-2" and "autoantibodies" or "autoantibody" and "IFN" or "interferon" for the period 20 December 2019 to 15 August 2022 was carried out using PubMed, Embase, Cochrane, and Web of Science. R 4.2.1 software was used for meta-analysis of the published results. Pooled risk ratios and 95% confidence intervals (CIs) were calculated. RESULTS: We identified eight studies involving 7729 patients, of whom 5097 (66%) had severe COVID-19 and 2632 (34%) had mild or moderate symptoms. The positive rate of anti-type-I-IFN-autoantibodies in the total dataset was 5% (95% CI, 3-8%), but reached 10% (95% CI, 7-14%) in those with severe infection. The most common subtypes were anti-IFN-α (89%) and anti-IFN-ω (77%). The overall prevalence in male patients was 5% (95% CI, 4-6%), and in female patients 2% (95% CI, 1-3%). CONCLUSION: Severe COVID-19 is associated with high rates of autoantibodies against type-I-IFN and more so in male than female patients.

Immune and Hereditary Thrombotic Thrombocytopenic Purpura: Can ADAMTS13 Deficiency Alone Explain the Different Clinical Phenotypes?

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy caused by a hereditary or immune-mediated deficiency of the enzyme ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13). TTPs are caused by the following pathophysiological mechanisms: (1) the presence of inhibitory autoantibodies against ADAMTS13; and (2) hereditary mutations of the ADAMTS13 gene, which is present on chromosome 9. In both syndromes, TTP results from a severe deficiency of ADAMTS13, which is responsible for the impaired proteolytic processing of high-molecular-weight von Willebrand factor (HMW-VWF) multimers, which avidly interact with platelets and subendothelial collagen and promote tissue and multiorgan ischemia. Although the acute presentation of the occurring symptoms in acquired and hereditary TTPs is similar (microangiopathic hemolytic anemia, thrombocytopenia, and variable ischemic end-organ injury), their intensity, incidence, and precipitating factors are different, although, in both forms, a severe ADAMTS13 deficiency characterizes their physiopathology. This review is aimed at exploring the possible factors responsible for the different clinical and pathological features occurring in hereditary and immune-mediated TTPs.

Autoantibodies during infectious diseases: Lessons from malaria applied to COVID-19 and other infections.

Autoimmunity is a common phenomenon reported in many globally relevant infections, including malaria and COVID-19. These and other highly inflammatory diseases have been associated with the presence of autoantibodies. The role that these autoantibodies play during infection has been an emerging topic of interest. The vast numbers of studies reporting a range of autoantibodies targeting cellular antigens, such as dsDNA and lipids, but also immune molecules, such as cytokines, during malaria, COVID-19 and other infections, underscore the importance that autoimmunity can play during infection. During both malaria and COVID-19, the presence of autoantibodies has been correlated with associated pathologies such as malarial anemia and severe COVID-19. Additionally, high levels of Atypical/Autoimmune B cells (ABCs and atypical B cells) have been observed in both diseases. The growing literature of autoimmune B cells, age-associated B cells and atypical B cells in Systemic Lupus erythematosus (SLE) and other autoimmune disorders has identified recent mechanistic and cellular targets that could explain the development of autoantibodies during infection. These new findings establish a link between immune responses during infection and autoimmune disorders, highlighting shared mechanistic insights. In this review, we focus on the recent evidence of autoantibody generation during malaria and other infectious diseases and their potential pathological role, exploring possible mechanisms that may explain the development of autoimmunity during infections.