PSGL-1, ADAM8, and selectins as potential biomarkers in the diagnostic process of systemic lupus erythematosus and systemic sclerosis: an observational study.

Background: Early diagnosis and treatment of Systemic lupus erythematosus (SLE) and Systemic sclerosis (SSc) present significant challenges for clinicians. Although various studies have observed changes in serum levels of selectins between healthy donors and patients with autoimmune diseases, including SLE and SSc, their potential as biomarkers has not been thoroughly explored. We aimed to investigate serum profiles of PSGL-1 (sPSGL-1), ADAM8 (sADAM8) and P-, E- and L-selectins (sP-, sE- and sL-selectins) in defined SLE and SSc patient cohorts to identify disease-associated molecular patterns. Methods: We collected blood samples from 64 SLE patients, 58 SSc patients, and 81 healthy donors (HD). Levels of sPSGL-1, sADAM8 and selectins were analyzed by ELISA and leukocyte membrane expression of L-selectin and ADAM8 by flow cytometry. Results: Compared to HD, SLE and SSc patients exhibited elevated sE-selectin and reduced sL-selectin levels. Additionally, SLE patients exhibited elevated sPSGL-1 and sADAM8 levels. Compared to SSc, SLE patients had decreased sL-selectin and increased sADAM8 levels. Furthermore, L-selectin membrane expression was lower in SLE and SSc leukocytes than in HD leukocytes, and ADAM8 membrane expression was lower in SLE neutrophils compared to SSc neutrophils. These alterations associated with some clinical characteristics of each disease. Using logistic regression analysis, the sL-selectin/sADAM8 ratio in SLE, and a combination of sL-selectin/sE-selectin and sE-selectin/sPSGL-1 ratios in SSc were identified and cross-validated as potential serum markers to discriminate these patients from HD. Compared to available diagnostic biomarkers for each disease, both sL-selectin/sADAM8 ratio for SLE and combined ratios for SSc provided higher sensitivity (98% SLE and and 67% SSc correctly classified patients). Importantly, the sADAM8/% ADAM8(+) neutrophils ratio discriminated between SSc and SLE patients with the same sensitivity and specificity than current disease-specific biomarkers. Conclusion: SLE and SSc present specific profiles of sPSGL-1, sE-, sL-selectins, sADAM8 and neutrophil membrane expression which are potentially relevant to their pathogenesis and might aid in their early diagnosis.

Regulation of Monocyte Apoptosis and DNA Extrusion in Monocyte Extracellular Traps by PSGL-1: Relevance in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease characterized by severe organ damage and lacking curative treatment. While various immune cell types, especially dysfunctional B and T cells and neutrophils, have been related with disease pathogenesis, limited research has focused on the role of monocytes in SLE. Increased DNA extracellular traps, apoptosis and necrosis have been related to lupus pathogenesis. Our goal is to analyze the contribution of P-selectin glycoprotein ligand 1 (PSGL-1) in SLE monocytes to disease pathogenesis by investigating the control exerted by PSGL-1 on monocyte apoptosis and DNA extrusion in extracellular traps (METs). Monocytes from active disease patients (aSLE) exhibited reduced levels of PSGL-1. Importantly, lower PSGL-1 levels in SLE monocytes associated with several clinical characteristics, including anti-dsDNA autoantibodies, lupus anticoagulant, clinical lung involvement, and anemia. Monocytes from SLE patients showed higher susceptibility to apoptosis than healthy donors (HD) monocytes and PSGL-1/P-selectin interaction decreased secondary necrosis in HD but not in aSLE monocytes. Regarding METs, aSLE monocytes exhibited higher susceptibility to generate METs than HD monocytes. The interaction of HD monocytes with P-selectin induced Syk activation and reduced the levels of DNA extruded in METs. However, in aSLE monocytes, PSGL-1/P-selectin interaction did not activate Syk or reduce the amount of extruded DNA. Our data suggest a dysfunctional PSGL-1/P-selectin axis in aSLE monocytes, unable to reduce secondary necrosis or the amount of DNA released into the extracellular medium in METs, potentially contributing to lupus pathogenesis.

Effectiveness and Safety of the COVID-19 Vaccine in Patients with Rheumatoid Arthritis in a Real-World Setting.

Novel mechanisms of COVID-19 vaccines raised concern about their potential immunogenicity in patients with rheumatoid arthritis (RA) undergoing immunomodulatory treatments. We designed a retrospective single-center study to investigate their effectiveness and safety in this population, analyzing data from the first vaccination program (December 2020-October 2021). Inclusion criteria were availability of post-vaccination serology and a minimum subsequent follow-up of 6 months. Binding antibody units (BAU/mL) ≥ 7.1 defined an adequate serological response. Post-vaccine COVID-19 incidence and its timing since vaccination, adverse events (AEs), and RA flares were recorded. Adjusted logistic and linear multivariate regression analyses were carried out to identify factors associated with vaccine response. We included 118 patients (87.2% women, age 65.4 ± 11.6 years, evolution 12.0 ± 9.6 years), of whom 95.8% had a complete vaccination schedule. Adequate humoral immunogenicity was achieved in 88.1% of patients and was associated with previous COVID-19 and mRNA vaccines, whereas smoking, aCCP, age, and DMARDs exerted a negative impact. Post-vaccine COVID-19 occurred in 18.6% of patients, a median of 6.5 months after vaccination. Vaccine AE (19.5%) and RA flares (1.7%) were mostly mild and inversely associated with age. Our results suggest that COVID-19 vaccines induce adequate humoral immunogenicity, with an acceptable safety profile in RA patients.

NFκB and NLRP3/NLRC4 inflammasomes regulate differentiation, activation and functional properties of monocytes in response to distinct SARS-CoV-2 proteins.

Increased recruitment of transitional and non-classical monocytes in the lung during SARS-CoV-2 infection is associated with COVID-19 severity. However, whether specific innate sensors mediate the activation or differentiation of monocytes in response to different SARS-CoV-2 proteins remain poorly characterized. Here, we show that SARS-CoV-2 Spike 1 but not nucleoprotein induce differentiation of monocytes into transitional or non-classical subsets from both peripheral blood and COVID-19 bronchoalveolar lavage samples in a NFκB-dependent manner, but this process does not require inflammasome activation. However, NLRP3 and NLRC4 differentially regulated CD86 expression in monocytes in response to Spike 1 and Nucleoprotein, respectively. Moreover, monocytes exposed to Spike 1 induce significantly higher proportions of Th1 and Th17 CD4 + T cells. In contrast, monocytes exposed to Nucleoprotein reduce the degranulation of CD8 + T cells from severe COVID-19 patients. Our study provides insights in the differential impact of innate sensors in regulating monocytes in response to different SARS-CoV-2 proteins, which might be useful to better understand COVID-19 immunopathology and identify therapeutic targets.

Beneficial effect of temporary methotrexate interruption on B and T cell responses upon SARS-CoV-2 vaccination in patients with rheumatoid arthritis or psoriatic arthritis.

B and T cell responses were evaluated in patients with rheumatoid arthritis (RA) or psoriatic arthritis (PsA) after 1 or 2 weeks of methotrexate (MTX) withdrawal following each COVID-19 vaccine dose and compared with those who maintained MTX. Adult RA and PsA patients treated with MTX were recruited and randomly assigned to 3 groups: MTX-maintenance (n = 72), MTX-withdrawal for 1 week (n = 71) or MTX-withdrawal for 2 weeks (n = 73). Specific antibodies to several SARS-CoV-2 antigens and interferon (IFN)-γ and interleukin (IL)-21 responses were assessed. MTX withdrawal in patients without previous COVID-19 was associated with higher levels of anti-RBD IgG and neutralising antibodies, especially in the 2-week withdrawal group and with higher IFN-γ secretion upon stimulation with pools of SARS-CoV-2 S peptides. No increment of RA/PsA relapses was detected across groups. Our data indicate that two-week MTX interruption following COVID-19 vaccination in patients with RA or PsA improves humoral and cellular immune responses.

Single-cell multi-omics analysis of COVID-19 patients with pre-existing autoimmune diseases shows aberrant immune responses to infection.

In COVID-19, hyperinflammatory and dysregulated immune responses contribute to severity. Patients with pre-existing autoimmune conditions can therefore be at increased risk of severe COVID-19 and/or associated sequelae, yet SARS-CoV-2 infection in this group has been little studied. Here, we performed single-cell analysis of peripheral blood mononuclear cells from patients with three major autoimmune diseases (rheumatoid arthritis, psoriasis, or multiple sclerosis) during SARS-CoV-2 infection. We observed compositional differences between the autoimmune disease groups coupled with altered patterns of gene expression, transcription factor activity, and cell-cell communication that substantially shape the immune response under SARS-CoV-2 infection. While enrichment of HLA-DRlow CD14+ monocytes was observed in all three autoimmune disease groups, type-I interferon signaling as well as inflammatory T cell and monocyte responses varied widely between the three groups of patients. Our results reveal disturbed immune responses to SARS-CoV-2 in patients with pre-existing autoimmunity, highlighting important considerations for disease treatment and follow-up.

Occurrence of SARS-CoV-2 viremia is associated with genetic variants of genes related to COVID-19 pathogenesis.

Introduction: SARS-CoV-2 viral load has been related to COVID-19 severity. The main aim of this study was to evaluate the relationship between SARS-CoV-2 viremia and SNPs in genes previously studied by our group as predictors of COVID-19 severity. Materials and methods: Retrospective observational study including 340 patients hospitalized for COVID-19 in the University Hospital La Princesa between March 2020 and December 2021, with at least one viremia determination. Positive viremia was considered when viral load was above the quantifiable threshold (20 copies/ml). A total of 38 SNPs were genotyped. To study their association with viremia a multivariate logistic regression was performed. Results: The mean age of the studied population was 64.5 years (SD 16.6), 60.9% patients were male and 79.4% white non-Hispanic. Only 126 patients (37.1%) had at least one positive viremia. After adjustment by confounders, the presence of the minor alleles of rs2071746 (HMOX1; T/T genotype OR 9.9 p < 0.0001), rs78958998 (probably associated with SERPING1 expression; A/T genotype OR 2.3, p = 0.04 and T/T genotype OR 12.9, p < 0.0001), and rs713400 (eQTL for TMPRSS2; C/T + T/T genotype OR 1.86, p = 0.10) were associated with higher risk of viremia, whereas the minor alleles of rs11052877 (CD69; A/G genotype OR 0.5, p = 0.04 and G/G genotype OR 0.3, p = 0.01), rs2660 (OAS1; A/G genotype OR 0.6, p = 0.08), rs896 (VIPR1; T/T genotype OR 0.4, p = 0.02) and rs33980500 (TRAF3IP2; C/T + T/T genotype OR 0.3, p = 0.01) were associated with lower risk of viremia. Conclusion: Genetic variants in HMOX1 (rs2071746), SERPING1 (rs78958998), TMPRSS2 (rs713400), CD69 (rs11052877), TRAF3IP2 (rs33980500), OAS1 (rs2660) and VIPR1 (rs896) could explain heterogeneity in SARS-CoV-2 viremia in our population.

Low P-Selectin Glycoprotein Ligand-1 Expression in Neutrophils Associates with Disease Activity and Deregulated NET Formation in Systemic Lupus Erythematosus.

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by the generation of anti-DNA autoantibodies due to exposure of immune cells to excessive amounts of extracellular DNA. Lack of P-selectin in mice induces the development of a lupus-like syndrome and patients with cutaneous lupus have reduced P-selectin expression in skin vessels. Using flow cytometry we analyzed in healthy donors and patients the expression of P-selectin Glycoprotein Ligand-1 (PSGL-1) in circulating neutrophils and the implication of PSGL-1/P-selectin interaction in neutrophil extracellular traps (NETs) generation. We found a statistical significance that neutrophils from active SLE patients have a reduced expression of PSGL-1 and low levels of PSGL-1 in neutrophils from SLE patients associated with the presence of anti-dsDNA antibodies, clinical lung involvement, Raynaud's phenomenon, and positive lupus anticoagulant. PSGL-1 is present along the DNA in the NET. In healthy donors, neutrophil interaction with immobilized P-selectin triggers Syk activation, increases the NETs percentage and reduces the amount of DNA extruded in the NETs. In active SLE patients, neutrophil interaction with P-selectin does not activate Syk or reduce the amount of DNA extruded in the NETs, that might contribute to increase the extracellular level of DNA and hence, to disease pathogenesis.

Difficult-to-treat rheumatoid arthritis (D2T RA): clinical issues at early stages of disease.

OBJECTIVES: Most studies on difficult-to-treat rheumatoid arthritis (D2T RA) have focused on established RA. Here, we analyse whether disease activity in the early stages of RA could influence progression to a D2T RA under real-life conditions. Other clinical and treatment-related factors were also analysed. METHODS: A longitudinal multicentre study of patients with RA was conducted from 2009 to 2018. Patients were followed up until January 2021. D2T RA was defined based on EULAR criteria (treatment failure, signs suggestive of currently active/progressive disease and management being perceived as problematic by the rheumatologist and/or patient). The main variable was disease activity in the early stages. The covariates were sociodemographic, clinical and treatment-related factors. We ran a multivariable logistic regression analysis to investigate risk factors associated with progression to D2T RA. RESULTS: The study population comprised 631 patients and 35 (5.87%) developed D2T RA. At the time of diagnosis, the D2T RA group were younger, with a higher disability, 28-joint Disease Activity Score (DAS28) score, tender joint count and pain scores. In our final model, DAS28 was not statistically significantly associated with D2T RA. No differences were found between groups for therapy. Disability was independently associated with D2T RA (OR: 1.89; p=0.01). CONCLUSIONS: In this cohort of patients newly diagnosed with RA, our results do not allow us to prove the influence of active disease according to DAS28. However, we did find that younger patients and those with elevated initial disability scores are more likely to develop D2T RA regardless of other factors.

Galectin-1: A Potential Biomarker Differentiating between Early Rheumatoid Arthritis and Spondyloarthritis.

Galectin-1 (Gal1) plays a regulatory role in the immune system. We have recently validated that Gal1 serum (sGal1) levels are increased in rheumatoid arthritis (RA) patients compared to healthy donors (HDs); however, there is no information on Gal1 in spondyloarthritis (SpA). Objective: To compare Gal1 levels in patients with SpA versus RA as a diagnostic biomarker. Methods: We studied sGal1 levels in HD (n = 52), SpA (n = 80) and RA patients (n = 64) who were randomly divided into discovery and validation sets. Synovial fluid (SF) from osteoarthritis (OA) (n = 28), peripheral SpA (n = 28) and RA (n = 28) were studied. In SpA patients, we analyzed the association between clinical parameters and sGal1 levels. Results: sGal1 levels were significantly lower in patients with SpA with respect to RA and similar to those of the HD. A cut-off of 20.50 ng/mL (sGal1) allowed one to differentiate RA patients from SpA and HD (Odd Ratio (OR) 8.23 and 12.64, respectively). Gal1 SF levels in SpA were slightly lower than OA patients and significantly lower than RA patients. No correlation was observed between sGal1 levels and clinical parameters in SpA patients. Conclusion: Gal1 could act as a diagnostic biomarker of RA and would allow one to distinguish SpA and RA patients.

NLRC4-mediated activation of CD1c+ DC contributes to perpetuation of synovitis in rheumatoid arthritis.

The individual contribution of specific myeloid subsets such as CD1c+ conventional DC (cDC) to perpetuation of rheumatoid arthritis (RA) pathology remains unclear. In addition, the specific innate sensors driving pathogenic activation of CD1c+ cDC in patients with RA and their functional implications have not been characterized. Here, we assessed phenotypical, transcriptional, and functional characteristics of CD1c+ and CD141+ cDC and monocytes from the blood and synovial fluid of patients with RA. Increased levels of CCR2 and the IgG receptor CD64 on circulating CD1c+ cDC was associated with the presence of this DC subset in the synovial membrane in patients with RA. Moreover, synovial CD1c+ cDC are characterized by increased expression of proinflammatory cytokines and high abilities to induce pathogenic IFN-γ+IL-17+CD4+ T cells in vitro. Finally, we identified the crosstalk between Fcγ receptors and NLRC4 as a potential molecular mechanism mediating pathogenic activation, CD64 upregulation, and functional specialization of CD1c+ cDC in response to dsDNA-IgG in patients with RA.

VIP/VPAC Axis Expression in Immune-Mediated Inflammatory Disorders: Associated miRNA Signatures.

Few studies have considered immune-mediated inflammatory disorders (IMID) together, which is necessary to adequately understand them given they share common mechanisms. Our goal was to investigate the expression of vasoactive intestinal peptide (VIP) and its receptors VPAC1 and VPAC2 in selected IMID, analyze the effect of biological therapies on them, and identify miRNA signatures associated with their expression. Serum VIP levels and mRNA of VPAC and miRNA expression in peripheral blood mononuclear cells were analyzed from 52 patients with psoriasis, rheumatoid arthritis, Graves' disease, or spondyloarthritis and from 38 healthy subjects. IMID patients showed higher levels of VIP and increased expression of VPAC2 compared to controls (p < 0.0001 and p < 0.0192, respectively). Receiver operating characteristic curve analysis showed that the levels of VIP or VPAC2 expression were adequate discriminators capable of identifying IMID. Treatment of IMID patients with anti-TNFα and anti-IL12/23 significantly affected serum VIP levels. We identified miRNA signatures associated with levels of serum VIP and VPAC2 expression, which correlated with IMID diagnosis of the patients. The results indicate that the expression of VIP/VPAC2 is able of identify IMIDs and open up a line of research based on the association between the VIP/VPAC axis and miRNA signatures in immune-mediated diseases.

Anti-Citrullinated Protein Antibody Titers Are Independently Modulated by Both Disease Activity and Conventional or Biologic Anti-Rheumatic Drugs.

This study aimed to analyze the factors that influence anti-citrullinated protein antibody (ACPA) titers in a seropositive early arthritis (EA) population under non-protocolized treatment with disease-modifying anti-rheumatic drugs (DMARDs). A total of 130 ACPA-positive patients from the PEARL (Princesa Early Arthritis Longitudinal) study were studied along a 5-year follow-up. Sociodemographic, clinical, and therapeutic variables, along with serum samples, were collected at five visits by protocol. Anti-cyclic citrullinated peptide 2 (CCP2) ACPA titers were measured by ELISA. The effect of different variables on anti-CCP2 titers was estimated using longitudinal multivariate analysis models, nested by visit and patient. Data from 471 visits in 130 patients were analyzed. A significant decrease in anti-CCP2 titers was observed at all time-points, compared to baseline, following the decline of disease activity. In the multivariate analysis, active or ever smoking was significantly associated with the highest anti-CCP2 titers while reduction in disease activity was associated with titer decline. After adjusting for these variables, both conventional synthetic (cs) and biologic (b) DMARDs accounted for the decline in anti-CCP2 titers as independent factors. Conclusion: In patients with EA, an early and sustained reduction in ACPA titers can be detected associated with the decline in disease activity, irrespective of the treatment used.

Relevant SARS-CoV-2 viremia is associated with COVID-19 severity: Prospective cohort study and validation cohort.

Early kinetics of SARS-CoV-2 viral load (VL) in plasma determined by quantitative reverse-transcription polymerase chain reaction (RT-PCR) was evaluated as a predictor of poor clinical outcome in a prospective study and assessed in a retrospective validation cohort. Prospective observational single-center study including consecutive adult patients hospitalized with COVID-19 between November 2020 and January 2021. Serial plasma samples were obtained until discharge. Quantitative RT-PCR was performed to assess SARS-CoV-2 VL. The main outcomes were in-hospital mortality, admission to the Intensive Care Unit (ICU), and their combination (Poor Outcome). Relevant viremia (RV), established in the prospective study, was assessed in a retrospective cohort including hospitalized COVID-19 patients from April 2021 to May 2022, in which plasma samples were collected according to clinical criteria. Prospective cohort: 57 patients were included. RV was defined as at least a twofold increase in VL within ≤2 days or a VL > 300 copies/ml, in the first week. Patients with RV (N = 14; 24.6%) were more likely to die than those without RV (35.7% vs. 0%), needed ICU admission (57% vs. 0%) or had Poor Outcome (71.4% vs. 0%), (p < 0.001 for the three variables). Retrospective cohort: 326 patients were included, 18.7% presented RV. Patients with RV compared with patients without RV had higher rates of ICU-admission (odds ratio [OR]: 5.6 [95% confidence interval [CI]: 2.1-15.1); p = 0.001), mortality (OR: 13.5 [95% CI: 6.3-28.7]; p < 0.0001) and Poor Outcome (OR: 11.2 [95% CI: 5.8-22]; p < 0.0001). Relevant SARS-CoV-2 viremia in the first week of hospitalization was associated with higher in-hospital mortality, ICU admission, and Poor Outcome. Findings observed in the prospective cohort were confirmed in a larger validation cohort.

Genetic LGALS1 Variants Are Associated with Heterogeneity in Galectin-1 Serum Levels in Patients with Early Arthritis.

Galectin 1 (Gal1) exerts immunomodulatory effects leading to therapeutic effects in autoimmune animal models. Patients with rheumatoid arthritis have been reported to show higher Gal1 serum levels than the healthy population. Our study aimed to find genetic variants on the Gal1 gene (LGALS1) modulating its expression and/or clinical features in patients with early arthritis (EA). LGALS1 was sequenced in 53 EA patients to characterize all genetic variants. Then, we genotyped rs9622682, rs929039, and rs4820293, which covered the main genetic variation in LGALS1, in 532 EA patients. Gal1 and IL-6 serum levels were measured by ELISA and Gal1 also by western blot (WB) in lymphocytes from patients with specific genotypes. Once disease activity improved with treatment, patients with at least one copy of the minor allele in rs9622682 and rs929039 or those with GG genotype in rs4820293 showed significantly higher Gal1 serum levels (p < 0.05). These genotypic combinations were also associated with higher Gal1 expression in lymphocytes by WB and lower IL-6 serum levels in EA patients. In summary, our study suggests that genetic variants studied in LGALS1 can explain heterogeneity in Gal1 serum levels showing that patients with higher Gal1 levels have lower serum IL-6 levels.

SARS-CoV-2 Viremia Precedes an IL6 Response in Severe COVID-19 Patients: Results of a Longitudinal Prospective Cohort.

Background: Interleukin 6 (IL6) levels and SARS-CoV-2 viremia have been correlated with COVID-19 severity. The association over time between them has not been assessed in a prospective cohort. Our aim was to evaluate the relationship between SARS-CoV-2 viremia and time evolution of IL6 levels in a COVID-19 prospective cohort. Methods: Secondary analysis from a prospective cohort including COVID-19 hospitalized patients from Hospital Universitario La Princesa between November 2020 and January 2021. Serial plasma samples were collected from admission until discharge. Viral load was quantified by Real-Time Polymerase Chain Reaction and IL6 levels with an enzyme immunoassay. To represent the evolution over time of both variables we used the graphic command twoway of Stata. Results: A total of 57 patients were recruited, with median age of 63 years (IQR [53-81]), 61.4% male and 68.4% Caucasian. The peak of viremia appeared shortly after symptom onset in patients with persistent viremia (more than 1 sample with > 1.3 log10 copies/ml) and also in those with at least one IL6 > 30 pg/ml, followed by a progressive increase in IL6 around 10 days later. Persistent viremia in the first week of hospitalization was associated with higher levels of IL6. Both IL6 and SARS-CoV-2 viral load were higher in males, with a quicker increase with age. Conclusion: In those patients with worse outcomes, an early peak of SARS-CoV-2 viral load precedes an increase in IL6 levels. Monitoring SARS-CoV-2 viral load during the first week after symptom onset may be helpful to predict disease severity in COVID-19 patients.

Correction: Transmembrane protease serine 2 (TMPRSS2) rs75603675, comorbidity and sex are the primary predictors of Covid-19 severity.

We identified an error in the abstract of the article: TPMRSS2 rs75603675 OR is incorrectly indicated. It should read (OR = 2.140) instead of (OR = 0.586). We apologize for this error. However, since the main text is correct, it has no impact on the results displayed in the study.

Usefulness of real-time RT-PCR to understand the kinetics of SARS-CoV-2 in blood: A prospective study.

BACKGROUND: SARS-CoV-2 viral load and kinetics assessed in serial blood samples from hospitalised COVID-19 patients by RT-PCR are poorly understood. METHODS: We conducted an observational, prospective case series study in hospitalised COVID-19 patients. Clinical outcome data (Intensive Care Unit admission and mortality) were collected from all patients until discharge. Viremia was determined longitudinally during hospitalisation, in plasma and serum samples collected sequentially, using two commercial and standardised RT-PCR techniques approved for use in diagnosis of SARS-CoV-2. Viral load (copies/mL and log10) was determined with quantitative TaqPath™COVID-19 test. Persistent viremia (PV) was defined as two or more consecutive quantifiable viral loads detected in blood samples (plasma/serum) during hospitalisation. RESULTS: SARS-CoV-2 viremia was studied in 57 hospitalised COVID-19 patients. PV was detected in 16 (28%) patients. All of them, except for one who rapidly progressed to death, cleared viremia during hospitalisation. Poor clinical outcome occurred in 62.5% of patients with PV, while none of the negative patients or those with sporadic viremia presented this outcome (p < 0.0001). Viral load was significantly higher in patients with PV than in those with Sporadic Viremia (p < 0.05). Patients presented PV for a short period of time: median time from admission was 5 days (Range = 2-12) and 4.5 days (Range = 2-8) for plasma and serum samples, respectively. Similar results were obtained with all RT-PCR assays for both types of samples. CONCLUSIONS: Detection of persistent SARS-CoV-2 viremia, by real time RT-PCR, expressed as viral load over time, could allow identifying hospitalised COVID-19 patients at risk of poor clinical outcome.

Transmembrane protease serine 2 (TMPRSS2) rs75603675, comorbidity, and sex are the primary predictors of COVID-19 severity.

By the end of December 2021, coronavirus disease 2019 (COVID-19) produced more than 271 million cases and 5.3 million deaths. Although vaccination is an effective strategy for pandemic control, it is not yet equally available in all countries. Therefore, identification of prognostic biomarkers remains crucial to manage COVID-19 patients. The aim of this study was to evaluate predictors of COVID-19 severity previously proposed. Clinical and demographic characteristics and 120 single-nucleotide polymorphisms were analyzed from 817 patients with COVID-19, who attended the emergency department of the Hospital Universitario de La Princesa during March and April 2020. The main outcome was a modified version of the 7-point World Health Organization (WHO) COVID-19 severity scale (WHOCS); both in the moment of the first hospital examination (WHOCS-1) and of the severest WHOCS score (WHOCS-2). The TMPRSS2 rs75603675 genotype (OR = 0.586), dyslipidemia (OR = 2.289), sex (OR = 0.586), and the Charlson Comorbidity Index (OR = 1.126) were identified as the main predictors of disease severity. Consequently, these variables might influence COVID-19 severity and could be used as predictors of disease development.