Increased migratory/activated CD8+ T cell and low avidity SARS-CoV-2 reactive cellular response in post-acute COVID-19 syndrome

The role of autoimmunity in post-acute sequelae of COVID-19 (PASC) is not well explored, although clinicians observe a growing population of convalescent COVID-19 patients with manifestation of post-acute sequelae of COVID-19. We analyzed the immune response in 40 post-acute sequelae of COVID-19 patients with non-specific PASC manifestation and 15 COVID-19 convalescent healthy donors. The phenotyping of lymphocytes showed a significantly higher number of CD8+ T cells expressing the Epstein-Barr virus induced G protein coupled receptor 2, chemokine receptor CXCR3 and C-C chemokine receptor type 5 playing an important role in inflammation and migration in PASC patients compared to controls. Additionally, a stronger, SARS-CoV-2 reactive CD8+ T cell response, characterized by IFN{gamma} production and predominant TEMRA phenotype but low SARS-CoV-2 avidity was detected in PASC patients compared to controls. Furthermore, higher titers of several autoantibodies were detected among PASC patients. Our data suggest that a persistent inflammatory response triggered by SARS-CoV-2 might be responsible for the observed sequelae in PASC patients. These results may have implications on future therapeutic strategies.

Generation of Inhibitory Autoantibodies to ADAMTS13 in Coronavirus Disease 2019

ObjectivesIt has recently been shown that von Willebrand factor (vWf) multimers may be a key driver of immunothrombosis in Coronavirus disease 2019 (COVID-19). Since COVID-19 is associated with an increased risk of autoreactivity, the present study investigates, whether the generation of autoantibodies to ADAMTS13 contributes to this finding. DesignObservational prospective controlled multicenter study. SettingBlood samples and clinical data of patients with COVID-19 were collected regularly during hospitalization in the period from April to November 2020. Patients90 patients with confirmed COVID-19 of mild to critical severity and 30 healthy controls participated in this study. Measuerements and Main ResultsAntibodies to ADAMTS13 occurred in 31 (34.4%) patients with COVID-19. Generation of ADAMTS13 antibodies was associated with a significantly lower ADAMTS13 activity (56.5%, interquartile range (IQR) 21.25 vs. 71.5%, IQR 24.25, p=0.0041), increased disease severity (severe or critical disease in 90% vs. 62.3%, p=0.0189), and a trend to a higher mortality (35.5% vs. 18.6%, p=0.0773). Median time to antibody development was 11 days after first positive SARS-CoV-2-PCR specimen. ConclusionThe present study demonstrates for the first time, that generation of antibodies to ADAMTS13 is a frequent finding in COVID-19. Generation of these antibodies is associated with a lower ADAMTS13 activity and an increased risk of an adverse course of the disease suggesting an inhibitory effect on the protease. These findings provide a rationale to include ADAMTS13 antibodies in the diagnostic workup of SARS-CoV-2 infections.

The differential impact of aerobic and isometric handgrip exercise on blood pressure variability and central aortic blood pressure.

BACKGROUND: Blood pressure variability and central SBP are independent markers of cardiovascular risk. Data on lifestyle-interventions to reduce these parameters are sparse. The present work reports the differential effects of aerobic vs. isometric handgrip exercise on blood pressure variability and central SBP in a prospective randomized trial. METHODS: Seventy-five hypertensive patients were randomized to one of the following 12-week programs: isometric handgrip training five times weekly; 'Sham-handgrip training' five times weekly; aerobic exercise training (30 min three to five times/week). Blood pressure variability was assessed by the coefficient of variation in 24-h ambulatory blood pressure monitoring (ABPM). Central SBP was measured noninvasively by the SphygmoCor device (AtCor Medical, Australia). RESULTS: The aerobic exercise program significantly decreased systolic daytime variability (12.1 ±â€Š2.5 vs. 10.3 ±â€Š2.8, P = 0.04), whereas diastolic daytime blood pressure variability was not significantly altered (P = 0.14). Night-time variability was not significantly affected (P > 0.05). Central SBP was reduced from 145±15 to 134 ±â€Š19 mmHg (P = 0.01). Isometric handgrip and sham-handgrip exercise did not significantly affect blood pressure variability (P > 0.05 each). Isometric exercise tended to reduce central SBP (142 ±â€Š19 to 136 ±â€Š17 mmHg, P = 0.06). ANCOVA revealed significant intergroup differences for the change of daytime SBP and DBP variability (P = 0.048 and 0.047, respectively). CONCLUSION: Aerobic exercise reduces blood pressure variability and central SBP. Isometric handgrip exercise does not reduce blood pressure variability but tends to lower central SBP in this hypertensive population.

COVID-19 is associated with relative ADAMTS13 deficiency and VWF multimer formation resembling TTP

BackgroundThrombotic microangiopathy (TMA) has been repeatedly described in COVID-19 and may contribute to SARS-CoV-2 associated hypercoagulability. The underlying mechanisms remain elusive. We hypothesized that endothelial damage may lead to substantially increased concentrations of Von Willebrand Factor (VWF) with subsequent relative deficiency of ADAMTS13. MethodsA prospective controlled trial was performed on 75 patients with COVID-19 of mild to critical severity and 10 healthy controls. VWF antigen (VWF:Ag), ADAMTS13 and VWF multimer formation were analyzed in a German hemostaseologic laboratory. ResultsVWF:Ag was 4.8 times higher in COVID-19 patients compared to healthy controls (p< 0.0001), whereas ADAMTS13 activities were not significantly different (p = 0.24). The ADAMTS13/VWF:Ag ratio was significantly lower in COVID-19 than in the control group (24.4{+/-}20.5 vs. 79.7{+/-}33.2, p< 0.0001). Fourteen patients (18.7%) undercut a critical ratio of 10 as described in thrombotic thrombocytopenic purpura (TTP). Gel analysis of multimers resembled the TTP constellation with loss of the largest multimers in 75% and a smeary triplet pattern in 39% of the patients. The ADAMTS13/VWF:Ag ratio decreased continuously from mild to critical disease (ANOVA p = 0.026). Moreover, it differed significantly between surviving patients and those who died from COVID-19 (p = 0.001) yielding an AUC of 0.232 in ROC curve analysis. ConclusionCOVID-19 is associated with a substantial increase in VWF levels, which can exceed the ADAMTS13 processing capacity resulting in the formation of large VWF multimers identical to TTP. The ADAMTS13/VWF:Ag ratio is an independent predictor of severity of disease and mortality. These findings render further support to perform studies on the use of plasma exchange in COVID-19 and to include VWF and ADAMTS13 in the diagnostic workup.

Impaired cytotoxic CD8+ T cell response in elderly COVID-19 patients

SARS-CoV-2 infection induces a T cell response that most likely contributes to virus control in COVID-19 patients, but may also induce immunopathology. Until now, the cytotoxic T cell response has not been very well characterized in COVID-19 patients. Here, we analyzed the differentiation and cytotoxic profile of T cells in 30 cases of mild COVID-19 during acute infection. SARS-CoV-2 infection induced a cytotoxic response of CD8+ T cells, but not CD4+ T cells, characterized by the simultaneous production of granzyme A and B, as well as perforin within different effector CD8+ T cell subsets. PD-1 expressing CD8+ T cells also produced cytotoxic molecules during acute infection indicating that they were not functionally exhausted. However, in COVID-19 patients over the age of 80 years the cytotoxic T cell potential was diminished, especially in effector memory and terminally differentiated effector CD8+ cells, showing that elderly patients have impaired cellular immunity against SARS-CoV-2. Our data provides valuable information about T cell responses in COVID-19 patients that may also have important implications for vaccine development. ImportanceCytotoxic T cells are responsible for the elimination of infected cells and are key players for the control of viruses. CD8+ T cells with an effector phenotype express cytotoxic molecules and are able to perform target cell killing. COVID-19 patients with a mild disease course were analyzed for the differentiation status and cytotoxic profile of CD8+ T cells. SARS-CoV-2 infection induced a vigorous cytotoxic CD8+ T cell response. However, this cytotoxic profile of T cells was not detected in COVID-19 patients over the age of 80 years. Thus, the absence of a cytotoxic response in elderly patients might be a possible reason for the more frequent severity of COVID-19 in this age group in comparison to younger patients.

SARS-CoV-2 reactive T cells in uninfected individuals are likely expanded by beta-coronaviruses

The current pandemic is caused by the SARS-CoV-2 virus and large progress in understanding the pathology of the virus has been made since its emergence in late 2019. Several reports indicate short lasting immunity against endemic coronaviruses, which contrasts repeated reports that biobanked venous blood contains SARS-CoV-2 reactive T cells even before the outbreak in Wuhan. This suggests there exists a preformed T cell memory in individuals not exposed to the pandemic virus. Given the similarity of SARS-CoV-2 to other members of the Coronaviridae family, the endemic coronaviruses appear likely candidates to generate this T cell memory. However, given the apparent poor immunological memory created by the endemic coronaviruses, other immunity against other common pathogens might offer an alternative explanation. Here, we utilize a combination of epitope prediction and similarity to common human pathogens to identify potential sources of the SARS-CoV-2 T cell memory. We find that no common human virus, other than beta-coronaviruses, can explain the pre-existing SARS-CoV-2 reactive T cells in uninfected individuals. Our study suggests OC43 and HKU1 are the most likely pathogens giving rise to SARS-CoV-2 preformed immunity.Competing Interest StatementThe authors have declared no competing interest.View Full Text

The SARS-CoV-2 T-cell immunity is directed against the spike, membrane, and nucleocapsid protein and associated with COVID 19 severity

Identification of immunogenic targets of SARS-CoV-2 is crucial for monitoring of antiviral immunity and vaccine design. Currently, mainly anti-spike (S)-protein adaptive immunity is investigated. However, also the nucleocapsid (N)- and membrane (M)-proteins should be considered as diagnostic and prophylactic targets. The aim of our study was to explore and compare the immunogenicity of SARS-CoV-2 S-, M- and N-proteins in context of different COVID-19 manifestations. Analyzing a cohort of COVID-19 patients with moderate, severe, and critical disease severity, we show that overlapping peptide pools (OPP) of all three proteins can activate SARS-CoV-2-reactive T-cells with a stronger response of CD4+ compared to CD8+ T-cells. Although interindividual variations for the three proteins were observed, M-protein induced the highest frequencies of CD4+ T-cells, suggesting its relevance as diagnostic and vaccination target. Importantly, patients with critical COVID-19 demonstrated the strongest T-cell response, including the highest frequencies of cytokine-producing bi- and trifunctional T-cells, for all three proteins. Although the higher magnitude and superior functionality of SARS-CoV-2-reactive T-cells in critical patients can also be a result of a stronger immunogenicity provided by severe infection, it disproves the hypothesis of insufficient SARS-CoV-2-reactive immunity in critical COVID-19. To this end, activation of effector T-cells with differentiated memory phenotype found in our study could cause hyper-reactive response in critical cases leading to immunopathogenesis. Conclusively, since the S-, M-, and N-proteins induce T-cell responses with individual differences, all three proteins should be evaluated for diagnostics and therapeutic strategies to avoid underestimation of cellular immunity and to deepen our understanding of COVID-19 immunity.

A possible role of immunopathogenesis in COVID-19 progression

BackgroundThe role of cellular immunity in pathogenesis of COVID-19 is unclear and conflicting data points to insufficient or pathogenic immunity as drivers of COVID-19 progression. Here we aimed to delineate the phenotype and function of the immune system in patients with moderate, severe, and critical COVID-19. MethodsIn this prospective study, we included 53 patients with moderate (n=21), severe (n=18), and critical (n=14) COVID-19 manifestations. Using multiparametric flow cytometry we compared quantitative, phenotypic, and functional characteristics of circulating immune cells, SARS-CoV-2 antigen-reactive T-cells, and humoral immunity. ResultsDeep phenotypic profiling revealed a depletion of circulating bulk CD8+ T-cells, CD4+ and CD8+ T-cell subsets with activated memory/effector T-cells expressing CD57+, HLA-DR+, and the key activation and migration molecule CD11a++ in critical COVID-19. Importantly, survival from acute respiratory distress syndrome was accompanied by a recovery of the depleted CD11++ T-cell subsets including T-cells expressing CD28, CD57, HLA-DR activation/effector molecules. We further observed a stronger response of S-protein specific T-cells producing inflammatory cytokines in critical COVID-19 cases. This seemingly contradictory observation is in fact confirmation of the underlying immunopathogenesis in patients with critical COVID-19. ConclusionOur findings suggest a CD11a-based immune signature as a possible prognostic marker for disease development. Our data further reveal that increased rather than decreased SARS-CoV-2 specific T cell immunity is associated with adverse outcome in COVID-19. Tissue migration of activated effectors T-cells may constitute a crucial cornerstone in the immunopathogenesis of SARS-CoV-2 associated tissue injury. Trial registrationThis is a prospective observational study without a trial registration number. FundingThis work was supported by grants from Mercator Foundation, the BMBF e:KID (01ZX1612A), and BMBF NoChro (FKZ 13GW0338B). 25 Word summaryStronger S-protein reactivity and decreased frequency of activated memory/effector T-cells expressing CD11a++ suggests immunopathogenesis in critical COVID-19 mediated by tissue migration of activated effector T-cells.