T cell immunity toward SARS-CoV-2 spike (S-), membrane (M-), and nucleocapsid (N-) proteins may define COVID-19 severity. Therefore, we compare the SARS-CoV-2-reactive T cell responses in moderate, severe, and critical COVID-19 patients and unexposed donors. Overlapping peptide pools of all three proteins induce SARS-CoV-2-reactive T cell response with dominance of CD4 + over CD8 + T cells and demonstrate interindividual immunity against the three proteins. M-protein induces the highest frequencies of CD4 + T cells, suggesting its relevance for diagnosis and vaccination. The T cell response of critical COVID-19 patients is robust and comparable or even superior to non-critical patients. Virus clearance and COVID-19 survival are not associated with either SARS-CoV-2 T cell kinetics or magnitude of T cell responses, respectively. Thus, our data do not support the hypothesis of insufficient SARS-CoV-2-reactive immunity in critical COVID-19. Conversely, it indicates that activation of differentiated memory effector T cells could cause hyperreactivity and immunopathogenesis in critical patients.

Severe acute respiratory syndrome corona virus 2 (SARS‐CoV‐2) preferentially affects epithelia of the upper and lower respiratory tract. Thus, impairment of kidney function has been primarily attributed until now to secondary effects such as cytokine release or fluid balance disturbances. We provide evidence that SARS‐CoV‐2 can directly infiltrate a kidney allograft. A 69‐year‐old male, who underwent pancreas‐kidney transplantation 13 years previously, presented to our hospital with coronavirus disease 2019 (COVID‐19) pneumonia and impaired pancreas and kidney allograft function. Kidney biopsy was performed showing tubular damage and an interstitial mononuclear cell infiltrate. Reverse transcriptase polymerase chain reaction from the biopsy specimen was positive for SARS‐CoV‐2. In‐situ hybridization revealed SARS‐CoV‐2 RNA in tubular cells and the interstitium. Subsequently, he had 2 convulsive seizures. Magnetic resonance tomography suggested meningoencephalitis, which was confirmed by SARS‐CoV‐2 RNA transcripts in the cerebrospinal fluid. The patient had COVID‐19 pneumonia, meningoencephalitis, and nephritis. SARS‐CoV‐2 binds to its target cells through angiotensin‐converting enzyme 2, which is expressed in a broad variety of tissues including the lung, brain, and kidney. SARS‐CoV‐2 thereby shares features with other human coronaviruses including SARS‐CoV that were identified as pathogens beyond the respiratory tract as well. The present case should provide awareness that extrapulmonary symptoms in COVID‐19 may be attributable to viral infiltration of diverse organs.

OBJECTIVES: Prevention and therapy of immunothrombosis remain crucial challenges in the management of coronavirus disease 2019, since the underlying mechanisms are incompletely understood. We hypothesized that endothelial damage may lead to substantially increased concentrations of von Willebrand factor with subsequent relative deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13). DESIGN: Prospective controlled cross-over trial. SETTING: Blood samples of patients with confirmed coronavirus disease 2019 and healthy controls were obtained in three German hospitals and analyzed in a German hemostaseologic laboratory. PATIENTS: Seventy-five patients with confirmed coronavirus disease 2019 of mild to critical severity and 30 healthy controls. MEASUREMENTS AND MAIN RESULTS: von Willebrand factor antigen, ADAMTS13, and von Willebrand factor multimer formation were analyzed. von Willebrand factor antigen was 4.1 times higher in COVID-19 patients compared with healthy controls (p < 0.0001), whereas ADAMTS13 activities were not significantly different (p = 0.18). The ADAMTS13/von Willebrand factor antigen ratio was significantly lower in COVID-19 than in the control group (24.4 ± 20.5 vs 82.0 ± 30.7; p < 0.0001). Fourteen patients (18.7%) undercut a critical ratio of 10 as described in thrombotic thrombocytopenic purpura. Gel analysis of multimers resembled a thrombotic thrombocytopenic purpura pattern with loss of the largest multimers in 75% and a smeary triplet pattern in 39% of the patients. The ADAMTS13/von Willebrand factor antigen ratio decreased continuously from mild to critical disease (analysis of variance p = 0.026). Furthermore, it differed significantly between surviving patients and those who died from COVID-19 (p = 0.001) yielding an area under the curve of 0.232 in receiver operating characteristic curve curve analysis. Conclusion: COVID-19 is associated with a substantial increase in von Willebrand factor levels, which can exceed the ADAMTS13 processing capacity resulting in the formation of large von Willebrand factor multimers indistinguishable from thrombotic thrombocytopenic purpura. The ADAMTS13/von Willebrand factor antigen ratio is an independent predictor of severity of disease and mortality. These findings provide a rationale to consider plasma exchange as a therapeutic option in COVID-19 and to include von Willebrand factor and ADAMTS13 in the diagnostic workup.

Supplemental Digital Content is available in the text.

No abstract

Preventing the progression to acute respiratory distress syndrome (ARDS) in COVID-19 is an unsolved challenge. The involvement of T cell immunity in this exacerbation remains unclear. To identify predictive markers of COVID-19 progress and outcome, we analyzed peripheral blood of 10 COVID-19-associated ARDS patients and 35 mild/moderate COVID-19 patients, not requiring intensive care. Using multi-parametric flow cytometry, we compared quantitative, phenotypic and functional characteristics of circulating bulk immune cells, and SARS-CoV-2 S-protein reactive T cell between the two groups. ARDS patients demonstrated significantly higher S-protein reactive CD4 + and CD8 + T cells compared to non-ARDS patients. Of interest, comparison of circulating bulk T cells in ARDS patients to non-ARDS patients demonstrated decreased frequencies of CD4 + and CD8 + T cell subsets with activated memory/effector T cells expressing tissue migration molecule CD11a ++ . Importantly, survival from ARDS (4/10) was accompanied by a recovery of the CD11a ++ T cell subsets in peripheral blood. Conclusively, data on S-protein reactive polyfunctional T cells indicate the ability of ARDS patients to generate antiviral protection. Furthermore, decreased frequencies of activated memory/effector T cells expressing tissue migratory molecule CD11a ++ observed in circulation of ARDS patients might suggest their involvement in ARDS development and propose CD11a-based immune signature as a possible prognostic marker.

No abstract

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-, Mand 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 individualdifferences, 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.