Adaptive Immunity Dysregulation Is Associated to the Development of Long Covid

Background: The pathogenetic mechanisms behind the development of long- COVID (LC) are largely unknown. Because both plasma SARS-CoV-2 RNAemia and dysregulated immunity have been correlated with COVID-19 severity, we evaluated whether they are associated with LC. Method(s): We consecutively enrolled unvaccinated hospitalized COVID-19 patients during acute-COVID-19 (T0) in March-October 2020 who either developed LC at a follow-up visit 2-3 months from virologic clearance (T1) or did not. LC was defined as persistence >=2 months after recovery of >=1 symptom: anosmia, dysgeusia, fever, gastrointestinal symptoms, dyspnoea, fatigue, musculoskeletal pain, muscle weakness, brain fog. We measured: SARS-CoV-2 RNAemia (RT-qPCR, log10(copies/mL)), magnitude (ELISA, AUC) and functionality (pseudovirus neutralization, ID50;Fc-mediated functions, %ADCC) of SARS-CoV-2-specific antibodies, SARS-CoV-2-specific B and CD4-T-cells (Immunophenotype, AIM and ICS assays). Result(s): We enrolled 48 COVID-19 individuals, 38/48 (79.2%) developed LC (LC+) and 10 did not (LC-). LC+ and LC- had similar co-morbidities and symptoms in the acute phase (Fig.1A), and the majority showed a radiologically documented SARS-CoV-2 pneumonia. The SARS-CoV-2 RNAemia did not differ between groups at both time points. The levels of RBD-specific Abs, as well as their functionality, appeared to increase over time in the LC- group but not in the LC+ (Fig.1B-D). Similarly, a trend towards increased RBD-specific B-cells was observed over time in the LC- group but not in LC+ (Fig.1E). B-cell immunophenotyping showed a significant increase over time of classical memory B cells (MBCs) at the expenses of activated MBCs (Fig.1F-G) as well as an IgA class-switching in the LC- group compared to LC+ (Fig.1H-I). Furthermore, LC+ showed a faster decline of SARS-CoV-2-specific (CD69+CD137+) CD4- TEMRA and CD4-TEM (Fig.1L-M). Finally, IFN-gamma-producing TREG of LC- individuals increased over time (Fig.1N). Conclusion(s): Acutely ill, hospitalized COVID-19 patients developing LC feature a dysregulated SARS-CoV-2-specific humoral as well as B- and T-cell response, in both magnitude and functionality, suggesting a link between dysregulated SARS-CoV-2-specific adaptive immunity and LC development. The fine understanding of the factors contributing to such dysregulation in LC patients is strongly needed, that might further inform targeted therapeutic interventions. (Figure Presented).

HIGH RNAemia ASSOCIATES WITH SKEWED T-CELL RESPONSE IN PLWH HOSPITALIZED FOR COVID-19

Background: Severe COVID-19 outcomes have been reported in people living with HIV (PLWH). High SARS-CoV-2 RNAemia has emerged as a hallmark of severe COVID-19, yet its pathogenic role in the context of COVID-19 in PLWH is currently unknown. We hereby measured SARS-CoV-2 RNAemia and explored its association with T-cell/humoral responses and clinical severity in PLWH. Method(s): Unvaccinated PLWH and age/sex-matched people living without HIV (PLWOH) hospitalized for radiologically-confirmed COVID-19 pneumonia were consecutively enrolled (March 2020-January 2021). We measured: SARS-CoV-2 RNAemia (RT-qPCR);T-cell activation (HLA-DR+CD-38+), cytotoxic T-cells [granzyme-B(GRZB)+perforin(PRF)+], GRZB/PRF production (MFI) by cytotoxic T-cells (flow cytometry);SARS-CoV-2-specific cytokines (IFN-gamma/ TNF-alpha/IL-2/IL-4/IL-17A)-producing T-cells, after SARS-CoV-2 spike peptides challenge (flow cytometry);anti-RBD antibodies (ELISA), Spike-ACE2 binding inhibition (receptor binding inhibition assay). Statistics: Mann-Whitney test and Spearman's correlation. Result(s): 18 PLWH (16 on cART;median CD4 361.5/mL;HIV-RNA< 50 cp/ mL in 15/18) and 18 PLWOH were included at a median of 10 days from symptoms onset (Fig.1A). PLWH had lower PaO2/FiO2 [140 (122-151.5) vs. 207 (156.3-309.3);P=0.0005] and higher SARS-CoV-2 RNAemia (Fig.1B). While humoral responses were comparable between groups ( Fig.1C-D), as was T-cell activation, PLWH showed skewed T-cell responses: higher perforin production by cytotoxic T-cells (Fig.1E);fewer SARS-CoV-2-specific IFN-gamma+ and IL-4+ CD4 T-cells (Fig.1F);lower Th1 tri-functional (IFN-gamma+TNF-alpha+IL-2+) and bi-functional (IFN-gamma+TNF-alpha+) CD4 T-cells (Fig.1G);reduced TNF-alpha+ CD8 T-cells (Fig.1H). Interestingly, SARS-CoV-2 RNAemia correlated negatively with PaO2/FiO2 nadir and SARS-CoV-2-specific T-cells, yet positively with perforin production by cytotoxic T-cells (Fig.1I-M). No correlations between RNAemia and humoral responses were found. Conclusion(s): As compared to HIV-uninfected patients, PLWH hospitalized for COVID-19 pneumonia feature high SARS-CoV-2 RNAemia which is linked to respiratory failure and skewed T-cell responses, with higher perforin production by cytotoxic T-cells, and yet fewer polyfunctional SARS-CoV-2-specific T-cells. Our data suggest a link between HIV-related T-cell dysfunction and poor control over circulating SARS-CoV-2 that may in turn influence COVID-19 severity in PLWH. (Figure Presented).

SARS-CoV-2 PLASMA VIREMIA and DYSREGULATED IMMUNITY in SEVERE COVID-19

Background: Critical COVID-19 occurs ca. 7d from symptoms onset, and is associated to immune dysregulation as well as SARS-CoV-2 detection in plasma (i.e. viremia). We hereby sought to detail the association between SARS-CoV-2 viremia measured at the end of the first week of disease and immune phenotypes/function in COVID-19 patients. Methods: We consecutively enrolled patients hospitalized in the acute phase of ascertained SARS-CoV-2 pneumonia. In this disease stage, we studied SARS-CoV-2 viremia (RT-PCR) and cytokines (MACSPlex), HLA-DR+CD38+ activated, GRZB+PRF+ pro-cytolitic T-cells, intracellular cytokine production (IL-2, IFNγ, TNFα, IL-4, IL-17A) after SARS-CoV-2 challenge (S-N-M-peptide pool). Simultaneous Th1-cytokines production (polyfunctionality) and amount (iMFI) was assessed. Humoral response: anti-S1/S2 IgG, anti-RBD total-Ig, IgM, IgA, IgG1 and IgG3 (ELISA), pseudoviruses neutralization (ID50) and Fc-mediated functions (%ADCC). Results: Out of 54 patients, 27 had detectable viremia (V+). Albeit comparable age and co-morbidities, V+ patients more frequently required non-invasive/invasive ventilatory support (p=0.035), with a trend to higher death (p=0.099) vs patients with undetectable viremia (V-)(Fig.1A). V+ displayed higher circulating IFN-α (p=0.002) and IL-6 (0.003), lower activated HLA-DR+CD38+CD4 (p=0.01) and CD8 (p=0.02), with no differences in GRZB+PRF+ T-cells. V+ featured reduced SARS-CoV-2-specific cytokine-producing T-cells, reaching significance for IFNγ+CD4 (p=0.02), TNFα+CD8, IL-4+CD8 (p=0.04) (Fig.1B-C), with lower bi-and tri-functional SARS-CoV-2-specific CD4 Th1, reaching significance for IL-2+TNFα+CD4 (p=0.03) (Fig.1D). A trend towards lower cytokines iMFI in bi-and tri-functional SARS-CoV-2-specific CD4 Th1 was observed in V+, reaching significance for IL-2+TNFα+CD4, p=0.004. V+ displayed lower anti-S IgG, anti-RBD total-Ig, IgM, IgG1 and IgG3 (Fig.1E), with lower ID50 and %ADCC vs V-(Fig.1F-G). Conclusion: Hospitalized COVID-19 patients with detectable plasma SARS-CoV-2 RNA in the acute phase of disease present worse outcome, higher inflammatory cytokines, fewer activated and SARS-CoV-2-specific polyfunctional T-cells, suggesting a link between SARS-CoV-2 viremia at the end of the first stage of disease and immune dysregulation. Whether high ab initium viral burden and/or intrinsic host factors contribute to a delayed and/or exhausted immune response in severe COVID-19 remains to be elucidated, to further inform strategies of targeted therapeutic interventions.