Alveolar compartmentalization of inflammatory and immune cell biomarkers in pneumonia-related ARDS.

BACKGROUND: Biomarkers of disease severity might help individualizing the management of patients with the acute respiratory distress syndrome (ARDS). Whether the alveolar compartmentalization of biomarkers has a clinical significance in patients with pneumonia-related ARDS is unknown. This study aimed at assessing the interrelation of ARDS/sepsis biomarkers in the alveolar and blood compartments and explored their association with clinical outcomes. METHODS: Immunocompetent patients with pneumonia-related ARDS admitted between 2014 and 2018 were included in a prospective monocentric study. Bronchoalveolar lavage (BAL) fluid and blood samples were obtained within 48 h of admission. Twenty-two biomarkers were quantified in BAL fluid and serum. HLA-DR+ monocytes and CD8+ PD-1+ lymphocytes were quantified using flow cytometry. The primary clinical endpoint of the study was hospital mortality. Patients undergoing a bronchoscopy as part of routine care were included as controls. RESULTS: Seventy ARDS patients were included. Hospital mortality was 21.4%. The BAL fluid-to-serum ratio of IL-8 was 20 times higher in ARDS patients than in controls (p < 0.0001). ARDS patients with shock had lower BAL fluid-to-serum ratio of IL-1Ra (p = 0.026), IL-6 (p = 0.002), IP-10/CXCL10 (p = 0.024) and IL-10 (p = 0.023) than others. The BAL fluid-to-serum ratio of IL-1Ra was more elevated in hospital survivors than decedents (p = 0.006), even after adjusting for SOFA and driving pressure (p = 0.036). There was no significant association between alveolar or alveolar/blood monocytic HLA-DR or CD8+ lymphocytes PD-1 expression and hospital mortality. CONCLUSIONS: IL-8 was the most compartmentalized cytokine and lower BAL fluid-to-serum concentration ratios of IL-1Ra were associated with hospital mortality in patients with pneumonia-associated ARDS.

Maturation and persistence of the anti-SARS-CoV-2 memory B cell response.

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role has been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including pre-existing cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late, remarkably stable, memory B cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection.

Uncontrolled Innate and Impaired Adaptive Immune Responses in Patients with COVID-19 Acute Respiratory Distress Syndrome.

Rationale: Uncontrolled inflammatory innate response and impaired adaptive immune response are associated with clinical severity in patients with coronavirus disease (COVID-19).Objectives: To compare the immunopathology of COVID-19 acute respiratory distress syndrome (ARDS) with that of non-COVID-19 ARDS, and to identify biomarkers associated with mortality in patients with COVID-19 ARDS.Methods: Prospective observational monocenter study. Immunocompetent patients diagnosed with RT-PCR-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and ARDS admitted between March 8 and March 30, 2020, were included and compared with patients with non-COVID-19 ARDS. The primary clinical endpoint of the study was mortality at Day 28. Flow cytometry analyses and serum cytokine measurements were performed at Days 1-2 and 4-6 of ICU admission.Measurements and Main Results: As compared with patients with non-COVID-19 ARDS (n = 36), those with COVID-19 (n = 38) were not significantly different regarding age, sex, and Sequential Organ Failure Assessment and Simplified Acute Physiology Score II scores but exhibited a higher Day-28 mortality (34% vs. 11%, P = 0.030). Patients with COVID-19 showed profound and sustained T CD4+ (P = 0.002), CD8+ (P < 0.0001), and B (P < 0.0001) lymphopenia, higher HLA-DR expression on monocytes (P < 0.001) and higher serum concentrations of EGF (epithelial growth factor), GM-CSF, IL-10, CCL2/MCP-1, CCL3/MIP-1a, CXCL10/IP-10, CCL5/RANTES, and CCL20/MIP-3a. After adjusting on age and Sequential Organ Failure Assessment, serum CXCL10/IP-10 (P = 0.047) and GM-CSF (P = 0.050) were higher and nasopharyngeal RT-PCR cycle threshold values lower (P = 0.010) in patients with COVID-19 who were dead at Day 28.Conclusions: Profound global lymphopenia and a "chemokine signature" were observed in COVID-19 ARDS. Increased serum concentrations of CXCL10/IP-10 and GM-CSF, together with higher nasopharyngeal SARS-CoV-2 viral load, were associated with Day-28 mortality.