Reduction in the number of neutrophils in the broncho-alveolar aspirate is associated with worse prognosis in elderly patients with severe COVID-19

Abstract

The blood levels of neutrophils are associated with the severity of COVID -19. However, their role in the pulmonary environment during COVID -19 severity is not clear. Here, we found a decrease in the neutrophil count in BAL (bronchoalveolar lavage) in non-survivors and in older patients (> 60 years). In addition, we have shown that older patients have higher serum concentration of CXCL8 and increased IL-10 expression by neutrophils.

Keywords: ARDS; Elderly patients; Mechanical ventilation; Neutrophils; Severe COVID-19.

Fig. 1

Neutrophils are reduced in the BAL of non-survivors and patients over than 60 years with severe COVID-19. Curve of survival from COVID-19 patients under mechanical ventilation (A). Flow cytometry analysis of neutrophils frequencies (B) and numbers (C) in survivor group (n = 10) and non-survivor group (n = 13). Survival curve of patients younger (< 60 years of age) and older (> 60 years of age) (D). Flow cytometry analysis of the neutrophil frequencies (E) and numbers (F). Frequencies (G) and numbers (H) of neutrophils in younger survivors (n = 7), younger non-survivors (n = 3), older survivors (n = 3), and older non-survivors (n = 10). Flow cytometry analysis of MFI of IL-10 (I), IFN-γ (J) and TNF (K) expressed by neutrophils. CXCL8 concentration (L) in the BAL of younger and older patients with COVID-19. Horizontal lines represent geometric mean ± 95% CI. *P < 0.05, **P < 0.01, ***P < 0.001 by one-way ANOVA followed by Newman–Keuls multiple comparisons post-test or by a t-test, to compare medians of the two groups. Survival analysis was made by Log Rank test. Outliers were identified using the ROUT (Q = 2.0%) method of GraphPad Prism program version 9.0 and removed from the analysis