- [INMUNOLOGÍA E INMUNOTERAPIA]
- [ANATOMÍA PATOLÓGICA]
- [MICROBIOLOGÍA CLÍNICA]
- [MEDICINA INTERNA]
- [ENFERMEDADES INFECCIOSAS]
Neutrophil extracellular traps, local IL-8 expression, and cytotoxic T-lymphocyte response in the lungs of fatal COVID-19
Ignacio Melero 1 , María Villalba-Esparza 2 , Borja Recalde-Zamacona 3 , Daniel Jiménez-Sánchez 4 , Álvaro Teijeira 5 , Alan Argueta 4 , Laura García-Tobar 4 , Laura Álvarez-Gigli 4 , Cristina Sainz 4 , David Garcia-Ros 6 , Estefanía Toledo 7 , Marta Abengozar-Muela 4 , Mirian Fernández-Alonso 8 , Mariano Rodríguez-Mateos 9 , Gabriel Reina 8 , Francisco Carmona-Torre 8 , Jorge Augusto Quiroga 10 , Jose L Del Pozo 8 , Amy Cross 11 , Álvaro López-Janeiro 12 , David Hardisson 12 , José I Echeveste 13 , Maria D Lozano 14 , Ling-Pei Ho 15 , Paul Klenerman 16 , Fadi Issa 11 , Manuel F Landecho 10 , Carlos E de Andrea 17
Background: Excessive inflammation is pathogenic in the pneumonitis associated with severe COVID-19. Neutrophils are among the most abundantly present leukocytes in the inflammatory infiltrates and may form neutrophil extracellular traps (NETs) under the local influence of cytokines. NETs constitute a defense mechanism against bacteria but have also been shown to mediate tissue damage in a number of diseases.
Research question: Could NETs and their tissue-damaging properties inherent to neutrophil-associated functions play a role in the respiratory failure seen in severe COVID-19 patients and how does this relate to the SARS-CoV-2 viral loads, IL-8 (CXCL8) chemokine expression, and cytotoxic T-lymphocytes infiltrates?
Study design and methods: Sixteen immediate post-mortem lung biopsies were methodically analyzed as exploratory and validation cohorts. NETs were quantitatively analyzed by multiplexed immunofluorescence and correlated with local levels of IL-8 mRNA and the density of CD8+ T-cell infiltration. SARS-CoV-2 presence in tissue was quantified by RT-PCR and immunohistochemistry.
Results: NETs were found in the lung interstitium and surrounding the bronchiolar epithelium with interindividual and spatial heterogeneity. NET density did not correlate with SARS-CoV-2 tissue viral load. NETs were associated with local IL-8 mRNA levels. NETs were also detected in pulmonary thrombi and in only one out of eight liver tissues. NET focal presence negatively correlated with CD8+ T-cell infiltration in the lungs.
Interpretation: Abundant neutrophils undergoing NETosis are found in the lungs of patients with fatal COVID-19, but no correlation is found with viral loads. The strong association between NETs and IL-8 points to this chemokine as a potentially causative factor. The function of cytotoxic T-lymphocytes in the immune responses against SARS-CoV-2 may be interfered with the presence of NETs.CITA DEL ARTÍCULO Chest. 2022 Nov;162(5):1006-1016. doi: 10.1016/j.chest.2022.06.007. Epub 2022 Jun 15