Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infections in infants, yet therapeutics are lacking. The aim of this study was to develop a pre‑clinical model that recapitulates key clinical outcomes in infants with RSV bronchiolitis, such as neutrophil activation and migration into the airways. Peripheral blood neutrophils from infants with severe RSV disease admitted to the Paediatric Intensive Care Unit showed elevated myeloperoxidase (MPO) in children with RSV, compared to age-matched controls. To mechanistically model this response, we established an air-liquid interface (ALI) system incorporating paediatric airway epithelial cells, endothelial cells and neutrophils from adults, to recapitulate the blood-airway barrier. Following RSV infection, with and without treatment with antivirals remdesivir or RSV604, neutrophil migration and activation were assessed using flow cytometry. While both drugs reduced viral load, only RSV604 attenuated MPO expression. This model suggests that MPO could be useful as a readout of therapeutic efficacy. Targeting neutrophil-driven inflammatory pathways may be critical for reducing pathology in infant RSV infection.

Type 2 diabetes mellitus (T2DM) is a critical risk factor for coronary artery disease (CAD), with neutrophils contributing to CAD through acute inflammatory responses. Sodium-glucose cotransporter 2 (SGLT-2) inhibitors offer cardiovascular benefits beyond glycemic control, but their mechanisms involving innate immunity and neutrophil function in T2DM-related CAD remain unclear. Neutrophils were isolated from healthy controls, patients with CAD and T2DM, and patients receiving SGLT2 inhibitor therapy. Bulk transcriptomic analysis, flow cytometry, ELISA, and western blotting were used to assess gene expression, signaling changes, and neutrophil activation. Co-cultures of neutrophils with luciferase-expressing human aortic endothelial cells (HAEC-Luc) assessed endothelial injury, and a diabetic rat model was used to assess in vivo cardiac injury. Results showed elevated peripheral neutrophil cell-free dsDNA, elastase 2, and GREM1 expression in patients with T2DM-CAD, reversed by SGLT-2 inhibitors. T2DM-CAD neutrophils induced significant endothelial injury, ameliorated by SGLT-2 inhibition, or GREM1 blockade. Mechanistically, SGLT-2 inhibitors suppressed GREM1, restored TGF-β/Smad signaling, and reduced neutrophil-mediated cytotoxicity. In vivo, SGLT-2 inhibitors alleviated cardiac damage in diabetic rat, with suppressed neutrophil activation and upregulated TGF-β signaling. Our findings suggest that increased GREM1 expression in neutrophils is associated with impaired Smad1/5/9-related signaling and enhanced endothelial injury in T2DM-CAD, and SGLT-2 inhibitors exert vascular protection through GREM1 downregulation and TGF-β/Smad pathway modulation, highlighting a novel immunoregulatory mechanism with translational potential for diabetic cardiovascular outcomes.

BackgroundHigh densities of tertiary lymphoid structures (TLSs) are associated with improved clinical outcomes in various malignancies, including human papillomavirus (HPV)-associated head and neck squamous cell carcinoma (HNSCC). However, the role of TLSs in shaping antitumor immunity in HPV-induced cervical cancer (CESC) remains unclear. Therefore, we analyzed the density, composition, and prognostic impact of TLSs in patients with CESC as well as patients with HNSCC.MethodsMultiplex immunofluorescence, immunohistochemistry, and spatial transcriptomics were used to analyze TLS density and composition in HNSCC and CESC tissue sections with respect to patient prognosis. The spatial approach was supplemented by flow cytometry-based analysis of the polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) phenotype in freshly resected primary tumor tissues.ResultsAlthough both indications were associated with HPV infection, we confirmed a positive correlation between TLS density and improved overall survival only in patients with HNSCC. The TLS composition differed markedly between HNSCC and CESC samples, with a shift toward high regulatory T cell (Treg) and PMN-MDSC abundance in CESC samples. The highest Treg and PMN-MDSC levels were observed in patients with CESC who died of the disease. CESC-infiltrating PMN-MDSCs showed high arginase 1 expression, which correlated with diminished T-cell receptor (TCR)ζ chain expression in CESC-infiltrating T cells. Additionally, the high number of PMN-MDSCs in TLSs was associated with the absence of HPV-specific T cells in CESC.ConclusionsUnlike in HNSCC, the composition of TLSs, rather than their quantity, was associated with the overall survival of patients with CESC. High numbers of Tregs and PMN-MDSCs infiltrating immature TLSs prevail in patients with CESC who succumbed to the disease and seem to affect tumor-specific immune responses.