Cytokine storm and vascular leakage in severe dengue: insights from single-cell RNA profiling.

Severe dengue is characterized by vascular leakage triggered by a hyperinflammatory response, though the underlying mechanisms remain unclear. Our previous mouse model study highlighted the importance of small intestine in severe disease and identified key cytokines (IL-17A, TNF-α, and IL-6) involved. Here, we used a Fixed RNA Profiling assay to characterize key cytokine- and effector-producing cells, along with their receptor expression. Type 3 innate lymphoid cells (ILC3), Th17 cells, and γδ T cells emerged as pathologically relevant IL-17A/Fproducing cells. These cells expressed IL-1β and IL-23 receptors, underscoring the significance of these signaling pathways. IL-1β was produced by M2-like macrophages, dendritic cells, and neutrophils, whereas M1-like macrophages, which differentiated post-infection, produced IL-23, TNF-, and IL-6, acting as initiators and amplifiers of the cytokine storm. Newly differentiated neutrophils produced IL-1β and effector molecule matrix metalloprotease-8, suggesting a dual role in exacerbating the cytokine storm and directly mediating vascular leakage. Identified macrophages and neutrophils exhibited atypical characteristics. These findings provide new pathological insights into severe dengue and broader mechanism underlying cytokine storm-related diseases.