Walewska, A. | bioRxiv Science

bioRxiv2025

Plasma Gelsolin Prevents Organ-Specific Inflammation and Enhances Innate Immune Function in a Systemic Candida albicans Infection

Systemic Candida albicans infections (candidemia) remain a significant cause of morbidity and mortality in immunocompromised patients, mainly due to severe inflammation, organ damage, and delayed fungal clearance. Plasma gelsolin (pGSN), an actin-binding protein with immunomodulatory properties, has demonstrated protective effects in bacterial sepsis models, but its role in fungal infections remains unexplored. Here, we evaluated the impact of pGSN in a murine model of candidemia. Mice intravenously challenged with C. albicans exhibited strong inflammatory responses, particularly in the kidneys and lungs, as visualized by IRDye 800CW 2-deoxyglucose imaging and confirmed by histopathological examination. Subcutaneous injection of pGSN significantly reduced systemic and organ-specific inflammation, decreased blood fungal burden, and prevented microabscess formation in the kidneys. In parallel, pGSN suppressed inflammatory gene expression in whole blood and enhanced phagocytic activity of human monocytes. Additionally, pGSN modulated monocyte reactive radical production by increasing nitric oxide and reducing hydrogen sulfide and reactive oxygen species production. These results highlight the dual immunomodulatory and host-protective properties of pGSN, supporting its potential as an adjunctive therapy in fungal sepsis.

microbiology↗

bioRxiv2024

Extracellular Vimentin is a Damage-Associated Molecular Pattern Protein Serving as an Agonist of TLR4 in Human Neutrophils

BackgroundVimentin is a type III intermediate filament protein, that plays an important role in cytoskeletal mechanics. It is now known that vimentin also plays important roles outside the cell. Recent studies show the controlled release of vimentin into the extracellular environment, where it functions as a signaling molecule. Such observations are expanding our current knowledge of vimentin as a structural cellular component towards additional roles as an active participant in cell signaling. MethodsOur study investigates the immunological roles of extracellular vimentin (eVim) and its citrullinated form (CitVim) as a damage-associated molecular pattern (DAMP) engaging the Toll-like receptor 4 (TLR4) of human neutrophils. We used in vitro assays to study neutrophil migration through endothelial cell monolayers and activation markers such as NADPH oxidase subunit 2 (NOX2/gp91phox). The comparison of eVim with CitVim and its effect on human neutrophils was extended to the induction of extracellular traps (NETs) and phagocytosis of pathogens. ResultsBoth eVim and CitVim interact with and trigger TLR4, leading to increased neutrophil migration and adhesion. CitVim stimulated the enhanced migratory ability of neutrophils, activation of NF-{kappa}B, and induction of NET formation mainly mediated through reactive oxygen species (ROS)-dependent and TLR4-dependent pathways. In contrast, neutrophils exposed to non-citrullinated vimentin exhibited higher efficiency in favoring pathogen phagocytosis, such as Escherichia coli and Candida albicans, compared to CitVim. ConclusionsOur study identifies new functions of eVim in its native and modified forms as an extracellular matrix DAMP and highlights its importance in the modulation of immune system functions. The differential effects of eVim and CitVim on neutrophil functions highlight their potential as new molecular targets for therapeutic strategies aimed at differential regulation of neutrophil activity in different pathological conditions. This, in turn, opens new windows of therapeutic intervention in inflammatory and immunological diseases characterized by immune system dysfunction, in which eVim and CitVim play a key role.

immunology↗