Biology subjects

Birnberg-Weiss, F.

Publications and source records attributed to Birnberg-Weiss, F..

3 recordsLinked to original sources

bioRxiv2025

Unraveling the Dual Immunomodulatory and Immunogenic Roles of the Central Conserved Cysteine-Rich Region in Respiratory Syncytial Virus G Protein

Respiratory syncytial virus (RSV) causes severe respiratory disease in infants and high-risk adults, in part by subverting host immunity. The RSV G glycoproteins central conserved cysteine-rich domain (CCD) contains a CX3C motif implicated in immune modulation, but the relationship between CCD redox state, structure and function is unresolved. We recombinantly expressed a CCD peptide (Gpep, residues 149-196) and combined structural and biophysical characterizations with cellular immunology and human serology to define how redox-dependent conformations govern immunogenicity and immunomodulation. Reduced Gpep is compact and rapidly folds via a dominant intermediate into an oxidized, extended monomer; at higher concentrations intermolecular disulfide isomerization produces covalent oligomers. Functionally, monomeric Gpep potently suppresses innate and adaptive activation inhibiting LPS- or UV-inactivated RSV-induced maturation of mouse bone marrow-derived dendritic cells, reducing antigen-specific CD4+ T cell proliferation and IFN-{gamma} production, and attenuating multiple human neutrophil responses (chemotaxis, CD11b upregulation, ROS, MPO release and NET formation), without cytotoxicity. Oligomerized Gpep lacks these suppressive activities. To link molecular mechanism and human exposure, analysis of sera from an ambulatory pediatric cohort (0-72 months) showed a progressive transient increase in the anti-F/anti-G IgG ratio with repeated early RSV exposures, maturating into a functional 2 to 3 ratio. This serologic shift is consistent with previously reported enrichment of F-directed neutralizing immunity. We propose a redox-dependent immune-evasion model in which soluble, monomeric G mediates transient immunosuppression that is removed by disulfide-driven oligomerization, which may occur in membrane-bound G. This may impact therapeutic strategies that commonly favor F-focused responses. ImportanceRespiratory syncytial virus (RSV) remains a leading cause of severe respiratory disease in young children and high-risk adults. This study identifies a chemical switch in a small conserved region of the RSV attachment protein that changes its shape and immune activity: when the region is present as a soluble, single chain, it transiently suppresses key innate and adaptive immune cells, but this activity is lost upon disulfide-mediated oligomerization. We also show that repetitive RSV exposures in early life bias the antibody response, initially boosting antibody responses toward the Fusion protein, rather than this conserved central region. Together, these results may uncover a mechanism by which RSV shapes the host immune response explaining the features of antibody development in children. Understanding this redox-dependent balance between immune evasion and antigenicity will inform safer vaccine and antibody strategies against RSV.

immunology↗

bioRxiv2024

The RNA from Pseudomonas aeruginosa impairs neutrophil responses favoring bacterial survival

Epithelial and endothelial cells are essential in the modulation of innate immune responses in the lung, including the arrival of neutrophils (PMN), which are crucial cells for the antibacterial host defense. These cells are exposed to prokaryotic RNA (pRNA) during bacterial infections and pRNA has been shown to promote or attenuate the inflammatory response on different immune cells. Pseudomonas aeruginosa (PAE) can cause severe pneumonia and has several immune-evading mechanisms. The aim of this study was to determine the effects of the RNA from PAE (RNAPAE) on lung epithelial, endothelial cells and PMN, and its impact on bacterial elimination. For this purpose, we purified total RNAPAE, and used it as a stimulus to evaluate different functions on Calu-6, HMEC-1 and isolated human PMN. We found that RNAPAE neither induced a pro-inflammatory response on Calu-6 or HMEC-1, as measured by ICAM-1 surface expression, or IL-6 and IL-8 secretion. Also, RNAPAE failed to activate PMN, as measured by forward-scatter (FSC) increase, CD11b surface expression, chemotaxis and IL-8 secretion. Pre-stimulation with RNAPAE diminished CD11b surface expression, chemotaxis and microbicidal activity when PMN were challenged with live bacteria. Moreover, we found that phagocytosis was affected in the presence of RNAPAE. Fragments of short RNA (<200 bp) were responsible for the PMN microbicidal attenuation during bacterial elimination. In conclusion, our results indicated that short fragments of RNAPAE diminished the immune response on PMN even in the presence of live bacteria. AUTHOR SUMMARYPseudomonas aeruginosa (PAE) pneumonia constitutes a major problem for human health. Therapies are frequently inefficient due to immune evasion mechanisms of PAE. Therefore, it is imperative to understand the relationship between PAE (or its components) with the immune system to improve therapeutic strategies. Since some bacterial RNA are immunosuppressive, our hypothesis was that the RNA from PAE (RNAPAE) might negatively modulate the immune response in a lung infection. We investigated the effects of the RNAPAE on lung epithelial, and microvascular endothelial cells, central cells that respond to PAE early during infection, and on neutrophils (PMN), the first immune cell that arrives at the site of infection. We found that RNAPAE failed to induce any response on pulmonary epithelium, endothelium, or PMN. Moreover, RNAPAE-treated PMN showed reduced migration, activation, and bactericidal response against live bacteria. Exploring deeper into this phenomenon, we found that increased bacterial survival was due to a lower phagocytic capacity of RNAPAE-treated PMN. Our results indicate that RNAPAE may act as another evasion strategy to favor PAEs survival in a pulmonary infection. Understanding the mechanisms by which PAE reduces the response of cells that participate in pulmonary immunity is crucial for planning interventions that may benefit infected patients.

immunology↗

bioRxiv2021

Effects of bacterial lipopolysaccharide and Shiga Toxin on induced Pluripotent Stem Cell-derived Mesenchymal Stem Cells

BackgroundMesenchymal Stem Cells can be activated and respond to different bacterial toxins. Lipopolysaccharides (LPS) and Shiga Toxin (Stx) are the two main bacterial toxins present in Hemolytic Uremic Syndrome (HUS) that cause endothelial damage. In this work we aimed to study the response of iPSC-MSC to LPS and/or Stx and its effect on the restoration of injured endothelial cells. MethodsiPSC-MSC were used as a source of mesenchymal stem cells (MSC) and Human Microvascular Endothelial Cells-1 (HMEC-1) as a source of endothelial cells. iPSC-MSC were treated or not with LPS and/or Stx. For some experiments, Conditioned Media (CM) were collected from each plate and incubated with an anti-Stx antibody to block the direct effect of Stx, or Polymyxin to block the direct effect of LPS. In CM from both treatments, anti-Stx and Polymyxin were used. Results are expressed as mean {+/-} S.E.M. Significant differences (p<0.05) were identified using one way analysis of variance (ANOVA) and Bonferronis Multiple comparison test. ResultsThe results obtained showed that LPS induced a pro-inflammatory profile on iPSC-MSC, but not Stx, even though they expressed Gb3 receptor. Moreover, LPS induced on iPSC-MSC an increment in migration and adhesion to gelatin substrate. Also, the addition of CM of iPSC-MSC treated with LPS+Stx, decreased the capacity of HMEC-1 to close a wound, and did not favor the formation of new tubes. Proteomic analysis of iPSC-MSC treated with LPS and/or Stx revealed specific protein secretion patterns that support many of the functional results described here. ConclusionsIn conclusion, these results suggest that iPSC-MSC activated by LPS acquired a pro-inflammatory profile that induces migration and adhesion to extracellular matrix proteins (ECM), but the combination LPS+Stx decreased the repair of endothelial damage. The importance of this work is that it provides knowledge to understand the context in which iPSC-MSC could benefit or not the restoration of tissue injury, taking into account that the inflammatory context in response to a particular bacterial toxin is relevant for iPSC-MSC immunomodulation.

immunology↗