Biology subjects

Zychlinsky, A.

Publications and source records attributed to Zychlinsky, A..

5 recordsLinked to original sources

bioRxiv2025

The DanRI regulatory system in uropathogenic Escherichia coli subverts neutrophil responses

Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infections (UTI). To establish an infection, UPEC must evade infiltrating neutrophils and their antimicrobial neutrophil extracellular traps (NETs). In this study, we identify a previously uncharacterized two-gene regulatory system within the pathogenicity island PAIUTI89II, which we named DanRI (Defense against neutrophil Regulator and Inhibitor). DanRI is induced by nucleosomes present in NETs and enables UPEC to suppress neutrophil responses by attenuating reactive oxygen species production and NET formation. Mechanistically, DanI functions as an antagonist to the transcriptional regulator DanR, thereby modulating key bacterial processes, including metabolic processes, flagellar biosynthesis, and stress response pathways. DanRI is required for UPEC fitness and long-term persistence in a mouse model of UTI. Taken together, our findings reveal DanRI as a novel regulatory system that promotes UPEC pathogenesis through immune evasion. Graphical abstract and model O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/658900v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@19095e6org.highwire.dtl.DTLVardef@1613c26org.highwire.dtl.DTLVardef@b415c3org.highwire.dtl.DTLVardef@100b79e_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2023

Myeloperoxidase-dependent tyrosine halogenation potentiates alpha-defensins functions

Neutrophils are immune cells that eliminate microbes using a powerful arsenal of reactive oxygen species, hypohalous acids, proteases, and antimicrobial peptides -- yet how these cytotoxic effectors act in concert remains poorly understood. Here, we identify an unrecognized synergy between oxidative and non-oxidative neutrophil defenses. We show that myeloperoxidase-derived hypohalous acids selectively halogenate -defensins (HNP1-3) at conserved tyrosine residues. This post-translational modification occurs in both human and rat neutrophils and is prominent in diseases marked by neutrophil-rich inflammation, including cystic fibrosis, bacterial pneumonia, and Staphylococcus aureus abscesses. Halogenation increases HNP1 hydrophobicity without altering its structure, reprogramming these peptides into potent immunomodulatory mediators. Using single-cell transcriptomics and a in vivo peritonitis model, we demonstrate that halogenated HNP1s amplify immune signaling. Our analysis of the human haloproteome reveals a novel oxidative mechanism by which hypohalous acids rewire immune protein functions, uncovering an unexpected layer of cooperation between neutrophil effector systems. The discovery of halogenated HNP1s represents, to our knowledge, the first characterization of a protein halogenation that has biologically significance in human immunity.

biochemistry↗

bioRxiv2021

Patients with recurrent PVL+-Staphylococcus aureus infections show enhanced sensitivity to PVL-mediated formation of atypical NETs

Staphylococcus aureus (S. aureus) strains that produce the toxin Panton-Valentine leukocidin (PVL; PVL-SA) frequently cause recurrent skin and soft tissue infections (SSTI). PVL binds to and kills human neutrophils, resulting in the formation of neutrophil extracellular traps, but the pathomechanism has not been extensively studied. Furthermore, it is unclear why some individuals colonized with PVL-SA suffer from recurring infections whereas others are asymptomatic. We thus aimed to (a) investigate how PVL exerts its pathogenicity on neutrophils and (b) identify factors that could help to explain the predisposition of patients with recurring infections. We provide genetic and pharmacological evidence that PVL-induced NET formation is independent of NADPH-oxidase and reactive oxygen species (ROS) production. Moreover, through NET proteome analysis we identified that the protein content of PVL-induced NETs is different from NETs induced by mitogen or the microbial toxin nigericin. The abundance of the proteins cathelicidin (CAMP), elastase (NE), and proteinase 3 (PRTN3) was lower on PVL-induced NETs, and as such they were unable to kill S. aureus. Furthermore, we found that neutrophils from affected patients express higher levels of CD45, one of the PVL receptors, and are more susceptible to be killed at a low PVL concentration than control neutrophils. Neutrophils from patients that suffer from recurring PVL-positive infections may thus be more sensitive to PVL-induced NET formation, which might impair their ability to combat the infection. ImportanceIndividuals colonized by Staphylococcus aureus strains that produce Panton-Valentine leukocidin (PVL-SA) often present with recurrent skin and soft-tissue infections, whilst other individuals remain asymptomatic. PVL is a toxin that kills neutrophils, which results in the formation of neutrophil extracellular traps. Traps induced by other stimuli are known to be toxic to S. aureus. We found however that NETs specifically induced by PVL are not toxic to S. aureus. Furthermore, we show that neutrophils from individuals that suffer from recurring PVL-SA infections are more sensitive to PVL-induced NET formation compared to healthy individuals. The significance of our work is in identifying a mechanism through which PVL-SA may actively counter the engagement of neutrophils. Moreover, we identified that patients with recuring PVL-SA infections may be more sensitive to this mechanism, which may help to explain their clinical condition and might provide avenues for future treatment development.

immunology↗

bioRxiv2021

Histone H3 Clipping is a novel signature of Human Neutrophil Extracellular Traps

Neutrophils are critical to host defence, executing diverse strategies to perform their antimicrobial and regulatory functions. One tactic is the production of neutrophil extracellular traps (NETs). In response to certain stimuli neutrophils decondense their lobulated nucleus and release chromatin into the extracellular space through a process called NETosis. However, NETosis, and the subsequent degradation of NETs, can become dysregulated. NETs are proposed to play a role in infectious as well as many non-infection related diseases including cancer, thrombosis, autoimmunity and neurological disease. Consequently, there is a need to develop specific tools for the study of these structures in disease contexts. In this study, we identified a NET-specific histone H3 cleavage event and harnessed this to develop a cleavage site-specific antibody for the detection of human NETs. By microscopy, this antibody distinguishes NETs from chromatin in purified and mixed cell samples. It also detects NETs in tissue sections. We propose this antibody as a new tool to detect and quantify NETs.

immunology↗

bioRxiv2019

Linker Histone H1 subtypes specifically regulate neutrophil differentiation

Neutrophils are important innate immune cells that tackle invading pathogens with different effector mechanisms. They acquire this antimicrobial potential during their maturation in the bone marrow, where they differentiate from hematopoietic stem cells in a process called granulopoiesis. Mature neutrophils are terminally differentiated and short-lived with a high turnover rate. Here, we show a critical role for linker histone H1 on the differentiation and function of neutrophils using a genome-wide CRISPR/Cas9 screen in the human cell line PLB-985. We systematically disrupted expression of somatic H1 subtypes to show that individual H1 subtypes affect PLB-985 maturation in opposite ways. Importantly, H1 subtypes also affect neutrophil differentiation of murine bone marrow stem cells, demonstrating an unexpected subtype-specific role for H1 in granulopoiesis.

immunology↗