Duganhaas7339

Phagocytosis is the key mechanism for host control of Pseudomonas aeruginosa, a motile gram-negative, opportunistic bacterial pathogen, which frequently undergoes adaptation and selection for traits that are advantageous for survival. One such clinically relevant adaptation is the loss of bacterial motility, observed within chronic infections, that is associated with increased antibiotic tolerance and phagocytic resistance. Previous studies using phagocytes from a Leukocyte Adhesion Deficiency type 1 (LAD-I) patient identified CD18 as a putative cell-surface receptor for uptake of live P. aeruginosa However, how bacterial motility alters direct engagement with CD18-containing integrins remains unknown. Here we demonstrate, with the use of motile and isogenic non-motile deletion mutants of two independent strains of P. aeruginosa and with CRISPR-generated CD18-deficient cell lines in human monocytes and murine neutrophils, that CD18 expression facilitates the uptake of both motile and non-motile P. aeruginosa However, unexpectedly, mechanistic studies revealed that CD18 expression was dispensable for initial attachment of the bacteria to the host cells, which was validated with ectopic expression of CR3 by CHO cells. Our data support that surface N-glycans likely facilitate the initial interaction of bacteria with monocytes and co-operate with CD18 integrins in trans to promote internalization of bacteria. Moreover, talin-1 and kindlin-3 proteins promote uptake, but not binding, of P. aeruginosa by murine neutrophils which supports a role for CD18 integrin signaling in this process. These findings provide novel insights into the cellular determinants for phagocytic recognition and uptake of P. aeruginosa. Copyright © 2020 American Society for Microbiology.Cellular membrane proteins are a critical part of the host defense mechanisms against infection and intracellular survival of Listeria monocytogenes The complex spatiotemporal regulation of bacterial infection by various membrane proteins has been challenging to study. Here, using mass spectrometry analyses, we depicted the dynamic expression landscape of membrane proteins upon L. monocytogenes infection in dendritic cells. We showed that Dynein light chain 1 (Dynll1) formed a persistent complex with the mitochondrial cytochrome oxidase, Cox4i1 that is disturbed by pathogen insult. We discovered that the dissociation of the Dynll1-Cox4i1 complex is required for the release of mitochondrial reactive oxygen species and serves as a regulator of intracellular proliferation of Listeria monocytogenes Our study shows that Dynll1 is an inhibitor of mitochondrial reactive oxygen species and can serve as a potential molecular drug target for antibacterial treatment. Copyright © 2020 Yuan et al.Bacterial populations are phenotypically heterogeneous, which allows subsets of cells to survive and thrive following changes in environmental conditions. For bacterial pathogens, changes within the host environment occur over the course of the immune response to infection, and can result in exposure to host-derived, secreted antimicrobials, or force direct interactions with immune cells. Many recent studies have shown host cell interactions promote virulence factor expression, forcing subsets of bacterial cells to battle the host response, while other bacteria reap the benefits of this pacification. It still remains unclear whether virulence factor expression is truly energetically costly within host tissues, and whether expression is sufficient to impact the growth kinetics of virulence factor-expressing cells. However, it is clear that slow-growing subsets of bacteria emerge during infection, and that these subsets are particularly difficult to eliminate with antibiotics. This MiniReview will focus on our current understanding of heterogenous virulence factor expression, and discuss the evidence that supports or refutes the hypothesis that virulence factor expression is linked to slowed growth and antibiotic tolerance. Copyright © 2020 American Society for Microbiology.Mucosal-associated invariant T (MAIT) cells are a type of innate lymphocyte and recognize riboflavin (vitamin B2) synthesis products presented by MHC-related protein 1. We investigated long-term reconstitution of MAIT cells and its association with chronic graft-versus-host disease (cGVHD) in a cross-sectional cohort of 173 adult patients after allogeneic hematopoietic cell transplantation. According to donor source, the number of MAIT cells significantly correlated with time after cord blood transplantation (CBT) but not with time after bone marrow transplantation or peripheral blood stem cell transplantation. selleck chemicals llc The number of MAIT cells was significantly lower in patients with cGVHD compared with patients without cGVHD. We also examined the association between MAIT cell reconstitution and gut microbiota as evaluated by 16S ribosomal sequencing of stool samples 1 mo post-CBT in 27 adult patients undergoing CBT. The diversity of gut microbiota was positively correlated with better MAIT cell reconstitution after CBT. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis indicated that amounts of ribB and ribA genes were significantly higher in the microbiomes of patients with subsequent MAIT cell reconstitution after CBT. In conclusion, long-term MAIT cell reconstitution is dependent on the type of donor source. Our data also unveiled an important role for the interaction of circulating MAIT cells with gut microbiota in humans. Copyright © 2020 by The American Association of Immunologists, Inc.4-1BBL, a member of the TNF superfamily, regulates the sustained production of inflammatory cytokines in macrophages triggered by TLR signaling. In this study, we have investigated the role of 4-1BBL in macrophage metabolism and polarization and in skin inflammation using a model of imiquimod-induced psoriasis in mice. Genetic ablation or blocking of 4-1BBL signaling by Ab or 4-1BB-Fc alleviated the pathology of psoriasis by regulating the expression of inflammatory cytokines associated with macrophage activation and regulated the polarization of macrophages in vitro. We further linked this result with macrophage by finding that 4-1BBL expression during the immediate TLR response was dependent on glycolysis, mitochondrial oxidative phosphorylation, and fatty acid metabolism, whereas the late-phase 4-1BBL-mediated sustained inflammatory response was dependent on glycolysis and fatty acid synthesis. Correlating with this, administration of a fatty acid synthase inhibitor, cerulenin, also alleviated the pathology of psoriasis.