PGLYRP1-mediated intracellular peptidoglycan detection promotes intestinal mucosal protection.

Peptidoglycan recognition proteins (PGLYRPs) are implicated in the control of the intestinal microbiota; however, molecular requirements for peptidoglycan (PGN) binding and receptor signaling mechanisms remain poorly understood. Here we show that PGLYRP1 is a receptor for the disaccharide motif of lysine N-acetylglucosamine N-acetylmuramic tripeptide (GMTriP-K). PGLYRP1 is required for innate immune activation by GMTriP-K but not muramyl dipeptide (MDP).

Bacterial Peptidoglycan Fragments Differentially Regulate Innate Immune Signaling.

The human innate immune system responds to both pathogen and commensal bacteria at the molecular level using bacterial peptidoglycan (PG) recognition elements. Traditionally, synthetic and commercially accessible PG monosaccharide units known as muramyl dipeptide (MDP) and -glycolyl MDP (ng-MDP) have been used to probe the mechanism of innate immune activation of pattern recognition receptors, such as NOD-like receptors. However, bacterial PG is a dynamic and complex structure, with various chemical modifications and trimming mechanisms that result in the production of disaccharide-containing elements.

Vascular Patterning as Integrative Readout of Complex Molecular and Physiological Signaling by VESsel GENeration Analysis.

The molecular signaling cascades that regulate angiogenesis and microvascular remodeling are fundamental to normal development, healthy physiology, and pathologies such as inflammation and cancer. Yet quantifying such complex, fractally branching vascular patterns remains difficult. We review application of NASA's globally available, freely downloadable VESsel GENeration (VESGEN) Analysis software to numerous examples of 2D vascular trees, networks, and tree-network composites.

The persistence of interleukin-6 is regulated by a blood buffer system derived from dendritic cells.

The interleukin-6 (IL-6) membrane receptor and its circulating soluble form, sIL-6R, can be targeted by antibody therapy to reduce deleterious immune signaling caused by chronic overexpression of the pro-inflammatory cytokine IL-6. This strategy may also hold promise for treating acute hyperinflammation, such as observed in coronavirus disease 2019 (COVID-19), highlighting a need to define regulators of IL-6 homeostasis. We found that conventional dendritic cells (cDCs), defined in mice via expression of the transcription factor Zbtb46, were a major source of circulating sIL-6R and, thus, systemically regulated IL-6 signaling.

Hepatic gap junctions amplify alcohol liver injury by propagating cGAS-mediated IRF3 activation.

Alcohol-related liver disease (ALD) accounts for the majority of cirrhosis and liver-related deaths worldwide. Activation of IFN-regulatory factor (IRF3) initiates alcohol-induced hepatocyte apoptosis, which fuels a robust secondary inflammatory response that drives ALD. The dominant molecular mechanism by which alcohol activates IRF3 and the pathways that amplify inflammatory signals in ALD remains unknown.

T cell fate following infection is determined by a STING-IRF1 signaling axis in mice.

The innate immune response following infection with entero-invasive bacterial species is triggered upon release of cyclic di-guanylate monophosphate (c-di-GMP) into the host cell cytosol. Bacterial c-di-GMP activates the intracellular Sensor Stimulator of Interferon Genes (STING), encoded by in mice. Here we identify Interferon Regulatory Factor (IRF) 1 as a critical effector of STING-mediated microbial DNA sensing that is responsible for T17 cell generation in the mucosal immune system.

GEF-H1 Signaling upon Microtubule Destabilization Is Required for Dendritic Cell Activation and Specific Anti-tumor Responses.

Dendritic cell (DC) activation is a critical step for anti-tumor T cell responses. Certain chemotherapeutics can influence DC function. Here we demonstrate that chemotherapy capable of microtubule destabilization has direct effects on DC function; namely, it induces potent DC maturation and elicits anti-tumor immunity.

Microbial recognition by GEF-H1 controls IKKε mediated activation of IRF5.

During infection, transcription factor interferon regulatory factor 5 (IRF5) is essential for the control of host defense. Here we show that the microtubule-associated guanine nucleotide exchange factor (GEF)-H1, is required for the phosphorylation of IRF5 by microbial muramyl-dipeptides (MDP), the minimal structural motif of peptidoglycan of both Gram-positive and Gram-negative bacteria. Specifically, GEF-H1 functions in a microtubule based recognition system for microbial peptidoglycans that mediates the activation of IKKε which we identify as a new upstream IKKα/β and IRF5 kinase.

CXCR1 Macrophages and CD8 T Cells Control Intestinal IgA Production.

Secretory IgA is a key host defense mechanism that controls the intestinal microbiota. We investigated the role of CD11cCXCR1CD64 macrophages in IgA production in the intestine. Intestinal CXCR1 macrophages directly induced IgA secretion by B cells.

is a colitis risk gene that regulates stability of epithelial adherens junctions.

Polymorphisms in are associated with increased risk of inflammatory bowel disease (IBD). However, the function of C1orf106 and the consequences of disease-associated polymorphisms are unknown. Here we demonstrate that C1orf106 regulates adherens junction stability by regulating the degradation of cytohesin-1, a guanine nucleotide exchange factor that controls activation of ARF6.

Shigella depends on SepA to destabilize the intestinal epithelial integrity via cofilin activation.

Shigella is unique among enteric pathogens, as it invades colonic epithelia through the basolateral pole. Therefore, it has evolved the ability to breach the intestinal epithelial barrier to deploy an arsenal of effector proteins, which permits bacterial invasion and leads to a severe inflammatory response. However, the mechanisms used by Shigella to regulate epithelial barrier permeability remain unknown.

Reovirus infection triggers inflammatory responses to dietary antigens and development of celiac disease.

Viral infections have been proposed to elicit pathological processes leading to the initiation of T helper 1 (T1) immunity against dietary gluten and celiac disease (CeD). To test this hypothesis and gain insights into mechanisms underlying virus-induced loss of tolerance to dietary antigens, we developed a viral infection model that makes use of two reovirus strains that infect the intestine but differ in their immunopathological outcomes. Reovirus is an avirulent pathogen that elicits protective immunity, but we discovered that it can nonetheless disrupt intestinal immune homeostasis at inductive and effector sites of oral tolerance by suppressing peripheral regulatory T cell (pT) conversion and promoting T1 immunity to dietary antigen.

Induction and suppression of antiviral RNA interference by influenza A virus in mammalian cells.

Influenza A virus (IAV) causes annual epidemics and occasional pandemics, and is one of the best-characterized human RNA viral pathogens. However, a physiologically relevant role for the RNA interference (RNAi) suppressor activity of the IAV non-structural protein 1 (NS1), reported over a decade ago, remains unknown. Plant and insect viruses have evolved diverse virulence proteins to suppress RNAi as their hosts produce virus-derived small interfering RNAs (siRNAs) that direct specific antiviral defence by an RNAi mechanism dependent on the slicing activity of Argonaute proteins (AGOs).

Gliadin Induces Neutrophil Migration via Engagement of the Formyl Peptide Receptor, FPR1.

Background: Gliadin, the immunogenic component within gluten and trigger of celiac disease, is known to induce the production of Interleukin-8, a potent neutrophil-activating and chemoattractant chemokine. We sought to study the involvement of neutrophils in the early immunological changes following gliadin exposure.

Methods: Utilizing immunofluorescence microscopy and flow cytometry, the redistribution of major tight junction protein, Zonula occludens (ZO)-1, and neutrophil recruitment were assessed in duodenal tissues of gliadin-gavaged C57BL/6 wild-type and Lys-GFP reporter mice, respectively.

SLAMF4 Is a Negative Regulator of Expansion of Cytotoxic Intraepithelial CD8+ T Cells That Maintains Homeostasis in the Small Intestine.

Background & Aims: Intraepithelial T lymphocyte cells (IEL) are the first immune cells to respond to pathogens; they help maintain the integrity of the epithelial barrier. We studied the function of the mouse glycoprotein Signaling Lymphocyte Activation Molecule Family receptor (SLAMF) 4 (encoded by Slamf4) on the surface of CD8αβ αβ T-cell receptor (TCR)(+) IELs, and the roles of these cells in homeostasis of the small intestine in mice.

Methods: SLAMF4(-) CD8(+) αβTCR(+) cells isolated from spleens of OT-I Rag1(-/-) mice were induced to express gut-homing receptors and transferred to C57BL/6J mice; levels of SLAMF4(+) cells were measured in small intestine tissues.

Small-molecule screening identifies inhibition of salt-inducible kinases as a therapeutic strategy to enhance immunoregulatory functions of dendritic cells.

Genetic alterations that reduce the function of the immunoregulatory cytokine IL-10 contribute to colitis in mouse and man. Myeloid cells such as macrophages (MΦs) and dendritic cells (DCs) play an essential role in determining the relative abundance of IL-10 versus inflammatory cytokines in the gut. As such, using small molecules to boost IL-10 production by DCs-MΦs represents a promising approach to increase levels of this cytokine specifically in gut tissues.

Plasmacytoid dendritic cells mediate anti-inflammatory responses to a gut commensal molecule via both innate and adaptive mechanisms.

Polysaccharide A (PSA), the archetypical immunomodulatory molecule of the gut commensal Bacteroides fragilis, induces regulatory T cells to secrete the anti-inflammatory cytokine interleukin-10 (IL-10). The cellular mediators of PSA's immunomodulatory properties are incompletely understood. In a mouse model of colitis, we find that PSA requires both innate and adaptive immune mechanisms to generate protection.

Glucocorticoid-Induced TNF Receptor Family-Related Protein Ligand is Requisite for Optimal Functioning of Regulatory CD4(+) T Cells.

Glucocorticoid-induced tumor necrosis factor receptor family-related protein (TNFRSF18, CD357) is constitutively expressed on regulatory T cells (Tregs) and is inducible on effector T cells. In this report, we examine the role of glucocorticoid-induced TNF receptor family-related protein ligand (GITR-L), which is expressed by antigen presenting cells, on the development and expansion of Tregs. We found that GITR-L is dispensable for the development of naturally occurring FoxP3(+) Treg cells in the thymus.

GEF-H1 controls microtubule-dependent sensing of nucleic acids for antiviral host defenses.

Detailed understanding of the signaling intermediates that confer the sensing of intracellular viral nucleic acids for induction of type I interferons is critical for strategies to curtail viral mechanisms that impede innate immune defenses. Here we show that the activation of the microtubule-associated guanine nucleotide exchange factor GEF-H1, encoded by Arhgef2, is essential for sensing of foreign RNA by RIG-I-like receptors. Activation of GEF-H1 controls RIG-I-dependent and Mda5-dependent phosphorylation of IRF3 and induction of IFN-β expression in macrophages.

Individual quality of life in patients with multiple myeloma.

Objective: The situation of patients with multiple myeloma, whose treatment often implies high-dose chemotherapy and stem cell transplantation that can be associated with severe symptoms and psychological distress, has gained attention in recent psychooncological research. This study followed an idiographic approach in order to identify the areas of life most relevant for the interviewed myeloma patients' quality of life (QoL) as well as their current satisfaction with these.

Methods: 64 patients took part in semi-structured interviews according to the SEIQoL-DW Manual (Schedule for the Evaluation of Individual Quality of Life - Direct Weighting).

Atg16l1 is required for autophagy in intestinal epithelial cells and protection of mice from Salmonella infection.

Background & Aims: Intestinal epithelial cells aid in mucosal defense by providing a physical barrier against entry of pathogenic bacteria and secreting antimicrobial peptides (AMPs). Autophagy is an important component of immune homeostasis. However, little is known about its role in specific cell types during bacterial infection in vivo.

Chitin-binding domains of Escherichia coli ChiA mediate interactions with intestinal epithelial cells in mice with colitis.

Background & Aims: Inducible chitinase 3-like-1 is expressed by intestinal epithelial cells (IECs) and adheres to bacteria under conditions of inflammation. We performed a structure-function analysis of the chitin-binding domains encoded by the chiA gene, which mediates the pathogenic effects of adherent invasive Escherichia coli (AIEC).

Methods: We created AIEC (strain LF82) with deletion of chiA (LF82-ΔchiA) or that expressed chiA with specific mutations.

Probiotic yeast inhibits VEGFR signaling and angiogenesis in intestinal inflammation.

Background And Aims: Saccharomyces boulardii (Sb) can protect against intestinal injury and tumor formation, but how this probiotic yeast controls protective mucosal host responses is unclear. Angiogenesis is an integral process of inflammatory responses in inflammatory bowel diseases (IBD) and required for mucosal remodeling during restitution. The aim of this study was to determine whether Sb alters VEGFR (vascular endothelial growth factor receptor) signaling, a central regulator of angiogenesis.