lipoteichoic-acid and Inflammatory-Bowel-Diseases

Intestinal immune regulatory signals govern gut homeostasis. Breakdown of such regulatory mechanisms may result in inflammatory bowel disease (IBD). Lactobacillus acidophilus contains unique surface layer proteins (Slps), including SlpA, SlpB, SlpX, and lipoteichoic acid (LTA), which interact with pattern recognition receptors to mobilize immune responses. Here, to elucidate the role of SlpA in protective immune regulation, the NCK2187 strain, which solely expresses SlpA, was generated. NCK2187 and its purified SlpA bind to the C-type lectin SIGNR3 to exert regulatory signals that result in mitigation of colitis, maintenance of healthy gastrointestinal microbiota, and protected gut mucosal barrier function. However, such protection was not observed in Signr3(-/-) mice, suggesting that the SlpA/SIGNR3 interaction plays a key regulatory role in colitis. Our work presents critical insights into SlpA/SIGNR3-induced responses that are integral to the potential development of novel biological therapies for autoinflammatory diseases, including IBD.

Topics: Animals; Antigens, CD; Bacterial Proteins; Inflammatory Bowel Diseases; Intestinal Mucosa; Lactobacillus acidophilus; Lectins, C-Type; Lipopolysaccharides; Mice; Mice, Knockout; Protein Binding; Teichoic Acids

While some probiotic strains might have adjuvant effects in the therapy for inflammatory bowel diseases (IBD), these effects remain controversial and cannot be generalized. In this study, a dltD mutant of the model probiotic Lactobacillus rhamnosus GG (LGG), having a drastic modification in its lipoteichoic acid (LTA) molecules, was analysed for its effects in an experimental colitis model. Dextran sulphate sodium (DSS) was used to induce either moderate to severe or mild chronic colitis in mice. Mice received either phosphate-buffered saline (PBS), LGG wild-type or the dltD mutant via the drinking water. Macroscopic parameters, histological abnormalities, cytokine and Toll-like receptor (TLR) expression were analysed to assess disease activity. LGG wild-type did not show efficacy in the different experimental colitis set-ups. This wild-type strain even seemed to exacerbate the severity of colitic parameters in the moderate to severe colitis model compared to untreated mice. In contrast, mice treated with the dltD mutant showed an improvement of some colitic parameters compared to LGG wild-type-treated mice in both experimental models. In addition, treatment with the dltD mutant correlated with a significant down-regulation of Toll-like receptor-2 expression and of downstream proinflammatory cytokine expression in the colitic mice. These results show that molecular cell surface characteristics of probiotics are crucial when probiotics are considered for use as supporting therapy in IBD.

Topics: Animals; Bacterial Proteins; Body Weight; Colon; Colony Count, Microbial; Dextran Sulfate; Female; Gastric Juice; Gastrointestinal Tract; Gene Expression; Inflammatory Bowel Diseases; Interferon-gamma; Interleukin-12 Subunit p40; Intestinal Mucosa; Lacticaseibacillus rhamnosus; Lipopolysaccharides; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Microbial Viability; Models, Animal; Probiotics; Teichoic Acids; Thiolester Hydrolases; Toll-Like Receptors; Treatment Outcome

Intestinal myofibroblasts are known to respond to inflammatory signals and may play a role in Crohn's disease-associated fibrosis. However, putative involvement by myofibroblasts in innate immune responses as part of intestinal host defense has not been characterized. We therefore analyzed expression and regulation of toll-like receptors (TLRs) in colonic human myofibroblasts (CCD-18) and primary human colonic myofibroblasts in comparison with human lung myofibroblasts (CCD-37).. Expression of TLRs (1-10) and NOD 1 and 2 was assessed before and after stimulation with either lipopolysaccharide (LPS) or lipoteichoic acid (LTA) by using a custom microarray, reverse-transcription polymerase chain reaction, Northern blot and Western blot analysis, and immunohistochemistry. Activation of signaling pathways, translocation of p65, and secretion of interleukin (IL)-8 were determined.. Messenger RNAs encoding for TLR1-9, as well as NOD1 and NOD2, were amplified from cultured and primary human intestinal myofibroblasts. After stimulation with LPS or LTA, a 1.5-4.2-fold up-regulation of TLRs (2, 3, 4, 6, 7) and elements of the signaling cascade (MyD88, TIR domain-containing adapter protein [TIRAP]) was observed. CCD-18 and CCD-37 cells expressed TLR 2 and 4 protein, which were located primarily on the cell membrane. Stimulation with LTA or LPS resulted in activation of the mitogen-activated protein kinases pathway, nuclear translocation of p65, and significantly increased IL-8 secretion.. Bacterial components directly activate intestinal myofibroblasts expressing TLRs. These cells may therefore participate in innate immune responses by sensing and responding to bacterial products that have penetrated into the subepithelial compartment.

Topics: Cells, Cultured; Colon; Fibroblasts; Humans; Immunity, Innate; Inflammatory Bowel Diseases; Interleukin-8; Intestinal Mucosa; Lipopolysaccharides; Membrane Glycoproteins; Mitogen-Activated Protein Kinases; Oligonucleotide Array Sequence Analysis; Receptors, Cell Surface; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Teichoic Acids; Toll-Like Receptor 1; Toll-Like Receptor 2; Toll-Like Receptors