Dataset Information

Transepithelial Barrier Dysfunction Drives Microbiota Dysbiosis to Initiate Epithelial Clock-driven Inflammation.

ABSTRACT:

Background

Factors that contribute to inflammatory bowel disease [IBD] pathogenesis include genetic polymorphisms, barrier loss, and microbial dysbiosis. A major knowledge gap exists in the origins of the colitogenic microbiome and its relationship with barrier impairment. Epithelial myosin light chain kinase [MLCK] is a critical regulator of the paracellular barrier, but the effects of MLCK activation on the intraepithelial bacteria [IEB] and dysbiosis are incompletely understood. We hypothesise that MLCK-dependent bacterial endocytosis promotes pathobiont conversion and shapes a colitogenic microbiome.

Methods

To explore this, transgenic [Tg] mice with barrier loss induced by intestinal epithelium-specific expression of a constitutively active MLCK were compared with wild-type [WT] mice.

Results

When progeny of homozygous MLCK-Tg mice were separated after weaning by genotype [Tg/Tg, Tg/WT, WT/WT], increased IEB numbers associated with dysbiosis and more severe colitis were present in Tg/Tg and Tg/WT mice, relative to WT/WT mice. Cohousing with MLCK-Tg mice induced dysbiosis, increased IEB abundance, and exacerbated colitis in WT mice. Conversely, MLCK-Tg mice colonised with WT microbiota at birth displayed increased Escherichia abundance and greater colitis severity by 6 weeks of age. Microarray analysis revealed circadian rhythm disruption in WT mice co-housed with MLCK-Tg mice relative to WT mice housed only with WT mice. This circadian disruption required Rac1/STAT3-dependent microbial invasion but not MLCK activity, and resulted in increased proinflammatory cytokines and glucocorticoid downregulation.

Conclusions

The data demonstrate that barrier dysfunction induces dysbiosis and expansion of invasive microbes that lead to circadian disruption and mucosal inflammation. These results suggest that barrier-protective or bacterium-targeted precision medicine approaches may be of benefit to IBD patients.

SUBMITTER: Pai YC

PROVIDER: S-EPMC10588795 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Publications

Transepithelial Barrier Dysfunction Drives Microbiota Dysbiosis to Initiate Epithelial Clock-driven Inflammation.

Pai Yu-Chen YC Li Yi-Hsuan YH Turner Jerrold R JR Yu Linda Chia-Hui LC

Journal of Crohn's & colitis 20231001 9

<h4>Background</h4>Factors that contribute to inflammatory bowel disease [IBD] pathogenesis include genetic polymorphisms, barrier loss, and microbial dysbiosis. A major knowledge gap exists in the origins of the colitogenic microbiome and its relationship with barrier impairment. Epithelial myosin light chain kinase [MLCK] is a critical regulator of the paracellular barrier, but the effects of MLCK activation on the intraepithelial bacteria [IEB] and dysbiosis are incompletely understood. We hy ...[more]

PMID: 37004200

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Project description:Lung inflammation induced by Mycoplasma hyorhinis infection accounts for significant economic losses in the swine industry. Increasing evidence suggests that there is cross talk between the lungs and the gut, but little is known about the effect of the lung inflammation caused by M. hyorhinis infection on gut microbiota and intestinal barrier function. Here, we investigated changes in the fecal microbiotas of pigs with M. hyorhinis infection and the microbial regulatory role of such infection in intestinal barrier function. We infected pigs with M. hyorhinis and performed 16S rRNA gene sequencing analyses of fecal samples, data-independent acquisition (DIA) quantitative proteomic analyses of intestinal mucosa, and analyses of barrier dysfunction indicators in serum. We found that pigs with M. hyorhinis infection exhibit lung and systemic inflammation, as reflected by the histopathological changes and activation of the TLR4/MyD88/NF-κB p65 signaling pathway in lung tissue, as well as the increased concentrations of serum inflammatory cytokines. Gut microbiotas tended to become disturbed, as evidenced by the enrichment of opportunistic pathogens. The increased diamine oxidase activities and d-lactate concentrations in serum and the decreased relative mRNA expression of Occludin, ZO-1, and Mucin2 indicated the impairment of intestinal barrier function. Quantitative proteomic analyses showed a variety of altered proteins involved in immunomodulatory and inflammatory functions. There was a positive correlation between the abundance of opportunistic pathogens and inflammatory-cytokine concentrations, as well as intestinal immunomodulatory proteins. Our results suggest that lung inflammation induced by M. hyorhinis infection can contribute to the dysbiosis of gut microbiota and intestinal barrier dysfunction, and dysbiosis of gut microbiota was associated with systemic inflammation and intestinal immune status. IMPORTANCE Cumulative evidence suggests that bacterial pneumonia may contribute to the dysbiosis of the gut microbiota and other gastrointestinal symptoms. Our experiment has demonstrated that lung inflammation induced by M. hyorhinis infection was associated with gut microbiota dysbiosis and intestinal barrier dysfunction, which may provide a theoretical basis for exploring the gut-lung axis based on M. hyorhinis infection.

Project description:BackgroundElevation of the transcription factor HIF-1 is a prominent mediator of not only processes that accompany hypoxia, but also the tumor microenvironment and tissue regeneration. This study uses mediators of "chemical hypoxia" to ask the question whether HIF-1α elevation in a healthy epithelial cell layer leads to leakiness in its tight junctional seals.MethodsTransepithelial electrical resistance and transepithelial diffusion of 14C-D-mannitol and other radiolabeled probes are used as indicators of transepithelial barrier function of CaCo-2 BBe human gastrointestinal epithelial cell layers cultured on permeable supports. Western immunoblot analyses of integral tight junctional proteins (occludin and claudins) are used as further indicators of barrier function change.ResultsCobalt, an inhibitor of the prolyl hydroxylase enzymes governing HIF-1α breakdown in the cell, induces transepithelial leakiness in CaCo-2 BBe cell layers in a time and concentration-dependent manner. This increased leakiness is accompanied by significant changes in certain specific integral tight junctional (TJ) proteins such as a decreased level of occludin and increased level of claudin-5. Similar results regarding barrier function compromise also occur with other chemical inhibitors of HIF-1α breakdown, namely ciclopiroxolamine (CPX) and dimethyloxalylglycine (DMOG). The increased leak is manifested by both decreased transepithelial electrical resistance (Rt) and increased paracellular diffusion of D-mannitol (Jm). The induced transepithelial leak shows significant size selectivity, consistent with induced effects on TJ permeability. Less-differentiated cell layers were significantly more affected than well-differentiated cell layers regarding induced transepithelial leak. A genetically modified CaCo-2 variant with reduced levels of HIF-1β, showed reduced transepithelial leak in response to cobalt exposure, further indicating that elevation of HIF-1α levels induced by agents of "chemical hypoxia" is responsible for the compromised barrier function of the CaCo-2 BBe cell layers.ConclusionsExposure to inducers of chemical hypoxia elevated HIF-1α levels and increased transepithelial leak. The degree of epithelial differentiation has significant effects on this action, possibly explaining the varying effects of HIF-1 modulation in epithelial and endothelial barrier function in different physiological and pathophysiological conditions.

Dataset Information

Transepithelial Barrier Dysfunction Drives Microbiota Dysbiosis to Initiate Epithelial Clock-driven Inflammation.

Background

Methods

Results

Conclusions

Publications

Transepithelial Barrier Dysfunction Drives Microbiota Dysbiosis to Initiate Epithelial Clock-driven Inflammation.

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