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A SNP of bacterial blc disturbs gut lysophospholipid homeostasis and induces inflammation through epithelial barrier disruption.

ABSTRACT: BACKGROUND:Alteration of commensal bacterial composition is associated with many inflammatory diseases. However, few studies have pinpointed the specific bacterial genes that may suppress host immune responses against microbes and maintain homeostasis in the host intestine. METHODS:High-throughput screening was performed in Caenorhabditis elegans with a single gene knockout ut screening was performed in Caenorhabditis elegans with a single gene knockout Escherichia coli (E. coli) library and identified the immune suppression gene blc. The coding sequences of blc among different kinds of E. coli strains were aligned to identify the single nucleotide polymorphisms (SNPs). Physiological and biochemical experiments were performed in C. elegans and mice to explore the function of the blc variant. FINDINGS:By screening 3983 E. coli mutants, we discovered that 9 bacterial genes, when deleted, activate innate immunity in the host C. elegans. Among these 9 genes, the gene encoding blc showed a distinctive SNP in many clinically pathogenic bacteria. We found that bacteria with this SNP, which converts Blc G84 to Blc E84, are highly enriched in the faeces of patients with inflammatory bowel disease (IBD). Exposure to BlcE84-encoding bacteria resulted in epithelial barrier disruption and immune activation in both worms and mice. Detailed analysis indicated that infection with BlcE84-encoding bacteria causes a significant decrease in LPE levels in the intestine and subsequently disrupts gut epithelial integrity in mice. Consistently, the levels of LPE in patients with IBD are significantly lower than those in healthy people. Finally, supplementation with LPE, which activates LPA1/PLC?/PKC signaling, reversed the defects induced by BlcE84-encoding bacteria. INTERPRETATION:Our results identified a novel bacterial gene, blc, in E. coli that regulates host gut integrity and immunity. FUND: The Ministry of Science and Technology of China; the National Natural Science Foundation of China; and the Natural Science Foundation of Jiangsu Province.

SUBMITTER: Zou D

PROVIDER: S-EPMC7026729 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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A SNP of bacterial blc disturbs gut lysophospholipid homeostasis and induces inflammation through epithelial barrier disruption.

Zou Dayuan D Pei Jingwen J Lan Jianfeng J Sang Hong H Chen Hongjuan H Yuan Haoliang H Wu Di D Zhang Yuanyuan Y Wang Yufang Y Wang Dingyu D Zou Yujie Y Chen Di D Ren Jianan J Gao Xiang X Lin Zhaoyu Z

EBioMedicine 20200212

<h4>Background</h4>Alteration of commensal bacterial composition is associated with many inflammatory diseases. However, few studies have pinpointed the specific bacterial genes that may suppress host immune responses against microbes and maintain homeostasis in the host intestine.<h4>Methods</h4>High-throughput screening was performed in Caenorhabditis elegans with a single gene knockout ut screening was performed in Caenorhabditis elegans with a single gene knockout Escherichia coli (E. coli) ...[more]

PMID: 32058942

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Project description:Introduction Disruption of the epithelial barrier can induce eosinophilic esophagitis (EoE), a TH2-mediated food- and aeroallergen associated chronic inflammatory disease 1, 2. The expression of IL-20 subfamily cytokines, IL-19, IL-20 and IL-24, is increased in TH2-mediated diseases, yet their function in EoE is unknown. Methods Combining RNA-sequencing (RNA-seq) and proteome analysis, we have examined the effects of the IL-20 subfamily on esophageal epithelial cells using patient-derived organoids and an experimental EoE mouse model. Results When stimulated with IL-20 subfamily cytokines patient-derived esophageal organoids showed decreased expression of Filaggrin (FLG) and Filaggrin 2 (FLG2) responsible for epithelial cornification. In agreement, EoE patients with active inflammation showed elevated IL-20 subfamily cytokines and decreased FLG and FLG2 expression. Topical corticosteroid treatment in EoE patients restored filaggrin expression, while reducing IL-20 subfamily cytokines. Abolishment of IL-20 subfamily signalling in Il20R2-/- animals attenuated experimental EoE in an OVA-induced mouse model. In the esophageal keratinocyte cell line, KYSE-180, we identified IL-20 subfamily-induced STAT3 and MAPK (ERK1/2) pathway activation. However, Stat3fl/flKrt5cre mice with an epithelium specific deletion of Stat3 developed exacerbated experimental EoE with a pronounced decrease of Flg2. In line, combined stimulation of patient-derived esophageal organoids with IL-20 subfamily cytokines and pharmacological inhibition of STAT3 resulted in aggravated decrease of FLG and FLG2. In addition, pharmacological STAT3 inhibition resulted in reduced transepithelial electrical resistance (TEER) and increased macromolecular flux in patient-derived air liquid interface (ALI) cultures. Whereas, inhibition of the MAPK (ERK1/2) pathway hampered IL-20 subfamily induced TEER reduction and paracellular flux increment. Finally, MAPK (ERK1/2) inhibitor treatment reduced infiltrating CD45+ immune cells in the esophagus and alleviated experimental EoE in mice. Conclusion We discovered a novel regulatory function of the IL-20 subfamily for epithelial barrier integrity. Aberrant IL-20 subfamily signaling disturbs the epithelial barrier function, while abrogation of IL-20 subfamily and ERK1/2 signaling restores epithelial integrity and attenuates experimental EoE. Therefore, we propose that targeting the IL-20 subfamily pathway could present a novel therapeutic strategy for EoE treatment.

Project description:HIV causes rapid CD4+ T cell depletion in the gut mucosa, resulting in immune deficiency and defects in the intestinal epithelial barrier. Breakdown in gut barrier integrity is linked to chronic inflammation and disease progression. However, the early effects of HIV on the gut epithelium, prior to the CD4+ T cell depletion, are not known. Further, the impact of early viral infection on mucosal responses to pathogenic and commensal microbes has not been investigated. We utilized the SIV model of AIDS to assess the earliest host-virus interactions and mechanisms of inflammation and dysfunction in the gut, prior to CD4+ T cell depletion. An intestinal loop model was used to interrogate the effects of SIV infection on gut mucosal immune sensing and response to pathogens and commensal bacteria in vivo. At 2.5 days post-SIV infection, low viral loads were detected in peripheral blood and gut mucosa without CD4+ T cell loss. However, immunohistological analysis revealed the disruption of the gut epithelium manifested by decreased expression and mislocalization of tight junction proteins. Correlating with epithelial disruption was a significant induction of IL-1? expression by Paneth cells, which were in close proximity to SIV-infected cells in the intestinal crypts. The IL-1? response preceded the induction of the antiviral interferon response. Despite the disruption of the gut epithelium, no aberrant responses to pathogenic or commensal bacteria were observed. In fact, inoculation of commensal Lactobacillus plantarum in intestinal loops led to rapid anti-inflammatory response and epithelial tight junction repair in SIV infected macaques. Thus, intestinal Paneth cells are the earliest responders to viral infection and induce gut inflammation through IL-1? signaling. Reversal of the IL-1? induced gut epithelial damage by Lactobacillus plantarum suggests synergistic host-commensal interactions during early viral infection and identify these mechanisms as potential targets for therapeutic intervention.

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A SNP of bacterial blc disturbs gut lysophospholipid homeostasis and induces inflammation through epithelial barrier disruption.

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A SNP of bacterial blc disturbs gut lysophospholipid homeostasis and induces inflammation through epithelial barrier disruption.

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