Bifidobacterium dentium-derived y-glutamylcysteine suppresses ER-mediated goblet cell stress and reduces TNBS-driven colonic inflammation

Abstract

Endoplasmic reticulum (ER) stress compromises the secretion of MUC2 from goblet cells and has been linked with inflammatory bowel disease (IBD). Although Bifidobacterium can beneficially modulate mucin production, little work has been done investigating the effects of Bifidobacterium on goblet cell ER stress. We hypothesized that secreted factors from Bifidobacterium dentium downregulate ER stress genes and modulates the unfolded protein response (UPR) to promote MUC2 secretion. We identified by mass spectrometry that B. dentium secretes the antioxidant γ-glutamylcysteine, which we speculate dampens ER stress-mediated ROS and minimizes ER stress phenotypes. B. dentium cell-free supernatant and γ-glutamylcysteine were taken up by human colonic T84 cells, increased glutathione levels, and reduced ROS generated by the ER-stressors thapsigargin and tunicamycin. Moreover, B. dentium supernatant and γ-glutamylcysteine were able to suppress NF-kB activation and IL-8 secretion. We found that B. dentium supernatant, γ-glutamylcysteine, and the positive control IL-10 attenuated the induction of UPR genes GRP78, CHOP, and sXBP1. To examine ER stress in vivo, we first examined mono-association of B. dentium in germ-free mice which increased MUC2 and IL-10 levels compared to germ-free controls. However, no changes were observed in ER stress-related genes, indicating that B. dentium can promote mucus secretion without inducing ER stress. In a TNBS-mediated ER stress model, we observed increased levels of UPR genes and pro-inflammatory cytokines in TNBS treated mice, which were reduced with addition of live B. dentium or γ-glutamylcysteine. We also observed increased colonic and serum levels of IL-10 in B. dentium-and γ-glutamylcysteine-treated mice compared to vehicle control. Immunostaining revealed retention of goblet cells and mucus secretion in both B. dentium-and γ-glutamylcysteine-treated animals. Collectively, these data demonstrate positive modulation of the UPR and MUC2 production by B. dentium-secreted compounds.

Bacteroides acidifaciens in the gut plays a protective role against CD95-mediated liver injury

“… 34 GSH is directly or indirectly synthesized by intestinal bacteria or the liver itself. 33 , 68–70 The present study found that BA administration in mice decreased the hepatic GSSG/GSH ratio. GSH also significantly inhibited CD95 expression and alleviated ConA-induced liver injury in vitro and in vivo.…”

“… 32 Some precursor metabolites from intestinal bacteria may affect glutathione (GSH) levels. 33 GSH administration attenuates CD95-mediated hepatic apoptosis and injury in mice. 34 The metabolites, and the intestinal bacteria that produce them, play a vital role in the “liver-gut interaction” and need to be further explored.…”

Native and Engineered Probiotics: Promising Agents against Related Systemic and Intestinal Diseases

“…In IBD mediated by pathogenic bacteria, they have been proven to regulate the tight junction of Caco-2 cells [ 123 ], counteract Adherent-Invasive Escherichia coli virulence in CD patients, and reduce the secretion of cytokines related to the IL-23/Th17 axis in UC patients [ 124 ]. Furthermore, secreted factors from Bifidobacterium dentium can also down-regulate the endoplasmic reticulum stress gene and regulate the unfolded protein response to promote MUC2 secretion [ 125 ].…”

Mathematical models to study the biology of pathogens and the infectious diseases they cause

“…bile acids/salts, amino acids and biogenic amines, short-chain fatty acids, and neurotransmitters) in a number of in vitro and in vivo models. Metabolomics measurements can be made on growth media collected from in vitro or ex vivo culture systems used to grow microbes or intestinal organoids ( Engevik et al., 2021a , 2021b , 2021c ; Horvath et al., 2020 ; Ihekweazu et al., 2021 ; Luck et al., 2021 ). There is an increasing number of protocols for metabolomics using extracts of cecal content and fecal samples, and homogenized gastrointestinal tract and brain tissues harvested from gnotobiotic mice ( Engevik et al., 2021a , 2021b , 2021c ; Horvath et al., 2020 ; Ihekweazu et al., 2021 ; Luck et al., 2021 ).…”