Glucosylceramide production maintains colon integrity in response toBacteroides fragilistoxin‐induced colon epithelial cell signaling

Abstract

Enterotoxigenic Bacteroides fragilis (ETBF) is a commensal bacterium of great importance to human health due to its ability to induce colitis and cause colon tumor formation in mice through the production of B. fragilis toxin (BFT). The formation of tumors is dependent on a pro-inflammatory signaling cascade, which begins with the disruption of epithelial barrier integrity through cleavage of E-cadherin. Here, we show that BFT increases levels of glucosylceramide, a vital intestinal sphingolipid, both in mice and in colon organoids (colonoids) generated from the distal colons of mice. When colonoids are treated with BFT in the presence of an inhibitor of glucosylceramide synthase (GCS), the enzyme responsible for generating glucosylceramide, colonoids become highly permeable, lose structural integrity, and eventually burst, releasing their contents into the extracellular matrix. By increasing glucosylceramide levels in colonoids via an inhibitor of glucocerebrosidase (GBA, the enzyme that degrades glucosylceramide), colonoid permeability was reduced, and bursting was significantly decreased. In the presence of BFT, pharmacological inhibition of GCS caused levels of tight junction protein 1 (TJP1) to decrease. However, when GBA was inhibited, TJP1 levels remained stable, suggesting that BFT-induced production of glucosylceramide helps to stabilize tight junctions. Taken together, our data demonstrate a glucosylceramide-dependent mechanism by which the colon epithelium responds to BFT.

Novel Insight into the Serum Sphingolipid Fingerprint Characterizing Longevity

“…Furthermore, glucosylceramide species, specifically HexCer 16:0, HexCer 22:0 and HexCer 24:1 chains, increased in C compared to Ag and specifically characterized C vs. both Ag and Ad. A recent paper highlighted the relevance of HexCer as a protective molecule to maintain cellular integrity in colon epithelial cells in response to stressors [ 51 ], and HexCers increase was described in cerebrospinal fluid (CSF) from idiopathic normal pressure hydrocephalus patients, compared to Alzheimer’s diseases subjects [ 9 ]. It is tempting to speculate that this increase could be a beneficial aspect at large, protecting C from stressor events.…”

Intestinal Inflammation and Parkinson’s Disease

“…GBA mutation has also been identified associated with IBD. It has been shown that by inhibiting GBA, glucosylceramide levels in colon organoids increase, leading to reduced colon permeability and decreased bursting [ 124 ], suggesting the possible role of GBA in maintaining intestinal permeability.…”

A systemic review of the role of enterotoxic Bacteroides fragilis in colorectal cancer

“…Thirty in vivo mouse studies were identified and included in the analysis [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] . 87% of these studies used the C57BL6 mouse strain (26 studies [38 , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [51] , [52] , [53] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] , [69] ), 10% used the BALB/c mouse strain (3 studies [54] , [55] , [56] ), and 3% used a germ free (GF) NIH mouse strain (...…”

“…NFAT5 and TLR4 knockdowns decreased tumor growth Patterson et al. 2020 [59] SPF C57BL/6 mice were colonized with ETBF Lipidomic analysis, confocal microscopy, qRT-PCR, Western blot, flow cytometry BFT increases glucosylceramide levels Boleij et al. 2021 [60] SPF WT C57BL6 and GPR35 −/− (KO) mice were colonized with ETBF qPCR, Histopathology, Choice of antibiotic pre-treatment influenced severity of ETBF-colitis.GPR35 knockdown resulted in reduced ETBF-induced weight loss, less severe colitis, increased survival rate, and reduced expression of IL-22, Cxcl5 , and Mt2 Destefano Shields et al.…”