Biology subjects

Devlin, A. S.

Publications and source records attributed to Devlin, A. S..

10 recordsLinked to original sources

bioRxiv2026

Human Gut Bacteria Convert Endogenous Steroids into Host Cortisol Shuttle Inhibitors

11{beta}-hydroxysteroid dehydrogenase 2 (HSD11B2) protects the mineralocorticoid receptor from glucocorticoid overstimulation by inactivating cortisol. HSD11B2 inhibition can drive receptor overactivation and contribute to hypertension; however, endogenous inhibitors remain poorly defined. Glycyrrhetinic acid-like factors (GALFs) are steroid-like metabolites that inhibit HSD11B2. Given the capacity of gut bacteria to metabolize host steroids, we hypothesized that the gut microbiome could generate GALF-like inhibitors. Here, we identify two 11-oxygenated steroid metabolites that potently inhibit human HSD11B2 in colonic cells and organoids, enabling cortisol-dependent mineralocorticoid receptor activation. We identify gut bacteria and enzymes that produce these compounds and show that their levels are markedly reduced in antibiotic-treated humans. One metabolite is elevated during pregnancy, and both are higher in individuals with stage 2 hypertension-range blood pressure. These findings reveal a bacterial route to altered host cortisol signaling and suggest a potential link between microbiome-derived GALFs and blood pressure regulation.

microbiology↗

bioRxiv2025

Vitamin D receptor is necessary for metabolic health after sleeve gastrectomy

BackgroundThe vitamin D receptor (VDR) regulates insulin sensitivity. Metabolic bariatric surgery (MBS) remains the most effective treatment for obesity and T2D. However, whether its metabolic effects are VDR-dependent is unknown. Here, we assessed VDR role in the metabolic response to sleeve gastrectomy (SG). MethodsWhole body VDR knockout (KO) and wild type (WT) C57BL/6J mice with diet-induced obesity (DIO) were assigned to either SG or sham procedure. Postoperatively, animals underwent glucose and insulin tolerance tests. On sacrifice, serum, white adipose tissue (WAT), liver and colonic contents were collected for further biochemical, histological and bile acid analysis. Separately, human VDR gene expression was assessed in subcutaneous adipose tissue (SAT) biopsies collected from patients with/without MBS history. ResultsKO SG mice exhibited delayed glucose utilization after an oral challenge and progressive loss of insulin sensitivity, despite the same magnitude of surgery-induced weight change between the two genotypes. WAT in KO SG mice had lower mass, smaller adipocytes and increased inflammation. SG had a differential effect on colonic levels of the glucoregulatory cholic acid 7-sulfate (CA7S): increasing CA7S concentration in the WT mice but decreasing it in the KO mice. Finally, patients with MBS history had higher VDR expression in SAT as compared to those without MBS history. ConclusionVDR is necessary for metabolic health after SG in DIO mice due to its role in WAT function, insulin sensitivity and inflammatory response after surgery. Increased expression of VDR in patients post-MBS suggests that it may also contribute to metabolic responses in humans. HighlightsO_LIVDR KO results in delayed glucose utilization following SG in DIO mice C_LIO_LIVDR KO results in progressive loss of improved insulin sensitivity after SG C_LIO_LIVDR KO results in white adipose tissue inflammation and remodeling after SG C_LIO_LIVDR expression increases in human subcutaneous adipose tissue after bariatric surgery C_LI

physiology↗

bioRxiv2025

Gut Microbiome-Produced Bile Acid Metabolite Lengthens Circadian Period in Host Intestinal Cells

Host circadian signaling, feeding, and the gut microbiome are tightly interconnected. Changes in the gut microbial community can affect the expression of core clock genes, but the specific metabolites and molecular mechanisms that mediate this relationship remain largely unknown. Here, we sought to identify gut microbial metabolites that impact circadian signaling. Through a phenotypic screen of a focused library of gut microbial metabolites, we identified a bile acid metabolite, lithocholic acid (LCA), as a circadian modulator. LCA lengthened the circadian period of core clock gene hPer2 transcription in a dose-responsive manner in human colonic cells. We found evidence that LCA modulates the casein kinase 1 {delta}/{varepsilon} (CK1{delta}/{varepsilon})-protein phosphatase 1 (PP1) feedback loop and stabilizes core clock protein cryptochrome 2 (CRY2). Furthermore, we showed that LCA feeding alters circadian transcription in mouse distal ileum and colon. Taken together, our work identifies LCA as a molecular link between host circadian biology and the microbiome. Because bile acids are secreted in response to feeding, our work provides potential mechanistic insight into the molecular nature of the food-entrainable oscillator by which peripheral clocks adapt to the timing of food intake. Given the association between circadian rhythm, feeding, and metabolic disease, our insights may offer a new avenue for modulating host health.

cell biology↗

bioRxiv2024

Cultured Bacteria Isolated from Primary Sclerosing Cholangitis Patient Bile Induce Inflammation and Cell Death

BackgroundPrimary sclerosing cholangitis (PSC) is a chronic liver disease characterized by inflammation and progressive fibrosis of the biliary tree. The pathogenesis of PSC remains poorly understood, and there are no effective therapeutic options. Previous studies have observed associations between changes in the colonic and biliary microbiome and PSC. We aimed to determine whether bacterial isolates cultured from PSC patient bile induced disease-associated phenotypes in cells. MethodsBile was collected from PSC patients (n=10) by endoscopic retrograde cholangiography and from non-PSC controls (n=3) undergoing cholecystectomies. Biliary bacteria were cultured anaerobically, and 50 colonies per sample were identified by 16S rRNA sequencing. The effects of supernatants from seven PSC-associated bacterial strains on cellular phenotypes were characterized using human colonic (Caco-2), hepatic (HepG2), and biliary (EGI-1) cells. ResultsNo bacteria were isolated from non-PSC controls, while bacteria were cultured from most PSC patients. The PSC bile microbiomes exhibited reduced diversity compared to the gut or oral cavity, with one or two bacterial strains predominating. Overall, PSC-associated bacteria produced factors that were cytotoxic to hepatic and biliary cells. Enterococcus faecalis, and to a lesser extent Veillonella parvula, induced epithelial permeability, while Escherichia coli, Fusobacterium necrophorum, and Klebsiella pneumoniae induced inflammatory cytokines in biliary cells. ConclusionsOur data suggest that bacteria cultured from PSC bile induce cellular changes that may contribute to PSC disease pathogenesis. Enterococcus may promote intestinal permeability, facilitating bacterial migration to the biliary tree. Once there, Escherichia, Fusobacterium and Klebsiella, may cause inflammation and damage in biliary and liver cells.

microbiology↗

bioRxiv2021

Bile salt hydrolases deplete conjugated bile acids and erode gut barrier integrity in non-alcoholic steatohepatitis

Altered host-microbe interactions and increased intestinal permeability have been implicated in the pathogenesis of a range of diseases. However, the mechanisms by which gut microbes affect epithelial barrier integrity remain unclear. Few host-produced metabolites that protect against epithelial damage have been identified, and whether microbial metabolism of host factors alters intestinal barrier function is unknown. Here, we investigate the effects of bacterial metabolism of host-produced bile acid (BA) metabolites on epithelial barrier integrity. We observe that rats fed a choline-deficient, high-fat diet (CDAHFD) exhibit reduced abundance of host-produced conjugated BAs in the intestine at early timepoints coinciding with increased permeability. We show that in vitro, conjugated BAs protect gut epithelial monolayers from damage caused by bacterially produced unconjugated BAs through micelle formation. We then demonstrate that inhibition of BA deconjugation using a small molecule inhibitor of gut bacterial bile salt hydrolase (BSH) enzymes prevents development of pathologic intestinal permeability and hepatic inflammation in CDAHFD-fed rats. Finally, we show that the predominant conjugated BAs in humans protect against epithelial barrier disruption in vitro. Our study identifies a protective role for conjugated BAs in intestinal epithelial barrier function and suggests that rational manipulation of microbial BA metabolism could be leveraged to regulate gut barrier integrity.

physiology↗

bioRxiv2021

A gut-restricted lithocholic acid analog as an inhibitor of gut bacterial bile salt hydrolases

Bile acids play crucial roles in host physiology by acting as both detergents that aid in digestion and as signaling molecules that bind to host receptors. Gut bacterial bile salt hydrolase (BSH) enzymes perform the gateway reaction leading to the conversion of host-produced primary bile acids into bacterially modified secondary bile acids. Small molecule probes that target BSHs will help elucidate the causal roles of these metabolites in host physiology. We previously reported the development of a covalent BSH inhibitor with low gut permeability. Here, we build on our previous findings and describe the development of a second-generation gut-restricted BSH inhibitor with enhanced potency, reduced off-target effects, and durable in vivo efficacy. SAR studies focused on the bile acid core identified a compound, AAA-10, containing a C3-sulfonated lithocholic acid scaffold and an alpha-fluoromethyl ketone warhead as a potent pan-BSH inhibitor. This compound inhibits BSH activity in conventional mouse fecal slurries, bacterial cultures, and purified BSH proteins and displays reduced toxicity against mammalian cells compared to first generation compounds. Oral administration of AAA-10 to wild-type mice for 5 days resulted in a decrease in the abundance of the secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA) in the mouse GI tract with low systemic exposure of AAA-10, demonstrating that AAA-10 is an effective tool for inhibiting BSH activity and modulating bile acid pool composition in vivo.

biochemistry↗

bioRxiv2021

Human gut bacteria produce TH17-modulating bile acid metabolites

The microbiota plays a pivotal role in gut immune homeostasis. Bacteria influence the development and function of host immune cells, including T helper cells expressing interleukin-17a (TH17 cells). We previously reported that the bile acid metabolite 3-oxolithocholic acid (3-oxoLCA) inhibits TH17 cell differentiation1. While it was suggested that gut-residing bacteria produce 3-oxoLCA, the identity of such bacteria was unknown. Furthermore, it was not clear whether 3-oxoLCA and other immunomodulatory bile acids are associated with gut inflammatory pathologies in humans. Using a high-throughput screen, we identified human gut bacteria and corresponding enzymes that convert the secondary bile acid lithocholic acid into 3-oxoLCA as well as the abundant gut metabolite isolithocholic acid (isoLCA). Like 3-oxoLCA, isoLCA suppressed TH17 differentiation by inhibiting ROR{gamma}t (retinoic acid receptor-related orphan nuclear receptor {gamma}t), a key TH17 cell-promoting transcription factor. Levels of both 3-oxoLCA and isoLCA and the 3-hydroxysteroid dehydrogenase (3-HSDH) genes required for their biosynthesis were significantly reduced in patients with inflammatory bowel diseases (IBD). Moreover, levels of these bile acids were inversely correlated with expression of TH17 cell-associated genes. Overall, our data suggest that bacterially produced TH17 cell-inhibitory bile acids may reduce the risk of autoimmune and inflammatory disorders such as IBD.

immunology↗

bioRxiv2021

A Bacterial Bile Acid Metabolite Modulates Treg Activity through the Nuclear Hormone Receptor NR4A1

Bile acids act as signaling molecules that regulate immune homeostasis, including the differentiation of CD4+ T cells into distinct T cell subsets. The bile acid metabolite isoallolithocholic acid (isoalloLCA) enhances the differentiation of anti-inflammatory regulatory T cells (Treg cells) by facilitating the formation of a permissive chromatin structure in the promoter region of the transcription factor forkhead box P3 (Foxp3). Here, we identify gut bacteria that synthesize isoalloLCA from 3-oxolithocholic acid and uncover a gene cluster responsible for the conversion in members of the abundant human gut bacterial phylum Bacteroidetes. We also show that the nuclear hormone receptor NR4A1 is required for the effect of isoalloLCA on Treg cells. Moreover, the levels of isoalloLCA and its biosynthetic genes are significantly reduced in patients with inflammatory bowel diseases, suggesting that isoalloLCA and its bacterial producers may play a critical role in maintaining immune homeostasis in humans.

immunology↗

bioRxiv2020

Bariatric surgery reveals a gut-restricted TGR5 agonist that exhibits anti-diabetic effects

Bariatric surgery, the most effective treatment for obesity and type 2 diabetes, is consistently associated with increased levels of the incretin hormone GLP-1 and changes in overall levels of circulating bile acids. The levels of individual bile acids in the GI tract following surgery, however, have remained largely unstudied. Using UPLC-MS-based quantification, we observed an increase in an endogenous bile acid, cholic acid-7-sulfate (CA7S), in the GI tract of both mice and humans after sleeve gastrectomy. We show that CA7S is a TGR5 agonist that induces GLP-1 secretion in vitro and in vivo and that CA7S administration increases glucose tolerance in insulin-resistant mice in a GLP-1 receptor-dependent manner. CA7S remains gut-restricted, minimizing off-target effects previously observed for TGR5 agonists absorbed into circulation. By studying changes in individual metabolites following surgery, this study has revealed a naturally occurring TGR5 agonist that exerts systemic glucoregulatory effects while remaining confined to the gut.

biochemistry↗

bioRxiv2019

Development of a Covalent Inhibitor of Gut Bacterial Bile Salt Hydrolases

Bile salt hydrolase (BSH) enzymes are widely expressed by human gut bacteria and catalyze the gateway reaction leading to secondary bile acid formation. Bile acids regulate key metabolic and immune processes by binding to host receptors. There is an unmet need for a potent tool to inhibit BSHs across all gut bacteria in order to study the effects of bile acids on host physiology. Here, we report the development of a covalent pan-inhibitor of gut bacterial BSH. From a rationally designed candidate library, we identified a lead compound bearing an alpha-fluoromethyl ketone warhead that modifies BSH at the catalytic cysteine residue. Strikingly, this inhibitor abolished BSH activity in conventional mouse feces. Mice gavaged with a single dose of this compound displayed decreased BSH activity and decreased deconjugated bile acid levels in feces. Our studies demonstrate the potential of a covalent BSH inhibitor to modulate bile acid composition in vivo.

microbiology↗