Kashyap, Purna

Background: Primary sclerosing cholangitis (PSC) is a major risk factor for cholangiocarcinoma (CCA). We investigated biliary and fecal microbiota to determine whether specific microbes in the bile or stool are associated with PSC or CCA. Methods: Bile was obtained from 32 patients with PSC, 23 with CCA with PSC, 26 with CCA without PSC, and 17 controls. Over 90% of bile samples were from patients with perihilar CCA. Stool was obtained from 31 patients with PSC (11 were matched to bile), 16 with CCA with PSC (10 matched to bile), and 11 with CCA without PSC (6 matched to bile). Microbiota composition was assessed using 16SrRNA-marker-based sequencing and was compared between groups. Results: Bile has a unique microbiota distinguished from negative DNA controls and stool. Increased species richness and abundance of Fusobacteria correlated with duration of PSC and characterized the biliary microbiota in CCA. Stool microbiota composition showed no significant differences between groups. Conclusions: We identified a unique microbial signature in the bile of patients with increased duration of PSC or with CCA, suggesting a role for microbiota-driven inflammation in the pathogenesis and or progression to perihilar CCA. Further studies are needed to test this hypothesis.

Abstract The role of maternal microbiome transmitted at birth in cancer control is poorly understood. We have developed the first germfree B6 mouse model of breast cancer to investigate the role of the maternal microbiome in controlling oncogenic/metastatic frequencies of pro-oncogenic mammary cells. In this model, a DNA barcoded, primitive normal mouse mammary epithelial cell encoding MMTV-PyMT oncogene, was transplanted in large numbers into conventional or germfree B6 mice. Next-gen sequencing analysis of the DNA barcodes in tissues enabled us to clonally track millions of cells and measure the frequency and growth dynamics of clones at the primary site and their systemic distribution in circulation and all vital organs, generating an unprecedented high-definition map of cancer progression. Our results show that in conventional B6 mice with maternal microbial transmission at-birth, a small fraction (~0.01%) of transplanted cells transform de novo and produce slow growing, late-onset benign tumors (mouse median survival of > 1 year). In contrast, in germfree B6 mice, a >10-fold higher frequency of cells transform de novo and generate early-onset, highly aggressive metastatic clones, and are frequently associated with features leading to early euthanasia or endpoint (i.e. sudden death, intracardiac metastasis, paralysis, swollen abdomen, early multiorgan aggressive metastasis) (median survival of ~4 months; p<0.005 vs conventional mice). However, postnatal intervention with healthy fecal implants reconstituted gut microbiota in germfree B6 mice and significantly restored protective effects against cancer progression and sudden death, as well as improved quality/duration of life (median survival of >1 year; p<0.005 vs germfree mice; p=ns vs conventional mice). We found maternal microbial transmission fully protected against systemic metastasis. GC-MS analysis identified significantly distinct primary tumor metabolome associated with conventional (non-metastatic) mice vs germfree (metastatic) mice. Metagenomic analysis of fecal samples from a subset of tumor bearing conventional (non-metastatic) mice vs fecal implanted (late-onset, less aggressive metastatic) germfree mice identified significant association between metastasis and altered microbial communities. These findings using novel germfree mouse model of metastasis and cellular DNA barcoding technology provide first direct evidence that diverse microbial communities transmitted at birth play a critical role in protecting the host from clonal de novo mammary cell transformation and progression to systemic disease and thereby improving quality and duration of life. Citation Format: Nagarajan Kannan, Syed Mohammed Musheer Aalam, Xiaojia Tang, Krishna Kalari, Purna Kashyap, Jun Chen, Stephen Johnson, Anguraj Sadanandam, Mark Sherman. Maternal microbiome protects host against clonal de novo transformation, early onset systemic metastasis, and sudden death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB226.

Introduction The gut microbiota is intricately connected with host health and is known to influence gene expression across multiple organ systems. Both animal and human longitudinal studies have demonstrated that exercise has independent effects on the composition and functionality of the gut microbiota. Previous studies performed by our group have also shown that transplant of an “exercised” microbiota into germ‐free mice confers enhanced protection against colitis compared to transplant of a “sedentary” microbiota. In this study, we assessed how an “exercised” microbiota transplant impacts global gene expression in gut, brain, and muscle tissue compared to a “sedentary” microbiota transplant. Methods Donor mice received access to a running wheel (n=10) or remained without access (n=9) for six weeks prior to euthanasia. Donor cecal contents were pooled by activity group and transplanted into two separate groups of recipient germ‐free mice (n=16 for each group). After five weeks of gut microbial colonization, recipient mice were sacrificed, and tissues were collected. Total RNA was isolated from the distal colon, soleus muscle, and hippocampus. Four representative mice were chosen from each group for whole transcriptome analysis (RNAseq) of these tissues. Anticipated Results We hypothesize that mice that received an “exercised” microbiome will have different global gene expression profiles than those that received a “sedentary” microbiome. We predict that genes related to immune function, cellular metabolism, and gut barrier function may be particularly affected by transplant of the “exercised” microbiome. Support or Funding Information This work supported by a grant from the Mayo Clinic‐University of Illinois Alliance for Technology‐based Healthcare. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Background Microbial conversion of dietary substrate to bioactive molecules represents a potential regulatory mechanism by which gut microbes can alter intestinal physiology. Tryptamine, a monoamine structurally similar to serotonin (5‐HT), can be generated via decarboxylation of tryptophan by the gut bacteria but its physiological effect is not known. Aim To determine the effect of bacterial metabolite tryptamine on colonic secretion. Methods We mounted proximal colon mucosa‐submucosa preparations from germ free (GF), humanized (HM; ex‐GF colonized with human gut bacteria for 4–5 weeks), conventionally raised WT and 5‐HT4 receptor knockout (5‐HT4R −/− ) male mice in the Ussing chamber. The change in short circuit current (ΔIsc) was determined in response to application of increasing concentrations of tryptamine (3μM – 3mM) on the submucosal (basolateral) side either alone or in the presence of 5‐HT3R or 5‐HT4R antagonist, ondansetron (100nM) and GR‐113808 (30nM) respectively, with and without TTX (500nM). Colonoids (3‐dimensional epithelial organoids derived from colon) from GF and HM were used for swelling assay and ELISA based cAMP measurement. Results Tryptamine application significantly increased Isc in both GF and HM mice (n=6, P < 0.05, two‐way ANOVA with Bonferroni post‐hoc). Tryptamine mediated ΔIsc response was not significantly affected by amiloride, an inhibitor of epithelial sodium channels and Na + /H + exchangers, which are primarily responsible for absorption but was significantly decreased by 5‐Nitro‐2‐(3‐phenylpropylamino) benzoic acid (NPPB; anion blocker), a calcium‐sensitive chloride channel and sodium bicarbonate exchanger inhibitor responsible for anionic secretion in both GF and HM mice (n=4, P < 0.05, two‐way ANOVA with Bonferroni post‐hoc). Tryptamine evoked ΔIsc was not inhibited by 5‐HT3R (n=4, P > 0.05) but completely blocked by 5‐HT4R antagonist and was absent in 5HT4R knock out mice suggesting that the effect of tryptamine is mediated via 5HT4R. The increase in Isc in response to tryptamine and its inhibition by 5‐HT4R antagonist was also seen in presence of TTX (neuronal blocker; n=4, one‐way ANOVA , P < 0.05) suggesting that the epithelial 5‐HT4R alone can mediate the effect of tryptamine. Application of tryptamine (1mM) for 30 minutes led to a significant increase in the surface area of fluorescein labelled colonoids (n=5, one‐way ANOVA , P < 0.05), similar to forskolin, when compared to vehicle treated and 5HT4R antagonist pre‐treated GF and HM colonoids. Colonoids incubated with tryptamine (1mM) for 60 minutes had significantly higher cAMP levels (normalized to forskolin) compared to vehicle treated GF and HM colonoids, confirming that tryptamine activates 5‐HT4 GPCR (n=3, student's t‐test, P < 0.05). Conclusion Tryptamine, a tryptophan‐derived microbial metabolite, increases colonic secretion via 5HT4 GPCR activation. The identification of a bacterial metabolite activating a host GPCR to alter GI function represents an important advance in the field, and provides a distinct example of small molecule mediated host‐microbe interaction. Engineered probiotics producing tryptamine could be used as therapeutics in diseases associated with constipation. Support or Funding Information NIH DK111850, DK114007 (PCK) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Gut microbes play a significant role in development and maintenance of intestinal functions, but can contribute to pathogenesis of gastrointestinal (GI) disorders when host‐microbiome relationship is perturbed. In this study we sought to examine how constipation affects microbiome, and how these alterations in turn affect the host. Adult C57Bl/6 mice were treated with 0.1% Loperamide in drinking water for 7 days to induce constipation. Loperamide‐treated mice had increased GI transit time, indicating constipation. Bacterial DNA analysis by HiSeq sequencing showed decreased Firmicutes and increased Bacteroidetes in constipated mice. Microbiome metabolic potential was measured with tetrazolium dye assay and showed shift toward increased sugar metabolism in Loperamide‐treated mice. Microbial metabolites were measured by GC‐MS, and showed lower butyrate concentration in constipated mice. To determine constipation effects on the host, we introduced microbiota from constipated donors to germ‐free recipients. These mice had delayed GI transit time. To determine mechanism for delayed GI transit we analyzed colon tissues by qRT‐PCR and western blotting analysis, and determined lower expression of nNos mRNA and protein levels in these mice. Overall, these results suggest that delayed GI transit shifts microbiome taxonomic and metabolic profile, and these changes further contribute to development of constipation. Grant Funding Source : NIH NIDDK T32 DK07074

Abstract Background: Berberine (BBR) is a plant-based nutraceutical that has been used for millennia to treat diarrheal infections and in contemporary medicine to improve patient lipid profiles. Reduction in lipids, particularly cholesterol, is achieved partly through up-regulation of bile acid synthesis and excretion into the gastrointestinal tract (GI). The efficacy of BBR is also thought to be dependent on structural and functional alterations of the gut microbiome. However, knowledge of the effects of BBR on gut microbiome communities is currently lacking. Distinguishing indirect effects of BBR on bacteria through altered bile acid profiles is particularly important in understanding how dietary nutraceuticals alter the microbiome. Results: Germfree mice were colonized with a defined minimal gut bacterial consortium capable of functional bile acid metabolism (Bacteroides vulgatus, Bacteroides uniformis, Parabacteroides distasonis, Bilophila wadsworthia, Clostridium hylemonae, Clostridium hiranonis, Blautia producta; B4PC2). Multi-omics (bile acid metabolomics, 16S rDNA sequencing, cecal metatranscriptomics) were performed in order to provide a simple in vivo model from which to identify network-based correlations between bile acids and bacterial transcripts in the presence and absence of dietary BBR. Significant alterations in network topology and connectivity in function were observed, despite similarity in gut microbial alpha diversity (P = 0.30) and beta-diversity (P = 0.123) between control and BBR treatment. BBR increased cecal bile acid concentrations, (P < 0.05), most notably deoxycholic acid (DCA) (P <0.001). Overall, analysis of transcriptomes and correlation networks indicates both bacterial species-specific responses to BBR, as well as functional commonalities among species, such as up-regulation of Na+/H+ antiporter, cell wall synthesis/repair, carbohydrate metabolism and amino acid metabolism. Bile acid concentrations in the GI tract increased significantly during BBR treatment and developed extensive correlation networks with expressed genes in the B4PC2 community.Conclusions: This work has important implications for interpreting the effects of BBR on structure and function of the complex gut microbiome, which may lead to targeted pharmaceutical interventions aimed to achieve the positive physiological effects previously observed with BBR supplementation.