Microbial Colonization of Germ‐Free Mice Restores Neointimal Hyperplasia Development After Arterial Injury

Background The potential role of the gut microbiome in cardiovascular diseases is increasingly evident. Arterial restenosis attributable to neointimal hyperplasia after cardiovascular procedures such as balloon angioplasty, stenting, and bypass surgery is a common cause of treatment failure, yet whether gut microbiota participate in the development of neointimal hyperplasia remains largely unknown. Methods and Results We performed fecal microbial transplantation from conventionally raised male C57BL/6 mice to age‐, sex‐, and strain‐matched germ‐free mice. Five weeks after inoculation, all mice underwent unilateral carotid ligation. Neointimal hyperplasia development was quantified after 4 weeks. Conventionally raised and germ‐free cohorts served as comparison groups. Conclusions Germ‐free mice have significantly attenuated neointimal hyperplasia development compared with conventionally raised mice. The arterial remodeling response is restored by fecal transplantation. Our results describe a causative role of gut microbiota in contributing to the pathogenesis of neointimal hyperplasia.

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PC230. Microbial Colonization Restores Neointimal Hyperplasia Development After Arterial Injury in Germ-Free Mice

Journal of Vascular Surgery ◽

10.1016/j.jvs.2019.04.408 ◽

2019 ◽

Vol 69 (6) ◽

pp. e267-e268

Author(s):

Edmund B. Chen ◽

Katherine Shapiro ◽

Thomas Kuntz ◽

Betty Theriault ◽

Michael Nooromid ◽

...

Keyword(s):

Neointimal Hyperplasia ◽

Arterial Injury ◽

Microbial Colonization ◽

Germ Free

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Su1093 – Fecal Transplantation Restores Neointimal Hyperplasia Development After Arterial Injury in Germ-Free Mice

Gastroenterology ◽

10.1016/s0016-5085(19)40644-6 ◽

2019 ◽

Vol 156 (6) ◽

pp. S-1438

Author(s):

Edmund Chen ◽

Katherine E. Shapiro ◽

Betty Theriault ◽

Michael Nooromid ◽

Kelly Wun ◽

...

Keyword(s):

Neointimal Hyperplasia ◽

Arterial Injury ◽

Fecal Transplantation ◽

Germ Free

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10 THE ROLE OF DIETARY L-SERINE IN THE REGULATION OF INTESTINAL MUCUS BARRIER DURING INFLAMMATION

Inflammatory Bowel Diseases ◽

10.1093/ibd/zaa010.110 ◽

2020 ◽

Vol 26 (Supplement_1) ◽

pp. S42-S42

Author(s):

Kohei Sugihara ◽

Nobuhiko Kamada

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Gut Microbiota ◽

Control Diet ◽

Bacterial Strains ◽

Germ Free ◽

Intestinal Mucus ◽

Gnotobiotic Mice ◽

Mucus Barrier

Abstract Background Recent accumulating evidence suggests that amino acids have crucial roles in the maintenance of intestinal homeostasis. In inflammatory bowel disease (IBD), amino acid metabolism is changed in both host and the gut microbiota. Among amino acids, L-serine plays a central role in several metabolic processes that are essential for the growth and survival of both mammalian and bacterial cells. However, the role of L-serine in intestinal homeostasis and IBD remains incompletely understood. In this study, we investigated the effect of dietary L-serine on intestinal inflammation in a murine model of colitis. Methods Specific pathogen-free (SPF) mice were fed either a control diet (amino acid-based diet) or an L-serine-deficient diet (SDD). Colitis was induced by the treatment of dextran sodium sulfate (DSS). The gut microbiome was analyzed by 16S rRNA sequencing. We also evaluate the effect of dietary L-serine in germ-free mice and gnotobiotic mice that were colonized by a consortium of non-mucolytic bacterial strains or the consortium plus mucolytic bacterial strains. Results We found that the SDD exacerbated experimental colitis in SPF mice. However, the severity of colitis in SDD-fed mice was comparable to control diet-fed mice in germ-free condition, suggesting that the gut microbiota is required for exacerbation of colitis caused by the restriction of dietary L-serine. The gut microbiome analysis revealed that dietary L-serine restriction fosters the blooms of a mucus-degrading bacterium Akkermansia muciniphila and adherent-invasive Escherichia coli in the inflamed gut. Consistent with the expansion of mucolytic bacteria, SDD-fed mice showed a loss of the intestinal mucus layer. Dysfunction of the mucus barrier resulted in increased intestinal permeability, thereby leading to bacterial translocation to the intestinal mucosa, which subsequently increased the severity of colitis. The increased intestinal permeability and subsequent bacterial translocation were observed in SDD-fed gnotobiotic mice that colonized by mucolytic bacteria. In contrast, dietary L-serine restriction did not alter intestinal barrier integrity in gnotobiotic mice that colonized only by non-mucolytic bacteria. Conclusion Our results suggest that dietary L-serine regulates the integrity of the intestinal mucus barrier during inflammation by limiting the expansion of mucus degrading bacteria.

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A9 DORSAL ROOT GANGLIA NEURONAL RESPONSES AND SUBSTANCE P PRODUCTION ARE HIGHER IN MALE MICE

Journal of the Canadian Association of Gastroenterology ◽

10.1093/jcag/gwab002.008 ◽

2021 ◽

Vol 4 (Supplement_1) ◽

pp. 10-11

Author(s):

J Pujo ◽

G De Palma ◽

J Lu ◽

S M Collins ◽

P Bercik

Keyword(s):

Abdominal Pain ◽

Substance P ◽

Gut Microbiota ◽

Sensory Neurons ◽

Dorsal Root ◽

Neuronal Response ◽

Neuronal Responses ◽

Visceral Sensitivity ◽

Germ Free

Abstract Background Abdominal pain is a common complaint in patients with chronic gastrointestinal disorders. Accumulating evidence suggests that gut microbiota is an important determinant of gut function, including visceral sensitivity. Germ-free (GF) mice have been shown to display visceral hypersensitivity, which normalizes after colonization. Sex also appears to play a key role in visceral sensitivity, as women report more abdominal pain than men. Thus, both gut bacteria and sex are important in the regulation of gut nociception, but the underlying mechanisms remain poorly understood. Aims To investigate the role of gut microbiota and sex in abdominal pain. Methods We used primary cultures of sensory neurons from dorsal root ganglia (DRG) of female and male conventionally raised (SPF) or germ-free (GF) mice (7–18 weeks old). To study the visceral afferent activity in vitro, calcium mobilization in DRG sensory neurons was measured by inverted fluorescence microscope using a fluorescent calcium probe Fluo-4 (1mM). Two parameters were considered i) the percentage of responding neurons ii) the intensity of the neuronal response. First, DRG sensory neurons were stimulated by a TRPV1 agonist capsaicin (12.5nM, 125nM and 1.25µM) or by a mixture of G-protein coupled receptors agonist (GPCR: bradykinin, histamine and serotonin; 1µM, 10µM and 100µM). We next measured the neuronal production of substance P and calcitonin gene-related peptide (CGRP), two neuropeptides associated with nociception, in response to capsaicin (1.25µM) or GPCR agonists (100µM) by ELISA and EIA, respectively. Results The percentage of neurons responding to capsaicin and GPCR agonists was similar in male and female SPF and GF mice. However, the intensity of the neuronal response was higher in SPF male compared to SPF female in response to capsaicin (125nM: p=0.0336; 1.25µM: p=0.033) but not to GPCR agonists. Neuronal activation was similar in GF and SPF mice of both sexes after administration of capsaicin or GPCR agonists. Furthermore, substance P and CGRP production by sensory neurons induced by capsaicin or GPCR agonists was similar in SPF and GF mice, regardless of sex. However, while the response to capsaicin was similar, the GPCR agonists-induced production of substance P was higher in SPF male mice compared to SPF females (p=0.003). The GPCR agonists-induced production of CGRP was similar in SPF male and female mice. Conclusions Our data suggest that at the level of DRG neurons, the absence of gut microbiota does not predispose to visceral hypersensitivity. The intensity of DRG neuronal responses to capsaicin and the GPCR agonists-induced production of substance P are higher in male compared to female mice, in contrast to previously published studies in various models of acute and chronic pain. Further studies are thus needed to investigate the role of sex in visceral sensitivity. Funding Agencies CIHR

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Guild-based analysis for understanding gut microbiome in human health and diseases

Genome Medicine ◽

10.1186/s13073-021-00840-y ◽

2021 ◽

Vol 13 (1) ◽

Cited By ~ 2

Author(s):

Guojun Wu ◽

Naisi Zhao ◽

Chenhong Zhang ◽

Yan Y. Lam ◽

Liping Zhao

Keyword(s):

Gut Microbiota ◽

Human Health ◽

Gut Microbiome ◽

Association Studies ◽

Causative Role ◽

Disease Phenotypes ◽

Genetic Complexity ◽

Causative Agents ◽

Specific Health

AbstractTo demonstrate the causative role of gut microbiome in human health and diseases, we first need to identify, via next-generation sequencing, potentially important functional members associated with specific health outcomes and disease phenotypes. However, due to the strain-level genetic complexity of the gut microbiota, microbiome datasets are highly dimensional and highly sparse in nature, making it challenging to identify putative causative agents of a particular disease phenotype. Members of an ecosystem seldomly live independently from each other. Instead, they develop local interactions and form inter-member organizations to influence the ecosystem’s higher-level patterns and functions. In the ecological study of macro-organisms, members are defined as belonging to the same “guild” if they exploit the same class of resources in a similar way or work together as a coherent functional group. Translating the concept of “guild” to the study of gut microbiota, we redefine guild as a group of bacteria that show consistent co-abundant behavior and likely to work together to contribute to the same ecological function. In this opinion article, we discuss how to use guilds as the aggregation unit to reduce dimensionality and sparsity in microbiome-wide association studies for identifying candidate gut bacteria that may causatively contribute to human health and diseases.

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Role of germ-free animal models in understanding interactions of gut microbiota to host and environmental health: A special reference to zebrafish

Environmental Pollution ◽

10.1016/j.envpol.2021.116925 ◽

2021 ◽

pp. 116925

Author(s):

Pan-Pan Jia ◽

Muhammad Junaid ◽

Ping-Ping Wen ◽

Yi-Fan Yang ◽

Wei-Guo Li ◽

...

Keyword(s):

Animal Models ◽

Gut Microbiota ◽

Special Reference ◽

Environmental Health ◽

Germ Free ◽

Free Animal

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Lupus Gut Microbiota Transplants Cause Autoimmunity and Inflammation

10.1101/2021.08.15.456375 ◽

2021 ◽

Author(s):

Yiyangzi Ma ◽

Ruru Guo ◽

Yiduo Sun ◽

Xin Li ◽

Lun He ◽

...

Keyword(s):

Gut Microbiota ◽

Lupus Erythematosus ◽

Fecal Microbiota Transplantation ◽

Fecal Microbiota ◽

Healthy Controls ◽

Germ Free ◽

Autoimmune Antibodies ◽

Expression Of Genes ◽

Rdna Sequencing

Background: The etiology of systemic lupus erythematosus (SLE) is multifactorial. Recently, growing evidence suggests that the microbiota plays a role in SLE, yet whether gut microbiota participates in the development of SLE remains largely unknown. To investigate this issue, we carried out 16s rDNA sequencing analyses in a cohort of 18 female un-treated active SLE patients and 7 female healthy controls, and performed fecal microbiota transplantation from patients and healthy controls to germ-free mice. Results: Compared to the healthy controls, we found no significant different microbial diversity but some significantly different species in SLE patients including Turicibacter genus and other 5 species. Fecal transfer from SLE patients to germ free (GF) C57BL/6 mice caused GF mice to develop a series of lupus-like phenotyptic features, which including an increased serum autoimmune antibodies, and imbalanced cytokines, altered distribution of immune cells in mucosal and peripheral immune response, and upregulated expression of genes related to SLE in recipient mice that received SLE fecal microbiota transplantation (FMT). Moreover, the metabolism of histidine was significantly altered in GF mice treated with SLE patient feces, as compared to those which received healthy fecal transplants. Conclusions: Overall, our results describe a causal role of aberrant gut microbiota in contributing to the pathogenesis of SLE. The interplay of gut microbial and histidine metabolism may be one of the mechanisms intertwined with autoimmune activation in SLE.

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