Analyzing the innate immunity of NIH hairless mice and the impact of gut microbial polymorphisms on Listeria monocytogenes infection

Extremely hair follicle density is associated with a significantly different cecal microbiota in rex rabbits

It has become increasingly clear that gut microbiota and skin are interconnected since the discovery of the 'gut-brain-skin' axis. Hair follicles (HFs) are skin microorganisms, but few studies have investigated their relationship to gut microbiota. Hence, we hypothesize that HFs have a close relationship with the gut, similarly to what was reported for the skin. Using rex rabbits as an animal model, one hundred healthy half-sibling rex rabbits were selected for the experiment, and 16 s rRNA gene sequencing was performed on the cecal microbiota of nine rabbits with the extremely high (HS) and low (LS) hair density (n = 9 per group) to determine differences between the composition and function of these communities. In comparison with the LS group, several alpha diversity index values were significantly lower in the HS group, although the higher variation in species composition in the HS group. Additionally, species diversity and abundance differed significantly in the cecum microbiota of HS and LS rabbits. Further, primary and secondary HF density was significantly correlated with the families Muribaculaceae and Bacteroidaceae, and genera Blautia, Bacteroides and Desulfovibrio. In particular, Muribaculaceae, Bacteroidaceae, Blautia and Bacteroides may support the development of HFs. Moreover, the expression of WNT4, WNT10a, WNT10b, CTNNB1 (β-catenin) and LEF1 in the skin was significantly higher in the HS group compared with the LS group. Altogether, the results of this study suggest that the extremely high density of HF in rabbits is associated with a significantly different microbiota diversity and community structure, and the Wnt/β-catenin signalling pathway was activated in the HS group. Thus, key bacteria may promote the development of HF.

Bovine serum albumin aggravates macrophage M1 activation and kidney injury in heterozygous Klotho-deficient mice via the gut microbiota-immune axis

Klotho expression abnormalities induces kidney injury and chronic kidney disease, however, the underlying mechanism remains unclear. Here, Klotho^+/- mice and wild-type mice were treated with low-dose bovine serum albumin (BSA). Pathological examination demonstrated that the area of glomerular collagen deposition and fibrosis in BSA-Kl^-/+ mice was significantly larger than that in BSA-WT mice. The serum levels of superoxide dismutase, malondialdehyde, creatinine, and urea in BSA-Kl^-/+ mice were significantly increased. Sequencing of gut microbiota 16S rRNA v3-v4 region indicated that BSA-Kl^-/+ mice showed a significantly higher relative abundance of the genera Dubosiella, Akkermansia, Alloprevotella, and Lachnospiraceae and a significantly lower relative abundance of the genera Allobaculum and Muribaculaceae than BSA-WT mice. KEGG analysis revealed that the metabolic pathways of signal transduction, xenobiotic biodegradation and metabolism, and lipid metabolism increased significantly in BSA-Kl^-/+ mice. Flow cytometry showed that the proportion of CD68⁺/CD11b⁺ cells in the peripheral blood was significantly higher in BSA-KL^-/+ mice than that in BSA-WT mice. qPCR and western blot suggested that Klotho and Nrf2 expression in MΦ1 cells of BSA-KL^-/+ mice was significantly decreased. Thus, the findings suggest during the immune activation and chronic inflammation induced by the gut microbiota imbalance in Klotho-deficient mice treated to BSA, disrupted expression of proteins in the Nrf2/NF-κB signaling pathway in monocyte-derived macrophage M1 cells leads to the aggravation of inflammation and kidney injury.

Fisetin regulates gut microbiota to decrease CCR9+/CXCR3+/CD4+ T-lymphocyte count and IL-12 secretion to alleviate premature ovarian failure in mice

Currently, there are no studies reporting the efficacy of fisetin in premature ovarian failure (POF). In this study, using mouse and Caenorhabditis elegans models, we found that fisetin not only significantly reversed ovarian damage in POF mice, but also effectively increased C. elegans lifespan and fertility. Subsequently, we carried out 16S rRNA v3+v4 sequencing using fresh feces samples from each group of mice. Results showed that although there was no significant difference in the number of gut microbiomes between the different groups of mice, fisetin affected the diversity and distribution of gut microbiota in POF mice. Alpha and beta diversity analyses showed that in the gut of POF mice in the fisetin group, the bacterial count of uncultured_bacterium_f_Lachnospiraceae was significantly increased, while that of Akkermansia was significantly decreased. Finally, flow cytometry analysis showed that the numbers of CCR9⁺/CXCR3⁺/CD4⁺ T lymphocytes in the peripheral blood of POF mice in the fisetin group were significantly reduced, along with the number of CD4⁺/interleukin (IL)-12⁺ cells. Therefore, our data suggested that fisetin regulates the distribution and bacterial counts of Akkermansia and uncultured_bacterium_f_Lachnospiracea in POF mice, and reduces peripheral blood CCR9⁺/CXCR3⁺/CD4⁺ T-lymphocyte count and IL-12 secretion to regulate the ovarian microenvironment and reduce inflammation, thus exerting therapeutic effects against POF.

Ranitidine and finasteride inhibit the synthesis and release of trimethylamine N-oxide and mitigates its cardiovascular and renal damage through modulating gut microbiota

Trimethylamine N-oxide (TMAO) leads to the development of cardiovascular and chronic kidney diseases, but there are currently no potent drugs that inhibit the production or toxicity of TMAO. In this study, high-fat diet-fed ApoE-/- mice were treated with finasteride, ranitidine, and andrioe. Subsequently, the distribution and quantity of gut microbiota in the faeces of the mice in each group were analysed using 16S rRNA sequencing of the V3+V4 regions. Pathological examination confirmed that both ranitidine and finasteride reduced atherosclerosis and renal damage in mice. HPLC analysis also indicated that ranitidine and finasteride significantly reduced the synthesis of TMAO and the TMAO precursor delta-Valerobetaine in their livers. The 16S rRNA sequencing showed that all 3 drugs significantly increased the richness and diversity of gut microbiota in the model mice. Bioinformatic analysis revealed that the faeces of mice treated with ranitidine and finasteride, had significant increases in the number of microbes in the families g_Helicobacter, f_Desulfovibrionaceae, Mucispirillum_schaedleri_ASF457, and g_Blautia, whereas the relative abundances of microbes in the families Enterobacter_sp._IPC1-8 and g_Bacteroides were significantly reduced. The microbiota metabolic pathways, such as nucleotide and cofactor and vitamin metabolism were also significantly increased, whereas the activities of metabolic signalling pathways related to glycan biosynthesis and metabolism and cardiovascular diseases were significantly reduced. Therefore, our study indicates that in addition to their known pharmacological effects, ranitidine and finasteride also exhibit potential cardiovascular and renal protective effects. They inhibit the synthesis and metabolism of TMAO and delay the deposition of lipids and endotoxins through improving the composition of the gut microbiota.

Influence of Intestinal Microbiota Transplantation and NleH Expression on Citrobacter rodentium Colonization of Mice

The intestinal microbiota plays an important role in regulating host resistance to enteric pathogens. The relative abundance of the microbiota is dependent upon both genetic and environmental factors. The attaching and effacing pathogens enteropathogenic Escherichia coli, enterohemorrhagic E. coli, and Citrobacter rodentium cause diarrheal disease and translocate type III secretion system effector proteins into host cells to inhibit pro-inflammatory host responses. Here we determined the influence of both the intestinal microbiota and the expression of the C. rodentium NleH effector on C. rodentium colonization in different mouse models. We performed fecal transplantation experiments between C57BL/6J and C57BL/10ScNJ mice and found that such microbiota transfers altered both the host resistance to C. rodentium infection as well as the benefit or detriment of expressing NleH to C. rodentium intestinal colonization.