The Gut Microbiome and Metabolic Health

Lactobacillus delbrueckii subsp. bulgaricus Alleviates Acute Injury in Hypoxic Mice

Acute mountain sickness (AMS) is a common ailment in high-altitude areas caused by the body's inadequate adaptation to low-pressure, low-oxygen environments, leading to organ edema, oxidative stress, and impaired intestinal barrier function. The gastrointestinal tract, being the first to be affected by ischemia and hypoxia, is highly susceptible to injury. This study investigates the role of Lactobacillus delbrueckii subsp. bulgaricus in alleviating acute hypoxic-induced intestinal and tissue damage from the perspective of daily consumed lactic acid bacteria. An acute hypoxia mouse model was established to evaluate tissue injury, oxidative stress, inflammatory responses, and intestinal barrier function in various groups of mice. The results indicate that strain 4L3 significantly mitigated brain and lung edema caused by hypoxia, improved colonic tissue damage, and effectively increased the content of tight junction proteins in the ileum, reducing ileal permeability and alleviating mechanical barrier damage in the intestines due to acute hypoxia. Additionally, 4L3 helped to rebalance the intestinal microbiota. In summary, this study found that Lactobacillus delbrueckii subsp. bulgaricus strain 4L3 could alleviate acute intestinal damage caused by hypoxia, thereby reducing hypoxic stress. This suggests that probiotic lactic acid bacteria that exert beneficial effects in the intestines may alleviate acute injury under hypoxic conditions in mice, offering new insights for the prevention and treatment of AMS.

The roles of different Bacteroides uniformis strains in alleviating DSS-induced ulcerative colitis and related functional genes

Bacteroides is a common intestinal bacterium closely associated with host colitis. However, relevant studies have been focused on the genus level, which could not identify the major Bacteroides species associated with intestinal disease. Thus, we have evaluated the Bacteroides species structure in healthy people and mouse intestinal tracts and explored the change in major Bacteroides species during colitis development. The results demonstrated that B. uniformis with a high abundance in the intestinal tract of healthy people and mice may be a core species that contributes to colitis remission. The results of animal experiments reported that B. uniformis FNMHLBE1K1 (1K1) could alleviate the severity of colitis and enhance the expression of the tight junction protein occludin by regulating gut microbiota. Notably, the protective roles of 1K1 may be attributed to some specific genes. This study revealed that B. uniformis is a key microbe influencing the occurrence and development of colitis and it provides a scientific basis for screening the next generation of probiotics.

Intraspecific difference of Latilactobacillus sakei in inflammatory bowel diseases: Insights into potential mechanisms through comparative genomics and metabolomics analyses

Inflammatory bowel diseases (IBDs) are chronic inflammatory diseases of the gastrointestinal tract that have become a global health burden. Studies have revealed that Latilactobacillus sakei can effectively alleviate various immune diseases, including colitis, rheumatoid arthritis, and metabolic disorders. Here, we obtained 72 strains of L. sakei from 120 fermentation and fecal samples across China. In total, 16 strains from different sources were initially screened in an in vitro Caco-2 model induced by dextran sulfate sodium. Subsequently, six strains (four exhibiting effectiveness and two exhibiting ineffectiveness) were selected for further validation in an in vivo colitis mouse model. The results demonstrated that L. sakei strains exhibited varying degrees of amelioration of the colitis disease process. Notably, L. sakei CCFM1267, the most effective strain, significantly restored colon length and tight-junction protein expression, and reduced the levels of cytokines and associated inflammatory enzymes. Moreover, L. sakei CCFM1267 upregulated the abundance of Enterorhabdus, Alloprevotella, and Roseburia, leading to increased levels of acetic acid and propionic acid. Conversely, the other four strains (L. sakei QJSSZ1L4, QJSSZ4L10, QGZZYRHMT1L6, and QGZZYRHMT2L6) only exhibited a partial remission effect, while L. sakei QJSNT1L10 displayed minimal impact. Therefore, L. sakei CCFM1267 and QJSNT1L10 were selected for further exploration of the mechanisms underlying their differential mitigating effects. Comparative genomics analysis revealed significant variations between the two strains, particularly in genes associated with carbohydrate-active enzymes, such as the glycoside hydrolase family, which potentially contribute to the diverse profiles of short-chain fatty acids in vivo. Additionally, metabolome analysis demonstrated that acetylcholine and indole-3-acetic acid were the main differentiating metabolites of the two strains. Therefore, the strains of L. sakei exhibited varying degrees of effectiveness in alleviating IBD-related symptoms, and the possible reasons for these variations were attributed to discrepancies in the carbohydrate-active enzymes and metabolites among the strains.

Roles of Secretory Immunoglobulin A in Host-Microbiota Interactions in the Gut Ecosystem

In the gastrointestinal tract (GIT), the immune system interacts with a variety of microorganisms, including pathogens as well as beneficial symbionts that perform important physiological functions for the host and are crucial to sustain intestinal homeostasis. In normal conditions, secretory immunoglobulin A (SIgA) is the principal antibody produced by B cells in the GIT mucosa. Polyreactivity provides certain SIgA molecules with the ability of binding different antigens in the bacterial surface, such as O-antigens and teichoic acids, while cross-species reactivity allows them to recognize and interact with different types of bacteria. These functions may be crucial in allowing SIgA to modulate the complex gut microbiota in an efficient manner. Several studies suggest that SIgA can help with the retention and proliferation of helpful members of the gut microbiota. Gut microbiota alterations in people with IgA deficiency include the lack of some species that are known to be normally coated by SIgA. Here, we discuss the different ways in which SIgA behaves in relation to pathogens and beneficial bacteria of the gut microbiota and how the immune system might protect and facilitate the establishment and maintenance of certain gut symbionts.

Qingrequzhuo capsule alleviated methionine and choline deficient diet-induced nonalcoholic steatohepatitis in mice through regulating gut microbiota, enhancing gut tight junction and inhibiting the activation of TLR4/NF-κB signaling pathway

Qingrequzhuo capsule (QRQZ), composed of Morus alba L., Coptis chinensis Franch., Anemarrhena asphodeloides Bunge, Alisma plantago-aquatica subsp. orientale (Sam.) Sam., Citrus × aurantium L., Carthamus tinctorius L., Rheum palmatum L., Smilax glabra Roxb., Dioscorea oppositifolia L., Cyathula officinalis K.C.Kuan, has been used to treat nonalcoholic steatohepatitis (NASH) in clinic. However, the mechanism of QRQZ on NASH remains unclear. Recent studies have found that the dysfunction of gut microbiota could impair the gut barrier and induce the activation of TLR4/NF-kB signaling pathway, and further contribute to the inflammatory response in NASH. Modulating the gut microbiota to reduce inflammation could prevent the progression of NASH. In this study, a mouse model of NASH was generated by methionine and choline deficient diet (MCD) and treated with QRQZ. First, we evaluated the therapeutic effects of QRQZ on liver injury and inflammation in the NASH mice. Second, the changes in the gut microbiota diversity and abundance in each group of mice were measured through 16S rRNA sequencing. Finally, the effects of QRQZ on gut mucosal permeability, endotoxemia, and liver TLR4/NF-kB signaling pathway levels were examined. Our results showed that QRQZ significantly reduced the lipid accumulation in liver and the liver injury in NASH mice. In addition, QRQZ treatment decreased the levels of inflammatory cytokines in liver. 16S rRNA sequencing showed that QRQZ affected the diversity of gut microbiota and a f f e c t e d t h e r e l a t i v e a b u n d a n c e s o f D u b o s i e l l a , Lachnospiraceae_NK4A136_group, and Blautiain NASH mice. Besides, QRQZ could increase the expression of tight junction proteins (zonula occludens-1 and occludin) in gut and decrease the lipopolysaccharide (LPS) level in serum. Western blot results also showed that QRQZ treatment decreased the protein expression ofTLR4, MyD88 and the phosphorylation of IkB and NF-kBp65 and qPCR results showed that QRQZ treatment down-regulated the gene expression of interleukin (IL)-1b, IL-6, and tumor necrosis factor (TNF)-a in liver. In conclusion, our study demonstrated that QRQZ could reduce the lipid accumulation and inflammatory response in NASH model mice. The mechanisms of QRQZ on NASH were associated with modulating gut microbiota, thereby inducing the tight junction of gut barrier, reducing the endotoxemia and inhibiting the activation of TLR4/NFkB signaling pathway in liver.

Mastiha (Pistacia lentiscus) Improves Gut Microbiota Diversity, Hepatic Steatosis, and Disease Activity in a Biopsy-Confirmed Mouse Model of Advanced Non-Alcoholic Steatohepatitis and Fibrosis

SCOPE

As a result of the obesity epidemic, the prevalence of non-alcoholic steatohepatitis (NASH) is increasing. No drug is approved for the treatment of NASH. In this study, the effect of a nutritional supplement, Mastiha or Chios mastic gum, on metabolic and histological parameters and on the gut microbiome in mice with NASH and fibrosis was investigated.

METHODS AND RESULTS

Advanced NASH was induced by feeding C57BL/6J mice a diet rich in fat, sucrose, and cholesterol for 41 weeks. After randomization, animals received the NASH-inducing diet with or without 0.2% (w/w) Mastiha for a further 8 weeks. Disease activity was assessed by liver histology and determination of plasma transaminase activities. Fecal microbiota DNA extraction and 16S rRNA amplicon sequencing were used to determine the composition of the gut microbiome. Mastiha supplementation led to a significant reduction in circulating alanine aminotransferase (ALT) activity, improvement in hepatic steatosis and collagen content, and a reduction in NAFLD activity score. Furthermore, it resulted in a partial but significant recovery of gut microbiota diversity and changes in identity and abundance of specific taxa.

CONCLUSION

This is the first study demonstrating an improvement in disease activity in mice with advanced NASH with fibrosis by a diet containing Mastiha.

Reappraising the exteriorization of the mammalian testes through evolutionary physiology

A number of theories have been proposed to explain the exteriorization of the testicles in most mammalian species. None of these provide a consistent account for the wide variety of testicular locations found across the animal kingdom. It is proposed that testicular location is the result of coordinate action of testicular tissue ecologies to sustain preferential states of homeostatic equipoise throughout evolutionary development in response to the advent of endothermy.

Four domains: The fundamental unicell and Post-Darwinian Cognition-Based Evolution

Contemporary research supports the viewpoint that self-referential cognition is the proper definition of life. From that initiating platform, a cohesive alternative evolutionary narrative distinct from standard Neodarwinism can be presented. Cognition-Based Evolution contends that biological variation is a product of a self-reinforcing information cycle that derives from self-referential attachment to biological information space-time with its attendant ambiguities. That information cycle is embodied through obligatory linkages among energy, biological information, and communication. Successive reiterations of the information cycle enact the informational architectures of the basic unicellular forms. From that base, inter-domain and cell-cell communications enable genetic and cellular variations through self-referential natural informational engineering and cellular niche construction. Holobionts are the exclusive endpoints of that self-referential cellular engineering as obligatory multicellular combinations of the essential Four Domains: Prokaryota, Archaea, Eukaryota and the Virome. Therefore, it is advocated that these Four Domains represent the perpetual object of the living circumstance rather than the visible macroorganic forms. In consequence, biology and its evolutionary development can be appraised as the continual defense of instantiated cellular self-reference. As the survival of cells is as dependent upon limitations and boundaries as upon any freedom of action, it is proposed that selection represents only one of many forms of cellular constraint that sustain self-referential integrity.