Effects of Intestinal Flora on Irritable Bowel Syndrome and Therapeutic Significance of Polysaccharides

Causal relationship between gut microbiota, lipids, and neuropsychiatric disorders: A Mendelian randomization mediation study

BACKGROUND

Numerous studies have shown an interconnection between the gut microbiota and the brain via the "gut-brain" axis. However, the causal relationships between gut microbiota, lipids, and neuropsychiatric disorders remain unclear. This study aimed to analyze potential associations among gut microbiota, lipids, and neuropsychiatric disorders-including AD, PD, ALS, MS, SCZ, MDD, and BD-using summary data from large-scale GWAS.

METHODS

Bidirectional Mendelian randomization (MR) with inverse variance weighting (IVW) was the primary method. Supplementary analyses included sensitivity analyses, Steiger tests, and Bayesian weighted MR (BWMR). Mediation analyses used two-step MR (TSMR) and multivariable MR (MVMR).

RESULTS

The analyses revealed 51 positive correlations (risk factors) (β > 0, P < 0.05) and 47 negative correlations (protective factors) (β < 0, P < 0.05) between gut microbiota and neuropsychiatric disorders. In addition, 35 positive correlations (β > 0, P < 0.05) and 22 negative correlations (β < 0, P < 0.05) between lipids and neuropsychiatric disorders were observed. Assessment of reverse causality with the seven neuropsychiatric disorders as exposures and the identified gut microbiota and lipids as outcomes revealed no evidence of reverse causality (P > 0.05). Mediation analysis indicated that the effect of the species Bacteroides plebeius on MDD is partially mediated through the regulation of phosphatidylcholine (16:0_20:4) levels (mediation proportion = 10.9 % [95 % CI = 0.0110-0.2073]).

CONCLUSION

This study provides evidence of a causal relationship between gut microbiota and neuropsychiatric disorders, suggesting lipids as mediators. These findings offer new insights into the mechanisms by which gut microbiota may influence neuropsychiatric disorders.

Effects of Portulaca oleracea L. Polysaccharide on piglets infected with porcine rotavirus

Piglet diarrhea stands as the primary cause of piglet mortality, inflicting substantial economic losses to pig farmers. Porcine rotavirus (PoRV), a member of the Reoviridae family, bears responsibility for instigating diarrhea and severe dehydration, culminating in piglet fatalities. Portulaca oleracea L. (POL), a Chinese medicinal herb commonly utilized for its antiviral properties and effectiveness in treating diarrhea, holds promise for mitigating these effects. Nevertheless, the in vivo antiviral effect of Portulaca oleracea L. polysaccharide (POL-P), a key component of POL, on PoRV infection remains obscure. This study aimed to investigate the antiviral effects of POL-P on PoRV in piglets and its impact on their intestinal flora. Studies have demonstrated that oral POL-P improves growth in both lactating mice and PoRV-infected piglets, while reducing diarrhea and mortality. It also helps to reduce intestinal damage and lower viral mRNA levels in the jejunum and ileum. Additionally, POL-P improves blood tests in piglets, boosting levels of IFN-α and IL-10, and lowering tumor necrosis factor-α and IL-6. Analysis of the intestinal flora in PoRV-infected piglets showed reduced levels of Bacteroides (18.39 %) and increased levels of Firmicutes (39.81 %), Proteobacteria (33.46 %), and Verrucomicrobia (7.42 %). After POL-P treatment, Bacteroides increased to 28.31 %, while Firmicutes, Proteobacteria, and Verrucomicrobia decreased to 34.93 %, 25.52 %, and 2.53 %, respectively. At the genus level, POL-P treatment reduced the abundance of Klebsiella, Ackermannia, and Streptococcus. In conclusion, POL-P helps reduce inflammation and intestinal damage caused by PoRV infection, prevents viral colonization, restores gut flora balance, improves piglet growth, and reduces diarrhea and mortality.

Gut microbiota and intestinal immunity-A crosstalk in irritable bowel syndrome

Irritable bowel syndrome (IBS), one of the most prevalent functional gastrointestinal disorders, is characterized by recurrent abdominal pain and abnormal defecation habits, resulting in a severe healthcare burden worldwide. The pathophysiological mechanisms of IBS are multi-factorially involved, including food antigens, visceral hypersensitivity reactions, and the brain-gut axis. Numerous studies have found that gut microbiota and intestinal mucosal immunity play an important role in the development of IBS in crosstalk with multiple mechanisms. Therefore, based on existing evidence, this paper elaborates that the damage and activation of intestinal mucosal immunity and the disturbance of gut microbiota are closely related to the progression of IBS. Combined with the application prospect, it also provides references for further in-depth exploration and clinical practice.

Gut Microbiota Dysbiosis Ameliorates in LNK-Deficient Mouse Models with Obesity-Induced Insulin Resistance Improvement

PURPOSE

To investigate the potential role of gut microbiota in obesity-induced insulin resistance (IR).

METHODS

Four-week-old male C57BL/6 wild-type mice (n = 6) and whole-body SH2 domain-containing adaptor protein (LNK)-deficient in C57BL/6 genetic backgrounds mice (n = 7) were fed with a high-fat diet (HFD, 60% calories from fat) for 16 weeks. The gut microbiota of 13 mice feces samples was analyzed by using a 16 s rRNA sequencing analysis.

RESULTS

The structure and composition of the gut microbiota community of WT mice were significantly different from those in the LNK-/- group. The abundance of the lipopolysaccharide (LPS)-producing genus Proteobacteria was increased in WT mice, while some short-chain fatty acid (SCFA)-producing genera in WT groups were significantly lower than in LNK-/- groups (p < 0.05).

CONCLUSIONS

The structure and composition of the intestinal microbiota community of obese WT mice were significantly different from those in the LNK-/- group. The abnormality of the gut microbial structure and composition might interfere with glucolipid metabolism and exacerbate obesity-induced IR by increasing LPS-producing genera while reducing SCFA-producing probiotics.