Dysbiosis, an imbalance of intestinal flora, can cause serious conditions such as obesity, cancer, and psychoneurological disorders. One cause of dysbiosis is inflammation. Ulcerative enteritis is a side effect of non-steroidal anti-inflammatory drugs (NSAIDs). To counteract this side effect, we proposed the concurrent use of histamine H₂ receptor antagonists (H₂RA), and we examined the effect on the intestinal flora. We generated a murine model of NSAID-induced intestinal mucosal injury, and we administered oral H₂RA to the mice. We collected stool samples, compared the composition of intestinal flora using terminal restriction fragment length polymorphism, and performed organic acid analysis using high-performance liquid chromatography. The intestinal flora analysis revealed that NSAID [indomethacin (IDM)] administration increased Erysipelotrichaceae and decreased Clostridiales but that both had improved with the concurrent administration of H₂RA. Fecal levels of acetic, propionic, and n-butyric acids increased with IDM administration and decreased with the concurrent administration of H₂RA. Although in NSAID-induced gastroenteritis the proportion of intestinal microorganisms changes, leading to the deterioration of the intestinal environment, concurrent administration of H₂RA can normalize the intestinal flora.

Non-steroidal anti-inflammatory drugs (NSAIDs), which are antipyretics and analgesics, cause gastrointestinal disorders, such as inflammation and ulcers. To prescribe NSAIDs more safely, it is important to clarify the mechanism of NSAID-induced gastrointestinal mucosal injury. However, there is a paucity of studies on small intestinal mucosal damage by NSAIDs, and it is currently unknown whether inflammation and ulceration also occur in the small intestine, and whether mediators are involved in the mechanism of injury. Therefore, in this study, we created an animal model in which small intestinal mucosal injury was induced using NSAIDs (indomethacin; IDM). Focusing on the dynamics of immune regulatory factors related to the injury, we aimed to elucidate the pathophysiological mechanism involved. We analyzed the pathological changes in the small intestine, the expression of immunoregulatory factors (cytokines), and identified cytokine secretion and expression cells from isolated lamina propria mononuclear cells (LPMCs). Ulcers were formed in the small intestine by administering IDM. Although the mRNA expression levels of IL-1β, IL-6, and TNFα were decreased on day 7 after IDM administration, IL-13 mRNA levels increased from day 3 after IDM administration and remained high even on day 7. The IL-13 mRNA expression and the secretion of IL-13 were increased in small intestinal LPMCs isolated from the IDM-treated group. In addition, we confirmed that IL-13 was expressed in CD4-positive T cells. These results provided new evidence that IL-13 production from CD4-positive T cells in the lamina propria of the small intestine contributes to NSAID-induced mucosal injury.

Leucine-rich repeat kinase 2 (LRRK2) is a multidomain serine/threonine kinase and a major genetic contributor to Parkinson’s disease (PD). Although LRRK2 has been extensively studied in neurodegeneration, emerging evidence indicates that it also plays a critical role in systemic metabolism. LRRK2 regulates glucose homeostasis through modulation of insulin signaling, vesicle trafficking, mitochondrial function, and inflammatory responses. Studies using LRRK2 knockout and knock-in models, including the pathogenic G2019S mutation, have revealed abnormalities in insulin sensitivity, adipose tissue inflammation, hepatic glucose production, and skeletal muscle metabolism. Mechanistically, LRRK2 phosphorylates Rab GTPases, thereby controlling insulin receptor trafficking and GLUT4 translocation. In addition, LRRK2 influences mitochondrial dynamics and reactive oxygen species production, linking metabolic stress to inflammatory signaling. Importantly, LRRK2 also regulates innate immune pathways, including TLR4–NFκB signaling and inflammasome activation, thereby connecting peripheral metabolic dysfunction to neuroinflammation. Here, we propose an integrated metabolic–neuroinflammatory crosstalk model in which LRRK2 functions as a molecular coordinator linking peripheral metabolic dysfunction to central neurodegeneration. In this framework, systemic metabolic stress—characterized by insulin resistance, chronic inflammation, advanced glycation end product (AGE) accumulation, and blood–brain barrier disruption—drives microglial activation and neurodegenerative processes. Understanding this systemic axis may provide new therapeutic opportunities targeting both metabolic dysfunction and neurodegeneration in PD.

Intestinal barrier dysfunction and mucus layer abnormalities are central features of inflammatory bowel disease, yet the epithelial mechanisms regulating goblet cell function remain incompletely understood. The TWEAK/Fn14 pathway is involved in intestinal inflammation, but its role in small intestinal epithelial responses, particularly in goblet cells, has not been fully clarified. In this study, we investigated TWEAK/Fn14 signaling using mouse small intestinal epithelial organoids. Fn14 was expressed in MUC2-positive cells in intestinal tissue, with staining preferentially observed toward the mucin-facing region. Fn14 staining was also observed in small intestinal epithelial organoids. TWEAK stimulation increased Tnf mRNA expression by approximately 1.56-fold and reduced Muc2 mRNA expression to approximately 66% of control, without markedly affecting epithelial proliferation or stem cell markers. TWEAK did not significantly alter the PAS-positive mucin area or AB-PAS-defined mucin composition, whereas PGM34 staining showed a non-significant tendency to increase. TNF treatment reproduced some of the TWEAK-associated changes, including reduced Muc2 mRNA expression and alterations in mucin-associated parameters, suggesting that TNF may contribute to some of the epithelial responses associated with TWEAK treatment. Treatment with an anti-TNF neutralizing antibody modified several TWEAK-associated responses, including changes in epithelial-associated gene expression and mucin-associated staining parameters. These findings suggest that TWEAK treatment is associated with goblet cell-related mucin responses in mouse small intestinal epithelial organoids, with possible involvement of TNF signaling.

Improvement of bowel function is accompanied by increased luminal flow and altered epithelial mechanical forces, yet the underlying epithelial mechanisms remain unclear. We investigated whether enhanced luminal stimulation is associated with epithelial mechanotransduction and junctional remodeling during changes in colonic motility. Sennoside was orally administered at 4.8 mg/kg body weight to 5-week-old male BALB/cAJcl mice for 21 days to model increased luminal stimulation. Stool characteristics, fecal water content, Bristol Stool Form Scale scores, and segmental colonic motility were assessed. Expression of Muc2, inflammatory cytokines, Trpv4, and E-cadherin was quantified across colonic regions. In CT26 monolayers, mechanical stress was applied to evaluate transient receptor potential channel induction, E-cadherin redistribution, and transepithelial electrical resistance, and the effect of Trpv4 knockdown. Sennoside softened stools, increased fecal water content (+18%) and Bristol scores (+57%), and enhanced distal colonic motility (+117%) without altering inflammatory cytokines. Trpv4 was selectively upregulated in the distal colon (3.3-fold). E-cadherin expression increased (2.5-fold) with junctional redistribution, whereas Muc2 decreased (−44%). In vitro, mechanical stress upregulated Trpv4 (2.5-fold), increased barrier resistance (+48%), and promoted E-cadherin assembly; these effects were augmented by sennoside and attenuated by Trpv4 silencing. These findings suggest that epithelial responses involving TRPV4-associated mechanotransduction and junctional remodeling are associated with altered barrier-related properties and distal colonic functional changes, providing insight into an epithelial component of stimulant laxative action.