Short-chain fatty acids ameliorate spinal cord injury recovery by regulating the balance of regulatory T cells and effector IL-17+ γδ T cells

Impact of inflammation and Treg cell regulation on neuropathic pain in spinal cord injury: mechanisms and therapeutic prospects

Spinal cord injury is a severe neurological trauma that can frequently lead to neuropathic pain. During the initial stages following spinal cord injury, inflammation plays a critical role; however, excessive inflammation can exacerbate pain. Regulatory T cells (Treg cells) have a crucial function in regulating inflammation and alleviating neuropathic pain. Treg cells release suppressor cytokines and modulate the function of other immune cells to suppress the inflammatory response. Simultaneously, inflammation impedes Treg cell activity, further intensifying neuropathic pain. Therefore, suppressing the inflammatory response while enhancing Treg cell regulatory function may provide novel therapeutic avenues for treating neuropathic pain resulting from spinal cord injury. This review comprehensively describes the mechanisms underlying the inflammatory response and Treg cell regulation subsequent to spinal cord injury, with a specific focus on exploring the potential mechanisms through which Treg cells regulate neuropathic pain following spinal cord injury. The insights gained from this review aim to provide new concepts and a rationale for the therapeutic prospects and direction of cell therapy in spinal cord injury-related conditions.

Fecal microbiota transplantation regulates the microbiota-gut-spinal cord axis to promote recovery after spinal cord injury

Spinal cord injury (SCI) is devastating for patients, and currently lacks effective treatments. Dysbiosis commonly occurs after SCI and has significant immunomodulatory effects, but its impact on recovery remains unclear. The current study investigated the effects and mechanisms of fecal microbiota transplantation (FMT) in SCI. FMT was administered in a rat model of SCI and spinal pathology, inflammatory cytokines, and gut microbiome composition were assessed. Flow cytometry identified a source of interleukin (IL)-17 in spinal cord tissues, and carboxyfluorescein succimidyl ester labeling tracked γδ T cell migration. In vitro coculture was used to analyze the regulatory mechanisms of γδ T cells. Seahorse analysis was used to profile dendritic cell (DC) metabolism. Here we show that FMT improved spinal pathology and dampened post-injury inflammation. It also corrected post-SCI dysbiosis, increasing levels of the beneficial bacterium Akkermansia. The therapeutic effects of FMT were mediated by IL-17 produced by γδ T cells. FMT regulated γδ T cells via DC-T regulatory cell interaction, and induced metabolic reprogramming in DCs. These findings suggest that FMT represents a promising therapeutic approach for SCI, with potential to target IL-17+ γδ T cells. Elucidating the interconnected pathways between microbiota, immunity, and the spinal cord may facilitate novel treatment strategies.

Ento-A alleviates DSS-induced experimental colitis in mice by remolding intestinal microbiota to regulate SCFAs metabolism and the Th17 signaling pathway

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by changes in the metabolism of short chain fatty acids (SCFAs), dysregulation of gut microbiota, and an imbalance of Treg/Th17. Herein, we explore the effects of the Ento-A (an alcohol extract of Periplaneta americana L.) on a mouse model of UC. First, a chronic and recurrent UC model was constructed in BALB/c mice by 2.2% DSS administration. UC mice were continuously treated for 14 days with Ento-A (50, 100, 200 mg/kg, i.g.) or a negative control. Ento-A alleviated many of the pathological changes observed in UC mice, such as body weight loss, disease activity index, changes in colon length, and colonic mucosal damage index. Ento-A also decreased levels of proinflammatory cytokines (IL-1β, IL-6, IL-17A, and TNF-α), increased levels of anti-inflammatory cytokines (IL-10 and TGF-β1) and repaired the intestinal mucosal barrier. Additionally, Ento-A regulated the proportions of Th17 cells, and Treg cells in mesenteric lymph nodes harvested from treated mice (as assessed by Flow cytometry), and the expression levels of IL-17A and Foxp3 in colon (as assessed by immunohistochemistry). 16 S rRNA gene sequencing revealed that Ento-A regulated gut microbiota. GC-MS analysis demonstrated that Ento-A also restored SCFAs content in the intestinal tract. Finally, transcriptomic analysis revealed that Ento-A regulated the IL-17 signaling pathway. In summary, Ento-A regulates the diversity and abundance of intestinal flora in UC mice, enhancing the secretion of SCFAs, subsequently regulating the IL-17 signaling pathway, and ultimately repairing the intestinal mucosal barrier.