AAV9-Delivered α7nAChR Ameliorates DSS-Induced Murine Ulcerative Colitis by Activating CAP Pathway, Inhibiting NF-κB/NLRP3 Axis and Restoring Intestinal Barrier and T-reg/Th-17 Homeostasis

This study aimed to explore the therapeutic effect and underlying mechanism of α7 nicotinic acetylcholine receptor (α7nAChR) mediated by adeno-associated virus serotype 9 (AAV9) on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Male C57BL/6 mice were randomly divided into the blank control group, model group, AAV-α7nAChR low/medium/high-dose groups, and AAV-GFP group. A chronic UC model was established, with interventions administered via intraperitoneal injection. Meanwhile, an acute UC model was set up, together with control groups treated with the α7nAChR antagonist methyllycaconitine (MLA) and 5-aminosalicylic acid (5-ASA). A series of indicators were detected, including body weight, Disease Activity Index (DAI), colonic pathological changes, inflammatory factors, pathway-related proteins, and T-regulatory (T-reg)/T helper 17 (Th-17) cell balance. Results demonstrated that AAV9-α7nAChR ameliorated UC symptoms in mice in a dose-dependent manner: it relieved body weight loss and hematochezia, restored colon length and spleen weight, and alleviated colonic mucosal damage. Furthermore, it activated the cholinergic anti-inflammatory pathway (CAP), inhibited the NF-κB/NLRP3 inflammatory axis, repaired the intestinal barrier (by upregulating ZO-1 and occludin), and restored the T-reg/Th-17 immune balance. The therapeutic efficacy of the high-dose AAV9-α7nAChR group was superior to that of the 5-ASA group, while MLA could suppress its therapeutic effect. This study preliminarily clarified the multi-target mechanism of AAV9-α7nAChR in treating UC, providing an experimental foundation for the clinical gene therapy of UC.