Published online Oct 21, 2020. doi: 10.3748/wjg.v26.i39.5997
Peer-review started: April 16, 2020
First decision: May 1, 2020
Revised: July 14, 2020
Accepted: September 4, 2020
Article in press: September 4, 2020
Published online: October 21, 2020
Recent studies have shown that autophagy dysfunction plays an important role in the pathogenesis of Crohn's disease (CD). Our previous studies have indicated that herbal cake-partitioned moxibustion (HM) can attenuate inflammation and ameliorate pathological changes in colon tissue in CD. However, it is unclear whether HM can regulate colonic autophagy in CD.
The mechanism of HM in the treatment of CD has remained unclear. We sought to elucidate the relevant mechanism by which HM alleviates CD from the perspective of autophagy.
To observe the effect of HM on colonic autophagy in CD rats and further explore the underlying mechanism.
2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to establish a rat CD model. The morphology of the colonic mucosa, formation of autophagosomes, and expression of microtubule-associated protein 1 Light chain 3 beta (LC3B) were observed by hematoxylin-eosin staining, electron microscopy, and immunofluorescence staining, respectively. Insulin and rapamycin were used to inhibit and activate colonic autophagy, respectively. The mRNA expression levels of phosphatidylinositol 3-kinase class I (PI3KC1), Akt1, LC3B, sequestosome 1 (p62), and mammalian target of rapamycin (mTOR) and the protein expression levels of interleukin-18 (IL-18), tumor necrosis factor-α (TNF-α), nuclear factor κB/p65 (NF-κB p65), LC3B, p62, coiled-coil myosin-like BCL2-interacting protein (Beclin-1), p-mTOR, PI3KC1, class III phosphatidylinositol 3-kinase (PI3KC3/Vps34), and p-Akt1 were evaluated by RT-qPCR and Western blot analysis, respectively.
Our experiments revealed that TNBS-induced inflammation activated autophagy in rat colon tissues. HM at the Qihai (CV6) and bilateral Tianshu (ST25) acupoints reversed the expression changes in the autophagy proteins LC3B, p62, Beclin-1, and p-mTOR in colon tissues while ameliorating colonic inflammation (indicated by IL-18, TNF-α, and NF-κB p65 levels) and damage. Furthermore, HM facilitated the repair of colonic epithelial cells. We hypothesized that the mechanisms by which HM alleviates CD may involve the PI3KC1/Akt1/mTOR pathway and the PI3KC3 (VPS34)-Beclin-1 protein complex and confirmed this hypothesis through our experiments.
HM can activate the PI3KC1/Akt1/mTOR signaling pathway while inhibiting the PI3KC3 (VPS34)-Beclin-1 protein complex, thereby inhibiting overactivated colonic autophagy in CD rats.
Our findings provide insights into the molecular mechanism of HM and shed new light on a cost-effective and safe therapy for CD.