Background:

Visceral hypersensitivity is a prevalent and debilitating symptom in inflammatory bowel disease (IBD), severely impairing quality of life. Although mechanisms remain incompletely understood, recent studies have reported abnormal copper metabolism and elevated serum copper in IBD patients. However, whether copper homeostasis contributes to visceral hypersensitivity remains unknown.

Methods:

We established a dextran sulfate sodium (DSS)-induced colitis model in C57BL/6J mice to induce visceral hypersensitivity. Copper content in the terminal colon and dorsal root ganglia (DRG) was measured using a colorimetric copper assay kit. Western blot analysis evaluated expression of central sensitization markers, calmodulin-dependent kinase II (CaMKII), phosphorylated CaMKII (p-CaMKII), cyclic adenosine monophosphate response element-binding protein (CREB), and phosphorylated CREB (p-CREB) in the spinal cord and DRG. The expression of cuproptosis-related proteins, including dihydrolipoamide S-acetyltransferase (DLAT), lipoic acid synthetase (LIAS), and ferredoxin 1 (FDX1), was also measured in the terminal colon and DRG. We examined the effects of the copper chelator ammonium tetrathiomolybdate (ATTM, 10 mg/kg, i.p., daily). Expression of copper transport ATPase copper transporting alpha (ATP7A) and copper transporter 1 (CTR1) was also assessed.

Results:

DSS-induced colitis resulted in visceral hypersensitivity and central sensitization, accompanied by copper accumulation in the terminal colon and DRG, along with downregulation of DLAT, LIAS, and FDX1. ATTM reduced copper accumulation, restored cuproptosis-related protein expression, and attenuated visceral hypersensitivity and central sensitization. Notably, ATTM normalized the expression of the copper efflux transporter ATP7A and the influx transporter CTR1 in the terminal colon and DRG.

Conclusion:

Our findings for the first time definitely identify and mechanistically elucidate that copper accumulation in the terminal colon and DRG contributes to visceral hypersensitivity in DSS-induced colitis. Dysregulation of the copper transporters ATP7A and CTR1 underlies this copper dyshomeostasis. Our results uncover copper ion homeostasis as a completely unrecognized, novel mechanistic axis driving visceral hypersensitivity in IBD.

Search results

Copper chelator ammonium tetrathiomolybdate ameliorates the visceral hypersensitivity in dextran sulfate sodium-induced colitis mice