Mixed effects of caffeic acid phenethyl ester (CAPE) on joint inflammation, bone loss and gastrointestinal inflammation in a murine model of collagen antibody-induced arthritis

Objective: To investigate the effect of caffeic acid phenethyl ester (CAPE) on local and systemic inflammation and bone loss in collagen antibody-induced arthritis (CAIA) mice. Methods: Four groups of mice (n = 8 per group) were allocated; control, CAPE (1 mg/kg), CAIA and CAIA + CAPE (1 mg/kg). Local inflammation and bone loss were evaluated using clinical paw scores, in vivo micro-computed tomography (micro-CT), histological assessment and tartrate-resistant acid phosphatase (TRAP) staining. Serum levels of C-reactive protein (CRP) and C-terminal telopeptide (CTX-1) were measured by ELISA. Jejunum and colon sections were evaluated histopathologically for damage and toxicity. Results: Greater paw scores and percentage change in paw volume were observed in CAIA + CAPE compared to the control groups (p < 0.05). Bone volume over time remained unchanged (p = 0.94) and the number of multinucleated TRAP-positive cells was greatest in CAIA + CAPE mice (p < 0.05). CRP and CTX-1 levels did not differ between groups. CAIA + CAPE mice exhibited lower colon toxicity scores and a reduced percentage of cavitated goblet cells in the colon crypts compared with CAIA mice (p = 0.026 and p = 0.003, respectively). Histopathology in the jejunum was not altered. Conclusion: CAPE did not reduce paw inflammation or bone loss in CAIA mice. CAPE reduced histopathological changes in the colon of CAIA mice.