Tolerability and effect of inhibiting microfibrillar-associated protein 4 in small intestinal anastomotic healing.

Crohn’s disease often leads to strictures due to excessive extracellular matrix deposition and smooth muscle cell hyperplasia. Current stricture treatments include surgical and endoscopic interventions, but high recurrence rates remain a challenge. Microfibrillar-associated protein 4 (MFAP4) contributes to fibrosis in various tissues. The anti-MFAP4 antibody was evaluated for its tolerability and anti-fibrotic efficacy on small intestinal anastomotic healing in pig models. Two small intestinal anastomoses were made in 45 pigs. Fibrosis was induced using aethoxysklerol injections. Each anastomosis was locally injected with either anti-MFAP4, positive control anakinra (interleukin-1 receptor antagonist) or negative vehicle control. Tolerability of anti-MFAP4 was observed across three observation durations (5, 10, and 28 days) and assessed by weight gain, anastomotic tissue strength, and histological evaluation. Anti-fibrotic efficacy was tested using semi-quantitative collagen scoring from the 28-days study. Proteome analysis of tissue sections was applied for mechanistic analyses. Local anastomotic injections of 16 mg and 32 mg anti-MFAP4 were well tolerated. Anastomotic fibrosis was significantly reduced both by positive control anakinra-treatment and anti-MFAP4-treatment. Anti-MFAP4 reduced fibrosis by 23% relative to the negative control. Gene ontology term analysis showed up-regulation of muscle cell contractile apparatus and down-regulation of transcription and translation in the anti-MFAP4 group. The data supported that anti-MFAP4-treatment reduced the anastomotic collagen deposition compared with vehicle. Moreover, the treatment induced smooth muscle cell switching from the synthetic phenotype involved in fibrosis to the contractile phenotype essential for homeostatic gut motor activity.