Insulin-like growth factor 1: Common mediator of multiple enterotrophic hormones and growth factors

PURPOSE OF REVIEW: To summarize the recent evidence that insulin-like growth factor 1 (IGF1) mediates growth effects of multiple trophic factors and discuss clinical relevance. RECENT FINDINGS: Recent reviews and original reports indicate benefits of growth hormone (GH) and long-acting glucagon-like peptide 2 (GLP2) analogs in short bowel syndrome and Crohn's disease. This review highlights the evidence that biomarkers of sustained small intestinal growth or mucosal healing and evaluation of intestinal epithelial stem cell biomarkers may improve clinical measures of intestinal growth or response to trophic hormones. Compelling evidence that IGF1 mediates growth effects of GH and GLP2 on intestine or linear growth in preclinical models of resection or Crohn's disease is presented, along with a concept that these hormones or IGF1 may enhance sustained growth if given early after bowel resection. Evidence that suppressor of cytokine signaling protein induction by GH or GLP2 in normal or inflamed intestine may limit IGF1-induced growth, but protect against risk of dysplasia or fibrosis, is reviewed. Whether IGF1 receptor mediates IGF1 action and potential roles of insulin receptors are addressed. SUMMARY: IGF1 has a central role in mediating trophic hormone action in small intestine. Better understanding of benefits and risks of IGF1, receptors that mediate IGF1 action, and factors that limit undesirable growth are needed.