Figure 1.

Regulatory effect of selected adipokines on intestinal homeostasis. The figure illustrates at which layer of the intestinal wall the selected adipokines exert their respective regulatory function. Blue indicates the intestinal epithelial layer. Adiponectin, apelin and leptin have been shown to enhance cell proliferation and enhance barrier function. The majority of these data derive from in vitro data, thus it remains open how these adipokines contribute to the complex crosstalk between epithelial cells and immune cells in vivo. Green indicates the lamina propria with all cell populations included. Chemerin has been shown here to attract innate immune cells resulting in a deterioration of colitis. Leptin induces T cell proliferation thus enhancing inflammation. Yellow indicates the mesenteric fat tissue. Adiponectin, apelin and leptin are all up-regulated in this compartment. Apelin enhances the function of the lymphatic vessels, that are known to be dysfunctional in Crohn's disease. Leptin strongly influences the polarization of infiltrating monocytes toward rather anti-inflammatory macrophages.