Increased Secretion of Granulocyte-Macrophage Colony-Stimulating Factor in Mucosal Lesions of Inflammatory Bowel Disease

Background: Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-3 transmit a same signal needed for growth and activation in granulocytes and macrophages, because these receptors utilize a common beta chain. Little is known about growth factors for intestinal myeloid cells in lesions of inflammatory bowel disease (IBD). Aim: To find out whether GM-CSF is produced by the intestinal cells in IBD patients and controls. Methods: We measured levels of GM-CSF, tumor necrosis factor (TNF), and IL-3 in the media of organ culture and lamina propria mononuclear cells (LPMCs) culture of colonic mucosa from the patients with IBD. Next, we have investigated GM-CSF production of colonic epithelial cell lines. Results: Spontaneous secretion of GM-CSF was increased in inflamed mucosa, while secretion of IL-3 was not detected. Release of GM-CSF was enhanced in LPMCs from inflamed mucosa. Mucosal GM-CSF production was correlated to TNF-α production. Colonic epithelial cell line and T cell produced GM-CSF with superantigen stimulation. Conclusion: We revealed pivotal production of GM-CSF but not IL-3 in intestinal lesion of IBD. Increased secretion of GM-CSF might lead to chronic gut inflammation.