RESUMO
Interleukin-4 activated human macrophages (M(IL4) promote epithelial wound healing and exert an anti-colitic effect in a murine model. Blood monocyte-derived M(IL4)s from healthy donors and individuals with Crohn's disease had increased mRNA expression of the calcitonin gene-related peptide (CGRP) receptor chain, RAMP1, raising the issue of neural modulation of the M(IL4)s reparative function. Thus, human (MIL4)s were treated with CGRP and the cells phagocytotic, epithelial wound repair and anti-colitic functions were assessed. Initial studies confirmed up-regulation of expression of the CGRP receptor, which was localized to the cell surface and was functional as determined by CGRP-evoked increases in cAMP. M(IL4,CGRP)s had increased mannose receptor (CD206) and FcgRIIa (CD32a) mRNA expression, a subtle, but significant increase in phagocytosis, and decreased chemokine production following exposure to E. coli. When delivered systemically (106 cells, ip.) to oxazolone-treated rag1-/- mice, M(IL4,CGRP) had an anti-colitic effect superior to M(IL4)s from the same blood donor. Conditioned medium (CM) from M(IL4,CGRP) had increased amounts of TGFb and increased wound-healing capacity compared to matched M(IL4)-CM in the human CaCo2 epithelial cell line in vitro wounding assay. Moreover, M(IL4,CGRP)s displayed increased cyclooxygenase (COX)-1 and prostaglandin D2, and CM from M(IL4,CGRP)s treated with indomethacin or SC-560 to inhibit COX1 activity failed to promote repair of wounded CaCo2 cell monolayers. These data confirm the human M(IL4)s' anti-colitic effect that was enhanced by CGRP, and may be partially dependent on macrophage COX1/PDG2 activity. Thus, input from neurone-derived molecules is a local modifier capable of boosting the anti-colitic effect of autologous M(IL4) transfer.
RESUMO
Inflammatory bowel diseases (IBD), encompassing ulcerative colitis (UC), and Crohn's disease (CD), are a group of disorders characterized by chronic, relapsing, and remitting, or progressive inflammation along the gastrointestinal tract. IBD is accompanied by massive infiltration of circulating leukocytes into the intestinal mucosa. Leukocytes such as neutrophils, monocytes, and T-cells are recruited to the affected site, exacerbating inflammation and causing tissue damage. Current treatments used to block inflammation in IBD include aminosalicylates, corticosteroids, immunosuppressants, and biologics. The first successful biologic, which revolutionized IBD treatment, targeted the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFα). Infliximab, adalimumab, and other anti-TNF antibodies neutralize TNFα, preventing interactions with its receptors and reducing the inflammatory response. However, up to 40% of people with IBD become unresponsive to anti-TNFα therapy. Thus, more recent biologics have been designed to block leukocyte trafficking to the inflamed intestine by targeting integrins and adhesins. For example, natalizumab targets the α4 chain of integrin heterodimers, α4ß1 and α4ß7, on leukocytes. However, binding of α4ß1 is associated with increased risk for developing progressive multifocal leukoencephalopathy, an often-fatal disease, and thus, it is not used to treat IBD. To target leukocyte infiltration without this life-threatening complication, vedolizumab was developed. Vedolizumab specifically targets the α4ß7 integrin and was approved to treat IBD based on the presumption that it would block T-cell recruitment to the intestine. Though vedolizumab is an effective treatment for IBD, some studies suggest that it may not block T-cell recruitment to the intestine and its mechanism(s) of action remain unclear. Vedolizumab may reduce inflammation by blocking recruitment of T-cells, or pro-inflammatory monocytes and dendritic cells to the intestine, and/or vedolizumab may lead to changes in the programming of innate and acquired immune cells dampening down inflammation.