Expression of HLA-G in inflammatory bowel disease provides a potential way to distinguish between ulcerative colitis and Crohn's disease.

In addition to being involved in nutrient uptake, the epithelial mucosa constitute the first line of defense against microbial pathogens. A direct consequence of this physiological function is a very complex network of immunological interactions that lead to a strong control of the mucosal immune balance. The dysfunction of immunological tolerance is likely to be a cause of inflammatory bowel disease (IBD), ulcerative colitis (UC) and Crohn's disease (CD). HLA-G is a non-classical major histocompatibility complex (HLA) class I molecule, which is highly expressed by human cytotrophoblast cells. These cells play a role in immune tolerance by protecting trophoblasts from being killed by uterine NK cells. Because of the deregulation of immune system activity in IBD, as well as the immunoregulatory role of HLA-G, we have analyzed the expression of HLA-G in intestinal biopsies of patients with UC and CD. Our study shows that the differential expression of HLA-G provides a potential way to distinguish between UC and CD. Although the reason for this differential expression is unclear, it might involve a different mechanism of immune regulation. In addition, we demonstrate that in the lamina propria of the colon of patients with UC, IL-10 is strongly expressed. In conclusion, the presence of HLA-G on the surface of intestinal epithelial cell in patients with UC lends support to the notion that this molecule may serve as a regulator of mucosal immune responses to antigens of undefined origin. Thus, this different pattern of HLA-G expression may help to differentiate between the immunopathogenesis of CD and UC

Spatial and temporal mapping of c-kit and its ligand, stem cell factor expression during human embryonic haemopoiesis.

Receptor tyrosine kinases (RTKs) mediate cellular responses to the extracellular signals involved in the regulation of cell differentiation and proliferation. Ligand binding initiates a cascade of events, such as receptor dimerization and tyrosine phosphorylation. The c-kit gene encodes an RTK for stem cell factor (SCF), (c-kit ligand, KL), both of which play a critical role in the differentiation and growth of haemopoietic stem cells (HSCs). We investigated the expression of the c-kit and SCF genes and the presence of the corresponding proteins in haemopoietic tissues during human embryogenesis. We have examined c-kit and SCF transcripts levels in human embryonic yolk sac, the AGM region, and liver at different stages of gestation (days 25 to 63), using RT-PCR amplification combined with PhosphorImager quantitative analysis and RNase Protection Assay (RPA). Weak levels of SCF gene expression were observed in the AGM region (days 25 to 34) and high levels were found in the early-stage liver (day 34). The expression of c-kit transcript was observed in all studied tissues, but at various levels. The restricted presence of SCF protein following mRNA expression was demonstrated in embryonic liver CD38+ haemopoietic cells by immunocytochemistry. These observations suggest that the biological function of the c-kit receptor plays an important role in the early stages of human haemopoiesis, and that c-kit/SCF signalling is particularly involved in early human definitive haemopoiesis

Characterization of human umbilical cord lining-derived epithelial cells and transplantation potential

10.3727/096368910X564085Cell Transplantation2011-121827-1841CTRA