Mast Cells and Histamine in the Pathophysiology of Diabetic Placenta

摘要

Human placental tissue contains relatively high amounts of histamine (HA) accumulated mostly in the vesicular structures of mast cells (MC). On the basis of neutral protease composition, human MC have been classified into two phenotypes: MCT (tryptase-positive, chymase-negative MC) and MCTC (tryptase-positive, chymase-positive MC) Degranulation of MC releases locally numerous vasoactive, angiogenic and proinflammatory mediators in addition to HA. The role of placental MC and MC-related mediators in normal course and complicated pregnancies are still under investigation. Accumulated data indicate that inflammatory-like processes and changed angiogenesis observed in diabetic placenta may be caused by an imbalance beetween tissular needs and availability of the MC-related mediators. This presentation, based on author's own scientific experience and the results of others, considers placental MC number and their heterogeneity (MCT/MCTC ratio), HA concentration in placental tissue, density of the network of placental vessels, and histamine H1, H2 and H4 receptors expression, with respect to the pathophysiology of diabetic placenta. Analyzed material was limited to the class C of diabetes in pregnancy (after White), the last stage without recognized vascular changes. The results showed that in diabetes class C increased density of the villous network of vessels correlates with both significantly (p < 0.05) higher MC number and increased HA concentration. MCT/MCTC ratio was higher (p < 0.05 in diabetic pregnancy as well as the immunoreactivity for H4. In conclusion, overview of the results may lead to the suggestion that MC and HA contribute to abnormal function of the placenta in diabetes class C.