Placental mast cell heterogeneity in pregnancy complicated by diabetes class C

Abstract

IntroductionIn humans, a strict classification into mucosal and connective tissue-type mast cells (MC) is not possible [1]. On the basis of neutral protease composition, human MC have been classified into two phenotypes. One phenotype, which is designated MC T (tryptase-positive, chymase-negative mast cells), contains tryptase but not chymase, while another phenotype, designated MC TC (tryptase-positive, chymase-positive mast cells), expresses both tryptase and chymase [2]. No tryptase-negative subpopulations of mast cells in humans have been found [1,3], although the MC type in human placenta is still unknown [4]. Some investigators have studied correlations between placental MC number and placental pathology during the course of pregnancy and labour [5,6]. Class C diabetes in pregnancy (after White) is the last stage without recognized vascular changes [7]. The results of our recent studies showed, that in diabetes class C an increased density of the villous network of vessels correlates with higher histamine concentrations and increased MC number [6]. Here we examined numbers and distribution of MC T and MC TC in White class C diabetes. Materials and methodsNine placentas obtained from nulliparas after single pregnancies complicated by diabetes White class C (group I; mean gestational age 251 ± 7 days), were compared with nine placentas obtained from gestationally matched preterm controls (group II; mean gestational age 253 ± 5 days). The mean (± SD) fetal/placental weights for group I and group II were: 3431 ± 316 g / 569 ± 51 g, and 3332 ± 321 g / 553 ± 70 g, respectively. The courses of the diabetic pregnancies were normal, without additional medication, except insulin. The control of glycemia in all cases was satisfactory: the levels of fraction of glycosylated hemoglobin (HbA 1c ) in all trimesters of pregnancy were less than 7.5 % (6.3 ± 0.5%).Five placental specimens were obtained immediately after labour in standardised manner, [6]. The samples were fixed in 4 % buffered formalin, embedded in paraffin wax or frozen and cut at 6 mm (5 cuts for each sample). The MC number in placental cuts was estimated after staining with toluidine blue or alcian blue. MC were counted in calibrated areas, using light microscopy with an image analysis system (Quantimet 500C + by Leica). The total number of MC represents the summation of MC numbers from all analysed areas of each placenta. MC protease content was examined using a double-enzyme immunohistochemical staining technique on paraffin sections. Mouse monoclonal antibodies to human MC tryptase and chymase were diluted 1: 2000 -1: 3000 in tris-buffered saline (TBS, pH 7.6) and applied to the tissue sections overnight (12 -14 h) at 4°C. After triple 10 min washing in TBS, biotinylated horse anti-mouse antibody diluted 1: 20 in TBS was applied to the sections for 30 min at room temperature. Sections were washed in TBS and the alkaline phosphatase or peroxidase was developed with appropriate chromogenic substrate at 37°C for 30 min. For each placenta the total number ...

Mast cell-derived vascular endothelial growth factor (VEGF) and microvascular density in diabetic placentae

“…MC and VEGF have been implicated in various conditions that are accompanied by neovascularization [7,8].…”

Fractalkine (CX3CL1) and Its Receptor CX3CR1 May Contribute to Increased Angiogenesis in Diabetic Placenta

“…For example, we previously observed both an increase in the number of mast cells in the diabetic placenta and changes in their heterogeneity, namely, a shift of the quantitative balance between tryptase-positive and tryptase/chymase-positive cells [51]. This shift may influence the placental cytokine network profile in diabetes, possibly including an increase in the local CX3CL1 concentration.…”