Abstract

Distinctive patterns of vascular cell adhesion molecule expression in early mouse decidua establish niches that recruit different subtypes of immune cells. In normal gestation day (gd)8 decidua, vascular cell adhesion molecule (VCAM)-1 and mucosal addressin cell adhesion molecule (MAdCAM)-1 occur in different regions enriched by uterine Natural Killer (uNK) cells and monocytes, respectively. UNK cells prepare endometrial spiral arteries for pregnancy-induced structural modifications, a process deficient in decidua of type 1 diabetic mice and women. In non-obese diabetic (NOD) mice, onset of insulitis coincides with islet expression of VCAM-1, MAdCAM-1 and peripheral lymph node addressin (PNAd), a molecule implicated in extravasation of human uNK precursor cells. We used immunohistochemistry to address the combined effects of diabetes and pregnancy on gd6 and 8 pancreatic and decidual expression of VCAM-1, MAdCAM-1 and PNAd and assessed the effect of diabetes on early uNK cell numbers. Normoglycemic (n) and diabetic (d) NOD and C57Bl/6 (B6) mice were studied. Pregnancy increased addressin expression in the pancreata of all mice with n- and d-NOD pancreata having stronger endothelial expression of VCAM-1, MAdCAM-1 and PNAd than B6. VCAM-1 expression was localized to uterine endothelium, including that of spiral arteries and was lower in d- than in n-NOD or B6 mice. MAdCAM-1 was localized to uterine endothelium and was lower in n- and d-NOD than in B6. PNAd expression was only observed in uterine epithelium and was stronger in d- than in n-NOD or B6. In all groups, only VCAM-1 had stronger expression in decidua than in pancreas. A mild elevation in uNK cells was present in n-and d-NOD mice at gd6 but not at gd8 when a higher proliferation index was found compared with B6. Thus, in type 1 diabetic gestations in mice, signals for the recruitment of circulating cells are reduced in uterus and elevated in pancreas.