Unique variation in genetic selection among Black North American women and its potential influence on pregnancy outcome.

We hypothesize that variations in the frequency of genetic polymorphisms, reflecting ancestral differences in living conditions and exposure to microorganisms, increase susceptibility to adverse pregnancy outcome among present day Black North American women. Striking differences were observed in the frequency of genetic variants between Black and White or Hispanic women in 5 genes (IL1RN, MBL2, PPARA, ATG16L1, CIAS1) associated with inflammation and anti-microbial immunity. The CIAS1 and IL1RN polymorphisms were associated with altered interleukin-1ß serum levels; the MBL2 polymorphism resulted in a decreased serum mannose-binding lectin concentration. Gene polymorphisms associated with an alteration in innate immunity were most frequent in Black women. This may reflect an evolutionary selection in response to an ancient environment containing a high multitude of microorganisms, and may increase susceptibility of Black women to infection-associated preterm birth in the current North American environment.

Inhibition of autophagy by sera from pregnant women.

Autophagy is a process that maintains homeostasis by eliminating senescent or damaged intracellular organelles and proteins. Its role in pregnancy has been scarcely studied. We compared the influence of sera from pregnant and nonpregnant women on autophagy induction. Peripheral blood mononuclear cells (PBMCs) were incubated with sera from 35 pregnant or nonpregnant women in the presence or absence of the autophagy inducer, rapamycin. After 48 hours, the cells were assayed for p62, a cytoplasmic protein essential for autophagy induction. Its concentration in the cytoplasm is inversely proportional to the level of autophagy induction. Sera were tested for immune mediators by enzyme-linked immunosorbent assay. Median (range) p62 concentrations were 6.7 ng/mL (1.1-22.7) for PBMCs incubated with pregnancy sera versus 2.5 ng/mL (0.8-7.7) for nonpregnant sera (P < .0001). In the presence of rapamycin, median p62 levels were 1.3 ng/mL (<0.1-4.9) with pregnancy sera, when compared to 0.6 ng/mL (<0.1-3.3) with control sera (P = .0191). Among the pregnant patients, the p62 level was inversely proportional to the results of a 50-g glucose challenge test (r = -.5630, P = .0005). Sera from pregnant women had elevated levels of insulin-like growth factor 1 (IGF-1), interleukin 13 (IL-13), and transforming growth factor ß1 (TGF-ß1). Autophagy during pregnancy may be inhibited by IGF-1, IL-13, and/or TGF-ß1 and may influence insulin resistance.

Induction of the 72 kDa heat shock protein by glucose ingestion in black pregnant women.

Obese Black women are at increased risk for development of gestational diabetes mellitus and have worse perinatal outcomes than do obese women of other ethnicities. Since hsp72 has been associated with the regulation of obesity-induced insulin resistance, we evaluated associations between glucose ingestion, hsp72 release and insulin production in Black pregnant women. Specifically, the effect of a 50-g glucose challenge test (GCT) on heat shock protein and insulin levels in the circulation 1 h later was evaluated. Hsp27 and hsp60 levels remained unchanged. In contrast, serum levels of hsp72 markedly increased after glucose ingestion (p = 0.0054). Further analysis revealed that this increase was limited to women who were not obese (body mass index <30). Insulin levels pre-GCT were positively correlated with body mass index (p = 0.0189). Median insulin concentrations also increased post GCT in non-obese women but remained almost unchanged in obese women. Post-GCT serum hsp72 concentrations were inversely correlated with post GCT insulin concentrations (p = 0.0111). These observations suggest that glucose intake during gestation in Black women rapidly leads to an elevation in circulating hsp72 only in non-obese Black women. The release of hsp72 may regulate the extent of insulin production in response to a glucose challenge and, thereby, protect the mother and/or fetus from development of hyperglycemia, hyperinsulinemia, and/or immune system alterations.