Serum levels of TGF-beta 1, cytokines, angiogenic, and anti-angiogenic factors in pregnant women who smoke

Introduction: Women who smoke during pregnancy have a reduced risk of preeclampsia. The mechanism of this association is poorly understood. Preeclampsia is an anti-angiogenic and inflammatory state. Transforming growth factor beta 1 (TGF-131) is a multi-functional anti-inflammatory cytokine that activates membrane bound endoglin on endothelial cells causing a myriad of vascular actions including vasorelaxation. The objective of the study was to determine serum levels of cytokines, angiogenic factors, placental growth factor (PlGF), TGF-13-1 and anti-angiogenic factors, soluble endoglin (sEng) and soluble vascular endothelial growth factor 1 (sVEGFR1) in smoking and non-smoking pregnant women. Methods: Using enzyme-linked immunosorbent and multiplex assays we prospectively analyzed serum levels of PIGF, TGF-131, sEng, sVEGFR1 and cytokines in normotensive pregnant smokers and non-smokers. Exclusion criteria included maternal hypertension, autoimmune disorders, rupture of membranes, evidence of labor and drug use. Results: There were 59 women in the smoking and 66 in the non-smoking group. Compared to non-smoking mothers. maternal age was lower in smoking mothers with no significant difference in other demographic variables. There was no difference in levels of cytokines, anti-angiogenic factors and PlGF between the two groups. Median TGF-131 levels were significantly higher in the smoking group (8120 pg/mL vs 6040 pg/mL, p < 0.001) and remained significant after controlling for confounders. TGF-131 levels correlated positively with cotinine levels in the smoking group. Conclusions: We speculate that higher TGF-131 levels may explain the reduced incidence of preeclampsia in mothers who smoke by being available for action on maternal endothelium even after inactivation by circulating maternal sEng.

Automated summary

This study compared the serum levels of related factors in smoking and non-smoking pregnant women and found that TGF-β1 levels were significantly higher in smoking mothers, which may help explain the lower risk of preeclampsia in smoking mothers.