Increased Circulating IL-32 Is Associated With Placenta Macrophage-derived IL-32 and Gestational Diabetes Mellitus
Xinmei Huang, Yue Li, Xiaoxu Tong, Yueyue Wu, Rui Zhang, Sheng Li, Jiong Xu, Zhiyan Yu, Zaoping Chen, Tiange Sun, Fang Wang, Qian Yang, Zhangyan Li, Cuijun Gao, Ling Ma, Heyuan Ding, Shufei Zang, Ni Yang, Tie‐Ning Zhang, Jun Liu
Abstract
OBJECTIVE: Placenta-derived inflammation plays a vital role in the pathophysiology of gestational diabetes mellitus (GDM). IL-32 is a novel pro-inflammatory cytokine and metabolic regulator involved in the development of metabolic disease. We investigated the effect of IL-32 in GDM. MATERIALS AND METHODS: First-trimester C-reactive protein (CRP) level was monitored in a case-control study of 186 women with GDM and 186 women without. Placental tissue was lysed and analyzed by high-resolution liquid chromatography-tandem mass spectrometry. Circulating level of inflammatory cytokines IL-32, IL-6, and TNF-α were measured by ELISA kits. The expression of placenta-derived macrophages, inflammatory cytokines, and related pathway proteins were assessed by reverse transcriptase-quantitative PCR, western blot, immunohistochemistry, or immunofluorescence. RESULTS: First-trimester CRP level in peripheral blood was closely associated with glucose and insulin resistance index and was an independent correlation with the development of GDM. High-resolution liquid chromatography-tandem mass spectrometry revealed that placenta-derived CRP expression was dramatically elevated in women with GDM. Interestingly, the expression of placenta-derived IL-32 was also increased and located in the macrophages of placental tissue. Meanwhile, the expression of IL-6, TNF-α, and p-p38 were up-regulated in the placental tissues with GDM. Either IL-6 or TNF-α was colocated with IL-32 in the placental tissue. Importantly, circulating IL-32 throughout pregnancy was increased in GDM and was related to placental-derived IL-32 expression, circulating IL-6, and TNF-α, glucose and insulin resistance index. CONCLUSION: Increased circulating IL-32 throughout pregnancy was closely associated with placenta macrophage-derived IL-32 expression and GDM. First trimester IL-32 level in peripheral blood may serve to predict the development of GDM.