The Activation of Peroxisome Proliferator-activated Receptor γ Enhances Insulin Signaling Pathways Via Up-regulating Chemerin Expression in High Glucose Treated HTR-8/SVneo Cells

Understanding PPARγ and Its Agonists on Trophoblast Differentiation and Invasion: Potential Therapeutic Targets for Gestational Diabetes Mellitus and Preeclampsia

The increasing incidence of pregnancy complications, particularly gestational diabetes mellitus (GDM) and preeclampsia (PE), is a cause for concern, as they can result in serious health consequences for both mothers and infants. The pathogenesis of these complications is still not fully understood, although it is known that the pathologic placenta plays a crucial role. Studies have shown that PPARγ, a transcription factor involved in glucose and lipid metabolism, may have a critical role in the etiology of these complications. While PPARγ agonists are FDA-approved drugs for Type 2 Diabetes Mellitus, their safety during pregnancy is not yet established. Nevertheless, there is growing evidence for the therapeutic potential of PPARγ in the treatment of PE using mouse models and in cell cultures. This review aims to summarize the current understanding of the mechanism of PPARγ in placental pathophysiology and to explore the possibility of using PPARγ ligands as a treatment option for pregnancy complications. Overall, this topic is of great significance for improving maternal and fetal health outcomes and warrants further investigation.

The role of chemerin in the regulation of cGAS-STING pathway in gestational diabetes mellitus placenta

Recent studies already confirmed that placenta mitochondrial dysfunction is associated with the progression of gestational diabetes mellitus (GDM). Besides, a possible relationship between adipokine chemerin and disulfide-bond A oxidoreductase-like protein (DsbA-L) had been revealed, whereas the potential interaction remains unclear. In addition, very little is still known about the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway and its mechanisms of action in the context of GDM. The present study aims to investigate the underlying mechanism of cGAS-STING pathway and its regulatory relationship with chemerin in GDM. A total of 50 participants, including 25 cases of GDM patients and 25 pregnant women with normal glucose tolerance, were enrolled, and their placenta tissues at term labor were collected. Besides, an insulin resistance cell model was established on the human trophoblastic cell line to explore the molecular mechanism of chemerin on cGAS-STING pathway. Results showed that there were mitochondrial pathological changes in GDM placenta, accompanied by the decreased expression of DsbA-L, increased level of chemerin, and the activation of cGAS-STING pathway. In the insulin resistant cell model, overexpression of chemerin upregulated protein expression of DsbA-L, and recombinant chemerin presented time-dependent inhibition on the cGAS-STING pathway, but this effect was not dependent on DsbA-L. In conclusion, elevated chemerin is probably a protective mechanism, which may be a potential therapeutic strategy for GDM.

Silencing of DsbA-L gene impairs the PPARγ agonist function of improving insulin resistance in a high-glucose cell model

Disulfide-bond A oxidoreductase-like protein (DsbA-L) is a molecular chaperone involved in the multimerization of adiponectin. Recent studies have found that DsbA-L is related to metabolic diseases including gestational diabetes mellitus (GDM), and can be regulated by peroxisome proliferator-activated receptor γ (PPARγ) agonists; the specific mechanism, however, is uncertain. Furthermore, the relationship between DsbA-L and the novel adipokine chemerin is also unclear. This article aims to investigate the role of DsbA-L in the improvement of insulin resistance by PPARγ agonists in trophoblast cells cultured by the high-glucose simulation of GDM placenta. Immunohistochemistry and western blot were used to detect differences between GDM patients and normal pregnant women in DsbA-L expression in the adipose tissue. The western blot technique was performed to verify the relationship between PPARγ agonists and DsbA-L, and to explore changes in key molecules of the insulin signaling pathway, as well as the effect of chemerin on DsbA-L. Results showed that DsbA-L was significantly downregulated in the adipose tissue of GDM patients. Both PPARγ agonists and chemerin could upregulate the level of DsbA-L. Silencing DsbA-L affected the function of rosiglitazone to promote the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (PKB)/AKT pathway. Therefore, it is plausible to speculate that DsbA-L is essential in the environment of PPARγ agonists for raising insulin sensitivity. Overall, we further clarified the mechanism by which PPARγ agonists improve insulin resistance.