Enhanced insulin signaling and its downstream effects in iron-overloaded primary hepatocytes from hepcidin knock-out mice

Co-regulation of hepatic steatosis by ferritinophagy and unsaturated fatty acid supply

Both iron overload and iron deficiency have been reported in obesity and metabolic syndromes. Due to the presence of multiple intracellular iron pools and the dynamic nature of iron mobilization and use, the actual status and contribution of free and metabolically active iron toward metabolic syndrome remain to be established. The discovery of nuclear receptor coactivator 4 (NCOA4) as a ferritinophagy receptor provides an opening to address the connection between iron and metabolic diseases. This study aims to specifically dissect the role of hepatic ferritinophagy in lipid metabolism and hepatic steatosis. We conducted a series of Ncoa4 gain- and loss-of-function experiments to examine how ferritinophagy affects lipid metabolism through phenotypic and lipidomic analyses both in vitro and in vivo. We show that ferritinophagy is required to release iron from ferritin cages for biological use, and is induced by lipid loading in vitro and during the development of obesity in vivo. Ncoa4 knockdown impairs mitochondrial morphology and reduces palmitate-induced lipid droplet formation in cultured cells and the development of hepatic steatosis in obese mice models. Importantly, the effect of Ncoa4 deficiency on mitochondrial morphology and lipid accumulation is specifically linked to lipidomic reductions in unsaturated fatty acid content in triglycerides and cardiolipins, and an external supply of unsaturated fatty acids reverses these phenotypes. Conclusion: This study shows that ferritinophagy-derived iron supports fatty acid desaturation and the synthesis of unsaturated fatty acid-rich lipids to reduce lipotoxicity. However, the continuous activation of ferritinophagy contributes to the development of hepatic steatosis and liver damage in obesity.

Impact of Pre-Pregnancy Hemoglobin Level on the Association Between Pre-Pregnancy Body Mass Index and Gestational Diabetes Mellitus: A Retrospective Cohort Study in a Single Center in China

AIM

To assess the impact of maternal pre-pregnancy body mass index (BMI) on gestational diabetes mellitus (GDM) based on different pre-pregnancy hemoglobin levels.

METHODS

This retrospective cohort study included 1289 pregnant women between June 2020 and January 2022. Clinical data were collected by reviewing their medical and antepartum screening records between 24 and 28 gestational weeks, including pre-pregnancy BMI and pre-pregnancy hemoglobin (Hb) levels. The diagnosis of GDM mainly depended on oral glucose tolerance test (OGTT) during 24-28 weeks. Restricted cubic spline (RCS) was used to investigate the association between the pre-pregnancy Hb level and the risk of GDM. Univariate and multivariate logistic regression analyses were applied to evaluate the relative risk of GDM.

RESULTS

Of the 1289 included pregnant women, 187 (14.5%) women were diagnosed with GDM in this study. The pre-pregnancy Hb level was significantly associated with GDM risk, and the pre-pregnancy Hb level of 123 g/L was identified as the threshold to stratify and assess the association between the GDM risk and the pre-pregnancy BMI. For women with a pre-pregnancy Hb level ≥123 g/L, the pre-pregnancy BMI showed a significant association with GDM risk, and the estimated incidence rate of GDM was 7.7%, 14.8%, 36.3% and 44% for underweight, normal-weight, overweight and obese pregnant women, respectively. After adjusting for potential influencing factors of GDM, the respective relative risk was 1.0 (reference), 2.04 (95% CI 0.84, 4.99), 7.06 (2.66, 18.61), and 10.77 (2.85, 40.63) (P for trend < 0.001).

CONCLUSION

In pregnant women with a pre-pregnancy Hb level ≥123 g/L, pre-pregnancy BMI showed a more significant association with GDM risk as compared with those with a pre-pregnancy Hb level <123 g/L.

Hepcidin gene silencing ameliorated inflammation and insulin resistance in adipose tissue of db/db mice via inhibiting METs formation

As a major feature of diabetes, inflammation is closely related to macrophage extracellular traps and the expression of hepcidin upregulated by diabetes is reportedly involved in chronic inflammation. Therefore, we aimed to explore whether hepcidin could be implicated in inflammation and macrophage extracellular traps (METs) formation. The diabetic db/db mouse model was established exhibiting insulin resistance (IR), inflammation, macrophages infiltration and higher expression of hepcidin, where samples were obtained from epididymal adipose tissue. We observed that inflammation and IR improved in adipose tissue of mice treated with hepcidin gene silencing. Furthermore, METs formation could be markedly inhibited via hepcidin gene silencing followed by attenuated inflammatory response due to METs, indicating hepcidin gene silencing played a key role in anti-inflammation by inhibiting METs formation. So, we concluded that hepcidin gene silencing has a potential for treatment of diabetes due to its ability to ameliorate inflammation via inhibiting METs formation.