Effects of bile acids on iodide uptake and deoxyribonucleic acid synthesis in porcine thyroid cells in primary culture

Huangqi Jianzhong decoction improves gastric intestinal metaplasia in rats by regulating the gut‒thyroid axis

BACKGROUND

Gastric intestinal metaplasia (GIM) is a crucial stage in the progression of gastric cancer. Huangqi Jianzhong decoction (HQJZ) has emerged as a leading therapeutic strategy for treating GIM patients with cold intolerance in traditional Chinese medicine clinics, but the detailed mechanism remains poorly understood.

OBJECTIVE

The present study aimed to elucidate the molecular mechanism by which HQJZ alleviates GIM in a rat model on the basis of the gut microbiota‒thyroid axis.

METHODS

A GIM rat model was established by administering cold salicylic acid and sodium deoxycholate (SDC) for 12 weeks, followed by gavage treatment with HQJZ for an additional four weeks. Lianpu Yin (LPY) was used as a comparison formula. The cold tolerance characteristics of GIM rats were evaluated using cold tolerance and temperature‒tropism experiment experiments. Thyroid pathological changes were evaluated with HE staining, and thyroid function was measured via quantification of T3 and T4 levels with ELISA. The gut microbiota was analyzed using 16S rRNA gene sequencing, and fecal butyric acid and serum metabolites were quantified utilizing metabolomics. The key molecular mechanism was verified in the Nthy-ori 3-1 cell model.

RESULTS

HQJZ, but not LPY, significantly improved gastric mucosa and thyroid tissue lesions in GIM rats, increased the serum levels of the thyroid hormones T3 and T4, and enhanced cold tolerance. HQJZ treatment promoted the enrichment of fecal butyrate-producing bacteria, specifically the bacteria Allobaculum and Bifidobacterium, resulting in a marked increase in fecal butyric acid concentrations. HQJZ treatment significantly diminished the levels of mitochondrial damage-related serum metabolites, including p-cresol sulfate and indoxyl sulfate. Mechanistically, in vivo investigations further demonstrated that butyric acid not only improved thyroid tissue lesions but also restored the fecal microbiota structure, as well as low-temperature tropism, in GIM rats. Furthermore, butyrate diminished the mitochondrial damage induced by SDC in these cells, as evidenced by decreased reactive oxygen species levels and increased ATP production and mitochondrial membrane potential. Importantly, in vitro studies revealed that butyrate protected against SDC-induced injury in Nthy-ori 3-1 cells through the upregulation of TG, TPO, and TSHR expression.

CONCLUSIONS

HQJZ promotes cold tolerance and improves thyroid function in GIM rats by enriching gut butyrate-producing bacteria.

Dietary Bile Acids Enhance Growth, and Alleviate Hepatic Fibrosis Induced by a High Starch Diet via AKT/FOXO1 and cAMP/AMPK/SREBP1 Pathway in Micropterus salmoides

A 10-week feeding trial was conducted to investigate the effects of dietary bile acids (BA) on growth, glucose and lipid metabolism, liver histopathology, and the underlying regulation mechanism on AKT/FOXO1 (forkhead box O1) and cAMP/AMPK/SREBP1 (sterol regulatory element-binding protein 1) pathway in largemouth bass (Micropterus salmoides) fed with a high starch diet. Six experimental diets were prepared with BA levels at 0 (B0), 80 (B80), 160 (B160), 240 (B240), 300 (B300), and 600 (B600) mg/kg in a basal diet with 18.7% starch. Each diet was fed to six replicates with 30 fish (6.17 ± 0.03 g) in each tank. The highest weight gain rate (WGR) was observed in B300 group and the optimal level of BA was estimated at 475 mg/kg by a monistic cubic equation regression analysis. Dietary BA inclusion decreased hepatosomatic index (HSI) and hepatic lipid content significantly. The fish in B300 group clearly showed alleviated hepatic fibrosis, but more steatohepatitis symptoms diagnosed with various histopathological and immunofluorescence analysis. 10 out of 12 samples were observed hepatic fibrosis in B0 group while only two fibrosis samples in B300 group. The promoted liver histopathology by dietary BA was related to improved glucose and lipid metabolism. Dietary BA inhibited the expression of G6Pase by activating AKT and reducing FOXO1 transcription, which improved the regulation ability of gluconeogenesis, activated cAMP/AMPK and repressed SREBP1 transcription to inhibit hepatic lipogenesis, which prevented hepatic lipid accumulation. In conclusion, dietary BA enhanced the growth and alleviated liver fibrosis induced by a high starch diet to steatohepatitis/recovery symptom via improving glucose and lipid metabolism, which regulated by AKT/FOXO1 and cAMP/AMPK/SREBP1 pathway in largemouth bass.

Bile acids and signal transduction: role in glucose homeostasis

Bile acids are mainly recognized for their role in dietary lipid absorption and cholesterol homeostasis. However, recent progress in bile acid research suggests that bile acids are important signaling molecules that play a role in glucose homeostasis. Among the various supporting evidence, several reports have demonstrated an improvement of the glycemic index of type 2 diabetic patients treated with diverse bile acid binding resins. Herein, we review the diverse interactions of bile acids with various signaling/response pathways, including calcium mobilization and protein kinase activation, membrane receptor-mediated responses, and nuclear receptor responses. Some of the effects of the bile acids are direct through the activation of specific receptors, i.e., TGR5, CAR, VDR, and FXR, while others imply modulation of the hormonal, growth factor and/or neuromediator responses, i.e., glucagon, EGF, and acetylcholine. We also discuss recent evidence implicating the interaction of bile acids with glucose homeostasis mechanisms, with the integration of our understanding of how the signaling mechanisms modulated by bile acid could regulate glucose metabolism.

Sodium iodide symporter in health and disease

Radioiodine-concentrating activity in thyroid tissues has allowed the use of radioiodine as a diagnostic and therapeutic agent for patients with thyroid disorders such as well-differentiated thyroid cancer. However, some extrathyroidal tissues also take up radioiodine, contributing to unwanted side effects of radioiodine therapy. Now that the molecule that mediates radioiodine uptake, the sodium iodide symporter (NIS), has been cloned and characterized, it may be possible to develop novel strategies to differentially modulate NIS expression and/or activity, enhancing it in target tissues and impeding it in others. In addition to restoring NIS expression/activity to ensure sufficient radioiodine uptake for the diagnosis and treatment of advanced thyroid cancers, we envision that it may be possible to selectively increase or confer NIS expression/activity in tumors of nonthyroidal tissues to facilitate the use of radioiodine in their diagnosis and treatment. We also consider the molecular basis of thyroid and nonthyroid disorders that may be complicated by NIS deregulation. Finally, we explore the use of NIS as an imaging reporter gene to monitor the expression profile of the transgene in transgenic mouse animal models and in patients undergoing gene therapy clinical trials.