The influence of the lack of insulin receptor substrate 2 (IRS2) on the thyroid gland

Thyroid-disrupting effects of bisphenol S in male Wistar albino rats: Histopathological lesions, follicle cell proliferation and apoptosis, and biochemical changes

In this presented study, the aim was to investigate the toxic effects of bisphenol S (BPS), one of the bisphenol A analogues, on the thyroid glands of male Wistar albino rats. Toward this aim, the rats (n = 28) were given a vehicle (control) or BPS at 3 different doses, comprising 20, 100, and 500 mg/kg of body weight (bw) via oral gavage for 28 days. According to the results, BPS led to numerous histopathological changes in the thyroid tissue. The average proliferation index values among the thyroid follicular cells (TFCs) displayed increases in all of the BPS groups, and significant differences were observed in the BPS-20 and BPS-100 groups. The average apoptotic index values in the TFCs were increased significantly in the BPS-500 group. The serum thyroid-stimulating hormone and serum free thyroxine levels did not show significant changes after exposure to BPS; however, the serum free triiodothyronine levels displayed significant decreases in all 3 of the BPS groups. BPS was determined to cause significant increases in the antioxidant enzyme activities of catalase, superoxide dismutase, glutathione-S-transferase, glutathione peroxidase, as well as a significantly decreased content of reduced glutathione. The malondialdehyde level in the thyroid tissue was elevated significantly in the BPS-500 group. The data obtained herein revealed that BPS has thyroid-disrupting potential based on structural changes, follicle cell responses, and biochemical alterations including a decreased serum free triiodothyronine level and increased oxidative stress.

Altered macronutrient composition and genetics influence the complex transcriptional network associated with adiposity in the Collaborative Cross

Background

Obesity is a serious disease with a complex etiology characterized by overaccumulation of adiposity resulting in detrimental health outcomes. Given the liver’s critical role in the biological processes that attenuate adiposity accumulation, elucidating the influence of genetics and dietary patterns on hepatic gene expression is fundamental for improving methods of obesity prevention and treatment. To determine how genetics and diet impact obesity development, mice from 22 strains of the genetically diverse recombinant inbred Collaborative Cross (CC) mouse panel were challenged to either a high-protein or high-fat high-sucrose diet, followed by extensive phenotyping and analysis of hepatic gene expression.

Results

Over 1000 genes differentially expressed by perturbed dietary macronutrient composition were enriched for biological processes related to metabolic pathways. Additionally, over 9000 genes were differentially expressed by strain and enriched for biological process involved in cell adhesion and signaling. Weighted gene co-expression network analysis identified multiple gene clusters (modules) associated with body fat % whose average expression levels were influenced by both dietary macronutrient composition and genetics. Each module was enriched for distinct types of biological functions.

Conclusions

Genetic background affected hepatic gene expression in the CC overall, but diet macronutrient differences also altered expression of a specific subset of genes. Changes in macronutrient composition altered gene expression related to metabolic processes, while genetic background heavily influenced a broad range of cellular functions and processes irrespective of adiposity. Understanding the individual role of macronutrient composition, genetics, and their interaction is critical to developing therapeutic strategies and policy recommendations for precision nutrition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12263-022-00714-x.

Metformin in Differentiated Thyroid Cancer: Molecular Pathways and Its Clinical Implications

Metformin is a synthetic biguanide that improves insulin sensitivity and reduces hepatic gluconeogenesis. Aside being the first-line therapy for Type 2 Diabetes (T2D), many pleiotropic effects have been discovered in recent years, such as its capacity to reduce cancer risk and tumorigenesis. Although widely studied, the effect of metformin on thyroid cancer remains controversial. Potential mechanisms for its growth inhibitory effects have been elucidated in various preclinical studies that involved pathways related to adenosine mono-phosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), mitochondrial glycerophosphate dehydrogenase (mGPDH), and the nuclear factor κB (NF-κB). Hyperinsulinemia increases cell glucose uptake and oxidative stress, and promotes thyroid cell growth, leading to hyperproliferation, carcinogenesis, and the development of malignant tumors. Furthermore, it has also been related to thyroid nodules size in nodular disease, as well as tumoral size in patients with thyroid cancer. Several clinical studies concluded that metformin might have an important role as an adjuvant therapy to reduce the growth of benign and malignant thyroid neoplasms. This suggests that metformin might be useful for patients with differentiated or poorly differentiated thyroid cancer and metabolic diseases such as insulin resistance or diabetes.

The Detection of Thyroid Nodules in Prediabetes Population and Analysis of Related Factors

Purpose

To explore the detection of thyroid nodules (TN) and related influencing factors in the population of prediabetes (PreDM) in northwest China’s Gansu Province.

Materials and Methods

A multi-stage stratified cluster random sampling method was used to select adult Han residents in Gansu Province for investigation, and recorded the clinical data of the subjects. The χ² test was used to analyze the difference in TN detection rate of the PreDM population. Logistic regression analyzed the risk factors of TN in the PreDM population.

Results

This study included 2659 people with normal glucose tolerance (NGT) and PreDM, of which 440 people were detected with TN. Among the PreDM population, the TN detection rate was higher than in the NGT population (24.48% vs 15.00%; P<0.05). The detection rate of TN in the impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and IFG+IGT group was also significantly higher than that in the NGT population (X²=4.117, X²=13.187, X²=13.016, all P<0.05), and of which, the IFG+IGT group was the highest (32.20%). The general trend of TN in the IFG, IGT and PreDM population all increased with age. General data showed that BMI, waist-to-height ratio, waist circumference, TG, TC, LDL-C, FPG, 2h PG, HbA1c and TSH indicators in the TN group were higher than those in the Non-TN group (P<0.05). The logistic regression suggested that the risk factors for TN in the PreDM population were female, age increase, high SP, high TSH, high FPG, high LDL-C, hypertension and family history of diabetes (all P<0.05).

Conclusion

The detection rate of TN in the PreDM population is high, especially in the IFG+IGT population. Middle-aged and elderly people with hypertension and abnormal glucose and lipid metabolism should be treated reasonably and regularly, and their TN should be screened and followed up.

The lack of Irs2 induces changes in the immunocytochemical expression of aromatase in the mouse retina

Insulin receptor substrate (Irs) belongs to a family of proteins that mediate the intracellular signaling of insulin and IGF-1. Insulin receptor substrate 2 (Irs2) is necessary for retinal function, since its failure in Irs2-deficient mice in hyperglycemic situation promotes photoreceptor degeneration and visual dysfunction, like in diabetic retinopathy. The expression of P450 aromatase, which catalyzes androgen aromatization to form 17ß-estradiol, increases in some neurodegenerative diseases thus promoting the local synthesis of neuroestrogens that exert relevant neuroprotective functions. Aromatase is also expressed in neurons and glial cells of the central nervous system (CNS), including the retina. To further understand the role of Irs2 at the retinal level, we performed an immunocytochemical study in adult normoglycemic Irs2-deficient mice. For this aim, the retinal immunoexpression of neuromodulators, such as aromatase, glutamine synthetase (GS), and tyrosine hydroxylase (TH) was analyzed, joint to a morphometric and planimetric study of the retinal layers. Comparing with wild-type (WT) control mice, the Irs2-knockout (Irs2-KO) animals showed a significant increase in the immunopositivity to aromatase in almost all of the retinal layers. Besides, Irs2-KO mice exhibited a decreased immunopositive reaction for GS and TH, in Müller and amacrine cells, respectively; morphological variations were also found in these retinal cell types. Furthermore, the retina of Irs2-KO mice displayed alterations in the structural organization, and a generalized decrease in the retinal thickness was observed in each of the layers, except for the inner nuclear layer. Our findings suggest that the absence of Irs2 induces retinal neurodegenerative changes in Müller and amacrine cells that are unrelated to hyperglycemia. Accordingly, in the Irs2-KO mice, the increased retinal immunocytochemical reactivity of aromatase could be associated with an attempt to repair such neural retina injuries by promoting local neuroprotective mediators.

Methyl Caffeate Isolated from the Flowers of Prunus persica (L.) Batsch Enhances Glucose-Stimulated Insulin Secretion

Phenolic compounds from natural products are considered effective enhancers of insulin secretion to prevent and treat type 2 diabetes (T2DM). The flowers of Prunus persica (L.) Batsch also contain many phenolic compounds. In this study, the extract of flowers of P. persica (PRPE) exhibited an insulin secretion effect in a glucose-stimulated insulin secretion (GSIS) assay, which led us to isolate and identify the bioactive compound(s) responsible for these effects. Compounds isolated from PRPE were screened for their efficacy in INS-1 rat pancreatic β-cells. Among them, caffeic acid (5), methyl caffeate (6), ferulic acid (7), chlorogenic acid (8), naringenin (11), nicotiflorin (12), and astragalin (13) isolated from PRPE increased GSIS without inducing cytotoxicity. Interestingly, the GSIS effect of methyl caffeate (6) as a phenolic compound was similar to gliclazide, an antidiabetic sulfonylurea drug. Western blot assay showed that methyl caffeate (6) enhanced the related signaling proteins of the activated pancreatic and duodenal homeobox-1 (PDX-1) and peroxisome proliferator-activated receptor-γ (PPAR-γ), but also the phosphorylation of the total insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), and Akt, which influence β-cell function and insulin secretion. This study provides evidence that methyl caffeate (6) isolated from PRPE may aid in the management of T2DM.

Insulin-Like Growth Factor Pathway and the Thyroid

The insulin-like growth factor (IGF) pathway comprises two activating ligands (IGF-I and IGF-II), two cell-surface receptors (IGF-IR and IGF-IIR), six IGF binding proteins (IGFBP) and nine IGFBP related proteins. IGF-I and the IGF-IR share substantial structural and functional similarities to those of insulin and its receptor. IGF-I plays important regulatory roles in the development, growth, and function of many human tissues. Its pathway intersects with those mediating the actions of many cytokines, growth factors and hormones. Among these, IGFs impact the thyroid and the hormones that it generates. Further, thyroid hormones and thyrotropin (TSH) can influence the biological effects of growth hormone and IGF-I on target tissues. The consequences of this two-way interplay can be far-reaching on many metabolic and immunologic processes. Specifically, IGF-I supports normal function, volume and hormone synthesis of the thyroid gland. Some of these effects are mediated through enhancement of sensitivity to the actions of TSH while others may be independent of pituitary function. IGF-I also participates in pathological conditions of the thyroid, including benign enlargement and tumorigenesis, such as those occurring in acromegaly. With regard to Graves' disease (GD) and the periocular process frequently associated with it, namely thyroid-associated ophthalmopathy (TAO), IGF-IR has been found overexpressed in orbital connective tissues, T and B cells in GD and TAO. Autoantibodies of the IgG class are generated in patients with GD that bind to IGF-IR and initiate the signaling from the TSHR/IGF-IR physical and functional protein complex. Further, inhibition of IGF-IR with monoclonal antibody inhibitors can attenuate signaling from either TSHR or IGF-IR. Based on those findings, the development of teprotumumab, a β-arrestin biased agonist as a therapeutic has resulted in the first medication approved by the US FDA for the treatment of TAO. Teprotumumab is now in wide clinical use in North America.