United States

ENDO 2021

Hepatocyte GHR/STAT5b Signaling Protects Against Liver Injury in NAFLD/NASH Mice Models Independent of Steatosis

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technical paper

Inhibition of Angiopoietin-like (ANGPTL3) Reduces Adipose Tissue Insulin Resistance in Patients with Familial Partial Lipodystrophy

ROR𝛾+ T Cells as Key Players in Thyroid Autoimmunity from Immune Checkpoint Immunotherapy (ICI)

Iodoacetic acid (IAA) – a water disinfection byproduct (DBP) formed from the reaction between an oxidizing disinfectant, i.e. chlorine, and iodide – is an understudied, yet potentially dangerous environmental toxicant. DBPs have been epidemiologically associated with reproductive dysfunction. In vitro studies have indicated that IAA is one of the most cyto- and genotoxic DBPs. Further, murine ovarian research has shown that IAA exposure significantly inhibits antral follicle growth and reduces estradiol levels. Despite this evidence, little is known about the other components of the reproductive axis: the hypothalamus and pituitary. To address this, we tested the hypothesis that IAA exposure would lead to disrupted expression of key hypothalamic and pituitary genes related to reproductive function. We exposed adult female CD1 mice to 0.5, 10, 100, or 500 mg/L IAA in their drinking water from postnatal day 40 (P40) to their first day in diestrus after P75. From this experiment, we collected whole pituitaries and hypothalamic punches containing the arcuate nucleus (ARC), anteroventral periventricular zone (AVPV), and medial preoptic nucleus (mPOA), and processed them for mRNA analysis. We also exposed pituitary explant cultures to IAA to observe direct effects on gene expression. In vivo, we found that mRNA levels of kisspeptin (Kiss1) are significantly increased in the ARC, the region that controls pulsatile GnRH release, at 0.5 and 10 mg/L IAA concentrations. Kiss1 is unchanged in the AVPV, the neuron population responsible for generating the LH surge. We also measured ARC expression of neurokinin B (Tac2) and dynorphin (Pdyn), neuropeptides secreted by kisspeptin co-expressing neurons to autosynaptically stimulate Kiss1 release. We saw no difference in either. GnRH (Gnrh1) expression was also unchanged. Both in vivo at 10 mg/L IAA and in culture, we found IAA exposure significantly reduced Fshb mRNA. Preliminary immunohistochemistry (IHC) data suggests it also leads to an apparent reduction in FSH-positive cells in vitro (N=2). Lhb and the α-subunit (Cga) were unaltered in vivo, though were significantly reduced with in vitro exposure. In neither context was mRNA expression of the GnRH receptor (Gnrhr) changed. Noting apparent direct effects of IAA on the pituitary, we assessed expression of the cell-cycle inhibitor p21 (Cdkn1a), which has been shown to increase with toxicant exposure. We found Cdkn1a increased in vivo at 500 mg/L IAA, trending at 100 mg/L (p=.070), and in vitro. IHC data in vitro suggests a marked increase in P21-positivity following IAA exposure. These data, together with prior ovarian findings, implicate IAA as a potential reproductive axis disruptor at each major level – through ARC Kiss1 expression, Fshb expression in vivo and in vitro, FSH expression in vitro, and Lhb and Cga in vitro. Further, Cdkn1a/P21 induction indicates IAA toxicity at the level of the pituitary.?? 

Exposure to Iodoacetic Acid, a Water Disinfection Byproduct, Leads to Abnormal Expression of Key Reproductive Axis Genes in the Hypothalamus and Pituitary

Low 17β-estradiol (E2) levels suppress luteinizing hormone (LH) release, while high E2 stimulates an LH surge in the positive-feedback required for ovulation. Kisspeptin (Kp) neurons in the anteroventral periventricular (AVPV) and arcuate (ARC) nuclei of hypothalamus have been implicated in E2 positive- and negative-feedback effects, respectively. However, how E2 differentially regulates these two neuronal populations remains unknown. We investigated whether neurons in the AVPV and ARC are differently responsive to changes in E2 levels and the regulatory role of estrogen receptors (ERs). Ovariectomized (OV) rats received oil or E2 at doses of 4 (OVE-4), 40 (OVE-40), or 80 (OVE-80) µg/kg. Rats on diestrus (DI) and proestrus (PRO) were used as physiological controls. OV rats were also treated with 0.02, 0.2 or 2.0 mg/kg of propyl pyrazole triol (PPT), or 6 mg/kg of diarylpropionitrile (DPN). Serial blood samples were collected for hormonal measurements. Brains were processed for immunohistochemistry and qPCR analyses in the AVPV and ARC. The E2 doses gradually increased plasma E2, with PRO levels being attained in OVE-80 rats. OVE-80 rats displayed a PRO-like LH surge, while LH levels were constantly suppressed in OVE-4 rats. Progesterone receptor (PR) was used as an index of E2 responsiveness. PR expression was increased in the AVPV of PRO and OVE-80 rats, associated with c-Fos expression and occurrence of LH surge. In the ARC, both low and high E2 induced PR expression and reduced the number of Kp-immunoreactive (ir) neurons, consistent with the negative feedback effects on LH. E2 at 4 or 80 µg/kg equally induced PR expression in 90% of ARC Kp-ir neurons. Despite the higher sensitivity to E2 in the ARC, the percentage of neurons expressing ERα was lower in the ARC compared with AVPV. However, Esr1 expression was 2-fold higher in the ARC than in AVPV for low E2 levels, whereas both Esr1 and Esr2 were more expressed in the AVPV under high E2 status. Notably, Esr1/Esr2 ratio was twice as high in the ARC as in the AVPV regardless of E2 levels, suggesting a stronger ERβ inhibition over ERα in the AVPV. Accordingly, ERα selective activation with PPT increased PR in the ARC at the doses of 0.2 and 2.0 mg/kg, reducing plasma LH, while only the highest dose was able to stimulate PR expression in the AVPV. ERβ activation with DPN, in turn, had no effect in OV rats but amplified the induction of AVPV PR and the size of the LH surge in OVE-80 rats. Thus, we provide evidence that ARC and AVPV neurons are responsive to low and high E2 levels, respectively. ARC is 10 times more sensitive to ERα activation than AVPV, whereas ERβ positively modulates AVPV responsiveness to high E2. These differential responses to E2 seem to be related to differences in the relative Esr1 and Esr2 expression in the ARC and AVPV. Our findings suggest that hypothalamic differences in the relative expression of ERs play a key role in the bimodal regulation of LH release by E2.?? 

Differential Expression of Estrogen Receptors in the Hypothalamus Underlies the Bimodal Effects of Estradiol on Luteinizing Hormone Release

Background: Next generation sequencing has led to the categorization of thyroid cancer (TC) based on the molecular and transcriptomic profile into the BRAF-like and RAS-like tumors. The BRAF-RAS score (BRS) has been developed to quantify the extent to which the gene expression profile resembles either the BRAFV600E- or RAS-mutant profiles and is utilized as a continuous measure from -1 to +1, respectively. Oncogene-driven signaling pathways have an impact on the intracellular metabolism– glycolysis and oxidative phosphorylation (OXPHOS). There are limited data on the genotype-metabolic phenotype correlation in TC cells. Therefore, the goal of this study was to perform a comprehensive analysis of the association between the BRS and TC cell metabolism.Methods: We analyzed the mRNA expression of key enzymes involved in glycolysis (lactate dehydrogenase LDHA) and OXPHOS (ATP synthase) in 496 BRAF-like and RAS-like human TC tissue samples based on The Cancer Genome Atlas. We performed an in vitro study using 8 TC cell lines– 4 BRAF-like with BRS between -1 and 0, and 4 RAS-like with BRS between 0 and +1. OXPHOS was determined by measuring oxygen consumption rate (OCR) of each cell line using Seahorse XF Cell Mito Stress Test Kit, while Seahorse XF Glycolysis Stress Test Kit was used to measure the extracellular acidification rate (ECAR) due to anaerobic glycolysis The association between the OCR, ECAR and BRS was tested using the Pearson correlation coefficient (r). Student T-test was used to compare the continuous variables between the groups with a p-value of ≤ 0.05 as statistically significant. Results: RAS-like tumors were associated with higher mRNA expression of the OXPHOS marker ATP synthase than BRAF-like lesions, as evidenced by a moderate positive correlation (r = 0.5) between ATP synthase expression and BRS. BRAF-like tumors were characterized by a relatively higher mRNA expression of a glycolytic enzyme LDHA, as documented by a moderate negative correlation (r = -0.6) between LDHA expression and BRS. Consistently, functional in vitro studies revealed that RAS-like cell lines had a higher OXPHOS compared with BRAF-like cell lines (maximum OCR: 2538.4±1601.3 vs 548.5±276.5, p=0.049, respectively). The glycolysis rate was comparable between RAS-like and BRAF-like cell lines (maximum ECAR: 1290.4±520.5 vs 2399.9±1413.1, p=0.19, respectively). There was a strong positive correlation between the BRS and OCR (r=0.78) and a low to negligible negative correlation between BRS and ECAR (r=-0.26) in examined TC cell lines. Conclusions: BRAF-like and RAS-like tumors are characterized by distinct metabolic phenotypes with RAS-like TC more likely to utilize OXPHOS to meet metabolic demands. Therapeutic strategies targeting oncogene-driven signaling pathways and cancer metabolism based on distinct metabolic phenotypes may provide an individualized approach to TC therapy.?? 

BRAF-Like and RAS-Like Thyroid Cancer is Characterized by Distinct Metabolic Phenotypes

Background: Previous adrenal morphological studies have shown that the zona reticularis (ZR) and the zona glomerulosa (ZG) decrease in size with aging. Although several lines of evidence indicate that the hypothalamic-pituitary-adrenal axis becomes hyperactive in elderly, little is known about age-related transformations of the adrenal zona fasciculata (ZF). Objectives: To investigate the morphological and functional changes of the adrenal cortex across the adult life span, with emphasis on: 1) the understudied ZF, and 2) potential sexual dimorphisms. Methods: We used immunohistochemistry to evaluate the expression of several cortical proteins: aldosterone synthase (CYP11B2), visinin-like protein 1 (VSNL1), 3β-hydroxysteroid dehydrogenase type II (HSD3B2), 11β-hydroxylase (CYP11B1) and cytochrome b5 type A (CYB5A). The ZF area was estimated by subtracting the VSNL1-positive (a ZG marker) area from the HSD3B2-expressing area (ZG and ZF). All captured images were quantitated by ImageJ. In addition, we employed liquid chromatography-tandem mass spectrometry to quantify the morning serum concentrations of 6 steroids: cortisol, 11-deoxycortisol (11dF), 17α-hydroxyprogesterone (17OHP4), 11-deoxycorticosterone (DOC), corticosterone, and androstenedione (A4). The Mann-Whitney U test and Spearman’s rank correlation coefficients were used for statistical analysis, as appropriate. Results: We included 60 adrenal glands from 30 men and 30 women, with ages between 18-86 years. The total cortical area was positively correlated with age (r=0.34, p=0.008), and this association was significant only in men (p=0.02). Both the total (VSNL1-positive) and functional ZG (CYP11B2-positive) areas declined abruptly with aging in men (r=-0.57 and -0.76, p=0.001 and p<0.0001, respectively), but not women (p=0.06 and 0.27, respectively). The CYB5A-positive area, marking the ZR, correlated negatively with age (r=-0.76, p<0.0001) in both sexes. In contrast, the estimated ZF area showed a strong positive correlation with age both in men (r=0.59, p=0.0006) and women (r=0.49, p=0.007), while CYP11B1-positive area remained stable across ages (p=0.86). Finally, we measured morning levels of 6 steroids in 149 men and 149 women, with ages between 21-95 years, matched for age and body mass index. Serum cortisol, corticosterone, and DOC levels remained relatively stable across ages (p=0.38, 0.64 and 0.25, respectively), while 11dF levels increased slightly with age (r=0.16 and p=0.007), particularly so in men (p=0.005). Expectedly, 17OHP4 and A4 declined with aging (r=-0.37 and -0.37, p<0.0001 for both). Conclusions: In contrast with the ZG and ZR, the ZF and the total adrenal cortex area enlarge with aging. An abrupt decline of the ZG occurs with age in men, but not in women, possibly contributing to sexual dimorphism in cardiovascular risk.?? 

Hepatocyte GHR/STAT5b Signaling Protects Against Liver Injury in NAFLD/NASH Mice Models Independent of Steatosis

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