β cell acetate production and release are negligible

BACKGROUND

Studies suggest that short chain fatty acids (SCFAs), which are primarily produced from fermentation of fiber, regulate insulin secretion through free fatty acid receptors 2 and 3 (FFA2 and FFA3). As these are G-protein coupled receptors (GPCRs), they have potential therapeutic value as targets for treating type 2 diabetes (T2D). The exact mechanism by which these receptors regulate insulin secretion and other aspects of pancreatic β cell function is unclear. It has been reported that glucose-dependent release of acetate from pancreatic β cells negatively regulates glucose stimulated insulin secretion. While these data raise the possibility of acetate's potential autocrine action on these receptors, these findings have not been independently confirmed, and multiple concerns exist with this observation, particularly the lack of specificity and precision of the acetate detection methodology used.

METHODS

Using Min6 cells and mouse islets, we assessed acetate and pyruvate production and secretion in response to different glucose concentrations, via liquid chromatography mass spectrometry.

RESULTS

Using Min6 cells and mouse islets, we showed that both intracellular pyruvate and acetate increased with high glucose conditions; however, intracellular acetate level increased only slightly and exclusively in Min6 cells but not in the islets. Further, extracellular acetate levels were not affected by the concentration of glucose in the incubation medium of either Min6 cells or islets.

CONCLUSIONS

Our findings do not substantiate the glucose-dependent release of acetate from pancreatic β cells, and therefore, invalidate the possibility of an autocrine inhibitory effect on glucose stimulated insulin secretion.

Geographic variation in the association between Hashimoto's thyroiditis and Papillary thyroid carcinoma, a meta-analysis

PURPOSE

The association between papillary thyroid cancer (PTC) and Hashimoto's thyroiditis (HT) remains a matter of debate. Several genetic and environmental factors have been found to influence this association. Because of the variation in these factors among different populations, we conducted a country- and region-based meta-analysis to examine whether the geographic area influences this association.

METHODS

We searched PubMed and Web of Science databases for original articles that investigated the association between HT and PTC from February 1955 to February 28, 2023. The included studies were stratified according to their country and region of origin. Various subgroup analyses were conducted. The primary outcome was the pooled relative risk (RR) and its 95% confidence interval (CI) for each region and country.

RESULTS

Forty-six studies including a total of 93,970 participants met our inclusion criteria. They originated from 16 countries distributed in five regions. Significant variation was found among countries but not among regions. Upon analysis of all 46 included studies, countries were classified based on their RR and its 95% CI. Excluding countries with pooled sample sizes <500, Sri Lanka (RR 4.23, 95% CI 2.91-6.14), Poland (RR 3.16, 95% CI 2.79-3.57) and Japan (2.68, 2.14-3.36) showed the strongest association between HT and PTC while Greece (RR 1.06, 95% CI 1.00-1.13), Spain (RR 0.70, 95% CI 0.23-2.11), and Jordan (0.62, 0.32-1.32) showed no significant association.

CONCLUSION

Our findings revealed a variation in the association between HT and PTC among countries but not among regions. The country-to-country variation could be due to certain genetic and/or environmental factors subject to geographic variation that influence this association. These findings may help guide health policies aiming to mitigate the risk of PTC in the HT population by helping identify high-risk and low-risk countries.

Liver-specific overexpression of HKDC1 increases hepatocyte size and proliferative capacity

A primary role of the liver is to regulate whole body glucose homeostasis. Glucokinase (GCK) is the main hexokinase (HK) expressed in hepatocytes and functions to phosphorylate the glucose that enters via GLUT transporters to become glucose-6-phosphate (G6P), which subsequently commits glucose to enter downstream anabolic and catabolic pathways. In the recent years, hexokinase domain-containing-1 (HKDC1), a novel 5th HK, has been characterized by our group and others. Its expression profile varies but has been identified to have low basal expression in normal liver but increases during states of stress including pregnancy, nonalcoholic fatty liver disease (NAFLD), and liver cancer. Here, we have developed a stable overexpression model of hepatic HKDC1 in mice to examine its effect on metabolic regulation. We found that HKDC1 overexpression, over time, causes impaired glucose homeostasis in male mice and shifts glucose metabolism towards anabolic pathways with an increase in nucleotide synthesis. Furthermore, we observed these mice to have larger liver sizes due to greater hepatocyte proliferative potential and cell size, which in part, is mediated via yes-associated protein (YAP) signaling.

RF17 | PSUN202 DICER1 Gene Mutation: Association With Thyroid Cancer and Other Endocrine Tumors

Introduction

DICER1 syndrome is a rare autosomal dominant hereditary tumor predisposition syndrome and is known to have many endocrine manifestations.

Case Description

A 21-year-old female with DICER1 syndrome presented to the clinic to establish care. She had a significant family history of DICER1 mutation in her father and two siblings. She was diagnosed with malignant neuroepithelioma of the uterus at the age of 12 and was treated with cisplatin/cyclophosphamide. Hepatic embryonal rhabdomyosarcoma and pleuropulmonary blastoma type 1 were diagnosed at the age of 16 and she underwent hepatic lobectomy, left lower lung lobectomy, and received additional chemotherapy.

She was first diagnosed with multiple thyroid nodules at the age of 14. Surveillance thyroid ultrasounds were performed biannually over the next 6 years. She also had multiple thyroid nodule FNAs, all showing benign results. Subsequently, CT chest revealed enlarging thyroid nodules with a chest wall lesion which prompted total thyroidectomy. Surgical pathology confirmed a 0.5 cm papillary thyroid carcinoma involving the left superior thyroid lobe; there was no lymph node involvement or extrathyroidal invasion and the surgical margins were intact. Surveillance ultrasounds have not shown any residual or recurrent disease. Excision of chest wall lesion showed nodular epithelia proliferation with rare eccrine duct present in the margin.

She also suffered from secondary amenorrhea from chemotherapy induced ovarian failure. She was started on estrogen patch and cyclical progesterone therapy, following which menstrual cycles resumed.

Discussion

DICER1 encodes an Rnase III endonuclease that processes miRNA precursor hairpins into mature miRNAs. miRNA-mediated effects that lead to this syndrome is due to loss-of-function in tumor suppressor genes or gain of function in oncogenes. This predisposes patients to a variety of different tumors, including many endocrine tumors.

Multiple thyroid nodules, as was seen in our patient, is a common finding in individuals with DICER1 syndrome. Rates of thyroid cancer are 10–20% higher in these patients. Follicular variant of papillary cancer and follicular thyroid cancer are the most common histologies seen. Thyroid cancer in these patients usually follows an indolent course with thyroidectomy typically curative. For screening of thyroid cancer, recommendations include annual thyroid examination, with some authors advocating for thyroid ultrasounds starting at the age 8, with repeated scans every 3 years if normal.

Other endocrine tumors that are associated with DICER1 mutations include pituitary blastomas and pineoblastoma. Patients with pituitary blastomas may present with features of Cushing disease with elevated ACTH. Pineoblastoma can be detected with surveillance brain MRI, but routine screening for these tumors is not currently recommended as these tumors are rare, even within this syndrome.

References

Endocr Relat Cancer. 2018 Mar;25(3): R197-R208.

Presentation: Sunday, June 12, 2022 12:48 p.m. - 12:53 p.m.

Critical appraisal of tocilizumab in the treatment of moderate to severe rheumatoid arthritis

Recent advances in our understanding of the role of interleukin (IL)-6 in autoimmunity and in particular rheumatoid arthritis (RA) have brought about important changes in the way we think about autoimmune diseases. Encouraging data from several phase III clinical trials of tocilizumab, a humanized monoclonal antibody against IL-6R, have led to its approval in Europe for the treatment of moderate to severe RA. Data on clinical efficacy, patient-reported outcomes, safety, and cost-effectiveness with the use of tocilizumab in patients with RA will be summarized in this review, with particular emphasis on phase III clinical trials. Furthermore, adverse events associated with the use of tocilizumab will be reviewed. Future clinical trials will evaluate the role of tocilizumab in other autoimmune diseases. The goal of this review is to describe the current understanding of the role of IL-6 in mediating the inflammatory response in RA, as well as the role of tocilizumab in the treatment of RA and the evolving role of this agent in other autoimmune diseases.