Abstract Objective Defective glucose uptake in adipocytes leads to impaired metabolic homeostasis and insulin resistance, hallmarks of type 2 diabetes. Extracellular ATP-derived nucleotides and ...nucleosides are important regulators of adipocyte function, but the pathway for controlled ATP release from adipocytes is unknown. Here, we investigated whether Pannexin 1 (Panx1) channels control ATP release from adipocytes and contribute to metabolic homeostasis. Methods We assessed Panx1 functionality in cultured 3T3-L1 adipocytes and in adipocytes isolated from murine white adipose tissue by measuring ATP release in response to known activators of Panx1 channels. Glucose uptake in cultured 3T3-L1 adipocytes was measured in the presence of Panx1 pharmacologic inhibitors and in adipocytes isolated from white adipose tissue from wildtype (WT) or adipocyte-specific Panx1 knockout (AdipPanx1 KO) mice generated in our laboratory. We performed in vivo glucose uptake studies in chow fed WT and AdipPanx1 KO mice and assessed insulin resistance in WT and AdipPanx1 KO mice fed a high fat diet for 12 weeks. Panx1 channel function was assessed in response to insulin by performing electrophysiologic recordings in a heterologous expression system. Finally, we measured Panx1 mRNA in human visceral adipose tissue samples by qRT-PCR and compared expression levels with glucose levels and HOMA-IR measurements in patients. Results Our data show that adipocytes express functional Pannexin 1 (Panx1) channels that can be activated to release ATP. Pharmacologic inhibition or selective genetic deletion of Panx1 from adipocytes decreased insulin-induced glucose uptake in vitro and in vivo and exacerbated diet-induced insulin resistance in mice. Further, we identify insulin as a novel activator of Panx1 channels. In obese humans Panx1 expression in adipose tissue is increased and correlates with the degree of insulin resistance. Conclusions We show that Panx1 channel activity regulates insulin-stimulated glucose uptake in adipocytes and thus contributes to control of metabolic homeostasis.
Abstract
Disclosure: S.E. Adamson: None. A. Li: None. J. Hughes: None.
Somatostatin is an important modulator of beta cell function, but communication between beta and delta cells is not ...well-understood. Primary cilia are membrane organelles that act as signaling hubs due to their enrichment in certain G-protein coupled receptors and other signaling proteins. We show that somatostatin modulates insulin secretion via somatostatin receptor 3 (SSTR3) located on beta cell primary cilia in mouse islets. SSTR3 and the presence of primary cilia are required for normal beta cell response to somatostatin. Somatostatin signaling leads to beta cell calcium changes, which we characterize here using a beta cell specific genetically-encoded GCaMP6f calcium reporter. Our findings show that ciliary SSTR3 mediates delta to beta cell paracrine crosstalk.
Presentation: Friday, June 16, 2023
Introduction: SGLT2 inhibitors increase DKA risk, limiting their use in T1D. To understand the effect of SGLT2i on ketone production, we measured glucose, beta-hydroxybutyrate (BOHB) and breath ...acetone (BrACE) with and without dapagliflozin during supervised insulin withdrawal in adults with T1D. Methods: 20 adults with T1D underwent on-site supervised insulin withdrawal twice in a randomized crossover design: during usual care and after treatment with dapagliflozin (10 mg daily for 2 weeks plus the test day). After insulin withdrawal, capillary blood glucose, BOHB, and BrACE measurements were obtained at least hourly until stopping rules were met (glucose >400 mg/dL, BOHB >3 mmol/L, >8 hours elapsed, or participant request). Results: Mean (± SD) age was 48 ± 18 years, with baseline HbA1c 7.0 ± 0.9%. The maximal BOHB and BrACE values achieved during supervised insulin withdrawal were both greater with dapagliflozin than usual care (BOHB: 2.4 ± 1.2 vs. 1.6 ± 1.0 mmol/L, P <0.001; BrACE: 13.7 ± 7.5 vs. 8.7 ± 5.7, P = 0.004). Adjusted for time from insulin withdrawal, dapagliflozin treatment was associated with significantly greater BOHB and BrACE concentration (both P <0.001 by ANCOVA). The proportions of participants reaching BOHB >1.5 mmol/L and >2.5 mmol/L during supervised insulin withdrawal were greater in the dapagliflozin arm (74% vs. 37% with BOHB >1.5 mmol/L; 53% vs. 16% with BOHB >2.5 mmol/L; both P <0.05 by McNemar’s test). Blood glucose reached a lower maximum (218 ± 53 vs. 302 ± 58 mg/dL, P <0.001) in the dapagliflozin arm and did not significantly change during insulin withdrawal in the dapagliflozin arm (P for linear trend = 0.91). Conclusion: In adults with T1D undergoing up to 8 hours of supervised insulin withdrawal after dapagliflozin treatment, blood and breath ketone concentrations were significantly greater compared to usual care and in the absence of significant hyperglycemia. Disclosure M.C. Petersen: None. K.E. Jones: None. K.L. Bohnert: None. A.M. Markov: None. M. Salam: None. P. Krutilova: None. A.M. McKee: Advisory Panel; Medtronic, Novo Nordisk. Employee; Novo Nordisk. S.E. Adamson: None. J.B. McGill: Advisory Panel; Bayer Inc., Boehringer-Ingelheim, ClearNote Health, Lilly Diabetes, MannKind Corporation, Novo Nordisk. Research Support; Novo Nordisk. Funding JDRF (2-SRA-2022-1190-M-B)
Introduction: SGLT2 inhibitors slow CKD progression but none are approved in T1D due to risk of ketosis-related adverse events, including DKA. We evaluated the impact of dapagliflozin on glucose ...metrics, insulin requirements and BHOB. Methods: After informed consent, 20 participants with T1D completed two weeks of outpatient care while monitoring capillary BOHB, both with and without open label dapagliflozin (10 mg) in a randomized crossover design. Glycemic metrics were monitored via CGM, and insulin use was recorded from pump download or self-reports in MDI users. BOHB (Precision Xtra®, Abbott) measurements were obtained up to 3X daily during the study periods. Results: Participant age was 48 ± 18 years, 45% female, A1c 7.0 ± 0.9%, baseline TIR 61 ± 18% (mean ± SD). The baseline median insulin TDD was 57 (38 - 88). Sixteen patients used CSII and 4 MDI. SGTL2i use led to a 6.9% reduction in median TDD, 26.3% in basal doses. Participants averaged 36 cBHOB measurements in both usual care and SGLT-2 treatment phases. During usual care, there were 3 ketosis events (cBOHB > 1.5 mmol/L) versus 10 during SGLT-2 treatment (P=0.11). Most ketosis events occurred in one individual over a 24hr period. No DKA occurred. Conclusion: In adults with T1D, dapagliflozin use was associated with reduction in insulin doses and improvement in GMI. Ketosis events were concentrated in 1 participant. Disclosure A.M. Markov: None. K.E. Jones: None. M.C. Petersen: None. P. Krutilova: None. A.M. McKee: Advisory Panel; Medtronic, Novo Nordisk. Employee; Novo Nordisk. K.L. Bohnert: None. S.E. Adamson: None. M. Salam: None. J.B. McGill: Advisory Panel; Bayer Inc., Boehringer-Ingelheim, ClearNote Health, Lilly Diabetes, MannKind Corporation, Novo Nordisk. Research Support; Novo Nordisk.
Introduction: Prior work has shown a linear relationship between breath acetone (BrACE) and capillary blood beta hydroxybutyrate (BOHB) in persons without diabetes. This innovative study investigates ...the correlation between capillary BOHB and BrACE in T1D during usual care and while taking an SGLT2 inhibitor in both insulin-sufficient and -deficient states. The primary outcome of the study is the correlation of capillary BOHB and BrACE. Methods: Participants provided written consent and were randomized to 2 weeks of usual care and 1 day of insulin withdrawal followed by 2 weeks of usual care plus dapagliflozin, 10 mg daily and 1 day of insulin withdrawal or the opposite sequence. Paired BOHB (Precision Xtra®, Abbott) and BrACE (Biosense®, Readout) were obtained 3X daily for 2 weeks, then hourly during supervised insulin withdrawal. Sick day rules were reviewed and insulin doses were minimally adjusted when taking dapagliflozin. The data was tested for normality and the Spearman’s test was utilized due to non-normally distributed data. Results: Participant age was 48 ±18 years (mean ± SD), baseline A1c 7.0 ± 0.9%, and CGM time in range 70-180mg/dL 61 ± 18%. During outpatient care, BrACE and BOHB were weakly correlated both without dapagliflozin (n=689 paired readings; Spearman’s ρ = 0.44; 95% CI: 0.37 to 0.50) and with dapagliflozin (n=718 paired readings; ρ = 0.32; 95% CI: 0.25 to 0.39). However, BrACE and BOHB were strongly correlated during supervised insulin withdrawal (n=246 paired values, ρ = 0.81; 95% CI: 0.77 to 0.85). In ROC analysis, BrACE of ≥ 5 demonstrated optimal sensitivity (93%) and specificity (87%) for detecting a capillary BOHB > 1.5 mmol/L. No serious adverse events occurred. Conclusion: In adults with T1D, BrACE monitoring provides a noninvasive estimate of ambient ketone levels when compared to blood BOHB but is more useful under supervised conditions with greater range of ketone production and less potential for interference with volatile organic compounds than in typical outpatient settings. Disclosure K. Jones: None. M.C. Petersen: None. A.M. Markov: None. P. Krutilova: None. A.M. McKee: Advisory Panel; Medtronic, Novo Nordisk. Employee; Novo Nordisk. K.L. Bohnert: None. S.E. Adamson: None. M. Salam: None. J.B. McGill: Advisory Panel; Bayer Inc., Boehringer-Ingelheim, ClearNote Health, Lilly Diabetes, MannKind Corporation, Novo Nordisk. Research Support; Novo Nordisk. Funding JDRF DRCICTS
In a 13-week, randomized trial involving persons 6 to 79 years of age with type 1 diabetes, use of a bionic pancreas was associated with a greater reduction in the glycated hemoglobin level than ...standard care.
Abstract
Integrase strand transfer inhibitor (INSTI)-based antiretroviral therapy (ART) is first line for treatment of people with human immunodeficiency virus (PWH). Emerging data suggest the ...possibility of adverse metabolic effects of these medications. We describe 3 cases in which PWH developed hyperglycemia and ketoacidosis within months of being switched to bictegravir-based ART.
We provide increased awareness among clinicians of the potential for antiretroviral therapy-associated hyperglycemia with bictegravir-containing regimens.
Abstract only Our group has previously shown that oxidized phospholipids (OxPL) induce a unique macrophage (MΦ) phenotype known as “Mox,” distinct from pro- and anti-inflammatory M1 and M2 ...phenotypes. We have also shown that Mox make up 30% of the MΦs found in atherosclerotic lesions. OxPL induce TLR2-dependent inflammatory gene expression in MΦs. TLR2 activation by peptidoglycan was shown to induce accumulation of ceramides, which can alter bioenergetics by inhibiting the mitochondria. Recently, it has been shown that spleen tyrosine kinase (Syk) is phosphorylated upon TLR2 agonist Pam3CSK stimulation in MΦs. The effect of OxPL on bioenergetics has never before been studied. Here we test the hypothesis that OxPL change MΦ bioenergetics and inflammatory capacity via a TLR2-Syk-Ceramide pathway. Using flow cytometry, we found that in mice fed a high-fat diet, more than 20% of all adipose tissue MΦs can be described as Mox. Concomitantly, using immunohistochemistry and liquid-chromatography mass spectrometry, we measured increased levels of OxPL in the stromal vascular fraction of obese murine adipose tissue, as compared to lean controls. We treated bone marrow-derived MΦs (BMDMs) from WT, TLR2-KO, and Syk-KO mice with OxPL and measured bioenergetics using a Seahorse Flux Analyzer. Our results show that OxPL decrease oxygen consumption rate (OCR), a measure of oxidative phosphorylation, and decrease extracellular acidification rate (ECAR), a measure of glycolytic capacity. These MΦs can be described as quiescent, but they still engage in low-level cytokine production. Moreover, OxPL result in the accumulation of ceramides, as quantified by mass spectrometry. Finally, using Syk-KO MΦs and Syk inhibitors, we show that OxPL-induced inflammatory gene expression and ceramide accumulation are dependent on Syk. In summary, our results demonstrate that OxPL accumulate in obese adipose tissue and induce a change in the inflammatory and metabolic profiles of MΦs, involving a TLR2-ceramide-Syk dependent pathway. These results suggest that OxPL are triggers of adipose tissue inflammation and subsequent development of insulin resistance. Furthermore, we identify Syk as a therapeutic target for inhibiting diet-induced adipose tissue inflammation and insulin resistance.
Background: Adrenocortical carcinoma is a rare, often aggressive tumor that is more common in women than men. The tumors are more often than not biochemically active in adults, and the majority ...secrete glucocorticoids alone (1,2).Clinical case: A 57yo woman w/ longstanding hypertension and history of total abdominal hysterectomy presented with shortness of breath. She reported worsening of her hypertension over the past six months associated with male pattern balding, body hair growth, anxiety, facial and abdominal swelling for the past four months. Computed tomography PE protocol showed bilateral pulmonary emboli and multiple pulmonary nodules. Subsequent computed tomography chest/abdomen/pelvis revealed pulmonary nodules in both lungs, the largest being 3.7cm x 2.5cm in the right upper lobe, and a large right retroperitoneal mass centered at the expected position of the right adrenal gland measures 12.4cm x 10.5cm causing mass effect on the inferior surface of the liver along with bulky mediastinal, hilar, paratracheal, gastrohepatic, portocaval, and retroperitoneal lymphadenopathy. Exam was significant for cushingoid habitus with central obesity, rounded facies, supraclavicular and dorsocervical fat pads, proximal muscle weakness, frontotemporal balding, severe hirsutism consistent with modified ferriman-gallwey score of 13, and an annular, scaly rash along gluteal cleft. 8am serum cortisol was 65mcg/dL. 24 hour urinary cortisol was 450mcg/24 hour. ACTH was undetectable <2.0pg/mL. Total Testosterone was 835ng/dL. DHEAS was 1,000mcg/dL. Renin, aldosterone, plasma fractionated metanephrines were normal. Excisional supraclavicular lymph node biopsy was positive for metastatic adrenocortical carcinoma. Subsequent FDG PET/CT also showed metastatic disease in the liver, right humeral head, sacrum, and bilateral iliac bones. Punch biopsy of the rash was consistent with tinea cruris. The patient was moved to the oncology service and started on therapy with mitotane, cisplatin, doxorubicin and etoposide.Conclusion: Rapid virilization is concerning for an underlying malignancy and should always include androgen evaluation with a high index of suspicion for ovarian or adrenal tumors.References:1. Wajchenberg BL, Albergaria Pereira MA, Medonca BB, et. Al. Adrenocortical carcinoma: clinical and laboratory observations. Cancer. 2000;88(4):711.2. Ng L, Libertino JM. Adrenocortical carcinoma: diagnosis, evaluation and treatment. J Urol. 2003;169(1):5.
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