Prasad G. Kamble

Lipocalin 2 produces insulin resistance and can be upregulated by glucocorticoids in human adipose tissue

The adipokine lipocalin 2 is linked to obesity and metabolic disorders. However, its role in human adipose tissue glucose and lipid metabolism is not explored. Here we show that the synthetic glucocorticoid dexamethasone dose-dependently increased lipocalin 2 gene expression in subcutaneous and omental adipose tissue from pre-menopausal females, while it had no effect in post-menopausal females or in males. Subcutaneous adipose tissue from both genders treated with recombinant human lipocalin 2 showed a reduction in protein levels of GLUT1 and GLUT4 and in glucose uptake in isolated adipocytes. In subcutaneous adipose tissue, lipocalin 2 increased IL-6 gene expression whereas expression of PPARγ and adiponectin was reduced. Our findings suggest that lipocalin 2 can contribute to insulin resistance in human adipose tissue. In pre-menopausal females, it may partly mediate adverse metabolic effects exerted by glucocorticoid excess.

Role of cannabinoid receptor 1 in human adipose tissue for lipolysis regulation and insulin resistance

We recently showed that the peripheral cannabinoid receptor type 1 (CNR1) gene is upregulated by the synthetic glucocorticoid dexamethasone. CNR1 is highly expressed in the central nervous system and has been a drug target for the treatment of obesity. Here we explore the role of peripheral CNR1 in states of insulin resistance in human adipose tissue. Subcutaneous adipose tissue was obtained from well-controlled type 2 diabetes subjects and controls. Subcutaneous adipose tissue gene expression levels of CNR1 and endocannabinoid synthesizing and degrading enzymes were assessed. Furthermore, paired human subcutaneous adipose tissue and omental adipose tissue from non-diabetic volunteers undergoing kidney donation or bariatric surgery, was incubated with or without dexamethasone. Subcutaneous adipose tissue obtained from volunteers through needle biopsy was incubated with or without dexamethasone and in the presence or absence of the CNR1-specific antagonist AM281. CNR1 gene and protein expression, lipolysis and glucose uptake were evaluated. Subcutaneous adipose tissue CNR1 gene expression levels were 2-fold elevated in type 2 diabetes subjects compared with control subjects. Additionally, gene expression levels of CNR1 and endocannabinoid-regulating enzymes from both groups correlated with markers of insulin resistance. Dexamethasone increased CNR1 expression dose-dependently in subcutaneous adipose tissue and omental adipose tissue by up to 25-fold. Dexamethasone pre-treatment of subcutaneous adipose tissue increased lipolysis rate and reduced glucose uptake. Co-incubation with the CNR1 antagonist AM281 prevented the stimulatory effect on lipolysis, but had no effect on glucose uptake. CNR1 is upregulated in states of type 2 diabetes and insulin resistance. Furthermore, CNR1 is involved in glucocorticoid-regulated lipolysis. Peripheral CNR1 could be an interesting drug target in type 2 diabetes and dyslipidemia.

Glucagon Levels during Short-term SGLT2 Inhibition are Largely Regulated by Glucose Changes in Type 2 Diabetes Patients.

Context The mechanism mediating sodium glucose cotransporter-2 (SGLT2) inhibitor-associated increase in glucagon levels is unknown. Objective To assess short-term effects on glucagon, other hormones, and energy substrates after SGLT2 inhibition and whether such effects are secondary to glucose lowering. The impact of adding a dipeptidyl peptidase-4 inhibitor was addressed. Design, Setting, and Patients A phase 4, single-center, randomized, three-treatment crossover, open-label study including 15 patients with type 2 diabetes treated with metformin. Interventions Patients received a single-dose of dapagliflozin 10 mg accompanied by the following in randomized order: isoglycemic clamp (experiment DG); saline infusion (experiment D); or saxagliptin 5 mg plus saline infusion (experiment DS). Directly after 5-hour infusions, a 2-hour oral glucose tolerance test (OGTT) was performed. Results Glucose and insulin levels were stable in experiment DG and decreased in experiment D [P for difference (Pdiff) < 0.001]. Glucagon-to-insulin ratio (Pdiff < 0.001), and levels of glucagon (Pdiff < 0.01), nonesterified fatty acids (Pdiff < 0.01), glycerol (Pdiff < 0.01), and β-OH-butyrate (Pdiff < 0.05) were lower in DG vs D. In multivariate analysis, change in glucose level was the main predictor of change in glucagon level. In DS, glucagon and active GLP-1 levels were higher than in D, but glucose and insulin levels did not differ. During OGTT, glucose levels rose less and glucagon levels fell more in DS vs D. Conclusion The degree of glucose lowering markedly contributed to regulation of glucagon and insulin secretion and to lipid mobilization during short-term SGLT2 inhibition.

Early Changes in Glucose Homeostasis after Gastric Bypass Surgery in Patients with T2DM—Role of Adipose Tissue Mechanisms?

Gastric bypass (GBP) surgery can effectively prevent or treat type 2 diabetes (T2D). Adipose tissue (AT) mechanisms may be important, but causality is not shown. We studied the relationship between early changes in whole-body and AT metabolism in obese T2D patients. Methods: Eight T2D patients with BMI 30-45 (M/F 3/5, age 49 ± 10) underwent GBP following 4 week low calorie diet. Assessments: OGTT, AT biopsies to measure gene expression in AT and in adipocytes size, glucose uptake (GU), lipolysis and insulin action. Results: At 4 and 24 weeks post-GBP, all subjects but one stopped diabetes medication. The Matsuda index increased compared to baseline, while HOMA-IR, fasting glucose, HbA1c and insulin levels decreased (p Conclusion: Glycemic control and insulin sensitivity clearly improved 4 weeks after GBP, but adipocyte insulin sensitivity in vitro did not improve despite a reduction in adipocyte size. Thus the mechanisms for rapid improvement of T2D after GBP may occur mainly in other tissues than adipose. Disclosure P. Katsogiannos: None. G.J. Boersma: None. P.G. Kamble: None. M.J. Pereira: None. P. Lundkvist: None. A. Karlsson: None. M. Sundbom: None. J.W. Eriksson: Employee; Spouse/Partner; Amgen Inc.. Consultant; Self; AstraZeneca. Research Support; Self; AstraZeneca. Consultant; Self; Novo Nordisk A/S, Merck Sharp & Dohme Corp.. Research Support; Self; Bristol-Myers Squibb Company.

Role of peroxisome proliferator-activated receptor gamma Pro12Ala polymorphism in human adipose tissue: assessment of adipogenesis and adipocyte glucose and lipid turnover

ABSTRACT The protective mechanisms of peroxisome proliferator-activated receptor gamma (PPARγ) Pro12Ala polymorphism in type 2 diabetes (T2D) are unclear. We obtained subcutaneous adipose tissue (AT) before and 3 h after oral glucose (OGTT) in carriers and non-carriers of the Ala allele (12 Pro/Pro, 15 Pro/Ala, and 13 Ala/Ala). Adipogenesis, adipocyte glucose uptake and lipolysis as well as PPARγ target gene expression were investigated and compared between the genotype groups. During fasting and post-OGTT, neither basal nor insulin-stimulated adipocyte glucose uptake differed between genotypes. Compared to fasting, a decreased hormone-sensitive lipase gene expression in Pro/Pro (p < 0.05) was accompanied with a higher antilipolytic effect of insulin post-OGTT (p < 0.01). The adipocyte size was similar across groups. Preadipocyte differentiation rates between Pro/Pro and Ala/Ala were unchanged. In conclusion, no major differences in AT differentiation, glucose uptake, lipolysis or expression of PPARγ target genes were observed between different PPARγ Pro12Ala genotypes. Albeit small, our study may suggest that other pathways in AT or effects exerted in other tissues might contribute to the Pro12Ala-mediated protection against T2D.

Genotype-based recall to study metabolic effects of genetic variation : a pilot study of PPARG Pro12Ala carriers

Abstract Aim: To assess practical implications of genotype-based recall (GBR) studies, an increasingly popular approach for in-depth characterization of genotype–phenotype relationships. Methods: We genotyped 2500 participants from the Swedish EpiHealth cohort and considered loss-of-function and missense variants in genes with relation to cardiometabolic traits as the basis for our GBR study. Therefore, we focused on carriers and non-carriers of the PPARG Pro12Ala (rs1801282) variant, as it is a relatively common variant with a minor allele frequency (MAF) of 0.14. It has also been shown to affect ligand binding and transcription, and carriage of the minor allele (Ala12) is associated with a reduced risk of type 2 diabetes. We re-invited 39 Pro12Pro, 34 Pro12Ala, and 30 Ala12Ala carriers and performed detailed anthropometric and serological assessments. Results: The participation rates in the GBR study were 31%, 44%, and 40%, and accordingly we included 12, 15, and 13 individuals with Pro12Pro, Pro12Ala, and Ala12Ala variants, respectively. There were no differences in anthropometric or metabolic variables among the different genotype groups. Conclusions: Our report highlights that from a practical perspective, GBR can be used to study genotype–phenotype relationships. This approach can prove to be a valuable tool for follow-up findings from large-scale genetic discovery studies by undertaking detailed phenotyping procedures that might not be feasible in large studies. However, our study also illustrates the need for a larger pool of genotyped or sequenced individuals to allow for selection of rare variants with larger effects that can be examined in a GBR study of the present size.