Review article: The role of adipose tissue in uraemia-related insulin resistance

Type 2 diabetes - An autoinflammatory disease driven by metabolic stress

Type 2 diabetes has traditionally been viewed as a metabolic disorder characterised by chronic high glucose levels, insulin resistance, and declining insulin secretion from the pancreas. Modern lifestyle, with abundant nutrient supply and reduced physical activity, has resulted in dramatic increases in the rates of obesity-associated disease conditions, including diabetes. The associated excess of nutrients induces a state of systemic low-grade chronic inflammation that results from production and secretion of inflammatory mediators from the expanded pool of activated adipocytes. Here, we review the mechanisms by which obesity induces adipose tissue dysregulation, detailing the roles of adipose tissue secreted factors and their action upon other cells and tissues central to glucose homeostasis and type 2 diabetes. Furthermore, given the emerging importance of adipokines, cytokines and chemokines in disease progression, we suggest that type 2 diabetes should now be viewed as an autoinflammatory disease, albeit one that is driven by metabolic dysregulation.

Adipocytokines and breast cancer

A substantial number of studies have revealed that a growing list of cancers might be influenced by obesity. In this regard, one of the most prominent and well-characterized cancers is breast cancer, the leading cause of cancer death among women. Obesity is associated with an increased risk for the occurrence and development of breast cancer particular in postmenopausal women. Moreover, the relationship between adiposity and breast cancer risk is complex, with associations that differ depending on when body size is assessed (eg, premenopausal vs postmenopausal obesity) and when breast cancer is diagnosed (ie, premenopausal vs postmenopausal disease). Obesity is mainly due to excessive fat accumulation in the regional tissue. Adipocytes in obese individuals produce endocrine, inflammatory, and angiogenic factors to affect adjacent breast cancer cells. Adipocytokines, are biologically active polypeptides that are produced either exclusively or substantially by adipocytes, play a critical and complex role, and act by endocrine, paracrine, and autocrine pathways in the malignant progression of breast cancer. Furthermore, the increased levels of leptin, resistin, and decreased adiponectin secretion are directly associated with breast cancer development. And there are also many studies indicating that adipocytokines could mediate the survival, growth, invasion, and metastasis of breast cancer cells by different cellular and molecular mechanisms to reduce the survival time and prompt the malignancy. In present review, we discuss the correlations between several adipocytokines and breast cancer cells in obesity as well as the underlying signaling pathways to provide the novel ideas for the prevention and treatment of breast cancer.

Adipose tissue DNA methylome changes in development of new-onset diabetes after kidney transplantation

AIM

New-onset diabetes after kidney transplant (NODAT) adversely impacts kidney allograft and patient survival. Epigenetic alterations in adipose tissue like DNA methylation may play a contributory role.

METHODS

Adipose tissue DNA of the patients with NODAT and their age, sex and BMI matched controls (nine each) were sequenced by reduced representation bisulfite sequencing. Differentially methylated CpGs (DMCs) and differentially methylated regions (DMRs) were studied.

RESULTS

Adipose tissue from the patients had reduced DNA methylation in intergenic and intronic regions. DMCs were found to be more hypomethylated in repeat regions and hypermethylated in CGIs and promoter region. About 900 DMRs were found and their associated genes were significantly enriched in 32 pathways, the top ones of which were associated with insulin resistance and inflammation. Some DMR or DMC genes have known T2DM associations.

CONCLUSION

Changes in DNA methylation in adipose tissue may be suggestive of future NODAT.

Resistin reinforces interferon λ-3 to eliminate hepatitis C virus with fine-tuning from RETN single-nucleotide polymorphisms

The effect of resistin (RETN) on the response to anti-HCV therapy remains unclear. A prospective cohort study was performed using 655 consecutive HCV patients, of whom 513 had completed a course of interferon-based therapy. Multivariate and GEE analyses revealed four RETN single-nucleotide polymorphisms (SNPs), rs34861192, rs3219175, rs3745367 and rs1423096, to be synergistically associated with resistin levels. After adjusting for co-factors such as interferon λ-3 (IFNL3)-rs12979860, the resistin level and the hyper-resistinemic genotype at the 4 RETN SNPs were positively and negatively associated with a sustained virological response (SVR), respectively. RETN-rs3745367 was in linkage disequilibrium with IFNL3-rs12979860. Compared to non-SVR patients, SVR patients had higher levels of pre-therapy resistin, primarily originating from intrahepatic lymphocytes, stellate cells, Kupffer cells, hepatic progenitor cells and hepatocytes. This difference diminished over the course of therapy, as only SVR patients exhibited a 24-week post-therapy decrease in resistin. Both resistin and IFNL3 mRNAs were upregulated, but only resistin mRNA was upregulated by recombinant resistin in peripheral blood mononuclear cells with and without hyper-resistinemic genotypes of the 4 RETN SNPs, respectively. Fine-tuned by RETN SNPs, intrahepatic, multi-cellular resistin reinforced IFNL3 in eliminating HCV via immunomodulation to counteract pro-inflammation. These results encourage the development of novel resistin-targeted anti-viral agents.

Management of glycemia in diabetic patients with stage IV and V chronic kidney disease

Diabetic kidney disease is a leading cause of end-stage kidney disease worldwide. Data suggest that prevention of progression to end-stage may lie in excellent blood glucose control; however, as kidney disease progresses, the risk of hypoglycemia increases, due to unpredictable insulin kinetics and altered pharmacokinetics of hypoglycemic agents. In addition, whole classes of hypoglycemic agents become contraindicated and regimens must be adjusted for declining kidney function. There is no consensus regarding the best therapy for the patient with advanced chronic kidney disease. In the best of circumstances, the care of these patients will involve intensive monitoring, with the input of a team of health care providers creating a coordinated care plan, including dietary advice and a drug regimen tailored to the specific issues faced by the individual patient. An open dialogue is necessary at all times, as patients may become frustrated and attempt self-treatment using over the counter alternatives.

Effect of biochanin a on serum visfatin level of streptozocin-induced diabetic rats

Background:

Bioflavonoids are well known for their multi directional biologic activity including antidiabetic effect. It has been demonstrated that flavonoids can act as insulin secretagogue or insulin mimetic agents.

Objectives:

This experimental study was designed in Arak University of Medical Sciences, Arak, Iran, to investigate the effects of biochanin A (a bioflavonoid) on fasting blood glucose (FBG), body weight, glycosylated hemoglobin (HbA₁c), lipid profile, serum enzymes, and visfatin of streptozocin-induced diabetic rats.

Patients and Methods:

We used 24 male Wistar rats and randomly allocated them to four groups of six rats. One group was randomly assigned as control and diabetes was induced in three other groups by administration of streptozocin (35 mg/kg of body weight) intraperitoneally. The groups received the following treatments: group 1 (control), 5% DMSO; group 2 (diabetic control), 0.5% DMSO; and group 3 and 4, respectively 10 and 15 mg/kg biochanin A for 30 days. Body weight and biochemical parameters including FBG, HbA₁c, lipid profile, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and visfatin were measured in all rats.

Results:

FBG level was significantly reduced in treated diabetic rats (139.8 ± 9.3 and 206 ± 11 mg/dL in groups 3 and 4, respectively) in comparison to the diabetic control (295.1 ± 14 mg/dL) (P < 0.05). Administration of biochanin A significantly decreased HbA₁c in group 3 (6.66 ± 0.33) and group 4 (7.11 ± 0.31) in comparison to the diabetic control group (8.26 ± 0.44) (P < 0.05). Levels of serum visfatin were improved to near normal levels in the treated rats (249 ± 35.5 and 161.33 ± 13.07 in groups 3 and 4, respectively) in comparison to the diabetic control (302.17 ± 19.4) (P < 0.05). Furthermore, biochanin A showed a protective effect against weight loss in diabetic rats (P < 0.05). In treated rats, serum total cholesterol, triglyceride, and low-density lipoprotein cholesterol (LDL-c) were significantly decreased and high-density lipoprotein (HDL-c) was increased in comparison with the diabetic control group. In addition, biochanin A restored the altered plasma enzymes (AST, ALT, and ALP) activities to near normal. Histopathologic examination of the pancreas also indicated that biochanin A had protective effects on β-cells in streptozocin-induced diabetic rats.

Conclusions:

This study demonstrated that biochanin A possessed hypoglycemic and antilipemic activities and could increase visfatin expression, which suggests its beneficial effect in the treatment of diabetes.

Biochemistry of adipose tissue: an endocrine organ

Adipose tissue is no longer considered to be an inert tissue that stores fat. This tissue is capable of expanding to accommodate increased lipids through hypertrophy of existing adipocytes and by initiating differentiation of pre-adipocytes. Adipose tissue metabolism exerts an impact on whole-body metabolism. As an endocrine organ, adipose tissue is responsible for the synthesis and secretion of several hormones. These are active in a range of processes, such as control of nutritional intake (leptin, angiotensin), control of sensitivity to insulin and inflammatory process mediators (tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), resistin, visfatin, adiponectin, among others) and pathways (plasminogen activator inhibitor 1 (PAI-1) and acylation stimulating protein (ASP) for example). This paper reviews some of the biochemical and metabolic aspects of adipose tissue and its relationship to inflammatory disease and insulin resistance.

Diabetes management in the kidney patient

Hyperglycemia management in chronic kidney disease (CKD) patients presents difficult challenges, partly due to the complexity involved in treating these patients, and partly due to lack of data supporting benefits of tight glycemic control. While hyperglycemia is central to the pathogenesis and management of diabetes, hypoglycemia and glucose variability also contribute to outcomes. Multiple agents with different mechanisms of action are now available; some can lower glucose levels without the risk of hypoglycemia. This article reviews metabolic changes present in kidney impairment/failure, current views about glycemic goals, and treatment options for the diabetic patient with CKD.

Growth hormone in chronic renal disease

Severe growth retardation (below the third percentile for height) is seen in up to one-third children with chronic kidney disease. It is thought to be multifactorial and despite optimal medical therapy most children are unable to reach their normal height. Under-nutrition, anemia, vitamin D deficiency with secondary hyperparathyroidism, metabolic acidosis, hyperphosphatemia, renal osteodystrophy; abnormalities in the growth hormone/insulin like growth factor system and sex steroids, all have been implicated in the pathogenesis of growth failure. Therapy includes optimization of nutritional and metabolic abnormalities. Failure to achieve adequate height despite 3-6 months of optimal medical measures mandates the use of recombinant GH (rGH) therapy, which has shown to result in catch-up growth, anywhere from 2 cm to 10 cm with satisfactory liner, somatic and psychological development.