Metabolic changes in diabetes

Role of the integrin-linked kinase/TGF-β/SMAD pathway in sitagliptin-mediated cardioprotective effects in a rat model of diabetic cardiomyopathy

OBJECTIVES

Diabetic cardiomyopathy is a known complication of diabetes mellitus. Herein, we aimed to determine whether glycemic control mediated by sitagliptin, a dipeptidyl peptidase-4 inhibitor, can ameliorate diabetic myocardial abnormalities by modulating TGF-β signaling via the SMAD and integrin-linked kinase (ILK) pathways.

METHODS

Four groups of male Wistar albino rats were used, with six rats in each group. Two nondiabetic and two diabetic (produced by a single intraperitoneal dose of streptozotocin (55 mg/kg)) groups were administered either normal saline or sitagliptin (100 mg/kg) orally for 6 weeks. Subsequently, HW/BW ratios and cardiac enzymes were assessed, along with a histological examination of cardiac tissues. Levels of TGF-β, collagen I, p-SMAD2/3, TNF-α, MMP-9, and ILK were detected.

RESULTS

Compared with the diabetic control group, sitagliptin-treated diabetic rats exhibited considerably reduced HW/BW ratios and troponin I and creatine kinase-MB levels, with improvements in histopathological changes in cardiac tissues. TGF-β, collagen I, p-SMAD2/3, TNF-α, and MMP-9 levels were significantly decreased in the sitagliptin-treated diabetic group, whereas ILK was elevated following sitagliptin treatment.

CONCLUSION

Sitagliptin could afford cardioprotective effects for the first time by altering ILK-associated TGF-β/SMAD signaling pathways. Thus, sitagliptin may be a promising therapeutic target for the prevention of diabetic cardiomyopathy.

From Bench to Bedside in Precision Medicine: Diabetes Mellitus and Peri-Implantitis Clinical Indices with a Short-Term Follow-Up: A Systematic Review and Meta-Analysis

Background and objective: Diabetes mellitus (DM) refers to a group of metabolic disorders characterized by hyperglycemia resulting from impaired secretion or action of insulin. The high levels of glucose in the blood can negatively affect the healing processes through alterations in vascularization, bone remodeling, and with increased susceptibility to infections. Diabetes mellitus is therefore a risk factor not only for many systemic diseases, but also for localized problems such as peri-implantitis. The objective of this systematic review was to identify a clear relationship between peri-implant inflammation indices and glycemic levels, through the investigation of prospective studies that report data on a short-term follow-up period. Our hypothesis was that peri-implant inflammatory indices may already present themselves in a statistically significant way as altered in patients with DM compared to patients without DM. Materials and methods: This review was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA). Results: More than 992 records were identified in the PubMed, Scopus, and Cochrane Central Register of Controlled Trial electronic databases and only seven studies were included in the meta-analysis. The results of the meta-analysis report worse outcomes in patients with DM, even in the short period of six months, for peri-implatitis inflammation indices, such as Marginal bone loss (standardized (Std). mean difference (MD) 12\6 months 0.81 [0.45, 1.17]\1.82 [0.53, 3.10]), Bleeding on probing (Std. MD 12\6 months 2.84 [1.34, 4.34]\3.44 [1.41, 5.50]), Probing depth (Std. MD 12\6 months 1.14 [0.60, 1.68]\2.24 [0.66, 3.83]), and the plaque index (Std. MD 12 months 2.83 [0.09, 5.57]). Conclusion: The literature linking glycaemic control to peri-implant disease is highly heterogeneous due to lack of consistency of the definition of peri-implantitis and its clinical indicators among studies. Therefore, interpretation of finding and relevance to clinical practice should be considered on individual bases. In the era of personalized medicine, the clinician should utilize individualized information from translational researches and analyze all risk factors to provide the patient with evidence-based treatment options.

C-Peptide as a Therapy for Type 1 Diabetes Mellitus

Diabetes mellitus (DM) is a complex metabolic disease affecting one-third of the United States population. It is characterized by hyperglycemia, where the hormone insulin is either not produced sufficiently or where there is a resistance to insulin. Patients with Type 1 DM (T1DM), in which the insulin-producing beta cells are destroyed by autoimmune mechanisms, have a significantly increased risk of developing life-threatening cardiovascular complications, even when exogenous insulin is administered. In fact, due to various factors such as limited blood glucose measurements and timing of insulin administration, only 37% of T1DM adults achieve normoglycemia. Furthermore, T1DM patients do not produce C-peptide, a cleavage product from insulin processing. C-peptide has potential therapeutic effects in vitro and in vivo on many complications of T1DM, such as peripheral neuropathy, atherosclerosis, and inflammation. Thus, delivery of C-peptide in conjunction with insulin through a pump, pancreatic islet transplantation, or genetically engineered Sertoli cells (an immune privileged cell type) may ameliorate many of the cardiovascular and vascular complications afflicting T1DM patients.

A genome-wide search for type 2 diabetes susceptibility genes in an extended Arab family

Twenty percent of people aged 20 to 79 have type 2 diabetes (T2D) in the United Arab Emirates (UAE). Genome-wide association studies (GWAS) to identify genes for T2D have not been reported for Arab countries. We performed a discovery GWAS in an extended UAE family (N=178; 66 diabetic; 112 healthy) genotyped on the Illumina Human 660 Quad Beadchip, with independent replication of top hits in 116 cases and 199 controls. Power to achieve genome-wide significance (commonly P=5×10(-8)) was therefore limited. Nevertheless, transmission disequilibrium testing in FBAT identified top hits at Chromosome 4p12-p13 (KCTD8: rs4407541, P=9.70×10(-6); GABRB1: rs10517178/rs1372491, P=4.19×10(-6)) and 14q13 (PRKD1: rs10144903, 3.92×10(-6)), supported by analysis using a linear mixed model approximation in GenABEL (4p12-p13 GABRG1/GABRA2: rs7662743, Padj-agesex=2.06×10(-5); KCTD8: rs4407541, Padj-agesex=1.42×10(-4); GABRB1: rs10517178/rs1372491, Padj-agesex=0.027; 14q13 PRKD1: rs10144903, Padj-agesex=6.95×10(-5)). SNPs across GABRG1/GABRA2 did not replicate, whereas more proximal SNPs rs7679715 (Padj-agesex=0.030) and rs2055942 (Padj-agesex=0.022) at COX7B2/GABRA4 did, in addition to a trend distally at KCTD8 (rs4695718: Padj-agesex=0.096). Modelling of discovery and replication data support independent signals at GABRA4 (rs2055942: Padj-agesex-combined=3×10(-4)) and at KCTD8 (rs4695718: Padj-agesex-combined=2×10(-4)). Replication was observed for PRKD1 rs1953722 (proxy for rs10144903; Padj-agesex=0.031; Padj-agesex-combined=2×10(-4)). These genes may provide important functional leads in understanding disease pathogenesis in this population.

Spectral and directional reflectance of the fovea in diabetes mellitus: photoreceptor integrity, macular pigment and lens

Our aim was to assess the integrity of the photoreceptors in the fovea, and to measure the optical density of the macular pigment and the eye lens in patients with diabetes mellitus, and to compare the results with those of a group of healthy subjects. The directional and spectral properties of the light reflected from a 1.9 deg field centered on the fovea were measured simultaneously, in a single one second flash, with the Foveal Reflection Analyzer. The directional characteristics, i.e., the optical Stiles-Crawford effect, provided information on the integrity of the foveal photoreceptors. Model analysis of the spectral reflectance yielded optical densities of the macular pigment and the lens. The amplitude of the directional reflectance in diabetic eyes was significantly lower compared to controls (P<0.001). This indicates that the integrity of the photoreceptors in the fovea was altered in diabetics. Surprisingly, the directionality (a measure for the peakedness) was similar in diabetics and controls (P=0.3). The density of macular pigment was not different from that in controls (P=0.3). The optical density of the lens increased with age in both groups, but the rate of increase was larger in the diabetics (P<0.05). Possibly, the lens optical density increasing at a higher rate with age reflects changes preceding cataract formation.