Correlation of serum resistin level with insulin resistance and severity of retinopathy in type 2 diabetes mellitus

Shedding light on eye disease in obesity: A review

Obesity is known to be associated with numerous ocular manifestations, including but not limited to, diabetic retinopathy (DR), age-related macular degeneration (AMD), cataracts, glaucoma, and dry eye disease. This review aims to provide an overview of the ophthalmological findings in obesity. A literature search was conducted using PubMed and Cochrane databases for studies describing randomized clinical trials, meta-analyses, systematic reviews, and observational studies published from 1 January 2017 to 1 April 2023. The search terms used included relevant keywords such as 'obesity', 'body mass index', 'waist-to-hip ratio', 'bariatric', 'ophthalmology', 'eye disease', 'myopia', 'retinopathy', 'glaucoma', and 'cataract'. This literature search was performed on 1 April 2023. Obesity is associated with increased risk of developing DR, a sight-threatening complication of diabetes mellitus. Similarly, obesity has been shown to increase risk of AMD, cataracts, glaucoma, and ocular surface disease. Multiple mechanisms linking obesity to ophthalmic disease have been proposed. Adipose tissue produces various inflammatory cytokines that can affect ocular tissues, leading to disease progression. Additionally, obesity is associated with systemic metabolic changes that can influence ocular health. Bariatric surgery has been shown to be protective against development of ophthalmic disease. Obesity is a significant risk factor for several ophthalmological diseases. Healthcare providers should encourage weight loss in patients with overweight or obesity to prevent or delay the onset of ocular complications. Further research is needed to better understand the underlying mechanisms of this association, and to identify effective strategies for preventing or managing ophthalmic disease in patients with obesity.

The correlation between serum resistin and toll-like receptor-4 with insulin resistance in hypertensive subjects with or without type 2 diabetes mellitus

Background: The most chronic disease prevalence in the Iraqi population are type-2 diabetes mellitus (T2DM) and hypertension (HT). One of the important causes of these chronic diseases is obesity. Resistin (RETN) is a major link between obesity and insulin resistance (IR) or T2DM (which induces IR). The action of RETN on IR is mediated by Toll-like receptor-4 (TLR4). TLR4 is a putative RETN receptor that has been suggested to participate in RETN-inducing inflammation and IR. Objectives: To study the association between serum RETN/TLR4 and IR in hypertensive patients with or without T2DM subjects. Methods: This cross-sectional study was conducted on 120 men that classified into four different groups. These groups consist of the following: 30 apparently control group, 30 patients with hypertension, 30 patients with T2DM but without HT and 30 hypertensive patients with T2DM. For all the subjects, serum RETN, TLR4 and serum insulin was estimated by using the ELISA technique. Results: Our results showed that mean levels of the serum RETN and TLR4 were significantly elevated in all patient groups when compared with the control group. Also, a positive correlation between serum RETN and TLR4 was found in hypertensive patients with T2DM patients. Conclusions: Serum RETN and TLR4 were higher in all patient groups when compared with the control group. In addition, a positive correlation between RETN and IR in all study groups was noted. Then, we suggested a close association between RETN and TLR4 and their positive correlations with IR.

Discordant Dose-Dependent Metabolic Effects of Eicosapentanoic Acid in Diet-Induced Obese Mice

Obesity is a widespread epidemic that increases the risk for several metabolic diseases. Despite several beneficial health effects of eicosapentaenoic acid (C20:5n-3, EPA), previous studies have used very high doses of EPA. In this study, dose-dependent effects of EPA on metabolic outcomes were determined in diet-induced obese mice. We used B6 male mice, fed high-fat diet (HF, 45% kcal fat) or HF diet supplemented with 9, 18, and 36 g/kg of EPA-enriched fish oil for 14 weeks. We conducted metabolic phenotyping during the feeding period, and harvested tissues and blood at termination. Only mice fed 36 g/kg of EPA significantly (p < 0.05) lowered body weight, fat content and epididymal fat pad weight, compared to HF. Both 18 and 36 g/kg doses of EPA significantly increased glucose clearance and insulin sensitivity, compared to HF or 9 g/kg of EPA. Locomotor activity was significantly increased with both 18 and 36 g/kg doses of EPA. Interestingly, all doses of EPA compared to HF, significantly increased energy expenditure and oxygen consumption and significantly reduced serum insulin, leptin, and triglycerides levels. These results demonstrate weight- and adiposity-independent metabolic benefits of EPA, at doses comparable to those currently used to treat hypertriglyceridemia.

Remodeling adipose tissue inflammasome for type 2 diabetes mellitus treatment: Current perspective and translational strategies

Obesity-associated type 2 diabetes mellitus (T2DM) is characterized by low-grade chronic systemic inflammation that arises primarily from the white adipose tissue. The interplay between various adipose tissue-derived chemokines drives insulin resistance in T2DM and has therefore become a subject of rigorous investigation. The adipocytokines strongly associated with glucose homeostasis include tumor necrosis factor-α, various interleukins, monocyte chemoattractant protein-1, adiponectin, and leptin, among others. Remodeling the adipose tissue inflammasome in obesity-associated T2DM is likely to treat the underlying cause of the disease and bring significant therapeutic benefit. Various strategies have been adopted or are being investigated to modulate the serum/tissue levels of pro- and anti-inflammatory adipocytokines to improve glucose homeostasis in T2DM. These include use of small molecule agonists/inhibitors, mimetics, antibodies, gene therapy, and other novel formulations. Here, we discuss adipocytokines that are strongly associated with insulin activity and therapies that are under investigation for modulation of their levels in the treatment of T2DM.

Serum and vitreous resistin levels in patıents with proliferative diabetic retinopathy

AIM

The aim of the study was to investigate the serum and vitreous levels of resistin in patients with the proliferative diabetic retinopathy (PDR) and to compare those with age-matched control subjects.

METHODS

The study included 45 eyes with PDR (group 1) and a control group of 22 (group 2). All eyes underwent vitrectomy surgery. The lipid profile, fasting blood glucose (FBG), HbA1c and resistin levels were investigated in blood samples of all subjects. Complete ophthalmological examinations were evaluated. Vitreous samples were collected from both groups during vitrectomy surgery and resistin levels were investigated in those samples. The results were evaluated using SPSS 9.0 software.

RESULTS

The demographic characteristics of the diabetic group and the control group were similar (p > 0.05). There was no significant difference between the groups in respect of mean visual acuity (VA), body mass index (BMI) values, or lipid profiles (p ˃ 0.05). There was no measurable value of resistin in the vitreous samples of all the eyes. The mean blood resistin level was 367 ng/ml in the control group and 387 ng/ml in the study group and the difference was not statistically significant (p > 0.05).

CONCLUSIONS

In the light of the findings of this study, it can be assumed that resistin did not pass through the vitreous at measurable levels. However, the serum resistin levels of the diabetic patients were higher than those of the control group although not statistically significant. Therefore, it can be considered that resistin does not play a major role in retinal neovascularization.

Exploring the interactional details between aldose reductase (AKR1B1) and 3-Mercapto-5H-1,2,4-triazino[5,6-b]indole-5-acetic acid through molecular dynamics simulations

Aldose reductase (AKR1B1) has been considered as a significant target for designing drugs to counteract the development of diabetic complications. In the present study, molecular dynamics (MD) simulations and molecular mechanics generalized Born surface area (MM-GB/SA) calculations were performed to make sure which tautomer is the preferred one among three tautomeric forms (Mtia1, Mtia2, and Mtia3) of 3-Mercapto-5H-1,2,4-triazino[5,6-b]indole-5-acetic acid (Mtia) for binding to AKR1B1. The overall structural features and the results of calculated binding free energies indicate that Mtia1 and Mtia2 have more superiority than Mtia3 in terms of binding to AKR1B1. Furtherly, the local active site conformational characteristics and non-covalent interaction analysis were identified. The results indicate that the combination of Mtia2 and AKR1B1 is more stable than that of Mtia1. Furthermore, two extra hydrogen bonds between AKR1B1 and Mtia2 are found with respect to Mtia1. In addition, Mtia2 makes slightly stronger electrostatic interaction with the positively charged nicotinamide group of NADP⁺ than Mtia1. Based on the results above, Mtia2 is the preferred tautomeric form among the three tautomers. Our study can provide an insight into the details of the interaction between AKR1B1 and Mtia at the atomic level, and will be helpful for the further design of AKR1B1 inhibitors.

Relationship of serum leptin with some biochemical, anthropometric parameters and abdominal fat volumes as measured by magnetic resonance imaging

AIMS

To measure the level of leptin in volunteers and correlate it with several anthropometric, biochemical variables and abdominal fat volumes.

METHODS

The level of leptin was investigated in 167 disease-free volunteers. Serum levels of IL-6, adiponectin, and resistin, blood lipid profile (cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride (TG) were determined. Waist circumference (WC) was measured using tape and magnetic resonance imaging (MRI) images.

RESULTS

All measured anthropometric (BMI, WC measured by tape and MRI) and biochemical variables (adiponectin, resistin, cholesterol, HDL, LDL and TG); and abdominal fats showed a significant (p<0.05) difference between participants with abnormal serum leptin levels and those with normal leptin levels. A higher percentage of participants with abnormal serum leptin were obese males while participants with normal leptin levels were either overweight or normal weight females. A significant (p <0.05) positive correlation was detected between serum leptin concentration and WC, BMI, subcutaneous fat, visceral fat, total abdominal fat, and resistin. A moderate association was found between serum leptin concentration and the inflammatory cytokine IL-6.

CONCLUSION

Abnormal serum leptin, was detected in obese male individuals which may be considered as an important indicator for the development of cardiovascular diseases and type 2 diabetes.

Obesity, metabolic syndrome and diabetic retinopathy: Beyond hyperglycemia

Diabetic retinopathy (DR) is the most feared ocular manifestation of diabetes. DR is characterized by progressive retinal damage that may eventually result in blindness. Clinically, this blindness is caused by progressive damage to the retinal microvasculature, which leads to ischemia, retinal swelling, and neovascularization. Retinopathy is associated with both type 1 and type 2 diabetes, with DR being the leading cause of new onset blindness in United States adults. Despite this strong association with diabetes, it must be noted that the development of retinopathy lesions is multifactorial and may occur in individuals without an established history of diabetes. Metabolic syndrome is a multifactorial condition of central obesity, hypertriglyceridemia, dyslipidemia, hypertension, fasting hyperglycemia, and insulin resistance. Although several studies examined the individual components observed in the metabolic syndrome in relation to the development of DR, there is conflicting data as to the association of the metabolic syndrome with the development of retinopathy lesions in non-diabetic subjects. This review will summarize the current literature on the evidence of the metabolic syndrome on retinopathy in subjects with and without an established history of diabetes. This review will also discuss some of the mechanisms through which metabolic syndrome can contribute to the development of retinopathy.

Effect of n-3 Polyunsaturated Fatty Acid Supplementation on Metabolic and Inflammatory Biomarkers in Type 2 Diabetes Mellitus Patients

BACKGROUND

Type 2 diabetes mellitus (T2DM) is accompanied by chronic low-grade inflammation, with an imbalance in the secretion of adipokines and, worsening insulin resistance. Supplementation with n-3 PUFA in T2DM decreases inflammatory markers, the purpose of the study was to investigate the effect of n-3 PUFA supplementation on adipokines, metabolic control, and lipid profile in T2DM Mexican adults.

METHODS

In a randomized, single-blind, placebo-controlled pilot study, 54 patients with T2DM received 520 mg of DHA + EPA-enriched fish-oil (FOG) or a placebo (PG) daily. Baseline and 24-week anthropometric and biochemical measurements included glucose, insulin, glycosylated hemoglobin (Hb1Ac), leptin, adiponectin, resistin, and lipid profile; n-3 PUFA intake was calculated in g/day.

RESULTS

Waist circumference and blood glucose showed significant reductions in the FOG group (p = 0.001 and p = 0.011, respectively). Hb1Ac (p = 0.009 and p = 0.004), leptin (p < 0.000 and p < 0.000), and leptin/adiponectin ratio (p < 0.000 and p < 0.000) decreased significantly in both groups after 24 weeks (FOG and PG respectively). Serum resistin (FOG p < 0.000 and PG p = 0.001), insulin (FOG p < 0.000 and PG p < 0.000), and HOMA-IR (FOG p = 0.000 and PG p < 0.000) increased significantly in both groups. FOG had an overall improvement in the lipid profile with a significant decrease in triacylgycerols (p = 0.002) and atherogenic index (p = 0.031); in contrast, the PG group had increased total cholesterol (p < 0.000), non-HDL cholesterol (p < 0.000), and atherogenic index (p = 0.017).

CONCLUSIONS

We found a beneficial effect of n-3 PUFA supplementation on waist circumference, glucose, Hb1Ac, leptin, leptin/adiponectin ratio, and lipid profile, without significant changes in adiponectin, and increases in resistin, insulin, and HOMA-IR in both groups.