Genetics of serum resistin: a paradigm of population-specific regulation?

Resistin adipokin in atopic dermatitis patients: A clinical, biochemical, and genetic study

BACKGROUND/OBJECTIVES

Atopic dermatitis (AD) is an inflammatory chronic skin disorder. The etiology of AD is not fully understood. Therefore, we aimed by this study to shed light on the potential role of resistin in an etiopathogenesis of AD through investigation of resistin rs3745367 single nucleotide polymorphism (SNP) and resistin serum levels, and their relation to leukocytic count in a sample of Egyptian patients having atopic dermatitis.

METHODS

This case-control study included 45 patients having AD and 40 controls. SCORAD index was assessed to evaluate the severity of AD. CBC, ELISA, and PCR-RFLP were performed to detect leukocytic count, resistin serum level, and resistin rs3745367 SNP, respectively.

RESULTS

Atopic dermatitis patients had significant low serum resistin concentrations (P = .036) and a significantly high frequency of leukocytosis (P = .003). Low resistin serum levels were significantly related to AD disease severity (P < .001) and the presence of leukocytosis (P < .001). Resistin rs3745367 GG genotype (P = .030), as well as its G allele (P = .019), was expressively associated with AD development, and both increased the risk of AD by 3- and 2-fold, respectively. Resistin rs3745367 GG genotype was significantly linked to low resistin serum levels (P < .001), AD-positive family history (P = .015), and the presence of leukocytosis (P < .001).

CONCLUSIONS

Resistin rs3745367 gene polymorphism may contribute to the development of AD. Resistin may have an immune-modulating active character in the AD etiopathogenesis that could be mediated through its anti-inflammatory effect. From this piece of work, we may suggest resistin as a new therapy to mitigate the pro-inflammatory environment found in AD.

Relevance of single-nucleotide polymorphism to the expression of resistin gene affecting serum and gingival crevicular fluid resistin levels in chronic periodontitis and type 2 diabetes mellitus: A randomized control clinical trial

Aim:

The present study is aimed to investigate whether single-nucleotide polymorphism (SNP) of resistin gene (RETN) at −420 and +299 sites, is associated with resistin levels in serum and gingival crevicular fluid (GCF) in periodontally healthy, chronic periodontitis (CP) with and without type 2 diabetes mellitus (T2DM) patients.

Materials and Methods:

Serum and GCF samples were procured from all the 60 patients (twenty in each group) of the three study groups i.e., periodontally healthy (Group I), CP (Group II) and CP with T2DM patients (Group III) to analyze resistin levels using enzyme-linked immunosorbent assay test and clinical parameters were assessed at baseline and at 3 months after scaling and root planing (SRP). RETN polymorphism at −420 and +299 was genotyped by polymerase chain reaction-restriction fragment length polymorphism technique.

Results:

Patients with SNP −420 and +299 were positively correlated with increased serum and GCF resistin levels in Group II and Group III patients. SRP led to substantial reduction in the serum and GCF resistin levels.

Conclusion:

These findings are suggestive of a biologic link between resistin, periodontal diseases, and periodontal diseases with T2DM and RETN SNP at −420 and +299 in imparting increased resistin levels in inflammatory and diabetic conditions.

Role of resistin genetic variations in knee osteoarthritis pathogenesis, a cross sectional study

Osteoarthritis (OA) is a serious health concern globally and is recognized by degradation of articular cartilage, bone remodeling and synovial inflammation. Resistin is an adipokine that shown to be involved in inflammatory process associated with OA. Aim of the current study was to estimate the link of resistin gene polymorphisms (- 420 C>G, + 299 G>A) with genetic susceptibility of knee OA in a Pakistani population. 280 patients and 308 age and sex matched controls were recruited in this case-control study. Genotype and allele frequencies were evaluated by Polymerase chain reaction-Restriction Fragment Length Polymorphism. Resistin concentration was measured by immunoassay. A significant difference in allele and genotype frequency was observed for both study groups. Resistin - 420 mutant genotype was associated with an increased susceptibility to OA (p = 0.001). Similarly, resistin + 299 GA + AA genotypes showed a relation with an elevated risk of knee OA compared to GG genotype (p = 0.01). Moreover, the mutant alleles frequency was significantly high in patient group as compared to healthy individuals for both loci (p < 0.01). Resistin - 420/+ 299 alleles haplotype analysis demonstrated that mutant alleles were more prevalent in OA affected individuals compared to healthy subjects (p < 0.05). The serum resistin levels were not remarkably different in patient vs. control group (p = 0.9). Further, the circulating resistin level was not found to be influenced by - 420G and + 299A alleles and non significant differences were observed in resistin concentration in mutant vs. wild type genotypes for both SNPs (p > 0.05). Our data suggest an association between investigated resistin genetic variants and knee OA susceptibility in our population. This is the first report to show association between investigated single nucleotide polymorphisms and OA among any population.

Association between serum resistin, adiposity measures and inflammatory makers in women without cardiovascular diseases

AIMS

The convergence of obesity and inflammation in the pathogenesis of cardiovascular diseases (CVD) has been recognized over the past decade. Resistin has emerged as a novel secreted protein with links to both insulin resistance and inflammation. We aimed to investigate the relationship between changes in serum resistin levels with metabolic parameters, including obesity and inflammatory markers in women free of CVD.

METHODS AND RESULTS

A total of 200 apparently healthy women were consecutively recruited from the Out-patients Clinics at King Abdulaziz university Hospital in Jeddah, Saudi Arabia. They were classified into 4 groups based on quartile for serum resistin. Anthropometric variables were measured in all study subjects. Fasting blood samples were collected for measurement of lipid profile, blood glucose and inflammatory markers. Study subjects within the upper quartile (Q4) had significantly higher body height (p < 0.0001), waist and hip circumferences (p < 0.05) and inflammatory markers (p < 0.0001) values than those in the lower quartile (Q1). Significant correlations were found between circulating resistin levels and systolic blood pressure, some anthropometric measures as well as inflammatory markers.

CONCLUSION

Serum resistin levels were found to be increased in overweight and obese women. Resistin was also independently associated with hs-CRP in women free of CVD, suggesting that resistin may be related to low-grade inflammation among obese subjects in the absence of overt CVD.

Serum resistin is causally related to mortality risk in patients with type 2 diabetes: preliminary evidences from genetic data

Resistin has been firmly associated with all-cause mortality. We investigated, whether, in patients with type 2 diabetes (T2D), this association is sustained by a cause-effect relationship. A genotype risk score (GRS), created by summing the number of resistin increasing alleles of two genome-wide association studies (GWAS)-derived single nucleotide polymorphisms (SNPs), serum resistin measurements and all-cause death records were obtained in 1,479 (403 events/12,454 person-years), patients with T2D from three cohorts, Gargano Heart Study-prospective design (n = 350), Gargano Mortality Study (n = 698) and Foggia Mortality Study (n = 431), from Italy. GRS was strongly associated with serum resistin in a non-linear fashion (overall p = 3.5 * 10^-7) with effect size modest for GRS = 1 and 2 and much higher for GRS >3, with respect to GRS = 0. A significant non-linear association was observed also between GRS and all-cause mortality (overall p = 3.3 * 10^-2), with a low effect size for GRS = 1 and 2, and nearly doubled for GRS ≥ 3, with respect to GRS = 0. Based on the above-reported associations, each genetic equivalent SD increase in log-resistin levels showed a causal hazard ratio of all-cause mortality equal to 2.17 (95%CI: 1.22-3.87), thus providing evidence for a causal role of resistin in shaping the risk of mortality in diabetic patients.

Resistin - 420 C/G polymorphism and serum resistin level in Iranian patients with gestational diabetes mellitus

Background

Resistin is a circulating adipokine with insulin-antagonizing effects. The aim of this study was to investigate the relationship between the single nucleotide polymorphism (SNP) -420C > G in the resistin gene with serum resistin levels, insulin resistance, and risk of gestational diabetes (GDM) in Iranian population.

Method

75 GDM patients and 70 healthy pregnant women were enrolled in this study. Genotyping for SNP- 420C > G in the resistin gene was performed by the polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) method. Serum resistin and insulin were measured by immunoassay. Blood glucose levels and lipid profile were measured by enzymatic methods. Homeostasis model of assessment for insulin resistance (HOMA-IR) were calculated.

Result

GG genotype and G allele of SNP-420C > G were more frequent in GDM patients compared to non-GDM subjects. Serum resistin level was similar in GDM and non-GDM patients. The serum levels of resistin in GDM and non-GDM women with GG genotype were similar to those with GC + CC genotype. Multivariate logistic regression analysis after adjusting for confounding factors showed a higher susceptibility to GDM in patients with GG genotype compared to subjects with GG + GT genotype (odds ratio = 4.59, 95% CI; 1.96-10.71, p = 0.00). Serum resistin level was correlated with serum triglyceride, total and low density lipoprotein (LDL) cholesterol (p < 0.05) in GDM patients. No significant association was found between serum resistin, insulin resistance, and SNP-420C > G.

Conclusion

The SNP-420C/G of resistin gene is associated with genetic susceptibility to GDM in our population. Further studies are necessary to confirm the role of this polymorphism in pathogenesis of GDM and to explore potential mechanisms by which it modulates susceptibility to GDM.

Serum resistin and glomerular filtration rate in patients with type 2 diabetes

Background

High serum levels of the pro-inflammatory adipokine resistin have been associated with decreased renal function in the general population. The goal of this study was to investigate whether such association is also present among diabetic subjects, who are at increased risk of renal function loss.

Methods

The cross-sectional association between serum resistin levels and estimated glomerular filtration rate (eGFR) was investigated in 1,560 type 2 diabetic (T2D) patients of European ancestry comprised in two different cohorts: 762 patients from San Giovanni Rotondo (SGR; Italy) and 798 patients from Boston (US).

Results

Serum resistin was inversely associated with eGFR in SGR [β (SE) for one SD of resistin increment = -1.01 (0.70) ml/min/1.73m², p = 0.019] and in Boston [β (SE) = -5.31 (0.74) ml/min/1.73m², p < 0.001] samples, as well as in the two studies combined [β (SE) = -3.42 (0.52) ml/min/1.73m², p < 0.001]. The association was unaffected by adjustment for smoking habits, BMI, waist circumference, diabetes duration, HbA1c, insulin treatment, hypertension and lipid-lowering therapy: β (SE) for one SD of resistin increment = -1.07 (0.70), p = 0.02; -5.50 (0.88), p < 0.001; and -2.81 (0.55) ml/min/1.73m², p < .001, in SGR, Boston and the two studies combined, respectively. The association was significantly stronger in men than in women (p for resistin-by-gender interaction = 0.003). For each resistin SD increment, the odds of having eGFR < 0 ml/min/1.73m² increased by 22% (OR = 1.22; 95% CI 1.02–1.44; p = 0.025) in SGR sample, 69% (OR = 1.69; 95% CI 1.38–2.07; p < 0.001) in Boston sample, and 47% (OR = 1.47; 95% CI 1.29–1.68; p < 0.001) in the two studies considered together. Similar associations were observed in the adjusted model: OR 95% CI for each SD resistin increment being 1.23 (1.03–1.46), p = 0.021; 1.52 (1.20–1.92), p < 0.001; 1.33 (1.16–1.53), p < 0.001, in SGR, Boston and the two studies combined, respectively.

Conclusions

This is the first report of an association between high serum resistin and low eGFR in patients with T2D of European ancestry.

Association of four insulin resistance genes with type 2 diabetes mellitus and hypertension in the Chinese Han population

Insulin resistance plays an important role in the development of type 2 diabetes mellitus (T2DM) and hypertension. The purpose of the present study was to evaluate the association between four insulin resistance genes (ADIPOQ, LEPR, RETN, and TRIB3) and both T2DM and hypertension. A total of 768 Han Chinese subjects were recruited into this study, including 188 cases who had T2DM alone, 223 cases who had hypertension alone, 181 cases with both T2DM and hypertension, and 176 control subjects with neither T2DM nor hypertension. Twenty-three tag SNPs in four insulin resistance genes were genotyped and analyzed for association with T2DM and hypertension. One intron SNP (rs13306519) in LEPR and one 3′UTR SNP (rs1063537) in ADIPOQ demonstrated a significant association with T2DM (P = 0.024 and 0.014 respectively). Another intron SNP (rs12037879) in LEPR and a promoter region SNP (rs266729) in ADIPOQ were significantly associated with hypertension (P = 0.041 and 0.042, respectively). These associations survived the permutation test (P = 0.023, 0.018, 0.026, and 0.035, respectively). These associations were still found to be significant in the additive model after adjusting for potential confounding factors including age, sex, BMI, HDL, LDL, total cholesterol, and triglyceride levels (P = 0.024, 0.016, 0.04, and 0.043, respectively). No other gene variants were found to be significantly associated with T2DM or hypertension (P > 0.05). None of the studied gene variants were found to be significantly associated with T2DM+ hypertension (P > 0.05). A significant interaction was observed between two SNPs rs13306519 in LEPR and rs266729 in ADIPOQ for T2DM (P_int = 0.012, OR_int = 2.67) and hypertension (P_int = 0.0041, OR_int = 2.23). These findings suggest that variants in ADIPOQ and LEPR are risk factors for T2DM and hypertension in the Chinese population and that variants in RETN and TRIB3 are not major risk factors for these diseases.

Serum resistin, cardiovascular disease and all-cause mortality in patients with type 2 diabetes

Background

High serum resistin has been associated with increased risk of cardiovascular disease in the general population, Only sparse and conflicting results, limited to Asian individuals, have been reported, so far, in type 2 diabetes. We studied the role of serum resistin on coronary artery disease, major cardiovascular events and all-cause mortality in type 2 diabetes.

Methods

We tested the association of circulating resistin concentrations with coronary artery disease, major cardiovascular events (cardiovascular death, non-fatal myocardial infarction and non-fatal stroke) and all-cause mortality in 2,313 diabetic patients of European ancestry from two cross-sectional and two prospective studies. In addition, the expression of resistin gene (RETN) was measured in blood cells of 68 diabetic patients and correlated with their serum resistin levels.

Results

In a model comprising age, sex, smoking habits, BMI, HbA1c, and insulin, antihypertensive and antidyslipidemic therapies, serum resistin was associated with coronary artery disease in both cross-sectional studies: OR (95%CI) per SD increment = 1.35 (1.10–1.64) and 1.99 (1.55–2.55). Additionally, serum resistin predicted incident major cardiovascular events (HR per SD increment = 1.31; 1.10–1.56) and all-cause mortality (HR per SD increment = 1.16; 1.06–1.26). Adjusting also for fibrinogen levels affected the association with coronary artery disease and incident cardiovascular events, but not that with all cause-mortality. Finally, serum resistin was positively correlated with RETN mRNA expression (rho = 0.343).

Conclusions

This is the first study showing that high serum resistin (a likely consequence, at least partly, of increased RETN expression) is a risk factor for cardiovascular disease and all-cause mortality in diabetic patients of European ancestry.

Common mechanisms of dysfunctional adipose tissue and obesity-related cancers

The relation between cancer and metabolic disorders was recognized several decades ago, but the underlying mechanisms involved in cancer development and progression remain obscure. In the last years, many groups have been studying systemic adipose tissue markers in cancer patients. However, few consistent results were obtained. On the other hand, several studies revealed many aspects of adipose tissue physiology in obesity. Nowadays, it is recognized that excessive lipid uptake in adipocytes leads to hypertrophy and consequently to metabolic dysregulation, hypoxia, inflammation, impaired adipocytokine expression and angiogenesis, insulin resistance and macrophage recruitment. In obese patients, tumours commonly colocalize with excessive adipose tissue accumulation, and most of the features of hypertrophic adipose tissue are observed in cancer patients, namely breast and colon. This review aimed to summarize pathological adipose tissue alterations that may contribute to cancer aetiology and development.

Genome-wide association analysis identifies TYW3/CRYZ and NDST4 loci associated with circulating resistin levels

Resistin is a polypeptide hormone that was reported to be associated with insulin resistance, inflammation and risk of type 2 diabetes and cardiovascular disease. We conducted a genome-wide association (GWA) study on circulating resistin levels in individuals of European ancestry drawn from the two independent studies: the Nurses' Health Study (n = 1590) and the Health, Aging and Body Composition Study (n = 1658). Single-nucleotide polymorphisms (SNPs) identified in the GWA analysis were replicated in an independent cohort of Europeans: the Gargano Family Study (n = 659). We confirmed the association with a previously known locus, the RETN gene (19p13.2), and identified two novel loci near the TYW3/CRYZ gene (1p31) and the NDST4 gene (4q25), associated with resistin levels at a genome-wide significant level, best represented by SNP rs3931020 (P = 6.37 × 10(-12)) and SNP rs13144478 (P = 6.19 × 10(-18)), respectively. Gene expression quantitative trait loci analyses showed a significant cis association between the SNP rs3931020 and CRYZ gene expression levels (P = 3.68 × 10(-7)). We also found that both of these two SNPs were significantly associated with resistin gene (RETN) mRNA levels in white blood cells from 68 subjects with type 2 diabetes (both P = 0.02). In addition, the resistin-rising allele of the TYW3/CRYZ SNP rs3931020, but not the NDST4 SNP rs13144478, showed a consistent association with increased coronary heart disease risk [odds ratio = 1.18 (95% CI, 1.03-1.34); P = 0.01]. Our results suggest that genetic variants in TYW3/CRYZ and NDST4 loci may be involved in the regulation of circulating resistin levels. More studies are needed to verify the associations of the SNP rs13144478 with NDST4 gene expression and resistin-related disease.

Serum resistin and kidney function: a family-based study in non-diabetic, untreated individuals

Background

High serum resistin levels have been associated with kidney dysfunction. Most of these studies have been carried out in individuals with severe kidney impairment, diabetes, cardiovascular disease and related treatments. Thus, the observed association might have been influenced by these confounders. Our aim was to study the relationship between serum resistin, urinary albumin/creatinine ratio (ACR) and glomerular filtration rate (GFR) in a family-based sample, the Gargano Family Study (GFS) of 635 non diabetic, untreated Whites.

Methods

A linear mixed effects model and bivariate analyses were used to evaluate the phenotypic and genetic relations between serum resistin and both ACR and eGFR. All analyses were adjusted for sex, age, age squared, BMI, systolic blood pressure, smoking habits and physical exercise.

Results

After adjustments, resistin levels were slightly positively associated with ACR (β±SE = 0.049±0.023, p = 0.035) and inversely related to eGFR (β±SE = −1.43±0.61, p = 0.018) levels. These associations remained significant when either eGFR or ACR were, reciprocally, added as covariates. A genetic correlation (ρg = −0.31±0.12; adjusted p = 0.013) was observed between resistin and eGFR (but not ACR) levels.

Conclusion

Serum resistin levels are independently associated with ACR and eGFR in untreated non-diabetic individuals. Serum resistin and eGFR share also some common genetic background. Our data strongly suggest that resistin plays a role in modulating kidney function.