Analysis of adiponectin gene polymorphisms in Chinese population with systemic lupus erythematosus

Circulating adiponectin levels and systemic lupus erythematosus: a two-sample Mendelian randomization study

OBJECTIVES

Several studies have reported increased serum/plasma adiponectin levels in SLE patients. This study was performed to estimate the causal effects of circulating adiponectin levels on SLE.

METHODS

We selected nine independent single-nucleotide polymorphisms that were associated with circulating adiponectin levels (P < 5 × 10-8) as instrumental variables from a published genome-wide association study (GWAS) meta-analysis. The corresponding effects between instrumental variables and outcome (SLE) were obtained from an SLE GWAS analysis, including 7219 cases with 15 991 controls of European ancestry. Two-sample Mendelian randomization (MR) analyses with inverse-variance weighted, MR-Egger regression, weighted median and weight mode methods were used to evaluate the causal effects.

RESULTS

The results of inverse-variance weighted methods showed no significantly causal associations of genetically predicted circulating adiponectin levels and the risk for SLE, with an odds ratio (OR) of 1.38 (95% CI 0.91, 1.35; P = 0.130). MR-Egger [OR 1.62 (95% CI 0.85, 1.54), P = 0.195], weighted median [OR 1.37 (95% CI 0.82, 1.35), P = 0.235) and weighted mode methods [OR 1.39 (95% CI 0.86, 1.38), P = 0.219] also supported no significant associations of circulating adiponectin levels and the risk for SLE. Furthermore, MR analyses in using SLE-associated single-nucleotide polymorphisms as an instrumental variable showed no associations of genetically predicted risk of SLE with circulating adiponectin levels.

CONCLUSION

Our study did not find evidence for a causal relationship between circulating adiponectin levels and the risk of SLE or of a causal effect of SLE on circulating adiponectin levels.

The Association between Adiponectin Single Nucleotide Polymorphisms and Side Effects of Isotretinoin in Acne Patients

Background

Acne is a common condition of pilosebaceous follicle especially among young. Clinically, the most used medication in the treatment of moderate to severe acne is oral isotretinoin. However, interindividual variability in therapeutic response to isotretinoin and many side effects such as musculoskeletal pain, headache, and alteration in lipid profile can be seen with this treatment.

Aim

In this study, the effect of genetic polymorphisms, rs2241766 and rs1501299, of the adiponectin gene was investigated in relation to the side effects of isotretinoin-treated young adult acne patients (n = 230).

Methods

Several biochemical parameters were measured at baseline and after treatments with isotretinoin. The ADIPOQ gene SNPs, rs2241766 and rs1501299, were genotyped in 230 patients.

Results

Alterations in lipid profile with a significant increase of ALT (P=0.007) were detected after isotretinoin treatment. Moreover, percentage change in HDL following isotretinoin treatment was significantly associated with rs1501299 (P=0.008). On the other hand, no associations between examined SNPs and side effects of isotretinoin and other lipid parameters (total cholesterol, LDL, and triglycerides) or liver function enzymes (ALT and AST) were detected.

Conclusions

Current findings showed that rs1501299 of the ADIPOQ gene might be associated with changes in HDL level in acne patients following treatment with isotretinoin.

Association of omentin-1, adiponectin, and resistin genetic polymorphisms with systemic lupus erythematosus in a Chinese population

OBJECTIVE

An increasing number of studies have demonstrated the roles of adipokines in systemic lupus erythematosus (SLE). We aimed to investigate the association of genetic variations of omentin-1, adiponectin, and resistin with SLE susceptibility.

METHODS

We selected 623 SLE patients and 665 normal controls in the present study. Genotyping of omentin-1 rs2274907, rs35779394, rs79209815, and rs13376023; adiponectin rs16861194 and rs266729; and resistin rs1862513, rs3745368, and rs3745367 was conducted by TaqMan SNP genotyping assays.

RESULTS

Overall, we found no significant differences in the allele or genotype frequencies of the nine studied SNPs between the SLE patients and controls. However, an increased frequency of the resistin rs3745368 variant was observed in the SLE patients under the dominant model (P = 0.024). In omentin-1, the rs13376023 A allele was found to be related to oral ulcers in SLE patients (P = 0.013), and the rs35779394 C and rs13376023 A allele frequencies were significantly lower in SLE patients with BMI ≥ 24 kg/m² (P = 0.019, P = 0.033, respectively). For resistin, the frequencies of the rs3745368 AA genotype and A allele were lower in SLE patients with discoid rash (P = 0.036, P = 0.011), and the rs3745368 A allele frequency was higher in SLE patients with lupus nephritis (P = 0.018). The resistin rs3745367 AA genotype and A allele frequencies were related to the occurrence of renal disorder in SLE patients (P = 0.024, P = 0.009). The haplotype analysis showed that the CGA haplotype of resistin was associated with susceptibility to SLE (P = 0.005). No significant associations of plasma omentin-1, adiponectin or resistin levels with their respective genotypes were found in SLE patients.

CONCLUSIONS

In summary, omentin-1, adiponectin and resistin SNPs are not associated with the genetic background of SLE in Chinese patients. However, omentin-1 and resistin genetic variations might contribute to several clinical phenotypes of SLE.

Metabolic determinants of lupus pathogenesis

The metabolism of healthy murine and more recently human immune cells has been investigated with an increasing amount of details. These studies have revealed the challenges presented by immune cells to respond rapidly to a wide variety of triggers by adjusting the amount, type, and utilization of the nutrients they import. A concept has emerged that cellular metabolic programs regulate the size of the immune response and the plasticity of its effector functions. This has generated a lot of enthusiasm with the prediction that cellular metabolism could be manipulated to either enhance or limit an immune response. In support of this hypothesis, studies in animal models as well as human subjects have shown that the dysregulation of the immune system in autoimmune diseases is associated with a skewing of the immunometabolic programs. These studies have been mostly conducted on autoimmune CD4⁺ T cells, with the metabolism of other immune cells in autoimmune settings still being understudied. Here we discuss systemic metabolism as well as cellular immunometabolism as novel tools to decipher fundamental mechanisms of autoimmunity. We review the contribution of each major metabolic pathway to autoimmune diseases, with a focus on systemic lupus erythematosus (SLE), with the relevant translational opportunities, existing or predicted from results obtained with healthy immune cells. Finally, we review how targeting metabolic programs may present novel therapeutic venues.

Genetic polymorphisms associated with the prevalence of retinal vein occlusion in a Greek population

PURPOSE

To investigate possible associations of single-nucleotide polymorphisms (SNPs) from five genes with branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO).

METHODS

A total of 69 patients with retinal vein occlusion-RVO (24 with BRVO and 45 with CRVO), and 82 controls, were enrolled in this study. All subjects were screened for hypertension, diabetes mellitus, hyperlipidemia, glaucoma, anticoagulant medication, smoking status and history of stroke. The genotyping of AGTR1-A1166C, adiponectin + 276 G/T, MMP2-1306C/T, Gpla/lla-C807T/G873A and VKORC1-G1639A polymorphisms was performed using restriction fragment length polymorphism or allele-specific polymerase chain reaction.

RESULTS

The percentage of the AGTR1-A1166C C allele carriers and Gpla/lla-C807T/G873A T/A carriers was significantly higher in the CRVO patients than in the controls (P = 0.00001 and P = 0.0004, respectively). At the multiple logistic regression analysis, the AGTR1-A1166C C allele carrier status and the Gpla/lla-C807T/G873A T/A allele carrier status were found to be associated with an increased risk of CRVO. Moreover, adiponectin + 276 G/T T allele carriers had a significantly increased risk of RVO in subjects ≥ 75 years old. There was no significant difference between the BRVO patients and controls concerning the genotype or the allele frequency distributions of these SNPs. The genotype distributions or allelic frequencies of the other evaluated polymorphisms did not significantly differ between the patients with RVO and the control subjects.

CONCLUSIONS

AGTR1 A1166C and Gpla/lla C807T/G873A polymorphisms are likely to be risk factors for CRVO. Adiponectin + 276 G/T SNP is likely to predispose to RVO in older subjects.

A Saccharomyces cerevisiae assay system to investigate ligand/AdipoR1 interactions that lead to cellular signaling

Adiponectin is a mammalian hormone that exerts anti-diabetic, anti-cancer and cardioprotective effects through interaction with its major ubiquitously expressed plasma membrane localized receptors, AdipoR1 and AdipoR2. Here, we report a Saccharomyces cerevisiae based method for investigating agonist-AdipoR interactions that is amenable for high-throughput scale-up and can be used to study both AdipoRs separately. Agonist-AdipoR1 interactions are detected using a split firefly luciferase assay based on reconstitution of firefly luciferase (Luc) activity due to juxtaposition of its N- and C-terminal fragments, NLuc and CLuc, by ligand induced interaction of the chimeric proteins CLuc-AdipoR1 and APPL1-NLuc (adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain and leucine zipper motif 1-NLuc) in a S. cerevisiae strain lacking the yeast homolog of AdipoRs (Izh2p). The assay monitors the earliest known step in the adiponectin-AdipoR anti-diabetic signaling cascade. We demonstrate that reconstituted Luc activity can be detected in colonies or cells using a CCD camera and quantified in cell suspensions using a microplate reader. AdipoR1-APPL1 interaction occurs in absence of ligand but can be stimulated specifically by agonists such as adiponectin and the tobacco protein osmotin that was shown to have AdipoR-dependent adiponectin-like biological activity in mammalian cells. To further validate this assay, we have modeled the three dimensional structures of receptor-ligand complexes of membrane-embedded AdipoR1 with cyclic peptides derived from osmotin or osmotin-like plant proteins. We demonstrate that the calculated AdipoR1-peptide binding energies correlate with the peptides’ ability to behave as AdipoR1 agonists in the split luciferase assay. Further, we demonstrate agonist-AdipoR dependent activation of protein kinase A (PKA) signaling and AMP activated protein kinase (AMPK) phosphorylation in S. cerevisiae, which are homologous to important mammalian adiponectin-AdipoR1 signaling pathways. This system should facilitate the development of therapeutic inventions targeting adiponectin and/or AdipoR physiology.

Amerindians show association to obesity with adiponectin gene SNP45 and SNP276: population genetics of a food intake control and "thrifty" gene

Adiponectin gene polymorphisms SNP45 and SNP276 have been related to metabolic syndrome (MS) and related pathologies, including obesity. However results of associations are contradictory depending on which population is studied. In the present study, these adiponectin SNPs are for the first time studied in Amerindians. Allele frequencies are obtained and comparison with obesity and other MS related parameters are performed. Amerindians were also defined by characteristic HLA genes. Our main results are: (1) SNP276 T is associated to low diastolic blood pressure in Amerindians, (2) SNP45 G allele is correlated with obesity in female but not in male Amerindians, (3) SNP45/SNP276 T/G haplotype in total obese/non-obese subjects tends to show a linkage with non-obese Amerindians, (4) SNP45/SNP276 T/T haplotype is linked to obese Amerindian males. Also, a world population study is carried out finding that SNP45 T and SNP276 T alleles are the most frequent in African Blacks and are found significantly in lower frequencies in Europeans and Asians. This together with the fact that there is a linkage of this haplotype to obese Amerindian males suggest that evolutionary forces related to famine (or population density in relation with available food) may have shaped world population adiponectin polymorphism frequencies.