A functional promoter polymorphism in interleukin 12B gene is associated with an increased risk of ovarian endometriosis

Association between gene polymorphisms of IL-12, IL-12 receptor and IL-27 and organ involvement in Iranian endometriosis patients

Endometriosis is an inflammatory disease characterized by the presence of ectopic endometrial tissue, immune cell dysfunction and abnormal cytokine secretion. In addition to immunological factors, genetic variations that influence endometriosis severity and cytokine expression levels play important roles in the pathogenesis of this disease. Interleukin-12 (IL-12), specifically its p40 subunit encoded by IL-12B gene and the interleukin-12 receptor β1 (IL-12Rβ2) chain of its receptor, as well as interleukin-27 (IL-27) are important in the establishment of endometriosis. So, in this study, we measured IL-12 and IL-27 serum levels and investigated the possible links between IL-12B rs3212227, IL-12Rβ2 rs3790565 and IL-27 rs153109 polymorphisms and the risk of developing endometriosis in a group of Iranian women. In this case-control study, 162 endometriosis patients and 151 healthy women were included and tested for the aforementioned polymorphisms using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The enzyme-linked immunosorbent assay (ELISA) method was also used to measure IL-12 and IL-27 serum levels. Although there was no statistically significant association between the genotypes and alleles of the studied polymorphisms and the development of endometriosis in general, the AA genotype of IL-12B rs3212227 showed a significant association with uterine endometriosis when compared to AC+CC genotypes (p = .04, CI = 0.270-0.988, OR = 0.517). Indeed, the AA genotype of the IL-12B rs3212227 single nucleotide polymorphism (SNP) may be linked with a lower risk of developing uterine endometriosis. There was no significant difference in IL-27 levels between the two studied groups (p = .49), and IL-12 levels were undetectable in both groups. In conclusion, the AA genotype of IL-12B rs3212227 might be associated with a decreased risk of uterine involvement in endometriosis patients.

Association between interleukin 12B and interleukin 23R gene polymorphisms and systemic lupus erythematosus: a meta-analysis

OBJECTIVE

To determine whether polymorphisms of interleukin 12B (IL12B) and IL23 receptor genes (IL23R) confer susceptibility to systemic lupus erythematosus (SLE).

METHODS

A meta-analysis was conducted to analyze the associations between SLE and IL12B rs3212227 and rs17860508 and IL23R rs7517847, rs10489629, rs10889677, rs1004819, rs11209026, rs11209032, rs1343151, and rs1884444 polymorphisms using allele contrast, dominant, recessive, heterozygote, and homozygote models. Ten studies involving 1989 patients with SLE and 2394 controls were considered for the meta-analysis.

RESULTS

The meta-analysis using the homozygote model revealed that IL23R rs10889677 was significantly associated with SLE susceptibility in the overall population (AA vs. CC) (odds ratio = 0.70, 95% confidence interval = 0.50-0.98) but not in the Asian population. Other polymorphisms of IL12B and IL23R were not significantly associated with SLE protection.

CONCLUSIONS

These findings suggest that the IL23R rs10889677 polymorphism confers SLE susceptibility to individuals of certain ethnicities. (Research Registry number: 1268).

Association of interleukin-12B gene polymorphisms and mRNA expression with preeclampsia

OBJECTIVE

To explore the effects of functional genetic polymorphisms of the interleukin-12B (IL-12B) gene on the susceptibility to preeclampsia in northern Chinese women.

STUDY DESIGN

Maternal peripheral blood from 306 preeclamptic women and 310 control women and the placentas from 52 preeclamptic and 55 control women were collected. Two polymorphisms (rs17860508 and rs3212227) of the IL-12B gene were genotyped by polymerase chain reaction (PCR) with a direct sequencing method. The mRNA expression of IL-12B in the placentas was measured by quantitative real-time PCR (qRT-PCR).

RESULTS

Significant differences were observed between preeclamptic women and the control group in the genotype frequencies of rs17860508 (P = 0.017). Compared with the TTAGAG/TTAGAG genotype of rs17860508, the GC/GC genotype were associated with a higher risk of preeclampsia (adjusted OR: 1.95; 95% CI = 1.18-3.22; P = 0.009), especially the early-onset preeclampsia (adjusted OR: 2.40; 95% CI = 1.23-4.68; P = 0.010). The qRT-PCR results showed that the mRNA levels of IL-12B were significantly higher in the placentas of preeclampsia patients than that in the placentas of controls (P = 0.001). Moreover, the expression of IL-12B mRNA was significantly higher in the placentas of patients carrying the GC/GC genotype than in those carrying the TTAGAG/GC (P = 0.007) and TTAGAG/TTAGAG (P = 0.005) genotypes.

CONCLUSION

The GC/GC genotype of rs17860508 polymorphism may be a risk factor for the early-onset preeclampsia by upregulating the expression of IL-12B in northern Chinese women.

Genetic Variation of Glutathione S-Transferase M1 Is Associated with Patients with Ovarian Endometriosis and Endometriosis-Related Primary Infertility

BACKGROUND

The aim of the study was to investigate the role of the genetic variation of glutathione S-transferase M1 (GSTM1) in the development of ovarian endometriosis and endometriosis-related primary infertility risk.

METHODS

This case-control study included 564 women with ovarian endometriosis and 576 normal women in the control group in northern China. The polymorphism of GSTM1 was genotyped by polymerase chain reaction (PCR)/ligase detection reaction method. To assess the biological significance of polymorphisms, the level of GSTM1 mRNA expression in patients' endometrial tissues with different genotypes was detected by quantitative real-time PCR (qRT-PCR).

RESULTS

Compared with the positive genotype, the null genotype of GSTM1 was associated with the risk of developing ovarian endometriosis (OR = 1.29, 95% CI = 1.02-1.62). Further analysis showed that patients with a null genotype also had a significantly higher risk of primary infertility than patients with positive genotypes (OR = 1.59, 95% CI = 1.01-2.49). In addition, we found that GSTM1 mRNA expression was present in the endometrial tissue of all patients, but the expression level of patients with a positive genotype was nearly 10 times higher than that of patients with a negative genotype.

CONCLUSION

Our results suggest that the GSTM1 polymorphism is not only related to the genetic susceptibility to ovarian endometriosis but also a potential molecular marker of primary infertility in patients with ovarian endometriosis.

Aberrant methylation of the IL-12B promotor region contributes to the risk of developing ovarian endometriosis

Studies have shown that aberrant expression of IL-12p40, which is encoded by the interleukin-12B (IL-12B) gene, may be involved in the development of endometriosis. In this study, we investigated the role of aberrant methylation of the IL-12B promoter region and its associated expression in the development of ovarian endometriosis. By using pyrosequencing, we analyzed the methylation level of the IL-12B promoter region in eutopic and ectopic endometrium of patients with ovarian endometriosis and normal endometrium of control women. The expression of IL-12B mRNA was detected by quantitative real-time PCR. The results showed that the methylation level of the IL-12B promoter region in ectopic and eutopic endometrium of patients with ovarian endometriosis was significantly lower than that in endometrium of women without endometriosis ( p < 0.001 and p = 0.041, respectively). In contrast, mRNA levels were significantly increased in ectopic and eutopic endometrium of patients with ovarian endometriosis compared to those in endometrium of women without endometriosis ( p < 0.001 and p = 0.042, respectively). Correlation analysis showed that the methylation level of the IL-12B promoter region was negatively correlated with mRNA levels of IL-12B ( p < 0.001). Our data suggested that aberrant methylation of the IL-12B promoter region may be responsible for aberrant IL-12B mRNA expression in endometrium tissue of women, which may be associated with the development of ovarian endometriosis in northern Chinese women.

Defining the genetic profile of endometriosis

Endometriosis is a pathological condition which has been extensively studied, since its pathophysiology stems from a broad spectrum of environmental influences and genetic factors. Familial studies aim at defining inheritance trends, while linkage analysis studies focus on the identification of genetic sites related to endometriosis susceptibility. Genetic association studies take into account candidate genes and single nucleotide polymorphisms, and hence target at unraveling the association between disease severity and genetic variation. The common goal of various types of studies is, through genetic mapping methods, the timely identification of therapeutic strategies for disease symptoms, including pelvic pain and infertility, as well as efficient counselling. While genome-wide association studies (GWAS) play a primary role in depicting genetic contributions to disease development, they entail a certain bias as regards the case-control nature of their design and the reproducibility of the results. Nevertheless, genetic-oriented studies and the implementation of the results through clinical tests, hold a considerable advantage in proper disease management. In this review article, we present information about gene-gene and gene-environment interactions involved in endometriosis and discuss the effectiveness of GWAS in identitying novel potential therapeutic targets in an attempt to develop novel therapeutic strategies for a better management and treatment of patients with endometriosis.