Interleukin-18 gene promoter polymorphisms and recurrent spontaneous abortion

Chronic Venous Disease during Pregnancy Is Related to Inflammation of the Umbilical Cord: Role of Allograft Inflammatory Factor 1 (AIF-1) and Interleukins 10 (IL-10), IL-12 and IL-18

Chronic venous disease (CVD) is a common condition that affects the veins in the lower limbs, resulting in a variety of symptoms, such as swelling, pain, and varicose veins (VVs). The plenty hormonal, hemodynamic and mechanical changes occurred in pregnancy make women especially vulnerable to suffer from this condition in this period. Previous works have identified that CVD is associated with an increased inflammatory milieu and significant damage in maternofetal tissues, such as the umbilical cord. However, the inflammatory status of this structure in these patients has not been studied yet. Thus, the aim of the present study was to examine gene and protein expression of a set of inflammatory markers-Allograft inflammatory factor 1 (AIF-1), the proinflammatory cytokines interleukin 12A (IL-12A) and IL-18 and the anti-inflammatory product IL-10-in the umbilical cord of women with CVD during pregnancy (N = 62) and healthy pregnant women (HC; N = 52) by the use of real time qPCR and immunohistochemistry (IHC). Our results demonstrate that the umbilical cord tissue from CVD women exhibit an increased expression of AIF-1, IL-12A and IL-18 along with a decrease in IL-10. Therefore, our study suggests an inflammatory status of this structure related to CVD. Further studies should be conducted to evaluate the expression of other inflammatory markers, as well as to analyze the maternofetal impact of these findings.

The Update Immune-Regulatory Role of Pro- and Anti-Inflammatory Cytokines in Recurrent Pregnancy Losses

Recurrent pregnancy losses (RPL) is a common reproductive disorder with various underlying etiologies. In recent years, rapid progress has been made in exploring the immunological mechanisms for RPL. A propensity toward Th2 over Th1 and regulatory T (Treg) over Th17 immune responses may be advantageous for reproductive success. In women with RPL and animals prone to abortion, an inordinate expression of cytokines associated with implantation and early embryo development is present in the endometrium or decidua secreted from immune and non-immune cells. Hence, an adverse cytokine milieu at the maternal-fetal interface assaults immunological tolerance, leading to fetal rejection. Similar to T cells, NK cells can be categorized based on the characteristics of cytokines they secrete. Decidual NK (dNK) cells of RPL patients exhibited an increased NK1/NK2 ratio (IFN-γ/IL-4 producing NK cell ratios), leading to pro-inflammatory cytokine milieu and increased NK cell cytotoxicity. Genetic polymorphism may be the underlying etiologies for Th1 and Th17 propensity since it alters cytokine production. In addition, various hormones participate in cytokine regulations, including progesterone and estrogen, controlling cytokine balance in favor of the Th2 type. Consequently, the intricate regulation of cytokines and hormones may prevent the RPL of immune etiologies. Local or systemic administration of cytokines or their antagonists might help maintain adequate cytokine milieu, favoring Th2 over Th1 response or Treg over Th17 immune response in women with RPL. Herein, we provided an updated comprehensive review regarding the immune-regulatory role of pro- and anti-inflammatory cytokines in RPL. Understanding the roles of cytokines involved in RPL might significantly advance the early diagnosis, monitoring, and treatment of RPL.

Chromosomally normal miscarriage is associated with vaginal dysbiosis and local inflammation

BACKGROUND

Emerging evidence supports an association between vaginal microbiota composition and risk of miscarriage; however, the underlying mechanisms are poorly understood. We aim to investigate the vaginal microbial composition and the local immune response in chromosomally normal and abnormal miscarriages and compare this to uncomplicated pregnancies delivering at term.

METHODS

We used 16S rRNA gene based metataxonomics to interrogate the vaginal microbiota in a cohort of 167 women, 93 miscarriages (54 euploid and 39 aneuploid using molecular cytogenetics) and 74 women who delivered at term and correlate this with the aneuploidy status of the miscarriages. We also measured the concentrations of IL-2, IL-4, IL-6, IL-8, TNF-α, IFN-γ, IL-1β, IL-18 and IL-10 in cervical vaginal fluid.

RESULTS

We show that euploid miscarriage is associated with a significantly higher prevalence of Lactobacillus spp. deplete vaginal microbial communities compared to aneuploid miscarriage (P = 0.01). Integration of matched cervicovaginal fluid immune-profiles showed that Lactobacillus spp. depleted vaginal microbiota associated with pro-inflammatory cytokine levels most strongly in euploid miscarriage compared to viable term pregnancy (IL-1β; P < 0.001, IL-8; P = 0.01, IL-6; P < 0.001).

CONCLUSIONS

Our data suggest the vaginal microbiota plays an important aetiological role in euploid miscarriage and may represent a target to modify risk of pregnancy loss.

Association of Promoter Region Polymorphisms of IL-6 and IL-18 Genes with Risk of Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis

Background: The present meta-analysis was performed to investigate the association of promoter region polymorphisms at IL-6 and IL-18 genes with recurrent pregnancy loss (RPL) risk. Methods: An electronic search of the PubMed, Embase, ISI Web of Knowledge and CNKI databases was performed to identify eligible studies up to May 30, 2019. Results: A total of 31 case-control studies were finally selected. Significant associations with the risk of RPL were detected for the IL-6 -174 G > C, -634 G > C and IL-18 -137 G > C polymorphisms in overall population. Further, subgroup analyses by ethnicity revealed that the IL-6 -174 G > C and -634 G > C polymorphisms were significantly associated with risk of RPL risk in Asians. Conclusions: Our results suggest that the IL-6 -174 G > C, -634 G > C and IL-18 -137 G > C polymorphisms may contribute to the susceptibility of RPL. The IL-18 -607 C > A polymorphism does not appear to influence the development of RPL.

Association of IL-10, IL-18, and IL-33 genetic polymorphisms with recurrent pregnancy loss risk in Iranian women

Recurrent pregnancy loss (RPL) is a heterogeneous disease with three or more consecutive abortions before 20 weeks of pregnancy. Recently, inflammatory factors such as interleukins (IL) have been found to be a significant factor in the RPL. The objective of this study was to investigate the association between RPL and IL-10 (rs1800896), IL-18 (rs1946518) and IL-33 (rs1929992) genes polymorphisms in Iranian women. The study participants consisted of 300 women with RPL and the control group comprised of 300 healthy women with successful delivery. Genomic DNA was extracted from peripheral blood, and genotyping was performed by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP). There were no significant differences in the frequencies of genotype and allele in IL-10 gene polymorphism (rs1800896) between patients and control group (p > .005). In contrast, there were significant differences in the frequencies of CC genotype in IL-18 gene polymorphism (rs1946518) between patients and the control groups (p = .004; OR =0.990; 95% CI: 0.320-8.855). Also, there were significant differences in the frequencies of GA genotype in IL-33 gene polymorphism (rs1929992) between patients and the control groups (p = .001; OR =0.955; 95% CI: 0.239-9.807). Present study showed that the rs1800896 polymorphism (IL-10) might not play role in RPL in the Iranian population; whereas rs1946518 (IL-18) and rs1929992 (IL-33) polymorphisms may be associated with the risk of RPL in the Iranian women.

Association between Genetic Polymorphisms in Interleukin Genes and Recurrent Pregnancy Loss - A Systematic Review and Meta-Analysis

Interleukins are a group of immunomodulatory proteins that mediate a variety of immune reactions in the human body. To investigate the association between interleukin gene polymorphisms and recurrent pregnancy loss (RPL), we reviewed 21 studies from MEDLINE, EMBASE, OVID SP and PubMed to evaluate RPL-related interleukin gene polymorphisms. Meta-analysis was performed on 12 of the polymorphisms, and a review included the others. Our integrated results indicated that IL-1β (-511C/T) (P = 0.02, 95% CI 0.77[0.62,0.96]), IL-6 (-634C/G) (P<0.001, 95% CI 2.91[2.01,4.22]), IL-10 (-1082G/A, -819T/C) (P = 0.01, 95% CI 0.80[0.67,0.96]; P<0.01, 95% CI 0.66[0.49,0.89]), and IL-18 (-137G/C, -105G/A) (P<0.01, 95% CI 1.69[1.24,2.31]; P = <0.01, 95% CI 1.41[1.17,1.70]) consistently associated with RPL after meta-analysis. IL-17A rs2275913 and IL-17F rs763780, IL-21 rs2055979 and rs13143866, IL-1β (-31C/T), IL-6 (-2954G/C), and IL-10 (-536A/G) were reported only once as having a significant association with RPL. The potential mechanism underlying miscarriage and these polymorphisms and future research directions are also discussed.

A gene-disease association study of IL18 in thyroid cancer: genotype and haplotype analyses

Thyroid cancer is the most common malignancy of the endocrine system, and genetic factors have been shown to be associated with its risk. Interleukin-18 (IL-18) is a pleiotropic pro-inflammatory cytokine that induces IFN-γ production and is involved in T helper type 1 development. To determine the role of IL-18 gene in thyroid cancer susceptibility, we conducted a case-control study, and genotyped five single nucleotide polymorphisms (SNPs) in IL-18 gene (-656 G/T (rs1946519), -607 C/A (rs1946518), and -137 G/C (rs187238) in the promoter region and +113 T/G (rs360718) and +127 C/T (rs360717) in 5'-untranslated region) in 105 patients with thyroid cancer and 148 healthy controls from Iranian population. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific primer-PCR were used for genotyping. The association of different genotypes with thyroid cancer, tumor type, and the tumor stage was analyzed. Comparing all of the patient population with the controls, TT genotype at position -656 G/T was observed to be associated with a significantly increased risk of thyroid cancer [31/105 (30.1 %) vs 19/148 (13.1 %), p = 0.002, OR 2.90, CI 1.40-5.70]. No association with thyroid cancer was found at other positions (-607 C/A, -137 G/C, +113 T/G, and +127 C/T). Excluding the patients with medullary carcinoma, and including only the ones with thyroid cancer derived from the follicular epithelium, nearly the same results were observed regarding the genotypes at position -656 G/T. Furthermore, significantly decreased risk of thyroid cancer derived from the follicular epithelium was observed upon inheritance of the homozygote genotype (CC) at position +127 C/T (40/94 (42.5 %) versus 84/148 (56.8 %) in patients and controls, respectively (OR 0.56, 95 % CI for OR 0.32-0.98, p = 0.04). Haplotype analysis indicated that among 32 possible haplotypes, TAGTT haplotype frequency was significantly higher in patients than in controls [12/188 (6.4 %) vs 2/292 (0.7 %), p = 0.0008] and this difference resisted Bonferroni correction (n = 19) and significant level set at 0.003. Nearly the same results were observed after excluding the patients with medullary carcinoma. No association was found between the SNPs and the stage of tumor. Our results suggest the increased susceptibility to thyroid cancer in subjects with TT genotype at position -656 G/T of the promoter of IL-18 gene, as well as TAGTT haplotype emerged from five studied SNPs in IL-18 gene. The data also suggest that the inheritance of +127 CC genotype may protect individuals from thyroid cancer derived from follicular epithelium.

Interleukin-18 gene polymorphisms and risk of recurrent pregnancy loss: A systematic review and meta-analysis

Interleukin-18 (IL-18) plays a potential pathological role in recurrent pregnancy loss (RPL). The results of published studies on the relationship between IL-18 gene promoter polymorphisms (-137G/C and-607C/A) and RPL risk remain controversial. This meta-analysis was performed to evaluate the association of IL-18, -137G/C and-607C/A gene polymorphisms with the risk of RPL under recessive, dominant and additive genetic models. A literature search was conducted in Medline, Embase and Web of Science for studies that described the effect of IL-18 gene polymorphisms on RPL risk. The numbers of each -137G/C and-607C/A genotype in the case and control groups were extracted. Quality of the original studies' methodology was also assessed. Meta-analysis was performed using Stata 13.1 software and the fixed effect model was used. Five articles were included in this meta-analysis. No significant heterogeneity between the studies was noted. The IL-18 -137 G/C polymorphism was significantly associated with an increased risk of RPL under a recessive genetic model (CC vs. GG + CG: odds ratio = 1.56, 95% confidence interval = 1.13 ~ 2.15). For the -607C/A mutation, we failed to find any association under any genetic models. The Egger's regression asymmetry test showed no publication bias. Our present study indicates a positive association between the CC genotype of the IL-18 -137G/C gene and RPL risk. Future well-designed large studies are needed to validate the association between IL-18 gene polymorphisms and the risk of RPL.

Genetic variant in interleukin-18 is associated with idiopathic recurrent miscarriage in Chinese Han population

Levels of IL-18 were significantly lower in women with recurrent miscarriage (RM) than those without idiopathic RM. IL-18 promoter single nucleotide polymorphisms were previously identified to have an impact on IL18 gene transcription activity and influence the level of IL-18 protein production. The aim of this study was to evaluate whether IL-18 gene polymorphisms are risk factors for idiopathic RM in Chinese Han population. Study subjects comprised of 484 idiopathic RM patients and 468 controls. Three polymorphisms (rs360717, rs187238, rs1946518) in IL-18 gene and serum IL-18 concentrations were assessed. rs187238 variant exhibits significant association with RM in additive and recessive genetic model (additive model p = 1.05 × 10⁻⁴, dominant model p = 0.025, recessive model p = 2.43 × 10⁻⁵). In contrast, rs360717 and rs1946518 are not significantly associated with RM. Serum IL-18 levels are significantly lower in RM cases than in control (111.98 ± 93.13 versus 148.74 ± 130.51 pg/mL, p = 7.42 × 10⁻⁷). There are lower levels of serum IL-18 in rs187238 homozygous mutant (CC) than homozygous wild-type (GG) in this study population, including cases and control groups (98.31 ± 86.46 versus 131.87 ± 115.02 pg/mL, p = 0.015). These results suggest that reduced IL-18 levels and rs187238 variant may contribute to pathogenesis of idiopathic RM in Chinese Han population.

IL-18 gene polymorphism in patients with visceral leishmaniasis in East Azarbaijan, Iran

Visceral leishmaniasis (VL) is a parasitic disease caused by Leishmania species. According to the important role of cellular immunity against VL, this study was directed to determine the frequency of -607A/C and -137G/C genotypes on promoter region of interleukin-18 gene. The study groups included 91 patients with confirmed history of VL, 106 healthy seronegative, and 79 healthy seropositive individuals. All three groups were analyzed by amplification refractory mutation system polymerase chain reaction (ARMS-PCR). The highest rate of -607/A, and -607/C alleles was observed in seronegative individuals (66/67 %) and in the patients (72/83 %). Allele frequency of -607/C is more than -607/A allele in all groups. In position of -137, frequency of -137/G allele in all groups was more than -137/C. Statistical analysis of distribution of genotypes, did not reveal any significant difference among groups. On the basis of the results, there was no significant association between VL and polymorphism of IL-18 promoter. The results of this study showed that IL-18 gene promoter polymorphisms at positions -607 and -137 are not associated with VL in East Azerbaijan, Iran.

Interleukin-18, interleukin-8, and CXCR2 and the risk of silicosis

Molecular mechanisms in the pathogenesis of silicosis are not fully understood. Exposure to crystalline silica leads to the activation of signaling pathways controlling the production and secretion of inflammatory mediators. Inflammatory cytokines are noted as important candidate genes for fibrotic lung diseases. Cytokines, chemokines, and variations of their genes have been associated with upregulation or downregulation of chronic inflammatory mediators. Variations in the interleukin (IL)-18, IL-8 and chemokine receptor CXCR2 genes are believed to influence the risk of silicosis in stone-grinding factory workers in Iran. Allele-specific oligonucleotide polymerase chain reaction (PCR) procedure was carried out for IL-18 −137 and IL-18 −607, meanwhile touchdown PCR was performed for IL-8 −251 and CXCR2 +1208 genotyping. Variation in genotypic and allelic frequencies was not statistically different among cases versus controls ( p > 0.05). These findings indicated for the first time that IL-18 −137, IL-18 −607, IL-8 −251, and CXCR2 +1208 are suggested not to influence the risk of silicosis in tested occupational group.

Genetics of recurrent miscarriage: challenges, current knowledge, future directions

Recurrent miscarriage (RM) occurs in 1-3% of couples aiming at childbirth. Due to multifactorial etiology the clinical diagnosis of RM varies. The design of genetic/"omics" studies to identify genes and biological mechanisms involved in pathogenesis of RM has challenges as there are several options in defining the study subjects (female patient and/or couple with miscarriages, fetus/placenta) and controls. An ideal study would attempt a trio-design focusing on both partners as well as pregnancies of the couple. Application of genetic association studies focusing on pre-selected candidate genes with potential pathological effect in RM show limitations. Polymorphisms in ∼100 genes have been investigated and association with RM is often inconclusive or negative. Also, implication of prognostic molecular diagnostic tests in clinical practice exhibits uncertainties. Future directions in investigating biomolecular risk factors for RM rely on integrating alternative approaches (SNPs, copy number variations, gene/protein expression, epigenetic regulation) in studies of single genes as well as whole-genome analysis. This would be enhanced by collaborative network between research centers and RM clinics.

Interleukin-18 promoter polymorphisms and risk of idiopathic recurrent pregnancy loss in a Tunisian population

IL-18 is a pro-inflammatory cytokine that regulates the differentiation and effector functions of CD4+ (Th1) and CD8+ (CTL) T cells, which are implicated in the pathogenesis of recurrent pregnancy loss (RPL). We investigated the association of the IL-18 gene promoter single nucleotide polymorphisms (SNPs) -656C/A (rs1946519), -137G/C (rs187238), -119A/C (rs360718), and -105G/A (rs360717), by TaqMan assays in analysis in 470 Tunisian women comprising 235 RPL cases and 235 multi-parous controls. The association of IL-18 alleles, genotypes, and haplotypes with RPL was evaluated by Fisher's exact test and regression analysis. The frequency of minor alleles -105G/A (P<0.001) and -656C/A (P<0.001), but not -119A/C (P=0.93) or -137G/C (P=0.32), were higher in RPL cases. Significant differences were also noted in the genotype distribution of -105G/A (P<0.001) and -656C/A (P<0.001) between cases and controls. Four-locus (-656C/A, -137G/C, -119A/C, -105G/A) IL-18 haplotype analysis identified AGAA (corrected P<0.001), and CGAA (corrected P<0.001) haplotypes to be associated with increased RPL risk, after adjusting for age and BMI. These results demonstrate that -105G/A and -656C/A IL-18 variants are significantly associated with RPL.

Expression and localization of IL-18 in the hypothalamic-pituitary-ovarian axis of non-pregnant, pregnant, and abortive rats

Cytokines present in the reproductive system play an important role both in the modulation of immune responses to infectious challenge and in the establishment and maintenance of pregnancy. Interleukin 18 (IL-18) has been regarded as an important regulator of innate and acquired immune response, but its expression and distribution in the hypothalamic-pituitary-ovarian axis remain unclear. In this paper, the expression and distribution of IL-18 in non-pregnant, pregnant, and early abortive rats were examined using an ultra-sensitive immunohistochemical streptavidin-peroxidase method, enzyme-linked immunosorbent assay, and reverse transcription-polymerase chain reaction. The results showed that IL-18 expression in the pituitary, in follicular ovaries, and in the corpus luteum of abortive rats were significantly lower than that of pregnant and non-pregnant rats. However, the staining of IL-18 in the hypothalamus, interstitial glands of the ovary, and uterus of abortive rats was strikingly stronger than those of the non-pregnant ones. IL-18 mRNA expression in rat uterus was detected in all groups, whereas IL-18 mRNA content in abortive rat uterus was significantly higher than in normal pregnant rats. Further, IL-18 in the peripheral blood serum of abortive rats was significantly lower than in same-period normal pregnant rats. The differential expression of IL-18 in early abortion suggests that IL-18 may be related to the underlying mechanisms of abortion.

Analysis of interleukin-18 promoter polymorphisms and changes in interleukin-18 serum levels underscores the involvement of interleukin-18 in recurrent spontaneous miscarriage

OBJECTIVE

To evaluate the association of interleukin-18 (IL-18) promoter single-nucleotide polymorphisms rs1946519 (-656C/A), rs187238 (-137G/C), rs360718 (-119A/C), and rs360717 (-105G/A) and changes in IL-18 serum levels with recurrent spontaneous miscarriage (RSM).

DESIGN

Case-control study.

SETTING

Outpatient obstetrics and gynecology clinics.

PATIENT(S)

Women with confirmed RSM (n = 282), and 283 age- and ethnically matched controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

IL-18 genotyping was accomplished by allelic discrimination assays; serum IL-18 levels were measured by ELISA.

RESULT(S)

The minor allele frequencies of rs360717 and rs1946519, but not rs360718 or rs187238, were higher in patients with RSM. Significant differences in the distribution of the rs360717 and rs1946519 genotypes were noted between patients and controls, and both rs360717 and rs1946519 IL-18 single-nucleotide polymorphisms showed significant association with RSM under additive, dominant, and recessive models. Lower serum IL-18 levels were seen between patients and controls and were more pronounced in rs360717 and rs1946519 heterozygous and homozygous genotypes. Four-locus (rs1946519/rs187238/rs360718/rs360717) IL-18 haplotype analysis identified that the AGAA (Pc<.001), CGAA (Pc<.001), and ACAG (Pc=.018) haplotypes were associated with a reduction in IL-18 secretion and with increased RSM risk, after adjustments for body mass index, menarche, and gravida.

CONCLUSION(S)

These results demonstrated that reduced IL-18 levels and rs360717 and rs1946519 IL-18 variants are significantly associated with RSM.

Polymorphisms in the interleukin-12/18 genes and recurrent spontaneous abortion

PROBLEM

Interleukin (IL) IL-12/IL-18 are involved in uterine NK cells control of uterine vascular development. Polymorphisms in the IL-12/IL-18 genes could modify the cytokine balance, which might result in an increased susceptibility to recurrent spontaneous abortion (RSA).

METHOD OF STUDY

A case-control study was conducted to determine the association between the IL12 (I/D) and IL18 (-607C>A, -137G>C) gene polymorphisms and the risk of RSA in 125 women with RSA and in 136 controls.

RESULTS

The frequencies of DD, ID, II for IL-12 were, 25.6%, 52.8% and 21.6% respectively, in patients versus 21.3%, 51.5% and 27.2% respectively in controls; the frequencies of CC, CA, AA genotypes for IL-18 (-607) were, 34.4%, 54.4% and 11.2% respectively in patients versus 30.1%, 58.1% and 11.8% respectively in controls; the frequencies of GG, GC, CC genotypes for IL-18(-137) were 47.2%, 43.2% and 9.6% respectively in patients and 45.6%, 46.3% and 8.1% respectively in controls.

CONCLUSION

IL-12B and IL-18 promoter gene polymorphisms were not associated with RSA in our women.