IL-1 receptor antagonist gene polymorphism in recurrent spontaneous abortion

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.

Association of of IL-1 receptor antagonist (IL-1RN) and interleukin-1β genes (IL-1β) polymorphisms with recurrent pregnancy loss in Iranian Azeri women

Objective One of the most important problems in human reproduction is recurrent pregnancy loss (RPL). RPL is defined as three or more consecutive abortions in the first trimester of pregnancy. The association between the polymorphisms in the immunological factors and RPL was investigated. The aim of our study was to determine the association of interleukin receptor antagonist (IL-IRN) and interleukin-1β (IL-1β) polymorphisms with RPL in Iranian Azeri women. Materials and methods The study participants consisted of 100 women with RPL of Iranian Azeri origin. The control group comprised 100 age- and ethnically-matched healthy women of the same reproductive age. Genomic DNA was extracted from the whole blood and genotype determinations were performed using polymerase chain reaction (PCR) amplification followed by restriction fragment length polymorphism (RFLP) analysis. Results Our results showed no significant relationship between IL-1RN polymorphism and RPL. The homozygous state in -857 C/T variant was seen to be higher in RPL patients than in control subjects. Also frequency of wild type genotype was lower in RPL patients than in controls. However, this associations was not significant. Conclusion This study suggested that -511 C/T (rs16944) and -31 C/T (rs1143627) polymorphisms in IL-1β gene may not be involved in RPL in Iranian Azeri women. Also the promoter polymorphism of the IL-1RN gene may not play a role in the susceptibility to RPL.

Effects of interleukin-1 receptor antagonist (IL-1Ra) gene 86 bp VNTR polymorphism on recurrent pregnancy loss: a case-control study

Objective

Recurrent pregnancy loss (RPL) is a heterogeneous disease which is defined as two or more consecutive fetal losses during early pregnancy. Interleukin-1 receptor antagonist (

Materials and methods

In this case control study, genetic polymorphism was studied in 140 RPL patients and 140 healthy women as controls. Genomic DNA was extracted from the blood samples and polymorphism analysis was performed using the polymerase chain reaction (PCR) method. Finally, the data obtained were analyzed by statistical software.

Results

We found an increased frequency of the IL-1Ra 1/1 genotype in the case group compared to the control group. Whereas, the frequency of IL-1Ra genotype 1/2 was higher in control group than in the case group. However, we did not observe an association between

Conclusion

VNTR polymorphism may not be a genetic factor for RPL. However, investigation of

Association of interleukin 1 receptor antagonist (IL1RN) gene polymorphism with recurrent pregnancy loss risk in the North Indian Population and a meta-analysis

An appropriate ratio of interleukin 1 beta to interleukin 1 receptor antagonist (IL1Ra) is required for successful pregnancy. Our objective was to study the genetic association between IL1RN variable numbers of tandem repeat (VNTR) polymorphism and recurrent pregnancy loss (RPL). To analyze the association between IL1RN VNTR allele and RPL, we investigated the IL1RN VNTR polymorphism in 136 RPL patients and in 200 healthy control women. Meta-analysis on this polymorphism was conducted to support our findings. PCR based approach was used to analyze IL1RN VNTR polymorphism and it was further confirmed by sequencing. Systematic review and meta-analysis was done using electronic database (Pub-Med, Google Scholar and Ovid) up to February 27, 2013. This meta-analysis was assessed by comprehensive meta-analysis software version 2. For meta-analysis 549 cases and 1,450 controls were included. The frequency of IL1RN genotype 2/2 was significantly higher in RPL compared to control group (AORs 3.10, 95 % CI 1.58-6.11, p = 0.001). The presence of rare allele also increased the risk of RPL significantly (ORs 1.63, 95 % CI 1.16-2.29, p = 0.004). The meta-analysis stratified by ethnicity showed that individuals with allele 2 had increased risk of RPL (OR 1.29, 95 % CI 1.04-1.61, p = 0.01), in Asians population by using fixed model. However the data of the present study clearly suggests that IL1RN VNTR polymorphism is a genetic risk factor for pregnancy loss in the study population.

Does L-arginine availability during the early pregnancy alters the immune response of Trypanosoma cruzi infected and pregnant Wistar rats?

Chagas disease induces a strong immune response and L-arginine is an essential amino acid which plays an important role in homeostasis of the immune system. The aims of this study were to evaluate parasitemia, corticosterone levels, production of nitric oxide (NO), fetal morphological measurements, and histology of heart and placenta. Twenty pregnant Wistar rats (180-220 g) were grouped in: pregnant control (PC), pregnant control and L-arginine supplied (PCA), pregnant infected (PI), pregnant infected and L-arginine supplied (PIA). Females were infected with 1×10(5) trypomastigotes of the Y strain (3rd day of pregnancy). Animals were supplied with 21 mg of L-arginine/kg/day during 14 days. PIA showed significant decreased levels of corticosterone and parasitemia. For control groups, any alteration in NO production was found with L-arginine supplementation; for PIA, enhanced nitrite concentrations were observed as compared to PI. Weights and lengths of fetuses were higher in L-arginine treated and infected pregnant rats as compared to untreated ones. Placental weight from the PIA group was significantly increased when compared to PI. In L-arginine treated animals, cardiac tissue showed reduced amastigote burdens. PIA and PI displayed similar placental parasitism. Based on these results, L-arginine supplementation may be potentially useful for the protection against Trypanosoma cruzi during pregnancy.

Interleukin-1 gene cluster variants and recurrent pregnancy loss among North Indian women: retrospective study and meta-analysis

The aim of this study was to determine whether or not interleukin-1 alpha (IL-1a), interleukin-1 beta (IL-1b) and IL-1 receptor antagonist (IL-1RA) polymorphisms are associated with risk of unexplained recurrent pregnancy loss (RPL) among North Indian women. This retrospective case–control study examine 200 well-characterized RPL cases for IL-1 gene cluster variants, determined by restriction fragment length polymorphism-PCR. The observed allele, genotype and haplotype distributions were compared with those obtained from 300 ethnically matched negative controls. Invariant distribution of IL-1 gene cluster single-nucleotide polymorphisms was observed among RPL cases and controls. Meta-analysis of IL-1b _511, +3953 and IL-1RN 86-bp variable number tandem repeat from the reported literature and this study did not reveal any significant association with the risk of RPL. In conclusion, no significant difference between RPL and control groups was observed at the allele, genotype or haplotype levels when tested for association using the dominant, recessive and additive models of inheritance for IL-1 gene cluster variants. As far as is known, this is the first report from India pertaining to IL-1 gene cluster variants’ association with the risk of RPL from North India.

Polymorphisms in VEGF, progesterone receptor and IL-1 receptor genes in women with recurrent spontaneous abortion

Hormonal, inflammatory and vascular alterations during pregnancy are thought to be involved in pregnancy loss. The role of progesterone, the actions of which involve cytokines and vascular endothelial growth factor (VEGF), has been thoroughly studied. Genetic factors are involved in modulation of these molecules, and several genes have been associated with recurrent spontaneous abortion (RSA), as well other obstetric conditions. Here we investigate the relationship between RSA and gene polymorphisms of the progesterone receptor (PROGINS), interleukin-1 receptor 1 (PstI) and vascular endothelial growth factor (VEGF) (-634, 936). This case-controlled study comprised a total of 89 women with idiopathic RSA and a control group of 191 women with at least two successful pregnancies and no miscarriages. Genomic DNA was extracted from whole blood, and polymorphism genotyping was conducted by digesting PCR products with specific restriction endonucleases. No correlations were found in any of the investigated polymorphisms, even among dominant, co-dominant and additive inheritance models and alleles. Our results support the hypothesis that these specific gene polymorphisms are not the major determinant of pregnancy success. Although we did not find any correlations, the investigation of these and other polymorphisms remains a challenge in the evaluation of RSA.

Polymorphisms in estrogen metabolism and estrogen pathway genes and the risk of miscarriage

PURPOSE

This study investigated genetic variations in the estrogen pathway and their association with miscarriages.

METHODS

A total of 483 patients were recruited from a comprehensive control group for case-control studies. Three variants of the CYP19A1 gene (rs10046, rs4646 and rs700519) and one variant each of the estrogen (ESR1) and progesterone (PGR) receptor genes (rs3020314 and rs1042838) were investigated using polymorphism genotyping. The chi-squared test and one-way analysis of variation (ANOVA) were used for statistical analysis.

RESULTS

For rs10046 (CYP19A1), the C/C genotype was associated with a greater frequency of miscarriages (P = 0.017). The other genotypes were not found to be associated with recurrent miscarriage.

CONCLUSIONS

This is the first study that has identified a single-nucleotide polymorphism in the aromatase gene that suggests a significant association between genotypes and miscarriage. As aromatase is an essential enzyme in the estrogen pathway, it may be speculated that variations in the aromatase gene in some way give rise to different conditions in the endocrine environment that can lead to impaired fertility.

Polymorphism of the interleukin 1 receptor antagonist (IL1Ra) gene and placental abruption

Candidate genes with a possible involvement in placental abruption are mainly those related to thrombophilia and preeclampsia. Some reports have shown by placental histologic investigation that increased risk of placental abruption is associated with prolonged inflammation. The polymorphic allele A2 in the gene coding for interleukin 1 receptor antagonist (IL1Ra) has been associated in various diseases of autoimmune or inflammatory nature. In obstetrics, previous research data has linked altered IL1Ra protein production with placental pathology and some severe pregnancy complications. In this study, we have determined whether IL1Ra gene polymorphism is associated also with an increased risk of placental abruption. The study involved 116 women with placental abruption and 112 healthy control pregnant women who were genotyped for polymorphism of the IL1Ra gene. The genotype and allele frequencies were assessed between the two groups and also compared with those in the general population. The frequency of the A2 allele was 28.0% among cases and 33.0% in controls (p=0.29), both similar to that in the general population (28.9%). In addition, the genotype distribution of IL1Ra polymorphisms was similar in both groups. Interestingly, there were a relatively higher number of cases with allele A3 (n=4; 1.7%) compared with the controls (0.4%) and the general population (1.0%) but the difference was not statistically significant. We conclude that there is no significant difference in IL1Ra polymorphisms between patients with and without placental abruption.

Cytokine gene polymorphisms in recurrent spontaneous abortions: a comprehensive review

PROBLEM

Cytokine gene polymorphism studies in women with recurrent spontaneous abortion (RSA) are reviewed to provide comprehensive understanding and a direction for the future investigation.

METHOD OF STUDY

A search of PubMed was made to identify the published data between 2001 and 2007 regarding RSA and cytokine gene polymorphisms.

RESULTS

Either allele and/or genotype frequencies of the following polymorphisms were reported to be significantly different between women with RSA and controls: IFN-gamma +874A-->T, TA (P = 0.01), AA (P = 0.04); IL-6, -634C-->G CG/GG (P = 0.026); IL-10, -592C-->A CC (P = 0.016); IL-1B -511C (P = 0.035), -31T (P = 0.029); IL-1RA, IL1RN*2 (P = 0.002), and IL1RN*3 (P = 0.002). None of these studies was repeatedly reported by others to be significantly different. Among these, four cytokine polymorphisms (IFN-gamma, +874A-->T; IL-1B -511C; IL-1RA, IL1RN*2, IL1RN*3) were refuted by others and rest of them were studied once.

CONCLUSION

Multiple cytokine polymorphisms were reported to be associated with RSA. However, a majority of studies were not confirmed by other investigators or refuted by others. Inconsistent study results might be related to: (i) the production of these cytokines is partly under genetic controls and other factors affect cytokine levels; (ii) ethnic background, environmental factors, and selection criteria for study populations are different and (iii) the possibilities exist that multiple cytokine gene polymorphisms or other genes in linkage disequilibrium may play a role in RSA.

The different expression patterns of interleukin-1 receptor antagonist in systemic lupus erythematosus

The interleukin-1 receptor antagonist (IL1RN or IL-1Ra) is a natural antagonist of IL-1-beta. Using IL1RN as a possible marker in patients with systemic lupus erythematosus (SLE), we evaluated whether uIL1RN single nucleotide polymorphisms (SNPs) were associated with the pathogenesis of SLE in Taiwanese, and specifically whether IL1RN (rs315952) was significantly associated with end-stage renal disease. We examined IL1RN isoform expression patterns in patients with SLE to determine whether the expressions play a role in the pathogenesis of SLE. Both case-control and family-based association studies were used. For the case-control study, 104 patients with SLE and 97 normal controls were recruited, and for the family-based study, 11 families with SLE without renal disorder were recruited from the 104 patients with SLE. Eight IL1RN SNPs (rs2234678, rs2234679, rs315951, rs315952, rs419598, rs432014, rs447713, and rs451578) were selected for the family-based study. Reverse-transcriptase-polymerase chain reaction (RT-PCR) was used to determine the expression pattern of each isoform. Our results showed that IL1RN (rs315952) was significantly associated with SLE in patients without renal disorder in the family-based study, after disease stratification, but was not significantly associated with SLE in the case-control study. In the family-based study, the haplotype of IL1RN (AGCCTTAG) was significantly associated with SLE (chi2 = 11.714, P < 0.001). Using RT-PCR to determine the expression pattern of the IL1RN isoforms, we found different expression patterns between normal controls and patients with SLE, with an addition of IL1RN isoform4 or the low expression of IL1RN isoform1. We concluded that IL1RN and its isoforms were involved in the pathogenesis of SLE.

Genetic association of interleukin-1β (−511C/T) and interleukin-1 receptor antagonist (86 bp repeat) polymorphisms with Type 2 diabetes mellitus in North Indians

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with a subclinical systemic inflammation and development of complications like nephropathy, retinopathy, neuropathy and hypertension. We studied the genetic association of bi-allelic polymorphism (-511C/T) of interleukin (IL)-1beta and 86 bp variable number tandem repeat (VNTR) polymorphism of natural receptor antagonist (IL-1RN) with T2DM and associated complications in North Indians.

METHODS

We genotyped 200 patients with T2DM and 223 healthy control subjects for IL-1beta (-511C/T) by PCR-RFLP. Genotyping of IL-1RN (VNTR) polymorphism was determined by gel electrophoresis after PCR amplification.

RESULTS

Interleukin-1beta (-511C/T) and IL-1RN (VNTR) polymorphisms were significantly associated with T2DM. IL-1beta -511T, IL-1RN*2 and IL-1RN*3 alleles were associated with high risk of T2DM whereas; individuals with IL-1beta -511C and IL-1RN*1 alleles were at low risk. Haplotype frequency analysis showed that T2 (IL-1beta -511T/IL-1RN*2) haplotype was associated with the high risk (p=0.000; OR=2.4, 95% CI 1.68-3.34) and C1 (IL-1beta -511C/IL-1RN*1) haplotype showed low risk (p=0.000; OR=0.38, 95% CI 0.27-0.53). Further, CT, TT genotypes of IL-1beta (-511C/T) and 1/2 genotype of IL-1RN (VNTR) were found to be associated with risk of complications particularly with nephropathy in T2DM.

CONCLUSION

The IL-1beta (-511C/T) and IL-1RN (VNTR) polymorphisms are significantly associated with increased risk of T2DM as well as associated complications in North Indians.

Pregnancy-associated plasma protein-A polymorphism and the risk of recurrent pregnancy loss

Pregnancy-associated plasma protein-A (PAPP-A)/insulin-like growth factor-binding protein-4 (IGFBP4) protease is a member of the metzincin family of metalloproteases, known as a sensitive biomarker of adverse pregnancy outcomes. Recently, a missense A/C (Tyr/Ser) polymorphism (dbSNP: rs7020782) in the PAPPA gene has been reported. To examine the association between recurrent pregnancy loss (RPL) and this polymorphism, a case-control study of 215 cases with two or more pregnancy losses (PLs) and 420 fertile controls was performed. Genotyping of the PAPPA polymorphism was determined by allelic discrimination using fluorogenic probes and the 5' nuclease assay. Sixty-nine cases (32.1%) were heterozygous and 11 cases (5.1%) were homozygous for the C allele of PAPPA; the respective figures were 127 (30.2%) and 11 (2.6%) in the controls. Women carrying the C allele had a tendency to increased risk of RPL (AA genotype [reference]; AC genotype: odds ratio [OR], 1.17; 95% confidence interval [CI], 0.82-1.68; CC genotype: OR, 2.06; 95% CI, 0.87-4.90), but it was not significant. Women with three or more PLs had a similar tendency (AA genotype [reference]; AC genotype: OR, 1.04; 95% CI, 0.66-1.64; CC genotype: OR, 2.20; 95% CI, 0.82-5.91). The risk of RPL with at least one PL after 9 weeks' gestation significantly increased in women carrying the C allele (AA genotype [reference]; AC genotype: OR, 1.54; 95% CI, 0.95-2.49; CC genotype: OR, 2.83; 95% CI, 1.00-8.05; AC+CC genotypes: OR, 1.65; CI, 1.04-2.62). This is the first report on the PAPPA gene polymorphism in women with RPL, demonstrating some association between the investigated polymorphism and the risk of RPL.

Interleukin-1 receptor antagonist and interleukin-1 beta polymorphisms in women with recurrent miscarriage

Genotypes and allele distributions for the interleukin (IL)-1beta -511 C/T and the IL-1 receptor antagonist gene intron 2 tandem repeat polymorphisms were compared in 206 women with recurrent miscarriage and a control population. No significant differences were observed between the distributions of IL-1beta or IL-1 receptor antagonist gene alleles in either the recurrent miscarriage group as a whole or when divided according to the cause of recurrent miscarriage compared with controls, which suggests that variation in the IL-1 receptor antagonist gene and IL-1beta genes individually does not play a role in susceptibility to recurrent miscarriage.

Maternal CD46H*2 and IL1B-511*1 homozygosity in T helper 1-type immunity to trophoblast antigens in recurrent pregnancy loss

BACKGROUND

Women with recurrent pregnancy loss (RPL) and T-helper (Th)1-type immunity to trophoblast antigens have an increased frequency of the IL1B-511*1 promoter variant. Since CD46 gene products also regulate maternal immune responses including Th1 immunity, we investigated whether CD46 gene polymorphisms are also associated with RPL in women with and without Th1 immunity to trophoblast, and the possibility of a synergistic effect with the IL1B-511*1 promoter variant.

METHODS

A case-controlled study was performed to document HindIII site polymorphism in intron 1 of the CD46 gene in 131 women with RPL and 72 fertile controls. Clinical information, Th1-type immune responsiveness to trophoblast in women with RPL history, and IL1B promoter allelotypes for this cohort were documented in a previous study.

RESULTS

The frequency of the CD46H*2 allele and CD46H*2 homozygosity were significantly increased in women with RPL compared with fertile controls (P<0.028 and P<0.011). CD46H*2 homozygosity was highly associated with RPL-Th1(+) (32.4 versus 9.7% in fertile controls, P<0.0045). Logistic regression analysis revealed that women homozygous for both the IL1B-511*1 and CD46H*2 alleles had an extremely high risk of RPL-Th1(+) [exponential coefficients (EC)=24]. Among women with RPL, homozygosity at both alleles, but not each alone, significantly increased the risk of Th1 immunity to trophoblast antigens (EC=16), suggesting a possible genetic interaction between these two alleles in the development of Th1 immunity.

CONCLUSIONS

The combination of homozygosity for both IL1B-511*1 and CD46H*2 alleles is a high risk factor for RPL-Th1(+).

Caffeine intake, CYP1A2 polymorphism and the risk of recurrent pregnancy loss

Some case-control studies have demonstrated that caffeine intake and high CYP1A2 activity increase risks of recurrent pregnancy loss (RPL) but the multifactorial effect is obscure. To investigate whether susceptible women who have more caffeine intake are at high risk of RPL, a case-control study of 58 cases with two or more RPL and fertile 147 controls was performed. The association between daily caffeine intake together with CYP1A21F (AA versus CA and CC) genotype and RPL was assessed. Without consideration of the genotype, there were no significant differences of the RPL risk in proportion to daily caffeine intake [less than 100 mg (reference); 100-299 mg: odds ratio (OR), 1.29; 95% confidence interval (CI), 0.66-2.50; 300 mg or more: OR, 1.82; 95% CI, 0.72-4.58; P for trend, 0.20]. However, the RPL risk significantly increased only among women who had homozygous CYP1A21F alleles with a dosage effect of daily caffeine intake [less than 100 mg (reference); 100-299 mg: OR, 1.94; 95% CI, 0.57-6.66; 300 mg or more: OR, 5.23; 95% CI, 1.05-25.9; P for trend, 0.03]. It was demonstrated for the first time that an increase in caffeine intake deteriorates the fecundity among susceptible women.

Ah receptor, CYP1A1, CYP1A2 and CYP1B1 gene polymorphisms are not involved in the risk of recurrent pregnancy loss

The etiology of recurrent pregnancy loss (RPL) remains unclear, but it may be related to a possible genetic predisposition together with involvement of environmental factors. We examined the relation between RPL and polymorphisms in four genes, human aryl hydrocarbon (Ah) receptor, cytochrome P450 (CYP) 1A1, CYP1A2 and CYP1B1, which are involved in the metabolism of a wide range of environmental toxins and carcinogens. All cases and controls were women resident in Sapporo, Japan and the surrounding area. The Ah receptor, CYP1A1, CYP1A2 and CYP1B1 genotypes were assessed in 113 Japanese women with recurrent pregnancy loss (RPL) and 203 ethnically matched women experiencing at least one live birth and no spontaneous abortion (control). No significant differences in Ah receptor, CYP1A1, CYP1A2 and CYP1B1 genotype frequencies were found between the women with RPL and the controls [Ah receptor: Arg/Arg (reference); Arg/Lys and Lys/Lys, odds ratio (OR)=0.67; 95% confidence interval (CI)=0.40-1.11, CYP1A1: m1m1 (reference); m1m2 and m2m2, OR = 0.86; 95% CI = 0.53-1.40, CYP1A2: C/C and C/A (reference); A/A, OR = 1.16; 95% CI = 0.71-1.88, CYP1B1: Leu/Leu (reference); Leu/Val and Val/Val, OR = 1.18; 95% CI = 0.68-2.02]. The present study suggests that the Ah receptor, CYP1A1, CYP1A2 and CYP1B1 gene polymorphisms are not major genetic regulators in RPL.