The Role of Interleukins in Recurrent Implantation Failure: A Comprehensive Review of the Literature

Recurrent implantation failure (RIF) is a multifactorial condition affecting 10-15% of in vitro fertilization (IVF) couples. Data suggest that functional dysregulation of the endometrial immune system constitutes one of the main pathophysiological mechanisms leading to RIF. The aim of this article is to provide a thorough presentation and evaluation of the role of interleukins (ILs) in the pathogenesis of RIF. A comprehensive literature screening was performed summarizing current evidence. During implantation, several classes of ILs are secreted by epithelial and stromal endometrial cells, including IL-6, IL-10, IL-12, IL-15, IL-18, and the leukemia inhibitory factor. These ILs create a perplexing network that orchestrates both proliferation and maturation of uterine natural killer cells, controls the function of regulatory T and B cells inhibiting the secretion of antifetal antibodies, and supports trophoblast invasion and decidua formation. The existing data indicate associations between ILs and RIF. The extensive analysis performed herein concludes that the dysregulation of the ILs network indeed jeopardizes implantation leading to RIF. This review further proposes a mapping of future research on how to move forward from mere associations to robust molecular data that will allow an accurate profiling of ILs in turn enabling evidence-based consultancy and decision making when addressing RIF patients.

Association of VEGF and p53 Polymorphisms and Spiral Artery Remodeling in Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis

Many studies have reported the association of VEGF-1154G/A, VEGF 936C/T, and p53 Arg72Pro polymorphisms with recurrent pregnancy loss (RPL), but the outcomes are inconsistent. We have used a meta-analysis to associate these polymorphisms with RPL, having the spiral artery remodeling as a major risk factor. The studies were identified from three different reputed databases, namely ScienceDirect, PubMed/Medline, and Scopus. The eligible studies of VEGF-1154G/A, VEGF 936C/T, and p53Arg72Pro polymorphisms associated with the RPL were selected for the analysis. They were segregated into three different ethnic groups as Asians, Caucasians, and mixed population. For the analysis, the overall prevalence, odds ratio, risk ratio, relative risk ratio, and p-values were calculated. A total of 3,241 RPL cases and 3,205 healthy controls from 21 different case-control studies were analyzed. RPL was highly prevalent in the mixed population with VEGF-1154G/A and p53 Arg72Pro polymorphisms (70.04 and 66.46%, respectively) and in the Asian population with VEGF 936C/T polymorphism (53.58%). The homozygous recessive genotypes of VEGF and p53 exhibited significant association between the respective polymorphisms and RPL along with the increased risk of outcome. The current analysis conclusively reports the geographic distribution of the different genetic polymorphisms which shows high association with the progression of RPL. Understanding the spectrum of polymorphisms on different populations with the spiral artery remodeling as a risk factor encloses the importance of the vasculature during the pregnancy.

Association of vascular endothelial growth factor A polymorphisms and aberrant expression of connexin 43 and VEGFA with idiopathic recurrent spontaneous miscarriage

AIM

Idiopathic recurrent spontaneous miscarriage (IRSM) is one of the pregnancy outcomes that affects 1-2% of women trying to conceive. Specific genotype or aberrant expression of vascular endothelial growth factor A (VEGFA) and connexin 43 (Cx43) as two important genes for embryonic development are deemed to increase the risk of IRSM.

METHODS

To investigate any possible association of VEGFA polymorphisms and aberrant expression of Cx43 and VEGFA with IRSM, we carried out a case-control study including embryo chorionic villus tissues of 100 pregnant women with IRSM and 100 embryo chorionic villus tissues of healthy pregnant women without history of miscarriage. Restriction fragment length polymorphism was used for genotyping of rs699947 (-2578C/A) and rs2010963 (-634G/C) polymorphisms in VEGFA. Besides, quantitative real-time PCR was performed for VEGFA and Cx43 expression analysis.

RESULTS

The results showed that the frequency of -634G/C and C/C genotypes was significantly higher in aborted fetuses (P = 0.001 and P < 0.001, respectively) compared to the control group's. However, the frequency of -2578C/A genotypes was not significantly different between the cases and controls. Moreover, a significant higher expression of VEGF (P = 0.0005) and Cx43 (P = 0.0011) was observed in chorionic villus tissues of women with IRSM.

CONCLUSION

The finding demonstrated that IRSM frequency may depend on GC and CC genotypes of rs2010963 VEGF polymorphism and expression level of VEGF and Cx43 in IRSM patients was increased.

Prevalence of candidate single nucleotide polymorphisms on p53, IL-11, IL-10, VEGF and APOE in patients with repeated implantation failure (RIF) and pregnancy loss (RPL)

Recurrent pregnancy loss (RPL; defined as the loss of three or more consecutive pregnancies) and recurrent implantation failure (RIF; when implantation is not achieved after at least three cycles of IVF) are two of the major challenges that reproductive medicine faces. Some polymorphisms have been identified as possible causes of an increased risk of these diseases. This paper studies the prevalence of the polymorphisms in p53, VEGF, IL-10, IL-11 and APOE in RIF and RPL patients that determines the risk for these pathologies. A total of 255 patients were selected (89 RPL patients, 77 RIF patients and 89 controls) and genotyped for p53-R72P; IL-11-1082-AG; VEGF-1154-AG; IL-10; APOE-R112C; APOE-R158C. Statistically significant differences were found in the prevalence of the E4 isoform (R122-R158) of the APOE gene in RPL patients (p < 0.05), and in RIF patients, the R72P polymorphism of the p53 gene and the 1154-AG of the VEGF gene showed different distribution (p < 0.05). Regarding the p53 and IL-11 studied polymorphisms, PP of p53 gene and GG of IL-11 are more prevalent in RPL patients without reaching statistical significance. In conclusion, our results suggest patients carrying variants in p53 and VEGF would be at risk of RIF, and those carrying variants in APOE gene would suffer RPL.

Angiogenesis and oxidative stress-related gene variants in recurrent pregnancy loss

Recurrent pregnancy loss (RPL) affects ~3-5% of couples attempting to conceive and in around 50% of cases the aetiology remains unknown. Adequate vascularisation and placental circulation are indispensable for the development of a normal pregnancy. Prostaglandin-endoperoxide synthase 2 (PTGS2), vascular endothelial growth factor (VEGF) and the nitric oxide (NO) systems play important roles in reproductive physiology, participating in several steps including implantation and apoptosis of trophoblast cells. In this study we evaluated genetic polymorphisms in the inducible nitric oxide synthase (NOS2), PTGS2 and VEGFA genes as susceptibility factors for RPL. A case-control study was conducted in 149 women having two or more miscarriages and 208 controls. Allele and genotype distributions of the polymorphisms studied in the two groups were not statistically different. However, the dominant model showed that the presence of variant T (TT/GT) of rs2779249 (-1290G>T) of NOS2 was significantly associated with RPL (OR=1.58, CI 95%=1.03-2.44; P=0.037). The increased risk remained significant when adjusted for number of pregnancies, alcohol consumption and ethnicity (OR=1.92, CI95%=1.18-3.11; P=0.008). These results suggest that the variant genotypes of the functional polymorphism rs2779249 in the NOS2 promoter are a potential risk for RPL, possibly due to oxidative stress mechanisms.

Association of VEGF genetic polymorphisms with recurrent spontaneous abortion risk: a systematic review and meta-analysis

Background

Studies of the associations between the genetic polymorphisms of the vascular endothelial growth factor (VEGF) gene and recurrent spontaneous abortion (RSA) have revealed conflicting results. The present meta-analysis was performed to provide a more precise estimation of these relationships and to explore potential sources of heterogeneity that may have influenced the reported disparities.

Methods

An extensive literature search for relevant studies was conducted on PubMed, Embase, and The Cochrane Library through June 6, 2014. Crude odds ratio (OR) with 95% confidence intervals were calculated.

Results

10 case-control studies including 1,832 RSA patients and 2,271 healthy controls were identified. Meta-analysis indicated that rs1570360, rs3025039, rs2010963, and rs3025020 polymorphisms in the VEGF gene correlated with elevated RSA risk. The rs1570360 variant was statistically significantly relevant to RSA risk among non-Asian populations. Interestingly, the rs3025039 variant was statistically significantly relevant to RSA risk among Asian populations.

Conclusions

The current meta-analysis indicates that rs1570360, rs3025039, rs2010963, and rs3025020 polymorphisms increase RSA susceptibility. Moreover, rs1570360 and rs3025039 polymorphisms may play various roles in RSA susceptibility in various geographic groups.

Vascular endothelial growth factor (VEGF) gene polymorphisms and breast cancer risk in Punjabi population from North West India

The purpose of this study was to evaluate the association of seven VEGF promoter polymorphisms with breast cancer risk in Punjabi population from North West India. We screened DNA samples of 102 sporadic breast cancer patients and 102 unrelated healthy, gender, and age-matched individuals for seven VEGF promoter polymorphisms [-417 C/T (rs833062), -172 C/A (rs59260042), -165 C/T (rs79469752), -160 C/T, -152 G/A (rs13207351), -141 A/C (rs28357093) and -116 G/A (rs1570360)] by direct sequencing. The frequency of GG, GA, and AA genotype of -152 G/A polymorphism was 26.47 vs 38.34%, 46.08 vs 51.96%, and 27.45 vs 9.80%, in patients and controls, respectively. VEGF -152 AA genotype was significantly associated with increased risk for breast cancer (OR = 4.04, 95%CI, 1.69-9.68, p = 0.001; recessive model OR = 3.48, 95%CI, 1.59-7.63, p = 0.001). For VEGF -116 G/A polymorphism, G and A allele frequencies were 65.2 vs 76.47% and 34.8 vs 23.53% in patients and controls, respectively. Individuals having -116 AA genotype (OR = 3.40; 95%CI, 1.24-9.37; p = 0.014) and A allele (OR = 1.73; 95%CI, 1.12-2.67; p = 0.012) were associated with increased risk for breast cancer. VEGF -165 C/T and -141 A/C polymorphisms were associated with reduced risk for breast cancer. There was significantly decreased frequency of CT genotype (4.90 vs 18.63%; p = 0.002) and T allele (2.45 vs 9.31%; p = 0.003) of -165 C/T polymorphism among breast cancer patients as compared to controls. VEGF -141 A and C allele frequency were 96.57 vs 91.18% and 3.43 vs 8.82% in patients and controls, respectively. Significant reduced risk for breast cancer was observed with AC genotype (OR = 0.34, 95%CI, 0.14-0.86; p = 0.019) and C allele (OR = 0.37; 95%CI, 0.15-0.89; p = 0.023) of -141 A/C polymorphism. We did not observe association of VEGF -417 T/C, -172 C/A, -160 C/T polymorphisms with breast cancer risk in the studied subjects (p > 0.05). The VEGF -152 G/A and -116 G/A polymorphisms were found to be significantly associated with increased risk for breast cancer while -165 C/T and -141 A/C polymorphisms were found to be associated with decreased risk for breast cancer in Punjabi population from North West India.