Baseline characteristics of patients and controls
A total of 120 cases of PE and 120 pregnant women were included in the study. Both plasma cytokines and genetic polymorphisms was successfully analysd in 115 PE patients and 102 pregnant women. Out of 150 healthy Chinese women included in the present investigation, IL-17, IL-23 and IL-12B polymorphisms and plasma cytokines levels were efficiently quantified in 147 subjects. Thus based on availability of data for both genotypes and levels of cytokines, a total of 364 females were considered in the present study comprising 115 PE patients, 102 pregnant women, and 147 non-pregnant women. Different baseline characteristics were compared among clinical categories (Table-1). A significant difference was observed in different parameters while comparing PE cases and pregnant women, such as duration of gestation (days), body mass index (Kg/m2), vaginal delivery (%), caesarian section (%), fetal birth weight (gram), systolic/diastolic blood pressure (mmHg), WBC count (x109/ L), levels of urea and uric acid (mg/dL). However, percentage of pre-eclamptic patients with primiparas were not significantly altered in comparison to healthy pregnant women.
PE patients displayed higher serum IL-17A compared to controls
The serum levels of IL-17A and IL-23 were quantified by ELISA. As shown in figure-1A, the mean level of IL-17A was 59.1±0.93 pg/ml in healthy women without pregnancy, whereas healthy pregnant women and subjects with PE had 61.13±1.43 pg/ml and 746.7±17.16 pg/ml of IL-17A level, respectively. Although a comparable level in IL-17A was observed between healthy pregnant and non-pregnant women, subjects with PE demonstrated a noticeably higher cytokine level as compared to two other study groups, suggesting an essential role of this molecule in promoting pathogenesis during PE. Further, to assesses the importance of IL-23 in regulating the pathologic condition of PE, the titer of the cytokine was measured in sera and the results are shown in figure-1B. The results showed a relatively similar level of this cytokine in all the three groups.
Distribution of IL-17A, IL-23A and IL-12B polymorphisms in healthy non-pregnant women
The genotype and allele frequency of IL-17A (rs2275913, rs1974226, and rs3748067), IL-23A (rs11171806) and IL-12B (rs3212227) polymorphisms in healthy female and the distribution of genotypes for all SNPs are in Hardy-Weinberg equilibrium (rs2275913: X2= 2.58, P= 0.10; rs1974226: X2= 2.83, P= 0.08; rs3748067: X2= 0.17, P= 0.67; rs11171806: X2= 1.93, P= 0.16; rs3212227: X2= 0.01, P= 0.90) (Table-2).
IL-17A (rs2275913) and IL-23A (rs11171806) polymorphisms are associated with predisposition to PE
As shown in Table-2. Heterozygous (GA) and minor allele (A) of IL-17A (rs2275913) polymorphism were significantly more prevalent in PE patients compared to the pregnant women (GA: P=0.007, OR=2.40; A: P=0.02, OR=1.54). No significant genetic association was observed in the distribution of other IL-17A polymorphisms (rs1974226 and rs3748067) and IL-12B (rs3212227) in PE patients in comparison to the pregnant women. Interestingly, when we analyzed association of IL-23A polymorphism (rs11171806) with predisposition to development of PE, a significant link of heterozygous variants and minor allele were noticed with susceptibility to PE development (GA: P=0.008, OR=3.24, A: P=0.004, OR=3.27).
Genotype-phenotype association of IL-17A and IL-23A polymorphisms
AA and GA genotypes of rs2275913 polymorphisms displayed significantly higher serum IL-17A compared to wildtype (GG) (Figure-2A). Serum IL-17A levels were comparable among different genotypes of rs1974226 and rs3748067 polymorphisms (data not shown). Furthermore, variants of IL-23A (rs11171806) also failed to demonstrate any functional relevance on serum levels of IL-23A (Figure-2B).