Author name:
زهراء عبد الرحیم احمد عبد لله
Supervisor name:
اخلاص مشرف عیدان | علي حسین ادحیة
Abstract:
Visceral leishmaniasis (VL) is a severe chronic systemic zoonotic disease caused by the protozoan Leishmania donovani or L. infantum, in which cytokines play an important role in its pathogenesis. These cytokines are under genetic controls, and their gene polymorphisms have been suggested to exert a functional role in regulating cytokine gene expression. Therefore, the present study determined IFN - γ, IL - 2, IL - 10 and IL - 12 serum levels and gene polymorphisms of 11 cytokine and cytokine receptor genes (IL1A, IL1B, IL2, IL4, IL4R, IL6, IL10, IL12B, TNF, IFNG and TGFB1) in VL patients by ELISA assay and sequence specific primer - PCR method. Gene polymorphism impact on IFN - γ, IL - 2, IL - 10 and IL - 12 serum levels was also evaluated.Forty - four Iraqi Arabs VL patients (age range : 4 months to 12 years) were enrolled in the study. They were referred to hospitals in two Iraqi governorates (Baghdad and Wasit) during the period March 2013 - February 2014. A control sample of 40 apparently healthy individuals was also included and matched patients for age and ethnicity.Most of the ascertained VL cases were in winter and spring with frequencies of 43.2 and 50.3%, respectively. The results also revealed that the age group 1 - 3 years accounted for more than 50% of cases (54.5%) and the infection was more prevalent in male (65.9%) than females (34.1%).A significant increased serum level of IL - 2 (14.72 ± 1.14 vs.4.43 ± 0.49 pg/ml), IL - 10 (40.02 ± 1.26 vs.18.60 ± 1.82 pg/ml), IFN - γ (29.06 ± 1.05 vs. 12.83 ± 1.38 pg/ml) was recorded in VL patients compared to controls. While, IL - 12 serum level showed a non - significant increased level in patients (5.33 ± 3.26 vs.2.17 ± 0.36 pg/ml). Cytokine gene polymorphism analysis revealed that neither genotypes nor alleles of IL1B - 511, IL4R+1902, IL12B - 1188, IFNG+874, TGFB1+896, TNF - 308, IL2 - 330, IL2+166, IL4 - 590, IL4 - 33, IL6nt565/ - 597, IL6 - 174, IL10 - 1082, IL10 - 819 and IL10 - 592 genes showed a significant variation between VL patients and controls. In contrast, a positive association between IL - 1β+3962 CC genotype an C allele and IL4 - 1098 G allele and VL was observed (susceptible genotypes and alleles), while a negative association (protective genotypes and alleles) was recorded for IL1A - 889 TT genotype, IL1B+3962 T allele and IL4 - 1098 TT genotype and T allele. To determine the impact of cytokine genotypes on cytokines serum level, VL patients and controls were distributed according to their serum level in the three genotypes of each cytokine. It was found that TG genotype of IL2 - 330 was observed with the highest IL - 2 level (16.56 ± 1.69 pg/ml) compared to other genotypes. The GT genotype of IL2+166 also showed the highest level of IL - 2 (17.47 ± 2.34 pg/ml) compared to GG (13.53 ± 1.38pg/ml) or TT (15.77 ± 3.88 pg/ml) genotypes in patients. The IL10 - 1082 GG genotype showed the highest level of IL - 10 in patients (45.73 ±3.15 pg/ml) compared to AA (38.02 ± 1.48 pg/ml) genotype. For IL10 - 819 genotypes, they recorded approximated means in patients and no significant difference between them was observed. At the third position of IL10 gene (IL10 - 592), neither patients nor controls demonstrated a significant difference between the means of IL - 10 in their genotypes. At IL12 - 1188, CC genotype showed a significant increase level of IL - 12 (26.16 ±19.76 pg/ml) compared to CA and AA genotype(1.35 ± 0.35 pg/ml and 1.48 ± 0.23 pg/ml respectively) in patients. Finally, neither VL patients nor controls demonstrated a significant difference between the means of IFN - γ in the genotypes of IFNG+874. In conclusion, the role of cytokines in pathogenesis of VL wasascertained, but such role can be better understood in the ground of cytokine gene polymorphisms, which may also have susceptibility or protective effects.
