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Objective: Helicobacter pylori (H. pylori) cytotoxin and its heterogeneity amongst strains has been closely linked to the varying infection-associated clinical outcomes. In order to determine the decisive role of the vacuolating cytotoxin (vacA) gene mosaicism in its corresponding gene expression and phenotype, we aimed to characterize vacA alleles of different H. pylori strains in addition to the resulting protein and its vacuolating activity in epithelial cell culture. Materials and Methods: vacA gene polymorphism was determined for 80 H. pylori strains isolated from dyspeptic patients, using multiplex gene-specific polymerase chain reaction (PCR). VacA protein was detected by immuno-blotting assay using a polyclonal anti-VacA antibody. In vitro cytotoxicity assay was conducted on HeLa cells in order to evaluate the vacuolating cytotoxin activity. Results: Genotyping revealed the following strain distribution: 26 (32.5%) s1m1, 35 (43.8%) s1m2, and 19 (23.8%) s2m2 subtypes. Infection with s1m1 type strain was significantly associated with gastric cancer as compared to non-ulcer dyspepsia (p=0.005) and peptic ulcer disease (p=0.008). A 95-kDa immuno-reactive band that represented the vacuolating toxin was demonstrated in SDS-PAGE analysis of concentrated culture filtrate (CCF) of H. pylori strains. H. pylori CCFs induced HeLa cell vacuolation which correlated with the strain genotype; s1m1 strains demonstrated higher levels of vacuolation as compared to s1m2 strains, whereas s2m2 strains showed no detectable cytotoxic activity. Conclusion: The current study confirmed the relatively high cytotoxic activity of s1m1 type H. pylori strains which infect the majority of patients suffering from gastric cancer and may be partly responsible for the pathogenesis of this mortal disease. [ABSTRACT FROM AUTHOR]

Background: Cytokine gene single nucleotide polymorphisms (SNPs) are widely used to study susceptibility to complex diseases and as a tool for anthropological studies., Materials and Methods: To investigate cytokine SNPs in an Iranian multi-ethnic population, we have investigated 10 interleukin (IL) SNPs (IL-1β (C-511T, T-31C), IL-2 (G-384T), IL-4 (C-590T), IL-6 (G-174C), IL-8 (T-251A), IL-10 (G-1082A, C-819T, C-592A) and tumor necrosis factor-alpha (TNF-α) (G-308A) in 415 Iranian subjects comprising of 6 different ethnicities. Allelic and genotypic frequencies as well as Hardy-Weinberg equilibrium (HWE) were calculated by PyPop software. Population genetic indices including observed heterozygosity (Ho), expected heterozygosity (He), fixation index (FIS), the effective number of alleles (N e) and polymorphism information content (PIC) were derived using Popgene 32 software. Multidimensional scaling (MDS) was constructed using Reynold's genetic distance obtained from the frequencies of cytokine gene polymorphism., Results: Genotypic distributions were consistent with the HWE assumptions, except for 3 loci (IL-4-590, IL-8-251 and IL-10-819) in Fars and 4 loci (IL-4-590, IL-6-174, IL-10-1082 and TNF-α-308) in Turks. Pairwise assessment of allelic frequencies, detected differences at the IL-4-590 locus in Gilakis versus Kurds (P = 0.028) and Lurs (P = 0.022). Mazanis and Gilakis displayed the highest (Ho= 0.50 ± 0.24) and lowest (Ho= 0.34 ± 0.16) mean observed heterozygosity, respectively., Conclusions: MDS analysis of our study population, in comparison with others, revealed that Iranian ethnicities except Kurds and Mazanis were tightly located within a single cluster with closest genetic affinity to Europeans.