Objective: To investigate the polymorphisms of interleukin-1B (IL-1B) promoter region -511C/T and interleukin-1 receptor antagonist (RN) gene, the relationship between the genotype of IL-1B and IL-1RN, and the susceptibility to chronic hepatitis B in Chinese population.
Methods: Genomic DNA was extracted from the peripheral blood of 190 patients with chronic hepatitis B and 249 normal controls and then was subjected to PCR amplification. The PCR product was digested by restriction endonuclease Ava I. The product of digestion was subjected to 2% gel-electrophoresis and ethidium bromide staining.
Results: The IL-1B -511C allele was detected in 0.50 of normal controls and 0.48 of patients, while the IL-1B -511T allele was detected in 0.50 of normal controls and 0.52 of patients. The frequency of CC genotype was 0.26 (65/249) and in normal controls 0.24 (45/190) in patients. The frequency of CT genotype was 0.47 (118/249) in normal controls and 0.49 (94/190) in patients. The frequency of TT genotype was 0.27 (66/249) in normal controls and 0.27 (51/190) in patients. The HBV-DNA copies in chronic hepatitis B with CC genotype were significantly decreased, compared with controls (P<0.05). Only four (1/1, 1/2, 2/2 and 1/4) of the five kinds of polymorphism of IL-1RN were found in this study. The frequencies of 1/1, 1/2, 2/2 and 1/4 were 0.88, 0.09, 0.01 and 0.02 in chronic hepatitis B patients respectively, while in controls were 0.81, 0.16, 0.01 and 0.02. The IL-1 RN*1 allele was detected in 0.94 of chronic hepatitis B patients and in 0.90 of controls, while the IL-1RN*2 allele was detected in 0.05 of patients and in 0.09 of normal controls. The frequencies of 1/2 genotype and IL-1RN*2 allele were lower in chronic hepatitis B than in controls (P<0.05).
Conclusion: The polymorphisms of the promoter region -511C/T of IL-1B gene and IL-1RN intron 2 gene are associated with the development of chronic hepatitis B. The people with IL-1RN*2 allele may be protected against HBV infection, and the IL-1B -511 CC genotype may be linked to HBV-DNA copy.