Objective: To study the copy numbers and mRNA expression levels of the Programmed Death-1 gene in chronic hepatitis B patients and to analyze the differences of the copy numbers and mRNA expression levels of the gene in patients with different clinical outcomes.
Methods: Real time PCR was adopted to detect the PD-1 gene copy numbers and their mRNA expressions in peripheral blood mononuclear cells (PBMCs) from 27 samples from healthy donors in Control group, 31 samples from chronic asymptomatic HBV carriers (ASC, n=31), 19 samples from chronic severe hepatitis B patients (CSH, n=19) and 29 samples from Primary hepatitis B Virus-related hepatocarcinoma (PHC, n=29). The differences and relationship of copy numbers and their mRNA expression levels among those groups were compared and analyzed by adopting Chi-square test and Rank sum test.
Results: PD-1 gene copy number deviated from 0 copy to 3 copies among all the 106 samples. In control group, ASC group, CSH group and PHC group, the percentages of cases of haploid (single) were 37.0%, 35.5%, 26.3% and 6.9%, respectively, the percentages of cases of diploid (double) were 55.5%, 58.0%, 63.2% and 82.8%, respectively, and the percentages of cases of triploid (triple) were 3.7%, 6.5%, 10.5% and 10.3%, respectively. The percentage of cases of polyploid (diploid and triploid) in control group, ASC group, CSH group and PHC group were 59.3%, 64.5%, 73.7% and 93.1%, respectively. The different distribution of PD-1 gene copy number of polyploid was significant in total samples (x2=9.583, P<0.05). Compared with Control Group and ASC group, the percentage of cases of polyploid in PHC group was lower with the x2 equals to 8.985 and 7.215 respectively and both with P less than 0.05. The difference between the two groups was statistically significant. The mean PD-1 gene copy numbers for these four groups were 1.59+/-0.63, 1.70+/-0.52, 1.84+/-0.60 and 2.00+/-0.37 while the median were 0.002 54, 0.002 72, 0.002 55 and 0.001 33 respectively. Except the control group, there was a uptrend in the other three groups while PD-1 gene mRNA expression presented a downtrend. The mean of PD-1 gene copy numbers of 2 and their mRNA expression levels were 19.59, 32.57 and 33.22 for PHC, CSH and ASC groups among which PHC group had the lowest value, there was significant differences found in the comparison with F=5.395 and P<0.05.
Conclusion: PD-1 gene copy numbers and their mRNA expression levels were different in chronic HBV infected patients with different transformation. It is valuable to follow up the patients with more than 1 copy number of PD-1 gene in long term.