Background: Apoptosis of neutrophils and CD4 T-lymphocytes in Human Immunodeficiency Virus (HIV) infection may occur due to activation of the extrinsic or intrinsic apoptotic pathway. Presently, there is limited data on expression of genes involved in intrinsic apoptotic pathway. In this study, the differential expression of genes involved in intrinsic apoptotic pathway was investigated in neutrophils and CD4 T-lymphocytes.
Materials and Methods: The differential expression of selected genes was investigated among the healthy controls and HIV-infected patients who were (1) Asymptomatic (CD4+ T-lymphocytes >200/μl), (2) Symptomatic (CD4+ T-lymphocytes <200/μl), (3) ART receivers (>3 years). Isolation of neutrophils and CD4 T-lymphocytes was performed using Ficoll-Hypaque method. Total RNA was extracted from the isolated neutrophils and CD4 T-lymphocytes and gene expression was performed by Real-time PCR. Measurement of CD4 T-lymphocytes was carried out by flowcytometry.
Results: Among the genes under study, BAX, BIM, Caspase-3, Caspase-9 and Calpain-1 in neutrophils were significantly up regulated in all the groups except those who were on ART, where all most all of the genes showed expression near to normal. Interestingly, amid of ongoing apoptosis in neutrophils, unexpected high-level expression of anti-apoptotic MCL-1 gene was observed in all HIV patients. In CD4 T-lymphocytes, no significant difference in expression of any of the genes was observed except downregulation of Caspase-9 (p < 0.05). None of the studied genes in both type of cells showed any significant correlations between the gene expressions and CD4 T-lymphocyte count except Calpain-1 expression in neutrophil (r = - 0.334, p<0.05).
Conclusion: The genes of intrinsic apoptotic pathway of neutrophils but not of peripheral CD4 T-lymphocytes were differently expressed during HIV infection which improved upon initiation of ART. However, there is no doubt that further studies are necessary to determine whether this differential gene expression is reflected at the level of protein or not.