Expression of arginase I and inducible nitric oxide synthase in the peripheral blood and lymph nodes of HIV-positive patients

Arginase I (Arg I) and inducible nitric oxide synthase (iNOS) are important in regulating immune functions through their metabolites. Previous studies have revealed that the expression of Arg I is increased and the expression of iNOS is reduced in the serum and peripheral blood mononuclear cells of human immunodeficiency virus (HIV)-infected patients. As one of the most important immune organs and HIV replication sites, whether similar changes are present in the lymph nodes following HIV infection remains to be elucidated. To investigate this, the present study collected lymph node and blood specimens from 52 HIV-infected patients to measure the expression levels of Arg I and iNOS by immunohistochemistry and fluoresence-based flow cytometry. Compared with control subjects without HIV infection, the patients with HIV had significantly higher expression levels of Arg I in the lymph nodes and higher frequencies of Arg I(+) CD4(+) T cells and CD8(+) T cells in the blood and lymph nodes, and these results were contrary the those of iNOS in the corresponding compartments. The expression levels of Arg I in the lymph nodes and blood were negatively associated with peripheral CD4(+) T cell count and positively associated with viral load. However, the expression levels of iNOS in the lymph nodes and blood were positively associated with peripheral CD4(+) T cell count and negatively associated with viral load. These results showed that alterations in the expression levels of Arg I and iNOS in the peripheral T cells and peripheral nodes of HIV infected patients are associated with disease progression in these patients. These results indicate a potential to therapeutic strategy for delaying disease progression through regulating and manipulating the expression levels of Arg I and iNOS in patients infected with HIV.