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

ZHANG, NAICHUN; DENG, JIANNING; WU, FENGYAO; LU, XIANGCHAN; HUANG, LEI; ZHAO, MIN

LNs by L-arginine remains to be fully elucidated in patients with HIV infection. Therefore, in the present study, immunohistochemistry and flow cytometry were used to detect the expression levels of Arg I and iNOS in peripheral T cells and LNs. The results showed that, compared with controls, asymptomatic and symptomatic HIV infected patients exhibited increased frequencies of Arg I positive CD4 + T cells and CD8 + T cells in the peripheral blood and LNs, and increased protein expression levels of Arg I in the LNs. In addition, the frequencies of Arg I positive CD4 + T cells and CD8 + T cells in the peripheral blood and LNs, and the protein expression levels of Arg I in the LNs were negatively associated with peripheral CD4 + T cell count and positively correlated with HIV load. By contrast, the frequencies of iNOS positive CD4 + T cells and CD8 + T cells in the peripheral blood and LNs, and the protein expression levels of iNOS were decreased in the LNs of HIV-infected patients, compared with controls. Furthermore, the frequencies of iNOS positive CD4 + T cells and CD8 + T cells in the peripheral blood and LNs, and the protein expression levels of iNOS in the LNs were positively associated with peripheral CD4 + T cell count and negatively associated with HIV load. In arginine-mediated metabolism, L-arginine is hydrolyzed into urea and ornithine, and ornithine is a precursor of polyamines, which are indispensable for the proliferation of cells and parasites (5, (26) (27) (28) . At least two subtypes of arginase have been identified in mammals: Cytoplasmic Arg I and mitochondrial Arg II (29) . These are involved in the same reaction (30) , although Arg I is more important in the urea cycle of the liver. In addition to its role in L-arginine metabolism, Arg is important for immune system function (31,32) as it can inhibit NO synthesis, induce fibrosis and tissue regeneration (33, 34) . Arg is also involved in multiple inflammatory diseases, and is essential for normal T cell function (6, 35, 36) .