Expression of chemokines by human fetal microglia after treatment with the human immunodeficiency virus type 1 protein Tat.
Chemokines are important mediators of inflammation. It has been demonstrated that there is an increase in chemokine expression in both the sera and brain of individuals infected with human immunodeficiency virus type 1 (HIV-1). The HIV-1 viral protein, Tat, a transcriptional regulator, has been detected in the central nervous system (CNS) of infected individuals, and has been demonstrated to induce chemokines from various cells within the brain. The authors now show that the interaction of human microglia, the resident phagocytes of the brain, with Tat leads to dramatic increases in the secretion of the chemokines CCL2, CXCL8, CXCL10, CCL3, CCL4, and CCL5. Treatment of microglia with Tat plus specific inhibitors of signal transduction pathways demonstrated that the induction of each chemokine is regulated differently. Tat-induced expression of CCL2 and CCL4 was mediated by the activation of the extracellular regulated kinase (ERK)1/2 mitogen-activated protein kinase (MAPK) pathway and the phosphatidylinositol 3-kinase (PI3K) pathway, whereas the induction of CXCL8 and CCL3 was mediated only by the p38 MAPK pathway. Tat-induced CXCL10 expression was mediated, to some extent, by activation of the ERK1/2 MAPK pathway, phosphatidylinositol 3-kinase pathway, and the p38 MAPK pathway, whereas CCL5 expression was not mediated by any pathway tested. Western blot analysis demonstrated phosphorylation of ERK 1/2 and Akt upon stimulation of microglia with Tat. These data suggest that a soluble HIV-1 viral protein can alter the chemokine balance in the brain, which can then lead to an influx of inflammatory cells and contribute to the neuropathogenesis of HIV-1 infection.
D'Aversa
Teresa G
TG
Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Yu
Karl O A
KO
Berman
Joan W
JW
D015526:AIDS Dementia Complex / Q000276:immunology*; D002478:Cells, Cultured; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D054357:Chemokine CXCL10; D018925:Chemokines / Q000235:genetics* / Q000378:metabolism; D019742:Chemokines, CC / Q000235:genetics / Q000378:metabolism; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism; D005333:Fetus; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D015696:Gene Products, tat / Q000494:pharmacology*; D015497:HIV-1; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D019402:Macrophage Inflammatory Proteins; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D054322:tat Gene Products, Human Immunodeficiency Virus
C066507:CCL4 protein, human; C483024:CCL5 protein, human; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D054357:Chemokine CXCL10; D018925:Chemokines; D019742:Chemokines, CC; D019743:Chemokines, CXC; D015696:Gene Products, tat; D036341:Intercellular Signaling Peptides and Proteins; D019402:Macrophage Inflammatory Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases