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Journal of Virology, August 2000, p. 6849-6855, Vol. 74, No. 15
Laboratory of Immunoregulation, National Institute of
Allergy and Infectious Diseases, National Institutes of Health,
Bethesda, Maryland 20892,1 and Division
of Medical Virology, Department of Molecular Microbiology and
Immunology, Nagasaki University Graduate School of Medical Science,
Nagasaki 852-8123,2 and Department of
Pediatrics, Nagasaki University School of Medicine, 1-7-1 Sakamoto,
Nagasaki 852-8501,3 Japan
Received 23 December 1999/Accepted 4 May 2000
Neutrophils dominate acute inflammatory responses that generally
evolve into chronic inflammatory reactions mediated by
monocyte/macrophages and lymphocytes. The latter cell types also serve
as major targets for human immunodeficiency virus type 1 (HIV-1). In
this study we have investigated the role of neutrophil products,
particularly cathepsin G, in HIV infection. Cathepsin G induced
chemotaxis and production of proinflammatory cytokines by macrophages
but not CD4+ T cells. Pretreatment with cathepsin G
markedly increased susceptibility of macrophages but not
CD4+ T cells to acute HIV-1 infection. When macrophages
were exposed to pertussis toxin prior to cathepsin G treatment, the
cathepsin G-mediated effect was almost abrogated, suggesting that
enhancement of HIV-1 replication by cathepsin G requires Gi
protein-mediated signal transduction. Although prolonged exposure to
cathepsin G suppressed HIV infection of macrophages, serine protease
inhibitors, which are exuded from the bloodstream later during
inflammatory processes, neutralized the inhibitory effect. Neutrophil
extracts or supernatants from neutrophil cultures, which contain
cathepsin G, had effects similar to purified cathepsin G. Thus,
cathepsin G, and possibly other neutrophil-derived serine proteases,
may have multiple activities in HIV-1 infection of macrophages,
including chemoattraction of monocyte/macrophages (HIV-1 targets) to
inflamed tissue, activation of target cells, and increase in their
susceptibility to acute HIV-1 infection.
0022-538X/00/$04.00+0
Cathepsin G, a Neutrophil-Derived Serine Protease,
Increases Susceptibility of Macrophages to Acute Human Immunodeficiency
Virus Type 1 Infection
*
Corresponding author. Mailing address: Department of
Pediatrics, Nagasaki University School of Medicine, 1-7-1 Sakamoto,
Nagasaki 852-8501, Japan. Phone: 81-95-849-7297. Fax: 81-95-849-7301. E-mail: hiromori{at}net.nagasaki-u.ac.jp.
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