Analysis of immunological responses of murine macrophages to hydroxyapatite
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Date
2006
Authors
Gopinath, Vellore Kannan
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Abstract
The aim of the present study was to analyze the immunological
response of hydroxyapatite (HA) to RAW264.7 cells by
determining HA-induced phagocytosis. Immunological
parameters included in this study were the role of
polymerization of actin and microtubule, protein kinase-C
(PKC), nitric oxide (NO), interleukin-1β (IL-1β) and tumor
necrosis factor-α (TNF-α).
The results showed that HA were phagocytosed by murine
macrophage cell line (RAW264.7 cells) at different incubation
time. Increased PI of HA-treated cells were paralleled with
increased period of incubation. TEM (Transmission electron
microscopy) analysis showed that HA particles were engulfed
by the cells and located within cell vacuoles. Cytochalasin B
or/and colchicine significantly inhibited phagocytic activity of the
cells to both HA particles and latex bead in a dose-dependent
fashion. Stimulated cells produced PKC enzyme right at the
early stage of phagocytosis at 7 minutes. Pre-treated cells with
Bisindolylmaleimide ingested fewer particles in a dose
dependent fashion. NO production was less by HA stimulated
cells than by latex bead-stimulated cells. Inducible nitric oxide
synthase (iNOS) expression in both latex bead- and HAstimulated
cells was observed at 7, 15, 30 and 60 minutes of
incubation time. L-arginine enhanced but L-NIL inhibited both
phagocytosis and NO production by HA-stimulated cells. HA
stimulated the cells to release both IL-1 β and TNF-α in a timedependent
fashion. In the presence of anti-murine IL-1 β and
TNF-α, HA-induced phagocytic activity by RAW264.7 cells was
significantly reduced. Therefore, the results of the present study
suggest that HA particles may induce phagocytic activity of
murine macrophages (RAW264.7 cells) in an actin and
microtubule polymerization dependent mechanism, which may
be mediated through PKC enzyme. NO may play a crucial role
in HA-induced phagocytosis by RAW264.7 cells which may
also depend on IL-1 β and TNF-α.
Description
PhD
Keywords
Biological science , Immunological , Murine macrophages , Hydroxyapatite