D. Lorton, BETA-AMYLOID-INDUCED IL-1-BETA RELEASE FROM AN ACTIVATED HUMAN MONOCYTE CELL-LINE IS CALCIUM-DEPENDENT AND G-PROTEIN-DEPENDENT, Mechanism of ageing and development, 94(1-3), 1997, pp. 199-211
The proinflammatory cytokine, interleukin-l (IL-I) is elevated in the
Alzheimer's disease (AD) brain [1-3]. Studies from our laboratory have
demonstrated that beta-amyloid (A beta) 1-42, fibrillar A beta 1-40 a
nd A beta 25-35 induce the release of IL-1 beta from activated THP-1 c
ells, a human monocyte cell line [4,9]. A beta also is chemotactic for
primary rodent microglia and peritoneal macrophages [5]. We hypothesi
ze that A beta is a chemokine and induces these responses by interacti
on with chemotactic receptors. If this is true, then these A beta-indu
ced responses should be calcium-dependent and require activation of pe
rtussis toxin-sensitive G-proteins. To test this hypothesis, THP-1 cel
ls were grown in culture with lipopolysaccharide (LPS) and incubated w
ith A beta 1-42 (5 mu M) in the presence and absence of a calcium chel
ator, an inhibitor of intracellular calcium mobilization, a calcium ch
annel blocker, or pertussis toxin, a bacterial endotoxin which uncoupl
es G proteins from receptors by catalyzing the ADP ribosylation of cys
teine near the carboxy-terminus of the alpha subunit [6]. The media wa
s collected and IL-1 beta present in the media was measured using an E
LISA. Treatment of LPS-activated THP-1 cells with A beta 1-42 signific
antly elevated IL-1 beta released into the media as previously shown.
Addition of ethylene glycol-bis (beta-aminothyl ether) N,N,N',N'-tetra
acetic acid (EGTA) (0.5 mM), a calcium chelator, to the media blocked
A beta-induced IL-1 beta release, but had no effect on LPS-activated T
HP-I cell release of IL-1 beta. The presence of 3,4,5-trimethoxybenzoi
c acid 8-(diethyl amino)-octyl ester (TMB-8), an inhibitor of intracel
lular calcium mobilization, as well as nickel chloride, a non-specific
calcium channel blocker, in the media also inhibited A beta-induced I
L-1 release from LPS-activated THP-1 cells. IL-1 beta release from act
ivated THP-1 monocytes incubated with TMB-8 and nickel chloride withou
t A beta remained at baseline values. Pretreatment of THP-1 monocytes
with pertussis toxin for 4 h, followed by LPS activation and incubatio
n with A beta, antagonized the release of IL-1 beta from these cells,
but did not alter IL-1 beta release from activated THP-1 monocytes. Th
ese data suggest that A beta-induced IL-1 beta release from these cell
s is calcium-dependent and requires the activation of specific G-prote
ins. These findings are consistent with known second messengers that a
re activated following stimulation of chemotactic receptors. (C) 1997
Elsevier Science Ireland Ltd.