Ketotifen is a
mast cell stabilizer and useful in younger children with allergic diseases such as
asthma and
allergic rhinitis.
Macrophage-derived chemokine (MDC) is a T-helper cell type 2 (Th2)-related
chemokine involved in recruitment of Th2 cells toward
allergen-challenged
inflammation. However, the Th1-related
chemokines,
interferon-inducible protein 10 (IP-10)/CXCL10, and the monokine induced by
interferon-gamma (MIG)/CXCL9 are also important in
allergen-induced
asthma in animal models. We investigated the effects of
ketotifen on the expression of Th1- and Th2-related
chemokines of human monocytes in vitro and ex vivo.
Ketotifen (5-50 microM) significantly down-regulated
lipopolysaccharide (LPS)-induced MDC, MIG and IP-10 (p < 0.05, each comparison) in THP-1 cells and human primary monocytes in a dose-dependent manner.
SB203580 [
p38-mitogen-activated protein kinase (MAPK) inhibitor] suppressed LPS-induced MDC and IP-10 expression, and
PD98059 (ERK-MAPK inhibitor) could only suppress LPS-induced IP-10, but not MDC expression. LPS-induced pp38 and p-ERK expression of THP-1 monocytic cells was suppressed by
ketotifen. These data demonstrate that
ketotifen is effective in down-regulating LPS-induced MDC, MIG and IP-10, which play important roles in the pathogenesis of airway
inflammation. The suppressive effect on MDC and IP-10 may, at least in part, involve the down-regulation of LPS-induced p38 and ERK-MAPK expression.