ABSTRACT
In the present study, we investigated the involvement of macrophage-inflammatory protein-1alpha (MIP-1alpha)[CC chemokine ligand 3 (CCL3)], MIP-1beta[CCL4], regulated on activation, normal T expressed and secreted (RANTES)[CCL5], and CC chemokine receptors (CCRs) on neutrophil migration in murine immune inflammation. Previously, we showed that ovalbumin (OVA)-triggered neutrophil migration in immunized mice depends on the sequential release of tumor necrosis factor alpha (TNF-alpha) and leukotriene B(4)(LTB(4)). Herein, we show increased mRNA expression for MIP-1alpha[CCL3], MIP-1beta[CCL4], RANTES[CCL5], and CCR1 in peritoneal cells harvested from OVA-challenged, immunized mice, as well as MIP-1alpha[CCL3] and RANTES[CCL5] but not MIP-1beta[CCL4] proteins in the peritoneal exudates. OVA-induced neutrophil migration response was muted in immunized MIP-1alpha[CCL3](-/-) mice, but it was not inhibited by treatment with antibodies against RANTES[CCL5] or MIP-1beta[CCL4]. MIP-1alpha[CCL3] mediated neutrophil migration in immunized mice through induction of TNF-alpha and LTB(4) synthesis, as these mediators were detected in the exudates harvested from OVA-challenged immunized wild-type but not MIP-1alpha[CCL3](-/-) mice; administration of MIP-1alpha[CCL3] induced a dose-dependent neutrophil migration, which was inhibited by treatment with an anti-TNF-alpha antibody in TNF receptor 1 (p55(-/-))-deficient mice or by MK 886 (a 5-lipoxygenase inhibitor); and MIP-1alpha[CCL3] failed to induce LTB(4) production in p55(-/-) mice. MIP-1alpha[CCL3] used CCR1 to promote neutrophil recruitment, as OVA or MIP-1alpha[CCL3] failed to induce neutrophil migration in CCR1(-/-) mice, in contrast to CCR5(-/-) mice. In summary, we have demonstrated that neutrophil migration observed in this model of immune inflammation is mediated by MIP-1alpha[CCL3], which via CCR1, induces the sequential release of TNF-alpha and LTB(4). Therefore, whether a similar pathway mediates neutrophil migration in human immune-inflammatory diseases, the development of specific CCR1 antagonists might have a therapeutic potential.
Subject(s)
Chemokines, CC/immunology , Chemotaxis, Leukocyte/immunology , Leukotriene B4/immunology , Macrophage Inflammatory Proteins/immunology , Neutrophils/immunology , Receptors, Chemokine/immunology , Tumor Necrosis Factor-alpha/immunology , Animals , Antibodies/pharmacology , Autoimmune Diseases/immunology , Autoimmune Diseases/physiopathology , Chemokine CCL3 , Chemokine CCL4 , Chemokine CCL5/genetics , Chemokine CCL5/immunology , Chemokines, CC/genetics , Chemokines, CC/pharmacology , Chemotaxis, Leukocyte/drug effects , Disease Models, Animal , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Inflammation/immunology , Inflammation/physiopathology , Leukotriene B4/metabolism , Macrophage Inflammatory Proteins/genetics , Macrophage Inflammatory Proteins/pharmacology , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Neutrophils/drug effects , Ovalbumin/immunology , Ovalbumin/pharmacology , RNA, Messenger/metabolism , Receptors, CCR1 , Receptors, Chemokine/drug effects , Receptors, Chemokine/genetics , Receptors, Tumor Necrosis Factor/genetics , Receptors, Tumor Necrosis Factor, Type I , Signal Transduction/drug effects , Signal Transduction/immunology , Tumor Necrosis Factor Decoy Receptors , Tumor Necrosis Factor-alpha/metabolism , Up-Regulation/immunologyABSTRACT
Flavonoids and related polyphenols, in addition to their cardioprotective, anti-tumor, anti-inflammatory, anti-carcinogenic and anti-allergic activities, also possess promising anti-HIV effects. Recent studies documented that the beta-chemokine receptors, CCR2b, CCR3 and CCR5, and the alpha-chemokine receptors, CXCR1, CXCR2 and CXCR4 serve as entry coreceptors for HIV-1. Although flavonoids and polyphenolic compounds elicit anti-HIV effects such as inhibition of HIV-1 expression and virus replication, the molecular mechanisms underlying these effects remain to be clearly elucidated. We hypothesize that flavonoids exert their anti-HIV effects, possibly by interfering at the HIV co-receptor level. We investigated the effect of flavonoid constituents of a proprietary grape seed extract (GSE) on the expression of HIV-1 coentry receptors by immunocompetent mononuclear leukocytes. Our results showed that GSE significantly downregulated the expression of the HIV-1 entry co-receptors, CCR2b, CCR3 and CCR5 in normal PBMC in a dose dependent manner. Further, GSE treated cultures showed significantly lower number of CCR3 positive cells as quantitated by flow cytometry analysis which supports RT-PCR gene expression data. Investigations of the mechanisms underlying the anti-HIV-1 effects of grape seed extracts may help to identify promising natural products useful in the prevention and/or amelioration of HIV-1 infection.