No abstract

To examine the significance of chemokine activation of CXCR2 in wound healing after chemical burn, cutaneous injury was created by topical application of nitrogen mustard on CXCR2 wild type (+/+), heterozygous (+/-), and knockout (-/-) mice. Wounds were analyzed histologically for neutrophil and monocyte infiltration and for reepithelialization at postwound days 4, 7, and 10. Neutrophil recruitment to the wound site was reduced through postwound day 7 in CXCR2 -/- mice as indicated by myeloperoxidase assay and by visual quantitation. Because there is always concern that mice with targeted deletion of a specific receptor may undergo developmental adaptations to offset the loss of the receptor, we also accessed chemical wound repair in the presence of a small molecule antagonist of CXCR2. Dietary supplementation with a CXCR2 antagonist (SB-265610) during the wound repair process also markedly delayed healing parameters in CXCR2 +/+ mice, even greater than treatment with glucocorticoids. These parallel studies further establish that mice deficient in CXCR2 function exhibit delayed cutaneous wound healing that may be primarily linked to impaired neutrophil recruitment after chemical burn with nitrogen mustard. Thus, there may be a potential therapeutic benefit of treating nitrogen mustard-induced skin lesions with agonists of CXCR2 to facilitate the wound repair process.

Alzheimer’s disease (AD) is characterized by a progressive cognitive decline and accumulation of neurotoxic oligomeric peptides amyloid-β (Aβ). Although the molecular events are not entirely known, it has become evident that inflammation, environmental and other risk factors may play a causal, disruptive and/or protective role in the development of AD. The present study investigated the ability of the chemokines, macrophage inflammatory protein-2 (MIP-2) and stromal cell-derived factor-1α (SDF-1α), the respective ligands for chemokine receptors CXCR2 and CXCR4, to suppress Aβ-induced neurotoxicity in vitro and in vivo. Pretreatment with MIP-2 or SDF-1α significantly protected neurons from Aβ-induced dendritic regression and apoptosis in vitro through activation of Akt, ERK1/2 and maintenance of metalloproteinase ADAM17 especially with SDF-1α. Intra-cerebroventricular (ICV) injection of Aβ led to reduction in dendritic length and spine density of pyramidal neurons in the CA1 area of the hippocampus and increased oxidative damage 24 h following the exposure. The Aβ-induced morphometric changes of neurons and increase in biomarkers of oxidative damage, F2-isoprostanes, was significantly inhibited by pretreatment with the chemokines MIP-2 or SDF-1α. Additionally, MIP-2 or SDF-1α was able to suppress the aberrant mislocalization of p21-activated kinase (PAK), one of the proteins involved in the maintenance of dendritic spines. Furthermore, MIP-2 also protected neurons against Aβ neurotoxicity in CXCR2−/− mice, potentially through observed up regulation of CXCR1 mRNA. Understanding the neuroprotective potential of chemokines is crucial in defining the role for their employment during the early stages of neurodegeneration.