Constant, Stephanie L.

Abstract Eosinophils are a major pathological component of the inflammatory cell infiltrate found in lungs as a result of allergic disease. They migrate into lungs in response to a variety of chemokines. The development and effector phases of the allergic response are dependent on the actions of interleukin (IL)-4 and IL-13 on a wide variety of cell types. However, how these two cytokines directly affect eosinophil signaling, function and chemotaxis is largely unknown. Using mouse eosinophils purified from IL-5 transgenic mice and a transwell migration assay, eotaxin-1 (30nM) induced eosinophil migration 6–11x over background. IL-4 alone was able to induce eosinophil migration 2x over background. More eosinophils migrated in response to eotaxin when IL-14 or IL-13 was also placed in the bottom chamber. IL-4 appeared to be more potent than IL-13. This effect was dependent upon cytokine concentration. Interestingly, when eosinophils were pretreated with IL-4 for 30 minutes prior to chemotaxis, migration to eotaxin-1 was enhanced 4-fold. However, pretreatment with IL-13 did not enhance chemotaxis to eotaxin-1. These data suggest that IL-4 and IL-13 have direct and rapid effects on the chemotactic function of eosinophils with some differences. We are investigating the mechanisms of these effects, as well as other signaling and functional responses of eosinophils to these cytokines. (AI38985 and HLT32007698)

Abstract Extracellular cyclophilins have been well described as chemotactic factors for various leukocyte subsets. This chemotactic capacity is dependent upon interaction of cyclophilins with the cell surface signaling receptor CD147. Elevated levels of extracellular cyclophilins have been documented in several inflammatory diseases. We propose that extracellular cyclophilins, via interaction with CD147, may contribute to the recruitment of leukocytes from the periphery into tissues during inflammatory responses. In this study, we examined whether extracellular cyclophilin-CD147 interactions might influence leukocyte recruitment in the inflammatory disease allergic asthma. Using a mouse model of asthmatic inflammation, we show that 1) extracellular cyclophilins are elevated in the airways of asthmatic mice; 2) mouse eosinophils and CD4+ T cells express CD147, which is up-regulated on CD4+ T cells upon activation; 3) cyclophilins induce CD147-dependent chemotaxis of activated CD4+ T cells in vitro; 4) in vivo treatment with anti-CD147 mAb significantly reduces (by up to 50%) the accumulation of eosinophils and effector/memory CD4+ T lymphocytes, as well as Ag-specific Th2 cytokine secretion, in lung tissues; and 5) anti-CD147 treatment significantly reduces airway epithelial mucin production and bronchial hyperreactivity to methacholine challenge. These findings provide a novel mechanism whereby asthmatic lung inflammation may be reduced by targeting cyclophilin-CD147 interactions.

Abstract Tumor-associated eosinophilia has been observed in numerous human cancers and several tumor models in animals; however, the details surrounding this eosinophilia remain largely undefined and anecdotal. We used a B16-F10 melanoma cell injection model to demonstrate that eosinophil infiltration of tumors occurred from the earliest palpable stages with significant accumulations only in the necrotic and capsule regions. Furthermore, the presence of diffuse extracellular matrix staining for eosinophil major basic protein was restricted to the necrotic areas of tumors, indicating that eosinophil degranulation was limited to this region. Antibody-mediated depletion of CD4+ T cells and adoptive transfer of eosinophils suggested, respectively, that the accumulation of eosinophils is not associated with T helper cell type 2-dependent immune responses and that recruitment is a dynamic, ongoing process, occurring throughout tumor growth. Ex vivo migration studies have identified what appears to be a novel chemotactic factor(s) released by stressed/dying melanoma cells, suggesting that the accumulation of eosinophils in tumors occurs, in part, through a unique mechanism dependent on a signal(s) released from areas of necrosis. Collectively, these studies demonstrate that the infiltration of tumors by eosinophils is an early and persistent response that is spatial-restricted. It is more important that these data also show that the mechanism(s) that elicit this host response occur, independent of immune surveillance, suggesting that eosinophils are part of an early inflammatory reaction at the site of tumorigenesis.