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Chemokine and chemokine receptor expression in a novel human mesangial cell line
1Nephrological Center, Medical Policlinic, Ludwig-Maximilians University, Munich, Germany. banas@medpoli.med.uni-muenchen.de
Abstract:
Chemokines are thought to play a pivotal role in mediating the selective migration of leukocytes into sites of tissue injury. The local production of chemokines by mesangial cells (MC) has been linked to inflammatory processes within the glomerulus. To study the chemokine biology of human MC, an immortalized human MC line was generated and then chemokine and chemokine receptor expression was examined in response to various proinflammatory stimuli. The results show that human MC have a specific and limited repertoire of chemokine expression. The stimulus-specific regulation of the chemokines monocyte chemoattractant protein- (MCP- 1), regulated upon activation, normal T cell expressed and secreted (RANTES), interleukin-8 (IL-8), and IP-10 was demonstrated using RNase protection assays. Transcripts for the chemokines MIP-1alpha, MIP-1beta, I-309, or lymphotactin could not be detected. The expression of CC chemokine receptors was investigated by reverse transcription-PCR and RNase protection assays. MC stimulated with interferon-gamma (IFN-gamma) expressed mRNA for the chemokine receptor CCR1. The expression could be further increased by activating the cells with a combination of tumor necrosis factor-a (TNF-alpha), IL-1beta, and IFN-gamma. Under these conditions, no mRNA for CCR2, CCR3, CCR4, CCR5, or CCR8 was detected. A comparison of the immortalized human mesangial cells with primary cells showed identical expression patterns of chemokine receptors. To demonstrate functional activity of chemokine receptors expressed by human MC, chemotaxis assays were performed. MC stimulated with a combination of TNF-alpha, IL-1beta, and IFN-gamma, but not unstimulated MC, migrated toward a RANTES gradient. Eotaxin did not enhance the migratory activity of human MC. In summary, a novel human mesangial cell line was established and the pattern of chemokine expression was examined. For the first time, the inducible expression of functionally active CCR1 by human MC was shown.