CCL5 induces a pro-inflammatory profile in microglia in vitro

The chemokine receptors CCR1, CCR2, CCR3, CCR5, and CXCR2 have been found to be expressed on microglia in many neurodegenerative diseases, such as multiple sclerosis and Alzheimer’s disease. There is emerging evidence that chemokines, besides chemoattraction, might directly modulate reactive profiles of microglia. To address this hypothesis we have investigated the effects of CCL2, CCL3, CCL5, and CXCL1 on cytokine and growth factor production, NO synthesis, and phagocytosis in non-stimulated and lipopolysaccharide-stimulated primary rat microglia. The respective receptors CCR1, CCR5, and CXCR2 were shown to be functionally expressed on microglia. All tested chemokines stimulated chemotaxis whereas only CCL5 increased NO secretion and attenuated IL-10 as well as IGF-1 production in activated microglia. Based on these findings we propose that besides its chemoattractant function CCL5 has a modulatory effect on activated microglia.