Expression of CXCL4 in microglia in vitro and in vivo and its possible signaling through CXCR3

Abstract

Signaling through chemokine receptor CXCR3 in the brain has been implicated in various brain diseases, as CXCR3 and its ligands are found under these conditions. Recently, a new chemokine ligand for CXCR3 was reported. In humans, an alternatively spliced variant of CXCR3 expressed on microvascular endothelial cells, named CXCR3b, was shown to bind CXCL4. In the periphery, the cellular expression and functions of CXCL4 are well described but in the brain its expression and function are unknown. Here, we show that brain microglia are a cellular source of CXCL4 in vitro and in vivo under neurodegenerating conditions. Microglial migration induced by CXCL4 is absent in CXCR3-deficient microglia, indicating a role of CXCR3. CXCL4 furthermore attenuates lipopolysaccharide-induced microglial phagocytosis and nitric oxide production in microglia and BV-2 cells. Based on these findings, it is proposed that locally released CXCL4 may control microglia responses.

S100B Protein Stimulates Microglia Migration via RAGE-dependent Up-regulation of Chemokine Expression and Release

“…Thus, both, BV-2 and primary microglia can be viewed as activated microglia, as also supported by the findings that they express basal levels of cytokines and COX-2 (22, 23) and chemokines (this report) and are able to phagocytose (20,61,83,84). In principle, the low expression level of RAGE in microglia under normal physiological conditions might make it possible that (low) S100B may have a role in microglia patrolling activity (38).…”

The suitability of BV2 cells as alternative model system for primary microglia cultures or for animal experiments examining brain inflammation

“…We switched the BV-2 culture completely to antibioticfree conditions and also reduced the use of FBS, another source of experimental uncertainties, to 2% during stimulations. From a purely logical point-of-view, one can never be sure that a cell line will be able to replace all experiments in PM and in animals, and indeed some differences have been observed between PM and BV-2 (Hausler et al, 2002;de Jong et al, 2008). However, interaction has not been shown in this direct form with purified cells, and the experimental system opens further fields of application of BV-2 cells.…”

“…The primary antibody (purified mouse anti-NF-κB p65, clone: 20/NF-κB/p65, final dilution: 1:200) was purchased from BD Biosciences (San Jose, CA USA), and the binding was visualised with an Alexa-488-labelled secondary antibody (Sigto primary microglia, express functional NADPH oxidase, an enzyme frequently implicated in microglia-triggered neuronal damage (Wu et al, 2006;Yang et al, 2007). However, doubts have been raised that this cell line does not always model the reaction of primary microglia in culture or in the brain (Hausler et al, 2002;de Jong et al, 2008;Horvath et al, 2008). In one study, BV-2 were compared to primary rat microglia, introducing a bias of species differences and different analysis methodology, e.g.…”

CXCR3 ligands are augmented during the pathogenesis of pulmonary sarcoidosis

“…More specifically, similar to the T-helper cell (Th) type 1/Th2 lymphocyte paradigm (Th1 lymphocytes express IFN-c, IL-12 and IL-18 as well as the cell receptors CCR5 and CXCR3, and Th2 lymphocytes express IL-4 and IL-13 as well as the cell surface receptors CCR3 and CCR4), macrophages can also polarise into type 1 (M1) or 2 (M2) macrophages [35][36][37]. Recently, microglia cells, the brain resident macrophages, have been found to express CXCR3 and contribute to specific neurological diseases [38][39][40][41]. We have expanded on these studies by demonstrating that lung cells of monocyte linage (e.g.…”