Administration of AMD3100 in endotoxemia is associated with pro-inflammatory, pro-oxidative, and pro-apoptotic effects in vivo.

BACKGROUND: Chemokine receptor 4 (CXCR4) is a multifunctional G protein-coupled receptor that is activated by its natural ligand, C-X-C motif chemokine 12 (CXCL12). As a likely member of the lipopolysaccharide (LPS)-sensing complex, CXCR4 is involved in pro-inflammatory cytokine production and exhibits substantial chemo-attractive activity for various inflammatory cells. Here, we aimed to characterize the effects of CXCR4 blockade in systemic inflammation and to evaluate its impact on organ function. Furthermore, we investigated whether CXCR4 blockade exerts deleterious effects, thereby substantiating previous studies showing a beneficial outcome after treatment with CXCR4 agonists in endotoxemia.

METHODS: The CXCR4 antagonist AMD3100 was administered intraperitoneally to mice shortly after LPS treatment. After 24 h, health status was determined and serum tumor necrosis factor alpha (TNF alpha), interferon gamma (IFN gamma), and nitric oxide (NO) levels were measured. We further assessed oxidative stress in the brain, kidney, and liver as well as liver biotransformation capacity. Finally, we utilized immunohistochemistry and immunoblotting in liver and spleen tissue to determine cluster of differentiation 3 (CD3), CD8, CD68, and TNF alpha expression patterns, and to assess the presence of various markers for apoptosis and oxidative stress.

RESULTS: Mice treated with AMD3100 displayed impaired health status and showed enhanced serum levels of TNF alpha, IFN gamma and NO levels in endotoxemia. This compound also amplified LPS-induced oxidative stress in all tissues investigated and decreased liver biotransformation capacity in co-treated animals. Co-treatment with AMD3100 further inhibited expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf-2), heme oxygenase-1 (HO-1), and various cytochrome P450 enzymes, whereas it enhanced expression of CD3, inducible nitric oxide synthase, and TNF alpha, as well as the total number of neutrophils in liver tissue. Spleens from co-treated animals contained large numbers of erythrocytes and neutrophils, but fewer CD3+ cells, and demonstrated increased apoptosis in the white pulp.

CONCLUSIONS: AMD3100 administration in a mouse model of endotoxemia further impaired health status and liver function and mediated pro-inflammatory, pro-oxidative, and pro-apoptotic effects. This suggests that interruption of the CXCR4/CXCL12 axis is deleterious in acute inflammation and confirms previous findings showing beneficial effects of CXCR4 agonists in endotoxemia, thereby more clearly elucidating the role of CXCR4 in inflammation.