Blockade of the chemokine receptor CXCR2 ameliorates adjuvant-induced arthritis in rats

Abstract

Background and purpose: Chemokine receptors CXCR1 and CXCR2 may mediate influx of neutrophils in models of acute and chronic inflammation. The potential benefits of oral administration of a CXCR1/2 inhibitor, DF 2162, in adjuvant-induced polyarthritis (AIA) were investigated.

Experimental approach: A model of AIA in rats was used to compare the therapeutic effects of the treatment with DF2162, anti-TNF or anti-CINC-1 antibodies on joint inflammation and local production of cytokines and chemokines.

Key results: DF2162 prevented chemotaxis of rat and human neutrophils induced by chemokines acting on CXCR1/2. DF2162 was orally bioavailable and metabolized to two major metabolites. Only metabolite 1 retained CXCR1/2 blocking activity. Treatment with DF2162 (15 mg kg(-1), twice daily) or metabolite 1, but not metabolite 2, starting on day 10 after arthritis induction diminished histological score, the increase in paw volume, neutrophil influx and local production of TNF, IL-1beta, CCL2 and CCL5. The effects of DF2162 were similar to those of anti-TNF, and more effective than those of anti-CINC-1, antibodies. DF2162 prevented disease progression even when started 13 days after arthritis induction.

Conclusions and implications: DF 2162, a novel orally-active non-competitive allosteric inhibitor of CXCR1 and CXCR2, significantly ameliorates AIA in rats, an effect quantitatively and qualitatively similar to those of anti-TNF antibody treatment. These findings highlight the contribution of CXCR2 in the pathophysiology of AIA and suggest that blockade of CXCR1/2 may be a valid therapeutic target for further studies aiming at the development of new drugs for treatment of rheumatoid arthritis.

Figure 1

Chemical structure, pharmacodynamic and pharmacokinetic profile of DF 2162 in rats. The chemical structures of DF 2162 and metabolite 1 are shown in (a). In (b), the inhibitory effects of DF 2162 and its two major metabolites against CINC-1 (2.5 nM)-induced neutrophil chemotaxis are shown. Only DF 2162 and metabolite 1 significantly (P<0.05) inhibited neutrophil chemotaxis. Plasma levels after single i.v. or p.o. administration of DF 2162 (15 mg kg⁻¹) are shown in (c). The steady-state concentrations of DF 2162 (15 mg kg⁻¹, twice daily) are shown in (d). In all experiments, there were five animals in each group, with the exception of (b) where results are expressed as percentage of inhibition of chemokine-induced chemotaxis from at least three experiments (6–18 replicates). ^*P<0.01 compared to CINC-1-induced chemotaxis.

Figure 2

Effects of treatment with DF 2162 in a model of adjuvant-induced arthritis in rats. Treatment with DF 2162 (15 mg kg⁻¹, twice daily) from day 10 after induction of disease (see arrow) inhibited the increase (a) in paw volume, (b) neutrophil influx, and local production of (c) TNF-α, IL-1β and (d) the chemokines CCL5 and CCL2. Results are mean±s.e.m. of six animals in each arthritic group and five non-arthritic animals. ^*P<0.01 compared to non-arthritic animals (control (cont)); ^#P<0.01 compared to vehicle-treated arthritic (vehicle (veh)) rats. For experiments in (a), comparisons were made between areas under the curve.

Figure 3

Effects of the treatment with DF 2162, metabolite 1, metabolite 2, anti-TNF-α or anti-CINC-1 in a model of adjuvant-induced arthritis in rats. Representative photographs of hematoxylin and eosin (H&E)-stained sections ( × 200) of tibiotarsal joints of arthritic animals at day 16 after arthritis induction. Note the marked inflammatory infiltrate (arrows) and tissue destruction in vehicle-treated animals (b, arthritis) when compared to non-arthritic animals (a). Also note the beneficial effects of the treatment with DF 2162 (c), metabolite 1 (d) and anti-TNF-α antibody (e). Treatment with anti-CINC-1 (f) and metabolite 2 (g) were less effective. See the text for detailed description of the effects of the various treatments. The pictures were labelled as follows to point out the changes: S (synovium), Bo_Ta (tarsal bone), Bo_Ti (tibial bone) and Ca (cartilage).

Figure 4

Effects of the delayed treatment with DF 2162 in a model of adjuvant-induced arthritis in rats. Treatment with DF 2162 (15 mg kg⁻¹, twice daily) from day 13 after induction of disease (see arrow) inhibited the increase (a) in paw volume, (b) neutrophil influx, and local production of (c) TNF-α, IL-1β and (d) the chemokines CCL5 and CCL2. Results are mean±s.e.mean of five animals in each group. ^*P<0.01 when compared to non-arthritic animals (control (cont)); ^#P<0.01 compared to vehicle-treated arthritic (vehicle (veh)) rats. For experiments in (a), comparisons were made between areas under the curve.

Figure 5

Effects of the treatment with the two major metabolites of DF 2162 in a model of adjuvant-induced arthritis in rats. The effects of the treatment with metabolite 1 (3 mg kg⁻¹, twice daily) and metabolite 2 (12 mg kg⁻¹, twice daily) from day 10 after induction of disease (see arrow) on the increase (a) in paw volume, (b) neutrophil influx, and local production of (c) IL-1β are shown in the relevant panels. Results are mean±s.e.mean of five animals in each arthritic group and four non-arthritic animals. ^*P<0.01 compared to non-arthritic animals (control); ^#P<0.01 compared to vehicle-treated arthritic (vehicle) rats. For experiments in (a), comparisons were made between areas under the curve.

Figure 6

Comparative effects of treatment with anti-TNF-α or anti-CINC-1 antibodies in a model of adjuvant-induced arthritis in rats. The effects of the treatment with anti-TNF-α or anti-CINC-1 (5 μl g⁻¹) on days 10 and 13 after induction of disease (see arrow) inhibited the increase (a) in paw volume, (b) neutrophil influx, and local production of (c) TNF-α, (d) IL-1β and the chemokines (e) CCL5 and (f) CCL2. Results are mean±s.e.mean of five animals in each group. ^*P<0.01 compared to non-arthritic animals (control (cont)); ^#P<0.01 compared to rats treated with non-immune serum (vehicle (veh)). For experiments in (a), comparisons were made between areas under the curve.