Fasitibant chloride, a kinin B₂ receptor antagonist, and dexamethasone interact to inhibit carrageenan-induced inflammatory arthritis in rats

Abstract

Background and purpose: Bradykinin, through the kinin B₂ receptor, is involved in inflammatory processes related to arthropathies. B₂ receptor antagonists inhibited carrageenan-induced arthritis in rats in synergy with anti-inflammatory steroids. The mechanism(s) underlying this drug interaction was investigated.

Experimental approach: Drugs inhibiting inflammatory mediators released by carrageenan were injected, alone or in combination, into the knee joint of pentobarbital anaesthetized rats 30 min before intra-articular administration of carrageenan. Their effects on the carrageenan-induced inflammatory responses (joint pain, oedema and neutrophil recruitment) and release of inflammatory mediators (prostaglandins, IL-1β, IL-6 and the chemokine GRO/CINC-1), were assessed after 6 h.

Key results: The combination of fasitibant chloride (MEN16132) and dexamethasone was more effective than each drug administered alone in inhibiting knee joint inflammation and release of inflammatory mediators. Fasitibant chloride, MK571, atenolol, des-Arg⁹-[Leu⁸]-bradykinin (B₂ receptor, leukotriene, catecholamine and B₁ receptor antagonists, respectively) and dexketoprofen (COX inhibitor), reduced joint pain and, except for the latter, also diminished joint oedema. A combination of drugs inhibiting joint pain (fasitibant chloride, des-Arg⁹-[Leu⁸]-bradykinin, dexketoprofen, MK571 and atenolol) and oedema (fasitibant chloride, des-Arg⁹-[Leu⁸]-bradykinin, MK571 and atenolol) abolished the respective inflammatory response, producing inhibition comparable with that achieved with the combination of fasitibant chloride and dexamethasone. MK571 alone was able to block neutrophil recruitment.

Conclusions and implications: Bradykinin-mediated inflammatory responses to intra-articular carrageenan were not controlled by steroids, which were not capable of preventing bradykinin effects either by direct activation of the B₂ receptor, or through the indirect effects mediated by release of eicosanoids and cytokines.

Figure 1

Carrageenan-induced knee joint incapacitation, 6 h after its intra-articular administration in rats. Right knee, 30 min before injection of saline (control group) or λ-carrageenan (2%, 25 µL), received, alone or in combination, fasitibant chloride (100 µg), dexamethasone (100 µg), dexketoprofen (300 µg), des-Arg⁹-[Leu⁸]-bradykinin (DALBK; 100 µg), atenolol (50 µg) or MK571 (100 µg). Data are the mean ± SEM of 6–12 rats. °P < 0.05, significantly different from the control group; unpaired Student's t-test and *P < 0.05, significantly different from the carrageenan-treated group; one-way anova followed by Dunnett's post-test. Dotted lines indicate the control value (upper) and the response after carrageenan treatment (lower).

Figure 2

Carrageenan-induced knee joint oedema 6 h after its intra-articular administration in rats. Right knee, 30 min before injection of saline (control group) or λ-carrageenan (2%, 25 µL), received, alone or in combination, fasitibant chloride (100 µg), dexamethasone (100 µg), dexketoprofen (300 µg), des-Arg⁹-[Leu⁸]-bradykinin (DALBK; 100 µg), atenolol (50 µg) or MK571 (100 µg). Data are the mean ± SEM of 6–12 rats. °P < 0.05, significantly different from the control group; unpaired Student's t-test and *P < 0.05, significantly different from the carrageenan-treated group; one-way anova followed by Dunnett's post-test. Dotted lines indicate the control value (lower) and the response after carrageenan treatment (upper).

Figure 3

Carrageenan-induced neutrophil infiltration, measured as MPO activity in the synovial capsule homogenates, 6 h after its intra-articular administration in rats. Right knee, 30 min before injection of saline (control group) or λ-carrageenan (2%, 25 µL), received, alone or in combination, fasitibant chloride (100 µg), dexamethasone (100 µg), dexketoprofen (300 µg), des-Arg⁹-[Leu⁸]-bradykinin (DALBK; 100 µg), atenolol (50 µg) or MK571 (100 µg). Data are the mean ± SEM of 6–12 rats. °P < 0.05, significantly different from the control group; unpaired Student's t-test and *P < 0.05, significantly different from the carrageenan-treated group; one-way anova followed by Dunnett's post-test. Dotted lines indicate the control value (lower) and the response after carrageenan treatment (upper).

Figure 4

Carrageenan-induced prostaglandin release in the synovial fluid. Carrageenan (2%, 25 µL) or saline (control group) were injected into the right knee of rats. After 6 h, a joint lavage was performed by saline perfusion and synovial levels of prostaglandin E metabolites (PGEMs) were measured. Fasitibant chloride (100 µg), dexamethasone (100 µg) or dexketoprofen (300 µg) were given alone or in combination in the right knee, 30 min before carrageenan administration. Data are the mean ± SEM of 10 rats. °P < 0.05, significantly different from the control group; unpaired Student's t-test and *P < 0.05, significantly different from the carrageenan-treated group; one-way anova followed by Dunnett's post-test.

Figure 5

Carrageenan-induced cytokine release in the synovium. Carrageenan (2%, 25 µL) or saline (control group) were injected into the right knee of rats. After 6 h, the levels of IL-1β, IL-6 and GRO/CINC-1 (rat orthologue of human IL-8) were measured in the synovial capsule homogenates. Fasitibant chloride (100 µg) or dexamethasone (100 µg) were given alone or in combination in the right knee, 30 min before carrageenan administration. Data are the mean ± SEM of 10 rats. °P < 0.05, significantly different from the control group; unpaired Student's t-test and *P < 0.05, significantly different from the carrageenan-treated group; one-way anova followed by Dunnett's post-test).

Figure 6

Diagram representing the inflammatory pathways activated by intra-articular carrageenan. B₂R, kinin B₂ receptor; dABK, des-Arg⁹-bradykinin; LT, leukotrienes; PG, prostaglandins; SA, sympathetic amines.