Anti-inflammatory and analgesic activity of the bradykinin antagonist, icatibant (Hoe 140), against an extract from Porphyromonas gingivalis

Elevated salivary activity of mast cell chymase of periodontitis patients, and a new bradykinin generation cascade, mediating the cross-talks between mast cell and gingival fibroblast

Activated-mast cells (MCs) within gingival-tissue of chronic-periodontitis (CP) patients, release various inflammatory-factors. Bradykinin is a nine-amino-acid peptide and pro-inflammatory mediator, produced through factor-XII-cascade or tryptase-cascade. The ability of MC-chymase in bradykinin generation has not been discussed yet. This study investigated the salivary levels of MC-chymase, high molecular weight kininogen (HMWK) and bradykinin of CP patients; examined the potential of MC-proteases in bradykinin production using biochemistry-models; and explored the effects of bradykinin on gingival fibroblasts (GFs). Saliva-samples were collected; MC-protease activities were detected; HMWK cleavage was assessed by western-blot and SDS-PAGE; bradykinin levels were measured using immunoassay. Primary GFs were extracted and cultured with or without bradykinin; cell-viability, gelatine-zymography and flow-cytometry were applied. Immunocytochemistry and western-blot were used to detect intracellular protein expressions of bradykinin-stimulated GFs. The data showed that the salivary-levels of MC-proteases, bradykinin, HMWK, and lactoferrin of CP-patients were increased. HMWK was cleaved by MC-chymase in-vitro, resulting in bradykinin generation. Bradykinin promoted cell proliferation, cell cycle and matrix-metalloproteinase-2(MMP-2) activity, and increased intracellular expressions of nuclear-factor-kappa-B(NF-κB), focal-adhesion-kinase(FAK), transforming-growth-factor-β(TGF-β), P38, P53 of GFs. MC-chymase promotes bradykinin production to stimulate GFs and to continue inflammation during CP development. A new BK-generation cascade found in this study provides a new basis for the pathogenesis of CP and the mechanism of continuous inflammation. The activation of MC-chymase/bradykinin-generation cascade depends on HMWK level and MC-chymase activity under inflammatory condition. MC-chymase contributes to bradykinin production, mediating the cross-talks between MCs and GFs. MC-chymase can be used as a therapeutic target and a salivary biomarker in this case.

A Comparative Analysis of the Chemical Composition, Anti-Inflammatory, and Antinociceptive Effects of the Essential Oils from Three Species of Mentha Cultivated in Romania

This work was aimed at correlating the chemotype of three Mentha species cultivated in Romania with an in vivo study of the anti-inflammatory and antinociceptive effects of essential oils. The selected species were Mentha piperita L. var. pallescens (white peppermint), Mentha spicata L. subsp. crispata (spearmint), and Mentha suaveolens Ehrh. (pineapple mint). Qualitative and quantitative analysis of the essential oils isolated from the selected Mentha species was performed by gas chromatography coupled with mass spectrometry (GC-MS). The anti-inflammatory activity of the essential oils was determined by the rat paw edema test induced by λ-carrageenan. The antinociceptive effect of the essential oils was evaluated by the writhing test in mice, using 1% (v/v) acetic acid solution administered intraperitonealy and by the hot plate test in mice. The results showed a menthol chemotype for M. piperita pallescens, a carvone chemotype for M. spicata, and a piperitenone oxide chemotype for M. suaveolens. The essential oil from M. spicata L. (EOMSP) produced statistically significant and dose-dependent anti-inflammatory and antinociceptive effects.

Bradykinin Antagonists Have No Analgesic Effect on Incisional Pain

Bradykinin, an endogenous nonapeptide and an important mediator of inflammation, is also implicated in the initiation and maintenance of pain. Both des-Arg(8), Leu(8)-bradykinin (dALBK) and HOE-140, the prototypic bradykinin B1 and B2 receptor antagonists, respectively, have been shown to reduce pain behaviors and inflammation in animal models of persistent nociception. We studied them for activity against incision-induced pain behaviors in a rat model for postoperative pain. A 1-cm plantar incision was made in the hind paw of halothane-anesthetized rats and closed with 5-0 nylon. Withdrawal responses to punctate and nonpunctate mechanical stimuli were tested with von Frey filaments and a plastic disk attached to a von Frey filament, respectively. Withdrawal latency to radiant heat was also tested. Rats were tested 1 day before the incision, 1 h after the incision, and 0.5, 1, 1.5, and 2.5 h after the injection of the drug. They were then retested at the same times before and after the injection of the drug on each of the first 2 postoperative days. The rats received the saline vehicle dALBK (0.1, 0.3, 1.0, or 3.0 mg/kg) or HOE-140 (0.1, 0.3, 1.0, or 3.0 mg/kg) IV. Another group of rats had the drug injected 1 h before incision and tested as above. Statistical significance (P < 0.05) was determined with Kruskal-Wallis test and a two-way analysis of variance. None of the doses of either dALBK or HOE-140 affected the responses to punctate or blunt mechanical stimulation or heat, either as a pretreatment or as a posttreatment. These data support the unique mechanisms for incision-induced pain relative to inflammation-related pain. Although inflammation may represent a component of incisional pain, the etiology of inflammation and its role seem different than in other models.

Mechanisms mediating Porphyromonas gingivalis gingipain RgpA-induced oral mucosa inflammation in vivo

Suffusion of gingipain RgpA (GRgpA) elicited a significant concentration-dependent increase in the clearance of macromolecules from in situ hamster cheek pouch which was attenuated by NPC 17647, a selective bradykinin B(2) receptor antagonist. Leupeptin and a mixture of proteinase inhibitors also attenuated GRgpA-induced responses. These data indicate that GRgpA elicits plasma exudation from in situ oral mucosa in a catalytic site-dependent fashion by elaborating bradykinin.

The nonpeptide B2 receptor antagonist FR173657: inhibition of effects of bradykinin related to its role in nociception

1. The nonpeptide bradykinin B2 receptor antagonist, FR173657 ((E)-3-(6-acetamido-3-pyridyl)-N-[N-(2, 4-dichloro-3-[(2-methyl-8-quinolinyl) oxymethyl] phenyl]-N-methylaminocarbonylmethyl] acrylamide), was tested in models involving bradykinin-induced activation of primary afferent neurones in vitro and in vivo. 2. Bradykinin-induced contractions of the rabbit isolated iris sphincter muscle mediated by tachykinin release from trigeminal afferent neurones were inhibited in a non-competitive manner by FR173657. A pKB value of 7.9 was calculated. Effects of substance P were unaffected by FR173657. 3. Nociceptive behavioural responses following intraplantar injection of bradykinin in unanaesthetized rats were reduced by 0.3 micromol kg(-1) FR173657 s.c. (P < 0.05), and completely abolished by 3 micromol kg(-1) (P < 0.05). Peroral administration of 5 micromol kg(-1) FR173657 abolished the bradykinin effects (P < 0.05); lower doses had no significant effect. 4. Shortening by intraplantar injection of bradykinin of the paw withdrawal latency in response to radiant heat was abolished by 3 micromol kg(-1) FR173657 s.c. (P < 0.05), while 300 nmol kg(-1) had an intermediate effect. Hyperalgesia induced by prostaglandin E2 remained unaffected by FR173657. 5. Blood pressure reflexes following i.p. instillation of bradykinin in anaesthetized rats were inhibited by FR173657 s.c. with an ID50 of 1.1 micromol kg(-1), while the peptidic B2 antagonist icatibant (Hoe-140; D-Arg0-[Hyp3, Thi5, D-Tic7, Oic8]-bradykinin) caused inhibition at significantly lower doses (ID50 8.5 nmol kg(-1) P < 0.001). Responses to hydrochloric acid i.p. remained unaffected by FR173657. 6. FR173657 or similar nonpeptide compounds may be useful for the development of drugs for diseases involving pain induced by the release of endogenous kinins, i.e. especially in acute inflammatory conditions.

Mutations in the B2 bradykinin receptor reveal a different pattern of contacts for peptidic agonists and peptidic antagonists

The B2 bradykinin receptor, a seven-helix transmembrane receptor, binds the inflammatory mediator bradykinin (BK) and the structurally related peptide antagonist HOE-140. The binding of HOE-140 and the binding of bradykinin are mutually exclusive and competitive. Fifty-four site-specific receptor mutations were made. BK's affinity is reduced 2200-fold by F261A, 490-fold by T265A, 60-fold by D286A, and 3-10-fold by N200A, D268A, and Q290A. In contrast, HOE-140 affinity is reduced less than 7-fold by F254A, F261A, Y297A, and Q262A. The almost complete discordance of mutations that affect BK binding versus HOE-140 binding is surprising, but it was paralleled by the effect of single changes in BK and HOE-140. [Ala9]BK and [Ala6]BK are reduced in receptor binding affinity 27,000- and 150-fold, respectively, while [Ala9]HOE-140 affinity is reduced 7-fold and [Ala6]HOE-140 affinity is unchanged. NMR spectroscopy of all of the peptidic analogs of BK or HOE-140 revealed a beta-turn at the C terminus. Models of the receptor-ligand complex suggested that bradykinin is bound partially inside the helical bundle of the receptor with the amino terminus emerging from the extracellular side of helical bundle. In these models a salt bridge occurs between Arg9 and Asp286; the models also place Phe8 in a hydrophobic pocket midway through the transmembrane region. Models of HOE-140 binding to the receptor place its beta-turn one alpha-helical turn deeper and closer to helix 7 and helix 1 as compared with bradykinin-receptor complex models.