Functionalized Nanogels with Endothelin-1 and Bradykinin Receptor Antagonist Peptides Decrease Inflammatory and Cartilage Degradation Markers of Osteoarthritis in a Horse Organoid Model of Cartilage.

Osteoarthritis (OA) is a degenerative and heterogeneous disease that affects all types of joint structures. Current clinical treatments are only symptomatic and do not manage the degenerative process in animals or humans. One of the new orthobiological treatment strategies being developed to treat OA is the use of drug delivery systems (DDS) to release bioactive molecules over a long period of time directly into the joint to limit inflammation, control pain, and reduce cartilage degradation. Two vasoactive peptides, endothelin-1 and bradykinin, play important roles in OA pathogenesis. In this study, we investigated the effects of two functionalized nanogels as DDS. We assessed the effect of chitosan functionalized with a type A endothelin receptor antagonist (BQ-123-CHI) and/or hyaluronic acid functionalized with a type B1 bradykinin receptor antagonist (R-954-HA). The biocompatibility of these nanogels, alone or in combination, was first validated on equine articular chondrocytes cultured under different oxic conditions. Further, in an OA equine organoid model via induction with interleukin-1 beta (IL-1ß), a combination of BQ-123-CHI and R-954-HA (BR5) triggered the greatest decrease in inflammatory and catabolic markers. In basal and OA conditions, BQ-123-CHI alone or in equimolar combinations with R-954-HA had weak pro-anabolic effects on collagens synthesis. These new nanogels, as part of a composite DDS, show promising attributes for treating OA.

The Effect of the Angiotensin-Converting Enzyme Inhibitor on Bone Health in Castrated Hypertensive Rats Is Mediated via the Kinin-Kallikrein System.

Background: In previous studies, angiotensin-converting enzyme inhibitor (ACEI) use was associated with increased bone loss, while an angiotensin II type I receptor blocker had no effect on bone loss in elder subjects, which suggested that the effect of ACEI on bone loss was not mediated through the classical renin-angiotensin system. In this study, we set to investigate whether the effect of ACEI on bone deterioration was mediated via the kinin-kallikrein system. Methods: Six-month-old male and female spontaneously hypertensive rats were used. The effect of captopril on blood pressure, serum Ang II, and bradykinin concentration was measured in intact rats. Ovariectomy and orchidectomy were performed to establish an osteoporosis model in female and male rats, respectively. Captopril and the bradykinin receptor blocker icatibant (HOE140) were administered after operation for 12 weeks. Serum Ang II and bradykinin concentration, bone turnover markers, bone mineral density (BMD), and bone microarchitecture were evaluated. Femur samples were subjected to a mechanical test. Results: Captopril decreased blood pressure and serum Ang II concentration and increased serum bradykinin concentration in intact rats (P < 0.05). After castration, captopril decreased serum Ang II concentration (P < 0.05); in female rats, icatibant increased serum Ang II concentration (P < 0.05). Captopril increased serum bradykinin concentration (P < 0.05); in male rats, icatibant decreased serum bradykinin concentration (P < 0.05). Captopril increased the rat urine deoxypyridinoline-creatinine ratio (DPD/Cr) and serum osteocalcin concentration (P < 0.05). Icatibant decreased urine DPD/Cr in male rats (P < 0.05) and increased osteocalcin concentration in female rats (P < 0.05). Captopril increased cancellous BMD in castrated hypertensive rats (P < 0.05), and icatibant further increased cancellous BMD (P < 0.05), which was due to the increased trabecular bone number. In mechanical testing, ACEI increased bone strength (P < 0.05), and icatibant further improved it (P < 0.05). Conclusion: ACEI decreased bone deterioration in both male and female hypertensive rats, and the bradykinin receptor blocker further decreased bone deterioration.

In vitro pharmacological profile of PHA-022121, a small molecule bradykinin B2 receptor antagonist in clinical development.

PHA-022121 is a novel small molecule bradykinin B2 receptor antagonist, in clinical development for the treatment and prevention of hereditary angioedema attacks. The present study describes the in vitro pharmacological characteristics of PHA-022121 and its active metabolite, PHA-022484 (M2-D). In mammalian cell lines, PHA-022121 and PHA-022484 show high affinity for the recombinant human bradykinin B2 receptor with Ki values of 0.47 and 0.70 nM, respectively, and potent antagonism of the human bradykinin B2 receptor with Kb values of 0.15 and 0.26 nM, respectively (calcium mobilization assay). Antagonist potency at the recombinant cynomolgus monkey bradykinin B2 receptor is similarly high (Kb values of 1.42 and 1.12 nM for PHA-022121 and PHA-022484, respectively), however, potency at rat, mouse, rabbit and dog bradykinin B2 receptors is at least 100-fold lower than the potency at the human receptor for both compounds. In the human umbilical vein contractility assay, both PHA-022121 and PHA-022484 show a potent, surmountable and reversible B2 antagonist activity with pA2 values of 0.35 and 0.47 nM, respectively. The in vitro off-target profile of PHA-022121 and PHA-022484 demonstrates a high degree of selectivity over a wide range of molecular targets, including the bradykinin B1 receptor. It is concluded that PHA-022121 is a novel, low-molecular weight, competitive antagonist of the human bradykinin B2 receptor with high affinity, high antagonist potency, and high selectivity. It is about 20-fold more potent than icatibant at the human bradykinin B2 receptor as assessed using recombinant or endogenously expressed receptors.

Novel Bradykinin Receptor Inhibitors Inhibit Proliferation and Promote the Apoptosis of Hepatocellular Carcinoma Cells by Inhibiting the ERK Pathway.

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. Studies have shown that bradykinin (BK) is highly expressed in liver cancer. We designed the novel BK receptor inhibitors J051-71 and J051-105, which reduced the viability of liver cancer cells and inhibited the formation of cancer cell colonies. J051-71 and J051-105 reduced cell proliferation and induced apoptosis in HepG2 and BEL-7402 cells, which may be due to the inhibition of the extracellular regulated protein kinase (ERK) signaling pathway. In addition, these BK receptor inhibitors reversed the cell proliferation induced by BK in HepG2 and BEL-7402 cells by downregulating B1 receptor expression. Inhibiting B1 receptor expression decreased the protein levels of p-ERK and reduced the malignant progression of HCC, providing a potential target for HCC therapy.

Bradykinin Receptors Play a Critical Role in the Chronic Post-ischaemia Pain Model.

Complex regional pain syndrome type-I (CRPS-I) is a chronic painful condition resulting from trauma. Bradykinin (BK) is an important inflammatory mediator required in acute and chronic pain response. The objective of this study was to evaluate the association between BK receptors (B1 and B2) and chronic post-ischaemia pain (CPIP) development in mice, a widely accepted CRPS-I model. We assessed mechanical and cold allodynia, and paw oedema in male and female Swiss mice exposed to the CPIP model. Upon induction, the animals were treated with BKR antagonists (HOE-140 and DALBK); BKR agonists (Tyr-BK and DABK); antisense oligonucleotides targeting B1 and B2 and captopril by different routes in the model (7, 14 and 21 days post-induction). Here, we demonstrated that treatment with BKR antagonists, by intraperitoneal (i.p.), intraplantar (i.pl.), and intrathecal (i.t.) routes, mitigated CPIP-induced mechanical allodynia and oedematogenic response, but not cold allodynia. On the other hand, i.pl. administration of BKR agonists exacerbated pain response. Moreover, a single treatment with captopril significantly reversed the anti-allodynic effect of BKR antagonists. In turn, the inhibition of BKRs gene expression in the spinal cord inhibited the nociceptive behaviour in the 14th post-induction. The results of the present study suggest the participation of BKRs in the development and maintenance of chronic pain associated with the CPIP model, possibly linking them to CRPS-I pathogenesis.

Penicillin causes non-allergic anaphylaxis by activating the contact system.

Immediate hypersensitivity reaction (IHR) can be divided into allergic- and non-allergic-mediated, while "anaphylaxis" is reserved for severe IHR. Clinically, true penicillin allergy is rare and most reported penicillin allergy is "spurious". Penicillin-initiated anaphylaxis is possible to occur in skin test- and specific IgE-negative patients. The contact system is a plasma protease cascade initiated by activation of factor XII (FXII). Many agents with negative ion surface can activate FXII to drive contact system. Our data showed that penicillin significantly induced hypothermia in propranolol- or pertussis toxin-pretreated mice. It also caused a rapid and reversible drop in rat blood pressure, which did not overlap with IgE-mediated hypotension. These effects could be countered by a bradykinin-B2 receptor antagonist icatibant, and consistently, penicillin indeed increased rat plasma bradykinin. Moreover, penicillin not only directly activated contact system FXII-dependently, but also promoted bradykinin release in plasma incubated-human umbilical vein endothelial cells. In fact, besides penicillin, other beta-lactams also activated the contact system in vitro. Since the autoactivation of FXII can be affected by multiple-factors, plasma from different healthy individuals showed vastly different amidolytic activity in response to penicillin, suggesting the necessity of determining the potency of penicillin to induce individual plasma FXII activation. These results clarify that penicillin-initiated non-allergic anaphylaxis is attributed to contact system activation, which might bring more effective diagnosis options for predicting penicillin-induced fatal risk and avoiding costly and inappropriate treatment clinically.

Bradykinin Exerts Independent Effects on Trophoblast Invasion and Blood Pressure in Pregnant Guinea Pigs.

INTRODUCTION: The pleiotropic kininogen-kallikrein-kinin system is upregulated in pregnancy and localizes in the uteroplacental unit. To identify the systemic and local participation of the bradykinin type 2 receptor (B2R), this was antagonized by Bradyzide (BDZ) during 2 periods: from days 20 to 34 and from days 20 to 60 in pregnant guinea pigs. METHODS: Pregnant guinea pigs received subcutaneous infusions of saline or BDZ from gestational day 20 until sacrifice on day 34 (Short B2R Antagonism [SH-B2RA]) or on day 60 (Prolonged B2R Antagonism [PR-B2RA]). In SH-BDZA, systolic blood pressure was determined on day 34, while in PR-BDZA it was measured preconceptionally, at days 40 and 60. On gestational day 60, plasma creatinine, uricemia, proteinuria, fetal, placental and maternal kidney weight, and the extent of trophoblast invasion were evaluated. RESULTS: The SH-B2RA increased systolic blood pressure on day 34 and reduced trophoblast myometrial invasion, spiral artery remodeling, and placental sufficiency. The PR-B2RA suppressed the normal blood pressure fall observed on days 40 and 60; vascular transformation, placental efficiency, urinary protein, serum creatinine, and uric acid did not differ between the groups. The proportion of all studied mothers with lost fetuses was greater under BDZ infusion than in controls. CONCLUSION: The increased systolic blood pressure and transient reduction in trophoblast invasion and fetal/placental weight in the SH-B2R blockade and the isolated impact on blood pressure in the PR-B2R blockade indicate that bradykinin independently modulates systemic hemodynamics and the uteroplacental unit through cognate vascular and local B2R receptors.

ACE-Triggered Hypertension Incites Stroke: Genetic, Molecular, and Therapeutic Aspects.

Stroke is the second largest cause of death worldwide. Angiotensin converting enzyme (ACE) gene has emerged as an important player in the pathogenesis of hypertension and consequently stroke. It encodes ACE enzyme that converts the inactive decapeptide angiotensin I to active octapeptide, angiotensin II (Ang II). Dysregulation in the expression of ACE gene, on account of genetic variants or regulation by miRNAs, alters the levels of ACE in the circulation. Variable expression of ACE affects the levels of Ang II. Ang II acts through different signal transduction pathways via various tyrosine kinases (receptor/non-receptor) and protein serine/threonine kinases, initiating a downstream cascade of molecular events. In turn these activated molecular pathways might lead to hypertension and inflammation thereby resulting in cardiovascular and cerebrovascular diseases including stroke. In order to regulate the overexpression of ACE, many ACE inhibitors and blockers have been developed, some of which are still under clinical trials.

Pulsatile antagonism on bradykinin 2-receptor (BK2R) by icatibant triggers the most effective kinin-dependent post-conditioning on rat hearts.

OBJECTIVE: Pharmacological post-conditioning (PC) by intermittent but not continuous administration of exogenous bradykinin (BK) reduces ischemia/reperfusion (I/R) injury via the Reperfusion Injury Salvage Kinase (RISK) pathway activation. We evaluated whether intermittent administration with icatibant (HOE140), a BK2R antagonist, may represent an effective PC strategy, with the advantage of limiting the potential risks of supra-physiologic BK activity. MATERIALS AND METHODS: Hearts from male Sprague-Dawley (SD) rats on a Langendorff system were exposed to I/R injury (30/120 min). BK (100 nM) and HOE140 (1 µM) were administered post-ischemically during the first 3 min of reperfusion, under continuous or intermittent infusion (10 s/each). Hearts were randomly assigned to 5 groups: 1) I/R alone (n=5); 2) continuous HOE140 (cHOE n=6); 3) intermittent HOE140 (iHOE n=6); 4) continuous BK (cBK n=6); 5) intermittent BK (iBK n=6). End-diastolic left ventricular pressure (LVEDP), developed left ventricular pressure (dLVP) and coronary flow (CF) were monitored throughout reperfusion. Left ventricular infarct mass (IM) was quantified together with the phosphorylated levels of Akt and GSK3ß (RISK pathway kinases) at the end of reperfusion. RESULTS: IM was not significantly changed in cBK or cHOE groups (vs. I/R). Conversely, both iBK and iHOE groups showed a significant limitation in IM (vs. I/R, p<0.05, p<0.01, respectively). Akt and GSK3ß phosphorylation levels were higher in iBK and iHOE groups (vs. I/R, p<0.05). When compared to I/R group, both LVEDP values (p<0.05, first 60-min reperfusion), as well as dLVP values (p<0.01) were improved only in iHOE group. CF values did not vary among all groups. CONCLUSIONS: In isolated rat hearts, intermittent modulation of the endogenous kallikrein-kinin system by a selective BK2R antagonist mediates PC cardioprotection via RISK signaling.

Small molecule BKM1972 inhibits human prostate cancer growth and overcomes docetaxel resistance in intraosseous models.

Bone metastasis is a major cause of prostate cancer (PCa) mortality. Although docetaxel chemotherapy initially extends patients' survival, in most cases PCa becomes chemoresistant and eventually progresses without a cure. In this study, we developed a novel small-molecule compound BKM1972, which exhibited potent in vitro cytotoxicity in PCa and other cancer cells regardless of their differences in chemo-responsiveness. Mechanistic studies demonstrated that BKM1972 effectively inhibited the expression of anti-apoptotic protein survivin and membrane-bound efflux pump ATP binding cassette B 1 (ABCB1, p-glycoprotein), presumably via signal transducer and activator of transcription 3 (Stat3). BKM1972 was well tolerated in mice and as a monotherapy, significantly inhibited the intraosseous growth of chemosensitive and chemoresistant PCa cells. These results indicate that BKM1972 is a promising small-molecule lead to treat PCa bone metastasis and overcome docetaxel resistance.

The kallikrein-Kinin system modulates the progression of colorectal liver metastases in a mouse model.

BACKGROUND: The Kallikrein-Kinin System (KKS) has been found to play a role in tumor progression in several cancers. The KKS metabolic cascade depends on signalling through two cross talking receptors; bradykinin receptor 1 (B1R) and bradykinin receptor 2 (B2R). Activation of the Kinin receptor is responsible for multiple pathophysiologic functions including increase of vascular permeability and induction of host inflammatory responses that exert diverse effects on tumor growth. METHODS: B1R and B2R expression on mouse and human CRC cell lines was investigated. Changes in tumor growth and progression was assessed in male CBA mice bearing colorectal liver metastases (CRLM) following treatment with B1R or B2R blockers. In vitro cultures of human SW-480 and mouse colorectal cancer (MoCR) cell lines were examined for changes in their proliferation and migration properties following treatment with B1R or B2R blockers. RESULTS: Both colorectal cancer cell lines tested strongly positive for B1R and B2R expression. Inhibition of both receptors retarded tumor growth but only B1R blockade significantly reduced tumor load and increased tumor apoptosis. Blockade of either receptor reduced tumor vascularization in vivo and significantly inhibited proliferation and migration of colorectal cancer cells in vitro. CONCLUSION: Taken together, the present study demonstrated that kinin receptor blockade inhibited tumor growth and reduced its invading properties suggesting that KKS manipulation could be a novel target in colorectal cancer therapy.

Multiple Inhibitory Mechanisms of Lidocaine on Bradykinin Receptor Activity in Model Sensory Neurons.

BACKGROUND AND OBJECTIVES: Local anesthetics (LAs) are often infiltrated subcutaneously for localized perioperative numbing. In addition to blocking nerve conduction, LAs act on pathways used by a variety of pain-inducing and inflammatory mediators. We describe the effects in isolated model sensory neurons of LAs on responses to the algogenic and sensitizing peptide, bradykinin (BK). METHODS: ND/7 sensory neurons were stimulated by different concentrations of BK in the presence or absence of LAs, with transient increases in intracellular calcium (Δ[Ca]in) detected fluorometrically in fields of cells. Equilibrium saturable binding of radiolabeled BK also was conducted on the same type of cells, with and without LA. RESULTS: Responses to low BK (5 nM) were inhibited by lidocaine at 1 mM (approximately 35% inhibition) and 10 mM (approximately 70% inhibition), whereas responses to high BK (100 nM) were unaffected by 1 mM yet inhibited (approximately 75%) by 10 mM lidocaine. Bupivacaine (1 and 2 mM) did not reduce peak Δ[Ca]in (using 5 nM BK). Lidocaine's quaternary derivative, QX-314 (10 mM), also was ineffective on peak Ca (5 nM BK). Saturation binding of BK showed that lidocaine lowered the binding capacity (Bmax) without changing the KD, consistent with noncompetitive inhibition. CONCLUSIONS: At subclinical concentrations, lidocaine suppresses BK's activation of model sensory neurons. This effect adds to the known analgesic mechanisms of LAs and likely contributes to the reduction of postincisional pain.

Ex vivo study of human visceral nociceptors.

OBJECTIVE: The development of effective visceral analgesics free of deleterious gut-specific side effects is a priority. We aimed to develop a reproducible methodology to study visceral nociception in human tissue that could aid future target identification and drug evaluation. DESIGN: Electrophysiological (single unit) responses of visceral afferents to mechanical (von Frey hair (VFH) and stretch) and chemical (bradykinin and ATP) stimuli were examined. Thus, serosal afferents (putative nociceptors) were used to investigate the effect of tegaserod, and transient receptor potential channel, vanilloid 4 (TRPV4) modulation on mechanical responses. RESULTS: Two distinct afferent fibre populations, serosal (n=23) and muscular (n=21), were distinguished based on their differences in sensitivity to VFH probing and tissue stretch. Serosal units displayed sensitivity to key algesic mediators, bradykinin (6/14 units tested) and ATP (4/10), consistent with a role as polymodal nociceptors, while muscular afferents are largely insensitive to bradykinin (0/11) and ATP (1/10). Serosal nociceptor mechanosensitivity was attenuated by tegaserod (-20.8±6.9%, n=6, p<0.05), a treatment for IBS, or application of HC067047 (-34.9±10.0%, n=7, p<0.05), a TRPV4 antagonist, highlighting the utility of the preparation to examine the mechanistic action of existing drugs or novel analgesics. Repeated application of bradykinin or ATP produced consistent afferent responses following desensitisation to the first application, demonstrating their utility as test stimuli to evaluate analgesic activity. CONCLUSIONS: Functionally distinct subpopulations of human visceral afferents can be demonstrated and could provide a platform technology to further study nociception in human tissue.

A cyclic pathway of P2 × 7, bradykinin, and dopamine receptor activation induces a sustained articular hyperalgesia in the knee joint of rats.

OBJECTIVE: We investigated whether: (1) P2 × 7 receptor activation by its agonist (BzATP) induces articular hyperalgesia in the rat's knee joint via inflammatory mechanisms and (2) activation of P2 × 7 receptors by endogenous ATP contributes to the articular hyperalgesia induced by bradykinin, TNF-α, IL-1ß, CINC-1, PGE2, and dopamine. METHODS: The articular hyperalgesia was quantified using the rat knee joint incapacitation test. The knee joint inflammation, characterized by the concentration of pro-inflammatory cytokines and by neutrophil migration, was quantified in the synovial lavage fluid by ELISA and myeloperoxidase enzyme activity assay, respectively. RESULTS: BzATP induced a dose-dependent articular hyperalgesia in the rat's knee joint that was significantly reduced by the selective antagonists for P2 × 7, bradykinin B1 or B2 receptors, ß1 or ß2 adrenoceptors, and by pre-treatment with Indomethacin. BzATP induced a local increase of TNF-α, IL-1ß, IL-6, and CINC-1 concentration and neutrophil migration into the knee joint. The co-administration of the selective P2 × 7 receptor antagonist A-740003 significantly reduced the articular hyperalgesia induced by bradykinin and dopamine, but not by TNF-α, IL-1ß, CINC-1, and PGE2. CONCLUSIONS: P2 × 7 receptor activation induces articular hyperalgesia mediated by the previous inflammatory mediator release. P2 × 7 receptor-induced articular hyperalgesia is sustained by the involvement of this purinergic receptor in bradykinin and dopamine-induced hyperalgesia in the knee joint.

Modulation of cardiac vagal tone by bradykinin acting on nucleus ambiguus.

Bradykinin (BK), a component of the kallikrein-kininogen-kinin system exerts multiple effects via B1 and B2 receptor activation. In the cardiovascular system, bradykinin has cardioprotective and vasodilator properties. We investigated the effect of BK on cardiac-projecting neurons of nucleus ambiguus, a key site for the parasympathetic cardiac regulation. BK produced a dose-dependent increase in cytosolic Ca2+ concentration. Pretreatment with HOE140, a B2 receptor antagonist, but not with R715, a B1 receptor antagonist, abolished the response to BK. A selective B2 receptor agonist, but not a B1 receptor agonist, elicited an increase in cytosolic Ca2+ similarly to BK. Inhibition of N-type voltage-gated Ca2+ channels with ω-conotoxin GVIA had no effect on the Ca2+ signal produced by BK, while pretreatment with ω-conotoxin MVIIC, a blocker of P/Q-type of Ca2+ channels, significantly diminished the effect of BK. Pretreatment with xestospongin C and 2-aminoethoxydiphenyl borate, antagonists of inositol 1,4,5-trisphosphate receptors, abolished the response to BK. Inhibition of ryanodine receptors reduced the BK-induced Ca2+ increase, while disruption of lysosomal Ca2+ stores with bafilomycin A1 did not affect the response. BK produced a dose-dependent depolarization of nucleus ambiguus neurons, which was prevented by the B2 receptor antagonist. In vivo studies indicate that microinjection of BK into nucleus ambiguus elicited bradycardia in conscious rats via B2 receptors. In summary, in cardiac vagal neurons of nucleus ambiguus, BK activates B2 receptors promoting Ca2+ influx and Ca2+ release from endoplasmic reticulum, and membrane depolarization; these effects are translated in vivo by bradycardia.

Simultaneous comparisons of treatments at multiple time points: Combined marginal models versus joint modeling.

We discuss several aspects of multiple inference in longitudinal settings, focusing on many-to-one and all-pairwise comparisons of (a) treatment groups simultaneously at several points in time, or (b) time points simultaneously for several treatments. We assume a continuous endpoint that is measured repeatedly over time and contrast two basic modeling strategies: fitting a joint model across all occasions (with random effects and/or some residual covariance structure to account for heteroscedasticity and serial dependence), and a novel approach combining a set of simple marginal, i.e. occasion-specific models. Upon parameter and covariance estimation with either modeling approach, we employ a variant of multiple contrast tests that acknowledges correlation between time points and test statistics. This method provides simultaneous confidence intervals and adjusted p-values for elementary hypotheses as well as a global test decision. We compare via simulation the powers of multiple contrast tests based on a joint model and multiple marginal models, respectively, and quantify the benefit of incorporating longitudinal correlation, i.e. the advantage over Bonferroni. Practical application is illustrated with data from a clinical trial on bradykinin receptor antagonism.

Cyclic non-opioid dynorphin A analogues for the bradykinin receptors.

Nerve injury and inflammation cause up-regulation of an endogenous opioid ligand, dynorphin A (Dyn A), in the spinal cord resulting in hyperalgesia via the interaction with bradykinin receptors (BRs). This is a non-opioid neuroexcitatory effect that cannot be blocked by opioid antagonists. Our systematic structure-activity relationships study on Dyn A identified lead ligands 1 and 4, along with the key structural feature (i.e. amphipathicity) for the BRs. However, the ligands showed very low metabolic stability in plasma (t1/2 <1h) and therefore, in order to improve their metabolic stabilities with retained biological activities, various modifications were performed. Cyclization of ligand 4 afforded a cyclic Dyn A analogue 5 that retained the same range of binding affinity as the linear ligand with improved metabolic stability (t1/2 >5h) and therefore possesses the potential as a pharmacophoric scaffold to be utilized for drug development.

Bradykinin receptor blockade restores the baroreflex control of renal sympathetic nerve activity in cisplatin-induced renal failure rats.

AIM: This study investigated the effect of renal bradykinin B1 and B2 receptor blockade on the high- and low-pressure baroreceptor reflex regulation of renal sympathetic nerve activity (RSNA) in rats with cisplatin-induced renal failure. METHODS: Cisplatin (5 mg/kg) or saline was given intraperitoneally 4 days prior to study. Following chloralose/urethane anaesthesia, rats were prepared for measurement of mean arterial pressure (MAP), heart rate and RSNA and received intrarenal infusions of either Lys-[des-Arg9 , Leu8 ]-bradykinin (LBK), a bradykinin B1 receptor blocker, or bradyzide (BZ), a bradykinin B2 receptor blocker. RSNA baroreflex gain curves and renal sympatho-inhibitory responses to volume expansion (VE) were obtained. RESULTS: In the control and renal failure groups, basal MAP (89 ± 3 vs. 80 ± 8 mmHg) and RSNA (2.0 ± 0.3 vs. 1.7 ± 0.6 µV.s) were similar but HR was lower in the latter group (331 ± 8 vs. 396 ± 9 beats/min). The baroreflex gain for RSNA in the renal failure rats was 39% (P < 0.05) lower than the control but was restored to normal values following intrarenal infusion of BZ, but not LBK. VE had no effect on MAP or HR but reduced RSNA by some 40% (P < 0.05) in control but not renal failure rats. Intrarenal LBK infusion in the renal failure rats normalized the VE induced renal sympatho-inhibition whereas BZ only partially restored the response. CONCLUSION: These findings suggest that pro-inflammatory bradykinin acting at different receptors within the kidney generates afferent neural signals which impact differentially within the central nervous system on high- and low-pressure regulation of RSNA.

A Role for Bradykinin Signaling in Chronic Vulvar Pain.

Chronic vulvar pain is alarmingly common in women of reproductive age and is often accompanied by psychological distress, sexual dysfunction, and a significant reduction in quality of life. Localized provoked vulvodynia (LPV) is associated with intense vulvar pain concentrated in the vulvar vestibule (area surrounding vaginal opening). To date, the origins of vulvodynia are poorly understood, and treatment for LPV manages pain symptoms, but does not resolve the root causes of disease. Until recently, no definitive disease mechanisms had been identified; our work indicates LPV has inflammatory origins, although additional studies are needed to understand LPV pain. Bradykinin signaling is one of the most potent inducers of inflammatory pain and is a candidate contributor to LPV. We report that bradykinin receptors are expressed at elevated levels in LPV patient versus healthy control vestibular fibroblasts, and patient vestibular fibroblasts produce elevated levels of proinflammatory mediators with bradykinin stimulation. Inhibiting expression of one or both bradykinin receptors significantly reduces proinflammatory mediator production. Finally, we determined that bradykinin activates nuclear factor (NF)κB signaling (a major inflammatory pathway), whereas inhibition of NFκB successfully ablates this response. These data suggest that therapeutic agents targeting bradykinin sensing and/or NFκB may represent new, more specific options for LPV therapy. PERSPECTIVE: There is an unmet need for the development of more effective vulvodynia therapies. As we explore the mechanisms by which human vulvar fibroblasts respond to proinflammatory/propain stimuli, we move closer to understanding the origins of chronic vulvar pain and identifying new therapeutic targets, knowledge that could significantly improve patient care.

Role of selective blocking of bradykinin receptor subtypes in attenuating allergic airway inflammation in guinea pigs.

The present study was designed to evaluate the potential role of bradykinin antagonists (R-715; bradykinin B1 receptor antagonist and icatibant; bradykinin B2 receptor antagonist) in treatment of allergic airway inflammation in comparison to dexamethasone and montelukast. R-715 as dexamethasone significantly decreased peribronchial leukocyte infiltration, bronchoalveolar lavage fluid (BALF) albumin and interleukin 1ß as well as serum OVA-specific IgE level. Also, R-715 like montelukast significantly decreased BALF cell count (total and eosinophils). Icatibant showed negative results. The current findings suggest that selective bradykinin B1 receptor antagonists may have the therapeutic potential for the treatment of allergic airway inflammation.