Evaluation of Novel B1R/B2R Agonists Containing TRIOZAN™ Nanoparticles for Targeted Brain Delivery of Antibodies in a Mouse Model of Alzheimer Disease.

The blood-brain barrier (BBB) is a major obstacle to the development of effective therapeutics for central nervous system (CNS) disorders, including Alzheimer's disease (AD). This has been particularly true in the case of monoclonal antibody (mAbs) therapeutic candidates, due to their large size. To tackle this issue, we developed new nanoformulations, comprising bio-based Triozan polymers along with kinin B1 and B2 receptor (B1R and B2R) peptide agonist analogues, as potent BBB-permeabilizers to enhance brain delivery of a new anti-C1q mAb for AD (ANX005). The prepared B1R/B2R-TRIOZAN™ nanoparticles (NPs) displayed aqueous solubility, B1R/B2R binding capacity and uniform sizes (~130-165 nm). The relative biodistribution profiles of the mAb loaded into these NPs versus the naked mAb were assessed in vivo through two routes of administrations (intravenous (IV), intranasal (IN)) in the Tg-SwDI mouse model of AD. At 24 h post-administration, brain levels of the encapsulated mAb were significantly increased (up to 12-fold (IV) and 5-fold (IN), respectively) compared with free mAb in AD brain affected regions, entorhinal cortex and hippocampus of aged mice. Liver uptakes remained relatively low with similar values for the nanoformulations and free mAb. Our findings demonstrate the potential of B1R/B2R-TRIOZAN™ NPs for the targeted delivery of new CNS drugs, which could maximize their therapeutic effectiveness.

Expression and function of TLR4- induced B1R bradykinin receptor on cardiac fibroblasts.

Cardiac fibroblasts (CF) are key cells for maintaining extracellular matrix (ECM) protein homeostasis in the heart, and for cardiac repair through CF-to-cardiac myofibroblast (CMF) differentiation. Additionally, CF play an important role in the inflammatory process after cardiac injury, and they express Toll like receptor 4 (TLR4), B1 and B2 bradykinin receptors (B1R and B2R) which are important in the inflammatory response. B1R and B2R are induced by proinflammatory cytokines and their activation by bradykinin (BK: B2R agonist) or des-arg-kallidin (DAKD: B1R agonist), induces NO and PGI2 production which is key for reducing collagen I levels. However, whether TLR4 activation regulates bradykinin receptor expression remains unknown. CF were isolated from human, neonatal rat and adult mouse heart. B1R mRNA expression was evaluated by qRT-PCR, whereas B1R, collagen, COX-2 and iNOS protein levels were evaluated by Western Blot. NO and PGI2 were evaluated by commercial kits. We report here that in CF, TLR4 activation increased B1R mRNA and protein levels, as well as COX-2 and iNOS levels. B1R mRNA levels were also induced by interleukin-1α via its cognate receptor IL-1R1. In LPS-pretreated CF the DAKD treatment induced higher responses with respect to those observed in non LPS-pretreated CF, increasing PGI2 secretion and NO production; and reducing collagen I protein levels in CF. In conclusion, no significant response to DAKD was observed (due to very low expression of B1R in CF) - but pre-activation of TLR4 in CF, conditions that significantly enhanced B1R expression, led to an additional response of DAKD.

Kinin-B1 Receptor Stimulation Promotes Invasion and is Involved in Cell-Cell Interaction of Co-Cultured Glioblastoma and Mesenchymal Stem Cells.

Glioblastoma multiforme (GBM) represents the most lethal brain tumour, and these tumours have very limited treatment options. Mesenchymal stem cells (MSC) are considered as candidates for advanced cell therapies, due to their tropism towards GBM, possibly affecting their malignancy, thus also representing a potential therapeutic vector. Therefore, we aimed to compare the effects of bone-marrow-derived versus adipose-tissue-derived MSC (BM-/AT-MSC) on heterogeneous populations of tumour cells. This cells' interplay was addressed by the in-vitro two-dimensional (monolayer) and three-dimensional (spheroid) co-culture models, using U87 and U373 GBM cell lines, expressing genotypically different mesenchymal transcriptome profiles. U87 cell low mesenchymal profile expressed high levels of kinin receptor 1 (B1R) and their invasion was greatly enhanced by the B1R agonist des-Arg9-bradykinin upon BM-MSC co-culturing in 3D co-cultures. This correlated to significantly higher cell-cell interactions in U87/BM-MSC mixed spheroids. This was not observed with the U373 cells and not in AT-MSC co-cultures. Altogether, these data support the on-going exploration of B1R as target for adjuvant approach in GBM therapy. Secondly, the results emphasize the need for further careful exploration of the selectivity regarding the origin of MSC as potential candidates for cell therapies, particular in cancer, where they may adversely affect heterogeneous tumour cell populations.

Kinin Receptors Sensitize TRPV4 Channel and Induce Mechanical Hyperalgesia: Relevance to Paclitaxel-Induced Peripheral Neuropathy in Mice.

Kinin B1 (B1R) and B2 receptors (B2R) and the transient receptor potential vanilloid 4 (TRPV4) channel are known to play a critical role in the peripheral neuropathy induced by paclitaxel (PTX) in rodents. However, the downstream pathways activated by kinin receptors as well as the sensitizers of the TRPV4 channel involved in this process remain unknown. Herein, we investigated whether kinins sensitize TRPV4 channels in order to maintain PTX-induced peripheral neuropathy in mice. The mechanical hyperalgesia induced by bradykinin (BK, a B2R agonist) or des-Arg9-BK (DABK, a B1R agonist) was inhibited by the selective TRPV4 antagonist HC-067047. Additionally, BK was able to sensitize TRPV4, thus contributing to mechanical hyperalgesia. This response was dependent on phospholipase C/protein kinase C (PKC) activation. The selective kinin B1R (des-Arg9-[Leu8]-bradykinin) and B2R (HOE 140) antagonists reduced the mechanical hyperalgesia induced by PTX, with efficacies and time response profiles similar to those observed for the TRPV4 antagonist (HC-067047). Additionally, both kinin receptor antagonists inhibited the overt nociception induced by hypotonic solution in PTX-injected animals. The same animals presented lower PKCε levels in skin and dorsal root ganglion samples. The selective PKCε inhibitor (εV1-2) reduced the hypotonicity-induced overt nociception in PTX-treated mice with the same magnitude observed for the kinin receptor antagonists. These findings suggest that B1R or B2R agonists sensitize TRPV4 channels to induce mechanical hyperalgesia in mice. This mechanism of interaction may contribute to PTX-induced peripheral neuropathy through the activation of PKCε. We suggest these targets represent new opportunities for the development of effective analgesics to treat chronic pain.

Neuroprotective effect of kinin B1 receptor activation in acute cerebral ischemia in diabetic mice.

Activation of the kallikrein-kinin system enhances cardiac and renal tolerance to ischemia. Here we investigated the effects of selective agonists of kinin B1 or B2 receptor (R) in brain ischemia-reperfusion in diabetic and non-diabetic mice. The role of endogenous kinins was assessed in tissue kallikrein deficient mice (TK-/-). Mice underwent 60min-middle cerebral artery occlusion (MCAO), eight weeks after type 1-diabetes induction. Treatment with B1R-, B2R-agonist or saline was started at reperfusion. Neurological deficit (ND), infarct size (IS), brain water content (BWC) were measured at day 0, 1 and 2 after injury. MCAO induced exaggerated ND, mortality and IS in diabetic mice. B2R-agonist increased ND and mortality to 60% and 80% in non-diabetic and diabetic mice respectively, by mechanisms involving hemodynamic failure and renal insufficiency. TK-/- mice displayed reduced ND and IS compared to wild-type littermate, consistent with suppression of B2R activity. B1R mRNA level increased in ischemic brain but B1R-agonist had no effect on ND, mortality or IS in non-diabetic mice. In contrast, in diabetic mice, B1R-agonist tested at two doses significantly reduced ND by 42-52% and IS by 66-71%, without effect on BWC or renal function. This suggests potential therapeutic interest of B1R agonism for cerebral protection in diabetes.

Synthesis and evaluation of a 68Ga-labeled bradykinin B1 receptor agonist for imaging with positron emission tomography.

A novel 68Ga-labeled bradykinin B1 receptor (B1R) agonist, 68Ga-Z01115, was synthesized and evaluated for imaging with positron emission tomography (PET). Z01115 exhibited good binding affinity (Ki=25.4±5.1nM) to hB1R. 68Ga-Z01115 was prepared in 74±5 decay-corrected radiochemical yield with >99% radiochemical purity and 155±89GBq/µmol (4.2±2.4Ci/µmol) specific activity. 68Ga-Z01115 was stable in vitro in mouse plasma (93% remaining intact after 60min incubation), and relatively stable in vivo (51±5% remaining intact at 5min post-injection). PET imaging and biodistribution studies in mice showed that 68Ga-Z01115 cleared rapidly from nontarget tissues/organs, and generated high target-to-nontarget contrast images. The uptake of 68Ga-Z01115 in B1R-positive (B1R+) tumor was 5.65±0.59%ID/g at 1h post-injection. Average contrast ratios of B1R+ tumor-to-B1R- tumor, -to-blood and -to-muscle were 24.3, 24.4 and 82.9, respectively. Uptake of 68Ga-Z01115 in B1R+ tumors was reduced by ∼90% with co-injection of cold standard, confirming it was mediated by B1R. Our data suggest that 68Ga-Z01115 is a promising tracer for imaging the expression of B1R that is overexpressed in a variety of cancers.

The transient receptor potential ankyrin-1 mediates mechanical hyperalgesia induced by the activation of B1 receptor in mice.

The kinin receptor B1 and the transient receptor potential ankyrin 1 (TRPA1) work as initiators and gatekeepers of nociception and inflammation. This study reports that the nociceptive transmission induced by activation of B1 receptor is dependent on TRPA1 ion channel. The mechanical hyperalgesia was induced by intrathecal (i.t.) injection of B1 agonist des-Arginine9-bradykinin (DABK) or TRPA1 agonist cinnamaldehyde and was evaluated by the withdrawal response after von Frey Hair application in the hind paw. After behavioral experiments, lumbar spinal cord and dorsal root ganglia (DRG) were harvested to assess protein expression and mRNA by immunohistochemistry and real time-PCR, respectively. The pharmacological antagonism (HC030031) or the down-regulation of TRPA1 greatly inhibited the mechanical hyperalgesia induced by DABK. Intrathecal injection of DABK up regulated the ionized calcium binding adaptor molecule (Iba-1) in lumbar spinal cord (L5-L6); TRPA1 protein and mRNA in lumbar spinal cord; and B1 receptor mRNA in both lumbar spinal cord and DRG. The knockdown of TRPA1 prevented microglia activation induced by DABK. Furthermore, the mechanical hyperalgesia induced by either DABK or by cinnamaldehyde was significantly reduced by inhibition of cyclooxygenase (COX), protein kinase C (PKC) or phospholipase C (PLC). In summary, this study revealed that TRPA1 positively modulates the mechanical hyperalgesia induced by B1 receptor activation in the spinal cord and that the classical GPCR downstream molecules PLC, diacylglycerol (DAG), 3,4,5-inositide phosphate (IP3) and PKC are involved in the nociceptive transmission triggered by these two receptors.

Activation of the human keratinocyte B1 bradykinin receptor induces expression and secretion of metalloproteases 2 and 9 by transactivation of epidermal growth factor receptor.

The B1 bradykinin receptor (BDKRB1) is a component of the kinin cascade localized in the human skin. Some of the effects produced by stimulation of BDKRB1 depend on transactivation of epidermal growth factor receptor (EGFR), but the mechanisms involved in this process have not been clarified yet. The primary purpose of this study was to determine the effect of a BDKRB1 agonist on wound healing in a mouse model and the migration and secretion of metalloproteases 2 and 9 from human HaCaT keratinocytes and delineate the signalling pathways that triggered their secretion. Although stimulation of BDKRB1 induces weak chemotactic migration of keratinocytes and wound closure in an in vitro scratch-wound assay, the BDKRB1 agonist improved wound closure in a mouse model. BDKRB1 stimulation triggers synthesis and secretion of both metalloproteases, effects that depend on the activity of EGFR and subsequent phosphorylation of ERK1/2 and p38 mitogen-activated protein kinases and PI3K/Akt. In the mouse model, immunoreactivity for both gelatinases was concentrated around wound borders. EGFR transactivation by BDKRB1 agonist involves Src kinases family and ADAM17. In addition to extracellular matrix degradation, metalloproteases 2 and 9 regulate cell migration and differentiation, cell functions that are associated with the role of BDKRB1 in keratinocyte differentiation. Considering that BDKRB1 is up-regulated by inflammation and/or by cytokines that are abundant in the inflammatory milieu, more stable BDKRB1 agonists may be of therapeutic value to modulate wound healing.

Safety and pharmacokinetics of a kinin B1 receptor peptide agonist produced with different counter-ions.

Several studies have shown the potential therapeutic utility of kinin B1 receptor (B1R) peptide agonists in neurological and ischemic cardiovascular diseases and brain cancer. Preclinical safety studies are a prerequisite for further drug development. The objectives of this study were to determine the acute toxicity and pharmacokinetics of the peptide B1R agonist, SarLys[dPhe8]desArg9-bradykinin (NG29), as trifluoroacetate (TFacetate) or acetate salt form, following intravenous injection in rats. A maximum tolerated dose (MTD) of NG29-TFacetate was established at 75 mg/kg from the results of a dose range-finding study (up to 200 mg/kg). The short-term (4-day) repeat-dose toxicity study of NG29, using its MTD value, showed that NG29-acetate exhibited minimal non-adverse clinical pathology changes in hematology, coagulation, clinical chemistry and urine parameters and severe kidney histopathological changes characterized by renal tubular degeneration. No such effects were observed with NG29-TFacetate. At the injection site, NG29-TFacetate was considered to be more locally irritating when compared to the acetate form. The extent of exposure and half-life values of NG29-TFacetate were comparable to the acetate form (AUC0-α of 10.2 mg/l*h vs. 9.9 mg/l*h; T1/2 of 2.3 h vs. 2.4 h). This study shows that in rats NG29-TFacetate exhibits a superior tolerability profile compared with the peptide acetate form.

Intracellular signaling pathways involved in the release of IL-4 and VEGF from human keratinocytes by activation of kinin B1 receptor: functional relevance to angiogenesis.

The injured skin produces a number of mediators that directly or indirectly modulate cell chemotaxis, migration, proliferation, and angiogenesis. Components of the kinin pathway including the kinin B1 receptor (B1R) have been found to occur in the human skin, but information about its role on keratinocyte biology is still scarce. Our aim was to determine whether stimulation of B1R causes the secretion of IL-4 and/or VEGF from human keratinocytes and to evaluate the role of the B1R agonist Lys-des[Arg(9)]bradykinin and IL-4 on various stages of angiogenesis, such as cell migration, proliferation, and release of metalloproteases. By using ELISA and Western blotting, we showed that HaCaT keratinocytes stimulated with the B1R agonist release IL-4 and VEGF. Stimulation of B1R also caused transient c-JunN-terminal kinase phosphorylation and JunB nuclear translocation, transcription factor that regulates IL-4 expression. The 3D-angiogenesis assay, performed on spheroids of EA.hy923 endothelial cells embedded in a collagen matrix, showed that their cumulative sprout area increased significantly following stimulation with either IL-4 or B1R agonist. Furthermore, these ligands produced significant endothelial cell migration and release of metalloproteases 2 and 9, but did not increase endothelial cell proliferation as measured by 5-bromo-2'-deoxyuridine incorporation. Our results provide experimental evidence that establishes IL-4 and B1R agonist as important angiogenic factors of relevance for skin repair.

Human Urinary Kallidinogenase Promotes Angiogenesis and Cerebral Perfusion in Experimental Stroke.

Angiogenesisis a key restorative mechanism in response to ischemia, and pro-angiogenic therapy could be beneficial in stroke. Accumulating experimental and clinical evidence suggest that human urinary kallidinogenase (HUK) improves stroke outcome, but the underlying mechanisms are not clear. The aim of current study was to verify roles of HUK in post-ischemic angiogenesis and identify relevant mediators. In rat middle cerebral artery occlusion (MCAO) model, we confirmed that HUK treatment could improve stroke outcome, indicated by reduced infarct size and improved neurological function. Notably, the 18F-FDG micro-PET scan indicated that HUK enhanced cerebral perfusion in rats after MCAO treatment. In addition, HUK promotespost-ischemic angiogenesis, with increased vessel density as well as up-regulated VEGF andapelin/APJ expression in HUK-treated MCAO mice. In endothelial cell cultures, induction of VEGF and apelin/APJ expression, and ERK1/2 phosphorylation by HUK was further confirmed. These changes were abrogated by U0126, a selective ERK1/2 inhibitor. Moreover, F13A, a competitive antagonist of APJ receptor, significantly suppressed HUK-induced VEGF expression. Furthermore, angiogenic functions of HUK were inhibited in the presence of selective bradykinin B1 or B2 receptor antagonist both in vitro and in vivo. Our findings indicate that HUK treatment promotes post-ischemic angiogenesis and cerebral perfusion via activation of bradykinin B1 and B2 receptors, which is potentially due to enhancement expression of VEGF and apelin/APJ in ERK1/2 dependent way.

Expression and bioregulation of the kallikrein-related peptidases family in the human neutrophil.

The family of kallikrein-related peptidases (KLKs) has been identified in a variety of immunolabeled human tissue sections, but no previous study has experimentally confirmed their presence in the human neutrophil. We have investigated the expression and bioregulation of particular KLKs in the human neutrophil and, in addition, examined whether stimulation by a kinin B(1) receptor (B1R) agonist or fMet-Leu-Phe (fMLP) induces their secretion. Western blot analysis of neutrophil homogenates indicated that the MM of the KLKs ranged from 27 to 50 kDa. RT-PCR showed that blood neutrophils expressed only KLK1, KLK4, KLK10, KLK13, KLK14 and KLK15 mRNAs, whereas the non-differentiated HL-60 cells expressed most of them, with exception of KLK3 and KLK7. Nevertheless, mRNAs for KLK2, KLK5, KLK6 and KLK9 that were previously undetectable appeared after challenging with a mixture of cytokines. Both kinin B(1)R agonist and fMLP induced secretion of KLK1, KLK6, KLK10, KLK13 and KLK14 into the culture medium in similar amounts, whereas the B(1)R agonist caused the release of lower amounts of KLK2, KLK4 and KLK5. When secreted, the differing proteolytic activity of KLKs provides the human neutrophil with a multifunctional enzymatic capacity supporting a new dimension for its role in human disorders of diverse etiology.

Kinin B1 receptor regulates interactions between neutrophils and endothelial cells by modulating the levels of Mac-1, LFA-1 and intercellular adhesion molecule-1.

Kinins are pro-inflammatory peptides that mimic the cardinal features of inflammation. We examined the concept that expression levels of endothelial intercellular adhesion molecule-1 (ICAM-1) and neutrophil integrins Mac-1 and LFA-1 are modulated by the kinin B1 receptor (B1R) agonist, Lys-des[Arg(9)]bradykinin (LDBK). Stimulation of endothelial cells with LDBK increased the levels of ICAM-1 mRNA transcripts/protein, and also of E-selectin and platelet endothelial adhesion molecule-1. ICAM-1 levels increased in a magnitude comparable with that produced by TNF-α. This stimulatory effect was reduced when endothelial cells, which had been previously transfected with a B1R small interfering RNA, were stimulated with LDBK, under comparable conditions. Similarly, LDBK produced a significant increase in protein levels of LFA-1 and Mac-1 integrins in human neutrophils, an effect that was reversed by pretreatment of cells with 10 µg/ml cycloheximide or a B1R antagonist. Functional experiments performed with post-confluent monolayers of endothelial cells stimulated with LDBK and neutrophils primed with TNF-α, and vice versa, resulted in enhanced adhesiveness between both cells. Neutralizing Abs to ICAM-1 and Mac-1 reduced the adhesion between them. Our results indicate that kinin B1R is a novel modulator that promotes adhesion of leukocytes to endothelial cells, critically enhancing the movement of neutrophils from the circulation to sites of inflammation.

Kinin receptor agonism restores hindlimb postischemic neovascularization capacity in diabetic mice.

Limb ischemia is a major complication of thromboembolic diseases. Diabetes worsens prognosis by impairing neovascularization. Genetic or pharmacological inactivation of the kallikrein-kinin system aggravates limb ischemia in nondiabetic animals, whereas angiotensin I-converting enzyme/kininase II inhibition improves outcome. The role of kinins in limb ischemia in the setting of diabetes is not documented. We assessed whether selective activation of kinin receptors by pharmacological agonists can influence neovascularization in diabetic mice with limb ischemia and have a therapeutic effect. Selective pseudopeptide kinin B1 or B2 receptor agonists resistant to peptidase action were administered by osmotic minipumps at a nonhypotensive dosage for 14 days after unilateral femoral artery ligation in mice previously rendered diabetic by streptozotocin. Comparison was made with ligatured, nonagonist-treated nondiabetic and diabetic mice. Diabetes reduced neovascularization, assessed by microangiography and histologic capillary density analysis, by roughly 40%. B1 receptor agonist or B2 receptor agonist similarly restored neovascularization in diabetic mice. Neovascularization in agonist-treated diabetic mice was indistinguishable from nondiabetic mice. Both treatments restored blood flow in the ischemic hindfoot, measured by laser-Doppler perfusion imaging. Macrophage infiltration increased 3-fold in the ischemic gastrocnemius muscle during B1 receptor agonist or B2 receptor agonist treatment, and vascular endothelial growth factor (VEGF) level increased 2-fold. Both treatments increased, by 50-100%, circulating CD45/CD11b-positive monocytes and CD34(+)/VEGFR2(+) progenitor cells. Thus, selective pharmacological activation of B1 or B2 kinin receptor overcomes the effect of diabetes on postischemic neovascularization and restores tissue perfusion through monocyte/macrophage mobilization. Kinin receptors are potential therapeutic targets in limb ischemia in diabetes.

Bioregulation of kallikrein-related peptidases 6, 10 and 11 by the kinin B1 receptor in breast cancer cells.

The sera of patients with breast cancer have higher levels of des[Arg(9)]bradykinin, a kinin B1 receptor (B1R) agonist, than that from healthy individuals. Stimulation of breast cancer cells with the analog Lys-des[Arg(9)]bradykinin causes release of metalloproteinases-2 and -9 and increases cell proliferation. We examined the possibility that breast cancer cells, in addition to B1R, express the kinin-forming protease true tissue kallikrein (KLK1) and the endogenous proteins termed kininogens from which kinins are enzymatically released. Furthermore, we investigated whether stimulation of breast cancer cells with a B1R agonist would modify the cellular levels of KLK6, KLK10 and KLK11, three kallikrein-related peptidases with a still poorly-understood biological role in breast cancer. We found that breast cancer cells expressed KLK1 and kininogens, and that stimulation of estrogen-sensitive breast cancer cells with the B1R agonist produced down-regulation of KLK10 (a protease associated with growth suppression) but up-regulation of KLK11 and KLK6 (peptidases related to increased cell proliferation and invasiveness, respectively). Furthermore, we showed that the B1R agonist acts as a functional stimulus for the secretion of KLK1 and KLK6, an event relevant for kinin production and cell invasion, respectively.

An interaction of renin-angiotensin and kallikrein-kinin systems contributes to vascular hypertrophy in angiotensin II-induced hypertension: in vivo and in vitro studies.

The kallikrein-kinin and renin-angiotensin systems interact at multiple levels. In the present study, we tested the hypothesis that the B1 kinin receptor (B1R) contributes to vascular hypertrophy in angiotensin II (ANG II)-induced hypertension, through a mechanism involving reactive oxygen species (ROS) generation and extracellular signal-regulated kinase (ERK1/2) activation. Male Wistar rats were infused with vehicle (control rats), 400 ng/Kg/min ANG II (ANG II rats) or 400 ng/Kg/min ANG II plus B1 receptor antagonist, 350 ng/Kg/min des-Arg(9)-Leu(8)-bradykinin (ANGII+DAL rats), via osmotic mini-pumps (14 days) or received ANG II plus losartan (10 mg/Kg, 14 days, gavage - ANG II+LOS rats). After 14 days, ANG II rats exhibited increased systolic arterial pressure [(mmHg) 184 ± 5.9 vs 115 ± 2.3], aortic hypertrophy; increased ROS generation [2-hydroxyethidium/dihydroethidium (EOH/DHE): 21.8 ± 2.7 vs 6.0 ± 1.8] and ERK1/2 phosphorylation (% of control: 218.3 ± 29.4 vs 100 ± 0.25]. B1R expression was increased in aortas from ANG II and ANG II+DAL rats than in aortas from the ANG II+LOS and control groups. B1R antagonism reduced aorta hypertrophy, prevented ROS generation (EOH/DHE: 9.17 ± 3.1) and ERK1/2 phosphorylation (137 ± 20.7%) in ANG II rats. Cultured aortic vascular smooth muscle cells (VSMC) stimulated with low concentrations (0.1 nM) of ANG II plus B1R agonist exhibited increased ROS generation, ERK1/2 phosphorylation, proliferating-cell nuclear antigen expression and [H3]leucine incorporation. At this concentration, neither ANG II nor the B1R agonist produced any effects when tested individually. The ANG II/B1R agonist synergism was inhibited by losartan (AT1 blocker, 10 µM), B1R antagonist (10 µM) and Tiron (superoxide anion scavenger, 10 mM). These data suggest that B1R activation contributes to ANG II-induced aortic hypertrophy. This is associated with activation of redox-regulated ERK1/2 pathway that controls aortic smooth muscle cells growth. Our findings highlight an important cross-talk between the DABK and ANG II in the vascular system and contribute to a better understanding of the mechanisms involved in vascular remodeling in hypertension.

Bradykinin-related peptides (BRPs) from skin secretions of three genera of phyllomedusine leaf frogs and their comparative pharmacological effects on mammalian smooth muscles.

While bradykinin has been identified in the skin secretions from several species of amphibian, bradykinin-related peptides (BRPs) are more common constituents. These peptides display a plethora of primary structural variations from the type peptide which include single or multiple amino acid substitutions, N- and/or C-terminal extensions and post-translational modifications such as proline hydroxylation and tyrosine sulfation. Such modified peptides have been reported in species from many families, including Bombinatoridae, Hylidae and Ranidae. The spectrum of these peptides in a given species is thought to be reflective of its predator profile from different vertebrate taxa. Here we report the isolation of BRPs and parallel molecular cloning of their respective biosynthetic precursor-encoding cDNAs from the skin secretions of the Mexican leaf frog (Pachymedusa dacnicolor), the Central American red-eyed leaf frog (Agalychnis callidryas) and the South American orange-legged leaf frog (Phyllomedusa hypochondrialis). Additionally, the eight different BRPs identified were chemically synthesized and screened for bioactivity using four different mammalian smooth muscle preparations and their effects and rank potencies were found to be radically different in these with some acting preferentially through bradykinin B1-type receptors and others through B(2)-type receptors.

Kinin-stimulated B1 receptor signaling depends on receptor endocytosis whereas B2 receptor signaling does not.

Kinins are potent pro-inflammatory peptides that act through two G protein-coupled receptor subtypes, B1 (B1R) and B2 (B2R). Kinin-stimulated B2R signaling is often transient, whereas B1R signaling is sustained. This was confirmed by monitoring agonist-stimulated intracellular Ca(2+) mobilization in A10 smooth muscle cells expressing human wild-type B2R and B1R. We further studied the role of receptor membrane trafficking in receptor-mediated phosphoinositide (PI) hydrolysis in model HEK293 cell lines stably expressing the receptors. Treatment of cells with brefeldin A, to inhibit maturation of de novo synthesized receptors, or hypertonic sucrose, to inhibit receptor endocytosis, showed that the basal cell surface receptor turnover was considerably faster for B1R than for B2R. Inhibition of endocytosis, which stabilized B1R on the cell surface, inhibited B1R signaling, whereas B2R signaling was not perturbed. Signaling by a B1R construct in which the entire C-terminal domain was deleted remained sensitive to inhibition of receptor endocytosis, whereas signaling by a B1R construct in which this domain was substituted with the corresponding domain in B2R was not sensitive. B2R and B1R co-expression, which also appeared to stabilize B1R on the cell surface, presumably by receptor hetero-dimerization, also inhibited B1R signaling, whereas B2R signaling was slightly enhanced. Furthermore, the B2R-specific agonist bradykinin (BK) directed both receptors through a common endocytic pathway, whereas the B1R-specific agonist Lys-desArg(9)-BK was unable to do so. These results suggest that B1R-mediated PI hydrolysis depends on a step in receptor endocytosis, whereas B2R-mediated PI hydrolysis does not. We propose that B1R uses at least part of the endocytic machinery to sustain agonist-promoted signaling.

Bradykinin B1 receptor-mediated vasodilation is impaired in myometrial arteries from women with pre-eclampsia.

OBJECTIVE: To investigate the vascular functional activity, localisation and expression of B1 and B2 kinin receptors in normal pregnancy and pre-eclampsia. METHODS: Kinin receptor-mediated relaxation of myometrial arteries was assessed using wire myography. Immunohistochemical staining and gene expression of kinin receptors in the myometrium was determined. RESULTS: B2 receptor-mediated relaxation was reduced in pre-eclampsia. B1 receptor-mediated relaxation was observed in a proportion of healthy women and was impaired in pre-eclampsia. Receptor expression and localisation was unaltered in pre-eclampsia. CONCLUSION: Here, we demonstrate a novel B1 receptor-mediated vasodilatation in healthy myometrial vessels that is absent in pre-eclampsia.

Dose-depending effect of intracerebroventricularly administered bradykinin on nociception in rats.

BACKGROUND: The effect of small and high doses of intracerebroventricularly (icv) applied bradykinin (BK) on nociception produced by mechanical stimuli and the participation of B1 and B2 receptors in this nociception were investigated in rats. RESULTS: BK at the lowest dose (0.06 µg) produced hyperalgesia whereas at the higher doses (6 and 12 µg) antinociception. This effect was abolished by B1 or B2 receptor antagonists, des-Arg(10)-HOE140 and HOE140 (1 pmol icv), respectively. CONCLUSION: Depending on the dose used, BK produces pro- or anti-nociceptive action. Both B1 and B2 receptors are involved in the action of icv applied BK.