Kinin Levels Research Articles

Kinins' Contribution to Postoperative Pain in an Experimental Animal Model and Its Implications.

Postoperative pain causes discomfort and disability, besides high medical costs. The search for better treatments for this pain is essential to improve recovery and reduce morbidity and risk of chronic postoperative pain. Kinins and their receptors contribute to different painful conditions and are among the main painful inflammatory mediators. We investigated the kinin's role in a postoperative pain model in mice and reviewed data associating kinins with this painful condition. The postoperative pain model was induced by an incision in the mice's paw's skin and fascia with the underlying muscle's elevation. Kinin levels were evaluated by enzyme immunoassays in sham or operated animals. Kinin's role in surgical procedure-associated mechanical allodynia was investigated using systemic or local administration of antagonists of the kinin B1 receptor (DALBk or SSR240612) or B2 receptor (Icatibant or FR173657) and a kallikrein inhibitor (aprotinin). Kinin levels increased in mice's serum and plantar tissue after the surgical procedure. All kinin B1 or B2 receptor antagonists and aprotinin reduced incision-induced mechanical allodynia. Although controversial, kinins contribute mainly to the initial phase of postoperative pain. The kallikrein-kinin system can be targeted to relieve this pain, but more investigations are necessary, especially associations with other pharmacologic targets.

Kinin B1 and B2 receptors mediate cancer pain associated with both the tumor and oncology therapy using aromatase inhibitors

Pain caused by the tumor or aromatase inhibitors (AIs) is a disabling symptom in breast cancer survivors. Their mechanisms are unclear, but pro-algesic and inflammatory mediators seem to be involved. Kinins are endogenous algogenic mediators associated with various painful conditions via B1 and B2 receptor activation, including chemotherapy-induced pain and breast cancer proliferation. We investigate the involvement of the kinin B1 and B2 receptors in metastatic breast tumor (4T1 breast cancer cells)-caused pain and in aromatase inhibitors (anastrozole or letrozole) therapy-associated pain. A protocol associating the tumor and antineoplastic therapy was also performed. Kinin receptors’ role was investigated via pharmacological antagonism, receptors protein expression, and kinin levels. Mechanical and cold allodynia and muscle strength were evaluated. AIs and breast tumor increased kinin receptors expression, and tumor also increased kinin levels. AIs caused mechanical allodynia and reduced the muscle strength of mice. Kinin B1 (DALBk) and B2 (Icatibant) receptor antagonists attenuated these effects and reduced breast tumor-induced mechanical and cold allodynia. AIs or paclitaxel enhanced breast tumor-induced mechanical hypersensitivity, while DALBk and Icatibant prevented this increase. Antagonists did not interfere with paclitaxel's cytotoxic action in vitro. Thus, kinin B1 or B2 receptors can be a potential target for treating the pain caused by metastatic breast tumor and their antineoplastic therapy.

Mass spectrometric study of variation in kinin peptide profiles in nasal fluids and plasma of adult healthy individuals

BackgroundThe kallikrein-kinin system is assumed to have a multifunctional role in health and disease, but its in vivo role in humans currently remains unclear owing to the divergence of plasma kinin level data published ranging from the low picomolar to high nanomolar range, even in healthy volunteers. Moreover, existing data are often restricted on reporting levels of single kinins, thus neglecting the distinct effects of active kinins on bradykinin (BK) receptors considering diverse metabolic pathways. A well-characterized and comprehensively evaluated healthy cohort is imperative for a better understanding of the biological variability of kinin profiles to enable reliable differentiation concerning disease-specific kinin profiles.MethodsTo study biological levels and variability of kinin profiles comprehensively, 28 healthy adult volunteers were enrolled. Nasal lavage fluid and plasma were sampled in customized protease inhibitor prespiked tubes using standardized protocols, proven to limit inter-day and interindividual variability significantly. Nine kinins were quantitatively assessed using validated LC–MS/MS platforms: kallidin (KD), Hyp4-KD, KD1-9, BK, Hyp3-BK, BK1-8, BK1-7, BK1-5, and BK2-9. Kinin concentrations in nasal epithelial lining fluid were estimated by correlation using urea.ResultsCirculating plasma kinin levels were confirmed in the very low picomolar range with levels below 4.2 pM for BK and even lower levels for the other kinins. Endogenous kinin levels in nasal epithelial lining fluids were substantially higher, including median levels of 80.0 pM for KD and 139.1 pM for BK. Hydroxylated BK levels were higher than mean BK concentrations (Hyp3-BK/BK = 1.6), but hydroxylated KD levels were substantially lower than KD (Hyp4-KD/KD = 0.37). No gender-specific differences on endogenous kinin levels were found.ConclusionsThis well-characterized healthy cohort enables investigation of the potential of kinins as biomarkers and would provide a valid control group to study alterations of kinin profiles in diseases, such as angioedema, sepsis, stroke, Alzheimer’s disease, and COVID-19.

Picomolar Sensitivity Analysis of Multiple Bradykinin-Related Peptides in the Blood Plasma of Patients With Hereditary Angioedema in Remission: A Pilot Study.

BackgroundHereditary angioedema (HAE) is a rare autosomal dominant disease; the most well understood forms concern the haplodeficiency of C1 esterase inhibitor (C1INH) and a gain of function mutation of factor XII (FXII). The acute forms of these conditions are mediated by an excessive bradykinin (BK) formation by plasma kallikrein.MethodsA validated LC-MS/MS platform of picomolar sensitivity developed for the analysis of eleven bradykinin-related peptides was applied to the plasma of HAE-C1INH and HAE-FXII sampled during remission.ResultsIn HAE-C1INH plasma, the concentrations of the relatively stable BK1−5 fragment (mean ± S.E.M.: 12.0 ± 4.2 pmol/L), of BK2−9 (0.7 ± 0.2 pmol/L) and of the sums of BK and its tested fragments (18.0 ± 6.4 pmol/L) are significantly greater than those recorded in the plasma of healthy volunteers (1.9 ± 0.6, 0.03 ± 0.03 and 4.3 ± 0.8 pmol/L, respectively), consistent with the previous evidence of permanent plasma kallikrein activity in this disease. Kinin levels in the plasma of HAE-FXII patients did not differ from controls, suggesting that triggering factors for contact system activation are not active during remission.ConclusionBK1−5, BK2−9 and the sum of BK and its fragments determined by the sensitive LC-MS/MS technique are proposed as potential biomarkers of HAE-C1INH in remission while this was not applicable to HAE-FXII patients.

Reliable measurement of plasma kinin peptides: Importance of preanalytical variables

BackgroundThe kallikrein‐kinin system is involved in many (patho)physiological processes and kinin peptides are considered potential clinical biomarkers. Variance in blood specimen collection and processing, artificial ex vivo bradykinin formation, and rapid degradation of kinins have contributed to divergence in published plasma levels, therefore limiting their significance. Thus, reliable preanalytical settings are highly required. ObjectivesThis study aimed to develop and evaluate a standardized preanalytical procedure for reliable kinin quantification. The procedure was based on identification of the most impactful variables on ex vivo plasma level alterations. MethodsSuitable protease inhibitors and blood specimen collection and handling conditions were systematically investigated. Their influence on plasma levels of seven kinins was monitored using an established in‐house liquid chromatography–tandem mass spectrometry platform. ResultsIn nonstandardized settings, ex vivo rise of bradykinin was found to already occur 30 seconds after blood sampling with high interindividual variation. The screening of 17 protease inhibitors resulted in a customized seven‐component protease inhibitor, which efficiently stabilized ex vivo kinin levels. The reliability of kinin levels was substantially jeopardized by prolonged rest time until centrifugation, phlebotomy methodology (eg, straight needles, catheters), vacuum sampling technique, or any time delays during venipuncture. The subsequently developed standardized procedure was applied to healthy volunteers and proved it significantly limited interday and interindividual kinin level variability. ConclusionThe developed procedure for blood specimen collection and handling is feasible in clinical settings and allows for determination of reliable kinin levels. It may contribute to further elucidating the role of the kallikrein‐kinin system in diseases like angioedema, sepsis, or coronavirus disease 2019.

Targeted LC-MS/MS platform for the comprehensive determination of peptides in the kallikrein-kinin system

The kallikrein-kinin system (KKS) is involved in many physiological and pathophysiological processes and is assumed to be connected to the development of clinical symptoms of angioedema or COVID-19, among other diseases. However, despite its diverse role in the regulation of physiological and pathophysiological functions, knowledge about the KKS in vivo remains limited. The short half-lives of kinins, their low abundance and structural similarities and the artificial generation of the kinin bradykinin greatly hinder reliable and accurate determination of kinin levels in plasma. To address these issues, a sensitive LC-MS/MS platform for the comprehensive and simultaneous determination of the four active kinins bradykinin, kallidin, des-Arg(9)-bradykinin and des-Arg(10)-kallidin and their major metabolites bradykinin 2-9, bradykinin 1-7 and bradykinin 1-5 was developed. This platform was validated according to the bioanalytical guideline of the US Food and Drug Administration regarding linearity, accuracy, precision, sensitivity, carry-over, recovery, parallelism, matrix effects and stability in plasma of healthy volunteers. The validated platform encompassed a broad calibration curve range from 2.0–15.3 pg/mL (depending on the kinin) up to 1000 pg/mL, covering the expected concentrations in disease states. No source-dependent matrix effects were identified, and suitable stability of the analytes in plasma was observed. The applicability of the developed platform was proven by the determination of endogenous levels in healthy volunteers, whose plasma kinin levels were successfully detected in the low pg/mL range. The established platform facilitates the investigation of kinin-mediated diseases (e.g. angioedema, COVID-19) and enables the assessment of the impact of altered enzyme activities on the formation or degradation of kinins.Graphical abstract

Kinins and their B1 and B2 receptors are involved in fibromyalgia-like pain symptoms in mice

Fibromyalgia is a disease characterised as generalised chronic primary pain that causes functional disability and a reduction in patients' quality of life, without specific pathophysiology or appropriate treatment. Previous studies have shown that kinins and their B1 and B2 receptors contribute to chronic painful conditions. Thus, we investigated the involvement of kinins and their B1 and B2 receptors in a fibromyalgia-like pain model induced by reserpine in mice. Nociceptive parameters (mechanical allodynia, cold sensitivity and overt nociception) and behaviours of burrowing, thigmotaxis, and forced swimming were evaluated after reserpine administration in mice. The role of kinin B1 and B2 receptors was investigated using knockout mice or pharmacological antagonism. The protein expression of kinin B1 and B2 receptors and the levels of bradykinin and monoamines were measured in the sciatic nerve, spinal cord and cerebral cortex of the animals. Knockout mice for the kinin B1 and B2 receptor reduced reserpine-induced mechanical allodynia. Antagonism of B1 and B2 receptors also reduced mechanical allodynia, cold sensitivity and overt nociception reserpine-induced. Reserpine altered thigmotaxis, forced swimming and burrowing behaviour in the animals; with the latter being reversed by antagonism of kinin B1 receptor. Moreover, reserpine increased the protein expression of kinin B1 and B2 receptors and levels of kinin, as well as reduced the levels of monoamines in peripheral and central structures. Kinins and its B1 and B2 receptors are involved in fibromyalgia-like pain symptoms. B1 or B2 receptors might represent a potential target for the relief of fibromyalgia-like pain symptoms.

Therapeutic Values of Human Urinary Kallidinogenase on Cerebrovascular Diseases.

The term “tissue kallikrein” is used to describe a group of serine proteases shared considerable sequence homology and colocalize in the same chromosomal locus 19q13. 2–q13.4. It has been widely discovered in various tissues and has been proved to be involved in kinds of pathophysiological processes, such as inhibiting oxidative stress, inflammation, apoptosis, fibrosis and promoting angiogenesis, and neurogenesis. Human Urinary Kallidinogenase (HUK) extracted from human urine is a member of tissue kallikrein which could convert kininogen to kinin and hence improve the plasma kinin level. Medical value of HUK has been widely investigated in China, especially on acute ischemic stroke. In this review, we will summarize the therapeutic values of Human Urinary Kallidinogenase on acute ischemic stroke and its potential mechanisms.

AB0145 Impaired healing of anterior cruciate ligament correlates with kinins expression

BackgroundACL is the most frequently injured ligament of the knee, with over 100,000 reconstructions performed annually. Reconstruction of injured ligaments is still a problem. The discovery that cartilage can make...

Extracellular aspartic protease SAP2 of Candida albicans yeast cleaves human kininogens and releases proinflammatory peptides, Met-Lys-bradykinin and des-Arg9-Met-Lys-bradykinin

Bradykinin-related peptides, universal mediators of inflammation collectively referred to as the kinins, are often produced in excessive amounts during microbial infections. We have recently shown that the yeast Candida albicans, the major fungal pathogen to humans, can exploit two mechanisms to enhance kinin levels at the sites of candidial infection, one depending on adsorption and activation of the endogenous kinin-generating system of the host on the fungal cell wall and the other relying on cleavage of kinin precursors, the kininogens, by pathogen-secreted proteases. This work aimed at assigning this kininogenase activity to the major secreted aspartic protease of C. albicans (SAP2). The purified SAP2 was shown to cleave human kininogens, preferably the low molecular mass form (LK) and optimally in an acidic environment (pH 3.5-4.0), and to produce two kinins, Met-Lys-bradykinin and its derivative, [Hydroxyproline(3)]-Met-Lys-bradykinin, both of which are capable of interacting with cellular bradykinin receptors of the B2 subtype. Additionally, albeit with a lower yield, des-Arg(9)-Met-Lys-bradykinin, an effective agonist of B1-subtype receptors, was released. The pathophysiological potential of these kinins and des-Arg-kinin was also proven by presenting their ability to stimulate human promonocytic cells U937 to release proinflammatory interleukin 1β (IL-1β) and IL-6.

Isolation and characterization of human meniscus-derived vascular stem cells

Isolation and characterization of human meniscus-derived vascular stem cells

Impaired healing of anterior cruciate ligament correlates with kinins expression

Purpose: ACL is the most frequently injured ligament of the knee, with over 100,000 reconstructions performed annually. Reconstruction of injured ligaments is still a problem. The discovery that cartilage can make products of the kinin-kallikrein pathway and its receptors suggests that it can not only respond to products of the pathway but initiate this inflammatory process in the joint by providing bradykinin (BK). An understanding of the process of ACL healing evolves, new markers will be indentified that will be accurate measures of this process. The purpose of the study was to define the levels of serum markers C1, 2C, C2C (cartilage degradation), CPII, CS846 (cartilage formation), natural (IgA, IgM, IgG) antibodies against BK (healing of ACL) in a cohort of patients before and after ACL reconstruction and compare them to matched, uninjured controls. Methods: Patients undergoing ACL reconstruction were matched with uninjured controls of similar age, sex, and BMI. Serum drawn upon entry to USMA and prior to graduation from both groups were tested ELISA kits (IBEX, Inc, Montreal, CA). In order to quantify NA to BK in the sera, were designed, synthesized and then used to develop a novel ELISA kits (INR). Results: Different classes of NA (IgM, IgG, IgA) against BK were detected with our ELISA protocol in the sera of ACL patients as well as in the sera of controls. There was no significant difference in binding of serum BK-IgA and BK-IgG levels in ACL patients in comparison with that in controls. Serum BK-IgM levels is elevated in patients after ACL reconstruction and correlate with individual and composite measures of the healing activity. There were significant differences (p<0.05) in the C2C and CPII levels between groups pre-injury, but not the C1, 2C and CS846 levels. There were significant differences (p<0.05) in the C1, 2C, C2C, and CPII levels between groups in the post-reconstruction state, but not for CS846. Comparing within group changes, all markers were significantly different over time (p<0.05) in both groups except for the controls C1, 2C and ACL injured CS846. Significant group by time interactions were observed (p<0.05) for C2C and CS846. Elevated BK-IgM in the sera was significantly correlated with C2C (r=0.85; p<0.0001) and CII (r=0.69; p<0.0003) in ACL patients in the post-reconstruction state. Conclusions: The process of ACL healing is highly complex, but is slowly starting to become more well defined. Kinins can stimulate the upregulation and production of cartilage after ACL reconstruction. A significant relationship was found between the examined markers of cartilage formation and degradation and the dynamic change of serum levels of kinins after ACL reconstruction. The difference in BK-IgM, CPII and C2C levels in the pre-injury state suggests that there may be differences in cartilage metabolism of individuals at risk for ACL tear. Significant changes over time were observed in kinins markers in the ACL-injured group and further study is warranted into the prognostic capabilities of these markers.

Change in Blood Kinin and Plasma Porcine Pancreatic Kallikrein Concentrations after Oral Administration of Kallikrein Formulation in Dog

Oral formulation of tissue kallikrein consists primarily of porcine pancreatic kallikrein (PPK) and is used to improve peripheral circulation, menopausal symptoms, and impaired chorioretinal circulation. Although gastrointestinal absorption of tissue kallikrein after oral administration has been reported in nonclinical and clinical studies, the increase in the concentration of pharmacologically active kinins, which are produced from kininogens by tissue kallikrein, has not been investigated. In this study, kallikrein formulation was orally administered to dogs and an increase in PPK in plasma was confirmed, along with an increase in the blood kinin level. After oral administration of kallikrein formulation (10 U/kg or 20 U/kg PPK) to dogs, PPK concentration in plasma reached maximum 3 h after administration, and then decreased time-dependently. The maximum concentration was 6.01 ± 1.44 pg/ml in the 10 U/kg group and 10.88 ± 3.59 pg/ml in the 20 U/kg group (mean ± S.E.M, n = 5). After oral administration of kallikrein formulation (40 U/kg PPK) to dogs, the blood kinin concentration in the PPK-treated group was significantly increased 2 h after administration as compared to the purified water-treated group (before administration: 48.8 ± 2.1 ng/ml vs. 48.1 ± 1.9 ng/ml, 2 h after administration: 55.5 ± 1.6 ng/ml vs. 49.6 ± 1.4 ng/ml; mean ± S.E.M, n = 4, p < 0.05). In conclusion, PPK was considered to be absorbed after oral administration and to exert its pharmacological action via kinins produced by kininogen degradation in dogs.

Reproducibility of nasal allergen challenge in evaluating the efficacy of intranasal corticosteroid treatment

Although nasal challenge with allergen has often been used to evaluate the efficacy of therapeutic modalities used for the treatment of allergic rhinitis, the reproducibility of this model in quantitatively evaluating efficacy has not been rigorously examined. To examine the reproducibility of the suppressive effects of an intranasal corticosteroid on the clinical and biochemical outcomes of a nasal allergen challenge during two identical treatment periods using the same subjects. In a single-blind study, 25 seasonal allergic subjects with positive skin tests to grass or ragweed were studied outside of their pollen season. Subjects underwent a baseline, three-dose allergen challenge. Beginning 1 week later, subjects received two 7-day courses of intranasal beclomethasone (168 microg b.i.d.) separated by a 1-month washout period. Nasal challenges with allergen were performed after each treatment period. The nasal allergic response was evaluated by counting sneezes, recording symptom scores and measuring levels of albumin (an index of vascular permeability), lysozyme (an index of serous glandular secretion) and kinins (proinflammatory peptides) in recovered nasal lavages. Compared with the baseline challenge, each course of beclomethasone significantly reduced sneezing, symptom scores, albumin and kinins, but not lysozyme. Reproducibility analysis of the net changes from diluent challenge in the two beclomethasone treatment periods, showed the following intraclass correlation coefficients: sneezing (0.92), lysozyme (0.82), symptom scores (0.72), albumin (0.64) and kinins (0.28). We conclude that the nasal challenge model is a reproducible method to evaluate the efficacy of anti-allergic medications. For nasal corticosteroid trials, sneezing, symptom scores and albumin levels are recommended as the most reproducibly suppressive outcome measures.

Angiotensin I–Converting Enzyme Inhibitors Are Allosteric Enhancers of Kinin B1 and B2 Receptor Function

The beneficial effects of angiotensin I-converting enzyme (ACE) inhibitors go beyond the inhibition of ACE to decrease angiotensin (Ang) II or increase kinin levels. ACE inhibitors also affect kinin B1 and B2 receptor (B1R and B2R) signaling, which may underlie some of their therapeutic usefulness. They can indirectly potentiate the actions of bradykinin (BK) and ACE-resistant BK analogs on B2Rs to elevate arachidonic acid and NO release in laboratory experiments. Studies indicate that ACE inhibitors and some Ang metabolites increase B2R functions as allosteric enhancers by inducing a conformational change in ACE. This is transmitted to B2Rs via heterodimerization with ACE on the plasma membrane of cells. ACE inhibitors are also agonists of the B1R, at a Zn-binding sequence on the second extracellular loop that differs from the orthosteric binding site of the des-Arg-kinin peptide ligands. Thus, ACE inhibitors act as direct allosteric B1R agonists. When ACE inhibitors enhance B2R and B1R signaling, they augment NO production. Enhancement of B2R signaling activates endothelial NO synthase, yielding a short burst of NO; activation of B1Rs results in a prolonged high output of NO by inducible NO synthase. These actions, outside inhibiting peptide hydrolysis, may contribute to the pleiotropic therapeutic effects of ACE inhibitors in various cardiovascular disorders.

Kallikrein protects against microalbuminuria in experimental type I diabetes

Tissue kallikrein is the main kinin-forming enzyme in mammals, and differences in kinin levels are thought to be a contributing factor to diabetic nephropathy. Here, we determined the role of the kallikrein-kinin system in the pathogenesis of streptozotocin-induced diabetic nephropathy in wild-type and tissue kallikrein-knockout mice. All diabetic mice developed similar hyperglycemia, but the knockout mice had a significant two-fold increase in albuminuria compared to the wild-type mice before and after blood pressure elevation. Ezrin mRNA, a podocyte protein potentially implicated in albuminuria, was downregulated in the kidney of knockout mice. One month after induction of diabetes, the mRNAs of kininogen, tissue kallikrein, kinin B1, and B2 receptors were all increased up to two-fold in the kidney in both genotypes. Diabetes caused a 50% decrease in renal angiotensin-converting enzyme expression and a 20-fold increase in kidney injury molecule-1 reflecting tubular dysfunction, but there was no genotype difference. Our study found an early activation of the kallikrein-kinin system in the kidney and that this has a protective role against the development of diabetic nephropathy. The effect of tissue kallikrein deficiency on microalbuminuria in diabetic mice is similar to the effect of genetically high angiotensin-converting enzyme levels, suggesting that both observations, in part, result from a deficiency in kinins.

Kallikreins, kininogens and kinin receptors on circulating and synovial fluid neutrophils: role in kinin generation in rheumatoid arthritis

Neutrophils traffic into and have the capacity to generate kinins in SF of RA patients. The aim of this study was to assess the expression of kallikreins, kininogens and kinin receptors in circulating and SF neutrophils, as well as synovial tissue of RA patients, and to assess kinin generation in SF. Neutrophils were isolated from blood and SF of RA patients and blood of healthy volunteers. Expression of kallikreins, kininogens and kinin receptors in neutrophils and synovial tissue was assessed by immunocytochemistry using specific antibodies, with visualization by brightfield and confocal microscopy. Levels of basal and generated kinins in SF of RA patients were measured by ELISA. Kinin labelling was significantly reduced, indicating the loss of the kinin moiety from kininogen on circulating (P < 0.001) and SF neutrophils (P < 0.05) of RA patients. Immunolabelling of tissue kallikrein was also decreased, whereas kinin B(1) and B(2) receptor expression was increased in circulating and SF neutrophils of RA patients. Immunolabelling of kallikreins and kinin receptor proteins was similar in RA and normal synovial tissues. The basal kinin level in SF of RA patients was 5.7 +/- 6.1 ng/ml and the mean concentration of kinins generated in vitro was 80.6 +/- 56.3 ng/ml. The capacity for kinin generation was positively correlated with measures of disease activity. Kallikrein-kinin proteins on neutrophils play an important role in kinin generation and the pathophysiology of RA. Specific kallikrein and kinin receptor antagonists may be useful as IA therapies for inflamed joints.

Blockade of renal medullary bradykinin B2 receptors increases tubular sodium reabsorption in rats fed a normal-salt diet.

The present study was performed to test the hypothesis that under normal physiological conditions and/or during augmentation of kinin levels, intrarenal kinins act on medullary bradykinin B(2) (BKB(2)) receptors to acutely increase papillary blood flow (PBF) and therefore Na(+) excretion. We determined the effect of acute inner medullary interstitial (IMI) BKB(2) receptor blockade on renal hemodynamics and excretory function in rats fed either a normal (0.23%)- or a low (0.08%)-NaCl diet. For each NaCl diet, two groups of rats were studied. Baseline renal hemodynamic and excretory function were determined during IMI infusion of 0.9% NaCl into the left kidney. The infusion was then either changed to HOE-140 (100 microg.kg(-1).h(-1), treated group) or maintained with 0.9% NaCl (time control group), and the parameters were again determined. In rats fed a normal-salt diet, HOE-140 infusion decreased left kidney Na(+) excretion (urinary Na(+) extraction rate) and fractional Na(+) excretion by 40 +/- 5% and 40 +/- 4%, respectively (P < 0.01), but did not alter glomerular filtration rate, inner medullary blood flow (PBF), or cortical blood flow. In rats fed a low-salt diet, HOE-140 infusion did not alter renal regional hemodynamics or excretory function. We conclude that in rats fed a normal-salt diet, kinins act tonically via medullary BKB(2) receptors to increase Na(+) excretion independent of changes in inner medullary blood flow.

Gene expression profiling in the remnant kidney model of wild type and kinin B1 and B2 receptor knockout mice

Angiotensin-converting enzyme inhibitors are the most efficient pharmacologic agents to delay the development of end-stage renal disease (ESRD). This is a multipharmacologic approach that inhibits angiotensin II formation while increasing kinin concentrations. Considerable attention has been focused on the role of decreased angiotensin II levels; however, the role of increased kinin levels is gaining in interest. Kinins affect cellular physiology by interacting with one of two receptors being the more inducible B1 and the more constitutive B2 receptors. This study utilizes the mouse remnant kidney of 20 weeks duration as a model of ESRD. Whole mouse genome microarrays were used to evaluate gene expression in the remnant kidneys of wild type, B1 and B2 receptor knockout animals. The microarray data indicate that gene families involved in vascular damage, inflammation, fibrosis, and proteinuria were upregulated, whereas gene families involved in cell growth, metabolism, lipid, and protein biosynthesis were downregulated in the remnant kidneys. Interestingly, the microarray analyses coupled to histological evaluations are suggestive of a possible protective role of kinins operating through the B2 receptor subtype in this model of renal disease. The results highlight the potential of microarray technology for unraveling complex mechanisms contributing to chronic renal failure.

Double-stranded RNA increases kinin B1 receptor expression and function in human airway epithelial cells

Increased levels of kinins have been detected within the airways during upper respiratory viral infections (URIs). Rhinovirus, the major URI associated with acute exacerbations of asthma, is an ssRNA virus that primarily infects the airway epithelium and produces dsRNA during replication. We asked whether dsRNA could increase the expression of kinin receptors in airway epithelial cells, thereby potentiating the inflammatory consequences of kinin generation. Human airway epithelial cell line BEAS-2B was stimulated with the dsRNA analog Poly I:C and kinin receptor expression detected by quantitative RT-PCR as well as radioligand binding. Poly I:C induced an increase in B1 and B2 receptor mRNA levels in BEAS-2B and primary human normal bronchial epithelial cells. At the cell surface, only B1 receptor expression was increased by Poly I:C. Furthermore, pretreatment of BEAS-2B cells with Poly I:C enhanced the induction of phospho-ERK following B1 receptor ligand stimulation. To investigate whether these finding had potential in vivo relevance, we assessed B1 receptor expression in nasal tissue obtained from 8 normal human subjects with URIs and 3 control subjects. Five of the URI subjects demonstrated increased B1 receptor mRNA compared to the 3 control subjects. We suggest that increased expression of B1 receptor in the human airway following a URI could increase the risk of an exacerbation of asthma by contributing to increased inflammation in the airway.