Influence of bradykinin B1 and B2 receptors in the immune response triggered by renal ischemia-reperfusion injury

COVID-19 cytokine storm: The anger of inflammation

Patients with COVID-19 who require ICU admission might have the cytokine storm. It is a state of out-of-control release of a variety of inflammatory cytokines. The molecular mechanism of the cytokine storm has not been explored extensively yet. The attachment of SARS-CoV-2 spike glycoprotein with angiotensin-converting enzyme 2 (ACE2), as its cellular receptor, triggers complex molecular events that leads to hyperinflammation. Four molecular axes that may be involved in SARS-CoV-2 driven inflammatory cytokine overproduction are addressed in this work. The virus-mediated down-regulation of ACE2 causes a burst of inflammatory cytokine release through dysregulation of the renin-angiotensin-aldosterone system (ACE/angiotensin II/AT1R axis), attenuation of Mas receptor (ACE2/MasR axis), increased activation of [des-Arg9]-bradykinin (ACE2/bradykinin B1R/DABK axis), and activation of the complement system including C5a and C5b-9 components. The molecular clarification of these axes will elucidate an array of therapeutic strategies to confront the cytokine storm in order to prevent and treat COVID-19 associated acute respiratory distress syndrome.

Binding to carboxypeptidase M mediates protective effects of fibrinopeptide Bβ15-42

During fibrinolysis a 28-amino-acid peptide is generated besides other degradation products of fibrin. This peptide, called Bβ_15-42, which is cleaved by plasmin from the end of the fibrin Bβ-chain, is protective in myocardial and renal ischemia/reperfusion injury and improves the outcome in experimental sepsis. Bβ_15-42 has been shown to mediate different beneficial effects in endothelial cells through binding to vascular endothelial-cadherin. Here, we provide in vitro and in vivo evidence that Bβ_15-42 has additional cell protective activity in tubular cells, which is caused by a distinct mechanism. As vascular endothelial-cadherin is not expressed by tubular cells we used ligand-receptor capture technology LRC-TriCEPS to search for tubular cell surface receptors and identified carboxypeptidase M (CBPM) as a novel binding partner of Bβ_15-42. Silencing CBPM with siRNA reduced the protective potential of Bβ_15-42 against tubular cell stress. Bβ_15-42 inhibited the enzymatic activity of CBPM and modified the impact of CBPM on bradykinin signaling. We conclude that beneficial properties of Bβ_15-42 are not restricted to endothelial cells but are also active in epithelial cells where cytoprotection depends on CBPM binding.

Immunobiology of spinal cord injuries and potential therapeutic approaches

The incidence of spinal cord injuries (SCI) is high every year. As the spinal cord is the highway that allows for the brain to control the rest of the body, spinal cord injuries greatly impact the quality of life of the patients. The SCI include the primary response consisting of the initial accident-induced damage and the secondary response that is characterized by damage due to inflammation and biological responses. Astrocytes are the first to act at the site of the injury, forming a glial scar and attracting immune cells. The immune system plays a role in cleaning out the debris caused by the injury, as well as preventing neurons to grow and heal. The secondary injury caused by the inflammatory response is the major target to combat SCI. This article critically reviews the key players in the inflammatory SCI response and potential therapies, specifically targeting astrocytes, neutrophils, and macrophages. These cells are both beneficial and detrimental following SCI, depending on the released molecules and the types of cells infiltrated to the site of injury. Indeed, depending on the subtype of macrophages, M1 or M2, beneficial or detrimental response could be incited. Therapeutic strategies to regulate and manipulate the immune cells via increasing or decreasing their recruitment to the site of injury could be developed together with upregulating and downregulating the release of certain chemicals from the infiltrated cells.

Complement inhibition attenuates acute kidney injury after ischemia-reperfusion and limits progression to renal fibrosis in mice

The complement system is an essential component of innate immunity and plays a major role in the pathogenesis of ischemia-reperfusion injury (IRI). In this study, we investigated the impact of human C1-inhibitor (C1INH) on the early inflammatory response to IRI and the subsequent progression to fibrosis in mice. We evaluated structural damage, renal function, acute inflammatory response, progression to fibrosis and overall survival at 90-days post-injury. Animals receiving C1INH prior to reperfusion had a significant improvement in survival rate along with superior renal function when compared to vehicle (PBS) treated counterparts. Pre-treatment with C1INH also prevented acute IL-6, CXCL1 and MCP-1 up-regulation, C5a release, C3b deposition and infiltration by neutrophils and macrophages into renal tissue. This anti-inflammatory effect correlated with a significant reduction in the expression of markers of fibrosis alpha smooth muscle actin, desmin and picrosirius red at 30 and 90 days post-IRI and reduced renal levels of TGF-β1 when compared to untreated controls. Our findings indicate that intravenous delivery of C1INH prior to ischemic injury protects kidneys from inflammatory injury and subsequent progression to fibrosis. We conclude that early complement blockade in the context of IRI constitutes an effective strategy in the prevention of fibrosis after ischemic acute kidney injury.

MATE-1 modulation by kinin B1 receptor enhances cisplatin efflux from renal cells

Cisplatin is a drug widely used in chemotherapy that frequently causes severe renal dysfunction. Organic transporters have an important role to control the absorption and excretion of cisplatin in renal cells. Deletion and blockage of kinin B1 receptor has already been show to protect against cisplatin-induced acute kidney injury. To test whether it exerts its protective function by modulating the organic transporters in kidney, we studied kinin B1 receptor knockout mice and treatment with a receptor antagonist at basal state and in presence of cisplatin. Cisplatin administration caused downregulation of renal organic transporters; in B1 receptor knockout mice, this downregulation of organic transporters in kidney was absent; and treatment by a B1 receptor antagonist attenuated the downregulation of the transporter MATE-1. Moreover, kinin B1 receptor deletion and blockage at basal state resulted in higher renal expression of MATE-1. Moreover we observed that kinin B1 receptor deletion and blockage result in less accumulation of platinum in renal tissue. Thus, we propose that B1 receptor deletion and blockage protect the kidney from cisplatin-induced acute kidney injury by upregulating the expression of MATE-1, thereby increasing the efflux of cisplatin from renal cells.

Kinin B1 receptor deficiency attenuates cisplatin-induced acute kidney injury by modulating immune cell migration

Cisplatin is a chemotherapeutic agent that causes severe renal dysfunction. The kinin B1 receptor has been associated with the migration of immune cells to injured tissue as well as with renal inflammation. To examine the role of the kinin B1 receptor in cisplatin-induced acute kidney injury, we used kinin B1 receptor knockout mice and treatment with a receptor antagonist before and after cisplatin administration. Cisplatin injection caused exacerbation of renal macrophage and neutrophil migration, higher levels of serum creatinine and blood urea, upregulation of B1 receptor mRNA and an increase in pro-inflammatory cytokines expression. B1 receptor knockout mice exhibited a reduction in serum creatinine and blood urea levels, diminished apoptosis, and decreased cisplatin-induced upregulation of inflammatory components. Moreover, treatment with the B1 receptor antagonist prior to cisplatin administration normalized serum creatinine, blood urea levels, protected from acute tubular necrosis, apoptosis-related genes, and prevented upregulation of pro-inflammatory cytokines. Thus, we propose that kinins have an important role in cisplatin-induced acute kidney injury by impairing immune cells migration to renal tissue during cisplatin nephrotoxicity.

KEY MESSAGE

Kinin B1 receptor is upregulated after cisplatin exposure. Kinin B1 receptor deficiency diminishes the nephrotoxicity caused by cisplatin. Kinin B1 receptor deficiency ameliorates the inflammatory response. Kinin B1 receptor deficiency diminishes apoptosis caused by cisplatin. Kinin B1 receptor antagonism ameliorates renal function after cisplatin injection.

The kallikrein-kinin system in experimental Chagas disease: a paradigm to investigate the impact of inflammatory edema on GPCR-mediated pathways of host cell invasion by Trypanosoma cruzi

Chronic chagasic myocarditis (CCM) depends on Trypanosoma cruzi persistence in the myocardium. Studies of the proteolytic mechanisms governing host/parasite balance in peripheral sites of T. cruzi infection revealed that tissue culture trypomastigotes (TCTs) elicit inflammatory edema and stimulate protective type-1 effector T cells through the activation of the kallikrein-kinin system. Molecular studies linked the proinflammatory phenotype of Dm28c TCTs to the synergistic activities of tGPI, a lipid anchor that functions as a Toll-like receptor 2 (TLR2) ligand, and cruzipain, a kinin-releasing cysteine protease. Analysis of the dynamics of inflammation revealed that TCTs activate innate sentinel cells via TLR2, releasing CXC chemokines, which in turn evoke neutrophil/CXCR2-dependent extravasation of plasma proteins, including high molecular weight kininogen (HK), in parasite-laden tissues. Further downstream, TCTs process surface bound HK, liberating lysyl-BK (LBK), which then propagates inflammatory edema via signaling of endothelial G-protein-coupled bradykinin B₂ receptors (BK₂R). Dm28 TCTs take advantage of the transient availability of infection-promoting peptides (e.g., bradykinin and endothelins) in inflamed tissues to invade cardiovascular cells via interdependent signaling of BKRs and endothelin receptors (ETRs). Herein we present a space-filling model whereby ceramide-enriched endocytic vesicles generated by the sphingomyelinase pathway might incorporate BK₂R and ETRs, which then trigger Ca²⁺-driven responses that optimize the housekeeping mechanism of plasma membrane repair from cell wounding. The hypothesis predicts that the NF-κB-inducible BKR (BK₁R) may integrate the multimolecular signaling platforms forged by ceramide rafts, as the chronic myocarditis progresses. Exploited as gateways for parasite invasion, BK₂R, BK₁R, ET_AR, ET_BR, and other G protein-coupled receptor partners may enable persistent myocardial parasitism in the edematous tissues at expense of adverse cardiac remodeling.

Bradykinin receptor 1 activation exacerbates experimental focal and segmental glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is one of the most important causes of end-stage renal failure. The bradykinin B1 receptor has been associated with tissue inflammation and renal fibrosis. To test for a role of the bradykinin B1 receptor in podocyte injury, we pharmacologically modulated its activity at different time points in an adriamycin-induced mouse model of FSGS. Estimated albuminuria and urinary protein to creatinine ratios correlated with podocytopathy. Adriamycin injection led to loss of body weight, proteinuria, and upregulation of B1 receptor mRNA. Early treatment with a B1 antagonist reduced albuminuria and glomerulosclerosis, and inhibited the adriamycin-induced downregulation of podocin, nephrin, and α-actinin-4 expression. Moreover, delayed treatment with antagonist also induced podocyte protection. Conversely, a B1 agonist aggravated renal dysfunction and even further suppressed the levels of podocyte-related molecules. Thus, we propose that kinin has a crucial role in the pathogenesis of FSGS operating through bradykinin B1 receptor signaling.

Novel kinin B1 receptor agonists with improved pharmacological profiles

There is some evidence to suggest that inducible kinin B1 receptors (B1R) may play beneficial and protecting roles in cardiovascular-related pathologies such as hypertension, diabetes, and ischemic organ diseases. Peptide B1R agonists bearing optimized pharmacological features (high potency, selectivity and stability toward proteolysis) hold promise as valuable therapeutic agents in the treatment of these diseases. In the present study, we used solid-phase methodology to synthesize a series of novel peptide analogues based on the sequence of Sar[dPhe(8)]desArg(9)-bradykinin, a relatively stable peptide agonist with moderate affinity for the human B1R. We evaluated the pharmacological properties of these peptides using (1) in vitro competitive binding experiments on recombinant human B1R and B2R (for index of selectivity determination) in transiently transfected human embryonic kidney 293 cells (HEK-293T cells), (2) ex vivo vasomotor assays on isolated human umbilical veins expressing endogenous human B1R, and (3) in vivo blood pressure tests using anesthetized lipopolysaccharide-immunostimulated rabbits. Key chemical modifications at the N-terminus, the positions 3 and 5 on Sar[dPhe(8)]desArg(9)-bradykinin led to potent analogues. For example, peptides 18 (SarLys[Hyp(3),Cha(5), dPhe(8)]desArg(9)-bradykinin) and 20 (SarLys[Hyp(3),Igl(5), dPhe(8)]desArg(9)-bradykinin) outperformed the parental molecule in terms of affinity, functional potency and duration of action in vitro and in vivo. These selective agonists should be valuable in future animal and human studies to investigate the potential benefits of B1R activation.

The kinin B(1) receptor and inflammation: new therapeutic target for cardiovascular disease

The kinin B(1) receptor plays an important role in mediating the inflammatory effects of the kallikrein-kinin pathway. The recent development of orally available non-peptidic antagonists and genetically modified mice deficient in B(1) receptor expression have demonstrated that the receptor plays a pivotal role in the cellular, particularly neutrophil, recruitment associated with an acute inflammatory response. These tools have also enabled elucidation of the pathways involved in mediating this effect and have highlighted a major role for chemokines, particularly CXCL5 and CCL2. Neutrophil recruitment is involved in the pathogenesis of renal disease and has very recently been implicated in the early stages of atherosclerosis. In this review we discuss the most recent evidence linking the B(1) receptor with the pathogenesis of these two inflammatory cardiovascular diseases and highlight the therapeutic potential of the kinin B(1) receptor in these disease states.

Deletion of bradykinin B1 receptor reduces renal fibrosis

The Kallikrein-kinin system works through activation of two receptors. One constitutive, named B2 receptor (B2R) and another inducible, denominated B1 receptor (B1R). In renal fibrosis, B2R receptor activation appears to be protective, however B1R participation is unveiled. The aim of this study was to analyze how the deletion of the B1R would modify tissue responses after unilateral ureteral obstruction (UUO). For that, B1R knockout (B1KO) and wild-type mice (B1B2WT) were subjected to UUO and sacrificed at days 1, 5 and 14. Renal dysfunction was assayed by urine proteinuria/creatinine ratio and percentage of tubulointerstitial fibrosis. Kidneys were harvested at day 5 to analyze anti and pro-inflammatory molecules expression by real-time PCR. We demonstrated that at all time points, B1KO mice presented lower proteinuria/creatinine ratio from bladder urine. B1KO protection was reinforced by its lower tubular interstitial fibrosis percentage at day 14 (B1B2WT: 12.16+/-1.53% vs. B1KO: 6.73+/-1.07%, p<0.02). UUO was able to induce B1R expression and its highest transcription was achieved at day 5. At this day, B1KO had significant lower expression of pro-inflammatory molecules such as TGF-beta, MCP-1, OPN and IL-6 and higher anti-inflammatory components, as IL-10 and HO-1. Herein, we observed that B1R deletion may be an important component in renal fibrosis prevention.

Delayed blockade of the kinin B1 receptor reduces renal inflammation and fibrosis in obstructive nephropathy

Renal fibrosis is the common histological feature of advanced glomerular and tubulointerstitial disease leading to end-stage renal disease (ESRD). However, specific antifibrotic therapies to slow down the evolution to ESRD are still absent. Because persistent inflammation is a key event in the development of fibrosis, we hypothesized that the proinflammatory kinin B1 receptor (B1R) could be such a new target. Here we show that, in the unilateral ureteral obstruction model of renal fibrosis, the B1R is overexpressed and that delayed treatment with an orally active nonpeptide B1R antagonist blocks macrophage infiltration, leading to a reversal of the level of renal fibrosis. In vivo bone marrow transplantation studies as well as in vitro studies on renal cells show that part of this antifibrotic mechanism of B1R blockade involves a direct effect on resident renal cells by inhibiting chemokine CCL2 and CCL7 expression. These findings suggest that blocking the B1R is a promising antifibrotic therapy.

Bradykinin [corrected] B1 receptor antagonism is beneficial in renal ischemia-reperfusion injury

Previously we have demonstrated that bradykinin B1 receptor deficient mice (B1KO) were protected against renal ischemia and reperfusion injury (IRI). Here, we aimed to analyze the effect of B1 antagonism on renal IRI and to study whether B1R knockout or antagonism could modulate the renal expression of pro and anti-inflammatory molecules. To this end, mice were subjected to 45 minutes ischemia and reperfused at 4, 24, 48 and 120 hours. Wild-type mice were treated intra-peritoneally with antagonists of either B1 (R-954, 200 µg/kg) or B2 receptor (HOE140, 200 µg/kg) 30 minutes prior to ischemia. Blood samples were collected to ascertain serum creatinine level, and kidneys were harvested for gene transcript analyses by real-time PCR. Herein, B1R antagonism (R-954) was able to decrease serum creatinine levels, whereas B2R antagonism had no effect. The protection seen under B1R deletion or antagonism was associated with an increased expression of GATA-3, IL-4 and IL-10 and a decreased T-bet and IL-1β transcription. Moreover, treatment with R-954 resulted in lower MCP-1, and higher HO-1 expression. Our results demonstrated that bradykinin B1R antagonism is beneficial in renal IRI.

Effects of intracerebroventricular infusion of angiotensin-(1-7) on bradykinin formation and the kinin receptor expression after focal cerebral ischemia-reperfusion in rats

Accumulating evidence suggests that the angiotensin-(1-7) [Ang-(1-7)], is an active member of the brain renin-angiotensin system (RAS). We evaluated the possibility that intracerebroventricular (ICV, lateral ventricle) infusion of exogenous Ang-(1-7) could participate in the potentiation of bradykinin (BK) release and the kinin receptor expression in ischemic brain parenchyma after focal cerebral ischemia-reperfusion in rats. The middle cerebral artery occlusion (MCAO) and sham-operated models were prepared, continuously administrated with Ang-(1-7) or artificial cerebrospinal fluid (aCSF) by implanted Alzet osmotic minipumps into lateral cerebral ventricle after reperfusion in male Sprague-Dawley (SD) rats. Experimental animals were divided into sham-operated group (sham+aCSF), aCSF treatment group (MCAO+aCSF) and Ang-(1-7) treatment groups [MCAO+Ang-(1-7)] at low (1 pmol/0.5 microl/h), medium (100 pmol/0.5 microl/h) or high (10 nmol/0.5 microl/h) dose levels. Cerebral infarction resulted in a significant increase of BK formation from 3 h to 6 h compared with sham-operated group after reperfusion, whereas medium- and high-dose Ang-(1-7) infusion markedly enhanced BK levels from 6 h to 48 h after reperfusion. Medium- and high-dose Ang-(1-7) infusion markedly increased kinin B(2) receptor mRNA and protein expression, whereas only high-dose Ang-(1-7) infusion induced upregulating the expression of B(1) receptor. Low-dose Ang-(1-7) infusion did not modify both the kinin B(1) and B(2) receptor expression compared with aCSF treatment group after focal cerebral ischemia-reperfusion at each time point. The finding might indicate complex interactions between Ang-(1-7) and kallikrein-kinin system in the CNS after focal cerebral ischemia-reperfusion in rats.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Bradykinin B1 and B2 receptors both have protective roles in renal ischemia/reperfusion injury

To explore the role of the kallikrein-kinin system in relation to ischemia/reperfusion injury in the kidney, we generated mice lacking both the bradykinin B1 and B2 receptor genes (B1RB2R-null, Bdkrb1-/-/Bdkrb2-/-) by deleting the genomic region encoding the two receptors. In 4-month-old mice, blood pressures were not significantly different among B1RB2R-null, B2R-null (Bdkrb2-/-), and WT mice. After 30 min of bilateral renal artery occlusion and 24 h of reperfusion, mortality rates, renal histological and functional changes, 8-hydroxy-2'-deoxyguanosine levels in total DNA, mtDNA deletions, and the number of TUNEL-positive cells in the kidneys increased progressively in the following order (from lowest to highest): WT, B2R-null, and B1RB2R-null mice. Increases in mRNA levels of TGF-beta1, connective tissue growth factor, and endothelin-1 after ischemia/reperfusion injury were also exaggerated in the same order (from lowest to highest): WT, B2R-null, and B1RB2R-null. Thus, both the B1 and B2 bradykinin receptors play an important role in reducing DNA damage, apoptosis, morphological and functional kidney changes, and mortality during renal ischemia/reperfusion injury.