Delivery of recombinant adeno-associated virus-mediated human tissue kallikrein for therapy of chronic renal failure in rats

Kinin receptors regulate skeletal muscle regeneration: differential effects for B1 and B2 receptors

OBJECTIVE AND DESIGN

After traumatic skeletal muscle injury, muscle healing is often incomplete and produces extensive fibrosis. Bradykinin (BK) reduces fibrosis in renal and cardiac damage models through the B2 receptor. The B1 receptor expression is induced by damage, and blocking of the kallikrein-kinin system seems to affect the progression of muscular dystrophy. We hypothesized that both kinin B1 and B2 receptors could play a differential role after traumatic muscle injury, and the lack of the B1 receptor could produce more cellular and molecular substrates for myogenesis and fewer substrates for fibrosis, leading to better muscle healing.

MATERIAL AND METHODS

To test this hypothesis, tibialis anterior muscles of kinin receptor knockout animals were subjected to traumatic injury. Myogenesis, angiogenesis, fibrosis, and muscle functioning were evaluated.

RESULTS

Injured B1KO mice showed a faster healing progression of the injured area with a larger amount of central nucleated fiber post-injury when compared to control mice. In addition, they exhibited higher neovasculogenic capacity, maintaining optimal tissue perfusion for the post-injury phase; had higher amounts of myogenic markers with less inflammatory infiltrate and tissue destruction. This was followed by higher amounts of SMAD7 and lower amounts of p-SMAD2/3, which resulted in less fibrosis. In contrast, B2KO and B1B2KO mice showed more severe tissue destruction and excessive fibrosis. B1KO animals had better results in post-injury functional tests compared to control animals.

CONCLUSIONS

We demonstrate that injured skeletal muscle tissues have a better repair capacity with less fibrosis in the presence of B2 receptor and absence of B1 receptor, including better performances in functional tests.

hKLK alleviates myocardial fibrosis in mice with viral myocarditis

Myocardial fibrosis is the most serious complication of viral myocarditis (VMC). This study aimed to investigate the therapeutic benefits and underlying mechanisms of lentivirus-mediated human tissue kallikrein gene transfer in myocardial fibrosis in VMC mice. We established VMC mouse model via intraperitoneal injection with Coxsackie B3 virus. The effect was then assessed after treatment with vehicle, the empty lentiviral vectors (EZ.null), and the vectors expressing hKLK1 (EZ.hKLK1) via tail vein injection for 30 days, respectively. The results showed that administering EZ.hKLK1 successfully induced hKLK1 overexpression in mouse heart. Compared with EZ.null treatment, EZ.hKLK1 administration significantly reduced the heart/weight ratio, improved cardiac function, and ameliorated myocardial inflammation in VMC mice, suggesting that hKLK1 overexpression alleviates VMC in mice. EZ.hKLK1 administration also significantly abrogated the increased myocardial collagen content, type I/III collagen ratio, TGF-β1 mRNA and protein expression in VMC mice, suggesting that hKLK1 overexpression reduces collagen accumulation and blunts TGF-β1 signaling in the hearts of VMC mice. In conclusion, our results suggest that hKLK1 alleviates myocardial fibrosis in VMC mice, possibly by downregulating TGF-β1 expression.

Good or bad: Application of RAAS inhibitors in COVID-19 patients with cardiovascular comorbidities

The coronavirus disease 2019 (COVID-19) pandemic is caused by a newly emerged coronavirus (CoV) called Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). COVID-19 patients with cardiovascular disease (CVD) comorbidities have significantly increased morbidity and mortality. The use of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor type 1 blockers (ARBs) improve CVD outcomes; however, there is concern that they may worsen the prognosis of CVD patients that become infected with SARS-CoV-2 because the virus uses the ACE2 receptor to bind to and subsequently infect host cells. Thus, some health care providers and media sources have questioned the continued use of ACE inhibitors and ARBs. In this brief review, we discuss the effect of ACE inhibitor-induced bradykinin on the cardiovascular system, on the renin-angiotensin-aldosterone system (RAAS) regulation in COVID-19 patients, and analyze recent clinical studies regarding patients treated with RAAS inhibitors. We propose that the application of RAAS inhibitors for COVID-19 patients with CVDs may be beneficial rather than harmful.

The kallikrein-kinin system in diabetic kidney disease

PURPOSE OF REVIEW

Diabetic kidney disease (DKD) is one of the most common complications in diabetes mellitus and accounts for a large proportion of clinical nephrology practice. Studies have shown that the kallikrein-kinin system (KKS) may be involved in several pathogenic mechanisms that contribute to DKD, including oxidative stress, inflammatory cytokines, and profibrotic autacoids. This review focuses on recent research advance on the potential role of the KKS in the development of DKD and its clinical relevance.

RECENT FINDINGS

A number of recent studies support the idea that there is a protective role of the KKS in diabetes. For example, agents that activate the KKS have shown strong renal protective effects that might highlight its potential to change the clinical practice. In addition, diabetic mice lacking both bradykinin B2 and B1 receptors have worse kidney lesions as compared with wild-type diabetic mice.

SUMMARY

Current basic research has demonstrated that pharmacological activation of the KKS improves renal outcomes in diabetes. These findings suggest that this system may be a therapeutic target in preventing and treating DKD.

Blockade of Bradykinin receptors worsens the dystrophic phenotype of mdx mice: differential effects for B1 and B2 receptors

The Kallikrein Kinin System (KKS) is a vasoactive peptide system with known functions in the maintenance of tissue homeostasis, renal function and blood pressure. The main effector peptide of KKS is Bradykinin (BK). This ligand has two receptors: a constitutive B2 receptor (B2R), which has been suggested to have anti-fibrotic effects in renal and cardiac models of fibrosis; and the inducible B1 receptor (B1R), whose expression is induced by damage and inflammation. Inflammation and fibrosis are hallmarks of Duchenne muscular dystrophy (DMD), therefore we hypothesized that the KKS may play a role in this disease. To evaluate this hypothesis we used the mdx mouse a model for DMD. We blocked the endogenous activity of the KKS by treating mdx mice with B2R antagonist (HOE-140) or B1R antagonist (DesArgLeu⁸BK (DALBK)) for four weeks. Both antagonists increased damage, fibrosis, TGF-β and Smad-dependent signaling, CTGF/CCN-2 levels as well as the number of CD68 positive inflammatory cells. B2R blockade also reduced isolated muscle contraction force. These results indicate that the endogenous KKS has a protective role in the dystrophic muscle. The KKS may be a new target for future therapies to reduce inflammation and fibrosis in dystrophic muscle.

Preserved Erectile Function in the Aged Transgenic Rat Harboring Human Tissue Kallikrein 1

INTRODUCTION

Human tissue kallikrein 1 (hKLK1) has enormous potential for the protection of vasodilation and endothelial function in the cardiovascular system. Our previous study proved the decreased expression of kallikrein 1 in the corpus cavernosum (CC) of aged rats, but the role of kallikrein 1 in age-related erectile dysfunction remains unknown.

AIM

To explore the effect and underlying mechanisms of hKLK1 on age-related erectile dysfunction.

METHODS

Male wild-type Sprague-Dawley rats (WTR) and transgenic rats harboring the hKLK1 gene (TGR) were fed to 4 and 27 months of age, respectively, and divided into four groups: young WTR (yWTR) as the control, young TGR (yTGR), aged WTR (aWTR), and aged TGR (aTGR). Rats' erectile function was evaluated by the cavernous nerve electrostimulation method. Then, CCs were collected for verification of hKLK1 followed by measurement of nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) and RhoA-Rho-kinase (ROCK) signaling activities. Masson trichrome staining and terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling assay were conducted to evaluate penile fibrosis and apoptosis.

MAIN OUTCOME MEASURES

Erectile response, NO-cGMP and RhoA-ROCK pathway-related indices, ratio of smooth muscle to collagen, and apoptosis index.

RESULTS

The hKLK1 alleviated the decrease of erectile function in the aWTR group. Endothelial NO synthase (eNOS) and phospho-eNOS(Ser1177) expressions, NO synthase activity, and NO and cGMP levels were decreased, whereas phospho-eNOS(Thr495), L-type Ca(2+) channel, RhoA, ROCK1, ROCK2, and transforming growth factor β1 proteins were increased in the CCs of the aWTR group compared with the control yWTR group. These changes were obviously mitigated in the aTGR group. Moreover, hKLK1 prevented the sharp decrease of the ratio of smooth muscle to collagen and the increase of the apoptosis index in the CCs of the aWTR group.

CONCLUSION

These results suggest that hKLK1 could play a preventive role in age-related erectile dysfunction by activation of the NO-cGMP pathway and inhibition of the RhoA-ROCK pathway and by antitissue fibrotic and apoptotic effects.

Up-regulation of the kinin B2 receptor pathway modulates the TGF-β/Smad signaling cascade to reduce renal fibrosis induced by albumin

The presence of high protein levels in the glomerular filtrate plays an important role in renal fibrosis, a disorder that justifies the use of animal models of experimental proteinuria. Such models have proved useful as tools in the study of the pathogenesis of chronic, progressive renal disease. Since bradykinin and the kinin B2 receptor (B2R) belong to a renoprotective system with mechanisms still unclarified, we investigated its anti-fibrotic role in the in vivo rat model of overload proteinuria. Upon up-regulating the kinin system by a high potassium diet we observed reduction of tubulointerstitial fibrosis, decreased renal expression of α-smooth muscle actin (α-SMA) and vimentin, reduced Smad3 phosphorylation and increase of Smad7. These cellular and molecular effects were reversed by HOE-140, a specific B2R antagonist. In vitro experiments, performed on a cell line of proximal tubular epithelial cells, showed that high concentrations of albumin induced expression of mesenchymal biomarkers, in concomitance with increases in TGF-β1 mRNA and its functionally active peptide, TGF-β1. Stimulation of the tubule cells by bradykinin inhibited the albumin-induced changes, namely α-SMA and vimentin were reduced, and cytokeratin recovered together with increase in Smad7 levels and decrease in type II TGF-β1 receptor, TGF-β1 mRNA and its active fragment. The protective changes produced by bradykinin in vitro were blocked by HOE-140. The development of stable bradykinin analogues and/or up-regulation of the B2R signaling pathway may prove value in the management of chronic renal fibrosis in progressive proteinuric renal diseases.

Repair effect of coexpression of the hVEGF and hBMP genes via an adeno-associated virus vector in a rabbit model of early steroid-induced avascular necrosis of the femoral head

We investigated the repair effect of coexpression of the human vascular endothelial growth factor (hVEGF) and human bone morphogenetic protein (hBMP) genes via an adeno-associated virus (AAV) vector in a rabbit model of early steroid-induced avascular necrosis of the femoral head (SANFH). The following AAV vectors were constructed: AAV-green fluorescent protein, AAV-VEGF, AAV-BMP, and AAV-VEGF/BMP. The rabbit model was induced using lipopolysaccharide and methylprednisolone. Virus vector was injected into the core decompression region at a dose of 25 μL per side after core decompression operation in each group. hVEGF165 and BMP-7 expressions were determined by Western blotting and immunohistochemical staining, and the femoral head was examined by magnetic resonance image scan, histopathologic staining, ink vessel staining, microcomputed tomography scan, and biomechanical assessment to determine the repair effect. The vector AAV-VEGF/BMP successfully expressed hVEGF165 and BMP-7 at the gene and protein levels at 12 weeks after virus injection. The expression of hVEGF165 promoted metabolism of the necrotic region by inducing vessel formation. The expression of BMP-7 promoted osteogenesis by increasing the mineral density and biomechanical strength of the femoral head. The repair effect of the AAV-VEGF/BMP group was better than those of the AAV-VEGF and AAV-BMP groups in the rabbit early SANFH model. The AAV-VEGF/BMP vector improved the bone repair capacity of the necrotic femoral head by inducing angiogenesis and improving bone quality in the femoral head.

Pharmacological effects of recombinant human tissue kallikrein on bradykinin B2 receptors

Tissue kallikrein (KLK-1), a serine protease, initiates the release of bradykinin (BK)-related peptides from low-molecular weight kininogen. KLK-1 and the BK B₂ receptor (B₂R) mediate beneficial effects on the progression of type 2 diabetes and renal disease, but the precise role of KLK-1 independent of its kinin-forming activity remains unclear. We used DM199, a recombinant form of human KLK-1, along with the isolated human umbilical vein, a robust bioassay of the B₂R, to address the previous claims that KLK-1 directly binds to and activates the human B₂R, with possible receptor cleavage. DM199 (1–10 nmol/L) contracted the isolated vein via the B₂R, but in a tachyphylactic, kinin-dependent manner, without desensitization of the tissue to exogenously added BK. In binding experiments with recombinant N-terminally tagged myc-B₂Rs expressed in HEK 293a cells, DM199 displaced [³H]BK binding from the rabbit myc-B₂R, but not from the human or rat myc-B₂Rs. No evidence of myc-B₂R degradation by immunoblot analysis was apparent following treatment of these 3 myc-B₂R constructs with DM199 (30 min, ≤10 nmol/L). In HEK 293 cells stably expressing rabbit B₂R-GFP, DM199 (11–108 pmol/L) elicited signaling-dependent endocytosis and reexpression, while a higher concentration (1.1 nmol/L) induced a partially irreversible endocytosis of the construct (microscopy), paralleled by the appearance of free GFP in cells (immunoblotting, indicative of incomplete receptor down-regulation). The pharmacology of DM199 at relevant concentrations (<10 nmol/L) is essentially based on the activity of locally generated kinins. Binding to and mild down-regulation of the B₂R is possibly a species-dependent idiosyncratic response to DM199.

Relation of plasma tissue kallikrein levels to presence and severity of coronary artery disease in a Chinese population

Objectives

Tissue kallikrein (TK) has been shown to provide cardiovascular and cerebrovascular protective effects in animal models. The aim of this study was to investigate the relationship of plasma TK levels with the presence and severity of coronary artery disease (CAD) in the Chinese.

Methods

The study involved 898 consecutive CAD patients and 905 ethnically and geographically matched controls. CAD was angiographically confirmed in all the patients, and the severity of CAD was expressed by the number of affected vessel and coronary artery stenosis scores. Plasma TK levels were measured using an enzyme-linked immunosorbent assay.

Results

Plasma TK levels were significantly higher in CAD patients than controls (0.347±.082 vs. 0.256±0.087 mg/L, P<0.001), and elevated plasma TK levels were directly associated with a higher risk of CAD (OR = 3.49, 95% CI 2.90–4.19). One-way ANOVA and multivariable stepwise linear regression analysis demonstrated that TK levels were negatively associated with the severity of CAD according to vessel scores (P<0.001) and stenosis scores (r = −0.211, p<0.001).

Conclusions

Our findings suggest that higher levels of TK in plasma are associated with the presence of CAD and are a predictor of mild coronary arteriosclerosis.

Bradykinin inhibits oxidative stress-induced cardiomyocytes senescence via regulating redox state

Background

Cell senescence is central to a large body of age related pathology, and accordingly, cardiomyocytes senescence is involved in many age related cardiovascular diseases. In consideration of that, delaying cardiomyocytes senescence is of great importance to control clinical cardiovascular diseases. Previous study indicated that bradykinin (BK) protected endothelial cells from senescence induced by oxidative stress. However, the effects of bradykinin on cardiomyocytes senescence remain to be elucidated. In this study, we investigated the effect of bradykinin on H₂O₂-induced H9C2 cells senescence.

Methods and Results

Bradykinin pretreatment decreased the senescence induced by H₂O₂ in cultured H9C2 cells in a dose dependent manner. Interestingly, 1 nmol/L of BK almost completely inhibited the increase in senescent cell number and p21 expression induced by H₂O₂. Since H₂O₂ induces senescence through superoxide-induced DNA damage, we also observed the DNA damage by comet assay, and BK markedly reduced DNA damage induced by H₂O₂, and moreover, BK treatment significantly prevented reactive oxygen species (ROS) production in H9C2 cells treated with H₂O₂. Importantly, when co-incubated with bradykinin B2 receptor antagonist HOE-140 or eNOS inhibitor N-methyl-L-arginine acetate salt (L-NAME), the protective effects of bradykinin on H9C2 senescence were totally blocked. Furthermore, BK administration significantly prevented the increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity characterized by increased ROS generation and gp91 expression and increased translocation of p47 and p67 to the membrane and the decrease in superoxide dismutase (SOD) activity and expression induced by H₂O₂ in H9C2 cells, which was dependent on BK B2 receptor mediated nitric oxide (NO) release.

Conclusions

Bradykinin, acting through BK B2 receptor induced NO release, upregulated antioxidant Cu/Zn-SOD and Mn-SOD activity and expression while downregulating NADPH oxidase activity and subsequently inhibited ROS production, and finally protected against cardiomyocytes senescence induced by oxidative stress.

Association of functional kallikrein-1 promoter polymorphisms and acute kidney injury: a case-control and longitudinal cohort study

BACKGROUND

Kallikrein-1 (KLK1) is a highly conserved serine protease that is expressed in the kidney and involved in blood pressure regulation. The activity of this enzyme is diminished in acute kidney injury (AKI).

METHODS

We first evaluated the potential role of functional multiallelic KLK1 promoter gene polymorphisms in a case-control study of 481 subjects (214 hospitalized patients with AKI of mixed causes and 267 healthy subjects). The complex, multiallelic G/C-rich repeat region of the proximal KLK1 promoter was determined by direct Sanger/capillary resequencing.

RESULTS

16 alleles were identified in a complex, polymorphic G/C-rich region of the KLK1 proximal promoter; 5 of these alleles (F, G, H, I, and K) were associated with development of AKI. Alleles I and G were classified as risk-alleles (unadjusted OR 1.86; 95% CI 1.23, 2.81; p = 0.003), whereas alleles F, H, and K were classified as protective-alleles (unadjusted OR 0.32; 95% CI 0.22, 0.46; p < 0.001) according to their directional association with development of AKI. After adjustment for sex, race, preexisting chronic kidney disease and APACHE II score, the KLK1 risk-allele (I or G) carrier state was associated with the composite of ≥2-fold increase in serum creatinine, oliguria, or dialysis requirement (adjusted OR 2.71; 95% CI 1.14, 6.44; p = 0.02). The KLK1 risk-allele carrier state was also marginally associated with the composite of ≥2-fold increase in serum creatinine, oliguria, dialysis requirement, or in-hospital death (adjusted OR 2.33; 95% CI 0.98, 5.52; p = 0.06).

CONCLUSIONS

KLK1 promoter polymorphisms are associated with development of AKI and adverse outcomes. Further studies are needed to validate these findings.

Antihypertensive and renoprotective effect of the kinin pathway activated by potassium in a model of salt sensitivity following overload proteinuria

The albumin overload model induces proteinuria and tubulointersitial damage, followed by hypertension when rats are exposed to a hypersodic diet. To understand the effect of kinin system stimulation on salt-sensitive hypertension and to explore its potential renoprotective effects, the model was induced in Sprague-Dawley rats that had previously received a high-potassium diet to enhance activity of the kinin pathway, followed with/without administration of icatibant to block the kinin B₂ receptor (B₂R). A disease control group received albumin but not potassium or icatibant, and all groups were exposed to a hypersodic diet to induce salt-sensitive hypertension. Potassium treatment increased the synthesis and excretion of tissue kallikrein (Klk1/rKLK1) accompanied by a significant reduction in blood pressure and renal fibrosis and with downregulation of renal transforming growth factor-β (TGF-β) mRNA and protein compared with rats that did not receive potassium. Participation of the B₂R was evidenced by the fact that all beneficial effects were lost in the presence of the B₂R antagonist. In vitro experiments using the HK-2 proximal tubule cell line showed that treatment of tubular cells with 10 nM bradykinin reduced the epithelial-mesenchymal transdifferentiation and albumin-induced production of TGF-β, and the effects produced by bradykinin were prevented by pretreatment with the B₂R antagonist. These experiments support not only the pathogenic role of the kinin pathway in salt sensitivity but also sustain its role as a renoprotective, antifibrotic paracrine system that modulates renal levels of TGF-β.

CYP2J2 overexpression increases EETs and protects against angiotensin II-induced abdominal aortic aneurysm in mice

Cytochrome P450 epoxygenase 2J2 (CYP2J2) metabolizes arachidonic acids to form epoxyeicosatrienoic acids (EETs), which possess various beneficial effects on the cardiovascular system. However, whether increasing EETs production by CYP2J2 overexpression in vivo could prevent abdominal aortic aneurysm (AAA) remains unknown. Here we investigated the effects of recombinant adeno-associated virus (rAAV)-mediated CYP2J2 overexpression on angiotensin (Ang) II-induced AAA in apoE-deficient mice. rAAV-CYP2J2 delivery led to an abundant aortic CYP2J2 expression and increased EETs generation. It was shown that CYP2J2 overexpression attenuated matrix metalloproteinase expression and activity, elastin degradation, and AAA formation, which was associated with reduced aortic inflammation and macrophage infiltration. In cultured vascular smooth muscle cells (VSMCs), rAAV-mediated CYP2J2 overexpression and EETs markedly suppressed Ang II-induced inflammatory cytokine expression. Moreover, overexpressed CYP2J2 and EETs inhibited Ang II-induced macrophage migration in a VSMC-macrophage coculture system. We further indicated that these protective effects were mediated by peroxisome proliferator-activated receptor (PPAR)γ activation. Taken together, these results provide evidence that rAAV-mediated CYP2J2 overexpression prevents AAA development which is likely via PPARγ activation and anti-inflammatory action, suggesting that increasing EETs levels could be considered as a potential strategy to prevent and treat AAA.

Genetic disruption of soluble epoxide hydrolase is protective against streptozotocin-induced diabetic nephropathy

Cytochrome P-450 (CYP) epoxygenases metabolize arachidonic acid into epoxyeicosatrienoic acids (EETs), which play important roles in regulating cardiovascular functions. The anti-inflammatory, antiapoptotic, proangiogenic, and antihypertensive properties of EETs suggest a beneficial role for EETs in diabetic nephropathy. Endogenous EET levels are maintained by a balance between synthesis by CYP epoxygenases and hydrolysis by epoxide hydrolases into physiologically less active dihydroxyeicosatrienoic acids. Genetic disruption of soluble epoxide hydrolase (sEH/EPHX2) results in increased EET levels through decreased hydrolysis. This study investigated the effects of sEH gene disruption on diabetic nephropathy in streptozotocin-induced diabetic mice. Streptozotocin-induced diabetic manifestations were attenuated in sEH-deficient mice relative to wild-type controls, with significantly decreased levels of Hb A(1c), creatinine, and blood urea nitrogen and urinary microalbumin excretion. The sEH-deficient diabetic mice also had decreased renal tubular apoptosis that coincided with increased levels of antiapoptotic Bcl-2 and Bcl-xl, and decreased levels of the proapoptotic Bax. These effects were associated with activation of the PI3K-Akt-NOS3 and AMPK signaling cascades. sEH gene inhibition and exogenous EETs significantly protected HK-2 cells from TNFα-induced apoptosis in vitro. These findings highlight the beneficial role of the CYP epoxygenase-EETs-sEH system in the pathogenesis of diabetic nephropathy and suggest that the sEH inhibitors available may be potential therapeutic agents for this condition.

Delivery of AAV2-CYP2J2 protects remnant kidney in the 5/6-nephrectomized rat via inhibition of apoptosis and fibrosis

The cytochrome P450 epoxygenase, CYP2J2, converts arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EETs), which are highly abundant in the kidney and considered renoprotective. Accumulating evidence suggests that EETs are important in regulating renal and cardiovascular function. Further, EETs have been confirmed to exert diverse biological activities including potent vasodilation; fibrinolytic properties; and antiinflammatory, antiapoptotic, and mitogenic effects. In the current study, we investigated the effects of overexpression of CYP2J2 via recombinant adeno-associated virus (rAAV) in protection against renal damage in a rat 5/6 nephrectomy (5/6-Nx) model of chronic renal failure. The rAAV-CYP2J2 gene delivery in vivo increased EET generation; attenuated the rise in blood pressure; and reduced the levels of proteinuria, serum creatinine, and blood urea nitrogen. Morphological analysis indicated that rAAV-CYP2J2 gene delivery reduced 5/6 nephrectomy-induced glomerular sclerosis, tubular dilatation, luminal protein cast formation, and tubulointerstitial fibrosis. rAAV-CYP2J2 gene delivery also significantly lowered collagen I and IV deposition, as well as renal cell apoptosis detected by TUNEL staining, caspase-3 activity, and the loss of mitochondrial membrane potential (ΔΨ(m)). Furthermore, rAAV-CYP2J2 gene delivery regulated the level of protein expression including transforming growth factor (TGF)-β(1)/SMADs; matrix metalloproteinases (MMPs); mitogen-activated protein kinases (MAPKs); and apoptosis-related proteins Bax, Bcl-2, and Bcl-x(L). Together, these findings demonstrated that rAAV-CYP2J2 gene delivery can protect remnant kidney against renal injury in 5/6-Nx rats by inhibiting apoptosis and fibrosis via regulation of protein expression including TGF-β(1)/SMADs, MMPs, MAPKs, and apoptosis-related proteins.

Plasma tissue kallikrein level is negatively associated with incident and recurrent stroke: a multicenter case-control study in China

OBJECTIVE

Tissue kallikrein (TK) cleaves kininogen to produce the potent bioactive compounds kinin and bradykinin, which lower blood pressure and protect the heart, kidneys, and blood vessels. Reduction in TK levels is associated with cardiovascular disease and diabetes in animal models. In this study, we investigated the association of TK levels with event-free survival over 5 years in Chinese first-ever stroke patients.

METHODS

We conducted a case-control study with 1,268 stroke patients (941 cerebral infarction, 327 cerebral hemorrhage) and 1,210 controls. Plasma TK levels were measured with an enzyme-linked immunosorbent assay. We used logistic regression and Cox proportional hazards models to assess the relationship between TK levels and risk of first-time or recurrent stroke.

RESULTS

Plasma TK levels were significantly lower in stroke patients (0.163 ± 0.064mg/l vs 0.252 ± 0.093mg/l, p < 0.001), especially those with ischemic stroke. After adjustment for traditional risk factors, plasma TK levels were negatively associated with the risk of first-ever stroke (odds ratio [OR], 0.344; 95% confidence interval [CI], 0.30-0.389; p < 0.001) and stroke recurrence and positively associated with event-free survival during 5 years of follow-up (relative risk, 0.82; 95% CI, 0.74-0.90; p < 0.001). Compared with the first quartile of plasma TK levels, the ORs for first-ever stroke patients were as follows: second quartile, 0.77 (95% CI, 0.56-1.07); third quartile, 0.23 (95% CI, 0.17-0.32); fourth quartile, 0.04 (95% CI, 0.03-0.06).

INTERPRETATION

Lower plasma TK levels are independently associated with first-ever stroke and are an independent predictor of recurrence after an initial stroke.

Proteases as therapeutics

Proteases are an expanding class of drugs that hold great promise. The U.S. FDA (Food and Drug Administration) has approved 12 protease therapies, and a number of next generation or completely new proteases are in clinical development. Although they are a well-recognized class of targets for inhibitors, proteases themselves have not typically been considered as a drug class despite their application in the clinic over the last several decades; initially as plasma fractions and later as purified products. Although the predominant use of proteases has been in treating cardiovascular disease, they are also emerging as useful agents in the treatment of sepsis, digestive disorders, inflammation, cystic fibrosis, retinal disorders, psoriasis and other diseases. In the present review, we outline the history of proteases as therapeutics, provide an overview of their current clinical application, and describe several approaches to improve and expand their clinical application. Undoubtedly, our ability to harness proteolysis for disease treatment will increase with our understanding of protease biology and the molecular mechanisms responsible. New technologies for rationally engineering proteases, as well as improved delivery options, will expand greatly the potential applications of these enzymes. The recognition that proteases are, in fact, an established class of safe and efficacious drugs will stimulate investigation of additional therapeutic applications for these enzymes. Proteases therefore have a bright future as a distinct therapeutic class with diverse clinical applications.

Angiopoiesis and bone regeneration via co-expression of the hVEGF and hBMP genes from an adeno-associated viral vector in vitro and in vivo

AIM

To investigate the therapeutic potential of adeno-associated virus (AAV)-mediated expression of vascular endothelial growth factor (VEGF) and bone morphogenetic protein (BMP).

METHODS

Four experimental groups were administered the following AAV vector constructs: rAAV-hVEGF(165)-internal ribosome entry site (IRES)-hBMP-7 (AAV-VEGF/BMP), rAAV-hVEGF(165)-GFP (AAV-VEGF), rAAV-hBMP-7-GFP (AAV-BMP), and rAAV-IRES-GFP (AAV-GFP). VEGF(165) and BMP-7 gene expression was detected using RT-PCR. The VEGF(165) and BMP-7 protein expression was determined by Western blotting and ELISA. The rabbit ischemic hind limb model was adopted and rAAV was administered intramuscularly into the ischemic limb.

RESULTS

Rabbit bone marrow-derived mesenchymal stem cells (BMSCs) were cultured and infected with the four viral vectors. The expression of GFP increased from the 7th day of infection and could be detected on the 28th day post-infection. In the AAV-VEGF/BMP group, the levels of VEGF165 and BMP-7 increased with prolonged infection time. The VEGF(165) and BMP-7 secreted from BMSCs in the AAV-VEGF/BMP group enhanced HUVEC tube formation and resulted in a stronger osteogenic ability, respectively. In rabbit ischemic hind limb model, GFP expression increased from the 4th week and could be detected at 8 weeks post-injection. The rAAV vector had superior gene expressing activity. Eight weeks after gene transfer, the mean blood flow was significantly higher in the AAV-VEGF/BMP group. Orthotopic ossification was radiographically evident, and capillary growth and calcium deposits were obvious in this group.

CONCLUSION

AAV-mediated VEGF and BMP gene transfer stimulates angiogenesis and bone regeneration and may be a new therapeutic technique for the treatment of avascular necrosis of the femoral head (ANFH).

Increased CYP2J3 expression reduces insulin resistance in fructose-treated rats and db/db mice

OBJECTIVE

Accumulating evidence suggests that cytochrome P450 (CYP) epoxygenases metabolize arachidonic acid into epoxyeicosatrienoic acids (EETs), which play crucial and diverse roles in cardiovascular homeostasis. The anti-inflammatory, antihypertensive, and pro-proliferative effects of EETs suggest a possible beneficial role for EETs on insulin resistance and diabetes.

RESEARCH DESIGN AND METHODS

This study investigated the effects of CYP2J3 epoxygenase gene therapy on insulin resistance and blood pressure in diabetic db/db mice and in a model of fructose-induced hypertension and insulin resistance in rats.

RESULTS

CYP2J3 gene delivery in vivo increased EET generation, reduced blood pressure, and reversed insulin resistance as determined by plasma glucose levels, homeostasis model assessment insulin resistance index, and glucose tolerance test. Furthermore, CYP2J3 treatment prevented fructose-induced decreases in insulin receptor signaling and phosphorylation of AMP-activated protein kinases (AMPKs) in liver, muscle, heart, kidney, and aorta. Thus, overexpression of CYP2J3 protected against diabetes and insulin resistance in peripheral tissues through activation of insulin receptor and AMPK pathways.

CONCLUSIONS

These results highlight the beneficial roles of the CYP epoxygenase-EET system in diabetes and insulin resistance.

Recombinant adeno-associated virus-mediated human kallikrein gene therapy protects against hypertensive target organ injuries through inhibiting cell apoptosis

AIM

Overexpression of human tissue kallikrein (HK), mediated by recombinant adeno-associated virus (rAAV), decreased blood pressure in spontaneous hypertensive rats (SHRs) and reduced injury to the heart, aorta and kidney. In this study, we used both an in vivo animal model and in vitro cell culture system to investigate whether rAAV-mediated HK gene therapy protects against organ damage by inhibiting cell apoptosis.

METHODS

rAAV encoding HK (rAAV-HK) or LacZ (rAAV-lacZ) were delivered as a control to spontaneously hypertensive rats (SHRs) and cultured human embryonic kidney (HEK) 293 cells.

RESULTS

Treatment with rAAV-HK decreased cell apoptosis in the target organs of SHRs and also inhibited lipopolysaccharide (LPS)-induced HEK 293 apoptosis. The rAAV-HK delivery system also increased the levels of apoptosis-inhibiting proteins bcl-2 and bcl-x(L), and decreased the level of Bax and the activity of caspase 3, two promoters of apoptosis. In addition to its role in the inhibition of apoptosis, rAAV-HK also activated the cell survival and proliferation signaling pathways ERK1/2 and PI3K/AKT.

CONCLUSION

rAAV-mediated HK gene delivery has multiple therapeutic possibilities for treating hypertension, not only by decreasing blood pressure, but also by directly inhibiting end-organ damage.

The kallikrein-kinin system in health and in diseases of the kidney

Since kallikrein was discovered as a vasodilatory substance in human urine, the kallikrein-kinin system (KKS) has been considered to play a physiological role in controlling blood pressure. Gene targeting experiments in mice in which the KKS has been inactivated to varying degrees have, however, questioned this role, because basal blood pressures are not altered. Rather, these experiments have shown that the KKS has a different and important role in preventing changes associated with normal senescence in mice, and in reducing the nephropathy and accelerated senescence-associated phenotypes induced in mice by diabetes. Other experiments have shown that the KKS suppresses mitochondrial respiration, partly by nitric oxide and prostaglandins, and that this suppression may be a key to understanding how the KKS influences senescence-related diseases. Here we review the logical progression and experimental data leading to these conclusions, and discuss their relevance to human conditions.