Systemic and portal vein delivery of human kallikrein gene reduces blood pressure in hypertensive rats

Kallistatin ameliorates influenza virus pathogenesis by inhibition of kallikrein-related peptidase 1-mediated cleavage of viral hemagglutinin

Proteolytic cleavage of the hemagglutinin (HA) of influenza virus by host trypsin-like proteases is required for viral infectivity. Some serine proteases are capable of cleaving influenza virus HA, whereas some serine protease inhibitors (serpins) inhibit the HA cleavage in various cell types. Kallikrein-related peptidase 1 (KLK1, also known as tissue kallikrein) is a widely distributed serine protease. Kallistatin, a serpin synthesized mainly in the liver and rapidly secreted into the circulation, forms complexes with KLK1 and inhibits its activity. Here, we investigated the roles of KLK1 and kallistatin in influenza virus infection. We show that the levels of KLK1 increased, whereas those of kallistatin decreased, in the lungs of mice during influenza virus infection. KLK1 cleaved H1, H2, and H3 HA molecules and consequently enhanced viral production. In contrast, kallistatin inhibited KLK1-mediated HA cleavage and reduced viral production. Cells transduced with the kallistatin gene secreted kallistatin extracellularly, which rendered them more resistant to influenza virus infection. Furthermore, lentivirus-mediated kallistatin gene delivery protected mice against lethal influenza virus challenge by reducing the viral load, inflammation, and injury in the lung. Taking the data together, we determined that KLK1 and kallistatin contribute to the pathogenesis of influenza virus by affecting the cleavage of the HA peptide and inflammatory responses. This study provides a proof of principle for the potential therapeutic application of kallistatin or other KLK1 inhibitors for influenza. Since proteolytic activation also enhances the infectivity of some other viruses, kallistatin and other kallikrein inhibitors may be explored as antiviral agents against these viruses.

A transient three-plasmid expression system for the production of hepatocytes targeting retroviral vectors

Targeting of retroviral vectors to specific cells was attempted through modifying the surface protein of the murine leukemia viruses (MLVs), but in many cases the protein function was affected, and it is difficult to achieve the targeted delivery. In this study, we have tried to engineer ecotropic Moloney murine leukemia viruses (MoMLV)-based retroviral vectors to transduce hepatocytes. A chimeric envelope (Env) expression plasmid was constructed containing the hepatitis B virus PreS2 peptide fused to aa +1 at the N-terminus of Env. Following simultaneous transfection of pgag-pol, pLEGFP and chimeric env plasmids into 293T cells, helper-free retrovirus stocks with the titer of approximately 10(4) infectious units/ml were achieved at 48 h post-transfection. These pseudotype vectors showed the normal host range of retrovirus, infecting host NIH 3T3 cells, although the efficiency was reduced compared with that of virions carrying wild-type ecotropic MoMLV envelope. In addition, the resultant pseudotype viruses could transduce human hepatoma cells mediated by polymerized human serum albumin with relatively high titers in comparison with those transductions without polymerized human serum albumin. This approach can be used to target hepatocytes selectively.

Renal kallikrein: a risk marker for nephropathy in children with sickle cell disease

OBJECTIVE

Although improvements in the management of sickle cell disease (SCD) have increased patient survival into adulthood, morbidity and mortality from end-organ damage remain major concerns. One of the most serious complications of SCD is renal failure, affecting about 20% of patients. The clinical manifestations of sickle cell nephropathy (SCN) involve changes in glomerular ultrastructure, albuminuria, and a progressive decline in glomerular hemodynamics. The mechanisms or factors that promote SCN are not fully elucidated. In the present study, the role of renal kallikrein as a risk marker for promoting SCN was explored in a cross-sectional study.

METHODS AND RESULTS

We measured the urinary excretion rate of active kallikrein in 73 children with sickle cell anemia (hemoglobin SS, SC, or S thalassemia) and in 30 control healthy African American children. The findings demonstrated that a significant difference in the excretion rate of log kallikrein in male versus female patients with SCD, P<0.0078 was observed. In children with SCD, cross-sectional analysis revealed a positive and significant correlation between the excretion rate of active kallikrein and log albumin excretion rate (AER), P<0.0088. Regression analysis also determined that the excretion rate of active kallikrein negatively correlates with hemoglobin in children with SCD, P<0.0096. In addition, an inverse relationship between log AER and hemoglobin was observed in male patients with SCD, P<0.0143. In children with SCD, cross-sectional analysis revealed a positive and significant correlation between log AER and age, suggesting age as a risk marker for AER in SCD. In multivariate regression analysis, our findings demonstrate a strong association between log AER and age and log kallikrein in children with SCD. About 20% of the variability in log AER in SCD patients is influenced by age and 6% is influenced by log kallikrein, P<0.0001 and P<0.02, respectively.

CONCLUSIONS

These findings provide the first evidence that the excretion rate of active kallikrein is positively and independently correlated with log AER in children with SCD, and suggest that kallikrein could be a marker for progressive nephropathy. Longitudinal studies are essential to address this issue.

The tissue kallikrein-kinin system protects against cardiovascular and renal diseases and ischemic stroke independently of blood pressure reduction

Tissue kallikrein (hK1) cleaves low-molecular-weight kininogen to produce kinin peptide, which binds to kinin receptors and triggers a wide spectrum of biological effects. Tissue kallikrein levels are reduced in humans and in animal models with hypertension, cardiovascular and renal diseases. Transgenic mice or rats over-expressing human tissue kallikrein or kinin B2 receptor are permanently hypotensive, and somatic kallikrein gene delivery reduces blood pressure in several hypertensive rat models. Moreover, kallikrein gene delivery or kallikrein protein infusion can directly improve cardiac, renal and neurological function without blood pressure reduction. Kallikrein has pleiotropic effects in inhibiting apoptosis, inflammation, proliferation, hypertrophy and fibrosis, and promoting angiogenesis and neurogenesis in different experimental animal models. Kallikrein's effects can be blocked by kinin B2 receptor antagonists. Mechanistically, tissue kallikrein/kinin leads to increased nitric oxide levels and Akt activation, and reduced reactive oxygen species formation, TGF-beta1 expression, MAPK and nuclear factor-kappaB activation. Our studies indicate that tissue kallikrein, through the kinin B2 receptor and nitric oxide formation, can protect against oxidative damage in cardiovascular and renal diseases and ischemic stroke. These novel findings suggest that kallikrein/kinin may serve as new drug targets for the prevention and treatment of heart failure, renal disease and stroke in humans.

Kallikrein–kinin in stroke, cardiovascular and renal disease

Tissue kallikrein, a serine proteinase, produces the potent vasodilator kinin peptide from kininogen substrate. The levels of tissue kallikrein are reduced in humans and animal models with hypertension, cardiovascular and renal disease. Using transgenic and somatic gene transfer approaches, we investigated the role of the tissue kallikrein-kinin system in cardiovascular, renal and central nervous systems. A single injection of the human tissue kallikrein gene in plasmid DNA or an adenoviral vector resulted in a prolonged reduction of blood pressure and attenuation of hypertrophy and fibrosis in the heart and kidney of several hypertensive animal models. Furthermore, enhanced kallikrein-kinin levels after gene transfer exerted beneficial effects, with protection against cardiac remodelling, renal injuries, restenosis, cerebral infarction and neurological deficits in normotensive animal models without haemodynamic effects, indicating direct actions of kallikrein independent of its ability to lower blood pressure. The effects of kallikrein were mediated by the kinin B2 receptor, as the specific B2 receptor antagonist icatibant abolished the actions of kallikrein. Moreover, kallikrein-kinin exhibited pleiotropic effects by inhibiting apoptosis, inflammation, hypertrophy and fibrosis, and promoting angiogenesis and neurogenesis in the heart, kidney, brain and blood vessel. Exogenous administration of kallikrein also led to increased nitric oxide (NO)/cGMP and cAMP levels, and reduced NAD(P)H oxidase activities, superoxide formation and pro-inflammatory cytokine levels. These results indicate a novel role of kallikrein-kinin through the kinin B2 receptor as an antioxidant and anti-inflammatory agent in protection against stroke, cardiovascular and renal disease, and may uncover new drug targets for the prevention and treatment of heart failure, vascular injury, end-stage renal disease and stroke in humans.

Altered renal response to acute volume expansion in transgenic rats harboring the human tissue kallikrein gene

The renal response to acute volume expansion was investigated in transgenic (TGR) rats harboring the human tissue kallikrein gene. After a primer injection of 0.9% NaCl (3 ml/100 g, i.v), Sprague-Dawley (SD) or TGR rats received a continuous infusion of 0.9% NaCl (15 microl/100 g/min, i.a.) through a catheter placed into the carotid artery. Acute volume expansion was produced by a second injection of 0.9% NaCl (2 ml/100 g, i.v.) 65 min after the first injection. Plasma vasopressin (AVP) and atrial natriuretic peptide (ANP) concentration was measured before and within 10 min of volume expansion. TGR animals presented a blunted response to acute volume expansion evidenced by an attenuated increase in total and fractional water and sodium excretion. Before or after volume expansion, plasma AVP and ANP did not differ between SD and TGR. Pre-treatment with the BK-B2 antagonist HOE-140 (7.5 microg/100 g. i.a) partially improved the renal response of TGRs and severely blunted the response in SD rats. These data show that TGR (hKLK1) rats have an impaired renal response to acute volume expansion that can not be accounted for by changes in the release of AVP or ANP.

Tissue kallikrein attenuates salt-induced renal fibrosis by inhibition of oxidative stress

BACKGROUND

High salt intake induces hypertension, cardiac hypertrophy, and progressive renal damage. Progressive renal injury is the consequence of a process of destructive fibrosis. Using gene transfer approach, we have shown that the tissue kallikrein-kinin system (KKS) plays an important role in protection against renal injury in several hypertensive rat models. In this study, we further investigated the effect and potential mechanisms mediated by kallikrein on salt-induced renal fibrosis.

METHODS

Adenovirus harboring the human tissue kallikrein gene was delivered intravenously into Dahl salt-sensitive (DSS) rats on a high salt diet for 4 weeks. Two weeks after gene delivery, the effect of kallikrein on renal fibrosis was examined by biochemical and histologic analysis.

RESULTS

Kallikrein gene delivery resulted in reduced blood urea nitrogen (BUN), urinary protein and albumin levels in DSS rats on a high salt diet. Expression of recombinant human tissue kallikrein was detected in the sera and urine of rats injected with the kallikrein gene. Histologic investigation showed that kallikrein gene delivery significantly reduced glomerular and tubular fibrosis scores and collagen deposition, as well as renal cell proliferation, compared to rats on a high salt diet injected with control virus. Kallikrein gene transfer significantly increased nitric oxide and cyclic guanosine monophosphate (cGMP) levels in conjunction with reduced salt-induced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NADH/NADPH) oxidase activity, superoxide production, transforming growth factor-beta1 (TGF-beta1) mRNA and protein levels, and TGF-beta1 immunostaining.

CONCLUSION

These results indicate that tissue kallikrein protects against renal fibrosis in hypertensive DSS rats through increased nitric oxide bioavailability and suppression of oxidative stress and TGF-beta expression.

Kallikrein gene transfer protects against ischemic stroke by promoting glial cell migration and inhibiting apoptosis

Kallikrein/kinin has been shown to protect against ischemia/reperfusion-induced myocardial infarction and apoptosis. In the present study, we examined the potential neuroprotective action of kallikrein gene transfer in cerebral ischemia. Adult, male Sprague-Dawley rats were subjected to a 1-hour occlusion of the middle cerebral artery followed by intracerebroventricular injection of adenovirus harboring either the human tissue kallikrein gene or the luciferase gene. Kallikrein gene transfer significantly reduced ischemia-induced locomotor deficit scores and cerebral infarction after cerebral ischemia injury. Expression of recombinant human tissue kallikrein was identified and localized in monocytes/macrophages of rat ischemic brain by double immunostaining. Morphological analyses showed that kallikrein gene transfer enhanced the survival and migration of glial cells into the ischemic penumbra and core, as identified by immunostaining with glial fibrillary acidic protein. Cerebral ischemia markedly increased apoptotic cells, and kallikrein gene delivery reduced apoptosis to near-normal levels as seen in sham control rats. In primary cultured glial cells, kinin stimulated cell migration but inhibited hypoxia/reoxygenation-induced apoptosis in a dose-dependent manner. The effects of kinin on both migration and apoptosis were abolished by icatibant, a bradykinin B2 receptor antagonist. Enhanced cell survival after kallikrein gene transfer occurred in conjunction with markedly increased cerebral nitric oxide levels and phospho-Akt and Bcl-2 levels but reduced caspase-3 activation, NAD(P)H oxidase activity, and superoxide production. These results indicate that kallikrein gene transfer provides neuroprotection against cerebral ischemia injury by enhancing glial cell survival and migration and inhibiting apoptosis through suppression of oxidative stress and activation of the Akt-Bcl-2 signaling pathway.

Prevention of diabetes-induced microangiopathy by human tissue kallikrein gene transfer

BACKGROUND

Microvascular insufficiency represents a major cause of end-organ failure among diabetics.

METHODS AND RESULTS

In streptozotocin-induced diabetic mice, we evaluated the potential of human tissue kallikrein (hTK) gene as a sole therapy against peripheral microangiopathy. Local delivery of hTK gene halted the progression of microvascular rarefaction in hindlimb skeletal muscle by inhibiting apoptosis, thus ensuring an improved hemodynamic recovery in case of supervening vascular occlusion. The curative action of hTK did not necessitate insulin supplementation. Application of gene therapy at a stage of established microangiopathy stimulated vascular regeneration.

CONCLUSIONS

Our studies indicate that hTK may represent a useful tool for the treatment of microvascular complications in diabetics.

Gene therapy for malignant liver disease

For most patients with advanced or multifocal hepatocellular carcinoma (HCC) or with metastatic malignant liver disease treatment options are limited, resulting in a poor prognosis. Novel therapeutic strategies such as gene therapy are therefore urgently required. Gene therapeutic approaches use gene delivery systems (vectors) to introduce DNA constructs as therapeutic agents into living cells. Antitumour strategies include the reintroduction of tumour suppressor genes into tumour cells, the expression of foreign enzymes to render tumours susceptible to treatment with chemotherapeutic agents and the enhancement of tumour immunogenicity by expressing immunomodulatory genes or by genetic vaccination with tumour antigens. Furthermore, gene therapy may be also used for anti-angiogenesis to reduce tumour growth and metastatic potential. Other novel approaches aim at the development of genetically altered replication competent viruses, which selectively replicate in tumour cells inducing cell lysis. Although most clinical trials of antitumour gene therapy so far have failed to induce strong therapeutic effects, further improvement of antitumour gene therapy may finally result in potent clinical treatment options for patients with malignant liver tumours.

Efficient liposome-mediated gene transfection and expression in the intact human uterus

Although gene therapy has been used for correction of metabolic defects in diseases such as cystic fibrosis, as adjuvant treatment in cancer, and in the treatment of infectious diseases, there has been no report of gene transfer to the intact female reproductive tract. We assessed the ability to transfect the human uterus ex vivo and thereby evaluate the applicability of gene therapy to gynecology. The uterine lumen was accessed transcervically, using an intrauterine insemination catheter. pcDNA3.1 plasmid containing the Escherichia coli lacZ reporter gene was delivered to each uterus via liposome-mediated transfection. Control uteri were transfected with empty pcDNA3.1. Immunohistochemical analysis revealed beta-galactosidase expression in the lacZ-treated uteri in endometrial epithelial cells, endometrial stromal cells, and myometrium to a depth of 1.75 cm from the endometrial-myometrial junction. Highest expression was seen in endometrial glandular epithelial cells, with significant expression in the stroma and adjacent myometrium. Each of these cell types in the control uteri showed no beta-galactosidase expression. Successful gene transfection and expression in the intact human uterus can be accomplished easily, rapidly, and efficiently. Gene therapy may have wide applicability in the treatment and study of gynecologic disease.

Angiogenesis gene therapy to rescue ischaemic tissues: achievements and future directions

Ischaemic diseases are characterized by an impaired supply of blood resulting from narrowed or blocked arteries that starve tissues of needed nutrients and oxygen. Coronary-atherosclerosis induced myocardial infarction is one of the leading causes of mortality in developed countries. Ischaemic disease also affects the lower extremities. Considerable advances in both surgical bypassing and percutaneous revascularization techniques have been reached. However, many patients cannot benefit from these therapies because of the extension of arterial occlusion and/or microcirculation impairment. Consequently, the need for alternative therapeutic strategies is compelling. An innovative approach consists of stimulating collateral vessel growth, a natural host defence response that intervenes upon occurrence of critical reduction in tissue perfusion (Isner & Asahara, 1999). This review will debate the relevance of therapeutic angiogenesis for promotion of tissue repair. The following issues will receive attention: (a) vascular growth patterns, (b) delivery systems for angiogenesis gene transfer, (c) achievements of therapeutic angiogenesis in myocardial and peripheral ischaemia, and (d) future directions to improve effectiveness and safety of vascular gene therapy.

Cationic liposome-mediated gene delivery to the liver and to hepatocellular carcinomas in mice

The potential of cationic liposomes as nonviral vectors for in vivo gene delivery to the liver and to intrahepatic hepatocellular carcinoma (HCC) was investigated. Mice were injected via the tail vein or portal vein with a cationic lipid complexed to plasmid DNA (pDNA) encoding the chloramphenicol acetyltransferase (CAT) reporter gene at various cationic lipid:pDNA molar ratios to analyze the efficiency of gene delivery after intravenous administration. Tail vein injection resulted in high CAT expression levels in lung and spleen and low levels in the liver. Portal vein injection, by comparison, significantly enhanced hepatic reporter gene expression but also resulted in pronounced hepatic toxicity. Gene delivery to intrahepatic tumors produced by intrahepatic injection of human HCC cells was analyzed in nude mice. Tail vein injection as well as portal vein injection resulted in low levels of gene expression in intrahepatic tumors. By comparison, high levels of gene expression were achieved by direct, intratumoral injection of liposome-pDNA complexes, with only minimal expression in the surrounding normal liver. Therefore, direct liposome-pDNA complex injection appears far superior to systemic or portal intravenous administration for gene therapy of localized intrahepatic tumors, and may be a useful adjunct in the treatment of human HCCs.

Specific organ gene transfer in vivo by regional organ perfusion with herpes viral amplicon vectors: implications for local gene therapy

BACKGROUND

Many gene therapy strategies would benefit from efficient, regional organ delivery of therapeutic genes.

METHODS

Regional perfusions of lung, liver, or bladder were performed to determine if rapid and efficient gene transfer can be accomplished in vivo, and to determine if in vivo gene transfer can be limited to the organ of interest. In addition, herpes simplex virus tumor necrosis factor (HSVtnf), carrying the human tumor necrosis factoralpha gene was used as a treatment for methylcholanthrene sarcoma in a syngeneic lung metastases model in Fisher rats.

RESULTS

A 20-minute perfusion using HSV carrying beta-galactosidase (HSVlac) produced significant expression of this marker gene isolated to the target organs, without organ-specific tissue injury or inflammation. Regional perfusion of organs with HSV carrying the cytokine gene tumor necrosis factor alpha also resulted in high-level local organ production of this cytokine (2851 +/- 53 pg/g tissue in perfused lung versus 0 for the contralateral lung). For the current vector construct, expression of the gene of interest peaked between 2 and 4 days and was undetectable by 2 weeks after perfusion. In animals undergoing perfusion as treatment for pulmonary sarcoma, there was no difference between tumor counts in lungs perfused with HSVlac (17 +/- 6) or HSVtnf (22 +/- 8), but either treatment resulted in lower tumor counts than controls (111 +/- 24 nodules per lung, P <.02).

CONCLUSIONS

Regional organ perfusion using herpes viral vectors is an effective and well-tolerated in vivo method of transiently delivering potentially toxic gene products to target organs in directing gene therapy. Regional lung perfusion with HSV amplicons reduces tumor burden in a rat model of pulmonary metastases, though HSVtnf cannot be demonstrated to augment the cytopathic effect of the HSV amplicon alone in the current model.

Adrenomedullin gene delivery attenuates hypertension, cardiac remodeling, and renal injury in deoxycorticosterone acetate-salt hypertensive rats

Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide that plays an important role in cardiorenal function. In this study, we explored the potential protective role of AM in volume-dependent hypertension by somatic gene delivery. Adenovirus containing the human AM cDNA under the control of the cytomegalovirus promoter/enhancer was administered into deoxycorticosterone acetate (DOCA)-salt hypertensive rats via tail vein injection. A single injection of the human AM gene resulted in a prolonged reduction of blood pressure with a maximal reduction of 41 mm Hg 9 days after gene delivery. Human AM gene delivery enhanced renal function, as indicated by a 3-fold increase in renal blood flow and a 2-fold increase in glomerular filtration rate (n=5, P<0.05). Histological examination of the kidney revealed a significant reduction in glomerular sclerosis, tubular injury, luminol protein cast accumulation, and interstitial fibrosis as well as urinary protein. Human AM gene delivery caused significant decreases in left ventricular weight and cardiomyocyte diameter, which were accompanied by reduced interstitial fibrosis and extracellular matrix formation within the heart. Expression of human AM mRNA was detected in the kidney, adrenal gland, heart, aorta, lung, and liver; immunoreactive human AM levels were measured in urine and plasma. Significant increases in urinary and cardiac cAMP levels were observed in DOCA-salt rats receiving the human AM gene, indicating activation of the AM receptor. These findings showed that AM gene delivery attenuates hypertension, protects against cardiac remodeling and renal damage in volume-overload hypertension, and may have significance in therapeutic applications in cardiovascular and renal diseases.

Reduced cardiac hypertrophy and altered blood pressure control in transgenic rats with the human tissue kallikrein gene

To evaluate the cardiovascular actions of kinins, we established a transgenic rat line harboring the human tissue kallikrein gene, TGR(hKLK1). Under the control of the zinc-inducible metallothionein promoter, the transgene was expressed in most tissues including the heart, kidney, lung, and brain, and human kallikrein was detected in the urine of transgenic animals. Transgenic rats had a lower 24-h mean arterial pressure in comparison with control rats, which was further decreased when their diet was supplemented with zinc. The day/night rhythm of blood pressure was significantly diminished in TGR(hKLK1) animals, whereas the circadian rhythms of heart rate and locomotor activity were unaffected. Induction of cardiac hypertrophy by isoproterenol treatment revealed a marked protective effect of the kallikrein transgene because the cardiac weight of TGR(hKLK1) increased significantly less, and the expression of atrial natriuretic peptide and collagen III as markers for hypertrophy and fibrosis, respectively, were less enhanced. The specific kinin-B2 receptor antagonist, icatibant, abolished this cardioprotective effect. In conclusion, the kallikrein-kinin system is an important determinant in the regulation of blood pressure and its circadian rhythmicity. It also exerts antihypertrophic and antifibrotic actions in the heart.

Adenovirus-mediated kallikrein gene delivery attenuates hypertension and protects against renal injury in deoxycorticosterone-salt rats

To demonstrate potential therapeutic effects of kallikrein gene delivery in salt-induced hypertension and renal diseases, we delivered adenovirus carrying the human tissue kallikrein gene (Ad.CMV-cHK) into deoxycorticosterone acetate (DOCA)-salt hypertensive rats. A single intravenous injection of Ad.CMV-cHK caused a delay in the rise of blood pressure that began 2 days post gene delivery and lasted for more than 23 days. A maximal blood pressure reduction of 50 mm Hg was observed in rats receiving kallikrein gene delivery, as compared to rats receiving adenovirus containing the luciferase gene (Ad.CMV-Luc) (172 +/- 5 vs. 222 +/- 13 mm Hg, n = 6, P < 0.01). Throughout the experimental period, a blood pressure reduction of at least 32 mm Hg was observed in the DOCA-salt rats injected with Ad.CMV-cHK as compared to DOCA-salt rats receiving control adenovirus. Immunoreactive human tissue kallikrein levels were detected in rat serum and urine post gene delivery. Adenovirus-mediated kallikrein gene delivery caused a significant reduction in urinary excretion, urinary protein levels and body weight. Morphological examination of the kidney showed that kallikrein gene transfer significantly reduced DOCA-salt-induced glomerular sclerotic lesions, brush border disruption of proximal tubules, tubular dilatation and protein cast accumulation. These findings showed that the expression of human tissue kallikrein via gene delivery has protective effects against hypertension and renal injury in DOCA-salt hypertensive rats.

Potassium supplement upregulates the expression of renal kallikrein and bradykinin B2 receptor in SHR

High potassium intake is known to attenuate hypertension, glomerular lesion, ischemic damage, and stroke-associated death. Our recent studies showed that expression of recombinant kallikrein by somatic gene delivery reduced high blood pressure, cardiac hypertrophy, and renal injury in hypertensive animal models. The aim of this study is to explore the potential role of the tissue kallikrein-kinin system in blood pressure reduction and renal protection in spontaneously hypertensive rats (SHR) on a high-potassium diet. Young SHR were given drinking water with or without 1% potassium chloride for 6 wk. Systolic blood pressure was significantly reduced beginning at 1 wk, and the effect lasted for 6 wk in the potassium-supplemented group compared with that in the control group. Potassium supplement induced 70 and 40% increases in urinary kallikrein levels and renal bradykinin B2 receptor density, respectively (P < 0.05), but did not change serum kininogen levels. Similarly, Northern blot analysis showed that renal kallikrein mRNA levels increased 2.7-fold, whereas hepatic kininogen mRNA levels remained unchanged in rats with high potassium intake. No difference was observed in beta-actin mRNA levels in the kidney or liver of either group. Competitive RT-PCR showed a 1.7-fold increase in renal bradykinin B2 receptor mRNA levels in rats with high potassium intake. Potassium supplement significantly increased water intake, urine excretion, urinary kinin, cAMP, and cGMP levels. This study suggests that upregulation of the tissue kallikrein-kinin system may be attributed, in part, to blood pressure-lowering and diuretic effects of high potassium intake.

Human kallikrein gene delivery protects against gentamycin-induced nephrotoxicity in rats

The tissue kallikrein-kinin system has been shown to play important roles in cardiovascular and renal function. The aim of this study was to investigate potential protective effects of kallikrein gene delivery in gentamycin-induced nephrotoxicity. Rats were injected subcutaneously with gentamycin daily for 10 to 14 days. Adenovirus, Ad.CMV-cHK carrying the human tissue kallikrein gene or Ad.CMV-LacZ carrying the beta-galactosidase gene under the control of the cytomegalovirus promoter, were delivered intravenously on the first day of gentamycin administration. The expression of human tissue kallikrein mRNA was identified in the kidney, aorta, heart and liver and immunoreactive human kallikrein levels were measured in the serum and urine of rats receiving kallikrein gene delivery. Adenovirus-mediated kallikrein gene delivery significantly increased the renal blood flow, glomerular filtration rates, and urine flow while it attenuated renal tubular damage, cellular necrosis, lumenal protein casts and reduced ventricular weight and cardiomyocyte size. Kallikrein gene delivery caused a decrease in blood urea nitrogen levels and increases in urinary kinin and nitrite/nitrate levels. This study shows that kallikrein gene delivery exhibits protection against gentamycin-induced nephrotoxicity, and raises the potential for kallikrein gene therapy to treat drug-induced renal diseases.

Kallikrein gene delivery attenuates hypertension and cardiac hypertrophy and enhances renal function in Goldblatt hypertensive rats

To demonstrate potential therapeutic effects of kallikrein gene delivery, we delivered adenovirus (Ad.CMV-cHK) carrying the human tissue kallikrein gene into two-kidney, one-clip Goldblatt hypertensive rats. A single intravenous injection of the recombinant adenovirus caused a delay of blood pressure increase that began 1 day after injection and continued for 24 days. A maximal blood pressure reduction was observed in rats receiving kallikrein gene delivery compared with control rats receiving Ad.CMV-LacZ (160+/-5 versus 186+/-7 mm Hg, n=6, P<.01). The expression of human tissue kallikrein mRNA was identified in the kidney, heart, aorta, and liver of rats receiving kallikrein gene delivery. Immunoreactive human kallikrein levels were measured in rat serum and urine in a time-dependent manner. Adenovirus-mediated kallikrein gene delivery caused a significant reduction in the left ventricular mass and cardiomyocyte size, as well as an increase in renal blood flow, urine flow, glomerular filtration rates, electrolyte output, and urine excretion. Enhanced renal responses were accompanied by significant increases in urinary kinin, nitrite/nitrate, and cyclic GMP levels. These findings show that the expression of human tissue kallikrein via gene delivery has protective effects against renovascular hypertension and cardiovascular and renal dysfunction.

Identification of human plasma kallikrein gene polymorphisms and evaluation of their role in end-stage renal disease

Kallikreins are serine proteases that release kinins from kininogens. Kinins, via their effects on cardiovascular and renal function, may be involved in the pathogenesis of hypertension and renal failure. Two groups of kallikreins exist, glandular or tissue kallikrein and plasma kallikrein. In this study, we examined the human plasma kallikrein gene KLK3 to determine whether it contributed to end-stage renal disease (ESRD) susceptibility. We identified two novel polymorphic sequences closely linked to the KLK3 gene, designated KLK3b and KLK3c (heterozygosities: 0.64 to 0.68 and 0.48 to 0.52, respectively). We mapped the KLK3 gene and the marker KLK3c to the long arm of human chromosome 4 between F11 and D4S426 using a radiation hybrid panel. The study population consisted of 142 sibling pairs concordant for ESRD from 121 African American families. The 142 sibling pairs were stratified into 78 pairs with hypertension- and chronic glomerulonephritis-associated ESRD and 64 with non-insulin-dependent diabetes mellitus-associated ESRD. Linkage analyses, using SIBPAL of SAGE, and exclusion analysis, using MAPMAKERS/SIBS, were performed. Linkage analysis of affected sibling pairs did not reveal any evidence of linkage of KLK3 to ESRD in all 142 sib-pairs or in the two stratified subsets. Exclusion analysis indicated that the KLK3 gene could be excluded from contributing to ESRD at a relative risk of 3 when the maximum log of the odds score of -2 was used as the criterion for exclusion. However, an association analysis using the relative predispositional effect technique showed that alleles 7 and 9 of KLK3b were consistently associated with ESRD. Alleles 7 and 9 were present in 11.2% and 10.8% of the 113 unrelated ESRD probands and in 6.6% and 6.6% of the 204 race-matched control subjects without renal disease (allele P=.0041 and .0016, respectively). Alleles 7 and 9 were also present in 13% and 10.4% of the proband's first siblings (allele P=.00014 and .0087, respectively). The association of KLK3b alleles with ESRD raises the possibility that polymorphisms in KLK3 may play a role in ESRD susceptibility. The lack of linkage might reflect our relatively small family set.

Central delivery of human tissue kallikrein gene reduces blood pressure in hypertensive rats

The human tissue kallikrein gene, in the form of naked DNA (CMV-cHK) or an adenoviral vector (Ad.CMV-cHK), was directly delivered by intracerebroventricular injection into spontaneously hypertensive rats. Control rats received the same amount of vector DNA (pcDNA3) or adenoviral vector (Ad.CMV-LacZ) carrying the lacZ gene. A single injection of the human tissue kallikrein gene caused a rapid and prolonged blood pressure-lowering effect that began 1 day post injection and the effect lasted for more than 7 days. The expression of human tissue kallikrein and its mRNA was identified in the cortex, cerebellum, brain stem, hippocampus and hypothalamus. Cellular localization of beta-galactosidase was detected by X-gal staining in the thalamus, hypothalamus and third ventricle in rats injected with Ad.CMV-LacZ. This suggests that the tissue kallikrein-kinin system may function in the central control of blood pressure homeostasis.

In vivo gene delivery to the liver using reconstituted chylomicron remnants as a novel nonviral vector

Lipoproteins are emulsion particles that consist of lipids and apolipoproteins. Their natural function is to transport lipids and/or cholesterol to different tissues. We have taken advantage of the hydrophobic interior of these natural emulsions to solubilize DNA. Negatively charged DNA was first complexed with cationic lipids containing a quaternary amine head group. The resulting hydrophobic complex was extracted by chloroform and then incorporated into reconstituted chylomicron remnant particles ( approximately 100 nm in diameter) with an efficiency approximately 65%. When injected into the portal vein of mice, there were approximately 5 ng of a transgene product (luciferase) produced per mg of liver protein per 100 microg injected DNA. This level of transgene expression was approximately 100-fold higher than that of mice injected with naked DNA. However, such a high expression was not found after tail vein injection. Histochemical examination revealed that a large number of parenchymal cells and other types of cells in the liver expressed the transgene. Gene expression in the liver increased with increasing injected dose, and was nearly saturated with 50 microg DNA. At this dose, the expression was kept at high level in the liver for 2 days and then gradually reduced and almost disappeared by 7 days. However, by additional injection at day 7, gene expression in the liver was completely restored. By injection of plasmid DNA encoding human alpha1-antitrypsin, significant concentrations of hAAT were detected in the serum of injected animals. This is the first nonviral vector that resembles a natural lipoprotein carrier.

Prolonged reduction of high blood pressure with human nitric oxide synthase gene delivery

Endothelium-derived nitric oxide (NO) in peripheral vessels has been shown to modulate vascular resistance and blood pressure. We explored the effect of a continuous supply of human endothelial NO synthase (eNOS) on the blood pressure of spontaneously hypertensive rats (SHR) by somatic gene delivery. A DNA construct containing the human eNOS gene fused to the cytomegalovirus promoter/enhancer was injected into SHR through the tail vein. A single injection of the naked eNOS plasmid DNA caused a significant reduction of systemic blood pressure for 5 to 6 weeks in SHR, and the effect continued for up to 10 to 12 weeks after a second injection. The differences were significant from 2 to 12 weeks postinjections (n=6, P<.01). In a separate experiment, L-arginine, the substrate of eNOS, was supplied in drinking water at a concentration of 7.5 g/L for 11 weeks after eNOS gene delivery. A maximal blood pressure reduction of 21 mm Hg in SHR was observed with eNOS DNA compared with that of control SHR injected with vector DNA (181.9+/-1.46 versus 202.7+/-2.79 mm Hg, mean+/-SEM, n=6, P<.01). Human eNOS gene delivery induces significant increases in urinary and aortic cGMP levels and urinary and serum nitrite/nitrate content (P<.05), while no significant differences in body weight, heart rate, water intake, food consumption, or urine excretion were observed. These results indicate that somatic delivery of the human eNOS gene induces a prolonged reduction of high blood pressure and raises the potential of using eNOS gene therapy for hypertension and cardiovascular diseases.

Expression of human tissue kallikrein in rat salivary glands and its secretion into circulation following adenovirus-mediated gene transfer

Replication-deficient adenovirus Ad.CMV-cHK, expressing human tissue kallikrein under the control of the cytomegalovirus enhancer/promoter, was introduced into rat salivary glands via a direct intracapsular injection. A single injection of Ad.CMV-cHK at a dose of 4 x 10(9) pfu resulted in a sustained expression of human tissue kallikrein in rat salivary glands. The level of immunoreactive human tissue kallikrein in rat sera was the highest at 1 day post gene delivery when both salivary glands were injected and decreased in a time-dependent manner after gene delivery. Human tissue kallikrein levels in sera increased concomitantly with the amount of adenovirus used in direct salivary injection. The detection of human tissue kallikrein in sera after gene delivery into salivary glands provided direct evidence indicating that rat salivary glands secrete locally synthesized human tissue kallikrein to the systemic circulation. The direct injection of salivary glands with replication-deficient adenovirus could provide a systemic route for gene delivery for studying salivary gland function and development. Targeted gene delivery to the salivary gland may provide the means to express therapeutic proteins in saliva and the systemic circulation.

Kallikrein gene therapy: a new strategy for hypertensive diseases

The tissue kallikrein-kinin system has been postulated to play a role in blood pressure homeostasis and the pathogenesis of clinical hypertension. To demonstrate the potential therapeutic effects of somatic gene delivery in treating hypertension, we used spontaneously hypertensive rats (SHR) as a model. The gene encoding the human tissue kallikrein was used because of its powerful hypotensive action. The human kallikrein DNA constructs were placed under the control of the metallothionein metal response element, the cytomegalovirus promoter/enhancer or the Rous sarcoma virus 3'-LTR. The human tissue kallikrein DNA constructs were incorporated into adenoviral vectors via homologous recombination. The naked plasmid DNA constructs or adenovirus containing the kallikrein gene were first introduced into kidney 293 cells and the expression of human tissue kallikrein was identified by ELISA. The kallikrein gene was delivered into SHR via intramuscular, intravenous, portal vein, intraperitoneal, and intracerebroventricular routes. A single injection of naked human kallikrein DNA constructs caused a prolonged reduction of high blood pressure for up to 8 weeks. Adenoviral-mediated gene delivery results in high efficiency of human tissue kallikrein expression. Immunoreactive human kallikrein was detected in rat serum at the highest level at 1 day post gene delivery. Portal vein delivery of a reporter gene, AdCMV-LacZ, results in intense staining of beta-galactosidase in rat liver, suggesting that recombinant kallikrein is mainly produced in liver and secreted into the circulation. These results show that kallikrein gene delivery causes a sustained reduction of blood pressure in genetically hypertensive rats and provide important information for a potential gene therapy approach to human hypertension and related diseases.

Adenovirus-mediated delivery of human kallistatin gene reduces blood pressure of spontaneously hypertensive rats

Human kallistatin, or human tissue kallikrein-binding protein (HKBP), is a serine proteinase inhibitor (serpin). Transgenic mice overexpressing rat kallikrein-binding protein are hypotensive. To elucidate therapeutic potentials of kallistatin in hypertension, the human kallistatin gene in an adenoviral vector was directly introduced into spontaneously hypertensive rats (SHR) through portal vein injection. The kallistatin cDNA construct (RSV-cHKBP) under the promoter control of Rous sarcoma virus 3' long terminal repeat (LTR) was incorporated into adenovirus (Ad.RSV-cHKBP). Recombinant kallistatin in 293 cells transfected with RSV-cHKBP or Ad.RSV-cHKBP was measured by ELISA and by its complex formation with tissue kallikrein. A single intraportal vein injection of Ad.RSV-cHKBP at a dose of 8 x 10(10) pfu results in a significant reduction of blood pressure of SHR for 4 weeks. Human kallistatin mRNA was detected in the liver, spleen, kidney, aorta, and lung of rats receiving gene delivery. Immunoreactive human kallistatin in rat serum was detected at the highest level 1 day post injection and at lesser amounts in rat tissues. This study shows that adenovirus harboring Ad.RSV-cHKBP produces functional kallistatin, and adenovirus-mediated transfer of the human kallistatin gene reduces blood pressures of SHR. The results suggest that kallistatin may function as a vasodilator in vivo and provide important information for a potential gene therapy approach to hypertension.