Apelin-13: a novel approach to suppressing renin production in RVHT.

Renovascular hypertension (RVHT) is characterized by renal artery stenosis and overactivated renin-angiotensin system (RAS). Apelin, known for its negative modulation of RAS, has protective effects against cardiovascular diseases. The role and mechanisms of the primary active form of apelin, apelin-13, in RVHT are unclear. In this study, male Sprague-Dawley rats were divided into control, two-kidney one-clip (2K1C) model, and 2K1C with apelin-13 treatment groups. Renin expression was analyzed using immunohistochemistry and molecular techniques. Full-length (pro)renin receptor (fPRR) and soluble PRR (sPRR) levels were assessed via Western blotting, and cAMP levels were measured using ELISA. Plasma renin content, plasma renin activity (PRA), angiotensin II (ANG II), and sPRR levels were determined by ELISA. Human Calu-6 and mouse As4.1 cells were used to investigate renin production mechanisms. The 2K1C model exhibited increased systolic blood pressure, plasma renin content, PRA, sPRR, and ANG II levels, while apelin-13 treatment reduced these elevations. Apelin-13 inhibited cAMP production, renin mRNA expression, protein synthesis, and PRR/sPRR protein expression in renal tissue. In Calu-6 cells, cAMP-induced fPRR and site-1 protease (S1P)-derived sPRR expression, which was blocked by cAMP-responsive element-binding protein (CREB) inhibition. Apelin-13 suppressed cAMP elevation, CREB phosphorylation, fPRR/sPRR protein expression, and renin production. Recombinant sPRR (sPRR-His) stimulated renin production, which was inhibited by the PRR decoy peptide PRO20 and S1P inhibitor PF429242. These findings suggest that apelin-13 inhibits plasma renin expression through the cAMP/PKA/sPRR pathway, providing a potential therapeutic approach for RVHT. Understanding the regulation of renin production is crucial for developing effective treatments.NEW & NOTEWORTHY Our research elucidated that apelin-13 inhibits renin production through the cAMP/PKA/soluble (pro)renin receptor pathway, presenting a promising therapeutic approach for renovascular hypertension (RVHT) by targeting renin expression mechanisms. These findings underscore the potential of apelin-13 as a novel strategy to address RVHT.

Comparative assessment of CacyBP/SIP, ß-catenin and cannabinoid receptors in the adrenals of hypertensive rats.

Taking into account homeostatic disorders resulting from arterial hypertension and the key importance of CacyBP/SIP, ß-catenin and endocannabinoids in the functioning of many organs, it was decided to assess the presence and distribution of CacyBP/SIP, ß-catenin, CB1 and CB2 in the adrenal glands of hypertensive rats of various aetiology. The study was conducted on the adrenal glands of rats with spontaneous and renovascular hypertension. The expression of CacyBP/SIP, ß-catenin, CB1 and CB2 was detected by immunohistochemistry and real-time PCR method. The results of the present study revealed both lower gene expression and immunoreactivity of CacyBP/SIP in the adrenal glands of all hypertensive groups compared to the normotensive rats. This study demonstrated a reduction in the immunoreactivity and expression of the ß-catenin, CB1 and CB2 genes in the adrenals of 2K1C rats. While in SHR, the reaction showing ß-catenin and CB1 was very weak or negative, and the expression of CB2 in the adrenal glands of these rats increased. The results of this study show, for the first time, marked differences in the expression of CacyBP/SIP, ß-catenin and CB1 and CB2 cannabinoid receptors in the adrenal glands of rats with primary (SHR) and secondary hypertension (2K1C).

Molecular genetic evaluation of pediatric renovascular hypertension due to renal artery stenosis and abdominal aortic coarctation in neurofibromatosis type 1.

The etiology of renal artery stenosis (RAS) and abdominal aortic coarctation (AAC) causing the midaortic syndrome (MAS), often resulting in renovascular hypertension (RVH), remains ill-defined. Neurofibromatosis type 1 (NF-1) is frequently observed in children with RVH. Consecutive pediatric patients (N = 102) presenting with RVH secondary to RAS with and without concurrent AAC were prospectively enrolled in a clinical data base, and blood, saliva and operative tissue, when available, were collected. Among the 102 children, 13 were having a concurrent clinical diagnosis of NF-1 (12.5%). Whole exome sequencing was performed for germline variant detection, and RNA-Seq analysis of NF1, MAPK pathway genes and MCP1 levels were undertaken in five NF-1 stenotic renal arteries, as well as control renal and mesenteric arteries from children with no known vasculopathy or NF-1. In 11 unrelated children with sequencing data, 11 NF1 genetic variants were identified, of which 10 had not been reported in gnomAD. Histologic analysis of NF-1 RAS specimens consistently revealed intimal thickening, disruption of the internal elastic lamina and medial thinning. Analysis of transcript expression in arterial lesions documented an approximately 5-fold reduction in NF1 expression, confirming heterozygosity, MAPK pathway activation and increased MCP1 expression. In summary, NF-1-related RVH in children is rare but often severe and progressive and, as such, important to recognize. It is associated with histologic and molecular features consistent with an aggressive adverse vascular remodeling process. Further research is necessary to define the mechanisms underlying these findings.

OXGR1-Dependent (Pro)Renin Receptor Upregulation in Collecting Ducts of the Clipped Kidney Contributes to Na+ Balance in Goldblatt Hypertensive Mice.

The two-kidney, one-clip (2K1C) Goldblatt rodent model elicits a reduction in renal blood flow (RBF) in the clipped kidney (CK). The reduced RBF and oxygen bio-ability causes the accumulation of the tricarboxylic cycle intermediary, α-ketoglutarate, which activates the oxoglutarate receptor-1 (OXGR1). In the kidney, OXGR1 is abundantly expressed in intercalated cells (ICs) of the collecting duct (CD), thus contributing to sodium transport and electrolyte balance. The (pro)renin receptor (PRR), a member of the renin-angiotensin system (RAS), is a key regulator of sodium reabsorption and blood pressure (BP) that is expressed in ICs. The PRR is upregulated in 2K1C rats. Here, we tested the hypothesis that chronic reduction in RBF in the CK leads to OXGR1-dependent PRR upregulation in the CD and alters sodium balance and BP in 2K1C mice. To determine the role of OXGR1 in regulating the PRR in the CDs during renovascular hypertension, we performed 2K1C Goldblatt surgery (clip = 0.13 mm internal gap, 14 days) in two groups of male mice: (1) mice treated with Montelukast (OXGR1 antagonist; 5 mg/Kg/day); (2) OXGR1-/- knockout mice. Wild-type and sham-operated mice were used as controls. After 14 days, 2K1C mice showed increased systolic BP (SBP) (108 ± 11 vs. control 82 ± 5 mmHg, p < 0.01) and a lower natriuretic response after the saline challenge test. The CK group showed upregulation of erythropoietin, augmented α-ketoglutarate, and increased PRR expression in the renal medulla. The CK of OXGR1 knockout mice and mice subjected to the OXGR1 antagonist elicited impaired PRR upregulation, attenuated SBP, and better natriuretic responses. In 2K1C mice, the effect of reduced RBF on the OXGR1-dependent PRR upregulation in the CK may contribute to the anti-natriuretic and increased SBP responses.

Genetic Deletion of AT1a Receptor or Na+/H+ Exchanger 3 Selectively in the Proximal Tubules of the Kidney Attenuates Two-Kidney, One-Clip Goldblatt Hypertension in Mice.

The roles of angiotensin II (Ang II) AT1 (AT1a) receptors and its downstream target Na+/H+ exchanger 3 (NHE3) in the proximal tubules in the development of two-kidney, 1-clip (2K1C) Goldblatt hypertension have not been investigated previously. The present study tested the hypothesis that deletion of the AT1a receptor or NHE3 selectively in the proximal tubules of the kidney attenuates the development of 2K1C hypertension using novel mouse models with proximal tubule-specific deletion of AT1a receptors or NHE3. 2K1C Goldblatt hypertension was induced by placing a silver clip (0.12 mm) on the left renal artery for 4 weeks in adult male wild-type (WT), global Agtr1a−/−, proximal tubule (PT)-specific PT-Agtr1a−/− or PT-Nhe3−/− mice, respectively. As expected, telemetry blood pressure increased in a time-dependent manner in WT mice, reaching a maximal response by Week 3 (p < 0.01). 2K1C hypertension in WT mice was associated with increases in renin expression in the clipped kidney and decreases in the nonclipped kidney (p < 0.05). Plasma and kidney Ang II were significantly increased in WT mice with 2K1C hypertension (p < 0.05). Tubulointerstitial fibrotic responses were significantly increased in the clipped kidney (p < 0.01). Whole-body deletion of AT1a receptors completely blocked the development of 2K1C hypertension in Agtr1a−/− mice (p < 0.01 vs. WT). Likewise, proximal tubule-specific deletion of Agtr1a in PT-Agtr1a−/− mice or NHE3 in PT-Nhe3−/− mice also blocked the development of 2K1C hypertension (p < 0.01 vs. WT). Taken together, the present study provides new evidence for a critical role of proximal tubule Ang II/AT1 (AT1a)/NHE3 axis in the development of 2K1C Goldblatt hypertension.

Renovascular hypertension and RNF213 p.R4810K variant in Korean children with Moyamoya disease.

Moyamoya disease (MMD) is the most common underlying disease in Korean pediatric renovascular hypertension (RVH). The ring finger protein 213 (RNF213) p.R4810K variant is reported to be a pathologic variant in East Asian MMD. The purpose of this study was to evaluate hypertension (HTN) prevalence and clinical manifestations as well as RNF213 p.R4810K variant prevalence in Korean pediatric MMD patients. The medical records of pediatric MMD patients from January 2000 to June 2018 were retrospectively reviewed. RVH was confirmed by computer tomography angiography or renal Doppler ultrasonography. The American Academy of Pediatrics 2017 guideline for sex-, age-, and height-related blood pressure standards was used to define HTN. Of 706 patients with MMD, 40 (5.7%) had HTN. Among these patients, 22 had RVH and 12 had HTN with no evidence of renal artery stenosis (non-RVH). Patients with MMD and RVH had an MMD onset at a younger age and lower body mass index compared to those with MMD and non-RVH. Among the patients with MMD and HTN, 4 presented with HTN before developing MMD. Genetic testing for the RNF213 p.R4810K variant was performed in 32 patients with MMD and HTN. When the patient had a homozygous RNF213 p.R4810K variant, the odds ratio of RVH to non-RVH was 8.3. Our study suggests that RVH is more prevalent than non-RVH in pediatric MMD patients. Furthermore, RNF213 p.R4810K may be the cause of RVH in Korean children with MMD.

A postzygotic KRAS mutation in a patient with Schimmelpenning syndrome presenting with lipomatosis, renovascular hypertension, and diabetes mellitus.

Schimmelpenning syndrome is a rare neurocutaneous disorder categorized as a mosaic RASopathy due to postzygotic HRAS or KRAS mutations. We report a 6-year-old girl diagnosed with Schimmelpenning syndrome due to a postzygotic KRAS G12D mutation. The patient had three atypical symptoms of Schimmelpenning syndrome: renovascular hypertension, congenital lipomatosis, and diabetes mellitus. The first two symptoms may overlap with phenotypes of other neurocutaneous syndromes or congenital lipomatous overgrowth syndrome due to mosaic RASopathies or other somatic mosaic mutations. We propose that impaired glucose tolerance was caused by KRAS mutation and a novel clinical phenotype of Schimmelpenning syndrome. Our study indicated that clinical diagnosis of Schimmelpenning syndrome or related conditions should be reorganized with genetic diagnosis of postzygotic mutation. Moreover, further accumulation of genetically proven cases with mosaic RASopathies should be used to more accurately characterize phenotypic presentations of this syndrome and develop a future therapeutic strategy, such as molecular-targeted therapy.

Hemorrhagic stroke and renovascular hypertension with Grange syndrome arising from a novel pathogenic variant in YY1AP1.

Pediatric hypertension can cause hypertensive emergencies, including hemorrhagic stroke, contributing to rare but serious childhood morbidity and mortality. Renovascular hypertension (RVH) is one of the major causes of secondary hypertension in children. Grange syndrome (MIM#602531) is a rare disease characterized by multiple stenosis or occlusion of the renal, abdominal, coronary, and cerebral arteries, which can cause phenotypes of RVH and fibromuscular dysplasia (MIM#135580). We report the case of a 7-year-old girl with Grange syndrome who showed RVH and multiple seizure episodes. At 1 year of age, she experienced seizures and sequential hemiparesis caused by a left thalamic hemorrhage without cerebral vascular anomalies. Chronic hypertension was observed, and abdominal computed tomography angiography showed characteristic bilateral renal artery stenosis. Whole-exome sequencing revealed a novel homozygous pathogenic variant in the YY1AP1 gene (NM_001198903.1: c.1169del: p.Lys390Argfs*12). Biallelic YY1AP1 mutations are known to cause Grange syndrome. Unlike previously reported patients, our patient presented with intracerebral hemorrhagic stroke without anomalous brain artery or bone fragility. The phenotype in our patient may help better understand this ultra-rare syndrome. Grange syndrome should be considered in patients presenting with childhood-onset hypertension and/or hemorrhagic stroke for early clinical intervention.

Boldine Improves Kidney Damage in the Goldblatt 2K1C Model Avoiding the Increase in TGF-ß.

Boldine, a major aporphine alkaloid found in the Chilean boldo tree, is a potent antioxidant. Oxidative stress plays a detrimental role in the pathogenesis of kidney damage in renovascular hypertension (RVH). The activation of the renin-angiotensin system (RAS) is crucial to the development and progression of hypertensive renal damage and TGF-β is closely associated with the activation of RAS. In the present study, we assessed the effect of boldine on the progression of kidney disease using the 2K1C hypertension model and identifying mediators in the RAS, such as TGF-β, that could be modulated by this alkaloid. Toward this hypothesis, rats (n = 5/group) were treated with boldine (50 mg/kg/day, gavage) for six weeks after 2K1C surgery (pressure ≥ 180 mmHg). Kidney function was evaluated by measuring of proteinuria/creatininuria ratio (U prot/U Crea), oxidative stress (OS) by measuring thiobarbituric acid reactive substances (TBARS). The evolution of systolic blood pressure (SBP) was followed weekly. Alpha-smooth muscle actin (α-SMA) and Col III were used as markers of kidney damage; ED-1 and osteopontin (OPN) were used as markers of inflammation. We also explored the effect in RAS mediators, such as ACE-1 and TGF-β. Boldine treatment reduced the UProt/UCrea ratio, plasma TBARS, and slightly reduced SBP in 2K1C hypertensive rats, producing no effect in control animals. In 2K1C rats treated with boldine the levels of α-SMA, Col III, ED-1, and OPN were lower when compared to 2K1C rats. Boldine prevented the increase in ACE-1 and TGF-β in 2K1C rats, suggesting that boldine reduces kidney damage. These results suggest that boldine could potentially be used as a nutraceutic.

Dynamics of Distribution of Capillaries with Matrix Metalloproteinase-2 and Its Tissue Inhibitor in Rat Brain during Development of Experimental Hypertension.

The capillaries containing MMP-2 and its tissue inhibitor TIMP-2 were examined in cerebral cortex and white matter obtained from intact Wistar rats (n=5) and the rats with progressing experimental renovascular hypertension (n=35). In hypertensive rats, the changes in intensity of the immunohistochemical reaction and in the density of capillaries expressing TIMP-2 significantly differed from the corresponding values in MMP-2-positive capillaries, which resulted in pronounced deviation of MMP-2/TIMP-2 index from the control level (especially in cerebral cortex) probably attesting to enhanced risk of complications in cases with arterial hypertension.

Blockade of CCR2 reduces macrophage influx and development of chronic renal damage in murine renovascular hypertension.

Renovascular hypertension (RVH) is a common cause of both cardiovascular and renal morbidity and mortality. In renal artery stenosis (RAS), atrophy in the stenotic kidney is associated with an influx of macrophages and other mononuclear cells. We tested the hypothesis that chemokine receptor 2 (CCR2) inhibition would reduce chronic renal injury by reducing macrophage influx in the stenotic kidney of mice with RAS. We employed a well-established murine model of RVH to define the relationship between macrophage infiltration and development of renal atrophy in the stenotic kidney. To determine the role of chemokine ligand 2 (CCL2)/CCR2 signaling in the development of renal atrophy, mice were treated with the CCR2 inhibitor RS-102895 at the time of RAS surgery and followed for 4 wk. Renal tubular epithelial cells expressed CCL2 by 3 days following surgery, a time at which no significant light microscopic alterations, including interstitial inflammation, were identified. Macrophage influx increased with time following surgery. At 4 wk, the development of severe renal atrophy was accompanied by an influx of inducible nitric oxide synthase (iNOS)+ and CD206+ macrophages that coexpressed F4/80, with a modest increase in macrophages coexpressing arginase 1 and F4/80. The CCR2 inhibitor RS-102895 attenuated renal atrophy and significantly reduced the number of dual-stained F4/80+ iNOS+ and F4/80+ CD206+ but not F4/80+ arginase 1+ macrophages. CCR2 inhibition reduces iNOS+ and CD206+ macrophage accumulation that coexpress F4/80 and renal atrophy in experimental renal artery stenosis. CCR2 blockade may provide a novel therapeutic approach to humans with RVH.

Spontaneous white matter lesion in brain of stroke-prone renovascular hypertensive rats: a study from MRI, pathology and behavior.

Hypertension is considered one of the most important controllable risk factors for white matter lesion (WML). Our previous work found that stroke-prone renovascular hypertensive rats (RHRSP) displayed a high rate of WML. This study aimed to investigate the WML in RHRSP from MRI, pathology and behavior. RHRSP model was established by two-kidney, two-clipmethod and kept for 20 weeks. WML was decteted by magnetic resonance imaging (MRI) and loyez staining. Cognition was tested by morris water maze (MWM). Vascular changes were observed by HE staining on brain and carotid sections. Ultrastucture of blood brain barrier (BBB) were observed by transmission electron microscope. Immunofluorescence was used to detect albumin leakage and cell proliferation. T(2)-weighted MRI scans of RHRSP displayed diffuse, confluent white-matter hyperintensities. Pathological examination of the same rat showed marked vacuoles, disappearence of myelin and nerve fibers in white matter, supporting the neuroimaging findings. Spatial learning and memory impairment were observed in RHRSP. The small arteries in brain exhibited fibrinoid necrosis, hyalinosis and vascular remodeling. BBB disruption and plasma albumin leakage into vascular wall was observed in RHRSP. Increased cell proliferation in subventricular zone was seen in RHRSP. RHRSP demonstrated spontaneous WML and cognitive impairment. Hypertensive small vessel lesions and BBB disruption might paly causative factors for the onset and development of WML. The characteristic features of WML in RHRSP suggested it a valid animal model for WML.

Co-existence of renovascular hypertension, polyarteritis nodosa, antiphospholipid syndrome and methylenetetrahydrofolate reductase mutation.

We present a hypertensive child with a co-existence of polyarteritis nodosa, anti-phospholipid antibodies (aPL), methylenetetrahydrofolate reductase (MTHFR) mutation and increased lipoprotein a level. Elevated renin, aldosterone and aPL levels, micro-aneurysms, occlusion and thrombosis at left and right renal artery were found. Anti-hypertensive agents, prednisolone and pulse cyclophosphamide therapy were started and a stent was inserted in the left renal artery. Two months later, brain magnetic resonance imaging/magnetic resonance imaging angiography showed acute infarct area of the left parietofrontal lobe and middle cerebral artery stenosis. We found bilateral peripheral neuropathy, persistent aPL and elevated Lp(a) level and heterozygous A1298C/MTHFR mutation. Intravenous immunoglobulin and low-molecular-weight heparin treatment was added. In conclusion, our observation suggests that in patients with systemic vasculitis, such as polyarteritis nodosa, aPL are probably associated with greater thrombotic risks. The investigation of the LP(a) levels and MTHFR mutations as a synergic pro-coagulant effect might also be considered for determining patients with vasculitis at risk for severe thrombotic events.

[Effect of puerarin combined with felodipine on mRNA and protein expression of apelin and APJ in renovascular hypertensive rat].

OBJECTIVE: To explore the effect of puerarin combined with felodipine on the mRNA and protein expression of apelin and APJ in renal tissue of renovascular hypertensive rat. METHOD: Sixty-two Sprague-Dawley rats were used, of which 8 rats were randomly chosen as sham-operation group. The remaining rats were made for the rat model with renovascular hypertension. The renovascular hypertensive rats were randomly divided into 5 groups as follows: 4 groups which were treated with felodipine (0.8 mg x kg(-1) x d(-1)), puerarin (50 mg x kg(-1) x d(-1)), puerarin combined with felodipine (puerarin 25 mg x kg(-1) x d(-1) + felodipine 0.4 mg x kg(-1) x d(-1)) or captopril combined with felodipine (captopril 15 mg x kg(-1) x d(-1) x felodipine 0.4 mg x kg(-1) x d(-1)), and 1 group which was treated with distilled water. Drugs or distilled water were administered for 8 weeks. The expression of apelin and APJ mRNA and protein in ischemic and non-ischemic kidneys was assessed by RT-PCR or Western blot. RESULT: Compared with sham-operation group, the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys in model group was increased significantly (P < 0.01); the expression of APJ mRNA and protein in ischemic kidneys had no significance, while that in non-ischemic kidneys was decreased (P < 0. 01). Compared with model group, the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys was decreased significantly in all drug-treated groups (P < 0.01); while that of APJ mRNA and protein in non-ischemic kidneys was upregulated (P < 0.01). Compared with felodipine group, the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys was decreased (P < 0.01 or P < 0.05) in the group treated with both puerarin and felodipine; and the expression of APJ mRNA and protein in ischemic kidneys did not reach significant level, however, that was upregulated in non-ischemic kidneys (P < 0.01 or P < 0.05). CONCLUSION: Puerarin downregulates the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys, and upregulates that of APJ mRNA and protein in non-ischemic kidneys. Combination of puerarin and felodipine enhances the above-mentioned effects and shows no significant difference versus the combination of felodipine and captopril. The results suggest that puerarin regulates blood pressure and protects target organ through apelin/APJ pathway and that puerarin has synergetic effects with CCB.

Increased endogenous H2S generation by CBS, CSE, and 3MST gene therapy improves ex vivo renovascular relaxation in hyperhomocysteinemia.

Hydrogen sulfide (H(2)S) has recently been identified as a regulator of various physiological events, including vasodilation, angiogenesis, antiapoptotic, and cellular signaling. Endogenously, H(2)S is produced as a metabolite of homocysteine (Hcy) by cystathionine ß-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST). Although Hcy is recognized as vascular risk factor at an elevated level [hyperhomocysteinemia (HHcy)] and contributes to vascular injury leading to renovascular dysfunction, the exact mechanism is unclear. The goal of the current study was to investigate whether conversion of Hcy to H(2)S improves renovascular function. Ex vivo renal artery culture with CBS, CSE, and 3MST triple gene therapy generated more H(2)S in the presence of Hcy, and these arteries were more responsive to endothelial-dependent vasodilation compared with nontransfected arteries treated with high Hcy. Cross section of triple gene-delivered renal arteries immunostaining suggested increased expression of CD31 and VEGF and diminished expression of the antiangiogenic factor endostatin. In vitro endothelial cell culture demonstrated increased mitophagy during high levels of Hcy and was mitigated by triple gene delivery. Also, dephosphorylated Akt and phosphorylated FoxO3 in HHcy were reversed by H(2)S or triple gene delivery. Upregulated matrix metalloproteinases-13 and downregulated tissue inhibitor of metalloproteinase-1 in HHcy were normalized by overexpression of triple genes. Together, these results suggest that H(2)S plays a key role in renovasculopathy during HHcy and is mediated through Akt/FoxO3 pathways. We conclude that conversion of Hcy to H(2)S by CBS, CSE, or 3MST triple gene therapy improves renovascular function in HHcy.

Genetic deficiency of Smad3 protects the kidneys from atrophy and interstitial fibrosis in 2K1C hypertension.

Although the two-kidney, one-clip (2K1C) model is widely used as a model of human renovascular hypertension, mechanisms leading to the development of fibrosis and atrophy in the cuffed kidney and compensatory hyperplasia in the contralateral kidney have not been defined. Based on the well-established role of the transforming growth factor (TGF)-ß signaling pathway in renal fibrosis, we tested the hypothesis that abrogation of TGF-ß/Smad3 signaling would prevent fibrosis in the cuffed kidney. Renal artery stenosis (RAS) was established in mice with a targeted disruption of exon 2 of the Smad3 gene (Smad3 KO) and wild-type (WT) controls by placement of a polytetrafluoroethylene cuff on the right renal artery. Serial pulse-wave Doppler ultrasound assessments verified that blood flow through the cuffed renal artery was decreased to a similar extent in Smad3 KO and WT mice. Two weeks after surgery, systolic blood pressure and plasma renin activity were significantly elevated in both the Smad3 KO and WT mice. The cuffed kidney of WT mice developed renal atrophy (50% reduction in weight after 6 wk, P < 0.0001), which was associated with the development of interstitial fibrosis, tubular atrophy, and interstitial inflammation. Remarkably, despite a similar reduction of renal blood flow, the cuffed kidney of the Smad3 KO mice showed minimal atrophy (9% reduction in weight, P = not significant), with no significant histopathological alterations (interstitial fibrosis, tubular atrophy, and interstitial inflammation). We conclude that abrogation of TGF-ß/Smad3 signaling confers protection against the development of fibrosis and atrophy in RAS.

Energy deficit as a possible factor for the induction of caspase-dependent apoptosis in left ventricular myocardial cells during genetically determined and secondary arterial hypertension.

Activities of caspase-3 and caspase-8 in the left ventricular myocardium of Chinchilla rabbits with renovascular arterial hypertension and spontaneously hypertensive rats were measured after 10-day administration of a macroergic compound phosphocreatine. Treatment with phosphocreatine prevented activation of caspase-3, but had no effect on caspase-8 during secondary and genetically determined arterial hypertension. Our results indicate that the intrinsic mechanism of the induction of the caspase cascade in myocardial cells dominates over the extrinsic pathway during both types of arterial hypertension. Energy deficit is one of the inducing factors of these processes.

RNA sequencing reveals induction of specific renal inflammatory pathways in a rat model of malignant hypertension.

In malignant hypertension, far more severe kidney injury occurs than in the "benign" form of the disease. The role of high blood pressure and the renin-angiotensin-aldosterone system is well recognized, but the pathogenesis of the renal injury of malignant hypertension (MH) remains incompletely understood. Using the rat model of two-kidney, one-clip renovascular hypertension in which some but not all animals develop MH, we performed a transcriptomic analysis of gene expression by RNA sequencing to identify transcriptional changes in the kidney cortex specific for MH. Differential gene expression was assessed in three groups: MH, non-malignant hypertension (NMH), and normotensive, sham-operated controls. To distinguish MH from NMH, we considered two factors: weight loss and typical renovascular lesions. Mean blood pressure measured intraarterially was elevated in MH (220 ± 6.5 mmHg) as well as in NMH (192 ± 6.4 mmHg), compared to controls (119 ± 1.7 mmHg, p < 0.05). Eight hundred eighty-six genes were exclusively regulated in MH only. Principal component analysis revealed a separated clustering of the three groups. The data pointed to an upregulation of many inflammatory mechanisms in MH including pathways which previously attracted relatively little attention in the setting of hypertensive kidney injury: Transcripts from all three complement activation pathways were upregulated in MH compared to NMH but not in NMH compared with controls; immunohistochemistry confirmed complement deposition in MH exclusively. The expression of chemokines attracting neutrophil granulocytes (CXCL6) and infiltration of myeloperoxidase-positive cells were increased only in MH rats. The data suggest that these pathways, especially complement deposition, may contribute to kidney injury under MH. KEY MESSAGES: The most severe hypertension-induced kidney injury occurs in malignant hypertension. In a rat model of malignant hypertension, we assessed transcriptional responses in the kidney exposed to high blood pressure. A broad stimulation of inflammatory mechanisms was observed, but a few specific pathways were activated only in the malignant form of the disease, notably activation of the complement cascades. Complement inhibitors may alleviate the thrombotic microangiopathy of malignant hypertension even in the absence of primary complement abnormalities.

The Transcription Factor Sox6 Controls Renin Expression during Renal Artery Stenosis.

Background: Renal artery stenosis (RAStenosis) or renal artery occlusion is an intractable problem affecting about 6% of people >65 and up to 40% of people with coronary or peripheral vascular disease in the Unites States. The renal renin-angiotensin-aldosterone system plays a key role in RAStenosis, with renin (which is mainly produced in the kidney) being recognized as the driver of the disease. In this study, we will determine a new function for the transcription factor Sox6 in the control of renal renin during RAStenosis. Methods: We hypothesize that knocking out Sox6 in Ren1d-positive cells will protect mice against renovascular hypertension and kidney injury. To test our hypothesis, we used a new transgenic mouse model, Ren1dcre/Sox6fl/fl (Sox6 KO), in which Sox6 is knocked out in renin-expressing cells. We used a modified two-kidney, one-clip (2K1C) Goldblatt mouse model to induce RAStenosis and renovascular hypertension. BP was measured using the tail-cuff method. Renin, prorenin, Sox6, and NGAL expressions levels were measured with Western blot, in situ hybridization, and immunohistochemistry. Creatinine levels were measured using the colorimetric assay. Results: Systolic BP was significantly lower in Sox6 KO 2 weeks after RAStenosis compared with Sox6 WT (Ren1dcre/Sox6wt/wt). Renin, prorenin, and NGAL expression levels in the stenosed kidney were lower in Sox6 KO compared with Sox6 WT mice. Furthermore, creatinine clearance was preserved in Sox6 KO compared with Sox6 WT mice. Conclusions: Our data indicate that Sox6 controls renal renin and prorenin expression and, as such, has a function in renovascular hypertension induced by RAStenosis. These results point to a novel transcriptional regulatory network controlled by Sox6.