Review on Molecular Mechanism of Hypertensive Nephropathy.

Hypertension, a prevalent chronic ailment, has the potential to impair kidney function, and thereby resulting in hypertensive nephropathy. The escalating incidence of hypertensive nephropathy attributed to the aging population in urban areas, has emerged as a prominent cause of end-stage renal disease. Nevertheless, the intricate pathogenesis of hypertensive nephropathy poses considerable obstacles in terms of precise clinical diagnosis and treatment. This paper aims to consolidate the research findings on the pathogenesis of hypertensive nephropathy by focusing on the perspective of molecular biology.

Single-cell transcriptomics uncover hub genes and cell-cell crosstalk in patients with hypertensive nephropathy.

Hypertensive nephropathy (HTN) is one of the leading causes of end-stage renal disease, yet the molecular mechanisms are still unknown. To explore novel mechanisms and gene targets for HTN, the gene expression profiles of renal biopsy samples obtained from 2 healthy living donor controls and 5 HTN patients were determined by single-cell RNA sequencing. Key hub genes expression were validated by the Nephroseq v5 platform. The HTN endothelium upregulated cellular adhesion genes (ICAM2 and CEACAM1), inflammatory genes (ETS2 and IFI6) and apoptosis related genes (CNN3). Proximal tubules in HTN highly expressed hub genes including BBOX1, TPM1, TMSB10, SDC4, and NUP58, which might be potential novel targets for proximal tubular injury. The upregulated genes in tubules of HTN were mainly participating in inflammatory signatures including IFN-γ signature, NF-κB signaling, IL-12 signaling and Wnt signaling pathway. Receptor-ligand interaction analysis indicated potential cell-cell crosstalk between endothelial cells or mesangial cells with other renal resident cells in HTN. Together, our data identify a distinct cell-specific gene expression profile, pathogenic inflammatory signaling and potential cell-cell communications between endothelial cells or mesangial cells with other renal resident cells in HTN. These findings may provide a promising novel landscape for mechanisms and treatment of human HTN.

The metabolic effects of APOL1 in humans.

Harboring apolipoprotein L1 (APOL1) variants coded by the G1 or G2 alleles of the APOL1 gene increases the risk for collapsing glomerulopathy, focal segmental glomerulosclerosis, albuminuria, chronic kidney disease, and accelerated kidney function decline towards end-stage kidney disease. However, most subjects carrying APOL1 variants do not develop the kidney phenotype unless a second clinical condition adds to the genotype, indicating that modifying factors modulate the genotype-phenotype correlation. Subjects with an APOL1 high-risk genotype are more likely to develop essential hypertension or obesity, suggesting that carriers of APOL1 risk variants experience more pronounced insulin resistance compared to noncarriers. Likewise, arterionephrosclerosis (the pathological correlate of hypertension-associated nephropathy) and glomerulomegaly take place among carriers of APOL1 risk variants, and these pathological changes are also present in conditions associated with insulin resistance, such as essential hypertension, aging, and diabetes. Insulin resistance may contribute to the clinical features associated with the APOL1 high-risk genotype. Unlike carriers of wild-type APOL1, bearers of APOL1 variants show impaired formation of lipid droplets, which may contribute to inducing insulin resistance. Nascent lipid droplets normally detach from the endoplasmic reticulum into the cytoplasm, although the proteins that enable this process remain to be fully defined. Wild-type APOL1 is located in the lipid droplet, whereas mutated APOL1 remains sited at the endoplasmic reticulum, suggesting that normal APOL1 may participate in lipid droplet biogenesis. The defective formation of lipid droplets is associated with insulin resistance, which in turn may modulate the clinical phenotype present in carriers of APOL1 risk variants.

Deacetylation of Septin4 by SIRT2 (Silent Mating Type Information Regulation 2 Homolog-2) Mitigates Damaging of Hypertensive Nephropathy.

BACKGROUND: Hypertension can lead to podocyte damage and subsequent apoptosis, eventually resulting in glomerulosclerosis. Although alleviating podocyte apoptosis has clinical significance for the treatment of hypertensive nephropathy, an effective therapeutic target has not yet been identified. The function of septin4, a proapoptotic protein and an important marker of organ damage, is regulated by post-translational modification. However, the exact role of septin4 in regulating podocyte apoptosis and its connection to hypertensive renal damage remains unclear. METHODS: We investigated the function and mechanism of septin4 in hypertensive nephropathy to discover a theoretical basis for targeted treatment. Mouse models including Rosa 26 (Gt(ROSA)26Sor)-SIRT2 (silent mating type information regulation 2 homolog-2)-Flag-TG (transgenic) (SIRT2-TG) mice SIRT2-knockout, and septin4-K174Q mutant mice, combined with proteomic and acetyl proteomics analysis, followed by multiple molecular biological methodologies, were used to demonstrate mechanisms of SIRT2-mediated deacetylation of septin4-K174 in hypertensive nephropathy. RESULTS: Using transgenic septin4-K174Q mutant mice treated with the antioxidant Tempol, we found that hyperacetylation of the K174 site of septin4 exacerbates Ang II (angiotensin II)- induced hypertensive renal injury resulting from oxidative stress. Proteomics and Western blotting assays indicated that septin4-K174Q activates the cleaved-PARP1 (poly [ADP-ribose] polymerase family, member 1)-cleaved-caspase3 pathway. In septin4-knockdown human renal podocytes, septin4-K174R, which mimics deacetylation at K174, rescues podocyte apoptosis induced by Ang II. Immunoprecipitation and mass spectrometry analyses identified SIRT2 as a deacetylase that interacts with the septin4 GTPase domain and deacetylates septin4-K174. In Sirt2-deficient mice and SIRT2-knockdown renal podocytes, septin4-K174 remains hyperacetylated and exacerbates hypertensive renal injury. By contrast, in Rosa26-Sirt2-Flag (SIRT2-TG) mice and SIRT2-knockdown renal podocytes reexpressing wild-type SIRT2, septin4-K174 is hypoacetylated and mitigates hypertensive renal injury. CONCLUSIONS: Septin4, when activated through acetylation of K174 (K174Q), promotes hypertensive renal injury. Septin4-K174R, which mimics deacetylation by SIRT2, inhibits the cleaved-PARP1-cleaved-caspase3 pathway. Septin4-K174R acts as a renal protective factor, mitigating Ang II-induced hypertensive renal injury. These findings indicate that septin4-K174 is a potential therapeutic target for the treatment of hypertensive renal injury.

The adducin saga: pleiotropic genomic targets for precision medicine in human hypertension-vascular, renal, and cognitive diseases.

Hypertension is a leading risk factor for stroke, heart disease, chronic kidney disease, vascular cognitive impairment, and Alzheimer's disease. Previous genetic studies have nominated hundreds of genes linked to hypertension, and renal and cognitive diseases. Some have been advanced as candidate genes by showing that they can alter blood pressure or renal and cerebral vascular function in knockout animals; however, final validation of the causal variants and underlying mechanisms has remained elusive. This review chronicles 40 years of work, from the initial identification of adducin (ADD) as an ACTIN-binding protein suggested to increase blood pressure in Milan hypertensive rats, to the discovery of a mutation in ADD1 as a candidate gene for hypertension in rats that were subsequently linked to hypertension in man. More recently, a recessive K572Q mutation in ADD3 was identified in Fawn-Hooded Hypertensive (FHH) and Milan Normotensive (MNS) rats that develop renal disease, which is absent in resistant strains. ADD3 dimerizes with ADD1 to form functional ADD protein. The mutation in ADD3 disrupts a critical ACTIN-binding site necessary for its interactions with actin and spectrin to regulate the cytoskeleton. Studies using Add3 KO and transgenic strains, as well as a genetic complementation study in FHH and MNS rats, confirmed that the K572Q mutation in ADD3 plays a causal role in altering the myogenic response and autoregulation of renal and cerebral blood flow, resulting in increased susceptibility to hypertension-induced renal disease and cerebral vascular and cognitive dysfunction.

Sirt6-mediated Nrf2/HO-1 activation alleviates angiotensin II-induced DNA DSBs and apoptosis in podocytes.

Recent studies suggested that DNA double-strand breaks (DSBs) were associated with the pathogenesis of chronic kidney disease (CKD). The purpose of this investigation was to determine the role of Sirtuin6 (Sirt6), a histone deacetylase related to DNA damage repair, in angiotensin (Ang) II-induced DNA DSBs and the cell injury of podocytes and explore the possible mechanism. Here we showed that an increase of DNA DSBs was accompanied by a reduction in Sirt6 expression in the glomeruli of patients with hypertensive nephropathy (HN). Similar results were found in rat kidneys infused with Ang II and in cultured podocytes stimulated with Ang II. Sirt6 overexpression inhibited Ang II-induced ROS generation and DNA DSBs, and thus served as a protection against Ang II-induced apoptosis in podocytes. Moreover, Sirt6 activation enhanced Nrf2 and HO-1 gene expressions in podocytes after Ang II treatment. Furthermore, Nrf2 knockdown could partly reverse the cytoprotective effects of Sirt6 activation. In conclusion, our observations demonstrated that the Sirt6-Nrf2-HO-1 pathway played a vital role in relieving Ang II-mediated oxidative DNA damage and podocyte injury.

A Genome-Wide Association Study for Hypertensive Kidney Disease in Korean Men.

Hypertension is one of the major risk factors for chronic kidney disease (CKD), and the coexistence of hypertension and CKD increases morbidity and mortality. Although many genetic factors have been identified separately for hypertension and kidney disease, studies specifically focused on hypertensive kidney disease (HKD) have been rare. Therefore, this study aimed to identify loci or genes associated with HKD. A genome-wide association study (GWAS) was conducted using two Korean cohorts, the Health Examinee (HEXA) and Korean Association REsource (KARE). Consequently, 19 single nucleotide polymorphisms (SNPs) were found to be significantly associated with HKD in the discovery and replication phases (p < 5 × 10-8, p < 0.05, respectively). We further analyzed HKD-related traits such as the estimated glomerular filtration rate (eGFR), creatinine, blood urea nitrogen (BUN), systolic blood pressure (SBP) and diastolic blood pressure (DBP) at the 14q21.2 locus, which showed a strong linkage disequilibrium (LD). Expression quantitative trait loci (eQTL) analysis was also performed to determine whether HKD-related SNPs affect gene expression changes in glomerular and arterial tissues. The results suggested that the FANCM gene may affect the development of HKD through an integrated analysis of eQTL and GWAS and was the most significantly associated candidate gene. Taken together, this study indicated that the FANCM gene is involved in the pathogenesis of HKD. Additionally, our results will be useful in prioritizing other genes for further experiments.

Telmisartan Attenuates the Growth of Epithelium-like Cells and Glomerular Injury in Spontaneously Hypertensive Rats.

The abnormal growth of epithelium-like cells has been noticed in spontaneously hypertensive rats (SHRs) with hypertensive nephropathy. However, the characteristics of abnormal epithelium-like cells and their pathogenesis in hypertensive nephropathy are not fully understood. In the present study, we investigated the correlation of epithelium-like cells with glomerular injury, and the effects of early drug intervention with telmisartan, an anti-hypertensive drug, on the growth of epithelium-like cells. The results showed that the epithelium-like cells were obviously observed lining along the luminal surface of Bowman's capsule in glomeruli, significantly resulting in the atrophy of the glomerular tuft. Some of the epithelium-like cells strongly expressed proliferating cell nuclear antigen (PCNA) and vimentin, indicating active cellular proliferation. The incidence of epithelium-like cells varied from 13.6% to 54.4% of glomeruli in 48-week-old SHRs, and from 5.1% to 18.0% of glomeruli in age-matched Wistar-Kyoto (WKY) rats (P<0.01). The linear regression analysis further confirmed an obvious correlation between the incidence of epithelium-like cells and the glomerular injury. Moreover, early intervention with telmisartan could dramatically attenuate the progression of epithelium-like cells growth. However, no significant effect of telmisartan on the established epithelium-like cells was observed. Taken together, we demonstrated the involvement of abnormal epithelium-like cells growth in glomerular injury during hypertensive nephropathy in SHRs, and firstly showed the positive effects of the anti-hypertensive drug on the progression of epithelium-like cells growth.

Negative correlation of urinary miR-199a-3p level with ameliorating effects of sarpogrelate and cilostazol in hypertensive diabetic nephropathy.

The prevalence of chronic kidney disease is increasing globally; however, effective therapeutic options are limited. In this study, we aimed to identify urinary miRNAs reflecting the effect of therapeutic intervention in rats with comorbid hypertension and diabetes. Additionally, the potential beneficial effects of anti-platelet sarpogrelate and cilostazol were investigated. Nephropathy progression in streptozotocin (STZ)-treated spontaneously hypertensive rats (SHRs), including albuminuria, collagen deposition, and histopathological changes, was alleviated by sarpogrelate and antihypertensive agent telmisartan. Global analysis of urinary miRNAs identified that miR-199a-3p was commonly reduced by sarpogrelate and telmisartan treatment. In vitro analysis suggested CD151 as a target gene of miR-199a-3p: miR-199a-3p overexpression repressed CD151 levels and miR-199a-3p interacted with the 3'-untranslated region of the CD151 gene. In addition, we demonstrated that the miR-199a-3p/CD151 axis is associated with the transforming growth factor-ß1 (TGF-ß1)-induced fibrogenic pathway. TGF-ß1 treatment led to miR-199a-3p elevation and CD151 suppression, and miR-199a-3p overexpression or CD151-silencing enhanced TGF-ß1-inducible collagen IV and α-smooth muscle actin (α-SMA) levels. In vivo analysis showed that the decrease in CD151 and the increase in collagen IV and α-SMA in the kidney from STZ-treated SHR were restored by sarpogrelate and telmisartan administration. In an additional animal experiment using cilostazol and telmisartan, there was a correlation between urinary miR-199a-3p reduction and the ameliorating effects of cilostazol or combination with telmisartan. Collectively, these results indicate that urinary miR-199a-3p might be utilized as a marker for nephropathy treatment. We also provide evidence of the benefits of antiplatelet sarpogrelate and cilostazol in nephropathy progression.

The research status and prospect of Periostin in chronic kidney disease.

The continuous accumulation of extracellular matrix will eventually lead to glomerular sclerosis, interstitial fibrosis, tubular atrophy and vascular sclerosis, which are involved in the progression of chronic kidney disease (CKD). If these processes can be discovered early and effective interventions given in time, the progression of kidney disease may be delayed. Therefore, exploring new biomarkers and therapeutic targets that can identify CKD at an early stage is urgently needed. In recent years, studies have shown that urine periostin may be used as a marker of early renal tubular injury. And in an animal model experiment of hypertensive nephropathy, periostin is involved in the progression of kidney injury and reflects its progression. Here we review the current progress on the role of periostin in pathologic pathways of kidney system to explore whether periostin is a potential therapeutic target for the treatment of CKD.

Identification of biomarkers and pathways in hypertensive nephropathy based on the ceRNA regulatory network.

BACKGROUND: Hypertensive nephropathy (HTN) is a kind of renal injury caused by chronic hypertension, which seriously affect people's life. The purpose of this study was to identify the potential biomarkers of HTN and understand its possible mechanisms. METHODS: The dataset numbered GSE28260 related to hypertensive and normotensive was downloaded from NCBI Gene Expression Omnibus. Then, the differentially expressed RNAs (DERs) were screened using R limma package, and functional analyses of DE-mRNA were performed by DAVID. Afterwards, a ceRNA network was established and KEGG pathway was analyzed based on the Gene Set Enrichment Analysis (GSEA) database. Finally, a ceRNA regulatory network directly associated with HTN was proposed. RESULTS: A total of 947 DERs were identified, including 900 DE-mRNAs, 20 DE-lncRNAs and 27 DE-miRNAs. Based on these DE-mRNAs, they were involved in biological processes such as fatty acid beta-oxidation, IRE1-mediated unfolded protein response, and transmembrane transport, and many KEGG pathways like glycine, serine and threonine metabolism, carbon metabolism. Subsequently, lncRNAs KCTD21-AS1, LINC00470 and SNHG14 were found to be hub nodes in the ceRNA regulatory network. KEGG analysis showed that insulin signaling pathway, glycine, serine and threonine metabolism, pathways in cancer, lysosome, and apoptosis was associated with hypertensive. Finally, insulin signaling pathway was screened to directly associate with HTN and was regulated by mRNAs PPP1R3C, PPKAR2B and AKT3, miRNA has-miR-107, and lncRNAs SNHG14, TUG1, ZNF252P-AS1 and MIR503HG. CONCLUSIONS: Insulin signaling pathway was directly associated with HTN, and miRNA has-miR-107 and lncRNAs SNHG14, TUG1, ZNF252P-AS1 and MIR503HG were the biomarkers of HTN. These results would improve our understanding of the occurrence and development of HTN.

Dual deficiency of angiotensin-converting enzyme-2 and Mas receptor enhances angiotensin II-induced hypertension and hypertensive nephropathy.

Angiotensin-converting enzyme-2 (ACE2) and Mas receptor are the major components of the ACE2/Ang 1-7/Mas axis and have been shown to play a protective role in hypertension and hypertensive nephropathy individually. However, the effects of dual deficiency of ACE2 and Mas (ACE2/Mas) on Ang II-induced hypertensive nephropathy remain unexplored, which was investigated in this study in a mouse model of hypertension induced in either ACE2 knockout (KO) or Mas KO mice and in double ACE2/Mas KO mice by subcutaneously chronic infusion of Ang II. Compared with wild-type (WT) animals, mice lacking either ACE2 or Mas significantly increased blood pressure over 7-28 days following a chronic Ang II infusion (P < .001), which was further exacerbated in double ACE2/Mas KO mice (P < .001). Furthermore, compared to a single ACE2 or Mas KO mice, mice lacking ACE2/Mas developed more severe renal injury including higher levels of serum creatinine and a further reduction in creatinine clearance, and progressive renal inflammation and fibrosis. Mechanistically, worsen hypertensive nephropathy in double ACE2/Mas KO mice was associated with markedly enhanced AT1-ERK1/2-Smad3 and NF-κB signalling, thereby promoting renal fibrosis and renal inflammation in the hypertensive kidney. In conclusion, ACE2 and Mas play an additive protective role in Ang II-induced hypertension and hypertensive nephropathy. Thus, restoring the ACE2/Ang1-7/Mas axis may represent a novel therapy for hypertension and hypertensive nephropathy.

Effect of gasotransmitters treatment on expression of hypertension, vascular and cardiac remodeling and hypertensive nephropathy genes in left ventricular hypertrophy.

BACKGROUND: Cardiac and renal dysfunction are often co-morbid pathologies leading to worsening prognosis resulting in difficulty in therapy of left ventricular hypertrophy (LVH). The aim of the current study was to determine the changes in expression of human ortholog genes of hypertension, vascular and cardiac remodeling and hypertensive nephropathy phenotypes under normal, disease and upon treatment with gasotransmitter including H2S (hydrogen sulphide), NO (nitric oxide) and combined (H2S + NO). METHODS: A total of 72 Wistar Kyoto rats (with equivalent male and female animals) were recruited in the present study where LVH rat models were treated with H2S and NO individually as well as with both combined. Cardiac and renal physical indices were recorded and relative gene expression were quantified. RESULTS: Both cardiac and renal physical indices were significantly modified with individual as well as combined H2S + NO treatment in control and LVH rats. Expression analysis revealed, hypertension, vascular remodeling genes ACE, TNFα and IGF1, mRNAs to be significantly higher (P ≤ 0.05) in the myocardia and renal tissues of LVH rats, while individual and combined H2S + NO treatment resulted in lowering the gene expression to normal/near to normal levels. The cardiac remodeling genes MYH7, TGFß, SMAD4 and BRG1 expression were significantly up-regulated (P ≤ 0.05) in the myocardia of LVH where the combined H2S + NO treatment resulted in normal/near to normal expression more effectively as compared to individual treatments. In addition individual as well as combined H2S and NO treatment significantly decreased PKD1 expression in renal tissue, which was up-regulated in LVH rats (P ≤ 0.05). CONCLUSIONS: The reduction in hemodynamic parameters and cardiac indices as well as alteration in gene expression on treatment of LVH rat model indicates important therapeutic potential of combined treatment with H2S + NO gasotransmitters in hypertension and cardiac hypertrophy when present as co-morbidity with renal complications.

Krüppel-like factor 15 is a key suppressor of podocyte fibrosis under rotational force-driven pressure.

Krüppel-like factor 15 (KLF15) is a well-known transcription factor associated with podocyte injury and fibrosis. Recently, hypertensive nephropathy was discovered to be closely related to podocyte injury and fibrosis. However, methods to stimulate hypertension in vitro are lacking. Here, we constructed an in vitro model mimicking hypertension using a rotational force device to identify the role of KLF15 in fibrosis due to mechanically induced hypertensive injury. First, we found that KLF15 expression was decreased in patients with hypertensive nephropathy. Then, an in vitro study of hypertension due to rotational force was conducted, and an increase in fibrosis markers and decrease in KLF15 levels were determined after application of 4 mmHg pressure in primary cultured human podocytes. KLF15 and tight junction protein levels increased with retinoic acid treatment. siRNA-mediated inhibition of KLF15 exacerbated pressure-induced fibrosis injury, and KLF15 expression after treatment with angiotensin II was similar to that observed after treatment with the blood pressure modeling device. Furthermore, the reduced KLF15 levels after mechanical pressure application were restored after the administration of an antihypertensive drug. KLF15 expression was also low in vivo. We confirmed the protective role of KLF15 in fibrosis using a mechanically induced in vitro model of hypertensive injury.

Chromogranin A pathway: from pathogenic molecule to renal disease.

BACKGROUND: Chromogranin A (CHGA) is an index granin protein critical for biogenesis and exocytotic release of catecholamine storage granules. It is elevated in plasma of patients with sympathetic over-activity and kidney dysfunction. Several CHGA polymorphisms are associated with hypertensive kidney disease. Previously, we unraveled the molecular mechanism by which CHGA expression is regulated in African Americans carrying a genetic variation associated with hypertensive chronic kidney disease (CKD). METHOD: Experimental CKD mouse model were created by 5/6th nephrectomy (Npx) using wild-type and Chga-/- knockout mouse strains to delineate the role of CHGA in CKD. RESULT: Wild-type-Npx mice expressing Chga developed exacerbated azotemia and fibrosis as compared with their knockout-Npx counterparts. Gene expression profiling revealed downregulation of mitochondrial respiratory complexes genes consistent with maladaptive mitochondria in wild-type-Npx mice, contrasted to knockout-Npx. In healthy individuals, an inverse relationship between circulating CHGA levels and glomerular function was observed. In vitro, mesangial cells treated with CHGA-triggered nitric oxide release by a signaling mechanism involving scavenger receptor SR-A. The CHGA-treated and untreated mesangial cells displayed differential expression of cytokine, chemokine, complement, acute phase inflammatory and apoptotic pathway genes. Thus, build-up of plasma CHGA because of kidney injury served as an insult to the mesangial cells resulting in expression of genes promoting inflammation, fibrosis, and progression of CKD. CONCLUSION: These findings improve understanding of the role of elevated CHGA in the progression of CKD and reveal novel pathways that could be exploited for therapeutic strategies in hypertensive kidney disease.

Bromodomain-containing protein 4 contributes to renal fibrosis through the induction of epithelial-mesenchymal transition.

Fibrosis is a common pathology in renal disease. Hypertensive nephropathy (HN) is one of the most common secondary nephropathies that often progresses to severe renal fibrosis with limited treatment options beyond hypertension control. Bromodomain-containing protein 4 (Brd4) was recently recognized as a target in signaling pathways that underlie the pathologies of inflammatory diseases and tumors. A recently developed inhibitor of Brd4, JQ1, has been shown to exert antifibrotic effects and is being clinically explored as an anti-inflammatory and antitumor drug. Here, using human kidney biopsies and Angiotensin II-induced mouse fibrotic kidney samples, we show that Brd4 was upregulated in renal tissue from HN patients and hypertensive mouse models. In mice, JQ1 alleviated Angiotensin II-induced kidney fibrosis and blocked epithelial-mesenchymal transition (EMT) by altering the expression of EMT-related proteins. Using an in vitro model of HK2 cells exposed to Angiotensin II, we also demonstrated that JQ1 suppressed the protein expression of fibrotic genes in these cells. These results further implicate Brd4 in the fibrotic response in HN and reveal that Brd4 is a potential antifibrotic target. BET inhibitors are currently being investigated in clinical trials as antitumor agents and show potent pharmacological effects. Our findings suggest that BET inhibitors may also be potential translational therapies for HN.

Circulating miR-103a-3p contributes to angiotensin II-induced renal inflammation and fibrosis via a SNRK/NF-κB/p65 regulatory axis.

Although angiotensin II (AngII) is known to cause renal injury and fibrosis, the underlying mechanisms remain poorly characterized. Here we show that hypertensive nephropathy (HN) patients and AngII-infused mice exhibit elevated levels of circulating miR103a-3p. We observe a positive correlation between miR-103a-3p levels and AngII-induced renal dysfunction. miR-103a-3p suppresses expression of the sucrose non-fermentable-related serine/threonine-protein kinase SNRK in glomerular endothelial cells, and glomeruli of HN patients and AngII-infused mice show reduced endothelial expression of SNRK. We find that SNRK exerts anti-inflammatory effects by interacting with activated nuclear factor-κB (NF-κB)/p65. Overall, we demonstrate that AngII increases circulating miR-103a-3p levels, which reduces SNRK levels in glomerular endothelial cells, resulting in the over-activation of NF-κB/p65 and, consequently, renal inflammation and fibrosis. Together, our work identifies miR-103a-3p/SNRK/NF-κB/p65 as a regulatory axis of AngII-induced renal inflammation and fibrosis.

Knockout of Dual-Specificity Protein Phosphatase 5 Protects Against Hypertension-Induced Renal Injury.

Dual-specificity protein phosphatase 5 (DUSP5) is a member of the tyrosine-threonine phosphatase family with the ability to dephosphorylate and inactivate extracellular signal-related kinase (ERK). The present study investigates whether knockout (KO) of Dusp5 improves renal hemodynamics and protects against hypertension-induced renal injury. The renal expression of DUSP5 was reduced, and the levels of phosphorylated (p) ERK1/2 and p-protein kinase C (PKC) α were elevated in the KO rats. KO of Dusp5 enhanced the myogenic tone of the renal afferent arteriole and interlobular artery in vitro with or without induction of deoxycorticosterone acetate-salt hypertension. Inhibition of ERK1/2 and PKC diminished the myogenic response to a greater extent in Dusp5 KO rats. Autoregulation of renal blood flow was significantly impaired in hypertensive wild-type (WT) rats but remained intact in Dusp5 KO animals. Proteinuria was markedly decreased in hypertensive KO versus WT rats. The degree of glomerular injury was reduced, and the expression of nephrin in the glomerulus was higher in hypertensive Dusp5 KO rats. Renal fibrosis and medullary protein cast formation were attenuated in hypertensive Dusp5 KO rats in association with decreased expression of monocyte chemoattractant protein 1, transforming growth factor-ß1, matrix metalloproteinase (MMP) 2, and MMP9. These results indicate that KO of Dusp5 protects against hypertension-induced renal injury, at least in part, by maintaining the myogenic tone of the renal vasculature and extending the range of renal blood flow autoregulation to higher pressures, which diminish glomerular injury, protein cast formation, macrophage infiltration, and epithelial-mesenchymal transformation in the kidney. SIGNIFICANCE STATEMENT: Dual-specificity protein phosphatase 5 (DUSP5) is a tyrosine-threonine phosphatase that inactivates extracellular signal-related kinase (ERK). We previously reported that knockout (KO) of Dusp5 enhanced the myogenic response and autoregulation in the cerebral circulation. The present study investigates whether KO of DUSP5 improves renal hemodynamics and protects against hypertension-induced renal injury. Downregulation of DUSP5 enhanced the myogenic tone of renal arteriole and artery and autoregulation of renal blood flow in association with reduced proteinuria, glomerular injury, and interstitial fibrosis after the induction of hypertension. Inhibition of ERK1/2 and protein kinase C diminished the myogenic response to a greater extent in Dusp5 KO rats. These results suggest that DUSP5 might be a viable drug target for the treatment of hypertension nephropathy.

Mother and Child Reunion in "Hypertensive" End-Stage Renal Disease: Will They Complement Each Other?

Severe hypertension can lead to irreversible kidney failure and end-stage renal disease (ESRD) and vice versa. Patients are often classified as hypertensive ESRD with no confirmative proof and the true cause of disease can therefore be missed, affecting outcomes. We present a case of chronic thrombotic microangiopathy (TMA) after kidney transplantation in a recipient who had been classified as hypertensive ESRD and found to have a genetic defect in CD46, a transmembrane protein that regulates complement activation, indicating atypical hemolytic uremic syndrome (HUS). The pathogenic variant in CD46 was also found in the mother who donated the kidney, indicating that the TMA occurred on the background of atypical HUS instead of severe hypertension. The patient died from disseminated cancer originated in the mother's kidney. Knowledge of the genetic background would have prevented recurrent disease and the cancer to occur. Patients classified as hypertensive ESRD suspect for TMA should therefore be screened for variants in complement genes to make informed decisions and save kidneys.

MiR-101a ameliorates AngII-mediated hypertensive nephropathy by blockade of TGFß/Smad3 and NF-κB signalling in a mouse model of hypertension.

Hypertensive nephropathy, clinically characterized by progressive renal fibrosis and inflammation, is a severe complication of hypertension. The objectives of this study were to investigate the roles of miR-101a in relieving angiotensin II (Ang II)-mediated hypertensive nephropathy and uncover the possible underlying mechanisms. A hypertensive mouse model was established via continuous 28-day AngII infusion. Systolic blood pressure (SBP), ratio of urine albumin to creatinine, blood urea nitrogen (BUN), serum creatinine (Scr) and glomerular filtration rate (GFR) were evaluated. Dual luciferase reporter assay was used to explore the target of miR-101a. mRNA levels of miR-101a, TGFßRI, fibrotic markers (Collagen I and α-SMA) and pro-inflammatory cytokines (IL-1ß and TNF-α) were determined by real-time PCR. Protein levels of TGFßRI, Collagen I, α-SMA, IL-1ß, TNF-α, t-p65, P-p65, t-Smad3, P-Smad3, t-IκBα and P-IκBα were detected by western blot. MiR-101a mimics significantly improved GFR and inhibited AngII-induced increase in the ratio of urine albumin to creatinine, BUN and Scr. MiR-101a mimics partially abolished AngII-induced increase in the mRNA and protein level of fibrotic markers by targeting TGFßRI and inhibiting TGFß/Smad3 pathway. Moreover, TGFßRI inhibitor galunisertib inhibited AngII-mediated renal injury in mice with hypertensive nephropathy. Additionally, miR-101a overexpression blocked AngII-induced up-regulation of pro-inflammatory markers via suppressing NF-κB pathway. MiR-101a exhibited protective effects against hypertensive nephropathy via inhibiting TGFß/Smad3 and NF-κB signalling pathways.