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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. Angiotensin II is known to cause renal inflammation and fibrosis. Here Lu et al. show that levels of circulating miR-103a-3p are elevated in hypertensive nephropathy patients and in an animal model of angiotensin II-induced renal dysfunction, and that miR-103a-3p suppresses SNRK expression leading to the activation of the pro-inflammatory NF-κB pathway in glomerular endothelial cells.

Developmental programming in the kidney has been recognised for more than two decades, but its contribution to the global burden of kidney diseases remains underappreciated by policy makers.3 In view of the many factors known to affect fetal kidney development, including maternal health and nutrition, exposure to stress, poverty, pollutants, drugs, and infections during gestation,3 a holistic strategy to prevent such programming effects is consistent with the life-course approach and aligns with the United Nations (UN) Sustainable Development Goals to foster health.2 Chronic kidney disease is an important contributor to the NCD burden that has been relatively neglected in WHO's Global Action Plan for the Prevention and Control of NCDs, despite chronic kidney disease being a major cause of hypertension and a major risk multiplier of cardiovascular disease.1,4 Although the prevalence of chronic kidney disease in many low-income countries remains unknown, the disease is most prevalent among disadvantaged populations within industrialised nations-eg, African-Americans and Aboriginal Australians.5 The number of people receiving dialysis or transplantation is projected to double, from 2·6 million in 2010 to 5·4 million in 2030.6 In 2010, 2·3-7·1 million adults died from lack of access to dialysis and transplantation in low-income countries.6 In view of the clinical outcomes and often prohibitively high costs of treatment, prevention and early detection are the only sustainable solutions to address this growing global burden. 16

Current research on hypertension utilizes more than fifty animal models that rely mainly on stable increases in systolic blood pressure. In experimental hypertension, grading or scoring of glomerulopathy in the majority of studies is based on a wide range of opinion-based histological changes that do not necessarily comply with lesional descriptors for glomerular injury that are well-established in clinical pathology. Here, we provide a critical appraisal of experimental hypertensive glomerulopathy with the same approach used to assess hypertensive glomerulopathy in humans. Four hypertensive models with varying pathogenesis were analyzed–chronic angiotensin II infused mice, mice expressing active human renin in the liver (TTRhRen), spontaneously hypertensive rats (SHR), and Goldblatt two-kidney one-clip rats (2K1C). Analysis of glomerulopathy utilized the same criteria applied in humans–hyalinosis, focal segmental glomerulosclerosis (FSGS), ischemic, hypertrophic and solidified glomeruli, or global glomerulosclerosis (GGS). Data from animal models were compared to human reference values. Kidneys in TTRhRen mice, SHR and the nonclipped kidneys in 2K1C rats had no sign of hyalinosis, FSGS or GGS. Glomerulopathy in these groups was limited to variations in mesangial and capillary compartment volumes, with mild increases in collagen deposition. Histopathology in angiotensin II infused mice corresponded to mesangioproliferative glomerulonephritis, but not hypertensive glomerulosclerosis. The number of nephrons was significantly reduced in TTRhRen mice and SHR, but did not correlate with severity of glomerulopathy. The most substantial human-like glomerulosclerotic lesions, including FSGS, ischemic obsolescent glomeruli and GGS, were found in the clipped kidneys of 2K1C rats. The comparison of affected kidneys to healthy control in animals produces lesion values that are numerically impressive but correspond to mild damage if compared to humans. Animal studies should be standardized by employing the criteria and classifications established in human pathology to make experimental and human data fully comparable for comprehensive analysis and model improvements.

Non-surgical rodent chronic kidney disease (CKD) models for both glomerular and tubular injuries are currently limited. The current study aimed to develop a rat model of CKD by combining anti-Fx1A with N(ω)-Nitro-L-Arginine Methyl Ester (L-NAME) administrations. Rats were assigned to groups receiving L-NAME, anti-Fx1A, anti-Fx1A + L-NAME, or vehicle. Renal function, stiffness, renal injury biomarkers, histopathology and renal genome-wide transcriptomic changes were evaluated. Protein and renal injury biomarker levels in urine were elevated in the anti-Fx1A alone and combination group. Shear wave elastography revealed increased stiffness of the kidneys in all treatment groups. Histopathological evaluation revealed glomerular injury, characterized by enlarged glomeruli with increased hyaline materials in both anti-Fx1A groups and tubular degeneration/regeneration in the renal cortex of all treated groups with the highest incidence and severity in the combination group. These tubular changes were sometimes accompanied by interstitial mononuclear cell infiltrates and interstitial fibrosis. Proteinuria and mild changes in blood, urine renal injury biomarkers and imaging endpoints were noted in association with these histopathologic changes. The concurrence and higher incidence and/or severity of glomerular and tubular injuries in the combination group indicates that this would be a useful and relevant CKD model suitable for mechanistic, pharmacologic and toxicologic investigations.

Chemerin and its receptor, chemokine-like receptor 1 (CmklR1), are associated with chemotaxis, inflammation, and endothelial function, especially in metabolic syndrome, coronary heart disease, and hypertension. In humans, circulating chemerin levels and renal function show an inverse relation. So far, little is known about the potential role of chemerin in hypertensive nephropathy and renal inflammation. Therefore, we determined systemic and renal chemerin levels in 2-kidney-1-clip (2k1c) hypertensive and Thy1.1 nephritic rats, respectively, to explore the correlation between chemerin and markers of renal inflammation and fibrosis. Immunohistochemistry revealed a model-specific induction of chemerin expression at the corresponding site of renal damage (tubular vs. glomerular). In both models, renal expression of chemerin (RT-PCR, Western blot) was increased and correlated positively with markers of inflammation and fibrosis. In contrast, circulating chemerin levels remained unchanged. Taken together, these findings demonstrate that renal chemerin expression is associated with processes of inflammation and fibrosis-related to renal damage. However, its use as circulating biomarker of renal inflammation seems to be limited in our rat models.

Hypertensive nephropathy (HN) is one of the main causes of end-stage renal disease (ESRD), leading to serious morbidity and mortality in hypertensive patients. However, existing treatment for hypertensive nephropathy are still very limited. It has been demonstrated that aerobic exercise has beneficial effects on the treatment of hypertension. However, the underlying mechanisms of exercise in HN remain unclear. The spontaneously hypertensive rats (SHR) were trained for 8 weeks on a treadmill with different exercise prescriptions. We detected the effects of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on inflammatory response, renal function, and renal fibrosis in SHR. We further investigated the relationship between TLR4 and the NLRC4 inflammasome in vitro HN model. MICT improved renal fibrosis and renal injury, attenuating the inflammatory response by inhibiting TLR4/NF-κB pathway and the activation of NLRC4 inflammasome. However, these changes were not observed in the HIIT group. Additionally, repression of TLR4/NF-κB pathway by TAK-242 inhibited activation of NLRC4 inflammasome and alleviated the fibrosis in Ang II-induced HK-2 cells. MICT ameliorated renal damage, inflammatory response, and renal fibrosis via repressing TLR4/NF-κB pathway and the activation of NLRC4 inflammasome. This study might provide new references for exercise prescriptions of hypertension.

Pharmacological inhibition of the proximal tubular sodium-glucose linked cotransporter-2 (SGLT2) leads to glycosuria in both diabetic and non-diabetic settings. As a consequence of their ability to modulate tubuloglomerular feedback, SGLT2 inhibitors, like agents that block the renin-angiotensin system, reduce intraglomerular pressure and single nephron GFR, potentially affording renoprotection. To examine this further we administered the SGLT2 inhibitor, dapagliflozin, to 5/6 (subtotally) nephrectomised rats, a model of progressive chronic kidney disease (CKD) that like CKD in humans is characterised by single nephron hyperfiltration and intraglomerular hypertension and where angiotensin converting enzyme inhibitors and angiotensin receptor blockers are demonstrably beneficial. When compared with untreated rats, both sham surgery and 5/6 nephrectomised rats that had received dapagliflozin experienced substantial glycosuria. Nephrectomised rats developed hypertension, heavy proteinuria and declining GFR that was unaffected by the administration of dapagliflozin. Similarly, SGLT2 inhibition did not attenuate the extent of glomerulosclerosis, tubulointerstitial fibrosis or overexpression of the profibrotic cytokine, transforming growth factor-ß1 mRNA in the kidneys of 5/6 nephrectomised rats. While not precluding beneficial effects in the diabetic setting, these findings indicate that SGLT2 inhibition does not have renoprotective effects in this classical model of progressive non-diabetic CKD.

Mechanical stress on the glomerular filtration barrier (GFB) exposes podocytes to hydrostatic pressure. Their mechanosensitivity is established, yet the underlying mechanotransduction pathways and responses under hypertension remain unclear. This review examines the mechanical stresses experienced by podocytes in both physiologic and hypertensive conditions and updates the latest extracorporeal techniques used to simulate these forces. Additionally, this review discusses how podocytes respond to these mechanical forces and elucidates the detailed molecular mechanisms involved. Furthermore, we summarize potential protective mechanisms that enable podocytes to withstand mechanical challenges and propose novel therapeutic strategies to delay the progression of hypertensive nephropathy. This review uniquely underscores the importance of biomechanical factors in disease progression and integrates emerging therapeutic strategies targeting podocyte mechanotransduction, offering a novel biomechanical framework for delaying hypertensive nephropathy progression.

Hypertension constitutes a significant public health concern, characterized by a high incidence and mortality rate. Hypertensive kidney disease is a prevalent complication associated with hypertension and is the second leading cause of end-stage renal disease (ESRD). Renal fibrosis linked to hypertension has emerged as the third leading cause of disease in dialysis patients. Autophagy activity is crucial for maintaining homeostasis, vitality, and physiological function of kidney cells, while also protecting the kidneys from fibrosis. The deficiency of autophagy will increase the sensitivity of the kidney to the damage, leading to impaired renal function, accumulation of damaged mitochondria and more severe of renal fibrosis. However, enhancing autophagy by activating the PI3K/AKT, AMPK, and mTOR pathways, improves podocyte injury and renal pathological changes, and ameliorates renal function. Current clinical interventions aimed at halting or reversing renal fibrosis in hypertensive patients are notably limited in their efficacy. Here, we present Non-lethal Sonodynamic Therapy (NL-SDT), in which ultrasound is used to activate locally sonosensitizers, thereby stimulating the production of reactive oxygen species for the purpose of modulating cell function or fate, as a novel methodology to inhibit progression of hypertensive renal fibrosis. To confirm whether NL-SDT can reduce hypertensive renal fibrosis and its mechanism. The mice model of hypertensive renal fibrosis was established by using osmotic minipumps (Alzet model 2004, Cupertino, CA) equipped with angiotensin-II (Ang II). The pumps were implanted in mice, ensuring constant infusion of Ang II at a dose of 1.0 µg/kg per minute for 4 weeks. The mice were exposed to 0.4 W/cm 2 intensity ultrasonic radiation for 15 min at 4 h post injection of sinoporphyrin sodium (DVDMS) (4 mg/kg) into the caudal vein was repeated weekly for 4 treatments. The kidney from mice was stained with masson’s trichrome staining for collagen fiber expression, while alpha-smooth muscle actin (α-SMA) expression was determined via immunohistochemical staining. The protein levels of fibrosis parameters (α-SMA, collagen I, vimentin), pathway-related proteins (PI3K, AKT, mTORC1) and autophagy-related protein LC3B were determined using western blotting. Intracellular reactive oxygen species (ROS) levels were detected using DCFH-DA probe. Immunofluorescence was also used to observe the expression of α-SMA and E-cadherin in cells. Pathway-related protein inhibitors (the autophagy-related inhibitor 3-methyladenine (3-MA), chloroquine (CQ), ROS inhibitor N-acetyl-L-cysteine (NAC) were applied, and autophagosome changes were observed under transmission electron microscopy. Immunofluorescence was used to observe LC3 spot formation within cells. We obtained the following results via animal and cellular research. In vivo, (1) The collagen area of renal tissue was increased significantly in Ang II group (50.6%). The positive expression of α-SMA was increased significantly (37.8%). (2) The collagen area decreased after NL-SDT treatment (34.8%). The expression of α-SMA was decreased too (48.9%). The expression of LC3B increased in NL-SDT group. (3) The effect of NL-SDT on reducing renal fibrosis can be changed by rapamycin and CQ. In vitro. (1) The expression of α-SMA, collagen I and vimentin were increased significantly in TGF-β1-induced NRK-52E cells. (2) The increase of autophagosomes was observed in TGF-β1-induced NRK-52E cells after NL-SDT. The levels of ROS were increased after NL-SDT (24.8%). The effect of NL-SDT on autophagy was reversed after administration of NAC. The expression of PI3K, P-AKT and P-mTORC1 was decreased in TGF-β1-induced NRK-52E cells after NL-SDT. NL-SDT inhibited the transition of epithelial cells into myofibroblasts by activating PI3K-AKT-mTORC1-autophagy pathway in TGF-β1-induced NRK-52E cells. (3) The administration of the pathway inhibitors showed a reciprocal effect on NL-SDT-inhibited epithelial-mesenchymal transition (EMT). (1) NL-SDT reduced blood pressure temporarily in mice model of hypertensive renal fibrosis induced by Ang II. (2) NL-SDT alleviated renal fibrosis in mice model of hypertensive renal fibrosis induced by Ang II. (3) NL-SDT promoted autophagy by inhibiting PI3K-AKT-mTORC1 signaling pathway and alleviated renal fibrosis in mice model of hypertensive renal fibrosis induced by Ang II. NL-SDT is a non-invasive and efficacious regimen to inhibit renal fibrosis. It may be a new approach for clinical treatment of renal fibrosis, delaying or reducing the occurrence of ESRD.

Hypertensive nephropathy (HTN) ranks as the second-leading cause of end-stage renal disease (ESRD). Accumulating evidence suggests that persistent hypertension injures tubular cells, leading to tubulointerstitial fibrosis (TIF), which is involved in the pathogenesis of HTN. G protein-coupled receptors (GPCRs) are implicated in many important pathological and physiological processes and act as important drug targets. In this study, we explored the intrarenal mechanisms underlying hypertension-associated TIF, and particularly, the potential role of GPR97, a member of the adhesion GPCR subfamily, in TIF. A deoxycorticosterone acetate (DOCA)/salt-induced hypertensive mouse model was used. We revealed a significantly upregulated expression of GPR97 in the kidneys, especially in renal tubules, of the hypertensive mice and 10 patients with biopsy-proven hypertensive kidney injury. GPR97 −/− mice showed markedly elevated blood pressure, which was comparable to that of wild-type mice following DOCA/salt treatment, but dramatically ameliorated renal injury and TIF. In NRK-52E cells, we demonstrated that knockdown of GPR97 suppressed the activation of TGF-β signaling by disturbing small GTPase RhoA-mediated cytoskeletal reorganization, thus inhibiting clathrin-mediated endocytosis of TGF-β receptors and subsequent Smad activation. Collectively, this study demonstrates that GPR97 contributes to hypertension-associated TIF at least in part by facilitating TGF-β signaling, suggesting that GPR97 is a pivotal intrarenal factor for TIF progression under hypertensive conditions, and therapeutic strategies targeting GPR97 may improve the outcomes of patients with HTN.