The Number and Size of Individual Kidney Medullary Pyramids is Associated with Clinical Characteristics, Kidney Biopsy Findings, and CKD Outcomes among Kidney Donors.

SIGNIFICANCE STATEMENT: Segmentation of multiple structures in cross-sectional imaging is time-consuming and impractical to perform manually, especially if the end goal is clinical implementation. In this study, we developed, validated, and demonstrated the capability of a deep learning algorithm to segment individual medullary pyramids in a rapid, accurate, and reproducible manner. The results demonstrate that cortex volume, medullary volume, number of pyramids, and mean pyramid volume is associated with patient clinical characteristics and microstructural findings and provide insights into the mechanisms that may lead to CKD. BACKGROUND: The kidney is a lobulated organ, but little is known regarding the clinical importance of the number and size of individual kidney lobes. METHODS: After applying a previously validated algorithm to segment the cortex and medulla, a deep-learning algorithm was developed and validated to segment and count individual medullary pyramids on contrast-enhanced computed tomography images of living kidney donors before donation. The association of cortex volume, medullary volume, number of pyramids, and mean pyramid volume with concurrent clinical characteristics (kidney function and CKD risk factors), kidney biopsy morphology (nephron number, glomerular volume, and nephrosclerosis), and short- and long-term GFR <60 or <45 ml/min per 1.73 m 2 was assessed. RESULTS: Among 2876 living kidney donors, 1132 had short-term follow-up at a median of 3.8 months and 638 had long-term follow-up at a median of 10.0 years. Larger cortex volume was associated with younger age, male sex, larger body size, higher GFR, albuminuria, more nephrons, larger glomeruli, less nephrosclerosis, and lower risk of low GFR at follow-up. Larger pyramids were associated with older age, female sex, larger body size, higher GFR, more nephrons, larger glomerular volume, more nephrosclerosis, and higher risk of low GFR at follow-up. More pyramids were associated with younger age, male sex, greater height, no hypertension, higher GFR, lower uric acid, more nephrons, less nephrosclerosis, and a lower risk of low GFR at follow-up. CONCLUSIONS: Cortex volume and medullary pyramid volume and count reflect underlying variation in nephron number and nephron size as well as merging of pyramids because of age-related nephrosclerosis, with loss of detectable cortical columns separating pyramids.

Nephroangiosclerosis: an update / Nefroangioesclerosis: actualización

Nephroangiosclerosis or kidney disease that accompanies chronic essential arterial hypertension has been known for more than a hundred years. The definitive diagnosis is established by renal biopsy, which is reserved for doubtful cases or atypical presentation, being in most cases a presumptive clinical diagnosis. The objective of this review is to analyse the main controversies that currently exist related to nephroangiosclerosis: inaccuracy in epidemiological aspects (prevalence and incidence unknown), diagnostic difficulties and lack of correlation studies between clinical data and histopathology, progression factors in Caucasians. Currently, with advances in genetic studies in hypertension, not using or redefining the term hypertensive kidney disease for another condition such as nephropathy related to the present genetic alteration is being considered. (AU)

La nefroangioesclerosis o enfermedad renal que acompaña a la hipertensión arterial esencial crónica, es una entidad conocida desde hace más de 100 años. El diagnóstico definitivo se establece por biopsia renal, la cual se reserva para casos dudosos o presentación atípica, siendo en la mayoría de casos un diagnóstico clínico de presunción. El objetivo de esta revisión es analizar las principales controversias que existen actualmente relacionadas con la nefroangioesclerosis: inexactitud en aspectos epidemiológicos (prevalencia e incidencia real desconocida), dificultades diagnósticas y falta de estudios de correlación entre datos clínicos e histopatología, factores de progresión en raza caucásica. Actualmente con los avances en estudios genéticos en hipertensión se está planteando abandonar o redefinir el término de enfermedad renal hipertensiva por otro como nefropatía relacionada con la alteración genética presente. (AU)

Age-Based Versus Young-Adult Thresholds for Nephrosclerosis on Kidney Biopsy and Prognostic Implications for CKD.

SIGNIFICANCE STATEMENT: Nephrosclerosis (glomerulosclerosis, interstitial fibrosis, and tubular atrophy) is the defining pathology of both kidney aging and CKD. Optimal thresholds for nephrosclerosis that identify persons with a progressive disease are unknown. This study determined a young-age threshold (18-29 years) and age-based 95th percentile thresholds for nephrosclerosis on the basis of morphometry of kidney biopsy sections from normotensive living kidney donors. These thresholds were 7.1-fold to 36-fold higher in older (70 years or older) versus younger (aged 18-29 years) normotensive donors. Age-based thresholds, but not young-age threshold, were prognostic for determining risk of progressive CKD among patients who underwent a radical nephrectomy or a for-cause native kidney biopsy, suggesting that age-based thresholds are more useful than a single young-age threshold for identifying CKD on biopsy. BACKGROUND: Nephrosclerosis, defined by globally sclerotic glomeruli (GSG) and interstitial fibrosis and tubular atrophy (IFTA), is a pathology of both kidney aging and CKD. A comparison of risk of progressive CKD using aged-based thresholds for nephrosclerosis versus a single young-adult threshold is needed. METHODS: We conducted morphometric analyses of kidney biopsy images for %GSG, %IFTA, and IFTA foci density among 3020 living kidney donors, 1363 patients with kidney tumor, and 314 patients with native kidney disease. Using normotensive donors, we defined young-age thresholds (18-29 years) and age-based (roughly by decade) 95th percentile thresholds. We compared age-adjusted risk of progressive CKD (kidney failure or 40% decline in eGFR) between nephrosclerosis that was "normal compared with young," "normal for age but abnormal compared with young," and "abnormal for age" in patients with tumor and patients with kidney disease. RESULTS: The 95th percentiles in the youngest group (18-29 years) to the oldest group (70 years or older) ranged from 1.7% to 16% for %GSG, 0.18% to 6.5% for %IFTA, and 8.2 to 59.3 per cm 2 for IFTA foci density. Risk of progressive CKD did not differ between persons with nephrosclerosis "normal compared with young" versus "normal for age but abnormal compared with young." Risk of progressive CKD was significantly higher with %GSG, %IFTA, or IFTA foci density that was abnormal versus normal for age in both cohorts. CONCLUSIONS: Given that increased risk of progressive CKD occurs only when nephrosclerosis is abnormal for age, age-based thresholds for nephrosclerosis seem to be better than a single young-age threshold for identifying clinically relevant CKD.

Endothelial-derived complement factor D contributes to endothelial dysfunction in malignant nephrosclerosis via local complement activation.

Malignant nephrosclerosis is a thrombotic microangiopathy associated with abnormal local activation of the complement alternative pathway (AP). However, the mechanism underlying local AP activation is not fully understood. We hypothesized that complement factor D (CFD) secreted by endothelial cells triggers vascular dysfunction in malignant nephrosclerosis via local complement activation. We investigated the deposition of CFD in human kidney biopsy tissues and the function of endothelial-derived CFD in endothelial cell cultures. Immunofluorescence microscopy and laser microdissection-targeted mass spectrometry revealed significant deposition of CFD in the kidneys of patients with malignant nephrosclerosis. Conditionally immortalized human glomerular endothelial cells (CiGEnCs) continuously expressed and secreted CFD in vitro. CFD knockdown in CiGEnCs by small interfering RNA reduced local complement activation and attenuated the upregulation of intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), von Willebrand factor (VWF), and endothelin-1 (ET-1) induced by Ang II. The expression of CFD in CiGEnCs was significantly higher than that in other types of microvascular endothelial cells. Our findings suggest that (i) glomerular endothelial cells are an important source of local renal CFD, (ii) endothelial-derived CFD can activate the local complement system, and (iii) endothelial-derived CFD mediates endothelial dysfunction, which may play a role in the pathogenesis of malignant nephrosclerosis.

Nephroangiosclerosis: an update.

Nephroangiosclerosis or kidney disease that accompanies chronic essential arterial hypertension has been known for more than a hundred years. The definitive diagnosis is established by renal biopsy, which is reserved for doubtful cases or atypical presentation, being in most cases a presumptive clinical diagnosis. The objective of this review is to analyse the main controversies that currently exist related to nephroangiosclerosis: inaccuracy in epidemiological aspects (prevalence and incidence unknown), diagnostic difficulties and lack of correlation studies between clinical data and histopathology, progression factors in Caucasians. Currently, with advances in genetic studies in hypertension, not using or redefining the term hypertensive kidney disease for another condition such as nephropathy related to the present genetic alteration is being considered.

Adolescent-onset TAFRO Syndrome with Malignant Nephrosclerosis-like Lesions.

A 16-year-old Japanese girl developed a fever, thrombocytopenia, and renal dysfunction. Treatment was started with steroids, but cervical lymphadenopathy and ascites developed. A lymph node biopsy indicated TAFRO syndrome. The patient's renal function deteriorated, and dialysis was started. Refractory hypertension and subsequent encephalopathy developed. Treatment was started with an anti-IL-6 receptor antibody and an anti-CD20 monoclonal antibody. A kidney biopsy showed malignant nephrosclerosis-like microangiopathy and glomerular collapse due to narrowing of the small arteries. The majority of TAFRO syndrome cases are adult-onset, with glomerular microangiopathy. To our knowledge, this is the first report of adolescent-onset TAFRO syndrome presenting with malignant nephrosclerosis-like lesions associated with hypertension.

Prediction of decreased estimated glomerular filtration rate using liver fibrosis markers: a renal biopsy-based study.

Non-alcoholic fatty liver disease is the most common chronic liver disease and is associated with chronic kidney disease. The fibrosis-4 index and non-alcoholic fatty liver disease score are widely used as non-invasive diagnostic methods for non-alcoholic fatty liver disease. However, the relationship between these markers and specific renal histopathologies in chronic kidney disease remain unclear. This study included 179 patients aged between 16 and 80 years who underwent renal biopsy. We examined the association between the fibrosis-4 index or non-alcoholic fatty liver disease score and change in estimated glomerular filtration rate 12 months after kidney biopsy for each renal histopathology. Renal histopathologies were determined by renal biopsy. Our results showed that there was a significant negative correlation between the fibrosis-4 index and estimated glomerular filtration rate. In nephrosclerosis, the non-alcoholic fatty liver disease score and estimated glomerular filtration rate tended to have a negative correlation, albeit without significance. In IgA nephropathy, both the fibrosis-4 index and non-alcoholic fatty liver disease score were significantly negatively correlated with estimated glomerular filtration rate. Furthermore, the fibrosis-4 index was not associated with urinary protein-to-creatinine ratio or renal function markers such as urinary b2 microglobulin and urinary N-acetyl-D-glucosamine. Our kidney biopsy-based study showed that the liver fibrosis markers fibrosis-4 index and non-alcoholic fatty liver disease score were negatively correlated with the estimated glomerular filtration rate in nephrosclerosis and IgA nephropathy.

Comparative analysis of hypertensive nephrosclerosis in animal models of hypertension and its relevance to human pathology. Glomerulopathy.

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.

Clinicopathological discordance in biopsy-proven nephrosclerosis: a nationwide cross-sectional study of the Japan Renal Biopsy Registry (J-RBR).

BACKGROUND: Patients with nephrosclerosis display heterogenous clinical phenotypes, often leading to a clinical diagnosis discordant with pathological nephrosclerosis diagnosis. However, little is known about clinical factors associated with clinicopathological discordance of biopsy-proven nephrosclerosis. METHODS: In a cross-sectional study of 891 patients with biopsy-proven nephrosclerosis registered in the Japan Renal Biopsy Registry (J-RBR) between July 2007 and June 2016, we examined clinical characteristics associated with a pre-biopsy clinical diagnosis discordant with pathological nephrosclerosis diagnosis using multivariable logistic regression with adjustment for relevant clinical characteristics. RESULTS: Overall, the mean (SD) age was 58.6 (13.7) years; 67.6% of patients were male; and 63.2% were on antihypertensive drugs. The median estimated glomerular filtration rate (eGFR) was 43.8 mL/min/1.73 m2 and the median proteinuria was 0.5 g/day. Of the 891 patients, 497 (55.8%) had a clinical diagnosis discordant with pathological nephrosclerosis diagnosis, with chronic nephritic syndrome being the most common (> 75%) discordant clinical diagnosis. After multivariable adjustment, age (odds ratio 1.34, [95% confidence interval, 1.16-1.55], per 10 years increase), eGFR (1.10 [1.00-1.21], per 10 mL/min/1.73 m2 increase), and proteinuria (1.20 [1.03-2.16], per 1 g/day decrease) were found to be significantly associated with the clinicopathological discordance. CONCLUSIONS: Patients with older age, higher eGFR, and lower proteinuria had significantly higher likelihood of being clinically diagnosed with other glomerular disease in patients with biopsy-proven nephrosclerosis. Our findings highlight the heterogeneous clinical phenotypes of nephrosclerosis and suggest the need for continuous improvement of clinical diagnostic accuracy as well as for wider kidney biopsy indications for nephrosclerosis.

Vascular, cardiac, and renal lesions attributed to primary systemic hypertension in western pygmy marmosets (Cebuella pygmaea).

In a retrospective study of a western pygmy marmoset (Cebuella pygmaea) colony, postmortem examination of 1/8 juvenile and 29/47 adult animals identified vascular, cardiac, and renal lesions consistent with systemic hypertension. This included frequent renal arteriolar hypertrophy, hyaline and proliferative arteriolosclerosis, fibrinoid necrosis of arterioles, glomerulosclerosis, and nephrosclerosis. Affected animals ranged from 0.6 to 12 years of age (mean 6 years) and had an observed male predominance. Genealogical relatedness was evident in several breeding pairs and spanned multiple generations. Concurrent cardiac and renal disease was commonly identified, although frequently subclinical, and both were important causes of morbidity and mortality in affected animals. Cardiomegaly and hypertrophy were typical features and were accompanied by left atrial thrombosis in 10 animals. Signs of heart failure included chronic pulmonary edema in 20 cases and body cavity effusions in 17. In the kidneys, 19 cases had glomerular disease and hypertensive vasculopathy, and 26 cases had nephrosclerosis or glomerulosclerosis. Common extrarenal secondary causes of hypertension were excluded by necropsy examination. The pathogenesis is suggested to involve primary hypertension leading to renal and cardiac disease. Elevated sympathetic activity might be an underlying factor in the frequent development of primary systemic hypertension in the pygmy marmoset, as for the owl monkey.

Aging-Related Kidney Diseases.

Clinical Background: Older age has been associated with higher prevalence and progression of chronic kidney disease (CKD). The presence of CKD leads to an increased risk of end-stage renal disease, cardiovascular diseases, and death. Epidemiology: Progressive aging of the population is accompanied by an increase in the prevalence of CKD worldwide. The high prevalence of CKD in the aged population would result in a considerably greater social burden. Challenges: Structural and functional changes are often observed in the aged kidney. The main pathological feature of the aged kidney is nephrosclerosis such as arteriosclerosis, glomerulosclerosis, tubular atrophy, and interstitial fibrosis. As a consequence of renal aging, the nephron number decreases. A lower nephron number approximately parallels with the decline in glomerular filtration rate (GFR), and GFR declines with aging. Recent studies have highlighted several pathological mechanisms involved in renal aging, that can serve as targets for intervention. Decreased renal oxygen levels, mitochondrial dysfunction, and inflammation drive renal fibrosis, one of the hallmarks of renal aging. Prevention and Treatment: Novel therapeutic approaches that target these functional changes are now being developed to prevent an aging-associated inevitable loss of renal function. For example, calorie restriction, Sirtuin 1 activator and peroxisome proliferator-activated receptor-γ agonists have the potential to ameliorate renal deterioration. This chapter provides an overview of the aged kidney and summarizes the current knowledge on therapeutic strategies to attenuate renal aging.

Effect of Shenkang on renal fibrosis and activation of renal interstitial fibroblasts through the JAK2/STAT3 pathway.

BACKGROUND: Activation of renal fibroblasts is a critical mechanism in the process of renal fibrosis. As a commonly used herbal formula, Shenkang (SK) has been found to attenuate renal fibrosis and renal parenchyma destruction. However, the effect of SK on renal fibroblast activation in unilateral ureteral obstruction (UUO) mice and its molecular mechanism remain undetermined. The present study was performed to elucidate the effect of SK on renal fibroblast activation and renal fibrosis, as well as the potential underlying mechanism, in both NRK-49F cells and UUO mice. METHODS: NRK-49F cells were stimulated with 10 ng/ml TGF-ß1 for 48 h. After SK treatment, the CCK-8 method was used to evaluate cell viability. Thirty-six C57BL/6 mice were randomly divided into the sham group, UUO group, angiotensin receptor blocker (ARB) group, and SK high-, moderate- and low-dose groups. UUO was induced in mice except those in the sham group. Drugs were administered 1 day later. On the 13th day, the fractional anisotropy (FA) value was determined by MRI to evaluate the degree of renal fibrosis. After 14 days, serum indexes were assessed. Hematoxylin and eosin (HE) and Sirius red staining were used to observe pathological morphology and the degree of fibrosis of the affected kidney. Western blotting and PCR were used to assess the expression of related molecules in both cells and animals at the protein and gene levels. RESULTS: Our results showed that SK reduced extracellular matrix (ECM) and α-smooth muscle actin (α-SMA) expression both in vitro and in vivo and attenuated renal fibrosis and the pathological lesion degree after UUO, suppressing JAK2/STAT3 activation. Furthermore, we found that SK regulated the JAK2/STAT3 pathway regulators peroxiredoxin 5 (Prdx5) in vitro and suppressor of cytokine signaling protein 1 (SOCS1) and SOCS3 in vivo. CONCLUSIONS: These results indicated that SK inhibited fibroblast activation by regulating the JAK2/STAT3 pathway, which may be a mechanism underlying its protective action in renal fibrosis.

New Mexico's COVID-19 Experience.

ABSTRACT: The 2019 novel coronavirus disease (COVID-19) has spread worldwide, infiltrating, infecting, and devastating communities in all locations of varying demographics. An overwhelming majority of published literature on the pathologic findings associated with COVID-19 is either from living clinical cohorts or from autopsy findings of those who died in a medical care setting, which can confound pure disease pathology. A relatively low initial infection rate paired with a high biosafety level enabled the New Mexico Office of the Medical Investigator to conduct full autopsy examinations on suspected COVID-19-related deaths. Full autopsy examination on the first 20 severe acute respiratory syndrome coronavirus 2-positive decedents revealed that some extent of diffuse alveolar damage in every death due to COVID-19 played some role. The average decedent was middle-aged, male, American Indian, and overweight with comorbidities that included diabetes, ethanolism, and atherosclerotic and/or hypertensive cardiovascular disease. Macroscopic thrombotic events were seen in 35% of cases consisting of pulmonary thromboemboli and coronary artery thrombi. In 2 cases, severe bacterial coinfections were seen in the lungs. Those determined to die with but not of severe acute respiratory syndrome coronavirus 2 infection had unremarkable lung findings.

Hypertensive nephrosclerosis: wider kidney biopsy indications may be needed to improve diagnostics.

BACKGROUND: Hypertensive nephrosclerosis is the presumed underlying cause in many end-stage kidney disease (ESKD) patients, but the diagnosis is disputed and based on clinical criteria with low diagnostic accuracy. OBJECTIVE: To evaluate and improve the diagnostic process for nephrosclerosis patients. METHODS: We included adults from the population-based HUNT study (n = 50 552), Norwegian CKD patients referred for kidney biopsy 1988-2012 (n = 7261), and unselected nephrology clinic patients (n = 193) used for matching. Decision tree analysis and ROC curve-based methods of optimal cut-offs were used to improve clinical nephrosclerosis criteria. RESULTS: Nephrosclerosis prevalence was 2.7% in the general population, and eGFR decline and risk for kidney-related hospital admissions and ESKD were comparable to patients with diabetic kidney disease. In the biopsy cohort, current clinical criteria had very low sensitivity (0.13) but high specificity (0.94) for biopsy-verified arterionephrosclerosis. A new optimized diagnostic algorithm based on proteinuria (<0.75 g d-1 ), systolic blood pressure (>155 mm Hg) and age (>75 years) only marginally improved diagnostic accuracy (sensitivity 0.19, specificity 0.96). Likewise, there were still false-positive cases with treatable diagnoses like glomerulonephritis, interstitial nephritis and others (40% of all test positive). Decision curve analysis showed that the new criteria can lead to higher clinical utility, especially for patients considering the potential harms to be close to the potential benefits, while the more risk-tolerant ones (harm:benefit ratio < 1:4) should consider kidney biopsy. CONCLUSION: Further improvements of the current clinical criteria seem difficult, so risks and benefits of kidney biopsy could be more actively discussed with selected patients to reduce misclassification and direct treatment.

Larger Nephron Size and Nephrosclerosis Predict Progressive CKD and Mortality after Radical Nephrectomy for Tumor and Independent of Kidney Function.

BACKGROUND: Nephron hypertrophy and nephrosclerosis may be important determinants of CKD and mortality. However, studies of outcomes associated with these microstructural features have been limited to small tissue specimens from patients selected for either good kidney health or known kidney disease. METHODS: To determine whether microstructural features are predictive of progressive CKD and mortality outcomes, we studied patients who underwent a radical nephrectomy for a tumor. Large wedge sections of renal parenchyma distal to the tumor were stained and scanned into high-resolution images; we annotated the cortex and all glomeruli to calculate glomerular volume, cortex volume per glomerulus, and percentage of globally sclerotic glomeruli. Morphometric measurements also included percentages of artery luminal stenosis and interstitial fibrosis/tubular atrophy (IF/TA) of the cortex. At follow-up visits every 6-12 months, we determined which patients experienced progressive CKD (defined as dialysis, kidney transplantation, or a 40% decline from postnephrectomy eGFR). Cox models for these outcomes were adjusted for age, sex, body mass index, hypertension, diabetes, smoking, eGFR, and proteinuria. RESULTS: Among 936 patients (mean age, 64 years; postnephrectomy baseline eGFR, 48 ml/min per 1.73 m2), 117 progressive CKD events, 183 noncancer deaths, and 116 cancer deaths occurred during a median follow-up of 6.4 years. Larger glomerular volume, larger cortex per glomerulus, and higher percentage of globally sclerotic glomeruli or IF/TA predicted progressive CKD. Higher percentage IF/TA also predicted noncancer mortality. Microstructural features did not predict cancer mortality or recurrence. CONCLUSIONS: After a radical nephrectomy, larger nephrons and nephrosclerosis predicted progressive CKD, and IF/TA predicted noncancer mortality. Morphometric analysis of renal parenchyma can predict noncancer clinical events in patients long after their radical nephrectomy.

MiR-185-5p ameliorates endoplasmic reticulum stress and renal fibrosis by downregulation of ATF6.

Endoplasmic reticulum (ER) stress is considered an important factor in the formation of fibrosis. Therefore, modulation of ER stress may represent a promising therapeutic strategy in renal fibrosis. MiR-185-5p has been identified to be implicated in TGF-ß1-induced renal fibrosis; however, it is largely unknown whether and how miR-185-5p regulates ER stress in renal fibrosis. In this study, we demonstrated that miR-185-5p directly bound to ATF6, an ER stress-related protein, and downregulated the expression thereof. We subsequently constructed an in vitro model of renal fibrosis using HK2 cells treated with TGF-ß1, and found that miR-185-5p attenuated ER stress and dedifferentiation of tubular epithelia by suppression of ATF6. In addition, we constructed an in vivo mouse model using unilateral urethral obstruction (UUO). Our in vivo findings showed that miR-185-5p reduced the expression of ER stress-related proteins and inhibited epithelial dedifferentiation via downregulation of ATF6, thereby improving UUO-induced renal fibrosis. Overall, our findings revealed that miR-185-5p exerts beneficial effects in renal fibrosis. Thus, the miR-185-5p/ATF6 regulatory pathway may be a potential target for therapeutic intervention in renal fibrosis.

Endogenous miR-204 Protects the Kidney against Chronic Injury in Hypertension and Diabetes.

BACKGROUND: Aberrant microRNA (miRNA) expression affects biologic processes and downstream genes that are crucial to CKD initiation or progression. The miRNA miR-204-5p is highly expressed in the kidney but whether miR-204-5p plays any role in the development of chronic renal injury is unknown. METHODS: We used real-time PCR to determine levels of miR-204 in human kidney biopsies and animal models. We generated Mir204 knockout mice and used locked nucleic acid-modified anti-miR to knock down miR-204-5p in mice and rats. We used a number of physiologic, histologic, and molecular techniques to analyze the potential role of miR-204-5p in three models of renal injury. RESULTS: Kidneys of patients with hypertension, hypertensive nephrosclerosis, or diabetic nephropathy exhibited a significant decrease in miR-204-5p compared with controls. Dahl salt-sensitive rats displayed lower levels of renal miR-204-5p compared with partially protected congenic SS.13BN26 rats. Administering anti-miR-204-5p to SS.13BN26 rats exacerbated interlobular artery thickening and renal interstitial fibrosis. In a mouse model of hypertensive renal injury induced by uninephrectomy, angiotensin II, and a high-salt diet, Mir204 gene knockout significantly exacerbated albuminuria, renal interstitial fibrosis, and interlobular artery thickening, despite attenuation of hypertension. In diabetic db/db mice, administering anti-miR-204-5p exacerbated albuminuria and cortical fibrosis without influencing blood glucose levels. In all three models, inhibiting miR-204-5p or deleting Mir204 led to upregulation of protein tyrosine phosphatase SHP2, a target gene of miR-204-5p, and increased phosphorylation of signal transducer and activator of transcription 3, or STAT3, which is an injury-promoting effector of SHP2. CONCLUSIONS: These findings indicate that the highly expressed miR-204-5p plays a prominent role in safeguarding the kidneys against common causes of chronic renal injury.

The Importance of Nephropathology in Kidney Cancer.

As early detection and advances in the treatment for renal cell carcinoma continue to lead to excellent oncologic outcomes, the preservation of renal function in kidney cancer patients has emerged as an increasingly important clinical objective. Given that diabetes, hypertension, obesity, cigarette smoking, and aging are independent risk factors for renal cell carcinoma, the corresponding non-neoplastic kidney diseases frequently are present, but often undiagnosed. In addition, the subsequent clinical management of the ensuing chronic kidney disease historically has not included nephrologists. Awareness of these practice gaps remain low among nephrologists, surgeons, and pathologists. This article discusses the common non-neoplastic kidney diseases that are encountered in cancer nephrectomy specimens. The accurate and timely diagnosis of these disorders will result in additional gains in clinical outcomes. There is a unique opportunity for the nephrology community to play a central role in the management of chronic kidney disease that often is present in kidney cancer patients.

Progressive Nephron Loss in Aging Kidneys: Clinical-Structural Associations Investigated by Two Anatomical Methods.

Two major studies of structural changes associated with aging in human kidneys are reviewed and new information presented. The studies are the Monash University stereologically analyzed series of 319 autopsy kidneys from the United States in which 44% were white and the Mayo Clinic CT angiogram/biopsy analysis of 1,388 US kidney donors in which 97% were white. Hypertension rates in the Monash series were 48% and included moderate and severe hypertension. In the Mayo Clinic study, 12% had mild hypertension. The studies showed no relationship between glomerular number and hypertension except for a weak relationship with older white women in the Monash series. An inverse relationship was present between glomerular number and glomerular volume, a reciprocity that tended to enhance glomerular mass and by inference filtration capacity with lower nephron numbers. This relationship seemed to be present whether low nephron numbers were intrinsic or acquired. In the Mayo Clinic studies, pretransplant iothalamate clearances demonstrated that single nephron (SN) glomerular filtration rates (GFR) were similar throughout the range of glomerular number in subjects younger than 70 years, but that increased SNGFR correlated with nephron hypertrophy and increased nephrosclerosis particularly at 70 years of age and over. Hypertension at least through middle age cannot be related to a deficiency of glomeruli, but glomeruli are lost with later aging in association with adaptive nephron hypertrophy that can maintain GFR near normal. These studies help define an age-related nephropathy that overlaps with hypertension as a potential cause of end-stage renal disease when glomerulosclerosis is advanced.