Application of visual transformer in renal image analysis.

Deep Self-Attention Network (Transformer) is an encoder-decoder architectural model that excels in establishing long-distance dependencies and is first applied in natural language processing. Due to its complementary nature with the inductive bias of convolutional neural network (CNN), Transformer has been gradually applied to medical image processing, including kidney image processing. It has become a hot research topic in recent years. To further explore new ideas and directions in the field of renal image processing, this paper outlines the characteristics of the Transformer network model and summarizes the application of the Transformer-based model in renal image segmentation, classification, detection, electronic medical records, and decision-making systems, and compared with CNN-based renal image processing algorithm, analyzing the advantages and disadvantages of this technique in renal image processing. In addition, this paper gives an outlook on the development trend of Transformer in renal image processing, which provides a valuable reference for a lot of renal image analysis.

Single-cell RNA sequencing for the study of kidney disease.

The kidney is an important organ for maintaining normal metabolism and stabilising the internal environment, in which, the heterogeneity of cell types has hindered the progress in understanding the mechanisms underlying kidney disease. In recent years the application of single-cell RNA sequencing (scRNA-seq) in nephrology has developed rapidly. In this review, we summarized the technical platform related to scRNA-seq and the role of this technology in investigating the onset and development of kidney diseases, starting from several common kidney diseases (mainly including lupus nephritis, renal cell carcinoma, diabetic nephropathy and acute kidney injury), and provide a reference for the application of scRNA-seq in the study of kidney disease diagnosis, treatment and prognosis.

The role of N-methyladenosine modification in acute and chronic kidney diseases.

N6-methyladenosine (m6A) modification is a kind of RNA modification in which methylation occurs at the sixth N position in adenosine in RNA, which can occur in various RNAs such as mRNAs, lncRNAs and miRNAs. This is one of the most prominent and frequent posttranscriptional modifications within organisms and has been shown to function dynamically and reversibly in a variety of ways, including splicing, export, attenuation and translation initiation efficiency to regulate RNA expression. There are three main enzymes associated with m6A modification: writers, readers and erasers. Increasing evidence has shown that m6A modification is associated with the onset and development of kidney disease. In this article, we address the important physiological and pathological roles of m6A modification in kidney diseases (uremia, ischemia-reperfusion kidney injury, drug-induced kidney injury, and diabetic nephropathy) and its molecular mechanisms to provide reference for the diagnosis and clinical management of kidney diseases.

Fibroblast growth factor 21 attenuates salt-sensitive hypertension-induced nephropathy through anti-inflammation and anti-oxidation mechanism.

BACKGROUND: Patients with salt-sensitive hypertension are often accompanied with severe renal damage and accelerate to end-stage renal disease, which currently lacks effective treatment. Fibroblast growth factor 21 (FGF21) has been shown to suppress nephropathy in both type 1 and type 2 diabetes mice. Here, we aimed to investigate the therapeutic effect of FGF21 in salt-sensitive hypertension-induced nephropathy. METHODS: Changes of FGF21 expression in deoxycorticosterone acetate (DOCA)-salt-induced hypertensive mice were detected. The influence of FGF21 knockout in mice on DOCA-salt-induced nephropathy were determined. Recombinant human FGF21 (rhFGF21) was intraperitoneally injected into DOCA-salt-induced nephropathy mice, and then the inflammatory factors, oxidative stress levels and kidney injury-related indicators were observed. In vitro, human renal tubular epithelial cells (HK-2) were challenged by palmitate acid (PA) with or without FGF21, and then changes in inflammation and oxidative stress indicators were tested. RESULTS: We observed significant elevation in circulating levels and renal expression of FGF21 in DOCA-salt-induced hypertensive mice. We found that deletion of FGF21 in mice aggravated DOCA-salt-induced nephropathy. Supplementation with rhFGF21 reversed DOCA-salt-induced kidney injury. Mechanically, rhFGF21 induced AMPK activation in DOCA-salt-treated mice and PA-stimulated HK-2 cells, which inhibited NF-κB-regulated inflammation and Nrf2-mediated oxidative stress and thus, is important for rhFGF21 protection against DOCA-salt-induced nephropathy. CONCLUSION: These findings indicated that rhFGF21 could be a promising pharmacological strategy for the treatment of salt-sensitive hypertension-induced nephropathy.

CircNr1h4 regulates the pathological process of renal injury in salt-sensitive hypertensive mice by targeting miR-155-5p.

Circular RNAs are a class of widespread and diverse endogenous RNAs that may regulate gene expression in various diseases, but their regulation and function in hypertensive renal injury remain unclear. In this study, we generated ribosomal-depleted RNA sequencing data from normal mouse kidneys and from injured mouse kidneys induced by deoxycorticosterone acetate-salt hypertension and identified at least 4900 circRNA candidates. A total of 124 of these circRNAs were differentially expressed between the normal and injured kidneys. Furthermore, we characterized one abundant circRNA, termed circNr1h4, which is derived from the Nr1h4 gene and significantly down-regulated in the injured kidneys. RNA sequencing data and qPCR analysis also showed many microRNAs and mRNAs, including miR-155-5p and fatty acid reductase 1 (Far1), were differentially expressed between the normal and injured kidney and related to circNr1h4. In vitro, the silencing of circNr1h4 or overexpression of miR-155-5p significantly decreased Far1 levels and increased reactive oxygen species. Mechanistic investigations indicated that circNr1h4 acts as a competing endogenous RNA for miR-155-5p, leading to regulation of its target gene Far1. Our study provides novel insight into the molecular mechanisms underlying kidney injury in hypertension, which will be required to develop therapeutic strategies of targeting circRNAs for hypertensive kidney injury.

Homocysteine aggravates DNA damage by impairing the FA/Brca1 Pathway in NE4C murine neural stem cells.

There is existing evidence that elevated homocysteine (Hcy) levels are risk factors for some neurodegenerative disorders. The pathogenesis of neurological diseases could be contributed to excessive cell dysfunction and death caused by defective DNA damage response (DDR) and accumulated DNA damage. Hcy is a neurotoxic amino acid and acts as a DNA damage inducer. However, it is not clear whether Hcy participates in the DDR. To investigate the effects of Hcy on DNA damage and the DDR, we employed mitomycin C (MMC) to cause DNA damage in NE4C murine neural stem cells (NSCs). Compared to treatment with MMC alone, we found that co-treatment with MMC and Hcy worsened DNA damage and increased death in NE4C cells. Intriguingly, in this DNA damage model mimicked by MMC, immunoblotting results showed that the monoubiquitination levels of Fanconi anemia complementation group I (Fanci) and Fanconi anemia complementation group D2 (Fancd2) were decreased to about 60.3% and 55.7% by supplementing cell culture medium with Hcy, indicating Hcy inactivates the function of Fanci and Fancd2 in DNA damage conditions. Given Breast Cancer 1 (BRCA1) is an important downstream of FANCD2, we next detected the interaction between Fancd2 and Brca1 in NE4C cells. Compared to treatment with MMC alone, the Fancd2-Brca1 interaction and the amount of Brca1 on chromatin were decreased when cells were co-exposed to MMC and Hcy, suggesting Hcy could impair the Fanconi anemia (FA)/Brca1 pathway. Taken together, our study demonstrates that Hcy may enhance cell death, which contributes to the accumulation of DNA damage and promotion of hypersensitivity to cytotoxicity by impairing the FA/Brca1 pathway in murine NSCs in the presence of DNA damage.

Pex11a deficiency causes dyslipidaemia and obesity in mice.

Peroxisomes play a central role in lipid metabolism. We previously demonstrated that Pex11a deficiency impairs peroxisome abundance and fatty acid ß-oxidation and results in hepatic triglyceride accumulation. The role of Pex11a in dyslipidaemia and obesity is investigated here with Pex11a knockout mice (Pex11a-/- ). Metabolic phenotypes including tissue weight, glucose tolerance, insulin sensitivity, cholesterol levels, fatty acid profile, oxygen consumption, physical activity were assessed in wild-type (WT) and Pex11a-/- fed with a high-fat diet. Molecular changes and peroxisome abundance in adipose tissue were evaluated through qRT-PCR, Western blotting, and Immunofluorescence. Pex11a-/- showed increased fat mass, decreased skeletal muscle, higher cholesterol levels, and more severely impaired glucose and insulin tolerance. Pex11a-/- consumed less oxygen, indicating a decrease in fatty acid oxidation, which is consistent with the accumulation of very long- and long-chain fatty acids. Adipose palmitic acid (C16:0) levels were elevated in Pex11a-/- , which may be because of dramatically increased fatty acid synthase mRNA and protein levels. Furthermore, Pex11a deficiency increased ventricle size and macrophage infiltration, which are related to the reduced physical activity. These data demonstrate that Pex11a deficiency impairs physical activity and energy expenditure, decreases fatty acid ß-oxidation, increases de novo lipogenesis and results in dyslipidaemia and obesity.

Pex11α deficiency impairs peroxisome elongation and division and contributes to nonalcoholic fatty liver in mice.

Hepatic triglyceride (TG) accumulation is considered to be a prerequisite for developing nonalcoholic fatty liver (NAFL). Peroxisomes have many important functions in lipid metabolism, including fatty acid ß-oxidization. However, the pathogenic link between NAFL and peroxisome biogenesis remains unclear. To examine the molecular and physiological functions of the Pex11α gene, we disrupted this gene in mice. Body weights and hepatic TG concentrations in Pex11α(-/-) mice were significantly higher than those in wild-type (WT) mice fed a normal or a high-fat diet. Hepatic TG concentrations in fasted Pex11α(-/-) mice were significantly higher than those in fasted WT mice. Plasma TG levels increased at lower rates in Pex11α(-/-) mice than in WT mice after treatment with the lipoprotein lipase inhibitor tyloxapol. The number of peroxisomes was lower in the livers of Pex11α(-/-) mice than in those of WT mice. Ultrastructural analysis showed that small and regular spherically shaped peroxisomes were more prevalent in Pex11α(-/-) mice fed normal chow supplemented without or with fenofibrate. We observed a significantly higher ratio of empty peroxisomes containing only PMP70, a peroxisome membrane protein, but not catalase, a peroxisome matrix protein, in Pex11α(-/-) mice. The mRNA expression levels of peroxisomal fatty acid oxidation-related genes (ATP-binding cassette, subfamily D, member 2, and acyl-CoA thioesterase 3) were significantly higher in WT mice than those in Pex11α(-/-) mice under fed conditions. Our results demonstrate that Pex11α deficiency impairs peroxisome elongation and abundance and peroxisomal fatty acid oxidation, which contributes to increased lipid accumulation in the liver.

MicroRNA 210 as a biomarker for congestive heart failure.

MicroRNAs (miRNAs) are endogenous small RNAs that are 18-23 nucleotides long. Recently, plasma miRNAs were reported to be sensitive and specific biomarkers of various pathological conditions. In the present study, we focused on miR-210, which is known to be induced by hypoxia and might therefore be an excellent biomarker for congestive heart failure. Plasma miR-210 levels and expression levels in mononuclear cells and skeletal muscles were elevated in Dahl salt-sensitive rats with heart failure. We also assessed miR-210 expression in patients with heart failure. The miR-210 expression levels in the mononuclear cells of patients with NYHA III and IV heart failure according to the New York Heart Association (NYHA) functional classification system were significantly higher than those with NYHA II heart failure and controls. Although no significant correlation was observed between plasma brain natriuretic peptide (BNP) and plasma miR-210 levels in patients with NYHA II heart failure, patients with an improved BNP profile at the subsequent hospital visit were classified in a subgroup of patients with low plasma miR-210 levels. Plasma miR-210 levels may reflect a mismatch between the pump function of the heart and oxygen demand in the peripheral tissues, and be a new biomarker for chronic heart failure in addition to plasma BNP concentrations.

DNA hypermethylation-induced miR-182 silence targets BCL2 and HOXA9 to facilitate the self-renewal of leukemia stem cell, accelerate acute myeloid leukemia progression, and determine the sensitivity of BCL2 inhibitor venetoclax.

Rationale: microRNAs (miRNAs) are frequently deregulated and play important roles in the pathogenesis and progression of acute myeloid leukemia (AML). miR-182 functions as an onco-miRNA or tumor suppressor miRNA in the context of different cancers. However, whether miR-182 affects the self-renewal of leukemia stem cells (LSCs) and normal hematopoietic stem progenitor cells (HSPCs) is unknown. Methods: Bisulfite sequencing was used to analyze the methylation status at pri-miR-182 promoter. Lineage-negative HSPCs were isolated from miR-182 knockout (182KO) and wild-type (182WT) mice to construct MLL-AF9-transformed AML model. The effects of miR-182 depletion on the overall survival and function of LSC were analyzed in this mouse model in vivo. Results: miR-182-5p (miR-182) expression was lower in AML blasts than normal controls (NCs) with hypermethylation observed at putative pri-miR-182 promoter in AML blasts but unmethylation in NCs. Overexpression of miR-182 inhibited proliferation, reduced colony formation, and induced apoptosis in leukemic cells. In addition, depletion of miR-182 accelerated the development and shortened the overall survival (OS) in MLL-AF9-transformed murine AML through increasing LSC frequency and self-renewal ability. Consistently, overexpression of miR-182 attenuated AML development and extended the OS in the murine AML model. Most importantly, miR-182 was likely dispensable for normal hematopoiesis. Mechanistically, we identified BCL2 and HOXA9 as two key targets of miR-182 in this context. Most importantly, AML patients with miR-182 unmethylation had high expression of miR-182 followed by low protein expression of BCL2 and resistance to BCL2 inhibitor venetoclax (Ven) in vitro. Conclusions: Our results suggest that miR-182 is a potential therapeutic target for AML patients through attenuating the self-renewal of LSC but not HSPC. miR-182 promoter methylation could determine the sensitivity of Ven treatment and provide a potential biomarker for it.

P2X7 deficiency attenuates hypertension and renal injury in deoxycorticosterone acetate-salt hypertension.

The P2X(7) receptor is a ligand-gated ion channel, and genetic variations in the P2X(7) gene significantly affect blood pressure. P2X(7) receptor expression is associated with renal injury and inflammatory diseases. Uninephrectomized wild-type (WT) and P2X(7)-deficient (P2X(7) KO) mice were subcutaneously implanted with deoxycorticosterone acetate (DOCA) pellets and fed an 8% salt diet for 18 days. Their blood pressure was assessed by a telemetry system. The mice were placed in metabolic cages, and urine was collected for 24 h to assess renal function. After 18 days of DOCA-salt treatment, P2X(7) mRNA and protein expression increased in WT mice. Blood pressure in P2X(7) KO mice was less than that of WT mice (mean systolic blood pressure 133 ± 3 vs. 150 ± 2 mmHg). On day 18, urinary albumin excretion was lower in P2X(7) KO mice than in WT mice (0.11 ± 0.07 vs. 0.28 ± 0.07 mg/day). Creatinine clearance was higher in P2X(7) KO mice than in WT mice (551.53 ± 65.23 vs. 390.85 ± 32.81 µl·min(-1)·g renal weight(-1)). Moreover, renal interstitial fibrosis and infiltration of immune cells (macrophages, T cells, B cells, and leukocytes) were markedly attenuated in P2X(7) KO mice compared with WT mice. The levels of IL-1ß, released by macrophages, in P2X(7) KO mice had decreased dramatically compared with that in WT mice. These results strongly suggest that the P2X(7) receptor plays a key role in the development of hypertension and renal disease via increased inflammation, indicating its potential as a novel therapeutic target.

Islet transplantation ameliorates diabetes-induced testicular interstitial fibrosis and is associated with inhibition of TGF-ß1/Smad2 pathway in a rat model of type 1 diabetes.

Islet transplantation (IT) is considered the most effective endocrine replacement therapy for diabetes mellitus (DM). Studies have demonstrated that IT can repair testicular structural injury caused by inflammatory and oxidative stress in a diabetic rat model. However, highly effective exogenous antioxidant and anti-inflammatory drugs can achieve this effect. Testicular interstitial fibrosis caused by long-term hyperglycemia is however difficult to reverse or recover. Thus far, there are no effective drugs that prevent or relieve testicular interstitial fibrosis. Therefore, it is necessary to explore the potential benefit of IT on testicular interstitial fibrosis induced by DM and its underlying molecular mechanisms. In the present study, Wistar rats were used to establish a DM model by intraperitoneal injection of streptozotocin. The diabetic models then underwent IT or received insulin treatment after 12 weeks. IT was more effective than insulin treatment in ameliorating diabetic-induced testicular interstitial fibrosis, Leydig cells apoptosis, testosterone deficiency and poor sperm motility. IT and insulin treatment both significantly inhibited the upregulation of TGF-ß1 and phosphorylated Smad2 in DM, with IT being more effective than insulin. The present study's findings proved that IT effectively protects diabetic-induced testicular interstitial fibrosis probably by inhibiting the TGF-ß1/Smad2 signaling pathway, which offers hope in male patients with DM complicating with testicular interstitial fibrosis.

Effects of alcohol-drinking behaviour and ADH1B and ALDH2 polymorphisms on basal DNA damage in human mononuclear cells as determined by the comet assay.

The aim of this study was to investigate the effects of alcohol drinking and ADH1B and ALDH2 polymorphisms on basal DNA damage (measured by the alkaline comet assay) of mononuclear cells in 122 healthy Japanese workers. Our results showed that drinking frequency had a significant impact on the tail moment (TM) value, with the highest TM value observed in habitual drinkers. The presence of the ADH1B*2 or ALDH2*2 allele was associated with increased DNA damage in older habitual drinkers. Furthermore, habitual drinkers with a combined genotype of ADH1B*2/*2 and ALDH2*1/*2 demonstrated a significantly higher TM value than other groups. Moreover, the combination of drinking and smoking has a combined effect on DNA damage. Multiple regression analysis revealed that drinking frequency, smoking status, and ALDH2 polymorphisms significantly influence basal TM value, suggesting that these are important variables affecting individual basal DNA damage.

Low-Dose Vitamin D Protects Hyperoxia-Induced Bronchopulmonary Dysplasia by Inhibiting Neutrophil Extracellular Traps.

Background and Objective: As bronchopulmonary dysplasia (BPD) can lead to considerable mortality and morbidity, this disease is the focus of attention in neonatology. Vitamin D (VD), which has anti-inflammatory properties and promotes lung growth, may have a therapeutic effect on BPD. The overexpression of neutrophil extracellular traps (NETs) has been demonstrated to be involved in the pathogenesis of BPD in our previous study. This study aimed to elucidate the effect of VD on BPD and the role of NETs in this process. Methods: Newborn rats were exposed to 90% oxygen continuously for 7 days to mimic BPD, and rats under hyperoxia were injected with 1,25(OH)2D3 at different doses (0.5 ng/g, 3 ng/g). Alveolarization, pulmonary vascular development, inflammatory cytokines and NETs were assessed. Results: Hyperoxia increased mortality, decreased body weight, impaired alveolarization with a decrease in radial alveolar count (RAC) and an increase in mean linear intercept (MLI), and impaired vascular development with low vascular endothelial growth factor (VEGF) expression. Meanwhile, hyperoxia enhanced expression of the proinflammatory factors TNF-α, IL-1ß, and IL-6, and elevated NETs in lung tissues and plasma. Low-dose VD (0.5 ng/g) administration increased the survival rate, attenuated developmental retardation, improved alveolarization, and pulmonary vascular development in hyperoxia-induced BPD, and reduced the expression of proinflammatory factors and NETs. However, high-dose VD (3 ng/g) treatment did not attenuate lung injury or NETs significantly, and even led to more severe developmental retardation and a higher mortality rate. Conclusions: Low-dose VD increased the survival rate, attenuated developmental retardation, and improved alveolarization and pulmonary vascularization arrest in hyperoxia-induced BPD partially by inhibiting NETs.

Effects of lifestyle on micronuclei frequency in human lymphocytes in Japanese hard-metal workers.

OBJECTIVE: The risks of cardiovascular disease, cancer, and other major causes of mortality are largely attributable to lifestyle factors such as smoking, alcohol drinking, hours of working and sleeping, physical activity, diet, and stress. Earlier studies have suggested that an unhealthy lifestyle is also associated with increased lymphocyte sensitivity to mutagens, oxidative DNA damage level, and leukocyte DNA damage. In order to explore the genotoxicity of unhealthy lifestyle, we evaluated the effect of overall lifestyle as well as some individual lifestyle factors on micronuclei (MN) frequency in cultured human lymphocytes. METHOD: The study was conducted among 208 healthy adult (19 to 59 years) male Japanese hard-metal workers. The subjects were divided into groups according to their self-reported good, moderate, and poor lifestyles based on their responses to a questionnaire regarding eight health practices (cigarette smoking, alcohol consumption, sleeping hours, working hours, physical exercise, eating breakfast, balanced nutrition, and mental stress), the presence or absence of each of which was summed to obtain a health practice index (HPI: range 0-8). Peripheral blood was taken and the cytokinesis-block micronuclei (CBMN) assay was performed. RESULTS: Total lifestyle quality as measured by the HPI was strongly negatively associated with MN frequency in cultured human lymphocytes (p<0.01). Nutritional imbalance, lack of regular exercise (<2 times per week), insufficient sleep (< or =6 h per day), and overtime working (> or =9 h per day) each contributed significantly to higher MN frequency (all p<0.05). In the smoker group, a significantly higher MN frequency was only found in heavy smokers (p<0.05). On the other hand, mental stress, eating breakfast, and alcohol drinking had no effect on MN frequency. CONCLUSIONS: Taken together, these findings indicate that poor lifestyle habits significantly increase MN frequency in human lymphocytes.

Differential responses to mutagens among human lymphocyte subpopulations.

Many previous studies have described differential responses to mutagens among human lymphocyte subpopulations. However, there are some confusing data about the sensitivity to mutagens among lymphocyte subpopulations. In this paper we review the studies published to date reporting differential responses among CD4+ T-cells, CD8+ T-cells, B-cells and NK-cells exposed to different mutagens, using different assay methods, such as micronuclei (MN), sister chromatid exchanges (SCEs), single cell gel electrophoresis (SCGE), and fluorescence-activated cell sorting (FACS). These methods are mostly used for genetic biomonitoring of human populations exposed to potential mutagens. Thus, this review may provide a reference of target cells sensitive to mutagens that will be useful for genetic biomonitoring of human populations.

Effects of cigarette smoking, XRCC1 genetic polymorphisms, and age on basal DNA damage in human blood mononuclear cells.

The aim of this study was to investigate the effects of smoking, polymorphisms of XRCC1 codons 194 and 399, and age on levels of basal DNA damage (as measured by an alkaline comet assay) on mononuclear cells in 122 healthy Japanese workers. In the whole group of 122 individuals, the tail moment (TM) values of current smokers (P < 0.001) or former smokers (P = 0.03) were significantly higher than those of nonsmokers. Individuals bearing the XRCC1 399Gln variant allele showed significant increases in TM values in all subjects or in referent subgroups stratified by age or smoking status except in the current smokers group; in contrast, the TM values of individuals bearing the XRCC1 194Trp variant allele were significantly lower than those of individuals bearing wild-type Arg/Arg genotypes. Furthermore, older subjects (> or =47 years old) had significantly higher TM values than younger subjects (<47 years old) in all subjects (P = 0.008). Multiple regression analysis indicated that smoking habits, polymorphisms of XRCC1 codons 194 and 399, and age were important variables affecting individuals basal DNA damage.

Differential DNA damage induced by H2O2 and bleomycin in subpopulations of human white blood cells.

The purpose of this study was to characterize the differential sensitivities of various subpopulations of human white blood cells after exposure to H2O2 (an oxidant agent) and bleomycin (a radiomimetic glycopeptide), in vitro, using single-cell gel electrophoresis (SCGE). Human peripheral blood was fractionated into mononuclear cells, which were further separated into monocytes, CD4+ T-cells, CD8+ T-cells, B-cells and natural killer cells (NK cells). The separated fractions were exposed to different doses of H2O2 and bleomycin, and then used to measure levels of induced and basal DNA damage. There was a significant increase in the amount of DNA damage in CD4+ T-cells, CD8+ T-cells, NK cells and B-cells when treated with H2O2 and bleomycin, whereas monocytes had the lowest sensitivity to H2O2 compared with the other cell fractions, but no lower sensitivity to bleomycin. Furthermore, CD4+ T-cells and CD8+ T-cells had the highest levels of basal DNA damage. When basal DNA damage was taken into account, NK cells tended to show a higher sensitivity to H2O2 than CD4+ T-cells, CD8+ T-cells and monocytes. In addition, B-cells, which showed lower sensitivity to H2O2 than CD4+ T-cells, CD8+ T-cells and NK cells when exposed to lower doses of H2O2 (<10 microM), showed higher sensitivity to H2O2 at higher doses (>20 microM). On the other hand, B-cells showed the highest sensitivity to bleomycin.

Urinary miR-21 as a potential biomarker of hypertensive kidney injury and fibrosis.

Kidney biopsy is considered the golden criterion for diagnosing the etiology of kidney disease but accompanied by non-negligible complications. We explored the possibility of using urinary microRNA (miRNA) as a non-invasive biomarker for hypertensive kidney injury. We assessed differential miRNA expressions in the kidneys and urine of hypertensive mice with kidney injury induced by deoxycorticosterone acetate (DOCA)-salt compared to the controls. DOCA-salt treatment significantly increased renal tubular lesions from day 2 and mRNA expression of fibrosis-related genes from day 4 compared to the controls, respectively. Urinary albumin and N-acetyl-beta-D-glucosaminidase was significantly increased on day 8 compared to the controls. Array results showed that 20 out of 585 miRNAs were highly expressed in the kidneys and significantly increased on day 8 compared to the controls, including miR-21, miR-146b, miR-155 and miR-132, which were confirmed by real-time polymerase chain reaction and were significantly higher from day 4. The miR-21/creatinine in the urine from day 4 was significantly higher than that of the controls and was detected earlier than urinary albumin. In conclusion, we have identified urinary miR-21 that correlates with histopathological lesions and functional markers of kidney damage to facilitate a potential noninvasive detection for hypertensive kidney injury.

miRNA Profiles of Tubular Cells: Diagnosis of Kidney Injury.

MicroRNAs (miRNAs) are small noncoding RNAs of 18-23 nucleotides that regulate gene expression. Recently, plasma miRNAs have been investigated as biomarkers for various physiological and pathological conditions. The present study details the conserved miRNA expression profiles of tubular tissues, and discusses whether they could be used to distinguish between proximal tubule injury, diagnose acute kidney injury (AKI), and the early-stage renal tubular dysfunction. miRNA expression was assessed with miRNA array and real-time reverse transcription polymerase chain reaction using the TaqMan system. The expression profiles of miR-200a/b/c, miR-145, miR-192, miR-194, miR-216a/b, miR-217, and miR-449a in human and rat tubular tissues such as the kidneys, lung, small intestine, and various exocrine glands were adequate for discriminating tubular tissues. In the kidney, miR-192 and miR-194 were highly expressed, whereas miR-145 and miR-449a were absent. miR-145 and miR-449a were relatively specifically expressed in small intestine and lung, respectively. Therefore, the combined levels of miR-200a/b/c, miR-192, and miR-194 in plasma were very useful in diagnosing AKI induced by contact freezing in mice. Moreover, urinary miR-200a levels were useful for the diagnosis of renal tubular dysfunction in Dahl salt-sensitive rat with high salt administration. Our results indicate that miRNA expression profiles are useful as biomarkers for identification of various kidney injuries.