Glomerular and tubulointerstitial miR-638, miR-198 and miR-146a expression in lupus nephritis

Mini-review: emerging roles of microRNAs in the pathophysiology of renal diseases

MicroRNAs (miRNA) are endogenously produced short noncoding regulatory RNAs that can repress gene expression by posttranscriptional mechanisms. They can therefore influence both normal and pathological conditions in diverse biological systems. Several miRNAs have been detected in kidneys, where they have been found to be crucial for renal development and normal physiological functions as well as significant contributors to the pathogenesis of renal disorders such as diabetic nephropathy, acute kidney injury, lupus nephritis, polycystic kidney disease, and others, due to their effects on key genes involved in these disease processes. miRNAs have also emerged as novel biomarkers in these renal disorders. Due to increasing evidence of their actions in various kidney segments, in this mini-review we discuss the functional significance of altered miRNA expression during the development of renal pathologies and highlight emerging miRNA-based therapeutics and diagnostic strategies for early detection and treatment of kidney diseases.

Increased Urinary Exosomal MicroRNAs in Patients with Systemic Lupus Erythematosus

There is increased interest in using microRNAs (miRNAs) as biomarkers in different diseases. Present in body fluids, it is controversial whether or not they are mainly enclosed in exosomes, thus we studied if urinary miRNAs are concentrated inside exosomes and if the presence of systemic lupus erythematosus with or without lupus nephritis modifies their distribution pattern. We quantified specific miRNAs in urine of patients with systemic lupus erythematosus (n = 38) and healthy controls (n = 12) by quantitative reverse-transcription PCR in cell-free urine, exosome-depleted supernatant and exosome pellet obtained by ultracentrifugation. In control group, miR-335* and miR-302d were consistently higher in exosomes than in exosome-depleted supernatant, and miR-200c and miR-146a were higher in cell-free fraction. In lupus patients, all urinary miRNAs tested were mainly in exosomes with lower levels outside them (p<0.05 and p<0.01, respectively). This pattern is especially relevant in patients with active lupus nephritis compared to the control group or to the SLE patients in absence of lupus nephritis, with miR-146a being the most augmented (100-fold change, p<0.001). Among the exosomal miRNAs tested, only the miR-146a discriminates the presence of active lupus nephritis. In conclusion, urinary miRNAs are contained primarily in exosomes in systemic lupus erythematosus, and the main increment was found in the presence of active lupus nephritis. These findings underscore the attractiveness of exosomal miRNAs in urine, a non-invasive method, as potential renal disease markers.

Common MIR146A Polymorphisms in Chinese Ankylosing Spondylitis Subjects and Controls

Common polymorphisms of microRNA gene MIR146A were reported as associated with different autoimmune diseases, include systemic lupus erythematosus, psoriatic arthritis, asthma and ankylosing spondylitis. In this study we investigated MIR146A SNPs in Chinese people with ankylosing spondylitis. Three common SNPs: rs2910164, rs2431697 and rs57095329 were selected and genotyped in 611 patients and 617 controls. We found no association between these SNPs and ankylosing spondylitis in our samples.

Extracellular Vesicles as Biomarkers of Systemic Lupus Erythematosus

Systemic lupus erythematosus is an autoimmune disease that predominantly affects women and typically manifests in multiple organs. The damage caused by this disorder is characterized by a chronic inflammatory state. Extracellular vesicles (EVs), including microvesicles (also known as microparticles), apoptotic bodies, and exosomes, are recognized vehicles of intercellular communication, carrying autoantigens, cytokines, and surface receptors. Therefore, the evidence of EVs and their cargo as biomarkers of autoimmune disease is rapidly expanding. This review will focus on biogenesis of extracellular vesicles, their pathophysiological roles, and their potential as biomarkers and therapeutics in inflammatory disease, especially in systemic lupus erythematosus.

Let-7 miRNAs Modulate the Activation of NF-κB by Targeting TNFAIP3 and Are Involved in the Pathogenesis of Lupus Nephritis

TNFAIP3 is a ubiquitin-editing enzyme that negatively regulates multiple NF-κB signaling pathways and dysregulation of TNFAIP3 is related to systemic lupus erythematosus (SLE). Although there exists evidence indicating that microRNAs (miRNAs) modulate the expression of TNFAIP3, whether and how miRNAs regulate TNFAIP3 and contribute to lupus nephritis (LN) is still not well understood. In this study, we screened eleven selected miRNAs that potentially regulated TNFAIP3 expression by dual luciferase assay and found that Let-7 miRNAs repressed TNFAIP3 expression by targeting the 3′UTR of TNFAIP3 mRNA. Overexpression of Let-7 miRNAs led to increased phosphorylation and sustained degradation of IκBα and enhanced phosphorylation of p65 following TNFα stimulation and promoted SeV-induced production of cytokines in HEK293T cells. In addition, the expression of Let-7 miRNAs was significantly up-regulated, and TNFAIP3 level was remarkably down-regulated in samples from LN patients compared control samples. Our findings have uncovered Let-7-TNFAIP3-NF-κB pathway that is involved in LN and thus provided a potential target for therapeutic intervention.

Biomarkers for Refractory Lupus Nephritis: A Microarray Study of Kidney Tissue

The prognosis of severe lupus nephritis (LN) is very different among individual patients. None of the current biomarkers can be used to predict the development of refractory LN. Because kidney histology is the gold standard for diagnosing LN, the authors hypothesize that molecular signatures detected in kidney biopsy tissue may have predictive value in determining the therapeutic response. Sixty-seven patients with biopsy-proven severely active LN by International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification III/IV were recruited. Twenty-three kidney tissue samples were used for RNA microarray analysis, while the remaining 44 samples were used for validation by real-time polymerase chain reaction (PCR) gene expression analysis. From hundreds of differential gene expressions in refractory LN, 12 candidates were selected for validation based on gene expression levels as well as relevant functions. The candidate biomarkers were members of the innate immune response molecules, adhesion molecules, calcium-binding receptors, and paracellular tight junction proteins. S100A8, ANXA13, CLDN19 and FAM46B were identified as the best kidney biomarkers for refractory LN, and COL8A1 was identified as the best marker for early loss of kidney function. These new molecular markers can be used to predict refractory LN and may eventually lead to novel molecular targets for therapy.

microRNAs in glomerular diseases from pathophysiology to potential treatment target

miRNAs are regulators of gene expression in diverse biological and pathological courses in life. Their discovery may be considered one of the most important steps in the story of modern biology. miRNAs are packed within exosomes and released by cells for cellular communications; they are present in bodily fluids. Their study opens the way for understanding the pathogenetic mechanisms of many diseases; furthermore, as potential candidate biomarkers, they can be measured in bodily fluids for non-invasive monitoring of disease outcomes. The present review highlights recent advances in the role of miRNAs in the pathogenesis of primary and secondary glomerulonephritides such as IgA nephropathy, focal segmental glomerular sclerosis, lupus nephritis and diabetic nephropathy. The identification of reciprocal expression of miRNAs and their target genes provides the molecular basis for additional information on the pathogenetic mechanisms of kidney diseases. Finally, recent findings demonstrate that miRNAs can be considered as potential targets for novel drugs.

miRNAs in urine: a mirror image of kidney disease?

miRNAs are short non-coding RNAs that control post-transcriptional regulation of gene expression. They are found ubiquitously in tissue and body fluids and participate in the pathogenesis of many diseases. Due to these characteristics and their stability, miRNAs could serve as biomarkers of different pathologies of the kidney. Urine is a non-invasive reservoir of molecules, especially indicative of the urinary system. In this review, we focus on urinary miRNAs and their potential to serve as biomarkers in kidney disease. Past studies show that urinary miRNAs correlate with renal dysfunctions and with processes involved in the pathophysiology. However, these studies also stress the need for future research focusing on large-scale studies to confirm the usability of urinary miRNAs as diagnostic and/or prognostic markers of different kidney diseases in clinical practice.

Decreased miR-26a expression correlates with the progression of podocyte injury in autoimmune glomerulonephritis

MicroRNAs contribute to the pathogenesis of certain diseases and may serve as biomarkers. We analyzed glomerular microRNA expression in B6.MRLc1, which serve as a mouse model of autoimmune glomerulonephritis. We found that miR-26a was the most abundantly expressed microRNA in the glomerulus of normal C57BL/6 and that its glomerular expression in B6.MRLc1 was significantly lower than that in C57BL/6. In mouse kidneys, podocytes mainly expressed miR-26a, and glomerular miR-26a expression in B6.MRLc1 mice correlated negatively with the urinary albumin levels and podocyte-specific gene expression. Puromycin-induced injury of immortalized mouse podocytes decreased miR-26a expression, perturbed the actin cytoskeleton, and increased the release of exosomes containing miR-26a. Although miR-26a expression increased with differentiation of immortalized mouse podocytes, silencing miR-26a decreased the expression of genes associated with the podocyte differentiation and formation of the cytoskeleton. In particular, the levels of vimentin and actin significantly decreased. In patients with lupus nephritis and IgA nephropathy, glomerular miR-26a levels were significantly lower than those of healthy controls. In B6.MRLc1 and patients with lupus nephritis, miR-26a levels in urinary exosomes were significantly higher compared with those for the respective healthy control. These data indicate that miR-26a regulates podocyte differentiation and cytoskeletal integrity, and its altered levels in glomerulus and urine may serve as a marker of injured podocytes in autoimmune glomerulonephritis.

Evaluation of microRNAs miR-196a, miR-30a-5P, and miR-490 as biomarkers of disease activity among patients with FSGS

BACKGROUND AND OBJECTIVES

This study aimed to identify urinary microRNAs (miRNAs) as biomarkers for FSGS disease activity.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Candidate urinary miRNAs were identified in pooled urine samples from patients with active FSGS (FSGS-A) and FSGS in remission (FSGS-CR), and were then validated using individual samples. Their levels were compared both under different treatment responses in a prospective study of FSGS and in patients with different membranous nephropathy (MN) and diabetic nephropathy (DN) disease activity. The prediction of these miRNAs for treatment responses was further analyzed in both retrospective and prospective cohorts of patients with FSGS.

RESULTS

All 54 miRNAs were included as candidate biomarkers, including those with high levels in patients with FSGS-A (n=9) under the TaqMan Low Density Array as well as those with conserved expression in kidneys and involved in immune response. TaqMan probe-based quantitative RT-PCR confirmed the higher levels of four miRNAs in patients with FSGS-A in two independent cohorts (n=18 and n=80). Urinary miR-196a, miR-30a-5p, and miR-490 discriminated FSGS-A from FSGS-CR, with an area under the curve of ≥ 0.80. After steroid treatment, their levels were lower in steroid-responsive patients with FSGS (all P<0.001), but were unchanged in steroid-resistant patients. The levels of miRNAs were similar between active MN and MN in remission as well as active DN and incipient DN (all P>0.05). Urinary miR-30a-5p marginally predicted the response to steroid treatment in patients with FSGS-A, with an area under the curve of 0.63 (P=0.03).

CONCLUSIONS

The levels of urinary miR-196a, miR-30a-5p, and miR-490 are associated with FSGS disease activity.

The regulation and function of microRNAs in kidney diseases

MicroRNAs (miRNA) are endogenous short noncoding RNAs, which regulate virtually all major cellular processes by inhibiting target gene expression. In kidneys, miRNAs have been implicated in renal development, homeostasis, and physiological functions. In addition, miRNAs play important roles in the pathogenesis of various renal diseases, including renal carcinoma, diabetic nephropathy, acute kidney injury, hypertensive nephropathy, polycystic kidney disease, and others. Furthermore, miRNAs may have great values as biomarkers in different kidney diseases.

Unmet needs in the treatment of autoimmunity: from aspirin to stem cells

As rheumatologic diseases became understood to be autoimmune in nature, the drugs used to treat this group of conditions has evolved from herbal or plant derived anti-inflammatory agents, such as salicylates, quinine and colchicine to the many recently approved biological response modifiers. These new drugs, especially the anti-tumor necrosis factor agents, have shown remarkable efficacy in autoimmune diseases, and there are new agents under investigation that will provide additional treatment options. In between, the world was introduced to cortisone and all of its derivatives, as chemical synthesis led to better, more efficacious drugs with lesser side effects. Disease modifying anti-rheumatic agents have actually been around since the first half of the 20th century, but only began to be used in the treatment of autoimmune diseases in the 1970s and 1980s. One advantage is that they have been invaluable in their ability to offer "steroid sparing" to decrease the adverse effects of steroids. Research over the past decade has resulted in a new class of drugs that influence cytokine regulatory pathways such as the Janus associated kinase inhibitors. The promise of personalized medicine now permeates current research into new pharmacological agents for the treatment of autoimmune disease. The new appreciation for the gene-environment interaction in the pathogenesis of most diseases especially those as heterogeneous as autoimmune diseases, has led to our focus on targeted therapies. Add to that the new knowledge of epigenetics and how changes in DNA and histone structure affect expression of genes that can play a role in immune signaling, and we now have a new exciting frontier for cutting edge drug development. The history of treatment of autoimmune diseases is really only a little over a century, but so much has changed, leading to increasing lifespans and improved quality of life of those who suffer from these ailments.

miR-146a gene polymorphism rs2910164 and the risk of digestive tumors: A meta-analysis of 21 case-control studies

Digestive tumors have the highest incidence among all tumor types worldwide. miR-146a has been shown to play an important role in the development, apoptosis, invasion and metastasis of digestive tumors. Additionally, a miR-146a gene polymorphism has been associated with the risk of a variety of cancer types in the digestive system. Therefore, in order to investigate the correlation, a meta-analysis of reported data was conducted, for which we obtained 21 research studies concerning the association between the miR-146a gene polymorphism and digestive tumors. Odds ratio (OR) values and 95% confidence intervals (95% CI) were used to assess this association. We found that the miR-146a polymorphism rs2910164 might significantly increase the susceptibility of digestive tumors, in particular for esophageal cancer and colorectal cancers. Furthermore, the miR-146a polymorphism might significantly increase the risk of digestive tumors in Asians. However, no obvious correlation between the polymorphism and the risk for digestive tumors was found in Caucasians.

Cellular and urinary microRNA alterations in NZB/W mice with hydroxychloroquine or prednisone treatment

Determining alterations to disease-associated miRNAs induced by specific therapeutics may allow the use of tailored therapy in lupus. We determined miRNA alterations in female NZB/W lupus mice treated with hydroxychloroquine (HCQ) or prednisone (PRED) for 12 weeks beginning at 24 weeks-of-age. B cell, PBMC, and urinary miR-let-7a expression were decreased with HCQ or PRED treatment. HCQ or PRED treatment reduced miR-21 expression in mesangial cells, T cells, pDCs, PBMCs, and the urine. MiR-146a expression was reduced in mesangial cells with HCQ treatment and in pDCs with HCQ or PRED treatment. PRED treatment increased miR-155 expression in mesangial, B, and T cells and PBMCs yet decreased miR-155 expression in pDCs and the urine. In vitro studies confirmed that HCQ or PRED's anti-inflammatory actions are dependent on their ability to inhibit miRNA expression. Our studies indicate that lupus therapeutics may work, in part, by altering the expression of disease-associated miRNAs.

Gene expression and regulation in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disease. Genome-wide (GW) association studies have identified more than 40 disease-associated loci, together accounting for only 10-20% of disease heritability. Gene expression represents the intermediate phenotype between DNA and disease phenotypic variation, and provides insights regarding genetic and epigenetic effects. We review data on gene expression and regulation in SLE by our group and other investigators.

MATERIALS AND METHODS

Systematic PubMed search for GW expression studies in SLE published since the year 2000.

RESULTS

Deregulation of genes involved in type I interferon signaling is a consistent finding in the peripheral blood of active and severe SLE patients. Upregulation of granulocyte-specific transcripts especially in bone marrow mononuclear cells (BMMCs), and of myeloid lineage transcripts in lupus nephritis, provide evidence for pathogenic role of these cells. Gene network analysis in BMMCs identified central gene regulators which could represent therapeutic targets and a high similarity between SLE and non-Hodgkin lymphoma providing a molecular basis for the reported association of the two diseases. Gene expression abnormalities driven by deregulated expression of certain microRNAs in SLE contribute to interferon production, T- and B-cell hyperactivity, DNA hypomethylation, and defective tissue response to injury. Methylation arrays have revealed alterations in white blood cell DNA methylation in SLE suggesting an important role of epigenetics and the environment.

CONCLUSIONS

Gene expression studies have contributed to the characterization of pathogenic processes in SLE. Integrated approaches utilizing genetic variation, transcriptome and epigenome profiling will facilitate efforts towards a molecular-based disease taxonomy.

Update on differences between childhood-onset and adult-onset systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease and occurs worldwide in both children and adults. The estimated annual incidence among children is 2.22/100,000 and among adults is 23.2/100,000 in the United States. There is increasing understanding about differences in disease manifestations, medication use, and disease severity between those with childhood-onset SLE as compared with adult-onset SLE. Children have a more fulminant disease onset and course than adults with SLE, resulting in two to three times higher mortality. In future years, we anticipate more insight into the genetics between childhood-onset SLE and adult-onset SLE to help delineate the best therapies for both subsets of patients.

MicroRNA-155 drives TH17 immune response and tissue injury in experimental crescentic GN

CD4(+) T cells play a pivotal role in the pathogenesis of autoimmune disease, including human and experimental crescentic GN. Micro-RNAs (miRs) have emerged as important regulators of immune cell development, but the impact of miRs on the regulation of the CD4(+) T cell immune response remains to be fully clarified. Here, we report that miR-155 expression is upregulated in the kidneys of patients with ANCA-associated crescentic GN and a murine model of crescentic GN (nephrotoxic nephritis). To elucidate the potential role of miR-155 in T cell-mediated inflammation, nephritis was induced in miR-155(-/-) and wild-type mice. The systemic and renal nephritogenic TH17 immune response decreased markedly in nephritic miR-155(-/-) mice. Consistent with this finding, miR-155-deficient mice developed less severe nephritis, with reduced histologic and functional injury. Adoptive transfer of miR-155(-/-) and wild-type CD4(+) T cells into nephritic recombination activating gene 1-deficient (Rag-1(-/-)) mice showed the T cell-intrinsic importance of miR-155 for the stability of pathogenic TH17 immunity. These findings indicate that miR-155 drives the TH17 immune response and tissue injury in experimental crescentic GN and show that miR-155 is a potential therapeutic target in TH17-mediated diseases.

A competitive regulatory mechanism discriminates between juxtaposed splice sites and pri-miRNA structures

We have explored the functional relationships between spliceosome and Microprocessor complex activities in a novel class of microRNAs (miRNAs), named Splice site Overlapping (SO) miRNAs, whose pri-miRNA hairpins overlap splice sites. We focused on the evolutionarily conserved SO miR-34b, and we identified two indispensable elements for recognition of its 3′ splice site: a branch point located in the hairpin and a downstream purine-rich exonic splicing enhancer. In minigene systems, splicing inhibition owing to exonic splicing enhancer deletion or AG 3′ss mutation increases miR-34b levels. Moreover, small interfering-mediated silencing of Drosha and/or DGCR8 improves splicing efficiency and abolishes miR-34b production. Thus, the processing of this 3′ SO miRNA is regulated in an antagonistic manner by the Microprocessor and the spliceosome owing to competition between these two machineries for the nascent transcript. We propose that this novel mechanism is commonly used to regulate the relative amount of SO miRNA and messenger RNA produced from primary transcripts.

MicroRNAs implicated in the immunopathogenesis of lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the deposition of immune complexes due to widespread loss of immune tolerance to nuclear self-antigens. Deposition in the renal glomeruli results in the development of lupus nephritis (LN), the leading cause of morbidity and mortality in SLE. In addition to the well-recognized genetic susceptibility to SLE, disease pathogenesis is influenced by epigenetic regulators such as microRNAs (miRNAs). miRNAs are small, noncoding RNAs that bind to the 3′ untranslated region of target mRNAs resulting in posttranscriptional gene modulation. miRNAs play an important and dynamic role in the activation of innate immune cells and are critical in regulating the adaptive immune response. Immune stimulation and the resulting cytokine milieu alter miRNA expression while miRNAs themselves modify cellular responses to stimulation. Here we examine dysregulated miRNAs implicated in LN pathogenesis from human SLE patients and murine lupus models. The effects of LN-associated miRNAs in the kidney, peripheral blood mononuclear cells, macrophages, mesangial cells, dendritic cells, and splenocytes are discussed. As the role of miRNAs in immunopathogenesis becomes delineated, it is likely that specific miRNAs may serve as targets for therapeutic intervention in the treatment of LN and other pathologies.

Biomarker profiling for lupus nephritis

Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE), which is associated with significant morbidity and mortality of SLE patients. The pathogenesis of LN involves multiple factors, including genetic predisposition, epigenetic regulation and environmental interaction. Over the last decade, omics-based techniques have been extensively utilized for biomarker screening and a wide variety of variations which are associated with SLE and LN have been identified at the levels of genomics, transcriptomics and proteomics. These studies and discoveries have expanded our understanding of the molecular basis of the disease and are important for identification of potential therapeutic targets for disease prediction and early treatment. In this review, we summarize some of the recent studies targeted at the identification of LN-associated biomarkers using genomics and proteomic approaches.

miR-150 promotes renal fibrosis in lupus nephritis by downregulating SOCS1

MicroRNAs (miRs) seem to mediate renal fibrosis in several renal diseases, with some miRs having profibrotic effects and others having opposing effects. Although differential expression of certain miRs has been described in lupus nephritis, it is unknown whether miRs contribute to fibrosis or could serve as biomarkers of specific histologic manifestations of lupus nephritis. Here, we compared miR expression in kidney biopsies from patients with lupus nephritis and identified miR-150 as the most differentially expressed miR in kidneys with high chronicity (chronicity index [CI] ≥ 4); miR-150 positively correlated with chronicity scores and the expression of profibrotic proteins. Overexpression of miR-150 significantly reduced expression of the antifibrotic protein suppressor of cytokine signaling 1 (SOCS1) and upregulated profibrotic proteins in both proximal tubular and mesangial cells. Directly targeting SOCS1 with a small interfering RNA produced similar results. Furthermore, TGF-β1 induced miR-150 expression, decreased SOCS1, and increased profibrotic proteins in proximal tubular cells and podocytes; a miR-150 inhibitor reversed these changes, suggesting that the profibrotic effects of TGF-β1 are, at least in part, mediated by miR-150. Consistent with these in vitro observations, biopsies with high miR-150 and high CI exhibited substantial expression of TGF-β1, reduced SOCS1, and an increase in profibrotic proteins. In summary, miR-150 is a promising quantitative renal biomarker of kidney injury in lupus nephritis. Our results suggest that miR-150 promotes renal fibrosis by increasing profibrotic molecules through downregulation of SOCS1.

MicroRNA-638 is highly expressed in human vascular smooth muscle cells and inhibits PDGF-BB-induced cell proliferation and migration through targeting orphan nuclear receptor NOR1

AIMS

Aberrant vascular smooth muscle cell (VSMC) proliferation and migration contribute significantly to the development of vascular pathologies, such as atherosclerosis and restenosis. MicroRNAs have recently emerged as critical modulators in cellular processes and the purpose of this study is to identify novel miRNA regulators implicated in human aortic VSMC proliferation and migration.

METHODS AND RESULTS

To identify miRNAs that are differentially expressed in human VSMCs, we performed miRNA microarray analysis in human aortic smooth muscle cells (SMCs) at different time points after platelet-derived growth factor (PDGF) stimulation. Here, we identified microRNA-638 (miR-638) as a transcript that was one of the most significantly down-regulated in human VSMCs after PDGF stimulation. Furthermore, we confirmed, by Quantitative RT-PCR, that miR-638 is highly expressed in human VSMCs, and its expression is markedly down-regulated in a dose- and time-dependent manner upon PDGF treatment. Consistent with a critical role in SMC proliferation, we found that miR-638 expression was significantly up-regulated in human VSMCs cultured in differentiation medium, a condition that inhibits SMC proliferation. Furthermore, we identified the orphan nuclear receptor NOR1 as a downstream target gene product of miR-638 and down-regulation of NOR1 is critical for miR-638-mediated inhibitory effects on PDGF-induced cyclin D1 expression, cell proliferation, and migration in human aortic SMCs.

CONCLUSION

These results indicate that miR-638 is a key molecule in regulating human VSMC proliferation and migration by targeting the NOR1/cyclin D pathway and suggest that specific modulation of miR-638 in human VSMCs may represent an attractive approach for the treatment of proliferative vascular diseases.

Association of MicroRNA-146a with autoimmune diseases

MicroRNAs (miRNAs) are a group of approximately 20-22-nucleotide-long non-coding RNAs that repress target gene expression through mRNA degradation and translation inhibition. MiRNA (miR)-146a, located in the second exon of the LOC285628 gene on human chromosome 5, is a negative regulator in immune and inflammatory responses. Studies have indicated that miR-146a is associated with the pathogenesis of several autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Sjögren's syndrome. In this review, emphasis will be laid on the recent progress in the functional roles of miR-146a in these autoimmune diseases.

MicroRNA involvement in lupus: the beginning of a new tale

PURPOSE OF REVIEW

The contributions of microRNA (miRNA) to pathogenesis of autoimmune diseases such as Systemic lupus erythematosus (SLE) are beginning to be uncovered. In this review, we discuss the major progress made in understanding of miRNA biology, as well as novel insights into SLE pathogenesis mediated by miRNAs.

RECENT FINDINGS

MiRNA biogenesis is a deliberately controlled process, which requires multiple layers of regulation involving participation of various protein regulators and posttranscriptional modifications. Its expression regulation is critically modulated by multiple physiopathological factors such as inflammation, stress, Epstein-Barr virus infection and sex hormones. MiRNAs play a crucial role in maintaining immune system development and function, and are implicated in development of numerous immunological disorders. Unique miRNA expression signatures in SLE reveal their clinical relevance. MiRNAs contribute broadly and actively to various aspects of SLE pathogenesis and hold great therapeutic potential.

SUMMARY

The recent findings underscore the potential importance of miRNAs to pathogenesis, diagnosis and treatment of SLE.

Urinary sediment miRNA levels in adult nephrotic syndrome

BACKGROUND

MicroRNAs are a group of non-coding RNA molecules that play important roles in the pathogenesis of various kidney diseases. We investigate the urinary sediment miRNA levels of adult patients with nephrotic syndrome.

METHODS

We study 20 patients with diabetic glomerulosclerosis (DGS), 21 with minimal change nephropathy (MCN) or focal glomerulosclerosis (FGS), 23 with membranous nephropathy (MGN), and 10 healthy controls. Urinary sediment miRNA levels are quantified.

RESULTS

Urinary sediment miR-29a, miR-192, and miR-200c levels were significantly different between diagnosis groups. Post hoc analysis showed that urinary miR-638 level was significantly lower in all causes of nephrotic syndrome than healthy controls, while the DGS group had lower urinary miR-192 level than other diagnosis groups. In contrast, the MCN/FGS group had higher urinary miR-200c level than other diagnosis groups. For each specific pathology group, urinary level of several miRNA targets significantly correlated with kidney function and histological scarring.

CONCLUSIONS

Urinary miR-29a, miR-192 and miR-200c levels have characteristic alterations among patients with different causes of nephrotic syndrome. Our results suggest that urinary miRNA levels have the potential of being developed as the diagnosis tool and marker of disease severity in adult nephrotic syndrome.