CD206+ macrophages are relevant non-invasive imaging biomarkers and therapeutic targets in experimental lung fibrosis.

BACKGROUND: Interstitial lung diseases (ILDs) include a large number of diseases associated with progressive pulmonary fibrosis (PPF), including idiopathic pulmonary fibrosis (IPF). Despite the rarity of each of the fibrotic ILDs individually, they cumulatively affect a considerable number of patients. PPF is characterised by an excessive collagen deposition leading to functional decline. OBJECTIVES: Therapeutic options are limited to nintedanib and pirfenidone which are only able to reduce fibrosis progression. CD206-expressing M2 macrophages are involved in fibrosis progression, and whether they may be relevant therapeutic targets or biomarkers remains an open question. RESULTS: In our study, CD206+ lung macrophages were monitored in bleomycin-induced lung fibrosis in mice by combining flow cytometry, scRNAseq and in vivo molecular imaging using a single photon emission computed tomography (SPECT) radiopharmaceutical, 99mTc-tilmanocept. The antifibrotic effect of the inhibition of M2 macrophage polarisation with a JAK inhibitor, tofacitinib, was assessed in vivo. We demonstrate that CD206-targeted in vivo SPECT imaging with 99mTc-tilmanocept was able to accurately detect and quantify the increase in CD206+ macrophages from early to advanced stages of experimental fibrosis and ex vivo in lung biopsies from patients with IPF. CD206-targeted imaging also specifically detected a decrease in CD206+ lung macrophages on nintedanib and tofacitinib treatment. Importantly, early in vivo imaging of CD206+ macrophages allowed the prediction of experimental lung fibrosis progression as well as nintedanib and tofacitinib efficacy. CONCLUSIONS: These findings indicate that M2 macrophages may be relevant theranostic targets for personalised medicine for patients with PPF.

The Long Noncoding RNA DNM3OS Is a Reservoir of FibromiRs with Major Functions in Lung Fibroblast Response to TGF-ß and Pulmonary Fibrosis.

Rationale: Given the paucity of effective treatments for idiopathic pulmonary fibrosis (IPF), new insights into the deleterious mechanisms controlling lung fibroblast activation, the key cell type driving the fibrogenic process, are essential to develop new therapeutic strategies. TGF-ß (transforming growth factor-ß) is the main profibrotic factor, but its inhibition is associated with severe side effects because of its pleiotropic role. Objectives: To determine if downstream noncoding effectors of TGF-ß in fibroblasts may represent new effective therapeutic targets whose modulation may be well tolerated. Methods: We investigated the whole noncoding fraction of TGF-ß-stimulated lung fibroblast transcriptome to identify new genomic determinants of lung fibroblast differentiation into myofibroblasts. Differential expression of the long noncoding RNA (lncRNA) DNM3OS (dynamin 3 opposite strand) and its associated microRNAs (miRNAs) was validated in a murine model of pulmonary fibrosis and in IPF tissue samples. Distinct and complementary antisense oligonucleotide-based strategies aiming at interfering with DNM3OS were used to elucidate the role of DNM3OS and its associated miRNAs in IPF pathogenesis. Measurements and Main Results: We identified DNM3OS as a fibroblast-specific critical downstream effector of TGF-ß-induced lung myofibroblast activation. Mechanistically, DNM3OS regulates this process in trans by giving rise to three distinct profibrotic mature miRNAs (i.e., miR-199a-5p/3p and miR-214-3p), which influence SMAD and non-SMAD components of TGF-ß signaling in a multifaceted way. In vivo, we showed that interfering with DNM3OS function not only prevents lung fibrosis but also improves established pulmonary fibrosis. Conclusions: Pharmacological approaches aiming at interfering with the lncRNA DNM3OS may represent new effective therapeutic strategies in IPF.

Tacrolimus-induced nephrotoxicity in mice is associated with microRNA deregulation.

Although Tacrolimus is an immunosuppressive drug widely used in renal transplantation, its chronic use paradoxically induces nephrotoxic effects, in particular renal fibrosis, which is responsible for chronic allograft dysfunction and represents a major prognostic factor of allograft survival. As molecular pathways and mechanisms involved in Tacrolimus-induced fibrogenic response are poorly elucidated, we assessed whether miRNAs are involved in the nephrotoxic effects mediated by Tacrolimus. Treatment of CD-1 mice with Tacrolimus (1 mg/kg/d for 28 days) resulted in kidney injury and was associated with alteration of a gene expression signature associated with cellular stress, fibrosis and inflammation. Tacrolimus also affected renal miRNA expression, including miRNAs previously involved in fibrotic and inflammatory processes as "fibromirs" such as miR-21-5p, miR-199a-5p and miR-214-3p. In agreement with in vivo data, Renal Proximal Tubular Epithelial cells exposed to Tacrolimus (25 and 50 µM) showed upregulation of miR-21-5p and the concomitant induction of epithelial phenotypic changes, inflammation and oxidative stress. In conclusion, this study suggests for the first time that miRNAs, especially fibromiRs, participate to Tacrolimus-induced nephrotoxic effects. Therefore, targeting miRNAs may be a new therapeutic option to counteract Tacrolimus deleterious effects on kidney.

Expression profiles of genes involved in xenobiotic metabolism and disposition in human renal tissues and renal cell models.

Numerous xenobiotics have been shown to be harmful for the kidney. Thus, to improve our knowledge of the cellular processing of these nephrotoxic compounds, we evaluated, by real-time PCR, the mRNA expression level of 377 genes encoding xenobiotic-metabolizing enzymes (XMEs), transporters, as well as nuclear receptors and transcription factors that coordinate their expression in eight normal human renal cortical tissues. Additionally, since several renal in vitro models are commonly used in pharmacological and toxicological studies, we investigated their metabolic capacities and compared them with those of renal tissues. The same set of genes was thus investigated in HEK293 and HK2 immortalized cell lines in commercial primary cultures of epithelial renal cells and in proximal tubular cell primary cultures. Altogether, our data offers a comprehensive description of kidney ability to process xenobiotics. Moreover, by hierarchical clustering, we observed large variations in gene expression profiles between renal cell lines and renal tissues. Primary cultures of proximal tubular epithelial cells exhibited the highest similarities with renal tissue in terms of transcript profiling. Moreover, compared to other renal cell models, Tacrolimus dose dependent toxic effects were lower in proximal tubular cell primary cultures that display the highest metabolism and disposition capacity. Therefore, primary cultures appear to be the most relevant in vitro model for investigating the metabolism and bioactivation of nephrotoxic compounds and for toxicological and pharmacological studies.

The FibromiR miR-214-3p Is Upregulated in Duchenne Muscular Dystrophy and Promotes Differentiation of Human Fibro-Adipogenic Muscle Progenitors.

Fibrosis is a deleterious invasion of tissues associated with many pathological conditions, such as Duchenne muscular dystrophy (DMD) for which no cure is at present available for its prevention or its treatment. Fibro-adipogenic progenitors (FAPs) are resident cells in the human skeletal muscle and can differentiate into myofibroblasts, which represent the key cell population responsible for fibrosis. In this study, we delineated the pool of microRNAs (miRNAs) that are specifically modulated by TGFß1 in FAPs versus myogenic progenitors (MPs) by a global miRNome analysis. A subset of candidates, including several "FibromiRs", was found differentially expressed between FAPs and MPs and was also deregulated in DMD versus healthy biopsies. Among them, the expression of the TGFß1-induced miR-199a~214 cluster was strongly correlated with the fibrotic score in DMD biopsies. Loss-of-function experiments in FAPs indicated that a miR-214-3p inhibitor efficiently blocked expression of fibrogenic markers in both basal conditions and following TGFß1 stimulation. We found that FGFR1 is a functional target of miR-214-3p, preventing the signaling of the anti-fibrotic FGF2 pathway during FAP fibrogenesis. Overall, our work demonstrates that the « FibromiR ¼ miR-214-3p is a key activator of FAP fibrogenesis by modulating the FGF2/FGFR1/TGFß axis, opening new avenues for the treatment of DMD.

Caveolin-1 rs4730751 single-nucleotide polymorphism may not influence kidney transplant allograft survival.

Caveolin-1 is a protein (encoded by the CAV1 gene) supposedly harboring a protective effect against fibrosis. CAV1 rs4730751 single nucleotide polymorphism (SNP) AA genotype was initially associated with lower graft survival compared to non-AA. However, subsequent studies could not find the same effect. CAV1 rs4730751 SNP was investigated on 918 kidney donors. Multivariate Cox-model analyses were performed to evaluate risk factors for graft loss. Longitudinal changes on long-term estimated glomerular filtration rate (eGFRs) were evaluated with a linear mixed model. Histopathological findings from protocolled biopsies after 3 months post transplantation were also analyzed. Donor CAV1 rs4730751 genotyping proportions were 7.1% for AA, 41.6% for AC and 51.3% for CC. The AA genotype, compared to non-AA, was not associated with lower graft survival censored or not for death (multivariate analysis: HR = 1.23 [0.74-2.05] and HR = 1.27 [0.84-1.92]). Linear mixed model on long-term eGFRs revealed also no significant difference according to the genotype, yet we observed a trend. AA genotype was also not associated with a higher degree of fibrosis index on protocolled kidney biopsies at 3 months. To conclude, donor CAV1 rs4730751 SNP may impact on kidney transplantation outcomes, but this study could not confirm this hypothesis.

miR-21-5p renal expression is associated with fibrosis and renal survival in patients with IgA nephropathy.

IgA nephropathy (IgAN) is the most prevalent primary glomerulonephritis, whose prognosis is highly variable. Interstitial fibrosis is a strong independent prognosis factor. Among microRNA involved in renal fibrogenesis, only few have been investigated in IgAN. In the context of IgAN, we aimed to analyze the role of miR-21-5p, miR-214-3p and miR-199a-5p, three established "fibromiRs" involved in renal fibrosis. Fifty-six IgAN biopsy specimens were retrospectively scored according to Oxford classification. Renal expression of miR-21-5p, miR-214-3p and miR-199a-5p were significantly associated with T score (miR-21-5p T0 RQ median = 1.23, T1 RQ = 3.01, T2 RQ = 3.90; miR-214-5p T0 RQ = 1.39, T1 RQ = 2.20, T2 RQ = 2.48; miR-199a-5p T0 RQ = 0.76, T1 RQ = 1.41, T2 RQ = 1.87). miR-21-5p expression was associated with S score (S0 RQ median = 1.31, S1 RQ = 2.65), but not miR-214-3p nor miR-199a-5p. In our cohort, poor renal survival was associated with high blood pressure, proteinuria and elevated creatininemia, as well as T and S scores. Moreover, renal expression of miR-21-5p, miR-214-3p were associated with renal survival. In conclusion, miR-21-5p, miR-214-3p and miR-199a-5p are three "fibromiRs" involved in renal fibrosis in the course of IgAN and miR-21-5p and miR-214-3p are associated with renal survival.

[MicroRNAs in kidney fibrosis]. / Implication des microARN dans la fibrose rénale.

Renal fibrosis represents the final stage of most chronic kidney diseases and contributes to the progressive and irreversible decline in kidney function with accumulation of extracellular matrix components in the renal parenchyma. The molecular mechanisms governing the renal fibrosis process are complex and remain poorly understood. Recently, the profibrotic role of several microRNAs (miRNAs) has been described in kidney fibrosis. MiRNAs are a new class of, small non-coding RNAs of about 20 nucleotides that act as gene expression negative regulators at the post-transcriptional level. Seminal studies have highlighted the potential importance of miRNA as new therapeutic targets and innovative diagnostic and/or prognostic biomarkers. This review summarizes recent scientific advances on the role played by miRNAs in kidney fibrogenesis and discusses potential clinical applications as well as future research directions.

Donor caveolin 1 (CAV1) genetic polymorphism influences graft function after renal transplantation.

BACKGROUND: Identification of the culprit genes underlying multifactorial diseases is one of the most important current challenges of molecular genetics. While recent advances in genomics research have accelerated the discovery of susceptibility genes, much remains to be learned about the functions of disease-associated genetic variants. Recently, Moore and co-workers identified, in the donor genome, an association between a common genetic variant (rs4730751) in the gene encoding caveolin-1 (CAV1), a major structural component of caveolae, and long-term allograft survival. METHODS: Four hundred seventy-five renal recipients consecutively transplanted were included in this study. Donor genomic DNA was extracted and used to genotype CAV1 rs4730751 Single Nucleotide Polymorphism. RESULTS: Patients receiving a graft carrying CAV1 rs4730751 AA genotype displayed a significant decrease in estimated glomerular filtration rate and a significant increase in serum creatinine in both univariate and multivariate analyzes. Moreover, patients receiving a graft with CAV1 AA genotype significantly developed more interstitial fibrosis lesions on systematic biopsies performed 3 months post-transplantation. CONCLUSIONS: Genotyping of CAV1 may be relevant to identify patients at risk of adverse renal transplant outcome.

Donor ABCB1 genetic polymorphisms influence epithelial-to-mesenchyme transition in tacrolimus-treated kidney recipients.

AIM: The contribution of epithelial-mesenchymal transition (EMT) has been suggested in renal transplant recipients receiving calcineurin inhibitors and developing nephrotoxicity. MATERIALS & METHODS: We assessed whether interindividual variability in tacrolimus pharmacokinetics is associated with the occurrence in tubular cells of two EMT markers (vimentin, ß-catenin) detected at 3-month in 140 allograft biopsies. We investigated whether genetic polymorphisms affecting CYP3A5 and ABCB1 influence EMT and kidney fibrosis. RESULTS: In univariate analysis, the donor CYP3A5*1 allele was significantly associated with a lower vimentin expression. In multivariate analysis, grafts carrying ABCB1 3435T allele(s) developed significantly less EMT and less interstitial fibrosis. CONCLUSION: Donor SNPs significantly influence the epithelial program in the context of kidney transplantation, and the epithelial metabolism of tacrolimus is one key to understand graft fibrogenesis.

Isolation and characterization of a primary proximal tubular epithelial cell model from human kidney by CD10/CD13 double labeling.

Renal proximal tubular epithelial cells play a central role in renal physiology and are among the cell types most sensitive to ischemia and xenobiotic nephrotoxicity. In order to investigate the molecular and cellular mechanisms underlying the pathophysiology of kidney injuries, a stable and well-characterized primary culture model of proximal tubular cells is required. An existing model of proximal tubular cells is hampered by the cellular heterogeneity of kidney; a method based on cell sorting for specific markers must therefore be developed. In this study, we present a primary culture model based on the mechanical and enzymatic dissociation of healthy tissue obtained from nephrectomy specimens. Renal epithelial cells were sorted using co-labeling for CD10 and CD13, two renal proximal tubular epithelial markers, by flow cytometry. Their purity, phenotypic stability and functional properties were evaluated over several passages. Our results demonstrate that CD10/CD13 double-positive cells constitute a pure, functional and stable proximal tubular epithelial cell population that displays proximal tubule markers and epithelial characteristics over the long term, whereas cells positive for either CD10 or CD13 alone appear to be heterogeneous. In conclusion, this study describes a method for establishing a robust renal proximal tubular epithelial cell model suitable for further experimentation.

Increased circulating miR-21 levels are associated with kidney fibrosis.

MicroRNAs (miRNAs) are a class of noncoding RNA acting at a post-transcriptional level to control the expression of large sets of target mRNAs. While there is evidence that miRNAs deregulation plays a causative role in various complex disorders, their role in fibrotic kidney diseases is largely unexplored. Here, we found a strong up-regulation of miR-21 in the kidneys of mice with unilateral ureteral obstruction and also in the kidneys of patients with severe kidney fibrosis. In addition, mouse primary fibroblasts derived from fibrotic kidneys exhibited higher miR-21 expression level compared to those derived from normal kidneys. Expression of miR-21 in normal primary kidney fibroblasts was induced upon TGFß exposure, a key growth factor involved in fibrogenesis. Finally, ectopic expression of miR-21 in primary kidney fibroblasts was sufficient to promote myofibroblast differentiation. As circulating miRNAs have been suggested as promising non-invasive biomarkers, we further assess whether circulating miR-21 levels are associated with renal fibrosis using sera from 42 renal transplant recipients, categorized according to their renal fibrosis severity, evaluated on allograft biopsies (Interstitial Fibrosis/Tubular Atrophy (IF/TA). Circulating miR-21 levels are significantly increased in patients with severe IF/TA grade (IF/TA grade 3: 3.0±1.0 vs lower grade of fibrosis: 1.5±1.2; p = 0.001). By contrast, circulating miR-21 levels were not correlated with other renal histological lesions. In a multivariate linear regression model including IF/TA grade and estimated GFR, independent associations were found between circulating miR-21 levels and IF/TA score (ß = 0.307, p = 0.03), and between miR-21 levels and aMDRD (ß = -0.398, p = 0.006). Altogether, these data suggest miR-21 has a key pathogenic role in kidney fibrosis and may represent a novel, predictive and reliable blood marker of kidney fibrosis.