Vimentin Expression and Myofibroblast Infiltration Are Early Markers of Renal Dysfunction in Kidney Transplantation: An Early Stage of Chronic Allograft Dysfunction?

Bortezomib limits renal allograft interstitial fibrosis by inhibiting NF-κB/TNF-α/Akt/mTOR/P70S6K/Smurf2 pathway via IκBα protein stabilization

Chronic allograft dysfunction is a major cause of late graft failure after kidney transplantation. One of the histological changes is interstitial fibrosis, which is associated with epithelial-mesenchymal transition. Bortezomib has been reported to prevent the progression of fibrosis in organs. We used rat renal transplantation model and human kidney 2 cell line treated with tumor necrosis factor-α (TNF-α) to examine their response to bortezomib. To explore the mechanism behind it, we assessed the previously studied TNF-α/protein kinase B (Akt)/Smad ubiquitin regulatory factor 2 (Smurf2) signaling and performed RNA sequencing. Our results suggested that bortezomib could attenuate the TNF-α-induced epithelial-mesenchymal transition and renal allograft interstitial fibrosis in vitro and in vivo. In addition to blocking Akt/mammalian target of rapamycin (mTOR)/p70S6 kinase/Smurf2 signaling, bortezomib's effect on the epithelial-mesenchymal transition was associated with inhibition of nuclear factor kappa B (NF-κB) pathway by stabilizing inhibitor of NF-κB. The study highlighted the therapeutic potential of bortezomib on renal allograft interstitial fibrosis. Such an effect may result from inhibition of NF-κB/TNF-α/Akt/mTOR/p70S6 kinase/Smurf2 signaling via stabilizing protein of inhibitor of NF-κB.

Laser capture microdissection on formalin-fixed and paraffin-embedded renal transplanted biopsies: Technical perspectives for clinical practice application

Renal biopsy (RBx) is an essential tool in the diagnostic and therapeutic process of most native kidney diseases and in the renal transplanted graft. Laser capture microdissection (LCM), combined with molecular biology, might improve the diagnostic power of RBx. However, the limited amount of available renal tissue is often an obstacle for achieving a satisfactory qualitative and quantitative analysis. In our work we present a method which allows us to obtain good quality and quantity of RNA from formalin-fixed and paraffin-embedded (FFPE) renal tissue derived from RBx performed in transplanted patients. Histology, immunohistochemistry, LCM, pre-amplify system and qRT-PCR of biomarkers related to tubular damage, inflammation and fibrosis on FFPE RBx were performed. Glomeruli, tubules and interstitium of three RBx (RB-A: no alteration; RB-B and -C: the progressive rise of creatinine) were compared. The method proposed, could well be useful in future clinical practice. It is quick, easy to perform and allows the analyses of many biomarkers. In addition, it could be extended to all types of RBx without any limitation on the sample amount. Nevertheless, the need for a higher number of well-trained technicians might represent some limitation, counterbalanced by the opportunity to elaborate more accurate diagnosis and, consequently, more targeted therapies.

Protection and immune modulation of activated human vaginal epithelial cells by Aurea helianthus extract

Aurea helianthus extract is associated with various properties including anti-melanogenesis, anti-oxidation, tumorigenic suppression, and immunoregulation; however, the mechanism by which it executes the immunomodulation of human vaginal epithelial cells (HVECs) remains elusive. We established three immunological functions of the extract. First, it mediated tumorigenic suppression in HVECs. Expression of cytokeratin 8, cancer antigen-125, and vimentin was dramatically downregulated in HVECs exposed to the extract under oxidative and fungal stresses. Second, the extract activated dendritic cells and macrophages. On exposing progenitor dendritic cells to the extract, the number of CD304⁺ cells increased by 40%; further, under oxidative and fungal stresses, this number was approximately 1.8 and 1.3 times lower, respectively, compared to that in the stressed cells. In monocytic differentiation, the number of dendritic cells and macrophages increased 9 and 6 times, respectively, compared to that in the control. Additionally, the extract enhanced and recovered polarisation by approximately 1.5 and 2 times, respectively, than that under stressed conditions. Third, the phagocytic activity of macrophages, against HPV16, 18, and 33 peptides, was enhanced by 12–35 times compared with that under stressed conditions. Thus, A. helianthus extract is a strong stimulator of the immune system and tumorigenic suppression under stress conditions.

Short-term dexamethasone treatment transiently, but not permanently, attenuates fibrosis after acute-to-chronic kidney injury

Background

Acute kidney injury (AKI) is an underestimated, yet important, risk factor for the development of chronic kidney disease (CKD). Persistence of inflammation after a renal ischemic injury has been observed, both in experimental models and patients, and is thought to be an important mechanisms underlying progression of acute-to-chronic renal injury. Temporary suppression of inflammation immediately after AKI might therefore be a good first-line therapeutic strategy towards a better long term outcome.

Methods

Male C57Bl/6 J mice (Charles River, 10–12 weeks of age) underwent warm (36 °C body temperature) unilateral ischemia-reperfusion of the kidney for 21 min, after which treatment with intraperitoneal injection of the corticosteroid dexamethasone (10 mg/kg) was initiated for 3 weeks. Both at that time point and after an additional 3 week post-treatment follow up period, fibrosis was quantified by collagen I gene expression and immunostaining, as well as gene expression analysis of fibrosis-related genes Tgfβ, Ccn2 (Ctgf), Pai-1 and Ccn3. Furthermore, inflammation was evaluated by Tnfα gene expression and protein expression of the F4/80 macrophage marker and the α-SMA fibroblast marker. Lastly, renal histopathology was quantified by a morphometric analysis of the tubulointerstitial area.

Results

Treatment with dexamethasone attenuated development of fibrosis, as evidenced by reduced collagen I gene expression and immunostaining, in combination with reduced gene expression of the pro-fibrotic Ccn2 and increased expression of the anti-fibrotic Ccn3. The effects of dexamethasone on renal fibrosis persisted during the 3 week follow up period, as evidenced by stagnation of collagen I deposition in the ischemic kidney, in contrast to vehicle-treatment, where progression of fibrosis was observed. However, expression levels of the pro-fibrotic genes re-approached those of vehicle-treated injured kidneys suggesting that the effects of dexamethasone on fibrosis beyond the treatment period are temporary.

Conclusion

A short term anti-inflammatory therapy with dexamethasone only transiently attenuates ischemia induced fibrosis. Prolonged or persistent anti-inflammatory treatment seems warranted to achieve long term benefit.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1151-7) contains supplementary material, which is available to authorized users.

Urinary transcriptomics reveals patterns associated with subclinical injury of the renal allograft

AIM

Subclinical pathological features in renal allograft biopsies predict poor outcomes, and noninvasive biomarkers are wanted. RNA quantification in urine predicts overt rejection. We hypothesized that a whole transcriptome analysis would be informative, even for discrete injury.

PATIENTS & METHODS

We performed an mRNA microarray with an optimized normalization method on 26 urinary cell pellets to study renal partial epithelial to mesenchymal transition (pEMT) in stable kidney allografts.

RESULTS & CONCLUSION

Unbiased pathway analysis revealed immune response as the main underlying biological process. In a subgroup of pristine biopsies, isolated pEMT was associated with reduced metabolic functions. Thus, pEMT translates into specific urinary mRNA patterns, in other words, increased inflammation and decreased metabolic functions. Deposited in Gene Expression Omnibus (GSE89652).

Prevention of chronic renal allograft rejection by AS2553627, a novel JAK inhibitor, in a rat transplantation model

BACKGROUND

Janus kinase (JAK) inhibitors are thought to be promising candidates to aid renal transplantation. However, the effectiveness of JAK inhibitors against features of chronic rejection, including interstitial fibrosis/tubular atrophy (IF/TA) and glomerulosclerosis, has not been elucidated. Here, we investigated the effect of AS2553627, a novel JAK inhibitor, on the development of chronic rejection in rat renal transplantation.

METHODS

Lewis (LEW) to Brown Norway (BN) rat renal transplantation was performed. Tacrolimus (TAC) at 0.1mg/kg was administered intramuscularly once a day for 10 consecutive days starting on the day of transplantation (days 0 to 9) to prevent initial acute rejection. After discontinuation of TAC treatment from days 10 to 28, AS2553627 (1 and 10mg/kg) was orally administered with TAC. At 13weeks after renal transplantation, grafts were harvested for histopathological and mRNA analysis. Creatinine and donor-specific antibodies were measured from plasma samples. Urinary protein and kidney injury markers were also evaluated.

RESULTS

AS2553627 in combination with TAC exhibited low plasma creatinine and a marked decrease in urinary protein and kidney injury markers, such as tissue inhibitor of metalloproteinase-1 and kidney injury molecule-1. At 13weeks, histopathological analysis revealed that AS2553627 treatment inhibited glomerulosclerosis and IF/TA. In addition, upregulation of cell surface markers, fibrosis/epithelial-mesenchymal transition and inflammation-related genes were reduced by the combination of AS2553672 and TAC, particularly CD8 and IL-6 mRNAs, indicating that AS2553627 prevented cell infiltration and inflammation in renal allografts.

CONCLUSIONS

These results indicate the therapeutic potential of JAK inhibitors in chronic rejection progression, and suggest that AS2553627 is a promising agent to improve long-term graft survival after renal transplantation.

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, β-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.

Vimentin is a dominant target of in situ humoral immunity in human lupus tubulointerstitial nephritis

OBJECTIVE

In lupus nephritis (LN), severe tubulointerstitial inflammation (TII) predicts progression to renal failure. Severe TII is associated with tertiary lymphoid neogenesis and in situ antigen-driven clonal B cell selection. The autoantigen(s) driving in situ B cell selection in TII are not known. This study was undertaken to identify the dominant driving autoantigen(s).

METHODS

Single CD38+ or Ki-67+ B cells were laser captured from 7 biopsy specimens that were diagnostic for LN. Eighteen clonally expanded immunoglobulin heavy- and light-chain variable region pairs were cloned and expressed as monoclonal antibodies. Seven more antibodies were cloned from flow-sorted CD38+ cells from an eighth biopsy specimen. Antigen characterization was performed using a combination of confocal microscopy, enzyme-linked immunosorbent assay, screening protoarrays, immunoprecipitation, and mass spectrometry. Serum IgG titers to the dominant antigen in 48 LN and 35 non-nephritic lupus samples were determined using purified antigen-coated arrays. Autoantigen expression on normal and LN kidney was localized by immunohistochemistry and immunofluorescence.

RESULTS

Eleven of 25 antibodies reacted with cytoplasmic structures, 4 reacted with nuclei, and none reacted with double-stranded DNA. Vimentin was the only autoantigen identified by both mass spectrometry and protoarray. Ten of the 11 anticytoplasmic TII antibodies directly bound vimentin. Vimentin was highly expressed by tubulointerstitial inflammatory cells, and the TII antibodies tested preferentially bound inflamed tubulointerstitium. Finally, high titers of serum antivimentin antibodies were associated with severe TII (P = 0.0001).

CONCLUSION

Vimentin, an antigenic feature of inflammation, is a dominant autoantigen targeted in situ in LN TII. This adaptive autoimmune response likely feeds forward to worsen TII and renal damage.

Recent advances in renal interstitial fibrosis and tubular atrophy after kidney transplantation

Although kidney transplantation has been an important means for the treatment of patients with end stage of renal disease, the long-term survival rate of the renal allograft remains a challenge. The cause of late renal allograft loss, once known as chronic allograft nephropathy, has been renamed “interstitial fibrosis and tubular atrophy” (IF/TA) to reflect the histologic pattern seen on biopsy. The mechanisms leading to IF/TA in the transplanted kidney include inflammation, activation of renal fibroblasts, and deposition of extracellular matrix proteins. Identifying the mediators and factors that trigger IF/TA may be useful in early diagnosis and development of novel therapeutic strategies for improving long-term renal allograft survival and patient outcomes. In this review, we highlight the recent advances in our understanding of IF/TA from three aspects: pathogenesis, diagnosis, and treatment.

Histopathology and biomarkers in prediction of renal function in children after kidney transplantation

BACKGROUND

Early detection of chronic allograft injury is a major challenge after kidney transplantation (RTx) in adults and children. We correlated the expression of four immunohistochemical biomarkers, P-selectin glycoprotein ligand-1 (PSGL-1), vimentin, α-smooth muscle actin (α-SMA) and collagen IV, to the kidney graft histology and function in pediatric RTx patients.

METHODS

We analyzed the histopathology and immunohistochemical stainings of 165 biopsies from 56 patients. Histopathology was scored according to Banff '05 classification and biomarker expression semiquantitatively. Glomerular filtration rate (GFR) was measured annually by (51)Cr-EDTA clearance.

RESULTS

In protocol biopsies, the expression of all four biomarkers correlated with the interstitial fibrosis and tubular atrophy (IF/TA) changes, which increased during the first 36months after RTx. At the time of 18month biopsy, we observed the deterioration of GFR in patients with high (≥2) IF/TA score (50 vs. 68ml/min/1.73m(2), p=0.004) or collagen IV expression (45 vs. 65ml/min/1.73m(2), p=0.016). Intense stainings of IF/TA, collagen IV and vimentin are also associated with poor GFR at 36 and 48months, however, the biomarker scores revealed no additional predictive value for concomitant or late GFR compared to IF/TA score. Patients with high and low biomarker expressions showed no significant differences in annual deterioration of GFR, which declined on average 2.2ml/min/1.73m(2)/year over the 7years follow-up.

CONCLUSIONS

Overall, the results suggest that traditional histopathology is a sufficient predictor for graft function, and the routine use of these histochemical markers as surrogates for graft function deterioration is questioned.

Preservation of Kidneys by Machine Perfusion Influences Gene Expression and May Limit Ischemia/Reperfusion Injury

Context

Machine perfusion improves graft survival. Histopathologic analysis reveals a lower incidence of chronic rejection and interstitial fibrosis in kidneys preserved with machine perfusion. Ischemic/reperfusion injury may help to explain these findings.

Objective

To assess the activation of genes correlated with ischemic/reperfusion injury in kidneys preserved under different conditions before transplant.

Design/Patients

Between 2005 and 2006, 69 kidney biopsy specimens were collected and patients were followed up for 5 years after that.

Intervention

Before transplant, kidneys were preserved with machine perfusion or cold storage. Donors from the machine perfusion and cold storage groups did not differ with regard to age, sex, or hemodynamic status. Recipients were divided into 5 groups: expanded criteria donor–machine perfusion (n = 16), standard criteria donor–machine perfusion (n = 10), expanded criteria donor–cold storage (n = 9), and standard criteria donor–cold storage (n = 27); 7 kidneys were retrieved from living related donors.

Main Outcome Measures

Biopsies were done 30 minutes after reperfusion. Interleukin-1β, vascular endothelial growth factor, heme oxygenase-1, and hypoxia-inducible factor–1 gene expression levels were analyzed.

Results

Mean expression levels of hypoxia-inducible factor–1α were significantly higher in the cold storage groups, and lower in the machine perfusion and living-related donor groups. Five-year graft survival was significantly ( P < .05) lower in the expanded criteria donor–cold storage group (66%) than in the standard criteria donor–machine perfusion group (90%). Machine perfusion influences gene expression related to hypoxia during reperfusion and may improve the long-term results of kidney transplant.

Kidney hypoxia, attributable to increased oxygen consumption, induces nephropathy independently of hyperglycemia and oxidative stress

Diabetic nephropathy is strongly associated with both increased oxidative stress and kidney tissue hypoxia. The increased oxidative stress causes increased kidney oxygen consumption resulting in kidney tissue hypoxia. To date, it has been difficult to determine the role of kidney hypoxia, per se, for the development of nephropathy. We tested the hypothesis that kidney hypoxia, without confounding factors such as hyperglycemia or elevated oxidative stress, results in nephropathy. To induce kidney hypoxia, dinitrophenol (30 mg per day per kg bodyweight by gavage), a mitochondrial uncoupler that increases oxygen consumption and causes kidney hypoxia, was administered for 30 consecutive days to rats. Thereafter, glomerular filtration rate, renal blood flow, kidney oxygen consumption, kidney oxygen tension, kidney concentrations of glucose and glycogen, markers of oxidative stress, urinary protein excretion, and histological findings were determined and compared with vehicle-treated controls. Dinitrophenol did not affect arterial blood pressure, renal blood flow, glomerular filtration rate, blood glucose, or markers of oxidative stress but increased kidney oxygen consumption, and reduced cortical and medullary concentrations of glucose and glycogen, and resulted in intrarenal tissue hypoxia. Furthermore, dinitrophenol treatment increased urinary protein excretion, kidney vimentin expression, and infiltration of inflammatory cells. In conclusion, increased mitochondrial oxygen consumption results in kidney hypoxia and subsequent nephropathy. Importantly, these results demonstrate that kidney tissue hypoxia, per se, without confounding hyperglycemia or oxidative stress, may be sufficient to initiate the development of nephropathy and therefore demonstrate a new interventional target for treating kidney disease.

EMT-MET in renal disease: should we curb our enthusiasm?

Renal epithelial cells arise during embryogenesis by mesenchymal to epithelial transition (MET). In the context of renal diseases, these cells can switch back to a mesenchymal phenotype, in a process thus reminiscent of an epithelial-to-mesenchymal transition (EMT) in which we referred to as "Epithelial Phenotypic Changes" (EPC). The pathophysiological consequence of EPC is controversial: in particular, to what extent EPC contribute to the pool of disease-associated renal fibroblasts is very uncertain. However, there is strong evidence that EPC correlate with a poor renal outcome. EPC indeed reflect an exposure to a profibrotic environment, at an early and potentially reversible stage. Detecting EPC has potential therapeutic implications for patients prone to renal fibrosis, both as a marker of efficacy or more directly as a target. In opposition to the EMT occurring during embryogenesis, EMT in fibrosis as well as in cancer is an anarchic cellular process actually developing at the expense of the whole organ(ism).

Epithelial phenotypic changes detect cyclosporine in vivo nephrotoxicity at a reversible stage

BACKGROUND

A widely used immunosuppressant, cyclosporine A (CsA), conveys long-term nephrotoxicity in some patients. However, no specific marker is presently available. In both native and transplanted human kidneys, epithelial phenotypic changes (EPCs) suggestive of epithelial to mesenchymal transition (EMT) are expressed in various diseases and are prognostic with respect to progression of interstitial fibrosis. We hypothesized that CsA is able to trigger these EPCs in tubular cells in vivo.

METHODS

We studied the kinetics of the EMT markers β-catenin, snail, vimentin, collagen III, and HSP47 at the messenger RNA and protein levels in the kidneys from rats injected with 15 mg/kg/day of CsA or its vehicle. We investigated several therapeutic strategies available to block EMT in this model.

RESULTS

By 2 weeks, CsA had induced histological changes (tubular dilatation and vacuoles) and overexpression of EMT-related genes. This up-regulation of the EMT program was associated with tubular, not interstitial, overexpression of mesenchymal markers. Angiotensin II and endothelin receptor antagonists failed to prevent this CsA-induced EMT. Interestingly, CsA withdrawal led to the gradual regression of histological lesions and EMT, demonstrating that it not only prevents progression but also allows healing of renal injury.

CONCLUSION

Our study suggests that detecting EPC could help to identify ongoing renal CsA-induced toxicity at an early and reversible stage.

Epithelial to mesenchymal transition as a biomarker in renal fibrosis: are we ready for the bedside?

Over the past two decades, the concept of the epithelial to mesenchymal transition (EMT) has been imported from embryology and oncology to fibrosis, particularly in the kidney. This interest in EMT in the context of renal fibrosis stems from observations of epithelial cells undergoing phenotypic changes reminiscent of fibroblasts. Whether EMT is actually a source of interstitial fibroblasts has been the subject of heated debate, and this controversy has caused physicians to neglect the value of EMT as a biomarker in renal fibrosis. In this review, we describe the evolution of the techniques used to detect EMT during fibrosing renal diseases, and what information they provide in the diagnosis of various renal diseases. Highlighting the great heterogeneity of these techniques and the need to standardize them, we warn against some misleading uses of EMT markers. We suggest using the association of vimentin and β-catenin for the diagnosis of EMT in renal pathology because it is both sensitive and prognostic, thus satisfying the properties required for a screening test. Finally, we discuss the potential interests to diagnose EMT for the comprehension of renal fibrosis and for clinical practice.