Chronic progressive interstitial fibrosis in renal disease--are there novel pharmacological approaches?

RIP kinases and necroptosis in aging and aging-related diseases

Aging is a natural process that is characterized by chronic, low-grade inflammation, which represents the primary risk factor in the pathogenesis of a variety of diseases, i.e. aging-related diseases. RIP kinases, in particular RIPK1 and RIPK3, have emerged as master regulators of proinflammatory responses that act either by causing apoptosis and necroptosis or by directly regulating intracellular inflammatory signaling. While, RIPK1/3 and necroptosis are intimately linked to multiple human diseases, the relationship among RIPK1/3, necroptosis, and aging remains unclear. In this review, we discuss current evidence arguing for the involvement of RIPK1/3 and necroptosis in the progression of aging. In addition, we provide updated information and knowledge on the role of RIPK1/3 and necroptosis in aging-related diseases. Leveraging these new mechanistic insights in aging, we postulate how our improved understanding of RIPK1/3 and necroptosis in aging may support the development of therapeutics targeting RIPK1/3 and necroptosis for the modulation of aging and treatment of aging-related diseases.

A Case Demonstrating the Pathological Relationship between Granulomatous Vasculitis and Glomerular Lesion in Renal Sarcoidosis

We experienced a rare case of tubulointerstitial angiocentric granulomatous vasculitis with focal segmental glomerulosclerosis (FSGS) and associated sarcoidosis. Our patient was an 18-year-old man who presented with exertional cough and dyspnea. He also had overt proteinuria (3.0 g/24 h), normal renal function (eGFR 95 mL/min/1.73 m²), heart failure, and hypertension. He had no previous episode of hypertension. These manifestations immediately improved after the administration of antihypertensive therapy that contained an angiotensin-converting enzyme inhibitor, calcium antagonists, beta antagonists, and diuretics. However, he, later on, developed renal dysfunction, with worsening of both proteinuria and hypertension. Renal biopsy was performed and showed epithelioid cells that were arranged concentrically around small blood vessels in tubulointerstitial granulomas. In the glomeruli, the segmental sclerotic lesions were classified as a perihilar variant of FSGS. There were no inflammatory changes, such as a mesangial lesion, inflammatory cell infiltration, fibrinoid necrosis, or crescent formation, and no glomerular granuloma. In the tubulointerstitial granulomas, the intimal elastic lamina of the interlobular arteries was reduplicated, and the intimal wall thickness of renal arterioles was remarkable. After receiving oral prednisolone therapy, the overt proteinuria resolved, the eGFR recovered from 39.4 to 60.6 mL/min/1.73 m², and hypertension was managed more easily. Thereafter, he did not experience any recurrence. The concurrent improvement of renal function and proteinuria by steroid treatment suggested a relationship between the glomerular lesions and the tubulointerstitial granulomatous vasculitis with associated sarcoidosis.

Clinical characteristics of biopsy-proven renal sarcoidosis in Japan

Background: Although some articles have described renal sarcoidosis, the incidence among biopsy cases remains unclear. Here, we defined the incidence of renal sarcoidosis among renal biopsy cases and analyzed the clinical course. Methods: We performed an epidemiological study examining renal biopsy cases treated at 5 centers between January 2000 and September 2015 and identified 16 cases (7 men, 9 women; mean (±SD) age, 59.4±18.6 years) out of a total of 14191 renal biopsy cases. Renal involvement of sarcoidosis was defined as granulomatous tubulointerstitial nephritis, tubulointerstitial nephritis without granulomatous lesions, and renal calcinosis. Fifteen of the cases were treated with steroid therapy. One case initially received steroid pulse therapy. The outcome was evaluated based on the estimated glomerular filtration rate (eGFR), CKD stage, and the change in eGFR (ΔeGFR) after treatment. A favorable response was defined as ΔeGFR ≥25%. Results: The incidence of renal sarcoidosis was 0.11%. The mean eGFR was 28.2±16.1 mL/min/1.73 m². At the last observation, the mean eGFR was 43.7±19.7 mL/min/1.73 m². Although a favorable response to steroid therapy was found in the majority of cases (10/15, 67%), 12 of the 15 cases (80%) had residual renal dysfunction at the last observation and 8 cases (53%) had moderate to severe renal dysfunction. Conclusion: Renal sarcoidosis is extremely rare among renal biopsy cases. Among cases with an unfavorable response to steroid therapy, pathogenetic mechanisms other than sarcoidosis and severe nephron damage were observed. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 252-260).

Characterization of transgene expression and pDNA distribution of the suctioned kidney in mice

We have previously developed an efficient and safe transfection method for the kidney in mice: renal suction-mediated transfection. In this study, we verified the detailed characteristics of transgene expression and plasmid DNA (pDNA) in mice to develop therapeutic strategies and application to gene function analysis in the kidney. After naked pDNA was administered intravenously, the right kidney was immediately suctioned by a tissue suction device. We examined the spatial distribution of transgene expression and pDNA in the suctioned kidney using tissue clearing by CUBIC, ClearT2, and Scale SQ reagents. Spatial distribution analysis showed that pDNA was transfected into extravascular cells and sufficiently delivered to the deep renal cortex. In addition, we revealed that transgene expression occurred mainly in peritubular fibroblasts of the suctioned kidney by tissue clearing and immunohistochemistry. Next, we confirmed the periods of pDNA uptake and activation of transcription factors nuclear factor-κB and activator protein 1 by luciferase assays. Moreover, the use of a pCpG-free plasmid enabled sustained transgene expression in the suctioned kidney. In conclusion, analyses of the spatial distribution and immunostaining of the section suggest that pDNA and transgene expression occurs mainly in peritubular fibroblasts of the suctioned kidney. In addition, we clarified some factors for efficient and/or sustained transgene expression in the suctioned kidney.

Fuzheng Huayu Formula () prevents rat renal interstitial fibrosis induced by HgCl2 via antioxidative stress and down-regulation of nuclear factor-kappa B activity

OBJECTIVE

To investigate the mechanism of action of Fuzheng Huayu Formula (, FZHY) against renal interstitial fibrosis (RIF) relating to oxidative injury and nuclear factor-kappa B (NF-κB) activity.

METHODS

Thirty-two Sprague-Dawley rats were randomly divided into 3 groups: normal group, model group and FZHY treatment group. The RIF model was induced by oral administration of HgCl₂ at a dose of 8 mg/kg body weight once a day for 9 weeks. Meanwhile, rats in FZHY treatment group orally took FZHY at a dose of 4.0 g/kg rat weight for 9 weeks. The content of hydroxyproline (Hyp) and collagen deposition in kidney were observed. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), the content of glutathione (GSH) and malondialdehyde (MDA) of kidney were tested. The expressions of inhibitor-κappa B (IκB), phospho-IκB (p-IκB), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-2 (MMP-2) and α-smooth muscle actin (α-SMA) were analyzed by Western blot. α-SMA expression was also observed by immunofluorescent staining. MMP-2 activity was measured by gelatin zymography. NF-κB activation was determined by electrophoretic mobility shift assay.

RESULTS

Renal interstitial fibrosis was induced by HgCl₂, demonstrated by remarkably increased Hyp contents and excessive collagen deposition in kidney (P<0.01). FZHY significantly inhibited renal interstitial collagen deposition and reduced Hyp content of the HgCl₂-treated rats (P<0.01). GSH content decreased obviously, and MDA content increased signifificantly in HgCl₂-treated rats compared with that of normal rats (P<0.01). FZHY significantly increased GSH content and decreased MDA content in the model rats (P<0.01). The expression α-SMA was increased in model rats compared with that of normal rats, FZHY signifificantly decreased its expression (P<0.01). The expressions of p-IκB and TNF-α and MMP-2, MMP-2 activity, and NF-κB activation were increased in model group compared with that in normal group (P<0.01), FZHY signifificantly decreased NF-κB activation, MMP-2 activity and p-IκB and TNF-α expressions (P<0.01).

CONCLUSIONS

FZHY could protect kidney from oxidative injury intoxicated by HgCl₂, and antagonized oxidative stress-stimulated NF-κB activity through inhibition of IκB phosphorylation in the interstitial fibrotic kidney, these effects importantly contributed to FZHY action mechanism against renal interstitial fifibrosis.

The Protective Mechanism of Fluorofenidone in Renal Interstitial Inflammation and Fibrosis

BACKGROUND

Deregulated inflammation has been implicated in the development of renal interstitial fibrosis and progressive renal failure. Previous work has established that fluorofenidone, a pyridone agent, attenuates renal fibrosis. However, the mechanism by which fluorofenidone prevents renal fibrosis remains unclear. The aim of this study was to investigate the in vivo effects of fluorofenidone on unilateral ureteral obstruction-induced fibrosis and the involved molecular mechanism in mouse peritoneal macrophages.

METHODS

Renal fibrosis was induced in rat by unilateral ureteral obstruction for 3, 7 or 14 days. Ipsilateral kidneys were harvested for morphologic analysis. Leukocyte infiltration was assessed by immunohistochemistry staining. The expression of chemokines (MCP-1, RANTAS, IP-10, MIP-1α and MIP-1β) and pro-inflammatory cytokines (TNF-α and IL-1β) was measured by enzyme-linked immunosorbent assay and real-time polymerase chain reaction. Mouse peritoneal macrophages and HK-2 cells were incubated with necrotic MES-13 cells or TNF-α in the presence or absence of fluorofenidone. The production of MCP-1 was measured by enzyme-linked immunosorbent assay, and phosphorylation of ERK1/2, p38 and JNK was quantified by Western blot.

RESULTS

Fluorofenidone treatment hampered renal pathologic change and interstitial collagen deposition. Leukocyte infiltration and the expression of chemokines (MCP-1, RANTES, IP-10, MIP-1α and MIP-1β) and pro-inflammatory cytokines (IL-1α) in kidney were significantly reduced by fluorofenidone treatment. Mechanistically, fluorofenidone significantly inhibited TNF-α or necrotic cell-induced activation of MAP kinase pathways in vitro.

CONCLUSIONS

Fluorofenidone serves as a novel anti-inflammatory agent that attenuates ureteral obstruction-induced renal interstitial inflammation and fibrosis, possibly through the inhibition of the microtubule-associated protein kinase pathways.

Pro: 'The usefulness of biomarkers in glomerular diseases'. The problem: moving from syndrome to mechanism--individual patient variability in disease presentation, course and response to therapy

The diagnosis and treatment decisions in glomerular disease are principally based on renal pathology and nonspecific clinical laboratory measurements such as serum creatinine and urine protein. Using these classification approaches, patients have marked variability in rate of progression and response to therapy, exposing a significant number of patients to toxicity without benefit. Additionally, clinical trials are at risk of not being able to detect an efficacious therapy in relevant subgroups as patients with shared clinical-pathologic diagnoses have heterogeneous underlying pathobiology. To change this treatment paradigm, biomarkers that reflect the molecular mechanisms underlying the clinical-pathologic diagnoses are needed. Recent progress to identify such biomarkers has been aided by advances in molecular profiling, large-scale data generation and multi-scalar data integration, including prospectively collected clinical data. This article reviews the evolving success stories in glomerular disease biomarkers across the genotype-phenotype continuum and highlights opportunities to transition to precision medicine in glomerular disease.

Effects of vitamin E on mercuric chloride-induced renal interstitial fibrosis in rats and the antioxidative mechanism

OBJECTIVE

To observe the effects of vitamin E (Vit E) on mercuric chloride (HgCl2)-induced renal interstitial fibrosis (RIF) in rats and discuss its antioxidative mechanism.

METHODS

A total of 32 Sprague-Dawley rats were randomly assigned to three groups: normal group, model group and Vit E group. RIF was induced by oral administration of HgCl(2) at a dose of 8 mg/kg body weight once a day for 9 weeks. Rats in Vit E group were administered with Vit E capsule at 100 mg/kg body weight, and rats in normal and model groups were treated with normal saline. At the end of the 9th week, rats were sacrificed and renal hydroxyproline (Hyp)'s trichrome and periodic acid-silver methenamine (PASM) staining. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and contents of glutathione (GSH) and malondialdehyde (MDA) in kidney tissue were tested with commercial kits. The expressions of nuclear factor-κB (NF-κB), inhibitor-κB (IκB), phospho-IκB (p-IκB) and tumor necrosis factor-α (TNF-α) were determined by Western blot. The expression of α-smooth muscle actin (α-SMA) was assayed by Western blot and immunofluorescent staining.

RESULTS

Renal Hyp content, HE, Masson's trichrome and PASM staining results and α-SMA expression confirmed development of HgCl2-induced RIF in rats. Oxidative stress markers GSH, GSH-Px and MDA confirmed oxidative stress in RIF rats. Compared with model rats, rats in Vit E group had lower kidney Hyp content (P<0.01). GSH and MDA contents decreased significantly in Vit E group compared with model group (P<0.01). The expressions of NF-κB and IκB had no significant difference among all groups (P>0.05). In Vit E group, the expressions of p-IκB and TNF-α decreased significantly compared with model group (P<0.01). The expression of α-SMA in Vit E group was also decreased significantly compared with model group (P<0.01).

CONCLUSION

Vit E has a protective effect on experimental RIF induced by HgCl(2) in rats and it is related to inhibition of lipid peroxidation, which involves blocking of NF-κB signaling pathway and the activation of cells producing extracellular matrix.

Fucosylated chondroitin sulfate attenuates renal fibrosis in animals submitted to unilateral ureteral obstruction: a P-selectin-mediated event?

Fibrosis is the end point of most renal diseases, and several glycosaminoglycans have been shown to attenuate this process. Marine invertebrate glycosaminoglycans with unique structures have opened the possibility to test these new compounds on renal fibrosis. The effect of a fucosylated chondroitin sulfate from an echinoderm marine species is reported with the use of a model of renal fibrosis in rats, termed unilateral ureteral obstruction. Animals were given 4 mg/kg body wt of fucosylated chondroitin sulfate intraperitoneally, once a day. After 14 days, their kidneys were examined by histological, immunohistochemical, and biochemical methods. Compared with control mice, collagen deposition decreased in the course of renal fibrosis in the animals receiving fucosylated chondroitin sulfate, as revealed by Sirius red staining and hydroxyproline content. The cellularity related to myofibroblasts and macrophages was also reduced, as was the production of transforming growth factor (TGF)-β. The glycosaminoglycan content increased in the renal interstitium of animals submitted to unilateral ureteral obstruction compared with the control contralateral kidney, mostly due to an increase of chondroitin sulfate content. Interestingly, no change in the pattern of glycosaminoglycan deposition was observed after administration of fucosylated chondroitin sulfate. Fibrosis induced by unilateral ureteral obstruction is attenuated in P-selectin-deficient mice, which also do not respond to the invertebrate glycosaminoglycan. In conclusion, fucosylated chondroitin sulfate attenuates renal fibrosis on a ureteral obstruction model in mice preponderantly through a P-selectin-mediated mechanism.

Novel systems biology insights using antifibrotic approaches for diabetic kidney disease

Although several interventions slow the progression of diabetic nephropathy, current therapies do not halt progression completely. Recent preclinical studies suggested that pirfenidone (PFD) prevents fibrosis in various diseases, but the mechanisms underlying its antifibrotic action are incompletely understood. To explore the therapeutic potential of PFD, we studied the PFD-treated db/db diabetic mouse kidney by liquid chromatography-tandem mass spectrometry proteomics. A total of 21 proteins unique to PFD-treated diabetic kidneys were identified. Analysis of gene ontology and protein-protein interactions of these proteins suggested that PFD may regulate RNA translation. Two key proteins involved in mRNA translation initiation and elongation were further evaluated and found to be regulated by PFD at the level of phosphorylation. In conclusion, insights from combining proteomics and bioinformatics improve the likelihood of rapid advancement of novel clinical therapies focused on reducing inflammation and fibrosis for diabetic complications.

Emerging concepts in cardiac matrix biologyThis article is one of a selection of papers published in a special issue on Advances in Cardiovascular Research

The cardiac extracellular matrix, far from being merely a static support structure for the heart, is now recognized to play central roles in cardiac development, morphology, and cell signaling. Recent studies have better shaped our understanding of the tremendous complexity of this active and dynamic network. By activating intracellular signal cascades, the matrix transduces myocardial physical forces into responses by myocytes and fibroblasts, affecting their function and behavior. In turn, cardiac fibroblasts and myocytes play active roles in remodeling the matrix. Coupled with the ability of the matrix to act as a dynamic reservoir for growth factors and cytokines, this interplay between the support structure and embedded cells has the potential to exert dramatic effects on cardiac structure and function. One of the clearest examples of this occurs when cell–matrix interactions are altered inappropriately, contributing to pathological fibrosis and heart failure. This review will examine some of the recent concepts that have emerged regarding exactly how the cardiac matrix mediates these effects, how our collective vision of the matrix has changed as a result, and the current state of attempts to pharmacologically treat fibrosis.

The cardiac fibroblast: therapeutic target in myocardial remodeling and failure

Cardiac fibroblasts play a central role in the maintenance of extracellular matrix in the normal heart and as mediators of inflammatory and fibrotic myocardial remodeling in the injured and failing heart. In this review, we evaluate the cardiac fibroblast as a therapeutic target in heart disease. Unique features of cardiac fibroblast cell biology are discussed in relation to normal and pathophysiological cardiac function. The contribution of cardiac fibrosis as an independent risk factor in the outcome of heart failure is considered. Candidate drug therapies that derive benefit from actions on cardiac fibroblasts are summarized, including inhibitors of angiotensin-aldosterone systems, endothelin receptor antagonists, statins, anticytokine therapies, matrix metalloproteinase inhibitors, and novel antifibrotic/anti-inflammatory agents. These findings point the way to future challenges in cardiac fibroblast biology and pharmacotherapy.

Effect of Pirfenidone on Apoptosis-Regulatory Genes in Chronic Cyclosporine Nephrotoxicity

BACKGROUND

: Apoptosis was shown to play a role in the progression of fibrosis in a chronic cyclosporine A (CsA) nephrotoxicity animal model. In addition, the antifibrotic molecule pirfenidone (PFD) was shown to ameliorate fibrosis in this model. We evaluated the role of PFD on the expression of apoptosis-regulatory genes in the kidneys of CsA-treated rats.

METHODS

: Rats were administered CsA 7.5 mg/kg per day, CsA+PFD (250 mg/kg/day), vehicle (VH), or VH+PFD, and sacrificed at 28 days. Physiologic and histologic changes were studied, and apoptosis was detected by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling stain. The mRNA expression of pro-apoptotic genes p53 and Fas-ligand was evaluated by quantitative polymerase chain reaction, and that of Bcl-xL, an anti-apoptotic gene, was evaluated by Northern blot analysis. In addition to mRNA expression, immunohistochemical studies of caspase 3 were performed.

RESULT

: PFD administration to CsA-treated rats significantly ameliorated nephrotoxicity. Apoptosis-positive cells were increased by CsA but significantly reduced by PFD treatment (68+/-19 vs. 3+/-1, P<0.01). In addition, PFD down-regulated the mRNA expression of CsA-induced p53 and Fas-ligand (P<0.01) and increased that of Bcl-xL, previously reduced by CsA (P<0.01). Finally, PFD significantly down-regulated caspase 3 expression, present mostly on renal tubular epithelial cells. None of these changes were observed in VH-treated rats.

CONCLUSION

: Whereas CsA favored the expression of pro-apoptotic genes, that effect was ameliorated by PFD. Because apoptosis can partly explain the loss of cells associated with fibrosis, the influence of PFD on apoptosis-regulatory genes in a manner that reduces apoptosis may explain some of its antifibrotic properties.

Pirfenidone treatment decreases transforming growth factor-beta1 and matrix proteins and ameliorates fibrosis in chronic cyclosporine nephrotoxicity

Chronic cyclosporine (CsA) nephrotoxicity is characterized by tubulointerstitial fibrosis. Pirfenidone (PFD) is a novel antifibrotic compound that was shown to prevent and even reverse fibrosis. The mechanism of action of PFD is unclear but involves inhibition of transforming growth factor-beta (TGF-beta). Salt-depleted rats were administered CsA, CsA + PFD, vehicle (VH) or VH + PFD and sacrificed at 28days. Physiologic and histologic changes were studied in addition to TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and biglycan mRNA expressions by Northern blot. TGF-beta1 immunohistochemistry was also performed. Treatment with PFD ameliorated CsA-induced fibrosis by about 50% (p < 0.05). CsA-induced decrease in creatinine clearance improved with PFD but the difference was not significant. TGF-beta1, PAI-1 and biglycan mRNA expressions increased with CsA (p < 0.05 vs. VH) but strikingly improved with PFD treatment (p < 0.05 vs. CsA), which brought the levels down to VH levels. PFD treatment also decreased TGF-beta1 protein expression by 80%. These results demonstrate that PFD can attenuate renal fibrosis in this model. PFD was associated with a decrease in TGF-beta1 expression, which, in turn, was associated with a decrease in matrix deposition. These experiments suggest that PFD can be clinically useful for preventing chronic CsA nephrotoxicity and may prove to be helpful in other progressive renal diseases.

Renal tubulointerstitial fibrosis. New thoughts on its development and progression

Current investigation of the pathogenesis of tubulointerstitial injury indicates that both interstitial fibroblasts and renal tubular epithelial cells promote extracellular matrix accumulation. Moreover, two peptides--TGF-beta and angiotensin II--produced locally or delivered in the circulation, appear to play a central role in renal fibrosis. Pharmacologic amelioration of renal fibrosis may require methods directed at multiple factors involved in the fibrotic process, including angiotensin II, TGF-beta, and the proliferation and activation of interstitial fibroblasts.

The role of tubulointerstitial injury in chronic renal failure

Progressive renal failure results from a triad of glomerulosclerosis, tubulointerstitial fibrosis and vascular sclerosis. The mechanisms by which tubules are injured, and by which the tubular epithelial cell then excites interstitial inflammation culminating in fibroblast activation and fibrosis have become increasingly understood. Most current methods to prevent progressive glomerulosclerosis would inherently prevent tubular injury and interstitial fibrosis. The behaviour and control of the renal fibroblast is being investigated, with the potential for direct interference with its functions.