Mechanistic connection between inflammation and fibrosis

TAK-242, a Toll-Like Receptor 4 Antagonist, Protects against Aldosterone-Induced Cardiac and Renal Injury

Cardiovascular and renal inflammation induced by Aldosterone (Aldo) plays an important role in the pathogenesis of hypertension and renal fibrosis. Toll-like receptor 4 (TLR4) signaling contributes to inflammatory cardiovascular and renal diseases, but its role in Aldo-induced hypertension and renal damage is not clear. In the current study, rats were treated with Aldo-salt combined with TAK-242 (a TLR4 signaling antagonist) for 4 weeks. Hemodynamic, cardiac and renal parameters were assayed at the indicated time. We found that Aldo-salt–treated rats present cardiac and renal hypertrophy and dysfunction. Cardiac and renal expression levels of TLR4 as well as levels of molecular markers attesting inflammation and fibrosis are increased by Aldo infusion, whereas the treatment of TAK-242 reverses these alterations. TAK-242 suppresses cardiac and renal inflammatory cytokines levels (TNF-a, IL-1β and MCP-1). Furthermore, TAK-242 inhibits hypertension, cardiac and renal fibrosis, and also attenuates the Aldo-induced Epithelial-Mesenchymal Transition (EMT). In experimental hyperaldosteronism, upregulation of TLR4 is correlated with cardiac and renal fibrosis and dysfunction, and a TLR4 signaling antagonist, TAK-242, can reverse these alterations. TAK-242 may be a therapeutic option for salt-sensitive hypertension and renal fibrosis.

Increased Expression of Connective Tissue Growth Factor (CTGF) in Multiple Organs After Exposure of Non-Human Primates (NHP) to Lethal Doses of Radiation

Exposure to sufficiently high doses of ionizing radiation is known to cause fibrosis in many different organs and tissues. Connective tissue growth factor (CTGF/CCN2), a member of the CCN family of matricellular proteins, plays an important role in the development of fibrosis in multiple organs. The aim of the present study was to quantify the gene and protein expression of CTGF in a variety of organs from non-human primates (NHP) that were previously exposed to potentially lethal doses of radiation. Tissues from non-irradiated NHP and NHP exposed to whole thoracic lung irradiation (WTLI) or partial-body irradiation with 5% bone marrow sparing (PBI/BM5) were examined by real-time quantitative reverse transcription PCR, western blot, and immunohistochemistry. Expression of CTGF was elevated in the lung tissues of NHP exposed to WTLI relative to the lung tissues of the non-irradiated NHP. Increased expression of CTGF was also observed in multiple organs from NHP exposed to PBI/BM5 compared to non-irradiated NHP; these included the lung, kidney, spleen, thymus, and liver. These irradiated organs also exhibited histological evidence of increased collagen deposition compared to the control tissues. There was significant correlation of CTGF expression with collagen deposition in the lung and spleen of NHP exposed to PBI/BM5. Significant correlations were observed between spleen and multiple organs on CTGF expression and collagen deposition, respectively, suggesting possible crosstalk between spleen and other organs. These data suggest that CTGF levels are increased in multiple organs after radiation exposure and that inflammatory cell infiltration may contribute to the elevated levels of CTGF in multiple organs.

Endogenous Inhibitors of Kidney Inflammation

Although inflammation is the physiological response to pathogen invasion and tissue damage, it can also be responsible for significant tissue damage. Therefore, the inflammatory response must be carefully regulated to prevent critical inflammatory damage to vital organs. Typically, local endogenous regulatory mechanisms adjust the magnitude of the response such that the injurious condition is resolved and homeostasis is mantained. Humoral mechanisms that restrain or inhibit inflammation include glucocorticoid hormones, anti-inflammatory cytokines such as IL-10 and transforming growth factor-β (TGF-β), and soluble cytokine receptors; other mediators facilitate tissue healing, like lipoxins and resolvins. There is growing evidence that inflammation plays a critical role in the development and progression of heart disease, cancer, stroke, diabetes, kidney diseases, sepsis, and several fibroproliferative disorders. Consequently, understanding the mechanisms that regulate inflammation may offer therapeutic targets for inhibiting the progression of several diseases. In this article, we review the significance of several novel endogenous anti-inflammatory mediators in the protection from kidney injury and the potential of these regulatory molecules as therapeutic targets for treatment of kidney inflammatory diseases.

Mechanisms of Kidney Injury in Lupus Nephritis - the Role of Anti-dsDNA Antibodies

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-tolerance, production of auto-antibodies and immune-mediated injury, resulting in damage accrual in multiple organs. Kidney involvement, termed lupus nephritis, is a major cause of morbidity and mortality that affects over half of the SLE population during the course of disease. The etiology of lupus nephritis is multifactorial and remains to be fully elucidated. Accumulating evidence suggests that in addition to forming immune complexes and triggering complement activation, anti-dsDNA antibodies contribute to the pathogenesis of lupus nephritis through binding, either directly or indirectly, to cross-reactive antigens or chromatin materials, respectively, to resident renal cells and/or extracellular matrix components, thereby triggering downstream cellular activation and proliferation as well as inflammatory and fibrotic processes. Several cross-reactive antigens that mediate anti-dsDNA antibody binding have been identified, such as annexin II and alpha-actinin. This review discusses the mechanisms through which anti-dsDNA antibodies contribute to immunopathogenesis in lupus nephritis. Corticosteroids combined with either mycophenolic acid (MPA) or cyclophosphamide is the current standard of care immunosuppressive therapy for severe lupus nephritis. This review also discusses recent data showing distinct effects of MPA and cyclophosphamide on inflammatory and fibrotic processes in resident renal cells.

Substitution between Aristolochia and Bryonia genus in North-Eastern Morocco: toxicological implications

ETHNOPHARMACOLOGICAL RELEVANCE

Although acknowledged as toxic herbs, Aristolochia species are still widely used worldwide. The aristolochic acids (AA) they contain can induce the so-called "aristolochic acid nephropathy", leading to renal fibrosis and upper urinary tract cancer. Traditional Moroccan medicine still often uses Aristolochia species under the vernacular name of Bereztem for the treatment of numerous ailments, notably cancer, diabetes or digestive tract disorders. As the botanical identity and renal toxicity of used species remain unexplored, the safety of patients may be threatened.

MATERIAL AND METHODS

Ethnopharmacological data were collected from herbalists from the provinces of Oujda and Berkane, located in North-Eastern Morocco. Samples of Bereztem were collected at herbalist shops and checked for their content in AA using TLC and LC-MS methods. The toxicity of crude methanolic extracts of each herb was assessed on a HK-2 cell-based in vitro model by measurement of the cell survival to evaluate cytotoxicity and by assessment of renal-specific toxicity via (i) the evaluation of genes (E-cadherin and α-smooth muscle actin) expression by RT-qPCR; (ii) the quantities of β-catenin and vimentin by immunofluorescence microscopy; (iii) the secretion of fibronectin; and (iv) the excretion of interleukin-6.

RESULTS

The survey indicated that, among 42 herbalists visited, 33 were retailers of Bereztem, which was generally sold as a cancer treatment. Botanical investigations revealed that Aristolochia longa was frequently substituted by Bryonia dioica, which was associated with a higher cytotoxicity. Parameters specific to renal toxicity were also found to be enhanced, as compared to Aristolochia baetica and A. longa: down-regulation of β-catenin and E-cadherin and up-regulation of vimentin and α-smooth muscle actin, and secretion of fibronectin and interleukin-6.

CONCLUSION

In accordance with the Moroccan regulations, the use of so-called Aristolochia species should be discontinued. On one hand, the correctly identified aristolochia contain nephrotoxic aristolochic acids; on the other hand, aristolochia are massively substituted in North-Eastern Morocco and adulterated by a well-known toxic herb, B. dioica. Our data indicate that the bryony renal toxicity may be deleterious in shorter time periods than aristolochia. Reinforced on-site controls are needed to remind herbalists and harvesters that these herbs should be prohibited.

Absence of nicotinic acetylcholine receptor α7 subunit amplifies inflammation and accelerates onset of fibrosis: an inflammatory kidney model

Inflammation is regulated by endogenous mechanisms, including anti-inflammatory cytokines, adenosine, and the nicotinic acetylcholine receptor α7 subunit (α7nAChR). We investigated the role of α7nAChR in protection against the progression of tissue injury in a model of severe, macrophage-mediated, cytokine-dependent anti-glomerular basement membrane (GBM) glomerulonephritis (GN), in α7nAChR-deficient (α7(-/-)) mice . At d 7 after the injection of anti-GBM antibody, kidneys from α7(-/-) mice displayed severe glomeruli (P < 0.0001) and tubulointerstitial lesions (P < 0.001) compared to kidneys from WT mice. An important finding was the presence of severe glomerulosclerosis in α7(-/-) mice in this early phase of the disease. Kidneys of α7(-/-) mice showed greater accumulation of inflammatory cells and higher expression of chemokines and cytokines than did those of WT mice. In addition, in α7(-/-) fibrotic kidneys, the expression of fibrin, collagen, TGF-β, and tissue inhibitor of metalloproteinase (TIMP)-2 increased, and the expression of TIMP3 declined. The increase in counterregulatory responses to inflammation in α7(-/-) nephritic kidneys did not compensate for the lack of α7nAChR. These findings indicate that α7nAChR plays a key role in regulating the inflammatory response in anti-GBM GN and that disruption of the endogenous protective α7nAChR amplifies inflammation to accelerate kidney damage and fibrosis.

Hydrogen Sulfide: A Therapeutic Candidate for Fibrotic Disease?

Fibrotic diseases including chronic kidney disease, liver cirrhosis, idiopathic pulmonary fibrosis, and chronic disease account for 45% mortality in the developed countries and pose a great threat to the global health. Many great targets and molecules have been reported to be involved in the initiation and/or progression of fibrosis, among which inflammation and oxidative stress are well-recognized modulation targets. Hydrogen sulfide (H₂S) is the third gasotransmitter with potent properties in inhibiting inflammation and oxidative stress in various organs. Recent evidence suggests that plasma H₂S level is decreased in various animal models of fibrotic diseases and supplement of exogenous H₂S is able to ameliorate fibrosis in the kidney, lung, liver, and heart. This leads us to propose that modulation of H₂S production may represent a promising therapeutic venue for the treatment of a variety of fibrotic diseases. Here, we summarize and discuss the current data on the role and underlying mechanisms of H₂S in fibrosis diseases related to heart, liver, kidney, and other organs.

Fibrosis progression according to epithelial-mesenchymal transition profile: a randomized trial of everolimus versus CsA

Markers of epithelial-mesenchymal transition (EMT) may identify patients at high risk of graft fibrogenesis who could benefit from early calcineurin inhibitor (CNI) withdrawal. In a randomized, open-label, 12-month trial, de novo kidney transplant patients received cyclosporine, enteric-coated mycophenolate sodium (EC-MPS) and steroids to month 3. Patients were stratified as EMT+ or EMT- based on month 3 biopsy, then randomized to start everolimus with half-dose EC-MPS (720 mg/day) and cyclosporine withdrawal (CNI-free) or continue cyclosporine with standard EC-MPS (CNI). The primary endpoint was progression of graft fibrosis (interstitial fibrosis/tubular atrophy [IF/TA] grade increase ≥1 between months 3-12) in EMT+ patients. 194 patients were randomized (96 CNI-free, 98 CNI); 153 (69 CNI-free, 84 CNI) were included in histological analyses. Fibrosis progression occurred in 46.2% (12/26) CNI-free EMT+ patients versus 51.6% (16/31) CNI EMT+ patients (p = 0.68). Biopsy-proven acute rejection (BPAR, including subclinical events) occurred in 25.0% and 5.1% of CNI-free and CNI patients, respectively (p < 0.001). In conclusion, early CNI withdrawal with everolimus initiation does not prevent interstitial fibrosis. Using this CNI-free protocol, in which everolimus exposure was relatively low and administered with half-dose EC-MPS, CNI-free patients were overwhelmingly under-immunosuppressed and experienced an increased risk of BPAR.

Calcitriol ameliorates renal damage in a pre-established proteinuria model

Proteinuria is critical in the tubulointerstitial changes that ultimately lead to renal insufficiency. Increased protein filtration has direct toxic effects on tubular epithelial cells, leading to epithelial mesenchymal transition (EMT) to a myofibroblast phenotype. Angiotensin II and transforming growth factor (TGF)-β1 are the main mediators of EMT. Calcitriol may exert a potential renoprotective effect by reducing the activity of the renin angiotensin system by suppressing renin gene expression and also by inhibiting the proinflammatory nuclear factor-κB pathway. The present study investigated the benefits of calcitriol treatment in a puromycin-induced protein-uric nephropathy model. Uninephrectomized adult male Wistar rats received intraperitoneal administration of a single dose of puromycin (100 mg/kg) or vehicle. After eight weeks, the animals were divided into two groups and received vehicle or calcitriol (0.5 μg/kg) for four weeks. The vehicle-treated, proteinuric rats developed progressive proteinuria and tubulointerstitial fibrosis after 12 weeks. Increased collagen deposition and fibrosis were significantly ameliorated by calcitriol treatment. Calcitriol was effective in preventing an increase in the EMT markers, α-smooth muscle actin and fibroblast-specific protein 1, reducing macrophage infiltration as evidenced by levels of ED-1. In addition, calcitriol increased the anti-inflammatory cytokine interleukin-10 and reduced the pro-oxidant p47 phox enzyme. These effects were paralleled by a reduction in TGF-β/Smad3 expression. Calcitriol may have therapeutic potential in the proteinuric nephropathy model used in the present study by inhibiting the TGF-β1 axis.

Chronic exposure to nanoparticulate TiO2 causes renal fibrosis involving activation of the Wnt pathway in mouse kidney

Chronic exposure to nano-TiO2 may induce renal fibrosis, and the mechanism of this process is not well understood. Therefore, in this study, mice were administered nano-TiO2 by intragastric feeding for 9 months, and the urinary levels of nephrotoxicity biomarkers, activation of the Wnt pathway, and markers of the epithelial-to-mesenchymal transition (EMT) in the kidneys were investigated. The findings suggested that exposure to nano-TiO2 increased the level of renal titanium accumulation, urinary levels of kidney injury molecule-1 (1.18 ± 0.13- to 3.60 ± 0.41-fold), clusterin (1.40 ± 0.16- to 5.14 ± 0.58-fold), and osteopontin (0.71 ± 0.08- to 2.41 ± 0.29-fold), and increased levels of renal inflammation and fibrosis. Furthermore, nano-TiO2 increased the level of expression of Wnt ligands (Wnt1, Wnt2, Wnt3, Wnt4, Wnt5a, Wnt6, Wnt7a, Wnt9a, Wnt10a, and Wnt11, 0.09 ± 0.02- to 4.84 ± 0.52-fold), Wnt receptors Frizzled (Fz1, Fz5, and Fz7, 0.37 ± 0.04- to 8.57 ± 0.91-fold), and coreceptors low-density lipoprotein receptor-related proteins 5 and 6 (0.73 ± 0.09- to 5.27 ± 0.56-fold) in the kidney. Wnt signaling components induced by nano-TiO2 were corroborated by decreased levels of expression of Wnt antagonist-related markers (Dkk1, Dkk2, Dkk3, Dkk4, and sFRP/FrzB, -0.06 ± 0.01- to -0.87 ± 0.09-fold) and increased levels of expression of Wnt target genes (Abcb1b, cyclin D1, and Myc, 0.03 ± 0.01- to 2.73 ± 0.28-fold) and EMT markers Colla1, Fn, Twist, and α-SMA (0.06 ± 0.02- to 5.80 ± 0.61-fold). These findings indicate that nano-TiO2 induced renal fibrosis that may be mediated via Wnt signaling.

KS370G, a caffeamide derivative, attenuates unilateral ureteral obstruction-induced renal fibrosis by the reduction of inflammation and oxidative stress in mice

Unilateral ureteral obstruction (UUO) is an established animal model used to study renal nephropathy. Caffeic acid phenethyl ester, a natural phenolic compound, possesses antifibrotic, anti-inflammation and anti-oxidative stress effects; however, rapid decomposition by esterases substantially decreases its bioavailability. The goal of this study was to investigate the beneficial effects of KS370G, a synthetic caffeamide derivative, on UUO-induced renal injury. Following the UUO, KS370G (10mg/kg) was administered by oral gavage once a day. Renal injury was analyzed at 14 days post-operation. Our results show that KS370G significantly attenuated collagen deposition in the obstructed kidney and inhibited UUO-induced renal fibrosis markers expression, including fibronectin, type I collagen, vimentin, and α-smooth muscle actin (α-SMA). KS370G significantly lowered the expression of renal inflammatory chemokines/adhesion molecules and monocyte cells marker (MCP-1, VCAM-1, ICAM-1 and CD11b). KS370G also reduced renal malondialdehyde levels and reversed the expression of renal antioxidant enzymes (SOD and catalase) after UUO. Furthermore, KS370G significantly inhibited UUO-induced elevated plasma AngII and TGF-β1 levels, TGF-β1 protein expression and Smad3 phosphorylation. These findings demonstrate that KS370G reduces renal obstructive nephropathy by possibly inhibiting AngII, TGF-β and Smad3 signaling pathways.

Nephroprotective effects of ferulic acid, Z-ligustilide and E-ligustilide isolated from Angelica sinensis against cisplatin toxicity in vitro

Cisplatin (CisPt), a chemotherapeutic drug applied against solid tumors, is highly detrimental to the kidney. The risk of acute kidney injury implies adequate patient hydration to ensure sufficient diuresis; this strategy, now implemented in clinical practice, remains however incompletely satisfactory. New pharmacological approaches relying on the discovery of bioactive compounds need to be developed. Based on previous studies reporting renoprotective activities for extracts of Angelica sinensis (Oliv.) Diels roots, three of its major active compounds, ferulic acid, Z-ligustilide and E-ligustilide, were investigated for possible alleviation of CisPt-induced nephrotoxicity. Five phenomena involved in acute kidney injury and subsequent fibrosis were investigated: (i) modulation of cell survival via reduction of the apoptosis rate; (ii) reduction of oxidative stress; (iii) improvement of tubular regeneration capacities through proliferation and migration; (iv) limitation of extracellular matrix and collagen deposition; and (v) prevention of the dedifferentiation processes via the β-catenin pathway. Ferulic acid emerged as the most potent compound for alleviating cell death and collagen deposition, and for enhancing cell regeneration capacities. It also partially inhibited the β-catenin pathway, but was ineffective in lowering oxidative stress. Z- and E-ligustilides, however, were effective for limiting the oxidative stress, but only moderately affected other parameters. Ferulic acid appears to be a promising nephroprotective drug lead deserving further preclinical investigation.

Differentiating Glomerular Inflammation from Fibrosis in a Bone Marrow Chimera for Rat Anti-Glomerular Basement Membrane Glomerulonephritis

BACKGROUND

Many types of glomerulonephritis (GN) undergo tandem connected phases: inflammation and fibrosis. Fibrosis in human GNs leads to irreversible end-stage disease. This study investigated how these 2 phases were controlled.

METHODS

Using a rat anti-glomerular basement membrane GN model, we established bone marrow (BM) chimeras between GN-resistant Lewis (LEW) and GN-susceptible Wistar Kyoto (WKY) rats. Glomerular inflammation and fibrosis were compared between chimeras.

RESULTS

LEW's BM to WKY chimeras with or without co-transfer of host WKY's T cells were GN-resistant. On the other hand, WKY's BM to LEW (LEW(WKY)) chimeras developed glomerular inflammation and albuminuria upon immunization. Quantitative analysis showed that the number and composition of inflammatory cells in glomeruli of immunized LEW(WKY) chimeras were similar to those in immunized WKY rats at their inflammatory peak. Thus, glomerular inflammation was controlled by BM-derived non-T cell populations. However, unlike WKY rats, LEW(WKY) rats did not develop fibrosis until the end of experiments (84 days) in spite of persistent inflammation and albuminuria.

CONCLUSION

Inflammation alone was not sufficient to trigger fibrosis, suggesting a critical role of glomerular cells in the fibrotic process. As LEW(WKY) chimera allows us to separate glomerular inflammation from fibrosis, this model provides a useful tool to study how fibrosis is initiated following inflammation.

A 3-biomarker-panel predicts renal outcome in patients with proteinuric renal diseases

BACKGROUND

Clinical and histological parameters are valid prognostic markers in renal disease, although they may show considerable interindividual variability and sometimes limited prognostic value. Novel molecular markers and pathways have the potential to increase the predictive prognostic value of the so called "traditional markers".

METHODS

Transcriptomics profiles from laser-capture microdissected proximal tubular epithelial cells from routine kidney biopsies were correlated with a chronic renal damage index score (CREDI), an inflammation score (INSCO), and clinical parameters. We used data from 20 renal biopsies with various proteinuric renal diseases with a median follow-up of 49 months (discovery cohort). For validation we performed microarrays from whole kidney biopsies from a second cohort consisting of 16 patients with a median follow-up time of 28 months (validation cohort).

RESULTS

562 genes correlated with the CREDI score and 285 genes correlated with the INSCO panel, respectively. 39 CREDI and 90 INSCO genes also correlated with serum creatinine at follow-up. After hierarchical clustering we identified 5 genes from the CREDI panel, and 10 genes from the INSCO panel, respectively, which showed kidney specific gene expression. After exclusion of genes, which correlated to each other by > 50% we identified VEGF-C from the CREDI panel and BMP7, THBS1, and TRIB1 from the INSCO panel. Traditional markers for chronic kidney disease progression and inflammation score predicted 44% of the serum creatinine variation at follow-up. VEGF-C did not further enhance the predictive value, but BMP7, THBS1 and TRIB1 together predicted 94% of the serum creatinine at follow up (p < 0.0001). The model was validated in a second cohort of patients yielding also a significant prediction of follow up creatinine (48%, p = 0.0115).

CONCLUSION

We identified and validated a panel of three genes in kidney biopsies which predicted serum creatinine at follow-up and therefore might serve as biomarkers for kidney disease progression.

FTY720 inhibits tubulointerstitial inflammation in albumin overload-induced nephropathy of rats via the Sphk1 pathway

AIM

FTY720, a new immunomodulatory drug with low cytotoxicity, is currently used to treat multiple sclerosis. In this study, we investigated the effects of FTY720 on inflammatory cell infiltration in albumin overload-induced nephropathy of rats.

METHODS

Male Wistar rats were subjected to right-side nephrectomy and divided into 3 groups. One week after the surgery, albumin overload (AO) group was treated with BSA (5 g·kg(-1)·d(-1), ip) for 9 weeks; AO+FTY720 group was given BSA (5 g·kg(-1)·d(-1), ip) plus FTY720 (0.5 g·kg(-1)·d(-1), ip) for 9 weeks; and control group received daily ip injection of equivalent volume of saline. All rats were killed 9 weeks after nephrectomy.

RESULTS

AO rats exhibited gradually increased urinary protein excretion accompanied by elevated urinary N-acetyl-β-O-glucosaminidase activity, and both reached their peak values at week 7. Furthermore, AO significantly increased lymphocytes and monocytes in circulation and the inflammatory cells recruited to tubulointerstitium, and the expression of inflammatory cytokines MCP-1, TNF-α and IL-6, as well as sphingosine 1-phosphate (S1P) receptors S1pr1 and S1pr3, and S1P-synthesizing enzyme sphingosine kinase 1 (Sphk1) in the kidney. Concomitant administration of FTY720 significantly attenuated all the AO-induced pathological changes.

CONCLUSION

FTY720 alleviates tubulointerstitium inflammation in an AO rat model of nephropathy via down-regulation of the Sphk1 pathway.

The α4β1 integrin and the EDA domain of fibronectin regulate a profibrotic phenotype in dermal fibroblasts

Prompt deposition of fibronectin-rich extracellular matrix is a critical feature of normal development and the host-response to injury. Fibronectin isoforms that include the EDA and EDB domains are prominent in these fibronectin matrices. We now report using human dermal fibroblast cultures that the EDA domain of fibronectin or EDA-derived peptides modeled after the C-C' loop promote stress fiber formation and myosin-light chain phosphorylation. These changes are accompanied by an increase in fibronectin synthesis and fibrillogenesis. These effects are blocked by pretreating cells with either siRNA or blocking antibody to the α4 integrin. Our data indicate that the interaction between the α4β1 integrin and the EDA domain of fibronectin helps to drive tissue fibrosis by promoting a contractile phenotype and an increase in fibronectin synthesis and deposition.

Formula optimization of the Jiashitang scar removal ointment and antiinflammatory compounds screening by NF-κB bioactivity-guided dual-luciferase reporter assay system

Inflammation plays a role in scar formation; therefore, decreasing inflammation benefits scar removal. Jiashitang scar removal ointment (JST) is a commercially available traditional Chinese medicinal formulation. It is composed of extracts from Carthamus tinctorius L. (Car), Rheum officinale Baill. (Rhe), Salvia miltiorrhiza Beg. (Sal), and Panax notoginseng (Burk.) F. H. Chen (Pan), which are all herbs with potent antiinflammatory activities. Our aims are to optimize the formula of JST and to elucidate its antiinflammatory active components. Response surface methodology was applied to optimize proportions of the four herb extracts. The antiinflammatory effects were evaluated using in vitro and in vivo models. To screen for active components in this formula, a bioactivity-based ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry analysis was performed. After optimization, the antiinflammatory effects of the new formula were significantly superior to the original one. Screening identified 13 active ingredients: a series of saffiomin, emodin, salvianolic acid, tanshinone, and triterpenoid saponin derivatives. These active ingredients were predicted to exert nuclear factor-κB inhibiting effects through MAPK, PI3K/AKT, and NIK-IKK pathways. In conclusion, the original formula was successfully optimized with more potent antiinflammatory activity. These methods can be applied to researches of other formulas.

Biomarkers in kidney fibrosis: are they useful?

With the escalating cost of monitoring and follow-up required in the care of patients with chronic kidney disease (CKD), biomarkers are increasingly being investigated for their utility in predicting patients most at risk of decline in renal function in order to rationalize and target care. Putative biomarkers have also emerged as treatment targets, with the potential to develop novel therapeutics. However, biomarker studies in CKD are largely derived from single-sample collections in observational or nested case-control studies that are suboptimal in study design, analyses, and end points relevant to confirm the utility of specific biomarkers. It has been demonstrated that biomarker expression may be modified by declining kidney function. Hence, their value in predicting future kidney dysfunction is limited. Therefore, understanding the nature, mechanism of action, and how specific biomarkers interact with the CKD disease process is a crucial step in defining the potential for biomarkers to predict outcome, or alternatively, develop as a therapeutic target. Unlike conventional risk factors that, albeit partly, enable us to distinguish an individual at risk of cardiovascular disease, biomarkers in patients with CKD may not be required to be modifiable either directly or indirectly in the disease process or by therapy. Reproducibility and prospective validation remain major challenges for the burgeoning number of purported biomarkers in patients with CKD. It is highly likely a combination of conventional and novel biomarkers will be needed to accurately predict the risk of end-stage kidney disease. This review will focus on recently identified biomarkers and their utility in predicting progressive kidney fibrosis.

Prostaglandin E2 EP1 receptor enhances TGF-β1-induced mesangial cell injury

Increasing evidence indicates that transforming growth factor-β1 (TGF-β1) is a pivotal mediator in the pathogenesis of renal fibrosis. Mesangial cells (MCs) are important for glomerular function under both physiological and pathological conditions. Studies have found that the expression level of prostaglandin E2 (PGE2) in MCs increases under high glucose conditions, that PGE2 affects the proliferation and hypertrophy of MCs mainly through the EP1 pathway, and that the proliferation of MCs and the accumulation of extracellular matrix are the main events leading to glomerular fibrosis. In this study, we investigated the effects and mechanisms of action of the EP1 receptor, which is induced by transforming growth factor (TGF)-β1, on the proliferation of mouse MCs, the accumulation of extracellular matrix and the expression of PGE2 synthase. Primary mouse glomerular MCs were isolated from EP1 receptor-deficient mice (EP1-/- mice, in which the EP1 receptor was knocked down) and wild-type (WT) mice (WT MCs). In our preliminary experiments, we found that cell proliferation, as well as the mRNA and protein expression of cyclin D1, proliferating cell nuclear antigen (PCNA), fibronectin (FN), collagen I (ColI), membrane-associated PGE2 synthase-1 (mPGES-1) and cyclooxygenase-2 (COX-2) in the WT MCs were significantly increased following treatment with 10 ng/ml TGF-β1 for 24 h. Compared with the WT MCs, following the knockdown of the EP1 gene, the TGF-β1-induced MC injury was markedly suppressed. The aforementioned changes were notably enhanced following treatment with the EP1 agonist, 17-phenyl trinor PGE2 ethyl amide. Additionally, TGF-β1 induced extracellular signal-regulated kinase (ERK) phosphorylation. We found that the TGF-β1-induced ERK phosphorylation was alleviated by EP1 knockdown and promoted by EP1 expression. These results suggest that the EP1 receptor plays a role in the proliferation of mouse MCs, in the accumulation of extracellular matrix and in the expression of mPGES-1 induced by TGF-β1. Its mechanisms of action are possibly related to the reinforcement of ERK phosphorylation.

Curcumin protects hearts from FFA-induced injury by activating Nrf2 and inactivating NF-κB both in vitro and in vivo

Obesity and increased free fatty acid (FFA) level are tightly linked, leading to the development of cardiovascular disorders. Curcumin is a natural product from Curcuma longa with multiple bioactivities and is known to have cardioprotective effects in several cellular and animal models. The current study was designed to evaluate the cardioprotective effects of curcumin and demonstrate the underlying mechanism in FFA-induced cardiac injury. Using cell culture studies and high fat in vivo model, we explored the mechanistic basis of anti-inflammatory and antioxidant activities of curcumin. We observed that palmitate (PA) treatment in cardiac derived H9C2 cells induced a marked increase in reactive oxygen species, inflammation, apoptosis and hypertrophy. All of these changes were effectively suppressed by curcumin treatment. In addition, oral administration of curcumin at 50mg/kg completely suppressed high fat diet-induced oxidative stress, inflammation, apoptosis, fibrosis, hypertrophy and tissue remodeling in mice. The beneficial actions of curcumin are closely associated with its ability to increase Nrf2 expression and inhibit NF-κB activation. Thus, both in vitro and in vivo studies showed a promising role of curcumin as a cardioprotective agent against palmitate and high fat diet mediated cardiac dysfunction. We indicated the regulatory roles of Nrf2 and NF-κB in obesity-induced heart injury, and suggested that they may be important therapeutic targets in the treatment of obesity-related disorders.

Semicarbazide-sensitive amine oxidase (SSAO) inhibition ameliorates kidney fibrosis in a unilateral ureteral obstruction murine model

Semicarbazide-sensitive amine oxidase (SSAO) is an enzyme known for its dual function in mediating inflammation and reactive oxygen species production. However, the role of SSAO inhibitors in limiting kidney fibrosis is unclear. We aimed to determine the effectiveness of a SSAO inhibitor (SSAOi; PXS4728A) as an antifibrotic agent using a 7-day unilateral ureteric obstruction (UUO) model of acute kidney fibrosis in 6- to 8-wk-old mice. The experimental groups were 1) Sham operated; 2) UUO; 3) UUO+SSAOi (2 mg/kg); 4) UUO+telmisartan, an angiotensin receptor blocker (3 mg/kg); and 5) UUO+SSAOi+telmisartan. Kidney tissue was analyzed for histological evidence of tubulointerstitial fibrosis, nitrotyrosine staining, and mRNA expression of markers associated with fibrosis and inflammation. Kidney SSAO activity was determined by radiometric [14C]benzylamine methodology. Our results show that SSAOi effectively suppresses UUO-mediated SSAO activity. Extracellular matrix markers, namely, fibronectin, collagen IV protein, and nitrotyrosine staining, were lower in UUO+SSAOi mice compared with untreated UUO mice. This was consistent with the attenuated mRNA expression of collagen IV and fibronectin. SSAOi effectively inhibited transforming growth factor-β1 (TGF-β1) and monocyte chemoattractant protein-1 (MCP-1) expression to a similar extent to that observed with telmisartan. Individually, SSAOi and telmisartan induced a reduction in interstitial leukocyte and macrophage accumulation. However, the combination of SSAOi and telmisartan was more effective at reducing inflammatory cell infiltration. These results demonstrate that SSAO inhibition significantly suppresses profibrotic and proinflammatory cytokine secretion, reduces oxidative stress, and limits inflammatory cell accumulation and extracellular matrix expression in an acute model of renal fibrosis.

Activation of the Nlrp3 inflammasome by mitochondrial reactive oxygen species: a novel mechanism of albumin-induced tubulointerstitial inflammation

Albuminuria is not only an important marker of chronic kidney disease but also a crucial contributor to tubulointerstitial inflammation (TIF). In this study, we determined whether activation of the Nlrp3 inflammasome is involved in albuminuria induced-TIF and the underlying mechanisms of inflammasome activation by mitochondrial reactive oxygen species (mROS). We established an albumin-overload induced rat nephropathy model characterised by albuminuria, renal infiltration of inflammatory cells, tubular dilation and atrophy. The renal expression levels of the Nlrp3 inflammasome, IL-1β and IL-18 were significantly increased in this animal model. In vitro, albumin time- and dose-dependently increased the expression levels of the Nlrp3 inflammasome, IL-1β and IL18. Moreover, the silencing of the Nlrp3 gene or the use of the caspase-1 inhibitor Z-VAD-fmk significantly attenuated the albumin-induced increase in IL-1β and IL-18 expression in HK2 cells. In addition, mROS generation was elevated by albumin stimulation, whereas the ROS scavenger N-acetyl-l-cysteine (NAC) inhibited Nlrp3 expression and the release of IL-1β and IL-18. In kidney biopsy specimens obtained from patients with IgA nephropathy, Nlrp3 expression was localised to the proximal tubular epithelial cells, and this result is closely correlated with the extent of proteinuria and TIF. In summary, this study demonstrates that albuminuria may serve as an endogenous danger-associated molecular pattern (DAMP) that stimulates TIF via the mROS-mediated activation of the cytoplasmic Nlrp3 inflammasome.

Tissue injury and hypoxia promote malignant progression of prostate cancer by inducing CXCL13 expression in tumor myofibroblasts

Prostate cancer (PC) is a slowly progressing malignancy that often responds to androgen ablation or chemotherapy by becoming more aggressive, acquiring a neuroendocrine phenotype, and undergoing metastatic spread. We found that B lymphocytes recruited into regressing androgen-deprived tumors by C-X-C motif chemokine 13 (CXCL13), a chemokine whose expression correlates with clinical severity, play an important role in malignant progression and metastatic dissemination of PC. We now describe how androgen ablation induces CXCL13 expression. In both allografted and spontaneous mouse PC, CXCL13 is expressed by tumor-associated myofibroblasts that are activated on androgen ablation through a hypoxia-dependent mechanism. The same cells produce CXCL13 after chemotherapy. Myofibroblast activation and CXCL13 expression also occur in the normal prostate after androgen deprivation, and CXCL13 is expressed by myofibroblasts in human PC. Hypoxia activates hypoxia-inducible factor 1 (HIF-1) and induces autocrine TGF-β signaling that promotes myofibroblast activation and CXCL13 induction. In addition to TGF-β receptor kinase inhibitors, myofibroblast activation and CXCL13 induction are blocked by phosphodiesterase 5 (PDE5) inhibitors. Both inhibitor types and myofibroblast immunodepletion block the emergence of castration-resistant PC in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model of spontaneous metastatic PC with neuroendocrine differentiation.

Cardiac and renal effects of atrasentan in combination with enalapril and paricalcitol in uremic rats

BACKGROUND/AIMS

The search for new therapies providing cardiorenal protection in chronic kidney disease (CKD) has led to treatments that combine conventional renin-angiotensin-aldosterone-system inhibitors with other drugs that exhibit potential in disease management.

METHODS

In rats made uremic by renal ablation, we examined the effects of addition of the endothelin-A receptor antagonist atrasentan to a previously examined combination of enalapril (angiotensin converting enzyme inhibitor) and paricalcitol (vitamin D receptor activator) on cardiac and renal parameters. The effects of the individual and combined drugs were examined after a 3-month treatment.

RESULTS

A decrease in systolic blood pressure, serum creatinine and proteinuria, and improvement of renal histology in uremic rats were attributed to enalapril and/or paricalcitol treatment; atrasentan alone had no effect. In heart tissue, individual treatment with the drugs blunted the increase in cardiomyocyte size, and combined treatment additively decreased cardiomyocyte size to normal levels. Perivascular fibrosis was blunted in uremic control rats with atrasentan or enalapril treatment.

CONCLUSIONS

We found distinct cardiac and renal effects of atrasentan. Combination treatment with atrasentan, enalapril and paricalcitol provided positive effects on cardiac remodeling in uremic rats, whereas combination treatment did not offer further protective effects on blood pressure, proteinuria or renal histology.

Renal expression of advanced oxidative protein products predicts progression of renal fibrosis in patients with IgA nephropathy

Predicting the risk of disease progression in IgA nephropathy (IgAN) remains a challenge. This study was conducted to test the hypothesis that renal accumulation of advanced oxidized protein products (AOPPs) is an early predictor for renal progression in IgAN. This was a single-center prospective cohort study. One hundred IgAN patients with eGFR>80 ml/min/1.73 m(2) were enrolled. Seventy-seven patients were followed for a mean of 4.2 years, and 30 patients received repeat renal biopsy at a mean of 42 months after diagnosis. The outcomes were the progression of renal fibrosis and rapid progression of CKD (>5 ml/min/1.73 m(2)/year) during follow-up. Immunoreactivity of AOPPs was detected predominantly in tubular epithelial cells and co-localized with expression of TGF-β1 and angiotensin II. Renal staining score of AOPPs at diagnosis was associated with the level of tissue cellular inflammation. Accumulation of AOPPs, particularly in interstitial-infiltrating cells, was negatively correlated with changes of eGFR during follow-up; those with expression scores greater than the median at diagnosis had significantly higher incidences of rapid decline of eGFR compared with those with the score less than or equal to the median. For patients who received repeat renal biopsy, renal AOPP levels greater than the median at diagnosis were associated with increase in renal fibrosis index at repeat biopsy. After multivariate adjustment, renal AOPP expression was an independent predictor for progression of renal fibrosis and rapid decline of eGFR. Taken together, these results demonstrate that renal AOPPs might be a predictor, detectable at the time of diagnosis, for renal progression in patients with early stage IgAN.

Vitamin D in inflammatory diseases

Changes in vitamin D serum levels have been associated with inflammatory diseases, such as inflammatory bowel disease (IBD), rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis (MS), atherosclerosis, or asthma. Genome- and transcriptome-wide studies indicate that vitamin D signaling modulates many inflammatory responses on several levels. This includes (i) the regulation of the expression of genes which generate pro-inflammatory mediators, such as cyclooxygenases or 5-lipoxygenase, (ii) the interference with transcription factors, such as NF-κB, which regulate the expression of inflammatory genes and (iii) the activation of signaling cascades, such as MAP kinases which mediate inflammatory responses. Vitamin D targets various tissues and cell types, a number of which belong to the immune system, such as monocytes/macrophages, dendritic cells (DCs) as well as B- and T cells, leading to individual responses of each cell type. One hallmark of these specific vitamin D effects is the cell-type specific regulation of genes involved in the regulation of inflammatory processes and the interplay between vitamin D signaling and other signaling cascades involved in inflammation. An important task in the near future will be the elucidation of the regulatory mechanisms that are involved in the regulation of inflammatory responses by vitamin D on the molecular level by the use of techniques such as chromatin immunoprecipitation (ChIP), ChIP-seq, and FAIRE-seq.

Beyond tissue injury-damage-associated molecular patterns, toll-like receptors, and inflammasomes also drive regeneration and fibrosis

Tissue injury initiates an inflammatory response through the actions of immunostimulatory molecules referred to as damage-associated molecular patterns (DAMPs). DAMPs encompass a group of heterogenous molecules, including intracellular molecules released during cell necrosis and molecules involved in extracellular matrix remodeling such as hyaluronan, biglycan, and fibronectin. Kidney-specific DAMPs include crystals and uromodulin released by renal tubular damage. DAMPs trigger innate immunity by activating Toll-like receptors, purinergic receptors, or the NLRP3 inflammasome. However, recent evidence revealed that DAMPs also trigger re-epithelialization upon kidney injury and contribute to epithelial-mesenchymal transition and, potentially, to myofibroblast differentiation and proliferation. Thus, these discoveries suggest that DAMPs drive not only immune injury but also kidney regeneration and renal scarring. Here, we review the data from these studies and discuss the increasingly complex connection between DAMPs and kidney diseases.

The Interplay between inflammation and fibrosis in kidney transplantation

Serial surveillance renal allograft biopsies have shown that early subclinical inflammation constitutes a risk factor for the development of interstitial fibrosis. More recently, it has been observed that persistent inflammation is also associated with fibrosis progression and chronic humoral rejection, two histological conditions associated with poor allograft survival. Treatment of subclinical inflammation with steroid boluses prevents progression of fibrosis and preserves renal function in patients treated with a cyclosporine-based regimen. Subclinical inflammation has been reduced after the introduction of tacrolimus based regimens, and it has been shown that immunosuppressive schedules that are effective in preventing acute rejection and subclinical inflammation may prevent the progression of fibrosis and chronic humoral rejection. On the other hand, minimization protocols are associated with progression of fibrosis, and noncompliance with the immunosuppressive regime constitutes a major risk factor for chronic humoral rejection. Thus, adequate immunosuppressive treatment, avoiding minimization strategies and reinforcing educational actions to prevent noncompliance, is at present an effective approach to combat the progression of fibrosis.

The role of uric acid in kidney fibrosis: experimental evidences for the causal relationship

Hyperuricemia is a common finding in chronic kidney disease due to decreased uric acid clearance. The role of uric acid as a risk factor for chronic kidney disease has been largely debated, and recent studies suggested a role of uric acid in the causation and progression of kidney fibrosis, a final common pathway in chronic kidney disease. Uric acid and xanthine oxidase may contribute to kidney fibrosis mainly by inducing inflammation, endothelial dysfunction, oxidative stress, and activation of the renin-angiotensin system. Besides, hyperuricemia induces alterations in renal hemodynamics via afferent arteriolopathy and contributes to the onset and progression of kidney fibrosis. Xanthine oxidase inhibitors may prevent kidney damage via lowering uric acid and/or inhibiting xanthine oxidase. However, there is still no sufficient evidence from interventional clinical researches supporting the causal relationship between uric acid and kidney fibrosis. The effect and role of xanthine oxidase inhibitors in preventing kidney fibrosis and chronic kidney disease progression must be further explored by performing future large scale clinical trials.

Mizoribine ameliorates renal injury and hypertension along with the attenuation of renal caspase-1 expression in aldosterone-salt-treated rats

Aldosterone-salt treatment induces not only hypertension but also extensive inflammation that contributes to fibrosis in the rat kidney. However, the mechanism underlying aldosterone-salt-induced renal inflammation remains unclear. Pyroptosis has recently been identified as a new type of cell death that is accompanied by the activation of inflammatory cytokines. We hypothesized that aldosterone-salt treatment could induce inflammation through pyroptosis and that mizoribine, an effective immunosuppressant, would ameliorate the renal inflammation that would otherwise cause renal fibrosis. Ten days after recovery from left uninephrectomy, rats were given drinking water with 1% sodium chloride. The animals were divided into three groups (n = 7 per group): (1) vehicle infusion group, (2) aldosterone infusion group, or (3) aldosterone infusion plus oral mizoribine group. Aldosterone-salt treatment increased the expression of the nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing 3 and caspase-1, and also increased the number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells. However, the oral administration of mizoribine attenuated these alterations. Furthermore, mizoribine inhibited hypertension and renal fibrosis, and also attenuated the aldosterone-induced expression of serum/glucocorticoid-regulated kinase and α epithelial sodium channel. These results suggest that caspase-1 activation plays an important role in the development of inflammation induced by aldosterone-salt treatment and that it functions as an anti-inflammatory strategy that protects against renal injury and hypertension.

Activation of platelet-activating factor receptor exacerbates renal inflammation and promotes fibrosis

Platelet-activating factor (PAF) is a lipid mediator with important pro-inflammatory effects, being synthesized by several cell types including kidney cells. Although there is evidence of its involvement in acute renal dysfunction, its role in progressive kidney injury is not completely known. In the present study, we investigated the role of PAF receptor (PAFR) in an experimental model of chronic renal disease. Wild-type (WT) and PAFR knockout (KO) mice underwent unilateral ureter obstruction (UUO), and at kill time, urine and kidney tissue was collected. PAFR KO animals compared with WT mice present: (a) less renal dysfunction, evaluated by urine protein/creatinine ratio; (b) less fibrosis evaluated by collagen deposition, type I collagen, Lysyl Oxidase-1 (LOX-1) and transforming growth factor β (TGF-β) gene expression, and higher expression of bone morphogenetic protein 7 (BMP-7) (3.3-fold lower TGF-β/BMP-7 ratio); (c) downregulation of extracellular matrix (ECM) and adhesion molecule-related machinery genes; and (d) lower levels of pro-inflammatory cytokines. These indicate that PAFR engagement by PAF or PAF-like molecules generated during UUO potentiates renal dysfunction and fibrosis and might promote epithelial-to-mesenchymal transition (EMT). Also, early blockade of PAFR after UUO leads to a protective effect, with less fibrosis deposition. In conclusion, PAFR signaling contributes to a pro-inflammatory environment in the model of obstructive nephropathy, favoring the fibrotic process, which lately will generate renal dysfunction and progressive organ failure.

Lignans from the bark of Eucommia ulmoides inhibited Ang II-stimulated extracellular matrix biosynthesis in mesangial cells

Background

Tree bark of Eucommia ulmoides Oliv., (commonly well-known as “Du-zhong” in China), has been used to treat hypertension, hypercholesterolemia, hyperglycemia, hepatic fibrosis and renal injury. This study aims to investigate the effects of lignans extracted from the bark of Eucommia ulmoides Oliv. on Ang II-induced proliferation and extracellular matrix biosynthesis in rat mesangial cells.

Methods

Rat mesangial cells (RMCs) were cultured in vitro and divided into six groups (control, Ang II, losartan, and low, middle and high concentration lignans groups). RMC proliferation was measured by MTT assay. RT-qPCR and western blotting were used to detect mRNA and protein expression of collagen type I (Col I), collagen type III (Col III), collagen type IV (Col IV), fibronectin and aldose reductase (AR).

Results

Cellular proliferation induced by Ang II was significantly suppressed by Eucommia lignans of different concentrations (P = 0.034, P < 0.001, and P < 0.001). Treatment of cells with Ang II increased Col I, Col III, Col IV, and fibronectin mRNA expression, which was observed at the protein level (P < 0.001, P < 0.001, P = 0.004, and P = 0.004, respectively). The increased mRNA expression and protein levels of Col I, Col III, Col IV, and fibronectin were diminished remarkably with by treatment Eucommia lignans, and elevated AR expression stimulated by Ang II was significantly inhibited by Eucommia lignans.

Conclusions

Eucommia lignans (Du-zhong) inhibited Ang II-stimulated extracellular matrix biosynthesis in mesangial cells.

Sphingosine-1-phosphate acts as a key molecule in the direct mediation of renal fibrosis

The major sphingolipid metabolite, sphingosine‐1‐phosphate (S1P), has important biological functions. S1P serves as a ligand for a family of five G‐protein‐coupled receptors with distinct signaling pathways regulating important biological pathways. S1P induces renal fibrosis through an inflammatory pathway. However, its direct fibrosis‐inducing effect on the kidney has not been shown. The role of S1P as a direct mediator of renal fibrosis was investigated in normal rat kidney interstitial fibroblast (NRK‐49F) cells (in vitro) and kidneys of a unilateral ureteral obstruction (UUO) mouse model (in vivo). To clarify the role of S1P in renal fibrosis, we adopted nude UUO mice with immune response deficits. NRK‐49F cells were stimulated with various concentrations of exogenous S1P and FTY720 (a S1P receptor agonist) or N,N‐dimethylsphingosine (DMS; a sphingosine kinase inhibitor). C57BL6 and nude UUO mice were pretreated with FTY720, DMS, or saline. Expression levels of alpha‐smooth muscle actin (a‐SMA), E‐cadherin, collagen type 1 (COL1), collagen type 4 (COL4), tissue inhibitor of matrix metalloproteinase‐1 (TIMP1), and plasminogen activator inhibitor‐1 (PAI1) were examined. S1P stimulated fibrosis in NRK‐49F cells and UUO mice. Increased a‐SMA, COL1, COL4, TIMP1, and PAI1 and decreased E‐cadherin expression levels were observed in both the S1P‐stimulated cells and UUO mice. Nude UUO mouse kidneys expressed fibrotic markers. Fibrotic changes were successfully induced in both UUO and nude UUO mice, evident through prominent fibronectin and COL1 staining. These S1P‐induced fibrotic changes were suppressed by FTY720 and DMS both in vitro and in vivo. Thus, S1P essentially and directly mediates renal fibrosis.

Sphingosine‐1‐phosphate (S1P) stimulated fibrosis both in vitro and in vivo. Fibrotic changes were successfully induced in both unilateral ureteral obstruction (UUO) and nude mice with UUO. These results suggest that S1P is a pivotal fibrotic mediator in renal fibrosis that acts, in part, through direct fibrotic effects.

New drug therapies for COPD

Clinical trials with new drugs for chronic obstructive pulmonary disease (COPD) have been performed. Viruses exacerbate COPD and bacteria may play a part in severe COPD; therefore, antibiotic and antiviral approaches have a sound rationale. Antiinflammatory approaches have been studied. Advances in understanding the molecular basis of other processes have resulted in novel drugs to target reactive oxidant species, mucus, proteases, fibrosis, cachexia, and muscle wasting, and accelerated aging. Studies with monoclonal antibodies have been disappointing, highlighting the tendency for infections and malignancies during treatment. Promising future directions are lung regeneration with retinoids and stem cells.

Hydrogen sulfide inhibits the renal fibrosis of obstructive nephropathy

Hydrogen sulfide has recently been found decreased in chronic kidney disease. Here we determined the effect and underlying mechanisms of hydrogen sulfide on a rat model of unilateral ureteral obstruction. Compared with normal rats, obstructive injury decreased the plasma hydrogen sulfide level. Cystathionine-β-synthase, a hydrogen sulfide-producing enzyme, was dramatically reduced in the ureteral obstructed kidney, but another enzyme cystathionine-γ-lyase was increased. A hydrogen sulfide donor (sodium hydrogen sulfide) inhibited renal fibrosis by attenuating the production of collagen, extracellular matrix, and the expression of α-smooth muscle actin. Meanwhile, the infiltration of macrophages and the expression of inflammatory cytokines including interleukin-1β, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in the kidney were also decreased. In cultured kidney fibroblasts, a hydrogen sulfide donor inhibited the cell proliferation by reducing DNA synthesis and downregulating the expressions of proliferation-related proteins including proliferating cell nuclear antigen and c-Myc. Further, the hydrogen sulfide donor blocked the differentiation of quiescent renal fibroblasts to myofibroblasts by inhibiting the transforming growth factor-β1-Smad and mitogen-activated protein kinase signaling pathways. Thus, low doses of hydrogen sulfide or its releasing compounds may have therapeutic potentials in treating chronic kidney disease.

Protective role of JAK/STAT signaling against renal fibrosis in mice with unilateral ureteral obstruction

Inflammation is involved in renal fibrosis, a final common pathway for kidney diseases. To clarify how JAK/STAT/SOCS system was involved in renal fibrosis, UUO was induced in BALB/c or SOCS3(+/-) mice in the presence or absence of JAK inhibitor-incorporated nanoparticle (pyridine6-PGLA). UUO increased pSTAT3 and subsequently elevated SOCS3 levels in the obstructed kidneys. pSTAT3 levels were further increased in SOCS3(+/-) mice. UUO-induced renal fibrosis was markedly suppressed in SOCS3(+/-) mice, while it was aggravated by pre-treatment with pyridine6-PGLA. Although there were no differences in renal mRNA levels of TGF-β and collagens between wild and SOCS3(+/-) mice, MMP-2 activity was enhanced in SOCS3(+/-) UUO mice. Activated MMP-2 was completely suppressed by pyridine6-PGLA-pre-treatment. TNF-α one of JAK/STAT activators, increased pSTAT3 levels and subsequently induced MMP-2 activation in proximal tubular cells. These results suggest that JAK/STAT3 signaling may play a role in repair process of renal fibrosis in UUO partly via MMP-2 activation.

Protective effects of schizandrin and schizandrin B towards cisplatin nephrotoxicity in vitro

Renal proximal tubular epithelial cells are the main targets of toxic drugs such as cisplatin (CisPt), an alkylating agent indicated for the treatment of solid organ tumors. Current techniques aiming at reducing nephrotoxicity in patients receiving CisPt are still not satisfactory as they can only partially prevent acute kidney injury. New nephroprotective strategies remain to be developed. In the present in vitro study, schizandrin (Schi) and schizandrin B (Schi B), major phytochemicals from Schisandra chinensis (Turcz.) Baill. fruits, were tested on HK-2 cells along four processes that could help alleviate CisPt toxicity. Results indicated that: (i) both Schi and Schi B enhanced cell survival via reducing apoptosis rate; (ii) only Schi showed moderate effects towards modulation of regeneration capacities of healthy cells; (iii) both Schi and Schi B limited extracellular matrix deposition; and (iv) both compounds could help preventing dedifferentiation processes via the β-catenin pathway. Schi and Schi B present promising activities for future development of protective agents against CisPt nephrotoxicity.

TNF-related weak inducer of apoptosis (TWEAK) promotes kidney fibrosis and Ras-dependent proliferation of cultured renal fibroblast

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) regulates apoptosis, proliferation and inflammation in renal epithelial cells and plays a role in acute kidney injury. However, there is little information on the chronic effects of TWEAK. We hypothesized that TWEAK may influence renal fibrosis and regulate kidney fibroblast biology, in part, through Ras pathway. We studied a chronic model of experimental unilateral ureteral obstruction in wild type and TWEAK deficient mice, and a murine model of systemic TWEAK overexpression. TWEAK actions were also explored in cultured renal and embryonic fibroblasts. TWEAK and TWEAK receptor expression was increased in the obstructed kidneys. The absence of TWEAK decreased early kidney tubular damage, inflammatory infiltrates and myofibroblast number. TWEAK deficient mice had decreased renal fibrosis 21days after obstruction, as assessed by extracellular matrix staining. In mice without prior underlying kidney disease, systemic overexpression of TWEAK induced kidney inflammation and fibrosis. In cultured fibroblasts, TWEAK induced proliferation through activation of the Ras/ERK pathway. TWEAK also activated nuclear factor κB (NFκB)-dependent inflammatory chemokine production in murine renal fibroblasts. In conclusion, lack of TWEAK reduces renal fibrosis in a model of persistent kidney insult and overexpression of TWEAK led to renal fibrosis. TWEAK actions on renal fibroblasts may contribute to the in vivo observations, as TWEAK promotes inflammatory activity and proliferation in fibroblast cultures.

Danger control programs cause tissue injury and remodeling

Are there common pathways underlying the broad spectrum of tissue pathologies that develop upon injuries and from subsequent tissue remodeling? Here, we explain the pathophysiological impact of a set of evolutionary conserved danger control programs for tissue pathology. These programs date back to the survival benefits of the first multicellular organisms upon traumatic injuries by launching a series of danger control responses, i.e., 1. Haemostasis, or clotting to control bleeding; 2. Host defense, to control pathogen entry and spreading; 3. Re-epithelialisation, to recover barrier functions; and 4. Mesenchymal, to repair to regain tissue stability. Taking kidney pathology as an example, we discuss how clotting, inflammation, epithelial healing, and fibrosis/sclerosis determine the spectrum of kidney pathology, especially when they are insufficiently activated or present in an overshooting and deregulated manner. Understanding the evolutionary benefits of these response programs may refine the search for novel therapeutic targets to limit organ dysfunction in acute injuries and in progressive chronic tissue remodeling.

Lipopolysaccharide induces a fibrotic-like phenotype in endothelial cells

Endothelial dysfunction is crucial in endotoxaemia-derived sepsis syndrome pathogenesis. It is well accepted that lipopolysaccharide (LPS) induces endothelial dysfunction through immune system activation. However, LPS can also directly generate actions in endothelial cells (ECs) in the absence of participation by immune cells. Although interactions between LPS and ECs evoke endothelial death, a significant portion of ECs are resistant to LPS challenge. However, the mechanism that confers endothelial resistance to LPS is not known. LPS-resistant ECs exhibit a fibroblast-like morphology, suggesting that these ECs enter a fibrotic programme in response to LPS. Thus, our aim was to investigate whether LPS is able to induce endothelial fibrosis in the absence of immune cells and explore the underlying mechanism. Using primary cultures of ECs and culturing intact blood vessels, we demonstrated that LPS is a crucial factor to induce endothelial fibrosis. We demonstrated that LPS was able and sufficient to promote endothelial fibrosis, in the absence of immune cells through an activin receptor-like kinase 5 (ALK5) activity-dependent mechanism. LPS-challenged ECs showed an up-regulation of both fibroblast-specific protein expression and extracellular matrix proteins secretion, as well as a down-regulation of endothelial markers. These results demonstrate that LPS is a crucial factor in inducing endothelial fibrosis in the absence of immune cells through an ALK5-dependent mechanism. It is noteworthy that LPS-induced endothelial fibrosis perpetuates endothelial dysfunction as a maladaptive process rather than a survival mechanism for protection against LPS. These findings are useful in improving current treatment against endotoxaemia-derived sepsis syndrome and other inflammatory diseases.

Kidney transplants with progressing chronic diseases express high levels of acute kidney injury transcripts

We previously reported that kidney transplants with early acute injury express transcripts indicating injury repair--the acute kidney injury signal. This study investigated the significance of this signal in transplants with other conditions, including rejection and recurrent disease. The injury signal was elevated in biopsies in many different conditions, including T cell-mediated rejection and potentially progressive diseases such as antibody-mediated rejection and glomerulonephritis. A high injury signal correlated with poor function and with inflammation in areas of fibrosis, but not with fibrosis without inflammation. In multivariate survival analysis, the injury signal in late kidney transplant biopsies strongly predicted future graft loss, similar to a published molecular risk score derived in late kidneys. Indeed, the injury signal shared many individual transcripts with the risk score, e.g. ITGB6, VCAN, NNMT. The injury signal was a better predictor of future graft loss than fibrosis, inflammation or expression of collagen genes. Thus the acute injury signal, first defined in early reversible injury, is present in many diseases as a reflection of parenchymal distress, where its significance is dictated by the inducing insult, i.e. treatable/self-limited versus untreatable and sustained. Progression in troubled transplants is primarily a function of ongoing parenchymal injury by disease, not fibrogenesis.

Diabetic nephropathy: the role of inflammation in fibroblast activation and kidney fibrosis

Kidney disease associated with diabetes mellitus is a major health problem worldwide. Although established therapeutic strategies, such as appropriate blood glucose control, blood pressure control with renin-angiotensin system blockade, and lipid lowering with statins, are used to treat diabetes, the contribution of diabetic end-stage kidney disease to the total number of cases requiring hemodialysis has increased tremendously in the past two decades. Once renal function starts declining, it can result in a higher frequency of renal and extra-renal events, including cardiovascular events. Therefore, slowing renal function decline is one of the main areas of focus in diabetic nephropathy research, and novel strategies are urgently needed to prevent diabetic kidney disease progression. Regardless of the type of injury and etiology, kidney fibrosis is the commonly the final outcome of progressive kidney diseases, and it results in significant destruction of normal kidney structure and accompanying functional deterioration. Kidney fibrosis is caused by prolonged injury and dysregulation of the normal wound-healing process in association with excess extracellular matrix deposition. Kidney fibroblasts play an important role in the fibrotic process, but the origin of the fibroblasts remains elusive. In addition to the activation of residential fibroblasts, other important sources of fibroblasts have been proposed, such as pericytes, fibrocytes, and fibroblasts originating from epithelial-to-mesenchymal and endothelial-to-mesenchymal transition. Inflammatory cells and cytokines play a vital role In the process of fibroblast activation. In this review, we will analyze the contribution of inflammation to the process of tissue fibrosis, the type of fibroblast activation and the therapeutic strategies targeting the inflammatory pathways in an effort to slow the progression of diabetic kidney disease.

TGF-β1-containing exosomes from injured epithelial cells activate fibroblasts to initiate tissue regenerative responses and fibrosis

Hypoxia is associated with tissue injury and fibrosis but its functional role in fibroblast activation and tissue repair/regeneration is unknown. Using kidney injury as a model system, we demonstrate that injured epithelial cells produce an increased number of exosomes with defined genetic information to activate fibroblasts. Exosomes released by injured epithelial cells promote proliferation, α-smooth muscle actin expression, F-actin expression, and type I collagen production in fibroblasts. Fibroblast activation is dependent on exosomes delivering TGF-β1 mRNA among other yet to be identified moieties. This study suggests that TGF-β1 mRNA transported by exosomes constitutes a rapid response to initiate tissue repair/regenerative responses and activation of fibroblasts when resident parenchyma is injured. The results also inform potential utility of exosome-targeted therapies to control tissue fibrosis.

TGF expression and macrophage accumulation in atherosclerotic renal artery stenosis

BACKGROUND AND OBJECTIVES

Atherosclerotic renal artery stenosis (ARAS) reduces renal blood flow and is a potential cause of chronic kidney injury, yet little is known regarding inflammatory pathways in this disorder in human participants. This study aimed to examine the hypothesis that reduced renal blood flow (RBF) in ARAS would be associated with tissue TGF-β activation and inflammatory cell accumulation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This cross-sectional study of ARAS of varying severity compared transjugular biopsy specimens in patients with ARAS (n=12, recruited between 2008 and 2012) with tissue from healthy kidney donors (n=15) and nephrectomy specimens from individuals with total vascular occlusion (n=65). ARAS patients were studied under controlled conditions to measure RBF by multidetector computed tomography and tissue oxygenation by blood oxygen level-dependent magnetic resonance imaging.

RESULTS

Compared with the nonstenotic contralateral kidneys, RBF was reduced in poststenotic kidneys (242±149 versus 365+174 ml/min; P<0.01) as was single-kidney GFR (28±17 versus 41±19 ml/min; P<0.01), whereas cortical and medullary oxygenation were relatively preserved. Tissue TGF-β immunoreactivity was higher in ARAS patients compared with those with both normal kidneys and those with total occlusion (mean score 2.4±0.7 versus 1.5+1.1 in the nephrectomy group and versus 0±0 in donors; P<0.01). By contrast, the number of CD68+ macrophages was higher with greater disease severity (from 2.2±2.7 in normal to 22.4±18 cells/high-power field in nephrectomy samples; P<0.001).

CONCLUSIONS

The results of this study indicate robust stimulation of TGF-β associated with macrophage infiltration within the human kidney with vascular occlusive disease.