Role of bone morphogenetic protein-7 in renal fibrosis

Andrographolide suppresses fibrogenic phenotype of chondrocytes and ameliorates osteoarthritis by regulating miR-137/BMP7 axis

Background

Pathogenic degeneration of cartilage and the generation of fibrotic cartilage are crucial characteristics linked to the progression of osteoarthritis (OA). The current research aims to explore the potential function of the miR-137/BMP7 pathway in regulating the fibrogenic transition of chondrocytes associated with OA, as well as assess the therapeutic potential of andrographolide.

Methods

Samples of cartilage from the knees of patients with OA and individuals without OA were gathered to investigate the expression patterns of miR-137, BMP7, and markers associated with fibrosis. A cell model using primary chondrocytes stimulated with interleukin (IL)-1β was developed to study the involvement of the miR-137/BMP7 axis during the fibrogenic transition of these cells. Additionally, we utilized an animal model of OA in order to assess the beneficial effects of the anti-inflammatory natural compound andrographolide on the fibrogenesis induced by OA in vivo.

Results

Elevated levels of fibrogenic and inflammatory factors were linked to decreased miR-137 expression in OA samples. In IL-1β-treated chondrocytes, there was an upregulation of fibrogenic markers alongside a reduction in miR-137 levels. The overexpression of miR-137 inhibited fibrogenesis through the negative regulation of BMP7. Additionally, treatment with andrographolide was effective in attenuating the fibrogenic phenotype in chondrocytes and mitigating OA pathogenesis via modulating the miR-137/BMP7 pathway.

Conclusion

miR-137 downregulation and BMP7 overexpression might contribute to the fibrogenic features in OA-related chondrocytes. Andrographolide attenuates fibrogenic phenotype in chondrocytes and alleviates the severity of OA by modulating the miR-137/BMP7 axis.

Characterization of Epithelial-Mesenchymal and Neuroendocrine Differentiation States in Pancreatic and Small Cell Ovarian Tumor Cells and Their Modulation by TGF-β1 and BMP-7

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, due in part to early invasion and metastasis, which in turn involves epithelial-mesenchymal transition (EMT) of the cancer cells. Prompted by the discovery that two PDAC cell lines of the quasi-mesenchymal subtype (PANC-1, MIA PaCa-2) exhibit neuroendocrine differentiation (NED), we asked whether NED is associated with EMT. Using real-time PCR and immunoblotting, we initially verified endogenous expressions of various NED markers, i.e., chromogranin A (CHGA), synaptophysin (SYP), somatostatin receptor 2 (SSTR2), and SSTR5 in PANC-1 and MIA PaCa-2 cells. By means of immunohistochemistry, the expressions of CHGA, SYP, SSTR2, and the EMT markers cytokeratin 7 (CK7) and vimentin could be allocated to the neoplastic ductal epithelial cells of pancreatic ducts in surgically resected tissues from patients with PDAC. In HPDE6c7 normal pancreatic duct epithelial cells and in epithelial subtype BxPC-3 PDAC cells, the expression of CHGA, SYP, and neuron-specific enolase 2 (NSE) was either undetectable or much lower than in PANC-1 and MIA PaCa-2 cells. Parental cultures of PANC-1 cells exhibit EM plasticity (EMP) and harbor clonal subpopulations with both M- and E-phenotypes. Of note, M-type clones were found to display more pronounced NED than E-type clones. Inducing EMT in parental cultures of PANC-1 cells by treatment with transforming growth factor-β1 (TGF-β1) repressed epithelial genes and co-induced mesenchymal and NED genes, except for SSTR5. Surprisingly, treatment with bone morphogenetic protein (BMP)-7 differentially affected gene expressions in PANC-1, MIA PaCa-2, BxPC-3, and HPDE cells. It synergized with TGF-β1 in the induction of vimentin, SNAIL, SSTR2, and NSE but antagonized it in the regulation of CHGA and SSTR5. Phospho-immunoblotting in M- and E-type PANC-1 clones revealed that both TGF-β1 and, surprisingly, also BMP-7 activated SMAD2 and SMAD3 and that in M- but not E-type clones BMP-7 was able to dramatically enhance the activation of SMAD3. From these data, we conclude that in EMT of PDAC cells mesenchymal and NED markers are co-regulated, and that mesenchymal-epithelial transition (MET) is associated with a loss of both the mesenchymal and NED phenotypes. Analyzing NED in another tumor type, small cell carcinoma of the ovary hypercalcemic type (SCCOHT), revealed that two model cell lines of this disease (SCCOHT-1, BIN-67) do express CDH1, SNAI1, VIM, CHGA, SYP, ENO2, and SSTR2, but that in contrast to BMP-7, none of these genes was transcriptionally regulated by TGF-β1. Likewise, in BIN-67 cells, BMP-7 was able to reduce proliferation, while in SCCOHT-1 cells this occurred only upon combined treatment with TGF-β and BMP-7. We conclude that in PDAC-derived tumor cells, NED is closely linked to EMT and TGF-β signaling, which may have implications for the therapeutic use of TGF-β inhibitors in PDAC management.

From inflammation to renal fibrosis: A one-way road in autoimmunity?

Renal fibrosis is now recognized as a main determinant of renal pathology to include chronic kidney disease. Deposition of pathological matrix in the walls of glomerular capillaries, the interstitial space, and around arterioles predicts and contributes to the functional demise of the nephron and its surrounding vasculature. The recent identification of the major cell populations of fibroblast precursors in the kidney interstitium such as pericytes and tissue-resident mesenchymal stem cells, or bone-marrow-derived macrophages, and in the glomerulus such as podocytes, parietal epithelial and mesangial cells, has enabled the study of the fibrogenic process thought the lens of involved immunological pathways. Besides, a growing body of evidence is supporting the role of the lymphatic system in modulating the immunological response potentially leading to inflammation and ultimately renal damage. These notions have moved our understanding of renal fibrosis to be recognized as a clinical entity and new main player in autoimmunity, impacting directly the management of patients.

Potential therapeutic medicines for renal fibrosis: Small-molecule compounds and natural products

Renal fibrosis is the pathological change process of chronic kidney disease deteriorating continuously. When the renal organ is stimulated by external stimuli, it will trigger the damage and phenotypic changes of some intrinsic cells in the kidney. When the body's autoimmune regulation or external treatment is not prompted enough to restore the organ, the pathological process is gradually aggravating, inducing a large amount of intracellular collagen deposition, which leads to the appearance of fibrosis and scarring. The renal parenchyma (including glomeruli and tubules) begins to harden, making it difficult to repair the kidney lesions. In the process of gradual changes in the kidney tissue, the kidney units are severely damaged and the kidney function shows a progressive decline, eventually resulting in the clinical manifestation of end-stage renal failure, namely uremia. This review provides a brief description of the diagnosis, pathogenesis, and potential therapeutic inhibitors of renal fibrosis. Since renal fibrosis has not yet had a clear therapeutic target and related drugs, some potential targets and relevant inhibitors are discussed, especially pharmacological effects and interactions with targets. Some existing natural products have potential efficacy for renal fibrosis, which is also roughly summarized, hoping that this article would have reference significance for the treatment of renal fibrosis.

A Quest for Potential Role of Vitamin D in Type II Diabetes Mellitus Induced Diabetic Kidney Disease

Diabetes mellitus is a metabolic disorder characterized by high blood sugar levels. In recent years, T2DM has become a worldwide health issue due to an increase in incidence and prevalence. Diabetic kidney disease (DKD) is one of the devastating consequences of diabetes, especially owing to T2DM and the key clinical manifestation of DKD is weakened renal function and progressive proteinuria. DKD affects approximately 1/3rd of patients with diabetes mellitus, and T2DM is the predominant cause of end-stage kidney disease (ESKD). Several lines of studies have observed the association between vitamin D deficiency and the progression and etiology of type II diabetes mellitus. Emerging experimental evidence has shown that T2DM is associated with various kinds of kidney diseases. Recent evidence has also shown that an alteration in VDR (vitamin D receptor) signaling in podocytes leads to DKD. The present review aims to examine vitamin D metabolism and its correlation with T2DM. Furthermore, we discuss the potential role of vitamin D and VDR in diabetic kidney disease.

NBL1 Reduces Corneal Fibrosis and Scar Formation after Wounding

Corneal scarring is a leading cause of blindness. Currently, there is no treatment to prevent and/or reduce corneal scar formation under pathological conditions. Our previous data showed that the NBL1 protein, also termed the DAN Family BMP (Bone morphogenetic protein) Antagonist, was highly expressed in corneal stromal cells upon wounding. Here, we examined the function of NBL1 in corneal wound healing. Mouse corneas were mechanically wounded, followed by a 2-week treatment using NBL1. Wounded corneas treated with vehicle or an Fc tag served as controls. Compared with the controls, NBL1 treatment facilitated wound re-epithelialization, partially restored the stromal thickness, and significantly reduced corneal scar formation. NBL1 treatment did not decrease immune cell infiltration, indicating that the anti-scarring effect was not dependent on immune suppression. We further examined the anti-fibrotic effect of NBL1 on human corneas. Pairs of human corneas were induced to form myofibroblasts (a key player in fibrosis and scarring) upon wounding and incubation in a medium containing TGF-β1. The OS corneas were treated with Fc as a control, and the OD corneas were treated with NBL1. Compared with the control, human corneas treated with NBL1 had significantly fewer myofibroblasts, which was consistent with these mouse data. A further study revealed that NBL1 treatment inhibited BMP canonical (phospho-Smad1/5) and no-canonical (phospho-p38) pathways in human corneas. Data show that NBL1 reduced corneal fibrosis and scar formation in mice and cultured human corneas. The underlying molecular mechanism is not certain because both anti-fibrotic Smad1/5 and pro-fibrotic p38 pathways were inhibited upon NBL1 treatment. Whether the p38 pathway dominates the Smad1/5 pathway during corneal fibrosis, leading to the anti-fibrotic effect of NBL1, needs further investigation.

Potential of bone morphogenetic protein-7 in treatment of lupus nephritis: addressing the hurdles to implementation

Up to 50% of systemic lupus erythematosus (SLE) patients world-wide develop lupus nephritis (LN). In low to middle income countries and in particular in sub-Saharan Africa, where SLE is prevalent with a more aggressive course, LN and end stage renal disease is a major cause of mortality. While developed countries have the funding to invest in SLE and LN research, patients of African descent are often underrepresented in clinical trials. Thus, the complex influence of ethnicity and genetic background on outcome of LN and SLE as a whole, is not fully understood. Several pathophysiological mechanisms including major role players driving LN have been identified. A large body of literature suggest that prevention of fibrosis-which contributes to chronicity of LN-may significantly improve long-term prognosis. Bone morphogenetic protein-7 (BMP-7) was first identified as a therapeutic option in this context decades ago and evidence of its benefit in various conditions, including LN, is ever-increasing. Despite these facts, BMP-7 is not being implemented as therapy in the context of renal disease. With this review, we briefly summarise current understanding of LN pathology and discuss the evidence in support of therapeutic potential of BMP-7 in this context. Lastly, we address the obstacles that need to be overcome, before BMP-7 may become available as LN treatment.

Obstructive nephropathy and molecular pathophysiology of renal interstitial fibrosis

The kidneys play a key role in maintaining total body homeostasis. The complexity of this task is reflected in the unique architecture of the organ. Ureteral obstruction greatly affects renal physiology by altering hemodynamics, changing glomerular filtration and renal metabolism, and inducing architectural malformations of the kidney parenchyma, most importantly renal fibrosis. Persisting pathological changes lead to chronic kidney disease, which currently affects ∼10% of the global population and is one of the major causes of death worldwide. Studies on the consequences of ureteral obstruction date back to the 1800s. Even today, experimental unilateral ureteral obstruction (UUO) remains the standard model for tubulointerstitial fibrosis. However, the model has certain limitations when it comes to studying tubular injury and repair, as well as a limited potential for human translation. Nevertheless, ureteral obstruction has provided the scientific community with a wealth of knowledge on renal (patho)physiology. With the introduction of advanced omics techniques, the classical UUO model has remained relevant to this day and has been instrumental in understanding renal fibrosis at the molecular, genomic, and cellular levels. This review details key concepts and recent advances in the understanding of obstructive nephropathy, highlighting the pathophysiological hallmarks responsible for the functional and architectural changes induced by ureteral obstruction, with a special emphasis on renal fibrosis.

The Influence of Race/Ethnicity on the Transcriptomic Landscape of Uterine Fibroids

The objective of this study was to determine if the aberrant expression of select genes could form the basis for the racial disparity in fibroid characteristics. The next-generation RNA sequencing results were analyzed as fold change [leiomyomas/paired myometrium, also known as differential expression (DF)], comparing specimens from White (n = 7) and Black (n = 12) patients. The analysis indicated that 95 genes were minimally changed in tumors from White (DF ≈ 1) but were significantly altered by more than 1.5-fold (up or down) in Black patients. Twenty-one novel genes were selected for confirmation in 69 paired fibroids by qRT-PCR. Among these 21, coding of transcripts for the differential expression of FRAT2, SOX4, TNFRSF19, ACP7, GRIP1, IRS4, PLEKHG4B, PGR, COL24A1, KRT17, MMP17, SLN, CCDC177, FUT2, MYO5B, MYOG, ZNF703, CDC25A, and CDCA7 was significantly higher, while the expression of DAB2 and CAV2 was significantly lower in tumors from Black or Hispanic patients compared with tumors from White patients. Western blot analysis revealed a greater differential expression of PGR-A and total progesterone (PGR-A and PGR-B) in tumors from Black compared with tumors from White patients. Collectively, we identified a set of genes uniquely expressed in a race/ethnicity-dependent manner, which could form the underlying mechanisms for the racial disparity in fibroids and their associated symptoms.

Bone morphogenetic protein-7 attenuates pancreatic damage under diabetic conditions and prevents progression to diabetic nephropathy via inhibition of ferroptosis

Background

Approximately 30% of diabetic patients develop diabetic nephropathy, a representative microvascular complication. Although the etiological mechanism has not yet been fully elucidated, renal tubular damage by hyperglycemia-induced expression of transforming growth factor-β (TGF-β) is known to be involved. Recently, a new type of cell death by iron metabolism called ferroptosis was reported to be involved in kidney damage in animal models of diabetic nephropathy, which could be induced by TGF-β. Bone morphogenetic protein-7 (BMP7) is a well-known antagonist of TGF-β inhibiting TGF-β-induced fibrosis in many organs. Further, BMP7 has been reported to play a role in the regeneration of pancreatic beta cells in diabetic animal models.

Methods

We used protein transduction domain (PTD)-fused BMP7 in micelles (mPTD-BMP7) for long-lasting in vivo effects and effective in vitro transduction and secretion.

Results

mPTD-BMP7 successfully accelerated the regeneration of diabetic pancreas and impeded progression to diabetic nephropathy. With the administration of mPTD-BMP7, clinical parameters and representative markers of pancreatic damage were alleviated in a mouse model of streptozotocin-induced diabetes. It not only inhibited the downstream genes of TGF-β but also attenuated ferroptosis in the kidney of the diabetic mouse and TGF-β-stimulated rat kidney tubular cells.

Conclusion

BMP7 impedes the progression of diabetic nephropathy by inhibiting the canonical TGF-β pathway, attenuating ferroptosis, and helping regenerate diabetic pancreas.

Injectable, Drug-Eluting Nanocrystals Prevent Fibrosis and Stricture Formation In Vivo

BACKGROUND & AIMS

Tissue fibrosis results from uncontrolled healing responses leading to excessive mesenchymal cell activation and collagen and other extracellular matrix deposition. In the gastrointestinal tract, fibrosis leads to narrowing of the lumen and stricture formation. A drug treatment to prevent fibrosis and strictures in the gastrointestinal tract would be transformational for patient care. We aimed to develop a stricture treatment with the following characteristics and components: a small molecule with strong antifibrotic effects that is delivered locally at the site of the stricture to ensure correct lesional targeting while protecting the systemic circulation, and that is formulated with sustained-release properties to act throughout the wound healing processes.

METHODS

A high-throughput drug screening was performed to identify small molecules with antifibrotic properties. Next, we formulated an antifibrotic small molecule for sustained release and tested its antifibrotic potential in 3 animal models of fibrosis.

RESULTS

Sulconazole, a US Food and Drug Administration-approved drug for fungal infections, was found to have strong antifibrotic properties. Sulconazole was formulated as sulconazole nanocrystals for sustained release. We found that sulconazole nanocrystals provided superior or equivalent fibrosis prevention with less frequent dosing in mouse models of skin and intestinal tissue fibrosis. In a patient-like swine model of bowel stricture, a single injection of sulconazole nanocrystals prevented stricture formation.

CONCLUSIONS

The current data lay the foundation for further studies to improve the management of a range of diseases and conditions characterized by tissue fibrosis.

TGF-β Inhibitors for Therapeutic Management of Kidney Fibrosis

Kidney fibrosis is a common pathophysiological mechanism of chronic kidney disease (CKD) progression caused by several underlying kidney diseases. Among various contributors to kidney fibrosis, transforming growth factor-β1 (TGF-β1) is the major factor driving fibrosis. TGF-β1 exerts its profibrotic attributes via the activation of canonical and non-canonical signaling pathways, which induce proliferation and activation of myofibroblasts and subsequent accumulation of extracellular matrix. Over the past few decades, studies have determined the TGF-β1 signaling pathway inhibitors and evaluated whether they could ameliorate the progression of CKD by hindering kidney fibrosis. However, therapeutic strategies that block TGF-β1 signaling have usually demonstrated unsatisfactory results. Herein, we discuss the therapeutic concepts of the TGF-β1 signaling pathway and its inhibitors and review the current state of the art regarding regarding TGF-β1 inhibitors in CKD management.

The Growth Factors: Potential Biomarkers and Therapeutic Targets in Kidney Diseases

BACKGROUND

Kidney diseases are a prevalent health problem worldwide. Although substantial progress has been made in understanding the pathophysiology of kidney disease, currently there is no satisfactory clinical treatment available to prevent or treat kidney disease. Therefore, strategies to establish early diagnosis, identify the key molecules, and develop novel therapeutic interventions to slow the progression of kidney diseases and reduce their complications are encouraged.

SUMMARY

The growth factors play a crucial role in the development of kidney diseases. The altered levels of growth factors are usually detected in circulation and urine in the disease course. A growing body of studies has suggested that growth factors, receptors, and related regulators are promising biomarkers for the diagnosis and/or prognosis and potential therapeutic targets for the treatment of kidney diseases. In this review, we summarize recent advances in the potential applications of growth factors for diagnostic biomarkers and therapeutic targets in kidney diseases and highlight their performances in clinical trials.

KEY MESSAGES

Most diagnostic and therapeutic strategies targeting growth factors are still far from clinical implementation. The better understanding of growth factor-regulated pathophysiology and the progress of new intervention approaches are expected to facilitate the clinical translation of growth factor-based diagnosis and therapy of kidney diseases.

Renal fibrosis as a hallmark of diabetic kidney disease: Potential role of targeting transforming growth factor-beta (TGF-β) and related molecules

INTRODUCTION

Diabetic kidney disease (DKD) is the most common cause of end-stage renal disease (ESRD) worldwide. Currently, there is no effective treatment to completely prevent DKD progression to ESRD. Renal fibrosis and inflammation are the major pathological features of DKD, being pursued as potential therapeutic targets for DKD.

AREAS COVERED

Inflammation and renal fibrosis are involved in the pathogenesis of DKD. Anti-inflammatory drugs have been developed to combat DKD but without efficacy demonstrated. Thus, we have focused on the mechanisms of TGF-β-induced renal fibrosis in DKD, as well as discussing the important molecules influencing the TGF-β signaling pathway and their potential development into new pharmacotherapies, rather than targeting the ligand TGF-β and/or its receptors, such options include Smads, microRNAs, histone deacetylases, connective tissue growth factor, bone morphogenetic protein 7, hepatocyte growth factor, and cell division autoantigen 1.

EXPERT OPINION

TGF-β is a critical driver of renal fibrosis in DKD. Molecules that modulate TGF-β signaling rather than TGF-β itself are potentially superior targets to safely combat DKD. A comprehensive elucidation of the pathogenesis of DKD is important, which requires a better model system and access to clinical samples via collaboration between basic and clinical researchers.

Human Cytomegalovirus and Human Herpesvirus 6 Coinfection of Dermal Fibroblasts Enhances the Pro-Inflammatory Pathway Predisposing to Fibrosis: The Possible Impact on Systemic Sclerosis

Systemic sclerosis (SSc) is a severe autoimmune disease likely triggered by genetic and environmental factors, including viral infections. Human cytomegalovirus (HCMV) and human herpesvirus 6A species (HHV-6A) have been associated with SSc, based on in vivo and in vitro evidence, but the data are still inconclusive. Furthermore, despite both viruses being highly prevalent in humans and able to exacerbate each other’s effects, no data are available on their joint effects. Hence, we aimed to study their simultaneous impact on the expression of cell factors correlated with fibrosis and apoptosis in in vitro coinfected fibroblasts, representing the main target cell type in SSc. The results, obtained by a microarray detecting 84 fibrosis/apoptosis-associated factors, indicated that coinfected cells underwent higher and more sustained expression of fibrosis-associated parameters compared with single-infected cells. Thus, the data, for the first time, suggest that HCMV and HHV-6A may cooperate in inducing alterations potentially leading to cell fibrosis, thus further supporting their joint role in SSc. However, further work is required to definitively answer whether β-herpesviruses are causally linked to the disease and to enable the possible use of targeted antiviral treatments to improve clinical outcomes.

Annexin A2 (ANXA2) regulates the transcription and alternative splicing of inflammatory genes in renal tubular epithelial cells

Background

Renal inflammation plays a crucial role during the progression of Chronic kidney disease (CKD), but there is limited research on hub genes involved in renal inflammation. Here, we aimed to explore the effects of Annexin A2 (ANXA2), a potential inflammatory regulator, on gene expression in human proximal tubular epithelial (HK2) cells. RNA-sequencing and bioinformatics analysis were performed on ANXA2-knockdown versus control HK2 cells to reveal the differentially expressed genes (DEGs) and regulated alternative splicing events (RASEs). Then the DEGs and RASEs were validated by qRT-PCR.

Results

A total of 220 upregulated and 171 downregulated genes related to ANXA2 knockdown were identified. Genes enriched in inflammatory response pathways, such as interferon-mediated signaling, cytokine-mediated signaling, and nuclear factor κB signaling, were under global transcriptional and alternative splicing regulation by ANXA2 knockdown. qRT-PCR confirmed ANXA2-regulated transcription of chemokine gene CCL5, as well as interferon-regulating genes ISG15, IFI6, IFI44, IFITM1, and IRF7, in addition to alternative splicing of inflammatory genes UBA52, RBCK1, and LITAF.

Conclusions

The present study indicated that ANXA2 plays a role in inflammatory response in HK2 cells that may be mediated via the regulation of transcription and alternative splicing of inflammation-related genes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08748-6.

BMP3 inhibits TGFβ2-mediated myofibroblast differentiation during wound healing of the embryonic cornea

Often acute damage to the cornea initiates drastic tissue remodeling, resulting in fibrotic scarring that disrupts light transmission and precedes vision impairment. Very little is known about the factors that can mitigate fibrosis and promote scar-free cornea wound healing. We previously described transient myofibroblast differentiation during non-fibrotic repair in an embryonic cornea injury model. Here, we sought to elucidate the mechanistic regulation of myofibroblast differentiation during embryonic cornea wound healing. We found that alpha-smooth muscle actin (αSMA)-positive myofibroblasts are superficial and their presence inversely correlates with wound closure. Expression of TGFβ2 and nuclear localization of pSMAD2 were elevated during myofibroblast induction. BMP3 and BMP7 were localized in the corneal epithelium and corresponded with pSMAD1/5/8 activation and absence of myofibroblasts in the healing stroma. In vitro analyses with corneal fibroblasts revealed that BMP3 inhibits the persistence of TGFβ2-induced myofibroblasts by promoting disassembly of focal adhesions and αSMA fibers. This was confirmed by the expression of vinculin and pFAK. Together, these data highlight a mechanism to inhibit myofibroblast persistence during cornea wound repair.

Hormonal Regulation of Renal Fibrosis

Fibrosis is a severe complication of many acute and chronic kidney pathologies. According to current concepts, an imbalance in the synthesis and degradation of the extracellular matrix by fibroblasts is considered the key cause of the induction and progression of fibrosis. Nevertheless, inflammation associated with the damage of tissue cells is among the factors promoting this pathological process. Most of the mechanisms accompanying fibrosis development are controlled by various hormones, which makes humoral regulation an attractive target for therapeutic intervention. In this vein, it is particularly interesting that the kidney is the source of many hormones, while other hormones regulate renal functions. The normal kidney physiology and pathogenesis of many kidney diseases are sex-dependent and thus modulated by sex hormones. Therefore, when choosing therapy, it is necessary to focus on the sex-associated characteristics of kidney functioning. In this review, we considered renal fibrosis from the point of view of vasoactive and reproductive hormone imbalance. The hormonal therapy possibilities for the treatment or prevention of kidney fibrosis are also discussed.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

Renal-on-Chip Microfluidic Platform with a Force-Sensitive Resistor (ROC-FS) for Molecular Pathogenesis Analysis of Hydronephrosis

Hydronephrosis is one of the most common diseases in urology. However, due to the difficulties in clinical trials and the lack of reliable in vitro platforms, the surgical indicators are not clear. Herein, the renal-on-chip with a force-sensitive resistor microfluidic platform was established to simulate the state of hydronephrosis. Cell counting kit-8 (CCK-8) and tight junction protein claudin-2 were detected on a renal-on-chip microfluidic platform with a force-sensitive resistor (ROC-FS). The results indicated that the ROC-FS had normal physiological functions and the cell viability on ROC-FS declined to around 40% after 48 h of hydronephrosis-simulated treatment. In addition, proteomics analysis of 15 clinical ureteropelvic junction obstruction (UPJO) samples showed that compared with normal children, a total of 50 common proteins were differentially expressed in UPJO children (P < 0.05, |log₂fold change| ≥ 1). Metabolomic analysis of 39 clinical UPJO samples showed that a total of 241 metabolisms were dysregulated. Subsequent immunofluorescence and enzyme-linked immunosorbent assay (ELISA) analysis using ROC-FS were performed to identify the clinical multi-omics results for screening. All results pointed out that the TGF-β-related signaling pathways and arginine-related metabolism signaling pathways were dysregulated and α-SMA, AGT, and AGA might be the potential biomarkers of hydronephrosis. In addition, correlation analysis of AGT and KLK1 with differential renal function (DRF) from clinical samples indicated good correlation coefficients (R² 0.923, 0.8742, 0.6412, and 0.8347). This demonstrates the state of hydronephrosis could be significantly correlated with the biomarkers. These findings could provide a reliable reference for determining surgical biomarkers clinically, and ROC could be further used in the analysis of other kidney diseases.

Profiling Biomarkers in HIV Glomerular Disease – Potential for the Non-Invasive Diagnosis of HIVAN?

Background

There is a wide spectrum of kidney pathology in human immunodeficiency virus (HIV) infection, affecting all structures of the kidney. The histology of HIV chronic kidney disease (CKD) is diverse, ranging from HIV-associated nephropathy (HIVAN) to focal glomerulosclerosis (FSGS), HIV-immune complex disease (HIV-ICD), other glomerulopathies and tubulo-interstitial nephritis. Definitive diagnosis is by kidney biopsy, an invasive procedure. However, serum and urinary biomarkers may be useful in predicting the histological diagnosis of HIVAN.

Purpose

We wished to determine the utility of serum and urinary biomarkers in predicting the histological diagnosis of HIVAN.

Patients and Methods

We measured neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, transforming growth factor (TGF)-β isoforms and bone morphogenetic protein (BMP)-7 in the serum and urine in patients with different histological forms of HIV glomerular disease.

Results

In HIVAN, we demonstrated increased levels of serum cystatin C and increased levels of serum and urinary NGAL. Urinary TGF-β1 and TGF-β2 levels were elevated in HIV-positive patients with CKD but were not significantly different in the different HIV histologies, while urinary BMP-7 levels were elevated in minimal change disease.

Conclusion

This study confirmed the presence of increased serum and urinary biomarkers of tubular injury in patients with HIVAN, and increased urinary biomarkers of fibrosis in HIV CKD, and may indicate their value as a non-invasive diagnostic tool for the diagnosis of HIVAN.

Harnessing the Physiological Functions of Cellular Prion Protein in the Kidneys: Applications for Treating Renal Diseases

A cellular prion protein (PrP^C) is a ubiquitous cell surface glycoprotein, and its physiological functions have been receiving increased attention. Endogenous PrP^C is present in various kidney tissues and undergoes glomerular filtration. In prion diseases, abnormal prion proteins are found to accumulate in renal tissues and filtered into urine. Urinary prion protein could serve as a diagnostic biomarker. PrP^C plays a role in cellular signaling pathways, reno-protective effects, and kidney iron uptake. PrP^C signaling affects mitochondrial function via the ERK pathway and is affected by the regulatory influence of microRNAs, small molecules, and signaling proteins. Targeting PrP^C in acute and chronic kidney disease could help improve iron homeostasis, ameliorate damage from ischemia/reperfusion injury, and enhance the efficacy of mesenchymal stem/stromal cell or extracellular vesicle-based therapeutic strategies. PrP^C may also be under the influence of BMP/Smad signaling and affect the progression of TGF-β-related renal fibrosis. PrP^C conveys TNF-α resistance in some renal cancers, and therefore, the coadministration of anti-PrP^C antibodies improves chemotherapy. PrP^C can be used to design antibody-drug conjugates, aptamer-drug conjugates, and customized tissue inhibitors of metalloproteinases to suppress cancer. With preclinical studies demonstrating promising results, further research on PrP^C in the kidney may lead to innovative PrP^C-based therapeutic strategies for renal disease.

Emodin-induced autophagic cell death hinders epithelial-mesenchymal transition via regulation of BMP-7/TGF-β1 in renal fibrosis

We aim to explore the effects of emodin and its mechanisms on renal fibrosis (RF). We firstly modeled adriamycin-induced rat RF with unilateral nephrectomy. In vivo and in vitro pharmacological experiments were performed in this study. The presence of collagen deposition was detected by Masson staining. To verify whether emodin attenuates RF by monitoring autophagy, the immunohistochemistry staining for autophagy protein LC3B was performed. We conducted western blot to detect the expression of the autophagy-related proteins in EMT in vitro model after treating with emotin and BMP-7. In vivo, we demonstrated that emodin could improve renal dysfunction and decrease pathological damage of the kidney by activation of autophagy and inhibition of EMT. Upregulation of BMP-7 was recorded in the RF rats subjected to emodin treatment. In vitro studies, emodin has the capacity of reversing EMT and activating autophagy, and emodin could regulate the expression of BMP-7. The results revealed that the attenuation of EMT by emodin could be blocked after the inhibition of BMP-7 and suppression of autophagy. Our findings demonstrated that emodin alleviates EMT during RF by actuating autophagy through BMP-7, suggesting a role of BMP-7 in RF treatment and prevention.

The Epithelial-to-Mesenchymal Transition as a Possible Therapeutic Target in Fibrotic Disorders

Fibrosis is a chronic and progressive disorder characterized by excessive deposition of extracellular matrix, which leads to scarring and loss of function of the affected organ or tissue. Indeed, the fibrotic process affects a variety of organs and tissues, with specific molecular background. However, two common hallmarks are shared: the crucial role of the transforming growth factor-beta (TGF-β) and the involvement of the inflammation process, that is essential for initiating the fibrotic degeneration. TGF-β in particular but also other cytokines regulate the most common molecular mechanism at the basis of fibrosis, the Epithelial-to-Mesenchymal Transition (EMT). EMT has been extensively studied, but not yet fully explored as a possible therapeutic target for fibrosis. A deeper understanding of the crosstalk between fibrosis and EMT may represent an opportunity for the development of a broadly effective anti-fibrotic therapy. Here we report the evidences of the relationship between EMT and multi-organ fibrosis, and the possible therapeutic approaches that may be developed by exploiting this relationship.

Candidate rejuvenating factor GDF11 and tissue fibrosis: friend or foe?

Growth differentiation factor 11 (GDF11 or bone morphogenetic protein 11, BMP11) belongs to the transforming growth factor-β superfamily and is closely related to other family member-myostatin (also known as GDF8). GDF11 was firstly identified in 2004 due to its ability to rejuvenate the function of multiple organs in old mice. However, in the past few years, the heralded rejuvenating effects of GDF11 have been seriously questioned by many studies that do not support the idea that restoring levels of GDF11 in aging improves overall organ structure and function. Moreover, with increasing controversies, several other studies described the involvement of GDF11 in fibrotic processes in various organ setups. This review paper focuses on the GDF11 and its pro- or anti-fibrotic actions in major organs and tissues, with the goal to summarize our knowledge on its emerging role in regulating the progression of fibrosis in different pathological conditions, and to guide upcoming research efforts.

Impact of Human Cytomegalovirus and Human Herpesvirus 6 Infection on the Expression of Factors Associated with Cell Fibrosis and Apoptosis: Clues for Implication in Systemic Sclerosis Development

Systemic sclerosis (SSc) is a severe autoimmune disorder characterized by vasculopathy and multi-organ fibrosis; its etiology and pathogenesis are still largely unknown. Herpesvirus infections, particularly by human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6), have been suggested among triggers of the disease based on virological and immunological observations. However, the direct impact of HCMV and/or HHV-6 infection on cell fibrosis and apoptosis at the cell microenvironment level has not yet been clarified. Thus, this study aimed to investigate the effects of HCMV and HHV-6 infection on the induction of pro-fibrosis or pro-apoptosis conditions in primary human dermal fibroblasts, one of the relevant SSc target cells. The analysis, performed by microarray in in vitro HCMV- or HHV-6-infected vs. uninfected cells, using specific panels for the detection of the main cellular factors associated with fibrosis or apoptosis, showed that both viruses significantly modified the expression of at least 30 pro-fibrotic and 20 pro-apoptotic factors. Notably, several recognized pro-fibrotic factors were highly induced, and most of them were reported to be involved in vivo in the multifactorial and multistep pathogenic process of SSc, thus suggesting a potential role of both HCMV and HHV-6.

Progress in drug delivery system for fibrosis therapy

Fibrosis is a necessary process in the progression of chronic disease to cirrhosis or even cancer, which is a serious disease threatening human health. Recent studies have shown that the early treatment of fibrosis is turning point and particularly important. Therefore, how to reverse fibrosis has become the focus and research hotspot in recent years. So far, the considerable progress has been made in the development of effective anti-fibrosis drugs and targeted drug delivery. Moreover, the existing research results will lay the foundation for more breakthrough delivery systems to achieve better anti-fibrosis effects. Herein, this review summaries anti-fibrosis delivery systems focused on three major organ fibrotic diseases such as liver, pulmonary, and renal fibrosis accompanied by the elaboration of relevant pathological mechanisms, which will provide inspiration and guidance for the design of fibrosis drugs and therapeutic systems in the future.

New targets for overactive bladder-ICI-RS 2109

AIM

To review evidence for novel drug targets that can manage overactive bladder (OAB) symptoms.

METHODS

A think tank considered evidence from the literature and their own research experience to propose new drug targets in the urinary bladder to characterize their use to treat OAB.

RESULTS

Five classes of agents or cellular pathways were considered. (a) Cyclic nucleotide-dependent (cyclic adenosine monophosphate and cyclic guanosine monophosphate) pathways that modulate adenosine triphosphate release from motor nerves and urothelium. (b) Novel targets for β3 agonists, including the bladder wall vasculature and muscularis mucosa. (c) Several TRP channels (TRPV1 , TRPV4 , TRPA1 , and TRPM4 ) and their modulators in affecting detrusor overactivity. (d) Small conductance Ca2+ -activated K+ channels and their influence on spontaneous contractions. (e) Antifibrosis agents that act to modulate directly or indirectly the TGF-β pathway-the canonical fibrosis pathway.

CONCLUSIONS

The specificity of action remains a consideration if particular classes of agents can be considered for future development as receptors or pathways that mediate actions of the above mentioned potential agents are distributed among most organ systems. The tasks are to determine more detail of the pathological changes that occur in the OAB and how the specificity of potential drugs may be directed to bladder pathological changes. An important conclusion was that the storage, not the voiding, phase in the micturition cycle should be investigated and potential targets lie in the whole range of tissue in the bladder wall and not just detrusor.

A negative feedback loop between JNK-associated leucine zipper protein and TGF-β1 regulates kidney fibrosis

Renal fibrosis is controlled by profibrotic and antifibrotic forces. Exploring anti-fibrosis factors and mechanisms is an attractive strategy to prevent organ failure. Here we identified the JNK-associated leucine zipper protein (JLP) as a potential endogenous antifibrotic factor. JLP, predominantly expressed in renal tubular epithelial cells (TECs) in normal human or mouse kidneys, was downregulated in fibrotic kidneys. Jlp deficiency resulted in more severe renal fibrosis in unilateral ureteral obstruction (UUO) mice, while renal fibrosis resistance was observed in TECs-specific transgenic Jlp mice. JLP executes its protective role in renal fibrosis via negatively regulating TGF-β1 expression and autophagy, and the profibrotic effects of ECM production, epithelial-to-mesenchymal transition (EMT), apoptosis and cell cycle arrest in TECs. We further found that TGF-β1 and FGF-2 could negatively regulate the expression of JLP. Our study suggests that JLP plays a central role in renal fibrosis via its negative crosstalk with the profibrotic factor, TGF-β1.

Identification of histone deacetylase 8 as a novel therapeutic target for renal fibrosis

Histone deacetylases (HDACs) have been shown to alleviate renal fibrosis, however, the role of individual HDAC isoforms in this process is poorly understood. In this study, we examined the role of HDAC8 in the development of renal fibrosis and partial epithelial-mesenchymal transitions (EMT). In a murine model of renal fibrosis induced by unilateral ureteral obstruction (UUO), HDAC8 was primarily expressed in renal tubular epithelial cells and time-dependently upregulated. This occurred in parallel with the deacetylation of cortactin, a nonhistone substrate of HDAC8, and increased expression of three fibrotic markers: α-smooth muscle actin, collagen 1, and fibronectin. Administration of PCI34051, a highly selective inhibitor of HDAC8, restored acetylation of contactin and reduced expression of those proteins. PCI34051 treatment also reduced the number of renal tubular epithelial cells arrested at the G2/M phase of the cell cycle and suppressed phosphorylation of Smad3, STAT3, β-catenin, and expression of Snail after ureteral obstruction. In contrast, HDAC8 inhibition reversed UUO-induced downregulation of BMP7 and Klotho, two renoprotective proteins. In cultured murine proximal tubular cells, treatment with PCI34051 or specific HDAC8 siRNA was also effective in inhibiting transforming growth factor β1 (TGFβ1)-induced deacetylation of contactin, EMT, phosphorylation of Smad3, STAT3, and β-catenin, upregulation of Snail, and downregulation of BMP7 and Klotho. Collectively, these results suggest that HDAC8 activation is required for the EMT and renal fibrogenesis by activation of multiple profibrotic signaling and transcription factors, and suppression of antifibrotic proteins. Therefore, targeting HDAC8 may be novel therapeutic approach for treatment of renal fibrosis.

Ethanol Extract of Centella asiatica (Gotu Kola) Attenuates Tubular Injury Through Inhibition of Inflammatory Cytokines and Enhancement of Anti-Fibrotic Factor in Mice with 5/6 Subtotal Nephrectomy

BACKGROUND

Chronic kidney disease (CKD) leads to inflammation, fibrosis and destruction of the renal architecture. Centella asiatica (CeA) is an herbaceous plant with anti-inflammatory effects. We aimed to elucidate the effect of CeA on inflammation, fibrosis, vascular remodelling and antifibrotic substances in a 5/6 subtotal nephrectomy (SN) model in mice.

METHODS

Mice were divided into three groups: sham operation (SO, n = 6), 5/6 SN for seven days (SN7, n = 7) and SN7 with oral CeA treatment (SN7-CeA, n = 7). At day 7, mice were euthanised, kidneys were harvested and stained with periodic-acid Schiff (for tubular injury and glomerulosclerosis) and sirius red (for fibrosis and vascular remodeling) staining. mRNA expression of prepro-endothelin-1, nephrin, E-cadherin, bone morphogenic protein-7 (BMP-7), toll-like receptor 4 (TLR4), tumour necrosis factor-α (TNFα) and hepatocyte growth factor (HGF) were quantified using reverse transcriptase-PCR.

RESULTS

SN group demonstrated significant higher interstitial fibrosis, vascular remodeling, tubular injury and glomerulosclerosis (P < 0.01) compared to SO group. Meanwhile, in SN7-CeA demonstrated attenuation of vascular remodeling as shown by significant higher lumen area with lower Wall/Lumen area ratio compared to SN7. RT-PCR analysis showed up-regulation of nephrin, BMP-7 and E-cadherin mRNA expression (P < 0.05) and down-regulation of ppET-1 in SN7-CeA group compared to SN7 group (P < 0.05).

CONCLUSION

CeA may ameliorate renal injury in the SN model in mice.

Danggui Shaoyao San Ameliorates Renal Fibrosis via Regulation of Hypoxia and Autophagy

Danggui Shaoyao San (DSS), a traditional Chinese medicinal prescription, was widely used to reinforce earth to activate collaterals in ancient times. Recently, many clinical studies found that DSS had a renoprotection. In this study, we evaluated the effect of DSS on unilateral ureteral obstruction- (UUO-) induced renal fibrosis in rats and investigated the mechanisms underlying the effect. Sprague Dawley (SD) rats were randomized to UUO or Sham operation. After 1 day, the rats that underwent UUO were randomized to treatment for four experimental groups (n=10 each group): Sham, UUO only, UUO+ benazepril (Bena), and UUO+DSS. After 4 weeks, we demonstrated that DSS significantly suppressed UUO-induced renal hypertrophy by gravimetric. In addition, DSS obviously prevented UUO-induced disorder in renal structure and renal function by HE and biochemistry test. We also found that DSS abrogated UUO-induced renal fibrosis by Masson's staining and collagen volume fraction (CVF) analysis; this is consistent with the western blot analysis that showed DSS abrogated the UUO-induced enhanced TGF-β1 and weakened BMP-7. Compared with the UUO only group, rats treated with DSS exhibited significant increase in vascular density, followed by decrease in hypoxia and HIF-1α protein level through western blot and immunofluorescence analysis. Furthermore, we also determined proteins of autophagy and DSS enhanced autophagy to prevent the damage-induced by UUO. Taken together, our findings demonstrated that DSS had a renoprotection effect in ameliorating renal fibrosis possibly via attenuating tissue hypoxia and regulating autophagy.

Exosomes from Human Umbilical Cord Mesenchymal Stem Cells Reduce Damage from Oxidative Stress and the Epithelial-Mesenchymal Transition in Renal Epithelial Cells Exposed to Oxalate and Calcium Oxalate Monohydrate

Objective

To investigate whether exosomes from human umbilical cord mesenchymal stem cells (hUC-MSCs) can protect against the toxic effects of oxalate and calcium oxalate monohydrate (COM) crystals in human proximal tubular epithelial (HK-2) cells.

Methods

Exosomes were isolated from hUC-MSCs, purified by ultracentrifugation, and verified by examination of cell morphology using transmission electron microscopy and the presence of specific biomarkers. HK-2 cells received 1 of 4 treatments: control (cells alone), hUC-MSC exosomes, oxalate+COM, or oxalate+COM and hUC-MSC exosomes. Cell viability was determined using the MTT assay. Oxidative stress was determined by measuring LDH activity and the levels of H₂O₂, malondialdehyde (MDA), and reactive oxygen species (ROS). Expressions of N-cadherin, TGF-β, and ZO-1 were determined by immunofluorescence. Expressions of epithelial markers, mesenchymal markers, and related signaling pathway proteins were determined by western blotting.

Results

After 48 h, cells in the oxalate+COM group lost their adhesion, appeared long, spindle-shaped, and scattered, and the number of cells had significantly decreased. The oxalate+COM treatment also upregulated TGF-β and mesenchymal markers, downregulated epithelial markers, increased the levels of LDH, H₂O₂, MDA, and ROS, decreased cell viability, and increased cell migration. The isolated exosomes had double-layer membranes, had hollow, circular, or elliptical shapes, had diameters mostly between 30 and 100 nm, and expressed CD9, CD63, and Alix. Treatment of HK-2 cells with hUC-MSC exosomes reversed or partly reversed all the effects of oxalate+COM.

Conclusions

Exosomes from hUC-MSCs alleviate the oxidative injury and the epithelial-mesenchymal transformation of HK-2 cells that is induced by oxalate+COM.

Canonical BMP signaling in tubular cells mediates recovery after acute kidney injury

Bone morphogenetic protein (BMP) signaling has been shown to modulate the development of renal fibrosis in animal models of kidney injury, but the downstream mediators are incompletely understood. In wild-type mice, canonical BMP signaling mediated by SMAD1/5/8 transcription factors was constitutively active in healthy renal tubules, transiently down-regulated after ischemia reperfusion injury (IRI), and reactivated during successful tubular regeneration. We then induced IRI in mice with a tubular-specific BMP receptor 1A (BMPR1A) deletion. These mice failed to reactivate SMAD1/5/8 signaling in the post-ischemic phase and developed renal fibrosis after injury. Using unbiased genomic analyses, we identified three genes encoding inhibitor of DNA-binding (ID) proteins (Id1, Id2, and Id4) as key targets of BMPR1A-SMAD1/5/8 signaling. BMPR1A-deficient mice failed to re-induce these targets following IRI. Instead, BMPR1A-deficiency resulted in activation of pro-fibrotic signaling proteins that are normally repressed by ID proteins, namely, p38 mitogen-activated protein kinase and cell cycle inhibitor p27. These data indicate that the post-ischemic activation of canonical BMP signaling acts endogenously to repress pro-fibrotic signaling in tubular cells and may help to prevent the progression of acute kidney injury to chronic kidney disease.

Mechanisms of Bone Morphogenetic Protein-7 Protective Effects Against Cold Ischemia-Induced Renal Injury in Rats

Deceased donor kidneys are exposed to cold ischemic insult which makes them particularly susceptible to the effects of cold ischemic injury during hypothermic preservation resulting in high rates of delayed graft function. Bone morphogenetic protein-7 (BMP-7) is a valuable reagent in the field of tissue regeneration and preservation under ischemic conditions. Following these insights, we investigated the effect of recombinant human BMP-7 (rhBMP-7) on graft preservation during cold ischemia. The study was conducted on an experimental model of kidney cold ischemia in rats. Kidneys were perfused with University of Wisconsin (UW) saline solution, rhBMP-7, or rhBMP-7 + UW, and exposed to cold ischemia for 6, 12, and 24 hours. In tubular epithelial cells of kidneys perfused with rhBMP-7 and rhBMP-7+UW solution, the expression of BMP-7 and E-cadherin was observed after 24 hours of cold ischemia. In kidneys not perfused with rhBMP-7, high expression of transforming growth factor-β and α-smooth muscle actin was found. Also, in kidneys perfused with rhBMP-7 solution, statistically higher levels of Smad1, Smad5, and Smad8 messenger RNA expressions were proven. BMP-7 maintains the morphology of kidney tissue better than UW solution during 24 hours of cold ischemia. BMP-7 prevents epithelial to mesenchymal transformation and consequently maintains epithelial phenotype of tubular cells.

The mTOR/p70S6K1 signaling pathway in renal fibrosis of children with immunoglobulin A nephropathy

Aim:

The purpose of this study was to explore whether mTOR/p70S6K1 signaling is activated in renal fibrosis of immunoglobulin A nephropathy.

Methods:

Seventy-two children with immunoglobulin A nephropathy were divided into three groups according to their clinical features and pathological grades. Six normal renal specimens were included in the control group. The expression levels of angiotensin II, mTOR, p70S6K1, E-cadherin, and α-smooth muscle actin in renal tissues were determined by immunohistochemistry method, the potential correlations of these indexes and relationship between these indexes and the clinicopathological indexes were analyzed.

Results:

Compared to the control group, the expression levels of angiotensin II, mTOR, p70S6K1, and α-smooth muscle actin were significantly higher and the expression levels of E-cadherin were lower both in glomeruli and tubulointerstitium of immunoglobulin A nephropathy children. And the most significant differences were found in the nephrotic syndrome group and pathological grade IV group. In immunoglobulin A nephropathy renal tissues, the expression levels of angiotensin II in glomeruli and tubulointerstitium were both positively correlated with the expression levels of mTOR and α- smooth muscle actin, and negatively correlated with the expression levels of E-cadherin.

Conclusion:

The mTOR/p70S6K1 signaling was activated in renal tissues of children with immunoglobulin A nephropathy, and future studies will need to address the mechanism of mTOR/p70S6K1 signaling in the progress of renal fibrosis in immunoglobulin A nephropathy.

Deleting Death and Dialysis: Conservative Care of Cardio-Vascular Risk and Kidney Function Loss in Chronic Kidney Disease (CKD)

The uremic syndrome, which is the clinical expression of chronic kidney disease (CKD), is a complex amalgam of accelerated aging and organ dysfunctions, whereby cardio-vascular disease plays a capital role. In this narrative review, we offer a summary of the current conservative (medical) treatment options for cardio-vascular and overall morbidity and mortality risk in CKD. Since the progression of CKD is also associated with a higher cardio-vascular risk, we summarize the interventions that may prevent the progression of CKD as well. We pay attention to established therapies, as well as to novel promising options. Approaches that have been considered are not limited to pharmacological approaches but take into account lifestyle measures and diet as well. We took as many randomized controlled hard endpoint outcome trials as possible into account, although observational studies and post hoc analyses were included where appropriate. We also considered health economic aspects. Based on this information, we constructed comprehensive tables summarizing the available therapeutic options and the number and kind of studies (controlled or not, contradictory outcomes or not) with regard to each approach. Our review underscores the scarcity of well-designed large controlled trials in CKD. Nevertheless, based on the controlled and observational data, a therapeutic algorithm can be developed for this complex and multifactorial condition. It is likely that interventions should be aimed at targeting several modifiable factors simultaneously.

Pulmonary administration of a dry powder formulation of the antifibrotic drug tilorone reduces silica-induced lung fibrosis in mice

The aim of this work was to study the antifibrotic effect of pulmonary administration of tilorone to lung fibrosis. L-leucine coated tilorone particles were prepared and their aerosolization properties were analyzed using two dry powder inhalers (Easyhaler and Twister). In addition, the biological activity and cell monolayer permeation was tested. The antifibrotic effect of tilorone delivered by oropharyngeal aspiration was studied in vivo using a silica-induced model of pulmonary fibrosis in mice in a preventive setting. When delivered from the Easyhaler in an inhalation simulator, the emitted dose and fine particle fraction were independent from the pressure applied and showed dose repeatability. However, with Twister the aerosolization was pressure-dependent indicating poor compatibility between the device and the formulation. The formulation showed more consistent permeation through a differentiated Calu-3 cell monolayer compared to pristine tilorone. Tilorone decreased the histological fibrosis score in vivo in systemic and local administration, but only systemic administration decreased the mRNA expression of type I collagen. The difference was hypothesized to result from 40-fold higher drug concentration in tissue samples in the systemic administration group. These results show that tilorone can be formulated as inhalable dry powder and has potential as an oral and inhalable antifibrotic drug.

Targeting renal fibrosis: Mechanisms and drug delivery systems

Renal fibrosis is the common outcome of many chronic kidney diseases (CKD) independent of the underlying etiology. Despite a host of promising experimental data, currently available strategies only ameliorate or delay the progression of CKD but do not reverse fibrosis. One of the major impediments of translating novel antifibrotic strategies from bench to bedside is due to the intricacies of the drug delivery process. In this review, we briefly describe mechanisms of renal fibrosis and methods of drug transfer into the kidney. Various tools used in gene therapy to administer nucleic acids in vivo are discussed. Furthermore, we review the modes of action of protein- or peptide-based drugs with target-specific antibodies and cytokines incorporated in hydrogels. Additionally, we assess an intriguing new method to deliver drugs specifically to tubular epithelial cells via conjugation with ligands binding to the megalin receptor. Finally, plant-derived compounds with antifibrotic properties are also summarized.

Activated renal tubular Wnt/β-catenin signaling triggers renal inflammation during overload proteinuria

Imbalance of Wnt/β-catenin signaling in renal cells is associated with renal dysfunction, yet the precise mechanism is poorly understood. Previously we observed activated Wnt/β-catenin signaling in renal tubules during proteinuric nephropathy with an unknown net effect. Therefore, to identify the definitive role of tubular Wnt/β-catenin, we generated a novel transgenic "Tubcat" mouse conditionally expressing stabilized β-catenin specifically in renal tubules following tamoxifen administration. Four weeks after tamoxifen injection, uninephrectomized Tubcat mice displayed proteinuria and elevated blood urea nitrogen levels compared to non-transgenic mice, implying a detrimental effect of the activated signaling. This was associated with infiltration of the tubulointerstitium predominantly by M1 macrophages and overexpression of the inflammatory chemocytokines CCL-2 and RANTES. Induction of overload proteinuria by intraperitoneal injection of low-endotoxin bovine serum albumin following uninephrectomy for four weeks aggravated proteinuria and increased blood urea nitrogen levels to a significantly greater extent in Tubcat mice. Renal dysfunction correlated with the degree of M1 macrophage infiltration in the tubulointerstitium and renal cortical up-regulation of CCL-2, IL-17A, IL-1β, CXCL1, and ICAM-1. There was overexpression of cortical TLR-4 and NLRP-3 in Tubcat mice, independent of bovine serum albumin injection. Finally, there was no fibrosis, activation of epithelial-mesenchymal transition or non-canonical Wnt pathways observed in the kidneys of Tubcat mice. Thus, conditional activation of renal tubular Wnt/β-catenin signaling in a novel transgenic mouse model demonstrates that this pathway enhances intrarenal inflammation via the TLR-4/NLRP-3 inflammasome axis in overload proteinuria.

BMP Signalling at the Crossroad of Liver Fibrosis and Regeneration

Bone Morphogenetic Proteins (BMPs) belong to the Transforming Growth Factor-β (TGF-β) family. Initially identified due to their ability to induce bone formation, they are now known to have multiple functions in a variety of tissues, being critical not only during development for tissue morphogenesis and organogenesis but also during adult tissue homeostasis. This review focus on the liver as a target tissue for BMPs actions, devoting most efforts to summarize our knowledge on their recently recognized and/or emerging roles on regulation of the liver regenerative response to various insults, either acute or chronic and their effects on development and progression of liver fibrosis in different pathological conditions. In an attempt to provide the basis for guiding research efforts in this field both the more solid and more controversial areas of research were highlighted.

Suppression of BMP-7 by histone deacetylase 2 promoted apoptosis of renal tubular epithelial cells in acute kidney injury

Cisplatin, a highly effective and widely used chemotherapeutic agent, has a major limitation for its nephrotoxicity. Currently, there are no therapies available to treat or prevent cisplatin nephrotoxicity. We recently identified a novel strategy for attenuating its nephrotoxicity in chemotherapy by histone deacetylase (HDAC) inhibitors via epigenetic modification to enhance bone morphogenetic protein 7 (BMP-7) expression. Cisplatin upregulated the activity of HDAC2 in the kidney. Inhibition of HDAC with clinically used trichostatin A (TSA) or valproic acid (VPA) suppressed cisplatin-induced kidney injury and epithelial cell apoptosis. Overexpression of HDAC2 promotes CP-treated tubular epithelium cells apoptosis. Chromatin immunoprecipitation assay clearly detected HDAC2 assosiation with BMP-7 promoter. Western blot and immunofluorescence results demonstrated that the expression of BMP-7 was clearly induced by TSA or VPA in vivo and in vitro. Interestingly, administration of recombinant BMP-7 (rhBMP-7) reduced cisplatin-induced kidney dysfunction. Moreover, BMP-7 treatment suppressed epithelial cell apoptosis and small interfering RNA-based knockdown of BMP-7 expression abolished HDAC inhibitors suppression of epithelial cell apoptosis in vitro. Results of current study indicated that TSA or VPA inhibited apoptosis of renal tubular epithelial cells via promoting the level of BMP-7 epigenetically through targeting HDAC2. Hence, HDAC inhibitors could be useful therapeutic agents for the prevention of cisplatin nephrotoxicity.

Targeting TGF-β Mediated SMAD Signaling for the Prevention of Fibrosis

Fibrosis occurs when there is an imbalance in extracellular matrix (ECM) deposition and degradation. Excessive ECM deposition results in scarring and thickening of the affected tissue, and interferes with tissue and organ homeostasis – mimicking an exaggerated “wound healing” response. Many transforming growth factor-β (TGF-β) ligands are potent drivers of ECM deposition, and additionally, have a natural affinity for the ECM, creating a concentrated pool of pro-fibrotic factors at the site of injury. Consequently, TGF-β ligands are upregulated in many human fibrotic conditions and, as such, are attractive targets for fibrosis therapy. Here, we will discuss the contribution of TGF-β proteins in the pathogenesis of fibrosis, and promising anti-fibrotic approaches that target TGF-β ligands.

Bone Morphogenetic Protein-7 Suppresses TGFβ2-Induced Epithelial-Mesenchymal Transition in the Lens: Implications for Cataract Prevention

Purpose

Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a key pathologic mechanism underlying cataract. Two members of the transforming growth factor-β (TGFβ) superfamily, TGFβ and bone morphogenetic protein-7 (BMP-7) have functionally distinct roles in EMT. While TGFβ is a potent inducer of EMT, BMP-7 counteracts the fibrogenic activity of TGFβ. We examine the modulating effect of BMP-7 on TGFβ-induced EMT in LECs.

Methods

Rat lens epithelial explants were treated exogenously with TGFβ2 alone or in combination with BMP-7 for up to 5 days. Expression levels of E-cadherin, β-catenin, α-smooth muscle actin (α-SMA), and phosphorylated downstream Smads were determined using immunofluorescence and Western blotting. Reverse transcriptase quantitative PCR (RT-qPCR) was used to study gene expression levels of EMT markers and downstream BMP target genes, including the Inhibitors of differentiation (Id).

Results

Transforming growth factor-β2 induced LECs to transdifferentiate into myofibroblastic cells. Addition of BMP-7 suppressed TGFβ2-induced α-SMA protein levels and mesenchymal gene expression, with retention of E-cadherin and β-catenin expression to the cell membrane. Addition of BMP-7 prevented lens capsular wrinkling and cellular loss associated with TGFβ2-induced EMT over the 5-day treatment period. The inhibitory effect of BMP-7 was accompanied by an early induction of pSmad1/5 and suppression of TGFβ2-induced pSmad2/3. Treatment with TGFβ2 alone suppressed gene expression of Id2/3 and addition of BMP-7 restored Id2/3 expression.

Conclusions

Exogenous administration of BMP-7 abrogated TGFβ2-induced EMT in rat lens epithelial explants. Understanding the complex interplay between the TGFβ- and BMP-7–associated Smad signaling pathways and their downstream target genes holds therapeutic promise in cataract prevention.

Human Fibrotic Diseases: Current Challenges in Fibrosis Research

Human fibrotic diseases constitute a major health problem worldwide owing to the large number of affected individuals, the incomplete knowledge of the fibrotic process pathogenesis, the marked heterogeneity in their etiology and clinical manifestations, the absence of appropriate and fully validated biomarkers, and, most importantly, the current void of effective disease-modifying therapeutic agents. The fibrotic disorders encompass a wide spectrum of clinical entities including systemic fibrotic diseases such as systemic sclerosis (SSc), sclerodermatous graft vs. host disease, and nephrogenic systemic fibrosis, as well as numerous organ-specific disorders including radiation-induced fibrosis and cardiac, pulmonary, liver, and kidney fibrosis. Although their causative mechanisms are quite diverse and in several instances have remained elusive, these diseases share the common feature of an uncontrolled and progressive accumulation of fibrotic tissue in affected organs causing their dysfunction and ultimate failure. Despite the remarkable heterogeneity in the etiologic mechanisms responsible for the development of fibrotic diseases and in their clinical manifestations, numerous studies have identified activated myofibroblasts as the common cellular element ultimately responsible for the replacement of normal tissues with nonfunctional fibrotic tissue. Critical signaling cascades, initiated primarily by transforming growth factor-β (TGF-β), but also involving numerous cytokines and signaling molecules which stimulate profibrotic reactions in myofibroblasts, offer potential therapeutic targets. Here, we briefly review the current knowledge of the molecular mechanisms involved in the development of tissue fibrosis and point out some of the most important challenges to research in the fibrotic diseases and to the development of effective therapeutic approaches for this often fatal group of disorders. Efforts to further clarify the complex pathogenetic mechanisms of the fibrotic process should be encouraged to attain the elusive goal of developing effective therapies for these serious, untreatable, and often fatal disorders.