Understanding the origin, activation and regulation of matrix-producing myofibroblasts for treatment of fibrotic disease

Conservative treatment of Peyronie's disease: a guide

PURPOSE

To review the literature on the topic, to suggest a common line of treatment applicable across a wide community of specialists, and to contribute in maintaining the high level of interest in this disease.

METHODS

A comprehensive and exhaustive review of the literature was performed, identifying hundreds of articles on the topic.

RESULTS

Peyronie's disease is a condition that has been recognized, studied, and treated for centuries; despite this, if one excludes surgery in cases in which the deformity is stable, no clear treatment (or line of treatment) is available for complete relief of signs and symptoms. Treatment options were divided into local, oral, and injection therapy, and a wide variety of drugs, remedies, and options were identified.

CONCLUSIONS

Low-intensity extracorporeal shock wave therapy, vacuum therapy, penile traction therapy, phosphodiesterase type 5 inhibitors, hyaluronic acid, and collagenase of Clostridium histolyticum may be recommended only in specific contexts. Further studies on individual options or potential combinations are required.

Phosphodiesterase inhibitor ameliorates senescent changes of renal interstitial pericytes in aging kidney

Pericytes are mesenchymal cells that surround endothelial cells, playing a crucial role in angiogenesis and vessel maturation. Additionally, they are associated with interstitial fibrosis as a major contributor to renal myofibroblasts. In this study, we aim to investigate whether the phosphodiesterase inhibitor, pentoxifylline (PTX), can ameliorate aging-related functional and histological deterioration in the kidney. We subjected aging C57BL/6 mice, dividing into young, aging, and PTX-treated aging groups. Renal function, albuminuria, and histological changes were assessed. Interstitial pericytes were assessed by immunohistochemistry analysis. We examined changes in pericytes in elderly patients using human kidney tissue obtained from healthy kidney donors for kidney transplantation. In vitro experiments with human pericytes and endothelial cells were performed. Aging mice exhibited declined renal function, increased albuminuria, and aging-related histological changes including mesangial expansion and tubulointerstitial fibrosis. Notably, number of pericytes declined in aging kidneys, and myofibroblasts increased. PTX treatment ameliorated albuminuria, histological alterations, and microvascular rarefaction, as well as modulated angiopoietin expression. In vitro experiments showed PTX reduced cellular senescence and inflammation. Human kidney analysis confirmed similar pericyte changes in aging kidneys. The phosphodiesterase inhibitor, PTX preserved microvascular density and improved renal interstitial fibrosis and inflammation in aging mice kidneys. These protective effects were suggested to be associated with the amelioration of pericytes reduction and the transition to myofibroblasts. Additionally, the upregulation of angiopoietin-1 expression may exert potential impacts. To the best of our knowledge, this is the first report on the changes in renal interstitial pericytes in aging human kidneys.

Progress in the treatment and prevention of esophageal stenosis after endoscopic submucosal dissection

The primary treatment for early esophageal cancer and precancerous lesions is endoscopic submucosal dissection (ESD). However, this approach leads to a high incidence of postoperative esophageal stenosis, which can significantly impact a patient's quality of life. While various methods are available to prevent post-ESD esophageal stenosis, their effectiveness varies. Therefore, this study aims to provide an overview of the currently employed methods for preventing post-ESD esophageal stenosis in clinical practice in view of assisting clinical practitioners.

Permissive role of vascular endothelium in fibrosis: focus on the kidney

Fibrosis, the morphologic end-result of a plethora of chronic conditions and the scorch for organ function, has been thoroughly investigated. One aspect of its development and progression, namely the permissive role of vascular endothelium, has been overshadowed by studies into (myo)fibroblasts and TGF-β; thus, it is the subject of the present review. It has been established that tensile forces of the extracellular matrix acting on cells are a prerequisite for mechanochemical coupling, leading to liberation of TGF-β and formation of myofibroblasts. Increased tensile forces are prompted by elevated vascular permeability in response to diverse stressors, resulting in the exudation of fibronectin, fibrinogen/fibrin, and other proteins, all stiffening the extracellular matrix. These processes lead to the development of endothelial cells dysfunction, endothelial-to-mesenchymal transition, premature senescence of endothelial cells, perturbation of blood flow, and gradual obliteration of microvasculature, leaving behind "string" vessels. The resulting microvascular rarefaction is not only a constant companion of fibrosis but also an adjunct mechanism of its progression. The deepening knowledge of the above chain of pathogenetic events involving endothelial cells, namely increased permeability-stiffening of the matrix-endothelial dysfunction-microvascular rarefaction-tissue fibrosis, may provide a roadmap for therapeutic interventions deemed to curtail and reverse fibrosis.

Multifaceted TGF-β signaling, a master regulator: From bench-to-bedside, intricacies, and complexities

Physiological embryogenesis and adult tissue homeostasis are regulated by transforming growth factor-β (TGF-β), an evolutionarily conserved family of secreted polypeptide factors, acting in an autocrine and paracrine manner. The role of TGF-β in inflammation, fibrosis, and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, especially fibrosis and cancer, overexpressed TGF-β causes extracellular matrix deposition, epithelial-mesenchymal transition, cancer-associated fibroblast formation, and/or angiogenesis. In this review article, we have tried to dive deep into the mechanism of action of TGF-β in inflammation, fibrosis, and carcinogenesis. As TGF-β and its downstream signaling mechanism are implicated in fibrosis and carcinogenesis blocking this signaling mechanism appears to be a promising avenue. However, targeting TGF-β carries substantial risk as this pathway is implicated in multiple homeostatic processes and is also known to have tumor-suppressor functions. There is a need for careful dosing of TGF-β drugs for therapeutic use and patient selection.

WNT-dependent interaction between inflammatory fibroblasts and FOLR2+ macrophages promotes fibrosis in chronic kidney disease

Chronic kidney disease (CKD) is a public health problem driven by myofibroblast accumulation, leading to interstitial fibrosis. Heterogeneity is a recently recognized characteristic in kidney fibroblasts in CKD, but the role of different populations is still unclear. Here, we characterize a proinflammatory fibroblast population (named CXCL-iFibro), which corresponds to an early state of myofibroblast differentiation in CKD. We demonstrate that CXCL-iFibro co-localize with macrophages in the kidney and participate in their attraction, accumulation, and switch into FOLR2+ macrophages from early CKD stages on. In vitro, macrophages promote the switch of CXCL-iFibro into ECM-secreting myofibroblasts through a WNT/β-catenin-dependent pathway, thereby suggesting a reciprocal crosstalk between these populations of fibroblasts and macrophages. Finally, the detection of CXCL-iFibro at early stages of CKD is predictive of poor patient prognosis, which shows that the CXCL-iFibro population is an early player in CKD progression and demonstrates the clinical relevance of our findings.

Natural products in traditional Chinese medicine: molecular mechanisms and therapeutic targets of renal fibrosis and state-of-the-art drug delivery systems

Renal fibrosis (RF) is the end stage of several chronic kidney diseases. Its series of changes include excessive accumulation of extracellular matrix, epithelial-mesenchymal transition (EMT) of renal tubular cells, fibroblast activation, immune cell infiltration, and renal cell apoptosis. RF can eventually lead to renal dysfunction or even renal failure. A large body of evidence suggests that natural products in traditional Chinese medicine (TCM) have great potential for treating RF. In this article, we first describe the recent advances in RF treatment by several natural products and clarify their mechanisms of action. They can ameliorate the RF disease phenotype, which includes apoptosis, endoplasmic reticulum stress, and EMT, by affecting relevant signaling pathways and molecular targets, thereby delaying or reversing fibrosis. We also present the roles of nanodrug delivery systems, which have been explored to address the drawback of low oral bioavailability of natural products. This may provide new ideas for using natural products for RF treatment. Finally, we provide new insights into the clinical prospects of herbal natural products.

FOXO3 Activation Prevents Cellular Senescence in Emphysema Induced by Cigarette Smoke

Because cigarette smoke can induce COPD/emphysema through accelerating senescence with or without an incomplete repair system. However, the pathogenesis of COPD following lung senescence induced by CS is not fully understood. Airspace enlargement and airway epithelial cell senescence are common finding during the COPD development. We investigated the lung tress response to CS and demonstrated that a stress-responsive transcription factor, FOXO3, was regulated by deacetylase. SIRT1 inhibited FOXO3 acetylation and FOXO3 degradation, leading to FOXO3 accumulation and activation in airway epithelial cells. CS exposure activated SIRT1 contributed to FOXO3 activation and functioned to protect lungs, as deletion of SIRT1 decreased CS-induced FOXO3 activation and resulted in more severe airway epithelial cells senescence airspace enlargement. Strikingly, deletion of FOXO3 during the development of COPD aggravated lung structural and functional damage, leading to a much more profound COPD phenotype. We show that deletion of FOXO3 resulted in decreased autophagic response and increased senescence, which may explain lung protection by FOXO3. Our study indicates that in the COPD, stress-responsive transcription factors can be activated for adaptions to counteract senescence insults, thus attenuating COPD development.

Mapping cardiac remodeling in chronic kidney disease

Patients with advanced chronic kidney disease (CKD) mostly die from sudden cardiac death and recurrent heart failure. The mechanisms of cardiac remodeling are largely unclear. To dissect molecular and cellular mechanisms of cardiac remodeling in CKD in an unbiased fashion, we performed left ventricular single-nuclear RNA sequencing in two mouse models of CKD. Our data showed a hypertrophic response trajectory of cardiomyocytes with stress signaling and metabolic changes driven by soluble uremia-related factors. We mapped fibroblast to myofibroblast differentiation in this process and identified notable changes in the cardiac vasculature, suggesting inflammation and dysfunction. An integrated analysis of cardiac cellular responses to uremic toxins pointed toward endothelin-1 and methylglyoxal being involved in capillary dysfunction and TNFα driving cardiomyocyte hypertrophy in CKD, which was validated in vitro and in vivo. TNFα inhibition in vivo ameliorated the cardiac phenotype in CKD. Thus, interventional approaches directed against uremic toxins, such as TNFα, hold promise to ameliorate cardiac remodeling in CKD.

Artificial Skin Therapies; Strategy for Product Development

Significance: Tissue-engineered artificial skin for clinical reconstruction can be regarded as an established practice. Bi-layered skin equivalents are available as established allogenic or autologous therapy, and various acellular skin replacements can support tissue repair. Moreover, there is considerable commonality between the skin and other soft tissue reconstruction products. This article presents an attempt to create a comprehensive global landscape review of advanced replacement materials and associated strategies for skin and soft tissue reconstruction. Recent Advances: There has been rapid growth in the number of commercial and pre-commercial products over the past decade. In this survey, 263 base products for advanced skin therapy have been identified, across 8 therapeutic categories, giving over 350 products in total. The largest market is in the United States, followed by the E.U. zone. However, despite these advances, and the investment of resources in each product development, there are key issues concerning the clinical efficacy, cost-benefit of products, and clinical impact. Each therapeutic strategy has relative merits and limitations. Critical Issues: A critical consideration in developing and evaluating products is the therapeutic modality, associated regulatory processes, and the potential for clinical adoption geographically, determined by regulatory territory, intellectual property, and commercial distribution factors. The survey identifies an opportunity for developments that improve basic efficacy or cost-benefit. Future Directions: The economic pressures on health care systems, compounded by the demands of our increasingly ageing population, and the imperative to distribute effective health care, create an urgent global need for effective and affordable products.

New insight into the role of fibroblasts in the epithelial immune microenvironment in the single-cell era

The skin is exposed to environmental challenges and contains heterogeneous cell populations such as epithelial cells, stromal cells, and skin-resident immune cells. As the most abundant type of stromal cells, fibroblasts have been historically considered silent observers in the immune responses of the cutaneous epithelial immune microenvironment (EIME), with little research conducted on their heterogeneity and immune-related functions. Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) have overcome the limitations of bulk RNA sequencing and help recognize the functional and spatial heterogeneity of fibroblasts, as well as their crosstalk with other types of cells in the cutaneous EIME. Recently, emerging single-cell sequencing data have demonstrated that fibroblasts notably participate in the immune responses of the EIME and impact the initiation and progression of inflammatory skin diseases. Here, we summarize the latest advances in the role of fibroblasts in the cutaneous EIME of inflammatory skin diseases and discuss the distinct functions and molecular mechanisms of activated fibroblasts in fibrotic skin diseases and non-fibrotic inflammatory skin diseases. This review help unveil the multiple roles of fibroblasts in the cutaneous EIME and offer new promising therapeutic strategies for the management of inflammatory skin diseases by targeting fibroblasts or the fibroblast-centered EIME.

A review of hydrogels used in endoscopic submucosal dissection for intraoperative submucosal cushions and postoperative management

Endoscopic submucosal dissection (ESD) has been clinically proved to have prominent advantages in the treatment of early gastrointestinal cancers over traditional surgery, including less trauma, fewer complications, a quicker recovery and lower costs. During the procedure of ESD, appropriate and multifunctional submucosal injected materials (SIMs) as submucosal cushions play an important role, however, even with many advances in design strategies of SIMs over the past decades, the performance of the submucosal cushions with postoperative management function seems to be still unsatisfactory. In this review, we gave a brief historical recount about the clinical development of SIMs, then some common applications of hydrogels used as SIMs in ESD were summarized, while an account of the universal challenges during ESD procedure was also outlined. Going one step further, some cutting-edge functional strategies of hydrogels for novel applications in ESD were exhibited. Finally, we concluded the advantages of hydrogels as SIMs for ESD as well as the treatment dilemma clinicians faced when it comes to deeply infiltrated lesions, some technical perspectives about linking the clinical demand with commercial supply were also proposed. Encompassing the basic elements of SIMs used in ESD surgery and the corresponding postoperative management requirements, this review could be a good reference for relevant practitioners in expanding the research horizon and improving the well-being index of patients.

A roadmap for developing and engineering in vitro pulmonary fibrosis models

Idiopathic pulmonary fibrosis (IPF) is a severe form of pulmonary fibrosis. IPF is a fatal disease with no cure and is challenging to diagnose. Unfortunately, due to the elusive etiology of IPF and a late diagnosis, there are no cures for IPF. Two FDA-approved drugs for IPF, nintedanib and pirfenidone, slow the progression of the disease, yet fail to cure or reverse it. Furthermore, most animal models have been unable to completely recapitulate the physiology of human IPF, resulting in the failure of many drug candidates in preclinical studies. In the last few decades, the development of new IPF drugs focused on changes at the cellular level, as it was believed that the cells were the main players in IPF development and progression. However, recent studies have shed light on the critical role of the extracellular matrix (ECM) in IPF development, where the ECM communicates with cells and initiates a positive feedback loop to promote fibrotic processes. Stemming from this shift in the understanding of fibrosis, there is a need to develop in vitro model systems that mimic the human lung microenvironment to better understand how biochemical and biomechanical cues drive fibrotic processes in IPF. However, current in vitro cell culture platforms, which may include substrates with different stiffness or natural hydrogels, have shortcomings in recapitulating the complexity of fibrosis. This review aims to draw a roadmap for developing advanced in vitro pulmonary fibrosis models, which can be leveraged to understand better different mechanisms involved in IPF and develop drug candidates with improved efficacy. We begin with a brief overview defining pulmonary fibrosis and highlight the importance of ECM components in the disease progression. We focus on fibroblasts and myofibroblasts in the context of ECM biology and fibrotic processes, as most conventional advanced in vitro models of pulmonary fibrosis use these cell types. We transition to discussing the parameters of the 3D microenvironment that are relevant in pulmonary fibrosis progression. Finally, the review ends by summarizing the state of the art in the field and future directions.

Regulation of pericyte metabolic reprogramming restricts the AKI to CKD transition

BACKGROUND AND AIMS

Acute kidney injury (AKI) is associated with high morbidity and mortality and is recognized as a long-term risk factor for progression to chronic kidney disease (CKD). The AKI to CKD transition is characterized by interstitial fibrosis and the proliferation of collagen-secreting myofibroblasts. Pericytes are the major source of myofibroblasts in kidney fibrosis. However, the underlying mechanism of pericyte-myofibroblast transition (PMT) is still unclear. Here we investigated the role of metabolic reprogramming in PMT.

METHODS

Unilateral ischemia/reperfusion-induced AKI to CKD mouse model and TGF-β-treated pericyte-like cells were used to detect the levels of fatty acid oxidation (FAO) and glycolysis, and the critical signaling pathways during PMT under the treatment of drugs regulating metabolic reprogramming.

RESULTS

PMT is characterized by a decrease in FAO and an increase in glycolysis. Enhancement of FAO by the peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α) activator ZLN-005 or suppression of glycolysis by the hexokinase 2 (HK2) inhibitor 2-DG can inhibit PMT, preventing the transition of AKI to CKD. Mechanistically, AMPK modulates various pathways involved in the metabolic switch from glycolysis to FAO. Specifically, the PGC1α-CPT1A pathway activates FAO, while inhibition of the HIF1α-HK2 pathway drives glycolysis inhibition. The modulations of these pathways by AMPK contribute to inhibiting PMT.

CONCLUSIONS

Metabolic reprogramming controls the fate of pericyte transdifferentiation and targets the abnormal metabolism of pericytes can effectively prevent AKI to CKD transition.

Platelet-instructed SPP1+ macrophages drive myofibroblast activation in fibrosis in a CXCL4-dependent manner

Fibrosis represents the common end stage of chronic organ injury independent of the initial insult, destroying tissue architecture and driving organ failure. Here we discover a population of profibrotic macrophages marked by expression of Spp1, Fn1, and Arg1 (termed Spp1 macrophages), which expands after organ injury. Using an unbiased approach, we identify the chemokine (C-X-C motif) ligand 4 (CXCL4) to be among the top upregulated genes during profibrotic Spp1 macrophage differentiation. In vitro and in vivo studies show that loss of Cxcl4 abrogates profibrotic Spp1 macrophage differentiation and ameliorates fibrosis after both heart and kidney injury. Moreover, we find that platelets, the most abundant source of CXCL4 in vivo, drive profibrotic Spp1 macrophage differentiation. Single nuclear RNA sequencing with ligand-receptor interaction analysis reveals that macrophages orchestrate fibroblast activation via Spp1, Fn1, and Sema3 crosstalk. Finally, we confirm that Spp1 macrophages expand in both human chronic kidney disease and heart failure.

Endothelial-mesenchymal transition as a novel mechanism for generating myofibroblasts during wound healing and scarring

BACKGROUND

The endothelial-mesenchymal transition (EndMT) is an important mechanism in tissue regeneration and the development of organ fibrosis. Whether EndMT occurs in wound healing and scarring remains unknown.

MATERIALS AND METHODS

The isolated cells from the normal dermal tissue and the wound tissue of mouse with full-thickness skin wound, and human scar tissue sections were performed with CD31/factorVII and α-SMA immunohistochemical staining and H and E staining. The ratio of factor VII or CD31/α-SMA double-positive cells in factor VII-positive cells was assessed in the isolated cells and in scar tissues.

RESULTS

In this study, we found that approximately 27-60% of ECs coexpressed VII factor and α-SMA in the isolated cells from the wound tissues of mice, which was significantly higher than that of normal dermal tissue cells. Accordingly, the number of CD31/α-SMA double-positive cells in mouse wound tissue sections was also significantly more than that in normal dermal tissue sections. In scar tissues, in addition to high-density microvessels, a large number of proliferative ECs in scar strama and CD31/α-SMA double-positive cells were also found. Approximately 46.82 to 84.11% of ECs and 68.77 to 95.25% of myofibroblasts coexpressed VII factor and α-SMA, and these two values in hypertrophic scars were significantly higher than those in keloids.

CONCLUSION

These results confirmed that ECs might contribute to the emergence of myofibroblasts in the wound and scar tissue via the process of EndMT.

Single-cell methods in myeloproliferative neoplasms: old questions, new technologies

Myeloproliferative neoplasms (MPN) are a group of clonal stem cell-derived hematopoietic malignancies driven by aberrant Janus kinase-signal transducer and activator of transcription proteins (JAK/STAT) signaling. Although these are genetically simple diseases, MPNs are phenotypically heterogeneous, reflecting underlying intratumoral heterogeneity driven by the interplay of genetic and nongenetic factors. Their evolution is determined by factors that enable certain cellular subsets to outcompete others. Therefore, techniques that resolve cellular heterogeneity at the single-cell level are ideally placed to provide new insights into MPN biology. With these insights comes the potential to uncover new approaches to predict the clinical course and treat these cancers, ultimately improving outcomes for patients. MPNs present a particularly tractable model of cancer evolution, because most patients present in an early disease phase and only a small proportion progress to aggressive disease. Therefore, it is not surprising that many groundbreaking technological advances in single-cell omics have been pioneered by their application in MPNs. In this review article, we explore how single-cell approaches have provided transformative insights into MPN disease biology, which are broadly applicable across human cancers, and discuss how these studies might be swiftly translated into clinical pathways and may eventually underpin precision medicine.

Myofibroblast-dominant proliferation associated with severe fibrosis in bulbar urethral strictures

OBJECTIVES

Myofibroblast-dominant proliferation (relative to fibroblast proliferation) is the key process in urethral fibrosis, but its association with clinical features is not understood. We conducted a histological analysis of urethral strictures and examined the association between myofibroblast proliferation and stricture characteristics.

METHODS

Formalin-fixed, paraffin-embedded urethral sections sliced axially from 175 male patients with bulbar urethral strictures were retrospectively analyzed. All patients underwent excision and primary anastomosis between September 2008 and January 2021 by a surgeon (AH). Masson's trichrome stain was used to estimate the area of fibrosis. Corresponding unstained slides with the largest area of fibrosis were selected and double-immunostained with anti-smooth muscle actin (SMA) and anti-TE-7 mouse monoclonal antibodies for the assessment of myofibroblasts and fibroblasts, respectively. The ratio of the number of SMA-positive cells to the number of TE-7-positive cells (SMA/TE-7 ratio) was calculated.

RESULTS

The area of fibrosis in strictures due to perineal trauma (n = 85, median 108.9 mm² ) was significantly larger than that in non-traumatic strictures (n = 90, median 42.9 mm² , p < 0.0001). The area of fibrosis positively correlated with SMA expression (r = 0.35, p < 0.0001) and the SMA/TE-7 ratio (r = 0.36, p < 0.0001), but not with TE-7 expression (r = -0.01, p = 0.75). In a multivariate linear regression model, traumatic etiology (standard coefficient 0.37, t value 3.9, p < 0.0001) and increased SMA expression (standard coefficient 0.17, t value 2.1, p = 0.03) were the predictors of wide fibrosis area.

CONCLUSIONS

Myofibroblast-dominant proliferation may contribute to the pathogenesis of severe urethral fibrosis.

Myofibroblast depletion reduces kidney cyst growth and fibrosis in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) involves the development and persistent growth of fluid filled kidney cysts. In a recent study, we showed that ADPKD kidney cyst epithelial cells can stimulate the proliferation and differentiation of peri-cystic myofibroblasts. Although dense myofibroblast populations are often found surrounding kidney cysts, their role in cyst enlargement or fibrosis in ADPKD is unclear. To clarify this, we examined the effect of myofibroblast depletion in the Pkd1RC/RC (RC/RC) mouse model of ADPKD. RC/RC;αSMAtk mice that use the ganciclovir-thymidine kinase system to selectively deplete α-smooth muscle actin expressing myofibroblasts were generated. Ganciclovir treatment for four weeks depleted myofibroblasts, reduced kidney fibrosis and preserved kidney function in these mice. Importantly, myofibroblast depletion significantly reduced cyst growth and cyst epithelial cell proliferation in RC/RC;αSMAtk mouse kidneys. Similar ganciclovir treatment did not alter cyst growth or fibrosis in wild-type or RC/RC littermates. In vitro, co-culture with myofibroblasts from the kidneys of patients with ADPKD increased 3D microcyst growth of human ADPKD cyst epithelial cells. Treatment with conditioned culture media from ADPKD kidney myofibroblasts increased microcyst growth and cell proliferation of ADPKD cyst epithelial cells. Further examination of ADPKD myofibroblast conditioned media showed high levels of protease inhibitors including PAI1, TIMP1 and 2, NGAL and TFPI-2, and treatment with recombinant PAI1 and TIMP1 increased ADPKD cyst epithelial cell proliferation in vitro. Thus, our findings show that myofibroblasts directly promote cyst epithelial cell proliferation, cyst growth and fibrosis in ADPKD kidneys, and their targeting could be a novel therapeutic strategy to treat PKD.

Emerging role of tumor suppressor p53 in acute and chronic kidney diseases

p53 is a major regulator of cell cycle arrest, apoptosis, and senescence. While involvement of p53 in tumorigenesis is well established, recent studies implicate p53 in the initiation and progression of several renal diseases, which is the focus of this review. Ischemic-, aristolochic acid (AA) -, diabetic-, HIV-associated-, obstructive- and podocyte-induced nephropathies are accompanied by activation and/or elevated expression of p53. Studies utilizing chemical or renal-specific inhibition of p53 in mice confirm the pathogenic role of this transcription factor in acute kidney injury and chronic kidney disease. TGF-β1, NOX, ATM/ATR kinases, Cyclin G, HIPK, MDM2 and certain micro-RNAs are important determinants of renal p53 function in response to trauma. AA, cisplatin or TGF-β1-mediated ROS generation via NOXs promotes p53 phosphorylation and subsequent tubular dysfunction. p53-SMAD3 transcriptional cooperation downstream of TGF-β1 orchestrates induction of fibrotic factors, extracellular matrix accumulation and pathogenic renal cell communication. TGF-β1-induced micro-RNAs (such as mir-192) could facilitate p53 activation, leading to renal hypertrophy and matrix expansion in response to diabetic insults while AA-mediated mir-192 induction regulates p53 dependent epithelial G2/M arrest. The widespread involvement of p53 in tubular maladaptive repair, interstitial fibrosis, and podocyte injury indicate that p53 clinical targeting may hold promise as a novel therapeutic strategy for halting progression of certain acute and chronic renal diseases, which affect hundreds of million people worldwide.

Influence of sphingomyelin metabolism during epithelial-mesenchymal transition associated with aging in the renal papilla

The renal collecting ducts (CD) are formed by a fully differentiated epithelium, and their tissue organization and function require the presence of mature cell adhesion structures. In certain circumstances, the cells can undergo de-differentiation by a process called epithelial-mesenchymal transition (EMT), in which the cells lose their epithelial phenotype and acquire the characteristics of the mesenchymal cells, which includes loss of cell-cell adhesion. We have previously shown that in renal papillary CD cells, cell adhesion structures are located in sphingomyelin (SM)-enriched plasma membrane microdomains and the inhibition of SM synthase 1 activity induced CD cells to undergo an EMT process. In the present study, we evaluated the influence of SM metabolism during the EMT of the cells that form the CD of the renal papilla during aging. To this end, primary cultures of renal papillary CD cells from young, middle-, and aged-rats were performed. By combining biochemical and immunofluorescence studies, we found experimental evidence that CD cells undergo an increase in spontaneous and reversible EMT during aging and that at least one of the reasons for this phenomenon is the decrease in SM content due to the combination of decreased SM synthase activity and an increase in SM degradation mediated by neutral sphingomyelinase. Age is a risk factor for many diseases, among which renal fibrosis is included. Our findings highlight the importance of sphingolipids and particularly SM as a modulator of the fate of CD cells and probably contribute to the development of treatments to avoid or reverse renal fibrosis during aging.

P144 a Transforming Growth Factor Beta Inhibitor Peptide, Generates Antifibrogenic Effects in a Radiotherapy Induced Fibrosis Model

Radiation-induced fibrosis (RIF) is a severe side effect related with soft tissues sarcomas (STS) radiotherapy. RIF is a multicellular process initiated primarily by TGF-β1 that is increased in irradiated tissue, whose signaling leads to intracellular Smad2/3 phosphorylation and further induction of profibrotic target genes. P144 (Disetertide©) is a peptide inhibitor of TGF-β1 and is proposed as a candidate compound for reducing RIF associated wound healing problems and muscle fibrosis in STS. Methods: A treatment and control group of WNZ rabbits were employed to implement a brachytherapy animal model, through catheter implantation at the lower limb. Two days after implantation, animals received 20 Gy isodosis, intended to induce a high RIF grade. The treatment group received intravenous P144 administration following a brachytherapy session, repeated at 24–72 h post-radiation, while the control group received placebo. Four weeks later, affected muscular tissues underwent histological processing for collagen quantification and P-Smad2/3 immunohistochemistry through image analysis. Results: High isodosis Brachytherapy produced remarkable fibrosis in this experimental model. Results showed retained macro and microscopical morphology of muscle in the P144 treated group, with reduced extracellular matrix fibrosis, with a lower area of collagen deposition measured through Masson’s trichrome staining. Intravenous P144 also induced a significant reduction in Smad2/3 phosphorylation levels compared with the placebo group. Conclusions: P144 administration clearly reduces RIF and opens a new potential co-treatment approach to reduce complications in soft tissue sarcoma (STS) radiotherapy. Further studies are required to establish whether the dosage and timing optimization of P144 administration, in different RIF phases, might entirely avoid fibrosis associated with STS brachytherapy.

Folic acid-mediated fibrosis is driven by C5a receptor 1-mediated activation of kidney myeloid cells

We previously reported that increased expression and activation of kidney cell complement components play an important role in the pathogenesis of renal scarring. Here we used floxed green fluorescent protein (GFP)-C5a receptor 1 (C5aR1) knock-in mice (GFP-C5ar1^fl/fl) and the model of Folic acid-induced kidney injury to define the cell types and potential mechanisms by which increased C5aR1 activation leads to fibrosis. Using flow cytometry and confocal microscopy we identified macrophages as the major interstitial cell type showing increased expression of C5aR1 in FA-treated mice. C5ar1^fl/fl.Lyz2Cre^+/- mice, in which C5aR1 has been specifically deleted in lysozyme M (LysM)-expressing myeloid cells, experienced reduced fibrosis when compared to control C5ar1^fl/fl mice. Examination of C5aR1-expressing macrophage transcriptomes by gene set enrichment analysis (GSEA) demonstrated that these cells were enriched in pathways corresponding to the complement cascade, collagen formation and the NABA matrisome, strongly pointing to their critical roles in tissue repair/scarring. Since C5aR1 was also detected in a small population of PDGFBR+ GFP+ cells we develop C5ar1^fl/fl.Foxd1Cre^+/- mice, in which C5aR1 is deleted specifically in pericytes, and found reduced FA-induced fibrosis. Primary cell cultures of platelet-derived growth factor receptor beta (PDGFRβ)+ pericytes isolated from FA-treated C5ar1^fl/fl.Foxd1Cre^+/- mice showed reduced secretion of several cytokines, including IL-6, and macrophage inflammatory proteins (MIP) 2, when compared to pericytes isolated from FA-treated control GFP-C5ar1^fl/fl mice. Collectively, these data imply that the C5a/C5aR1 axis activation primarily in interstitial cells contributes to the development of renal fibrosis.

Genetically engineered FGF1-sericin hydrogel material treats intrauterine adhesion and restores fertility in rat

Endometrial injury can cause intrauterine adhesions (IUA) and induce the formation of endometrial fibrosis, leading to infertility and miscarriage. At present, there is no effective treatment method for severe IUA and uterine basal injury with adhesion area larger than 1/3 of the uterus. In this study, we prepared FGF1 silk sericin hydrogel material (FGF1-SS hydrogel) to treat endometrial injury and prevent endometrial fibrosis. Compared with the silk sericin hydrogel material (WT-SS hydrogel), FGF1-SS hydrogel significantly promotes the cell migration and infiltration ability of endometrial stromal cells (ESCs). More importantly, FGF1-SS hydrogel can release FGF1 stably for a long time and inhibit The ESCs injury model forms fibrosis through the TGF-β/Smad pathway. In the IUA rat model, FGF1-SS hydrogel treatment effectively restored the number of uterine glands and uterine wall thickness in rats, with a fertility rate of 65.1 ± 6.4%. The results show that FGF1-SS hydrogel is expected to be a candidate to prevent IUA.

Deletion of STAT3 from Foxd1 cell population protects mice from kidney fibrosis by inhibiting pericytes trans-differentiation and migration

Signal transduction and activator of transcription 3 (STAT3) is a key transcription factor implicated in the pathogenesis of kidney fibrosis. Although Stat3 deletion in tubular epithelial cells is known to protect mice from fibrosis, vFoxd1 cells remains unclear. Using Foxd1-mediated Stat3 knockout mice, CRISPR, and inhibitors of STAT3, we investigate its function. STAT3 is phosphorylated in tubular epithelial cells in acute kidney injury, whereas it is expanded to interstitial cells in fibrosis in mice and humans. Foxd1-mediated deletion of Stat3 protects mice from folic-acid- and aristolochic-acid-induced kidney fibrosis. Mechanistically, STAT3 upregulates the inflammation and differentiates pericytes into myofibroblasts. STAT3 activation increases migration and profibrotic signaling in genome-edited, pericyte-like cells. Conversely, blocking Stat3 inhibits detachment, migration, and profibrotic signaling. Furthermore, STAT3 binds to the Collagen1a1 promoter in mouse kidneys and cells. Together, our study identifies a previously unknown function of STAT3 that promotes kidney fibrosis and has therapeutic value in fibrosis.

Inflammation, Fibrosis and Cancer: Mechanisms, Therapeutic Options and Challenges

Uncontrolled inflammation is a salient factor in multiple chronic inflammatory diseases and cancers. In this review, we provided an in-depth analysis of the relationships and distinctions between uncontrolled inflammation, fibrosis and cancers, while emphasizing the challenges and opportunities of developing novel therapies for the treatment and/or management of these diseases. We described how drug delivery systems, combination therapy and the integration of tissue-targeted and/or pathways selective strategies could overcome the challenges of current agents for managing and/or treating chronic inflammatory diseases and cancers. We also recognized the value of the re-evaluation of the disease-specific roles of multiple pathways implicated in the pathophysiology of chronic inflammatory diseases and cancers-as well as the application of data from single-cell RNA sequencing in the success of future drug discovery endeavors.

Donor-But Not Recipient-Derived Cells Produce Collagen-1 in Chronically Rejected Cardiac Allografts

Fibrosis is a prominent feature of chronic allograft rejection, caused by an excessive production of matrix proteins, including collagen-1. Several cell types produce collagen-1, including mesenchymal fibroblasts and cells of hematopoietic origin. Here, we sought to determine whether tissue-resident donor-derived cells or allograft-infiltrating recipient-derived cells are responsible for allograft fibrosis, and whether hematopoietic cells contribute to collagen production. A fully MHC-mismatched mouse heterotopic heart transplantation model was used, with transient depletion of CD4⁺ T cells to prevent acute rejection. Collagen-1 was selectively knocked out in recipients or donors. In addition, collagen-1 was specifically deleted in hematopoietic cells. Tissue-resident macrophages were depleted using anti-CSF1R antibody. Allograft fibrosis and inflammation were quantified 20 days post-transplantation. Selective collagen-1 knock-out in recipients or donors showed that tissue-resident cells from donor hearts, but not infiltrating recipient-derived cells, are responsible for production of collagen-1 in allografts. Cell-type-specific knock-out experiments showed that hematopoietic tissue-resident cells in donor hearts substantially contributed to graft fibrosis. Tissue resident macrophages, however, were not responsible for collagen-production, as their deletion worsened allograft fibrosis. Donor-derived cells including those of hematopoietic origin determine allograft fibrosis, making them attractive targets for organ preconditioning to improve long-term transplantation outcomes.

Control of Tissue Fibrosis by 5-Methoxytryptophan, an Innate Anti-Inflammatory Metabolite

Tissue fibrosis causes debilitating human diseases such as liver cirrhosis, heart failure, chronic kidney disease and pulmonary insufficiency. It is a dynamic process orchestrated by specific subsets of monocyte-macrophages, fibroblasts, pericytes and hepatic stellate cells. Fibrosis is linked to tissue inflammation. Pro-inflammatory macrophages promote fibrosis by driving myofibroblast differentiation and macrophage myofibroblast transition. Myofibroblasts express α-smooth muscle cell actin (α-SMA) and secrete extracellular matrix (ECM) proteins notably collagen I and III. Deposition of ECM proteins at injury sites and interstitial tissues distorts normal structure and impairs vital functions. Despite advances in the mechanisms of fibrosis at cellular, molecular and genetic levels, prevention and treatment of fibrotic diseases remain poorly developed. Recent reports suggest that 5-methoxytryptophan (5-MTP) is effective in attenuating injury-induced liver, kidney, cardiac and pulmonary fibrosis. It inhibits macrophage activation and blocks fibroblast differentiation to myofibroblasts. Furthermore, it inhibits hepatic stellate cell differentiation into myofibroblasts. As 5-MTP is an endogenous molecule derived from tryptophan catabolism via tryptophan hydroxylase pathway, it is well-suited as a lead compound for developing new anti-fibrotic drugs. This article provides an overview of 5-MTP synthesis, and a critical review of its anti-fibrotic activities. Its mechanisms of actions and potential therapeutic value will be discussed.

SARS-CoV-2 infects the human kidney and drives fibrosis in kidney organoids

Kidney failure is frequently observed during and after COVID-19, but it remains elusive whether this is a direct effect of the virus. Here, we report that SARS-CoV-2 directly infects kidney cells and is associated with increased tubule-interstitial kidney fibrosis in patient autopsy samples. To study direct effects of the virus on the kidney independent of systemic effects of COVID-19, we infected human-induced pluripotent stem-cell-derived kidney organoids with SARS-CoV-2. Single-cell RNA sequencing indicated injury and dedifferentiation of infected cells with activation of profibrotic signaling pathways. Importantly, SARS-CoV-2 infection also led to increased collagen 1 protein expression in organoids. A SARS-CoV-2 protease inhibitor was able to ameliorate the infection of kidney cells by SARS-CoV-2. Our results suggest that SARS-CoV-2 can directly infect kidney cells and induce cell injury with subsequent fibrosis. These data could explain both acute kidney injury in COVID-19 patients and the development of chronic kidney disease in long COVID.

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COVID-19 patients present tubulo-interstitial kidney fibrosis compared with controls

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SARS-CoV-2 infection stimulates profibrotic signaling in human kidney organoids

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SARS-CoV-2 infection can be inhibited by a protease blocker in human kidney organoids

Chromatin-accessibility estimation from single-cell ATAC-seq data with scOpen

A major drawback of single-cell ATAC-seq (scATAC-seq) is its sparsity, i.e., open chromatin regions with no reads due to loss of DNA material during the scATAC-seq protocol. Here, we propose scOpen, a computational method based on regularized non-negative matrix factorization for imputing and quantifying the open chromatin status of regulatory regions from sparse scATAC-seq experiments. We show that scOpen improves crucial downstream analysis steps of scATAC-seq data as clustering, visualization, cis-regulatory DNA interactions, and delineation of regulatory features. We demonstrate the power of scOpen to dissect regulatory changes in the development of fibrosis in the kidney. This identifies a role of Runx1 and target genes by promoting fibroblast to myofibroblast differentiation driving kidney fibrosis.

Roles of the Mesenchymal Stromal/Stem Cell Marker Meflin/Islr in Cancer Fibrosis

Fibroblasts synthesise the extracellular matrix (ECM) such as collagen and elastin, the excessive accumulation of which can lead to fibrosis and organ dysfunction under pathological conditions. Cancer-associated fibroblasts (CAFs) are major constituents of the tumour microenvironment (TME) that accompany the desmoplastic reaction responsible for anti-cancer treatment resistance. Thus, it is important to dissect the roles of CAFs in the TME to develop new therapeutic strategies for refractory cancers. Recent progress in the studies of CAF biology suggests that the functions of CAFs are complicated and that they are composed of functionally distinct populations, including cancer-promoting CAFs (pCAFs) and cancer-restraining CAFs (rCAFs). We recently identified a new cell surface marker for rCAFs in pancreatic and colon cancers, designated as Meflin (mesenchymal stromal cell- and fibroblast-expressing Linx paralogue)/Islr (immunoglobulin super family containing leucine-rich repeat). Based on the distribution of Meflin/Islr-positive cells, we also considered it a specific candidate marker for mesenchymal stroma/stem cells. Meflin/Islr-positive CAFs have been shown to suppress cancer progression by being involved in regulating collagen structures and BMP signalling in the TME. This review describes the function of Meflin/Islr in cancer fibrosis as well as in cardiac and lung fibrosis and its potential in the development of new cancer therapeutics.

Cumulative DNA damage by repeated low-dose cisplatin injection promotes the transition of acute to chronic kidney injury in mice

Cisplatin is a commonly used anticancer drug, but nephrotoxicity is a dose-limiting adverse effect. Recent experimental and clinical observations have demonstrated that multiple injections of cisplatin induce the transition to chronic kidney disease; however, the underlying mechanisms remain unclear. We found that multiple injections of higher doses of cisplatin in a shorter interval affected the severity of kidney injury, causing kidney fibrosis to develop at a later time point. An additional injection of cisplatin during the recovery period after a prior injury, when proximal tubule epithelia are actively proliferating, induced substantial tubular injury by inducing more severe DNA damage than that induced by a single injection. Lineage tracing analysis of proximal tubular epithelia demonstrated that the tubular epithelia that underwent multiple rounds of cell division after multiple injections of cisplatin existed at the chronic phase, and these populations often expressed vcam1 + , suggesting the induction of proinflammatory failed-repair tubular epithelia. Our study revealed that as cisplatin exerts cytotoxic effects on actively proliferating cells, additional cisplatin injections before the completion of tubular repair exacerbates kidney injury through cumulative DNA damage. Appropriate both the setting of dosage and dosing intervals, with careful monitoring, are essential to prevent nephrotoxicity of repeated cisplatin treatment in cancer patients.

Global gene expression analysis of systemic sclerosis myofibroblasts demonstrates a marked increase in the expression of multiple NBPF genes

Myofibroblasts are the key effector cells responsible for the exaggerated tissue fibrosis in Systemic Sclerosis (SSc). Despite their importance to SSc pathogenesis, the specific transcriptome of SSc myofibroblasts has not been described. The purpose of this study was to identify transcriptome differences between SSc myofibroblasts and non-myofibroblastic cells. Alpha smooth muscle actin (α-SMA) expressing myofibroblasts and α-SMA negative cells were isolated employing laser capture microdissection from dermal cell cultures from four patients with diffuse SSc of recent onset. Total mRNA was extracted from both cell populations, amplified and analyzed employing microarrays. Results for specific genes were validated by Western blots and by immunohistochemistry. Transcriptome analysis revealed 97 differentially expressed transcripts in SSc myofibroblasts compared with non-myofibroblasts. Annotation clustering of the SSc myofibroblast-specific transcripts failed to show a TGF-β signature. The most represented transcripts corresponded to several different genes from the Neuroblastoma Breakpoint Family (NBPF) of genes. NBPF genes are highly expanded in humans but are not present in murine or rat genomes. In vitro studies employing cultured SSc dermal fibroblasts and immunohistochemistry of affected SSc skin confirmed increased NBPF expression in SSc. These results indicate that SSc myofibroblasts represent a unique cell lineage expressing a specific transcriptome that includes very high levels of transcripts corresponding to numerous NBPF genes. Elevated expression of NBPF genes in SSc myofibroblasts suggests that NBPF gene products may play a role in SSc pathogenesis and may represent a novel therapeutic target.

Extracellular vesicles from adipose stromal cells combined with a thermoresponsive hydrogel prevent esophageal stricture after extensive endoscopic submucosal dissection in a porcine model

In this study, we investigated the combination of extracellular (nano) vesicles (EVs) from pig adipose tissue-derived stromal cells (ADSCs) and a thermoresponsive gel, Pluronic® F-127 (PF-127), to prevent stricture formation after endoscopic resection in a porcine model. ADSC EVs were produced at a liter scale by a high-yielding turbulence approach from ADSCs 3D cultured in bioreactors and characterized in terms of size, morphology and membrane markers. The thermoresponsive property of the PF-127 gel was assessed by rheology. The pro-regenerative potency of ADSC EVs was investigated ex vivo in esophageal biopsies under starvation. In vivo tests were performed in a porcine model after extended esophageal endoscopic mucosal dissection (ESD). Pigs were randomized into 3 groups: control (n = 6), gel (n = 6) or a combination of 1.45 × 1012 EVs + gel (n = 6). Application of gel ± EVs was performed just after ESD with a follow-up finalized on day 21 post-ESD. There was a trend towards less feeding disorder in the EV + gel group in comparison with the gel and the control groups (16.67% vs. 66.7% vs. 83.33%, respectively) but without reaching a statistically significant difference. A significant decrease in the esophageal stricture rate was confirmed by endoscopic, radiological and histological examination for the EV + gel group. A decrease in the mean fibrosis area and larger regenerated muscularis mucosae were observed for the EV + gel group. In summary, the application of EVs + gel after extended esophageal endoscopic resection succeeded in preventing stricture formation with an anti-fibrotic effect. This nano-therapy may be of interest to tackle an unmet medical need considering that esophageal stricture is the most challenging delayed complication after extended superficial cancer resection by endoscopy.

Fluorescent probes for visualizing ROS-associated proteins in disease

Abnormal expression of proteins, including catalytic and expression dysfunction, is directly related to the development of various diseases in living organisms. Reactive oxygen species (ROS) could regulate protein expression by redox modification or cellular signal pathway and thus influence the development of disease. Determining the expression level and activity of these ROS-associated proteins is of considerable importance in early-stage disease diagnosis and the identification of new drug targets. Fluorescence imaging technology has emerged as a powerful tool for specific in situ imaging of target proteins by virtue of its non-invasiveness, high sensitivity and good spatiotemporal resolution. In this review, we summarize advances made in the past decade for the design of fluorescent probes that have contributed to tracking ROS-associated proteins in disease. We envision that this review will attract significant attention from a wide range of researchers in their utilization of fluorescent probes for in situ investigation of pathological processes synergistically regulated by both ROS and proteins.

Dissecting esophageal squamous-cell carcinoma ecosystem by single-cell transcriptomic analysis

Esophageal squamous-cell carcinoma (ESCC), one of the most prevalent and lethal malignant disease, has a complex but unknown tumor ecosystem. Here, we investigate the composition of ESCC tumors based on 208,659 single-cell transcriptomes derived from 60 individuals. We identify 8 common expression programs from malignant epithelial cells and discover 42 cell types, including 26 immune cell and 16 nonimmune stromal cell subtypes in the tumor microenvironment (TME), and analyse the interactions between cancer cells and other cells and the interactions among different cell types in the TME. Moreover, we link the cancer cell transcriptomes to the somatic mutations and identify several markers significantly associated with patients’ survival, which may be relevant to precision care of ESCC patients. These results reveal the immunosuppressive status in the ESCC TME and further our understanding of ESCC.

Esophageal squamous-cell carcinomas (ESCC) have poor prognosis, and detailed molecular profiles are necessary to identify prognostic markers. Here the authors analyse 60 ESCC patient samples using scRNA-seq, TCR-seq and genomics; they find mucosal immunity markers associated with survival and immunosuppressive microenvironments.

Negative regulators of TGF-β1 signaling in renal fibrosis; pathological mechanisms and novel therapeutic opportunities

Elevated expression of the multifunctional cytokine transforming growth factor β1 (TGF-β1) is causatively linked to kidney fibrosis progression initiated by diabetic, hypertensive, obstructive, ischemic and toxin-induced injury. Therapeutically relevant approaches to directly target the TGF-β1 pathway (e.g., neutralizing antibodies against TGF-β1), however, remain elusive in humans. TGF-β1 signaling is subjected to extensive negative control at the level of TGF-β1 receptor, SMAD2/3 activation, complex assembly and promoter engagement due to its critical role in tissue homeostasis and numerous pathologies. Progressive kidney injury is accompanied by the deregulation (loss or gain of expression) of several negative regulators of the TGF-β1 signaling cascade by mechanisms involving protein and mRNA stability or epigenetic silencing, further amplifying TGF-β1/SMAD3 signaling and fibrosis. Expression of bone morphogenetic proteins 6 and 7 (BMP6/7), SMAD7, Sloan-Kettering Institute proto-oncogene (Ski) and Ski-related novel gene (SnoN), phosphate tensin homolog on chromosome 10 (PTEN), protein phosphatase magnesium/manganese dependent 1A (PPM1A) and Klotho are dramatically decreased in various nephropathies in animals and humans albeit with different kinetics while the expression of Smurf1/2 E3 ligases are increased. Such deregulations frequently initiate maladaptive renal repair including renal epithelial cell dedifferentiation and growth arrest, fibrotic factor (connective tissue growth factor (CTGF/CCN2), plasminogen activator inhibitor type-1 (PAI-1), TGF-β1) synthesis/secretion, fibroproliferative responses and inflammation. This review addresses how loss of these negative regulators of TGF-β1 pathway exacerbates renal lesion formation and discusses the therapeutic value in restoring the expression of these molecules in ameliorating fibrosis, thus, presenting novel approaches to suppress TGF-β1 hyperactivation during chronic kidney disease (CKD) progression.

PAI-1 induction during kidney injury promotes fibrotic epithelial dysfunction via deregulation of klotho, p53, and TGF-β1-receptor signaling

Renal fibrosis leads to chronic kidney disease, which affects over 15% of the U.S. population. PAI-1 is highly upregulated in the tubulointerstitial compartment in several common nephropathies and PAI-1 global ablation affords protection from fibrogenesis in mice. The precise contribution of renal tubular PAI-1 induction to disease progression, however, is unknown and surprisingly, appears to be independent of uPA inhibition. Human renal epithelial (HK-2) cells engineered to stably overexpress PAI-1 underwent dedifferentiation (E-cadherin loss, gain of vimentin), G2/M growth arrest (increased p-Histone3, p21), and robust induction of fibronectin, collagen-1, and CCN2. These cells are also susceptible to apoptosis (elevated cleaved caspase-3, annexin-V positivity) compared to vector controls, demonstrating a previously unknown role for PAI-1 in tubular dysfunction. Persistent PAI-1 expression results in a loss of klotho expression, p53 upregulation, and increases in TGF-βRI/II levels and SMAD3 phosphorylation. Ectopic restoration of klotho in PAI-1-transductants attenuated fibrogenesis and reversed the proliferative defects, implicating PAI-1 in klotho loss in renal disease. Genetic suppression of p53 reversed the PA1-1-driven maladaptive repair, moreover, confirming a pathogenic role for p53 upregulation in this context and uncovering a novel role for PAI-1 in promoting renal p53 signaling. TGF-βRI inhibition also attenuated PAI-1-initiated epithelial dysfunction, independent of TGF-β1 ligand synthesis. Thus, PAI-1 promotes tubular dysfunction via klotho reduction, p53 upregulation, and activation of the TGF-βRI-SMAD3 axis. Since klotho is an upstream regulator of both PAI-1-mediated p53 induction and SMAD3 signaling, targeting tubular PAI-1 expression may provide a novel, multi-level approach to the therapy of CKD.

Platelet-derived growth factor C signaling is a potential therapeutic target for radiation proctopathy

Radiation proctopathy (RP) is characterized by inflammation of colorectal tissue and is a common complication of radiation therapy for pelvic malignancies with high incidence but lacking effective treatment. Here, we found that platelet-derived growth factor C (PDGF-C) and fibrosis markers were up-regulated in tissue samples from patients with RP and in rectal tissues after irradiation in a mouse model of RP. Genetic deletion of Pdgf-c in mice ameliorated RP-induced injuries. Genome-wide gene expression profiling and in vitro assays revealed that the promotive effect of PDGF-C in RP development was mediated by activation of PDGF receptors (PDGFRs) and C-X-C motif chemokine receptor 4, a proinflammatory chemokine regulated by transcription factor ETS variant transcription factor 1. Treatment with crenolanib, a selective inhibitor of PDGFRs, prevented or reduced RP in mice after irradiation. These results reveal that inhibition of PDGF-C signaling may have therapeutic value for the treatment of RP.

The Genomic Response to TGF-β1 Dictates Failed Repair and Progression of Fibrotic Disease in the Obstructed Kidney

Tubulointerstitial fibrosis is a common and diagnostic hallmark of a spectrum of chronic renal disorders. While the etiology varies as to the causative nature of the underlying pathology, persistent TGF-β1 signaling drives the relentless progression of renal fibrotic disease. TGF-β1 orchestrates the multifaceted program of kidney fibrogenesis involving proximal tubular dysfunction, failed epithelial recovery or re-differentiation, capillary collapse and subsequent interstitial fibrosis eventually leading to chronic and ultimately end-stage disease. An increasing complement of non-canonical elements function as co-factors in TGF-β1 signaling. p53 is a particularly prominent transcriptional co-regulator of several TGF-β1 fibrotic-response genes by complexing with TGF-β1 receptor-activated SMADs. This cooperative p53/TGF-β1 genomic cluster includes genes involved in cellular proliferative control, survival, apoptosis, senescence, and ECM remodeling. While the molecular basis for this co-dependency remains to be determined, a subset of TGF-β1-regulated genes possess both p53- and SMAD-binding motifs. Increases in p53 expression and phosphorylation, moreover, are evident in various forms of renal injury as well as kidney allograft rejection. Targeted reduction of p53 levels by pharmacologic and genetic approaches attenuates expression of the involved genes and mitigates the fibrotic response confirming a key role for p53 in renal disorders. This review focuses on mechanisms underlying TGF-β1-induced renal fibrosis largely in the context of ureteral obstruction, which mimics the pathophysiology of pediatric unilateral ureteropelvic junction obstruction, and the role of p53 as a transcriptional regulator within the TGF-β1 repertoire of fibrosis-promoting genes.

MUC16 Is Overexpressed in Idiopathic Pulmonary Fibrosis and Induces Fibrotic Responses Mediated by Transforming Growth Factor-β1 Canonical Pathway

Several transmembrane mucins have demonstrated that they contribute intracellularly to induce fibrotic processes. The extracellular domain of MUC16 is considered as a biomarker for disease progression and death in IPF patients. However, there is no evidence regarding the signalling capabilities of MUC16 that contribute to IPF development. Here, we demonstrate that MUC16 was overexpressed in the lung tissue of IPF patients (n = 20) compared with healthy subjects (n = 17) and localised in fibroblasts and hyperplastic alveolar type II cells. Repression of MUC16 expression by siRNA-MUC16 transfection inhibited the TGF-β1-induced fibrotic processes such as mesenchymal/ myofibroblast transformations of alveolar type II A549 cells and lung fibroblasts, as well as fibroblast proliferation. SiRNA-MUC16 transfection also decreased the TGF-β1-induced SMAD3 phosphorylation, thus inhibiting the Smad Binding Element activation. Immunoprecipitation assays and confocal immunofluorescence showed the formation of a protein complex between MUC16/p-SMAD3 in the cell membrane after TGF-β1 stimulation. This study shows that MUC16 is overexpressed in IPF and collaborates with the TGF-β1 canonical pathway to induce fibrotic processes. Therefore, direct or indirect targeting of MUC16 could be a potential drug target for human IPF.

Tbx18-positive cells-derived myofibroblasts contribute to renal interstitial fibrosis via transforming growth factor-β signaling

It has been demonstrated that the T-box family transcription factor 18 (Tbx18) -positive cells give rise to renal mesenchymal cells and contribute to the development of the urinary system. However, it is unclear whether Tbx18-positive cells are the origin of the myofibroblasts during renal fibrosis. The present study aimed to determine the contribution of Tbx18-positive cells in kidney fibrosis and their underlying mechanism. We show that Tbx18-positive cells contribute to the development of the urinary system, especially renal fibroblasts. Following unilateral ureteral obstruction (UUO), genetic fate tracing results demonstrated that Tbx18-positive cells not only proliferate but also expand and differentiate into fibroblasts and myofibroblasts, indicating that they may act as profibrotic progenitors. Cell culture results suggest that transforming growth factor (TGF)-β promotes Tbx18-positive cells differentiation into myofibroblasts and assist their contribution to kidney fibrosis. Overall, the present study demonstrated that Tbx18-positive cells may act as profibrotic progenitor cells in a pathological condition of UUO-induced injury. Moreover, TGF-β may play a role in differentiation of Tbx18-positive cells into myofibroblasts in kidney fibrosis. These findings may provide a potential target on Tbx18-positive myofibroblast progenitors in the treatment of renal fibrosis.

Myofibroblast progeny in wound biology and wound healing studies

Fibroblasts and myofibroblasts play a myriad of important roles in human tissue function, especially in wound repair and healing. Among all cells, fibroblasts are group of cells that decide the status of wound as they maintain tissue homeostasis. Currently, the increase in the deleterious effects of chronic wound and their morbidity rate has necessitated the need to understand the influence of fibroblasts and myofibroblasts, which chiefly originate locally from tissue-resident fibroblasts to address the same. Wound pathophysiology is complex, herein, we have discussed fibroblast and myofibroblast heterogeneity in skin and different organs by understanding the phenotypical and functional properties of each of its sub-populations in the process of wound healing. Recent advancements in fibroblast activation, differentiation to myofibroblasts, proliferation and migration are discussed in detail. Fibroblasts and myofibroblasts are key players in wound healing and wound remodelling, respectively, and their significance in wound repair is discussed. An increased understanding of their biology during wound healing also gives an opportunity to explore more of fibroblast and myofibroblast focused therapies to treat chronic wounds which are clinical challenges. In this regard, in the current review, we have described the different methods for isolation of primary fibroblasts and myofibroblasts from both animal models and humans, and their characterization. Additionally, we have also provided details on possible molecular targets for better understanding of prognosis, diagnosis and treatment of chronic wounds. Information will help both researchers and clinicians in providing molecular insight that enable them for effective chronic wound management. The knowledge of intimate dialogue between the fibroblast, sub-populations like, myofibroblast and their microenvironment, will serve useful in determining novel, efficient and specific therapeutic targets to treat pathological wound conditions.

Lessons from mouse models of MPN

Over the past decades, a variety of MPN mouse models have been developed to express in HSC the main mutations identified in patients: JAK2^V617F, CALRdel52 or ins5 and MPL^W515L. These models mimic quite faithfully human PV or ET with their natural evolutions into MF and their hemostasis complications, demonstrating the driver function of these mutations in MPN. Here, we review these models and show how they have improved our general understanding of MPN regarding (1) the mechanisms of fibrosis, thrombosis/hemorrhages and disease initiation, (2) the roles of additional mutations and signaling pathways in disease progression and (3) the preclinical development of novel therapies. We also address controversial results between these models and remind how these models may differ from human MPN onset and also how basically mice are not humans, encouraging caution when one draw lessons from mice to humans. Furthermore, the contribution of germline genetic predisposition, HSC and niche aging, metabolic, oxidative, replicative or genotoxic stress, inflammation, immune escape and additional mutations need to be considered in further investigations to encompass the full complexity of human MPN in mice.

T helper 17 cells in the pathophysiology of acute and chronic kidney disease

Both acute and chronic kidney disease have a strong underlying inflammatory component. This review focuses primarily on T helper 17 (Th17) cells as mediators of inflammation and their potential to modulate acute and chronic kidney disease. We provide updated information on factors and signaling pathways that promote Th17 cell differentiation with specific reference to kidney disease. We highlight numerous clinical studies that have investigated Th17 cells in the setting of human kidney disease and provide updated summaries from various experimental animal models of kidney disease indicating an important role for Th17 cells in renal fibrosis and hypertension. We focus on the pleiotropic effects of Th17 cells in different renal cell types as potentially relevant to the pathogenesis of kidney disease. Finally, we highlight studies that present contrasting roles for Th17 cells in kidney disease progression.

MUC4 is overexpressed in idiopathic pulmonary fibrosis and collaborates with transforming growth factor β inducing fibrotic responses

Several mucins are implicated in idiopathic pulmonary fibrosis (IPF); however, there is no evidence regarding the role of MUC4 in the development of IPF. Here we demonstrated that MUC4 was overexpressed in IPF patients (n = 22) compared with healthy subjects (n = 21) and located in pulmonary arteries, bronchial epithelial cells, fibroblasts, and hyperplastic alveolar type II cells. Decreased expression of MUC4 using siRNA-MUC4 inhibited the mesenchymal/myofibroblast transformations of alveolar type II A549 cells and lung fibroblasts, as well as cell senescence and fibroblast proliferation induced by TGF-β1. The induction of the overexpression of MUC4 increased the effects of TGF-β1 on mesenchymal/myofibroblast transformations and cell senescence. MUC4 overexpression and siRNA-MUC4 gene silencing increased or decreased, respectively, the phosphorylation of TGFβRI and SMAD3, contributing to smad-binding element activation. Immunoprecipitation analysis and confocal immunofluorescence showed the formation of a protein complex between MUC4β/p-TGFβRI and p-SMAD3 in the cell membrane after TGF-β1 stimulation and in lung tissue from IPF patients. Bleomycin-induced lung fibrosis was reduced in mice transiently transfected with siRNA-MUC4. This study shows that MUC4 expression is enhanced in IPF and promotes fibrotic processes in collaboration with TGF-β1 canonical pathway that could be an attractive druggable target for human IPF.

Proximal tubule LPA1 and LPA2 receptors use divergent signaling pathways to additively increase profibrotic cytokine secretion

Lysophosphatidic acid (LPA) increases platelet-derived growth factor-B (PDGFB) and connective tissue growth factor (CTGF) production and secretion by proximal tubule (PT) cells through LPA2 receptor-Gqα-αvβ6-integrin-mediated activation of transforming growth factor-β1 (TGFB1). LPA2, β6-integrin, PDGFB, and CTGF increase in kidneys after ischemia-reperfusion injury (IRI), coinciding with fibrosis. The TGFB1 receptor antagonist SD-208 prevents increases of β6-integrin, TGFB1-SMAD signaling, and PDGFB/CTGF expression after IRI and ameliorates fibrosis (Geng H, Lan R, Singha PK, Gilchrist A, Weinreb PH, Violette SM, Weinberg JM, Saikumar P, Venkatachalam MA. Am J Pathol 181: 1236-1249, 2012; Geng H, Lan R, Wang G, Siddiqi AR, Naski MC, Brooks AI, Barnes JL, Saikumar P, Weinberg JM, Venkatachalam MA. Am J Pathol 174: 1291-1308, 2009). We report now that LPA1 receptor signaling through epidermal growth factor receptor (EGFR)-ERK1/2-activator protein-1 cooperates with LPA2-dependent TGFB1 signaling to additively increase PDGFB/CTGF production and secretion by PT cells. Conversely, inhibition of both pathways results in greater suppression of PDGFB/CTGF production and secretion and promotes greater PT cellular differentiation than inhibiting one pathway alone. Antagonism of the LPA-generating enzyme autotaxin suppressed signaling through both pathways. After IRI, kidneys showed not only more LPA2, nuclear SMAD2/3, and PDGFB/CTGF but also increased LPA1 and autotaxin proteins, together with enhanced EGFR/ERK1/2 activation. Remarkably, the TGFB1 receptor antagonist SD-208 prevented all of these abnormalities excepting increased LPA2. SD-208 inhibits only one arm of LPA signaling: LPA2-Gqα-αvβ6-integrin-dependent production of active TGFB1 and its receptor-bound downstream effects. Consequently, far-reaching protection by SD-208 against IRI-induced signaling alterations and tubule-interstitial pathology is not fully explained by our data. TGFB1-dependent feedforward modulation of LPA1 signaling is one possibility. SD-208 effects may also involve mitigation of injury caused by IRI-induced TGFB1 signaling in endothelial cells and monocytes. Our results have translational implications for using TGFB1 receptor antagonists, LPA1 and LPA2 inhibitors concurrently, and autotaxin inhibitors in acute kidney injury to prevent the development of chronic kidney disease.

[Fibrosis-driving cells in patients with primary myelofibrosis and myelodysplastic syndromes with myelofibrosis]

Objective: To compare fibrosis-driving cells in patients with primary myelofibrosis (PMF) and patients with myelodysplastic syndromes (MDS) with myelofibrosis (MF) (MDS-MF) . Methods: Bone marrow biopsy sections of patients with newly diagnosed PMF and MDS (10 each randomly selected for MF-0/1, MF-2, and MF-3) were stained with specific immunofluorescence antibodies to label Gli1, LeptinR, alpha smooth muscle actin (α-SMA) , CD45, and ProcollagenⅠ. Images captured by confocal microscopy were analyzed by Fiji-ImageJ to calculate the cell counts of Gli1(+), LeptinR(+) cells, and fibrosis-driving cells including α-SMA(+), α-SMA(+)/Gli1(+), α-SMA(+)/LeptinR(+), and ProcollagenⅠ(+)/CD45(+) cells. Results: Patients with PMF and MDS with MF-2/3 had higher LeptinR(+), α-SMA(+), α-SMA(+)/Gli1(+), and Procollagen Ⅰ(+)/CD45(+) cell counts compared with those with MF-0/1 (all P values<0.05) . However, patients with PMF with MF-2/3 presented with higher Gli1(+) and α-SMA(+)/LeptinR(+) cell counts than those with MF-0/1 (P=0.001 and 0.006) , whereas these cells were similar between patients with MDS with MF-0/1 and MF-2/3 (P=0.169 and 0.067) . In patients with MF-0/1, all fibrosis-driving cells did not differ between PMF and MDS (all P>0.05) . However, in patients with MF-2/3, Procollagen Ⅰ(+)/CD45(+) cell counts were higher in patients with PMF compared with those with MDS (P=0.007) , while other fibrosis-driving cell counts were similar between these two groups (all P>0.05) . MF grade and fibrosis-driving cell counts were not correlated with overall survival in patients with either PMF or MDS. Conclusion: α-SMA(+) cells in patients with PMF originated from both Gli1(+) and LeptinR(+) cells, whereas α-SMA(+) cells in patients with MDS-MF only originated from Gli1(+) cells; patients with PMF had higher ProcollagenⅠ(+)/CD45(+) cell counts than those with MDS-MF.

Therapeutic Effect of Human Amniotic Epithelial Cells in Rat Models of Intrauterine Adhesions

As a refractory fibrosis disease, intrauterine adhesions (IUAs) is defined as fibrosis of the physiological endometrium. Although hysteroscopic adhesiolysis is widely recommended as an effective treatment, prognosis and recurrence remain poor in severe cases. Recently, stem cell therapy has been promoted as a promising treatment for IUAs. The ability of human amniotic epithelial cells (hAECs), emerging as a new candidate for stem cell therapy, to treat IUAs has not been demonstrated. To study the potential effects of hAECs on IUAs, we created an IUA rat model using mechanical injury and injected cultured primary hAECs into the rats’ uteri. Next, we observed the morphological structure of endometrial thickness and glands using hematoxylin and eosin staining, and we detected extracellular-matrix collagen deposition using Masson staining. In addition, we performed immunohistochemical staining and reverse-transcription polymerase chain reaction (RT-PCR) to investigate potential fibrosis molecules and angiogenesis factors 7 d after hAECs transplantation. Finally, we detected estrogen receptor (ER) and growth factors via RT-PCR to verify the molecular mechanism underlying cell therapy. In the IUA rat models, endometrial thickness and endometrial glands proliferated and collagen deposition decreased significantly after hAEC transplantation. We found that during the recovery of injured endometrium, the crucial fibrosis marker transforming growth factor-β (TGF-β) was regulated and angiogenesis occurred in the endometrial tissue with the up-regulation of vascular endothelial growth factor. Furthermore, hAECs were shown to promote ER expression in the endometrium and regulate the inflammatory reaction in the uterine microenvironment. In conclusion, these results demonstrated that hAEC transplantation could inhibit the progression of fibrosis and promote proliferation and angiogenesis in IUA rat models. The current study suggests hAECs as a novel stem cell candidate in the treatment of severe IUA.

In vivo silencing of amphiregulin by a novel effective Self-Assembled-Micelle inhibitory RNA ameliorates renal fibrosis via inhibition of EGFR signals

Amphiregulin (AREG) is a transmembrane glycoprotein recently implicated in kidney fibrosis. Previously, we reported that the AREG-targeting Self-Assembled-Micelle inhibitory RNA (SAMiRNA-AREG) alleviated fibrosis by stably silencing the AREG gene, and reduced the side effects of conventional siRNA treatment of pulmonary fibrosis. However, the therapeutic effect of SAMiRNA-AREG in renal fibrosis has not been studied until now. We used two animal models of renal fibrosis generated by a unilateral ureteral obstruction (UUO) and an adenine diet (AD) to investigate whether SAMiRNA-AREG inhibited renal fibrosis. To investigate the delivery of SAMiRNA-AREG to the kidney, Cy5-labeled SAMiRNA-AREG was injected into UUO- and AD-induced renal fibrosis models. In both kidney disease models, SAMiRNA-AREG was delivered primarily to the damaged kidney. We also confirmed the protective effect of SAMiRNA-AREG in renal fibrosis models. SAMiRNA-AREG markedly decreased the UUO- and AD-induced AREG mRNA expression. Furthermore, the mRNA expression of fibrosis markers, including α-smooth muscle actin, fibronectin, α1(I) collagen, and α1(III) collagen in the UUO and AD-induced kidneys, was diminished in the SAMiRNA-AREG-treated mice. The transcription of inflammatory markers (tumor necrosis factor-α and monocyte chemoattractant protein-1) and adhesion markers (vascular cell adhesion molecule 1 and intercellular adhesion molecule 1) was attenuated. The hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining results showed that SAMiRNA-AREG decreased renal fibrosis, AREG expression, and epidermal growth factor receptor (EGFR) phosphorylation in the UUO- and AD-induced models. Moreover, we studied the effects of SAMiRNA-AREG in response to TGF-β1 in mouse and human proximal tubule cells, and mouse fibroblasts. TGF-β1-induced extracellular matrix production and myofibroblast differentiation were attenuated by SAMiRNA-AREG. Finally, we confirmed that upregulated AREG in the UUO or AD models was mainly localized in the distal tubules. In conclusion, SAMiRNA-AREG represents a novel siRNA therapeutic for renal fibrosis by suppressing EGFR signals.