Thrombospondin-1 short hairpin RNA suppresses tubulointerstitial fibrosis in the kidney of ureteral obstruction by ameliorating peritubular capillary injury

Relationship between circulating thrombospondin-1 messenger ribonucleic acid and microribonucleic acid-194 levels in Chinese patients with type 2 diabetic kidney disease: The outcomes of a case-control study

AIMS/INTRODUCTION

We investigated the relationship of circulating TSP-1 mRNA and miR-194 with diabetic kidney disease's degree.

MATERIALS AND METHODS

We enrolled 167 hospitalized type 2 diabetes patients in the endocrinology department. Patients were split into three groups according to urinary microalbumin: A, B and C. The control group comprised healthy outpatients (n = 163). The quantities of microribonucleic acid (miR)-194 and thrombospondin-1 (TSP-1) messenger ribonucleic acid (mRNA) in the participants' circulation were measured using a quantitative real-time polymerase chain reaction.

RESULTS

Circulating TSP-1 mRNA (P = 0.024) and miR-194 (P = 0.029) expressions significantly increased in type 2 diabetes patients. Circulating TSP-1 mRNA (P = 0.040) and miR-194 (P = 0.007) expression levels differed significantly among the three groups; circulating TSP-1 mRNA expression increased with urinary microalbumin. However, miR-194 declined in group B and increased in group C. Circulating TSP-1 mRNA was positively correlated with cystatin-c (r = 0.281; P = 0.021) and microalbumin/creatinine ratio (UmALB/Cr; r = 0.317; P = 0.009); miR-194 was positively correlated with UmALB/Cr (r = 0.405; P = 0.003). Stepwise multivariate linear regression analysis showed cystatin-c (β = 0.578; P = 0.021) and UmALB/Cr (β = 0.001; P = 0.009) as independent factors for TSP-1 mRNA; UmALB/Cr (β = 0.005; P = 0.028) as an independent factor for miR194. Areas under the curve for circulating TSP-1 mRNA and miR194 were 0.756 (95% confidence interval 0.620-0.893; sensitivity 0.69 and specificity 0.71, P < 0.01) and 0.584 (95% confidence interval 0.421-0.748; sensitivity 0.54 and specificity 0.52, P < 0.01), respectively.

CONCLUSIONS

Circulating TSP-1 mRNA and miR-194 expressions significantly increased in type 2 diabetes patients. The microalbumin group had lower levels of miR-194 (a risk factor that is valuable for type 2 diabetes kidney disease evaluation).

Let‑7f‑5p Regulated by Hsa_circ_0000437 Ameliorates Bleomycin-Induced Skin Fibrosis

The current treatment of skin fibrosis is limited in its effectiveness due to a lack of understanding of the underlying mechanisms. Previous research has shown a connection between microRNAs (miRNAs) and the development of skin fibrosis. Therefore, investigating miRNA for the treatment of skin fibrotic diseases is highly important and merits further exploration. In this study, we have discovered that let-7f-5p could suppress the proliferation, migration, and expression of collagen type I alpha 1 (COL1A1) in human dermal fibroblasts (HDFs). It was further determined that let-7f-5p could target thrombospondin-1 (THBS1), thereby inhibiting the TGF-β2/Smad3 signaling pathway and exerting its biological effects. Additionally, let-7f-5p is regulated by Hsa_circ_0000437, which acts as a sponge molecule for let-7f-5p and consequently regulates the biological function of HDFs. Furthermore, our findings indicate that in vivo overexpression of let-7f-5p leads to a reduction in dermal thickness and COL1A1 expression, effectively inhibiting the progression of bleomycin (BLM)-induced skin fibrosis in mice. Hence, our research enhances the comprehension of the Hsa_circ_0000437/let-7f-5p/THBS1/TGF-β2/Smad3 regulatory network, highlighting the potential of let-7f-5p as a therapeutic approach for the treatment of skin fibrosis.

Circ_0047339 promotes the activation of fibroblasts and affects the development of urethral stricture by targeting the miR-4691-5p/TSP-1 axis

Urethral stricture is related to scar tissue fibrosis, but its pathogenesis is still unclear. This study aims to explore the regulatory mechanism of circular RNA (circRNA) in the occurrence and development of urethral stricture. CircRNA microarray was employed to analyze circRNA expression profiles between human urethral scar tissue and normal urethral tissue. The results of circRNA microarray showed that there were 296 differentially expressed genes between urethral scar tissue and normal urethral tissue. The enrichment analysis of Kyoto encyclopedia of genes and genomes showed that these circRNAs were significantly correlated with ECM–receptor interaction. The first nine differentially expressed circRNA were selected to predict the circRNA–miRNA network. RT-qPCR results showed that circ_0047339 was upregulated considerably in urethral scar tissue. Urethral scar fibroblasts were isolated from human urethral scar tissue and cultured in vitro. After silencing circ_0047339, the proliferation of urethral scar cells decreased significantly, and the expressions of Collagen I (COL-1) and α-smooth muscle actin (α-SMA) also reduced. As a competing endogenous RNA, circ_0047339 could increase the expression of TSP-1 by competitively binding miR-4691-5p. In addition, miR-4691-5p mimic transfection could inhibit the proliferation of urethral scar fibroblasts and the presentation of thrombospondin-1 (TSP-1), α-SMA and COL-1, while circ_0047339 overexpression eliminated this inhibition. Our results showed that circ_0047339 might promote the growth and fibrosis of urethral scar fibroblasts through miR-4691-5p/TSP-1 axis, thus promoting the development of urethral stricture.

The fibrogenic niche in kidney fibrosis: components and mechanisms

Kidney fibrosis, characterized by excessive deposition of extracellular matrix (ECM) that leads to tissue scarring, is the final common outcome of a wide variety of chronic kidney diseases. Rather than being distributed uniformly across the kidney parenchyma, renal fibrotic lesions initiate at certain focal sites in which the fibrogenic niche is formed in a spatially confined fashion. This niche provides a unique tissue microenvironment that is orchestrated by a specialized ECM network consisting of de novo-induced matricellular proteins. Other structural elements of the fibrogenic niche include kidney resident and infiltrated inflammatory cells, extracellular vesicles, soluble factors and metabolites. ECM proteins in the fibrogenic niche recruit soluble factors including WNTs and transforming growth factor-β from the extracellular milieu, creating a distinctive profibrotic microenvironment. Studies using decellularized ECM scaffolds from fibrotic kidneys show that the fibrogenic niche autonomously promotes fibroblast proliferation, tubular injury, macrophage activation and endothelial cell depletion, pathological features that recapitulate key events in the pathogenesis of chronic kidney disease. The concept of the fibrogenic niche represents a paradigm shift in understanding of the mechanism of kidney fibrosis that could lead to the development of non-invasive biomarkers and novel therapies not only for chronic kidney disease, but also for fibrotic diseases of other organs.

Network Pharmacology and In Vivo Analysis of Dahuang-Huangqi Decoction Effectiveness in Alleviating Renal Interstitial Fibrosis

Dahuang and Huangqi are the most frequently prescribed treatment methods for chronic kidney disease in China. Our study aimed to clarify the pharmacological mechanism of action of Dahuang-Huangqi decoction (DHHQD) in renal interstitial fibrosis (RIF). The intersection of genes targeted by DHHQD active ingredients and RIF target genes was searched using network pharmacology to build a chemical ingredient and disease target network. For in vivo analysis, Sprague–Dawley rats with unilateral urethral obstruction (UUO) were administered DHHQD, and their kidney function-related indicators and pathological indices were determined. The expression of core targets was quantified using real-time polymerase chain reaction and western blotting. A total of 139 common targets for DHHQD and RIF in chronic kidney disease were detected. Compared with the untreated UUO rats, the DHHQD-treated rats showed reductions in the following: blood urea nitrogen and serum creatinine levels, kidney tubular atrophy and necrosis, interstitial fibrosis, hyperplasia and abnormal deposition of extracellular matrix, and microstructural changes in the mesangial matrix and glomerular basement membrane. DHHQD treatment significantly regulated the levels of renal core proteins, such as eNOS, IL-6, EGFR, and VEGF and reduced the mRNA and protein expression of the core targets involved in inflammation pathways, such as PI3K/AKT and TLR4/NF-κB. DHHQD treatment ameliorated the severity of RIF by potentially regulating the AKT/PI3K and TLR4/NF-κB signaling pathways. Our study findings provide insights into the mechanisms associated with DHHQD action and essential data for future research.

The renal microcirculation in chronic kidney disease: novel diagnostic methods and therapeutic perspectives

Chronic kidney disease (CKD) affects 8–16% of the population worldwide and is characterized by fibrotic processes. Understanding the cellular and molecular mechanisms underpinning renal fibrosis is critical to the development of new therapeutics. Microvascular injury is considered an important contributor to renal progressive diseases. Vascular endothelium plays a significant role in responding to physical and chemical signals by generating factors that help maintain normal vascular tone, inhibit leukocyte adhesion and platelet aggregation, and suppress smooth muscle cell proliferation. Loss of the rich capillary network results in endothelial dysfunction, hypoxia, and inflammatory and oxidative effects and further leads to the imbalance of pro- and antiangiogenic factors, endothelial cell apoptosis and endothelial-mesenchymal transition. New techniques, including both invasive and noninvasive techniques, offer multiple methods to observe and monitor renal microcirculation and guide targeted therapeutic strategies. A better understanding of the role of endothelium in CKD will help in the development of effective interventions for renal microcirculation improvement. This review focuses on the role of microvascular injury in CKD, the methods to detect microvessels and the novel treatments to ameliorate renal fibrosis.

Thrombospondin-1 CD47 Signalling: From Mechanisms to Medicine

Recent advances provide evidence that the cellular signalling pathway comprising the ligand-receptor duo of thrombospondin-1 (TSP1) and CD47 is involved in mediating a range of diseases affecting renal, vascular, and metabolic function, as well as cancer. In several instances, research has barely progressed past pre-clinical animal models of disease and early phase 1 clinical trials, while for cancers, anti-CD47 therapy has emerged from phase 2 clinical trials in humans as a crucial adjuvant therapeutic agent. This has important implications for interventions that seek to capitalize on targeting this pathway in diseases where TSP1 and/or CD47 play a role. Despite substantial progress made in our understanding of this pathway in malignant and cardiovascular disease, knowledge and translational gaps remain regarding the role of this pathway in kidney and metabolic diseases, limiting identification of putative drug targets and development of effective treatments. This review considers recent advances reported in the field of TSP1-CD47 signalling, focusing on several aspects including enzymatic production, receptor function, interacting partners, localization of signalling, matrix-cellular and cell-to-cell cross talk. The potential impact that these newly described mechanisms have on health, with a particular focus on renal and metabolic disease, is also discussed.

Kidney Allograft Fibrosis: Diagnostic and Therapeutic Strategies

Interstitial fibrosis with tubule atrophy (IF/TA) is the response to virtually any sustained kidney injury and correlates inversely with kidney function and allograft survival. IF/TA is driven by various pathways that include hypoxia, renin-angiotensin-aldosterone system, transforming growth factor (TGF)-β signaling, cellular rejection, inflammation and others. In this review we will focus on key pathways in the progress of renal fibrosis, diagnosis and therapy of allograft fibrosis. This review discusses the role and origin of myofibroblasts as matrix producing cells and therapeutic targets in renal fibrosis with a particular focus on renal allografts. We summarize current trends to use multi-omic approaches to identify new biomarkers for IF/TA detection and to predict allograft survival. Furthermore, we review current imaging strategies that might help to identify and follow-up IF/TA complementary or as alternative to invasive biopsies. We further discuss current clinical trials and therapeutic strategies to treat kidney fibrosis.Supplemental Visual Abstract; http://links.lww.com/TP/C141.

The role of CD47 in pathogenesis and treatment of renal ischemia reperfusion injury

Ischemia reperfusion (IR) injury is a process defined by the temporary loss of blood flow and tissue perfusion followed later by restoration of the same. Brief periods of IR can be tolerated with little permanent deficit, but sensitivity varies for different target cells and tissues. Ischemia reperfusion injuries have multiple causes including peripheral vascular disease and surgical interventions that disrupt soft tissue and organ perfusion as occurs in general and reconstructive surgery. Ischemia reperfusion injury is especially prominent in organ transplantation where substantial effort has been focused on protecting the transplanted organ from the consequences of IR. A number of factors mediate IR injury including the production of reactive oxygen species and inflammatory cell infiltration and activation. In the kidney, IR injury is a major cause of acute injury and secondary loss of renal function. Transplant-initiated renal IR is also a stimulus for innate and adaptive immune-mediated transplant dysfunction. The cell surface molecule CD47 negatively modulates cell and tissue responses to stress through limitation of specific homeostatic pathways and initiation of cell death pathways. Herein, a summary of the maladaptive activities of renal CD47 will be considered as well as the possible therapeutic benefit of interfering with CD47 to limit renal IR.

Thrombospondin 1 and Its Diverse Roles as a Regulator of Extracellular Matrix in Fibrotic Disease

Thrombospondin 1 (TSP1) is a matricellular extracellular matrix protein that has diverse roles in regulating cellular processes important for the pathogenesis of fibrotic diseases. We will present evidence for the importance of TSP1 control of latent transforming growth factor beta activation in renal fibrosis with an emphasis on diabetic nephropathy. Other functions of TSP1 that affect renal fibrosis, including regulation of inflammation and capillary density, will be addressed. Emerging roles for TSP1 N-terminal domain regulation of collagen matrix assembly, direct effects of TSP1-collagen binding, and intracellular functions of TSP1 in mediating endoplasmic reticulum stress responses in extracellular matrix remodeling and fibrosis, which could potentially affect renal fibrogenesis, will also be discussed. Finally, we will address possible strategies for targeting TSP1 functions to treat fibrotic renal disease.

Astaxanthin ameliorates renal interstitial fibrosis and peritubular capillary rarefaction in unilateral ureteral obstruction

Loss of peritubular capillaries is a notable feature of progressive renal interstitial fibrosis. Astaxanthin (ASX) is a natural carotenoid with various biological activities. The present study aimed to evaluate the effect of ASX on unilateral ureteral obstruction (UUO)‑induced renal fibrosis in mice. For that purpose, mice were randomly divided into five treatment groups: Sham, ASX 100 mg/kg, UUO, UUO + ASX 50 mg/kg and UUO + ASX 100 mg/kg. ASX was administered to the mice for 7 or 14 days following UUO. The results demonstrated that UUO‑induced histopathological changes in the kidney tissue were prevented by ASX. Renal function was improved by ASX treatment, as evidenced by decreased blood urea nitrogen and serum creatinine levels. Furthermore, the extent of renal fibrosis and collagen deposition induced by UUO was suppressed by ASX. The levels of collagen I, fibronectin and α‑smooth muscle actin were increased by UUO in mice or by transforming growth factor (TGF)‑β1 treatment in NRK‑52E cells, and were reduced by ASX administration. In addition, ASX inhibited the UUO‑induced decrease in peritubular capillary density by upregulating vascular endothelial growth factor and downregulating thrombospondin 1 levels. Inactivation of the TGF‑β1/Smad signaling pathway was involved in the anti‑fibrotic mechanism of ASX in UUO mice and TGF‑β1‑treated NRK‑52E cells. In conclusion, ASX attenuated renal interstitial fibrosis and peritubular capillary rarefaction via inactivation of the TGF‑β1/Smad signaling pathway.

Calcium Dobesilate and Micro-vascular diseases

Micro-vascular diseases and its associated complications continue to be a significant health problem worldwide. Vascular lesions from microvascular involvement lead to impaired blood flow and contribute to damage and dysfunction of one or more target organs, that is, the heart, kidneys, eyes, and nervous system. Calcium Dobesilate Drug (CAD) is an established vasoactive and angioprotective drug that has shown a unique, multitarget mode of action in several experimental studies and in different animal models of diabetic microvascular complications. CAD has been widely used as an antioxidant and a vascular protective agent. At present, the application of Calcium Dobesilate is mainly related to Micro-vascular damage-related diseases, such as diabetic retinopathy (DR) and diabetic nephropathy (DN), and it is found to significantly improve the related symptoms. Its beneficial effects make it an attractive therapeutic compound especially in the early stages of these diseases. Scholars at home and abroad have studied the effectiveness, safety, and mechanisms of the related diseases, furthermore, the subjects involved patients and animal models, they have found some new clinical effects of this medicine. This paper makes a brief summary of a research progress of clinical application about Vascular injury related diseases and other aspects.

MicroRNA let-7d targets thrombospondin-1 and inhibits the activation of human pancreatic stellate cells

OBJECTIVES

The microRNA (miRNA) let-7d is linked to the formation of pancreatic cancer-related fibrosis. In this study, the mechanism by which let-7d regulates the activation of the human pancreatic stellate cell (hPSC) was evaluated.

METHODS

The transient transfection of a let-7d mimic in the hPSCs was performed, and the altered thrombospondin 1 (THBS1) expression was confirmed by western blotting and real-time qPCR. Targeting of the 3'-untranslated region (UTR) of THBS1 by let-7d was investigated by the luciferase assays. After hPSC transfection using THBS1 siRNA, the fibrosis markers (α-SMA and collagen 1A1) were evaluated by western blotting and real-time qPCR. The correlation between tumor fibrosis and let-7d or THBS1 was estimated using the data from The Cancer Genome Atlas project. Finally, the effects of genistein on the hPSCs were evaluated.

RESULTS

We found that a let-7d mimic inhibits THBS1 expression by targeting its 3'-UTR. THBS1 inhibition by siRNA inhibited hPSC activation. An in silico analysis revealed that let-7d and THBS1 expression are negatively correlated. Additionally, let-7d was negatively correlated with the stromal score, while THBS1 was positively correlated with this score. Genistein substantially induced let-7d and decreased the expression of fibrosis marker along with the inhibition of THBS1.

CONCLUSIONS

Let-7d inhibited hPSC activation by targeting THBS1. Genistein induced the expression of let-7d and might modulate pancreatic fibrosis.

Cellular and molecular mechanisms of kidney fibrosis

Renal fibrosis is the final pathological process common to any ongoing, chronic kidney injury or maladaptive repair. It is considered as the underlying pathological process of chronic kidney disease (CKD), which affects more than 10% of world population and for which treatment options are limited. Renal fibrosis is defined by excessive deposition of extracellular matrix, which disrupts and replaces the functional parenchyma that leads to organ failure. Kidney's histological structure can be divided into three main compartments, all of which can be affected by fibrosis, specifically termed glomerulosclerosis in glomeruli, interstitial fibrosis in tubulointerstitium and arteriosclerosis and perivascular fibrosis in vasculature. In this review, we summarized the different appearance, cellular origin and major emerging processes and mediators of fibrosis in each compartment. We also depicted and discussed the challenges in translation of anti-fibrotic treatment to clinical practice and discuss possible solutions and future directions.

Thrombospondin immune regulation and the kidney

Most therapeutic attempts to prevent the progression of kidney diseases have been based on interventions to inhibit the production of transforming growth factor-β (TGF-β). Thrombospondins (TSPs) play an important role in activating TGF-β. In the healthy kidney, two TSPs are expressed, TSP1 and TSP2, which exert contrasting effects. While TSP1 is a major activator of TGF-β in renal cells and exerts pro-inflammatory effects both in vitro and in vivo, TSP2 lacks the ability for TGF-β activation but regulates matrix remodeling and inflammation in experimental kidney disease. The effects of TSPs in the kidney have been mostly investigated by using the murine model of unilateral ureteral obstruction. In this model, TSP1 expression is increased along with the development of interstitial fibrosis and TGF-β. Relief of the obstruction gradually improves renal function and decreases the expression in TSP1 and TGF-β1. Several inhibitors of TSP1 prevented progressive interstitial fibrosis in murine models of ureteral obstruction, suggesting that control of latent TGF-β activation by inhibiting TSP1 might represent a novel potential target for preventing renal interstitial fibrosis. However, further studies are needed to assess whether TSP1-mediated TGF-β activation can be safely used in humans. In fact, TSPs normally act to suppress tumors in vivo. Moreover, TGF-β can exert a pivotal function in the immune system, as it may induce the production of regulatory T cells and suppress B cell responses. Knowledge of the molecular mechanisms involved in TGF-β regulation may help in finding effective treatments of tissue fibrosis, cancer and autoimmune disease.

Fibrosis-related miRNAs as serum biomarkers for pancreatic ductal adenocarcinoma

We investigated whether serum microRNAs (miRNAs) could be diagnostic or prognostic markers in pancreatic ductal adenocarcinoma (PDAC). We first identified miRNAs showing altered expression in human pancreatic stellate cells (hPSCs) co-cultured with PDAC cells (Panc-1 and BxPC-3) as compared to hPSCs cultured alone. Among the miRNAs with altered expression, let-7d exhibited reduced expression in an in silico analysis of The Cancer Genome Atlas data. Inhibition of let-7d resulted in enhanced expression of fibrosis-related genes. We extracted serum miRNA from 45 PDAC patients and 42 healthy controls and quantified expression let-7d using digital PCR. Based on the level of let-7d expression, we were able to distinguish between PDAC patients and controls. Additionally, reduced let-7d expression correlated with poor overall survival. Thus, fibrosis-related miRNAs may be serum biomarkers for PDAC.

Capillary rarefaction from the kidney point of view

Capillary rarefaction is broadly defined as a reduction in vascular density. Capillary rarefaction in the kidneys is thought to promote hypoxia, impair hemodynamic responses and predispose to chronic kidney disease (CKD) progression and hypertension development. Various mechanisms have been suggested to play a role in the development of capillary rarefaction, including inflammation, an altered endothelial-tubular epithelial cell crosstalk, a relative deficiency in angiogenic growth factors, loss of pericytes, increased activity of Transforming growth factor -β1 and thrombospondin-1, vitamin D deficiency, a link to lymphatic neoangiogenesis and INK4a/ARF (Cylin-dependent kinase inhibitor 2a; CDKN2A). In this review, we summarize the tools available to monitor capillary rarefaction noninvasively in the clinic, the contribution of capillary rarefaction to CKD and hypertension, the known mechanisms of capillary rarefaction, and potential future strategies to attenuate capillary rarefaction and reduce its negative impact. Therapeutic strategies to be explored in more detail include optimization of antihypertensive therapy, vitamin D receptor activators, sirtuin 1 activators, Hypoxia inducible factor prolyl hydroxylase inhibitors and stem cell therapy.

Progression of chronic kidney disease: too much cellular talk causes damage

Tubulointerstitial fibrosis, tubular atrophy, and peritubular capillary rarefaction are major hallmarks of chronic kidney disease. The tubulointerstitium consists of multiple cell components including tubular epithelial, mesenchymal (fibroblasts and pericytes), endothelial, and inflammatory cells. Crosstalk among these cell components is a key component in the pathogenesis of this complex disease. After severe or recurrent injury, the renal tubular epithelial cells undergo changes in structure and cell cycle that are accompanied by altered expression and production of cytokines. These cytokines contribute to the initiation of the fibrotic response by favoring activation of fibroblasts, recruitment of inflammatory cells, and loss of endothelial cells. This review focuses on how augmented growth factor and cytokine production induces epithelial crosstalk with cells in the interstitium to promote progressive tubulointerstitial fibrosis after renal injury.

Inhibition of p38 mitogen-activated protein kinases attenuates renal interstitial fibrosis in a murine unilateral ureteral occlusion model

AIMS

Cellular hypoxia has been proposed as a major factor contributing to the pathogenesis of chronic renal injury. Much of our understanding of how mitogen-activated protein kinases (MAPK) signaling promotes renal fibrosis has been based on cell culture studies. Therefore, we used the unilateral ureteral occlusion (UUO) model to further elucidate the role of the p38 MAPK pathway in renal interstitial fibrosis induced by hypoxia.

MATERIALS AND METHODS

In the present study, 24 male mice were randomized into the following three groups (n=8 each): Sham group (DMSO solution), UUO group (UUO+DMSO solution) and UP group (UUO+p38 inhibitor). The model of UUO was conducted using an established procedure described previously. Histological changes in renal tubular interstitium were observed with hematoxylin-eosin (HE) and Masson's trichrome. The protein levels of hypoxia inducible factor-1α (HIF-1α)、transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF) and collagen type I were analyzed by western blotting and immunohistochemistry at 2weeks.

KEY FINDINGS

Increased expression of hypoxia inducible factor-1α (HIF-1α) in UUO mice confirmed the existence of hypoxia in renal interstitial. Hypoxia result in tubulointerstitial fibrosis via the molecular activation of connective tissue growth factor (CTGF). p38 inhibitor administration markedly downregulates the protein of connective tissue growth factor (CTGF) and collagen type I expression induced by hypoxia.

SIGNIFICANCE

An increase in p38 MAPK activation is induced by hypoxia. The hypoxia up-regulates the protein connective tissue growth factor (CTGF) and collagen I expression in a p38-dependent manner.

Early infiltration of p40IL12(+)CCR7(+)CD11b(+) cells is critical for fibrosis development

INTRODUCTION

Macrophages are heterogeneous and thus can be correlated with distinct tissue outcomes after injury. Conflicting data have indicated that the M2-related phenotype directly triggers fibrosis. Conversely, we hypothesize here that the inflammatory milieu provided by early infiltration of pro-inflammatory macrophages dictates tissue scarring after injury.

METHODS AND RESULTS

We first determined that tissue-localized macrophages exhibit a pro-inflammatory phenotype (p40IL12(+)CCR7(+)CD11b(+)) during the early phase of a chronic injury model, in contrast to a pro-resolving phenotype (Arg1(+)IL10(+)CD206(+)CD11b(+)) at a later stage. Then, we evaluated the effects of injecting macrophages differentiated in vitro in the presence of IFNγ + LPS or IL4 + IL13 or non-differentiated macrophages (hereafter, M0) on promoting inflammation and progression of chronic injury in macrophage-depleted mice. In addition to enhancing the expression of pro-inflammatory cytokines, the injection of M (IFNγ + LPS), but not M (IL4 + IL13) or M0, accentuated fibrosis while augmenting levels of anti-inflammatory molecules, increasing collagen deposition and impairing organ function. We observed a similar profile after injection of sorted CCR7(+)CD11b(+) cells and a more pronounced effect of M (IFNγ + LPS) cells originated from Stat6(-/-) mice. The injection of M (IFNγ + LPS) cells was associated with the up-regulation of inflammation- and fibrosis-related proteins (Thbs1, Mmp7, Mmp8, and Mmp13).

CONCLUSIONS

Our results suggest that pro-inflammatory macrophages promote microenvironmental changes that may lead to fibrogenesis by inducing an inflammatory milieu that alters a network of extracellular-related genes, culminating in tissue fibrosis.

Thrombospondin 1 Deficiency Ameliorates the Development of Adriamycin-Induced Proteinuric Kidney Disease

Accumulating evidence suggests that thrombospondin 1 (TSP1) is an important player in diabetic nephropathy. However, the role of TSP1 in podocyte injury and the development of non-diabetic proteinuric kidney disease is largely unknown. In the current study, by using a well-established podocyte injury model (adriamycin-induced nephropathy mouse model), we examined the contribution of TSP1 to the development of proteinuric kidney disease. We found that TSP1 was up-regulated in the glomeruli, notably in podocytes, in adriamycin injected mice before the onset of proteinuria. ADR treatment also stimulated TSP1 expression in cultured human podocytes in vitro. Moreover, increased TSP1 mediated ADR-induced podocyte apoptosis and actin cytoskeleton disorganization. This TSP1's effect was through a CD36-dependent mechanism and involved in the stimulation of p38MAPK pathway. Importantly, in vivo data demonstrated that TSP1 deficiency protected mice from ADR induced podocyte loss and foot process effacement. ADR induced proteinuria, glomerulosclerosis, renal macrophage infiltration and inflammation was also attenuated in TSP1 deficient mice. Taken together, these studies provide new evidence that TSP1 contributes to the development of non-diabetic proteinuric kidney disease by stimulating podocyte injury and the progression of renal inflammation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The serum levels of connective tissue growth factor in patients with systemic lupus erythematosus and lupus nephritis

OBJECTIVE

The expression of connective tissue growth factor mRNA in human kidneys may serve as an early marker for lupus nephritis progression. Therefore, we speculated that connective tissue growth factor may be involved in the pathogenesis of systemic lupus erythematosus and lupus nephritis. In this study, we set out to investigate the associations between serum connective tissue growth factor levels and clinicopathological features of patients with systemic lupus erythematosus and lupus nephritis.

METHODS

Serum samples from patients with non-renal systemic lupus erythematosus, renal biopsy-proven lupus nephritis and healthy control subjects were detected by enzyme-linked immunosorbent assay for serum connective tissue growth factor levels. The associations between connective tissue growth factor levels and clinicopathological features of the patients were further analysed.

RESULTS

The levels of serum connective tissue growth factor in patients with non-renal systemic lupus erythematosus and lupus nephritis were both significantly higher than those in the normal control group (34.14 ± 12.17 ng/ml vs. 22.8 ± 3.0 ng/ml, p<0.001; 44.1 ± 46.8 ng/ml vs. 22.8 ± 3.0 ng/ml, p = 0.035, respectively). There was no significant difference of the serum connective tissue growth factor levels between non-renal systemic lupus erythematosus and lupus nephritis group (34.14 ± 12.17 ng/ml vs. 44.1 ± 46.8 ng/ml, p = 0.183). Serum connective tissue growth factor levels were significantly higher in lupus nephritis patients with the following clinical manifestations, including anaemia (51.3 ± 51.4 ng/ml vs. 23.4 ± 9.7 ng/ml, p<0.001) and acute renal failure (85.5 ± 75.0 ng/ml vs. 31.2 ± 21.8 ng/ml, p = 0.002). Serum connective tissue growth factor levels in class IV were significantly higher than that in class II, III and V (57.6 ± 57.5 ng/ml vs. 18.7 ± 6.4 ng/ml, p = 0.019; 57.6 ± 57.5 ng/ml vs. 25.2 ± 14.9 ng/ml, p = 0.006; 57.6 ± 57.5 ng/ml vs. 30.5 ± 21.3 ng/ml, p = 0.017, respectively). Serum connective tissue growth factor levels were significantly higher in those with both active/chronic lesions than those in those with active lesions only in either class IV (84.9 ± 69.6 ng/ml vs. 40.0 ± 40.2 ng/ml, p = 0.001) or in combination of class III and IV lupus nephritis (63.3 ± 63.4 ng/ml vs. 38.3 ± 37.9 ng/ml, p = 0.035, respectively). Serum connective tissue growth factor levels were negatively associated with estimated glomerular filtration rate (r = -0.46, p<0.001) and positively associated with interstitial inflammation (r = 0.309, p = 0.002) and interstitial fibrosis (r = 0.287, p = 0.004). Serum connective tissue growth factor level was a risk factor for doubling of serum creatinine in lupus nephritis (p<0.001, hazard ratio = 1.015, 95% confidence intervals 1.008-1.022) in univariate analysis.

CONCLUSIONS

Serum connective tissue growth factor levels were significantly higher in lupus and correlated with chronic renal interstitial injury and doubling of serum creatinine in patients with lupus nephritis.

The physical basis of renal fibrosis: effects of altered hydrodynamic forces on kidney homeostasis

Healthy kidneys are continuously exposed to an array of physical forces as they filter the blood: shear stress along the inner lumen of the tubules, distension of the tubular walls in response to changing fluid pressures, and bending moments along both the cilia and microvilli of individual epithelial cells that comprise the tubules. Dysregulation of kidney homeostasis via underlying medical conditions such as hypertension, diabetes, or glomerulonephritis fundamentally elevates the magnitudes of each principle force in the kidney and leads to fibrotic scarring and eventual loss of organ function. The purpose of this review is to summarize the progress made characterizing the response of kidney cells to pathological levels of mechanical stimuli. In particular, we examine important, mechanically responsive signaling cascades and explore fundamental changes in renal cell homeostasis after cyclic strain or fluid shear stress exposure. Elucidating the effects of these disease-related mechanical imbalances on endogenous signaling events in kidney cells presents a unique opportunity to better understand the fibrotic process.

Allogeneic mesenchymal stem cell infusion for the stabilization of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is the most frequent acquired renal condition resulting in end stage kidney disease in children. We describe a cell therapy treatment with human allogeneic bone marrow mesenchymal stem cells (MSC) in a 13-year-old patient developing recurrent FSGS after renal transplantation, which was not responding to conventional therapy. This treatment relied on the following measurements:clinical and laboratory evaluation of renal function, proteome array, biopsy, short tandem repeat assay. Before MSC treatment, the patient needed weekly plasmapheresis to achieve proteinuria-to-creatininuria ratio below 5. After three MSC infusions without adverse events, the patient has a stable renal function and the proteinuria target was reached without plasmapheresis. In addition, some circulating inflammatory factors decreased and their levels were still low after one year. This is the first report of an MSC treatment in an FSGS patient. Even though different factors may have contributed to the clinical results, after MSC infusion a stable reduction in the serum level of several inflammatory factors has been registered and the patient does not need anymore plasmapheresis to keep proteinuria under control. In addition, this encouraging single case let us identify some putative efficacy biomarkers that could be of clinical interest in chronic kidney diseases.