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Background: Diabetic cardiomyopathy (DCM) is a common diabetic complication characterized by diastolic relaxation abnormalities, myocardial fibrosis, and chronic heart failure. Although TGF-b/Smad3 signaling has been shown to play a critical role in chronic heart disease, the role and mechanisms of Smad3 in DCM remain unclear. Methods: We generated Smad3 knockout (KO)-db/db, Smad3 wild-type (WT)-db/db, Smad3+/- db/db, and their littermate Smad3 KO/WT-db/m mice. The role of Smad3 in DCM including the left ventricular (LV) ejection fraction (EF), LV fractional shortening (FS), and LV Mass were determined and mechanisms of Smad3 in cardiac inflammation and fibrosis including Smad3-dependent microRNAs were investigated. Results: At the age of 32 weeks, Smad3WT-db/db mice developed moderate to severe DCM as demonstrated by a significant fall in LVEF, LVFS, and a marked increase in LV mass with progressive myocardial fibrosis and inflammation. In contrast, db/db mice lacking Smad3 (Smad3KO-db/db) were protected against the development of DCM with normal cardiac function without myocardial inflammation and fibrosis. Interestingly, db/db mice with deleting one copy of Smad3 (Smad3+/-db/db) did not show any cardioprotective effect. Mechanistically, we found that deletion of Smad3 from db/db mice largely protected cardiac Smad7 from Smurf2-mediated ubiquitin proteasome degradation, thereby inducing IkBa to suppress NF-kB-driven cardiac inflammation. In addition, deletion of Smad3 also altered Smad3-dependent miRNAs by upregulating cardiac miR-29b while suppressing miR-21 to exhibit the cardioprotective effect on Smad3KO-db/db mice. Conclusions: Smad3 is a key mediator in the pathogenesis of DCM. Results from this study imply that targeting Smad3 may be a novel therapy for DCM.

Macroautophagy/autophagy dysregulation has been noted in diabetic nephropathy; however, the regulatory mechanisms controlling this process remain unclear. In this study, we showed that SMAD3 (SMAD family member 3), the key effector of TGFB (transforming growth factor beta)-SMAD signaling, induces lysosome depletion via the inhibition of TFEB-dependent lysosome biogenesis. The pharmacological inhibition or genetic deletion of SMAD3 restored lysosome biogenesis activity by alleviating the suppression of TFEB, thereby protecting lysosomes from depletion and improving autophagic flux in renal tubular epithelial cells in diabetic nephropathy. Mechanistically, we found that SMAD3 directly binds to the 3ʹ-UTR of TFEB and inhibits its transcription. Silencing TFEB suppressed lysosome biogenesis and resulted in a loss of the protective effects of SMAD3 inactivation on lysosome depletion under diabetic conditions. In conclusion, SMAD3 promotes lysosome depletion via the inhibition of TFEB-dependent lysosome biogenesis; this may be an important mechanism underlying autophagy dysregulation in the progression of diabetic nephropathy. Abbreviations: AGEs: advanced glycation end products; ATP6V1H: ATPase H+ transporting V1 subunit H; CTSB: cathepsin B; ChIP: chromatin immunoprecipitation; Co-BSA: control bovine serum albumin; DN: diabetic nephropathy; ELISA: enzyme-linked immunosorbent assay; FN1: fibronectin 1; HAVCR1/TIM1/KIM-1: hepatitis A virus cellular receptor 1; LAMP1: lysosomal associated membrane protein 1; LMP: lysosome membrane permeabilization; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; NC: negative control; SIS3: specific inhibitor of SMAD3; SMAD3: SMAD family member 3; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TECs: tubular epithelial cells; TFEB: transcription factor EB; TGFB1: transforming growth factor beta 1; TGFBR1: transforming growth factor beta receptor 1; UTR: untranslated region; VPS11: VPS11 core subunit of CORVET and HOPS complexes.

Acute kidney injury (AKI) is one of the most common complications affecting hospitalized patients associated with an extremely high mortality rate. However, the underlying pathogenesis of AKI remains unclear that largely limits its effective management in clinic. Increasing evidence demonstrated the importance of long non-coding RNAs (lncRNAs) in the pathogenesis of AKI, because of their regulatory roles in transcription, translation, chromatin modification, and cellular organization. Here, we reported a new role of LRNA9884 in AKI. Using experimental cisplatin-induced AKI model, we found that LRNA9884 was markedly up-regulated in the nucleus of renal tubular epithelium in mice with AKI. We found that silencing of LRNA9884 effectively inhibited the production of inflammatory cytokines MCP-1, IL-6, and TNF-α in the mouse renal tubular epithelial cells (mTECs) under IL-1β stimulation in vitro. Mechanistically, LRNA9884 was involved into NF-κB-mediated inflammatory cytokines production especially on macrophage migration inhibitory factor (MIF). Collectedly, our study suggested LRNA9884 promoted MIF-triggered the production of inflammatory cytokines via NF-κB pathway after AKI injury. This study uncovered LRNA9884 has an adverse impact in AKI, and targeting LRNA9884 might represent a potential therapeutic target for AKI.

Unresolved inflammation can lead to tissue fibrosis and impaired organ function. Macrophage–myofibroblast transition (MMT) is one newly identified mechanism by which ongoing chronic inflammation causes progressive fibrosis in different forms of kidney disease. However, the mechanisms underlying MMT are still largely unknown. Here, we discovered a brain-specific homeobox/POU domain protein Pou4f1 (Brn3a) as a specific regulator of MMT. Interestingly, we found that Pou4f1 is highly expressed by macrophages undergoing MMT in sites of fibrosis in human and experimental kidney disease, identified by coexpression of the myofibroblast marker, α-SMA. Unexpectedly, Pou4f1 expression peaked in the early stage in renal fibrogenesis in vivo and during MMT of bone marrow-derived macrophages (BMDMs) in vitro. Mechanistically, chromatin immunoprecipitation (ChIP) assay identified that Pou4f1 is a Smad3 target and the key downstream regulator of MMT, while microarray analysis defined a Pou4f1-dependent fibrogenic gene network for promoting TGF-β1/Smad3-driven MMT in BMDMs at the transcriptional level. More importantly, using two mouse models of progressive renal interstitial fibrosis featuring the MMT process, we demonstrated that adoptive transfer of TGF-β1-stimulated BMDMs restored both MMT and renal fibrosis in macrophage-depleted mice, which was prevented by silencing Pou4f1 in transferred BMDMs. These findings establish a role for Pou4f1 in MMT and renal fibrosis and suggest that Pou4f1 may be a therapeutic target for chronic kidney disease with progressive renal fibrosis.

Rationale: Transforming Growth Factor-beta (TGF-β) /Smad3 signaling has been shown to play important roles in fibrotic and inflammatory diseases, but its role in beta cell function and type 2 diabetes is unknown. Methods: The role of Smad3 in beta cell function under type 2 diabetes condition was investigated by genetically deleting Smad3 from db/db mice. Phenotypic changes of pancreatic islets and beta cell function were compared between Smad3 knockout db/db (Smad3KO-db/db) mice and Smad3 wild-type db/db (Smad3WT-db/db) mice, and other littermate controls. Islet-specific RNA-sequencing was performed to identify Smad3-dependent differentially expressed genes associated with type 2 diabetes. In vitro beta cell proliferation assay and insulin secretion assay were carried out to validate the mechanism by which Smad3 regulates beta cell proliferation and function. Results: The results showed that Smad3 deficiency completely protected against diabetes-associated beta cell loss and dysfunction in db/db mice. By islet-specific RNA-sequencing, we identified 8160 Smad3-dependent differentially expressed genes associated with type 2 diabetes, where Smad3 deficiency markedly prevented the down-regulation of those genes. Mechanistically, Smad3 deficiency preserved the expression of beta cell development mediator Pax6 in islet, thereby enhancing beta cell proliferation and function in db/db mice in vivo and in Min6 cells in vitro. Conclusions: Taken together, we discovered a pathogenic role of Smad3 in beta cell loss and dysfunction via targeting the protective Pax6. Thus, Smad3 may represent as a novel therapeutic target for type 2 diabetes prevention and treatment.

Renal fibrosis is a hallmark of chronic kidney disease. Although considerable achievements in the pathogenesis of renal fibrosis have been made, the underlying mechanisms of renal fibrosis remain largely to be explored. Now we have reached the consensus that TGF-β is a master regulator of renal fibrosis. Indeed, TGF-β regulates renal fibrosis via both canonical and noncanonical TGF-β signaling. Moreover, ongoing renal inflammation promotes fibrosis as inflammatory cells such as macrophages, conventional T cells and mucosal-associated invariant T cells may directly or indirectly contribute to renal fibrosis, which is also tightly regulated by TGF-β. However, anti-TGF-β treatment for renal fibrosis remains ineffective and nonspecific. Thus, research into mechanisms and treatment of renal fibrosis remains highly challenging.

Inflammation and fibrosis are two pathological features of chronic kidney disease (CKD). Transforming growth factor-β (TGF-β) has been long considered as a key mediator of renal fibrosis. In addition, TGF-β also acts as a potent anti-inflammatory cytokine that negatively regulates renal inflammation. Thus, blockade of TGF-β inhibits renal fibrosis while promoting inflammation, revealing a diverse role for TGF-β in CKD. It is now well documented that TGF-β1 activates its downstream signaling molecules such as Smad3 and Smad3-dependent non-coding RNAs to transcriptionally and differentially regulate renal inflammation and fibrosis, which is negatively regulated by Smad7. Therefore, treatments by rebalancing Smad3/Smad7 signaling or by specifically targeting Smad3-dependent non-coding RNAs that regulate renal fibrosis or inflammation could be a better therapeutic approach. In this review, the paradoxical functions and underlying mechanisms by which TGF-β1 regulates in renal inflammation and fibrosis are discussed and novel therapeutic strategies for kidney disease by targeting downstream TGF-β/Smad signaling and transcriptomes are highlighted.

AimsMyocardial dysfunction is an important cause of heart failure (HF). RNA polymerase II subunit 5 (RPB5)-mediating protein (RMP) is a transcriptional mediating protein which co-ordinates cellular processes including gene expression, metabolism, proliferation, and genome stability. However, its role in cardiac disease remains unknown. We aimed to determine the role and regulatory mechanisms of RMP in cardiomyocyte function and the development of HF.Methods and resultsMyocardial RMP expression was examined in human heart tissues from healthy controls and patients with advanced HF. Compared to normal cardiac tissues, RMP levels were significantly decreased in the myocardium of patients with advanced HF. To investigate the role of RMP in cardiac function, Cre-loxP recombinase technology was used to generate tamoxifen-inducible cardiomyocyte-specific Rmp knockout mice. Unexpectedly, cardiomyocyte-specific deletion of Rmp in mice resulted in contractile dysfunction, cardiac dilatation, and fibrosis. Furthermore, the lifespan of cardiac-specific Rmp-deficient mice was significantly shortened when compared with littermates. Mechanistically, we found that chronic HF in Rmp-deficient mice was associated with impaired mitochondrial structure and function, which may be mediated via a transforming growth factor-β/Smad3-proliferator-activated receptor coactivator1α (PGC1α)-dependent mechanism. PGC1α overexpression partially rescued chronic HF in cardiomyocyte-specific Rmp-deficient mice, and Smad3 blockade protected against the loss of PGC1α and adenosine triphosphate content that was induced by silencing RMP in vitro.ConclusionsRMP plays a protective role in chronic HF. RMP may protect cardiomyocytes from injury by maintaining PGC1α-dependent mitochondrial biogenesis and function. The results from this study suggest that RMP may be a potential therapeutic agent for treating HF.

Transforming growth factor β1 (TGF-β1) plays a promoting role in tumor growth via a mechanism associated with hyperactive Smad3 and suppressed Smad7 signaling in the tumor microenvironment. We report that retrieving the balance between Smad3 and Smad7 signaling with asiatic acid (AA, a Smad7 inducer) and naringenin (NG, a Smad3 inhibitor) effectively inhibited tumor progression in mouse models of invasive melanoma (B16F10) and lung carcinoma (LLC) by promoting natural killer (NK) cell development and cytotoxicity against cancer. Mechanistically, we found that Smad3 physically bound Id2 and IRF2 to suppress NK cell production and NK cell-mediated cytotoxicity against cancer. Treatment with AA and NG greatly inhibited Smad3 translation and phosphorylation while it restored Smad7 expression, and, therefore, it largely promoted NK cell differentiation, maturation, and cytotoxicity against cancer via Id2/IRF2-associated mechanisms. In contrast, silencing Id2 or IRF2 blunted the protective effects of AA and NG on NK cell-dependent anti-cancer activities. Thus, treatment with AA and NG produced an additive effect on inactivating TGF-β1/Smad3 signaling, and, therefore, it suppressed melanoma and lung carcinoma growth by promoting NK cell immunity against cancer via a mechanism associated with Id2 and IRF2.

Natural killer (NK) cells, early effectors in anticancer immunity, are paralyzed by TGFβ1, an immunosuppressive cytokine produced by cancer cells. Development and activity of NK cells are largely inhibited in the Smad3-dependent tumor microenvironment. Here, we used genetic engineering to generate a stable SMAD3-silencing human NK cell line, NK-92-S3KD, whose cancer-killing activity and cytokine production were significantly enhanced under TGFβ1-rich condition compared with the parental cell line. Interestingly, we identified that the IFNG gene is a direct E4BP4 target gene. Thus, silencing of SMAD3 allows upregulation of E4BP4 that subsequently promoting interferon-γ (IFNγ) production in the NK-92-S3KD cells. More importantly, NK-92-S3KD immunotherapy increases the production of not only IFNγ, but also granzyme B and perforin in tumors; therefore, inhibiting cancer progression in two xenograft mouse models with human hepatoma (HepG2) and melanoma (A375). Thus, the NK-92-S3KD cell line may be useful for the clinical immunotherapy of cancer. Cancer Immunol Res; 6(8); 965–77. ©2018 AACR.

Transforming growth factor-β (TGF-β) is the key player in tissue fibrosis. However, antifibrotic therapy targeting this multifunctional protein may interfere with other physiological processes to cause side effects. Thus, precise therapeutic targets need to be identified by further understanding the underlying mechanisms of TGF-β1 signalling during fibrogenesis. Equilibrium of Smad signalling is crucial for TGF-β-mediated renal fibrosis, where Smad3 is pathogenic but Smad2 and Smad7 are protective. The activation of TGF-β1/Smad signalling triggers extracellular matrix deposition, and local myofibroblast generation and activation. Mechanistic studies have shown that TGF-β/Smad3 transits the microRNA profile from antifibrotic to profibrotic and therefore promotes renal fibrosis via regulating non-coding RNAs at transcriptional levels. More importantly, disease-specific Smad3-dependent long non-coding RNAs have been recently uncovered from mouse kidney disease models and may represent novel precision therapeutic targets for chronic kidney disease. In this review, mechanisms of TGF-β-driven renal fibrosis via non-coding RNAs and their translational capacities will be discussed in detail.

AIM C-reactive protein (CRP) is a mediator of systemic inflammation. Peritoneal dialysis (PD) is known to cause peritoneal inflammation and fibrosis. We compare the degree of peritoneal inflammation and fibrosis in wild-type (WT) and CRP-transgenic (Tg) mice after PD treatment. METHODS WT (n = 7) and CRP-Tg (n = 10) C57BL/6 J mice (all male, 10-12 weeks old) were injected intra-peritoneally with 4.25% dextrose PD solution (3 mL/mouse) daily for 28 days, followed by a 2-h peritoneal equilibration test (PET). The mice were then killed. Parietal peritoneal and omental tissues were collected for the assessment of inflammation and fibrosis. RESULTS After 28 days of PD treatment, CRP-Tg mice had higher dialysate-to-plasma (D/P) creatinine ratio than that of WT mice. Parietal peritoneum of the CRP-Tg mice was more cellular and thicker than that of the WT mice. CRP-Tg mice also had higher connective tissue growth factor (CTGF), intercellular adhesion molecule 1 (ICAM1) and tumor necrosis factor α (TNFα) RNA expressions as well as immunohistochemical staining in the parietal peritoneum than that of the WT mice. CONCLUSIONS CRP-Tg mice have significantly more inflammation and fibrosis than WT mice after PD treatment. Our results suggest that CRP play a role in inflammation and fibrosis induced by PD. The implication of our results to human PD therapy needs further investigations.

Tumor-associated macrophages (TAM) have important roles in cancer progression, but the signaling behind the formation of protumoral TAM remains understudied. Here, by single-cell RNA sequencing, we revealed that the pattern recognition receptor Mincle was highly expressed in TAM and significantly associated with mortality in patients with non–small cell lung cancer. Cancer cells markedly induced Mincle expression in bone marrow–derived macrophages (BMDM), thus promoting cancer progression in invasive lung carcinoma LLC and melanoma B16F10 in vivo and in vitro. Mincle was predominately expressed in the M2-like TAM in non–small cell lung carcinoma and LLC tumors, and silencing of Mincle unexpectedly promoted M1-like phenotypes in vitro. Mechanistically, we discovered a novel Mincle/Syk/NF-κB signaling pathway in TAM needed for executing their TLR4-independent protumoral activities. Adoptive transfer of Mincle-silenced BMDM significantly suppressed TAM-driven cancer progression in the LLC-bearing NOD/SCID mice. By modifying our well-established ultrasound microbubble–mediated gene transfer protocol, we demonstrated that tumor-specific silencing of Mincle effectively blocked Mincle/Syk/NF-κB signaling, therefore inhibiting the TAM-driven cancer progression in the syngeneic mouse cancer models. Thus, our findings highlight the function of Mincle as a novel immunotherapeutic target for cancer via blocking the Mincle/Syk/NF-κB circuit in TAM.

Background Transforming growth factor (TGF)-β/Smad3 signaling is highly activated in kidneys of patients with type 2 diabetic nephropathy (T2DN), however, the precise role of Smad3 in the pathogenesis of diabetic nephropathy remains unclear. Methods Smad3 knockout (KO)-db/db mice were generated by intercrossing of male and female double-heterozygous Smad3+/− db/m mice. Renal functions including urinary albumin excretion and serum creatinine were determined. Renal histological injury including renal fibrosis and inflammation were examined by periodic acid Schiff (PAS), periodic acid-silver methenamine (PASM), and immunohistochemistry (IHC) staining. Results Smad3 knockout (KO)-db/db mice were protected from the development of diabetic kidney injury, characterized by the normal levels of urinary albumin excretion and serum creatinine without any evidence for renal fibrosis and inflammation. In contrast, Smad3 wild-type (WT) db/db and Smad3+/− db/db mice developed progressively decline in renal function over the 12 to 32-week time course, including increased microalbuminuria and elevated levels of serum creatinine. Pathologically, Smad3 WT db/db and Smad3+/− db/db mice exhibited a marked deposition of collagen-I (col I), collagen-IV(col-IV), and an increased infiltration of F4/80+ macrophages in kidney. Mechanistically, Smad3 deficiency decreased the lncRNA Erbb4-IR transcription, while increased miR-29b transcription and therefore protected the kidney from progressive renal injury in db/db mice. Conclusion Results from this study imply that Smad3 may represent as a novel and effective therapeutic target for T2DN.

Transforming growth factor-β/Smad3 signaling plays an important role in diabetic nephropathy, but its underlying working mechanism remains largely unexplored. The current study uncovered the pathogenic role and underlying mechanism of a novel Smad3-dependent long noncoding RNA (lncRNA) (LRNA9884) in type 2 diabetic nephropathy (T2DN). We found that LRNA9884 was significantly upregulated in the diabetic kidney of

Macrophage migration inhibitory factor (MIF) is elevated in patients with acute kidney injury (AKI) and is suggested as a potential predictor for renal replacement therapy in AKI. In this study, we found that MIF also plays a pathogenic role and is a therapeutic target for AKI. In a cisplatin-induced AKI mouse model, elevated plasma MIF correlated with increased serum creatinine and the severity of renal inflammation and tubular necrosis, whereas deletion of MIF protected the kidney from cisplatin-induced AKI by largely improving renal functional and histological injury, and suppressing renal inflammation including upregulation of cytokines such as interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α), IL-6, inducible nitric oxide synthase (iNOS), MCP-1, IL-8, and infiltration of macrophages, neutrophils, and T cells. We next developed a novel therapeutic strategy for AKI by blocking the endogenous MIF with an MIF inhibitor, ribosomal protein S19 (RPS19). Similar to the MIF-knockout mice, treatment with RPS19, but not the mutant RPS19, suppressed cisplatin-induced AKI. Mechanistically, we found that both genetic knockout and pharmacological inhibition of MIF protected against AKI by inactivating the CD74-nuclear factor κB (NF-κB) signaling. In conclusion, MIF is pathogenic in cisplatin-induced AKI. Targeting MIF with an MIF inhibitor RPS19 could be a promising therapeutic potential for AKI.

It is well established that Smad3 is a key downstream effector of transforming growth factor-β (TGF-β) signaling in tissue fibrogenesis. We reported here that targetting Smad3 specifically with a Smad3 inhibitor SIS3 is able to prevent or halt the progression of renal fibrosis in a mouse model of unilateral ureteral obstructive nephropathy (UUO). We found that preventive treatment with SIS3 at the time of disease induction largely suppressed progressive renal fibrosis by inhibiting α-smooth muscle actin (α-SMA) + myofibroblast accumulation and extracellular matrix (collagen I (Col.I) and fibronectin (FN)) production. Importantly, we also found that treatment with SIS3 on established mouse model of UUO from day 4 after UUO nephropathy halted the progression of renal fibrosis. Mechanistically, the preventive and therapeutic effects of SIS3 on renal fibrosis were associated with the inactivation of Smad3 signaling and inhibition of TGF-β1 expression in the UUO kidney. In conclusion, results from the present study suggest that targetting Smad3 may be a specific and effective therapy for renal fibrosis.

Tubular cell necrosis is a key histological feature of acute kidney injury (AKI). Necroptosis is a type of programed necrosis, which is executed by mixed lineage kinase domain-like protein (MLKL) upon its binding to the plasma membrane. Emerging evidence indicates that necroptosis plays a critical role in the development of AKI. However, it is unclear whether renal tubular cells undergo necroptosis in vivo and how the necroptotic pathway is regulated during AKI. Repulsive guidance molecule (RGM)-b is a member of the RGM family. Our previous study demonstrated that RGMb is highly expressed in kidney tubular epithelial cells, but its biological role in the kidney has not been well characterized. In the present study, we found that RGMb reduced membrane-associated MLKL levels and inhibited necroptosis in cultured cells. During ischemia/reperfusion injury (IRI) or oxalate nephropathy, MLKL was induced to express on the apical membrane of proximal tubular (PT) cells. Specific knockout of Rgmb in tubular cells (Rgmb cKO) increased MLKL expression at the apical membrane of PT cells and induced more tubular cell death and more severe renal dysfunction compared with wild-type mice. Treatment with the necroptosis inhibitor Necrostatin-1 or GSK'963 reduced MLKL expression on the apical membrane of PT cells and ameliorated renal function impairment after IRI in both wild-type and Rgmb cKO mice. Taken together, our results suggest that proximal tubular cell necroptosis plays an important role in AKI, and that RGMb protects against AKI by inhibiting MLKL membrane association and necroptosis in proximal tubular cells.

Natural killer (NK) cells belong to the innate immune system and are a first-line anti-cancer immune defense; however, they are suppressed in the tumor microenvironment and the underlying mechanism is still largely unknown. The lack of a consistent and reliable source of NK cells limits the research progress of NK cell immunity. Here, we report an in vitro system that can provide high quality and quantity of bone marrow-derived murine NK cells under a feeder-free condition. More importantly, we also demonstrate that siRNA-mediated gene silencing successfully inhibits the E4bp4-dependent NK cell maturation by using this system. Thus, this novel in vitro NK cell differentiating system is a biomaterial solution for immunity research.

We recently showed that imbalance of TGF-β/Smad signaling with over-activation of Smad3 but lower levels of Smad7 is a central mechanism of tissue fibrosis. In the present study, we report here that inhibition of Smad3 with naringenin (NG) and upregulation of Smad7 with asiatic acid (AA) produced an additive effect on inhibition of renal fibrosis in a mouse model of obstructive nephropathy. We found that AA, a triterpene from Centella Asiatica, functioned as a Smad7 agonist and suppressed TGF-β/Smad3-mediated renal fibrosis by inducing Smad7. Whereas, NG, a flavonoid from grapefruits and citrus fruits, was a Smad3 inhibitor that inhibited renal fibrosis by blocking Smad3 phosphorylation and transcription. The combination of AA and NG produced an additive effect on inhibition of renal fibrosis by blocking Smad3 while upregulating Smad7. Thus, rebalancing the disorder of TGF-β/Smad signaling by treatment with AA and NG may represent as a novel and effective therapy for chronic kidney disease associated with fibrosis.

T cells play a critical role in acute allograft rejection. TGF-β/Smad3 signaling is a key pathway in regulating T cell development. We report here that Smad3 is a key transcriptional factor of TGF-β signaling that differentially regulates T cell immune responses in a mouse model of cardiac allograft rejection in which donor hearts from BALB/c mice were transplanted into Smad3 knockout (KO) and wild type (WT) mice. Results showed that the cardiac allograft survival was prolonged in Smad3 KO recipients. This allograft protection was associated with a significant inhibition of proinflammatory cytokines (IL-1β, TNF-α, and MCP-1) and infiltration of neutrophils, CD3+ T cells, and F4/80+ macrophages. Importantly, deletion of Smad3 markedly suppressed T-bet and IFN-γ while enhancing GATA3 and IL-4 expression, resulting in a shift from the Th1 to Th2 immune responses. Furthermore, mice lacking Smad3 were also protected from the Th17-mediated cardiac injury, although the regulatory T cell (Treg) response was also suppressed. In conclusion, Smad3 is an immune regulator in T cell-mediated cardiac allograft rejection. Loss of Smad3 results in a shift from Th1 to Th2 but suppressing Th17 immune responses. Thus, modulation of TGF-β/Smad3 signaling may be a novel therapy for acute allograft rejection.

Inflammation, fibrosis, and lipid disorder are essential promoters in the pathogenesis of diabetic kidney injury in diabetes mellitus type 2. Berberine (BBR) has been reported to have beneficial effects on diabetic nephropathy, but its action mechanism is still unclear. The present study was designed to elucidate the therapeutic mechanism of BBR in a type 2 diabetic nephropathy rat model induced by a high-fat diet and low-dose streptozotocin injection. The diabetic rats were treated with or without BBR by gavage for 20 weeks and examined by serology, 24-h albuminuria, histology, immunohistochemistry, and molecular analyses. Results showed that treatment with BBR significantly reduced serum levels of blood glucose and lipids, inhibited urinary excretion of albumin, and attenuated renal histological injuries in diabetic rats. Berberine treatment also inhibited renal inflammation, which was associated with inactivation of nuclear factor kappa-light-chain-enhancer of activated B-cell signalling. As a result, the upregulation of pro-inflammatory cytokines (interleukin-1β, tumour necrosis factor-α) and chemokine (monocyte chemotactic protein-1) was blocked. In addition, BBR treatment also inactivated transforming growth factor-β/Smad3 signalling and suppressed renal fibrosis, including expression of fibronectin, collagen I, and collagen IV. The present study reveals that BBR is a therapeutic agent for attenuating type 2 diabetic nephropathy by inhibiting nuclear factor kappa-light-chain-enhancer of activated B cell-driven renal inflammation and transforming growth factor-β/Smad3 signalling pathway.

// Xiao-Yu Dai 1,2,* , Li Zhou 1,2,* , Xiao-Ru Huang 1 , Ping Fu 2 and Hui-Yao Lan 1 1 Department of Medicine and Therapeutics, and Li Ka Shing Institute of Health Sciences, and Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China 2 Division of Nephrology, West China Hospital of Sichuan University, Chengdu, China * These authors have contributed equally to this work Correspondence to: Hui Y. Lan, email: // Ping Fu, email: // Keywords : chronic aristolochic acid nephropathy, Smad7, renal fibrosis, renal inflammation Received : January 26, 2015 Accepted : March 05, 2015 Published : March 30, 2015 Abstract Chronic Aristolochic Acid Nephropathy (AAN) is a progressive chronic kidney disease related to herb medicine. However, treatment for chronic AAN remains ineffective. We report here that Smad7 is protective and has therapeutic potential for chronic AAN. In a mouse model of chronic AAN, progressive renal injury was associated with a loss of renal Smad7 and disruption of Smad7 largely aggravated the severity of chronic AAN as demonstrated by a significant increase in levels of 24-hour urinary protein excretion, serum creatinine, and progressive renal fibrosis and inflammation. In contrast, restored Smad7 locally in the kidneys of Smad7 knockout mice prevented the progression of chronic AAN. Further studies revealed that worsen chronic AAN in Smad7 knockout mice was associated with enhanced activation of TGF-β/Smad3 and NF-κB signaling pathways, which was reversed when renal Smad7 was restored. Importantly, we also found that overexpression of Smad7 locally in the kidneys with established chronic AAN was capable of attenuating progressive chronic AAN by inactivating TGF-β/Smad3-medated renal fibrosis and NF-κB-driven renal inflammation. In conclusion, Smad7 plays a protective role in the pathogenesis of chronic AAN and overexpression of Smad7 may represent a novel therapeutic potential for chronic AAN.

Transforming growth factor β (TGF-β)/Smad3 signaling plays a role in tissue fibrosis. We report here that Erbb4-IR is a novel long non-coding RNA (lncRNA) responsible for TGF-β/Smad3-mediated renal fibrosis and is a specific therapeutic target for chronic kidney disease. Erbb4-IR was induced by TGF-β1 via a Smad3-dependent mechanism and was highly upregulated in the fibrotic kidney of mouse unilateral ureteral obstructive nephropathy (UUO). Silencing Erbb4-IR blocked TGF-β1-induced collagen I and alpha-smooth muscle actin (α-SMA) expressions in vitro and effectively attenuated renal fibrosis in the UUO kidney by blocking TGF-β/Smad3 signaling. Mechanistic studies revealed that Smad7, a downstream negative regulator of TGF-β/Smad signaling, is a target gene of Erbb4-IR because a binding site of Erbb4-IR was found on the 3′ UTR of Smad7 gene. Mutation of this binding site prevented the suppressive effect of Erbb4-IR on the Smad7 reporter activity; in contrast, overexpression of Erbb4-IR largely inhibited Smad7 but increased collagen I and α-SMA transcriptions. Thus, kidney-specific silencing of Erbb4-IR upregulated renal Smad7 and thus blocked TGF-β/Smad3-mediated renal fibrosis in vivo and in vitro. In conclusion, the present study identified that Erbb4-IR is a novel lncRNA responsible for TGF-β/Smad3-mediated renal fibrosis by downregulating Smad7. Targeting Erbb4-IR may represent a precise therapeutic strategy for progressive renal fibrosis.

DNA damage contributes to renal tubular cell death during kidney injury, but how DNA damage in tubular cells is regulated is not fully understood. Lethal (3) malignant brain tumor-like 2 (L3MBTL2), a novel polycomb group protein, has been implicated in regulating chromatin architecture. However, the biological functions of L3MBTL2 are largely undefined. Here we found that L3MBTL2 was expressed in the nuclei of renal tubular epithelial cells in mice. Ablation of L3mbtl2 in renal tubular cells resulted in increases in nuclear DNA damage, p53 activation, apoptosis, tubular injury and kidney dysfunction after cisplatin treatment or unilateral ureteral obstruction. In vitro, inhibition of L3MBTL2 sequentially promoted histone γH2AX expression, p53 activation and apoptosis in cisplatin-treated mouse proximal tubular TKPTS cells. Inhibition of p53 activity attenuated the apoptosis induced by L3mbtl2 deficiency after cisplatin treatment both in vivo and in vitro. Intriguingly, unlike other polycomb proteins, L3MBTL2 was not recruited to DNA damage sites, but instead increased nuclear chromatin density and reduced initial DNA damage load. Thus, L3MBTL2 plays a protective role in kidney injury, in part by inhibiting the DNA damage-p53-apoptosis pathway.

Regulatory T cells (Tregs) have been shown to play a protective role in glomerulonephritis (GN) and Foxp3 is a master transcription factor in Treg development. In this study, we examined the functional role and mechanisms of Foxp3 in a mouse model of accelerated anti-glomerular basement membrane (anti-GBM) GN induced in antigen-primed Foxp3 transgenic (Tg) mice. Compared with littermate of wildtype (WT) mice in which induced severe crescentic GN developed with progressive renal dysfunction, Foxp3 Tg mice had reduced crescent formation, urinary protein excretion, plasma creatinine and decline in creatinine clearance. The protective role of Foxp3 in crescentic GN was associated with a markedly suppressed expression of proinflammatory interleukin-1 beta (IL-1β), tumour necrosis factor-alpha (TNF-α) and monocyte chemoattractant protein 1 (MCP-1), and diminished infiltration of the kidneys by CD3+ T cells and F4/80+ macrophages. Moreover, overexpression of Foxp3 resulted in a significant increase in CD4+ Foxp3+ Tregs systemically and in the diseased kidneys, thereby blunting Th1, Th2, and Th17 responses systemically and in the kidneys. In conclusion, Foxp3 protects against kidney injury in crescentic GN through enhancement of Treg numbers and function, and suppression of Th1, Th2 and Th17 immune responses at the systemic and local tissue levels.

Angiotensin-converting enzyme-2 (ACE2) is downregulated in hypertensive nephropathy. The present study investigated the mechanisms whereby loss of ACE2 promoted angiotensin II–induced hypertensive nephropathy in ACE2 gene knockout mice. We found that compared with wild-type animals, mice lacking ACE2 developed much more severe hypertensive nephropathy in response to chronic angiotensin II infusion, including higher levels of blood pressure, urinary protein excretion, serum creatinine, and progressive renal fibrosis and inflammation. Mechanistic studies revealed that worsening kidney injury in ACE2 knockout mice was associated with an increase in Smurf2 (Smad-specific E3 ubiquitin protein ligase 2), a decrease in renal Smad7, and marked activation of TGF-β (transforming growth factor β)/Smad3 and NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells) signaling, suggesting that Smurf2-dependent Smad7 ubiquitin degradation may be a key mechanism whereby loss of ACE2 promotes angiotensin II–induced TGF-β/Smad3 and NF-κB–mediated hypertensive nephropathy. This was validated by restoring Smad7 locally in the kidneys of ACE2 knockout mice to block angiotensin II–induced TGF-β/Smad3-mediated renal fibrosis and NF-κB–driven renal inflammation. Moreover, we found that angiotensin II could induce microRNA-21 in the mouse kidney and in cultured mesangial cells via a Smad3-dependent mechanism, which was enhanced by deleting ACE2 but inhibited by overexpressing renal Smad7. In conclusion, loss of ACE2 promotes angiotensin II–induced renal injury by targeting Smad7 for degradation via a Smurf2-dependent mechanism. Overexpression of renal Smad7 protects against hypertensive nephropathy by inactivating angiotensin II–induced TGF-β/Smad3 and NF-κB pathways and by targeting the Smad3-dependent microRNA-21 axis.

Src activation has been associated with fibrogenesis after kidney injury. Macrophage-myofibroblast transition is a newly identified process to generate collagen-producing myofibroblasts locally in the kidney undergoing fibrosis in a TGF-β/Smad3-dependent manner. The potential role of the macrophage-myofibroblast transition in Src-mediated renal fibrosis is unknown. In studying this by RNA sequencing at single-cell resolution, we uncovered a unique Src-centric regulatory gene network as a key underlying mechanism of macrophage-myofibroblast transition. A total of 501 differentially expressed genes associated with macrophage-myofibroblast transition were identified. However, Smad3-knockout largely reduced the transcriptome diversity. More importantly, inhibition of Src largely suppresses ureteral obstruction-induced macrophage-myofibroblast transition in the injured kidney in vivo along with transforming growth factor-β1-induced elongated fibroblast-like morphology, α-smooth muscle actin expression and collagen production in bone marrow derived macrophages in vitro . Unexpectedly, we further uncovered that Src serves as a direct Smad3 target gene and also specifically up-regulated in macrophages during macrophage-myofibroblast transition. Thus, macrophage-myofibroblast transition contributes to Src-mediated tissue fibrosis. Hence, targeting Src may represent as a precision therapeutic strategy for macrophage-myofibroblast transition-driven fibrotic diseases.

Transforming growth factor (TGF)-β1 signals through downstream Smad-dependent and -independent pathways to exert its biological actions. It has been reported that overexpression of TGF-β1 results in the development of psoriasis-like lesions in a mouse model of K5.TGF-β(WT) transgenic mice. However, the signalling mechanisms by which TGF-β1 mediates the development of psoriasis-like lesions remain unknown. The aim of the present study was to investigate the hypothesis that TGF-β1 mediates the development of psoriasis-like lesions via a Smad3-dependent mechanism. This was tested in a mouse model of K5.TGF-β(WT) transgenic mice by blocking TGF-β signalling with a specific Smad3 inhibitor. Topical treatment with a Smad3 inhibitor markedly blocked TGF-β/Smad3 signalling and progressive psoriasis-like lesions in K5.TGF-β(WT) transgenic mice, as evidenced by decreased skin severity scores, double skin fold thickness (DSFT) scores, infiltration of CD3(+) T cells and F4/80(+) macrophages and the degree of fibrosis in the dermis. This was associated with a marked reduction in TGF-β1, interleukin (IL)-6, IL-23 and IL-17A both locally in skin plaque lesions and systemically in the plasma, resulting in inhibition of both the T helper (Th) 17 cell transcription factor RORγt and accumulation of CD4(+) IL-17A(+) cells within the skin plaque lesions. In conclusion, TGF-β1 mediates the development of psoriasis-like lesions via a Smad3-dependent, Th17-mediated mechanism. Targeting TGF-β/Smad3 signalling with a Smad3 inhibitor may represent a novel and effective therapy for psoriasis.

Smad7 is well demonstrated as a negative regulator of TGF-β signaling. Its alteration in expression often results in diseases such as cancer and fibrosis. However, the exact role of Smad7 in regulating bone remodeling during mammalian development has not been properly delineated. In this study we performed experiments to clarify the involvement of Smad7 in regulating osteogenesis and osteoclastogenesis both invivo and invitro. Genetically engineered Smad7(ΔE1) (KO) mice were used, whereby partial functional of Smad7 is lost by deleting exon I of the Smad7 gene and the truncated proteins cause a hypomorphic allele. Analysis with μCT imagery and bone histomorphometry showed that the KO mice had lower TbN, TbTh, higher TbSp in the metaphysic region of the femurs at 6, 12, 24weeks from birth, as well as decreased MAR and increased osteoclast surface compared with the WT mice. In vitro BM-MSC multi-lineage differentiation evaluation showed that the KO group had reduced osteogenic potential, fewer mineralized nodules, lower ALP activity, and reduced gene expression of Col1A1, Runx2 and OCN. The adipogenic potential was elevated in the KO group with more formation of lipid droplets, and increased gene expression of Adipsin and C/EBPα. The osteoclastogenic potential of KO mice BMMs was elevate, with emergence of more osteoclasts, larger resorptive areas, and increased gene expression of TRAP and CTR. Our results indicate that partial loss of Smad7 function in mice leads to compromised bone formation and enhanced bone resorption. Thus, Smad7 is acknowledged as a novel key regulator between osteogenesis and osteoclastogenesis.

Peritoneal fibrosis is a major cause of ultrafiltration failure in patients receiving continuous ambulatory peritoneal dialysis. Transforming growth factor (TGF)-β1 is an important mediator in this process; however, its signaling mechanisms had not been explored. Thus, we examined TGF-β1/Smad signaling in human peritoneal biopsy specimens associated with continuous ambulatory peritoneal dialysis. We found that TGF-β/Smad2/3 signaling was highly activated in patients with increased collagen deposition and thickening of the peritoneal membrane who were receiving continuous ambulatory peritoneal dialysis. Long-term exposure of wild-type mice to 4.25% peritoneal dialysis solution for 30 days induced significant peritoneal fibrosis with impaired peritoneal equilibrium, which was prevented in Smad3 knockout mice. In contrast, conditional Smad2 gene deletion in the peritoneum exacerbated peritoneal fibrosis and dysfunction. The contrasting roles of Smad2 and Smad3 in peritoneal fibrosis were also examined in vitro . Cultured mesothelial cells from Smad3 knockout mice were resistant to TGF-β1–induced collagen I production and the transition toward a myofibroblast phenotype as seen in wild-type cells, whereas Smad2 deficiency in mesothelial cells failed to modulate the profibrotic response to TGF-β1. In conclusion, this study found activation of TGF-β/Smad signaling in peritoneal fibrosis in patients receiving continuous ambulatory peritoneal dialysis and identifies opposing roles for Smad2 and Smad3 in peritoneal dialysis–associated peritoneal fibrosis. These findings provide a mechanistic basis for future therapies targeting TGF-β/Smad signaling in peritoneal fibrosis.

Loss of miR-29 is associated with cardiac fibrosis. This study examined the role and therapeutic potential of miR-29 in mouse model of hypertension induced by angiotensin II (AngII). By using microRNA microarray, in situ hybridization, and real-time polymerase chain reaction, we found that AngII-induced cardiac fibrosis in the hypertensive heart and in cultured cardiac fibroblasts were associated with downregulation of miR-29a-c via a Smad3-dependent mechanism. In vitro knockdown of miR-29b enhanced but overexpression of miR-29b inhibited AngII-induced fibrosis, revealing a protective role of miR-29b in cardiac fibrosis in response to AngII. This was further demonstrated in vivo by the ability of overexpressing miR-29b in the mouse heart to prevent AngII-mediated cardiac fibrosis and cardiac dysfunction. Importantly, we also found that restored miR-29b in the established hypertensive heart was capable of blocking progressive cardiac fibrosis and improving cardiac dysfunction, demonstrating a therapeutic potential of miR-29b for chronic heart disease. Further studies revealed that targeting the transforming growth factor (TGF)-β1 coding sequence region, thereby inhibiting TGF-β/Smad3 signaling, could be a new mechanism by which miR-29b inhibited AngII-induced cardiac fibrosis. In conclusion, miR-29b plays a protective role in AngII-mediated cardiac remodeling and may be a therapeutic agent for cardiac fibrosis by targeting the TGF-β/Smad3 pathway.

Background: Cancer-associated fibroblasts (CAF) are highly heterogeneous and their origins are largely unknown. Recently, we revealed that bone marrow-derived macrophages (BMDM) can further differentiate into myofibroblasts locally at the inflammatory site in a Smad3-dependent manner, but its potential role in the tumor microenvironment (TME) is still unexplored. Thus, we hypothesize that tumor-associated macrophages (TAM) may be able to transit into CAF, termed TAM to CAF transition (TAM-CAF), in TME for cancer promotion. Here, we are the first study to discover TAM-CAF as a common phenomenon in cancer. Methods: The evidence of TAM-CAF was confirmed on tumor biopsies from several cancer types including non-small cell lung carcinoma (NSCLC) tissue microarray. The occurrence pattern of TAM-CAF was determined in LysM-Cre/Rosa26-tdTomato mice with syngeneic lung carcinoma LLC by the fate-mapping study. The pathogenic role of TAM-CAF was examined by adoptive transferring of TAM-CAF cells onto LLC-bearing NOD-SCID mice. The regulatory mechanism was further elucidated on Smad3-WT/KO mice in vivo and BMDM in vitro. Results: Interestingly, we observed myofibroblast marker expressing TAM (α-SMA+CD68+) in the tumor biopsies of liver, kidney and lung cancers, which contributed to ~40% of the total CAF and positively associated with the NSCLC mortality. Fate mapping study confirmed the existence of macrophage-derived CAF (α-SMA+ tdTomato+) in LLC-tumor, where the contribution of TAM-CAF on CAF production was progressively increased throughout the tumorigenesis. Furthermore, adoptive transferring of TAM-CAF cells largely promotes tumor progression in LLC-bearing NOD/SCID mice associated with a marked increase of angiogenesis in the TME. Mechanistically, we found that phosphorylation of Smad3 is significantly associated with CAF production in NSCLC-TME (n=120), supported by the dramatic reduction of TAM-CAF in LLC-tumor and BMDM after deletion of Smad3. More importantly, we identified a conserved Smad3 binding site on the 5’UTR of FAP gene by ECR browser and ChIP assay in vitro; revealing its direct regulation on FAP expression at transcriptional level during TAM-CAF. Conclusion: We are the first study to uncover TAM as a rich source of CAF, which is commonly occurred in TME for cancer promotion via a Smad3-dependent mechanism. Thus, TAM-CAF may represent a novel and precision therapeutic target for cancer. Acknowledgments: This study was supported by Lui Che Woo Institute of Innovative Medicine (CARE program), Research Grants Council of Hong Kong (GRF 14117815, 14121816, 14163317, C7018-16G, TRS T12-402/13N), Health and Medical Research Fund (03140486, 14152321), Innovation and Technology Fund of Hong Kong (ITS/068/18), Direct Grant for Research CUHK (2017.002). Citation Format: Philip Chiu-Tsun Tang, Patrick Ming-Kuen Tang, Jeff Yat-Fai Chung, Xiao-Ru Huang, Ka-Fai TO, Hui-Yao LAN. Macrophage is a novel and rich source of cancer-associated fibroblasts in the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1095.

Tumor microenvironment (TME) is a new therapeutic target for cancer, however it is highly heterogeneous and still largely unknown. Recently, we revealed that Smad3 is essential for TME-driven cancer progression, better understanding of the underlying mechanism may uncover novel therapeutic targets for cancer. Indeed, Smad3-dependent TME (Smad3-TME) is originated from bone marrow, where neutrophils are the most abundant leukocytes but their role in cancer is still controversial. Here, we are the first study to reveal the regulatory role of Smad3 in tumor-associated neutrophils (TAN). Interestingly, we observed that knockout of Smad3 (Smad3-KO) dramatically increased TAN population in mice bearing syngeneic melanoma B16F10 and lung carcinoma LLC, where the anticancer N1 phenotypes were significantly induced in the SMad3-KO TME-isolated TAN. Unexpectedly, adoptive transfer of Smad3-KO bone marrow-derived neutrophils markedly suppressed the progression of LLC-tumor on Smad3-WT mice in vivo, and their enhanced cancer-killing activity was confirmed by co-culture assay in vitro. Furthermore, microarray analysis identified a total of 4416 differentially expressed genes associated with Smad3-KO neutrophils under cancer condition in vitro, but the presence of Smad3 largely decreased the transcriptome diversity; especially on genes associated with virus defense response including an anticancer cytokine IL-28. Silencing of IL-28 significantly reduced the anticancer efficiency of Smad3-KO TAN on LLC-bearing mice in vivo. Mechanistically, we uncovered that IL-28A serves as a direct Smad3 target gene and specifically down-regulated in neutrophils under TGF-β1 or LLC-secretome stimulations; showing by ChIP and dual-luciferase reporter assays in vitro. Thus, targeting Smad3 precisely on TAN may represent as a novel and effective immunotherapy for cancer. Acknowledgments: This study was supported by Lui Che Woo Institute of Innovative Medicine (CARE program), Research Grants Council of Hong Kong (GRF 14117815, 14121816, 14163317, C7018-16G, TRS T12-402/13N), Health and Medical Research Fund (03140486, 14152321), Innovation and Technology Fund of Hong Kong (ITS/068/18), Direct Grant for Research CUHK (2017.002). Note: This abstract was not presented at the meeting. Citation Format: Patrick Ming-Kuen Tang, Philip Chiu-Tsun Tang, Jeff Yat-Fai Chung, Xiao-Ru Huang, Ka-Fai To, Hui-Yao Lan. Smad3 silences neutrophil anticancer activity in the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1081.

Aims Smad7 plays a negative regulatory role in many inflammatory diseases, but its effect on hypertensive disease remains unknown. The present study tested the hypothesis that overexpression of Smad7 may have therapeutic potential for angiotensin II (Ang II)-mediated hypertensive cardiac remodelling. Methods and results Hypertensive heart disease was induced in mice by subcutaneous infusion of Ang II for 28 days and treated with Smad7 by a non-invasive ultrasound-microbubble-mediated inducible Smad7 gene transfer. We found that cardiac Smad7 was largely reduced in the hypertensive heart and overexpression of cardiac Smad7 protected against the fall in the left ventricular (LV) ejection fraction (EF), an increase in LV mass, and cardiac inflammation and fibrosis such as up-regulation of pro-inflammatory cytokines (IL-1β, TNF-α) and fibrotic markers (collagen I, α-SMA), and infiltration of CD3+ T cells and F4/80+ macrophages. Further studies revealed that inactivation of the Sp1-TGF-β/Smad3-NF-κB (NF-κB, nuclear factor κB) pathways and prevention of cardiac miR-29 loss were mechanisms by which overexpression of Smad7 inhibited Ang II-mediated cardiac remodelling. Importantly, we also found that treatment with Smad7 when hypertensive cardiopathy established at day 14 halted the progression of cardiac injury by blunting the fall of EF and an increase in LV mass, and blocking TGF-β/Smad3-mediated cardiac fibrosis and NF-κB-driven inflammation. Conclusion Smad7 plays a protective role in Ang II-induced cardiac remodelling via mechanisms involving the Sp1-TGF-β/Smad-NF-κB-miR-29 regulatory network. Thus, Smad7 may be a novel therapeutic agent for hypertensive cardiovascular diseases.

Podocyte injury and the appearance of proteinuria are features of minimal-change disease (MCD). Cyclosporin A (CsA) and tacrolimus (FK506) has been reported to reduce proteinuria in patients with nephrotic syndrome, but mechanisms remain unknown. We, therefore, investigated the protective mechanisms of CsA and FK506 on proteinuria in a rat model of MCD induced by puromycin aminonucleoside (PAN) and in vitro cultured mouse podocytes. Our results showed that CsA and FK506 treatment decreased proteinuria via a mechanism associated to a reduction in the foot-process fusion and desmin, and a recovery of synaptopodin and podocin. In PAN-treated mouse podocytes, pre-incubation with CsA and FK506 restored the distribution of the actin cytoskeleton, increased the expression of synaptopodin and podocin, improved podocyte viability, and reduced the migrating activities of podocytes. Treatment with CsA and FK506 also inhibited PAN-induced podocytes apoptosis, which was associated with the induction of Bcl-xL and inhibition of Bax, cleaved caspase 3, and cleaved PARP expression. Further studies revealed that CsA and FK506 inhibited PAN-induced p38 and JNK signaling, thereby protecting podocytes from PAN-induced injury. In conclusion, CsA and FK506 inhibit proteinuria by protecting against PAN-induced podocyte injury, which may be associated with inhibition of the MAPK signaling pathway.

Mincle (macrophage-inducible C-type lectin, Clec4e) is a transmembrane pattern recognition receptor involving the innate immunity, but its role in kidney disease is still unexplored. In the obstructed kidney of the unilateral ureteral obstruction model of renal injury, Mincle was specifically detected in the infiltrating M1 macrophages (CD68 + iNOS + cells) on day one but was rapidly reduced following reduction of M1 macrophages during the progression of kidney injury. Interestingly, Mincle-expressing macrophages were progressively increased in the cisplatin-induced acute kidney injury model, where iNOS expression was detected in the CD68 + cells following Mincle induction. Adaptive transfer of Mincle + M1 macrophages largely promoted cisplatin-induced renal inflammation, which was prevented by the knockdown of Mincle in the transferred cells. Mincle was tightly regulated by TLR4/NF-κB signaling as evidenced by the binding of NF-κB/p65 to the promoter region of Mincle in LPS-primed macrophages. Blocking TLR4 or NF-κB suppressed LPS-induced Mincle expression on macrophages. Importantly, Mincle was found to be essential for maintaining the inflammatory phenotypes of M1 macrophages through the Syk signaling pathway since knockdown of Mincle or inhibition of Syk suppressed LPS-induced IL-1β, MCP-1, and iNOS expression. Thus, Mincle is induced specifically on M1 macrophages, where Mincle-Syk signaling promotes and maintains inflammatory phenotypes of M1 macrophages in acute renal inflammation. Hence, targeting Mincle may be a novel therapy for acute kidney injury associated with M1 macrophages.

This study aimed to evaluate the validation of the leptin receptor-deficient mice model for secondary osteoporosis associated with type 2 diabetes mellitus (T2DM) at bone micro-architectural level. Thirty three 36-week old male mice were divided into four groups: normal control (db/m) (n = 7), leptin receptor-deficient T2DM (db/db) (n = 8), human C-reactive protein (CRP) transgenic normal control (crp/db/m) (n = 7) and human CRP transgenic T2DM (crp/db/db) (n = 11). Lumber vertebrae (L5) and bilateral lower limbs were scanned by micro-CT to analyze trabecular and cortical bone quality. Right femora were used for three-point bending to analyze the mechanical properties. Trabecular bone quality at L5 was better in db/db or crp/db/db group in terms of bone mineral density (BMD), bone volume fraction, connectivity density, trabecular number and separation (all p crp/db/db group was significantly shorter than db/m group (p db/db and crp/db/db groups (p > 0.05). Maximum loading and energy yield in mechanical test were similar among groups while the elastic modulus in db/db and crp/db/db significantly lower than db/m. The leptin-receptor mice is not a proper model for secondary osteoporosis associated with T2DM.

C-reactive protein (CRP) is associated with progressive diabetic nephropathy in patients with type-2 diabetes (T2DN). However, role of CRP in T2DN remains unclear. We report here that CRP is pathogenic in T2DN in db/db mice that express human CRP (CRPtg-db/db). Compared to the littermate db/db mice, CRPtg-db/db developed more severe T2DN, showing higher levels of fasting blood glucose and microalbuminuria and more progressive renal inflammation and fibrosis. Enhanced T2DN in CRPtg-db/db mice were associated with over-activation of CRP-CD32b, NF-κB, TGF-β/Smad3 and mTOR signaling. Further studies in vitro defined that CRP activated Smad3 directly at 15 mins via the CD32b- ERK/p38 MAP kinase crosstalk pathway and indirectly at 24 hours through a TGF-β1-dependent mechanism. Importantly, CRP also activated mTOR signaling at 30 mins via a Smad3-dependent mechanism as Smad3 bound mTOR physically and CRP-induced mTOR signaling was abolished by a neutralizing CD32b antibody and a specific Smad3 inhibitor. Finally, we also found that CRP induced renal fibrosis through a CD32b-Smad3-mTOR pathway because blocking mTOR signaling with rapamycin inhibited CRP-induced CTGF and collagen I expression. Thus, CRP is pathogenic in T2DN. CRP may promote CD32b- NF-κB signaling to mediate renal inflammation; whereas, CRP may enhance renal fibrosis in T2DN via CD32b-Smad3-mTOR signaling.

The TGF-β/MAD homologue (SMAD) and nuclear factor κB (NF-κB) signalling pathways have been shown to play a critical role in the development of renal fibrosis and inflammation in diabetic nephropathy. We therefore examined whether targeting these pathways by a kidney-targeting Smad7 gene transfer has therapeutic effects on renal lesions in the db/db mouse model of type 2 diabetes.We delivered Smad7 plasmids into the kidney of db/db mice using kidney-targeting, ultrasound-mediated, microbubble-inducible gene transfer. The histopathology, ultrastructural pathology and pathways of TGF-β/SMAD2/3-mediated fibrosis and NF-κB-dependent inflammation were evaluated.In this mouse model of type 2 diabetes, Smad7 gene therapy significantly inhibited diabetic kidney injury, compared with mice treated with empty vectors. Symptoms inhibited included: (1) proteinuria and renal function impairment; (2) renal fibrosis such as glomerular sclerosis, tubulo-interstitial collagen matrix abundance and renal inflammation, including Inos (also known as Nos2), Il1b and Mcp1 (also known as Ccl2) upregulation, as well as macrophage infiltration; and (3) podocyte and endothelial cell injury as demonstrated by immunohistochemistry and/or electron microscopy. Further study demonstrated that the improvement of type 2 diabetic kidney injury by overexpression of Smad7 was associated with significantly inhibited local activation of the TGF-β/SMAD and NF-κB signalling pathways in the kidney.Our results clearly demonstrate that kidney-targeting Smad7 gene transfer may be an effective therapy for type 2 diabetic nephropathy, acting via simultaneous modulation of the TGF-β/SMAD and NF-κB signalling pathways.

Although C-reactive protein (CRP) has been implicated as a risk factor in diabetes, its pathogenic importance in diabetic kidney disease (DKD) remains unclear. The present study investigated the potential role of CRP in DKD.Diabetes was induced by streptozotocin in human CRP transgenic and wild-type mice for assessment of kidney injury at 24 weeks by real-time PCR, immunohistochemistry and western blot analysis. In vitro, the pathogenic effect of CRP was investigated using human kidney tubular epithelial cells cultured with high glucose and/or CRP.We found that CRP transgenic mice developed much more severe diabetic kidney injury than wild-type mice, as indicated by a significant increase in urinary albumin excretion and kidney injury molecule-1 abundance, enhanced infiltration of macrophages and T cells, and upregulation of pro-inflammatory cytokines (IL-1β, TNFα) and extracellular matrix (collagen I, III and IV). Enhanced renal inflammation and fibrosis in CRP transgenic mice was associated with upregulation of CRP receptor, CD32a, and over-activation of the TGF-β/SMAD and nuclear factor κB signalling pathways. In vitro, CRP significantly upregulated pro-inflammatory cytokines (IL-1β, TNFα, monocyte chemoattractant protein-1 [MCP-1]) and pro-fibrotic growth factors (TGF-β1, connective tissue growth factor [CTGF]) via CD32a/64. CRP was induced by high glucose, which synergistically promoted high glucose-mediated renal inflammation and fibrosis.CRP is not only a biomarker, but also a mediator in DKD. Enhanced activation of TGF-β/SMAD and nuclear factor κB signalling pathways may be the mechanisms by which CRP promotes renal inflammation and fibrosis under diabetic conditions.

OBJECTIVE - Although Smad3 has been considered as a downstream mediator of transforming growth factor-β (TGF-β) signaling in diabetes complications, the role of Smad7 in diabetes remains largely unclear. The current study tests the hypothesis that Smad7 may play a protective role and has therapeutic potential for diabetic kidney disease. RESEARCH DESIGN AND METHODS - Protective role of Smad7 in diabetic kidney disease was examined in streptozotocin-induced diabetic mice that have Smad7 gene knockout (KO) and in diabetic rats given Smad7 gene transfer using an ultrasound-microbubble-mediated technique. RESULTS - We found that mice deficient for Smad7 developed more severe diabetic kidney injury than wild-type mice as evidenced by a significant increase in microalbuminuria, renal fibrosis (collagen I, IV, and fibronectin), and renal inflammation (interleukin-1β [IL-1β], tumor necrosis factor-α [TNF-α], monocyte chemoattractant protein-1 [MCP-1], intracellular adhesion molecule-1 [ICAM-1], and macrophages). Further studies revealed that enhanced renal fibrosis and inflammation in Smad7 KO mice with diabetes were associated with increased activation of both TGF-β/Smad2/3 and nuclear factor-κB (NF-κB) signaling pathways. To develop a therapeutic potential for diabetic kidney disease, Smad7 gene was transferred into the kidney in diabetic rats by an ultrasound-microbubble-mediated technique. Although overexpression of renal Smad7 had no effect on levels of blood glucose, it significantly attenuated the development of microalbuminuria, TGF-β/Smad3-mediated renal fibrosis such as collagen I and IV and fibronectin accumulation and NF-κB/p65-driven renal inflammation including IL-1β, TNF-α, MCP-1, and ICAM-1 expression and macrophage infiltration in diabetic rats. CONCLUSIONS-Smad7 plays a protective role in diabetic renal injury. Overexpression of Smad7 may represent a novel therapy for the diabetic kidney complication. © 2011 by the American Diabetes Association., link_to_subscribed_fulltext

C-reactive protein (CRP) is a mediator of systemic inflammation. Peritoneal dialysis (PD) is known to cause peritoneal inflammation and fibrosis. We compare the degree of peritoneal inflammation and fibrosis in wild-type (WT) and CRP-transgenic (Tg) mice after PD treatment.WT (n = 7) and CRP-Tg (n = 10) C57BL/6 J mice (all male, 10-12 weeks old) were injected intra-peritoneally with 4.25% dextrose PD solution (3 mL/mouse) daily for 28 days, followed by a 2-h peritoneal equilibration test (PET). The mice were then killed. Parietal peritoneal and omental tissues were collected for the assessment of inflammation and fibrosis.After 28 days of PD treatment, CRP-Tg mice had higher dialysate-to-plasma (D/P) creatinine ratio than that of WT mice. Parietal peritoneum of the CRP-Tg mice was more cellular and thicker than that of the WT mice. CRP-Tg mice also had higher connective tissue growth factor (CTGF), intercellular adhesion molecule 1 (ICAM1) and tumor necrosis factor α (TNFα) RNA expressions as well as immunohistochemical staining in the parietal peritoneum than that of the WT mice.CRP-Tg mice have significantly more inflammation and fibrosis than WT mice after PD treatment. Our results suggest that CRP play a role in inflammation and fibrosis induced by PD. The implication of our results to human PD therapy needs further investigations.