Increasing evidence shows that TGF-β1 is a key mediator in diabetic nephropathy (DN) and induces renal fibrosis positively by Smad3 but negatively by Smad7. However, treatment of DN by blocking the TGF-β/Smad pathway remains limited. The present study investigated the anti-fibrotic effect of a traditional Chinese medicine, Chaihuang-Yishen granule (CHYS), on DN.
Research Design and Methods
Protective role of CHYS in DN was examined in an accelerated type 1 DN induced by streptozotocin in uninephrectomized Wistar rats. CHYS, at a dose of 0.56 g/kg body weight, was administered by a daily gastric gavage for 20 weeks and the therapeutic effect and potential mechanisms of CHYS on diabetic kidney injury were examined.
Treatment with CHYS attenuated diabetic kidney injury by significantly inhibiting 24-h proteinuria and progressive renal fibrosis including glomerulosclerotic index, tubulointerstitial fibrosis index, and upregulation of extracellular matrix (collagen I, IV, and fibronectin), despite the same levels of blood glucose. Further studies revealed that inhibition of renal fibrosis in CHYS-treated diabetic rats was associated with inhibition of TGF-β1/Smad3 signaling as demonstrated by upregulation of Smad7 but downregulation of TGF-β1, TGF-β receptors, activation of Smad3, and expression of miRNA-21.
CHYS may be a therapeutic agent for DN. CHYS attenuates DN by blocking TGF-β/Smad3-mediated renal fibrosis.
Tissue kallikrein (KLK1) expression is up-regulated in human diabetic kidney tissue and induced by high glucose (HG) in human proximal tubular epithelial cells (PTEC). Since the kallikrein-kinin system (KKS) has been linked to cellular inflammatory process in many diseases, it is likely that KLK1 expression may mediate the inflammatory process during the development of diabetic nephropathy. In this study, we explored the role of KLK1 in tubular pro-inflammatory responses under the diabetic milieu. Recombinant KLK1 stimulated the production of inflammatory cytokines in PTEC via the activation of p42/44 and p38 MAPK signaling pathways. Molecular knockdown of endogenous KLK1 expression by siRNA transfection in PTEC attenuated advanced glycation end-products (AGE)-induced IL-8 and ICAM-1 productions in vitro. Interestingly, exposure of PTEC to KLK1 induced the expression of protease-activated receptors (PARs). There was a 2.9-fold increase in PAR-4, 1.4-fold increase in PAR-1 and 1.2-fold increase in PAR-2 mRNA levels. Activation of PAR-4 by a selective agonist was found to elicit the pro-inflammatory and pro-fibrotic phenotypes in PTEC while blockade of the receptor by specific antagonist attenuated high glucose-induced IL-6, CCL-2, CTGF and collagen IV expression. Calcium mobilization by the PAR-4 agonist in PTEC was desensitized by pretreatment with KLK1. Consistent with these in vitro findings, there was a markedly up-regulation of tubular PAR-4 expression in human diabetic renal cortical tissues. Together, these results suggest that up-regulation of KLK1 in tubular epithelial cells may mediate pro-inflammatory pathway and PAR activation during diabetic nephropathy and provide a new therapeutic target for further investigation.
Rapid growth of diabetes and diabetic kidney disease exerts a great burden on society. Owing to the lack of effective treatments for diabetic kidney disease, treatment relies on drugs that either reduces its progression or involve renal replacement therapies, such as dialysis and kidney transplantation. It is urgent to search for biomarkers for early diagnosis and effective therapy. The discovery of microRNAs had lead to a new era of post-transcriptional regulators of gene expression. Studies from cells, experimental animal models and patients under diabetic conditions demonstrate that expression patterns of microRNAs are altered during the progression of diabetic kidney disease. Functional studies indicate that the ability of microRNAs to bind 3′ untranslated region of messenger RNA not only shows their capability to regulate expression of target genes, but also their therapeutic potential to diabetic kidney disease. The presence of microRNAs in plasma, serum, and urine has been shown to be possible biomarkers in diabetic kidney disease. Therefore, identification of the pathogenic role of microRNAs possesses an important clinical impact in terms of prevention and treatment of progression in diabetic kidney disease because it allows us to design novel and specific therapies and diagnostic tools for diabetic kidney disease.
Micro ribonucleic acids (miRNAs) are short noncoding RNAs that inhibit gene expression through the post-transcriptional repression of their target mRNAs. Increasing evidence shows that miRNAs have emerged as key players in diverse biologic processes. Aberrant miRNA expression is also closely related to various human diseases, including kidney diseases. From clinical and experimental animal studies, emerging evidence demonstrates a critical role for miRNAs in renal pathophysiology. Renal fibrosis is the hallmark of various chronic kidney diseases and transforming growth factor beta (TGF-β) is recognized as a vital mediator of renal fibrosis because it can induce production of extracellular matrix proteins resulting in dysfunction of the kidneys. The relationship between TGF-β signaling and miRNAs expression during renal diseases has been recently established. TGF-β positively or negatively regulates expression of several miRNAs, such as miR-21, miR-192, miR-200, and miR-29. Both miR-192 and miR-21 are positively regulated by TGF-β1/Smad3 signaling and play a pathological role in kidney diseases. Conversely, members of both miR-29 and miR-200 families are negatively regulated by TGF-β/Smad3 and play a protective role in renal fibrosis by inhibiting the deposition of extracellular matrix and preventing epithelial-to-mesenchymal transition, respectively. Clinically, levels of miRNAs in circulation and urine may be potential biomarkers for detecting early stages of renal diseases and targeting miRNAs also provides promising therapeutic effects in rodent models of chronic kidney disease. However, mechanisms and roles of miRNAs under disease conditions remain to be explored. Thus, understanding the function of miRNAs in the pathogenesis of kidney diseases may offer an innovative approach for both early diagnosis and treatment of renal diseases.
microRNAs; kidney diseases; renal fibrosis; TGF-β signaling
Smad7 has been shown to negatively regulate fibrosis and inflammation, but its role in angiotensin II (Ang II)-induced hypertensive cardiac remodeling remains unknown. Therefore, the present study investigated the role of Smad7 in hypertensive cardiopathy induced by angiotensin II infusion. Hypertensive cardiac disease was induced in Smad7 gene knockout (KO) and wild-type (WT) mice by subcutaneous infusion of Ang II (1.46 mg/kg/day) for 28 days. Although equal levels of high blood pressure were developed in both Smad7 KO and WT mice, Smad7 KO mice developed more severe cardiac injury as demonstrated by impairing cardiac function including a significant increase in left ventricular (LV) mass (P<0.01),reduction of LV ejection fraction(P<0.001) and fractional shortening(P<0.001). Real-time PCR, Western blot and immunohistochemistry detected that deletion of Smad7 significantly enhanced Ang II-induced cardiac fibrosis and inflammation, including upregulation of collagen I, α-SMA, interleukin-1β, TNF-α, and infiltration of CD3+ T cells and F4/80+ macrophages. Further studies revealed that enhanced activation of the Sp1-TGFβ/Smad3-NF-κB pathways and downregulation of miR-29 were mechanisms though which deletion of Smad7 promoted Ang II-mediated cardiac remodeling. In conclusions, Smad7 plays a protective role in AngII-mediated cardiac remodeling via mechanisms involving the Sp1-TGF-β/Smad3-NF.κB-miR-29 regulatory network.
The emergence and spread of antibiotic-resistant Neisseria gonorrhoeae has led to difficulties in treating patients, and novel strategies to prevent and treat this infection are urgently needed. Here, we examined 21 different nanomaterials for their potential activity against N. gonorrhoeae (ATCC 49226). Silver nanoparticles (Ag NPs, 120 nm) showed the greatest potency for reducing N. gonorrhoeae colony formation (MIC: 12.5 µg/ml) and possessed the dominant influence on the antibacterial activity with their properties of the nanoparticles within a concentration range that did not induce cytotoxicity in human fibroblasts or epithelial cells. Electron microscopy revealed that the Ag NPs significantly reduced bacterial cell membrane integrity. Furthermore, the use of clinical isolates of multidrug-resistant N. gonorrhoeae showed that combined treatment with 120 nm Ag NPs and cefmetazole produced additive effects. This is the first report to screen the effectiveness of nanomaterials against N. gonorrhoeae, and our results indicate that 120 nm Ag NPs deliver low levels of toxicity to human epithelial cells and could be used as an adjuvant with antibiotic therapy, either for topical use or as a coating for biomaterials, to prevent or treat multidrug-resistant N. gonorrhoeae.
Smad7 is an inhibitory Smad and plays a protective role in obstructive and diabetic kidney disease. However, the role and mechanisms of Smad7 in hypertensive nephropathy remains unexplored. Thus, the aim of this study was to investigate the role and regulatory mechanisms of Smad7 in ANG II-induced hypertensive nephropathy. Smad7 gene knockout (KO) and wild-type (WT) mice received a subcutaneous infusion of ANG II or control saline for 4 weeks via osmotic mini-pumps. ANG II infusion produced equivalent hypertension in Smad7 KO and WT mice; however, Smad7 KO mice exhibited more severe renal functional injury as shown by increased proteinuria and reduced renal function (both p<0.05) when compared with Smad7 WT mice. Enhanced renal injury in Smad7 KO mice was associated with more progressive renal fibrosis with elevated TGF-β/Smad3 signalling. Smad7 KO mice also showed more profound renal inflammation including increased macrophage infiltration, enhanced IL-1β and TNF-α expression, and a marked activation of NF-κB signaling (all p<0.01). Further studies revealed that enhanced ANG II-mediated renal inflammation and fibrosis in Smad7 KO mice were also associated with up-regulation of Sp1 but downregulation of miR-29b expression. Taken together, the present study revealed that enhanced Sp1-TGF-β1/Smad3-NF-κB signaling and loss of miR-29 may be mechanisms by which deletion of Smad7 promotes ANG II-mediated renal fibrosis and inflammation. Thus, Smad7 may play a protective role in ANG II-induced hypertensive kidney disease.
Although blockade of Rho kinase with pharmacologic inhibitors ameliorates renal fibrosis and diabetic kidney disease (DKD), the underlined mechanisms remain largely unclear. The present study tested the hypothesis that ROCK1 may regulate the early development of albuminuria via the megalin/cubilin-dependent mechanism.
A DKD model was induced in ROCK1 knockout and wild-type mice by streptozotocin (STZ). The effect of deleted ROCK1 on urinary albumin excretion and the expression of megalin/cubilin were examined. In addition, the effect of blocking ROCK activities with an inhibitor (Y-27632) on tubular albumin reabsorption was tested in a normal rat tubular epithelial cell line (NRK52E) under high-glucose conditions. Expression of transforming growth factor (TGF)-β1, interleukin-1β and collagen-1 was also been examined.
Urinary albumin excretion was significantly increased in ROCK1 WT mice at 8 weeks after STZ injection. In contrast, mice lacking ROCK1 gene were protected against the development of albuminuria. This was associated with the protection against the loss of megalin/cubilin and an increase in TGF-β1, IL-1β, and fibrosis in the kidney. In vitro, we also found that blockade of Rho kinase with inhibitor Y-27632 prevented high-glucose-induced loss of megalin expression and an increase of TGF-β1, thereby increasing the absorption rate of FITC-labeled albumin by tubular epithelial cells.
ROCK1 may play a role in the development of albuminuria in DKD by downregulating the endocytosis receptors complex – megalin/cubilin.
Copyright © 2011 S. Karger AG, Basel
Diabetic kidney disease; Tubular cells, albuminuria; ROCK; Megalin; Cubilin
Liver fibrosis is a major cause of liver failure, but treatment remains ineffective. In the present study, we investigated the mechanisms and anti-hepatofibrotic activities of asiatic acid (AA) in a rat model of liver fibrosis induced by carbon tetrachloride (CCl4) and in vitro in TGF-beta1-stimulated rat hepatic stellate cell line (HSC-T6). Treatment with AA significantly attenuated CCl4-induced liver fibrosis and functional impairment in a dosage-dependent manner, including blockade of the activation of HSC as determined by inhibiting de novo alpha smooth muscle actin (a-SMA) and collagen matrix expression, and an increase in ALT and AST (all p<0.01). The hepatoprotective effects of AA on fibrosis were associated with upregulation of hepatic Smad7, an inhibitor of TGF-beta signaling, thereby blocking upregulation of TGF-beta1 and CTGF and the activation of TGF-beta/Smad signaling. The anti-fibrosis activity and mechanisms of AA were further detected in vitro in HSC-T6. Addition of AA significantly induced Smad7 expression by HSC-T6 cells, thereby inhibiting TGF-beta1-induced Smad2/3 activation, myofibroblast transformation, and collagen matrix expression in a dosage-dependent manner. In contrast, knockdown of Smad7 in HSC-T6 cells prevented AA-induced inhibition of HSC-T6 cell activation and fibrosis in response to TGF-beta1, revealing an essential role for Smad7 in AA-induced anti-fibrotic activities during liver fibrosis in vivo and in vitro. In conclusion, AA may be a novel therapeutic agent for liver fibrosis. Induction of Smad7-dependent inhibition of TGF-beta/Smad-mediated fibrogenesis may be a central mechanism by which AA protects liver from injury.
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.
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.
Smad7 plays a protective role in diabetic renal injury. Overexpression of Smad7 may represent a novel therapy for the diabetic kidney complication.
Neisseria gonorrhoeae infection is the second major cause of sexually transmitted diseases worldwide. Development of resistance to multiple classes of antimicrobials in N. gonorrhoeae has compromised treatment and disease control. Herein, we report the availability of the draft genome sequence of a multidrug-resistant N. gonorrhoeae isolate, TCDC-NG08107, which spread in groups of men who have sex with men (MSM) in Taiwan.
IL-17A is a pro-inflammatory cytokine that plays important role in inflammatory disease pathology and tumor microenvironment. The aim of this study is to investigate the effect of IL-17A on the progression of hepatocellular carcinoma (HCC).
Methodology and Principal Finding
Expression pattern of IL-17A in clinical HCC samples (n = 43) was determined by immunohistochemistry staining. Transcript levels of MMP2, MMP9 and IL-17A were measured in another 50 pairs (including tumor and related non-tumor tissues) HCC samples. Cell growth, focus formation, cell migration, invasion and western blot assays were used to characterize the functional and signaling mechanisms in IL-17A-treated HCC. Association study was used to identify clinical significance of IL-17A in HCC. Compared with paired non-tumor tissue, higher frequency of IL-17A-positive cells was detected in tumor tissues in HCCs with metastasis, and the frequency of IL-17A-positive cells was also significantly associated with poor prognosis of HCC (P = 0.01). Functional study found that IL-17A could promote HCC cell migration and invasion. Further molecular analysis also showed that IL-17A could upregulate MMP2 and MMP9 expression via NF-κB signaling activation.
IL-17A could promote HCC metastasis by the upregulation of MMP2 and MMP9 expression via activating NF-κB signaling pathway.
Interstitial fibrosis plays a major role in progression of renal diseases. Oncostatin M (OSM) is a cytokine that regulates cell survival, differentiation, and proliferation. Renal tissue from patients with chronic obstructive nephropathy was examined for OSM expression. The elevated levels in diseased human kidneys suggested possible correlation between OSM level and kidney tissue fibrosis. Indeed, unilateral ureteral obstruction (UUO), a model of renal fibrosis, increased OSM and OSM receptor (OSM-R) expression in a time-dependent manner within hours following UUO. In vitro, OSM overexpression in tubular epithelial cells (TECs) resulted in epithelial-myofibroblast transdifferentiation. cDNA microarray technology identified up-regulated expression of immune modulators in obstructed compared with sham-operated kidneys. In vitro, OSM treatment up-regulated CC chemokine ligand CCL7, and CXC chemokine ligand (CXCL)-14 mRNA in kidney fibroblasts. In vivo, treatment of UUO mice with neutralizing anti-OSM antibody decreased renal chemokines expression. In conclusion, OSM is up-regulated in kidney tissue early after urinary obstruction. Therefore, OSM might play an important role in initiation of renal fibrogenesis, possibly by inducing myofibroblast transdifferentiation of TECs as well as leukocyte infiltration. This process may, in turn, contribute in part to progression of obstructive nephropathy and makes OSM a promising therapeutic target in renal fibrosis.
Autoimmunity leads to the activation of innate effector pathways, pro-inflammatory cytokine production, and end-organ injury. Macrophage migration inhibitory factor (MIF) is an upstream activator of the innate response that mediates the recruitment and retention of monocytes via CD74 and associated chemokine receptors, and it has a role in the maintenance of B lymphocytes. High-expression MIF alleles also are associated with end-organ damage in different autoimmune diseases. We assessed the therapeutic efficacy of ISO-1, an orally bioavailable, MIF antagonist, in two distinct models of systemic lupus erythematosus (SLE): the NZB/NZW F1 and the MRL/lpr mouse strains. ISO-1, like anti-MIF, inhibited the interaction between MIF and its receptor, CD74, and in each model of disease, it reduced functional and histological indices of glomerulonephritis, CD74+ and CXCR4+ leukocyte recruitment, and pro-inflammatory cytokine and chemokine expression. Neither autoantibody production nor T and B cell activation were significantly affected, pointing to the specificity of MIF antagonism in reducing excessive pro-inflammatory responses. These data highlight the feasibility of targeting the MIF–MIF receptor interaction by small molecule antagonism and support the therapeutic value of downregulating MIF-dependent pathways of tissue damage in SLE.
Autoimmunity; Cytokine; Innate Immunity
Among 254 Neisseria gonorrhoeae isolates from a sexually transmitted infection (STI) clinic in northern Taiwan, 69 isolates were found to contain the mosaic penA (MA) gene and were associated with elevated cefixime and ceftriaxone MICs. Most of these MA gene-harboring isolates were also resistant to penicillin (71.4%) and ciprofloxacin (100%) and were from men who have sex with men (MSM) or from bisexual men (81.2%). Three major sequence types (ST835, ST2180, and ST2253) constituted 55.7% of these isolates. The major sequence types harboring the mosaic penA gene may represent major sexual networks responsible for the emergence/introduction and the spread of the multidrug-resistant clones in Taiwan.
TGF-β1 has been long considered as a key mediator in renal fibrosis and induces renal scarring largely by activating its downstream Smad signaling pathway. Interestingly, while mice overexpressing active TGF-β1 develop progressive renal injury, latent TGF-β1 plays a protective role in renal fibrosis and inflammation. Under disease conditions, Smad2 and Smad3 are highly activated, while Smad7 is degraded through the ubiquitin proteasome degradation mechanism. In addition to TGF-β1, many pathogenic mediators such as angiotensin II and advanced glycation end products can also activate the Smad pathway via both TGF-β-dependent and independent mechanisms. Smads interact with other signaling pathways, such as the MAPK and NF-κB pathways, to positively or negatively regulate renal inflammation and fibrosis. Studies from gene knockout mice demonstrate that TGF-β1 acts by stimulating its downstream Smads to diversely regulate kidney injury. In the context of renal fibrosis and inflammation, Smad3 is pathogenic, while Smad2 and Smad7 are protective. Smad4 exerts its diverse roles by transcriptionally enhancing Smad3-mediated renal fibrosis while inhibiting NF-κB-driven renal inflammation via a Smad7-dependent mechanism. Furthermore, we also demonstrated that TGF-β1 acts by stimulating Smad3 to positively or negatively regulate microRNAs to exert its fibrotic role in kidney disease. In conclusion, TGF-β/Smad signaling is a major pathway leading to kidney disease. Smad3 is a key mediator in renal fibrosis and inflammation, whereas Smad2 and Smad7 are renoprotective. Smad4 exerts its diverse role in promoting renal fibrosis while inhibiting inflammation. Thus, targeting the downstream TGF-β/Smad3 signaling pathway by gene transfer of either Smad7 or Smad3-dependent microRNAs may represent a specific and effective therapeutic strategy for kidney disease.
TGF-β/Smads; fibrosis; inflammation; anti-TGF-β therapy; microRNAs.
There is evidence that disaccharide sucrose produce a greater increase in serum fructose and triglycerides (TGs) than the effect produced by their equivalent monosaccharides, suggesting that long-term exposure to sucrose or fructose + glucose could potentially result in different effects.
Aim of the study
We studied the chronic effects of a combination of free fructose and glucose relative to sucrose on rat liver.
Rats were fed either a combination of 30% fructose and 30% glucose (FG) or 60% sucrose (S). Control rats were fed normal rat chow (C). All rats were pair fed and were followed for 4 months. After killing, blood chemistries and liver tissue were examined.
Both FG-fed- and S-fed rats developed early features of metabolic syndrome when compared with C. In addition, both diets induced hepatic alterations, including variable increases in hepatic TG accumulation and fatty liver, an increase in uric acid content in the liver, as well as an increase in hepatic levels of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-α) measured in liver homogenates.
Diets containing 30% of fructose either as free fructose and glucose, or as sucrose, induce metabolic syndrome, intrahepatic accumulation of uric acid and TGs, increased MCP-1 and TNF-α as well as fatty liver in rats. It will be relevant to determine clinically whether pharmacological reduction in uric acid levels might have a therapeutic advantage in the treatment of non-alcoholic fatty liver disease.
Non-alcoholic steatosis; Metabolic syndrome; Sucrose; Fructose
From April 2006 to August 2007, a total of 146 Neisseria gonorrhoeae isolates collected from 139 male patients in Taipei, Taiwan, were analyzed by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and antibiotic susceptibility testing. The resistance rates of all isolates to ciprofloxacin, cefpodoxime, and cefixime were 76.7 (112/146), 21.2 (31/146), and 16.4% (24/146), respectively. NG-MAST identified 71 sequence types (STs), of which 21 STs contained 2 to 21 isolates. The isolates that belonged to the three major ST clusters typically were from patients who had specific epidemiological characteristics (such as sexual orientation and human immunodeficiency virus status). The major ST clones exhibited distinct resistance profiles and are associated with specific groups at high risk of human immunodeficiency virus and syphilis infections.
It has been shown that blockade of TGF-β1 signaling with Smad7 prevents experimental peritoneal fibrosis. The present study investigated whether Smad7 has a therapeutic effect on established peritoneal fibrosis associated with peritoneal dialysis (PD).
A rat model of peritoneal fibrosis was induced by a daily intraperitoneal infusion of 4.25% Dianeal. After peritoneal fibrosis had been established on day 14, groups of 6 rats were treated intraperitoneally with gene transfer of Smad7 or control plasmids using an ultrasound-microbubble-mediated system for 2 weeks until day 28. In addition, a group of 6 diseased rats was euthanized on day 14 before treatment as the basal disease control.
Compared to the control-treatment animals on day 28, real-time PCR, Western blot, and confocal microscopy revealed that Smad7 gene transfer significantly attenuated the increased peritoneal fibrosis including the thickening of fibrotic peritoneum, accumulation of α-SMA and collagen I, and an improvement in peritoneal dysfunction (all p < 0.05). Importantly, Smad7 treatment also improved the severity of peritoneal fibrosis and functional impairment when compared to those on day 14 before treatment (all p < 0.05). Inhibition of the established peritoneal fibrosis by Smad7 was associated with an abrogation of TGF-β signaling and upregulation of TGF-β1 and PAI-1.
Smad7 gene therapy is able to inhibit established peritoneal fibrosis in a rat model of PD. Results from this study suggest that Smad7 may be a therapeutic agent for the treatment of peritoneal fibrosis associated with PD.
Gene therapy; Smad7; Peritoneal fibrosis; Peritoneal dialysis; TGF-β1; Ultrasound
The identification of Chlamydia trachomatis genotypes is important for both the study of molecular epidemiology and infection control. We have developed a microsphere suspension array assay that can identify C. trachomatis genotypes rapidly and accurately and also discriminate among multiple genotypes in one clinical specimen.
Angiotensin II (Ang II) plays a pivotal role in vascular fibrosis, which leads to serious complications in hypertension and diabetes. However, the underlying signaling mechanisms are largely unclear. In hypertensive patients, we found that arteriosclerosis was associated with the activation of Smad2/3. This observation was further investigated in vitro by stimulating mouse primary aorta vascular smooth muscle cells (VSMCs) with Ang II. There were several novel findings. First, Ang II was able to activate an early Smad signaling pathway directly at 15 to 30 minutes. This was extracellular signal-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) dependent but transforming growth factor-β (TGF-β) independent because Ang II–induced Smad signaling was blocked by addition of ERK1/2 inhibitor and by dominant-negative (DN) ERK1/2 but not by DN-Tβ RII or conditional deletion of Tβ RII. Second, Ang II was also able to activate the late Smad2/3 signaling pathway at 24 hours, which was TGF-β dependent because it was blocked by the anti–TGF-β antibody and DN-TβRII. Finally, activation of Smad3 but not Smad2 was a key and necessary mechanism of Ang II–induced vascular fibrosis because Ang II induced Smad3/4 promoter activities and collagen matrix expression was abolished in VSMCs null for Smad3 but not Smad2. Thus, we concluded that Ang II induces vascular fibrosis via both TGF-β– dependent and ERK1/2 MAPK-dependent Smad signaling pathways. Activation of Smad3 but not Smad2 is a key mechanism by which Ang II mediates arteriosclerosis.
angiotensin; TGF-β; Smads; vascular fibrosis
Background: Angiotensin II is a key mediator of diabetes-related vascular disease. It is now recognized that in addition to angiotensin converting enzyme (ACE), chymase is an important alternative angiotensin II generating enzyme in hypertension and diabetes. However, the mechanism of induction of chymase in diabetes remains unknown.
Methods and Results: Here we report that chymase is upregulated in coronary and renal arteries in patients with diabetes by immunohistochemistry. Upregulation of vascular chymase is associated with deposition of advanced glycation end products (AGEs), increase in expression of the receptor for AGEs (RAGE), and activation of ERK1/2 MAP kinase. In vitro, AGEs can induce chymase expression and chymase-dependent angiotensin II generation in human vascular smooth muscle cells via the RAGE-ERK1/2 MAP kinase-dependent mechanism. This is confirmed by blockade of AGE-induced vascular chymase expression with a neutralizing RAGE antibody and an inhibitor to ERK1/2, and by overexpression of the dominant negative-ERK1/2. Compared to ACE, chymase contributes to the majority of angiotensin II production (more than 70%, p<0.01) in response to AGEs. Further more, AGE-induced Angiotensin II production is blocked by the anti-RAGE antibody and by inhibition of ERK1/2 MAP kinase activities.
Conclusions: Advanced glycation end products, a hallmark of diabetes, induce chymase via the RAGE-ERK1/2 MAP kinase pathway. Chymase initiates an important alternative angiotensin II generating pathway in diabetes and may play a critical role in diabetic vascular disease.
Advanced Glycation End products; Chymase; Angiotensin II
Assuming multiple loci play a role in regulating the expression level of a single phenotype, we propose a new approach to identify cis- and trans-acting loci that regulate gene expression. Using the Problem 1 data set made available for Genetic Analysis Workshop 15 (GAW15), we identified many expression phenotypes that have significant evidence of association and linkage to one or more chromosomal regions. In particular, six of ten phenotypes that we found to be regulated by cis- and trans-acting loci were also mapped by a previous analysis of these data in which a total of 27 phenotypes were identified with expression levels regulated by cis-acting determinants. However, in general, the p-values associated with these regulators identified in our study were larger than in their studies, since we had also identified other factors regulating expression. In fact, we found that most of the gene expression phenotypes are influenced by at least one trans-acting locus. Our study also shows that much of the observable heritability in the phenotypes could be explained by simple single-nucleotide polymorphism associations; residual heritability was reduced and the remaining heritability may represent complex regulation systems with interactions or noise.
Focusing on chromosome 1, a recursive partitioning linkage algorithm (RP) was applied to perform linkage analysis on the rheumatoid arthritis NARAC data, incorporating covariates such as HLA-DRB1 genotype, age at onset, severity, anti-cyclic citrullinated peptide (anti-CCP), and life time smoking. All 617 affected sib pairs from the ascertained families were used, and an RP linkage model was used to identify linkage possibly influenced by covariates. This algorithm includes a likelihood ratio (LR)-based splitting rule, a pruning algorithm to identify optimal tree size, and a bootstrap method for final tree selection.
The strength of the linkage signals was evaluated by empirical p-values, obtained by simulating marker data under null hypothesis of no linkage. Two suggestive linkage regions on chromosome 1 were detected by the RP linkage model, with identified associated covariates HLA-DRB1 genotype and age at onset. These results suggest possible gene × gene and gene × environment interactions at chromosome 1 loci and provide directions for further gene mapping.