Monocytes induce proximal tubular epithelial-mesenchymal transition through NF-kappa B dependent upregulation of ICAM-1

Fibrosis in Chronic Kidney Disease: Pathophysiology and Therapeutic Targets

Chronic kidney disease (CKD) is a slowly progressive condition characterized by decreased kidney function, tubular injury, oxidative stress, and inflammation. CKD is a leading global health burden that is asymptomatic in early stages but can ultimately cause kidney failure. Its etiology is complex and involves dysregulated signaling pathways that lead to fibrosis. Transforming growth factor (TGF)-β is a central mediator in promoting transdifferentiation of polarized renal tubular epithelial cells into mesenchymal cells, resulting in irreversible kidney injury. While current therapies are limited, the search for more effective diagnostic and treatment modalities is intensive. Although biopsy with histology is the most accurate method of diagnosis and staging, imaging techniques such as diffusion-weighted magnetic resonance imaging and shear wave elastography ultrasound are less invasive ways to stage fibrosis. Current therapies such as renin-angiotensin blockers, mineralocorticoid receptor antagonists, and sodium/glucose cotransporter 2 inhibitors aim to delay progression. Newer antifibrotic agents that suppress the downstream inflammatory mediators involved in the fibrotic process are in clinical trials, and potential therapeutic targets that interfere with TGF-β signaling are being explored. Small interfering RNAs and stem cell-based therapeutics are also being evaluated. Further research and clinical studies are necessary in order to avoid dialysis and kidney transplantation.

Identification of the key immune-related genes and immune cell infiltration changes in renal interstitial fibrosis

Background

Chronic kidney disease (CKD) is the third-leading cause of premature mortality worldwide. It is characterized by rapid deterioration due to renal interstitial fibrosis (RIF) via excessive inflammatory infiltration. The aim of this study was to discover key immune-related genes (IRGs) to provide valuable insights and therapeutic targets for RIF in CKD.

Materials and methods

We screened differentially expressed genes (DEGs) between RIF samples from CKD patients and healthy controls from a public database. Least absolute shrinkage and selection operator regression analysis and receiver operating characteristic curve analysis were applied to identify significant key biomarkers. The single-sample Gene Set Enrichment Analysis (ssGSEA) algorithm was used to analyze the infiltration of immune cells between the RIF and control samples. The correlation between biomarkers and immune cell composition was assessed.

Results

A total of 928 DEGs between CKD and control samples from six microarray datasets were found, 17 overlapping immune-correlated DEGs were identified by integration with the ImmPort database, and six IRGs were finally identified in the model: apolipoprotein H (APOH), epidermal growth factor (EGF), lactotransferrin (LTF), lysozyme (LYZ), phospholipid transfer protein (PLTP), and secretory leukocyte peptidase inhibitor (SLPI). Two additional datasets and in vivo experiments indicated that the expression levels of APOH and EGF in the fibrosis group were significantly lower than those in the control group, while the expression levels of LTF, LYZ, PLTP, and SLPI were higher (all P < 0.05). These IRGs also showed a significant correlation with renal function impairment. Moreover, four upregulated IRGs were positively associated with various T cell populations, which were enriched in RIF tissues, whereas two downregulated IRGs had opposite results. Several signaling pathways, such as the "T cell receptor signaling pathway" and "positive regulation of NF-κB signaling pathway", were discovered to be associated not only with immune cell infiltration, but also with the expression levels of six IRGs.

Conclusion

In summary, six IRGs were identified as key biomarkers for RIF, and exhibited a strong correlation with various T cells and with the NF-κB signaling pathway. All these IRGs and their signaling pathways may evolve as valuable therapeutic targets for RIF in CKD.

Novel small-molecule compound VCP979 attenuates renal fibrosis in male rats with unilateral ureteral obstruction

Renal fibrosis is a hallmark of chronic kidney disease, while efficient therapy against renal fibrosis is still lacking. In this study, we investigated the role of a novel small-molecule compound VCP979 on renal fibrosis and inflammation in a rat model of unilateral ureteral obstruction (UUO). One week after the UUO surgery, rats were administered VCP979 by gavage for one week, and after treatment, magnetic resonance imaging of T1rho mapping and histopathological analysis were performed to evaluate renal fibrosis in vivo and ex vivo. This study showed that treatment with VCP979 effectively reduced renal fibrosis, extracellular matrix accumulation, and alleviated epithelial-mesenchymal transition in UUO rats, as well as improved renal function. In vivo T1rho mapping displayed increased T1rho values in the UUO rats, which was decreased after VCP979 treatment, and a positive correlation was detected between the T1rho values and the percentage of fibrotic area. Moreover, the administration of VCP979 also ameliorated the inflammatory cytokines expression and the infiltration of macrophages in renal tissues. Mechanistically, VCP979 treatment inhibited the activation of p38 mitogen-activated protein kinase, nuclear factor-kappa B, and transforming growth factor-β1/Smads signaling pathways. These results indicated that VCP979 could be an effective therapeutic agent for alleviating renal fibrosis and inflammation in the rat model of UUO via its antifibrotic and anti-inflammatory effects.

DNA methyltransferase 1 knockdown reverses PTEN and VDR by mediating demethylation of promoter and protects against renal injuries in hepatitis B virus-associated glomerulonephritis

Background

Aberrant DNA methylation patterns, including hypermethylation of key genes that inhibit fibrosis and inflammation, have been described in human kidney diseases. However, the role of DNA methyltransferase 1 (DNMT1) in hepatitis B virus-associated glomerulonephritis (HBV-GN) remains unclear.

Methods

We explored the underlying mechanism by establishing HBV X protein (HBx) overexpressing renal tubular epithelial (HK-2) cells and human podocytes with DNMT1 knockdown. Using RNA-sequencing to determine the downstream targets of DNMT1 and evaluate its levels of promoter methylation. HBV transgenic mice were used to examine the effects of DNMT1 inhibitor on renal in vivo.

Results

DNMT1 was significantly upregulated in the renal tissue of HBV-GN patients, accompanied by injuries of HK-2 cells and podocytes. HBx markedly upregulated DNMT1 and induced epithelial-mesenchymal transition (EMT) and inflammation in HK-2 cells and human podocytes. This increased DNMT1 expression was attenuated after DNMT1 knockdown, accompanied by restored HK-2 cells and podocyte injuries resulting from the activation of PI3K/Akt/mTOR and nuclear factor-kappa B (NF-κB) pathways. Hypermethylation of the phosphatase and tensin homolog (PTEN) promoter and vitamin D receptor (VDR) was induced in HBx-overexpressing HK-2 cells and podocytes, respectively, whereas DNMT1 knockdown effectively corrected these alterations. Furthermore, PTEN and VDR ablation resulted in marked EMT and inflammation induction in HBx-overexpressing HK-2 cells and human podocytes even with DNMT1 knockdown. Downregulation of the PI3K/Akt/mTOR-related pathway attenuated HBx-induced EMT and inflammation in HK-2 cells. Luciferase reporter assay revealed VDR as a direct target of the Snail family transcriptional repressor 1 (SNAI1) in HBx-overexpressing podocytes. DNA methylation inhibitor 5-azacytidine alleviated urinary protein and renal inflammation in HBV transgenic mice via PTEN-PI3K/Akt signaling and VDR signaling axis.

Conclusions

Our study clarifies the potential epigenetic mechanisms underlying HBx-induced renal injuries in HBV-GN and the renoprotective effects of inhibiting DNMT1, which can provide important insights into the development of treatments for HBV-GN.

Interaction Between Intrinsic Renal Cells and Immune Cells in the Progression of Acute Kidney Injury

A growing number of studies have confirmed that immune cells play various key roles in the pathophysiology of acute kidney injury (AKI) development. After the resident immune cells and intrinsic renal cells are damaged by ischemia and hypoxia, drugs and toxins, more immune cells will be recruited to infiltrate through the release of chemokines, while the intrinsic cells promote macrophage polarity conversion, and the immune cells will promote various programmed deaths, phenotypic conversion and cycle arrest of the intrinsic cells, ultimately leading to renal impairment and fibrosis. In the complex and dynamic immune microenvironment of AKI, the bidirectional interaction between immune cells and intrinsic renal cells affects the prognosis of the kidney and the progression of fibrosis, and determines the ultimate fate of the kidney.

Total flavonoids in Epimedium koreanum Nakai alleviated chronic renal failure via promoting AMPK activation

Chronic renal failure (CRF) is a result of the progression of chronic kidney diseases (CKD), a global health problem with a high cost of treatment and no ideal therapy. The aim of this study is to evaluate the pharmacological efficacy of the total flavonoids in Epimedium koreanum Nakai (TFE), a dietary supplement, against CRF and to determine the mechanism of actions. An adenine-induced CRF rat model and a TGF-β1 induced human kidney proximal tubule epithelial (HK-2) cell based in vitro renal fibrosis model were established and used to evaluate TFE's efficacy. Renal hemodynamics, biochemical indexes, inflammatory cytokines, histopathology and the reactive oxygen species (ROS) levels were determined to evaluate the efficacy of TFE on CRF. NMR-based metabolomics, immunohistochemical (IHC) staining, immunofluorescence (IF) staining, quantitative real time-PCR (qRT-PCR) and western blotting were conducted to determine the mechanism. The results showed that TFE had a significant effect on CRF at 150 mg kg^-1 d^-1 and could significantly alleviate renal fibrosis in the animal model. Twelve potential biomarkers, which mainly involve energy metabolism pathways, for CRF were identified using the metabolomics approach. The mechanism study suggested that TFE regulated AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) and AMPK/silent information regulator 1 (SIRT1)/nuclear factor kappa-B (NF-κB) signaling pathways. Furthermore, the effect of TFE was inhibited by compound C in the in vitro experiment, which also confirmed the above conclusion.

Curcumin attenuates renal interstitial fibrosis of obstructive nephropathy by suppressing epithelial-mesenchymal transition through inhibition of the TLR4/NF-кB and PI3K/AKT signalling pathways

CONTEXT

Renal interstitial fibrosis (RIF) is characterized by the accumulation of inflammatory cytokines and epithelial-mesenchymal transition (EMT). Curcumin exerts antifibrogenic, anti-inflammatory and antiproliferative effects.

OBJECTIVE

To explore the mechanisms underlying the effects of curcumin on RIF.

MATERIALS AND METHODS

Eight-week-old male C57BL/6 mice were intragastrically administered curcumin (50 mg/kg/day) for 14 days after undergoing unilateral ureteral obstruction (UUO) operations. Renal function (blood urea nitrogen [BUN] and serum creatinine [Scr]) and inflammatory cytokine levels were tested using colorimetric assays and ELISA, respectively. EMT markers were evaluated through immunohistochemistry, western blotting and qPCR. Transforming growth factor beta 1 (TGF-β1; 10 ng/mL) and lipopolysaccharides (LPS; 100 ng/mL) were used to stimulate EMT and an inflammatory response in human renal proximal tubular epithelial (HK-2) cells, respectively, for further investigation.

RESULTS

In vivo, curcumin significantly improved the levels of BUN and Scr by 28.7% and 21.3%, respectively. Moreover, curcumin reduced the levels of IL-6, IL-1β and TNF-α by 22.5%, 30.3% and 26.7%, respectively, and suppressed vimentin expression in UUO mice. In vitro, curcumin reduced the expression of vimentin and α-smooth muscle actin in TGF-β1-induced HK-2 cells. In LPS-induced HK-2 cells, curcumin decreased the release of IL-6, IL-1β and TNF-α by 43.4%, 38.1% and 28.3%, respectively. In addition, curcumin reduced the expression of TLR4, p-PI3K, p-AKT, p-NF- κB and p-IκBα in both LPS- and TGF-β1-induced HK-2 cells.

DISCUSSION AND CONCLUSIONS

Curcumin repressed EMT and the inflammatory response by inhibiting the TLR4/NF-κB and PI3K/AKT pathways, demonstrating its potential utility in RIF treatment.

Rosmarinic Acid Prevents Radiation-Induced Pulmonary Fibrosis Through Attenuation of ROS/MYPT1/TGFβ1 Signaling Via miR-19b-3p

The mechanism of pulmonary fibrosis caused by irradiation remains obscure. Since rosmarinic acid (RA) have anti-oxidant and anti-inflammatory properties, we aimed to evaluate the effect of RA on the X-ray-induced lung injury. Male rats received RA (30, 60, or 120 mg/kg) 7 days before 15 Gy of X-ray irradiation. Here, we showed that RA reduced X-ray-induced the expression of inflammatory related factors, and the level of reactive oxygen species. RA down-regulated the phosphorylation of nuclear factor kappa-B (NF-κB). We found that thoracic tumor patients whose lung regions received radiation showed lower level of microRNA-19b-3p (miR-19b-3p). Furthermore, we provided evidence that miR-19b-3p targets myosin phosphatase target subunit 1 (MYPT1), and RA attenuated RhoA/Rock signaling through upregulating miR-19b-3p, leading to the inhibition of fibrosis. In conclusion, RA may be an effective agent to relieve the pulmonary fibrosis caused by radiotherapy of thoracic tumor.

NF-κB interaction long non-coding RNA inhibits migration, invasion and epithelial-mesenchymal transition of cervical cancer cells through inhibiting NF-κB signaling pathways

The long non-coding RNA (lncRNA) NF-κB interaction lncRNA (NKILA) has been found to exert tumor suppressive effects in numerous types of carcinoma; however, the relationship between NKILA and cervical cancer (CC) remains largely unclear. The present study aimed to investigate the effects of NKILA on the proliferation and metastasis of CC cell lines, in addition to the related molecular mechanisms. Reverse transcription-quantitative PCR was used to detect the expression levels of NKILA in cancer tissues and cell lines. The constructed overexpression vector, pcDNA3.1NKILA, and its corresponding negative control sequence were transfected into CaSki cells and short hairpin RNA targeting NKILA and the corresponding negative control sequence were transfected into C-33A cells. Subsequently, the proliferative, migratory and invasive ability, as well as the process of epithelial-mesenchymal transition (EMT) of C-33 A and CaSki cells were analyzed by performing Cell Counting Kit-8, wound healing, Matrigel invasion and western blot assays, respectively. The expression levels of proteins were detected using western blot analysis. The expression levels of NKILA were decreased in CC tissues and CC cell lines (SiHa, C-33A, CaSki and HeLa) and the downregulation of NKILA expression using shRNA was observed to significantly increase the proliferation of CC cells. Conversely, the upregulation of NKILA inhibited the proliferation of CC cells, in addition to significantly inhibiting the migration and invasion of CaSki cells, whereas the knockdown of NKILA promoted the invasion of C-33A cells. Thus, it was hypothesized that NKILA may inhibit the migration and invasion of CC cells via regulation of EMT processes, which was reflected by the expression of ZO-1, E-cadherin, N-cadherin and Vimentin. Furthermore, the overexpression of NKILA significantly inhibited the activation of NF-κB in CaSki cells, whereas the knockdown of NKILA expression promoted the degradation of inhibitory protein-κB and promoted the transfer of p65 into the nucleus in C-33A cells. In conclusion, the results from the present study suggested that NKILA may be involved in the inhibition of migration and invasion in CC cells through regulating EMT processes, which may be related to its inhibition of NF-κB activation.

Recent advances in understanding the role of hypoxia-inducible factor 1α in renal fibrosis

Renal fibrosis is the most common pathological manifestation of chronic kidney disease (CKD), and with numerous influencing factors, its pathogenesis is complex. Epithelial-mesenchymal transition (EMT) is known to promote the progression of renal fibrosis via alterations in the secreted proteome. Moreover, blocking or even reversing EMT can effectively reduce the degree of fibrosis. As such, targeting the key molecules responsible for promoting EMT may be an effective strategy for inhibiting renal fibrosis. Research in recent years has demonstrated that hypoxia-inducible factor 1α (HIF-1α) acts to promote renal fibrosis through regulation of EMT. However, the relationship between HIF-1α and EMT remains incompletely understood. In the present review, the underlying mechanism of the interaction between HIF-1α and EMT is explored to provide novel insight into the pathogenesis of renal fibrosis and new ideas for early targeted intervention.

The roles and mechanism of IFIT5 in bladder cancer epithelial-mesenchymal transition and progression

The prognosis of bladder cancer (BCa) depends on several key factors including anatomical site, tumor grade, and stage. In general, muscle-invasive bladder cancer (MIBC) is associated with higher incidence of distant metastasis compared with Non-muscle-invasive bladder cancer (NMIBC). Treatment outcome of the patients with metastatic BCa has been very poor with ~15% of overall survival rate. Thus, it is apparently important to understand the underlying biology for metastatic progression of BCa. Although epithelial–mesenchymal transition (EMT) has long been implicated in BCa metastasis and treatment resistance, the underlying mechanism is not fully understood. In this study, we have identified that the expression of interferon induced protein with tetratricopeptide repeats 5 (IFIT5) is positively correlated with pathological characteristics, and predicts a poor prognosis of BCa patients. Since the function of IFIT5 in BCa has not yet been characterized, we demonstrate that IFIT5 can induce EMT, promote cell migration and invasion, and increase the expression of ICAM1 in BCa via down-regulation of mature miR-99a. Moreover, ICAM1 is shown as a direct target of miR-99a. Overall, we conclude that IFIT5 is a new oncogene in BCa.

Salidroside Ameliorates Renal Interstitial Fibrosis by Inhibiting the TLR4/NF-κB and MAPK Signaling Pathways

Salidroside (Sal) is an active ingredient that is isolated from Rhodiola rosea, which has been reported to have anti-inflammatory activities and a renal protective effect. However, the role of Sal on renal fibrosis has not yet been elucidated. Here, the purpose of the current study is to test the protective effects of Sal against renal interstitial fibrosis (RIF), and to explore the underlying mechanisms using both in vivo and in vitro models. In this study, we establish the unilateral ureteric obstruction (UUO) or folic acid (FA)-induced mice renal interstitial fibrosis in vivo and the transforming growth factor (TGF)-β1-stimulated human proximal tubular epithelial cell (HK-2) model in vitro. The levels of kidney functional parameters and inflammatory cytokines in serum are examined. The degree of renal damage and fibrosis is determined by histological assessment. Immunohistochemistry and western blotting are used to determine the mechanisms of Sal against RIF. Our results show that treatment with Sal can ameliorate tubular injury and deposition of the extracellular matrix (ECM) components (including collagen Ш and collagen I). Furthermore, Sal administration significantly suppresses epithelial-mesenchymal transition (EMT), as evidenced by a decreased expression of α-SMA, vimentin, TGF-β1, snail, slug, and a largely restored expression of E-cadherin. Additionally, Sal also reduces the levels of serum biochemical markers (serum creatinine, Scr; blood urea nitrogen, BUN; and uric acid, UA) and decreases the release of inflammatory cytokines (IL-1β, IL-6, TNF-α). Further study revealed that the effect of Sal on renal interstitial fibrosis is associated with the lower expression of TLR4, p-IκBα, p-NF-κB and mitogen-activated protein kinases (MAPK), both in vivo and in vitro. In conclusion, Sal treatment improves kidney function, ameliorates the deposition of the ECM components and relieves the protein levels of EMT markers in mouse kidneys and HK-2 cells. Furthermore, Sal treatment significantly decreases the release of inflammatory cytokines and inhibits the TLR4/NF-κB and MAPK signaling pathways. Collectively, these results suggest that the administration of Sal could be a novel therapeutic strategy in treating renal fibrosis.

Osthole Ameliorates Renal Fibrosis in Mice by Suppressing Fibroblast Activation and Epithelial-Mesenchymal Transition

Renal fibrosis is a common pathway of virtually all progressive kidney diseases. Osthole (OST, 7-Methoxy-8-(3-methylbut-2-enyl)-2-chromenone), a derivative of coumarin mainly found in plants of the Apiaceae family, has shown inhibitory effects on inflammation, oxidative stress, fibrosis and tumor progression. The present study investigated whether OST mediates its effect via suppressing fibroblast activation and epithelial-mesenchymal transition (EMT) in unilateral ureteral obstruction (UUO)-induced renal fibrosis in mice. Herein, we found that OST inhibited fibroblast activation in a dose-dependent manner by inhibiting the transforming growth factor-β1 (TGFβ1)-Smad pathway. OST also blocked fibroblast proliferation by reducing DNA synthesis and downregulating the expressions of proliferation- and cell cycle-related proteins including proliferating cell nuclear antigen (PCNA), CyclinD1 and p21 Waf1/Cip1. Meanwhile, in the murine model of renal interstitial fibrosis induced by UUO, myofibroblast activation with increased expression of α-smooth muscle actin (α-SMA) and proliferation were attenuated by OST treatment. Additionally, we provided in vivo evidence suggesting that OST repressed EMT with preserved E-cadherin and reduced Vimentin expression in obstructed kidney. UUO injury-induced upregulation of EMT-related transcription factors, Snail family transcriptional repressor-1(Snail 1) and Twist family basic helix-loop-helix (BHLH) transcription factor (Twist) as well as elevated G2/M arrest of tubular epithelial cell, were rescued by OST treatment. Further, OST treatment reversed aberrant expression of TGFβ1-Smad signaling pathway, increased level of proinflammatory cytokines and NF-kappaB (NF-κB) activation in kidneys with obstructive nephropathy. Taken together, these findings suggest that OST hinder renal fibrosis in UUO mouse mainly through inhibition of fibroblast activation and EMT.

A pathogenetic role for M1 macrophages in peritoneal dialysis-associated fibrosis

Peritoneal fibrosis (PF) is a frequent complication of peritoneal dialysis (PD) accompanied by the infiltration of inflammatory cells. Recently, the function of macrophages in an inflammatory microenvironment during PD remains unknown. This study aimed to elucidate the role of distinct macrophage phenotypes in the progression of PF through macrophage depletion in a peritoneal dialysis-induced mouse model. After injection of 200 μl liposomal clodronate (LC) at the start of instillation PD fluids (PDFs), mice were injected with 100 μL LC every 4 days after the first time injection for longer macrophage depletion, while control mice were co-treated with PBS liposomes. For macrophages transfusion,primary macrophages (M0) were stimulated into M1 and M2 macrophages and transfuritoneal fibrosis (PF) is a frequent complication of peritoneal dialysis (PD) accompanied by the infiltration of inflammatory cells. Recently, the function of macrophages in an inflammatory microenvironment during PD remains unknown. This study aimed to elucidate the role of distinct macrophage phenotypes in the progression of PF through macrophage depletion in a peritoneal dialysis-induced mouse model. After injection of 200 μl liposomal clodronate (LC) at the start of instillation PD fluids (PDFs), mice were injected with 100 μL LC every 4 days after the first time injection for longer macrophage depletion, while control mice were co-treated with PBS liposomes. For macrophages transfusion,primary macrophages (M0) were stimulated into M1 and M2 macrophages and transfused into the mice the next day after each LC injection. Mice were sacrificed after 6 weeks of PDFs treatment for the assessment of histological changes, ECM deposition and peritoneal ultrafiltration function. Systemic monocyte/macrophage depletion resulted in less severe structural alterations, including thickening and cubic transformation of mesothelial cells, fibrin deposition, fibrous capsule formation, and interstitial fibrosis. A strong reduction of alpha-smooth muscle actin (α-SMA) and fibronectin expression, as well as an increased E-cadherin expression was also observed, indicating an overall inhibition of peritoneal fibrosis in macrophages depletion mice.M1 macrophage reperfusion showed a significant increase in histological damages, ECM deposition and peritoneal ultrafiltration functional decline compared with those of the M2 and control groups. TLR4 expression was enhanced in M1 macrophage-treated group. These results suggest that M1 macrophages are an important mediator of peritoneal fibrosis.

Targeting c-fms kinase attenuates chronic aristolochic acid nephropathy in mice

Aristolochic acid nephropathy (AAN) is a progressive kidney disease caused by some Chinese herbal medicines, but treatment remains ineffective. Macrophage accumulation is an early feature in human and experimental AAN; however, the role of macrophages in chronic AAN is unknown. We report here that targeting macrophages with fms-I, a selective inhibitor of the tyrosine kinase activity of the macrophage colony-stimulating factor receptor, suppressed disease progression in a mouse model of chronic AAN. Treatment with fms-I (10mg/kg/BID) from day 0 to 28 (prevention study) or from day 14 to 28 (intervention study) substantially inhibited macrophage accumulation and significantly improved renal dysfunction including a reduction in proteinuria and tubular damage. Progressive interstitial fibrosis (myofibroblast accumulation and collagen deposition) and renal inflammation (increased expression of MCP-1, MIF, and TNF-α) were also attenuated by fms-I treatment. These protective effects involved inhibition of TGF-β/Smad3 and NF-kB signaling. In conclusion, the present study establishes that macrophages are key inflammatory cells that exacerbates progressive tubulointerstitial damage in chronic AAN via mechanisms associated with TGF-β/Smad3-mediated renal fibrosis and NF-κB-driven renal inflammation. Targeting macrophages via a c-fms kinase inhibitor may represent a novel therapy for chronic AAN.

Effect of captopril on radiation-induced TGF-β1 secretion in EA.Hy926 human umbilical vein endothelial cells

The pathophysiological mechanism involved in the sustained endothelial secretion of cytokines that leads to fibrosis 6–16 months after radiotherapy remains unclear. Angiotensin II (Ang II) is produced by the endothelium in response to stressing stimuli, like radiation, and may induce the synthesis of TGF-β, a profibrotic cytokine. In this study we tested the hypothesis that captopril, an angiotensin-converting enzyme (ACE) inhibitor, inhibits or attenuates radiation-induced endothelial TGF-β1 secretion. The human endothelial hybrid cell line EA.HY926 was irradiated with split doses of x-rays (28 Gy delivered in 14 fractions of 2 Gy). TGF-β1 mRNA, TNF-α mRNA and TGF-β1 protein levels were evaluated by RT-PCR and western blotting each month until the fifth month post radiation. Ang II was detected using radioimmunoassays, NF-κB activity was examined using EMSA, and western blotting was used to detect the expression of Iκ-Bα. To explore the role of Ang II on radiation-induced TGF-β1 release and Iκ-Bα expression, captopril was added to cultured cells before, during, or after irradiation. Sustained strong expression of TGF-β1 was observed after conventional fractionated irradiation. TNF-α, Ang II, and NF-κB activity were also increased in EA.Hy926 cells after radiation. Captopril decreased Ang II expression, inhibited the NF-κB pathway and reduced TGF-β1 expression. These data suggest that captopril might protect the endothelium from radiation-induced injury.

Correlation between PKB/Akt, GSK-3β expression and tubular epithelial-mesenchymal transition in renal allografts with chronic active antibody-mediated rejection

Chronic antibody-mediated rejection (ABMR) is a major cause of the transplant renal interstitial fibrosis and transplanted kidney epithelial cell transdifferentiation is one of the main mechanisms. The transforming growth factor (TGF)-β1/integrin-linked kinase (ILK) signaling pathway has a significant role in the epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells; however, the molecular mechanisms of this process have remained elusive. The present study confirmed that Akt and glycogen synthase kinase (GSK)-3β, as TGF-β1 downstream signaling factors, are involved in fibrotic processes caused by kidney disease, which, however, has been rarely reported in the kidney transplant field. Based on the Banff 2009 standard, transplanted kidney specimens were classified according to the fibrosis level. The results showed that with the reduction of the interstitial fibrosis level, E-cadherin expression was gradually reduced, while α-smooth muscle actin expression progressively increased. The expression of Akt and GSK-3β in normal human kidney tissue was not obvious but showed a marked increase with the aggravation of the interstitial fibrosis level, which confirmed the occurrence of EMT during the fibrosis process, and that phosphorylated (p)-Akt and GSK-3β have an important role in the EMT process in the transplanted kidney. A correlation analysis of p-Akt, GSK-3β, TGF-β1 and ILK suggested that overexpression of p-Akt and GSK-3β may induce and mediate the transdifferentiation of renal tubular epithelial cells to myofibroblasts and that this proceeds via TGFβ1/ILK signaling pathways.

Cardiac troponin I exacerbates myocardial ischaemia/reperfusion injury by inducing the adhesion of monocytes to vascular endothelial cells via a TLR4/NF-κB-dependent pathway

Cardiac troponin I (cTnI), a biomarker for myocardial damage and risk stratification, may be involved in the pathogenesis of cardiovascular diseases, which was ascribed to the effect of cTnI auto-antibodies. Whether or not cTnI itself has a direct impact on acute myocardial injury is unknown. To exclude the influence of cTnI antibody on the cardiac infarct size, we studied the effect of cTnI shortly after myocardial ischaemia-reperfusion (I/R) injury when cTnI antibodies were not elevated. Pretreatment with cTnI augmented the myocardial infarct size caused by I/R, accompanied by an increase in inflammatory markers in the blood and myocardium. Additional experiments using human umbilical vein endothelial cells (HUVECs) showed that the detrimental effect of cTnI was related to cTnI-induced increase in vascular cell adhesion molecule-1 (VCAM-1) expression and VCAM-1 mediated adhesion of human monocytes (THP-1) to HUVECs, which could be neutralized by VCAM-1 antibody. Both toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) were involved in the signalling pathway, because blockade of either TLR4 or NF-κB inhibited the cTnI's effect on VCAM-1 expression and adhesion of monocytes to endothelial cells. Moreover, TLR4 inhibition reduced cTnI-augmented cardiac injury in rats with I/R injury. We conclude that cTnI exacerbates myocardial I/R injury by inducing the adhesion of monocytes to vascular endothelial cells via activation of the TLR4/NF-κB pathway. Inhibition of TLR4 may be an alternative strategy to reduce cTnI-induced myocardial I/R injury.

Exploring the role of sphingolipid machinery during the epithelial to mesenchymal transition program using an integrative approach

The epithelial to mesenchymal transition (EMT) program is activated in epithelial cancer cells and facilitates their ability to metastasize based on enhanced migratory, proliferative, anti-apoptotic, and pluripotent capacities. Given the fundamental impact of sphingolipid machinery to each individual process, the sphingolipid-related mechanisms might be considered among the most prominent drivers/players of EMT; yet, there is still limited knowledge. Given the complexity of the interconnected sphingolipid system, which includes distinct sphingolipid mediators, their synthesizing enzymes, receptors and transporters, we herein apply an integrative approach for assessment of the sphingolipid-associated mechanisms underlying EMT program. We created the sphingolipid-/EMT-relevant 41-gene/23-gene signatures which were applied to denote transcriptional events in a lung cancer cell-based EMT model. Based on defined 35-gene sphingolipid/EMT-attributed signature of regulated genes, we show close associations between EMT markers, genes comprising the sphingolipid network at multiple levels and encoding sphingosine 1-phosphate (S1P)-/ceramide-metabolizing enzymes, S1P and lysophosphatidic acid (LPA) receptors and S1P transporters, pluripotency genes and inflammation-related molecules, and demonstrate the underlying biological pathways and regulators. Mass spectrometry-based sphingolipid analysis revealed an EMT-attributed shift towards increased S1P and LPA accompanied by reduced ceramide levels. Notably, using transcriptomics data across various cell-based perturbations and neoplastic tissues (24193 arrays), we identified the sphingolipid/EMT signature primarily in lung adenocarcinoma tissues; besides, bladder, colorectal and prostate cancers were among the top-ranked. The findings also highlight novel regulatory associations between influenza virus and the sphingolipid/EMT-associated mechanisms. In sum, data propose the multidimensional contribution of sphingolipid machinery to pathological EMT and may yield new biomarkers and therapeutic targets.

In vivo sodium tungstate treatment prevents E-cadherin loss induced by diabetic serum in HK-2 cell line

Diabetic nephropathy (DN) is characterized by interstitial inflammation and fibrosis, which is the result of chronic accumulation of extracellular matrix produced by activated fibroblasts in the renal tubulointerstitium. Renal proximal tubular epithelial cells (PTECs), through the process of epithelial-to-mesenchymal transition (EMT), are the source of fibroblasts within the interstitial space, and loss of E-cadherin has shown to be one of the earliest steps in this event. Here, we studied the effect of the anti-diabetic agent sodium tungstate (NaW) in the loss of E-cadherin induced by transforming growth factor (TGF) β-1, the best-characterized in vitro EMT promoter, and serum from untreated or NaW-treated diabetic rats in HK-2 cell line, a model of human kidney PTEC. Our results showed that both TGFβ-1 and serum from diabetic rat induced a similar reduction in E-cadherin expression. However, E-cadherin loss induced by TGFβ-1 was not reversed by NaW, whereas sera from NaW-treated rats were able to protect HK-2 cells. Searching for soluble mediators of NaW effect, we compared secretion of TGFβ isoforms and vascular endothelial growth factor (VEGF)-A, which have opposite actions on EMT. One millimolar NaW alone reduced secretion of both TGFβ-1 and -2, and stimulated secretion of VEGF-A after 48 h. However, these patterns of secretion were not observed after diabetic rat serum treatment, suggesting that protection from E-cadherin loss by serum from NaW-treated diabetic rats originates from an indirect rather than a direct effect of this salt on HK-2 cells, via a mechanism independent of TGFβ and VEGF-A functions.

Causes of genome instability: the effect of low dose chemical exposures in modern society

Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus, genome instability can be defined as an enhanced tendency for the genome to acquire mutations; ranging from changes to the nucleotide sequence to chromosomal gain, rearrangements or loss. This review raises the hypothesis that in addition to known human carcinogens, exposure to low dose of other chemicals present in our modern society could contribute to carcinogenesis by indirectly affecting genome stability. The selected chemicals with their mechanisms of action proposed to indirectly contribute to genome instability are: heavy metals (DNA repair, epigenetic modification, DNA damage signaling, telomere length), acrylamide (DNA repair, chromosome segregation), bisphenol A (epigenetic modification, DNA damage signaling, mitochondrial function, chromosome segregation), benomyl (chromosome segregation), quinones (epigenetic modification) and nano-sized particles (epigenetic pathways, mitochondrial function, chromosome segregation, telomere length). The purpose of this review is to describe the crucial aspects of genome instability, to outline the ways in which environmental chemicals can affect this cancer hallmark and to identify candidate chemicals for further study. The overall aim is to make scientists aware of the increasing need to unravel the underlying mechanisms via which chemicals at low doses can induce genome instability and thus promote carcinogenesis.

TNF-related weak inducer of apoptosis (TWEAK) regulates junctional proteins in tubular epithelial cells via canonical NF-κB pathway and ERK activation

The tubular epithelium may be intrinsically involved in promoting kidney injury by junctional instability, epithelial-mesenchymal transition (EMT) and extracellular matrix remodelling. In this work, we investigated whether the pleiotropic and proinflammatory cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK), could be able to disturb junctional protein expression and to induce EMT of tubular cells. In cultured murine proximal tubular cells TWEAK induced phenotypic changes that were accompanied by F-actin redistribution, loss of epithelial adherent (E-cadherin, Cadherin-16, β-catenin) and tight junction (ZO-1) proteins, and re-expression of the mesenchymal protein Vimentin. The transcriptional repressors Snail and HNF1β were also modulated by TWEAK. In a murine model of obstructive renal pathology, TWEAK expression correlated with the appearance of the mesenchymal marker αSMA in kidney tubular cells. Mechanistically, the epithelial changes induced by TWEAK, including loss of epithelial integrity and EMT, via Fn14 were TGF-β1 independent, but mediated by several intracellular signaling systems, including the canonical NF-κB, ERK activation and the vitamin D receptor modulation. These results highlight potential contributions of TWEAK-induced inflammatory mechanisms that could unveil new pathogenic effects of TWEAK starting tubulointerstitial damage and fibrosis.

Soluble factors regulated by epithelial-mesenchymal transition mediate tumour angiogenesis and myeloid cell recruitment

Epithelial-mesenchymal transition (EMT) programmes provide cancer cells with invasive and survival capacities that might favour metastatic dissemination. Whilst signalling cascades triggering EMT have been extensively studied, the impact of EMT on the crosstalk between tumour cells and the tumour microenvironment remains elusive. We aimed to identify EMT-regulated soluble factors that facilitate the recruitment of host cells in the tumour. Our findings indicate that EMT phenotypes relate to the induction of a panel of secreted mediators, namely IL-8, IL-6, sICAM-1, PAI-1 and GM-CSF, and implicate the EMT-transcription factor Snail as a regulator of this process. We further show that EMT-derived soluble factors are pro-angiogenic in vivo (in the mouse ear sponge assay), ex vivo (in the rat aortic ring assay) and in vitro (in a chemotaxis assay). Additionally, conditioned medium from EMT-positive cells stimulates the recruitment of myeloid cells. In a bank of 40 triple-negative breast cancers, tumours presenting features of EMT were significantly more angiogenic and infiltrated by a higher quantity of myeloid cells compared to tumours with little or no EMT. Taken together, our results show that EMT programmes trigger the expression of soluble mediators in cancer cells that stimulate angiogenesis and recruit myeloid cells in vivo, which might in turn favour cancer spread.

CD44(+)/CD24(-) breast cancer cells exhibit phenotypic reversion in three-dimensional self-assembling peptide RADA16 nanofiber scaffold

Background

Self-assembling peptide nanofiber scaffolds have been shown to be a permissive biological material for tissue repair, cell proliferation, differentiation, etc. Recently, a subpopulation (CD44⁺/CD24⁻) of breast cancer cells has been reported to have stem/progenitor cell properties. The aim of this study was to investigate whether this subpopulation of cancer cells have different phenotypes in self-assembling COCH₃-RADARADARADARADA-CONH₂ (RADA16) peptide nanofiber scaffold compared with Matrigel^® (BD Biosciences, Two Oak Park, Bedford, MA, USA) and collagen I.

Methods

CD44 and CD24 expression was determined by flow cytometry. Cell proliferation was measured by 5-bromo-2′-deoxyuridine assay and DNA content measurement. Immunostaining was used to indicate the morphologies of cells in three-dimensional (3D) cultures of different scaffolds and the localization of β-catenin in the colonies. Western blot was used to determine the expression of signaling proteins. In vitro migration assay and inoculation into nude mice were used to evaluate invasion and tumorigenesis in vivo.

Results

The breast cancer cell line MDA-MB-435S contained a high percentage (>99%) of CD44⁺/CD24⁻ cells, which exhibited phenotypic reversion in 3D RADA16 nanofiber scaffold compared with collagen I and Matrigel. The newly formed reverted acini-like colonies reassembled a basement membrane and reorganized their cytoskeletons. At the same time, cells cultured and embedded in RADA16 peptide scaffold exhibited growth arrest. Also, they exhibited different migration potential, which links their migration ability with their cellular morphology. Consistent with studies in vitro, the in vivo tumor formation assay further supported of the functional changes caused by the reversion in 3D RADA16 culture. Expression levels of intercellular surface adhesion molecule-1 were upregulated in cells cultured in RADA16 scaffolds, and the NF-kappa B inhibitor pyrrolidine dithiocarbamate could inhibit RADA16-induced upregulation of intercellular surface adhesion molecule-1 and the phenotype reversion of MDA-MB-453S cells.

Conclusion

Culturing a CD44⁺/CD24⁻-enriched breast cancer cell population in 3D RADA16 peptide nanofiber scaffold led to a significant phenotypic reversion compared with Matrigel and collagen I.

Cadherin expression, vectorial active transport, and metallothionein isoform 3 mediated EMT/MET responses in cultured primary and immortalized human proximal tubule cells

BACKGROUND

Cultures of human proximal tubule cells have been widely utilized to study the role of EMT in renal disease. The goal of this study was to define the role of growth media composition on classic EMT responses, define the expression of E- and N-cadherin, and define the functional epitope of MT-3 that mediates MET in HK-2 cells.

METHODS

Immunohistochemistry, microdissection, real-time PCR, western blotting, and ELISA were used to define the expression of E- and N-cadherin mRNA and protein in HK-2 and HPT cell cultures. Site-directed mutagenesis, stable transfection, measurement of transepithelial resistance and dome formation were used to define the unique amino acid sequence of MT-3 associated with MET in HK-2 cells.

RESULTS

It was shown that both E- and N-cadherin mRNA and protein are expressed in the human renal proximal tubule. It was shown, based on the pattern of cadherin expression, connexin expression, vectorial active transport, and transepithelial resistance, that the HK-2 cell line has already undergone many of the early features associated with EMT. It was shown that the unique, six amino acid, C-terminal sequence of MT-3 is required for MT-3 to induce MET in HK-2 cells.

CONCLUSIONS

The results show that the HK-2 cell line can be an effective model to study later stages in the conversion of the renal epithelial cell to a mesenchymal cell. The HK-2 cell line, transfected with MT-3, may be an effective model to study the process of MET. The study implicates the unique C-terminal sequence of MT-3 in the conversion of HK-2 cells to display an enhanced epithelial phenotype.

Cancer cells remodel themselves and vasculature to overcome the endothelial barrier

Metastasis refers to the spread of cancer cells from a primary tumor to distant organs mostly via the bloodstream. During the metastatic process, cancer cells invade blood vessels to enter circulation, and later exit the vasculature at a distant site. Endothelial cells that line blood vessels normally serve as a barrier to the movement of cells into or out of the blood. It is thus critical to understand how metastatic cancer cells overcome the endothelial barrier. Epithelial cancer cells acquire increased motility and invasiveness through epithelial-to-mesenchymal transition (EMT), which enables them to move toward vasculature. Cancer cells also express a variety of adhesion molecules that allow them to attach to vascular endothelium. Finally, cancer cells secrete or induce growth factors and cytokines to actively prompt vascular hyperpermeability that compromises endothelial barrier function and facilitates transmigration of cancer cells through the vascular wall. Elucidation of the mechanisms underlying metastatic dissemination may help develop new anti-metastasis therapeutics.

Basement membrane zone collagens XV and XVIII/proteoglycans mediate leukocyte influx in renal ischemia/reperfusion

Collagen type XV and XVIII are proteoglycans found in the basement membrane zones of endothelial and epithelial cells, and known for their cryptic anti-angiogenic domains named restin and endostatin, respectively. Mutations or deletions of these collagens are associated with eye, muscle and microvessel phenotypes. We now describe a novel role for these collagens, namely a supportive role in leukocyte recruitment. We subjected mice deficient in collagen XV or collagen XVIII, and their compound mutant, as well as the wild-type control mice to bilateral renal ischemia/reperfusion, and evaluated renal function, tubular injury, and neutrophil and macrophage influx at different time points after ischemia/reperfusion. Five days after ischemia/reperfusion, the collagen XV, collagen XVIII and the compound mutant mice showed diminished serum urea levels compared to wild-type mice (all p<0.05). Histology showed reduced tubular damage, and decreased inflammatory cell influx in all mutant mice, which were more pronounced in the compound mutant despite increased expression of MCP-1 and TNF-α in double mutant mice compared to wildtype mice. Both type XV and type XVIII collagen bear glycosaminoglycan side chains and an in vitro approach with recombinant collagen XVIII fragments with variable glycanation indicated a role for these side chains in leukocyte migration. Thus, basement membrane zone collagen/proteoglycan hybrids facilitate leukocyte influx and tubular damage after renal ischemia/reperfusion and might be potential intervention targets for the reduction of inflammation in this condition.

Role of NF-κB in induction of epithelial-mesenchymal transition, migration and invasion of human colon cancer cells

AIM: To investigate the role of nuclear factor-kappa B (NF-κB) in the induction of epithelial-mesenchymal transition (EMT), migration and invasion of human colon cancer cell line HCT116.

METHODS: HCT116 cells were divided into three groups and treated with 20 ng/mL of tumor necrosis factor-α (TNF-α) (NF-κB activation group), 20 μmol/L of ammonium pyrrolidinedithiocarbamate (PDTC) (NF-κB suppression group), and equal volume of culture medium (control group), respectively. Four days later, cell morphological changes associated with EMT were observed under a phase contrast microscope, and the migration ability and invasiveness were assessed by Transwell chamber assays. The protein expression of p65, P-p65, E-cadherin and N-cadherin was analyzed by Western blot, and the mRNA expression of E-cadherin and N-cadherin was detected by quantitative real-time PCR.

RESULTS: TNF-α up-regulated the expression of P-p65 and N-cadherin, suppressed the expression of E-cadherin, and caused a complete EMT-phenotype, which manifested as the formation of large filopodia-like processes and spindle-cell shape. Also, TNF-α promoted cell invasion and migration. In contrast, PDTC down-regulated the expression of P-p65 and N-cadherin, up-regulated the expression of E-cadherin, inhibited the occurrence of typical EMT phenomenon, and suppressed cell invasion and migration. Compared with the control group, TNF-α group and PDTC group showed significantly different cell invasion (97.75 ± 3.77 vs 118.50 ± 1.95, 51.00 ± 1.83, P < 0.05 for both), cell migration (140.00 ± 4.32 vs 167.00 ± 6.36, 80.00 ± 2.53, P < 0.05 for both), and mRNA expression of N-cadherin (1.00 ± 0.00 vs 3.90 ± 0.47, 0.08 ± 0.02, P < 0.05 for both) and E-cadherin (1.00 ± 0.00 vs 0.26 ± 0.08, 6.03 ± 0.59, P < 0.05 for both).

CONCLUSION: NF-κB induces the occurrence of typical EMT phenomenon and promotes cell invasion and migration in human colon cancer cell line HCT116.

Monocyte interaction accelerates HCl-induced lung epithelial remodeling

Background

Acute respiratory distress syndrome (ARDS) is characterized by overwhelming inflammatory responses and lung remodeling. We hypothesized that leukocyte infiltration during the inflammatory response modulates epithelial remodeling through a mechanism of epithelial-mesenchymal transition (EMT).

Methods

Human lung epithelial cells were treated for 30 min with hydrochloric acid (HCl). Human monocytes were then cocultured with the epithelial cells for up to 48 h, in the presence or absence of blocking peptides against lymphocyte function-associated antigen-1 (LFA-1), or tyrphostin A9, a specific inhibitor for platelet-derived growth factor (PDGF) receptor tyrosine kinase.

Results

Exposure of lung epithelial cells to HCl resulted in increased expression of intercellular adhesion molecule-1 (ICAM-1) and production of interleukin (IL)-8 at 24 h. The expression of the epithelial markers E-cadherin decreased while the mesenchymal markers vimentin and α-smooth muscle actin (α-SMA) increased at 24 h and remained high at 48 h. The addition of monocytes augmented the profiles of lower expression of epithelial markers and higher mesenchymal markers accompanied by increased collagen deposition. This EMT profile was associated with an enhanced production of IL-8 and PDGF. Treatment of the lung epithelial cells with the LAF-1 blocking peptides CD11a_237–246 or/and CD18_112–122 suppressed monocyte adhesion, production of IL-8, PDGF and hydroxyproline as well as EMT markers. Treatment with tyrphostin A9 prevented the EMT profile shift induced by HCl stimulation.

Conclusions

The interaction between epithelial cells and monocytes enhanced epithelial remodelling after initial injury through EMT signalling that is associated with the release of soluble mediators, including IL-8 and PDGF.

Total glucosides of paeony attenuate renal tubulointerstitial injury in STZ-induced diabetic rats: role of Toll-like receptor 2

Accumulating evidence suggested that macrophages induce tubulointerstitial injury. Total glucosides of paeony (TGP), extracted from Paeonia lactiflora, has presented anti-inflammatory activities in diabetic kidney disease. This research will investigate the protective effect of TGP on renal tubulointerstitium and its mechanism in streptozotocin-induced diabetic rats. TGP was administered orally at a dose of 50, 100, and 200 mg·kg(-1)·d(-1) for 8 weeks. Tubulointerstitial injury was quantified, followed by immunohistochemistry analysis of renal α-smooth muscle actin (α-SMA), E-cadherin (E-cad) expression, nuclear factor kappa B (NF-κB)-p-p-65(+), Toll-like receptor (TLR)2(+), and ED-1(+) cell infiltration in renal tubulointerstitium. Renal TLR2(+) macrophages were detected by double immunohistochemical staining. Western blotting was used to detect the TLR2 expression. Histologically, there was marked accumulation of TLR2(+), NF-κB-p-p-65(+), ED-1(+) cells, and ED-1(+)TLR2(+) cells (macrophages) in the diabetic kidney and TGP treatment could alleviate it. Accompanying with that, the tubulointerstitial injury was ameliorated, α-SMA expression was lower, and E-cad expression was higher compared with the diabetic rats. Western blot analysis showed that the expression of TLR2 protein was significantly increased in the kidney of the diabetic rats, whereas TGP treatment reduced it. Our study showed that TGP could prevent renal tubulointerstitium injury in diabetic rats through a mechanism that may be at least partly correlated with suppression of increased macrophage infiltration and the expression of TLR2.

Tumor-associated macrophages exhibit pro- and anti-inflammatory properties by which they impact on pancreatic tumorigenesis

Pancreatic ductal adenocarcinoma (PDAC) still ranking 4th in the order of fatal tumor diseases is characterized by a profound tumor stroma with high numbers of tumor-associated macrophages (TAMs). Driven by environmental factors, monocytes differentiate into M1- or M2-macrophages, the latter commonly regarded as being protumorigenic. Because a detailed analysis of TAMs in human PDAC development is still lacking, freshly isolated PDAC-derived TAMs were analyzed for their phenotype and impact on epithelial-mesenchymal-transition (EMT) of benign (H6c7) and malignant (Colo357) pancreatic ductal epithelial cells. TAMs exhibited characteristics of M1-macrophages (expression of HLA-DR, IL-1β, or TNF-α) and M2-macrophages (expression of CD163 and IL-10). In the presence of TAMs, H6c7, and Colo357 cells showed an elongated cell shape along with an increased expression of mesenchymal markers such as vimentin and reduced expression of epithelial E-cadherin. Similar to TAMs, in vitro generated M1- and M2-macrophages both mediated EMT in H6c7 and Colo357 cells. M1-macrophages acquired M2-characteristics during coculture that could be prevented by GM-CSF treatment. However, M1-macrophages still potently induced EMT in H6c7 and Colo357 cells although lacking M2-characteristics. Overall, these data demonstrate that TAMs exhibit anti- as well as proinflammatory properties that equally contribute to EMT induction in PDAC initiation and development.

Constitutional Nephrin Deficiency in Conditionally Immortalized Human Podocytes Induced Epithelial-Mesenchymal Transition, Supported by β-Catenin/NF-kappa B Activation: A Consequence of Cell Junction Impairment?

The kidney glomerular podocytes are the cellular target of many chronic nephropathies both determined and acquired genetically. Mutations that affected the expression and/or the function of nephrin, a key component of the slit-diaphragm, are often causes of these pathologies. Recent findings showed that murine podocytes could undergo epithelial-mesenchymal transformation (EMT), suggesting new hypotheses about the pathogenesis of glomerular fibrosis. Here, we show that also human podocytes can undergo EMT, but more importantly nephrin ablation itself can trigger this phenotypic transformation. In fact, a model of human podocyte with engineered nephrin deficiency constitutionally expressed high levels of α-SMA, vimentin, fibronectin, and other hallmarks of EMT. Since it is known that cell contact abrogation is one of the triggers of EMT, we reasoned that nephrin loss could account for such cell junction disruption and cause the EMT. Therefore, we demonstrated that also normal podocytes could spontaneously undergo EMT if grown in Ca²⁺-free medium, which is known to impair cell contacts. The analysis of the main intracellular signal transduction pathways evidenced some major anomalies consequent with the nephrin abrogation. The most intriguing was the activation of β-catenin pathway, which plays a critical role in podocyte ontogenesis as well as in the nephrin expression and EMT regulation. Also other important signaling proteins, like NF-κB, p53, and retinoblastoma protein (RB), showed important activity modifications. Interestingly, most of the above indicated signaling pathway alterations were again reproducible by cell junction rupture, induced by Ca²⁺ deprivation. Finally, immunofluorescence analysis on kidney sections of patients with NS of Finnish type confirmed the constitutive expression of α-SMA.

Dexamethasone prevents monocyte-induced tubular epithelial-mesenchymal transition in HK-2 cells

Epithelial-mesenchymal transition (EMT) is a key cellular event in the early stage of tubulointerstitial fibrosis (TIF). Monocyte infiltration plays an important role in the progression of TIF. We have previously demonstrated that monocytes can directly induce HK-2 cell transition by direct contact. Dexamethasone, an important anti-inflammatory and immunosuppressant agent, has been widely used in renal disease for decades. Whether it could influence the monocyte and HK-2 cell interaction and prevent EMT is still uncertain. In this study, we found that the typical epithelial cell morphology of HK-2 cells disappeared 24 h after co-culture with monocytes, and dexamethasone significantly prevented this change in a dose-dependent manner. In addition, we found that dexamethasone prevented monocytes from binding to HK-2 cells by inhibiting ICAM-1 expression on HK-2 cells. Further analysis demonstrated that there was increased E-cadherin expression and decreased α-SMA and fibronectin expression after co-culture with dexamethasone, suggesting that dexamethasone prevents monocyte-induced HK-2 cell transition. The nuclear transcription factor κB (NF-κB) pathway played an important role in this process. These findings suggest a novel mechanism by which corticosteroids may delay the progression of TIF via preventing EMT.

Eosinophils promote epithelial to mesenchymal transition of bronchial epithelial cells

Eosinophilic inflammation and remodeling of the airways including subepithelial fibrosis and myofibroblast hyperplasia are characteristic pathological findings of bronchial asthma. Epithelial to mesenchymal transition (EMT) plays a critical role in airway remodelling. In this study, we hypothesized that infiltrating eosinophils promote airway remodelling in bronchial asthma. To demonstrate this hypothesis we evaluated the effect of eosinophils on EMT by in vitro and in vivo studies. EMT was assessed in mice that received intra-tracheal instillation of mouse bone marrow derived eosinophils and in human bronchial epithelial cells co-cultured with eosinophils freshly purified from healthy individuals or with eosinophilic leukemia cell lines. Intra-tracheal instillation of eosinophils was associated with enhanced bronchial inflammation and fibrosis and increased lung concentration of growth factors. Mice instilled with eosinophils pre-treated with transforming growth factor(TGF)-β1 siRNA had decreased bronchial wall fibrosis compared to controls. EMT was induced in bronchial epithelial cells co-cultured with human eosinophils and it was associated with increased expression of TGF-β1 and Smad3 phosphorylation in the bronchial epithelial cells. Treatment with anti-TGF-β1 antibody blocked EMT in bronchial epithelial cells. Eosinophils induced EMT in bronchial epithelial cells, suggesting their contribution to the pathogenesis of airway remodelling.

NF-κB activation mediates crystal translocation and interstitial inflammation in adenine overload nephropathy

Adenine overload promotes intratubular crystal precipitation and interstitial nephritis. We showed recently that these abnormalities are strongly attenuated in mice knockout for Toll-like receptors-2, -4, MyD88, ASC, or caspase-1. We now investigated whether NF-κB activation also plays a pathogenic role in this model. Adult male Munich-Wistar rats were distributed among three groups: C (n = 17), receiving standard chow; ADE (n = 17), given adenine in the chow at 0.7% for 1 wk and 0.5% for 2 wk; and ADE + pyrrolidine dithiocarbamate (PDTC; n = 14), receiving adenine as above and the NF-κB inhibitor PDTC (120 mg·kg⁻¹·day⁻¹ in the drinking water). After 3 wk, widespread crystal deposition was seen in tubular lumina and in the renal interstitium, along with granuloma formation, collagen accumulation, intense tubulointerstitial proliferation, and increased interstitial expression of inflammatory mediators. Part of the crystals were segregated from tubular lumina by a newly formed cell layer and, at more advanced stages, appeared to be extruded to the interstitium. p65 nuclear translocation and IKK-α increased abundance indicated activation of the NF-κB system. PDTC treatment prevented p65 migration and normalized IKK-α, limited crystal shift to the interstitium, and strongly attenuated interstitial fibrosis/inflammation. These findings indicate that the complex inflammatory phenomena associated with this model depend, at least in part, on NF-κB activation, and suggest that the NF-κB system may become a therapeutic target in the treatment of chronic kidney disease.

Activation of renin-angiotensin system is involved in dyslipidemia-mediated renal injuries in apolipoprotein E knockout mice and HK-2 cells

Background

Dyslipidemia and activation of renin-angiotensin system (RAS) contribute to the progression of chronic kidney disease (CKD). This study investigated possible synergistic effects of intrarenal RAS activation with hyperlipidemia in renal injuries.

Methods

Apolipoprotein knockout mice were fed with normal chow diet (control) or high fat diet (HF group) for eight weeks. Human proximal tubular epithelial cell line (HK-2) was treated without (control) or with cholesterol (30 μg/ml) plus 25-hydroxycholesterol (1 μg/ml) (lipid group) for 24 hours. The plasma lipid profile and RAS components were determined by clinical biochemistry assay and radiommunoassay, respectively. Collagen deposition in kidneys was evaluated by Masson-staining. The gene and protein expressions of molecules involved in RAS components and biomarkers of epithelial mesenchymal transition (EMT) were examined by real-time PCR, immunochemical staining, and Western blot.

Results

The mice fed with high-fat diet showed significant hyperlipidemia with collagen deposition in renal tubular interstitium compared to controls. The plasma levels of renin, angiotensin I, and angiotensin II were no difference in two groups. However, the kidneys of HF group showed up-regulated RAS components, which were positively associated with increased plasma levels of triglyceride, total cholesterol, and LDL. These effects were further confirmed by in vitro studies. Lipid loading induced HK-2 cells underwent EMT, which was closely associated with the increased expressions of intracellular RAS components.

Conclusions

Local RAS activation was involved in hyperlipidemia-mediated renal injuries, suggesting that there are synergistic effects resulting from RAS activation with hyperlipidemia that accelerates the progression of CKD.

Role of EMT in gastrointestinal tract tumors

Epithelial-mesenchymal transition (EMT) refers to the process by which cells transit from epithelial phenotype to mesenchymal phenotype. EMT is important for embryonic development, wound healing, and invasion of carcinomas. The molecular mechanisms of EMT are a hot topic of research in invasion and migration of malignant tumors, especially digestive carcinomas. Since malignant epithelial tumors account for a large proportion of tumors and are associated with very poor outcome and prognosis, exploration of the process of epithelial cell migration and invasion is of great significance for the prevention and treatment of tumors. The investigation of EMT provides a basis for understanding the pathogenesis of tumors and their prognosis and resistance to antitumor drugs. This review focuses on the molecular mechanisms and role of EMT in gastrointestinal tract tumors.

Pirfenidone inhibits macrophage infiltration in 5/6 nephrectomized rats

Tubulointerstitial macrophage infiltration is a hallmark of chronic kidney disease involved in the progression of renal fibrosis. Pirfenidone is a newly identified antifibrotic drug, the potential mechanism of which remains unclear. The aim of this study was to investigate the effects of pirfenidone on M1/M2 macrophage infiltration in nephrectomized rats. Nephrectomized rats were treated with pirfenidone by gavage for 12 wk. Twenty-four hour urinary protein, N-acetyl-β-D-glycosaminidase (NAG) activity, systolic blood pressure, and C-reactive protein were determined. Paraffin-embedded sections were stained for CD68, CCR7, and CD163 macrophages. Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α), as well as M1 and M2 macrophages secretory markers, were evaluated by real-time RT-PCR and Western blotting analysis. Pirfenidone significantly improved the elevated proteinuria and NAG activity from week 2 onward after surgery. Pirfenidone attenuated interstitial fibrosis and decreased expression of fibrotic markers including transforming growth factor-β(1), connective tissue growth factor, α-smooth muscle actin, fibronectin, and fibroblast-specific protein-1. Pirfenidone significantly decreased the infiltrating macrophages. The number of M1 and M2 macrophages was significantly lower after pirfenidone treatment. MCP-1 and MIP-1α were increased in nephrectomized rats at mRNA and protein levels. Pirfenidone treatment significantly inhibited their expression. The TNF-α, IL-6, and nitric oxide synthases-2 expressed by M1 macrophages were increased in nephrectomized rats, and pirfenidone significantly attenuated their expression. Pirfenidone treatment also significantly decreased arginase-1, dectin-1, CD206, and CD86 expressed by M2 macrophages. Thus pirfenidone inhibits M1 and M2 macrophage infiltration in 5/6 nephrectomized rats, which suggests its efficacy in the early and late periods of renal fibrosis.

Moscatilin inhibits migration and metastasis of human breast cancer MDA-MB-231 cells through inhibition of Akt and Twist signaling pathway

Breast cancer metastasis is more resistant to chemotherapy and radiotherapy than is cancer of the visceral tissues; therefore, new treatment strategies are urgently needed. Moscatilin, derived from the orchid Dendrobrium loddigesii, has shown anticancer activity. We evaluated the mechanism by which moscatilin suppresses the migration and metastasis of human breast cancer MDA-MB-231 cells in vitro and in vivo. We demonstrated that moscatilin significantly inhibits MDA-MB-231 cell migration by using scratch assays and Boyden chambers. Transcriptional factors inducing epithelial-mesenchymal transition, such as Twist, Snail, and Akt, play important roles in cell migration and cancer metastasis. Moscatilin inhibited the mRNA and protein expression of Twist, but not that of Snail, and subsequently inhibited N-cadherin expression. However, these effects were reversed by constitutively expressing active myristoylated (myr)-Akt and Twist overexpression. Moscatilin also suppressed Akt phosphorylation. However, Akt overexpression reversed the inhibitory effects of moscatilin on phospho-Akt protein expression but not its effects on Twist. The moscatilin-mediated inhibition of cell migration was reversed by Akt and Twist overexpression, demonstrating that moscatilin blocked cell migration by inhibiting Akt and Twist. In an MDA-MB-231 metastatic animal model, moscatilin (100 mg/kg) significantly suppressed breast cancer metastasis to the lungs and reduced the number of metastatic lung nodules and lung weight without causing any toxicity. These results indicated that moscatilin inhibited MDA-MB-231 cell migration via Akt- and Twist-dependent pathways; this finding was consistent with moscatilin's antimetastatic activity in vivo. Therefore, moscatilin may be an effective compound for the prevention of human breast cancer metastasis.

Urinary mRNA markers of epithelial-mesenchymal transition correlate with progression of diabetic nephropathy

OBJECTIVE

Epithelial-mesenchymal transition (EMT) plays an important role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA (mRNA) expression in urinary sediment is emerging as a noninvasive method of screening DN-associated biomarkers. The aim of our study was to examine whether urinary mRNA profile of EMT-associated genes may provide valuable clinical insight into the different stages of DN.

DESIGN AND METHODS

Diabetic nephropathy patients (n = 44) and healthy controls (n = 12) were enrolled in this study. DN patients were divided into three groups according to the levels of estimated glomerular filtration rate (eGFR): Group A (eGFR > 60 ml/min per 1·73 m(2), n = 27), Group B (45 < eGFR < 60 ml/min per 1·73 m(2), n = 9), and Group C (eGFR < 45 ml/min per 1·73 m(2), n = 8). Relative mRNA abundance of α-smooth muscle actin (α-SMA), fibronectin, FSP1 and matrix metalloproteinase-9 (MMP-9) were quantified, and correlations between target mRNAs and clinical parameters were examined.

RESULTS

The urinary mRNA levels of α-SMA, fibronectin and MMP-9 were significantly higher in the DN group compared with controls (P < 0·05), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both urinary albumin excretion (UAE) and blood urea nitrogen (BUN). Moreover, the expression of α-SMA, fibronectin and MMP-9 mRNA correlated with serum creatinine levels (r = 0·514, r = 0·53 and r = 0·469, all P < 0·001) and GFR levels (r = -0·374, r = -0·392 and r = -0·487, all P < 0·01).

CONCLUSIONS

Quantification of EMT-associated genes in urinary sediment may be a novel approach for searching new biomarkers of DN.

Monocytes conditioned media stimulate fibronectin expression and spreading of inflammatory breast cancer cells in three-dimensional culture: A mechanism mediated by IL-8 signaling pathway

Background

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer characterized by invasion of carcinoma cells into dermal lymphatic vessels where they form tumor emboli over expressing adhesion molecule E-cadherin. Although invasion and metastasis are dynamic processes controlled by complex interaction between tumor cells and microenvironment the mechanisms by which soluble mediators may regulate motility and invasion of IBC cells are poorly understood. The present study investigated the effect of media conditioned by human monocytes U937 secreted cytokines, chemokines and growth factors on the expression of adhesion molecules E-cadherin and fibronectin of human IBC cell line SUM149. Furthermore, cytokines signaling pathway involved were also identified.

Results

U937 secreted cytokines, chemokines and growth factors were characterized by cytokine antibody array. The major U937 secreted cytokines/chemokines were interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1/CCL2). When SUM149 cells were seeded in three dimensional (3D) models with media conditioned by U937 secreted cytokines, chemokines and growth factors; results showed: 1) changes in the morphology of IBC cells from epithelial to migratory spindle shape branched like structures; 2) Over-expression of adhesion molecule fibronectin and not E-cadherin. Further analysis revealed that over-expression of fibronectin may be mediated by IL-8 via PI3K/Akt signaling pathway.

Conclusion

The present results suggested that cytokines secreted by human monocytes may promote chemotactic migration and spreading of IBC cell lines. Results also indicated that IL-8 the major secreted cytokine by U937 cells may play essential role in fibronectin expression by SUM149 cells via interaction with IL-8 specific receptors and stimulation of PI3K/Akt signaling pathway.

Recovery from glycerol-induced acute kidney injury is accelerated by suramin

Acute kidney injury (AKI) is a common and potentially life-threatening complication after ischemia/reperfusion and exposure to nephrotoxic agents. In this study, we examined the efficacy and mechanism(s) of suramin in promoting recovery from glycerol-induced AKI, a model of rhabdomyolysis-induced AKI. After intramuscular glycerol injection (10 ml of 50% glycerol per kilogram) into male Sprague-Dawley rats, serum creatinine maximally increased at 24 to 72 h and then decreased at 120 h. Creatinine clearance (CrCl) decreased 75% at 24 to 72 h and increased at 120 h. Suramin (1 mg/kg i.v.) administered 24 h after glycerol accelerated recovery of renal function as demonstrated by increased CrCl, decreased renal kidney injury molecule-1, and improved histopathology 72 h after glycerol injection. Suramin treatment decreased interleukin-1β (IL-1β) mRNA, transforming growth factor-β(1) (TGF-β(1)), phospho-p65 of nuclear factor-κB (NF-κB), and cleaved caspase-3 at 48 h compared with glycerol alone. Suramin treatment also decreased glycerol-induced activation of intracellular adhesion molecule-1 (ICAM-1) and leukocyte infiltration at 72 h. Urinary/renal neutrophil gelatinase-associated lipocalin 2 (NGAL) levels, hemeoxygenase-1 expression, and renal cell proliferation were increased by suramin compared with glycerol alone at 72 h. Mechanistically, suramin decreases early glycerol-induced proinflammatory (IL-1β and NF-κB) and growth inhibitory (TGF-β(1)) mediators, resulting in the prevention of late downstream inflammatory effects (ICAM-1 and leukocyte infiltration) and increasing compensatory nephrogenic repair. These results support the hypothesis that delayed administration of suramin is effective in abrogating apoptosis, attenuating inflammation, and enhancing nephrogenic repair after glycerol-induced AKI.

Cellular and molecular mechanisms of renal fibrosis

Renal fibrosis, particularly tubulointerstitial fibrosis, is the common final outcome of almost all progressive chronic kidney diseases. Renal fibrosis is also a reliable predictor of prognosis and a major determinant of renal insufficiency. Irrespective of the initial causes, renal fibrogenesis is a dynamic and converging process that consists of four overlapping phases: priming, activation, execution and progression. Nonresolving inflammation after a sustained injury sets up the fibrogenic stage (priming) and triggers the activation and expansion of matrix-producing cells from multiple sources through diverse mechanisms, including activation of interstitial fibroblasts and pericytes, phenotypic conversion of tubular epithelial and endothelial cells and recruitment of circulating fibrocytes. Upon activation, matrix-producing cells assemble a multicomponent, integrin-associated protein complex that integrates input from various fibrogenic signals and orchestrates the production of matrix components and their extracellular assembly. Multiple cellular and molecular events, such as tubular atrophy, microvascular rarefaction and tissue hypoxia, promote scar formation and ensure a vicious progression to end-stage kidney failure. This Review outlines our current understanding of the cellular and molecular mechanisms of renal fibrosis, which could offer novel insights into the development of new therapeutic strategies.