Role of JAK3 in the Pathogenesis of Oxidative Stress-Induced Kidney Fibrosis

The Janus kinase (JAK) tyrosine kinase family and JAK/STAT signal transduction pathway may act in kidney fibrogenesis. JAK3 expression was investigated in in vitro and in vivo models of kidney fibrosis involving oxidative stress. There was a marked down-regulation of JAK3 mRNA in rat kidney tubular epithelial cells (NRK52E) and fibroblasts (NRK49F) exposed to 1.0 mM H2O2 for 18–20 h compared with controls, which correlated with increased apoptosis and decreased mitosis in both cell lines. However, JAK3 protein levels were not significantly different in control and H2O2-treated epithelial and fibroblast cultures. JAK3 activation (phospho-tyrosine) increased in NRK52E cells and decreased in NRK49F cells with oxidative stress. STAT3 phosphorylation decreased in both cell lines with oxidative stress compared with controls. JAK3 protein expression and localisation were investigated in kidneys using the unilateral ureteral obstruction (UUO) model (0–7 days, rats) of kidney fibrosis that involves oxidative stress. JAK3 protein expression did not differ between UUO and controls; however, JAK3 localisation increased temporally with UUO, with strong epithelial expression in mitotic cells compared with controls. Apoptotic tubular epithelium showed minimal JAK3. In summary, in vitro, decreased kidney JAK3 mRNA after oxidative stress was not seen translationally. Differences in the activation of the JAK3/STAT3 pathway may have different consequences for renal fibrosis. In vivo, changes in JAK3 protein localisation, and especially its colocalisation with mitotic cells, indicate that JAK3 protein may contribute to renal tubular epithelial cell proliferation after oxidative stress

Lentiviral-Mediated RNA Interference against TGF-Beta Receptor Type II in Renal Epithelial and Fibroblast Cell Populations In Vitro Demonstrates Regulated Renal Fibrogenesis That Is More Efficient than a Nonlentiviral Vector

Background. Lentiviral constructs reportedly can integrate into the genome of non-dividing, terminally differentiated cells and dividing cells, for long-term gene expression. This investigation tested whether a third generation lentiviral-mediated small interfering RNA (siRNA) delivered into renal epithelial and fibroblast cells against type II transforming growth factor-beta receptor (siRNA-TBRII) could better attenuate renal fibrogenesis in comparison with a non-lentiviral construct. Methods. HIV-derived lentiviral and non-lentiviral constructs were used to transfect cells with siRNA-TBRII or siRNA-EGFP control. Human embryonic kidney (HEK-293T), renal epithelial cells (NRK-52E) and renal fibroblasts (NRK-49F) were transfected and gene silencing quantified (fluorescence microscopy, Western blotting, fluorescence-activated cell sorting). Renal fibrogenesis was assessed using extracellular matrix protein synthesis (fibronectin and collagen-III; Western immunoblot), and α-smooth muscle actin (α-SMA) was analysed as a marker of fibroblast activation and epithelial-to-mesenchymal transdifferentiation (EMT). Results. Lentiviral-mediated siRNA-TBRII significantly suppressed TBRII expression in all cell lines, and also significantly suppressed renal fibrogenesis. In comparison with the non-lentiviral construct, lentiviral-mediated siRNA-TBRII produced stronger and more persistent inhibition of collagen-III in NRK-49F cells, fibronectin in all renal cell lines, and α-SMA in renal epithelial cells. Conclusions. Lentiviral vector systems against TBRII can be delivered into renal cells to efficiently limit renal fibrogenesis by sequence-specific gene silencing

Evaluation of Steroid Hormones and their Receptors in Development and Progression of Renal Cell Carcinoma

Steroid hormones and their receptors have important roles in normal kidney biology, and alterations in their expression and function help explain the differences in development of kidney diseases, such as nephrotic syndrome and chronic kidney disease. The distinct gender difference in incidence of renal cell carcinoma (RCC), with males having almost twice the incidence as females globally, also suggests a role for sex hormones or their receptors in RCC development and progression. There was a peak in interest in evaluating the roles of androgen and estrogen receptors in RCC pathogenesis in the late 20th century, with some positive outcomes for RCC therapy that targeted estrogen receptors, especially for metastatic disease. Since that time, however, there have been few studies that look at use of steroid hormone modulators for RCC, especially in the light of new therapies such as the tyrosine kinase inhibitors and new immune therapies, which are having some success for treatment of metastatic RCC. This review summarises past and current literature and attempts to stimulate renewed interest in research into the steroid hormones and their receptors, which might be used to effect, for example, in combination with the other newer targeted therapies for RCC

Multiphoton microscopy can visualize zonal damage and decreased cellular metabolic activity in hepatic ischemia-reperfusion injury in rats

Ischemia-reperfusion (I/R) injury is a common occurrence in liver surgery. In orthotopic transplantation, the donor liver is exposed to periods of ischemia and when oxygenated blood is reintroduced to the liver, oxidative stress may develop and lead to graft failure. The aim of this project was to investigate whether noninvasive multiphoton and fluorescence lifetime imaging microscopy, without external markers, were useful in detecting early liver damage caused by I/R injury. Localized hepatic ischemia was induced in rats for 1 h followed by 4 h reperfusion. Multiphoton and fluorescence lifetime imaging microscopy was conducted prior to ischemia and up to 4 h of reperfusion and compared to morphological and biochemical assessment of liver damage. Liver function was significantly impaired at 2 and 4 h of reperfusion. Multiphoton microscopy detected liver damage at 1 h of reperfusion, manifested by vacuolated cells and heterogeneous spread of damage over the liver. The damage was mainly localized in the midzonal region of the liver acinus. In addition, fluorescence lifetime imaging showed a decrease in cellular metabolic activity. Multiphoton and fluorescence lifetime imaging microscopy detected evidence of early I/R injury both structurally and functionally. This provides a simple noninvasive technique useful for following progressive liver injury without external markers. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3647597

PAR2 activation on human tubular epithelial cells engages converging signaling pathways to induce an inflammatory and fibrotic milieu

Key features of chronic kidney disease (CKD) include tubulointerstitial inflammation and fibrosis. Protease activated receptor-2 (PAR2), a G-protein coupled receptor (GPCR) expressed by the kidney proximal tubular cells, induces potent proinflammatory responses in these cells. The hypothesis tested here was that PAR2 signalling can contribute to both inflammation and fibrosis in the kidney by transactivating known disease associated pathways. Using a primary cell culture model of human kidney tubular epithelial cells (HTEC), PAR2 activation induced a concentration dependent, PAR2 antagonist sensitive, secretion of TNF, CSF2, MMP-9, PAI-1 and CTGF. Transcription factors activated by the PAR2 agonist 2F, including NFκB, AP1 and Smad2, were critical for production of these cytokines. A TGF-β receptor-1 (TGF-βRI) kinase inhibitor, SB431542, and an EGFR kinase inhibitor, AG1478, ameliorated 2F induced secretion of TNF, CSF2, MMP-9, and PAI-1. Whilst an EGFR blocking antibody, cetuximab, blocked PAR2 induced EGFR and ERK phosphorylation, a TGF-βRII blocking antibody failed to influence PAR2 induced secretion of PAI-1. Notably simultaneous activation of TGF-βRII (TGF-β1) and PAR2 (2F) synergistically enhanced secretion of TNF (2.2-fold), CSF2 (4.4-fold), MMP-9 (15-fold), and PAI-1 (2.5-fold). In summary PAR2 activates critical inflammatory and fibrotic signalling pathways in human kidney tubular epithelial cells. Biased antagonists of PAR2 should be explored as a potential therapy for CKD

Anti-coagulant and anti-thrombotic properties of blacklip abalone (Haliotis rubra): in vitro and animal studies

Sulphated polysaccharides with anti-thrombotic and anti-coagulant activities have been found in various marine biota. In this study, a previously characterised anti-thrombotic and anti-coagul ant extract from blacklip abalone was fractionated by anion exchange chromatography (AEC), pooled (on a sulphated polysaccharide basis) and administered to Wistar rats via oral gavage (N = 8) for assessment as an oral therapeutic. To ensure that the preparation had anti-coagulant activity prior to oral administration, it was assessed in rat blood by thromboelastography (TEG) significantly increasing reaction (R) time (or time until clot formation). Following in vitro confirmation of anti-coagulant activity, 40 mg of the preparation was orally administered to rats with blood samples collected at 2, 4, and 6 h post-gavage. Assessment of all blood samples by TEG showed some prolongation of R time from 355 to 380 s after 4 h. Dosing of the post-gavage blood samples with the abalone preparation to confirm anti-thrombotic activity in vitro revealed residual anti-coagulant activity, further suggesting that oral administration did increase anti-coagulant potential in the collected blood but that bioavailability was low. Assessment of tissues and haematological parameters showed no obvious harmful effects of the abalone preparation in animals. In summary, even though oral administration of fractionated and pooled blacklip abalone extract to rats delayed clotting after 4 h, bioavailability of the preparation appeared to be low and may be more appropriate for intravenous administration as an anti-thrombotic or anti-coagulant therapeutic

Understanding molecular pathways and targets of brachyury in epithelial-mesenchymal transition (EMT) in human cancers

Brachyury is an important transcription factor of the T-box gene family with an evolutionarily-conserved function in mesoderm development in the embryo. Recent research has demonstrated that, in various human carcinomas, overexpression of Brachyury is associated with epithelial-mesenchymal transition (EMT), tumor metastasis, expression of markers for cancer stem cells, and resistance to chemotherapy and radiotherapy. Brachyury is a diagnostic and prognostic biomarker, and its expression in tumor tissues is associated with increasing tumor grade, stage, invasiveness, metastasis and poor prognosis. Targeting of Brachyury-positive tumor cells may modulate the extent of EMT and stop invasiveness. Fibroblast growth factor, transforming growth factor-β and other EMT signalling factors are involved in the molecular pathways of Brachyury in tumorigenesis and development. Experimentally, Brachyury knockdown resulted in downregulation of EMT and stem cell markers, formation of tumor spheroids, and invasiveness. Treatment with recombinant yeast-Brachyury vector-based vaccine can activate and expand Brachyury-specific CD4+ and CD8+ Tcells in vitro, with an outcome of lysis of human tumor cells expressing the Brachyury protein. Further understanding of the characteristics of Brachyury and its associated signaling pathways might help in developing novel therapeutic strategies against EMT

Nontraditional (non-Western pharmaceutical) treatments for chronic kidney disease

Nontraditional, non-Western medicines, often called complementary and alternative medicines (CAM), for chronic kidney disease (CKD) patients are, potentially, a huge low-cost therapy resource for poorer populations in the world. Use of CAM, particularly from plant sources, is common in poorer communities, but the scientific basis for their use is still under-researched and under-published. This review presents information on the treatment of kidney disease with CAM, particularly CKD and its closely associated cardiovascular disease (CVD), which might benefit vulnerable populations. The challenges of developing CAM therapies for resource-limited environments are also discussed, particularly with reference to targeting oxidative stress, a known cause of progressive diseases such as CKD and CVD. Oxidative stress is a mechanism often targeted by CAM, with good scientific basis. Dietary supplementation with antioxidants is one approach to reducing CKD incidence or morbidity. Antioxidant supplementation in populations with sufficient dietary antioxidant intake often report little benefit. In comparison, poorer populations that may have restricted nutritional dietary antioxidant intake may benefit from supplementation with antioxidants. Also needing consideration are the recorded instances of nephrotoxicity from CAM therapies, particularly related to nephrotoxic plant extracts, extract-drug reactions, and toxicity from contaminants within the extracts. As long as the possible toxicity of plant-derived CAM is considered, we argue that populations having marked deficiency in, or poor access to, dietary antioxidants, or high exposure to environmental oxidants, may benefit from these nontraditional medicines