P2 X 7 receptor is a critical regulator of extracellular ATP-induced profibrotic genes expression in rat kidney: implication of transforming growth factor-ß/Smad signaling pathway.

This study was designed to investigate the potential of extracellular adenosine 5'-triphosphate (ATP) via the P2 X 7 receptor to activate the renal fibrotic processes in rats. The present study demonstrates that administration of ATP rapidly activated transforming growth factor-ß (TGF-ß) to induce phosphorylation of Smad-2/3. Renal connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA and protein expressions were also increased following ATP administration. A decrease in TGF-ß amount in serum as well as renal Smad-2/3 phosphorylation was noticed in animals pre-treated with the specific antagonist of P2 X 7 receptor, A 438,079. In addition, a significant reduction in mRNA and protein expression of CTGF and TIMP-1were also observed in the kidneys of those animals. Collectively, the current findings demonstrate that ATP has the ability to augment TGF-ß-mediated Smad-2/3 phosphorylation and enhance the expression of the pro-fibrotic genes, CTGF and TIMP-1, an effect that is largely mediated via P2 X 7 receptor.

Omeprazole induces profibrotic gene expression in rat kidney: implication of TGF-ß/Smad signaling pathway.

Proton pump inhibitors (PPIs) are one of the most commonly prescribed medications. However, PPI usage is linked to a higher risk of both acute and chronic renal damage by mechanisms not entirely known. The present study demonstrates that omeprazole (10 mg/kg body weight, i.p.) causes TGF-ß/Smad signaling activation and subsequent expression of the profibrotic genes CTGF and TIMP-1 in rat kidney. Increased production of CTGF and TIMP-1 accompany activation of the TGF-ß/Smad signaling cascade. However, simultaneous treatment of omeprazole and the TGF-ß inhibitor, disitertide (P144) (1 mg/kg body weight i.p.) suppresses the TGF-ß/Smad signaling pathway and subsequent production of CTGF and TIMP-1. Additionally, TGF-ß level in rat kidney was highly reduced in animals treated with the ROS (reactive oxygen species) scavenger, N-acetyl cysteine (NAC) (100 mg/kg body weight i.p.) before omeprazole administration. Furthermore, the reduction in SOD activity brought by omeprazole was returned to the normal level in those animals. However, MDA level increased by omeprazole was highly reduced in the presence of NAC. Collectively, the current findings demonstrate that omeprazole has the ability to promote the expression of the profibrotic genes CTGF and TIMP-1 in a ROS and TGF-ß dependent manner. The present study suggests the co-use of ROS scavenger to improve the therapeutic use of the PPI omeprazole.

A low dose of naloxone mitigates autoimmune hepatitis by regulating TLR4/NF-κB and Nrf2/HO-1 signaling pathways.

Naloxone is a non-selective opiate receptor antagonist that is mainly used in the management of acute opioid overdose or intoxication. Previously, naloxone has been shown to have anti-inflammatory and antioxidant properties. Concanavalin A (Con A) model is a common and well established animal model of autoimmune hepatitis that closely resembles the pathological alterations that occur in human. The present study demonstrates that a low dose of naloxone (LD NX) has the ability to improve hepatic function and attenuate hepatic damage induced by Con A as indicated by a clear reduction in serum aminotransferase, bilirubin and enhancement of albumin production as well as liver pathological changes. Also, The proinflammatory cytokines, tumor necrosis factor-α (TNF-α), interferon- γ (IFN-γ), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) were highly suppressed in animals pretreated with LD NX via interference with TLR4/NF-κB as well as JNK signaling pathways. Furthermore, oxidative stress was highly attenuated in animals pretreated with LD NX as indicated by high reduction in hepatic MDA and an increase in Nrf2, HO-1 expression and subsequent production of the endogenous antioxidants, SOD, CAT and GSH. Collectively, this study demonstrates that LD NX has the ability to mitigate Con A-induced autoimmune hepatitis via modulation of inflammatory cytokines secretion and interference with reactive oxygen species generation.

Role of motor proteins in human cancers.

Motor proteins include several protein families (Kinesin, Dynein and Myosin) responsible for intracellular transport, intercellular communication, among other functions. In cancer cells, motor proteins along with microtubules (MT) and other tubulin and actin structures, are crucial for cell proliferation and invasion. The cBioPortal platform for Cancer Genomics database was queried for solid cancers in a combined cohort of 9204 patients with complete cancer genomics data. To assess the importance of motor proteins in cancer, copy number alterations (CNAs) and survival rates were analyzed in the combined dataset. Kinesin, Dynein, and Myosin families showed CNAs in 47%, 49%, and 57 % of patients, respectively, in at least one of their members. Survival analysis showed that CNAs in Kinesin and Dynein, families' genes in the same patients were significantly correlated to decreased overall survival. These results added more evidence to previous literature highlighting the importance of motor proteins as a target in cancer therapy. Kinesin inhibitors could act by several mechanisms such as inhibiting spindle assembly or centrosome separation during mitosis, leading to cell cycle arrest and eventually apoptosis. Dynein inhibitors modulate Dynein's activity and MT binding, inhibiting cell proliferation and invasion. Myosin inhibitors act by stabilizing MT, inducing cell cycle arrest and inhibiting invasiveness. Increasing the specificity of motor proteins targeting drugs could improve cancer therapy and patient survival.

Curcumin augments the cardioprotective effect of metformin in an experimental model of type I diabetes mellitus; Impact of Nrf2/HO-1 and JAK/STAT pathways.

Metformin is one of the most commonly prescribed antidiabetic drugs. A recent clinical study has highlighted the protective role of metformin against cardiac complications in type I diabetes. Curcumin is a natural compound with well-known antioxidant and anti-inflammatory properties. The present study was designed to investigate the possible role of curcumin in potentiating metformin`s putative effects. Rats received single injection of 52.5 mg/kg streptozocin and the diabetic rats were treated with metformin (200 mg/kg/day), curcumin (100 mg/kg/day) and their combination for 6 weeks. Diabetic rats showed degenerated myocardium as well as significant increase in Creatine Kinase-MB (CK-MB), troponin I and TGF-ß1 levels. In addition, cardiac levels of lipid peroxidation, IL-6, and NF-κB were significantly elevated. Although treatment with metformin restored most of the measured parameters, it showed insignificant improvement in histopathological architecture accompanied by absence of antioxidant effect. Interestingly, concomitant administration of curcumin along with metformin revealed more protection than metformin alone. Inhibition of JAK/STAT pathway and activation of Nrf2/HO-1 pathway seems to be among the mechanisms mediating the effects of curcumin and metformin. The findings of this study highlight the benefits of metformin/curcumin combination in preventing diabetic cardiomyopathy.

Vitamin E inhibits cyclosporin A-induced CTGF and TIMP-1 expression by repressing ROS-mediated activation of TGF-ß/Smad signaling pathway in rat liver.

Cyclosporin A (CsA) is the most common immunosuppressive drug used in organ transplantation. However, the clinical use of CsA is often limited by several side effects including hepatotoxicity. In the present study, it was found that administration of CsA causes a rapid activation of TGF-ß/Smad signaling cascade and subsequent expression of the profibrotic genes connective tissue growth factor (CTGF) and tissue inhibitors of matrix metallproteinases-1 (TIMP-1) in rat liver. In addition, Smad phosphorylation and subsequent CTGF and TIMP-1 expression were markedly reduced in the presence of neutralizing monoclonal TGFß1-3 antibody. Furthermore, CsA administration significantly increased the serum levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as well as lipid peroxidation in hepatic tissues. Moreover, significant reduction in the hepatic content of reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) was observed in CsA-alone-treated animals. Histopathological changes were also observed in CsA-alone-treated rats. Pretreatment of animals with Vitamin E (Vit E) before CsA administration significantly reduced TGF-ß level as well as Smad phosphorylation and subsequent CTGF and TIMP-1 expression. Furthermore, administration of PEG-SOD clearly attenuated TGF-ß/Smad signaling induced by CsA. Moreover, concomitant administration of Vit E along with CsA significantly ameliorated the histopathological changes and improved liver function as well as the antioxidant capacity. Finally, this study shows that the immunosuppressive efficiency of CsA was not altered in the presence of Vit E. These data may support the concept of using antioxidant therapy as a valuable approach for the prevention of CsA-induced tissue fibrosis.

Propolis alleviates concanavalin A-induced hepatitis by modulating cytokine secretion and inhibition of reactive oxygen species.

Viral hepatitis-induced oxidative stress accompanied by increased levels of transforming growth factor-ß (TGF-ß) and hepatic fibrosis are hallmarks of hepatitis C virus infection. The present study was designed to investigate the potential protective effect of propolis against liver injury induced by concanavalin A (Con A), a T-cell-dependent model that causes an immune-mediated hepatitis in a similar pattern to the one induced by viral infections. In the present study, rats were randomly divided into four groups. The first group (control) was administered the vehicle of Con A (i.v.) for 24 h. The second group received Con A (12 mg/kg body weight i.v.) for 24 h. The third group received propolis (300 mg/kg by oral gavage) 5 days before and concurrently with Con A for 24 h. The last group received propolis alone. Following a single injection of Con A, histopathological changes as well as significant reduction in albumin level were observed. In addition, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin were significantly increased. These increases correlated with an increase in lipid peroxidation and downregulation of reduced glutathione (GSH) as well as superoxide dismutase (SOD) and catalase activities in liver tissue. Furthermore, these changes were associated with an increase in serum levels of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) as well as the profibrotic cytokine TGF-ß. Moreover, TGF- ß activation was accompanied with an increase in Smad phosphorylation. Interestingly, concomitant administration of propolis along with Con A significantly attenuated all these negative effects and improved liver function indicating that propolis has the ability to protect rats from Con A-induced hepatitis.

Molecular mechanisms of PDGF-AA expression induced by the dsRNA-mimetic poly (I:C) and IL-18.

Several animal studies suggest a role of platelet-derived growth factors (PDGFs) particularly A and B in atherosclerosis. Previously, it has been shown that viral infections have the ability to initiate and accelerate atherosclerosis in animal models. Recently, it has been reported that IL-18 has a pro-atherogenic character. Moreover, viral infections have been shown to be associated with induction of IL-18 bioactivity. By using human predendritic KG1 cells, we sought to assess PDGF-AA production under the influence of IL-18 and the byproduct of viral replication, dsRNA-mimetic poly (I:C). Here we demonstrate that poly (I:C) and IL-18 have the ability to induce PDGF-AA expression. In addition, costimulation of KG-1 cells with both IL-18 plus poly (I:C) shows an additive effect on PDGF-AA production. Furthermore, we demonstrate that neither p38 nor SAPK/JNK is required for PDGF-AA production by both PIC and IL-18. However, the expression of PDGF-AA has been found to be associated with increased activation of NF-κB and enhancement of DNA-binding capacity of NF-κB as shown by electrophoretic mobility shift assay (EMSA) and supershift analysis. Collectively, this study demonstrates that the byproduct of viral replication, dsRNA [poly (I:C)], and IL-18 have the ability to induce PDGF-AA in NF-κB-dependent manner. Furthermore, dsRNA act in an additive way with IL-18 to induce PDGF-AA which plays a major role in atherosclerosis. These data might help to understand the pro-atherogenic character of IL-18 and molecular mechanisms of viral infection-induced atherosclerosis.

The dsRNA-mimetic poly (I:C) and IL-18 synergize for IFNgamma and TNFalpha expression.

Interleukin (IL)-18 bioactivity and dsRNA sensing by receptors of innate immunity are key components of anti-viral host defense. Despite extensive data on signal transduction activated by both pathways knowledge on cross-communication is incomplete. By using human PBMC and predendritic KG1 cells, as prototypic IL-18-responsive cellular models, we sought to assess cytokine production under the influence of IL-18 and the dsRNA-mimetic poly (I:C). Here, we report on potent synergy between both mediators concerning pro-inflammatory IFNgamma and TNFalpha production. KG1 data revealed that synergistic induction likely relied on TLR3 and was associated with prolonged/increased activation of NF-kappaB, as detected by IkappaB analysis and luciferase reporter assays, respectively. Moreover, extended activation of JNK was mediated by IL-18/poly (I:C). Although vital for innate immunity, overwhelming induction of inflammatory cytokines during viral infections poses the threat of serious collateral tissue damage. The stunning synergism inherent to IL-18/dsRNA-induced TNFalpha/IFNgamma detected herein may contribute to this pathological phenomenon.