Pál Pacher

Publications of Pál Pacher

• Cisplatin Nephrotoxicity Involves Mitochondrial Injury with Impaired Tubular Mitochondrial Enzyme Activity.

  Authors: Zsuzsanna K Zsengellér, Lena Ellezian, Dan Brown, Béla Horváth, Partha Mukhopadhyay, Balaraman Kalyanaraman, Samir M Parikh, S Ananth Karumanchi, Isaac E Stillman, Pál Pacher

  The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 04/2012;

• Regulation of macrophage function by adenosine.

  Authors: György Haskó, Pál Pacher

  Arteriosclerosis, thrombosis, and vascular biology. 04/2012; 32(4):865-9.

  Following its release into the extracellular space in response to metabolic disturbances, the endogenous nucleoside adenosine exerts a range of immunomodulatory effects and cells of the mononuclearFollowing its release into the extracellular space in response to metabolic disturbances, the endogenous nucleoside adenosine exerts a range of immunomodulatory effects and cells of the mononuclear phagocyte system are among its major targets. Adenosine governs mononuclear phagocyte functions via 4 G-protein-coupled cell membrane receptors, which are denoted A(1), A(2A), A(2B), and A(3) receptors. Adenosine promotes osteoclast differentiation via A(1) receptors and alters monocyte to dendritic cell differentiation through A(2B) receptors. Adenosine downregulates classical macrophage activation mainly through A(2A) receptors. In contrast A(2B) receptor activation upregulates alternative macrophage activation. Adenosine promotes angiogenesis, which is mediated by inducing the production of vascular endothelial growth factor by mononuclear phagocytes through A(2A), A(2B), and A(3) receptors. By regulating mononuclear phagocyte function adenosine dictates the course of inflammatory and vascular diseases and cancer.

• Cannabinoid 1 receptor promotes cardiac dysfunction, oxidative stress, inflammation, and fibrosis in diabetic cardiomyopathy.

  Authors: Mohanraj Rajesh, Sándor Bátkai, Malek Kechrid, Partha Mukhopadhyay, Wen-Shin Lee, Béla Horváth, Eileen Holovac, Resat Cinar, Lucas Liaudet, Ken Mackie, György Haskó, Pál Pacher

  Diabetes. 03/2012; 61(3):716-27.

  Endocannabinoids and cannabinoid 1 (CB(1)) receptors have been implicated in cardiac dysfunction, inflammation, and cell death associated with various forms of shock, heart failure, andEndocannabinoids and cannabinoid 1 (CB(1)) receptors have been implicated in cardiac dysfunction, inflammation, and cell death associated with various forms of shock, heart failure, and atherosclerosis, in addition to their recognized role in the development of various cardiovascular risk factors in obesity/metabolic syndrome and diabetes. In this study, we explored the role of CB(1) receptors in myocardial dysfunction, inflammation, oxidative/nitrative stress, cell death, and interrelated signaling pathways, using a mouse model of type 1 diabetic cardiomyopathy. Diabetic cardiomyopathy was characterized by increased myocardial endocannabinoid anandamide levels, oxidative/nitrative stress, activation of p38/Jun NH(2)-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs), enhanced inflammation (tumor necrosis factor-α, interleukin-1β, cyclooxygenase 2, intracellular adhesion molecule 1, and vascular cell adhesion molecule 1), increased expression of CB(1), advanced glycation end product (AGE) and angiotensin II type 1 receptors (receptor for advanced glycation end product [RAGE], angiotensin II receptor type 1 [AT(1)R]), p47(phox) NADPH oxidase subunit, β-myosin heavy chain isozyme switch, accumulation of AGE, fibrosis, and decreased expression of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA2a). Pharmacological inhibition or genetic deletion of CB(1) receptors attenuated the diabetes-induced cardiac dysfunction and the above-mentioned pathological alterations. Activation of CB(1) receptors by endocannabinoids may play an important role in the pathogenesis of diabetic cardiomyopathy by facilitating MAPK activation, AT(1)R expression/signaling, AGE accumulation, oxidative/nitrative stress, inflammation, and fibrosis. Conversely, CB(1) receptor inhibition may be beneficial in the treatment of diabetic cardiovascular complications.

• Interplay of cannabinoid 2 (CB(2)) receptors with nitric oxide synthases, oxidative and nitrative stress, and cell death during remote neurodegeneration.

  Authors: Pál Pacher, Ken Mackie

  Journal of molecular medicine (Berlin, Germany). 02/2012; 90(4):347-51.

  Remote neuronal degeneration and death/injury, which often occur in regions remote but functionally connected to the primary lesion site, may play a pivotal role in extending neuronalRemote neuronal degeneration and death/injury, which often occur in regions remote but functionally connected to the primary lesion site, may play a pivotal role in extending neuronal damage/dysfunction following traumatic brain injury, stroke, or peripheral nerve injury, as well as in chronic neurodegenerative diseases such as multiple sclerosis and amyotrophic lateral sclerosis. Even though the precise mechanisms of remote neuronal injury are poorly understood and no efficacious treatment options are available, it involves glial activation, inflammation, oxidative/nitrative stress, and apoptotic cell death. The newly discovered endocannabinoid signaling system consisting of endocannabinoids (endogenous bioactive lipid mediators), their synthetic and metabolizing enzymes, and their primary G protein-coupled cannabinoid 1 and 2 (CB(1) and CB(2)) receptors has been implicated in the regulation of numerous physiological and pathological processes/functions, including those associated with neurodegeneration. Using a well-characterized rodent model of remote neuronal degeneration, Oddi et al. (J Mol Med 2012, in press, DOI 10.1007/s00109-012-0884-1 ) have demonstrated that targeting CB(2) cannabinoid receptors may represent a promising novel approach to attenuate this pathological process. This editorial discusses the clinical significance of these interesting observations and the mechanisms of the possible interplay of CB(2) receptors with nitric oxide synthases, oxidative and nitrative stress, and cell death during remote neurodegeneration.

• β-Caryophyllene ameliorates cisplatin-induced nephrotoxicity in a cannabinoid 2 receptor-dependent manner.

  Authors: Béla Horváth, Partha Mukhopadhyay, Malek Kechrid, Vivek Patel, Galin Tanchian, David A Wink, Jürg Gertsch, Pál Pacher

  Free radical biology & medicine. 01/2012; 52(8):1325-33.

  (E)-β-caryophyllene (BCP) is a natural sesquiterpene found in many essential oils of spice (best known for contributing to the spiciness of black pepper) and food plants with recognized(E)-β-caryophyllene (BCP) is a natural sesquiterpene found in many essential oils of spice (best known for contributing to the spiciness of black pepper) and food plants with recognized anti-inflammatory properties. Recently it was shown that BCP is a natural agonist of endogenous cannabinoid 2 (CB(2)) receptors, which are expressed in immune cells and mediate anti-inflammatory effects. In this study we aimed to test the effects of BCP in a clinically relevant murine model of nephropathy (induced by the widely used antineoplastic drug cisplatin) in which the tubular injury is largely dependent on inflammation and oxidative/nitrative stress. β-caryophyllene dose-dependently ameliorated cisplatin-induced kidney dysfunction, morphological damage, and renal inflammatory response (chemokines MCP-1 and MIP-2, cytokines TNF-α and IL-1β, adhesion molecule ICAM-1, and neutrophil and macrophage infiltration). It also markedly mitigated oxidative/nitrative stress (NOX-2 and NOX-4 expression, 4-HNE and 3-NT content) and cell death. The protective effects of BCP against biochemical and histological markers of nephropathy were absent in CB(2) knockout mice. Thus, BCP may be an excellent therapeutic agent to prevent cisplatin-induced nephrotoxicity through a CB(2) receptor-dependent pathway. Given the excellent safety profile of BCP in humans it has tremendous therapeutic potential in a multitude of diseases associated with inflammation and oxidative stress.

• The endocannabinoid system and plant-derived cannabinoids in diabetes and diabetic complications.

  Authors: Béla Horváth, Partha Mukhopadhyay, György Haskó, Pál Pacher

  The American journal of pathology. 12/2011; 180(2):432-42.

  Oxidative stress and inflammation play critical roles in the development of diabetes and its complications. Recent studies provided compelling evidence that the newly discovered lipid signalingOxidative stress and inflammation play critical roles in the development of diabetes and its complications. Recent studies provided compelling evidence that the newly discovered lipid signaling system (ie, the endocannabinoid system) may significantly influence reactive oxygen species production, inflammation, and subsequent tissue injury, in addition to its well-known metabolic effects and functions. The modulation of the activity of this system holds tremendous therapeutic potential in a wide range of diseases, ranging from cancer, pain, neurodegenerative, and cardiovascular diseases to obesity and metabolic syndrome, diabetes, and diabetic complications. This review focuses on the role of the endocannabinoid system in primary diabetes and its effects on various diabetic complications, such as diabetic cardiovascular dysfunction, nephropathy, retinopathy, and neuropathy, particularly highlighting the mechanisms beyond the metabolic consequences of the activation of the endocannabinoid system. The therapeutic potential of targeting the endocannabinoid system and certain plant-derived cannabinoids, such as cannabidiol and Δ9-tetrahydrocannabivarin, which are devoid of psychotropic effects and possess potent anti-inflammatory and/or antioxidant properties, in diabetes and diabetic complications is also discussed.

• Adenosine augments IL-10 production by microglial cells through an A2B adenosine receptor-mediated process.

  Authors: Balázs Koscsó, Balázs Csóka, Zsolt Selmeczy, Leonóra Himer, Pál Pacher, László Virág, György Haskó

  Journal of immunology (Baltimore, Md. : 1950). 11/2011; 188(1):445-53.

  Microglia are activated by pathogen-associated molecular patterns and produce proinflammatory cytokines, such as TNF-α, IL-6, and IL-12, and the anti-inflammatory cytokine IL-10. Adenosine is anMicroglia are activated by pathogen-associated molecular patterns and produce proinflammatory cytokines, such as TNF-α, IL-6, and IL-12, and the anti-inflammatory cytokine IL-10. Adenosine is an endogenous purine nucleoside and a ligand of four G protein-coupled adenosine receptors (ARs), which are the A(1)AR, A(2A)AR, A(2B)AR, and A(3)AR. ARs have been shown to suppress TNF-α production by microglia, but their role in regulating IL-10 production has not been studied. In this study, we demonstrate that adenosine augments IL-10 production by activated murine microglia while suppressing the production of proinflammatory cytokines. Because the order of potency of selective AR agonists in inducing IL-10 production was NECA > IB-MECA > CCPA ≥ CGS21680, and the A(2B)AR antagonist MRS1754 prevented the effect of NECA, we conclude that the stimulatory effect of adenosine on IL-10 production is mediated by the A(2B)AR. Mechanistically, adenosine augmented IL-10 mRNA accumulation by a transcriptional process. Using mutant IL-10 promoter constructs we showed that a CREB-binding region in the promoter mediated the augmenting effect of adenosine on IL-10 transcription. Chromatin immunoprecipitation analysis demonstrated that adenosine induced CREB phosphorylation at the IL-10 promoter. Silencing CREB using lentivirally delivered short hairpin RNA blocked the enhancing effect of adenosine on IL-10 production, confirming a role for CREB in mediating the stimulatory effect of adenosine on IL-10 production. In addition, adenosine augmented IL-10 production by stimulating p38 MAPK. Collectively, our results establish that A(2B)ARs augment IL-10 production by activated murine microglia.

• Mitochondrial-targeted antioxidants represent a promising approach for prevention of cisplatin-induced nephropathy.

  Authors: Partha Mukhopadhyay, Béla Horváth, Zsuzsanna Zsengellér, Jacek Zielonka, Galin Tanchian, Eileen Holovac, Malek Kechrid, Vivek Patel, Isaac E Stillman, Samir M Parikh, Joy Joseph, Balaraman Kalyanaraman, Pál Pacher

  Free radical biology & medicine. 11/2011; 52(2):497-506.

  Cisplatin is a widely used antineoplastic agent; however, its major limitation is the development of dose-dependent nephrotoxicity whose precise mechanisms are poorly understood. Here we show notCisplatin is a widely used antineoplastic agent; however, its major limitation is the development of dose-dependent nephrotoxicity whose precise mechanisms are poorly understood. Here we show not only that mitochondrial dysfunction is a feature of cisplatin nephrotoxicity, but also that targeted delivery of superoxide dismutase mimetics to mitochondria largely prevents the renal effects of cisplatin. Cisplatin induced renal oxidative stress, deterioration of mitochondrial structure and function, an intense inflammatory response, histopathological injury, and renal dysfunction. A single systemic dose of mitochondrially targeted antioxidants, MitoQ or Mito-CP, dose-dependently prevented cisplatin-induced renal dysfunction. Mito-CP also prevented mitochondrial injury and dysfunction, renal inflammation, and tubular injury and apoptosis. Despite being broadly renoprotective against cisplatin, Mito-CP did not diminish cisplatin's antineoplastic effect in a human bladder cancer cell line. Our results highlight the central role of mitochondrially generated oxidants in the pathogenesis of cisplatin nephrotoxicity. Because similar compounds seem to be safe in humans, mitochondrially targeted antioxidants may represent a novel therapeutic approach against cisplatin nephrotoxicity.

• Adenosine promotes alternative macrophage activation via A2A and A2B receptors.

  Authors: Balázs Csóka, Zsolt Selmeczy, Balázs Koscsó, Zoltán H Németh, Pál Pacher, Peter J Murray, Diane Kepka-Lenhart, Sidney M Morris, William C Gause, S Joseph Leibovich, György Haskó

  FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 09/2011; 26(1):376-86.

  Adenosine has been implicated in suppressing the proinflammatory responses of classically activated macrophages induced by Th1 cytokines. Alternative macrophage activation is induced by the Th2Adenosine has been implicated in suppressing the proinflammatory responses of classically activated macrophages induced by Th1 cytokines. Alternative macrophage activation is induced by the Th2 cytokines interleukin (IL)-4 and IL-13; however, the role of adenosine in governing alternative macrophage activation is unknown. We show here that adenosine treatment of IL-4- or IL-13-activated macrophages augments the expression of alternative macrophage markers arginase-1, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and macrophage galactose-type C-type lectin-1. The stimulatory effect of adenosine required primarily A(2B) receptors because the nonselective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) increased both arginase activity (EC(50)=261.8 nM) and TIMP-1 production (EC(50)=80.67 nM), and both pharmacologic and genetic blockade of A(2B) receptors prevented the effect of NECA. A(2A) receptors also contributed to the adenosine augmentation of IL-4-induced TIMP-1 release, as both adenosine and NECA were less efficacious in augmenting TIMP-1 release by A(2A) receptor-deficient than control macrophages. Of the transcription factors known to drive alternative macrophage activation, CCAAT-enhancer-binding protein β was required, while cAMP response element-binding protein and signal transducer and activator of transcription 6 were dispensable in mediating the effect of adenosine. We propose that adenosine receptor activation suppresses inflammation and promotes tissue restitution, in part, by promoting alternative macrophage activation.

• Ecto-5'-nucleotidase (CD73) decreases mortality and organ injury in sepsis.

  Authors: György Haskó, Balázs Csóka, Balázs Koscsó, Rachna Chandra, Pál Pacher, Linda F Thompson, Edwin A Deitch, Zoltán Spolarics, László Virág, Pál Gergely, Rolando H Rolandelli, Zoltán H Németh

  Journal of immunology (Baltimore, Md. : 1950). 09/2011; 187(8):4256-67.

  The extracellular concentrations of adenosine are increased during sepsis, and adenosine receptors regulate the host's response to sepsis. In this study, we investigated the role of theThe extracellular concentrations of adenosine are increased during sepsis, and adenosine receptors regulate the host's response to sepsis. In this study, we investigated the role of the adenosine-generating ectoenzyme, ecto-5'-nucleotidase (CD73), in regulating immune and organ function during sepsis. Polymicrobial sepsis was induced by subjecting CD73 knockout (KO) and wild type (WT) mice to cecal ligation and puncture. CD73 KO mice showed increased mortality in comparison with WT mice, which was associated with increased bacterial counts and elevated inflammatory cytokine and chemokine concentrations in the blood and peritoneum. CD73 deficiency promoted lung injury, as indicated by increased myeloperoxidase activity and neutrophil infiltration, and elevated pulmonary cytokine levels. CD73 KO mice had increased apoptosis in the thymus, as evidenced by increased cleavage of caspase-3 and poly(ADP-ribose) polymerase and increased activation of NF-κB. Septic CD73 KO mice had higher blood urea nitrogen levels and increased cytokine levels in the kidney, indicating increased renal dysfunction. The increased kidney injury of CD73 KO mice was associated with augmented activation of p38 MAPK and decreased phosphorylation of Akt. Pharmacological inactivation of CD73 in WT mice using α, β-methylene ADP augmented cytokine levels in the blood and peritoneal lavage fluid. These findings suggest that CD73-derived adenosine may be beneficial in sepsis.

• Poly(ADP-ribose) polymerase-1 is a key mediator of cisplatin-induced kidney inflammation and injury.

  Authors: Partha Mukhopadhyay, Béla Horváth, Malek Kechrid, Galin Tanchian, Mohanraj Rajesh, Amarjit S Naura, A Hamid Boulares, Pál Pacher

  Free radical biology & medicine. 08/2011; 51(9):1774-88.

  Cisplatin is a commonly used chemotherapeutic drug, the clinical use of which is limited by the development of dose-dependent nephrotoxicity. Enhanced inflammatory response, oxidative stress, andCisplatin is a commonly used chemotherapeutic drug, the clinical use of which is limited by the development of dose-dependent nephrotoxicity. Enhanced inflammatory response, oxidative stress, and cell death have been implicated in the development of cisplatin-induced nephropathy; however, the precise mechanisms are elusive. Overactivation of the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) by oxidative DNA damage under various pathological conditions promotes cell death and up-regulation of key proinflammatory pathways. In this study, using a well-established model of nephropathy, we have explored the role of PARP-1 in cisplatin-induced kidney injury. Genetic deletion or pharmacological inhibition of PARP-1 markedly attenuated the cisplatin-induced histopathological damage, impaired renal function (elevated serum BUN and creatinine levels), and enhanced inflammatory response (leukocyte infiltration; TNF-α, IL-1β, F4/80, adhesion molecules ICAM-1/VCAM-1 expression) and consequent oxidative/nitrative stress (4-HNE, 8-OHdG, and nitrotyrosine content; NOX2/NOX4 expression). PARP inhibition also facilitated the cisplatin-induced death of cancer cells. Thus, PARP activation plays an important role in cisplatin-induced kidney injury, and its pharmacological inhibition may represent a promising approach to preventing the cisplatin-induced nephropathy. This is particularly exciting because several PARP inhibitors alone or in combination with DNA-damaging anticancer agents show considerable promise in clinical trials for treatment of various malignancies (e.g., triple-negative breast cancer).

• Sulforaphane, a natural constituent of broccoli, prevents cell death and inflammation in nephropathy.

  Authors: Carlos Enrique Guerrero-Beltrán, Partha Mukhopadhyay, Béla Horváth, Mohanraj Rajesh, Edilia Tapia, Itzhel García-Torres, José Pedraza-Chaverri, Pál Pacher

  The Journal of nutritional biochemistry. 06/2011;

  Cisplatin (cis-diamminedichloroplatinum II, CIS) is a potent and widely used chemotherapeutic agent to treat various malignancies, but its therapeutic use is limited because of dose-dependentCisplatin (cis-diamminedichloroplatinum II, CIS) is a potent and widely used chemotherapeutic agent to treat various malignancies, but its therapeutic use is limited because of dose-dependent nephrotoxicity. Cell death and inflammation play a key role in the development and progression of CIS-induced nephropathy. Sulforaphane (SFN), a natural constituent of cruciferous vegetables such as broccoli, Brussels sprouts, etc., has been shown to exert various protective effects in models of tissue injury and cancer. In this study, we have investigated the role of prosurvival, cell death and inflammatory signaling pathways using a rodent model of CIS-induced nephropathy, and explored the effects of SFN on these processes. Cisplatin triggered marked activation of stress signaling pathways [p53, Jun N-terminal kinase (JNK), and p38-α mitogen-activated protein kinase (MAPK)] and promoted cell death in the kidneys (increased DNA fragmentation, caspases-3/7 activity, terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick-end labeling), associated with attenuation of various prosurvival signaling pathways [e.g., extracellular signal-regulated kinase (ERK) and p38-β MAPK]. Cisplatin also markedly enhanced inflammation in the kidneys [promoted NF-κB activation, increased expression of adhesion molecules ICAM and VCAM, enhanced tumor necrosis factor-α (TNF-α) levels and inflammatory cell infiltration]. These effects were significantly attenuated by pretreatment of rodents with SFN. Thus, the cisplatin-induced nephropathy is associated with activation of various cell death and proinflammatory pathways (p53, JNK, p38-α, TNF-α and NF-κB) and impairments of key prosurvival signaling mechanisms (ERK and p38-β). SFN is able to prevent the CIS-induced renal injury by modulating these pathways, providing a novel approach for preventing this devastating complication of chemotherapy.

• Female X-chromosome mosaicism for NOX2 deficiency presents unique inflammatory phenotype and improves outcome in polymicrobial sepsis.

  Authors: Rachna Chandra, Stephanie Federici, Zoltán H Németh, Béla Horváth, Pál Pacher, György Haskó, Edwin A Deitch, Zoltán Spolarics

  Journal of immunology (Baltimore, Md. : 1950). 06/2011; 186(11):6465-73.

  Cellular X-chromosome mosaicism, which is unique to females, may be advantageous during pathophysiological challenges compared with the single X-chromosome machinery of males, and it may contributeCellular X-chromosome mosaicism, which is unique to females, may be advantageous during pathophysiological challenges compared with the single X-chromosome machinery of males, and it may contribute to gender dimorphism in the inflammatory response. We tested the hypothesis of whether cellular mosaicism for the X-linked gp91phox (NOX2) deficiency, the catalytic component of the superoxide anion-generating NADPH oxidase complex, is advantageous during polymicrobial sepsis. Deficient, wild-type (WT), and heterozygous/mosaic mice were compared following polymicrobial sepsis initiated by cecal ligation and puncture. Compared with WT littermates, sepsis-induced mortality was improved in deficient mice, as well as in mosaic animals carrying both deficient and WT phagocyte subpopulations. In contrast, blood bacterial counts were greatest in deficient mice. Consistent with poor survival, WT mice also showed the most severe organ damage following sepsis. In mosaic animals, the deficient neutrophil subpopulations displayed increased organ recruitment and elevated CD11b membrane expression compared with WT neutrophil subpopulations within the same animal. The dynamics of sepsis-induced blood and organ cytokine content and WBC composition changes, including lymphocyte subsets in blood and bone marrow, showed differences among WT, deficient, and mosaic subjects, indicating that mosaic mice are not simply the average of the deficient and WT responses. Upon oxidative burst, interchange of oxidants between WT and deficient neutrophil subpopulations occurred in mosaic mice. This study suggests that mice mosaic for gp91phox expression have multiple advantages compared with WT and deficient mice during the septic course.

• Soluble guanylate cyclase as an emerging therapeutic target in cardiopulmonary disease.

  Authors: Johannes-Peter Stasch, Pál Pacher, Oleg V Evgenov

  Circulation. 05/2011; 123(20):2263-73.

• Suppression of tumorigenicity 2: a janus-faced player in sepsis.

  Authors: György Haskó, Pál Pacher

  American journal of respiratory and critical care medicine. 04/2011; 183(7):841-3.

• Investigational A₃ adenosine receptor targeting agents.

  Authors: Balázs Koscsó, Balázs Csóka, Pál Pacher, György Haskó

  Expert opinion on investigational drugs. 04/2011; 20(6):757-68.

  INTRODUCTION: Adenosine is an endogenous nucleoside that accumulates in the extracellular space in response to metabolic stress and cell damage. Extracellular adenosine is a signaling molecule thatINTRODUCTION: Adenosine is an endogenous nucleoside that accumulates in the extracellular space in response to metabolic stress and cell damage. Extracellular adenosine is a signaling molecule that signals by activating four GPCRs: the A(1), A(2A), A(2B) and A(3) receptors. Since the discovery of A(3) adenosine receptors, accumulating evidence has identified these receptors as potential targets for therapeutic intervention. AREAS COVERED: A(3) adenosine receptors are expressed on the surface of most immune cell types, including neutrophils, macrophages, dendritic cells, lymphocytes and mast cells. A(3) adenosine receptor activation on immune cells governs a broad array of immune cell functions, which include cytokine production, degranulation, chemotaxis, cytotoxicity, apoptosis and proliferation. In accordance with their multitudinous immunoregulatory actions, targeting A(3) adenosine receptors has been shown to impact the course of a wide spectrum of immune-related diseases, such as asthma, rheumatoid arthritis, cancer, ischemia and inflammatory disorders. EXPERT OPINION: Given the existence of both preclinical and early clinical data supporting the utility of A(3) adenosine receptor ligands in treating immune-related diseases, further development of A(3) adenosine receptor ligands is anticipated.

• Δ(8) -Tetrahydrocannabivarin protects against hepatic ischemia/reperfusion injury by attenuating oxidative stress and inflammatory response involving CB(2) receptors.

  Authors: Sándor Bátkai, Partha Mukhopadhyay, Bėla Horváth, Mohanraj Rajesh, Rachel Y Gao, Anu Mahadevan, Mukkanti Amere, Natalia Battista, Aron H Lichtman, Lisa A Gauson, Mauro Maccarrone, Roger G Pertwee, Pál Pacher

  British journal of pharmacology. 04/2011;

  BACKGROUND AND PURPOSE: Activation of cannabinoid 2 (CB(2) ) receptors is protective against various forms of reperfusion injury. Δ(8) -tetrahydrocannabivarin (Δ(8) -THCV) is a synthetic analog ofBACKGROUND AND PURPOSE: Activation of cannabinoid 2 (CB(2) ) receptors is protective against various forms of reperfusion injury. Δ(8) -tetrahydrocannabivarin (Δ(8) -THCV) is a synthetic analog of the plant cannabinoid Δ(9) -tetrahydrocannabivarin, which has been reported to exert anti-inflammatory effects in rodents involving activation of CB(2) receptors. EXPERIMENTAL APPROACH: In this study we have explored if Δ(8) -THCV or its metabolite 11-OH-Δ(8) -THCV activates CB(2) receptors in vitro, and if Δ(8) -THCV protects against hepatic ischemia/reperfusion (I/R) injury in vivo. KEY RESULTS: Displacement of [(3) H]CP55940 by Δ(8) -THCV or 11-OH-Δ(8) -THCV from specific binding sites in Chinese hamster ovary (CHO) cell membranes transfected with human CB(2) receptors (hCB(2) ) yielded K(i) values of 68.4 and 59.95 nM, respectively. Δ(8) -THCV or 11-OH-Δ(8) -THCV inhibited the forskolin-stimulated cyclic AMP production by hCB(2) CHO cells (EC(50) = 12.95 and 14.3 nM, respectively). Δ(8) -THCV, given prior to the induction of I/R, significantly attenuated the extent of liver damage (measured by serum alanine aminotransferase and aspartate aminotransferase levels), decreased tissue protein carbonyl adducts, 4-hydroxy-2-nonenal (HNE), macrophage inflammatory protein-1alpha and 2 (MIP-1α/CCL3, MIP-2/CXCL2), tumor necrosis factor-alpha (TNF-α), inter-cellular adhesion molecule 1 (ICAM-1/CD54) mRNA levels, tissue neutrophil infiltration, caspase3/7 activity and DNA fragmentation. The protective effect of Δ(8) -THCV against liver damage was also preserved when given at the beginning of reperfusion. CB(2) receptor antagonist pretreatment attenuated the protective effect of Δ(8) -THCV, while CB(1) antagonist rather tended to enhance it. CONCLUSIONS AND IMPLICATIONS: Δ(8) -THCV can activate CB(2) receptors in vitro and decrease tissue injury and inflammation associated with I/R partly via CB(2) receptor activation.

• A new cannabinoid 2 receptor agonist HU-910 attenuates oxidative stress, inflammation, and cell death associated with hepatic ischemia/reperfusion injury.

  Authors: Bėla Horváth, Lital Magid, Partha Mukhopadhyay, Sándor Bátkai, Mohanraj Rajesh, Ogyi Park, Galin Tanchian, Rachel Y Gao, Catherine E Goodfellow, Michelle Glass, Raphael Mechoulam, Pál Pacher

  British journal of pharmacology. 03/2011;

  BACKGROUND AND PURPOSE: Cannabinoid 2 (CB(2) ) receptor activation has been reported to attenuate myocardial, cerebral and hepatic ischemia-reperfusion (I/R) injury. EXPERIMENTAL APPROACH: We haveBACKGROUND AND PURPOSE: Cannabinoid 2 (CB(2) ) receptor activation has been reported to attenuate myocardial, cerebral and hepatic ischemia-reperfusion (I/R) injury. EXPERIMENTAL APPROACH: We have investigated the effects of a novel CB(2) receptor agonist HU-910 on liver injury inflicted by 1hour of ischemia followed by 2,6 or 24hours of reperfusion, using a well-established mouse model of segmental hepatic I/R. KEY RESULTS: Displacement of [(3) H]CP55940 by HU-910 from specific binding sites in Chinese hamster ovary (CHO) cell membranes transfected with human CB(2) or CB(1) receptors (hCB(1/2) ) yielded Ki values of 6 nM and 1.4 µM, respectively. HU-910 inhibited the forskolin-stimulated cyclic AMP production by hCB(2) CHO cells (EC(50) = 162 nM) and yielded EC(50) of 26.4 nM in [(35) S]GTPγS binding assay using hCB(2 ) expressing CHO membranes. HU-910 given prior to ischemia significantly attenuated the levels of I/R-induced hepatic pro-inflammatory chemokines (macrophage inflammatory protein-1α/2, monocyte chemotactic protein-1), cytokine tumor necrosis factor-α (TNF-α), and inter-cellular adhesion molecule-1, neutrophil infiltration, oxidative stress and cell death. Some of the beneficial effect of HU-910 also persisted when given at the beginning of the reperfusion or 1h after the ischemic episode. Furthermore, HU-910 attenuated the bacterial endotoxin-triggered TNF-α production in isolated Kupffer cells, likewise the adhesion molecules expression in primary human liver sinusoidal endothelial cells stimulated with TNF-α. CB2 receptor antagonist pretreatment significantly attenuated the protective effect of HU-910, while CB1 antagonist rather tended to enhance it. CONCLUSIONS AND IMPLICATIONS: HU-910 is a potent CB(2) receptors agonist which may exert protective effects in various diseases associated with inflammation and tissue injury.

• Cannabidiol protects against hepatic ischemia/reperfusion injury by attenuating inflammatory signaling and response, oxidative/nitrative stress, and cell death.

  Authors: Partha Mukhopadhyay, Mohanraj Rajesh, Béla Horváth, Sándor Bátkai, Ogyi Park, Galin Tanchian, Rachel Y Gao, Vivek Patel, David A Wink, Lucas Liaudet, György Haskó, Raphael Mechoulam, Pál Pacher

  Free radical biology & medicine. 02/2011; 50(10):1368-81.

  Ischemia/reperfusion (I/R) is a pivotal mechanism of liver damage after liver transplantation or hepatic surgery. We have investigated the effects of cannabidiol (CBD), the nonpsychotropicIschemia/reperfusion (I/R) is a pivotal mechanism of liver damage after liver transplantation or hepatic surgery. We have investigated the effects of cannabidiol (CBD), the nonpsychotropic constituent of marijuana, in a mouse model of hepatic I/R injury. I/R triggered time-dependent increases/changes in markers of liver injury (serum transaminases), hepatic oxidative/nitrative stress (4-hydroxy-2-nonenal, nitrotyrosine content/staining, and gp91phox and inducible nitric oxide synthase mRNA), mitochondrial dysfunction (decreased complex I activity), inflammation (tumor necrosis factor α (TNF-α), cyclooxygenase 2, macrophage inflammatory protein-1α/2, intercellular adhesion molecule 1 mRNA levels; tissue neutrophil infiltration; nuclear factor κB (NF-κB) activation), stress signaling (p38MAPK and JNK), and cell death (DNA fragmentation, PARP activity, and TUNEL). CBD significantly reduced the extent of liver inflammation, oxidative/nitrative stress, and cell death and also attenuated the bacterial endotoxin-triggered NF-κB activation and TNF-α production in isolated Kupffer cells, likewise the adhesion molecule expression in primary human liver sinusoidal endothelial cells stimulated with TNF-α and attachment of human neutrophils to the activated endothelium. These protective effects were preserved in CB2 knockout mice and were not prevented by CB1/2 antagonists in vitro. Thus, CBD may represent a novel, protective strategy against I/R injury by attenuating key inflammatory pathways and oxidative/nitrative tissue injury, independent of classical CB1/2 receptors.

• Resveratrol attenuates azidothymidine-induced cardiotoxicity by decreasing mitochondrial reactive oxygen species generation in human cardiomyocytes.

  Authors: Rachel Yue Gao, Partha Mukhopadhyay, Rajesh Mohanraj, Hua Wang, Béla Horváth, Shi Yin, Pál Pacher

  Molecular medicine reports. 01/2011; 4(1):151-5.

  Nucleotide reverse transcriptase inhibitors, such as zidovudine (azidothymidine, AZT) and stavudine, represent a class of approved antiretroviral agents for highly active antiretroviral therapy,Nucleotide reverse transcriptase inhibitors, such as zidovudine (azidothymidine, AZT) and stavudine, represent a class of approved antiretroviral agents for highly active antiretroviral therapy, which prolongs the life expectancy of patients infected with human-immunodeficiency virus. Unfortunately, the use of these drugs is associated with known toxicities in the liver, skeletal muscle, heart and other organs, which may involve increased reactive oxygen species (ROS) generation, among other mechanisms. Resveratrol is a polyphenolic plant-derived antioxidant abundantly found in certain grapes, roots, berries, peanuts and red wine. This study, using primary human cardiomyocytes, evaluated the effects of AZT and pre-treatment with resveratrol on mitochondrial ROS generation and the cell death pathways. AZT induced concentration-dependent cell death, involving both caspase-3 and -7 and poly(ADP-ribose) polymerase activation, coupled with increased mitochondrial ROS generation in human cardiomyocytes. These effects of AZT on mitochondrial ROS generation and cell death may be attenuated by resveratrol pre-treatment. The results demonstrate that mitochondrial ROS generation plays a pivotal role in the cardiotoxicity of AZT in human cardiomyocytes, and resveratrol may provide a potential strategy to attenuate these pathological alterations, which are associated with widely used antiretroviral therapy.