Concanavalin A-induced Acute Liver Injury Research Articles

Anti-CD24 neutralizing antibody exacerbates Concanavalin A-induced acute liver injury in mice via liver M1 macrophages

Liver largely relies on its innate immunity to initiate quick and effective defense against potentially toxic agents, and innate immune cells are major players in this process. However, excessive inflammation due to out-of-control immune response may eventually cause liver injury. Thus, it is important to fully understand the regulatory mechanisms associated with liver inflammation. Here we showed that anti-CD24 neutralizing antibody exacerbated hepatic inflammation in a Con A-induced acute liver injury murine model. Our results supported that hepatic macrophages were required for anti-CD24 neutralizing antibody-aggravated liver inflammation, as depletion of macrophages significantly alleviated Con A-induced inflammation. M1 macrophages, but not M2 macrophages, were specifically induced by Con A, and more greatly by Con A in combination with anti-CD24 neutralizing antibody. The combined treatment further promoted M1 hepatic macrophages to express TNF-α, which increased hepatocytes apoptosis. Taken together, these data suggest that anti-CD24 neutralizing antibody plays an important role in aggravating inflammation in the process of Con A-induced acute liver injury in mice. The possible mechanism might involve the enhanced secretion of TNF-α by hepatic M1 macrophages. This study also implicates a role for CD24 in negative regulation of Con A-induced liver inflammation.

MicroRNA-674-5p/5-LO axis involved in autoimmune reaction of Concanavalin A-induced acute mouse liver injury.

Autoimmune hepatitis is characterized, in part, by the pathways involving cysteinyl-leukotriene metabolites of arachidonic acid, the dynamics of which remain unclear. Here, we explored post-transcriptional regulation in the 5-lipoxygenase (5-LO) pathway of arachidonic acid in a Concanavalin A (Con A) induced mouse model. We found that Con A administration lead to 5-LO overexpression and cysteinyl-leukotriene release in early hepatic injury, which was attenuated by cyclosporin A pretreatment. Subsequent microarray and qRT-PCR analysis further showed that microRNA-674-5p (miR-674-5p) displayed a significant decrease in expression in Con A-damaged liver. Noting that miR-674-5p harbors a potential binding region for 5-LO, we further transfected hepatic cell lines with overexpressing miR-674-5p mimic and discovered a negative regulating effect of miR-674-5p on 5-LO expression in the presence of IL-6 or TNF-α. These findings suggest that miR-674-5p might be a negative regulator in 5-LO mediated autoimmune liver injury, representing a compelling avenue towards future therapeutic interventions.

Shikonin Attenuates Concanavalin A-Induced Acute Liver Injury in Mice via Inhibition of the JNK Pathway.

Objective. Shikonin possesses anti-inflammatory effects. However, its function in concanavalin A-induced acute liver injury remains uncertain. The aim of the present study was to investigate the functions of shikonin and its mechanism of protection on ConA-induced acute liver injury. Materials and Methods. Balb/C mice were exposed to ConA (20 mg/kg) via tail vein injection to establish acute liver injury; shikonin (7.5 mg/kg and 12.5 mg/kg) was intraperitoneally administered 2 h before the ConA injection. The serum liver enzyme levels and the inflammatory cytokine levels were determined at 3, 6, and 24 h after ConA injection. Results. After the injection of ConA, inflammatory cytokines IL-1β, TNF-α, and IFN-γ were significantly increased. Shikonin significantly ameliorated liver injury and histopathological changes and suppressed the release of inflammatory cytokines. The expressions of Bcl-2 and Bax were markedly affected by shikonin pretreatment. LC3, Beclin-1, and p-JNK expression levels were decreased in the shikonin-pretreated groups compared with the ConA-treated groups. Shikonin attenuated ConA-induced liver injury by reducing apoptosis and autophagy through the inhibition of the JNK pathway. Conclusion. Our results indicated that shikonin pretreatment attenuates ConA-induced acute liver injury by inhibiting apoptosis and autophagy through the suppression of the JNK pathway.

Role of inflammatory macrophages and CCR9/CCL25 chemokine axis in the pathogenesis of liver injury as a therapeutic target.

It is widely known that a variety of immune cells in the liver contribute to the pathogenesis of liver diseases. Recently, roles of chemokines/chemokines receptors axes regarding the migration of immune competent cells to the inflamed liver have been reported as possible therapeutic targets. We here showed that CCR9+ CD11b+ macrophages play an important role during the course of Concanavalin A-induced murine acute liver injury as well as human acute hepatitis via the production of inflammatory cytokines and the Th1 induction. Further analysis using liver-shielded radiation and bone marrow (BM) transplantation model mice revealed that these CCR9+ CD11b+ macrophages are originated from BM-derived monocytes, but not liver resident macrophages (Kupffer cells). Furthermore, these CD11b+ inflammatory macrophages in contact with hepatic stellate cells contribute to the pathogenesis of murine experimental liver fibrosis via CCR9/CCL25 axis. Collectively, these results with further verification in human samples clarify the pathogenic role of CCR9/CCL25 axis as therapeutic target of a variety of liver diseases.

Tonsil-derived mesenchymal stem cells alleviate concanavalin A-induced acute liver injury

Acute liver failure, the fatal deterioration of liver function, is the most common indication for emergency liver transplantation, and drug-induced liver injury and viral hepatitis are frequent in young adults. Stem cell therapy has come into the limelight as a potential therapeutic approach for various diseases, including liver failure and cirrhosis. In this study, we investigated therapeutic effects of tonsil-derived mesenchymal stem cells (T-MSCs) in concanavalin A (ConA)- and acetaminophen-induced acute liver injury. ConA-induced hepatitis resembles viral and immune-mediated hepatic injury, and acetaminophen overdose is the most frequent cause of acute liver failure in the United States and Europe. Intravenous administration of T-MSCs significantly reduced ConA-induced hepatic toxicity, but not acetaminophen-induced liver injury, affirming the immunoregulatory capacity of T-MSCs. T-MSCs were successfully recruited to damaged liver and suppressed inflammatory cytokine secretion. T-MSCs expressed high levels of galectin-1 and -3, and galectin-1 knockdown which partially diminished interleukin-2 and tumor necrosis factor α secretion from cultured T-cells. Galectin-1 knockdown in T-MSCs also reversed the protective effect of T-MSCs on ConA-induced hepatitis. These results suggest that galectin-1 plays an important role in immunoregulation of T-MSCs, which contributes to their protective effect in immune-mediated hepatitis. Further, suppression of T-cell activation by frozen and thawed T-MSCs implies great potential of T-MSC banking for clinical utilization in immune-mediated disease.

Evaluation of Concanavalin A-induced Acute Liver Injury in Rats using an Empirical Mathematical Model and Dynamic Contrast-enhanced MR Imaging with Gd-EOB-DTPA

We evaluated concanavalin A (Con A)-induced acute hepatic injury in rats using an empirical mathematical model (EMM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA). We allocated 18 rats into 3 groups of six each and intravenously injected them with either 10 mg/kg body weight (BW) of Con A (Con A [10] group), 20 mg/kg BW of Con A (Con A [20] group), or a single dose of of saline (4 mL/kg BW, normal control group). We performed the DCE-MRI studies using Gd-EOB-DTPA (0.025 mmol Gd/kg; 0.1 mL/kg BW) as the contrast agent 24 hours after injection of Con A or saline. We then sampled blood, measured serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and calculated the rate of contrast uptake (α), rate of contrast washout (β), area under the curve (AUC), time to maximum relative enhancement (RE) (T(max)), and elimination half-life of RE (T(1/2)) from the time-signal intensity curves using the EMM. β values were significantly smaller in the Con A (10) and Con A (20) groups than the control group, but α did not differ significantly among the 3 groups. The AUC value was significantly greater in the Con A (10) group than controls, and the T(max) and T(1/2) values were significantly greater in the Con A (20) group than controls. The β, T(max), and T(1/2) values correlated significantly with AST and ALT. In conclusion, the EMM is useful for evaluating Con A-induced acute hepatic injury using DCE-MRI with Gd-EOB-DTPA.

Synthesis and biological evaluation of novel dimethyl[1,1′-biphenyl]-2,2′-dicarboxylate derivatives containing thiazolidine-2,4-dione for the treatment of concanavalin A-induced acute liver injury of BALB/c mice

In this paper, we reported the synthesis of bifendate derivatives and evaluation of anti-inflammatory activity by detecting the production of the Nitric Oxide (NO) in the lipopolysaccharide(LPS)-stimulated RAW 264.7 cell lines. Among the newly derivatives, compound 7k was the most potent one and two other compounds ( 7e and 7f) also exhibited greater anti-inflammatory activity than bifendate. Further in vivo studies confirmed that 7k significantly and dose-dependently inhibited carrageenan-induced paw edema and decreased the serum levels of alanine aminotransaminase, and aspartate aminotransaminase in concanavalin A-induced hepatitis model. Histopathological evaluation demonstrated that 7k has better hepatoprotective effect on acute liver injury induced by concanavalin A than bifendate, suggesting that 7k is a potential drug candidate for the treatment of hepatic injuries.

CGX, a traditional Korean medicine ameliorates concanavalin A-induced acute liver injury

Concanavalin A (Con A)-induced acute liver injury model is well established as a model of T cell-mediated liver injury, in which T cells and NKT cells exert their cytotoxicity towards liver cells. In this study, we investigated the protective effects of CGX, a traditional Korean medicine against Con A-induced liver injury and its underlying mechanisms. After pretreatment with CGX ( po, 50, 100 or 200 mg/kg) or distilled water once daily during 7 days, Con A (15 mg/kg) was injected intravenously. Thereafter serum level of AST and ALT, lipid peroxidation and cytokines in the liver tissue, and immune cell population in blood and the spleen were analyzed. CGX treatment reduced serum ALT, AST level in a dose-dependent manner. CGX treatment significantly decreased the lipid peroxidation and glutathione depletion in the liver tissue, and also lowered tissue levels of tumor necrotic factor-α and interferon-γ. CGX treatment attenuated the compositional alteration of Tc, Th, NKT, and B cells in blood as well as in the spleen. These results suggest that CGX has hepatoprotective property against Con A-induced liver injury through antioxidant action and immune regulation.

Corrections to Discovery of (Z)-5-(4-Methoxybenzylidene)thiazolidine-2,4-dione, a Readily Available and Orally Active Glitazone for the Treatment of Concanavalin A-Induced Acute Liver Injury of BALB/c Mice

Corrections to Discovery of (<i>Z</i>)-5-(4-Methoxybenzylidene)thiazolidine-2,4-dione, a Readily Available and Orally Active Glitazone for the Treatment of Concanavalin A-Induced Acute Liver Injury of BALB/c Mice

Discovery of (Z)-5-(4-Methoxybenzylidene)thiazolidine-2,4-dione, a Readily Available and Orally Active Glitazone for the Treatment of Concanavalin A-Induced Acute Liver Injury of BALB/c Mice

A large amount of evidence suggests that monocytes/macrophages infiltration is implicated in a variety of inflammatory diseases including acute liver injury. Monocyte chemoattractant protein 1 (MCP-1) plays a crucial role in the process of macrophages recruitment. We herein presented a small-molecule library and a feasible quick screening method of evaluating potency of inhibition of chemotaxis of RAW264.7 cells stimulated by MCP-1. Fifty-three small molecules were synthesized and screened, and four compounds (2g, 2h, 4f, and 6h) showed inhibitory effects with IC(50) values range from 0.72 to 20.47 microM, with compound 4f being the most efficient. Further in vivo studies demonstrated that oral administration of 2g, 2h, 4f, or 6h decreases, most significantly for 4f, the serum levels of alanine aminotransaminase (ALT) and asparate aminotransaminase (AST) in ConA-induced acute livery injury BALB/c mice. Histopathological evaluation liver sections confirmed 4f as a potent, orally active compound for hepatoprotective effects against ConA-induced acute liver injury in BALB/c mice.

Short-form Ron receptor is required for normal IFN-γ production in concanavalin A-induced acute liver injury

Abrogation of Ron receptor tyrosine kinase function results in defects in macrophage activation and dysregulated acute inflammatory responses in vivo. Several naturally occurring constitutively active alternative forms of Ron have been identified, including from primary human tumors and tumor cell lines. One of these alternative forms, short-form (SF) Ron, is generated from an alternative start site in intron 10 of the Ron gene that eliminates most of the extracellular portion of the receptor and is overexpressed in several human cancers. To test the physiological significance of SF-Ron in vivo, mice were generated that solely express the full-length form of Ron (FL-Ron). Our results show that elimination of the capacity to express SF-Ron in vivo leads to augmented production of IFN-gamma from splenocytes following stimulation ex vivo with either concanavalin A or anti-CD3/T cell receptor monoclonal antibody. Moreover, in a concanavalin A-induced murine model of acute liver injury, FL-Ron mice have increased production of serum INF-gamma and serum alanine aminotransferase levels and worsened liver histology and overall survival compared with wild-type control mice. Taken together, these results suggest for the first time that SF-Ron impacts the progression of inflammatory immune responses in vivo and further support a role for the Ron receptor and its various forms in liver pathophysiology.

A selective adenosine A 2A receptor agonist, ATL-146e, prevents concanavalin A-induced acute liver injury in mice

Background and aims Concanavalin A (Con A) activates T lymphocytes and induces CD4 + T cell-mediated hepatic injury in mice. Pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-6 (IL-6), are critical mediators in this experimental model. Activation of adenosine A 2A receptors reduces the production of various pro-inflammatory cytokines and suppresses T cell activation. A selective adenosine A 2A receptor agonist (ATL-146e) has been shown to be a potent inhibitor of inflammation by increasing intracellular cyclic AMP (cAMP) in leukocytes. The aim of the present study was to determine whether ATL-146e could ameliorate Con A-induced hepatic injury, reduction of pro-inflammatory cytokine production. Methods Balb/c mice were injected with 25 mg/kg Con A with or without a single injection of ATL-146e (0.5–50 μg/kg), 5 min prior to Con A administration. Liver enzymes, histology, and serum levels of tumor necrosis factor-α, interferon-γ, and interleukin-6 were examined. We also assessed the effects of ATL-146e on pro-inflammatory cytokine production with CD4 + T cell. Results Pretreatment with ATL-146e significantly reduced serum levels of liver enzymes ( P < 0.001). The serum pro-inflammatory cytokines were all increased after Con A administration and reduced to near normal levels by ATL-146e. ATL-146e also inhibited CD4 + T cell pro-inflammatory cytokine production. Conclusion A selective adenosine A 2A receptor agonist, ATL-146e, can prevent concanavalin A-induced hepatic injury that is presumably mediated by its anti-inflammatory properties.