AhR Activation Leads to Attenuation of Murine Autoimmune Hepatitis: Single-Cell RNA-Seq Analysis Reveals Unique Immune Cell Phenotypes and Gene Expression Changes in the Liver

The aryl hydrocarbon receptor (AhR) is a ubiquitously expressed ligand-activated transcription factor. While initially identified as an environmental sensor, this receptor has been shown more recently to regulate a variety of immune functions. AhR ligands vary in structure and source from environmental chemicals such as 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and indoles found in cruciferous vegetables to endogenous ligands derived from tryptophan metabolism. In the current study, we used TCDD, a high affinity AhR ligand to study the impact of AhR activation in the murine model of autoimmune hepatitis (AIH). Primarily, we used single-cell RNA-sequencing (scRNA-seq) technology to study the nature of changes occurring in the immune cells in the liver at the cellular and molecular level. We found that AhR activation attenuated concanavalin A (ConA)-induced AIH by limiting chemotaxis of pro-inflammatory immune cell subsets, promoting anti-inflammatory cytokine production, and suppressing pro-inflammatory cytokine production. scRNA-seq analysis showed some unusual events upon ConA injection such as increased presence of mature B cells, natural killer (NK) T cells, CD4+ or CD8+ T cells, Kupffer cells, memory CD8+ T cells, and activated T cells while TCDD treatment led to the reversal of most of these events. Additionally, the immune cells showed significant alterations in the gene expression profiles. Specifically, we observed downregulation of inflammation-associated genes including Ptma, Hspe1, and CD52 in TCDD-treated AIH mice as well as alterations in the expression of migratory markers such as CXCR2. Together, the current study characterizes the nature of inflammatory changes occurring in the liver during AIH, and sheds light on how AhR activation during AIH attenuates liver inflammation by inducing phenotypic and genotypic changes in immune cells found in the liver.

The Protective Role of IL-36/IL-36R Signal in Con A-Induced Acute Hepatitis

The IL-36 family, including IL-36α, IL-36β, IL-36γ, and IL-36R antagonist, belong to the IL-1 superfamily. It was reported that IL-36 plays a role in immune diseases. However, it remains unclear how IL-36 regulates inflammation. To determine the role of IL-36/IL-36R signaling pathways, we established an acute hepatitis mouse model (C57BL/6) by i.v. injection of the plant lectin Con A. We found that the levels of IL-36 were increased in the liver after Con A injection. Our results demonstrated the infiltrated neutrophils, but not the hepatocytes, were the main source of IL-36 in the liver. Using the IL-36R-/- mouse model (H-2b), we surprisingly found that the absence of IL-36 signals led to aggravated liver injury, as evidenced by increased mortality, elevated serum alanine aminotransferase and aspartate aminotransferase levels, and severe liver pathological changes. Further investigations demonstrated that a lack of IL-36 signaling induced intrahepatic activation of CD4+ and CD8+ T lymphocytes and increased the production of inflammatory cytokines. In addition, IL-36R-/- mice had reduced T regulatory cell numbers and chemokines in the liver. Together, our results from the mouse model suggested a vital role of IL-36 in regulating T cell function and homeostasis during liver inflammation.

Antioxidant Capacity and Hepatoprotective Role of Chitosan-Stabilized Selenium Nanoparticles in Concanavalin A-Induced Liver Injury in Mice

Selenium nanoparticles (SeNPs) have attracted wide attention for their use in nutritional supplements and nanomedicine applications. However, their potential to protect against autoimmune hepatitis has not been fully investigated, and the role of their antioxidant capacity in hepatoprotection is uncertain. In this study, chitosan-stabilized SeNPs (CS-SeNPs) were prepared by means of rapid ultra-filtration, and then their antioxidant ability and free-radical scavenging capacity were evaluated. The hepatoprotective potential of a spray-dried CS-SeNPs powder against autoimmune liver disease was also studied in the concanavalin A (Con A)-induced liver injury mouse model. CS-SeNPs with size of around 60 nm exhibited acceptable oxygen radical absorbance capacity and were able to scavenge DPPH, superoxide anion, and hydroxyl radicals. The CS-SeNPs powder alleviated Con A-caused hepatocyte necrosis and reduced the elevated levels of serum alanine transaminase, aspartate transaminase, and lactic dehydrogenase in Con A-treated mice. These results suggest that the CS-SeNPs powder protected the mice from Con-A-induced oxidative stress in the liver by retarding lipid oxidation and by boosting the activities of superoxide dismutase, glutathione peroxidase, and catalase, partly because of its ability to improve Se retention. In conclusion, SeNPs present potent hepatoprotective potential against Con A-induced liver damage by enhancing the redox state in the liver; therefore, they deserve further development.

The Antidepressant Mirtazapine Inhibits Hepatic Innate Immune Networks to Attenuate Immune-Mediated Liver Injury in Mice

Activation of the innate immune system, including tissue macrophages and associated neutrophil infiltration, is an important driver of subsequent adaptive immune responses in many autoimmune diseases, including autoimmune hepatitis (AIH). The antidepressant mirtazapine has a unique complex pharmacology, altering signaling through a number of serotonin and histamine receptors that can impact macrophage function; an effect potentially influencing AIH outcome. In the mouse model of concanavalin A (Con A) induced liver injury (mimics many aspects of human AIH), in which early innate immune activation (i.e., stimulated hepatic macrophages/monocytes recruit neutrophils and additional monocytes to the liver) critically drives immune-mediated hepatitis induction, mirtazapine strikingly and dose-dependently inhibited Con A-induced liver injury. This inflammation-suppressing effect of mirtazapine was linked to an attenuation of Con A-stimulated early innate immune responses within the liver, including inhibition of hepatic macrophage/monocyte activation, decreased hepatic macrophage/monocyte-derived pro-inflammatory cytokine (e.g., TNFα) and chemokine (e.g., CXCL1 and CXCL2) production, suppression of Con A-induced increases in the hepatic expression of the neutrophil relevant endothelial cell adhesion molecule ICAM-1, with the resultant significant reduction in neutrophil recruitment into the liver. Consistent with our findings in the Con A model, mirtazapine also significantly reduced activation-induced release of cytokine/chemokine mediators from human CD14⁺ monocytes in vitro. Conclusion: Our data suggest that mirtazapine can attenuate hepatic innate immune responses that critically regulate the subsequent development of autoimmune liver injury. Therefore, given that it is a safe and widely used medication, mirtazapine may represent a novel therapeutic approach to autoimmune liver disease.

Protective effect of Yiguanjian decoction against DNA damage on concanavalin A-induced liver injury mice model

OBJECTIVE

To investigate the inhibitory effect of Yiguanjian decoction (YD) on DNA damage in Concanavalin A (Con A)-induced liver injury mice model and to explain the possible mechanism.

METHODS

METHODS: Totally 120 male BALB/c mice were randomly divided into 6 groups, 20 mice each: normal group, model group, Bifendate group, YD low dose group, YD middle dose group and YD high dose group. Except normal group, liver injury model induced by Con A was established. While modeling, each mouse in YD group was given YD (0.4 mL/20 g per day) by intragastric administration (0.13 g YD for YD low dose group; 0.26 g for YD middle dose group; 0.52 g for YD high dose group). Bifendate group was given Bifendate (0.2 g·kg-1·d-1) by gavage. Normal group and model group were fed with same volume of physiological saline daily. After 8 weeks, the serum alanine transaminase (ALT) and aspartate transaminase (AST) were tested. The hematoxylin-eosin staining was used to evaluate the grade of liver inflammation and liver fibrosis stage. Hepatocellular DNA damage was detected by single cell gel electrophoresis technology. The protein expression of tumor necrosis factor-α (TNF-α), Bax and MutT Homolog 1 (MTH1) was detected by western blotting and enzyme linked immunosorbent assay. Bax mRNA and MTH1 mRNA were detected by Real-time Polymerase Chain Reaction (PCR).

RESULTS

YD can improve the degree of liver inflammation and fibrosis in the liver of chronic hepatitis mice, the dose effect relationship is remarkable (P < 0.05). YD can reduce liver cell DNA damage. The difference between YD middle dose group and model group was statistically significant (P < 0.05). YD middle dose group had decreased the protein expression of TNF-α in the mice liver of immunological liver injury (P < 0.05). YD can increase the protein expression of Bax (P < 0.05). Compared with normal group, the protein expression of MTH1 was decreased (P < 0.05), but there was no statistical significance between YD group and model group (P > 0.05). YD can increase the mRNA expression of Bax and MTH1 (both P < 0.05).

CONCLUSION

YD can effectively inhibit the DNA damage in immunological liver injury mice, the mechanism may be that it can decrease the TNF-α and increase the Bax and MTH1 expression.

Contribution of the Kallikrein/Kinin System to the Mediation of ConA-Induced Inflammatory Ascites

Intraperitoneal administration of concanavalin A (ConA, 25 mg/kg b.w.), a cell-binding plant lectin was used for inducing inflammatory ascites, and potential inhibitors were tested in 1 h and 2.5 h experiments, i.e. still before the major influx of leucocytes. At the end of the experiment the peritoneal fluid was collected and measured. The ConA-induced ascites was significantly (p<0.01) and dose-dependently inhibited by icatibant (HOE-140), a synthetic polypeptide antagonist of bradykinin receptors. Aprotinin, a kallikrein inhibitor protein also had significant (p<0.01), but less marked inhibitory effect. L-NAME, an inhibitor of NO synthesis, and atropine methylnitrate, an anticholinergic compound, were ineffective. It is concluded, that the kallikrein/kinin system contributes to the mediation of the ConA-induced ascites by increasing subperitoneal vascular permeability, independent of the eventual vasodilation produced by NO. It is known, that membrane glycoproteins are aggregated by the tetravalent ConA and the resulting distortion of membrane structure may explain the activation of the labile prekallikrein. Complete inhibition of the ConA-induced ascites could not be achieved by aprotinin or icatibant, which indicates the involvement of additional mediators.

[The Protective Effect of B7-H4 on Concanavalin A Induced Hepatic Injury in Mice]

OBJECTIVE

To explore the protective effect and its mechanism of B7-H4 on the immuno hepatic injury.

METHODS

The immuno hepatic injury was induced by Concanavalin A (Con A). Sixty KM mice were randomly divided into 4 groups with 15 mice in each group: Group A (saline), Group B (pcDNA3.1-mB7-H4-Fc), Group C (pcDNA3.1), Group D (Con A). One day before the injection of Con A (25 mg/kg), the mice in Group B and Group C received the injection of 100 pg pcDNA3.1-mB7-H4-Fc and 100 microg pcDNA3.1 respectively. The blood samples were collected at 12 h, 24 h and 48 h after Con A injection, the levels of ALT, AST, IL-4 and IFN-gamma were measured. Five mice in each group were sacrificed at the above 3 time points, the liver tissue were harvested for histopathological detection.

RESULTS

After Con A injection, the level of ALT in Group B, C, and D were higher than that in Group A. The level of ALT in Group B was lower than that in Group C and D. The significant difference was found between Group B and Group C. The hepatic injury of Group B was less serious than that of Group C and D.

CONCLUSION

B7-H4 may have protection on the immune injury of liver induced by Con A.

Large graphene quantum dots alleviate immune-mediated liver damage

We investigated the effect of large (40 nm) graphene quantum dots (GQDs) in concanavalin A (Con A; 12 mg/kg i.v.)-induced mouse hepatitis, a T cell-mediated liver injury resembling fulminant hepatitis in humans. Intravenously injected GQDs (50 mg/kg) accumulated in liver and reduced Con A-mediated liver damage, as demonstrated by histopathological analysis and a decrease in liver lipid peroxidation and serum levels of liver transaminases. The cleavage of apoptotic markers caspase-3/PARP and mRNA levels of proapoptotic mediators Puma, Noxa, Bax, Bak1, Bim, Apaf1, and p21, as well as LC3-I conversion to autophagosome-associated LC3-II and expression of autophagy-related (Atg) genes Atg4b, Atg7, Atg12, and beclin-1, were attenuated by GQDs, indicating a decrease in both apoptosis and autophagy in the liver tissue. This was associated with the reduced liver infiltration of immune cells, particularly the T cells producing proinflammatory cytokine IFN-γ, and a decrease in IFN-γ serum levels. In the spleen of GQD-exposed mice, mRNA expression of IFN-γ and its transcription factor T-bet was reduced, while that of the IL-33 ligand ST2 was increased. The hepatoprotective effect of GQDs was less pronounced in ST2-deficient mice, indicating that it might depend on ST2 upregulation. In vitro, GQDs inhibited splenocyte IFN-γ production, reduced the activation of extracellular signal-regulated kinase in macrophage and T cell lines, inhibited macrophage production of the free radical nitric oxide, and reduced its cytotoxicity toward hepatocyte cell line HepG2. Therefore, GQDs alleviate immune-mediated fulminant hepatitis by interfering with T cell and macrophage activation and possibly by exerting a direct hepatoprotective effect.

[Sodium butyrate inhibits HMGB1 expression and release and attenuates concanavalin A-induced acute liver injury in mice]

The purpose of the present study is to explore the protective effects of sodium butyrate (SB) pretreatment on concanavalin A (Con A)-induced acute liver injury in mice. The model animals were first administered intraperitoneally with SB. Half an hour later, acute liver injury mouse model was established by caudal vein injection with Con A (15 mg/kg). Then, levels of serous alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured using standard clinical method by an automated chemistry analyzer, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were measured by ELISA, and pathological changes in hepatic tissue were observed by using HE staining and light microscopy. The expression and release of high-mobility group box 1 (HMGB1) were assessed by using reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry and ELISA. The results showed that the pretreatment of SB significantly protected Con A-treated mice from liver injury as evidenced by the decrease of serum ALT, AST (P < 0.01) and reduction of hepatic tissues necrosis. SB also decreased levels of serous TNF-α and IFN-γ (P < 0.01). Furthermore, the expression and release of HMGB1 were markedly inhibited by SB pretreatment (P < 0.05 or P < 0.01). These results suggest that the attenuating effect of SB on Con A-induced acute liver injury may be due to its role of reducing the TNF-α and IFN-γ production, and inhibiting HMGB1 expression and release.

Protective effect of ellagic acid on concanavalin A-induced hepatitis via toll-like receptor and mitogen-activated protein kinase/nuclear factor κB signaling pathways

Ellagic acid (EA) is present in certain fruits and nuts, including raspberries, pomegranates, and walnuts, and has anti-inflammatory and antioxidant properties. The aims of this study were to examine the protective effect of EA on concanavalin A (Con A)-induced hepatitis and to elucidate its underlying molecular mechanisms in mice. Mice were orally administered EA at different doses before the intravenous delivery of Con A; the different experimental groups were as follows: (i) vehicle control, (ii) Con A alone without EA, (iii) EA at 50 mg/kg, (iv) EA at 100 mg/kg, and (v) EA at 200 mg/kg. We found that EA pretreatment significantly reduced the levels of plasma aminotransferase and liver necrosis in Con A-induced hepatitis. Also, EA significantly decreased the expression levels of the toll-like receptor 2 (TLR2) and TLR4 mRNA and protein in liver tissues. Further, EA decreased the phosphorylation of JNK, ERK1/2, and p38. EA-treated groups showed suppressions of nuclear factor κB (NF-κB) and IκB-α degradation levels in liver tissues. In addition, EA pretreatment decreased the expression of pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and interleukin 1β (IL-1β). These results suggest that EA protects against T-cell-mediated hepatitis through TLR and mitogen-activated protein kinase (MAPK)/NF-κB signaling pathways.

STAT4 knockout mice are more susceptible to concanavalin A-induced T-cell hepatitis

STAT4, which is activated mainly by IL-12, promotes inflammatory responses by inducing Th1 and Th2 cytokines. Recent genome-wide association studies indicate that STAT4 gene variants are associated with risk of various types of liver diseases, but how STAT4 contributes to liver disease pathogenesis remains obscure. In this study, STAT4 activation was detected in liver immune cells from patients with viral hepatitis and autoimmune hepatitis, as well as in a mouse model of concanavalin A (Con A)-induced hepatitis. Such STAT4 activation was detected mainly in T cells, natural killer T cells, and macrophages and Kupffer cells, and was diminished in Il12a(-/-) and Il12b(-/-) mice. As expected, disruption of the Stat4 gene reduced production of Th1 and Th2 cytokines, but surprisingly exacerbated Con A-induced liver injury. Similarly, disruption of Il12a or Il12b also augmented Con A-induced hepatocellular damage. Further studies showed that hepatic natural killer T (NKT) cells from Con A-treated Stat4(-/-) mice had higher levels of FasL expression and increased cytotoxicity against hepatocytes than those from Con A-treated WT mice. In vitro, blocking FasL attenuated Stat4(-/-) NKT cytotoxicity against hepatocytes. In conclusion, despite up-regulation of proinflammatory cytokines, STAT4 protects against acute T-cell hepatitis, which is mediated by direct or indirect down-regulation of FasL expression on NKT cells.

[Effect of ronggan mixture on immunoregulation and hepatocyte apoptosis-related factors in concanavalin A induced acute immunological liver injury mice]

OBJECTIVE

To explore the effect of Ronggan Mixture (RM) on immunoregulation and hepatocyte apoptosis-related factors in concanavalin A (Con A) induced acute immunological liver injury mice.

METHODS

Totally 60 hepatitis B virus (HBV) transgenic mice were randomly divided into 6 groups, i.e., the blank control group, the model group, the RM group, the Herba Artemisiae Scopariae (HAS) group, the Yinchenhao Decoction (YD) group, and the Bifendate group, 10 mice in each group. The acute immunological liver injury model was established by tail vein injection of ConA. Fourteen days before modeling, normal saline was administered to mice in the blank control group and the model group. RM, YD, HAS decoction, and Bifendate solution was respectively given to mice in the RM group, the YD group, the HAS group, and the Bifendate group. The medication was performed once daily. One h after the last gastrogavage, phosphate buffer solution (PBS) was injected to mice in the blank control group from the tail vein. Modeling was conducted by injecting Con A at 3 microg/g body weight from the tail vein. Mice were sacrificed 8 h after modeling. Blood or tissue samples were collected to detect lab indicators such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil), tumor necrosis factor alpha (TNF-alpha), interferon gamma (INF-gamma), IL-4, IL-10, Fas, FasL, Bax, and bcl-2.

RESULTS

There was significant difference in all lab indicators between the normal group and the blank control group (P < 0.05, P < 0.01). Compared with the model group, ALT and AST levels were significantly lower in the RM group and the Bifendate group (P < 0.01); TBil significantly decreased in the RM group (P < 0.01). The expression level of TNF-alpha decreased in the RM group (P <0.05). The expression level of IFN-gamma decreased in the RM group and the YD group (P < 0.05). The expression level of IL-4 could be elevated in all medicated groups (P < 0.05). RM could elevate the expression level of IL-10 (P < 0.05). The expression level of Fas in the liver tissue decreased in the RM group and the YD group (P < 0.05). The expression level of FasL decreased and the expression of bcl-2 gene increased in the RM group (both P < 0.05). The expression level of Bax was down-regulated in the RM group and the YD group (P < 0.05). The ratio of bcl-2/Bax was up-regulated in the RM group (P < 0.05). Meanwhile, RM showed better effect in decreasing expressions of ALT and AST than HAS (P < 0.05). The effect of increasing IL-10 expression levels was better in the RM group than in the YD group (P < 0.01). The effect of decreasing expressions of Fas and FasL was better in the RM group than in the HAS group, the YD group, and the Bifendate group (P < 0.05). The effect of enhancing the expression of IL-10 in the liver tissue was better in the RM group than in the HAS group (P < 0. 05).

CONCLUSION

RM had protective effect on Con A induced acute immunological liver injury mice, which might be achieved by changing the immunological balance of Thl/Th2 factors (decreasing expressions of TNF-alpha and IFN-gamma, elevating expressions of IL-10 and IL-4) and regulating hepatocyte apoptosis-related factors (down-regulating gene expressions of Fas, FasL, and Bax; up-regulating bcl-2 gene expression, and up-regulating the bcl-2/Bax ratio).

The protective effect of intrasplenic transplantation of Ad-IL-18BP/IL-4 gene-modified fetal hepatocytes on ConA-induced hepatitis in mice

Background

Concanavalin A (ConA)-induced hepatitis is an experimental murine model mirroring the pathology of human autoimmune hepatitis.

Aim

To investigate the effects of intrasplenically transplanted fetal hepatocytes (BNL.CL2) transfected with recombinant adenovirus vector expressing the IL-18 binding protein (IL-18BP) and IL-4 fusion protein on ConA-induced hepatitis in mice.

Methods

Ad-IL-18BP/IL-4 was used to infect BNL.CL2 cells. IL-4 and IL-18BP fusion protein expression were detected by ELISA and Western blotting. BNL.CL2 cells infected with Ad-IL-18BP/IL-4 were intrasplenically transplanted into mice. After 10 days, mice were injected with ConA (15 mg/kg), and sacrificed 18 hours later. Liver injury was assessed by serum transaminase and liver histology. TNF-α, IL-18, IL-4, IL-10, IL-12p70 and monocyte-chemoattracting protein (MCP)-1 levels in serum and liver homogenates were detected by ELISA. Signaling molecules in liver homogenates were analyzed by Western blotting.

Results

Ad-IL-18BP/IL-4 effectively expressed the IL-18BP/IL-4 fusion protein for more than 14 days in BNL.CL12 cells. Treatment of mice with Ad-IL-18BP/IL-4-BNL.CL2 before ConA injection significantly reduced the elevated plasma levels of transaminases compared with ConA control groups. TNF-α, IL-18, IL-12p70 and MCP-1 levels in serum and liver homogenates from mice transplanted with Ad-IL-18BP/IL-4-BNL.CL2 were lower and IL-4 and IL-10 levels were higher than control groups. Phosphorylation levels of NF-κB p65, AKT, p38 and JNK1/2 in liver homogenates were markedly suppressed by Ad-IL-18BP/IL-4.

Conclusions

Ad-IL-18BP/IL-4 was effectively transfected into mouse BNL.CL2 cells. Intrasplenic transplantation of Ad-IL-18BP/IL-4-BNL.CL12 cells alleviated the severity of inflammation in ConA-induced experimental hepatitis and provides a useful basis for the targeted gene therapy of liver disease.

Galectin-9 ameliorates Con A-induced hepatitis by inducing CD4(+)CD25(low/int) effector T-Cell apoptosis and increasing regulatory T cell number

Background

T cell-mediated liver damage is a key event in the pathogenesis of many chronic human liver diseases, such as liver transplant rejection, primary biliary cirrhosis, and sclerosing cholangitis. We and other groups have previously reported that galectin-9, one of the β-galactoside binding animal lectins, might be potentially useful in the treatment of T cell-mediated diseases. To evaluate the direct effect of galectin-9 on hepatitis induced by concanavalin A (Con A) administration in mice and to clarify the mechanisms involved, we administered galectin-9 into mice, and evaluated its therapeutic effect on Con A-induced hepatitis.

Methodology/Principal Findings

Galectin-9 was administrated i.v. to Balb/c mice 30 min before Con A injection. Compared with no treatment, galectin-9 pretreatment significantly reduced serum ALT and AST levels and improved liver histopathology, suggesting an ameliorated hepatitis. This therapeutic effect was not only attributable to a blunted Th1 immune response, but also to an increased number in regulatory T cells, as reflected in a significantly increased apoptosis of CD4⁺CD25^low/int effector T cells and in reduced proinflammatory cytokine levels.

Conclusion/Significance

Our findings constitute the first preclinical data indicating that interfering with TIM-3/galectin-9 signaling in vivo could ameliorate Con A-induced hepatitis. This strategy may represent a new therapeutic approach in treating human diseases involving T cell activation.

Adenovirus-mediated viral interleukin-10 gene transfer prevents concanavalin A-induced liver injury

BACKGROUND AND AIM

Liver injury is closely associated with immune inflammation. Lacking immunostimulatory functions, viral interleukin-10 (vIL-10), a cellular IL-10 homologue, has been an attractive molecule for immunomodulatory therapy. We aimed to reveal a protective effect of the gene transfer of an adenoviral vector encoding vIL-10 on liver injury induced by concanavalin A.

METHODS

C57BL/6J mice were intravenously injected with adenoviral vector encoding vIL-10 before concanavalin A challenge. Liver injury was assessed. Interferon-γ and interleukin-4 levels were measured by ELISA. The activation of splenic and hepatic immune cells was analysed using an MTT assay.

RESULTS

Adenoviral vector encoding vIL-10 pretreatment significantly decreased concanavalin A-mediated elevations in serum alanine aminotransaminase and aspartate aminotransaminase activity, and necrotic area in liver tissues. The protective effect of adenoviral vector encoding vIL-10 was attributed to its inhibition of T cell activation, and production of interferon-γ and interleukin-4 by the immune cells. Recombinant mouse IL-10, a high homologous cytokine to vIL-10, effectively downregulated interferon-γ and interleukin-4 release by hepatic mononuclear cells.

CONCLUSION

Adenovirus vector-mediated vIL-10 gene transfer can prevent concanavalin A-induced hepatic injury, minimise pro-inflammatory cytokine release, and inhibit the activation of T lymphocytes.

[An experimental study of the anti-inflammatory action of noopept and its effect on the level of cytokines]

The anti-inflammatory effects of noopept (dipeptide analog of piracetam) upon a single intraperitoneal (i.p.) administration at doses of 1, 5, and 10 mg/kg in comparison to the reference drug diclofenac (10 mg/kg, i.p.) have been studied on a model of acute exudative inflammation induced by carrageenan in outbred rats and concanavalin A (Con A) in CBA mice. The level of cytokines was studied on the lipopolysaccharide (LPS) model (single administration, 100 mg/kg, i.p.) with 5-day administration of noopept at a dose of 5 mg/kg (i.p., before endotoxin injection) in C57BL/6 mice. The administration of noopept led to a significant suppression of the inflammatory response to both carrageenan and Con A. The administration of Con A caused a 16-fold increase in the level of IL-6 interleukin in the blood serum of mice as compared to control. Noopept (5 mg/kg) reduced the level of IL-6 by a factor of 1.8 in the inflammatory response to Con A. The administration of LPS led to pronounced increase in the levels ofpro-inflammatory IL-6 and TNF-alpha in the blood serum of test mice as compared to intact animals. The course administration of noopept (5 mg/kg) significantly decreased the level of IL-6 and reduced by half the level of TNF-alpha.

In vivo consequences of liver-specific interleukin-22 expression in mice: Implications for human liver disease progression

Interleukin-22 (IL-22), which acts as either a proinflammatory or anti-inflammatory cytokine in various disease models, is markedly up-regulated in chronic liver diseases, including hepatitis B and C. In this report, we demonstrate a strong correlation between IL-22 expression in the liver with active, inflammatory human liver disease. To clarify the role of IL-22 up-regulation in the pathogenesis of liver diseases, liver-specific IL-22 transgenic (IL-22TG) mice, under the control of albumin promoter, were developed. Despite elevated IL-22 serum levels ranging from 4,000 to 7,000 pg/mL, IL-22TG mice developed normally without obvious adverse phenotypes or evidence of chronic inflammation (except for slightly thicker epidermis and minor inflammation of the skin) compared with wild-type mice. Interestingly, IL-22TG mice were completely resistant to concanavalin A-induced T cell hepatitis with minimal effect on liver inflammation and had accelerated liver regeneration after partial hepatectomy. Although they did not spontaneously develop liver tumors, IL-22TG mice were more susceptible to diethylnitrosamine-induced liver cancer. Microarray analyses revealed that a variety of antioxidant, mitogenic, acute phase genes were up-regulated in the livers of IL-22TG mice compared with those from wild-type mice.

CONCLUSION

These findings indicate that localized production of IL-22 in the liver promotes hepatocyte survival and proliferation but primes the liver to be more susceptible to tumor development without significantly affecting liver inflammation.

A humanized anti-osteopontin antibody protects from Concanavalin A induced-liver injury in mice

Osteopontin has been implicated in various inflammatory diseases including rheumatoid arthritis, multiple sclerosis, Crohn's disease, and fulminant hepatitis. Increased expression of osteopontin has been detected in pathological foci of these diseases. RA and fulminant hepatitis have been successfully treated by administration of neutralizing anti-osteopontin antibody in mice. However, rodent antibodies are highly immunogenic in humans and therefore limited in their clinical application. Here, a murine monoclonal antibody 23C3 against human osteopontin, was humanized by complementarity-determining region grafting method based on computer-assisted molecular modeling. The humanized version of 23C3, denoted as Hu23C3, was shown to possess affinity comparable to that of its parental antibody. Hu23C3 could also inhibit monocyte migration in response to osteopontin in vitro. Furthermore, in vivo data showed that Hu23C3 significantly protects mice from Concanavalin A (Con A) induced-liver injury in association with the reduction of transaminase activities and improvement of liver injury. Mechanistic studies demonstrated that Hu23C3 inhibited T and NKT cell infiltration, and activation of nuclear factor κB (NF-κB) in the liver, resulting in reduction of TNF-α and IFN-γ production. Thus, our data strongly support that the humanized anti-osteopontin antibody, Hu23C3, may have a potential for the treatment of T cell mediated-hepatitis in human.

[The protective effect of XD in ConA-induced liver injury]

AIM

To explore the protective effect and its mechanism of Modified Xiaochaihu decoction(MXD) in the liver injury of mice. METHORDS: Using Reitman methord to examine serum ALT and ATS; Using sandwich enzyme immunoassay ABC-ELISA to examine serum TNF-α and IFN-γ.

RESULTS

Serum ALT and ATS of MXD large dose group and Xiaochaihu decoction (XD )group were lower than that of animal models group, there was significant difference among groups (P<0.05). There were not significant difference (P>0.05) between serum ALT and ATS of MXD small dose group and that of animal models group; MXD large dose group, XD group and Biphenyldimethylesterate (DDB) group are similar, no difference (P>0.05). Serum TNF-α and IFN-γ of MXD large dose group and XD group were significant lower than that of animal models group, there was significant difference among groups (P<0.05). Serum TNF-α and IFN-γ of XD group ware higher than that of MXD large dose group, there was significant difference among groups (P<0.05). MXD large dose group, XD group and DDB group were similar, no difference.

CONCLUSIONS

Xiaocaihu decoction possesses the effect of pro2 tection of hepatic impairment and the protective mechanism might be associated with the inhibition of apoptosis and immunomodulation.

[Preclinical safety investigation of GB-115 dipeptide]

Preclinical safety investigations of newly synthesized dipeptide compound GB-115 (amide N-phenylhexanoyl-glycyl-L-tryptophan), an antagonist of cholecystokinin receptors, were performed. No animals were lost after GB-115 acute oral administration at a maximum dose of 6000 mg/kg in mice and at 3500 mg/kg in rats. GB-115 administered per os during 6 months in rabbits and rats (both males and females) at the doses of 0.1 and 10 mg/kg induced no irreversible pathological changes in organs and systems studied. The tested dipeptide exhibited no allergenic, immunotoxic and mutagenic activity, and did not affect generative function and the antenatal and postnatal development of progeny. GB-115 at a dose of 10 mg/kg produced suppression of the inflammatory reaction to concanavalin A.

[Therapeutic efficacy of bone marrow-derived mesenchymal stem cells infused into mice with liver injury induced by concanavalin A]

The aim of this study was to evaluate the therapeutic potential of bone marrow mesenchymal stem cells (MSC) on acute liver injury induced by concanavalin A (ConA). MSCs were isolated from male C57BL/6 mice and cultured, and a ConA-induced acute liver injury model was used. MSCs were systemically infused immediately after mice were challenged with ConA, control mice received only saline infusion. 24 hours after MSC transplantation, the level of serum aminotransferases, histologic change and in situ apoptosis of cells were detected, the expression of inflammatory mediators were examined by real-time RT-PCR. The results indicated that MSC transplantation significantly reduced ConA-induced acute liver injury, including the decrease of the level of serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST) and the extenuation of liver necrosis and in situ apoptosis. Furthermore, after MSC infusion the expression of TNF-alpha, IFN-gamma in liver decreased greatly (p<0.05) with no statistical difference in the expression of iNOS, IL-2 and IL-10 (p>0.05). It is concluded that the systemic infusion of MSCs can alleviate ConA induced acute liver injury in mice.

[Effect of ronggan mixture on cell apoptosis in rats with chronic immune liver injury induced by concanavalin A]

OBJECTIVE

To explore the effects of Ronggan Mixture (RGM) on cell apoptosis by observing the expressions of apoptosis-related genes (Fasl and Bcl-2) in transgenic mice with chronic liver immune injury induced by concanavalin A (ConA).

METHODS

Seventy-four transgenic mice were divided into 6 groups, the model group, the normal group, and the treated groups treated respectively with biphenyldicarboxylate (DDB), oriental wormwood (OWW), Yinchenhao Decoction (YCHD) and RGM. Pathologic changes of liver tissue were observed by light microscopy, number of apoptotic cells were determined by TUNEL method, and expressions of apoptosis-related genes, Fasl and Bcl-2, in hepatic T lymphocyte were detected by flow cytometer.

RESULTS

Evident pathological changes of liver appeared in the model mice, showed severely destroyed structure of hepatic lobules. As compared with the model group, the changes of liver fibrosis and cell necrosis were much lessened in the RGM group and the YCHD group (P < 0.05). The protein expression of apoptotic gene Fasl and the apoptotic index in the model group were higher than those in the normal group (P < 0.05), but that of the apoptotic inhibiting gene, Bcl-2, in model mice was similar to that in normal mice. As compared with the model group, apoptosis index decreased (P < 0.01), levels of Fasl expression was lower and Bcl-2 expression was higher in the RGM group and the YCHD group (P < 0.05, P < 0.01), and the effect of the two was similar, but significantly superior to that of OWW and DDB (P < 0.05 or P < 0.01).

CONCLUSION

The Chinese compound, RGM and YCHD can not only relieve the hepatic pathological injury, but also reduce the cell apoptosis in chronic liver immune injury mice through regulating the expressions of Fasl and Bcl-2.

Baicalin protects mouse from Concanavalin A-induced liver injury through inhibition of cytokine production and hepatocyte apoptosis

BACKGROUND

Baicalin (BA) exhibits an anti-inflammatory effect in vivo and in vitro and is used to treat chronic hepatitis. However, the mechanism by which BA exerts the liver-protective effect remains largely unknown.

AIMS

The present study reports that BA inhibits cytokine production and hepatocyte apoptosis to protect mice from liver injury induced by concanavalin A (Con A), a T-cell-dependent liver injury model.

RESULTS

Con A injection of mice induced severe immune responses and extensive hepatocellular apoptosis within 24 h. Pretreatment of 200 or 100 mg/kg BA markedly reduced serum aminotransferase activities, protected hepatoycte apoptosis and reduced the increase of plasma cytokine levels, including tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and interleukin-6 (IL-6). Furthermore, BA pretreatment decreased tissue myeloperoxidase activity and lipid peroxidation, but increased the superoxide dismutase level. In vitro studies indicated that the beneficial effect of BA was associated with reduced cytokine production from lymphocytes and reduced TNF-alpha-induced hepatocyte apoptosis.

CONCLUSION

These results suggest that BA has therapeutic potential for T-cell-mediated liver injury.

Suppression of immune-mediated liver injury after vaccination with attenuated pathogenic cells

Cell vaccination via immunization with attenuated pathogenic cells is an effective preventive method that has been successfully applied in several animal models of inflammatory or autoimmune diseases. Concanavalin A (Con A)-induced hepatitis (CIH) is a commonly used experimental model to study immune-mediated liver injury. Multiple cell types including T lymphocytes, macrophages and neutrophils have been found to be involved in the pathogenesis of CIH. In this study, we used attenuated spleen lymphocytes or peripheral blood lymphocytes as vaccines to investigate whether they could induce protective immune responses to prevent mice from developing CIH. We found that mice receiving such vaccination before CIH induction developed much milder diseases, exhibited a lower level of alanine aminotransferase (ALT) released into their plasma and had less inflammatory lesions in their livers. Such CIH-suppression is dose- and frequency-dependent. The suppressive effect was associated with inhibition of several major inflammatory mediators, pro-inflammatory cytokines and chemokines.

[The protective role of adiponectin in Con A-induced mouse liver injury]

OBJECTIVE

To evaluate the role of adiponectin in regulating tumor necrosis factor alpha (TNF alpha) production and preventing fulminant autoimmunological damage of hepatocytes following concanavalin A (Con A) injection into mice.

METHODS

Three days after recombinant plasmids pAA-neo-mAd were injected into the mice via the tail veins, Con A was injected into the mice. Mice transfected with empty pAA-neo vector served as controls. The serum levels of alanine aminotransferase (ALT), TNF alpha and adiponectin were detected, and histological examination of livers was carried out at different time points after the Con A injection. All results were subjected to statistical analyses.

RESULTS

Histological examinations showed that the damage in livers of mice with high serum adiponectin levels was milder than that of the controls. The serum levels of ALT and TNF alpha were both lower than those of the controls (P less than 0.01, respectively). Statistical analyses showed the serum levels of ALT was negatively related to the levels of adiponectin in the sera (r=-0.5034).

CONCLUSION

Adiponectin is effective in protecting hepatocytes from Con A-induced immunological injury. The mechanism of this protective effect may be caused by inhibiting the synthesis and/or release of TNF alpha.

IL-10, regulatory T cells, and Kupffer cells mediate tolerance in concanavalin A-induced liver injury in mice

The liver appears to play an important role in immunological tolerance, for example, during allo-transplantation. We investigated tolerance mechanisms in the model of concanavalin A (ConA)-induced immune-mediated liver injury in mice. We found that a single injection of a sublethal ConA dose to C57BL/6 mice induced tolerance toward ConA-induced liver damage within 8 days. This tolerogenic state was characterized by suppression of the typical Th1 response in this model and increased IL-10 production. Tolerance induction was fully reversible in IL-10 -/- mice and after blockade of IL-10 responses by anti-IL10R antibody. Co-cultures of CD4+CD25+ regulatory T cells (T(reg)s) and CD4+CD25- responder cells revealed T(reg) from ConA-tolerant mice being more effective in suppressing polyclonal T cell responses than T(reg) from control mice. Moreover, T(reg) from tolerant but not from control mice were able to augment in vitro IL-10 expression. Depletion by anti-CD25 monoclonal antibody (MAb) indicated a functional role of T(reg)s in ConA tolerance in vivo. Cell depletion studies revealed T(reg)S and Kupffer cells (KC) to be crucial for IL-10 expression in ConA tolerance. Studies with CD1d -/- mice lacking natural killer T (NKT) cells disclosed these cells as irrelevant for the tolerogenic effect. Finally, cellular immune therapy with CD4+CD25+ cells prevented ConA-induced liver injury, with higher protection by Treg from ConA-tolerized mice.

CONCLUSION

The immunosuppressive cytokine IL-10 is crucial for tolerance induction in ConA hepatitis and is mainly expressed by CD4+CD25+ T(reg) and KC. Moreover, T(reg)s exhibit therapeutic potential against immune-mediated liver injury.

Lack of macrophage migration inhibitory factor protects mice against concanavalin A-induced liver injury

BACKGROUND

Macrophage migration inhibitory factor (MIF) is involved in inflammatory and immune-mediated diseases but the role of MIF in liver injury has not yet been elucidated.

METHODS

We investigated biochemically, histologically and immunologically the character of MIF in concanavalin A (Con A)-induced T-cell-mediated liver injury using MIF knockout (KO) mice and wild-type (WT) mice.

RESULTS

MIF KO mice showed significantly decreased serum alanine aminotransferase values and suppressed histological change with massive necrosis of the hepatic parenchymal cells and infiltration of inflammatory cells compared with their WT counterparts. This protection was not mediated by either tumor necrosis factor-alpha or interferon-gamma, which are critical mediators of Con A-induced liver injury, as their serum concentrations were shown to be similar in MIF KO and WT mice. On the other hand, a flow cytometric analysis demonstrated that the number of activated hepatic leukocytes decreased more in the MIF KO mice than in the WT mice.

CONCLUSIONS

A lack of MIF protected the mice from Con A-induced liver injury. Controlling the MIF activity may be a useful therapeutic strategy for treating such T-cell activation-associated liver diseases as autoimmune hepatitis and viral hepatitis.

Therapeutic administration of Y-40138, a multiple cytokine modulator, inhibits concanavalin A-induced hepatitis in mice

Concanavalin A-induced hepatitis is often used as a model of liver injury. In this model, plasma tumor necrosis factor-alpha (TNF-alpha) level increased in concanavalin A-injected mice. Prophylactic treatment with Y-40138, N-[1-(4-[4-(pyrimidin-2-yl)piperazin-1-yl]methyl phenyl)cyclopropyl] acetamide.HCl, significantly suppressed the increase in plasma TNF-alpha level. In this study, we compared the effect of Y-40138 with those of pentoxifylline and anti-TNF-alpha antibody on concanavalin A-induced hepatitis. Prophylactic treatment with pentoxifylline, anti-TNF-alpha antibody and Y-40138 reduced plasma alanine aminotransferase level. Therapeutic treatment with Y-40138 significantly reduced plasma alanine aminotransferase level, but pentoxifylline and anti-TNF-alpha antibody did not. Therapeutic treatment with Y-40138 significantly reduced plasma interferon-gamma (IFN-gamma) and monokine induced by interferon-gamma levels. From these results, Y-40138 may be expected as a new class of therapeutic drug for treatment of TNF-alpha, IFN-gamma and/or chemokine-related liver diseases such as alcoholic liver disease.

Sleep During Concanavalin-A-Induced Hepatitis and Peritonitis in Inbred Mice

STUDY OBJECTIVES

To assess the suitability of concanavalin-A-induced hepatitis as a model for investigating the relationships between hepatic disease and alterations in somnolence.

DESIGN

We characterized the sleep patterns of various strains of inbred mice undergoing ConA-induced inflammation.

SETTING

Southern Illinois University School of Medicine, Springfield, IL.

INTERVENTION

Intravenous or intraperitoneal administration of concanavalin-A.

PARTICIPANTS

Inbred mice.

MEASUREMENTS AND RESULTS

Intravenous and intraperitoneal administration of concanavalin-A both elicited strain-dependent changes in slow-wave sleep. ConA treatment also reduced spontaneous locomotor activity. ConA-induced changes in slow-wave sleep varied with dose, route of administration, and circadian period of administration. As compared with the other strains, C57BL/6J mice had lower serum concentrations of interferon-gamma at 8 hours after ConA administration.

CONCLUSIONS

These data provide the first demonstration that sleep enhancement and reduced locomotor activity accompany hepatic inflammation in mice.

[Anti-inflammatory and reparative effect of olipiphate]

The therapeutic effect of olipiphate was demonstrated for chronic inflammation of advanced arthritis and concanavalin A-related acute edema. The best systemic effect was obtained with 50 mg/kg, symptomatic--100 mg/kg. Skin wounds treated with 5% olipiphate (26 + 2) healed faster than those treated with 2% solcoseryl (30 + 0.8) or in control (33 + 0.6). It was shown histologically that the proliferative and antiphlogistic effect of olipiphate involved no scars.

High, but not low, molecular weight hyaluronan prevents T-cell-mediated liver injury by reducing proinflammatory cytokines in mice

BACKGROUND

The extracellular matrix component hyaluronan (HA) modulates the production of various cytokines and chemokines by activated inflammatory cells. In this study, we investigated whether exogenous administration of HA influences T-cell-mediated liver injury and cytokine production.

METHODS

Liver injury was induced by administration of concanavalin A (Con A) or D-galactosamine/lipopolysaccharide (GalN/LPS), and 0.05%-0.35% (v/v) HA (MW 250, 470, 780, 900, and 1200 kDa) was administered intravenously 18 h before Con A or GalN/LPS injection. Plasma ALT level was determined enzymatically and plasma cytokine levels were determined by ELISA.

RESULTS

The elevated plasma levels of ALT at 8 h after Con A and at 7 h after GalN/LPS injection were significantly decreased by pretreatment with high molecular weight HAs (780, 900, and 1200 kDa) but not low molecular weight HAs (250 and 470 kDa). High molecular weight HA (900 kDa) significantly reduced plasma tumor necrosis factor-alpha, interferon gamma, macrophage inflammatory protein 2, and interleukin 4 levels after Con A injection. However, this inhibitory effect on plasma cytokines was not observed with low molecular weight HA (250 kDa) pretreatment.

CONCLUSIONS

The present results suggest that high molecular weight but not low molecular weight HA prevents liver injury by reducing proinflammatory cytokines in a T-cell-mediated liver injury model. The extracellular matrix component hyaluronan (HA) modulates the production of various cytokines and chemokines by activated inflammatory cells. In this study, we investigated whether exogenous administration of HA influences T-cell-mediated liver injury and cytokine production.

Chronic alcohol consumption accelerates liver injury in T cell-mediated hepatitis: alcohol disregulation of NF-kappaB and STAT3 signaling pathways

Alcohol consumption is a major risk factor accelerating the progression of liver disease in patients with chronic hepatitis virus infection. However, the mechanism underlying the enhanced susceptibility of alcoholics to liver injury is not fully understood. Here, we demonstrate that chronic ethanol consumption increases the susceptibility of C57BL/6 mice to concanavalin A (Con A)-induced T cell-mediated hepatitis. Injection of a low dose of Con A (5 microg/g) causes severe liver damage in ethanol-fed mice as evidenced by a significant elevation of serum alanine aminotransaminase levels, massive necrosis, and infiltration of leukocytes but only slightly induces liver injury in control pair-fed mice. In ethanol-fed mice, the activation and cytotoxicity of natural killer T cells, cells that play key roles in Con A-induced T cell hepatitis, are not significantly enhanced relative to pair-fed mice. Moreover, Con A-induced activation of hepatic NF-kappaB is increased, whereas activation of STAT1 and STAT3 is attenuated in ethanol-fed mice. Consistent with this result, the expression of chemokines and adhesion molecules [such as ICAM-1, macrophage inflammatory protein (MIP)-1, MIP-2, and MCP-1] controlled by NF-kappaB is upregulated, whereas STAT1-controlled expression of chemokines (such as MIG and IP-10) is downregulated in ethanol-fed mice compared with pair-fed mice. In conclusion, chronic alcohol consumption accelerates T cell-mediated hepatitis via upregulation of the NF-kappaB signaling pathway and subsequently enhances expression of chemokines/adhesive molecules and recruitment of leukocytes into the liver. Downregulation of the antiapoptotic STAT3 signal may also contribute to alcohol potentiation of T cell hepatitis.

NSAID zaltoprofen improves the decrease in body weight in rodent sickness behavior models: proposed new applications of NSAIDs (Review)

In infectious diseases and during inflammation, anorexia, loss of body weight, malaise, fatigue and depression are induced. These symptoms are correctively called 'sickness behaviors', and the central actions of cytokines play a role in their induction. The loss of body weight in cancer cachexia is also a result of development of sickness behaviors. It has been reported that the administration of NSAID ibuprofen to patients with cancer cachexia improves the loss in body weight. We studied the effect of NSAID on the loss of body weight by using rodent sickness behavior models. We have reported that sickness behaviors such as anorexia, decrease in body weight, and loss of locomotor activity are induced in concanavalin A (Con A)-induced mouse hepatitis and carbon tetrachloride-induced rat hepatitis. Zaltoprofen is a non-steroidal anti-inflammatory drug (NSAID) causes potent inhibition of cyclooxygenase-2 with fewer side effects on the gastrointestinal tract. Zaltoprofen improves the loss in body weight in both Con A-treated mice and carbon tetrachloride-treated rats. These results suggest the possible application of zaltoprofen for the treatment of sickness behaviors including loss of body weight occurring in cancer cachexia.

NC-1500 prevents concanavalin A-induced mice hepatitis without affecting cytokine gene expression

NC-1500 is a dihydropyridine type calcium channel blocker. The effect of NC-1500 on mice concanavalin A-induced hepatitis was examined. Treatment of mice with concanavalin A (Con A) caused elevation of plasma transaminase. Pretreatment of mice with NC-1500 (3, 10 and 30 mg/kg, p.o.) prevented this Con A-induced elevation of plasma transaminase. Treatment of mice with Con A induced tumor necrosis factor-alpha (TNF-alpha) mRNA expression in the liver. However, NC-1500 (30 mg/kg, p.o.) did not affect this Con A-induced TNF-alpha mRNA expression in the liver. The present results showed that NC-1500 inhibited Con A-induced hepatitis without affecting TNF-alpha mRNA expression in the liver.

[Protective effect of bicyclol on concanavalin A-induced liver nuclear DNA injury in mice]

OBJECTIVE

To study the protective effect of bicyclol on concanavalin A (Con A) induced liver nuclear DNA injury in mice.

METHODS

Bicyclol was fed into the stomachs of 32 mice. Then Con A was injected into their caudal veins. Six, twelve, twenty-four, and forty-eight hours after the injection, 8 mice were killed at each time point and their blood and livers were taken to be tested. Serum alanine aminotransferase (ALT), and nuclear DNA fragmentation, DNA ladder, H2O2 level, and sensitivity of nuclear DNA to oxidative damage by CuSO4-ortho-phenanthrolin-vitamin C-H2O2 system in hepatocytes of mice were determined. The protective effect on damage of pure DNA by CuSO4-ortho-phenanthrolin-vitamin C-H2O2 system was determined in vitro too. Eight mice were injected with Con A only as normal controls. Nine mice were injected with Con A only as Con A controls.

RESULTS

In the experimental groups, six hours after the injection of Con A, the serum ALT level increased significantly (P < 0.05), reached the peak after 12 hours (P < 0.01), and then decreased. The liver nuclear DNA fragmentation increased 12 hours after injection of Con A in the Con A control group. However, the liver nuclear DNA fragmentation was significantly less in bicyclol groups (P < 0.05 and P < 0.01). The percentage of DNA ladder in the 150 mg/kg bicyclol group was 25%, significantly lower than that in Con A control group (100%). The H2O2 level in liver was significantly increased 12 hours after injection of Con A in the Con A control group, and remained normal in the 150 mg/kg bicyclol group. The Con A-induced decrease of sensitivity of liver nuclear DNA to damage by CuSO4-ortho-phenanthrolin-vitamin C-H2O2 system was counteracted by bicyclol injection.

CONCLUSION

Bicyclol is significantly effective in protecting liver from nuclear DNA injury of hepatocytes induced by Con A in mice.

Non-peptidic analogs of the cell adhesion motif RGD prevent experimental liver injury

In chronic viral hepatitis, autoimmune hepatitis, and some chronic cholestatic liver diseases, T lymphocytes serve as effector cells of the immunostimulatory processes. Cellular interactions of immune cells with extracellular matrix components are regulated primarily via the beta 1 subfamily of integrin receptors. The target epitope of several such integrin receptors is the Arg-Gly-Asp sequence, a cell adhesion motif shared by several matrix-associated adhesive glycoproteins. We review the use of synthetic non-peptidic analogs of RGD in the prevention of immune-mediated, concanavalin A-induced liver damage in mice and in inhibiting the development of liver cirrhosis in rats. The Con A-induced elevation of serum transaminases and tumor necrosis factor-alpha and the infiltration of liver tissue by inflammatory cells were inhibited by pretreatment of the mice with the synthetic RGD mimetics. In rats, the progression of thioacetamide-induced liver cirrhosis was markedly inhibited by the co-administration of the RGD mimetic SF-6,5. The compounds described here may be examined therapeutically for pathological conditions in the liver, manifested as necro-inflammation and fibrosis.

Glycyrrhizin protects mice from concanavalin A-induced hepatitis without affecting cytokine expression

The administration of concanavalin A (Con A) to mice induces cytokine-dependent hepatitis. In the present study, the effect of glycyrrhizin on Con A-induced hepatitis was examined. Treatment of mice with Con A (0.2 mg/mouse, i.v.) induced elevation of the plasma transaminase activities at 24 h. Mice were treated with glycyrrhizin (100, 200 and 400 mg/kg, i.p.), and glycyrrhizin at the doses of 200 and 400 mg/kg inhibited the Con A-induced elevation of the plasma transaminase activities. At 1 h after Con A treatment, interferon-gamma, tumor necrosis factor-alpha, interleukin-2 and interleukin-6 proteins were released into the plasma. Although treatment with glycyrrhizin at 200 mg/kg inhibited Con A-induced hepatitis, it did not affect the release of any of these Con A-induced cytokines into the plasma. The present results clearly show that glycyrrhizin inhibited Con A-induced hepatitis without affecting cytokine expression.

Effects of concanavalin A on protein-C activity

Concanavalin A interacts specifically with the oligosaccharides from protein-C and modifies its anticoagulant activity. The lectin activates the protein-C activity in a dose dependent manner as demonstrated by in vitro and in vivo assays. Concanavalin A at low concentration (0.1 to 2 microg/mL) induces an increase on the catalytic activity of protein-C; at higher concentrations (5 to 20 microg/mL), the catalytic activity returns to the baseline. The effect of concanavalin A was prevented by incubating the protein-C with alpha-methyl-mannoside or by treating the purified protein-C with alpha-mannosidase; furthermore, cleavage of mannosidic residues diminishes its catalytic activity. Our results indicate that the oligomannosidic portion of protein-C participates in the regulation of the catalytic activity of this protein.

Interferon gamma plays a critical role in T cell-dependent liver injury in mice initiated by concanavalin A

BACKGROUND & AIMS

T cell-dependent liver injury involving endogenous tumor necrosis factor (TNF) alpha can be induced by either concanavalin A in naive mice or by activating anti-CD3 antibody or staphylococcal enterotoxin B in D-galactosamine-sensitized mice. In this study, the role of interferon gamma (IFN-gamma) in these T-cell models was addressed.

METHODS

Mice were pretreated with a neutralizing anti-mouse IFN-gamma antiserum before injection of T cell-activating agents. Plasma cytokine and transaminase levels were determined. Apoptotic cell death was assessed by hepatic DNA fragmentation.

RESULTS

Anti-IFN-gamma antiserum significantly protected mice from concanavalin A-induced liver injury. Circulating IFN-gamma was completely suppressed, and TNF was reduced by 50%. Recombinant TNF-alpha administered to mice treated with concanavalin A and anti-IFN-gamma antiserum failed to initiate liver injury. Similar results were obtained with recombinant IFN-gamma in concanavalin A-challenged mice under the condition of TNF neutralization. Neither hepatic DNA fragmentation nor release of transaminases was inhibited by anti-IFN-gamma antiserum when liver injury was induced by staphylococcal enterotoxin B or anti-CD3 antibody in D-galactosamine-sensitized mice.

CONCLUSIONS

Both TNF as well as IFN-gamma are critical mediators of liver injury in concanavalin A-treated mice, whereas hepatic DNA fragmentation and liver failure in the D-galactosamine models depend only on TNF.

Some characteristics of inflammation induced by muramyl dipeptide, endotoxin, and concanavalin A

Inflammatory reactions induced by muramyl dipeptide (MDP), endotoxin, and concanavalin A (Con A) were examined in the skin of rabbits. The neutrophil influx induced by MDP peaked at 2 h and declined to a low level by 4 h, thus resembling the response induced by endotoxin. MDP and endotoxin exhibited homologous desensitization when extant lesions were restimulated at 6 h. These agents did not, however, induce heterologous desensitization. Con A induced a biphasic influx of neutrophils into inflammatory lesions with peaks at 2 h and 12 h. Neither the first nor second peak exhibited desensitization to homologous restimulation; however, the cell influx in restimulated lesions assumed a monophasic character peaking at 3 h. Con A lesions were not desensitized to restimulation with MDP or endotoxin. The results suggest that these chemotaxinogens rely on different endogenous mediators to induce an inflammatory response. The protracted second period of neutrophil infiltration of Con A-induced lesions and the failure of desensitization of this response to develop suggest that the mediator of Con A-induced inflammation may play an important role in the sustained recruitment of neutrophils in some inflammatory diseases.

Concanavalin a: modification of kidney graft immunogenicity in a double transplant model

This study determines the effectiveness of flush graft pretreatment with concanavalin A (Con A) in minimally immunosuppressed recipients receiving double kidney transplantation. Significant prolongation of survival was seen when both kidneys from the same unrelated donor were treated with Con A, when both kidneys from different unrelated donors were treated with Con A, or when the allogeneic kidney was treated with Con A, and the syngeneic kidney was untreated. There was no significant prolongation in kidney allograft survival when one of the two allogeneic kidneys was treated with Con A, whether they came from the same, or different donors. If only the syngeneic kidney was treated with Con A and no treatment was given to the allogeneic kidney, also no prolongation of survival was observed. Thus, this study fully agrees with previous data indicating that Con A is not acting by systemic immunosuppression, but by local changes that modify the kidney immunogenicity. The theoretical implications associated with the prolongation of graft survival after flush pretreatment with Con A are activation of suppressor T cells, enhancement, physico-chemical modifications of the cell membrane and/or others.

Mucotractive effect of lectin

The jackbean lectin concanavalin A caused hypersecretion of mucus in the human nose and the rat jejunum, and histology of the latter demonstrated increased emptying of goblet cells. This "mucotractive" effect has implications for the fibre hypothesis and might be therapeutically useful in patients with cystic fibrosis.

The immunosuppressive effect of concanavalin A in monkeys

These studies were performed to evaluate the immunosuppressive effect of concanavalin A (ConA) in monkeys. Bonnet monkeys (Macaca radiata) weighing between 2.5-3.5 kg were used. Following the exchange of full thickness skin allografts in randomly selected animals, gross and histopathological studies of the rejection reaction were performed. Gross observations showed the allograft reaction in control animals to be a well defined phenomenon occurring at 9.0 +/- 0.7 days. In contrast the rejection process in animals that received i.v. ConA was a poorly defined prolonged process occurring at 14.8 +/- 3.9 days (single 75-mg dose of ConA), and 19.0 +/- 2.2 days (75 mg 1 day before and 25 mg 3 days after grafting). In monkeys that received the double dose schedule of ConA, histopathological studies showed distinct retardation of the rejection reaction with reduced lymphocytic infiltration of the graft-host junction. Control grafts showed almost complete rejection in 7-9 days while allografts on ConA-treated animals showed corresponding degrees of destruction only by the 15th day. These studies indicate that ConA does have an immunosuppressive effect in vivo in monkeys. The local and systemic toxic effects of ConA encountered in these animals have been reported and its haematological effects in vivo briefly described.

Immunosuppressive activity of concanavalin A

Daily intraperitoneal doses of concanavalin A (Con A) produced a dose-related inhibition of adjuvant-induced arthritis in rats. Con A was also effective on established arthritis, markedly relieving the disease after only three doses. The inhibitory effect of Con A was neutralised by pre-incubation with ovalbumin, although this treatment did not modify the delayed phlogistic action of Con A in rat paws.