Immunomodulation of liver injury by Ascaris suum extract in an experimental model of autoimmune hepatitis

Concanavalin A-induced autoimmune hepatitis model in mice: Mechanisms and future outlook

The concanavalin A (Con A)-induced liver injury mouse model is a typical animal model focusing on T cell-dependent hepatic damage in the field of autoimmune hepatitis (AIH). However, the underlying mechanism of hepatic dysfunction due to cell activation or signaling pathways triggered by Con A has not been fully clarified. Therefore, the controversy on this model remains in the academic community. In this article, we first summarized the merit and demerit of this contentious model from the perspectives of cell dysfunction, microcirculation disturbance, involved signaling pathways, as well as the properties of Con A. Then, we summed up the scientific implications of the model in elucidating the pathogenesis of AIH, and the shortcomings of this model were also summarized to elucidate the pathogenesis and application prospect of this classical liver injury mouse model in the study of AIH.

Synthesis and biological evaluation of novel schisanhenol derivatives as potential hepatoprotective agents

Twenty-one new schisanhenol derivatives were synthesized, and their hepatoprotective effects against liver injury induced by concanavalin A (Con A) were evaluated in vitro using an MTT assay. The data indicated that most derivatives exhibited equivalent or better protective activity than the positive control (dimethyl dicarboxylate biphenyl, DDB) under the same conditions. Among them, compound 1b showed the most potent hepatoprotective activity against Con A-induced immunological injury. Mechanistic studies in vitro revealed that 1b inhibited cell apoptosis and inflammatory responses caused by Con A treatment via IL-6/JAK2/STAT3 signaling pathway. Consistently, it also exhibited significant hepatoprotective activity in mice with Con A-induced immunological liver injury. These results clearly indicated that 1b might be a highly potent hepatoprotective agent targeting IL-6/STAT3 signaling pathway.

Extract from Ascaris suum and N-acetyl-L-cysteine induces an immunosuppressant effect in model of autoimmune hepatitis

BACKGROUND

Extract of adult Ascaris suum (ASC) worms attenuated the liver damage in experimental autoimmune hepatitis (EAH) with induction of Th2 immune response, but fibrosis occurred. N-acetyl-L-cysteine (NAC) has protective effects against liver fibrosis.

OBJECTIVES

Evaluate the association ASC + NAC on the T- and B-cell activation, inflammation and fibrogenic markers in the liver in EAH.

METHODS

Experimental autoimmune hepatitis was induced intravenously with concanavalin A in BALB/c mice. EAH + ASC+NAC group received NAC and ASC; EAH + ASC group received ASC; EAH group received PBS. Doubly labelled CD4⁺ T (CD28, CTLA-4, CD40L or IL-10) and CD45R⁺ B lymphocytes (IL-10) and CD4⁺ CD25⁺ FoxP3⁺ cells were evaluated, along with gene expression of Col1a1, α-SMA, Fizz1, Arg1 and PPAR-γ and histomorphometry.

RESULTS

Experimental autoimmune hepatitis group showed high frequency of CD28⁺ and CD40L⁺  T lymphocytes, but not the EAH + ASC group. In relation to EAH group, the Fizz1 expression was lower in both groups treated, but Arg1 expression was lower in only EAH + ASC+NAC group. In the EAH + ASC+NAC group, there were higher frequencies of CD4⁺ IL-10⁺ and CD4⁺ CD25⁺ FoxP3⁺ cells, but not CD45R⁺ IL-10⁺ , along with mitigated inflammation and collagen production.

CONCLUSIONS

Ascaris suum favoured immunosuppression in EAH limiting the T cells activation. However, association ASC and NAC was necessary for attenuating the inflammatory process and collagen production.

Extract of Ascaris suum induces TGF-β and early production of IgG1 in experimental autoimmune hepatitis

In experimental autoimmune hepatitis (EAH) of Th1 profile, an extract of adult Ascaris suum worms (ASC) was previously found to deviate the immune response to a Th2/IL-10 pattern. Here, the effects of treatment with ASC on production of TGF-β and the anti-Ascaris isotypes IgG1 and IgG2a in EAH were evaluated. EAH was induced in BALB/c mice, intravenously with concanavalin A. Two hours later, these animals received ASC (EAH+ASC group) or PBS vehicle (EAH group). IgG1 and IgG2a were evaluated 8 h, 24 h and 7 d after induction. TGF-β was measured in a splenocyte culture at this last time. The isotype levels in the EAH group were low throughout the kinetics. In the EAH+ASC group, there was significant production of IgG1 at 24 h and 7 d, but of IgG2a only at 7 d. There was statistically greater production of TGF-β in the EAH+ASC group. The higher levels of IgG1 and TGF-β in this group suggest that an additional Th1 response control route exists in EAH, which needs to be investigated.

Whipworm and roundworm infections

Trichuriasis and ascariasis are neglected tropical diseases caused by the gastrointestinal dwelling nematodes Trichuris trichiura (a whipworm) and Ascaris lumbricoides (a roundworm), respectively. Both parasites are staggeringly prevalent, particularly in tropical and subtropical areas, and are associated with substantial morbidity. Infection is initiated by ingestion of infective eggs, which hatch in the intestine. Thereafter, T. trichiura larvae moult within intestinal epithelial cells, with adult worms embedded in a partially intracellular niche in the large intestine, whereas A. lumbricoides larvae penetrate the gut mucosa and migrate through the liver and lungs before returning to the lumen of the small intestine, where adult worms dwell. Both species elicit type 2 anti-parasite immunity. Diagnosis is typically based on clinical presentation (gastrointestinal symptoms and inflammation) and the detection of eggs or parasite DNA in the faeces. Prevention and treatment strategies rely on periodic mass drug administration (generally with albendazole or mebendazole) to at-risk populations and improvements in water, sanitation and hygiene. The effectiveness of drug treatment is very high for A. lumbricoides infections, whereas cure rates for T. trichiura infections are low. Novel anthelminthic drugs are needed, together with vaccine development and tools for diagnosis and assessment of parasite control in the field.

Critical roles of conventional dendritic cells in autoimmune hepatitis via autophagy regulation

Autoimmune hepatitis (AIH) is a necroinflammatory disease associated with interactive cell populations of the innate and adaptive immune systems. The contribution of conventional dendritic cells (cDCs) to AIH and the underlying mechanism remain poorly understood. The frequency of peripheral mature cDCs increased in AIH patients and was positively correlated with disease severity. In experimental autoimmune hepatitis (EAH), hepatic accumulation of mature cDCs was observed, along with an increase in the periphery. Sequentially, bone marrow-derived dendritic cells (BMDC) from EAH mice exhibit more proinflammatory function than those from control mice. In vitro, ConA treatment promotes the maturation of BMDCs, which are characterized by higher expression of MHC-II, costimulatory molecules and cytokine secretion. ConA also induced the expression of autophagy-related protein and the formation of autophagosomes in DCs. To further investigate whether ConA-induced DC activation is associated with autophagy, we utilized 3-MA and bafilomycin A1 to block autophagy flux and accessed the maturation and function of DCs induced by ConA. 3-MA and bafilomycin A1 inhibited the mature status and proinflammatory cytokine secretion and diminished the proliferation and differentiation of CD4+ T cells when ConA-induced BMDCs cocultured CD4+ T cells. We demonstrated that cDCs contribute to the pathogenesis of AIH through excessive maturation. Aberrant autophagy flux plays a vital role in the immunogenic maturation of cDCs in AIH, and tolerogenic cDCs by inhibition of autophagy flux can be exploited as a new therapeutic approach for AIH.

Ascaris lumbricoides Cystatin Prevents Development of Allergic Airway Inflammation in a Mouse Model

Severe helminth infections are negatively associated to allergic diseases like asthma; therefore, the immunomodulatory properties of parasite-derived components have been analyzed, raising the possibility of their use as anti-inflammatory molecules. We evaluated the immunomodulatory properties of Ascaris lumbricoides recombinant cysteine protease inhibitor (rAl-CPI) in a mouse model of allergic airway inflammation induced by the house dust mite (HDM) Blomia tropicalis and its effects on human monocyte-derived dendritic cells (HmoDCs). The B. tropicalis sensitized/challenged mice developed extensive cellular airway inflammatory response, which was significantly reduced upon treatment with rAl-CPI prior to B. tropicalis sensitization, affecting particularly the perivascular/peribronchial infiltrate cells, eosinophils/neutrophils, and goblet cells. A significant decrease of Th2 cytokines, total, and specific IgE antibodies was observed in rAl-CPI treated mice. The antibody response was biased to IgG, mainly IgG2a. Administration of rAl-CPI-alone and rAl-CPI before mite sensitization were associated with a significant increase of regulatory T cells (Tregs) in spleen and elevated IL-10 levels in BAL and splenocytes culture supernatants, which was partially affected by anti-IL10 receptor use. In vitro, rAl-CPI showed a modulatory effect on HmoDCs, lowering the expression of HLA-DR, CD83, and CD86, while inducing IL-10 and IL-6 production. This suggests an inhibition of HmoDC maturation and a possible link with the inhibition of the allergic response observed in the murine model.

Protective effects of Punica granatum (pomegranate) peel extract on concanavalin A-induced autoimmune hepatitis in mice

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease of an unknown etiology, glucocorticoid therapy is currently recognized as an effective treatment for AIH, but conventional application and patient compliance are both hindered by its side effects. The exploration of the AIH pathogenesis and the searching for the new candidate drugs that exert potential activity and low toxicity are urgently needed. Pomegranate peel extract (PoPx) is a natural extract of Punica granatum and has been reported to have anti-inflammatory and antioxidative properties. The present study aimed to clarify the effect of PoPx on the concanavalin A (ConA)-induced autoimmune hepatitis in a mouse model that is well established at 12h after tail vein injection with a dose of 20 mg/kg of ConA. C57BL/6 female mice were pretreated with PoPx (250 mg/kg, once daily for 3 days) followed by a ConA challenge. Pretreatment with PoPx significantly alleviated ConA-induced liver injury by down-regulating the levels of plasma alanine transaminase (ALT), aspartate transaminase (AST) and cytokine, including TNF-α, interferon (IFN) -γ and interleukin (IL)-6. Moreover, liver hematoxylin and eosin (H&E) staining displayed a lighter inflammatory infiltration around the portal area in the PoPx-pretreated mice. In addition, the flow cytometry (FCM) data showed that the immune response in the liver was died down in the PoPx-pretreated condition. Specially, pretreatment with PoPx reduced the infiltration of activated CD4+ and CD8+ T cells in the liver. Taken together, these findings contributed to a better understanding of the actions of PoPx against acute AIH and indicated that PoPx might be a potential compound in treating T cell-mediated autoimmune liver injury.

Helminth therapy for organic diseases?

Autoimmune and chronic inflammatory organic diseases represent a "postindustrial revolution epidemics," and their frequency has increased dramatically in the last century. Today, it is assumed that the increase in hygiene standards reduced the interactions with helminth parasites that coevolved with the immune system and are crucial for its proper functioning. Several helminths have been proposed and tested in the search of the ideal therapeutic. In this review, the authors summarize the translational and clinical studies and review the caveats and possible solutions for the optimization of helminth therapies.