Concanavalin-A stimulates IL-17 and nitric oxide production and induces macrophage polarization and resistance to Trypanosoma cruzi infection

Ursolic acid-rich extract presents trypanocidal action in vitro but worsens mice under experimental acute Chagas disease

Chagas disease is a neglected tropical disease with only two drugs available for treatment and the plant Cecropia pachystachya has several compounds with antimicrobial and anti-inflammatory activities. This study aimed to evaluate a supercritical extract from C. pachystachya leaves in vitro and in vivo against Trypanosoma cruzi. A supercritical CO2 extraction was used to obtain the extract (CPE). Cytotoxicity and immunostimulation ability were evaluated in macrophages, and the in vitro trypanocidal activity was evaluated against epimastigotes and trypomastigotes forms. In vivo tests were done by infecting BALB/c mice with blood trypomastigotes forms and treating animals orally with CPE for 10 days. The parasitemia, survival rate, weight, cytokines and nitric oxide dosage were evaluated. CPE demonstrated an effect on the epi and trypomastigotes forms of the parasite (IC50 17.90 ± 1.2 μg/mL; LC50 26.73 ± 1.2 μg/mL) and no changes in macrophages viability, resulting in a selectivity index similar to the reference drug. CPE-treated animals had a worsening compared to non-treated, demonstrated by higher parasitemia and lower survival rate. This result was attributed to the anti-inflammatory effect of CPE, demonstrated by the higher IL-10 and IL-4 values observed in the treated mice compared to the control ones. CPE demonstrated a trypanocidal effect in vitro and a worsening in the in vivo infection due to its anti-inflammatory activity.

Celastrol pretreatment attenuates concanavalin A-induced hepatitis in mice by suppressing interleukin-6/STAT3-interleukin-17 signaling

BACKGROUND AND AIM

Celastrol is extracted from Tripterygium wilfordii Hook F. It has been reported to have protective effects against various liver diseases and immune regulation of autoimmune diseases. However, little is known about whether celastrol protects against immune-mediated hepatitis. This study aimed to investigate the effect of celastrol on liver injury induced by concanavalin A (ConA) and the potential mechanisms.

METHODS

Intravenous administration of ConA was applied to induce acute liver injury in mice with or without pretreatment of celastrol. The effects of celastrol on ConA-induced liver injury were further demonstrated by biochemical and histopathological assessments, immunoblotting, and flow cytometry analysis.

RESULTS

Both biochemical and histopathological observations showed that pretreatment of celastrol significantly ameliorated liver injury induced by ConA. Moreover, the hepatocyte apoptosis and inflammatory responses induced by ConA were also improved in celastrol-pretreated mice. Further studies revealed that these improvements were characterized as the celastrol-mediated suppression of total interleukin (IL)-17 from liver mononuclear cells in ConA-treated mice. Flow cytometry analysis suggested that celastrol specifically decreased IL-17 production by CD4⁺ T cells but not by CD8⁺ T cells. Fundamentally, pretreatment with celastrol inhibited both the IL-6 produced by F4/80⁺ macrophages and the IL-6 receptor on Th17 cells in the liver, which further led to the downregulated activation of STAT3, thus accounting for blocked Th17 signaling.

CONCLUSIONS

Celastrol may exhibit immune regulatory effects by regulating IL-6/STAT3-IL-17 signaling in ConA-induced hepatitis, which suggested new potentials for celastrol to be applied in treating immune-mediated liver diseases.

CP-25 exerts a protective effect against ConA-induced hepatitis via regulating inflammation and immune response

Hepatitis is a complex multifactorial pathological disorder, which can eventually lead to liver failure and even potentially be life threatening. Paeoniflorin-6′-O-benzene sulfonate (CP-25) has proven to have critical anti-inflammatory effects in arthritis. However, the effects of CP-25 in the pathogenesis of hepatitis remains unclear. In this experiment, mice were intragastrically administered with CP-25 (25, 50 and 100 mg/kg), and then ConA (25 mg/kg) was intravenous injected to establish hepatitis model in vivo. CP-25 administration attenuated liver damage and decreased ALT and AST activities in mice with hepatitis. Besides, CP-25 modulated immune responses including down-regulated the proportions of activated CD4+, activated CD8+ T cells, and ratio of Th1/Th2 in ConA-injected mice. Furthermore, ConA-mediated production of reactive oxygen species (ROS), release of inflammatory cytokines including IFN-γ, TNF-α, activation of MAPK pathways and nuclear translocation of nuclear factor-kappaB (NF-κB) were significantly decreased in CP-25 administrated mice. In ConA-stimulated RAW264.7 cells, CP-25 suppressed inflammatory cytokines secretion and reduced ROS level, which were consistent with animal experiments. Otherwise, the data showed that CP-25 restrained phosphorylation of ERK, JNK and p38 MAPK pathways influenced by ROS, accompanied with inhibiting NF-κB nuclear translocation. In conclusion, our findings indicated that CP-25 protected against ConA-induced hepatitis may through modulating immune responses and attenuating ROS-mediated inflammation via the MAPK/NF-κB signaling pathway.

Effects of Metabolism on Macrophage Polarization Under Different Disease Backgrounds

Macrophages are versatile immune cells associated with various diseases, and their phenotypes and functions change on the basis of the surrounding environments. Reprogramming of metabolism is required for the proper polarization of macrophages. This review will focus on basic metabolic pathways, the effects of key enzymes and specific products, relationships between cellular metabolism and macrophage polarization in different diseases and the potential prospect of therapy targeted key metabolic enzymes. In particular, the types and characteristics of macrophages at the maternal-fetal interface and their effects on a successful conception will be discussed.

Characterisation of Macrophage Polarisation in Mice Infected with Ninoa Strain of Trypanosoma cruzi

Macrophages (MΦ) play a key role in the development of the protective immune response against Trypanosoma cruzi infection. To determine the role of MΦ subtypes M1 and M2 in the development of immunity against the Mexican strain of T. cruzi (Ninoa strain), we have analysed in a time course the infection and characterised the M1 and M2 subtypes in two mouse models, BALB/c and C57BL/6. After infection, BALB/c mice developed an increased blood parasite load and the parasites were cleared from the blood one week later than in C57BL/6 mice. However, similar cellular infiltrate and cardiac alterations were observed between BALB/c and C57BL/6 mice. At 36 days, the T. cruzi infection differentially modulated the expression of immune cells, and both the BALB/c and C57BL/6 mice significantly reduced TCD4+ cells. However, BALB/c mice produced significantly more TCD8+ than C57BL/6 mice in the spleen and lymph nodes. Furthermore, BALB/c mice produce significantly more MΦ in the spleen, while C57BL/6 produce similar levels to uninfected mice. The M1 MΦ ratio increased significantly at 3-5 days post-infection (dpi), but then decreased slightly. On the contrary, the M2 MΦ were low at the beginning of the infection, but the proportion of M1 and M2 MΦ at 36 dpi was similar. Importantly, the MΦ subtypes M2c and M2d significantly increased the induction of tissue repair by the end of the acute phase of the infection. These results indicate that the Ninoa strain has developed strategies to modulate the immune response, with fine differences depending on the genetic background of the host.

Interleukin-9 in Immunopathology of Trypanosoma cruzi Experimental Infection

Chagas’ disease is a parasitosis caused by Trypanosoma cruzi, which affects approximately 8 million people worldwide. The balance between pro- and anti-inflammatory cytokines produced during immunological responses contributes to disease prognosis and progression. Parasite tissue persistence can induce chronic inflammatory stimuli, which can cause long-term tissue injury and fibrosis. Chronic Chagas’ patients exhibit increased levels of interleukin (IL)-9, an important cytokine in the regulation of inflammatory and fibrogenic processes. Data on the role of IL-9 in other pathologies are sometimes contradictory, and few studies have explored this cytokine’s influence in Chagas’ disease pathology. Hence, the aim of this study was to evaluate the role of IL-9 in the progression of T. cruzi infection in vivo and in vitro. In vitro infection demonstrated that IL-9 reduced the number of infected cells and decreased the multiplication of intracellular amastigotes in both C2C12 myoblasts and bone marrow-derived macrophages. In myoblasts, the increased production of nitric oxide (NO) was essential for reduced parasite multiplication, whereas macrophage responses resulted in increased IL-6 and reduced TGF-β levels, indicating that parasite growth restriction mechanisms induced by IL-9 were cell-type specific. Experimental infection of BALB/c mice with T. cruzi trypomastigotes of the Y strain implicated a major role of IL-9 during the chronic phase, as increased Th9 and Tc9 cells were detected among splenocytes; higher levels of IL-9 in these cell populations and increased cardiac IL-9 levels were detected compared to those of uninfected mice. Moreover, rIL9 treatment decreased serum IL-12, IL-6, and IL-10 levels and cardiac TNF-α levels, possibly attempting to control the inflammatory response. IL-9 neutralization increased cardiac fibrosis, synthesis of collagens I and III, and mastocyte recruitment in BALB/c heart tissue during the chronic phase. In conclusion, our data showed that IL-9 reduced the invasion and multiplication of T. cruzi in vitro, in both myoblasts and macrophages, favoring disease control through cell-specific mechanisms. In vivo, IL-9 was elevated during experimental chronic infection in BALB/c mice, and this cytokine played a protective role in the immunopathological response during this phase by controlling cardiac fibrosis and proinflammatory cytokine production.