Curcumin as a Stabilizer of Macrophage Polarization during Plasmodium Infection.

Malaria is a parasitic infection responsible for high morbidity and mortality rates worldwide. During the disease, phagocytosis of infected red blood cells by the macrophages induces the production of reactive oxygen (ROS) and nitrogen species (RNS), culminating in parasite death. Curcumin (CUR) is a bioactive compound that has been demonstrated to reduce the production of pro-inflammatory cytokines and chemokines produced by macrophages but to reduce parasitemia in infected mice. Hence, the main purpose of this study is to investigate whether curcumin may interfere with macrophage function and polarization after Plasmodium berghei infection in vitro. In our findings, non-polarized macrophage (M0), classically activated (M1), and alternatively activated (M2) phenotypes showed significantly increased phagocytosis of infected red blood cells (iRBCs) when compared to phagocytosis of uninfected red blood cells (RBCs) 3 h after infection. After 24 h, M1 macrophages exposed to RBCs + CUR showed greater elimination capacity when compared to macrophages exposed to iRBCs + CUR, suggesting the interference of curcumin with the microbicidal activity. Additionally, curcumin increased the phagocytic activity of macrophages when used in non-inflammatory conditions (M0) and reduced the inducible nitric oxide synthase (iNOS) and arginase activities in all macrophage phenotypes infected (M0, M1, and M2), suggesting interference in arginine availability by curcumin and balance promotion in macrophage polarization in neutral phenotype (M0). These results support the view of curcumin treatment in malaria as an adjuvant, promoting a balance between pro- and anti-inflammatory responses for a better clinical outcome.

Leishmania (Viannia) braziliensis amastigotes from patients with mucosal leishmaniasis have increased ability to disseminate and are controlled by nitric oxide at the early stage of murine infection.

Mucosal leishmaniasis (ML) caused by Leishmania (Vianna) braziliensis usually appears after the healing of the primary lesion when amastigotes disseminate from the infection site to the mucosal area. Here, we investigated murine infection with amastigotes obtained from patients with ML or localized cutaneous leishmaniasis (LCL). Amastigotes were used to infect wild type, IFN-γ KO and inducible nitric oxide synthase (iNOS) KO mice. Amastigotes from patients with LCL induced lesions that appeared earlier in IFN-γ KO than parasites from ML. The lesion after infection with ML appeared early in iNOS KO than in IFN-γ KO mice and in iNOS KO mice parasites from ML and LCL cause similar lesions at the initial phase of infection, while parasites from ML induced greater lesions than the ones from LCL at the late phase. A greater number of parasites were observed in spleen of IFN-γ KO and iNOS KO mice infected with amastigotes from patients with ML than those with LCL. Parasites from ML infect a lower percentage of macrophages and are killed independent on IFN-γ and dependent on NO. The data suggest that amastigotes responsible for mucosal lesion in humans develop slowly on the initial phase of infection due to high susceptibility to NO and they have an increased ability to disseminate.

Electroacupuncture at the ST36 acupoint increases interleukin-4 responsiveness in macrophages, generation of alternatively activated macrophages and susceptibility to Leishmania major infection.

BACKGROUND: Electroacupuncture (EA) has been used to treat inflammatory diseases. Alternatively activated macrophages (AAMo) stimulated by cytokines such as interleukin (IL)-4, IL-10 and IL-13 are anti-inflammatory and mildly microbicidal. This study aimed to evaluate whether EA at the Zusanli acupoint (ST36) would change the profile of healthy murine macrophages, particularly the generation of AAMo and susceptibility to Leishmania major infection. METHODS: BALB/c mice were treated with EA (15/30 Hz) at the ST36 acupoint for 20 min/d for 5 d. After the final EA session, the mice were euthanized and their peritoneal cells were harvested and counted for determination of arginase activity, nitric oxide (NO) production and microbicidal activity after culture in the presence or absence of IL-4, interferon-γ (IFNγ) or lipopolysaccharide (LPS) or both IFNγ and LPS. Twelve mice were infected with L. major promastigotes into the footpads after the final EA session and the infection course was monitored. RESULTS: Peritoneal cells freshly obtained from EA-treated mice had similar arginase and microbicidal activities to cells from sham-treated mice. After culture with IL-4, cells from EA-treated mice exhibited significant increases in the arginase activity (sham: 58 ± 11.3 vs. EA: 80.7 ± 4.6%, P = 0.025) and number of parasites/infected cell (sham: 2.5 ± 0.4 vs. EA: 4.3 ± 0.8 cells, P = 0.007). The NO production was lower in cells from EA-treated mice cultured in the presence of a combination of IFNγ and LPS (sham: 31.6 ± 6.5 vs. EA: 22.3 ± 2.1 µM, P = 0.025). The lesion size in mice infected with L. major promastigotes was larger in EA-treated mice (sham: 3.26 ± 0.29 vs. EA: 2.23 ± 0.4 mm, P = 0.039). CONCLUSION: EA at the ST36 acupoint increases IL-4 responsiveness in macrophages, Generation of AAMo and susceptibility to L. major infection.