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.

Effect of HeNe laser irradiation on extracellular matrix deposition and expression of cytokines and chemokines in paracoccidioidomycotic lesions.

Paracoccidioidomycosis is the most prevalent human mycosis in Latin America. Cutaneous lesions are extremely painful and sensitive, and current treatment with antifungal drugs is lengthy and may cause side effects to patients. In this perspective, the helium-neon (HeNe) laser emerges as a novel therapy form due to its ability to heal wounds without changing cell function. In this work, we evaluate the effects of HeNe laser irradiation on extracellular matrix deposition and expression of cytokines and chemokines in cutaneous lesions caused by experimental infection of Balb/c mice. Our results showed decreased levels of pro-inflammatory interleukin (IL)-17 and tumor necrosis factor-alpha, and of anti-inflammatory IL-10 cytokines in lesions exposed to HeNe laser irradiation. Chemokines CCL3 and CXCL10 showed decreased levels in laser-treated lesions, but no significant difference was observed in relation to CCL5 expression. We also detected decreased density of fibronectin and laminin in HeNe laser-treated lesions. Data presented herein support the validity of our previous results suggesting positive effects of HeNe laser in accelerating wound healing in this experimental model. We believe that HeNe laser is a new nonharmful strategy that may be used as adjuvant and/or alternative therapy for improving treatment of paracoccidioidomycotic lesions.

Thymic microenvironmental alterations in experimentally induced diabetes.

Little is known about the immunologic consequences from endocrine changes observed in diabetes. Since a preserved thymic microenvironment is of critical importance for the T cell development and maturation, we have examined the thymus from alloxan-diabetic mice. An intense thymic atrophy accompanied by changes in histological pattern and in thymocyte subpopulations were observed in diabetic mice. Laminin and fibronectin, which are closely associated with thymocytes maturation, were evaluated, but, only laminin presented an altered distribution and density in thymuses from diabetes group. the expression of fibronectin and laminin receptors was found to be decreased in diabetic mice. There was also intense decrease in the expression of two important chemokines for thymus, CCL25 and CXCL12, and in the CCR9 (CCL25 receptor), but the expression of CXCR4 (CXCL12 receptor) did not drop on cells. However, no significant difference was observed in the in vitro thymocytes migratory capacity from diabetic mice. The results show significant alterations in thymus microenvironment in diabetes and offer insights for studies involving endocrine influences on lymphatic organs and T cell maturation.

Changes in cell migration-related molecules expressed by thymic microenvironment during experimental Plasmodium berghei infection: consequences on thymocyte development.

We previously showed alterations in the thymus during experimental infection with Plasmodium berghei. Such alterations comprised histological changes, with loss of cortical-medullary limits, and the intrathymic presence of parasites. As the combination of chemokines, adhesion molecules and extracellular matrix (ECM) is critical to appropriate thymocyte development, we analysed the thymic expression of ECM ligands and receptors, as well as chemokines and their respective receptors during the experimental P. berghei infection. Increased expression of ECM components was observed in thymi from infected mice. In contrast, down-regulated surface expression of fibronectin and laminin receptors was observed in thymocytes from these animals. Moreover, in thymi from infected mice there was increased CXCL12 and CXCR4, and a decreased expression of CCL25 and CCR9. An altered thymocyte migration towards ECM elements and chemokines was seen when the thymi from infected mice were analysed. Evaluation of ex vivo migration patterns of CD4/CD8-defined thymocyte subpopulations revealed that double-negative (DN), and CD4(+) and CD8(+) single-positive (SP) cells from P. berghei-infected mice have higher migratory responses compared with controls. Interestingly, increased numbers of DN and SP subpopulations were found in the spleens of infected mice. Overall, we show that the thymic atrophy observed in P. berghei-infected mice is accompanied by thymic microenvironmental changes that comprise altered expression of thymocyte migration-related molecules of the ECM and chemokine protein families, which in turn can alter the thymocyte migration pattern. These thymic disturbances may have consequences for the control of the immune response against this protozoan.

Trypanosoma cruzi: populations bearing opposite virulence induce differential expansion of circulating CD3+CD4-CD8- T cells and cytokine serum levels in young and adult rats.

The JG strain is the least virulent while the CL-Brener clone is one of the most virulent Trypanosoma cruzi populations in young rats. In this study, we determined that the parasitemia peak values in CL-Brener clone-infected adult rats were 50-fold lower than in young rats and that mortality was null as compared to 45% death in young rats. Low parasitemia, milder and sustained myocarditis and myositis characterized JG infections. CL-Brener clone caused a significantly higher production of pro-inflammatory cytokines and higher expansion of CD3(+)CD4(-)CD8(-), double-negative (DN) T cells, during the acute phase in both adult and young rats. DN T cell frequencies correlated with IFN-gamma levels. These findings may explain the higher inflammation and fast acute phase resolution in CL-Brener infection. In young rats, IL-10 levels were similar in both infections. The IL-10/IFN-gamma ratio was higher in JG acute infection in accordance with the milder inflammation and parasite persistence leading to a chronic phase. In conclusion, virulence and pathogenicity depend on T. cruzi ability to induce expansion of DN T cells and production of specific cytokines.

Peripheral macrophage depletion reduces central nervous system parasitism and damage in Trypanosoma cruzi-infected suckling rats.

We aim at investigating the role of blood born macrophages on the brain reaction to Trypanosoma cruzi infection in suckling rats. This infection provoked the appearance of numerous ED1(+) cells in the neural parenchyma and increased the amount of meningeal and perivascular ED2(+) macrophages. CD8(+) and NKR(+) cells also occurred. Parenchymal blood vessels showed strong ICAM-1 and decreased occludin immunoreactivities. Selective depletion of peripheral macrophages by clodronate liposomes decreased tissue parasitism, nodular lesions, ICAM-1 upregulation and leukocyte infiltration. Occludin immunoreactivity remained as in uninfected animals. Our results indicate a role for blood-born macrophages in both parasite invasion and brain reaction. Microglia activation cannot be discarded.

Rat heart GDNF: effect of chemical sympathectomy.

Developmental studies indicate a role for GDNF in survival of motor, autonomic, and sensory neurons. However, no study attempted to demonstrate its participation in autonomic nerve regeneration. In this work, chemical sympathectomy by 6-hydroxydopamine provided the model for assessing heart GDNF expression during denervation and axonal regrowth. A glyoxylic acid-based histochemical technique evaluated the noradrenergic innervation. ELISA determined GDNF levels after concentrating heart homogenates. Light and ultrastructural in situ hybridization and immunocytochemistry were used for identifying cells expressing GDNF mRNA and protein. In control rats, the GDNF cardiac levels were significantly higher in 37-day-old animals in comparison with those aging 60 days. In sympathectomized rats, GDNF cardiac levels were significantly higher 7 days after sympathectomy and dropped to control levels at day 30. GDNF mRNA was expressed in atrial and ventricular myocytes from normal and sympathectomized rats. GDNF immunoreactivity occurred on atrial granules and quantitative analysis in electron micrographs confirmed ELISA-obtained data. In ventricular myocytes gold particles occurred sparsely. These findings constitute the first evidence for GDNF synthesis by cardiomyocytes and postulate a role for this factor soon after cardiac sympathetic denervation, probably in nerve regeneration. In atrial myocytes, GDNF is probably secreted by regulated pathway.