Studies performed in vitro suggest that activation of Toll-like receptors (TLRs) by parasite-derived molecules may initiate inflammatory responses and host innate defense mechanisms against Trypanosoma cruzi. Here, we evaluated the impact of TLR2 and myeloid differentiation factor 88 (MyD88) deficiencies in host resistance to infection with T. cruzi. Our results show that macrophages derived from TLR2 −/− and MyD88−/− mice are less responsive to GPI-mucin derived from T. cruzi trypomastigotes and parasites. In contrast, the same cells from TLR2−/− still produce TNF-α, IL-12, and reactive nitrogen intermediates (RNI) upon exposure to live T. cruzi trypomastigotes. Consistently, we show that TLR2−/− mice mount a robust proinflammatory cytokine response as well as RNI production during the acute phase of infection with T. cruzi parasites. Further, deletion of the functional TLR2 gene had no major impact on parasitemia nor on mortality. In contrast, the MyD88−/− mice had a diminished cytokine response and RNI production upon acute infection with T. cruzi. More importantly, we show that MyD88−/− mice are more susceptible to infection with T. cruzi as indicated by the higher parasitemia and accelerated mortality, as compared with the wild-type mice. Together, our results indicate that T. cruzi parasites elicit an alternative inflammatory pathway independent of TLR2. This pathway is partially dependent on MyD88 and necessary for mounting optimal inflammatory and RNI responses that control T. cruzi replication during the early stages of infection.

Nutritional deficiencies can be prevented if a multidisciplinary team regularly assists the patient. Malnutrition is generally reverted with nutrient supplementation, once it is promptly diagnosed. Especial attention should be given to adolescents, mainly girls at reproductive age who have a substantial risk of developing iron deficiency. Future studies are necessary to detect nutrient abnormalities after new procedures and to evaluate the safety of bariatric surgery in younger obese patients.

Toxoplasma gondii is an obligate intracellular protozoan parasite, which infects a wide range of intermediate hosts that include different species of birds and mammals, including humans. The tachyzoites, the rapid multiplying form of the parasite, can invade and replicate within all nucleated cells and, if left unchecked by the immune system, causes extensive tissue damage and death of the intermediate host (11). Resistance to acute infection with T. gondii in the murine model is highly dependent on endogenous gamma interferon (IFN-␥) (11,12,37,43). Soon after initial infection in the intermediate host, T. gondii tachyzoites trigger the synthesis of interleukin-12 (2, 12, 13, 23, 34) and other costimulatory cytokines (13,17,22,23), which initiate the synthesis of IFN-␥ by NK cells (13, 23) and CD4 ϩ CD8 Ϫ ␣␤ ϩ T lymphocytes (12). IFN-␥ combined with tumor necrosis factor alpha will activate macrophages to produce high levels of reactive nitrogen intermediates (RNI) that are involved in the control of parasite replication (1, 26). However, RNI is only one of the IFN-␥-inducible mechanisms involved in the control of tachyzoite replication, and mice treated with inducible nitric oxide synthase (iNOS) inhibitor (20) or deficient in iNOS (38) are relatively more resistant than mice treated with neutralizing antibodies to IFN-␥ (12) or deficient in IFN-␥ or IFN-␥ receptor (10, 37). Thus, additional effector mechanisms induced by IFN-␥ and active during early experimental infection with T. gondii in the mouse model still have to be defined (11,21).Indoleamine 2,3-dioxygenase (INDO) is an enzyme that catalyzes the initial rate-limiting step of tryptophan (Trp) catabolism to N-formylkynurenine and kynurenine (Kyn) (21, 44). Many human cell lines express INDO upon stimulation with IFN-␥. Restriction of available Trp due to degradation by INDO leads to the control of various intracellular pathogens, including T. gondii, in both nonprofessional phagocytic cells (NPPC) and professional phagocytic cells (PPC) (4,5,7,8,28,29,32,39,45). In the absence of Trp, an essential amino acid for T. gondii, parasite growth also becomes restricted (32,36,41). In fact, in human NPPC the induction of INDO appears to be the main mechanism by which IFN-␥ controls the intracellular replication of T. gondii tachyzoites (4,5,7,8,29,32).The INDO activity and the Trp-Kyn metabolic pathway can be induced in murine tissues under various conditions (21,27,35,36). However, it has been difficult to demonstrate the role of INDO and Trp degradation in the control of tachyzoite replication in cell lines of mouse origin (18,19,40). In addition, no information is available about the induction of the Trp-Kyn metabolic pathway and its possible role in the restriction of parasite replication during in vivo experimental infection with T. gondii. In the present study, we evaluated the induction of INDO mRNA, Trp degradation, and Kyn formation during infection with T. gondii. Our results show that during the early stage of infection with T. gondii in the mouse ...

Objective Emerging evidence suggests that neuronal guidance cues, typically expressed during development, are involved in both physiological and pathological immune responses. We hypothesized that endothelial expression of such guidance cues may regulate leukocyte trafficking into the vascular wall during atherogenesis. Approach/Results We demonstrate that members of the Netrin, Semaphorin and Ephrin family of guidance molecules are differentially regulated under conditions that promote or protect from atherosclerosis. Netrin-1 and Semaphorin3A are expressed by coronary artery endothelial cells and potently inhibit chemokine-directed migration of human monocytes. Endothelial expression of these negative guidance cues is down-regulated by pro-atherogenic factors, including oscillatory shear stress and pro-inflammatory cytokines associated with monocyte entry into the vessel wall. Furthermore, we show using intravital microscopy that inhibition of Netrin-1 or Semaphorin3A using blocking peptides increases leukocyte adhesion to the endothelium. Unlike Netrin-1 and Semaphorin3A, the guidance cue EphrinB2 is up-regulated under pro-atherosclerotic flow conditions and functions as a chemoattractant, increasing leukocyte migration in the absence of additional chemokines. Conclusions The concurrent regulation of negative and positive guidance cues may facilitate leukocyte infiltration of the endothelium through a balance between chemoattraction and chemorepulsion. These data indicate a previously unappreciated role for axonal guidance cues in maintaining the endothelial barrier and regulating leukocyte trafficking during atherogenesis.

Tributyrin (TBT) is a TAG composed of three butyric acids that has beneficial effects on ulcerative colitis due to its trophic, anti-inflammatory, pro-apoptotic and anti-carcinogenic properties. The goal of the present study was to evaluate the efficacy and mechanisms of action of TBT supplementation in the prevention of mucosal damage in experimental colitis. Mice received either a control diet or a TBT-supplemented diet for 15 d. Colitis was induced by dextran sodium sulphate administration during the last 7 d. Mucosal damage and the activation of immune cells and cytokines were determined by histological score, flow cytometry and ELISA. Leucocyte rolling and adhesion were assessed by intravital microscopy. Oxidative stress was determined by monitoring hydroperoxide concentration and evaluating superoxide dismutase (SOD) and catalase activities. Intestinal permeability was analysed using diethylenetriaminepentaacetate acid ( 99mTc DTPA). Compared with the colitis group, the animals in the colitis þ TBT group had reduced mucosal damage and neutrophil and eosinophil mucosal infiltration, which were associated with a higher percentage of regulatory T cells (Treg) and higher levels of transforming growth factor b and IL-10 in the lamina propria. The level of in vivo leucocyte adhesion in the colon microvasculature was reduced after TBT supplementation. A lower level of hydroperoxide and higher levels of SOD and catalase activities were associated with TBT supplementation. TBT-supplemented mice showed reduced intestinal permeability to the levels intermediate between the control and colitis groups. In conclusion, the present results show that TBT has positive effects on colonic restructuring in experimental colitis. Additionally, TBT supplementation changes the immune response by controlling inflammation and regulating the expression of anti-inflammatory cytokines and Treg.

No abstract

The majority of contacts with foreign antigenic materials occur on the gut mucosa, and are represented by food proteins and the autochthonous microbiota. In the present study, we replaced intact dietary proteins by equivalent amounts of amino acids from weaning on and investigated its effects on the development of the immune system of mice. Adult animals reared on a balanced protein-free diet (Aa-mice) have a poorly developed gut-associated lymphoid tissue resembling suckling mice. They also display low numbers of lamina propria cells and TCRalphabeta intraepithelial lymphocytes, and low levels of secretory IgA. Levels of circulating IgG and IgA are also reduced in Aa-mice, whereas IgM levels are normal. In vitro cytokine production by cells from several lymphoid organs shows a predominant T(h)2 profile with a high concentration of IL-10 and IL-4, and a low concentration of IFN-gamma. These parameters also resemble the immunological patterns observed in pre-weaned mice. Thus, our data clearly show that exposure to food proteins after weaning has a physiological role in the maturation of the immune system both locally and systemically.

Human exposure to mercury is a serious problem of public health in Amazon. As in other vulnerable populations throughout the world, Amazonian riverine populations are chronically exposed to this metal and some symptoms of mercury intoxication were already detected in these populations. However, studies on the genetic susceptibility to mercury toxicity in the Amazon are scarce, and they tested a limited number of individuals. In this context, apolipoprotein E gene (APOE) is a key element with a well-established association among their alleles and the neurodegenerative consequences of mercury intoxication. However, no studies have addressed APOE genotyping in Amazonian exposed populations. Additionally, epidemiological studies with APOE genotyping in Amazon have been restricted to indigenous populations. Therefore, this work analyzed for the first time the genotypic and allelic profiles of APOE in Amazonian riverine populations chronically exposed to mercury. Eight hundred and twenty three individuals were enrolled in our study donating blood (794) and/or hair (757). APOE genotyping was analyzed by real-time PCR. Total mercury and mercury species were quantified by ICP-MS and GC-pyro-AFS, respectively. Genomic ancestry markers were evaluated by multiplex-PCR reaction, separated by capillary electrophoresis on the ABI 3130 Genetic Analyzer instrument and analyzed on GeneMapper ID v3.2. The 𝜀3 and 𝜀3/𝜀3 were the most frequent allele and genotype, respectively, followed by 𝜀4 allele and 𝜀3/𝜀4 genotype. Only 𝜀2/𝜀2 genotype was not found, suggesting that the absence of this genotype is a generalized phenomenon in Amazon. Also, our data supported an association between the presence of APOE4 and the Amerindian origin in these populations. Fifty-nine individuals were identified at maximum risk with levels of mercury above 10 μg/g and the presence of APOE4. Interestingly, among individuals with high mercury content, APOE4-carriers had high mercury levels than APOE2-carriers, pointing to a different heavy metal accumulation according to the APOE allele. These data suggest that APOE4, in addition to a possible pharmacodynamic effect, may influence pharmacokinetically the mercury exposure causing its higher accumulation and leading to worse deleterious consequences. Our results may aid in the development of prevention strategies and health policy decision-making regarding these at-risk vulnerable populations.