Elevated IL-17 levels and echocardiographic signs of preserved myocardial function in benznidazole-treated individuals with chronic Chagas' disease.

BACKGROUND: The immunological and clinical impact of trypanocidal treatment in chronic Chagas' disease (CCD) is unclear. METHODOLOGY AND FINDINGS: Several cytokines were measured in plasma of 66 patients with CCD. Thirty-three patients had been previously treated with benznidazole and 33 had never been treated. The treated group exhibited higher levels of IL-17 (median 142.45×1.22pg/ml, P=0.025), which was the only one significantly associated with Bz treatment, especially after adjusting for time of disease and NYHA class (P=0.024; OR 1.006, 95% CI 1.001-1.010). Compared to untreated patients, the treated group exhibited higher median values of mitral annular E' lateral (13.0×10.0cm/s, P=0.038), S' infero-lateral (8.9×7.6cm/s, P=0.013), S' septal (8.5×7.4cm/s, P=0.034), mean S' (9.0×7.9cm/s, P=0.013) and tricuspid annular S' (13.3×11.1cm/s, P=0.001) and lower values of E/E' septal (7.2×9.5cm/s, P=0.049). After adjustment for time of disease and NYHA class, S' infero-lateral (P=0.031), mean S' (P=0.049) and S' tricuspid (P=0.024) persisted as significantly associated with treatment. CONCLUSION: The present findings suggest that the group of CCD patients treated with Bz displayed increased plasma levels of IL-17 and preserved myocardial function, reinforcing the idea that Bz treatment may be beneficial.

Associations between hepcidin and immune response in individuals with hyperbilirubinaemia and severe malaria due to Plasmodium vivax infection.

BACKGROUND: Hyperbilirubinaemia (bilirubin >51.3 µmol/L) alone is not indicative of severe malaria, and the immune response underlying hyperbilirubinaemia remains largely unexplored. Liver damage associated with hyperbilirubinaemia may alter the expression of hepcidin, which regulates systemic iron by degrading ferroportin. For this study, the association between hepcidin and the levels of cytokines and chemokines in the serum of individuals with mild and severe vivax malaria and subjects with malaria with isolated hyperbilirubinaemia was evaluated. METHODS: Cytokines/chemokines and hepcidin were measured in individuals with mild (n = 72) and severe (n = 17) vivax malaria, as well as in the serum of subjects with vivax malaria with isolated hyperbilirubinaemia (n = 14) from the Brazilian Amazon between 2009 and 2013 by multiplex assay and ELISA, respectively. The polymorphism 744 G > T in the ferroportin gene was identified by restriction fragment-length polymorphism analysis and the restriction enzyme PvuII. RESULTS: The polymorphism at position 744 G > T in the ferroportin gene was typed and no differences in the distributions of genotypes or alleles were observed between the study groups. Subjects with severe malaria had higher levels of interleukin (IL)-2 and IL-13 than subjects with hyperbilirubinaemia. No differences in the expression of immune markers were observed between subjects with mild malaria and those with hyperbilirubinaemia. However, hepcidin levels were higher in individuals with severe malaria and hyperbilirubinaemia than those with mild malaria (p = 0.0002 and p = 0.0004, respectively) and cut-off values of hepcidin differentiated these groups from subjects with mild malaria. Hepcidin was positively associated with IL-6 and IL-10 levels and with parasitaemia in subjects with mild malaria and with IFN-γ in subjects with severe malaria. CONCLUSIONS: Malaria in the presence of hyperbilirubinaemia produces a less robust inflammatory response compared to severe cases of malaria. Hepcidin levels are positively associated with immune markers in vivax malaria outcomes.

Unravelling the patterns of host immune responses in Plasmodium vivax malaria and dengue co-infection.

BACKGROUND: Concurrent malaria and dengue infection is frequently diagnosed in endemic countries, but its immunopathology remains largely unknown. In the present study, a large panel of cytokines/chemokines and clinical laboratory markers were measured in patients with Plasmodium vivax and dengue co-infection as well as in individuals with malaria or dengue mono-infections in order to identify biosignatures of each clinical condition. METHODS: Individuals from the Brazilian Amazon were recruited between 2009 and 2013 and classified in three groups: vivax malaria (n = 52), dengue (n = 30) and vivax malaria and dengue co-infection (n = 30). P. vivax malaria was diagnosed by thick blood smear and confirmed by PCR; dengue cases were detected by IgM ELISA or NS1 protein. The plasma levels of cytokines and chemokines were determined by multiplex assay. RESULTS: Individuals with malaria and dengue co-infection displayed lower levels of platelets and haemoglobin than those with malaria or dengue mono-infections (p = 0.0047 and p = 0.0001, respectively). The group of individuals co-infected exhibited the highest median concentrations of IFN-γ, IL-6, CCL4 than the mono-infected groups. Network analyses of plasma cytokines/chemokines revealed that malaria and dengue co-infection exhibits a distinct immune profile with critical roles for TNF, IL-6 and IFN-γ. Further, parasitaemia levels displayed positive significant interactions with IL-6, CCL4 and IL-10 in the group of patients co-infected with malaria and dengue. No differences were observed in distribution of dengue virus serotypes and Plasmodium parasitaemia levels between the groups. CONCLUSIONS: The findings described here identify unique patterns of circulating immunological markers in cases of malaria and dengue co-infection and provide insights on the immunopathology of this co-morbid condition.

Medical Specialty Choice and Related Factors of Brazilian Medical Students and Recent Doctors.

BACKGROUND: Choosing a medical specialty is an important, complex, and not fully understood process. The present study investigated the factors that are related to choosing and rejecting medical specialties in a group of students and recent medical doctors. METHODOLOGY AND FINDINGS: A cross-sectional survey of 1,223 medical students and doctors was performed in Brazil in 2012. A standardized literature-based questionnaire was applied that gathered preferable or rejected specialties, and asked questions about extracurricular experiences and the influence of 14 factors on a Likert-type scale from 0 to 4. Specialties were grouped according to lifestyle categories: controllable and uncontrollable, which were subdivided into primary care, internal medicine, and surgical specialties. Notably, the time period of rejection was usually earlier than the time period of intended choice (p < 0.0001, χ(2) = 107.2). The choice mainly occurred during the internship period in medical school (n = 466; 38.7%). An overall large frequency of participation in extracurricular activities was observed (n = 1,184; 95.8%), which were highly associated with the respective medical area. Orthopedic surgery had the highest correlation with participation in specialty-specific organized groups (OR = 59.9, 95% CI = 21.6-166.3) and psychiatry was correlated with participation in research groups (OR = 18.0, 95% CI = 9.0-36.2). With regard to influential factors in controllable lifestyle specialties, "financial reason" (mean score ± standard deviation: 2.8 ± 1.0; median = 3) and "personal time" (3.1 ± 1.3; median = 4) were important factors. In primary care, these factors were less important (1.7 ± 1.3 and 1.7 ± 1.5, respectively; median = 2 for both), and higher scores were observed for "curricular internship" (3.2 ± 1.1, median = 4) and "social commitment" (2.6 ± 1.3, median = 3). CONCLUSION: The present findings provide important insights into developing strategies to stimulate interest in specialties based on the needs of the Brazilian healthcare system.

DDX39B (BAT1), TNF and IL6 gene polymorphisms and association with clinical outcomes of patients with Plasmodium vivax malaria.

BACKGROUND: DDX39B (BAT1) encodes an RNA helicase known to regulate expression of TNF and IL-6. Elevated levels of these two cytokines are associated with increased severity of clinical malaria. The aim of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in the DDX39B, TNF and IL6 genes and the clinical outcomes of patients with Plasmodium vivax malaria. METHODS: Cross-sectional investigations were carried out in two regions of the Brazilian Amazon where several studies on the pathogenesis of vivax malaria had been performed. Individuals were categorized according to infection status as well as clinical presentation into the following groups: uninfected, asymptomatic infection, mild infection, or complicated infection. Polymorphisms were identified using PCR restriction fragment-length polymorphism analysis and the restriction enzymes NlaIII or NcoI. The plasma levels of cytokines were determined using ELISA. RESULTS: The G allele of DDX39B-22C > G was associated with absent or decreased manifestations of malaria and the C allele was a risk factor for disease complications. Study participants heterozygous for TNF-308 (GA) and DDX39B-348 (CT) had higher TNF levels than wild-type participants. Haplotypes that included DDX39B (-22C > G and -348C > T) and TNF polymorphisms were not directly associated with mild or complicated malaria infections; however, haplotypes AGC, ACC, GGT, AGT and ACT were associated with increased TNF levels. Participants with genotype combinations GC/CC/GG/GG and GG/CT/GG/GG (DDX39B-22/DDX39B-348/TNF-308/IL6-176) had decreased and increased risk of mild malaria, respectively, compared with asymptomatic and uninfected participants. GC/CC/GG/GG was linked to decreased TNF and IL-6 levels. CONCLUSIONS: This is the first study to describe patients with DDX39B and IL6 SNPs who had vivax malaria. These findings support the postulation that a set of mutations in immune-related genes is associated with inflammatory mediators and the clinical outcomes of patients with malaria.

Networking the host immune response in Plasmodium vivax malaria.

BACKGROUND: Plasmodium vivax malaria clinical outcomes are a consequence of the interaction of multiple parasite, environmental and host factors. The host molecular and genetic determinants driving susceptibility to disease severity in this infection are largely unknown. Here, a network analysis of large-scale data from a significant number of individuals with different clinical presentations of P. vivax malaria was performed in an attempt to identify patterns of association between various candidate biomarkers and the clinical outcomes. METHODS: A retrospective analysis of 530 individuals from the Brazilian Amazon, including P. vivax-infected individuals who developed different clinical outcomes (148 asymptomatic malaria, 187 symptomatic malaria, 13 severe non-lethal malaria, and six severe lethal malaria) as well as 176 non-infected controls, was performed. Plasma levels of liver transaminases, bilirubins, creatinine, fibrinogen, C-reactive protein, superoxide dismutase (SOD)-1, haem oxygenase (HO)-1 and a panel composed by multiple cytokines and chemokines were measured and compared between the different clinical groups using network analysis. RESULTS: Non-infected individuals displayed several statistically significant interactions in the networks, including associations between the levels of IL-10 and IL-4 with the chemokine CXCL9. Individuals with asymptomatic malaria displayed multiple significant interactions involving IL-4. Subjects with mild or severe non-lethal malaria displayed substantial loss of interactions in the networks and TNF had significant associations more frequently with other parameters. Cases of lethal P. vivax malaria infection were associated with significant interactions between TNF ALT, HO-1 and SOD-1. CONCLUSIONS: The findings imply that clinical immunity to P. vivax malaria is associated with multiple significant interactions in the network, mostly involving IL-4, while lethality is linked to a systematic reduction of complexity of these interactions and to an increase in connections between markers linked to haemolysis-induced damage.

Association between the haptoglobin and heme oxygenase 1 genetic profiles and soluble CD163 in susceptibility to and severity of human malaria.

Intravascular hemolysis is a hallmark event in the immunopathology of malaria that results in increased systemic concentrations of free hemoglobin (Hb). The oxidation of Hb by free radicals causes the release of heme, which amplifies inflammation. To circumvent the detrimental effects of free heme, hosts have developed several homeostatic mechanisms, including the enzyme haptoglobin (Hp), which scavenges cell-free Hb, the monocyte receptor CD163, which binds to Hb-Hp complexes, and heme oxygenase-1 (HO-1), which degrades intracellular free heme. We tested the association between these three main components of the host response to hemolysis and susceptibility to malaria in a Brazilian population. The genetic profiles of the HMOX1 and Hp genes and the plasma levels of a serum inflammatory marker, the soluble form of the CD163 receptor (sCD163), were studied in 264 subjects, including 78 individuals with symptomatic malaria, 106 individuals with asymptomatic malaria, and 80 uninfected individuals. We found that long (GT)n repeats in the microsatellite polymorphism region of the HMOX1 gene, the Hp2 allele, and the Hp2.2 genotype were associated with symptomatic malaria. Moreover, increased plasma concentrations of heme, Hp, HO-1, and sCD163 were associated with susceptibility to malaria. The validation of these results could support the development of targeted therapies and aid in reducing the severity of malaria.

The host genetic diversity in malaria infection.

Populations exposed to Plasmodium infection develop genetic mechanisms of protection against severe disease. The clinical manifestation of malaria results primarily from the lysis of infected erythrocytes and subsequent immune and inflammatory responses. Herein, we review the genetic alterations associated with erythrocytes or mediators of the immune system, which might influence malaria outcome. Moreover, polymorphisms in genes related to molecules involved in mechanisms of cytoadherence and their influence on malaria pathology are also discussed. The results of some studies have suggested that the combinatorial effects of a set of genetic factors in the erythrocyte-immunology pathway might be relevant to host resistance or susceptibility against Plasmodium infection. However, these results must be interpreted with caution because of the differences observed in the functionality and frequency of polymorphisms within different populations. With the recent advances in molecular biology techniques, more robust studies with reliable data have been reported, and the results of these studies have identified individual genetic factors for consideration in preventing severe disease and the individual response to treatment.

Hepatitis B infection is associated with asymptomatic malaria in the Brazilian Amazon.

BACKGROUND: Areas that are endemic for malaria are also highly endemic for hepatitis B virus (HBV) infection. Nevertheless, it is unknown whether HBV infection modifies the clinical presentation of malaria. This study aimed to address this question. METHODOLOGY AND FINDINGS: An observational study of 636 individuals was performed in Rondônia, western Amazon, Brazil between 2006 and 2007. Active and passive case detections identified Plasmodium infection by field microscopy and nested Polymerase Chain Reaction (PCR). HBV infections were identified by serology and confirmed by real-time PCR. Epidemiological information and plasma cytokine profiles were studied. The data were analyzed using adjusted multinomial logistic regression. Plasmodium-infected individuals with active HBV infection were more likely to be asymptomatic (OR: 120.13, P<0.0001), present with lower levels of parasitemia and demonstrate a decreased inflammatory cytokine profile. Nevertheless, co-infected individuals presented higher HBV viremia. Plasmodium parasitemia inversely correlated with plasma HBV DNA levels (r = -0.6; P = 0.0003). CONCLUSION: HBV infection diminishes the intensity of malaria infection in individuals from this endemic area. This effect seems related to cytokine balance and control of inflammatory responses. These findings add important insights to the understanding of the factors affecting the clinical outcomes of malaria in endemic regions.