Genetically Determined MBL Deficiency Is Associated with Protection against Chronic Cardiomyopathy in Chagas Disease

<div><p>Chagas disease (CD) is caused by <i>Trypanosoma cruzi</i>, whose sugar moieties are recognized by mannan binding lectin (MBL), a soluble pattern-recognition molecule that activates the lectin pathway of complement. MBL levels and protein activity are affected by polymorphisms in the <i>MBL2</i> gene. We sequenced the <i>MBL2</i> promoter and exon 1 in 196 chronic CD patients and 202 controls. The <i>MBL2*C</i> allele, which causes MBL deficiency, was associated with protection against CD (P = 0.007, OR = 0.32). Compared with controls, genotypes with this allele were completely absent in patients with the cardiac form of the disease (P = 0.003). Furthermore, cardiac patients with genotypes causing MBL deficiency presented less heart damage (P = 0.003, OR = 0.23), compared with cardiac patients having the <i>XA</i> haplotype causing low MBL levels, but fully capable of activating complement (P = 0.005, OR = 7.07). Among the patients, those with alleles causing MBL deficiency presented lower levels of cytokines and chemokines possibly implicated in symptom development (IL9, p = 0.013; PDGFB, p = 0.036 and RANTES, p = 0.031). These findings suggest a protective effect of genetically determined MBL deficiency against the development and progression of chronic CD cardiomyopathy.</p></div

Distribution of MBL levels according to <i>MBL2</i> genotypes in controls and patients.

<p>Open circles indicate individuals with the <i>LYQC</i> haplotype. Medians in each group are given by a horizontal line. P values refer to Kruskal-Wallis test.</p

Hypothetical role of high MBL levels in heart Chagas disease.

<p>In the acute stage of <i>T</i>. <i>cruzi</i> infection, MBL molecules function as opsonins for the pathogen. Thus high MBL levels would increase phagocytosis of the parasite. In the chronic stage of the disease, MBL may bind to altered-cell molecular patterns expressed on myocardium of CD patients, activating the lectin pathway and leading to an increased secretion of RANTES and pro-inflammatory cytokines such as IL-9 and PDGF (in patients with the <i>MBL2*A/A</i> genotype), thereby promoting heart damage leading to chagasic chronic cardiomiopathy.</p

Distribution of cytokine/chemokine levels according to the presence of <i>MBL2*O</i> (<i>B</i>, <i>C</i> or <i>D</i>) alleles.

<p>A. IL9 distribution (P value refers to Mann-Whitney test; horizontal line indicates the median level). B. PDGF distribution (P value refers to an unpaired t-test; horizontal line indicates the mean level). C. RANTES distribution (P value refers to Mann-Whitney test; horizontal line indicates the median level). There were no <i>MBL2*O/O</i> homozygotes among those measured for the investigated cytokines/chemokines. Three outliers with inconsistent results were excluded from all comparisons. Due to small sample size, Bonferroni P values were not significant.</p

Distribution of MBL levels according to the functional classification of heart failure.

<p>Open circles indicate patients with the <i>YO</i> haplotype; open diamonds, patients with the <i>XA/XA</i> or <i>XA/YA</i> genotypes. Medians in each group are given by a horizontal line. MBL levels were not analyzed in patients classified within the “B2” class. P value refers to Kruskal-Wallis test.</p

Oxidation Process of Adrenaline in Freshly Isolated Rat Cardiomyocytes: Formation of Adrenochrome, Quinoproteins, and GSH Adduct

High concentrations of circulating biogenic catecholamines often exist during the course of several cardiovascular disorders. Additionally, coronary dysfunctions are prominent and frequently related to the ischemic and reperfusion phenomenon (I/R) in the heart, which leads to the release of large amounts of catecholamines, namely adrenaline, and to a sustained generation of reactive oxygen species (ROS). Thus, this work aimed to study the toxicity of adrenaline either alone or in the presence of a system capable of generating ROS [xanthine with xanthine oxidase (X/XO)], in freshly isolated, calcium tolerant cardiomyocytes from adult rats. Studies were performed for 3 h, and cardiomyocyte viability, ATP level, lipid peroxidation, protein carbonylation content, and glutathione status were evaluated, in addition to the formation of adrenaline’s oxidation products and quinoproteins. Intracellular GSH levels were time-dependently depleted with no GSSG formation when cardiomyocytes were exposed to adrenaline or to adrenaline with X/XO. Meanwhile, a time-dependent increase in the rate of formation of adrenochrome and quinoproteins was observed. Additionally, as a new outcome, 5-(glutathion-S-yl)adrenaline, an adrenaline adduct of glutathione, was identified and quantified. Noteworthy is the fact that the exposure to adrenaline alone promotes a higher rate of formation of quinoproteins and glutathione adduct, while adrenochrome formation is favored where ROS production is stimulated. This study shows that the redox status of the surrounding environment greatly influences adrenaline’s oxidation pathway, which may trigger cellular changes responsible for cardiotoxicity