Improvement of the functional capacity is associated with BDNF and autonomic modulation in Chagas disease

Aerobic exercise attenuates dysautonomia, cardiac diastolic dysfunctions, and hemodynamic overload in female mice with atherosclerosis

Cardiovascular risk increases during the aging process in women with atherosclerosis and exercise training is a strategy for management of cardiac risks in at-risk populations. Therefore, the aims of this study were to evaluate: (1) the influence of the aging process on cardiac function, hemodynamics, cardiovascular autonomic modulation, and baroreflex sensitivity in females with atherosclerosis at the onset of reproductive senescence; and (2) the impact of exercise training on age-related dysfunctions in this model. Eighteen Apolipoprotein-E knockout female mice were divided equally into young (Y), middle-aged (MA), and trained middle-aged (MAT). Echocardiographic exams were performed to verify cardiac morphology and function. Cannulation for direct recording of blood pressure and heart rate, and analysis of cardiovascular autonomic modulation, baroreflex sensitivity were performed. The MA had lower cardiac diastolic function (E'/A' ratio), and higher aortic thickness, heart rate and mean arterial pressure, lower heart rate variability and baroreflex sensitivity compared with Y. There were no differences between Y and MAT in these parameters. Positive correlation coefficients were found between aortic wall thickness with hemodynamics data. The aging process causes a series of deleterious effects such as hemodynamic overload and dysautonomia in female with atherosclerosis. Exercise training was effective in mitigating aged-related dysfunctions.

Could pre-infection exercise training improve the efficacy of specific antiparasitic chemotherapy for Chagas disease?

Considering a potential exercise-drug interaction, we investigated whether exercise training could improve the efficacy of specific antiparasitic chemotherapy in a rodent model of Chagas disease. Wistar rats were randomized into five groups: sedentary and uninfected (CT); sedentary and infected (SI); sedentary, infected and treated (SIT); trained and infected (TI); trained, infected and treated (TIT). After 9-weeks running training, the animals were infected with T. cruzi and followed up for 4 weeks, receiving 100 mg kg-1 day-1 benznidazole. No evidence of myocarditis was observed in CT animals. TI animals exhibited reduced parasitemia, myocarditis, and reactive tissue damage compared to SI animals, in addition to increased IFN-γ, IL-4, IL-10, heart non-protein antioxidant (NPA) levels and glutathione-s transferase activity (P < 0.05). The CT, SIT and TIT groups presented similar reductions in parasitemia, cytokines (IFN-γ, TNF-α, IL-4, IL-10, IL-17 and MCP-1), inflammatory infiltrate, oxidative heart damage and antioxidant enzymes activity compared to SI and TI animals, as well as reduced heart microstructural remodeling (P < 0.05). By modulating heart inflammation and redox metabolism, exercise training exerts a protective effect against T. cruzi infection in rats. However, the antiparasitic and cardioprotective effects of benznidazole chemotherapy are more pronounced, determining similar endpoints in sedentary and trained T. cruzi-infected rats.

Physical training improves exercise tolerance, cardiac function and promotes changes in neurotrophins levels in chagasic mice

AIMS

To investigate the effects of moderate aerobic physical training on cardiac function and morphology as well as on the levels of glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) of animals infected with the Y strain of Trypanosoma cruzi.

MAIN METHODS

Twenty-eight male C57BL/6 mice were distributed into 4 groups: sedentary control (SC), trained control (TC), sedentary infected (CHC) and trained infected (CHT). The infection was performed by intraperitoneal injection of trypomastigote forms and the animals were adapted to treadmill in the week before the beginning of the training protocol, initiated 45 days post infection. Maximal exercise test (TEM) was performed at the baseline as well as at the end of the 4th, 8th and 12th weeks of training. At the end of the 12th week, all animals were evaluated for cardiac morphology and function by echocardiography.

KEY FINDINGS

CHC group showed a larger area of right ventricle (RVA), increased end-systolic volume and reduction in ejection fraction (EF), stroke volume (SV), cardiac output (CO) and fractional area change (FAC). The training reduced the RVA and improved the FAC of chagasic animals. GDNF level was higher in TC and CHC groups compared to SC in heart and BDNF levels were higher in CHC compared to SC in heart and serum.

SIGNIFICANCE

Physical training ameliorated the cardiac function of infected animals and promoted adjusts in BDNF and GDNF levels. These findings evidenced these neurotrophins as possible biomarkers of cardiac function responsive to exercise stimulus.

Prognostic value of serum brain-derived neurotrophic factor levels in patients with Chagas cardiomyopathy

BACKGROUND

Serum brain-derived neurotrophic factor (BDNF) levels have been shown to be lower in patients with Chagas cardiomyopathy (ChC) than in patients with non-dilated chagasic cardiomyopathy. However, its prognostic value was not established in patients with ChC.

METHODS

Forty-nine patients with ChC (50 ± 7 years, New York Heart Association “NYHA” I-III); were evaluated by echocardiography, exercise testing, and blood analysis. Serum BDNF levels were determined using enzyme-linked immunosorbent assay sandwich. Patients were followed-up, and cardiac death was considered the end-point. The survival analyses were performed using Kaplan-Meier and Cox regression.

RESULTS

After 39 ± 14 months of follow-up, 12 patients (25%) died. The concentration of 2.5 ng/mL was the optimal cut-off value to predict survival with significant difference between the groups with low (≤ 2.5 ng/mL) and high (> 2.5 ng/mL) BDNF levels (p = 0.006). Lower serum BDNF levels (hazards ratio (HR) 1.1, 95% confidence interval (CI) 1.1-1.4; p = 0.001), peak oxygen uptake (HR 1.2, 95% CI 1.0-1.3; p = 0.009), and left ventricular ejection fraction (HR 0.8, 95% CI 0.7-0.9; p = 0.001) were the independent predictors of survival. The combination of low serum BDNF levels and reduced left ventricular ejection fraction were highly predictive of death (HR 5.6, 95% CI: 1.2-9.7; p = 0.026).

CONCLUSION

In patients with ChC, reduced serum BDNF levels, especially if associated with systolic function, may provide useful prognostic information.

Cardiac autonomic denervation and expression of neurotrophins (NGF and BDNF) and their receptors during experimental Chagas disease

Although cardiac dysautonomia is a distinctive feature of Chagas disease, its clinical and functional significance is still being speculated. Neurotrophic factors are potentially involved; however, studies of their effect in this infection are rare. Ultrastructural abnormalities in autonomic varicosities, levels of both nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF), as well as the expression of their receptors, were analysed in the heart of a rat model of Trypanosoma infection. Predominantly, at the early stage of the infection, cardiac autonomic varicosities displayed several signs of degeneration parallel to the elevation of cardiac levels of NGF, as well as expression of the receptors TrkA and p75NTR. For BDNF and TrkB, the changes were less conspicuous. Data obtained here can contribute to further clarify the factors related to the autonomic nervous system's adaptive changes that could determine the evolution of different clinical forms of Chagas disease; mainly, the cardiac form.

BDNF - A key player in cardiovascular system

Neurotrophins (NTs) were first identified as target-derived survival factors for neurons of the central and peripheral nervous system (PNS). They are known to control neural cell fate, development and function. Independently of their neuronal properties, NTs exert unique cardiovascular activity. The heart is innervated by sensory, sympathetic and parasympathetic neurons, which require NTs during early development and in the establishment of mature properties, contributing to the maintenance of cardiovascular homeostasis. The identification of molecular mechanisms regulated by NTs and involved in the crosstalk between cardiac sympathetic nerves, cardiomyocytes, cardiac fibroblasts, and vascular cells, has a fundamental importance in both normal heart function and disease. The article aims to review the recent data on the effects of Brain-Derived Neurotrophic Factor (BDNF) on various cardiovascular neuronal and non-neuronal functions such as the modulation of synaptic properties of autonomic neurons, axonal outgrowth and sprouting, formation of the vascular and neural networks, smooth muscle migration, and control of endothelial cell survival and cardiomyocytes. Understanding these mechanisms may be crucial for developing novel therapeutic strategies, including stem cell-based therapies.

Parasite control and skeletal myositis in Trypanosoma cruzi-infected and exercised rats

Non-pharmacological strategies have been rarely described in the treatment of infectious diseases. Although exercise training has been recently incorporated in the clinical management of Chagas disease, the rationale basis that supports this indication is poorly understood. Thus, we investigated the effect of an aerobic exercise on the parasitism, inflammation and oxidative tissue damage in a murine model of Trypanosoma cruzi-induced skeletal myositis. Wistar rats were randomized into four groups: trained not infected (TNI) and infected (TI), sedentary not infected (SNI) and infected (SI). A running training program was administered 5days/week for 9 weeks. Then, infected animals were inoculated with T. cruzi and followed up for another 9 weeks. Exercise training induced beneficial adaptations by increasing time to fatigue and lactate threshold in TNI and TI animals. SI animals presented higher parasitemia, skeletal muscle parasitism, cell necrosis, leukocyte infiltration, cytokines levels, reactive oxygen species and nitric oxide production, thiobarbituric acid reactive substances, carbonyl proteins, myosin heavy chain I depletion, and increased catalase (CAT) and superoxide dismutase (SOD) activities. Beyond attenuation in all these variables, TI animals showed reduced TNF-α, CCL-2/MCP-1 and CX3CL1, and increased IL-10 muscle levels. Furthermore, these animals presented higher CAT and SOD activities and reduced lipid and protein oxidation. Taken together, our findings indicated that exercise training induced a protective phenotype in T. cruzi-infected mice, enhancing host defenses against the parasite and attenuating the pathological remodeling associated with skeletal myositis, aspects potentially associated to an improved immunological and redox balance in infected animals.

The role of interleukin 17-mediated immune response in Chagas disease: High level is correlated with better left ventricular function

Interleukin 17A (IL-17A) has been associated with protective rather than pathogenic response in Chagas disease (ChD). However, it is not established whether or not IL-17A-mediated immune response is correlated with patient’s left ventricular (LV) function in ChD. To address this question we have gathered cardiac functional parameters from ChD patients and analysed the possible relationship between their plasma IL-17A levels and LV function. Plasma IL-17A levels were measured by BD Cytometric Bead Array (CBA) in 240 patients with positive specific serology for Trypanosoma cruzi (T. cruzi) grouped as indeterminate (IND) and Chagas cardiomyopathy (CARD) forms. The levels of IL-17A in ChD patients were compared with 32 healthy individuals, mean age of 39 years, 50% male, that were also included as a control group (non-infected [NI]). The overall mean age of ChD patients was 46 years and 52% were male. The IND group included 95 asymptomatic patients, with ages ranging from 27 to 69 years (mean of 43 years), and 42.1% of them were male. The CARD group included 145 patients, which 58.6% were male, with ages ranging from 23 to 67 years (mean of 49). The IND group presented substantially higher levels of IL-17A, median of 26.16 (3.66–48.33) as compared to both the CARD group, median of 13.89 (3.87–34.54) (P <0.0001), and the NI group, median of 10.78 (6.23–22.26) (P <0.0001). The data analysis demonstrated that the IND group comprises a significantly greater proportion (P <0.001) of high IL-17A producers (52.6%, 50 of 95 subjects) than do the other groups. A significant direct correlation was verified between IL-17A levels and cardiac function expressed by LV ejection fraction (LVEF), LV diastolic diameter (LVDd), and body surface area (BSA)-indexed LVDd as well as ratio of the early diastolic transmitral flow velocity to early diastolic mitral annular velocity (E/e’) in both groups. We demonstrated that plasma IL-17A levels has an accurate sensitivity and specificity to predict heart failure in serology-positive patients and might be a useful parameter to distinguish patients with or without cardiac impairment. This study indicates a consistent relationship between high expression of IL-17A and better LV in human chronic ChD. Our data raise the possibility that IL-17A plays an important immunomodulatory role in the chronic phase of ChD and might be involved in protection against myocardial damage.

Modulation of inflammatory and oxidative status by exercise attenuates cardiac morphofunctional remodeling in experimental Chagas cardiomyopathy

AIMS

The rational basis that explains the benefits of exercise therapy on Chagas cardiomyopathy (ChC) is poorly understood. This study investigated the impact of an exercise program on exercise performance, heart parasitism, immunoinflammatory response, fibrogenesis, oxidative damage, and cardiomyocytes contractility in experimental ChC.

MAIN METHODS

Wistar rats were subjected to a 9-week treadmill running training and challenged with Trypanosoma cruzi. Control animals remained sedentary. Physical and metabolic performance, cardiac morphology, cytokines, chemokines, nitric oxide, oxidative tissue damage, cardiomyocyte morphology and contractility were analyzed.

KEY FINDINGS

Exercise training was efficient to improve physical performance and anaerobic threshold in trained animals. By increasing cardiac and serum levels of cytokines (TNF-α, IFN-γ, and IL-6), chemokines (MCP-1 and CX3CL1), the myocardial activity catalase and superoxide dismutase, and reducing lipid and protein oxidation in cardiac tissue, exercise training seem to be a beneficial strategy to mitigate the progression and severity of Chagas-associated cardiomyopathy.

SIGNIFICANCE

The protective adaptations to the host triggered by exercise training contributed to reduce cardiac parasitism, inflammation, fibrosis and cardiomyocytes atrophy. Although exercise training does not affect nitric oxide levels in cardiac tissue from infected animals, this strategy enhanced the efficiency of endogenous antioxidant mechanisms, restricting oxidative tissue damage with positive repercussions to cardiomyocytes biomechanics in rats.

Health-related quality of life in patients with Chagas disease: a review of the evidence

Chagas disease (ChD), a neglected tropical disease caused by infection with the parasite Trypanosoma cruzi (T. cruzi), remains a serious public health issue in Latin America and is an emerging disease in several non-endemic countries, where knowledge of the condition and experience with its clinical management are limited. Regionally, the disease is the major cause of disability secondary to tropical diseases in young adults. Health-related quality of life (HRQoL) impairment is common in patients with ChD, especially in those with Chagas dilated cardiomyopathy, the most severe manifestation of the disease, which frequently leads to heart failure. The aim of this review was to conduct a literature search for studies that have evaluated the determining factors of HRQoL in ChD patients. We included cross-sectional, case-control, cohort, and experimental studies, as well as clinical trials that evaluated the HRQoL in ChD patients aged 18 to 60 years and are presenting an explicit description of statistical analysis. Using a combination of keywords based on Descriptors in Health Sciences (DeCS) and Medical Subject Headings (MeSH) for searches in PubMed and the Scientific Electronic Library Online (SciELO), 148 studies were found. After exclusions, 12 studies were selected for analysis. Three main findings were extracted from these studies: 1) cardiac involvement is associated with a worse HRQoL in ChD patients; 2) HRQoL is associated with the patients' functional capacity; and 3) simple and inexpensive therapeutic measures are effective for improving HRQoL in ChD patients. Hence, ChD patients' functional capacity, the effectiveness of non-surgical conservative treatment, and cardiac involvement are important determining factors for the HRQoL in ChD patients.