Advances in understanding the role of adipose tissue and mitochondrial oxidative stress in Trypanosoma cruzi infection

Adipocyte-released adipomes in Chagas cardiomyopathy: Impact on cardiac metabolic and immune regulation

Chronic Trypanosoma cruzi infection leads to Chagas cardiomyopathy (CCM), with varying manifestations such as inflammatory hypertrophic cardiomyopathy, arrhythmias, and dilated cardiomyopathy. The factors responsible for the increasing risk of progression to CCM are not fully understood. Previous studies link adipocyte loss to CCM progression, but the mechanism triggering CCM pathogenesis remains unexplored. Our study uncovers that T. cruzi infection triggers adipocyte apoptosis, leading to the release of extracellular vesicles named "adipomes". We developed an innovative method to isolate intact adipomes from infected mice's adipose tissue and plasma, showing they carry unique lipid cargoes. Large and Small adipomes, particularly plasma-derived infection-associated L-adipomes (P-ILA), regulate immunometabolic signaling and induce cardiomyopathy. P-ILA treatment induces hypertrophic cardiomyopathy in wild-type mice and worsens cardiomyopathy severity in post-acute-infected mice by regulating adipogenic/lipogenic and mitochondrial functions. These findings highlight adipomes' pivotal role in promoting inflammation and impairing myocardial function during cardiac remodeling in CD.

Kinetic Characterization and Inhibition of Trypanosoma cruzi Hypoxanthine–Guanine Phosphoribosyltransferases

Chagas disease, caused by the parasitic protozoan Trypanosoma cruzi, affects over 8 million people worldwide. Current antiparasitic treatments for Chagas disease are ineffective in treating advanced, chronic stages of the disease, and are noted for their toxicity. Like most parasitic protozoa, T. cruzi is unable to synthesize purines de novo, and relies on the salvage of preformed purines from the host. Hypoxanthine–guanine phosphoribosyltransferases (HGPRTs) are enzymes that are critical for the salvage of preformed purines, catalyzing the formation of inosine monophosphate (IMP) and guanosine monophosphate (GMP) from the nucleobases hypoxanthine and guanine, respectively. Due to the central role of HGPRTs in purine salvage, these enzymes are promising targets for the development of new treatment methods for Chagas disease. In this study, we characterized two gene products in the T. cruzi CL Brener strain that encodes enzymes with functionally identical HGPRT activities in vitro: TcA (TcCLB.509693.70) and TcC (TcCLB.506457.30). The TcC isozyme was kinetically characterized to reveal mechanistic details on catalysis, including identification of the rate-limiting step(s) of catalysis. Furthermore, we identified and characterized inhibitors of T. cruzi HGPRTs originally developed as transition-state analogue inhibitors (TSAIs) of Plasmodium falciparum hypoxanthine–guanine–xanthine phosphoribosyltransferase (PfHGXPRT), where the most potent compound bound to T. cruzi HGPRT with low nanomolar affinity. Our results validated the repurposing of TSAIs to serve as selective inhibitors for orthologous molecular targets, where primary and secondary structures as well as putatively common chemical mechanisms are conserved.

Prognosis of chronic Chagas heart disease and other pending clinical challenges

In this chapter, the main prognostic markers of Chagas heart disease are addressed, with an emphasis on the most recent findings and questions, establishing the basis for a broad discussion of recommendations and new approaches to managing Chagas cardiopathy. The main biological and genetic markers and the contribution of the electrocardiogram, echocardiogram and cardiac magnetic resonance are presented. We also discuss the most recent therapeutic proposals for heart failure, thromboembolism and arrhythmias, as well as current experience in heart transplantation in patients suffering from severe Chagas cardiomyopathy. The clinical and epidemiological challenges introduced by acute Chagas disease due to oral contamination are discussed. In addition, we highlight the importance of ageing and comorbidities in influencing the outcome of chronic Chagas heart disease. Finally, we discuss the importance of public policies, the vital role of funding agencies, universities, the scientific community and health professionals, and the application of new technologies in finding solutions for better management of Chagas heart disease.

Sex Differences in Cardiac Pathology of SARS-CoV2 Infected and Trypanosoma cruzi Co-infected Mice

Coronavirus disease-2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2; CoV2) is a deadly contagious infectious disease. For those who survive COVID-19, post-COVID cardiac damage greatly increases the risk of cardiomyopathy and heart failure. Currently, the number of COVID-related cases are increasing in Latin America, where a major COVID comorbidity is Chagas' heart disease, which is caused by the parasite Trypanosoma cruzi. However, the interplay between indeterminate Chagas disease and COVID-19 is unknown. We investigated the effect of CoV2 infection on heart pathology in T. cruzi infected mice (coinfected with CoV2 during the indeterminate stage of T. cruzi infection). We used transgenic human angiotensin-converting enzyme 2 (huACE2/hACE2) mice infected with CoV2, T. cruzi, or coinfected with both in this study. We found that the viral load in the hearts of coinfected mice is lower compared to the hearts of mice infected with CoV2 alone. We demonstrated that CoV2 infection significantly alters cardiac immune and energy signaling via adiponectin (C-ApN) and AMP-activated protein kinase (AMPK) signaling. Our studies also showed that increased β-adrenergic receptor (b-AR) and peroxisome proliferator-activated receptors (PPARs) play a major role in shifting the energy balance in the hearts of coinfected female mice from glycolysis to mitochondrial β-oxidation. Our findings suggest that cardiac metabolic signaling may differently regulate the pathogenesis of Chagas cardiomyopathy (CCM) in coinfected mice. We conclude that the C-ApN/AMPK and b-AR/PPAR downstream signaling may play major roles in determining the progression, severity, and phenotype of CCM and heart failure in the context of COVID.

Fat tissue regulates the pathogenesis and severity of cardiomyopathy in murine chagas disease

Chronic Chagas cardiomyopathy (CCC) caused by a parasite Trypanosoma cruzi is a life-threatening disease in Latin America, for which there is no effective drug or vaccine. The pathogenesis of CCC is complex and multifactorial. Previously, we demonstrated T. cruzi infected mice lose a significant amount of fat tissue which correlates with progression of CCC. Based on this an investigation was undertaken during both acute and chronic T. cruzi infection utilizing the FAT-ATTAC murine model (that allows modulation of fat mass) to understand the consequences of the loss of adipocytes in the regulation of cardiac parasite load, parasite persistence, inflammation, mitochondrial stress, ER stress, survival, CCC progression and CCC severity. Mice were infected intraperitoneally with 5x10⁴ and 10³ trypomastigotes to generate acute and chronic Chagas models, respectively. Ablation of adipocytes was carried out in uninfected and infected mice by treatment with AP21087 for 10 days starting at 15DPI (acute infection) and at 65DPI (indeterminate infection). During acute infection, cardiac ultrasound imaging, histological, and biochemical analyses demonstrated that fat ablation increased cardiac parasite load, cardiac pathology and right ventricular dilation and decreased survival. During chronic indeterminate infection ablation of fat cells increased cardiac pathology and caused bi-ventricular dilation. These data demonstrate that dysfunctional adipose tissue not only affects cardiac metabolism but also the inflammatory status, morphology and physiology of the myocardium and increases the risk of progression and severity of CCC in murine Chagas disease.

An estimated eight million individuals worldwide are chronically infected with Trypanosoma cruzi, the causative agent of Chagas disease (CD). Of these infected individuals, 30% will develop chronic Chagas cardiomyopathy (CCC), a major cause of morbidity and mortality in CD endemic regions for which there is currently no effective drug or vaccine. The molecular mechanisms underlying CCC pathogenesis, progression and severity are complex, multi-factorial and not completely understood. Earlier, it was demonstrated that T. cruzi persists in adipose tissue, alters adipocyte physiology, and causes loss of body fat mass in T. cruzi infected mice with CCC. In this study, the authors examined the role of visceral fat pad (adipose tissue) in regulating the pathogenic signalling in the development and progression of CCC using a fat mass modulatable transgenic mouse CD model. Loss of fat cells increased cardiac lipid load and deregulated cardiac lipid metabolism leading to mitochondrial oxidative stress and endoplasmic reticulum stress and severe CCC. In addition, loss of fat cells increased cardiac parasite load during acute infection and altered immune signalling in the hearts of infected mice during chronic infection. These discoveries underscore the importance of adipose tissue in the development of CCC.

Increased epicardial adipose tissue thickness associated with increased metabolic risk and the presence of heart failure in patients with Chronic Chagas disease

BACKGROUND

It has been described that Trypanosoma cruzi is capable of promoting metabolic disturbances currently considered as cardiovascular risk factors. Moreover, it has been observed that the protozoa can remain in adipose tissue and alter its immune endocrine functions. The aim of this study was to characterize the thickness of epicardial adipose tissue (EAT) in patients with chronic Chagas disease (CCD) concerning their cardiovascular metabolic risk profile compared with those without CCD.

METHODS

A cross-sectional study was performed including T. cruzi seropositive individuals categorized according to a standard CCD classification and a matched seronegative control group. Complete clinical examination, metabolic laboratory tests and transthoracic echocardiography to assess cardiac function and to quantify EAT were performed.

RESULTS

Fifty-five individuals aged 46.7±11.9 y, 34 with CCD and 21 in the control group, were included. The CCD group presented higher EAT thickness in relation to controls (4.54±1.28 vs 3.22±0.99 mm; p=0.001), which was significantly associated with the presence of insulin resistance (OR=3, 95% CI 1.58 to 5.73; p<0.001). This group presented lower levels of plasmatic adiponectin than controls, especially in those patients with EAT ≥4.5 mm (p=0.005) who also presented with heart failure more frequently (p=0.01).

CONCLUSION

In patients with CCD, a higher EAT thickness is observed and is associated with an increased metabolic risk profile indicated mainly by insulin resistance.

Trypanosoma cruzi down-regulates adiponectin expression in mouse adipocytes via the NFAT signaling pathway

Upon infection by Trypanosoma cruzi, adipocytes adopt a clearly defined inflammatory phenotype with concomitant down-regulation of adiponectin expression, which influences the pathogenesis of Chagas heart disease. Herein, we examined how T. cruzi interferes with transcriptional regulation of adiponectin production in mouse adipocytes. The invading pathogen activates the Ca²⁺/calcineurin/NFATc4 signaling pathway in 3T3-L1 cells. Parasite-induced early activation of NFATc4 is involved in repressing adiponectin expression through recognition of the specific response element located at (-363 to -344) of the gene promoter. Nuclear import of dephosphorylated NFATc4 and decreased adiponectin levels were further demonstrated in white adipose tissue from acutely infected mice. Our current findings point to better clarify the complex role of adipose tissue in the modulation of inflammatory mechanisms operative during T. cruzi infection.

Brucella abortus Infection Modulates 3T3-L1 Adipocyte Inflammatory Response and Inhibits Adipogenesis

Brucellosis is a prevalent global zoonotic infection but has far more impact in developing countries. The adipocytes are the most abundant cell type of adipose tissue and their secreted factors play an important role in several aspects of the innate and adaptive immune response. Here, we demonstrated the ability of Brucella abortus to infect and replicate in both adipocytes and its precursor cells (pre-adipocytes) derived from 3T3-L1 cell line. Additionally, infection of pre-adipocytes also inhibited adipogenesis in a mechanism independent of bacterial viability and dependent on lipidated outer membrane protein (L-Omp19). B. abortus infection was able to modulate the secretion of IL-6 and the matrix metalloproteases (MMPs) -2 and-9 in pre-adipocytes and adipocytes, and also modulated de transcription of adiponectin, leptin, and resistin in differentiated adipocytes. B. abortus-infected macrophages also modulate adipocyte differentiation involving a TNF-α dependent mechanism, thus suggesting a plausible interplay between B. abortus, adipocytes, and macrophages. In conclusion, B. abortus is able to alter adipogenesis process in adipocytes and its precursors directly after their infection, or merely their exposure to the B. abortus lipoproteins, and indirectly through soluble factors released by B. abortus-infected macrophages.