Betulinic Acid Derivative BA5, Attenuates Inflammation and Fibrosis in Experimental Chronic Chagas Disease Cardiomyopathy by Inducing IL-10 and M2 Polarization

Subcutaneously transplanted xenogeneic protein recruits treg cells and M2 macrophages to induce browning of inguinal white adipose tissue

OBJECTIVE

To study whether subcutaneously embedding xenogeneic protein threads or synthetic polymer absorbable threads can improve obesity phenotypes and metabolic conditions, and to further explore its underlying mechanism.

METHODS

Thirty-six 8-week-old ob/ob mice were randomly allocated to three groups, respectively, receiving catgut embedding, PGA thread embedding or sham treatment bilaterally to the groin. Individual parameters including weight, food intake, and core temperature are recorded and metabolism assessment, energy expenditure analysis, and PET/CT scanning are also performed at fixed timepoints. After surgical incision, the inguinal white adipose tissue was histologically examined and its expression profile was tested and compared among groups 4 weeks and 12 weeks after operation.

RESULTS

Catgut embedding reduced weight gain and improved metabolic status in ob/ob mice. Browning of bilateral inguinal WAT (white adipose tissue) was induced after catgut embedding, with massive infiltration of Treg cells and M2 macrophages in the tissue slices of fat pads. IL-10 and TGF-β released by Treg cells targeted macrophages and the induced M2 macrophages increased the expression of thermogenic and anti-inflammatory genes in fat. The secretion of catecholamines by polarized M2 macrophages led to the activation of β3-AR-related pathways in adipocytes and the browning of adipose tissue.

CONCLUSIONS

Abdominal subcutaneous catgut embedding has the potential to combat obesity through the induction of WAT browning mediated by infiltrated Treg cells and macrophages.

Anti-Inflammatory Activities of Betulinic Acid: A Review

Inflammatory diseases have a high prevalence and has become of great interest due to the increase in life expectancy and the costs to the health care system worldwide. Chronic diseases require long-term treatment frequently using corticosteroids and non-steroidal anti-inflammatory drugs, which are associated with diverse side effects and risk of toxicity. Betulinic acid, a lupane-type pentacyclic triterpene, is a potential lead compound for the development of new anti-inflammatory treatments, and a large number of derivatives have been produced and tested. The potential of betulinic acid and its derivatives has been shown in a number of pre-clinical studies using different experimental models. Moreover, several molecular mechanisms of action have also been described. Here we reviewed the potential use of betulinic acid as a promissory lead compound with anti-inflammatory activity and the perspectives for its use in the treatment of inflammatory conditions.

Potential of Triterpenic Natural Compound Betulinic Acid for Neglected Tropical Diseases New Treatments

Neglected tropical diseases are one of the most important public health problems in many countries around the world. Among them are leishmaniasis, Chagas disease, and malaria, which contribute to more than 250 million infections worldwide. There is no validated vaccine to prevent these infections and the treatments available are obsolete, highly toxic, and non-effective due to parasitic drug resistance. Additionally, there is a high incidence of these diseases, and they may require hospitalization, which is expensive to the public health systems. Therefore, there is an urgent need to develop new treatments to improve the management of infected people, control the spread of resistant strains, and reduce health costs. Betulinic acid (BA) is a triterpene natural product which has shown antiparasitic activity against Leishmania, Trypanosoma cruzi, and Plasmodium. Here, we review the main results regarding the in vitro and in vivo pharmacological activity of BA and its derivatives against these parasites. Some chemical modifications of BA have been shown to improve its activities against the parasites. Further improvement on studies of drug-derived, as well as structure–activity relationship, are necessary for the development of new betulinic acid-based treatments.

Immunomodulation for the Treatment of Chronic Chagas Disease Cardiomyopathy: A New Approach to an Old Enemy

Chagas disease is a parasitic infection caused by the intracellular protozoan Trypanosoma cruzi. Chronic Chagas cardiomyopathy (CCC) is the most severe manifestation of the disease, developed by approximately 20-40% of patients and characterized by occurrence of arrhythmias, heart failure and death. Despite having more than 100 years of discovery, Chagas disease remains without an effective treatment, especially for patients with CCC. Since the pathogenesis of CCC depends on a parasite-driven systemic inflammatory profile that leads to cardiac tissue damage, the use of immunomodulators has become a rational alternative for the treatment of CCC. In this context, different classes of drugs, cell therapies with dendritic cells or stem cells and gene therapy have shown potential to modulate systemic inflammation and myocarditis in CCC models. Based on that, the present review provides an overview of current reports regarding the use of immunomodulatory agents in treatment of CCC, bringing the challenges and future directions in this field.

Dual chemotherapy with benznidazole at suboptimal dose plus curcumin nanoparticles mitigates Trypanosoma cruzi-elicited chronic cardiomyopathy

Curcumin (Cur) is a natural polyphenolic flavonoid isolated from the rhizomes of Curcuma longa. Its anti-inflammatory and cardioprotective properties are increasingly considered to have beneficial effects on the progression of cardiomyopathy associated with Chagas disease, caused by Trypanosoma cruzi. However, the Cur therapeutic limitation is its bioavailability and new Cur nanomedicine formulations are developed to overcome this obstacle. In this research, we provide evidence showing that oral therapy with a suboptimal dose of the standard parasiticidal drug benznidazole (BZ) in combination with Cur-loaded nanoparticles is capable of reducing myocardial parasite load, cardiac hypertrophy, inflammation and fibrosis in mice with long-term infection by T. cruzi. Treatment with BZ plus Cur was highly effective in downregulating myocardial expression of proinflammatory cytokines/chemokines (IL-1β, TNF-α, IL-6, CCL5), and the level/activity of matrix metalloproteinases (MMP-2, MMP-9) and inducible enzymes (cyclooxygenase, nitric oxide synthase) implicated in leukocyte recruitment and cardiac remodeling. Oral administration of a Cur-based nanoformulation displays potential as a complementary strategy to the conventional BZ chemotherapy in the treatment of chronic Chagas heart disease.

Adding insult to injury - Inflammation at the heart of cardiac fibrosis

The fibrotic response has evolutionary worked in tandem with the inflammatory response to facilitate healing following injury or tissue destruction as a result of pathogen clearance. However, excessive inflammation and fibrosis are key pathological drivers of organ tissue damage. Moreover, fibrosis can occur in several conditions associated with chronic inflammation that are not directly caused by overt tissue injury or infection. In the heart, in particular, fibrotic adverse cardiac remodeling is a key pathological driver of cardiac dysfunction in heart failure. Cardiac fibroblast activation and immune cell activation are two mechanistic domains necessary for fibrotic remodeling in the heart, and, independently, their contributions to cardiac fibrosis and cardiac inflammation have been studied and reviewed thoroughly. The interdependence of these two processes, and how their cellular components modulate each other's actions in response to different cardiac insults, is only recently emerging. Here, we review recent literature in cardiac fibrosis and inflammation and discuss the mechanisms involved in the fibrosis-inflammation axis in the context of specific cardiac stresses, such as myocardial ischemia, and in nonischemic heart conditions. We discuss how the search for anti-inflammatory and anti-fibrotic therapies, so far unsuccessful to date, needs to be based on our understanding of the interdependence of immune cell and fibroblast activities. We highlight that in addition to the extensively reviewed role of immune cells modulating fibroblast function, cardiac fibroblasts are central participants in inflammation that may acquire immune like cell functions. Lastly, we review the gut-heart axis as an example of a novel perspective that may contribute to our understanding of how immune and fibrotic modulation may be indirectly modulated as a potential area for therapeutic research.

IL-10-Dependent and -Independent Mechanisms Are Involved in the Cardiac Pathology Modulation Mediated by Fenofibrate in an Experimental Model of Chagas Heart Disease

IL-10 is an anti-inflammatory cytokine that plays a significant role in the modulation of the immune response in many pathological conditions, including infectious diseases. Infection with Trypanosoma cruzi (T. cruzi), the etiological agent of Chagas disease, results in an ongoing inflammatory response that may cause heart dysfunction, ultimately leading to heart failure. Given its infectious and inflammatory nature, in this work we analyzed whether the lack of IL-10 hinders the anti-inflammatory effects of fenofibrate, a PPARα ligand, in a murine model of Chagas heart disease (CHD) using IL-10 knockout (IL-10 KO) mice. Our results show fenofibrate was able to restore the abnormal cardiac function displayed by T. cruzi-infected mice lacking IL-10. Treatment with fenofibrate reduced creatine kinase (CK) levels in sera of IL-10 KO mice infected with T. cruzi. Moreover, although fenofibrate could not modulate the inflammatory infiltrates developing in the heart, it was able to reduce the increased collagen deposition in infected IL-10 KO mice. Regarding pro-inflammatory mediators, the most significant finding was the increase in serum IL-17. These were reduced in IL-10 KO mice upon fenofibrate treatment. In agreement with this, the expression of RORγt was reduced. Infection of IL-10 KO mice increased the expression of YmI, FIZZ and Mannose Receptor (tissue healing markers) that remained unchanged upon treatment with fenofibrate. In conclusion, our work emphasizes the role of anti-inflammatory mechanisms to ameliorate heart function in CHD and shows, for the first time, that fenofibrate attains this through IL-10-dependent and -independent mechanisms.

Inhibition of SREBP Improves Cardiac Lipidopathy, Improves Endoplasmic Reticulum Stress, and Modulates Chronic Chagas Cardiomyopathy

Background Trypanosoma cruzi is an intracellular parasite that causes debilitating chronic Chagas cardiomyopathy (CCM), for which there is no effective drug or vaccine. Previously, we demonstrated increased cardiac lipid accumulation and endoplasmic reticulum stress in mice with CCM. Increased endoplasmic reticulum stress may lead to uncontrolled SREBP (sterol regulatory element-binding protein) activation and lipotoxicity in the myocardium during the intermediate stage of infection and result in progression to chronic CCM. Therefore, we investigated whether inhibiting SREBP activation modulates CCM progression in T cruzi-infected mice. Methods and Results T cruzi-infected cultured cardiomyocytes (3:1 multiplicity of infection; 24 hours postinfection) were incubated with betulin (3 μmol/L per mL), an SREBP inhibitor, for 24 hours. Quantitative polymerase chain reaction and Western blotting analyses demonstrated a significant reduction in SREBP activation, lipid biosynthesis, and endoplasmic reticulum stress in betulin-treated infected cells compared with untreated cells. T cruzi infected (10³ trypomastigotes of the Brazil strain) Swiss mice were fed a customized diet containing betulin during the intermediate stage (40 days postinfection) until the chronic stage (120 DPI). Cardiac ultrasound imaging and histological and biochemical analyses demonstrated anatomical and functional improvements in betulin-treated, infected mice compared with untreated controls: we observed a significant reduction in cholesterol/fatty acid synthesis that may result in the observed cardiac reduction in cardiac lipid accumulation, mitochondrial and endoplasmic reticulum stress, and ventricular enlargement. Conclusions Our study (in vitro and vivo) demonstrates that inhibition of cardiac SREBP activation reduces cardiac damage during T cruzi infection and modulates CCM in a murine Chagas model.