Dehydroepiandrosterone affects Trypanosoma cruzi tissue parasite burdens in rats

Mechanisms behind the high mortality rate in chronic Chagas cardiomyopathy: Unmasking a three-headed monster

Chagas disease is a neglected tropical disease caused by the parasite Trypanosoma cruzi. Chronic Chagas cardiomyopathy (CCC), the most severe form of target organ involvement in Chagas disease, is characterized by a complex pathophysiology and a unique phenotype that differentiates it from other cardiomyopathies, highlighting its worse prognosis compared to other aetiologies of heart failure. The three pathophysiological mechanisms with the largest impact on this differential mortality include rapidly progressive heart failure, a high incidence of stroke, and a high burden of ventricular arrhythmias. However, despite significant advances in understanding the unique molecular circuits underlying these mechanisms, the new knowledge acquired has not been efficiently translated into specific diagnostic and therapeutic approaches for this unique cardiomyopathy. The lack of dedicated clinical trials and the limited CCC-specific risk stratification tools available are evidence of this reality. This review aims to provide an updated perspective of the evidence and pathophysiological mechanisms associated with the higher mortality observed in CCC compared to other cardiomyopathies and highlight opportunities in the diagnostic and therapeutic approaches of the disease.

In vitro, ex vivo and in vivo short-term screening of DHEA nitrate derivatives activity over Trypanosoma cruzi Ninoa and TH strains from Oaxaca State, México

Chagas disease is a health problem that affects millions of persons, currently Nifurtimox (Nfx) and Benznidazole (Bz) are the unique drugs to treat it. However, these drugs produce adverse effects and high toxicity, which has motivated the search for new candidate drugs. Based on reports about the extensive biological activity of steroidal nitrate esters, in this study three nitrate esters steroids (1b, 2b and 4b) were synthetized and characterized from Dehydroepiandrosterone (DHEA, 1a), 19-hydroxy-DHEA (2a), and Androst-5-en-3β,17β-diol (4a), respectively. In addition, compounds 3a and 3b were obtained by introducing an α-ethynyl and a β-hydroxyl groups at position 17 of 2b and further nitration of the hydroxyl group. The trypanocidal activity of these steroids was evaluated in vitro against the epimastigote stage of two T. cruzi strains, Ninoa and TH, and their cytotoxicity over J774.2 macrophage cell line was assayed. Compounds 3a, 3b, and 4a shown higher trypanocidal activity than Bz and Nfx against epimastigotes of Ninoa strain, whereas DHEA (1a) and its nitrate derivative 1b showed higher activity than the reference drugs against the TH strain epimastigote. None of the compounds showed activity in the ex vivo assays against the blood trypomastigote of both strains. Interestingly, the selectivity index of Androst-5-en-3β,17β-diol 4a was almost twice the value of Nfx and 50 times more than Bz, against Ninoa and TH strains, respectively. Therefore, compound 4a could represent a valuable starting point toward the optimization of steroid derivatives as trypanocidal agents.

Immune-neuroendocrine and metabolic disorders in human and experimental T. cruzi infection: New clues for understanding Chagas disease pathology

Studies in mice undergoing acute Trypanosoma cruzi infection and patients with Chagas disease, led to identify several immune-neuroendocrine disturbances and metabolic disorders. Here, we review relevant findings concerning such abnormalities and discuss their possible influence on disease physiopathology.

A Nature-Inspired Design Yields a New Class of Steroids Against Trypanosomatids

Chagas disease and Leishmaniasis are neglected endemic protozoan diseases recognized as public health problems by the World Health Organization. These diseases affect millions of people around the world however, efficient and low-cost treatments are not available. Different steroid molecules with antimicrobial and antiparasitic activity were isolated from diverse organisms (ticks, plants, fungi). These molecules have complex structures that make de novo synthesis extremely difficult. In this work, we designed new and simpler compounds with antiparasitic potential inspired in natural steroids and synthesized a series of nineteen steroidal arylideneketones and thiazolidenehydrazines. We explored their biological activity against Leishmania infantum, Leishmania amazonensis, and Trypanosoma cruzi in vitro and in vivo. We also assayed their genotoxicity and acute toxicity in vitro and in mice. The best compound, a steroidal thiosemicarbazone compound 8 (ID_1260) was active in vitro (IC₅₀ 200 nM) and in vivo (60% infection reduction at 50 mg/kg) in Leishmania and T. cruzi. It also has low toxicity in vitro and in vivo (LD₅₀ >2000 mg/kg) and no genotoxic effects, being a promising compound for anti-trypanosomatid drug development.

The role of melatonin in parasite biology

Regarded as the circadian hormone in mammals, melatonin is a highly conserved molecule, present in nearly all species. In this review, we discuss the role of this indolamine and its precursors in the cell biology of parasites and the role of the molecule in the physiology of the host. In Plasmodium, melatonin can modulate intracellular concentrations of calcium and cAMP, which in turn can regulate kinase activity and cell cycle. In Trypanosoma infections, modulation of the immune system by melatonin is extremely important in controlling the parasite population. Melatonin also contributes to the inflammatory response to Toxoplasma gondii infection. Thus, there are a number of unique adaptations involving intricate connections between melatonin and the biology of the parasite-host relationship.

Prior and concomitant dehydroepiandrosterone treatment affects immunologic response of cultured macrophages infected with Trypanosoma cruzi in vitro?

DHEA, a steroid hormone synthesized from cholesterol by cells of the adrenal cortex, plays an essential role in enhancing the host's resistance to different experimental infections. Receptors for this hormone can be found in distinct immune cells (especially macrophages) that are known to be the first line defense against Trypanosoma cruzi infection. These cells operate through an indirect pathway releasing nitric oxide (NO) and cytokines such TNF-α and IL-12 which in turn trigger an enhancement of natural killer cells and lymphocytes which finally secrete pro and anti-inflammatory cytokines. The effects of pre- and post-infection DHEA treatment on production of IL-12, TNFα and NO were evaluated. T. cruzi infected macrophages post treated with DHEA displayed enhanced concentrations of TNF-α, IL-12 and NO. Probably, the mechanisms that induced the production of cytokines by infected cells are more efficient when the immune system has been stimulated first by parasite invasion, suggesting that the protective role of DHEA is greater when administered post infection.

Melatonin and dehydroepiandrosterone combination: does this treatment exert a synergistic effect during experimental Trypanosoma cruzi infection?

Previous studies showed that melatonin or dehydroepiandrosterone (DHEA) enhances the immune response against parasitic pathogens. The present study investigated the in vitro activity of melatonin combined with DHEA in a period of 24 hr during the course of in vivo T. cruzi infection. The in vitro activity of melatonin or DHEA alone, as well as together, were tested for the trypomastigote forms (doses ranging from 0.5 to 128 microm). In vitro, neither melatonin nor DHEA alone had any activity against trypomastigote forms, although when the highest concentration of combined melatonin and DHEA was used, it was active against the trypomastigote forms of the parasite. However, for this concentration, a quite toxicity on peritoneal macrophages was observed. For in vivo evaluation, male Wistar rats were infected with the Y strain of T. cruzi. They were orally treated with 10 mg/kg body weight/day of melatonin and subcutaneously with 40 mg/kg body weight/day of DHEA. Treatment with melatonin, DHEA and the association showed a significant reduction in the number of blood trypomastigotes during the acute phase of infection as compared to untreated animals (P < 0.05). A significant increase in the number of macrophages and nitric oxide (NO) concentrations were observed during the peak of parasitaemia with melatonin alone or combined with DHEA. However, with DHEA alone the highest concentration of NO was observed (P < 0.05). Moreover, DHEA treatment increased TNF-alpha levels during the infection (P < 0.05). These results show that melatonin, DHEA or the combination of both reduces parasitemia during the acute phase of infection. The combined action of both molecules did not exert a synergic action on the host's ability to fight infection, and it seems that among all treatments DHEA induces a more efficient immune response.

Trypanosoma cruzi: orchiectomy and dehydroepiandrosterone therapy in infected rats

The ability of gonadal hormones to influence and induce diverse immunological functions during the course of a number of parasitic infections has been extensively studied in the latest decades. Dehydroepiandrosterone and its sulfate are the most abundant steroid hormones secreted by the human adrenal cortex and are considered potent immune-activators. The effects of orchiectomy on the course of Trypanosoma cruzi infection in rats, treated and untreated with DHEA were examined, by comparing blood and cardiac parasitism, macrophage numbers, nitric oxide and IFN-gamma levels. Orchiectomy enhanced resistance against infection with elevated numbers of macrophages, enhanced concentrations of NO and IFN-gamma and reduced amastigote burdens in heart when compared to control animals. DHEA replacement exerted a synergistic effect, up-modulating the immune response. Male sex steroids appear to play fundamental role in determining the outcome of disease, through the regulation and modulation of the activity of the immune response.

Dehydroepiandrosterone increases resistance to experimental infection by Trypanosoma cruzi

Dehydroepiandrosterone (DHEA) enhances immune responses against a wide range of viral, bacterial, and parasitic pathogens. In a previous study, we reported that administration of DHEA significantly decreased the numbers of blood parasites in Trypanosoma cruzi experimental infection. The present study was undertaken to determine the effectiveness of DHEA in reducing the severity of acute phase T. cruzi infection of male and female Wistar rats. Animals were treated subcutaneously with 40 mg/kg body weight/day of DHEA. The concentration of nitric oxide (NO) was determined in spleen peritoneal cavity. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were determined in the sera of uninfected and infected animals. DHEA treatment augments NO production for both sexes after in vitro LPS treatment for uninfected animals. Infection triggered enhanced NO levels although not significant. IL-2 and IFN-gamma were detectable in higher concentrations in treated and infected rats of both genders when compared to untreated controls. These data suggest that DHEA may have a potent immunoregulatory function that can affect the course of T. cruzi infection.