A polyvalent RNA vaccine reduces the immune imprinting phenotype in mice and induces neutralizing antibodies against omicron SARS-CoV-2

Immune imprinting is now evident in COVID-19 vaccinated people. This phenomenon may impair the development of effective neutralizing antibodies against variants of concern (VoCs), mainly Omicron and its subvariants. Consequently, the boost doses with bivalent vaccines have not shown a significant gain of function regarding the neutralization of Omicron. The approach to design COVID-19 vaccines must be revised to improve the effectiveness against VoCs. Here, we took advantage of the self-amplifying characteristic of RepRNA and developed a polyvalent formulation composed of mRNA from five VoCs. LION/RepRNA Polyvalent induced neutralizing antibodies in mice previously immunized with LION/RepRNA D614G and reduced the imprinted phenotype associated with low neutralization capacity of Omicron B.1.1.529 pseudoviruses. The polyvalent vaccine can be a strategy to handle the low neutralization of Omicron VoC, despite booster doses with either monovalent or bivalent vaccines.

Therapeutic Potential of Natural Products in the Treatment of Schistosomiasis

It is estimated that 250 million people worldwide are affected by schistosomiasis. Disease transmission is related to the poor sanitation and hygiene habits that affect residents of impoverished regions in tropical and subtropical countries. The main species responsible for causing disease in humans are Schistosoma Mansoni, S. japonicum, and S. haematobium, each with different geographic distributions. Praziquantel is the drug predominantly used to treat this disease, which offers low effectiveness against immature and juvenile parasite forms. In addition, reports of drug resistance prompt the development of novel therapeutic approaches. Natural products represent an important source of new compounds, especially those obtained from plant sources. This review compiles data from several in vitro and in vivo studies evaluating various compounds and essential oils derived from plants with cercaricidal and molluscicidal activities against both juvenile and adult forms of the parasite. Finally, this review provides an important discussion on recent advances in molecular and computational tools deemed fundamental for more rapid and effective screening of new compounds, allowing for the optimization of time and resources.

Molecular Hybridization Strategy on the Design, Synthesis, and Structural Characterization of Ferrocene-N-acyl Hydrazones as Immunomodulatory Agents

Immunomodulatory agents are widely used for the treatment of immune-mediated diseases, but the range of side effects of the available drugs makes necessary the search for new immunomodulatory drugs. Here, we investigated the immunomodulatory activity of new ferrocenyl-N-acyl hydrazones derivatives (SintMed(141−156). The evaluated N-acyl hydrazones did not show cytotoxicity at the tested concentrations, presenting CC50 values greater than 50 µM. In addition, all ferrocenyl-N-acyl hydrazones modulated nitrite production in immortalized macrophages, showing inhibition values between 14.4% and 74.2%. By presenting a better activity profile, the ferrocenyl-N-acyl hydrazones SintMed149 and SintMed150 also had their cytotoxicity and anti-inflammatory effect evaluated in cultures of peritoneal macrophages. The molecules were not cytotoxic at any of the concentrations tested in peritoneal macrophages and were able to significantly reduce (p < 0.05) the production of nitrite, TNF-α, and IL-1β. Interestingly, both molecules significantly reduced the production of IL-2 and IFN-γ in cultured splenocytes activated with concanavalin A. Moreover, SintMed150 did not show signs of acute toxicity in animals treated with 50 or 100 mg/kg. Finally, we observed that ferrocenyl-N-acyl hydrazone SintMed150 at 100 mg/kg reduced the migration of neutrophils (44.6%) in an acute peritonitis model and increased animal survival by 20% in an LPS-induced endotoxic shock model. These findings suggest that such compounds have therapeutic potential to be used to treat diseases of inflammatory origin.

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.

Therapeutic Applications of Physalins: Powerful Natural Weapons

Physalins, or 16,24-cyclo-13,14-seco steroids, are compounds belonging to the class of withanolides that can be found in plants of Solanaceae family, mainly in species belonging to the genus Physalis spp., which are annual herbaceous plants widely distributed in tropical and subtropical regions of the world. Physalins are versatile molecules that act in several cell signaling pathways and activate different mechanisms of cell death or immunomodulation. A number of studies have shown a variety of actions of these compounds, including anticancer, anti-inflammatory, antiparasitic, antimicrobial, antinociceptive, and antiviral activities. Here we reviewed the main findings related to the anticancer, immunomodulatory, and antiparasitic activities of physalins and its mechanisms of action, highlighting the \challenges and future directions in the pharmacological application of physalins.

Structural Design, Synthesis and Antioxidant, Antileishmania, Anti-Inflammatory and Anticancer Activities of a Novel Quercetin Acetylated Derivative

Quercetin (Q) is a bioflavonoid with biological potential; however, poor solubility in water, extensive enzymatic metabolism and a reduced bioavailability limit its biopharmacological use. The aim of this study was to perform structural modification in Q by acetylation, thus, obtaining the quercetin pentaacetate (Q5) analogue, in order to investigate the biological potentials (antioxidant, antileishmania, anti-inflammatory and cytotoxicity activities) in cell cultures. Q5 was characterized by FTIR, ¹H and ¹³C NMR spectra. The antioxidant potential was evaluated against the radical ABTS^•+. The anti-inflammatory potential was evaluated by measuring the pro-inflammatory cytokine tumor necrosis factor (TNF) and the production of nitric oxide (NO) in peritoneal macrophages from BALB/c mice. Cytotoxicity tests were performed using the AlamarBlue method in cancer cells HepG2 (human hepatocarcinoma), HL-60 (promyelocytic leukemia) and MCR-5 (healthy human lung fibroblasts) as well as the MTT method for C6 cell cultures (rat glioma). Q and Q5 showed antioxidant activity of 29% and 18%, respectively, which is justified by the replacement of hydroxyls by acetyl groups. Q and Q5 showed concentration-dependent reductions in NO and TNF production (p < 0.05); Q and Q5 showed higher activity at concentrations > 40µM when compared to dexamethasone (20 µM). For the HL-60 lineage, Q5 demonstrated selectivity, inducing death in cancer cells, when compared to the healthy cell line MRC-5 (IC₅₀ > 80 µM). Finally, the cytotoxic superiority of Q5 was verified (IC₅₀ = 11 µM), which, at 50 µM for 24 h, induced changes in the morphology of C6 glioma cells characterized by a round body shape (not yet reported in the literature). The analogue Q5 had potential biological effects and may be promising for further investigations against other cell cultures, particularly neural ones.

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.

The protective effect of solidagenone from Solidago chilensis Meyen in a mouse model of airway inflammation

Solidagenone is the main active constituent present in Solidago chilensis Meyen which is used in folk medicine to treat pain and inflammatory diseases. This study aimed to evaluate the anti-inflammatory activity of solidagenone in vitro and in a model of allergic airway inflammation. In vitro studies were performed in activated macrophages and lymphocytes. BALB/c mice were sensitized and challenged with ovalbumin and treated with solidagenone orally (30 or 90 mg/kg body weight) or dexamethasone, as a positive control in our in vivo analysis. Supernatant concentrations of nitrite, TNF and IL-1β, as well as gene expression of pro-inflammatory mediators in macrophages cultures, were reduced after solidagenone treatment, without affecting macrophages viability. Besides, solidagenone significantly decreased T cell proliferation and secretion of IFNγ and IL-2. Th2 cytokine concentrations and inflammatory cell counts, especially eosinophils, in bronchoalveolar lavage fluid were reduced in mice treated with solidagenone. Histopathological evaluation of lung tissue was performed, and morphometrical analyses demonstrated reduction of cellular infiltration and mucus hypersecretion. Altogether, solidagenone presented anti-inflammatory activity in vitro and in vivo in the OVA-induced airway inflammation model, suggesting its promising pharmacological use as an anti-inflammatory agent for allergic hypersensitivity.

Prevalence of burnout syndrome and associated factors in university professors working in Salvador, state of Bahia

INTRODUCTION:

Burnout syndrome is a phenomenon characterized by chronic emotional exhaustion that can lead to physical, psychological, and social consequences. Because they need to support themselves financially, university professors have accepted increasingly longer working hours and accumulated duties, resulting in greater exposure to factors that may induce the onset of mental disorders such as burnout syndrome.

OBJECTIVES:

This cross-sectional epidemiological study aimed to determine the prevalence of burnout syndrome and predisposing factors in university professors working in Salvador, Brazil.

METHODS:

The sample consisted of 210 participants. The Maslach Burnout Inventory adapted for teachers, the gold standard for detecting burnout syndrome, and a sociodemographic questionnaire were administered to identify variables that may influence the development of burnout. Then, the data were compiled in Excel and analyzed with the aid of GraphPad Prism.

RESULTS:

The prevalence of burnout was 41% (n = 86). A stratified data analysis showed that being under 40 years of age, being single, being childless, teaching natural sciences, and working at several institutions are risk factors for developing burnout syndrome.

CONCLUSIONS:

The prevalence of burnout syndrome in university professors was 41%. Professors who were young, single, childless, taught natural sciences, and worked at more than one institution were found to be more likely to develop burnout syndrome.

Ozonized Water in Microbial Control: Analysis of the Stability, In Vitro Biocidal Potential, and Cytotoxicity

O3 dissolved in water (or ozonized water) has been considered a potent antimicrobial agent, and this study aimed to test this through microbiological and in vitro assays. The stability of O3 was accessed following modifications of the physicochemical parameters of water, such as the temperature and pH, with or without buffering. Three concentrations of O3 (0.4, 0.6, and 0.8 ppm) dissolved in water were tested against different microorganisms, and an analysis of the cytotoxic effects was also conducted using the human ear fibroblast cell line (Hfib). Under the physicochemical conditions of 4 °C and pH 5, O3 remained the most stable and concentrated compared to pH 7 and water at 25 °C. Exposure to ozonized water resulted in high mortality rates for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, and Candida albicans. Scanning electron micrograph images indicate that the effects on osmotic stability due to cell wall lysis might be one of the killing mechanisms of ozonized water. The biocidal agent was biocompatible and presented no cytotoxic effect against Hfib cells. Therefore, due to its cytocompatibility and biocidal action, ozonized water can be considered a viable alternative for microbial control, being possible, for example, its use in disinfection processes.

In vitro and In Vivo Immunomodulatory Activity of Physalis angulata Concentrated Ethanolic Extract

The need for new immunomodulatory drugs is due to the side effects associated with the prolonged use of the currently used immunomodulatory drugs. In this context, the present work aimed to investigate the immunomodulatory effect of an ethanolic concentrated extract from Physalis angulata. The cytotoxicity of samples was determined using peritoneal macrophages though the Alamar Blue assay. The immunomodulatory activity of the ethanolic extract from P. angulata on activated macrophages was determined by measurement of nitrite and cytokine production. The immunosuppressive effects of the ethanolic extract from P. angulata was evaluated on lymphocyte proliferation and cytokine production. The effects of the extract on cell cycle progression and cell death on lymphocytes were evaluated by flow cytometry. Lastly, the ethanolic extract from P. angulata was tested in vivo in toxicological tests and in models of peritonitis and delayed-type hypersensitivity response. The ethanolic extract from P. angulata decreased nitrite, interleukin-6, interleukin-12, and TNF-α production by activated macrophages without affecting the cell viability. In addition, the ethanolic extract from P. angulata inhibited lymphoproliferation and the secretion of interleukin-2, interleukin-6, and IFN-γ, and increased interleukin-4 secretion by activated splenocytes. Flow cytometry analysis in lymphocyte cultures showed that treatment with the ethanolic extract from P. angulata induces cell cycle arrest in the G1 phase followed by cell death by apoptosis. Moreover, mice treated with the extract from P. angulata at 100 or 200 mg/kg did not show signs of toxicity or alterations in serum components. Finally, the ethanolic extract from P. angulata significantly reduced neutrophil migration and reduced paw edema in bovine serum albumin-induced the delayed-type hypersensitivity response model. Our results demonstrate the potential of the ethanolic extract of P. angulata as an alternative for the treatment of immune-inflammatory diseases.

Inhibition of intracellular Ca2+ mobilization and potassium channels activation are involved in the vasorelaxation induced by 7-hydroxycoumarin

Coumarins exhibit a wide variety of biological effects, including activities in the cardiovascular system and the aim of this study was to evaluate the vascular therapeutic potential of 7-Hydroxicoumarin (7-HC). The vascular effects induced by 7-HC (0.001 μM-300 μM), were investigated by in vitro approaches using isometric tension measurements in rat superior mesenteric arteries and by in silico assays using Ligand-based analysis. Our results suggest that the vasorelaxant effect of 7-HC seems to rely on potassium channels, notably through large conductance Ca²⁺-activated K⁺ (BK_Ca) channels activation. In fact, 7-HC (300 μM) significantly reduced CaCl₂-induced contraction as well as the reduction of intracellular calcium mobilization. However, the relaxation induced by 7-HC was independent of store-operated calcium entry (SOCE). Moreover, in silico analysis suggests that potassium channels have a common binding pocket, where 7-HC may bind and hint that its binding profile is more similar to quinine's than verapamil's. These results are compatible with the inhibition of Ca²⁺ release from intracellular stores, which is prompted by phenylephrine and caffeine. Taken together, these results demonstrate a therapeutic potential of 7-HC on the cardiovascular system, making it a promising lead compound for the development of drugs useful in the treatment of cardiovascular diseases.

Phenylpropanoids from Croton velutinus with cytotoxic, trypanocidal and anti-inflammatory activities

This current study presents the phytochemical analysis of Croton velutinus, describing phenylpropanoids obtained from this species. The fractionation of the roots hexane extract led to the isolation of four new phenylpropanoids derivatives, velutines A-D (1-4) and three known (5-7). Their structures were established based on spectroscopic (1D-2D NMR; HRMS and IR) analysis. Cytotoxic, trypanocidal and anti-inflammatory activities of compounds 1-7 were evaluated. Only compounds 2 and 5 showed cytotoxic activity against cancer cell lines (B16F10, HL-60, HCT116, MCF-7 and HepG2), with IC₅₀ values ranging from 6.8 to 18.3 μM and 11.1 to 18.3 μM, respectively. Compounds 2 and 5 also showed trypanocidal activity against bloodstream trypomastigotes with EC₅₀ values of 9.0 and 9.58 μM, respectively. Finally, the anti-inflammatory potential of these compounds was evaluated on cultures of activated macrophages. All compounds exhibited concentration-dependent suppressive activity on the production of nitrite and IL-1β by macrophages stimulated with LPS and IFN-γ. These results indicate phenylpropanoids esters (2 and 5) from C. velutinus as promising cytotoxic, trypanocidal and anti-inflammatory candidates that warrants further studies.

Mesenchymal Stem Cells and Atopic Dermatitis: A Review

Mesenchymal stem/stromal cells (MSCs) are stromal-derived non-hematopoietic progenitor cells that reside in and can be expanded from various tissues sources of adult and neonatal origin, such as the bone marrow, umbilical cord, umbilical cord blood, adipose tissue, amniotic fluid, placenta, dental pulp and skin. The discovery of the immunosuppressing action of MSCs on T cells has opened new perspectives for their use as a therapeutic agent for immune-mediated disorders, including allergies. Atopic dermatitis (AD), a chronic and relapsing skin disorder that affects up to 20% of children and up to 3% of adults worldwide, is characterized by pruritic eczematous lesions, impaired cutaneous barrier function, Th2 type immune hyperactivation and, frequently, elevation of serum immunoglobulin E levels. Although, in the dermatology field, the application of MSCs as a therapeutic agent was initiated using the concept of cell replacement for skin defects and wound healing, accumulating evidence have shown that MSC-mediated immunomodulation can be applicable to the treatment of inflammatory/allergic skin disorders. Here we reviewed the pre-clinical and clinical studies and possible biological mechanisms of MSCs as a therapeutic tool for the treatment of atopic dermatitis.

Tolerogenic Dendritic Cells Reduce Cardiac Inflammation and Fibrosis in Chronic Chagas Disease

Chronic Chagas disease cardiomyopathy (CCC) is the most frequent and severe form of this parasitic disease. CCC is caused by a progressive inflammation in the heart, resulting in alterations that can culminate in heart failure and death. The use of dendritic cells (DCs) appears as an option for the development of treatments due to their important role in regulating immune responses. Here, we investigated whether tolerogenic cells (tDCs) could interfere with the progression of CCC in an experimental model of Chagas disease. The tDCs were generated and characterized as CD11b⁺ CD11c⁺ cells, low expression of MHC-II, CD86, CD80, and CD40, and increased expression of PD-L. These cells produced low levels of IL-6 and IL-12p70 and higher levels of IL-10, compared to mature DCs (mDCs). Interestingly, tDCs inhibited lymphoproliferation and markedly increased the population of FoxP3⁺ Treg cells in vitro, compared to mature DCs. In a mouse model of CCC, treatment with tDCs reduced heart inflammation and fibrosis. Furthermore, tDCs treatment reduced the gene expression of pro-inflammatory cytokines (Ifng and Il12) and of genes related to cardiac remodeling (Col1a2 and Lgals3), while increasing the gene expression of IL-10. Finally, administration of tDCs, increased the percentage of Treg cells in the hearts and spleens of chagasic mice. Ours results show that tolerogenic dendritic cells have therapeutic potential on CCC, inhibiting disease progression.

Development and in vitro characterization of polymeric nanoparticles containing recombinant adrenomedullin-2 intended for therapeutic angiogenesis

Cardiovascular diseases (CVD) are the leading cause of death worldwide. Growth factor therapy has emerged as novel therapeutic strategy under investigation for CVD. In this sense, adrenomedullin-2 (ADM-2) has been recently identified as a new angiogenic factor able to regulate the regional blood flow and cardiovascular function. However, the therapeutic value of ADM-2 is limited by its short biological half-life and low plasma stability. Poly (lactic-co-glycolic acid) (PLGA) micro- and nanoparticles have been investigated as growth factor delivery systems for cardiac repair. In this study, we aimed to develop PLGA nanoparticles containing ADM-2 intended for therapeutic angiogenesis. PLGA nanoparticles containing ADM-2 were prepared by a double emulsion modified method, resulting in 300 nm-sized stable particles with zeta potential around - 30 mV. Electron microscopy analysis by SEM and TEM revealed spherical particles with a smooth surface. High encapsulation efficiency was reached (ca.70%), as quantified by ELISA. ADM-2 associated to polymer nanoparticles was also determined by EDS elemental composition analysis, SDS-PAGE and LC-MS/MS for peptide identification. In vitro release assays showed the sustained release of ADM-2 from polymer nanoparticles for 21 days. Cell viability experiments were performed in J774 macrophages and H9c2 cardiomyocyte cells, about which PLGA nanoparticles loaded with ADM-2 did not cause toxicity in the range 0.01-1 mg/ml. Of note, encapsulated ADM-2 significantly induced cell proliferation in EA.hy926 endothelial cells, indicating the ADM-2 bioactivity was preserved after the encapsulation process. Collectively, these results demonstrate the feasibility of using PLGA nanoparticles as delivery systems for the angiogenic peptide ADM-2, which could represent a novel approach for therapeutic angiogenesis in CVD using growth factor therapy.

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

Chronic Chagas disease cardiomyopathy (CCC) is a major cause of heart disease in Latin America and treatment for this condition is unsatisfactory. Here we investigated the effects of BA5, an amide semi-synthetic derivative betulinic acid, in a model of CCC. Mice chronically infected with T. cruzi were treated orally with BA5 (10 or 1 mg/Kg), three times per week, for 2 months. BA5 treatment decreased inflammation and fibrosis in heart sections but did not improve exercise capacity or ameliorate cardiac electric disturbances in infected mice. Serum concentrations of TNF-α, IFN-γ, and IL-1β, as well as cardiac gene expression of pro-inflammatory mediators, were reduced after BA5 treatment. In contrast, a significant increase in the anti-inflammatory cytokine IL-10 concentration was observed in BA5-treated mice in both tested doses compared to vehicle-treated mice. Moreover, polarization to anti-inflammatory/M2 macrophage phenotype was evidenced by a decrease in the expression of NOS2 and proinflammatory cytokines and the increase in M2 markers, such as Arg1 and CHI3 in mice treated with BA5. In conclusion, BA5 had a potent anti-inflammatory activity on a model of parasite-driven heart disease related to IL-10 production and a switch from M1 to M2 subset of macrophages.

Indirubin derivatives are potent and selective anti-Trypanosoma cruzi agents

Current treatment for combatting Chagas disease, a life-threatening illness caused by the kinetoplastid protozoan parasite Trypanosoma cruzi is inadequate, and thus the discovery of new antiparasitic compounds is of prime importance. Previous studies identified the indirubins, a class of ATP kinase inhibitors, as potent growth inhibitors of the related kinetoplastid Leishmania. Herein, we evaluated the inhibitory activity of a series of 69 indirubin analogues screened against T. cruzi trypomastigotes and intracellular amastigotes. Seven indirubins were identified as potent T. cruzi inhibitors (low μΜ, nM range). Cell death analysis of specific compounds [3'oxime-6-bromoindirubin(6-BIO) analogues 10, 11 and 17, bearing a bulky extension on the oxime moiety and one 7 substituted analogue 32], as evaluated by electron microscopy and flow cytometry, showed a different mode of action between compound 32 compared to the three 6-BIO oxime- substituted indirubins, suggesting that indirubins may kill the parasite by different mechanisms dependent on their substitution. Moreover, the efficacy of four compounds that show the most potent anti-parasitic effect in both trypomastigotes and intracellular amastigotes (10, 11, 17, 32), was evaluated in a mouse model of T. cruzi infection. Compound 11 (3ʹpiperazine-6-BIO) displayed the best in vivo efficacy (1/6 mortality, 94.5% blood parasitaemia reduction, 12 dpi) at a dose five times reduced over the reference drug benznidazole (20 mg/kg vs100 mg/kg). We propose 3ʹpiperazine-6-BIO as a potential lead for the development of new treatments of Chagas disease.

Potent immunosuppressive activity of a phosphodiesterase-4 inhibitor N-acylhydrazone in models of lipopolysaccharide-induced shock and delayed-type hypersensitivity reaction

Immunosuppressive drugs are widely used for the treatment of immune-mediated diseases and inflammation, but the toxicity and side effects of the available immunosuppressors make the search of new agents of great relevance. Here, we evaluated the immunomodulatory activity of an N-acylhydrazone derivative, (E)-N'-(3,4-dimethoxybenzylidene)-4-methoxybenzohydrazide (LASSBio-1386), a phosphodiesterase-4 (PDE-4) inhibitor. LASSBio-1386 inhibited lymphocyte activation in a concentration-dependent fashion, decreasing lymphoproliferation and IFN-γ and IL-2 production stimulated by anti-CD3/CD28 mAbs or concanavalin A (Con A) and inducing cell-cycle arrest in the G0/G1 phase. These effects were not blocked by RU486, a glucocorticoid receptor (GR) antagonist, indicating an effect independent of glucocorticoid receptor activation. Combination index-isobologram analysis indicates a synergistic effect between LASSBio-1386 and dexamethasone in lymphoproliferation inhibition. LASSBio-1386 presented immunomodulatory action in macrophage cultures, as observed by a significant and concentration-dependent decrease in NO and TNF-α production, an effect achieved by reducing IĸB expression and NF-κB activation. In the mouse model of endotoxic shock, LASSBio-1386 at 50 and 100 mg/kg protected 50 and 85% of mice against LPS-induced lethality, respectively. In agreement to its in vitro action, treatment with 100 mg/kg of LASSBio-1386 reduced TNF-α and IL-1β serum levels, while increased IL-6 and IL-10. Finally, LASSBio-1386 reduced the paw edema in a BSA-induced delayed-type hypersensitivity model. These findings demonstrate the immunomodulatory and immunosuppressant effects of LASSBio-1386 and indicate this molecule is a promising pharmacologic agent for immune-mediated diseases.

Erratum: Tolerogenic Dendritic Cells Reduce Airway Inflammation in a Model of Dust Mite Triggered Allergic Inflammation

This corrects the article on p. 406 in vol. 10, PMID: 29949837.

Tolerogenic Dendritic Cells Reduce Airway Inflammation in a Model of Dust Mite Triggered Allergic Inflammation

PURPOSE

The use of tolerogenic dendritic cells (TolDCs) to control exacerbated immune responses may be a prophylactic and therapeutic option for application in autoimmune and allergic conditions. The objective of this work was to evaluate the effects of TolDC administration in a mouse model of allergic airway inflammation caused by mite extract.

METHODS

Mouse bone marrow-derived TolDCs were induced by incubation with granulocyte-macrophage colony-stimulating factor (GM-CSF) and dexamethasone, and then characterized by flow cytometry and cytokine production by enzyme-linked immunosorbent assay (ELISA). For the in vivo model of Blomia tropicalis-induced allergy, mice transplanted with antigen-pulsed TolDCs were sensitized intraperitoneally with B. tropicalis mite extract (BtE) adsorbed to aluminium hydroxide. After challenge by nasal administration of BtE, bronchoalveolar lavage fluid (BALF), lungs, spleen and serum were collected for analysis.

RESULTS

Induction of TolDCs was efficiently achieved as shown by low expression of major histocompatibility complex (MHC) II, programmed death-ligand (PD-L) 2 and pro-inflammatory cytokine production, and up-regulation of interleukin (IL)-10, upon LPS stimulation in vitro. Transplantation of 1 or 2 doses of BtE-pulsed TolDCs reduced the number of inflammatory cells in BALF and lungs as well as mucus deposition. Moreover, compared to saline-injected controls, TolDC-treated mice showed lower serum levels of anti-BtE immunoglobulin E (IgE) antibodies as well as reduced Gata3 and IL-4 gene expression in the lungs and decreased IFN-γ levels in the supernatant of splenocyte cultures Transplantation of TolDCs increased the percentage of the regulatory T cells in the spleen and the lungs.

CONCLUSIONS

Preventive treatment with TolDCs protects against dust mite-induced allergy in a mouse model, reinforcing the use of tolerogenic dendritic cells for the management of allergic conditions.

Structural design, synthesis and pharmacological evaluation of thiazoles against Trypanosoma cruzi

Chagas disease is one of the most significant health problems in the American continent. benznidazole (BDZ) and nifurtimox (NFX) are the only drugs approved for treatment and exhibit strong side effects and ineffectiveness in the chronic stage, besides different susceptibility among T. cruzi DTUs (Discrete Typing Units). Therefore, new drugs to treat this disease are necessary. Thiazole compounds have been described as potent trypanocidal agents. Here we report the structural planning, synthesis and anti-T. cruzi evaluation of a new series of 1,3-thiazoles (7-28), which were designed by placing this heterocycle instead of thiazolidin-4-one ring. The synthesis was conducted in an ultrasonic bath with 2-propanol as solvent at room temperature. By varying substituents attached to the phenyl and thiazole rings, substituents were observed to retain, enhance or greatly increase their anti-T. cruzi activity. In some cases, methyl at position 5 of the thiazole (compounds 9, 12 and 23) increased trypanocidal property. The exchange of phenyl for pyridinyl heterocycle resulted in increased activity, giving rise to the most potent compound against the trypomasigote form (14, IC_50trypo = 0.37 μM). Importantly, these new thiazoles were toxic for trypomastigotes without affecting macrophages and cardiomyoblast viability. The compounds were also evaluated against cruzain, and five of the most active compounds against trypomastigotes (7, 9, 12, 16 and 23) inhibited more than 70% of enzymatic activity at 10 μM, among which compound 7 had an IC₅₀ in the submicromolar range, suggesting a possible mechanism of action. In addition, examination of T. cruzi cell death showed that compound 14 induces apoptosis. We also examined the activity against intracellular parasites, revealing that compound 14 inhibited T. cruzi infection with potency similar to benznidazole. The antiparasitic effect of 14 and benznidazole in combination was also investigated against trypomastigotes and revealed that they have synergistic effects, showing a promising profile for drug combination. Finally, in mice acutely-infected with T. cruzi,14 treatment significanty reduced the blood parasitaemia and had a protective effect on mortality. In conclusion, we report the identification of compounds (7), (12), (15), (23) and (26) with similar trypanocidal activity of benznidazole; compounds (9) and (21) as trypanocidal agents equipotent with BDZ, and compound 14 with potency 28 times better than the reference drug without affecting macrophages and cardiomyoblast viability. Mechanistically, the compounds inhibit cruzain, and 14 induces T. cruzi cell death by an apoptotic process, being considered a good starting point for the development of new anti-Chagas drug candidates.

Betulinic acid derivative BA5, a dual NF-kB/calcineurin inhibitor, alleviates experimental shock and delayed hypersensitivity

Betulinic acid (BA) is a naturally occurring triterpenoid with several biological properties already described, including immunomodulatory activity. Here we investigated the immunomodulatory activity of eight semi-synthetic amide derivatives of betulinic acid. Screening of derivatives BA1-BA8 led to the identification of compounds with superior immunomodulatory activity than BA on activated macrophages and lymphocytes. BA5, the most potent derivative, inhibited nitric oxide and TNFα production in a concentration-dependent manner, and decreased NF-κB activation in Raw 264.7 cells. Additionally, BA5 inhibited the proliferation of activated lymphocytes and the secretion of IL-2, IL-4 IL-6, IL-10, IL-17A and IFNɣ, in a concentration-dependent manner. Flow cytometry analysis in lymphocyte cultures showed that treatment with BA5 induces cell cycle arrest in pre-G1 phase followed by cell death by apoptosis. Moreover, BA5 also inhibited the activity of calcineurin, an enzyme that plays a critical role in the progression of cell cycle and T lymphocyte activation. BA5 has a synergistic inhibitory effect with dexamethasone on lymphoproliferation, showing a promising profile for drug combination. Finally, we observed immunosuppressive effects of BA5 in vivo in mouse models of lethal endotoxemia and delayed type hypersensitivity. Our results reinforce the potential use of betulinic acid and its derivatives in the search for potent immunomodulatory drugs.

Therapeutic effects of sphingosine kinase inhibitor N,N-dimethylsphingosine (DMS) in experimental chronic Chagas disease cardiomyopathy

Chagas disease cardiomyopathy is a parasite-driven inflammatory disease to which there are no effective treatments. Here we evaluated the therapeutic potential of N,N-dimethylsphingosine(DMS), which blocks the production of sphingosine-1-phosphate(S1P), a mediator of cellular events during inflammatory responses, in a model of chronic Chagas disease cardiomyopathy. DMS-treated, Trypanosoma cruzi-infected mice had a marked reduction of cardiac inflammation, fibrosis and galectin-3 expression when compared to controls. Serum concentrations of galectin-3, IFNγ and TNFα, as well as cardiac gene expression of inflammatory mediators were reduced after DMS treatment. The gene expression of M1 marker, iNOS, was decreased, while the M2 marker, arginase1, was increased. DMS-treated mice showed an improvement in exercise capacity. Moreover, DMS caused a reduction in parasite load in vivo. DMS inhibited the activation of lymphocytes, and reduced cytokines and NO production in activated macrophage cultures in vitro, while increasing IL-1β production. Analysis by qRT-PCR array showed that DMS treatment modulated inflammasome activation induced by T. cruzi on macrophages. Altogether, our results demonstrate that DMS, through anti-parasitic and immunomodulatory actions, can be beneficial in the treatment of chronic phase of T. cruzi infection and suggest that S1P-activated processes as possible therapeutic targets for the treatment of Chagas disease cardiomyopathy.

Antiparasitic evaluation of betulinic acid derivatives reveals effective and selective anti-Trypanosoma cruzi inhibitors

Betulinic acid is a pentacyclic triterpenoid with several biological properties already described, including antiparasitic activity. Here, the anti-Trypanosoma cruzi activity of betulinic acid and its semi-synthetic amide derivatives (BA1-BA8) was investigated. The anti-Trypanosoma cruzi activity and selectivity were enhanced in semi-synthetic derivatives, specially on derivatives BA5, BA6 and BA8. To understand the mechanism of action underlying betulinic acid anti-T. cruzi activity, we investigated ultrastructural changes by electron microscopy. Ultrastructural studies showed that trypomastigotes incubated with BA5 had membrane blebling, flagella retraction, atypical cytoplasmic vacuoles and Golgi cisternae dilatation. Flow cytometry analysis showed that parasite death is mainly caused by necrosis. Treatment with derivatives BA5, BA6 or BA8 reduced the invasion process, as well as intracellular parasite development in host cells, with a potency and selectivity similar to that observed in benznidazole-treated cells. More importantly, the combination of BA5 and benznidazole revealed synergistic effects on trypomastigote and amastigote forms of T. cruzi. In conclusion, we demonstrated that BA5 compound is an effective and selective anti-T. cruzi agent.

In vitro and in vivo antiparasitic activity of Physalis angulata L. concentrated ethanolic extract against Trypanosoma cruzi

BACKGROUND

The current treatment of Chagas disease, endemic in Latin America and emerging in several countries, is limited by the frequent side effects and variable efficacy of benznidazole. Natural products are an important source for the search for new drugs.

AIM/HYPOTHESIS

Considering the great potential of natural products as antiparasitic agents, we investigated the anti-Trypanosoma cruzi activity of a concentrated ethanolic extract of Physalis angulata (EEPA).

METHODS

Cytotoxicity to mammalian cells was determined using mouse peritoneal macrophages. The antiparasitic activity was evaluated against axenic epimastigote and bloodstream trypomastigote forms of T. cruzi, and against amastigote forms using T. cruzi-infected macrophages. Cell death mechanism was determined in trypomastigotes by flow cytometry analysis after annexin V and propidium iodide staining. The efficacy of EEPA was examined in vivo in an acute model of infection by monitoring blood parasitaemia and survival rate 30 days after treatment. The effect against trypomastigotes of EEPA and benznidazole acting in combination was evaluated.

RESULTS

EEPA effectively inhibits the epimastigote growth (IC50 2.9 ± 0.1 µM) and reduces bloodstream trypomastigote viability (EC50 1.7 ± 0.5 µM). It causes parasite cell death by necrosis. EEPA impairs parasite infectivity as well as amastigote development in concentrations noncytotoxic to mammalian cells. In mice acutely-infected with T. cruzi, EEPA reduced the blood parasitaemia in 72.7%. When combined with benznidazole, EEPA showed a synergistic anti-T. cruzi activity, displaying CI values of 0.8 ± 0.07 at EC50 and 0.83 ± 0.1 at EC90.

CONCLUSION

EEPA has antiparasitic activity against T. cruzi, causing cell death by necrosis and showing synergistic activity with benznidazole. These findings were reinforced by the observed efficacy of EEPA in reducing parasite load in T. cruzi-mice. Therefore, this represents an important source of antiparasitic natural products.

Potent anti-inflammatory activity of betulinic acid treatment in a model of lethal endotoxemia

Betulinic acid (BA) is a lupane-type triterpene with a number of biological activities already reported. While potent anti-HIV and antitumoral activities were attributed to BA, it is considered to have a moderate anti-inflammatory activity. Here we evaluated the effects of BA in a mouse model of endotoxic shock. Endotoxemia was induced through intraperitoneally LPS administration, nitric oxide (NO) and cytokines were assessed by Griess method and ELISA, respectively. Treatment of BALB/c mice with BA at 67 mg/kg caused a 100% survival against a lethal dose of lipopolysaccharide (LPS). BA treatment caused a reduction in TNF-α production induced by LPS but did not alter IL-6 production. Moreover, BA treatment increased significantly the serum levels of IL-10 compared to vehicle-treated, LPS-challenged mice. To investigate the role of IL-10 in BA-induced protection, wild-type and IL-10(-/-) mice were studied. In contrast to the observations in IL-10(+/+) mice, BA did not protect IL-10(-/-) mice against a lethal LPS challenge. Addition of BA inhibited the production of pro-inflammatory mediators by macrophages stimulated with LPS, while promoting a significant increase in IL-10 production. BA-treated peritoneal exudate macrophages produced lower concentrations of TNF-α and NO and higher concentrations of IL-10 upon LPS stimulation. Similarly, macrophages obtained from BA-treated mice produced less pro-inflammatory mediators and increased IL-10 when compared to non-stimulated macrophages obtained from vehicle-treated mice. In conclusion, we have shown that BA has a potent anti-inflammatory activity in vivo, protecting mice against LPS by modulating TNF-α production by macrophages in vivo through a mechanism dependent on IL-10.

Dimeric flavonoids from Arrabidaea brachypoda and assessment of their anti-Trypanosoma cruzi activity

The nonpolar fraction of an aqueous ethanol extract of the roots of Arrabidaea brachypoda, a Brazilian medicinal plant, demonstrated significant in vitro activity against Trypanosoma cruzi, the parasite responsible for Chagas disease. Targeted isolation of the active constituents led to the isolation of three new dimeric flavonoids (1-3), and their structures were elucidated using UV, NMR, and HRMS analysis, as well as by chemical derivatization. The anti-T. cruzi activity and cytotoxicity toward mammalian cells were determined for these substances. Compound 1 exhibited no activity toward T. cruzi, while flavonoids 2 and 3 exhibited selective activity against these trypomastigotes. Compounds 2 and 3 inhibited the parasite invasion process and its intracellular development in host cells with similar potencies to benznidazole. In addition, compound 2 reduced the blood parasitemia of T. cruzi-infected mice. This study has revealed that these two dimeric flavonoids represent potential anti-T. cruzi lead compounds for further drug development.

A New Source of (R)-Limonene and Rotundifolone from Leaves of Lippia pedunculosa (Verbenaceae) and their Trypanocidal Properties

Investigation by GC-FID and GC-MS of the essential oil (LPOE) from the leaves of Lippia pedunculosa revealed, as the major compounds, the monoterpenes rotundifolone (71.7%) and ( R)-limonene (21.8%). These two compounds and the minor constituent piperitenone (1.2%) were also isolated from the leaves and identified by spectrometric analysis. LPOE and isolated compounds were evaluated for their trypanocidal activity against epimastigote and trypomastigote forms of Trypanosoma cruzi. Significant results with IC50 values lower than 34.0 μg.mL−1 were observed against these forms of T. cruzi for LPOE and isolated compounds. Rotundifolone was the most active compound with an IC50 lower than 10.0 μg.mL–1 for both forms of T. cruzi. The effects of LPOE and isolated compounds were also evaluated in cultures of macrophages infected with T. cruzi. Treatment with ( R)-limonene and rotundifolone caused a moderate reduction in the percentage of macrophages infected by T. cruzi and in the number of intracellular parasites at concentrations non-toxic to macrophages.

A new source of (R)-limonene and rotundifolone from leaves of Lippia pedunculosa (verbenaceae) and their trypanocidal properties

Investigation by GC-FID and GC-MS of the essential oil (LPOE) from the leaves of Lippia pedunculosa revealed, as the major compounds, the monoterpenes rotundifolone (71.7%) and (R)-limonene (21.8%). These two compounds and the minor constituent piperitenone (1.2%) were also isolated from the leaves and identified by spectrometric analysis. LPOE and isolated compounds were evaluated for their trypanocidal activity against epimastigote and trypomastigote forms of Trypanosoma cruzi. Significant results with IC50 values lower than 34.0 microg.mL(-1) were observed against these forms of T. cruzi for LPOE and isolated compounds. Rotundifolone was the most active compound with an ICso lower than 10.0 ig.mL"' for both forms of T. cruzi. The effects of LPOE and isolated compounds were also evaluated in cultures of macrophages infected with T. cruzi. Treatment with (R)-limonene and rotundifolone caused a moderate reduction in the percentage of macrophages infected by T. cruzi and in the number of intracellular parasites at concentrations non-toxic to macrophages.

Chemical composition and anti-Trypanosoma cruzi activity of essential oils obtained from leaves of Xylopia frutescens and X. laevigata (Annonaceae)

Essential oils from leaves of Xylopia frutescens (XFMJ) and two specimens of Xylopia laevigata (XLMC and XLSI) were obtained by hydrodistillation using a Clevenger-type apparatus, and analyzed by GC-MS and GC-FID. Sesquiterpenes dominated the essential oils. The main constituents of XFMJ were (E)-caryophyllene (24.8%), bicyclogermacrene (20.8%), germacrene D (17.0%), beta-elemene (7.9%), and (E)-beta-ocimene (6.8%). XLMC contained significant quantities of germacrene D (18.9%), bicyclogermacrene (18.4%), beta-elemene (9.5%), delta-selinene (9.2%), (E)-caryophyllene (8.5%), germacrene B (5.7%) and gamma-muurolene (5.7%), while germacrene D (27.0%), bicyclogermacrene (12.8%), (E)-caryophyllene (8.6%), gamma-muurolene (8.6%), delta-cadinene (6.8%), and germacrene B (6.0%) were the main components of XLSI. The essential oils had trypanocidal activity against the Y strain of Trypanosoma cruzi, with IC50 values lower than 30 microg x mL(-1) and 15 microg x mL(-1) against epimastigote and trypomastigote forms of T. cruzi, respectively, and were also able to reduce the percentage in vitro of T. cruzi-infected macrophages and the intracellular number of amastigotes at concentrations that were non-cytotoxic to macrophages.

Chemical Composition and Anti-Trypanosoma cruzi Activity of Essential Oils Obtained from Leaves of Xylopia frutescens and X. laevigata (Annonaceae)

Essential oils from leaves of Xylopia frutescens (XFMJ) and two specimens of Xylopia laevigata (XLMC and XLSI) were obtained by hydrodistillation using a Clevenger-type apparatus, and analyzed by GC-MS and GC-FID. Sesquiterpenes dominated the essential oils. The main constituents of XFMJ were ( E)-caryophyllene (24.8%), bicyclogermacrene (20.8%), germacrene D (17.0%), β-elemene (7.9%), and ( E)-β-ocimene (6.8%). XLMC contained significant quantities of germacrene D (18.9%), bicyclogermacrene (18.4%), β-elemene (9.5%), 5-selinene (9.2%), ( E)-caryophyllene (8.5%), germacrene B (5.7%) and γ-muurolene (5.7%), while germacrene D (27.0%), bicyclogermacrene (12.8%), ( E)-caryophyllene (8.6%), γ-muurolene (8.6%), 5-cadinene (6.8%), and germacrene B (6.0%) were the main components of XLSI. The essential oils had trypanocidal activity against the Y strain of Trypanosoma cruzi. with IC50 values lower than 30 μg.mL−1 and 15 μg.mL−1 against epimastigote and trypomastigote forms of T. cruzi. respectively, and were also able to reduce the percentage in vitro of T. cruzi-infected macrophages and the intracellular number of amastigotes at concentrations that were non-cytotoxic to macrophages.

Optimization of anti-Trypanosoma cruzi oxadiazoles leads to identification of compounds with efficacy in infected mice

We recently showed that oxadiazoles have anti-Trypanosoma cruzi activity at micromolar concentrations. These compounds are easy to synthesize and show a number of clear and interpretable structure-activity relationships (SAR), features that make them attractive to pursue potency enhancement. We present here the structural design, synthesis, and anti-T. cruzi evaluation of new oxadiazoles denoted 5a-h and 6a-h. The design of these compounds was based on a previous model of computational docking of oxadiazoles on the T. cruzi protease cruzain. We tested the ability of these compounds to inhibit catalytic activity of cruzain, but we found no correlation between the enzyme inhibition and the antiparasitic activity of the compounds. However, we found reliable SAR data when we tested these compounds against the whole parasite. While none of these oxadiazoles showed toxicity for mammalian cells, oxadiazoles 6c (fluorine), 6d (chlorine), and 6e (bromine) reduced epimastigote proliferation and were cidal for trypomastigotes of T. cruzi Y strain. Oxadiazoles 6c and 6d have IC(50) of 9.5 ± 2.8 and 3.5 ± 1.8 μM for trypomastigotes, while Benznidazole, which is the currently used drug for Chagas disease treatment, showed an IC(50) of 11.3 ± 2.8 μM. Compounds 6c and 6d impair trypomastigote development and invasion in macrophages, and also induce ultrastructural alterations in trypomastigotes. Finally, compound 6d given orally at 50mg/kg substantially reduces the parasitemia in T. cruzi-infected BALB/c mice. Our drug design resulted in potency enhancement of oxadiazoles as anti-Chagas disease agents, and culminated with the identification of oxadiazole 6d, a trypanosomicidal compound in an animal model of infection.