Investigation of the Potential Targets behind the Promising and Highly Selective Antileishmanial Action of Synthetic Flavonoid Derivatives.

Leishmaniases are among the neglected tropical diseases that still cause devastating health, social, and economic consequences to more than 350 million people worldwide. Despite efforts to combat these vector-borne diseases, their incidence does not decrease. Meanwhile, current antileishmanial drugs are old and highly toxic, and safer presentations are unaffordable to the most severely affected human populations. In a previous study by our research group, we synthesized 17 flavonoid derivatives that demonstrated impressive inhibition capacity against rCPB2.8, rCPB3, and rH84Y. These cysteine proteases are highly expressed in the amastigote stage, the target form of the parasite. However, although these compounds have been already described in the literature, until now, the amastigote effect of any of these molecules has not been proven. In this work, we aimed to deeply analyze the antileishmanial action of this set of synthetic flavonoid derivatives by correlating their ability to inhibit cysteine proteases with the action against the parasite. Among all the synthesized flavonoid derivatives, 11 of them showed high activity against amastigotes of Leishmania amazonensis, also providing safety to mammalian host cells. Furthermore, the high production of nitric oxide by infected cells treated with the most active cysteine protease B (CPB) inhibitors confirms a potential immunomodulatory response of macrophages. Besides, considering flavonoids as multitarget drugs, we also investigated other potential antileishmanial mechanisms. The most active compounds were selected to investigate another potential biological pathway behind their antileishmanial action using flow cytometry analysis. The results confirmed an oxidative stress after 48 h of treatment. These data represent an important step toward the validation of CPB as an antileishmanial target, as well as aiding in new drug discovery studies based on this protease.

Differential interactions of the antimicrobial peptide, RQ18, with phospholipids and cholesterol modulate its selectivity for microorganism membranes.

BACKGROUND: Antimicrobial peptides (AMPs) are molecules with potential application for the treatment of microorganism infections. We, herein, describe the structure, activity, and mechanism of action of RQ18, an α-helical AMP that displays antimicrobial activity against Gram-positive and Gram-negative bacteria, and yeasts from the Candida genus. METHODS: A physicochemical-guided design assisted by computer tools was used to obtain our lead peptide candidate, named RQ18. This peptide was assayed against Gram-positive and Gram-negative bacteria, yeasts, and mammalian cells to determine its selectivity index. The secondary structure and the mechanism of action of RQ18 were investigated using circular dichroism, large unilamellar vesicles, and molecular dynamic simulations. RESULTS: RQ18 was not cytotoxic to human lung fibroblasts, peripheral blood mononuclear cells, red blood cells, or Vero cells at MIC values, exhibiting a high selectivity index. Circular dichroism analysis and molecular dynamic simulations revealed that RQ18 presents varying structural profiles in aqueous solution, TFE/water mixtures, SDS micelles, and lipid bilayers. The peptide was virtually unable to release carboxyfluorescein from large unilamellar vesicles composed of POPC/cholesterol, model that mimics the eukaryotic membrane, indicating that vesicles' net charges and the presence of cholesterol may be related with RQ18 selectivity for bacterial and fungal cell surfaces. CONCLUSIONS: RQ18 was characterized as a membrane-active peptide with dual antibacterial and antifungal activities, without compromising mammalian cells viability, thus reinforcing its therapeutic application. GENERAL SIGNIFICANCE: These results provide further insight into the complex process of AMPs interaction with biological membranes, in special with systems that mimic prokaryotic and eukaryotic cell surfaces.

Detection of regulatory T cell phenotypic markers and cytokines in patients with human papillomavirus infection.

Infection with human papillomavirus (HPV) is the main cause of cervical cancer. Viral persistence is considered the main risk factor for neoplastic progression and evidence suggests that regulatory T cells (Treg) play an important role in the failure of viral elimination. The aim of this study was to detect phenotypic markers of Treg and cytokines interleukin (IL)-10 and transforming growth factor (TGF)-ß, in the cervical microenvironment of HPV-infected patients. One hundred and one samples of uterine cervix embedded in paraffin were analyzed. We used immunohistochemistry to examine the coexpression of the CD25/FOXP3 and CD4/TGF-ß markers, and the expression of GITR and IL-10 in cells present in the cervical stroma. We detected a microenvironment composed of high proportions of CD25+ FOXP3+ , CD4+ TGFß+ , IL-10+ , and GITR+ cells in samples with high viral loads and severe lesions of HPV-infected patients. The abundance of these markers, indicative of the presence of Treg cells and immunosuppressive cytokines, was significantly associated with severe lesions and elevated viral loads in the examined samples. These results suggest that Treg cells may be involved in maintaining a microenvironment favorable for viral persistence and neoplastic progression. Our findings support those of previous studies that suggested that these markers could be used to predict HPV persistence and neoplastic progression, and as potential targets for immune response modulation.

Human papillomavirus and coinfections with Chlamydia trachomatis, Gardnerella vaginalis, and Trichomonas vaginalis in self-collected samples from female sex workers in the Central-Western region of Brazil / Papilomavírus humano e coinfecção por Chlamydia trachomatis, Gardnerella vaginalis e Trichomonas vaginalis em amostras autocoletadas de mulheres profissionais do sexo da região Centro-Oeste do Brasil

ABSTRACT Introduction: Human papillomavirus (HPV) is intimately associated with cervical cancer, and the presence of coinfections, such as with Chlamydia trachomatis, Gardnerella vaginalis and Trichomonas vaginalis, may potentiate or facilitate HPV infection. Female sex workers are considered vulnerable to the acquisition of these infections due to exposure to risk factors. Objective: To determine HPV infection, viral types and coinfections in self-collected samples from female sex workers. Methods: Self-collected samples from female sex workers, of vaginal canal and uterine cervix, were subjected to HPV-deoxyribonucleic acid (DNA) detection, viral genotyping by type-specific polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and the detection of coinfection. Results: HPV-DNA was detected in 19.4% of the samples, and HPV 31, 6, and 53 were the most frequently detected types. There was a predominance of high-risk oncogenic HPV (HR-HPV) and a strong presence of simultaneous infections with multiple HPV types (84.6%). Coinfections with both HPV and C. trachomatis, and HPV and G. vaginalis were detected. The variables that were statistically associated with HPV infection and the presence of multiple infections were non-use of condoms and non-compliance with regular cervical cytology screening. Conclusion: The results highlight the importance of more comprehensive studies among vulnerable populations, aiming to establish measures to raise awareness about the risks of contracting sexually transmitted infections, as well as to support future studies for introducing HPV vaccines with wider coverage of viral types.

RESUMO Introdução: O papilomavírus humano (HPV) está intimamente associado ao câncer cervical, e a presença de coinfecções, como por Chlamydia trachomatis, Gardnerella vaginalis e Trichomonas vaginalis, pode potencializar ou facilitar a infecção por HPV. As mulheres profissionais do sexo são consideradas vulneráveis à aquisição dessas infecções devido à exposição aos fatores de risco. Objetivo: Determinar a infecção por HPV, os tipos virais e as coinfecções em amostras autocoletadas de mulheres profissionais do sexo. Métodos: Amostras autocoletadas de mulheres profissionais do sexo, do canal vaginal e da cérvice uterina, foram submetidas a detecção do HPV-ácido desoxirribonucleico (DNA), genotipagem viral por reação em cadeia da polimerase (PCR) tipo específica e restriction fragment length polymorphism (RFLP) e detecção de coinfecção. Resultados: O HPV-DNA foi detectado em 19,4% das amostras, sendo os tipos HPV 31, 6 e 53 os mais frequentes. Houve predominância de HPV de alto risco (HR-HPV) e elevada presença de infecções múltiplas (84,6%). A presença de coinfecções foi observada tanto para HPV e C. trachomatis quanto para HPV e G. vaginalis. Observou-se também que mulheres profissionais do sexo que não fazem uso de preservativos e aquelas que não realizam o exame citológico rotineiramente estão predispostas à aquisição da infecção causada pelo HPV. Conclusão: Os resultados obtidos ressaltam a importância de estudos mais abrangentes entre as populações vulneráveis, objetivando estabelecer medidas para a conscientização sobre os riscos de aquisição das infecções sexualmente transmitidas, bem como auxiliar estudos futuros para introdução de vacinas contra o HPV com maior cobertura de tipos virais.

Predominant overexpression of CD25/FOXP3, IFN-γ, and suppressive cytokines in high-grade lesion samples infected with human papillomavirus / PPredominância de superexpressão de CD25/FOXP3, IFN-γ e citocinas supressoras em amostras de lesão de alto grau infectadas pelo papilomavírus humano

ABSTRACT Introduction: Human papillomavirus (HPV) persistent infection is the leading cause of cervical cancer and its precursor lesions, and the inappropriate immune response is among the factors that contribute to viral persistence. This may be influenced by regulatory T (Treg) cells and the production of immunosuppressive cytokines, such as transforming growth factor beta (TGF-β) and interleukin-10 (IL-10). Objective: We established the profile of the predominant response, Th1 or immunosuppressive response, in the tissue microenvironment, by detecting interferon-gamma (IFN-γ), TGF-β, and IL-10, as well as the co-expression of IL-2 receptor alpha (CD25) and forkhead box P3 (FOXP3). Methods: Seventy-four samples from uterine cervix biopsies that underwent HPV deoxyribonucleic acid (DNA) detection and histopathology analysis were immunostained to detect CD25/FOXP3, IFN-γ and suppressive cytokines in lymphocytes. Results: The microenvironment of high-grade squamous intraepithelial lesion (HSIL) samples with high numbers of viral particles (≥ 10,000 copies/ml) contained high numbers of CD25/FOXP3+, TGF-β+, IL-10+, and IFN-γ+ cells. Conclusion: The co-expression of CD25/FOXP3 and the expression of TGF-β, and IL-10 in HSIL samples suggest the existence of Treg cells in these locations, although IFN-γ expression was observed in several cells in these samples. Our data suggest that this cytokine could be related to immunosuppressed microenvironment maintenance, favoring the persistent HPV infection and the progression to carcinoma.

RESUMO Introdução: A infecção persistente por papilomavírus humano (HPV) é a principal causa do câncer cervical e suas lesões precursoras, e a resposta imune inadequada está entre os fatores que contribuem para a persistência viral. Isso pode ser influenciado por células T regulatórias (Treg) e pela produção de citocinas imunossupressoras, como o fator de transformação de crescimento beta (TGF-β) e a interleucina 10 (IL-10). Objetivo: Estabelecemos o perfil de resposta predominante, resposta Th1 ou imunossupressora, no microambiente tecidual, pela detecção de interferon gama (IFN-γ), TGF-β, e IL-10, bem como a coexpressão do receptor da cadeia alfa da IL-2 (CD25) e do forkhead box P3 (FOXP3). Método: Setenta e quatro amostras de biópsias de cérvice uterina, submetidas à detecção do ácido desoxirribonucleico (DNA) de HPV e à análise histopatológica, foram utilizadas nas reações de imuno-histoquímica para detectar IFN-γ, TGF-β, IL-10 e CD25/FOXP3 em linfócitos. Resultados: O microambiente das amostras de lesões intraepiteliais escamosas de alto grau (HSIL) com elevado números de partículas virais (≥ 10.000 cópias/ml) continha elevado número de células CD25/FOXP3+, TGF-β+, IL-10+ e IFN-γ+. Conclusão: A coexpressão de CD25/FOXP3 e a expressão de TGF-β nas amostras HSIL sugerem a existência de células Treg nesses locais, embora a expressão de IFN-γ tenha sido observada em várias células. Nossos dados sugerem que essa citocina pode estar relacionada com a manutenção do microambiente imunossuprimido, favorecendo a infecção persistente por HPV e a progressão para carcinoma.