Leishmania infantum induces high phagocytic capacity and intracellular nitric oxide production by human proinflammatory monocyte.

BACKGROUND: The mechanism of resistance to SbIII in Leishmania is complex, multifactorial and involves not only biochemical mechanisms, but also other elements, such as the immune system of the host. OBJECTIVES: In this study, putative changes in the immunological profile of human monocytes infected with wild-type (WT) and antimony (SbIII)-resistant Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum lines were evaluated. METHODS: Susceptibility assays WT and SbIII-resistant L. braziliensis and L. infantum were performed using lines THP-1 human monocytic lineage. Phagocytic capacity, cytokine profile, intracellular nitric oxide (NO) production and surface carbohydrate residues profile were performed in peripheral blood monocytes by flow cytometry. FINDINGS: The phagocytic capacity and intracellular NO production by classical (CD14++CD16-) and proinflammatory (CD14++CD16+) monocytes were higher in the presence of L. infantum lines compared to L. braziliensis lines. The results also highlight proinflammatory monocytes as the cellular subpopulation of major relevance in a phagocytosis event and NO expression. It is important to note that L. infantum induced a proinflammatory cytokine profile characterised by higher levels of TNF-α in culture supernatant than L. braziliensis. Conversely, both Leishmania lines induce high levels of IL-6 in culture supernatant. Analysis of the expression profile of surface carbohydrates showed that L. braziliensis presents 4.3-fold higher expression of galactose(ß1,4)N-acetylglucosamine than L. infantum line. Interestingly, the expression level of α-N-acetylgalactosamine residues was 2-fold lower in the SbIII-resistant L. braziliensis line than its counterpart WT line, indicating differences in surface glycoconjugates between these lines. MAIN CONCLUSIONS: Our results showed that L. braziliensis and L. infantum induce different innate immune responses and a highly inflammatory profile, which is characteristic of infection by L. infantum, the species associated with visceral disease.

Mannosyltransferase (GPI-14) overexpression protects promastigote and amastigote forms of Leishmania braziliensis against trivalent antimony.

BACKGROUND: Glycosylphosphatidylinositol is a surface molecule important for host-parasite interactions. Mannosyltransferase (GPI-14) is an essential enzyme for adding mannose on the glycosylphosphatidyl group. This study attempted to overexpress the GPI-14 gene in Leishmania braziliensis to investigate its role in the antimony-resistance phenotype of this parasite. RESULTS: GPI-14 mRNA levels determined by quantitative real-time PCR (qRT-PCR) showed an increased expression in clones transfected with GPI-14 compared to its respective wild-type line. In order to investigate the expression profile of the surface carbohydrates of these clones, the intensity of the fluorescence emitted by the parasites after concanavalin-A (a lectin that binds to the terminal regions of α-D-mannosyl and α-D-glucosyl residues) treatment was analyzed. The results showed that the clones transfected with GPI-14 express 2.8-fold more mannose and glucose residues than those of the wild-type parental line, indicating effective GPI-14 overexpression. Antimony susceptibility tests using promastigotes showed that clones overexpressing the GPI-14 enzyme are 2.4- and 10.5-fold more resistant to potassium antimonyl tartrate (SbIII) than the parental non-transfected line. Infection analysis using THP-1 macrophages showed that amastigotes from both GPI-14 overexpressing clones were 3-fold more resistant to SbIII than the wild-type line. CONCLUSIONS: Our results suggest the involvement of the GPI-14 enzyme in the SbIII-resistance phenotype of L. braziliensis.

Apoptosis and expression of argyrophilic nucleolus organizer regions in epithelial neoplasms of the larynx / Apoptose e expressão de regiões argirófilas organizadoras de nucléolos em neoplasias epiteliais da laringe

INTRODUCTION: Occurrence of apoptosis and expression of proliferative markers are powerful tools to establish a prognosis in the follow-up of cancer. OBJECTIVE: To evaluate the growth fraction in papillomas and laryngeal squamous cell carcinomas with three degrees of differentiation through apoptosis and the expression of nucleolus organizer regions. METHODS: Retrospective study from which paraffin material was submitted to microtomy and hematoxylin-eosin and silver staining. Stained slides were used to quantify the apoptotic index and the number of nucleolus organizer regions by morphometry. RESULTS: Apoptosis was significantly more frequent in well differentiated carcinomas and in papillomas, and a higher growth fraction of expressed nucleolus organizer regions and cells that expressed a greater than average number of nucleolus organizer regions were more frequently noted in undifferentiated carcinomas. CONCLUSIONS: Thus, it was possible to verify that a high apoptotic index was associated with a lower chance of tumor differentiation in carcinomas, while a greater number of total nucleolus organizer regions, cells expressing nucleolus organizer regions above average and a higher growth fraction were associated with greater likelihood of abnormal cell proliferation and increased tumor differentiation. .

INTRODUÇÃO: A ocorrência de apoptose e a expressão de marcadores proliferativos são ferramentas poderosas no estabelecimento do prognóstico do câncer. OBJETIVO: Avaliar a fração de crescimento de papilomas e carcinomas laríngeos de células escamosas, com três graus de diferenciação, através da apoptose e expressão de regiões organizadoras de nucléolo. MÉTODO: Estudo retrospectivo, cujo material em blocado em parafina foi submetido à microtomia e coloração em hematoxilina-eosina, e pela prata. As lâminas coradas foram utilizadas para quantificar o índice apoptótico e o número de regiões organizadoras de nucléolo (NORs) através da morfometria. RESULTADOS: A apoptose foi significativamente mais frequente em carcinomas bem diferenciados e em papilomas; enquanto que uma maior fração de crescimento, de NORs expressos e de células que expressaram maior número de NORs, foram mais frequentes nos carcinomas indiferenciados. CONCLUSÕES: Foi possível verificar que o índice apoptótico elevado indica menores chances de diferenciação tumoral nos carcinomas, enquanto que um maior número de NORs totais e células expressando NORs acima da média, e uma maior fração de crescimento, determinam maiores chances de proliferação celular anormal e maior diferenciação tumoral. .

Apoptosis and expression of argyrophilic nucleolus organizer regions in epithelial neoplasms of the larynx.

INTRODUCTION: Occurrence of apoptosis and expression of proliferative markers are powerful tools to establish a prognosis in the follow-up of cancer. OBJECTIVE: To evaluate the growth fraction in papillomas and laryngeal squamous cell carcinomas with three degrees of differentiation through apoptosis and the expression of nucleolus organizer regions. METHODS: Retrospective study from which paraffin material was submitted to microtomy and hematoxylin-eosin and silver staining. Stained slides were used to quantify the apoptotic index and the number of nucleolus organizer regions by morphometry. RESULTS: Apoptosis was significantly more frequent in well differentiated carcinomas and in papillomas, and a higher growth fraction of expressed nucleolus organizer regions and cells that expressed a greater than average number of nucleolus organizer regions were more frequently noted in undifferentiated carcinomas. CONCLUSIONS: Thus, it was possible to verify that a high apoptotic index was associated with a lower chance of tumor differentiation in carcinomas, while a greater number of total nucleolus organizer regions, cells expressing nucleolus organizer regions above average and a higher growth fraction were associated with greater likelihood of abnormal cell proliferation and increased tumor differentiation.