Non-opsonic phagocytosis of homologous non-toxigenic and toxigenicCorynebacterium diphtheriaestrains by human U-937 macrophages
| Autor: | Ana LuÃza de Mattos-Guaraldi, CÃntia Silva dos Santos, Fernanda dos Santos Dourado, Raphael Hirata Junior, Gabriela Andrade Pereira, Monica Cristina Souza, Priscila Soares Sabbadini, Maulori Curié Cabral, Alexandre Alves de Souza de Oliveira Dias, Louisy Sanches dos Santos |
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| Rok vydání: | 2010 |
| Předmět: |
Necrosis
Phagocytosis Immunology Angiogenesis Inhibitors Apoptosis Enzyme-Linked Immunosorbent Assay Microbiology Bacterial Adhesion fluids and secretions Virology medicine Humans Protein Kinase Inhibitors Opsonin Corynebacterium diphtheriae biology U937 cell Macrophages Intracellular parasite U937 Cells biology.organism_classification Cytochalasins Genistein Tubulin Modulators Microscopy Fluorescence bacteria medicine.symptom Colchicine Bacteria |
| Zdroj: | Microbiology and Immunology. 54:1-10 |
| ISSN: | 1348-0421 0385-5600 |
| Popis: | As interactions between bacteria and macrophages dictate the outcome of most infectious diseases, analyses of molecular mechanisms of non-opsonic phagocytosis should lead to new approaches for the prevention of diphtheria and systemic Corynebacterium diphtheriae infections. The present study aimed to evaluate human macrophage-bacteria interactions in the absence of opsonin antibodies and the influence of the tox gene on this process. Homologous C. diphtheriae tox+ and tox- strains were evaluated for adhesion, entering and survival within U-937 human macrophages at different incubation periods. Higher numbers of viable bacteria associated with and internalized by macrophages were demonstrated for the tox+ strain. However, viable intracellular bacteria were detected at T-24 hr only for the tox- strain. Cytoskeletal inhibitors, cytochalasin E, genistein and colchicine, inhibited intracellular viability of both strains at different levels. Bacterial replication was evidenced at T-24 hr in supernatants of monolayers infected with the tox- strain. Host cell death and nuclear alterations were evidenced by the Trypan blue exclusion assay and DAPI fluorescence microscopy. ELISA of histone-associated DNA fragments allowed detection of apoptosis and necrosis induced by tox+ and tox- strains at T-1 hr and T-3 hr. In conclusion, human macrophages in the absence of opsonins may not be promptly effective at killing diphtheria bacilli. The presence of the tox gene influences the susceptibility of C. diphtheriae to human macrophages and the outcome of non-opsonic phagocytosis. C. diphtheriae strains exhibit strategies to survive within macrophages and to exert apoptosis and necrosis in human phagocytic cells, independent of the tox gene. |
| Databáze: | OpenAIRE |
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