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The effect of intracellular Chlamydia psittaci on lysosomal enzyme activities in mouse peritoneal macrophages
B Mørland1, G I Byrne, T C Jones
1Council for Medical Research, Norwegian Research Council for Science and the Humanities, Oslo, Norway.
Abstract:
Live or heat killed (30 min at 56 degrees C) Chlamydia psittaci elementary bodies (EB) were phagocytosed by mouse peritoneal macrophages. Inoculation with killed Chlamydia caused rises in three lysosomal enzyme activities tested, especially in acid phosphatase activity. In contrast, after infection with live Chlamydia, only a negligible increase was seen in acid phosphatase activity, and no change in the activities of beta-glucuronidase and cathepsin D was observed. It was concluded that regulation of lysosomal enzyme synthesis in macrophages may be linked to signals mediated by phago-lysosome fusions.
Insights
Heat-killed Chlamydia psittaci elementary bodies (EB) triggered lysosomal enzyme increases in macrophages, unlike live Chlamydia. This suggests phago-lysosome fusion signals regulate macrophage lysosomal enzyme synthesis.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Macrophages play a crucial role in the innate immune response through phagocytosis.
- Lysosomal enzymes are essential for degrading phagocytosed material within macrophages.
- Chlamydia psittaci is an obligate intracellular bacterium that infects macrophages.
Purpose of the Study:
- To investigate the effect of live and heat-killed Chlamydia psittaci elementary bodies (EB) on lysosomal enzyme activity in mouse peritoneal macrophages.
- To explore the role of phago-lysosome fusion in regulating lysosomal enzyme synthesis.
Main Methods:
- Mouse peritoneal macrophages were incubated with live or heat-killed Chlamydia psittaci EB.
- Lysosomal enzyme activities, including acid phosphatase, beta-glucuronidase, and cathepsin D, were measured.
Main Results:
- Heat-killed EB induced significant increases in lysosomal enzyme activities, particularly acid phosphatase.
- Live EB infection resulted in only a negligible increase in acid phosphatase and no change in beta-glucuronidase or cathepsin D.
- Differential enzyme responses were observed based on the viability of Chlamydia EB.
Conclusions:
- Macrophage lysosomal enzyme synthesis regulation appears to be influenced by signals generated during phago-lysosome fusion.
- The interaction between Chlamydia EB and macrophages modulates specific lysosomal enzyme pathways.
- Viability of the pathogen is a critical factor in the macrophage's lysosomal response.
