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Leishmania major surface protease Gp63 interferes with the function of human monocytes and neutrophils in vitro
A L Sørensen1, A S Hey, A Kharazmi
1Department of Clinical Microbiology, National University Hospital, Copenhagen, Denmark.
Abstract:
In the present study the effect of Leishmania major surface protease Gp63 on the chemotaxis and oxidative burst response of human peripheral blood monocytes and neutrophils was investigated. It was shown that prior incubation of cells with Gp63 inhibited chemotaxis of neutrophils but not monocytes towards the chemotactic peptide f-met-leu-phe. On the other hand, chemotaxis of both neutrophils and monocytes towards zymosan-activated serum containing C5a was inhibited by Gp63. Monocyte and neutrophil chemiluminescence response to opsonized zymosan was reduced by preincubation of the cells with Gp63 in a concentration-dependent manner. Notably, monocytes were inhibited to a much greater degree than neutrophils by a given concentration of Gp63, and they were also inhibited at much lower concentrations of the protease. The inhibitory effect of Gp63 on chemotaxis and chemiluminescence was completely abolished by heat inactivation of the protease at 70 degrees C for 15 min. Neither neutrophil nor monocyte chemiluminescence was inhibited by Gp63 when cells were stimulated with PMA. Our data suggest that the major surface protease Gp63 might play an important role in the initial stages of Leishmania/macrophage interactions and the intracellular survival of the parasite.
Insights
The Leishmania major surface protease Gp63 inhibits neutrophil and monocyte immune responses. Gp63 impairs cell movement and oxidative burst, potentially aiding parasite survival.
Area of Science:
- Immunology
- Parasitology
- Molecular Biology
Background:
- Leishmania major is a parasite that infects macrophages.
- The surface protease Gp63 is crucial for parasite survival.
- Immune cell responses like chemotaxis and oxidative burst are vital for fighting infections.
Purpose of the Study:
- To investigate the effect of Leishmania major surface protease Gp63 on human monocyte and neutrophil immune functions.
- To understand the role of Gp63 in the early stages of Leishmania-macrophage interactions.
Main Methods:
- Human peripheral blood monocytes and neutrophils were incubated with Gp63.
- Chemotaxis was assessed using the peptide f-met-leu-phe and zymosan-activated serum (C5a).
- Oxidative burst response was measured by chemiluminescence using opsonized zymosan and PMA stimulation.
Main Results:
- Gp63 inhibited neutrophil chemotaxis to f-met-leu-phe but not monocyte chemotaxis.
- Gp63 inhibited chemotaxis of both cell types towards C5a.
- Gp63 reduced the chemiluminescence response to opsonized zymosan in a concentration-dependent manner, with greater inhibition of monocytes.
- Heat inactivation of Gp63 abolished its inhibitory effects.
- Gp63 did not inhibit responses to PMA stimulation.
Conclusions:
- Leishmania major surface protease Gp63 modulates key innate immune cell functions.
- Gp63's inhibitory effects on chemotaxis and oxidative burst suggest a role in parasite evasion and intracellular survival.
- These findings highlight Gp63 as a potential target for therapeutic interventions against Leishmania infections.