The critical window for host defense: macrophage trogocytosis eliminates Echinococcus multilocularis at the early
Ning Yang1,2, Liang Li1, Junlong Xue1
1State Key Laboratory of Pathogenesis, Prevention, and Treatment of Central Asian High Incidence Diseases, Clinical Medical Research Institute, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, China.
Introduction:
The ability of Echinococcus multilocularis (E.m) to establish infection depends on evading host immune clearance during the early stages. This study investigated the mechanisms by which host macrophages eliminate E.m during this critical window.
Methods:
We utilized a mouse infection model with fluorescently labeled protoscoleces to observe early immune dynamics in vivo. Histopathological analysis was performed to characterize lesion phenotypes. The mechanism of parasite killing was further explored using in vitro co-culture experiments and scanning electron microscopy (SEM).
Results:
Rapid immune cell infiltration and parasite clearance in the liver were observed within 24 hours post-infection. Histopathological analysis revealed two distinct lesion phenotypes: "Progressive Lesions," characterized by a failure of macrophage infiltration and parasite transformation into vesicles, and "Regressive Lesions," marked by high macrophage density and complete parasite elimination. In vitro experiments demonstrated that macrophages mediated protoscolex killing through complement-dependent trogocytosis, a process requiring active serum components. SEM confirmed direct macrophage-parasite contact and trogocytosis as the primary mode of elimination.
Discussion:
These findings highlight the pivotal role of macrophage trogocytosis in early host defense against E.m infection and provide new insights into the mechanisms of innate immunity in parasitic clearance.
Insights
Host macrophages eliminate Echinococcus multilocularis (E.m) through complement-dependent trogocytosis. This process is crucial for early immune defense against E.m infection, preventing parasite establishment.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Echinococcus multilocularis (E.m) establishes infection by evading early host immune clearance.
- Understanding macrophage-mediated elimination mechanisms is critical for controlling E.m infections.
Purpose of the Study:
- To investigate the mechanisms by which host macrophages eliminate E.m during the early stages of infection.
- To elucidate the role of innate immunity in parasitic clearance.
Main Methods:
- A mouse infection model with fluorescently labeled protoscoleces was used for in vivo observation.
- Histopathological analysis, in vitro co-culture, and scanning electron microscopy (SEM) were employed to study immune dynamics and parasite killing mechanisms.
Main Results:
- Rapid immune cell infiltration and parasite clearance were observed within 24 hours post-infection.
- Two lesion phenotypes were identified: progressive (failed clearance) and regressive (complete elimination).
- Macrophages mediated protoscolex killing via complement-dependent trogocytosis, confirmed by SEM.
Conclusions:
- Macrophage trogocytosis is pivotal in early host defense against E.m.
- These findings offer new insights into innate immune mechanisms for parasitic clearance.
Related Concept Videos
01:31Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
01:25Immune Surveillance by NK Cells and Phagocytes
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...