Phagocytic hemocytes, independent of pericardial cells, modulate cellular immune responses on the dorsal vessel of mosquitoes, including the infection-induced reduction of the heart rate

2025/09/19 by Cole J. Meier, Shabbir Ahmed, Tania Y. Estévez‐Lao +1 · 1 voice · 1 citation
Medicine · Immunology and Microbiology · Neuroscience · #Mosquito-borne diseases and control #Invertebrate Immune Response Mechanisms #Neurobiology and Insect Physiology Research

paper · pdf · doi:10.1007/s00441-025-04011-y

openalex publication_date 2025/09/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23

Abstract

Infection induces the aggregation of hemocytes on the dorsal vessel of mosquitoes. These hemocytes, called periostial hemocytes, phagocytose pathogens and produce immune factors on the abdominal portion of the dorsal vessel, called the heart. One of these immune factors, nitric oxide, is a pleiotropic free radical that is an antimicrobial and a heartbeat reducer. But nitric oxide is not just produced by hemocytes. It is also synthesized by pericardial cells that flank the heart, and other tissues. To determine whether it is the periostial hemocytes or the pericardial cells that modulate the heart following infection, we chemically ablated the hemocytes using clodronate liposomes and measured immune responses and heart physiology. We demonstrate that clodronate liposomes ablate the sessile hemocytes, including the periostial hemocytes, while leaving the pericardial cells and heart integrity unaffected. Moreover, ablating hemocytes abolishes the phagocytosis of bacteria, alters the deposition of melanized bacteria, and decreases nitric oxide synthase activity on the heart. Importantly, hemocyte ablation eliminates the infection induced reduction of the heart rate, mainly by modifying the anterograde heart rate. Therefore, periostial hemocytes drive immune responses on the heart and infection-induced changes to circulatory physiology.

Citations

• Activation of the immune deficiency pathway (IMD) reduces the mosquito heart rate via a nitric oxide-based mechanism
• Extracellular matrix proteins Pericardin and Lonely heart mediate periostial hemocyte aggregation in the mosquito Anopheles gambiae
• Localization of nitric oxide–producing hemocytes in Aedes and Culex mosquitoes infected with bacteria
• The immune deficiency and c-Jun N-terminal kinase pathways drive the functional integration of the immune and circulatory systems of mosquitoes
• Analysis of Relative Gene Expression Data Using Real-Time Quantitative PCR and the 2−ΔΔCT Method

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Discussions

• New paper: Phagocytic hemocytes, independent of pericardial cells, modulate cellular immune responses on the dorsal vessel of mosquitoes, including the infection-induced reduction of the heart rate @v [bsky, 4 points, 0 comments]

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