“Proliferation of DBLOX Peroxidase-Expressing Oenocytes Maintains Innate Immune Memory in Primed Mosquitoes”

Abstract

Immune priming in Anopheles gambiae mosquitoes following infection with Plasmodium parasites is mediated by the systemic release of a hemocyte differentiation factor (HDF), a complex of lipoxin A4 bound to Evokin, a lipid carrier. HDF increases the proportion of circulating granulocytes and enhances mosquito cellular immunity. We found that Evokin is constitutively produced by hemocytes and fat-body cells, but expression increases in response to infection. Insects synthesize lipoxins, but lack lipoxygenases. Here, we show that the Double Peroxidase (DBLOX) enzyme, present in insects but not in vertebrates, is essential for HDF synthesis. DBLOX is highly expressed in oenocytes in the fat body tissue, and these cells proliferate in response to Plasmodium challenge. We provide direct evidence that modifications mediated by the histone acetyltransferase AgTip60 (AGAP01539) are essential for sustained oenocyte proliferation, HDF synthesis and immune priming. We propose that oenocytes function as a population of “memory” cells that continuously release lipoxin to orchestrate and maintain a broad, systemic and long-lasting state of enhanced immune surveillance.

A male-specific cell line from the African malaria mosquito Anopheles gambiae: Establishment and a comparative transcriptomic analysis

“…The A. gambiae Sua5.1 hemocyte-like cell line 7,11 has been extensively used in studies on mosquito immunity [12][13][14][15][16][17][18][19] . It was also used as an in vitro tool, for example, to test the functionality of the bi-partite GAL4-UAS expression system 20 , to explore the activity of putative constitutive promoters of the A. gambiae genes 21,22 , or to study fundamental developmental biology of A. gambiae 23,24 .…”