PSC niche develops into immune-responsive blood cells capable of transdifferentiating into lamellocytes inDrosophila

Abstract

Drosophila blood cells called hemocytes form an efficient barrier against infections and tissue damage. During metamorphosis, hemocytes undergo tremendous changes in their shape and behavior preparing them for tissue clearance. Yet, the diversity and functional plasticity of pupal blood cells have not been explored. Here, we combine single-cell transcriptomics and high-resolution microscopy to dissect the heterogeneity and plasticity of pupal hemocytes. We identified precursor and effector hemocytes with distinct molecular signatures and cellular functions clearly distinct from other stages of hematopoiesis. Strikingly, we identified that PSC cells, which function as lymph gland niche, are highly migratory and immune responsive cells in the pupa. PSC cells can transdifferentiate to lamellocytes triggered by wasp infection. Altogether, our data highlight a remarkable cell heterogeneity, and identifies a cell population that acts not only as a stem cell niche in larval hematopoiesis, but functions as cell reservoir to pupal and adult blood cells.

Mycobacterium abscessus resists the innate cellular response by surviving cell lysis of infected phagocytes

“…Hemese, Tep4 and ance genes have been reported to be more highly expressed than crq gene in a new class of plasmatocytes called thanacytes (as we will refer to them throughout the text for a better understanding) at the larval stage [39]. Interestingly, this population might correspond to the secretory Plasmatocytes, very recently described at the pupal stage, strongly suggesting a persistence of thanacytes in adult flies [44]. We thus confirmed the presence of these cells in adult flies by confocal microscopy by observing Tep4>GFP and ance>GFP positive hemocytes (S6A Fig).…”

“…We have highlighted another sub-population of plasmatocytes, expressing He, ance, Tep4, CG30088 and CG30090, that is detrimental for fly survival. Due to this expression profile, they are presumably the subtype recently identified by single cell sequencing of Drosophila larval hemocytes called either thanacytes [39] or PL-Pcd/PL-AMP [42,43], which do not exhibit this capacity for phagocytosis [43] and even more recently described in pupae as Seceretory-PL [44]. Interestingly, Drosophila are protected from S M. abscessus infection when He-or anceexpressing cells were depleted by expressing the pro-apoptotic debcl gene.…”