Comparative RNA-Seq analyses of Drosophila plasmatocytes reveal gene specific signatures in response to clean injury and septic injury

Abstract

Drosophila melanogaster's blood cells (hemocytes) play essential roles in wound healing and are involved in clearing microbial infections. Here, we report the transcriptional changes of larval plasmatocytes after clean injury or infection with the Gram-negative bacterium Escherichia coli or the Gram-positive bacterium Staphylococcus aureus compared to hemocytes recovered from unchallenged larvae via RNA-Sequencing. This study reveals 676 differentially expressed genes (DEGs) in hemocytes from clean injury samples compared to unchallenged samples, and 235 and 184 DEGs in E. coli and S. aureus samples respectively compared to clean injury samples. The clean injury samples showed enriched DEGs for immunity, clotting, cytoskeleton, cell migration, hemocyte differentiation, and indicated a metabolic reprogramming to aerobic glycolysis, a well-defined metabolic adaptation observed in mammalian macrophages. Microbial infections trigger significant transcription of immune genes, with significant differences between the E. coli and S. aureus samples suggesting that hemocytes have the ability to engage various programs upon infection. Collectively, our data bring new insights on Drosophila hemocyte function and open the route to post-genomic functional analysis of the cellular immune response.

Identification of silkworm hemocyte subsets and analysis of their response to BmNPV infection based on single-cell RNA sequencing

“…Also the increased expression of a gene associated with protein glycosylation, which is most often associated with secreted and membrane proteins, is conform to such function. With respect to the potential expression of an aquaporin genes, it is noted that in Drosophila , the aquaporin Prip is one of the most enriched genes in plasmatocytes (Ramond et al, 2020) and another aquaporin, Drip, is enriched in lamellocytes (Tattikota et al, 2020). During cellular immunity in Spodoptera exigua , aquaporins are involved in the regulation of cell shape (Ahmed and Kim, 2019).…”

Polarization of Macrophages in Insects: Opening Gates for Immuno-Metabolic Research

“…That may be supported by transcriptomic data characterizing Drosophila immune cells with various stimuli. In larvae, both differentiating and proliferating immune cells display hallmarks of increased glycolytic rate and conversion of pyruvate to lactate resembling aerobic glycolysis ( Irving et al, 2005 ; Johansson et al, 2005 ; Bajgar et al, 2015 ; Ramond et al, 2020 ). The versatility of Drosophila immune cells and their metabolic response to the activating stimuli may be further documented by the single-cell transcriptomic analysis published recently ( Tattikota et al, 2020 ), which shows the above-mentioned patterns in raw data.…”

“…Recently, it has been deciphered that ImpL2 is released from infection-activated plasmatocytes during acute immune response in Drosophila ( Krejčová et al, 2020 ; Figure 3 ). However, a recently published RNA-Seq analysis of Drosophila larval plasmatocytes revealed neither an increase in ImpL2 transcripts upon septic injury nor enriched expression of ImpL2 in plasmatocytes ( Ramond et al, 2020 ). That is in concordance with other observations showing that larval ImpL2 is expressed in the fat body rather than in circulating immune cells.…”

“…Recently, the concept of immuno-metabolism has been developed in mammals, which indicates that several populations of mammalian immune cells must adopt a specific cellular metabolism in order to perform the desired function ( Galván-peña and O’Neill, 2014 ). Although there are still some doubts about an analogous mechanism for Drosophila plasmatocytes, several publications and transcriptomic data document this ability ( Krejčová et al, 2019 ; Cattenoz et al, 2020 ; Ramond et al, 2020 ; Tattikota et al, 2020 ). These observations are necessary not only for a comprehensive understanding of the antibacterial immune response but may become a base for research of many other human diseases that are connected with the pathological metabolic polarization of mammalian immune cells.…”

Paths and Pathways that Generate Cell-Type Heterogeneity and Developmental Progression in Hematopoiesis

“…RNA-Seq has been used recently as a technique to study Drosophila blood cells (Cattenoz et al 2020; Cho et al 2020; Fu et al 2020; Ramond et al 2020; Tattikota et al 2020). However, several important distinctions make this current work broadly relevant to developmental biology.…”