Prolonged Transcriptional Consequences in Survivors of Sepsis

Abstract

Survivors of sepsis often suffer from prolonged post-critical illness syndrome secondary to the immune system's reprogramming. It is unclear if this process is static and pervasive due to methodological difficulties studying long-term outcomes of sepsis. The purpose of this study is to evaluate transcriptional profiles longitudinally in Drosophila melanogaster in the aftermath of sepsis to provide preliminary data for targets playing a role in post-sepsis immunostasis. Adult Drosophila melanogaster were infected with E. coli, and survivors were euthanized at 7, 14, and 21 days. Control flies were subjected to sham stress. Gene profiling was done with RNA-seq, and potential miRNA factors were computed. Profiling identified 55 unique genes at seven days, 61 unique genes at 14 days, and 78 genes at 21 days in sepsis survivors vs. sham control. Each post-sepsis timepoint had a distinctive transcriptional pattern with a signature related to oxidative stress at seven days, neuronal signal transduction at 14 days, and metabolism at 21 days. Several potential miRNA patterns were computed as potentially affecting several of the genes expressed in sepsis survivors. Our study demonstrated that post-sepsis changes in the transcriptome profile are dynamic and extend well into the Drosophila melanogaster natural life span.

Keywords: Drosophila melanogaster; RNA-seq; bacteremia; genomic profiling; glutathione pathway; gram-negative; long-term; metabolomic; miRNA; post-septic syndrome; sepsis; survival.

Figure 1

Distribution and number of genes that were differentially expressed at 14 (C_14) (A) and 21 (C_21) (B) days as compared to animals without surgery (C_0).

Figure 2

Sham surgery resulted in changes in gene expression over time (A), which was to a certain degree observed in sepsis survivors (B). Distinctive gene expression was seen when comparing flies surviving 21 days after sepsis compared to one and two week survivors or control animals. Unique gene patterns at 7, 14, and 21 among sepsis survivors can be seen (C).

Figure 3

Abnormal expression of glutathione gene among Drosophila surviving sepsis is the dominant trait seen in our study.

Figure 4

All of the genes analyzed had potential targeting sites by different microRNAs. The frequency of miR-315-5p in the gene list was highest and, notably, evolutionarily conserved among multiple Drosophila species unlike any other microRNAs studied. The involvement in miR-315-5p suggests several potential targets.