RNA-Seq Reveals an Integrated Immune Response in Nucleated Erythrocytes

Abstract

BackgroundThroughout the primary literature and within textbooks, the erythrocyte has been tacitly accepted to have maintained a unique physiological role; namely gas transport and exchange. In non-mammalian vertebrates, nucleated erythrocytes are present in circulation throughout the life cycle and a fragmented series of observations in mammals support a potential role in non-respiratory biological processes. We hypothesised that nucleated erythrocytes could actively participate via ligand-induced transcriptional re-programming in the immune response.Methodology/Principal FindingsNucleated erythrocytes from both fish and birds express and regulate specific pattern recognition receptor (PRR) mRNAs and, thus, are capable of specific pathogen associated molecular pattern (PAMP) detection that is central to the innate immune response. In vitro challenge with diverse PAMPs led to de novo specific mRNA synthesis of both receptors and response factors including interferon-alpha (IFNα) that exhibit a stimulus-specific polysomal shift supporting active translation. RNA-Seq analysis of the PAMP (Poly (I∶C), polyinosinic∶polycytidylic acid)-erythrocyte response uncovered diverse cohorts of differentially expressed mRNA transcripts related to multiple physiological systems including the endocrine, reproductive and immune. Moreover, erythrocyte-derived conditioned mediums induced a type-1 interferon response in macrophages thus supporting an integrative role for the erythrocytes in the immune response.Conclusions/SignificanceWe demonstrate that nucleated erythrocytes in non-mammalian vertebrates spanning significant phylogenetic distance participate in the immune response. RNA-Seq studies highlight a mRNA repertoire that suggests a previously unrecognized integrative role for the erythrocytes in other physiological systems.

The Fish Pathogen Vibrio vulnificus Biotype 2: Epidemiology, Phylogeny, and Virulence Factors Involved in Warm-Water Vibriosis

“…In fact, the transcription of rtxA1 3 was upregulated when the bacteria were cocultured with either granulocytes or erythrocytes, but only if the bacterium and eukaryotic cell were in contact (104). Interestingly, the eel erythrocytes were able to agglutinate the rtxA1 3 deficient strain, which suggests that fish erythrocytes can exert a defensive role against bacterial pathogens as suggested by Morera et al (106). In the light of these results, the authors hypothesized that RtxA1 3 is expressed as a defense mechanism against cells from the innate immune system, destroy them and trigger a cytokine storm that could cause the death of the animals by septic shock.…”

No evidence for immunoproteasomes in chicken lymphoid organs and activated lymphocytes

“…For chicken erythrocytes, thrombocytes as well as bone-marrow-derived DCs, macrophages, and monocyte-derived macrophages, it was already shown that they react to immune stimuli by, e.g., up-or downregulation of chemokine receptors and induction of IFN-γ (Morera et al 2011;St Paul et al 2012a;St Paul et al 2012b;St Paul et al 2012c;Wu and Kaiser 2011). We could confirm that chicken spleen cells incubated with PMA/ionomycin and concanavalin A showed an induction of IFN-γ mRNA and the stimulation was further documented by a strong cell proliferation after PMA/ionomycin treatment.…”

RNA-Seq Technology and Its Application in Fish Transcriptomics

“…These transcripts were found to encode transcription factors, signal transduction proteins, cytokines and chemokines, complement factors, proteins involved in apoptosis and proteolysis, proteins with anti-microbial activities, as well as many known or novel proteins not previously linked to the immune response. Additionally, RNA-Seq analysis of Poly (I:C) (polyinosinic:polycytidylic acid)-challenged rainbow trout erythrocytes revealed diverse groups of differentially expressed mRNA transcripts related to multiple physiological systems including the endocrine, reproductive, and immune systems (Morera et al, 2011).…”