Cellular distribution of CD200 receptor in rats and its interaction with cytomegalovirus e127 protein
CD200 is a membrane protein that interacts with CD200R on the surface of immune cells and delivers an inhibitory signal. In this study, we characterized the distribution of inhibitory CD200R in rats. In addition, we investigated if e127, a homologue of rat CD200 expressed by rat cytomegalovirus (RCMV), can suppress immune functions in vitro. RT-PCR analysis was carried out to test the expression of CD200R in different rat tissues and flow cytometry was performed to characterize CD200R at the cellular level. To test the inhibitory functions of e127, a co-culture system was utilized in which immune cells were incubated with e127-expressing cells. The strongest CD200R expression was detected in lymphoid organs such as bone marrow and spleen. Flow cytometry analyses showed that CD200R+ cells were mainly CD4− dendritic cells (DC) and CD4+ T cells in the spleen. In blood, nearly all monocytes and granulocytes expressed CD200R and in bone marrow the NKRP1low subset of natural killer cells highly expressed CD200R. In addition, both peritoneal macrophages and the NR8383 macrophage cell line carried CD200R. At the functional level, viral e127 conferred an inhibitory signal on TNFα and IL6 cytokine release from IFNγ-stimulated macrophages. However, e127 did not affect the cytotoxic activity of DC. CD200R in the rat is mainly expressed on myeloid cells but also on non-myeloid cell subsets, and RCMV e127 can deliver inhibitory signals to immune cells by engaging CD200R. The RCMV model provides a useful tool to study potential immune evasion mechanisms of the herpesviridae and opens new avenues for understanding and controlling herpesvirus infections.
KeywordsCytomegalovirus e127 protein CD200 receptor Viral CD200 homologues Viral immune evasion
Mohamed A. El-Mokhtar was kindly supported by the GERLS (German Egyptian Research Long-Term Scholarships) program from the German Academic Exchange Service (DAAD).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The rats were kept under specific pathogen-free conditions with ad libitum diet at the animal facility of the Robert Koch Institute. All procedures performed involving animals were in accordance with the ethical standards of the Robert Koch Institute, Berlin, Germany, and were approved by the ethics committee of Berlin state authorities.
- 4.Lyons A, McQuillan K, Deighan BF, O’Reilly JA, Downer EJ, Murphy AC, Watson M, Piazza A, O’Connell F, Griffin R, Mills KH, Lynch MA (2009) Decreased neuronal CD200 expression in IL-4-deficient mice results in increased neuroinflammation in response to lipopolysaccharide. Brain Behav Immun 23(7):1020–1027CrossRefGoogle Scholar
- 17.Misstear K, Chanas SA, Rezaee SA, Colman R, Quinn LL, Long HM, Goodyear O, Lord JM, Hislop AD, Blackbourn DJ (2012) Suppression of antigen-specific T cell responses by the Kaposi’s sarcoma-associated herpesvirus viral OX2 protein and its cellular orthologue, CD200. J Virol 86(11):6246–6257CrossRefGoogle Scholar
- 30.Voigt S, Sandford GR, Hayward GS, Burns WH (2005) The English strain of rat cytomegalovirus (CMV) contains a novel captured CD200 (vOX2) gene and a spliced CC chemokine upstream from the major immediate-early region: further evidence for a separate evolutionary lineage from that of rat CMV Maastricht. J Gen Virol 86(Pt 2):263–274CrossRefGoogle Scholar
- 47.Wright GJ, Cherwinski H, Foster-Cuevas M, Brooke G, Puklavec MJ, Bigler M, Song Y, Jenmalm M, Gorman D, McClanahan T, Liu MR, Brown MH, Sedgwick JD, Phillips JH, Barclay AN (2003) Characterization of the CD200 receptor family in mice and humans and their interactions with CD200. J Immunol 171(6):3034–3046CrossRefGoogle Scholar
- 49.Mehta M, Hetta HF, Abdel-Hameed EA, Rouster SD, Hossain M, Mekky MA, Khalil NK, Mohamed WA, El-Feky MA, Ahmed SH, Daef EA, El-Mokhtar MA, Abdelwahab SF, Medhat A, Sherman KE, Shata MT (2016) Association between IL28B rs12979860 single nucleotide polymorphism and the frequency of colonic Treg in chronically HCV-infected patients. Arch Virol 161(11):3161–3169CrossRefGoogle Scholar
- 64.Kretz-Rommel A, Qin F, Dakappagari N, Ravey EP, McWhirter J, Oltean D, Frederickson S, Maruyama T, Wild MA, Nolan MJ, Wu D, Springhorn J, Bowdish KS (2007) CD200 expression on tumor cells suppresses antitumor immunity: new approaches to cancer immunotherapy. J Immunol 178(9):5595–5605CrossRefGoogle Scholar