Pancreatic beta cells persistently infected with coxsackievirus B4 are targets of NK cell-mediated cytolytic activity
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It has been suggested that the persistence of coxsackieviruses-B (CV-B) in pancreatic beta cells plays a role in the pathogenesis of type 1 diabetes (T1D). Yet, immunological effectors, especially natural killer (NK) cells, are supposed to clear virus-infected cells. Therefore, an evaluation of the response of NK cells to pancreatic beta cells persistently infected with CV-B4 was conducted. A persistent CV-B4 infection was established in 1.1B4 pancreatic beta cells. Infectious particles were found in supernatants throughout the culture period. The proportion of cells containing viral protein VP1 was low (< 5%), although a large proportion of cells harbored viral RNA (around 50%), whilst cell viability was preserved. HLA class I cell surface expression was downregulated in persistently infected cultures, but HLA class I mRNA levels were unchanged in comparison with mock-infected cells. The cytolytic activities of IL-2-activated non-adherent peripheral blood mononuclear cells (PBMCs) and of NK cells were higher towards persistently infected cells than towards mock-infected cells, as assessed by an LDH release assay. Impaired cytolytic activity of IL-2-activated non-adherent PBMCs from patients with T1D towards infected beta cells was observed. In conclusion, pancreatic beta cells persistently infected with CV-B4 can be lysed by NK cells, implying that impaired cytolytic activity of these effector cells may play a role in the persistence of CV-B in the host and thus in the viral pathogenesis of T1D.
KeywordsEnterovirus Persistence HLA class I Type 1 diabetes LDH assay
This work was supported by Ministere de l’Education Nationale de la Recherche et de la Technologie, Universite Lille 2 (Equipe d’accueil 3610), Centre Hospitalier Regional et Universitaire de Lille, and by EU FP7 (GA-261441-PEVNET: Persistent virus infection as a cause of pathogenic inlammation in type 1 diabetes—an innovative research program of biobanks and expertise). M. P. N was supported by a “CABRI 2016” scholarship of Universite Lille 2 and a “Programme Eifel 2017” scholarship of Ministere des Afaires etrangeres et du Developpement International de la Republique Francaise. Funding was supported by Campus France (EIFFELDOCTORAT 2017/n°P714914K). The authors thank Dr Sarah Richardson (Exeter, UK) for helpful discussion. The authors thank Dr Adrian J. F. Luty for reading the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.
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