Development of human beta cell models for host-virus interaction studies

BACKGROUND:

Epidemiological research and studies on patient samples have indicated that enterovirus infections, especially the ones caused by Coxsackieviruses (CVB) are connected to type 1 diabetes (T1D). We have hypothesized that CVB infections predispose genetically susceptible individuals to T1D either by altering the HLA class I peptidome of infected beta cells making them more vulnerable to CD8+ T cell mediated immune attack, or by activating destructive innate immune responses. The aim of the present study was to assess the suitability of human beta cell lines for mechanistic testing of these hypotheses.

METHODS:

Human beta cells were infected with different serotypes of type B Coxsackieviruses. The conditions for infection were optimized for reaching a high infection efficiency, as evaluated by the detection of viral capsid protein, VP1, and the viral genome replication product dsRNA using flow cytometry. The production of infectious viral progeny was validated using a standard plaque assay technique. Changes in cell phenotype induced by CVB infection and interferon stimulation, mimicking a pro-inflammatory environment, were measured by flow cytometry and transcriptomics tools.

RESULTS:

We have established models for CVB infection in human beta cell lines, reaching an infection efficiency above 50%. We have observed that the Coxsackie virus and adenovirus receptor (CAR) is expressed on the surface of human beta cells and serves as a primary entry receptor for CVBs. Pre-stimulation of beta cells with interferons induces a cellular antiviral state significantly reducing permissiveness to infection. At steady state, the CVB infection cycle is completed resulting in the release of infectious CVB virions. Along with the VP1 and dsRNA expression data, this indicates that all CVB protein components are expressed and available for antigen processing and peptide presentation by infected beta cells.