Abstract
Background: The infection of a participant with norovirus during the adaptive study of interleukin-2 dose on regulatory T cells in type 1 diabetes (DILT1D) allowed a detailed insight into the cellular and cytokine immune responses to this prevalent gastrointestinal pathogen.Methods: Serial blood, serum and peripheral blood mononuclear cell (PBMC) samples were collected pre-, and post-development of the infection. To differentiate between the immune response to norovirus and to control for the administration of a single dose of aldesleukin (recombinant interleukin-2, rIL-2) alone, samples from five non-infected participants administered similar doses were analysed in parallel.Results: Norovirus infection was self-limited and resolved within 24 hours, with the subsequent development of anti-norovirus antibodies. Serum pro- and anti-inflammatory cytokine levels, including IL-10, peaked during the symptomatic period of infection, coincident with increased frequencies of monocytes and neutrophils. At the same time, the frequency of regulatory CD4+T cell (Treg), effector T cell (Teff) CD4+and CD8+subsets were dynamically reduced, rebounding to baseline levels or above at the next sampling point 24 hours later. NK cells and NKT cells transiently increased CD69 expression and classical monocytes expressed increased levels of CD40, HLA-DR and SIGLEC-1, biomarkers of an interferon response. We also observed activation and mobilisation of Teffs, where increased frequencies of CD69+and Ki-67+effector memory Teffs were followed by the emergence of memory CD8+Teff expressing the mucosal tissue homing markers CD103 and β7 integrin. Treg responses were coincident with the innate cell, Teff and cytokine response. Key Treg molecules FOXP3, CTLA-4, and CD25 were upregulated following infection, alongside an increase in frequency of Tregs with the capacity to home to tissues.Conclusions: The results illustrate the innate, adaptive and counter-regulatory immune responses to norovirus infection. Low-dose IL-2 administration induces many of the Treg responses observed during infection.
Highlights
We conducted an interleukin-2 (IL-2; aldesleukin [Proleukin]) dose-finding, mechanistic trial, “Adaptive study of IL-2 dose on regulatory T cells in type 1 diabetes” (DILT1D), in 40 participants with type 1 diabetes (T1D), as a first step towards treatment and prevention of T1D by enhancing Treg functions[1,2]
Study design The adaptive study of IL-2 dose on Tregs in T1D (DILT1D) was a 60-day duration, single center, single dose non-randomised, open label, adaptive dose-finding trial that was conducted at the National Institute for Health Research Cambridge Biomedical Centre, Addenbrooke’s Hospital, Cambridge, United Kingdom[1]
The adaptive clinical trial DILT1D was primarily designed to examine the Treg response to a single dose of IL-2 and we noted the similarity between the systemic response of Tregs to the drug to that induced by norovirus infection
Summary
We conducted an interleukin-2 (IL-2; aldesleukin [Proleukin]) dose-finding, mechanistic trial, “Adaptive study of IL-2 dose on regulatory T cells in type 1 diabetes” (DILT1D), in 40 participants with type 1 diabetes (T1D), as a first step towards treatment and prevention of T1D by enhancing Treg functions[1,2]. Adverse events were recorded throughout the trial and one participant developed an acute gastrointestinal infection, confirmed as norovirus, in the period of daily sampling post-IL-2 injection. A functional immune system is imperative for acute control of norovirus infection in humans[7], and pre-existing anti-norovirus IgA antibody titers negatively correlate with severity of symptoms in human challenge studies[8]. The infection of a participant with norovirus during the adaptive study of interleukin-2 dose on regulatory T cells in type 1 diabetes (DILT1D) allowed a detailed insight into the cellular and cytokine immune responses to this prevalent gastrointestinal pathogen. To differentiate between the immune response to norovirus and to control for the administration of a single dose of aldesleukin (recombinant interleukin-2, rIL-2) alone, samples from five non-infected participants administered similar doses were analysed in parallel. We observed activation and mobilisation of Teffs, where increased frequencies of CD69+ and Ki-67+
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