Mild COVID-19 despite autoantibodies against type I IFNs in autoimmune polyendocrine syndrome type 1

Abstract

Autoantibodies against IFN-α and IFN-ω (type I IFNs) were recently reported as causative for severe COVID-19 in the general population. Autoantibodies against IFN-α and IFN-ω are present in almost all patients with autoimmune polyendocrine syndrome type 1 (APS-1) caused by biallelic deleterious or heterozygous dominant mutations in AIRE. We therefore hypothesized that autoantibodies against type I IFNs also predispose patients with APS-1 to severe COVID-19. We prospectively studied 6 patients with APS-1 between April 1, 2020 and April 1, 2021. Biobanked pre-COVID-19 sera of APS-1 subjects were tested for neutralizing autoantibodies against IFN-α and IFN-ω. The ability of the patients' sera to block recombinant human IFN-α and IFN-ω was assessed by assays quantifying phosphorylation of signal transducer and activator of transcription 1 (STAT1) as well as infection-based IFN-neutralization assays. We describe 4 patients with APS-1 and preexisting high titers of neutralizing autoantibodies against IFN-α and IFN-ω who contracted SARS-CoV-2, yet developed only mild symptoms of COVID-19. None of the patients developed dyspnea, oxygen requirement, or high temperature. All infected patients with APS-1 were females and younger than 26 years of age. Clinical penetrance of neutralizing autoantibodies against type I IFNs for severe COVID-19 is not complete.

Keywords: COVID-19; Immunology; Innate immunity.

Figure 1. Neutralizing auto-Abs against IFN-α2 and IFN-ω in patients with APS-1.

(A) Detection of IgG auto-Abs against IFN-α2, IFN-ω, IFN-β, IFN-γ, IL-6, and GM-CSF in sera (1:100 dilution) from patients with APS-1 (P1–P6), healthy controls (NEG, n = 17), and patients with known auto-Abs against IFN-γ, IL-6, and GM-CSF (POS, n = 1). Detection of auto-Abs against (B) IFN-α2 and (C) IFN-ω in serially diluted patient sera. Dotted lines indicate the maximum light signal counts (LSC) in the anti–IFN-α2 and anti–IFN-ω assay in the cohort of healthy controls. (D) FACS histograms depicting STAT1 phosphorylation (p-STAT1) in whole-blood monocytes from a healthy control and 4 APS-1 patients stimulated with IFN-α2 (1 and 10 ng/mL) or IFN-γ (10 ng/mL).

Figure 2. Auto-Abs in patients with APS-1 neutralize the ability of type I IFNs to inhibit SARS-CoV-2 infection.

Calu-3 cells were mock treated (no serum) or pretreated with indicated concentrations of human serum in the presence or absence of 200 IU/mL IFN-α2a (A and D) or 5 ng/mL IFN-ω (B and E) for 16 hours before infection. IFN and serum were removed, and cells were infected with SARS-CoV-2 at an MOI of 0.01 for 1 hour, washed, and fresh medium was applied to the cells. Twenty-four hours after infection, supernatant was harvested for viral RNA extraction and plaque assays. (A–C) Viral RNA was extracted from supernatant and SARS-CoV-2 genome equivalents/μL were quantified by qRT-PCR using primers targeting the E gene region. (D–F) Supernatants were titrated on Vero E6 cells and incubated for plaque formation for 3 days. Plaques were counted and PFU/mL was determined. Data were generated in 2 independent assays. Values obtained in the absence of serum and IFN were set to 100%.