In a recent study published in Science Immunology, researchers investigated whether individuals with breakthrough infections of severe coronavirus disease 2019 (COVID-19) pneumonia demonstrated normal antibody responses to vaccinations and whether they harbored type I interferon (IFN)-neutralizing auto-antibodies (auto-Abs).
Fatal breakthrough cases of severe COVID-19 have been linked to waning or poor Ab responses to SARS-CoV-2 vaccinations among high-risk individuals. Pre-existing type I IFN-neutralizing auto-Abs are underlying factors for >15% of cases of severe COVID-19-associated pneumonia among unvaccinated persons; however, the contribution of type I IFN-neutralizing auto-Abs to hypoxemic breakthrough infection cases among vaccinated individuals is unknown.
About the study
In the present study, researchers investigated whether individuals with breakthrough infections of severe COVID-19 pneumonia demonstrated normal antibody responses to vaccinations and whether they harbored type I IFN- neutralizing auto-Abs.
The team enrolled and tested COVID Human Genetic Effort (CHGE) patients with breakthrough SARS-CoV-2 infections and hypoxemic pneumonia. Forty-eight persons (aged 20 to 86 years, 14 females and 34 males) who had received two doses of messenger ribonucleic acid (mRNA) vaccinations and developed breakthrough infections with hypoxemic COVID-19-associated pneumonia after two weeks to four months were chosen for the analysis. In addition, 11 and 12 BNT162b2 vaccinated and unvaccinated controls, respectively, were analyzed.
The participants were enrolled from six nations, namely, Greece, France, Turkey, North Macedonia, the United States of America, and Ukraine. Five participants had known B lymphocyte immunodeficiencies, of which three patients received immunosuppressive therapies, one patient had human immunodeficiency virus (HIV) infection, and one patient had lymphoma and was under chimeric antigen receptor (CAR)-T lymphocyte treatment.
The serum antibody titers induced by BNT162b2 vaccinations, SARS-CoV-2 neutralization, and type I IFN-neutralizing auto-Abs were determined. Further, patients without known B lymphocyte immunodeficiency who elicited normal antibody responses to mRNA vaccinations were tested for immunoglobulin G (IgG) auto-Abs against type I IFN. Next, patients with anti-IFN IgG were tested for their neutralization potency against IFN-α2, IFN-β, IFN- ω at 10 ng/mL, 10 ng/mL (high concentration) and 100 pg/mL (low concentration) respectively.
Sera of BNT162b2 vaccinated healthy individuals/controls who had no history of prior SARS-CoV-2 infections were assessed using anti-SARS-CoV-2 nucleocapsid (N) protein assays. The anti-cytokine (IFN type I) auto-Abs were detected using enzyme-linked immunosorbent assays (ELISA) and the anti-IFN-α2 auto-Abs were detected using radioligand binding assays (RLBA). Luciferase reporter assays were performed to evaluate the blocking activities of anti-IFN-ω and anti-IFN-α2 autoAbs. In addition, Luminex assays and pseudovirus neutralization assays were also performed.
Critical/severe COVID-19 pneumonia was described as cases of pneumonia developing in patients with critical illness, whether respiratory, requiring high-flow oxygen, requiring mechanical ventilators, septic shock, or any organ injury requiring intensive care unit (ICU) admission. Severe SARS-CoV-2 infections were described as COVID-19 cases developing pneumonia and requiring low-flow oxygen.
Results and discussion
Out of 48 patients with severely hypoxemic COVID-19 pneumonia, 42 didn’t have known B lymphocyte immune deficiencies and demonstrated normal antibody responses to vaccinations, and 10 (out of 42) individuals (24%) aged 43 to 86 years showed type I IFN-neutralizing auto-Abs. Out of these 10 individuals, eight individuals showed IFN-α2-neutralizing and also IFN-ω-neutralizing auto-Abs, whereas two individuals showed only IFN-ω neutralization.
None of the study participants showed IFN-β neutralization. Seven and three individuals neutralized high concentration (10 ng/mL) and low concentration (100 pg/mL) of IFNs type I, respectively. Seven participants and one participant effectively neutralized SARS-CoV-2 the D614G strain and the Delta strain, respectively. Two participants (out of three participants who neutralized 100 pg/mL of IFNs type I) showed less efficient neutralization of the D61G strain and the Delta strain.
Type I IFN-neutralizing auto Abs were not detected in any of the six participants who were excluded previously due to known B lymphocyte immunodeficiencies (n=5) or insufficient antibody responses to the BNT162b2 mRNA vaccinations (n=1). Participants with anti-IFN-ω and anti-IFN-α2 autoAbs showed lesser induction of luciferase in the luciferase reporter assays.
The immunopathogenesis of fatal COVID-19-associated pneumonia cases involves type I IFN immunodeficiencies, resulting in widespread SARS-CoV-2 spread and exuberant pulmonary and systemic inflammation. Thus, screening for type I IFN-neutralizing auto-Abs at hospitalization could aid in managing persons with hypoxemic pneumonia. For example, monoclonal antibodies (mAbs) that neutralize SARS-CoV-2 could be administered promptly among interferon-regulatory factor 9 (IRF9)-deficient patients, particularly for those with high titers of type I IFN-neutralizing auto-Abs.
Further, mRNA vaccinations have been highly effective in preventing severe COVID-19-associated pneumonia, therefore, it is likely that vaccination is beneficial for the majority of the patients who elicit auto-Abs that neutralize type I interferons. However, this protection may be inadequate for individuals with auto Abs that can efficiently neutralize high concentration type I interferons.
Overall, the study findings showed that despite double BNT162b2 vaccinations, inoculations, and the presence of circulating Ab which had SARS-CoV-2 neutralizing abilities, type I IFN-neutralizing auto-Abs could underlie a substantial proportion of hypoxemic COVID-19 pneumonia cases. The findings indicate that testing for type I IFN-neutralizing auto-Abs among vaccinated individuals with breakthrough cases of COVID-19-associated pneumonia of variable severity may be beneficial.
The health authorities may also consider testing non-infected individuals, including vaccinated persons, especially for those >70 years since increased prevalence (>4%) of type I-neutralizing auto-Abs has been reported among elders. Furthermore, testing individuals with conditions associated with type I interferon-neutralizing auto Abs such as myasthenia gravis and autoimmune polyendocrine syndrome type I (APS-1) may also be beneficial.