Interferon Gamma Therapy in a Novel Case of Homozygous Interferon Alpha/beta Receptor Alpha Chain (IFNAR1) Deciency Infected With SARS-CoV-2

Background: Interferons play a crucial role in antiviral immunity. Genetic defects in interferon receptors (IFNRs) can lead to the development of life-threatening forms of infectious diseases. Case presentation: A thirteen-year-old boy with a novel mutation in interferon alpha/beta receptor subunit 1 (IFNAR1)(c.674-2A>G) was diagnosed with COVID-19. He had cold symptoms and a high-grade fever at the time of admission. He was admitted to the pediatric intensive care unit after showing no response to favipiravir. High-resolution computed tomography (HRCT) scanning revealed lung involvement of 70% with extensive areas of consolidation in both lungs. Antibiotics, interferon gamma (IFN-γ), remdesivir, methylprednisolone pulse, and other medications were started in the patient. However, remdesivir and methylprednisolone pulse were discontinued after the occurrence of hypertension and bradycardia in the patient. His general condition improved, and a few days later was discharged from the hospital. Conclusion: We reported a COVID-19 patient who had a novel mutation in IFNAR1 and was treated with IFN-γ. Our ndings and approach to managing this COVID-19 patient suggest that IFN-γ therapy could be an appropriate choice to treat patients with defects in IFN-α/β signaling pathways.

Generally, INFAR2 has a higher a nity for ligands, but recent studies have shown that IFN-β has the tightest binding among IFNs, which is associated with IFNAR1 [2]. Activation of IFNAR by IFN-α and IFN-β leads to tyrosine phosphorylation of several proteins, such as Janus kinase 1 (JAK1), tyrosine kinase 2 (TYK2), signal transducer and activator of transcription (STAT) proteins, and the subunits of IFNAR themselves in JAK-STAT signaling pathway [1]. IFNAR1 interacts with TYK2, and IFNAR2 interacts with JAK1 and STAT proteins. Then, STAT proteins become transported to the nucleus and act as transcription factors inducing/suppressing expression of interferon-stimulated genes (ISGs) that are associated with the immune system [2]. STAT proteins play their aforementioned role by interferon regulatory factor 9 (IRF9) to form the ISG factor 3 (ISGF3) complex [3].
Type I interferons are mainly known for their antiviral activity. They play their role by several mechanisms, such as inhibiting viral replication in the early stages of infection, upregulating the effector function of immune cells, triggering the adaptive immune response, and increasing antigen presentation [4]. The production of type I interferons is triggered by toll-like receptors (TLRs) [5]. Individuals with mutations in interferons, their receptors or signaling pathway, and insu cient interferon production show an inadequate antiviral response to the viral infections, which leads to the development of the lifethreatening form of the disease [6]. For instance, patients with mutated IFNAR show adverse reaction to vaccination with live attenuated vaccines, such as measles, mumps, and rubella (MMR), and yellow fever vaccine [7]. Investigations in individuals with coronavirus disease (COVID-19) showed that patients with genetic defects in the TLR pathway or IFNAR are more prone to developing severe forms of COVID-19 associated pneumonia than others [5,8]. Previously, type I interferons were administered to treat COVID-19 patients with a genetic defect in the production of type I interferon pathways, which improved their symptoms [9]. The result of a clinical trial showed that administration of IFN-β decreases the time to clinical improvement in COVID-19 patients [10]. Another study revealed the positive effect of interferon gamma (IFN-γ) (type II interferon) in patient with moderate COVID-19 [11]. Hence, interferons may be a potential drug for treating COVID-19 patients with inborn type I interferon immunity errors. However, IFNAR de ciency complicates the administration of IFN-α/β for patients with COVID-19 since they have impaired receptors for type I interferons. Considering this fact, we reported a novel case of homozygous IFNAR1 de ciency infected with SARS-CoV-2, who was treated with IFN-γ.

Case Presentation
A thirteen-year-old boy with IFNAR1 de ciency was admitted to Bushehr Khalij Fars Hospital, Bushehr, Iran, in April 2021. He presented with upper respiratory tracts infection symptoms, such as runny nose, itchy throat, and low-grade fever for 11 days, followed by sweating and high-grade fever in the last three days. The patient only had a history of meningitis after getting vaccinated for MMR at 12 months of age.
He was a suspected case of COVID-19, con rmed by a positive COVID-19 polymerase chain reaction (PCR) test. The treatment was initiated with favipiravir; however, the patient showed no response to the therapy, and his symptoms worsened, including shortness of breath and persistent fevers. Therefore, he was admitted to the pediatric intensive care unit (PICU). The result of high-resolution computed tomography (HRCT) scanning revealed lung involvement of 70% with extensive areas of consolidation in both lungs and patchy consolidation in the base of the lungs (see Fig. 1). The result of his echo test was normal. The oxygen saturation (SpO2) of the patient at the rst emergency department visit was 94% but decreased to 90% within the rst days after hospitalization.
After hospitalization, the patient received vancomycin, piperacillin, tazobactam, aspirin, famotidine, zinc, vitamin C, IFN-γ, remdesivir, and methylprednisolone pulse (30mg/kg). Two days after hospitalization, the patient's fever persisted, and the antibiotics were switched to colistin and teicoplanin, and caspofungin was added to his medications. Although the level of IL-6 was high in the patient's serum, tocilizumab was not initiated for the patient due to the prolonged prothrombin time (PT) and partial thromboplastin time (PTT) (see Table 1). Because of the critical condition of the patient, he received one dose (1gr/kg) of intravenous immune globulin (IVIG). The patient also received IFN-γ (50µg/m 2 ) between the third and sixth days of hospitalization (4 doses). On the fth day of hospitalization, the patient had bradycardia and hypertension; however, the second echo test and cardiology consultation were normal. Atropine was prescribed for the patient to be used in case the heart rate falls below 40 beats/min. The eye examination showed no papilledema, but pseudotumor cerebri was suspected. Therefore, remdesivir and methylprednisolone pulse were discontinued. After the fth day of hospitalization, his fever was reduced, and his general condition improved on the sixth day of hospitalization. The SpO2 of the patient increased to 94% with nasal cannula oxygen therapy (with a ow of 6 liters/min). The antibiotic therapy was continued for ten days, and the patient received fresh frozen plasma (FFP) (10cc/kg) to treat his prolonged PT and abnormal international normalized ratio (INR). During hospitalization, the patient had recurrent panic attacks that led to a lower SpO2 below 90%. Hence, the psychologist prescribed risperidone, pill every night.
Eight days after hospitalization, the patient had a good general condition and was moved to the ward from PICU. On the ninth day of hospitalization, the patient's SpO2 was above 94% without oxygen therapy, and two days later, he was discharged from the hospital.

IFNAR1 de ciency
The presented case was born to consanguineous parents and had a sister who passed away after getting vaccinated for MMR. As mentioned before, the patient had a history of meningitis after getting vaccinated for MMR at 12 months of age that led to his recurrent hospitalization due to fever twice a 1 4 year. The periodic neutropenia disorder was suspected in the patient. Therefore, to nd the underlying genetic cause of the disease, whole exome sequencing (WES) was performed as previously described [7]. The result of WES (see Table 2) revealed a novel homozygous mutation in the IFNAR1 gene at the splicing site of exon 6 (NM_000629 Exon6:c.674(-2b)A>G). The Sanger sequencing analysis indicated that the parents, as expected, were heterozygous for such mutation. However, given the function of IFNAR1, the high effect of splicing mutation and heterozygosity of parents, the causative effect of this mutation on the disease is highly suggested.

Discussion
In this case report, presented a COVID-19 case who had a novel IFNAR1 de ciency. COVID-19, caused by SARS-CoV-2, has been a global concern since its emergence in 2020 [12]. We treated our IFNAR1 de cient patient, who was infected with SARS-CoV-2, with IFN-γ administration. IFN-γ is a type II interferon produced by activated T cells and natural killer cells that binds interferongamma receptor (IFNGR) complex protein, and consequently, activates JAK/STAT pathway [14]. The activation of JAK/STAT pathway leads to induction/suppression of the transcription of IFN-γ-regulated genes [15]. IFN-γ has several functions, including antiviral immunity, macrophage activation, T helper 1 (Th1)/Th2 balance, regulation of apoptosis, and increasing antigen presentation via major histocompatibility complex (MHC) I and MHC II pathway [14]. IFN-γ induces antiviral immunity via inhibiting viral entry, suppressing virus replication, inducing cytokine production by immune cells, and enhancing cytotoxic T lymphocyte killing activity and phagocytosis. Nevertheless, due to the proin ammatory nature of the IFN-γ, persistently high levels of IFN-γ can lead to the occurrence of cytokine  [15]. Administration of type I interferon in patients with IFNAR1 de ciency is ineffective. Based on this fact, we considered IFN-γ therapy for our patient. It should be noted that we discontinued IFN-γ therapy after the sixth day of hospitalization since the persistently high levels of IFN-γ may lead to cytokine storm in the later stages of the disease [17].
As mentioned before, on the fth day of hospitalization, our patient showed symptoms similar to Cushing's (bradycardia and hypertension) [18], which indicates increased intracranial pressure. The corticosteroid therapy was discontinued in the patient since pseudotumor cerebri is one of the side effects of corticosteroids [19]. Unfortunately, Due to the patient's critical condition, further investigations for measuring intracranial pressure were not possible. Additionally, remdesivir was also discontinued because of its adverse cardiac effects, including bradycardia [20].
To the best of our knowledge, we reported the rst case with novel IFNAR1 de ciency that is infected with SARS-CoV-2, and treated with IFN-γ. Our ndings and approach to managing this COVID-19 patient suggest that IFN therapy could be an appropriate choice to treat patients with defects in IFN production and signaling pathways.
Declarations Figure 1 Lung HRCTs on admission day (left) and a few days later during hospitalization (right); A. Axial HRCT, aortic arch level. Extensive consolidation in upper lobes is seen; B. Axial HRCT, subcarinal level. Patchy con uent consolidation is turning to ground glass attenuation on the second study; C. Axial HRCT, basilar area. There are a few nodular consolidations in the rst study (arrows). Patchy con uent consolidations and ground glass opacities are noted on the second study