Human inherited complete STAT2 deficiency underlies inflammatory viral diseases.

STAT2 is a transcription factor activated by type I and III IFNs. We report 23 patients with loss-of-function variants causing autosomal recessive (AR) complete STAT2 deficiency. Both cells transfected with mutant STAT2 alleles and the patients' cells displayed impaired expression of IFN-stimulated genes and impaired control of in vitro viral infections. Clinical manifestations from early childhood onward included severe adverse reaction to live attenuated viral vaccines (LAV) and severe viral infections, particularly critical influenza pneumonia, critical COVID-19 pneumonia, and herpes simplex virus type 1 (HSV-1) encephalitis. The patients displayed various types of hyperinflammation, often triggered by viral infection or after LAV administration, which probably attested to unresolved viral infection in the absence of STAT2-dependent types I and III IFN immunity. Transcriptomic analysis revealed that circulating monocytes, neutrophils, and CD8+ memory T cells contributed to this inflammation. Several patients died from viral infection or heart failure during a febrile illness with no identified etiology. Notably, the highest mortality occurred during early childhood. These findings show that AR complete STAT2 deficiency underlay severe viral diseases and substantially impacts survival.

Haploidentical CD3+ TCR αß/CD19+ depleted HSCT for MHC Class II deficiency and persistent SARS-CoV-2 pneumonitis.

Background & Objectives: SARS-CoV-2 infection leads to coronavirus disease 2019 (COVID-19), which can range from a mild illness to a severe phenotype characterised by acute respiratory distress, needing mechanical ventilation. Children with combined immunodeficiencies might be unable to mount a sufficient cellular and humoral immune response against Covid-19 and have persistent disease. The authors describe a child with combined immunodeficiency, with favorable post-HSCT course following a haploidentical haematopoietic stem cell transplant in the presence of persistent SARS-CoV-2 infection. Methods & results: A 13-month-old girl with MHC class II deficiency developed persistent pre-HSCT SARS-CoV-2 infection. Faced with a significant challenge of balancing the risk of progressive infection due to incompetent immune system with the danger of inflammatory pneumonitis peri-immune reconstitution post-HSCT, she underwent a maternal (with a recent history of Covid-19 infection) haploidentical haematopoietic stem cell transplant. The patient received Regdanvimab® (post stem cell infusion) and Remdesivir (pre and post stem cell infusion). We noted a gradual increase in the Ct (cycle threshold) values, implying reduction in viral RNA with concomitant expansion in the CD3 lymphocyte subset and clinical/radiological improvement. Conclusions: Combination of adoptive transfer of maternal CD45RO+ memory add-back T-lymphocytes after haploidentical HSCT, use of Regdanvimab® (SARS-CoV-2 neutralising monoclonal antibody) and Remdesivir may have led to the successful outcome in our patient with severe immunodeficiency, undergoing HSCT. Our case highlights the role of novel antiviral strategies (monoclonal antibodies and CD45RO+ memory T-lymphocytes) in contributing to viral clearance in a challenging clinical scenario.

Haploidentical CD3+ TCR αβ/CD19+ depleted HSCT for MHC Class II deficiency and persistent SARS-CoV-2 pneumonitis

Background & Objectives SARS-CoV-2 infection leads to coronavirus disease 2019 (COVID-19), which can range from a mild illness to a severe phenotype characterised by acute respiratory distress, needing mechanical ventilation. Children with combined immunodeficiencies might be unable to mount a sufficient cellular and humoral immune response against Covid-19 and have persistent disease. The authors describe a child with combined immunodeficiency, with favorable post-HSCT course following a haploidentical haematopoietic stem cell transplant in the presence of persistent SARS-CoV-2 infection. Methods & results A 13-month-old girl with MHC class II deficiency developed persistent pre-HSCT SARS-CoV-2 infection. Faced with a significant challenge of balancing the risk of progressive infection due to incompetent immune system with the danger of inflammatory pneumonitis peri-immune reconstitution post-HSCT, she underwent a maternal (with a recent history of Covid-19 infection) haploidentical haematopoietic stem cell transplant. The patient received Regdanvimab® (post stem cell infusion) and Remdesivir (pre and post stem cell infusion). We noted a gradual increase in the Ct (cycle threshold) values, implying reduction in viral RNA with concomitant expansion in the CD3 lymphocyte subset and clinical/radiological improvement. Conclusions Combination of adoptive transfer of maternal CD45RO+ memory add-back T-lymphocytes after haploidentical HSCT, use of Regdanvimab® (SARS-CoV-2 neutralising monoclonal antibody) and Remdesivir may have led to the successful outcome in our patient with severe immunodeficiency, undergoing HSCT. Our case highlights the role of novel antiviral strategies (monoclonal antibodies and CD45RO+ memory T-lymphocytes) in contributing to viral clearance in a challenging clinical scenario.

Conjunctival epithelial cells resist productive SARS-CoV-2 infection.

Conjunctival epithelial cells, which express viral-entry receptors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine type 2 (TMPRSS2), constitute the largest exposed epithelium of the ocular surface tissue and may represent a relevant viral-entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of basal, suprabasal, and superficial epithelial cells, and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single-cell RNA sequencing (RNA-seq), with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome expression, a productive infection did not ensue. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust autocrine and paracrine NF-κB activity, without activation of antiviral interferon signalling. Collectively, these data enrich our understanding of SARS-CoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies and conjunctival transplantation.

Life-threatening viral disease in a novel form of autosomal recessive IFNAR2 deficiency in the Arctic.

Type I interferons (IFN-I) play a critical role in human antiviral immunity, as demonstrated by the exceptionally rare deleterious variants of IFNAR1 or IFNAR2. We investigated five children from Greenland, Canada, and Alaska presenting with viral diseases, including life-threatening COVID-19 or influenza, in addition to meningoencephalitis and/or hemophagocytic lymphohistiocytosis following live-attenuated viral vaccination. The affected individuals bore the same homozygous IFNAR2 c.157T>C, p.Ser53Pro missense variant. Although absent from reference databases, p.Ser53Pro occurred with a minor allele frequency of 0.034 in their Inuit ancestry. The serine to proline substitution prevented cell surface expression of IFNAR2 protein, small amounts of which persisted intracellularly in an aberrantly glycosylated state. Cells exclusively expressing the p.Ser53Pro variant lacked responses to recombinant IFN-I and displayed heightened vulnerability to multiple viruses in vitro-a phenotype rescued by wild-type IFNAR2 complementation. This novel form of autosomal recessive IFNAR2 deficiency reinforces the essential role of IFN-I in viral immunity. Further studies are warranted to assess the need for population screening.

Case Report: Severe Acute Pulmonary COVID-19 in a Teenager Post Autologous Hematopoietic Stem Cell Transplant.

Pulmonary severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children is generally described as mild, and SARS-CoV-2 infection in immunocompromised children are observed as generally mild as well. A small proportion of pediatric patients will become critically ill due to (cardio)respiratory failure and require intensive care treatment. We report the case of a teenager with Hodgkin's lymphoma who acquired SARS-CoV-2 (detected by PCR) on the day of her autologous stem cell transplant and developed acute respiratory distress syndrome, successfully treated with a combination of antivirals, immunomodulation with steroids and biologicals, and ECMO.

Delayed induction of type I and III interferons mediates nasal epithelial cell permissiveness to SARS-CoV-2.

The nasal epithelium is a plausible entry point for SARS-CoV-2, a site of pathogenesis and transmission, and may initiate the host response to SARS-CoV-2. Antiviral interferon (IFN) responses are critical to outcome of SARS-CoV-2. Yet little is known about the interaction between SARS-CoV-2 and innate immunity in this tissue. Here we apply single-cell RNA sequencing and proteomics to a primary cell model of human nasal epithelium differentiated at air-liquid interface. SARS-CoV-2 demonstrates widespread tropism for nasal epithelial cell types. The host response is dominated by type I and III IFNs and interferon-stimulated gene products. This response is notably delayed in onset relative to viral gene expression and compared to other respiratory viruses. Nevertheless, once established, the paracrine IFN response begins to impact on SARS-CoV-2 replication. When provided prior to infection, recombinant IFNß or IFNλ1 induces an efficient antiviral state that potently restricts SARS-CoV-2 viral replication, preserving epithelial barrier integrity. These data imply that the IFN-I/III response to SARS-CoV-2 initiates in the nasal airway and suggest nasal delivery of recombinant IFNs to be a potential chemoprophylactic strategy.

Human Disease Phenotypes Associated with Loss and Gain of Function Mutations in STAT2: Viral Susceptibility and Type I Interferonopathy.

STAT2 is distinguished from other STAT family members by its exclusive involvement in type I and III interferon (IFN-I/III) signaling pathways, and its unique behavior as both positive and negative regulator of IFN-I signaling. The clinical relevance of these opposing STAT2 functions is exemplified by monogenic diseases of STAT2. Autosomal recessive STAT2 deficiency results in heightened susceptibility to severe and/or recurrent viral disease, whereas homozygous missense substitution of the STAT2-R148 residue is associated with severe type I interferonopathy due to loss of STAT2 negative regulation. Here we review the clinical presentation, pathogenesis, and management of these disorders of STAT2.

The Impact of COVID-19 Pandemic on Adult and Pediatric Allergy & Immunology Services in the UK National Health Service.

BACKGROUND: The coronavirus disease 2019 pandemic imposed multiple restrictions on health care services. OBJECTIVE: To investigate the impact of the pandemic on Allergy & Immunology (A&I) services in the United Kingdom. METHODS: A national survey of all A&I services registered with the Royal College of Physicians and/or the British Society for Allergy and Clinical Immunology was carried out. The survey covered staffing, facilities, personal protective equipment, appointments & patient review, investigations, treatments, and research activity. Weeks commencing February 3, 2020 (pre-coronavirus disease), April 6, 2020, and May 8, 2020, were used as reference points for the data set. RESULTS: A total of 99 services participated. There was a reduction in nursing, medical, administrative, and allied health professional staff during the pandemic; 86% and 92% of A&I services continued to accept nonurgent and urgent referrals, respectively, during the pandemic. There were changes in immunoglobulin dose and infusion regimen in 67% and 14% of adult and pediatric services, respectively; 30% discontinued immunoglobulin replacement in some patients. There was a significant (all variables, P ≤ .0001) reduction in the following: face-to-face consultations (increase in telephone consultations), initiation of venom immunotherapy, sublingual and subcutaneous injection immunotherapy, anesthetic allergy testing, and hospital procedures (food challenges, immunoglobulin and omalizumab administration); and a significant increase (P ≤ .0001) in home therapy for immunoglobulin and omalizumab. Adverse clinical outcomes were reported, but none were serious. CONCLUSIONS: The pandemic had a significant impact on A&I services, leading to multiple unplanned pragmatic amendments in service delivery. There is an urgent need for prospective audits and strategic planning in the medium and long-term to achieve equitable, safe, and standardized health care.