SARS-Cov2 acute and post-active infection in the context of autoimmune and chronic inflammatory diseases.

The clinical and immunological spectrum of acute and post-active COVID-19 syndrome overlaps with criteria used to characterize autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Indeed, following SARS-Cov2 infection, the innate immune response is altered with an initial delayed production of interferon type I (IFN-I), while the NF-kappa B and inflammasome pathways are activated. In lung and digestive tissues, an alternative and extrafollicular immune response against SARS-Cov2 takes place with, consequently, an altered humoral and memory T cell response leading to breakdown of tolerance with the emergence of autoantibodies. However, the risk of developing severe COVID-19 among SLE and RA patients did not exceed the general population except in those having pre-existing neutralizing autoantibodies against IFN-I. Treatment discontinuation rather than COVID-19 infection or vaccination increases the risk of developing flares. Last but not least, a limited number of case reports of individuals having developed SLE or RA following COVID-19 infection/vaccination have been reported. Altogether, the SARS-Cov2 pandemic represents an unique opportunity to investigate the dangerous interplay between the immune response against infectious agents and autoimmunity, and to better understand the triggering role of infection as a risk factor in autoimmune and chronic inflammatory disease development.

SOCS1 Haploinsufficiency Presenting As Incidental Refractory Thrombocytopenia in a Pediatric Patient with Inflammatory Symptoms and History of Sars Cov-2 Infection

BACKGROUND: Immune thrombocytopenia purpura (ITP) has a complex pathogenesis and may be a primary diagnosis or secondary to an underlying condition 1. Evaluation for underlying diagnoses in patients presenting with atypical features of classic ITP is key, as this can impact treatment decisions, therapy response, and prognosis. Genetic variants that predispose patients to ITP are especially important to investigate as patients may be at risk for additional autoimmune phenomenon or malignancy. The SARS CoV-2 pandemic has added further complexity as reports suggest the infection can lead to autoimmunity in those with genetic predispositions 2,3. Loss of the suppressor of cytokine signaling 1 (SOCS1) function has been described to manifest with autoinflammatory syndrome, with or without immunodeficiency 4,5. Reports of autoimmunity developing in patients with SOCS1 haploinsufficiency after SARS CoV-2 infection are documented, including multi-system inflammatory syndrome (MIS-C) 2. A proposed mechanism of this virus-triggered autoimmunity includes a transient innate and adaptive immunodeficiency 3. This raises the question whether patients harboring genetic variants with risk of autoimmunity are placed at an even higher risk for ITP in the wake of SARS-CoV2 infection. CASE PRESENTATION: We present a 6-year-old female with isolated thrombocytopenia of 4,000/uL identified during evaluation for severe arthralgias unresponsive to corticosteroid treatment (maximum dose 1mg/kg/day) over a 6-month period. Laboratory results at presentation were consistent with ITP, including presence of platelet autoantibodies. Evaluation revealed hypocellularity for age (~50%) on bone marrow evaluation as well as elevated IgE (2080 kU/L), with IgA, IgM, and IgG levels within reference range. She had a remote history of SARS CoV-2-like illness and SARS CoV-2 antibodies were found present in serologic assay, without a history of vaccination. Genetic testing, including chromosomal microarray from peripheral blood and marrow, was included in the diagnostic workup given concern for a history of developmental delays with macrocephaly and necessity to rule-out malignancy with the patient noted to have a 5 mega-base deletion at 16p13.2p13.11, which includes the SOCS1 gene. Comprehensive next generation sequencing for additional immune dysregulation/primary immunodeficiency associated variants was unremarkable. Functional studies of surface expression of interferon-inducible genes (CD169 (SIGLEC-1)) and STAT1 phosphorylation via analysis of CD14+ monocytes revealed excess interferon signaling previously described in patients with SOCS1 haploinsufficiency (Figure 1). Measurements of B-cell-activating factor were also found to be extremely elevated at 6432 pg/mL. The patient's ITP course was complicated by hematuria, melena and refractory platelet response to first line therapy consisting of intravenous immunoglobulin 1 g/kg x2 doses and 2 mg/kg/day prednisolone. She required escalation to high dose methylprednisolone (30mg/kg), rituximab 375 mg/m 2/weekly x4 doses, and concurrent romiplostim (2 doses) for control of thrombocytopenia and bleeding manifestations. Her rheumatologic symptoms subsided with initiation of corticosteroids, and she has subsequently completed a prolonged corticosteroid taper. She currently has a normal platelet count with non-steroidal anti-inflammatory therapy utilized for arthralgia management with plan to transition to JAK inhibition for maintenance therapy. CONCLUSION: This case highlights the potential impact of investigating for susceptibility genes for ITP with consideration for broader testing including targeted next generation sequencing panels or microarray analysis in patients with atypical ITP presentations or response to therapy, as knowledge of this patient's underlying genetics led to earlier treatment and use of alternative agents. Additionally, the case adds the novel finding of bone marrow hypocellularity to the clinical phenotype of SOCS1 haploinsufficiency, as this has not yet been reported and contributes to the literature on the relationship of autoimmunity and SARS CoV-2 infections in patients with predisposing genetic variants. [Formula presented] Disclosures: Walkovich: Horizon Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees;Pharming: Honoraria, Membership on an entity's Board of Directors or advisory committees;Swedish Orphan Biovitrum AB (Sobi): Consultancy, Honoraria;X4 Pharmaceuticals: Other: Local PI for clinical trial involving mavorixafor and patients with neutropenia.

Single Cell Transcriptomic Re-analysis of Immune Cells in Bronchoalveolar Lavage Fluids Reveals the Correlation of B Cell Characteristics and Disease Severity of Patients with SARS-CoV-2 Infection.

The coronavirus disease 2019 (COVID-19) pandemic (severe acute respiratory syndrome coronavirus 2) is a global infectious disease with rapid spread. Some patients have severe symptoms and clinical signs caused by an excessive inflammatory response, which increases the risk of mortality. In this study, we reanalyzed scRNA-seq data of cells from bronchoalveolar lavage fluids of patients with COVID-19 with mild and severe symptoms, focusing on Ab-producing cells. In patients with severe disease, B cells seemed to be more activated and expressed more immunoglobulin genes compared with cells from patients with mild disease, and macrophages expressed higher levels of the TNF superfamily member B-cell activating factor but not of APRIL (a proliferation-inducing ligand). In addition, macrophages from patients with severe disease had increased pro-inflammatory features and pathways associated with Fc receptor-mediated signaling, compared with patients with mild disease. CCR2-positive plasma cells accumulated in patients with severe disease, probably because of increased CCL2 expression on macrophages from patients with severe disease. Together, these results support the hypothesis that different characteristics of B cells might be associated with the severity of COVID-19 infection.