Prevalence of autoantibody responses in acute coronavirus disease 2019 (COVID-19)

Autoimmune response to COVID-19 characterised by eosinophilia, NETosis and EETosis

A previously healthy man in his 50s was admitted with severe COVID-19 pneumonia requiring extracorporeal membrane oxygenation (ECMO) support. He was found to have persistent eosinophilia, with a peak level of 7.5×109/L. He had received multiple courses of steroids, including dexamethasone and methylprednisolone, with no improvement. On day 47, hydrocortisone was initiated for the treatment of septic shock. This resulted in the normalisation of the eosinophil count, which correlated with radiographic and clinical improvement. The patient was transitioned off ECMO and eventually weaned off mechanical ventilation. Studies conducted using the patient's serum identified circulating autoantibodies, which induced neutrophil extracellular traps (NETosis) and eosinophil extracellular traps (EETosis). A varying response of the eosinophils to different corticosteroids was observed in vivo that corresponded with the ex vivo experiments. This case highlights an unrecognised phenomenon of differential response to corticosteroids in severe COVID-19. Furthermore, this is the first reported case of EETosis in COVID-19.

Autoantibodies targeting angiotensin-converting enzyme 2 are prevalent and not induced by SARS-CoV-2 infection

Clinical outcomes resulting from SARS-CoV-2 infection vary widely, ranging from asymptomatic cases to the development of mild to severe respiratory illness, and in some instances, chronic lingering disease and mortality. The underlying biological mechanisms driving this wide spectrum of pathogenicity among certain individuals and demographics remain elusive. Autoantibodies have emerged as potential contributors to the severity of COVID-19. Although preliminary reports have suggested the induction of antibodies targeting Angiotensin-Converting Enzyme II (ACE2) post-infection, this assertion lacks confirmation in large-scale studies. In this study, our objective is to comprehensively characterize and quantify the prevalence and expression levels of autoantibodies directed against ACE2 in a sizable cohort (n = 464). Our findings reveal that ACE2-reactive IgM antibodies are the most prevalent, with an overall seroprevalence of 18.8%, followed by IgG at 10.3% and IgA at 6.3%. Longitudinal analysis of individuals with multiple blood draws showed stable ACE2 IgG and IgA levels over time. Upon stratifying individuals based on molecular testing for SARS-CoV-2 or serological evidence of past infection, no significant differences were observed between groups. Functional assessment of ACE2 autoantibodies demonstrated that they are non-neutralizing and failed to inhibit spike-ACE2 interaction or affect the enzymatic activity of ACE2. Our results highlight that ACE2 autoantibodies are prevalent in the general population and were not induced by SARS-CoV-2 infection in our cohort. Notably, we found no substantiated evidence supporting a direct role for ACE2 autoantibodies in SARS-CoV-2 pathogenesis.

Autoantibodies in COVID-19: implications for disease severity and clinical outcomes

Few pathogens have historically been subjected to as intense scientific and clinical scrutiny as SARS-CoV-2. The genetic, immunological, and environmental factors influencing disease severity and post-infection clinical outcomes, known as correlates of immunity, remain largely undefined. Clinical outcomes of SARS-CoV-2 infection vary widely, ranging from asymptomatic cases to those with life-threatening COVID-19 symptoms. While most infected individuals return to their former health and fitness within a few weeks, some develop debilitating chronic symptoms, referred to as long-COVID. Autoimmune responses have been proposed as one of the factors influencing long-COVID and the severity of SARS-CoV-2 infection. The association between viral infections and autoimmune pathologies is not new. Viruses such as Epstein-Barr virus and cytomegalovirus, among others, have been shown to induce the production of autoantibodies and the onset of autoimmune conditions. Given the extensive literature on SARS-CoV-2, here we review current evidence on SARS-CoV-2-induced autoimmune pathologies, with a focus on autoantibodies. We closely examine mechanisms driving autoantibody production, particularly their connection with disease severity and long-COVID.

Brain Fog: a Narrative Review of the Most Common Mysterious Cognitive Disorder in COVID-19

It has been more than three years since COVID-19 impacted the lives of millions of people, many of whom suffer from long-term effects known as long-haulers. Notwithstanding multiorgan complaints in long-haulers, signs and symptoms associated with cognitive characteristics commonly known as "brain fog" occur in COVID patients over 50, women, obesity, and asthma at excessive. Brain fog is a set of symptoms that include cognitive impairment, inability to concentrate and multitask, and short-term and long-term memory loss. Of course, brain fog contributes to high levels of anxiety and stress, necessitating an empathetic response to this group of COVID patients. Although the etiology of brain fog in COVID-19 is currently unknown, regarding the mechanisms of pathogenesis, the following hypotheses exist: activation of astrocytes and microglia to release pro-inflammatory cytokines, aggregation of tau protein, and COVID-19 entry in the brain can trigger an autoimmune reaction. There are currently no specific tests to detect brain fog or any specific cognitive rehabilitation methods. However, a healthy lifestyle can help reduce symptoms to some extent, and symptom-based clinical management is also well suited to minimize brain fog side effects in COVID-19 patients. Therefore, this review discusses mechanisms of SARS-CoV-2 pathogenesis that may contribute to brain fog, as well as some approaches to providing therapies that may help COVID-19 patients avoid annoying brain fog symptoms.

Ebola Virus-Specific Neutralizing Antibody Persists at High Levels in Survivors 2 Years After Resolution of Disease in a Sierra Leonean Cohort

Ebola virus (EBOV) infection results in Ebola virus disease (EVD), an often severe disease with a nonspecific presentation. Since its recognition, periodic outbreaks of EVD continue to occur in sub-Saharan Africa. The 2013-2016 West African EVD outbreak was the largest recorded, resulting in a substantial cohort of EVD survivors with persistent health complaints and variable immune responses. In this study, we characterize humoral immune responses in EVD survivors and their contacts in Eastern Sierra Leone. We found high levels of EBOV IgG in EVD survivors and lower yet substantial antibody levels in household contacts, suggesting subclinical transmission. Neutralizing antibody function was prevalent but variable in EVD survivors, raising questions about the durability of immune responses from natural infection with EBOV. Additionally, we found that certain discrete symptoms-ophthalmologic and auditory-are associated with EBOV IgG seropositivity, while an array of symptoms are associated with the presence of neutralizing antibody.

Advance in the mechanism and clinical research of myalgia in long COVID

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve, mortality rates of coronavirus disease 2019 (COVID-19) have significantly decreased. However, a variable proportion of patients exhibit persistent prolonged symptoms of COVID-19 infection (long COVID). This virus primarily attacks respiratory system, but numerous individuals complain persistent skeletal muscle pain or worsening pre-existing muscle pain post COVID-19, which severely affects the quality of life and recovery. Currently, there is limited research on the skeletal muscle pain in long COVID. In this brief review, we review potential pathological mechanisms of skeletal muscle pain in long COVID, and summarize the various auxiliary examinations and treatments for skeletal muscle pain in long COVID. We consider abnormal activation of inflammatory response, myopathy, and neurological damages as pivotal pathological mechanisms of skeletal muscle pain in long COVID. A comprehensive examination is significantly important in order to work out effective treatment plans and relieve skeletal muscle pain. So far, rehabilitation interventions for myalgia in long COVID contain but are not limited to drug, nutraceutical therapy, gut microbiome-targeted therapy, interventional therapy and strength training. Our study provides a potential mechanism reference for clinical researches, highlighting the importance of comprehensive approach and management of skeletal muscle pain in long COVID. The relief of skeletal muscle pain will accelerate rehabilitation process, improve activities of daily living and enhance the quality of life, promoting individuals return to society with profound significance.

Interplay between Comorbidities and Long COVID: Challenges and Multidisciplinary Approaches

Long COVID, a name often given to the persistent symptoms following acute SARS-CoV-2 infection, poses a multifaceted challenge for health. This review explores the intrinsic relationship between comorbidities and autoimmune responses in shaping the trajectory of long COVID. Autoantibodies have emerged as significant players in COVID-19 pathophysiology, with implications for disease severity and progression. Studies show immune dysregulation persisting months after infection, marked by activated innate immune cells and high cytokine levels. The presence of autoantibodies against various autoantigens suggests their potential as comorbid factors in long COVID. Additionally, the formation of immune complexes may lead to severe disease progression, highlighting the urgency for early detection and intervention. Furthermore, long COVID is highly linked to cardiovascular complications and neurological symptoms, posing challenges in diagnosis and management. Multidisciplinary approaches, including vaccination, tailored rehabilitation, and pharmacological interventions, are used for mitigating long COVID's burden. However, numerous challenges persist, from evolving diagnostic criteria to addressing the psychosocial impact and predicting disease outcomes. Leveraging AI-based applications holds promise in enhancing patient management and improving our understanding of long COVID. As research continues to unfold, unravelling the complexities of long COVID remains paramount for effective intervention and patient care.

The Onset of Antinuclear Antibodies (ANAs) as a Potential Risk Factor for Mortality and Morbidity in COVID-19 Patients: A Single-Center Retrospective Study

The immune system's amplified response to SARS-CoV-2 may lead to the production of autoantibodies, but their specific impact on disease severity and outcome remains unclear. This study aims to assess if hospitalized COVID-19 patients face a worse prognosis based on ANA presence, even without autoimmune diseases. We performed a retrospective, single-center, observational cohort study, enrolling 638 COVID-19 patients hospitalized from April 2020 to March 2021 at Hospital "Policlinico Riuniti" of Foggia (Italy). COVID-19 patients with a positive ANA test exhibited a significantly lower 30-day survival rate (64.4% vs. 83.0%) and a higher likelihood of severe respiratory complications during hospitalization than those with negative ANA screening (35.4% vs. 17.0%) (p < 0.001). The association between poor prognosis and ANA status was identified by calculating the HALP score (Hemoglobin-Albumin-Lymphocyte-Platelet), which was lower in COVID-19 patients with a positive ANA test compared to ANA-negative patients (108.1 ± 7.4 vs. 218.6 ± 11.2 AU; p < 0.011). In detail, COVID-19 patients with a low HALP showed a lower 30-day survival rate (99.1% vs. 83.6% vs. 55.2% for high, medium, and low HALP, respectively; p < 0.001) and a higher incidence of adverse respiratory events compared to those with high and medium HALP (13.1% vs. 35.2% vs. 64.6% for high, medium, and low HALP, respectively; p < 0.001). In summary, ANA positivity in COVID-19 patients appears to be linked to a more aggressive disease phenotype with a reduced survival rate. Furthermore, we propose that the HALP score could serve as a valuable parameter to assess prognosis for COVID-19 patients.

Exploring the Pathophysiology of Long COVID: The Central Role of Low-Grade Inflammation and Multisystem Involvement

Long COVID (LC), also referred to as Post COVID-19 Condition, Post-Acute Sequelae of SARS-CoV-2 Infection (PASC), and other terms, represents a complex multisystem disease persisting after the acute phase of COVID-19. Characterized by a myriad of symptoms across different organ systems, LC presents significant diagnostic and management challenges. Central to the disorder is the role of low-grade inflammation, a non-classical inflammatory response that contributes to the chronicity and diversity of symptoms observed. This review explores the pathophysiological underpinnings of LC, emphasizing the importance of low-grade inflammation as a core component. By delineating the pathogenetic relationships and clinical manifestations of LC, this article highlights the necessity for an integrated approach that employs both personalized medicine and standardized protocols aimed at mitigating long-term consequences. The insights gained not only enhance our understanding of LC but also inform the development of therapeutic strategies that could be applicable to other chronic conditions with similar pathophysiological features.

Antiphospholipid antibody-related hepatic vasculitis in a juvenile after non-severe COVID-19: a case report and literature review

Antiphospholipid antibodies (aPL) are both laboratory evidence and causative factors for a broad spectrum of clinical manifestations of antiphospholipid syndrome (APS), with thrombotic and obstetric events being the most prevalent. Despite the aPL-triggered vasculopathy nature of APS, vasculitic-like manifestations rarely exist in APS and mainly appear associated with other concurrent connective tissue diseases like systemic lupus erythematous. Several studies have characterized pulmonary capillaritis related to pathogenic aPL, suggesting vasculitis as a potential associated non-thrombotic manifestation. Here, we describe a 15-year-old girl who develops hepatic infarction in the presence of highly positive aPL, temporally related to prior non-severe COVID-19 infection. aPL-related hepatic vasculitis, which has not been reported before, contributes to liver ischemic necrosis. Immunosuppression therapy brings about favorable outcomes. Our case together with retrieved literature provides supportive evidence for aPL-related vasculitis, extending the spectrum of vascular changes raised by pathogenic aPL. Differentiation between thrombotic and vasculitic forms of vascular lesions is essential for appropriate therapeutic decision to include additional immunosuppression therapy. We also perform a systematic review to characterize the prevalence and clinical features of new-onset APS and APS relapses after COVID-19 for the first time, indicating the pathogenicity of aPL in a subset of COVID-19 patients.

Self-DNA driven inflammation in COVID-19 and after mRNA-based vaccination: lessons for non-COVID-19 pathologies

The coronavirus disease 2019 (COVID-19) pandemic triggered an unprecedented concentration of economic and research efforts to generate knowledge at unequalled speed on deregulated interferon type I signalling and nuclear factor kappa light chain enhancer in B-cells (NF-κB)-driven interleukin (IL)-1β, IL-6, IL-18 secretion causing cytokine storms. The translation of the knowledge on how the resulting systemic inflammation can lead to life-threatening complications into novel treatments and vaccine technologies is underway. Nevertheless, previously existing knowledge on the role of cytoplasmatic or circulating self-DNA as a pro-inflammatory damage-associated molecular pattern (DAMP) was largely ignored. Pathologies reported 'de novo' for patients infected with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 to be outcomes of self-DNA-driven inflammation in fact had been linked earlier to self-DNA in different contexts, e.g., the infection with Human Immunodeficiency Virus (HIV)-1, sterile inflammation, and autoimmune diseases. I highlight particularly how synergies with other DAMPs can render immunogenic properties to normally non-immunogenic extracellular self-DNA, and I discuss the shared features of the gp41 unit of the HIV-1 envelope protein and the SARS-CoV 2 Spike protein that enable HIV-1 and SARS-CoV-2 to interact with cell or nuclear membranes, trigger syncytia formation, inflict damage to their host's DNA, and trigger inflammation - likely for their own benefit. These similarities motivate speculations that similar mechanisms to those driven by gp41 can explain how inflammatory self-DNA contributes to some of most frequent adverse events after vaccination with the BNT162b2 mRNA (Pfizer/BioNTech) or the mRNA-1273 (Moderna) vaccine, i.e., myocarditis, herpes zoster, rheumatoid arthritis, autoimmune nephritis or hepatitis, new-onset systemic lupus erythematosus, and flare-ups of psoriasis or lupus. The hope is to motivate a wider application of the lessons learned from the experiences with COVID-19 and the new mRNA vaccines to combat future non-COVID-19 diseases.

Evidence of a Sjögren's disease-like phenotype following COVID-19 in mice and humans

Sjögren's Disease (SjD) is a systemic autoimmune disease characterized by lymphocytic inflammation of the lacrimal and salivary glands (SG), dry eyes and mouth, and systemic symptoms. SARS-CoV-2 may trigger the development or progression of autoimmune diseases. To test this, we used a mouse model of SARS-CoV-2 infection and convalescent patients' blood and SG in order to understand the development of SjD-like autoimmunity after infection. First, SARS-CoV-2-infected human angiotensin-converting enzyme 2 (ACE2) transgenic mice exhibited decreased salivation, elevated antinuclear antibodies (ANA), and lymphocytic infiltration in the lacrimal and SG. The sera from patients with COVID-19 sera showed increased ANA (i.e., anti-SSA [Sjögren's-syndrome-related antigen A]/anti-Ro52 and anti-SSB [SS-antigen B]/anti-La). Male patients showed elevated anti-SSA compared with female patients, and female patients exhibited diverse ANA patterns. SG biopsies from convalescent COVID-19 patients were microscopically similar to SjD SG with focal lymphocytic infiltrates in 4 of 6 patients and 2 of 6 patients exhibiting focus scores of at least 2. Lastly, monoclonal antibodies produced in recovered patients blocked ACE2/spike interaction and cross-reacted with nuclear antigens. Our study shows a direct association between SARS-CoV-2 and SjD. Hallmark features of SjD-affected SGs were histologically indistinguishable from convalescent COVID-19 patients. The results implicate that SARS-CoV-2 could be an environmental trigger for SjD.

Mild-to-moderate COVID-19 does not predispose to the development of autoimmune rheumatic diseases or autoimmune-based thrombosis

An infection with severe acute respiratory syndrome coronavirus (SARS-CoV-2) may have a significant impact on the human immune system. Interactions between the virus and defence mechanisms may promote the development of autoimmune processes which manifest as antinuclear antibody (ANA) synthesis. Since many different viruses are suspected to take part in the pathogenesis of different systemic autoimmune rheumatic diseases (SARDs), we examined whether coronavirus disease 2019 convalescents who suffer from mild to moderate disease have a higher risk of developing ANA and anti-β2-glicoprotein I IgG antibodies (β2 GPI). In a retrospective study, we examined 294 adults among volunteer blood donors divided into convalescents (N = 215) and healthy controls (N = 79). For ANA detection, we used line-blotting, a type of indirect immunofluorescence assay (IF), to determine antigenic specificity and ELISA for β2 GPI. We found a lower incidence of ANA in convalescents than in healthy controls, with the majority of these antibodies directed to antigens with no known clinical significance. Additionally, no participants were positive for β2 GPI in either group. Our results show that COVID-19 with mild to moderate symptoms in the generally healthy population does not induce the development of ANA or anti-β2 GPI antibodies for at least 6 months following the disease.

Impaired immune response against SARS-CoV-2 infection is the major factor indirectly altering reproductive function in COVID-19 patients: a narrative review

Coronavirus disease 2019 (COVID-19) is an infectious disease affecting multiple systems and organs, including the reproductive system. SARS-CoV-2, the virus that causes COVID-19, can damage reproductive organs through direct (angiotensin converting enzyme-2, ACE-2) and indirect mechanisms. The immune system plays an essential role in the homeostasis and function of the male and female reproductive systems. Therefore, an altered immune response related to infectious and inflammatory diseases can affect reproductive function and fertility in both males and females. This narrative review discussed the dysregulation of innate and adaptive systems induced by SARS-CoV-2 infection. We reviewed the evidence showing that this altered immune response in COVID-19 patients is the major indirect mechanism leading to adverse reproduction outcomes in these patients. We summarized studies reporting the long-term effect of SARS-CoV-2 infection on women's reproductive function and proposed the chronic inflammation and chronic autoimmunity characterizing long COVID as potential underlying mechanisms. Further studies are needed to clarify the role of autoimmunity and chronic inflammation (long COVID) in altered female reproduction function in COVID-19.

The spectrum of COVID-19-associated chorioretinal vasculopathy

Purpose

Although conjunctivitis represents the most common ocular manifestation of COVID-19 infection, sight-threatening retinal involvement has been reported. Herein, we report and characterize with multimodal retinal imaging 5 cases of acute vision loss secondary to presumed chorioretinal vasculopathy temporally associated with COVID-19 infection with varying severity, visual morbidity, and treatment response, and review the available literature on the association between COVID-19 infection and retinal microvascular changes.

Design

Observational case series and literature review.

Methods

Multicenter case series of 5 patients who presented to academic centers and private offices with acute vision loss temporally associated with COVID-19 infection. A review of the literature was conducted using online databases.

Results

10 eyes of 5 patients, 3 men and 2 women, with a mean age of 30.8 years (median 33, range 16-44) were described. All patients had a recently preceding episode of COVID-19, with symptomatology ranging from mild infection to life-threatening encephalopathy. Treatment for their retinal disease included topical, oral, intravitreal, and intravenous steroids, steroid-sparing immunosuppression, retinal photocoagulation, antivirals, and antiplatelet and anticoagulant agents. Treatment response and visual recovery ranged from complete recovery of baseline acuity to permanent vision loss and need for chronic immunosuppression.

Conclusions and Importance

Clinicians should be mindful of the potential for vision-threatening retinal involvement after COVID-19 infection. If found, treatment with both anti-inflammatory therapy and anticoagulation should be considered, in addition to close monitoring, as some patients with this spectrum of disease may require chronic immune suppression and/or anti-VEGF therapy.

The unfolded protein response components IRE1α and XBP1 promote human coronavirus infection

The cellular processes that support human coronavirus replication and contribute to the pathogenesis of severe disease remain incompletely understood. Many viruses, including coronaviruses, cause endoplasmic reticulum (ER) stress during infection. IRE1α is a component of the cellular response to ER stress that initiates non-conventional splicing of XBP1 mRNA. Spliced XBP1 encodes a transcription factor that induces the expression of ER-related targets. Activation of the IRE1α-XBP1 pathway occurs in association with risk factors for severe human coronavirus infection. In this study, we found that the human coronaviruses HCoV-OC43 (human coronavirus OC43) and SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) both robustly activate the IRE1α-XBP1 branch of the unfolded protein response in cultured cells. Using IRE1α nuclease inhibitors and genetic knockdown of IRE1α and XBP1, we found that these host factors are required for optimal replication of both viruses. Our data suggest that IRE1α supports infection downstream of initial viral attachment and entry. In addition, we found that ER stress-inducing conditions are sufficient to enhance human coronavirus replication. Furthermore, we found markedly increased XBP1 in circulation in human patients with severe coronavirus disease 2019 (COVID-19). Together, these results demonstrate the importance of IRE1α and XBP1 for human coronavirus infection. IMPORTANCE There is a critical need to understand the cellular processes co-opted during human coronavirus replication, with an emphasis on identifying mechanisms underlying severe disease and potential therapeutic targets. Here, we demonstrate that the host proteins IRE1α and XBP1 are required for robust infection by the human coronaviruses, SARS-CoV-2 and HCoV-OC43. IRE1α and XBP1 participate in the cellular response to ER stress and are activated during conditions that predispose to severe COVID-19. We found enhanced viral replication with exogenous IRE1α activation, and evidence that this pathway is activated in humans during severe COVID-19. Together, these results demonstrate the importance of IRE1α and XBP1 for human coronavirus infection.

A systematic review of the incidence, management and prognosis of new-onset autoimmune connective tissue diseases after COVID-19

A literature review on new-onset autoimmune connective tissue diseases (ACTDs) following COVID-19 is lacking. We evaluated potential associations between COVID-19 and the development of new-onset ACTDs. The "population" was adults with disease terms for ACTDs, including systemic lupus erythematosus (SLE), Sjogren's syndrome, systemic sclerosis (SSc), idiopathic inflammatory myositis (IIM), anti-synthetase syndrome, mixed CTD and undifferentiated CTD, and "intervention" as COVID-19 and related terms. Databases were searched for English-language articles published until September 2022. We identified 2236 articles with 28 ultimately included. Of the 28 included patients, 64.3% were female, with a mean age was 51.1 years. The USA reported the most cases (9/28). ACTD diagnoses comprised: 11 (39.3%) IIM (including four dermatomyositis); 7 (25%) SLE; four (14.3%) anti-synthetase syndrome; four (14.3%) SSc; two (7.1%) other ACTD (one lupus/MCTD overlap). Of eight, four (14.3%) patients (including that with lupus/MCTD) had lupus nephritis. The average time from COVID-19 to ACTD diagnosis was 23.7 days. A third of patients were admitted to critical care, one for treatment of haemophagocytic lymphohistiocytosis in SLE (14 sessions of plasmapheresis, rituximab and intravenous corticosteroids) and nine due to COVID-19. 80% of patients went into remission of ACTD following treatment, while three (10%) patients died-one due to macrophage activation syndrome with anti-synthetase syndrome and two from unreported causes. Our results suggest a potential association between COVID-19 and new-onset ACTDs, notably in young females, reflecting more comprehensive CTD epidemiology. The most common diagnosis in our cohort was IIM. The aetiology and mechanisms by which ACTDs emerge following COVID-19 remain unknown and require further research.

Antiphospholipid Antibodies Occurrence in Acute SARS-CoV-2 Infection without Overt Thrombosis

We sought to determine the prevalence of antiphospholipid antibodies (aPLs) and their correlation with COVID-19 severity (in terms of clinical and laboratory parameters) in patients without thrombotic events during the early phase of infection. This was a cross-sectional study with the inclusion of hospitalized COVID-19 patients from a single department during the COVID-19 pandemic (April 2020-May 2021). Previous known immune disease or thrombophilia along with long-term anticoagulation and patients with overt arterial or venous thrombosis during SARS-CoV-2 infection were excluded. In all cases, data on four criteria for aPL were collected, namely lupus anticoagulant (LA), IgM and IgG anticardiolipin antibodies (aCL), as well as IgG anti-β2 glycoprotein I antibodies (aβ2GPI). One hundred and seventy-nine COVID-19 patients were included, with a mean age of 59.6 (14.5) years and a sex ratio of 0.8 male: female. LA was positive in 41.9%, while it was strongly positive in 4.5%; aCL IgM was found in 9.5%, aCL IgG in 4.5%, and aβ2GPI IgG in 1.7% of the sera tested. Clinical correlation: LA was more frequently expressed in severe COVID-19 cases than in moderate or mild cases (p = 0.027). Laboratory correlation: In univariate analysis, LA levels were correlated with D-dimer (p = 0.016), aPTT (p = 0.001), ferritin (p = 0.012), C-reactive protein (CRP) (p = 0.027), lymphocyte (p = 0.040), and platelet (p < 0.001) counts. However, in the multivariate analysis, only the CRP levels correlated with LA positivity: OR (95% CI) 1.008 (1.001-1.016), p = 0.042. LA was the most common aPL identified in the acute phase of COVID-19 and was correlated with infection severity in patients without overt thrombosis.

Antinuclear antibodies in individuals with COVID-19 reflect underlying disease: Identification of new autoantibodies in systemic sclerosis (CDK9) and malignancy (RNF20, RCC1, TRIP13)

A high prevalence of antinuclear antibodies (ANA) in COVID-19 has been insinuated, but the nature of the target antigens is poorly understood. We studied ANA by indirect immunofluorescence in 229 individuals with COVID-19. The target antigens of high titer ANA (≥1:320) were determined by immunoprecipitation (IP) combined with liquid-chromatography-mass spectrometry (MS). High titer ANA (≥1:320) were found in 14 (6%) of the individuals with COVID-19. Of the 14 COVID-19 cases with high titer ANA, 6 had an underlying autoimmune disease and 5 a malignancy. IP-MS revealed known target antigens associated with autoimmune disease as well as novel autoantigens, including CDK9 (in systemic sclerosis) and RNF20, RCC1 and TRIP13 (in malignancy). The novel autoantigens were confirmed by IP-Western blotting. In conclusion, in depth analysis of the targets of high titer ANA revealed novel autoantigens in systemic sclerosis and in malignant disease.

Cross-sectional analysis reveals autoantibody signatures associated with COVID-19 severity

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with increased levels of autoantibodies targeting immunological proteins such as cytokines and chemokines. Reports further indicate that COVID-19 patients may develop a broad spectrum of autoimmune diseases due to reasons not fully understood. Even so, the landscape of autoantibodies induced by SARS-CoV-2 infection remains uncharted territory. To gain more insight, we carried out a comprehensive assessment of autoantibodies known to be linked to diverse autoimmune diseases observed in COVID-19 patients in a cohort of 231 individuals, of which 161 were COVID-19 patients (72 with mild, 61 moderate, and 28 with severe disease) and 70 were healthy controls. Dysregulated IgG and IgA autoantibody signatures, characterized mainly by elevated concentrations, occurred predominantly in patients with moderate or severe COVID-19 infection. Autoantibody levels often accompanied anti-SARS-CoV-2 antibody concentrations while stratifying COVID-19 severity as indicated by random forest and principal component analyses. Furthermore, while young versus elderly COVID-19 patients showed only slight differences in autoantibody levels, elderly patients with severe disease presented higher IgG autoantibody concentrations than young individuals with severe COVID-19. This work maps the intersection of COVID-19 and autoimmunity by demonstrating the dysregulation of multiple autoantibodies triggered during SARS-CoV-2 infection. Thus, this cross-sectional study suggests that SARS-CoV-2 infection induces autoantibody signatures associated with COVID-19 severity and several autoantibodies that can be used as biomarkers of COVID-19 severity, indicating autoantibodies as potential therapeutical targets for these patients.

Lupus Anticoagulant Is Associated with Critical Cases and High Mortality in COVID-19: A Literature Review

Background

In severe COVID-19 cases, a hypercoagulable state may occur. Antiphospholipid syndrome-related auto-antibodies (APSRAs) contribute to coagulopathy, but their role in COVID- 19 remains unclear. We aimed to investigate the prevalence of positive APSRAs and their effect on clinical outcomes in confirmed COVID-19 patients.

Materials and Methods

In this cross-sectional study, severe hospitalized COVID-19 cases were enrolled. Demographic and clinical data were obtained from the day of admission. APSRAs including IgG and/or IgM anticardiolipin (aCL) and anti-β2-glycoprotein1 (anti-β2GP1) as well as lupus anticoagulant (LAC) were measured.

Results

In this study, 54 severe COVID-19 cases with positive RT-PCR and chest CT scans were recruited. Positive APSRAs were found in 7 (12.9%) patients. Positive LAC was a more prevalent marker as compared to other tests (11.1%). The prevalence of positive aCL (IgM or IgG) and anti-ß2 GPI (IgM or IgG) was 1.8% (in an elderly woman). Lower oxygen saturation was found in the positive APSRAs group as opposed to the negative APSRAs group (70.3±9 vs. 84.8±9.7%). The mortality rate in the positive APSRAs group was significantly higher relative to the negative APSRAs group (83.3% vs. 27.1%; P-value: 0.01). Likewise, the mechanical ventilation requirement in the positive group was also higher (50% vs. 27.1%, P-value: 0.28).

Conclusion

This study indicated that LAC might be associated with critical cases and high mortality of COVID-19. Nonetheless, the mortality was not related to macrothrombotic incidence.

COVID-19 and the antiphospholipid syndrome

Coronavirus disease 2019 (COVID-19) has resulted in a global pandemic. Most COVID-19 patients are asymptomatic or have flu-like symptoms. However, around 15% of the patients may have severe disease, including unilateral or bilateral pneumonia with acute respiratory distress syndrome and progressive hypoxemia that may require mechanical ventilation assistance. A systemic inflammatory response syndrome occurs in the most severe forms of COVID-19, with multiorgan involvement which can be life threatening caused by a cytokine storm. Although what best characterizes COVID-19 are the manifestations of the respiratory system, it has been shown that it also acts at the cardiovascular level, producing coagulation abnormalities, which causes thrombotic events mainly in the arteries/arterioles, microcirculation and venous system, and potentially increased mortality risk. This multiorgan vascular disease overlaps with other known microangiopathies, such as thrombotic microangiopathy or paroxysmal nocturnal hemoglobinuria, where complement overactivation plays an important role in the pathophysiology of thrombosis. Furthermore, coagulopathy secondary to COVID-19 occurs in the context of an uncontrolled inflammatory response, reminiscent of APS, especially in its catastrophic form. This review summarizes the current knowledge regarding the relationship between COVID-19 and the APS.

Evidence of a Sjögren's disease-like phenotype following COVID-19

Objectives

Sjögren's Disease (SjD) is a chronic and systemic autoimmune disease characterized by lymphocytic infiltration and the development of dry eyes and dry mouth resulting from the secretory dysfunction of the exocrine glands. SARS-CoV-2 may trigger the development or progression of autoimmune diseases, as evidenced by increased autoantibodies in patients and the presentation of cardinal symptoms of SjD. The objective of the study was to determine whether SARS-CoV-2 induces the signature clinical symptoms of SjD.

Methods

The ACE2-transgenic mice were infected with SARS-CoV-2. SJD profiling was conducted. COVID-19 patients' sera were examined for autoantibodies. Clinical evaluations of convalescent COVID-19 subjects, including minor salivary gland (MSG) biopsies, were collected. Lastly, monoclonal antibodies generated from single B cells of patients were interrogated for ACE2/spike inhibition and nuclear antigens.

Results

Mice infected with the virus showed a decreased saliva flow rate, elevated antinuclear antibodies (ANAs) with anti-SSB/La, and lymphocyte infiltration in the lacrimal and salivary glands. Sera of COVID-19 patients showed an increase in ANA, anti-SSA/Ro52, and anti-SSB/La. The male patients showed elevated levels of anti-SSA/Ro52 compared to female patients, and female patients had more diverse ANA patterns. Minor salivary gland biopsies of convalescent COVID-19 subjects showed focal lymphocytic infiltrates in four of six subjects, and 2 of 6 subjects had focus scores >2. Lastly, we found monoclonal antibodies produced in recovered patients can both block ACE2/spike interaction and recognize nuclear antigens.

Conclusion

Overall, our study shows a direct association between SARS-CoV-2 and SjD. Hallmark features of SjD salivary glands were histologically indistinguishable from convalescent COVID-19 subjects. The results potentially implicate that SARS-CoV-2 could be an environmental trigger for SjD.

Key Messages

What is already known about this subject?SAR-CoV-2 has a tropism for the salivary glands. However, whether the virus can induce clinical phenotypes of Sjögren's disease is unknown.What does this study add?Mice infected with SAR-CoV-2 showed loss of secretory function, elevated autoantibodies, and lymphocyte infiltration in glands.COVID-19 patients showed an increase in autoantibodies. Monoclonal antibodies produced in recovered patients can block ACE2/spike interaction and recognize nuclear antigens.Minor salivary gland biopsies of some convalescent subjects showed focal lymphocytic infiltrates with focus scores.How might this impact on clinical practice or future developments?Our data provide strong evidence for the role of SARS-CoV-2 in inducing Sjögren's disease-like phenotypes.Our work has implications for how patients will be diagnosed and treated effectively.

Autoimmunity and SARS-CoV-2 infection: Unraveling the link in neurological disorders

According to the World Health Organization, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already infected more than 400 million people and caused over 5 million deaths globally. The infection is associated with a wide spectrum of clinical manifestations, ranging from no signs of illness to severe pathological complications that go beyond the typical respiratory symptoms. On this note, new-onset neurological and neuropsychiatric syndromes have been increasingly reported in a large fraction of COVID-19 patients, thus potentially representing a significant public health threat. Although the underlying pathophysiological mechanisms remain elusive, a growing body of evidence suggests that SARS-CoV-2 infection may trigger an autoimmune response, which could potentially contribute to the establishment and/or exacerbation of neurological disorders in COVID-19 patients. Shedding light on this aspect is urgently needed for the development of effective therapeutic intervention. This review highlights the current knowledge of the immune responses occurring in Neuro-COVID patients and discusses potential immune-mediated mechanisms by which SARS-CoV-2 infection may trigger neurological complications.

COVID-19 and antiphospholipid antibodies

Antiphospholipid syndrome and the coagulopathy of COVID-19 share many pathophysiologic features, including endotheliopathy, hypercoagulability, and activation of platelets, complement pathways, and neutrophil extracellular traps, all acting in concert via a model of immunothrombosis. Antiphospholipid antibody production in COVID-19 is common, with 50% of COVID-19 patients being positive for lupus anticoagulant in some studies, and with non-Sapporo criteria antiphospholipid antibodies being prevalent as well. The biological significance of antiphospholipid antibodies in COVID-19 is uncertain, as such antibodies are usually transient, and studies examining clinical outcomes in COVID-19 patients with and without antiphospholipid antibodies have yielded conflicting results. In this review, we explore the biology of antiphospholipid antibodies in COVID-19 and other infections and discuss mechanisms of thrombogenesis in antiphospholipid syndrome and parallels with COVID-19 coagulopathy. In addition, we review the existing literature on safety of COVID-19 vaccination in patients with antiphospholipid antibodies and antiphospholipid syndrome.

Autoimmune and immunoserological markers of COVID-19 pneumonia: Can they help in the assessment of disease severity

Background

Immune dysregulation and associated inefficient anti-viral immunity during Coronavirus Disease 2019 (COVID-19) can cause tissue and organ damage which shares many similarities with pathogenetic processes in systemic autoimmune diseases. In this study, we investigate wide range autoimmune and immunoserological markers in hospitalized patients with COVID-19.

Methods

Study included 51 patients with confirmed Severe Acute Respiratory Syndrome Coronavirus 2 infection and hospitalized due to COVID-19 pneumonia. Wide spectrum autoantibodies associated with different autoimmune inflammatory rheumatic diseases were analyzed and correlated with clinical and laboratory features and pneumonia severity.

Results

Antinuclear antibodies (ANA) positivity was found in 19.6%, anti-cardiolipin IgG antibodies (aCL IgG) in 15.7%, and anti-cardiolipin IgM antibodies (aCL IgM) in 7.8% of patients. Positive atypical x anti-neutrophil cytoplasmic antibodies (xANCA) were detected in 10.0% (all negative for Proteinase 3 and Myeloperoxidase) and rheumatoid factor was found in 8.2% of patients. None of tested autoantibodies were associated with disease or pneumonia severity, except for aCL IgG being significantly associated with higher pneumonia severity index (p = 0.036). Patients with reduced total serum IgG were more likely to require non-invasive mechanical ventilation (NIMV) (p < 0.0001). Serum concentrations of IgG (p = 0.003) and IgA (p = 0.032) were significantly lower in this group of patients. Higher total serum IgA (p = 0.009) was associated with mortality, with no difference in serum IgG (p = 0.115) or IgM (p = 0.175). Lethal outcome was associated with lower complement C4 (p = 0.013), while there was no difference in complement C3 concentration (p = 0.135).

Conclusion

Increased autoimmune responses are present in moderate and severe COVID-19. Severe pneumonia is associated with the presence of aCL IgG, suggesting their role in disease pathogenesis. Evaluation of serum immunoglobulins and complement concentration could help assess the risk of non-invasive mechanical ventilation NIMV and poor outcome.

Clinical and immunological features associated to the development of a sustained immune humoral response in COVID-19 patients: Results from a cohort study

Background

Until now, most of the research addressing long-term humoral responses in coronavirus disease 2019 (COVID-19) had only evaluated the serum titers of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgGs, without the assessment of the baseline antiviral clinical and immune profile, which is the aim of this study and may be the key factor leading to a broad and sustained antibody response.

Methods

We included 103 patients with COVID-19. When the patients sought medical attention (baseline), a blood sample was drawn to perform immunophenotype of lymphocytes by flow cytometry. The patients were assessed 15 days after baseline and then every month until the third month, followed by a last visit 6 months after recruitment. We evaluated the anti-SARS-COV-2 IgG at all time points, and the serum levels of cytokines, chemokines, anti-cellular (AC) antibodies and neutrophil extracellular traps were also assessed during the follow-up. The primary outcome of the study was the presence of a sustained immune humoral response, defined as an anti-SARS-CoV-2 IgG titer >4.99 arbitrary units/mL in at least two consecutive measures. We used generalized lineal models to assess the features associated with this outcome and to assess the effect of the changes in the cytokines and chemokines throughout time on the development of a sustained humoral immune response.

Results

At baseline the features associated to a sustained immune humoral response were the diagnosis of critical disease, absolute number of lymphocytes, serum IP-10, IL-4, IL-2, regulatory T cells, CD8⁺ T cells, and positive AC antibodies. Critical illness and the positivity of AC antibodies were associated with a sustained humoral immune response after 3 months, whilst critical illness and serum IL-13 were the explanatory variables after 6 months.

Conclusion

A sustained immune humoral response is strongly related to critical COVID-19, which is characterized by the presence of AC antibodies, quantitative abnormalities in the T cell compartment, and the serum cytokines and chemokines during acute infection and throughout time.

Autoantibodies in COVID-19 correlate with antiviral humoral responses and distinct immune signatures

BACKGROUND

Several autoimmune features occur during coronavirus disease 2019 (COVID-19), with possible implications for disease course, immunity, and autoimmune pathology. In this study, we longitudinally screened for clinically relevant systemic autoantibodies to assess their prevalence, temporal trajectory, and association with immunity, comorbidities, and severity of COVID-19.

METHODS

We performed highly sensitive indirect immunofluorescence assays to detect antinuclear antibodies (ANA) and antineutrophil cytoplasmic antibodies (ANCA), along with serum proteomics and virome-wide serological profiling in a multicentric cohort of 175 COVID-19 patients followed up to 1 year after infection, eleven vaccinated individuals, and 41 unexposed controls.

RESULTS

Compared with healthy controls, similar prevalence and patterns of ANA were present in patients during acute COVID-19 and recovery. However, the paired analysis revealed a subgroup of patients with transient presence of certain ANA patterns during acute COVID-19. Furthermore, patients with severe COVID-19 exhibited a high prevalence of ANCA during acute disease. These autoantibodies were quantitatively associated with higher SARS-CoV-2-specific antibody titers in COVID-19 patients and in vaccinated individuals, thus linking autoantibody production to increased antigen-specific humoral responses. Notably, the qualitative breadth of antibodies cross-reactive with other coronaviruses was comparable in ANA-positive and ANA-negative individuals during acute COVID-19. In autoantibody-positive patients, multiparametric characterization demonstrated an inflammatory signature during acute COVID-19 and alterations of the B-cell compartment after recovery.

CONCLUSION

Highly sensitive indirect immunofluorescence assays revealed transient autoantibody production during acute SARS-CoV-2 infection, while the presence of autoantibodies in COVID-19 patients correlated with increased antiviral humoral immune responses and inflammatory immune signatures.

The role of antigen-presenting cells in the pathogenesis of COVID-19

Coronavirus Disease 2019 (COVID-19) is one of the three lethal coronavirus outbreaks in the recent two decades and a serious threat to global health all over the world. The principal feature of the COVID-19 infection is the so-called "cytokine storm" exaggerated molecular response to virus distribution, which plays massive tissue and organ injury roles. Immunological treatments, including monoclonal antibodies and vaccines, have been suggested as the main approaches in treating and preventing this disease. Therefore, a proper investigation of the roles of antigen-presenting cells (APCs) in the aforementioned immunological responses appears essential. The present review will provide detailed information about APCs' role in the infection and pathogenesis of SARS-CoV-2 and the effect of monoclonal antibodies in diagnosis and treatment.

Patients with severe COVID-19 do not have elevated autoantibodies against common diagnostic autoantigens

OBJECTIVES

Infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative pathogen of coronavirus disease 2019 (COVID-19) presents occasionally with an aberrant autoinflammatory response, including the presence of elevated circulating autoantibodies in some individuals. Whether the development of autoantibodies against self-antigens affects COVID-19 outcomes remains unclear. To better understand the prognostic role of autoantibodies in COVID-19, we quantified autoantibodies against 23 markers that are used for diagnosis of autoimmune disease. To this end, we used serum samples from patients with severe [intensive care unit (ICU)] and moderate (ward) COVID-19, across two to six consecutive time points, and compared autoantibody levels to uninfected healthy and ICU controls.

METHODS

Acute and post-acute serum (from 1 to 26 ICU days) was collected from 18 ICU COVID-19-positive patients at three to six time points; 18 ICU COVID-19-negative patients (sampled on ICU day 1 and 3); 21 ward COVID-19-positive patients (sampled on hospital day 1 and 3); and from 59 healthy uninfected controls deriving from two cohorts. Levels of IgG autoantibodies against 23 autoantigens, commonly used for autoimmune disease diagnosis, were measured in serum samples using MSD^® U-PLEX electrochemiluminescence technology (MSD division Meso Scale Discovery^®), and results were compared between groups.

RESULTS

There were no significant elevations of autoantibodies for any of the markers tested in patients with severe COVID-19.

CONCLUSIONS

Sample collections at longer time points should be considered in future studies, for assessing the possible development of autoantibody responses following infection with SARS-CoV-2.

An Autoantigen Atlas From Human Lung HFL1 Cells Offers Clues to Neurological and Diverse Autoimmune Manifestations of COVID-19

COVID-19 is accompanied by a myriad of both transient and long-lasting autoimmune responses. Dermatan sulfate (DS), a glycosaminoglycan crucial for wound healing, has unique affinity for autoantigens (autoAgs) from apoptotic cells. DS-autoAg complexes are capable of stimulating autoreactive B cells and autoantibody production. We used DS-affinity proteomics to define the autoantigen-ome of lung fibroblasts and bioinformatics analyses to study the relationship between autoantigenic proteins and COVID-induced alterations. Using DS-affinity, we identified an autoantigen-ome of 408 proteins from human HFL1 cells, at least 231 of which are known autoAgs. Comparing with available COVID data, 352 proteins of the autoantigen-ome have thus far been found to be altered at protein or RNA levels in SARS-CoV-2 infection, 210 of which are known autoAgs. The COVID-altered proteins are significantly associated with RNA metabolism, translation, vesicles and vesicle transport, cell death, supramolecular fibrils, cytoskeleton, extracellular matrix, and interleukin signaling. They offer clues to neurological problems, fibrosis, smooth muscle dysfunction, and thrombosis. In particular, 150 altered proteins are related to the nervous system, including axon, myelin sheath, neuron projection, neuronal cell body, and olfactory bulb. An association with the melanosome is also identified. The findings from our study illustrate a connection between COVID infection and autoimmunity. The vast number of COVID-altered proteins with high intrinsic propensity to become autoAgs offers an explanation for the diverse autoimmune complications in COVID patients. The variety of autoAgs related to mRNA metabolism, translation, and vesicles suggests a need for long-term monitoring of autoimmunity in COVID. The COVID autoantigen atlas we are establishing provides a detailed molecular map for further investigation of autoimmune sequelae of the pandemic, such as "long COVID" syndrome.

Summary Sentence

An autoantigen-ome by dermatan sulfate affinity from human lung HFL1 cells may explain neurological and autoimmune manifestations of COVID-19.

Long COVID from rheumatology perspective - a narrative review

Long-term sequel of acute COVID-19, commonly referred to as long COVID, has affected millions of patients worldwide. Long COVID patients display persistent or relapsing and remitting symptoms that include fatigue, breathlessness, cough, myalgia, arthralgia, sleep disturbance, cognitive impairment and skin rashes. Due to the shared clinical features, laboratory and imaging findings, long COVID could mimic rheumatic disease posing a diagnostic challenge. Our comprehensive literature review will help rheumatologist to be aware of long COVID manifestations and differentiating features from rheumatic diseases to ensure a timely and correct diagnosis is reached.

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.

Paradoxical sex-specific patterns of autoantibody response to SARS-CoV-2 infection

Background

Pronounced sex differences in the susceptibility and response to SARS-CoV-2 infection remain poorly understood. Emerging evidence has highlighted the potential importance of autoimmune activation in modulating the acute response and recovery trajectories following SARS-CoV-2 exposure. Given that immune-inflammatory activity can be sex-biased in the setting of severe COVID-19 illness, the aim of the study was to examine sex-specific autoimmune reactivity to SARS-CoV-2 in the absence of extreme clinical disease.

Methods

In this study, we assessed autoantibody (AAB) reactivity to 91 autoantigens previously linked to a range of classic autoimmune diseases in a cohort of 177 participants (65% women, 35% men, mean age of 35) with confirmed evidence of prior SARS-CoV-2 infection based on presence of antibody to the nucleocapsid protein of SARS-CoV-2. Data were compared to 53 pre-pandemic healthy controls (49% women, 51% men). For each participant, socio-demographic data, serological analyses, SARS-CoV-2 infection status and COVID-19 related symptoms were collected by  an electronic survey of questions. The symptoms burden score was constructed based on the total number of reported symptoms (N = 21) experienced within 6 months prior to the blood draw, wherein a greater number of symptoms corresponded to a higher score and assigned as more severe burden.

Results

In multivariable analyses, we observed sex-specific patterns of autoreactivity associated with the presence or absence (as well as timing and clustering of symptoms) associated with prior COVID-19 illness. Whereas the overall AAB response was more prominent in women following asymptomatic infection, the breadth and extent of AAB reactivity was more prominent in men following at least mildly symptomatic infection. Notably, the observed reactivity included distinct antigens with molecular homology with SARS-CoV-2.

Conclusion

Our results reveal that prior SARS-CoV-2 infection, even in the absence of severe clinical disease, can lead to a broad AAB response that exhibits sex-specific patterns of prevalence and antigen selectivity. Further understanding of the nature of triggered AAB activation among men and women exposed to SARS-CoV-2 will be essential for developing effective interventions against immune-mediated sequelae of COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03184-8.

Pericarditis Following Recovery From COVID-19 Infection in a 15-Year-Old Boy: A Postinflammatory Immune-Mediated Presentation or a New-Onset Autoimmune Disease

As the COVID-19 pandemic evolves, the medical community continues to report a variety of clinical manifestations of SARS-CoV-2 in the pediatric population. Although younger age groups experience less severe disease, attention is given to the immunologic manifestations of the disease. Pericarditis is a rare cardiac complication of COVID-19 infection. We discuss the first case of delayed presentation of pericarditis following recovery from COVID-19 infection in the pediatric population.

A 15-year-old male adolescent presented to the emergency department (ED) with a two-day history of left-sided, sub-sternal chest pain that worsened during inspiration and a low-grade fever. Twenty days prior to this presentation, the patient experienced fever and was tested positive for SARS-CoV-2. His family history was remarkable for Hashimoto thyroiditis and rheumatoid arthritis, with his mother having experienced 18 episodes of pericarditis during the exacerbations of her disease. RT-PCR for SARS-CoV-2 was negative on this occasion and the serology assay identified positive IgG antibodies against the virus. The ECG was suggestive for pericarditis and the diagnosis was confirmed by the presence of pericardial effusion on ECHO. The rest of the aetiological investigations for pericarditis were negative. In view of the strong family history of autoimmunity, questions were raised in the medical team of our hospital regarding the etiology of his pericarditis and on whether it represented a postinflammatory immune-mediated presentation of SARS-CoV-2 or a new-onset autoimmune disease.

Antinuclear antibodies (ANAs) detected by indirect immunofluorescence (IIF) method in acute COVID-19 infection; future roadmap for laboratory diagnosis

INTRODUCTION

As in other viral infections, anti-nuclear antibodies (ANAs) are observed in SARS-CoV-2 infection. We investigated the presence of autoantibodies in acute COVID-19 and the association with early laboratory findings.

MATERIALS AND METHODS

We examined 50 sera (>18 years, 25 Female) from patients with acute COVID-19. ANAs (HEp-20-10 liver biochip), anti-neutrophil cytoplasmic antibody (ANCA, Europlus Granulocyte Mosaic 32) and anti-double stranded DNA were investigated with product of Euroimmune AG (Luebeck, Germany) by indirect immunofluorescence (IIF) method. Also, antibody against cyclic citrullinated peptide (anti-CCP) was examined by a chemiluminisens assay (Euroimmun AG, Luebeck, Germany). Samples from 50 blood bank donors collected before the COVID-19 pandemic were used as controls.

RESULTS

The IIF-ANA test was positive in 18% (N = 9/50) of the patients. The median time of sample collection was 7 days (range: 1-28 days) after diagnosis. ANA was positive in only one (2%) control sample. Five (55.5%) patients were ANA positive with a strong titer (3+). There was no relationship between antibody titration and time of sample collection (p = 0,55). Anti-CCP was detected in a nucleolar (3+) positive patient (2%). ANA was detected in 14.28% (N = 1/7, rods-rings (±), p = 0,78) of patients in the intensive care unit(ICU). Patients treated in the clinic have more and higher titers of ANA, mostly in nucleolar patterns, than ICU patients.

CONCLUSIONS

The variety of antibodies detected in acute COVID-19 and the uncertainty of how long they persist can lead to confusion, especially in the diagnosis of systemic autoimmune rheumatic diseases for IIF-ANA testing in immunology laboratories. Improvements in cell lines and methods will facilitate the diagnostic process.

Acute PR3-ANCA vasculitis in an asymptomatic COVID-19 teenager

We present the case of an acute onset ANCA positive vasculitis in an asymptomatic COVID-19 infected teenager, resulting in significant colonic damage. The patient was initially diagnosed with Henoch-Schönlein purpura and presented with worsening symptoms with significant necrosis of her perineum and rectum requiring surgical debridement and diverting colostomy. As a part of her work-up, she tested positive for COVID-19 total IgG/IgM antibodies and ANCA antibodies. This case complements previously reported cases of COVID-19 induced autoimmune disease in children but is novel in describing extensive intestinal disease as a result of an autoimmune vasculitis in a child.

SARS-CoV-2 Proteome Harbors Peptides Which Are Able to Trigger Autoimmunity Responses: Implications for Infection, Vaccination, and Population Coverage

Autoimmune diseases (ADs) could occur due to infectious diseases and vaccination programs. Since millions of people are expected to be infected with SARS-CoV-2 and vaccinated against it, autoimmune consequences seem inevitable. Therefore, we have investigated the whole proteome of the SARS-CoV-2 for its ability to trigger ADs. In this regard, the entire proteome of the SARS-CoV-2 was chopped into more than 48000 peptides. The produced peptides were searched against the entire human proteome to find shared peptides with similar experimentally confirmed T-cell and B-cell epitopes. The obtained peptides were checked for their ability to bind to HLA molecules. The possible population coverage was calculated for the most potent peptides. The obtained results indicated that the SARS-CoV-2 and human proteomes share 23 peptides originated from ORF1ab polyprotein, nonstructural protein NS7a, Surface glycoprotein, and Envelope protein of SARS-CoV-2. Among these peptides, 21 peptides had experimentally confirmed equivalent epitopes. Amongst, only nine peptides were predicted to bind to HLAs with known global allele frequency data, and three peptides were able to bind to experimentally confirmed HLAs of equivalent epitopes. Given the HLAs which have already been reported to be associated with ADs, the ESGLKTIL, RYPANSIV, NVAITRAK, and RRARSVAS were determined to be the most harmful peptides of the SARS-CoV-2 proteome. It would be expected that the COVID-19 pandemic and the vaccination against this pathogen could significantly increase the ADs incidences, especially in populations harboring HLA-B*08:01, HLA-A*024:02, HLA-A*11:01 and HLA-B*27:05. The Southeast Asia, East Asia, and Oceania are at higher risk of AD development.

Systematic Review of Antiphospholipid Antibodies in COVID-19 Patients: Culprits or Bystanders?

PURPOSE OF REVIEW

COVID-19 patients have a procoagulant state with a high prevalence of thrombotic events. The hypothesis of an involvement of antiphospholipid antibodies (aPL) has been suggested by several reports. Here, we reviewed 48 studies investigating aPL in COVID-19 patients.

RECENT FINDINGS

Prevalence of Lupus Anticoagulant (LA) ranged from 35% to 92% in ICU patients. Anti-cardiolipin (aCL) IgG and IgM were found in up to 52% and up to 40% of patients respectively. Anti-β2-glycoprotein I (aβ2-GPI) IgG and IgM were found in up to 39% and up to 34% of patients respectively. Between 1% and 12% of patients had a triple positive aPL profile. There was a high prevalence of aβ2-GPI and aCL IgA isotype. Two cohort studies found few persistent LA but more persistent solid phase assay aPL over time. aPL determination and their potential role is a real challenge for the treatment of this disease.

COVID-19 and the clinical course of rheumatic manifestations

The manifestations of COVID-19 have been evolving over time. Various post-COVID-19 syndromes are being recognised. Various viruses have been implicated in the pathogenesis of autoimmune diseases, and we expect a similar outcome with the severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2). The SARS-CoV-2 virus penetrates various tissues and organs and has a predisposition to lead to endotheliitis that may cause vascular manifestations including thrombosis. SARS-CoV-2 has been shown to activate Toll-like receptors and the complement system. It perpetuates NETosis and leads to autoantibody formation. These predispose to systemic autoimmunity. Both reactive arthritis and connective tissue disorders such as lupus and inflammatory myositis have been reported after COVID-19. Other reported autoimmune disorders include haemolytic anaemia, immune thrombocytopenia, cutaneous vasculitis, and Guillain Barré-like acute demyelinating disorders. The multi-system inflammatory syndrome in children and its adult counterpart are another post-COVID-19 entity that presents as an admixture of Kawasaki disease and staphylococcal toxic shock syndrome. Patients with preexisting rheumatic diseases may flare during the SARS-CoV-2 infection. They may develop novel autoimmune features also. The immune-suppressants used during the acute COVID-19 illness may confound the outcomes whereas comorbidities present in patients with rheumatic diseases may mask them. There is an urgent need to follow-up patients recovering from COVID and monitor autoantibody production in the context of rheumatic manifestations. Key Points • COVID-19 is associated with both innate and acquired immune reactions and production of various autoantibodies. • Various immune-mediated manifestations such as arthritis, myositis, haemolytic anaemia, thrombocytopenia, and acute demyelination may develop after COVID-19. • Longitudinal cohort data are warranted to describe, predict, and test prevent various rheumatic manifestations in post-COVID-19 subjects.

COVID-19 and Antiphospholipid Antibodies: Time for a Reality Check?

Antiphospholipid antibodies (aPL) comprise a panel of autoantibodies that reflect a potential prothrombotic risk in several autoimmune conditions, most notably antiphospholipid (antibody) syndrome (APS). aPL can be divided into those that form part of the laboratory criteria for APS, namely, lupus anticoagulant (LA), as well as anticardiolipin antibodies (aCL) and anti-β2-glycoprotein I antibodies (aβ2GPI) of the immunoglobulin G and M classes, and those that form a group considered as "noncriteria antibodies." The noncriteria antibodies include, for example, antiphosphatidylserine antibodies (aPS), antiprothrombin antibodies (aPT), and antiphosphatidylserine/prothrombin complex antibodies (aPS/PT). COVID-19 (coronavirus disease 2019) represents a prothrombotic disorder, and there have been several reports of various aPL being present in COVID-19 patients. There have also been similarities drawn between some of the pathophysiological features of COVID-19 and APS, in particular, the most severe form, catastrophic APS (CAPS). In this review, we critically appraise the literature on aPL and COVID-19. This is a companion piece to a separate review focused on LA. In the current review, we primarily concentrate on the so-called solid phase identifiable aPL, such as aCL and aβ2GPI, but also reflect on noncriteria aPL. We conclude that aPL positivity may be a feature of COVID-19, at least in some patients, but in general, identified "solid-phase" aPL are of low titer and not able to be well-linked to the thrombotic aspects of COVID-19. Also, most publications did not assess for aPL persistence, and where persistence was checked, the findings appeared to represent transient aPL. Importantly, high-titer aPL or multiple aPL positivity (including double, triple) were in the minority of COVID-19 presentations, and thus discount any widespread presence of APS, including the most severe form CAPS, in COVID-19 patients.

Aptamer BC 007's Affinity to Specific and Less-Specific Anti-SARS-CoV-2 Neutralizing Antibodies

COVID-19 is a pandemic respiratory disease that is caused by the highly infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Anti-SARS-CoV-2 antibodies are essential weapons that a patient with COVID-19 has to combat the disease. When now repurposing a drug, namely an aptamer that interacts with SARS-CoV-2 proteins for COVID-19 treatment (BC 007), which is, however, a neutralizer of pathogenic autoantibodies in its original indication, the possibility of also binding and neutralizing anti-SARS-CoV-2 antibodies must be considered. Here, the highly specific virus-neutralizing antibodies have to be distinguished from the ones that also show cross-reactivity to tissues. The last-mentioned could be the origin of the widely reported SARS-CoV-2-induced autoimmunity, which should also become a target of therapy. We, therefore, used enzyme-linked immunosorbent assay (ELISA) technology to assess the binding of well-characterized publicly accessible anti-SARS-CoV-2 antibodies (CV07-209 and CV07-270) with BC 007. Nuclear magnetic resonance spectroscopy, isothermal calorimetric titration, and circular dichroism spectroscopy were additionally used to test the binding of BC 007 to DNA-binding sequence segments of these antibodies. BC 007 did not bind to the highly specific neutralizing anti-SARS-CoV-2 antibody but did bind to the less specific one. This, however, was a lot less compared to an autoantibody of its original indication (14.2%, range 11.0–21.5%). It was also interesting to see that the less-specific anti-SARS-CoV-2 antibody also showed a high background signal in the ELISA (binding on NeutrAvidin-coated or activated but noncoated plastic plate). These initial experiments suggest that the risk of binding and neutralizing highly specific anti-SARS CoV-2 antibodies by BC 007 should be low.

Antibodies Against Angiotensin II Receptor Type 1 and Endothelin A Receptor Are Associated With an Unfavorable COVID19 Disease Course

Background

Lung histopathology demonstrates vasculopathy in a subset of deceased COVID19 patients, which resembles histopathology observed in antibody-mediated lung transplant rejection. Autoantibodies against angiotensin II type 1 receptor (AT1R) and Endothelin receptor Type A (ETAR) have been demonstrated in antibody-mediated rejection and may also be associated with severe COVID19 infection. Objective To assess AT1R and ETAR auto-antibodies in COVID19 patients and controls, and explore their association with disease course.

Methods

65 hospitalized patients with COVID19 infection were included. Clinical and laboratory findings were retrospectively assessed. Patients with unfavorable disease course, admitted at the intensive care unit and/or deceased during hospital admission (n=33) were compared to admitted COVID19 patients with favorable disease course (n=32). The presence of antinuclear antibodies (ANA) and auto-antibodies against AT1R or ETAR in peripheral blood were compared between COVID19 with unfavorable and favorable disease course and age matched controls (n=20).

Results

The presence of ANA was not significantly different between COVID19 patients with unfavorable (n=7/33; 21%) and favorable disease course (n=6/32; 19%) (p= 0.804) and controls (n=3/20; 15%). Auto-antibodies against AT1R were significantly increased in unfavorable disease course (median 14.59 U/mL, IQR 11.28 – 19.89) compared to favorable disease course (median 10.67 U/mL, IQR 8.55 – 13.0, p< 0.01). ETAR antibody titers were also significantly increased in unfavorable disease course (median 7.21, IQR 5.0 – 10.45) as compared to favorable disease course (median 4.0, IQR 3.0 – 6.0, p <0.05).

Conclusion

Auto-antibodies against AT1R and ETAR are significantly increased in COVID19 patients with an unfavorable disease course.

Rare presentation of multisystem inflammatory syndrome in an adult associated with SARS-CoV-2 infection: unilateral neck swelling

Multisystem inflammatory syndrome in adults (MIS-A) is a rare but often severe complication of SARS-CoV-2 infection. While several case reports about MIS-A in the setting of COVID-19 have been published since the term was first coined in June 2020, a clear description of the underlying pathophysiology and guideline-based recommendations on the diagnostic and therapeutic approach are lacking. What has been reported is that in the absence of severe respiratory illness, MIS-A can present with hypotension or shock, high-grade fever, abdominal pain, diarrhoea and severe weakness days to weeks after SARS-CoV-2 infection. Here, we present a case of a 28-year-old man who presented with a rarely described initial symptom: unilateral neck swelling. His presentation, disease progression and treatment course provide further information about MIS-A as a complication and in formulating diagnostic guidelines.

An autoantigen profile of human A549 lung cells reveals viral and host etiologic molecular attributes of autoimmunity in COVID-19

We aim to establish a comprehensive COVID-19 autoantigen atlas in order to understand autoimmune diseases caused by SARS-CoV-2 infection. Based on the unique affinity between dermatan sulfate and autoantigens, we identified 348 proteins from human lung A549 cells, of which 198 are known targets of autoantibodies. Comparison with current COVID data identified 291 proteins that are altered at protein or transcript level in SARS-CoV-2 infection, with 191 being known autoantigens. These known and putative autoantigens are significantly associated with viral replication and trafficking processes, including gene expression, ribonucleoprotein biogenesis, mRNA metabolism, translation, vesicle and vesicle-mediated transport, and apoptosis. They are also associated with cytoskeleton, platelet degranulation, IL-12 signaling, and smooth muscle contraction. Host proteins that interact with and that are perturbed by viral proteins are a major source of autoantigens. Orf3 induces the largest number of protein alterations, Orf9 affects the mitochondrial ribosome, and they and E, M, N, and Nsp proteins affect protein localization to membrane, immune responses, and apoptosis. Phosphorylation and ubiquitination alterations by viral infection define major molecular changes in autoantigen origination. This study provides a large list of autoantigens as well as new targets for future investigation, e.g., UBA1, UCHL1, USP7, CDK11A, PRKDC, PLD3, PSAT1, RAB1A, SLC2A1, platelet activating factor acetylhydrolase, and mitochondrial ribosomal proteins. This study illustrates how viral infection can modify host cellular proteins extensively, yield diverse autoantigens, and trigger a myriad of autoimmune sequelae. Our work provides a rich resource for studies into “long COVID” and related autoimmune sequelae.

An Autoantigen-ome from HS-Sultan B-Lymphoblasts Offers a Molecular Map for Investigating Autoimmune Sequelae of COVID-19

To understand how COVID-19 may induce autoimmune diseases, we have been compiling an atlas of COVID-autoantigens (autoAgs). Using dermatan sulfate (DS) affinity enrichment of autoantigenic proteins extracted from HS-Sultan lymphoblasts, we identified 362 DS-affinity proteins, of which at least 201 (56%) are confirmed autoAgs. Comparison with available multi-omic COVID data shows that 315 (87%) of the 362 proteins are affected in SARS-CoV-2 infection via altered expression, interaction with viral components, or modification by phosphorylation or ubiquitination, at least 186 (59%) of which are known autoAgs. These proteins are associated with gene expression, mRNA processing, mRNA splicing, translation, protein folding, vesicles, and chromosome organization. Numerous nuclear autoAgs were identified, including both classical ANAs and ENAs of systemic autoimmune diseases and unique autoAgs involved in the DNA replication fork, mitotic cell cycle, or telomerase maintenance. We also identified many uncommon autoAgs involved in nucleic acid and peptide biosynthesis and nucleocytoplasmic transport, such as aminoacyl-tRNA synthetases. In addition, this study found autoAgs that potentially interact with multiple SARS-CoV-2 Nsp and Orf components, including CCT/TriC chaperonin, insulin degrading enzyme, platelet-activating factor acetylhydrolase, and the ezrin-moesin-radixin family. Furthermore, B-cell-specific IgM-associated ER complex (including MBZ1, BiP, heat shock proteins, and protein disulfide-isomerases) is enriched by DS-affinity and up-regulated in B-cells of COVID-19 patients, and a similar IgH-associated ER complex was also identified in autoreactive pre-B1 cells in our previous study, which suggests a role of autoreactive B1 cells in COVID-19 that merits further investigation. In summary, this study demonstrates that virally infected cells are characterized by alterations of proteins with propensity to become autoAgs, thereby providing a possible explanation for infection-induced autoimmunity. The COVID autoantigen-ome provides a valuable molecular resource and map for investigation of COVID-related autoimmune sequelae and considerations for vaccine design.