Antiphospholipid Antibodies in Critically Ill Patients With COVID-19

Coronavirus disease 2019 and catastrophic antiphospholipid syndrome: Case report

RATIONALE

The emergence of catastrophic antiphospholipid syndrome (CAPS) alongside coronavirus disease 2019 (COVID-19) is of great concern, because of its high mortality and unclear mechanism. This severe disease, characterized by multiple thrombi and multisystem disorder, has notably diverse clinical presentations, which complicates its diagnosis in clinical practice. Now, we report a rare case of CAPS in a patient with COVID-19.

PATIENT CONCERNS

A 64-year-old patient who mainly presented with pain and swelling 2 months ago progressed gradually into multiple thrombi, including pulmonary embolism, renal embolism, and deep vein thrombosis; transient ischemic attack; multiple organ dysfunction with acute kidney injury; and necrosis of both lower limbs, left upper extremity, both ears, and penile gangrene.

DIAGNOSES

He was diagnosed as CAPS with COVID-19 by positive severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) testing and high-titer immunoglobulin (Ig) A anti-β2-glycoprotein I antibody (anti-β2GPI).

INTERVENTIONS

Active rescue treatments such as anticoagulants, plasmapheresis, glucocorticoid pulse therapy, antibiotics, and multi-organ functional support alleviated the disease effectively.

OUTCOMES

Although his clinical symptoms were successfully controlled, we could not save the necrotic tissue. The patient refused to undergo limb amputation and died of necrotic tissue infection.

LESSONS

CAPS in patients with COVID-19 is an extremely serious disease with a high mortality rate. A delay in diagnosis and treatment can result in potentially devastating consequences. Therefore, physicians should be alert to the possibility of CAPS in patients with multiple thrombi and COVID-19. Furthermore, this case serves as a foundation upon which future studies can build to investigate the possible mechanisms of IgA anti-β2GPI-positive CAPS in patients with COVID-19, which may guide the exploration of potential therapeutic strategies to prevent the disease's progression.

Prevalence of antiphospholipid antibodies in COVID-19 patients: A meta-analysis

OBJECTIVE

In some reports, antiphospholipid antibodies (aPL) prevalence is higher in COVID-19 patients. This study intended to compare aPL prevalence between COVID-19 patients and healthy controls, and differences in aPL types using meta-analysis.

METHODS

This work retrieved published literature about association between COVID-19 and aPL from Embase, Web of Science, PubMed, and The Cochrane Library databases. The observation group was COVID-19 patients, and the control group was healthy individuals. Outcome measures contained any of following aPLs: classic aPL: anti-cardiolipin antibodies (aCL) and anti-β2-glycoprotein-1 antibodies (Anti-β2GP1); other non-criteria aPL: anti-phosphatidylserine/prothrombin antibodies (aPS/PT) and anti-annexin-V antibodies (AnV). Meta-analysis was done on Review Manager 5.4.

RESULTS

10 studies involving 2288 patients were deemed eligible for inclusion. The results of the meta-analysis showed that the prevalence of Classic aPL and Any aPL in the COVID-19 group was significantly higher than in the healthy group (Classic aPL, RR = 2.55, 95 % CI = 1.83-3.55, P < 0.00001; Any aPL, RR = 2.34, 95 % CI = 1.46-3.77, P = 0.0005). Anti-β2GP1 IgA antibodies were the most common aPL in COVID-19 patients, with a significantly higher prevalence than in the healthy group (RR = 4.26, 95 % CI = 2.84-6.40, P < 0.00001). The prevalence of the four types of IgM aPL was significantly higher in the COVID-19 group compared to the healthy group, while there was no significant difference in aPL IgG between the two groups.

CONCLUSION

The prevalence of aPL in COVID-19 patients was significantly higher than in the healthy control group. IgM aPL was more easily detectable in the early stages of COVID-19 infection, while IgG aPL may be of more concern in the later time points of the immune epidemiology following SARS-CoV-2 infection.

Does COVID-19 infection or COVID-19 mRNA vaccination induce antiphospholipid antibodies in women with recurrent pregnancy loss?

Antiphospholipid syndrome (APS) is a well-established cause of recurrent pregnancy loss (RPL). If coronavirus disease 2019 (COVID-19) infection or vaccination induces antiphospholipid antibody (aPL) production, it may lead to miscarriage in subsequent pregnancies. We investigated the association between COVID-19 infection and vaccination history with aPL positivity in women with RPL. This study included 424 women with RPL. We found no difference in the positivity rate for aPL according to the presence or absence of a history of COVID-19 infection. The positivity rate was significantly higher in patients infected during the omicron period (27.9 %, 43/154) than in those infected during the delta period (8.7 %, 2/23) of the COVID-19 pandemic (P = 0.0351). Of the 416 patients with a detailed vaccination history, 365 (87.7 %) had received at least one vaccination. The aPL positivity rate did not significantly differ according to the history of vaccination or number of vaccinations. Our results suggest that mild COVID-19 infection and vaccination are unlikely to stimulate aPL production and, therefore, are unlikely to increase miscarriage due to APS.

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.

The New Occurrence of Antiphospholipid Syndrome in Severe COVID-19 Cases with Pneumonia and Vascular Thrombosis Could Explain the Post-COVID Syndrome

Introduction: The classification of antiphospholipid syndrome (APS) comprises clinical criteria (vascular thrombosis or obstetric complications throughout life) and laboratory criteria (antiphospholipid antibodies (aPLs) positivity, confirmed at least twice at 12-week interval). Methods: In 100 patients admitted to the hospital with COVID-19 pneumonia, thrombosis and pregnancy complications were recorded during the hospital stay and in personal medical history. They were tested for nine types of aPLs at four time points (admission, deterioration, discharge, and 3-month follow-up): anticardiolipin (aCL), anti-β2-glycoproteinI (anti-β2GPI), and antiphosphatidylserine/prothrombin (aPS/PT) isotypes IgM/IgG/IgA. Results: During hospitalization, aPLs were detected at least once in 51% of patients. All 7% of deceased patients tested negative for aPLs upon admission, and only one patient became aCL IgG positive as his condition worsened. In 83.3% of patients, intrahospital thrombosis was not related to aPLs. One patient with pulmonary artery and cerebral artery thrombosis was given an APS diagnosis (triple aPLs positivity on admission, double on follow-up). Personal anamnesis (PA) for thromboembolism was verified in 10 patients, all of whom tested negative for aPLs at admission; however, transition to aPLs positivity at discharge (as the disease subsided) was seen in 60% of patients: three of six with arterial thrombosis (at follow-up, two did not appear, and one was negativized) and three of four with deep vein thrombosis (one was confirmed at follow-up and diagnosed with APS, one was negativized, and one did not appear). At admission, the majority of the aPLs were of the aCL IgG class (58.8%). Unexpectedly, as the COVID-19 disease decreased, anti-β2GPI IgG antibodies (linked with thromboses) became newly positive at discharge (14.9%), as confirmed at follow-up (20.8%). Conclusion: The incidence of APS in our cohort was 2.0%, whereas in the general population, it ranges from 0.001% to 0.002%. The incidence might have increased even more if the four aPLs-positive patients with intrahospital thrombosis/history of thrombosis had attended follow-up. Recommendation: All patients with severe COVID-19 or post-COVID syndrome should be evaluated for current/previous thrombosis and tested for aPLs at least twice: at admission to the hospital and at discharge, then retested 3 months later in positive cases in order to be given the appropriate therapy.

Antiphospholipid Antibodies and COVID-19: A Systematic Review of Clinical Implications

INTRODUCTION

As the COVID-19 pandemic transitions, understanding the intricate dynamics of the disease becomes paramount. This systematic review explores the role of antiphospholipid antibodies in COVID-19, focusing on their potential clinical implications.

METHODS

This systematic review, following PRISMA guidelines, assesses studies exploring the link between antiphospholipid antibodies and COVID-19. PubMed/Medline, Embase, and Scopus were searched for relevant studies published up to December 22, 2024. Inclusion criteria comprised studies involving patients diagnosed with COVID-19 and reporting on the presence of antiphospholipid antibodies. The risk of bias in individual studies was evaluated using the Joanna Briggs Institute appraisal tool.

RESULTS

Our Study includes 59 records involving a total of 28,489 COVID-19 patients. Antiphospholipid antibodies were tested in 14,498 COVID-19 patients. It was observed that 50.84% of patients tested positive for antiphospholipid antibodies. Various types of antiphospholipid antibodies, including Anticardiolipin, Anti beta2 glycoproteins, and Lupus anticoagulant antibody, displayed prevalence rates in the patients with thrombosis. The overall frequency of antiphospholipid antibodies in thrombosis patients was 38.55%.

CONCLUSION

The presence of antiphospholipid antibodies in a significant proportion of COVID-19 patients underscores the need for a detailed investigation into their role in thrombotic events. Our study highlights potential avenues for targeted interventions. However, the evolving nature of COVID-19 necessitates continued research efforts to clarify clinical implications and optimize management strategies in this complex landscape of thrombosis and immunology. The review reveals some limitations, such as variability in study designs and demographics and inherent differences in methodologies among included studies. Future studies should address these limitations with standardized methodologies for more conclusive findings.

Immune complexome analysis reveals an autoimmune signature predictive of COVID-19 severity

BACKGROUND

The factors contributing to the development of severe coronavirus disease 2019 (COVID-19) following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain unclear. Although the presence of immune complexes (ICs), formed between antibodies and their antigens, has been linked to COVID-19 severity, their role requires further investigation, and the antigens within these ICs are yet to be characterized.

METHOD

Here, a C1q enzyme-liked immunosorbent assay and immune complexome analysis were used to determine IC concentrations and characterize IC antigens, respectively, in the sera of 64 unvaccinated COVID-19 patients with PCR-confirmed SARS-CoV-2 infection, enrolled at seven participating centers in 2020. For the analysis, the patients were split into the severe (n = 35) and non-severe (n = 28) groups on the basis of their COVID-19 symptoms.

RESULTS

We found that neither serum IC concentration nor IC antigen number was associated with COVID-19 severity. However, we identified six IC antigens, which were significantly enriched in the severe versus non-severe group. These IC antigens were all derived from human proteins, namely haptoglobin, the serum amyloid A-2 protein, the serum amyloid A-1 protein, clusterin, and lipopolysaccharide-binding protein, and complement-factor-H-related protein 3. Meanwhile, we found no association between COVID-19 severity and IC antigens derived from SARS-CoV-2 proteins. Collectively, the six IC antigens predicted COVID-19 severity with a moderate degree of accuracy (area under the receiver operating characteristic curve = 0.90, sensitivity = 94 %, specificity = 79 %).

CONCLUSIONS

The IC antigen signature identified in this study may have important implications for the diagnosis and treatment of severe COVID-19.

Characteristics of Oral Adverse Effects following COVID-19 Vaccination and Similarities with Oral Symptoms in COVID-19 Patients: Taste and Saliva Secretory Disorders

Although coronavirus disease 2019 (COVID-19) vaccines exhibit diverse side effects, taste and saliva secretory disorders have remained poorly understood despite their negative impact on the overall quality of life. The present study aimed to characterize oral adverse effects following COVID-19 vaccination and assess their similarities with oral symptoms in COVID-19 patients. A literature search was conducted in databases, including PubMed, LitCovid, and Google Scholar, to retrieve relevant studies. The narrative review indicated that a certain number of vaccinated people develop ageusia, dysgeusia, hypogeusia, xerostomia, and dry mouth, while they are rare compared with COVID-19 oral symptoms. The prevalence of oral adverse effects varies by country/region and such geographical differences may be related to the type of vaccine used. Similar to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, COVID-19 vaccination adversely affects taste perception and salivary secretion in females and older subjects more frequently than in males and younger subjects. Their impairments mostly appear within 3 days of vaccination, and bitter taste is specifically impaired in some cases. Considering that oral adverse effects following COVID-19 vaccination share some characteristics with oral symptoms in COVID-19 patients, it is speculated that the spike protein derived from COVID-19 vaccination and SARS-CoV-2 infection may be pathophysiologically responsible for taste and saliva secretory disorders. This is because such spike protein has the potential to interact with ACE2 expressed on the relevant cells, produce proinflammatory cytokines, and form antiphospholipid antibodies. Our results do not deny the advantages of COVID-19 vaccination, but attention should be paid to post-vaccination oral effects in addition to COVID-19 oral symptoms. Although coronavirus disease 2019 (COVID-19) vaccines exhibit diverse side effects, taste and saliva secretory disorders have remained poorly understood despite their negative impact on the overall quality of life. The present study aimed to characterize oral adverse effects following COVID-19 vaccination and assess their similarities with oral symptoms in COVID-19 patients. A literature search was conducted in databases, including PubMed, LitCovid, and Google Scholar, to retrieve relevant studies. The narrative review indicated that a certain number of vaccinated people develop ageusia, dysgeusia, hypogeusia, xerostomia, and dry mouth, while they are rare compared with COVID-19 oral symptoms. The prevalence of oral adverse effects varies by country/region and such geographical differences may be related to the type of vaccine used. Similar to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, COVID-19 vaccination adversely affects taste perception and salivary secretion in females and older subjects more frequently than in males and younger subjects. Their impairments mostly appear within 3 days of vaccination, and bitter taste is specifically impaired in some cases. Considering that oral adverse effects following COVID-19 vaccination share some characteristics with oral symptoms in COVID-19 patients, it is speculated that the spike protein derived from COVID-19 vaccination and SARS-CoV-2 infection may be pathophysiologically responsible for taste and saliva secretory disorders. This is because such spike protein has the potential to interact with ACE2 expressed on the relevant cells, produce proinflammatory cytokines, and form antiphospholipid antibodies. Our results do not deny the advantages of COVID-19 vaccination, but attention should be paid to post-vaccination oral effects in addition to COVID-19 oral symptoms.

Pathological Sequelae of SARS-CoV-2: A Review for Clinicians

The Coronavirus Disease 2019 (COVID-19) pandemic, driven by the novel coronavirus and its variants, has caused over 518 million infections and 6.25 million deaths globally, leading to a significant health crisis. Beyond its primary respiratory impact, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has been implicated in various extra-pulmonary complications. Research studies reveal that the virus affects multiple organs, including the kidneys, liver, pancreas, and central nervous system (CNS), largely due to the widespread expression of Angiotensin Converting Enzyme-2 (ACE-2) receptors. Clinical evidence shows that the virus can induce diabetes by disrupting pancreatic and liver functions as well as cause acute kidney injury. Additionally, neurological complications, including cognitive impairments and neuroinflammation, have been observed in a significant number of COVID-19 patients. This review discusses the mechanisms linking SARS-CoV-2 to acute kidney injury, Type 1 and Type 2 Diabetes Mellitus (T1DM and T2DM), emphasizing its effects on pancreatic beta cells, insulin resistance, and the regulation of gluconeogenesis. We also explore how SARS-CoV-2 induces neurological complications, detailing the intricate pathways of neuro-invasion and the potential to trigger conditions such as Alzheimer's disease (AD). By elucidating the metabolic and neurological manifestations of COVID-19 and the underlying pathogenic mechanisms, this review underscores the imperative for continued research and the development of effective therapeutic interventions to mitigate the long-term and short-term impacts of SARS-CoV-2 infection.

Comparison of anti-phospholipid antibody titers before and after SARS-CoV-2 mRNA vaccination in hospital staff

Multiple concerning reports have emerged of cardiovascular complications, particularly thrombosis, following mRNA vaccination against the SARS-CoV-2 pathogen. The presence of serologically persistent anti-phospholipid antibodies is a characteristic of antiphospholipid syndrome, which presents with clinical manifestations including thrombosis or pregnancy morbidity. Anti-SARS-CoV-2 mRNA vaccines pose a theoretical risk of cross-reactivity between the SARS-CoV-2 spike protein and phospholipids in host tissues. In this study, serum anti-phospholipid antibody titers before and after SARS-CoV-2 mRNA vaccination were compared among 184 hospital staff members. Although no significant differences were found in terms of antibody titers targeting cardiolipin and β2-glycoprotein I, post-vaccination antibody titers targeting phosphatidylethanolamine were found to be significantly increased compared to pre-vaccination levels (p = 0.008). Anti-phosphatidylethanolamine antibodies are the most common anti-phospholipid antibodies detected in patients with recurrent miscarriages at < 10 weeks of gestation. However, the association between vaccination and these types of adverse events remains unknown, thus warranting further investigation.

Clinical features and treatment of 70 children with lupus anticoagulant-hypoprothrombinemia syndrome: a retrospective study from a single center in China

Background

Lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS) is a rare acquired bleeding disorder characterized by the presence of lupus anticoagulant (LA) and acquired hypoprothrombinemia.

Objectives

To summarize the experience of diagnosis, clinical features, and treatment of lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS).

Methods

A retrospective study of 70 children diagnosed with LAHPS from January 2019 to February 2024 at a single center was conducted.

Results

A total of 70 subjects (32 boys and 38 girls), with a mean age of 5.58 years, were included in the study. Among these subjects, 15 had autoimmune diseases (AIDs), 51 had infections, and 4 had unknown causes. Fifty-six of 70 (80%) subjects experienced bleeding with the median bleeding score of 4, 1 of 70 (1.4%) presented with thrombosis, and 13 of 70 (18.6%) were asymptomatic. All patients exhibited prolonged prothrombin time, significantly prolonged activated partial thromboplastin time, decreased factor (F)II activity (FII:C), and positive lupus anticoagulant. There was a weak negative correlation between the severity of bleeding and FII:C level (rs = -0.4283; P < .001). Patients with infection-associated LAHPS were younger than those with AIDs-associated LAHPS (P < .0001). In the study, LAHPS subjects are treated with corticosteroids as the first-line therapy, or in combination with immunosuppressants. Coagulation factor replacement therapy can effectively prevent and control bleeding events. After follow-up, lupus anticoagulant of all patients had turned negative within 12 weeks. And, prothrombin time and FII:C were completely normalized of all patients without recurrence of bleeding and without thrombosis.

Conclusion

Children develop LAHPS most commonly after AIDs and infection. Most patients presented with mild to moderate bleeding. The severity of bleeding symptoms was not exactly parallel to the decreased FII:C level.

IgA Anti-β2-Glycoprotein I Antibodies as Markers of Thrombosis and Severity in COVID-19 Patients

Patients with COVID-19 may develop a hypercoagulable state due to tissue and endothelial injury, produced by an unbalanced immune response. Therefore, an increased number of thromboembolic events has been reported in these patients. The aim of this study is to investigate the presence of antiphospholipid antibodies (aPL) in COVID-19 patients, their role in the development of thrombosis and their relationship with the severity of the disease. In this retrospective study, serum samples from 159 COVID-19 patients and 80 healthy donors were analysed for the presence of aPL. A total of 29 patients (18.2%) and 14 healthy donors (17.5%) were positive for aPL. Nineteen COVID-19 patients (12%) but no healthy donor presented a positive percentage of the IgA isotype aPL. IgA anti-β2-glycoprotein I antibodies (anti-β2GPI) were the most frequent type (6.3%) in patients but was not detected in any healthy donor. The positivity of this antibody was found to be significantly elevated in patients with thromboembolic events (25% vs. 5%, p = 0.029); in fact, patients with positive IgA anti-β2GPI had an incidence of thrombosis over six times higher than those who had normal antibody concentrations [OR (CI 95%) of 6.67 (1.5-30.2), p = 0.014]. Additionally, patients with moderate-severe disease presented a higher aPL positivity than patients with mild disease according to the Brescia (p = 0.029) and CURB-65 (p = 0.011) severity scales. A multivariate analysis showed that positivity for IgA anti-β2GPI is significantly associated with disease severity measured by CURB-65 [OR (CI 95%) 17.8 (1.7-187), p = 0.0016]. In conclusion, COVID-19 patients have a significantly higher positive percentage of the IgA isotype aPL than healthy donors. IgA anti-β2GPI antibodies were the most frequently detected aPL in COVID-19 patients and were associated with thrombosis and severe COVID-19 and are thus proposed as a possible marker to identify high-risk patients.

The development of anticyclic citrullinated peptide (anti-CCP) antibody following severe COVID-19

OBJECTIVES

The dysregulated immune response is one of the cardinal features of severe coronavirus disease 2019 (COVID-19). This study was conducted to clarify the occurrence of autoantibodies (AABs) associated with systemic autoimmune rheumatic diseases (SARDs) in hospitalized patients with a moderate, severe, and critical form of COVID-19.

METHODS

The serum samples obtained from 176 hospitalized COVID-19 patients were investigated in this study, including patients with moderate (N = 90), severe (N = 50), and critical (N = 36) forms of COVID-19. Also, the serum samples collected from healthy subjects before the COVID-19 pandemic were used as controls (N = 176). The antinuclear antibodies (ANAs), antidouble-stranded DNA (anti-dsDNA), cytoplasmic-anti neutrophil cytoplasmic antibody (c-ANCA), perinuclear ANCA (p-ANCA), antiphospholipid antibodies (aPLs), and anticyclic citrullinated peptide (anti-CCP) occurrence was evaluated using a solid-phase enzyme-linked immunosorbent assay (ELISA).

RESULTS

The results showed that the occurrence of ANAs, anti-dsDNA, anti-CCP, c-ANCA, and p-ANCA was significantly higher in the COVID-19 patients compared to serum obtained from healthy subjects (p < .0001, p < .0001, p < .0001, p < .05, and p < .001, respectively). The positive number of anti-CCP tests increased significantly in severe COVID-19 compared to the moderate group (p < .01).

CONCLUSION

Our study further supports the development of autoantibodies related to systemic autoimmune rheumatologic diseases. To the best of our knowledge, this is the first study with a large sample size that reported the occurrence of anti-CCP in a severe form of COVID-19.

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.

Viewpoint: Lupus anticoagulant detection and interpretation in antiphospholipid syndrome

Lupus anticoagulant (LA) is a well-established risk factor for the clinical manifestations of antiphospholipid syndrome (APS). Accurate LA detection is an essential prerequisite for optimal diagnosis and management of patients with APS or aPL carriers. Variability remains a challenge in LA testing, with reliable detection influenced by multiple factors, including pre-analytical conditions, anticoagulation treatment, choice of tests and procedures performed, as well as interpretation of results, that can lead to false-positives or negatives. A standardised approach to LA testing, following current guidance, based on published data and international consensus, and with attention to detail, is required to underpin accurate detection of LA. Future work should focus on better characterisation of the nature of LA, which may ultimately lead to improved diagnosis and management of patients with APS and aPL carriers. This article reviews current practice and challenges, providing an overview on detection of LA.

Sarcoidosis-related autoimmune inflammation in COVID-19 convalescent patients

Currently, there are a large number of reports about the development of autoimmune conditions after COVID-19. Also, there have been cases of sarcoid-like granulomas in convalescents as a part of the post-COVID-19 syndrome. Since one of the etiological theories of sarcoidosis considers it to be an autoimmune disease, we decided to study changes in the adaptive humoral immune response in sarcoidosis and SARS-CoV-2 infection and to find out whether COVID-19 can provoke the development of sarcoidosis. This review discusses histological changes in lymphoid organs in sarcoidosis and COVID-19, changes in B cell subpopulations, T-follicular helper cells (Tfh), and T-follicular regulatory cells (Tfr), and analyzes various autoantibodies detected in these pathologies. Based on the data studied, we concluded that SARS-CoV-2 infection may cause the development of autoimmune pathologies, in particular contributing to the onset of sarcoidosis in convalescents.

Antiphospholipid antibodies are enriched post-acute COVID-19 but do not modulate the thrombotic risk

BACKGROUND AND OBJECTIVES

COVID-19-associated coagulopathy, shown to increase the risk for the occurrence of thromboses and microthromboses, displays phenotypic features of the antiphospholipid syndrome (APS), a prototype antibody-mediated autoimmune disease. Several groups have reported elevated levels of criteria and non-criteria antiphospholipid antibodies (aPL), assumed to cause APS, during acute or post-acute COVID-19. However, disease heterogeneity of COVID-19 is accompanied by heterogeneity in molecular signatures, including aberrant cytokine profiles and an increased occurrence of autoantibodies. Moreover, little is known about the association between autoantibodies and the clinical events. Here, we first aim to characterise the antiphospholipid antibody, anti-SARS-CoV-2 antibody, and the cytokine profiles in a diverse collective of COVID-19 patients (disease severity: asymptomatic to intensive care), using vaccinated individuals and influenza patients as comparisons. We then aim to assess whether the presence of aPL in COVID-19 is associated with an increased incidence of thrombotic events in COVID-19.

METHODS AND RESULTS

We conducted anti-SARS-CoV-2 IgG and IgA microELISA and IgG, IgA, and IgM antiphospholipid line immunoassay (LIA) against 10 criteria and non-criteria antigens in 155 plasma samples of 124 individuals, and we measured 16 cytokines and chemokines in 112 plasma samples. We additionally employed clinical and demographic parameters to conduct multivariable regression analyses within multiple paradigms. In line with recent results, we find that IgM autoantibodies against annexin V (AnV), β2-glycoprotein I (β2GPI), and prothrombin (PT) are enriched upon infection with SARS-CoV-2. There was no evidence for seroconversion from IgM to IgG or IgA. PT, β2GPI, and AnV IgM as well as cardiolipin (CL) IgG antiphospholipid levels were significantly elevated in the COVID-19 but not in the influenza or control groups. They were associated predominantly with the strength of the anti-SARS-CoV-2 antibody titres and the major correlate for thromboses was SARS-CoV-2 disease severity.

CONCLUSION

While we have recapitulated previous findings, we conclude that the presence of the aPL, most notably PT, β2GPI, AnV IgM, and CL IgG in COVID-19 are not associated with a higher incidence of thrombotic events.

Severity of neurological Long-COVID symptoms correlates with increased level of autoantibodies targeting vasoregulatory and autonomic nervous system receptors

BACKGROUND

The Long-COVID syndrome constitutes a plethora of persisting symptoms with neurological disorders being the most disabling ones. The pathogenesis of Long-COVID is currently under heavy scrutiny and existing data on the role of auto-immune reaction to G-protein coupled receptors (GPCR) are conflicting.

METHODS

This monocentric, cross-sectional study included patients who suffered a mild to moderate SARS-CoV-2 infection up to 12 months prior to enrollment with (n = 72) or without (n = 58) Long-COVID diagnosis according to the German S1 guideline or with no known history of SARS-CoV-2 infection (n = 70). While autoantibodies specific for the vasoregulation associated Adrenergic Receptor (ADR) B1 and B2 and the CNS and vasoregulation associated muscarinic acetylcholine receptor (CHR) M3 and M4 were measured by ELISA, neurological disorders were quantified by internationally standardized questionnaires.

RESULTS

The prevalence and concentrations of evaluated autoantibodes were significantly higher in Long-COVID compared to the 2 other groups (p = 2.1*10-9) with a significantly higher number of patients with simultaneous detection of more than one autoantibody in the Long-COVID group (p = 0.0419). Importantly, the overall inflammatory state was low in all 3 groups. ARB1 and ARB2 correlated negatively CERAD Trail Marking A and B (R ≤ -0.26, p ≤ 0.043), while CHRM3 correlated positively with Chadler Fatigue Scale (R = 0.37, p = 0.0087).

CONCLUSIONS

Concentrations of autoantibodies correlates to the intensity of neurological disorders including psychomotor speed, visual search, attention, and fatigue.

Thrombosis and antiphospholipid antibodies in Japanese COVID-19: based on propensity score matching

Background

Thrombosis is a unique complication of coronavirus disease 2019 (COVID-19). Although antiphospholipid antibodies (aPL) are detected in COVID-19 patients, their clinical significance remains elusive. We evaluated the prevalence of aPL and serum concentrations of beta-2 glycoprotein I (β2GPI), a major self-antigen for aPL, in Japanese COVID-19 patients with and without thrombosis.

Methods

This retrospective single-center nested case-control study included 594 hospitalized patients with COVID-19 between January 2020 and August 2021. Thrombotic complications were collected from medical records. Propensity score-matching method (PSM) (1:2 matching including age, sex, severity on admission, and prior history of thrombosis) was performed to compare the prevalence and titer of aPL (anti-cardiolipin (aCL) IgG/IgM, anti-β2GPI IgG/IgM/IgA, and anti-phosphatidylserine/prothrombin antibody (aPS/PT) IgG/IgM) and serum β2GPI concentration. In addition, PSM (1:1 matching including age and sex) was performed to compare the serum β2GPI concentration between COVID-19 patients and healthy donors.

Results

Among the patients, 31 patients with thrombosis and 62 patients without were compared. The prevalence of any aPLs was indifferent regardless of the thrombosis (41.9% in those with thrombosis vs. 38.7% in those without, p =0.82). The positive rates of individual aPL were as follows: anti-CL IgG (9.7% vs. 1.6%, p =0.11)/IgM (0% vs. 3.2%, p =0.55), anti-β2GP1 IgG (22.6% vs. 9.7%, p =0.12)/IgA (9.7% vs. 9.7%, p =1.0)/IgM (0% vs. 0%, p =1.0), and anti-PS/PT IgG (0% vs. 1.6%, p =1.0)/IgM (12.9% vs. 21.0%, p =0.41), respectively. The aPL titers were also similar regardless of thrombosis. The levels of β2GPI in COVID-19 patients were lower than those in the healthy donors.

Conclusion

Although aPLs were frequently detected in Japanese COVID-19 patients, their prevalence and titer were irrelevant to thrombotic complications. While COVID-19 patients have lower levels of serum β2GPI than healthy blood donors, β2GPI levels were indifferent regardless of thrombosis. Although most of the titers were below cut-offs, positive correlations were observed among aPLs, suggesting that the immune reactions against aPL antigens were induced by COVID-19. We should focus on the long-term thromboembolic risk and the development of APS in the aPL-positive patients with high titer or multiple aPLs.

Molecular mimicry and autoimmunity in the time of COVID-19

Infectious diseases are commonly implicated as potential initiators of autoimmune diseases (ADs) and represent the most commonly known factor in the development of autoimmunity in susceptible individuals. Epidemiological data and animal studies on multiple ADs suggest that molecular mimicry is one of the likely mechanisms for the loss of peripheral tolerance and the development of clinical disease. Besides molecular mimicry, other mechanisms such as defects in central tolerance, nonspecific bystander activation, epitope-determinant spreading, and/or constant antigenic stimuli, may also contribute for breach of tolerance and to the development of ADs. Linear peptide homology is not the only mechanism by which molecular mimicry is established. Peptide modeling (i.e., 3D structure), molecular docking analyses, and affinity estimation for HLAs are emerging as critical strategies when studying the links of molecular mimicry in the development of autoimmunity. In the current pandemic, several reports have confirmed an influence of SARS-CoV-2 on subsequent autoimmunity. Bioinformatic and experimental evidence support the potential role of molecular mimicry. Peptide dimensional analysis requires more research and will be increasingly important for designing and distributing vaccines and better understanding the role of environmental factors related to autoimmunity.

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.

Activation and pro-inflammatory cytokine production by unswitched memory B cells during SARS-CoV-2 infection

Memory B cells are comprised of unswitched (CD27+IgD+) and switched (CD27+IgD-) subsets. The origin and function of unswitched human memory B cells are debated in the literature, whereas switched memory B cells are primed to respond to recurrent infection. Unswitched memory B cells have been described to be reduced in frequency with severe SARS-CoV2 infection and here we characterize their activation status, BCR functionality, and contribution to virally-induced cytokine production. Analyses of whole blood from healthy individuals, people immunized against SARS-CoV2, and those who have had mild and severe SARS-CoV2 infection, confirm a reduction in the frequency of unswitched memory B cells during severe SARS-CoV2 infection and demonstrate this reduction is associated with increased levels of systemic TNFα. We further document how severe viral infection is associated with an increased frequency of 'IgD+' only memory B cells that correlate with increased IgG autoantibody levels. Unswitched and switched memory B cells from severe SARS-CoV2 infection displayed evidence of heightened activation with a concomitant reduction in the expression of the inhibitory receptor CD72. Functionally, both populations of memory B cells from severe SARS-COV2 infection harbored a signaling-competent BCR that displayed enhanced BCR signaling activity in the unswitched population. Finally, we demonstrate that B cells from mild SARS-CoV2 infection are poised to secrete pro-inflammatory cytokines IL-6 and TNFα. Importantly, unswitched memory B cells were a major producer of IL-6 and switched memory B cells were a major producer of TNFα in response to viral TLR ligands. Together these data indicate that B cells contribute to the inflammatory milieu during viral infection.

Biological mechanisms underpinning the development of long COVID

As COVID-19 evolves from a pandemic to an endemic disease, the already staggering number of people that have been or will be infected with SARS-CoV-2 is only destined to increase, and the majority of humanity will be infected. It is well understood that COVID-19, like many other viral infections, leaves a significant fraction of the infected with prolonged consequences. Continued high number of SARS-CoV-2 infections, viral evolution with escape from post-infection and vaccinal immunity, and reinfections heighten the potential impact of Long COVID. Hence, the impact of COVID-19 on human health will be seen for years to come until more effective vaccines and pharmaceutical treatments become available. To that effect, it is imperative that the mechanisms underlying the clinical manifestations of Long COVID be elucidated. In this article, we provide an in-depth analysis of the evidence on several potential mechanisms of Long COVID and discuss their relevance to its pathogenesis.

Immune complexes as culprits of immunopathology in severe COVID-19

Infection with the pandemic human coronavirus SARS-CoV-2 elicits a respiratory tract disease, termed Coronavirus disease 2019 (COVID-19). While a variable degree of disease-associated symptoms may emerge, severe COVID-19 is commonly associated with respiratory complications such as acute respiratory distress syndrome (ARDS), the necessity for mechanical ventilation or even extracorporeal membrane oxygenation (ECMO). Amongst others, disease outcome depends on age and pre-existing conditions like cardiovascular diseases, metabolic disorders but also age and biological sex. Intriguingly, increasing experimental and clinical evidence suggests that an exacerbated inflammatory response and in particular IgG immune complexes (ICs), significantly contribute to severe and prolonged COVID-19 disease progression. Vast amounts of deposited, unresolved ICs in tissue are capable to initiate an exaggerated Fc gamma receptor (FcγR) mediated signalling cascade which eventually results in common IC-associated organ diseases such as vasculitis, glomerulonephritis and arthritis, comorbidities that have been frequently reported for COVID-19. Moreover and independent of deposited ICs, very recent work identified soluble ICs (sIC) to be also present in the circulation of a majority of severely ill patients, where their systemic abundance correlated with disease severity. Thus, detection of circulating sICs in patients represents a potential marker for critical COVID-19 disease progression. Their detection early after clinical deterioration might become an indicator for the requirement of prompt anti-inflammatory treatment. Here, we review the role of ICs in COVID-19 progression, their possible origins and potential intervention strategies.

Cellular and molecular features of COVID-19 associated ARDS: therapeutic relevance

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection can be asymptomatic or cause a disease (COVID-19) characterized by different levels of severity. The main cause of severe COVID-19 and death is represented by acute (or acute on chronic) respiratory failure and acute respiratory distress syndrome (ARDS), often requiring hospital admission and ventilator support.The molecular pathogenesis of COVID-19-related ARDS (by now termed c-ARDS) is still poorly understood. In this review we will discuss the genetic susceptibility to COVID-19, the pathogenesis and the local and systemic biomarkers correlated with c-ARDS and the therapeutic options that target the cell signalling pathways of c-ARDS.

Decreased protein C activity, lower ADAMTS13 antigen and free protein S levels accompanied by unchanged thrombin generation potential in hospitalized COVID-19 patients

INTRODUCTION

COVID-19 is associated with an increased thromboembolic risk. However, the mechanisms triggering clot formation in those patients remain unknown.

PATIENTS AND METHODS

In 118 adult Caucasian severe but non-critically ill COVID-19 patients (median age 58 years; 73 % men) and 46 controls, we analyzed in vitro plasma thrombin generation profile (calibrated automated thrombogram [CAT assay]) and investigated thrombophilia-related factors, such as protein C and antithrombin activity, free protein S level, presence of antiphospholipid antibodies and factor V Leiden R506Q and prothrombin G20210A mutations. We also measured circulating von Willebrand factor (vWF) antigen and a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) antigen and activity. In patients, blood samples were collected on admission to the hospital before starting any therapy, including heparin. Finally, we examined the relationship between observed alterations and disease follow-up, such as thromboembolic complications.

RESULTS

COVID-19 patients showed 17 % lower protein C activity, 22 % decreased free protein S levels, and a higher prevalence of positive results for IgM anticardiolipin antibodies. They also had 151 % increased vWF, and 27 % decreased ADAMTS13 antigens compared with controls (p < 0.001, all). On the contrary, thrombin generation potential was similar to controls. In the follow-up, pulmonary embolism (PE) occurred in thirteen (11 %) patients. They were characterized by a 55 % elevated D-dimer (p = 0.04) and 2.7-fold higher troponin I (p = 0.002) during hospitalization and 29 % shorter time to thrombin peak in CAT assay (p = 0.009) compared to patients without PE.

CONCLUSIONS

In COVID-19, we documented prothrombotic abnormalities of peripheral blood. PE was characterized by more dynamic thrombin generation growth in CAT assay performed on admittance to the hospital.

Risk factors for persistent positive anticardiolipin antibodies in women with recurrent pregnancy loss

Antiphospholipid syndrome (APS) is an established cause of recurrent pregnancy loss (RPL). It is necessary to detect persistently positive antiphospholipid antibodies to diagnose APS. This study aimed to explore risk factors for persistent anticardiolipin (aCL) positivity. Women with a history of RPL or with a history of one or more intrauterine fetal deaths after 10 weeks underwent examinations to determine the causes of RPL, including antiphospholipid antibodies. If aCL-IgG or aCL-IgM antibodies were positive, retests were performed at least 12 weeks apart. Risk factors for persistent aCL antibody positivity were retrospectively investigated. The number and percentage of cases above the 99th percentile were 74/2399 (3.1%) for aCL-IgG, and 81/2399 (3.5%) for aCL-IgM. Of the initially tested cases, 2.3% (56/2399) for aCL-IgG and 2.0% (46/2289) for aCL-IgM were ultimately positive above the 99th percentile in retests. Retest values after 12 weeks were significantly lower than the initial values for both IgG and IgM immunoglobulin classes. Initial aCL antibody titers were significantly higher in the persistent-positive group than in the transient-positive group for both IgG and IgM immunoglobulin classes. The cut-off values for predicting persistent positivity of aCL-IgG antibodies and aCL-IgM antibodies were 15 U/mL (99.1 percentile) and 11 U/mL (99.2 percentile), respectively. The only risk factor for persistently positive aCL antibodies is a high antibody titer during the initial test. When the aCL antibody titer in the initial test exceeds the cut-off value, therapeutic strategies can be defined in subsequent pregnancies without waiting for 12 weeks.

Antiphospholipid syndrome: advances in diagnosis, pathogenesis, and management

Antiphospholipid syndrome (APS) is a thrombo-inflammatory disease propelled by circulating autoantibodies that recognize cell surface phospholipids and phospholipid binding proteins. The result is an increased risk of thrombotic events, pregnancy morbidity, and various other autoimmune and inflammatory complications. Although antiphospholipid syndrome was first recognized in patients with lupus, the stand alone presentation of antiphospholipid syndrome is at least equally common. Overall, the diagnosis appears to affect at least one in 2000 people. Studies of antiphospholipid syndrome pathogenesis have long focused on logical candidates such as coagulation factors, endothelial cells, and platelets. Recent work has shed light on additional potential therapeutic targets within the innate immune system, including the complement system and neutrophil extracellular traps. Vitamin K antagonists remain the mainstay of treatment for most patients with thrombotic antiphospholipid syndrome and, based on current data, appear superior to the more targeted direct oral anticoagulants. The potential role of immunomodulatory treatments in antiphospholipid syndrome management is receiving increased attention. As for many systemic autoimmune diseases, the most important future direction is to more precisely identify mechanistic drivers of disease heterogeneity in pursuit of unlocking personalized and proactive treatments for patients.

COVID-19: A trigger of autoimmune diseases

The SARS-coronavirus-2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19), has spread worldwide and caused a global health emergency. SARS-CoV-2 is a coronaviridae virus that infects target cells by interacting with the plasma membrane-expressed angiotensin-converting enzyme 2 (ACE2) via the S1 component of the S protein. Effective host immune response to SARS-CoV-2 infection, which includes both innate and adaptive immunity, is critical for virus management and elimination. The intensity and outcome of COVID-19 may be related to an overabundance of pro-inflammatory cytokines, which results in a "cytokine storm" and acute respiratory distress syndrome. After SARS-CoV-2 infection, the immune system's hyperactivity and production of autoantibodies may result in autoimmune diseases such as autoimmune hemolytic anemia, autoimmune thrombocytopenia, Guillain-Barré syndrome, vasculitis, multiple sclerosis, pro-thrombotic state, and diffuse coagulopathy, as well as certain autoinflammatory conditions such as Kawasaki disease in children. We have reviewed the association between COVID-19 and autoimmune disorders in this article.

Advanced Imaging Supports the Mechanistic Role of Autoimmunity and Plaque Rupture in COVID-19 Heart Involvement

The cardiovascular system is frequently affected by coronavirus disease-19 (COVID-19), particularly in hospitalized cases, and these manifestations are associated with a worse prognosis. Most commonly, heart involvement is represented by myocarditis, myocardial infarction, and pulmonary embolism, while arrhythmias, heart valve damage, and pericarditis are less frequent. While the clinical suspicion is necessary for a prompt disease recognition, imaging allows the early detection of cardiovascular complications in patients with COVID-19. The combination of cardiothoracic approaches has been proposed for advanced imaging techniques, i.e., CT scan and MRI, for a simultaneous evaluation of cardiovascular structures, pulmonary arteries, and lung parenchyma. Several mechanisms have been proposed to explain the cardiovascular injury, and among these, it is established that the host immune system is responsible for the aberrant response characterizing severe COVID-19 and inducing organ-specific injury. We illustrate novel evidence to support the hypothesis that molecular mimicry may be the immunological mechanism for myocarditis in COVID-19. The present article provides a comprehensive review of the available evidence of the immune mechanisms of the COVID-19 cardiovascular injury and the imaging tools to be used in the diagnostic workup. As some of these techniques cannot be implemented for general screening of all cases, we critically discuss the need to maximize the sustainability and the specificity of the proposed tests while illustrating the findings of some paradigmatic cases.

[Importance of autoimmunity induced by SARS-CoV-2 and development of post-vaccination autoimmune diseases]

SARS-CoV-2, a virus belonging to the large family of coronavirus, aroused great interest following the outbreak of this new strain reported in 2019, in Wuhan China. Its clinical spectrum is highly variable, ranging from a self-limited disease to an acute respiratory distress syndrome with systemic clinical manifestations (COVID-19), in which the immune system plays a key role in the pathophysiology of this disease and in its severity; several studies show the prevalence of some autoimmune markers suggesting that they may lead to autoimmune states. The most important strategy worldwide to protect the population was the development of vaccines to induce immunity to severe COVID-19; however, vaccines have also been shown to have the ability to produce autoimmune states in a small percentage of the world's population; nevertheless, the best strategy remains vaccination. The aim of this review is to show the current overview of the mechanisms of SARS-CoV-2-induced autoimmunity and post-vaccination for a better understanding and identification of these in the population. Publications from 2019 to 2022 were reviewed in PubMed as the primary search source.

Outcomes associated with antiphospholipid antibodies in COVID-19: A prospective cohort study

Background

The significance of antiphospholipid antibodies (aPL) in COVID-19 remains uncertain.

Objectives

We determined whether aPL are associated with COVID-19 and/or thrombosis or adverse outcomes during hospitalization for COVID-19.

Methods

Symptomatic adults tested for SARS-CoV-2 for clinical reasons (March-July 2020) with either ≥1 positive polymerase chain reaction (COVID-19+) or all negative (non-COVID-19) results were recruited to a biobank collecting plasma, clinical data, and outcomes. We tested baseline plasma samples (days 0-7) of all subjects (and day-30 samples in the COVID-19+ subjects, when available) for aPL (anticardiolipin immunoglobulin [Ig]M/IgG, anti-β2-glycoprotein I IgM/IgG, antiphosphatidylserine/prothrombin IgM/IgG, and lupus anticoagulant). We compared the baseline prevalence of aPL between the COVID-19+ and non-COVID-19 subjects. Among hospitalized COVID-19+ subjects, multivariable logistic regression was used to evaluate the association of aPL (and their subtypes) with arterial or venous thromboembolic events, acute kidney injury, intensive care unit admission, mechanical ventilation, and death after adjusting for potential confounders.

Results

At baseline, 123 of 289 (43%) COVID+ subjects had ≥1 aPL versus 116 of 261 (32%) non-COVID-19 subjects (difference, 10%; 95% CI, 3%-18%). Among 89 COVID+ subjects with repeated samples, aPL persisted on day 30 in 15 of 34 (44%) subjects with baseline aPL positivity, and half of those without aPL at baseline developed one or more new aPL. In hospitalized COVID-19 subjects (n = 241), baseline aPL positivity was associated with acute kidney injury (odds ratio [OR], 1.8; 95% CI, 1.1-3.2) and mechanical ventilation (OR, 3.2; 95% CI, 1.5-6.8) but not death (OR, 1.2; 95% CI, 0.6-2.5). In secondary analyses, medium-to-high titers of anticardiolipin IgG (>40) were associated with thromboembolic events (OR, 7.3; 95% CI, 1.8-30.1).

Conclusion

In patients with COVID-19, aPL may help identify an increased risk of thrombosis and other adverse outcomes.

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.

Antiphospholipid antibodies in patients with stroke during COVID-19: A role in the signaling pathway leading to platelet activation

Background

Several viral and bacterial infections, including COVID-19, may lead to both thrombotic and hemorrhagic complications. Previously, it has been demonstrated an "in vitro" pathogenic effect of "antiphospholipid" antibodies (aPLs), which are able to activate a proinflammatory and procoagulant phenotype in monocytes, endothelial cells and platelets. This study analyzed the occurrence of aPL IgG in patients with acute ischemic stroke (AIS) during COVID-19, evaluating the effect of Ig fractions from these patients on signaling and functional activation of platelets.

Materials and methods

Sera from 10 patients with AIS during COVID-19, 10 non-COVID-19 stroke patients, 20 COVID-19 and 30 healthy donors (HD) were analyzed for anti-cardiolipin, anti-β2-GPI, anti-phosphatidylserine/prothrombin and anti-vimentin/CL antibodies by ELISA. Platelets from healthy donors were incubated with Ig fractions from these patients or with polyclonal anti-β2-GPI IgG and analyzed for phospho-ERK and phospho-p38 by western blot. Platelet secretion by ATP release dosage was also evaluated.

Results

We demonstrated the presence of aPLs IgG in sera of patients with AIS during COVID-19. Treatment with the Ig fractions from these patients or with polyclonal anti-β2-GPI IgG induced a significant increase of phospho-ERK and phospho-p38 expression. In the same vein, platelet activation was supported by the increase of adenyl nucleotides release induced by Ig fractions.

Conclusions

This study demonstrates the presence of aPLs in a subgroup of COVID-19 patients who presented AIS, suggesting a role in the mechanisms contributing to hypercoagulable state in these patients. Detecting these antibodies as a serological marker to check and monitor COVID-19 may contribute to improve the risk stratification of thromboembolic manifestations in these patients.

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.

An update on angiotensin-converting enzyme 2 structure/functions, polymorphism, and duplicitous nature in the pathophysiology of coronavirus disease 2019: Implications for vascular and coagulation disease associated with severe acute respiratory syndrome coronavirus infection

It has been known for many years that the angiotensin-converting enzyme 2 (ACE2) is a cell surface enzyme involved in the regulation of blood pressure. More recently, it was proven that the severe acute respiratory syndrome coronavirus (SARS-CoV-2) interacts with ACE2 to enter susceptible human cells. This functional duality of ACE2 tends to explain why this molecule plays such an important role in the clinical manifestations of coronavirus disease 2019 (COVID-19). At the very start of the pandemic, a publication from our Institute (entitled "ACE2 receptor polymorphism: susceptibility to SARS-CoV-2, hypertension, multi-organ failure, and COVID-19 disease outcome"), was one of the first reviews linking COVID-19 to the duplicitous nature of ACE2. However, even given that COVID-19 pathophysiology may be driven by an imbalance in the renin-angiotensin system (RAS), we were still far from understanding the complexity of the mechanisms which are controlled by ACE2 in different cell types. To gain insight into the physiopathology of SARS-CoV-2 infection, it is essential to consider the polymorphism and expression levels of the ACE2 gene (including its alternative isoforms). Over the past 2 years, an impressive amount of new results have come to shed light on the role of ACE2 in the pathophysiology of COVID-19, requiring us to update our analysis. Genetic linkage studies have been reported that highlight a relationship between ACE2 genetic variants and the risk of developing hypertension. Currently, many research efforts are being undertaken to understand the links between ACE2 polymorphism and the severity of COVID-19. In this review, we update the state of knowledge on the polymorphism of ACE2 and its consequences on the susceptibility of individuals to SARS-CoV-2. We also discuss the link between the increase of angiotensin II levels among SARS-CoV-2-infected patients and the development of a cytokine storm associated microvascular injury and obstructive thrombo-inflammatory syndrome, which represent the primary causes of severe forms of COVID-19 and lethality. Finally, we summarize the therapeutic strategies aimed at preventing the severe forms of COVID-19 that target ACE2. Changing paradigms may help improve patients' therapy.

Evaluation of the Association between Antiphospholipid Antibodies and ICU Admission Outcome in Critically Ill COVID-19 Patients in Iranian Population

Background

The role of anti-phospholipid antibodies (aPLs) in the prognosis of COVID-19 patients is controversial. In order to prove the role of this factor, the necessary measures such as early initiation of anticoagulants should be started even in the early stages of the disease and in outpatients or the use of other drugs in addition to anticoagulants. We decided to investigate the role of these antibodies in ICU admission outcomes in critically ill COVID-19 patients.

Methods

The case-control study was carried out in Isfahan, Iran, from March to September 2021. One hundred nine patients in the case group were selected, including patients admitted to the ICU with a COVID-19 diagnosis. The 140 patients in the control group were selected from hospitalized and outpatients with COVID-19 with PCR + and pulmonary involvement, similar to the case group without the need for ICU hospitalization. The anti B2GP1 (IgM, IgG) and anti-cardiolipin (IgM, IgG)) were compared in two groups.

Results

The frequency percentage of patients in the abnormal group of anti-phospholipid antibodies was about 10% in total. No statistically significant difference in these aPLs in continued measures was observed between the two groups of patients admitted to the ICU and those outside the ICU. Also, in the logistics regression analysis, no significant association was observed.

Conclusions

Therefore, the cause of coagulation in patients admitted to the ICU is not related to these aPLs. This means that aPLs could not be a good predictor of patient admission to the ICU.

Unique hepatic manifestations of COVID-19-induced immune dysregulation in children

The two cases we present are the first to demonstrate novel manifestations of COVID-19 related interaction between the liver and the immune system in pediatric patients. Written informed consent was obtained from the parent/guardian to publish this report in accordance with the journal's patient consent policy.

Prevalence and coagulation correlation of anticardiolipin antibodies in patients with COVID-19

We aimed to determine prevalence and characteristics of anticardiolipin antibodies (ACLs) and its correlations with laboratory coagulation variables in patients with coronavirus disease 2019 (COVID-19). We retrospectively analyzed the prevalence of serum ACLs and its correlation with coagulative laboratory variables in 87 patients with COVID-19. ACLs were detected in 13/21 (61.91%) critically ill patients, and 21/66 (31.82%) in non-critically ill patients. For ACLs, IgA, and IgG were the most common types. The prevalence of IgG in critical ill patients was much higher than that in non-critical patients with odd ratio = 2.721. And the levels of all isotypes of ACLs in critically ill patients were much higher than those in non-critically ill patients. Correlation analysis showed that activated partial thromboplastin time and thrombin time had weak correlation with ACLs-IgG (R = 0.308, P = .031; R = 0.337, P = .018, respectively). Only the prevalence of ACLs-IgG shows a significant difference when compared critically ill patients with non-critically ill patients. ACLs do not seem to have a clear correlation with thrombosis occurred in COVID-19 patients.

Lupus anticoagulant-hypoprothrombinemia syndrome with severe bleeding diathesis after coronavirus disease 2019: a case report

Acquired antibodies against factor II (prothrombin) are rare and most commonly associated with severe liver disease or vitamin K antagonist treatment. In very rare cases, these antibodies and associated hypoprothrombinemia are found in patients with lupus anticoagulant (LAC), an antiphospholipid antibody that inhibits phospholipid-dependent coagulation tests. This uncommon entity, called lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS), may cause both severe, life-threatening bleeding and a predisposition to thrombosis. Coronavirus disease 2019 (COVID-19) is associated with a variety of coagulation abnormalities and an increased risk of thrombosis. Bleeding may occur, but it is less common than thromboembolism and has mostly been described in association with the severity of the disease and anticoagulation treatment in hospitalized patients, rarely in the post-acute phase of the disease. We report on a case of an 80-year-old man who developed LAHPS with prothrombin antibodies and severe bleeding after COVID-19.

Central Retinal Vein Occlusion Presumably Associated with Lupus Anticoagulant Induced by SARSCoV-2

PURPOSE

To report a case of unilateral central retinal vein occlusion (CRVO) and macular edema presumably associated with lupus anticoagulant (LA) induced by severe acute respiratory syndrome coronavirus 2 (SARS CoV-2).

METHOD

Case report.

RESULTS

A 32-year-old male patient presented to the emergency department with a 5-day history of blurry vision. He was diagnosed with a CRVO and macular edema. The only pathological finding was positive LA which could have been induced by his recent confirmed SARS CoV-2 infection. The patient's evolution was satisfactory after two injections of Intravitreal dexamethasone (Ozurdex®), with improvement in macular edema and visual acuity.

CONCLUSION

COVID-19 may be associated to retinal vascular occlusive disorders. Transient virus-induced LA might play a role in the pathogenesis of the thrombotic event.

Complementary Sets of Autoantibodies Induced by SARS-CoV-2, Adenovirus and Bacterial Antigens Cross-React with Human Blood Protein Antigens in COVID-19 Coagulopathies

COVID-19 patients often develop coagulopathies including microclotting, thrombotic strokes or thrombocytopenia. Autoantibodies are present against blood-related proteins including cardiolipin (CL), serum albumin (SA), platelet factor 4 (PF4), beta 2 glycoprotein 1 (β2GPI), phosphodiesterases (PDE), and coagulation factors such as Factor II, IX, X and von Willebrand factor (vWF). Different combinations of autoantibodies associate with different coagulopathies. Previous research revealed similarities between proteins with blood clotting functions and SARS-CoV-2 proteins, adenovirus, and bacterial proteins associated with moderate-to-severe COVID-19 infections. This study investigated whether polyclonal antibodies (mainly goat and rabbit) against these viruses and bacteria recognize human blood-related proteins. Antibodies against SARS-CoV-2 and adenovirus recognized vWF, PDE and PF4 and SARS-CoV-2 antibodies also recognized additional antigens. Most bacterial antibodies tested (group A streptococci [GAS], staphylococci, Escherichia coli [E. coli], Klebsiella pneumoniae, Clostridia, and Mycobacterium tuberculosis) cross-reacted with CL and PF4. while GAS antibodies also bound to F2, Factor VIII, Factor IX, and vWF, and E. coli antibodies to PDE. All cross-reactive interactions involved antibody-antigen binding constants smaller than 100 nM. Since most COVID-19 coagulopathy patients display autoantibodies against vWF, PDE and PF4 along with CL, combinations of viral and bacterial infections appear to be necessary to initiate their autoimmune coagulopathies.

Autoantibodies elicited with SARS-CoV-2 infection are linked to alterations in double negative B cells

Double negative (DN) B cells (CD27-IgD-) comprise a heterogenous population of DN1, DN2, and the recently described DN3 and DN4 subsets. In autoimmune disease, DN2 cells are reported to be precursors to autoreactive antibody secreting cells and expansion of DN2 cells is linked to elevated interferon levels. Severe SARS-CoV-2 infection is characterized by elevated systemic levels of pro-inflammatory cytokines and serum autoantibodies and expansion of the DN2 subset in severe SARS-CoV-2 infection has been reported. However, the activation status, functional capacity and contribution to virally-induced autoantibody production by DN subsets is not established. Here, we validate the finding that severe SARS-CoV-2 infection is associated with a reduction in the frequency of DN1 cells coinciding with an increase in the frequency of DN2 and DN3 cells. We further demonstrate that with severe viral infection DN subsets are at a heightened level of activation, display changes in immunoglobulin class isotype frequency and have functional BCR signaling. Increases in overall systemic inflammation (CRP), as well as specific pro-inflammatory cytokines (TNFα, IL-6, IFNγ, IL-1β), significantly correlate with the skewing of DN1, DN2 and DN3 subsets during severe SARS-CoV-2 infection. Importantly, the reduction in DN1 cell frequency and expansion of the DN3 population during severe infection significantly correlates with increased levels of serum autoantibodies. Thus, systemic inflammation during SARS-CoV-2 infection drives changes in Double Negative subset frequency, likely impacting their contribution to generation of autoreactive antibodies.

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.

Management of acute aortoiliac arterial thrombosis in patients with the novel coronavirus disease 2019: A case series and systematic review of the literature

Objectives

Venous thrombosis has been widely described in the setting of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; however, arterial thrombosis has rarely been reported. This study aims to assess the incidence, risk factors, interventions, and outcomes of acute aortoiliac arterial thrombosis in patients with active SARS-CoV-2 infections.

Methods

We present seven SARS-CoV-2-positive patients from our institution who acutely developed thrombi in the aortoiliac arterial system (7/2020-1/2021). A systematic review of the literature on aortoiliac arterial thrombosis in patients with SARS-CoV-2 infections in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was also performed. The available data from all reported cases in the literature and at our institution were analyzed.

Results

Thirty published articles and journal correspondences, including 52 patients, were reviewed and analyzed in addition to our institution's 7 cases. In total, 59 SARS-CoV-2-positive patients were found to have acute aortoiliac thrombosis. The abdominal aorta was the most frequent location for the development of a thrombus. Baseline demographics and medical comorbidities were not significantly different between the symptomatic and asymptomatic cohorts. Seventy-one percent of patients were symptomatic (lower limb ischemia: 75.0%, renal infarction: 20.0%, stroke: 12.5%, mesenteric ischemia: 10.0%). All patients with thrombus involving the ascending aorta, aortic bifurcation, or iliac artery developed thromboembolic or ischemic complications. All patients received systemic anticoagulation. Fifty-three percent of all patients were managed medically. Ninety-four percent of the asymptomatic patients were managed medically. One asymptomatic patient underwent endovascular aspiration of a mobile thrombus. Three (23.1%) deaths occurred in the asymptomatic cohort from hypoxic respiratory failure. Fourteen (36.8%) deaths occurred in the symptomatic cohort. The in-hospital mortality rate was 33.3% overall and 43.8% for patients with thrombi involving more than one aortoiliac segment.

Conclusions

The presence of thrombi in the aortoiliac arterial system appears to be a poor prognostic indicator for patients with active SARS-CoV-2 infections. Medical management of patients with asymptomatic aortoiliac thrombi may be considered. The presence of thrombi involving the ascending aorta, aortic bifurcation, or iliac artery may warrant consideration for operative intervention due to the risk for thromboembolic or ischemic complications. Further study is needed to fully delineate the risk factors, optimal treatment, and outcomes of arterial thrombosis in the setting of SARS-CoV-2 infection.

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.