Novel and unique rheumatoid factors cross-react with viral epitopes in COVID-19.

Rheumatoid factors (RFs), polyreactive antibodies canonically known to bind two conformational epitopes of IgG Fc, are a hallmark of rheumatoid arthritis but also can arise in other inflammatory conditions and infections. Also, infections may contribute to the development of rheumatoid arthritis and other autoimmune diseases. Recently, RFs only in rheumatoid arthritis were found to bind novel linear IgG epitopes as well as thousands of other rheumatoid arthritis autoantigens. Specific epitopes recognized by infection-induced polyreactive RFs remain undefined but could provide insights into loss of immune tolerance. Here, we identified novel linear IgG epitopes bound by RFs in COVID-19 but not rheumatoid arthritis or other conditions. The main COVID-19 RF was polyreactive, binding two IgG and multiple viral peptides with a tripeptide motif, as well as IgG Fc and SARS-CoV-2 spike proteins. In contrast, a rheumatoid arthritis-specific RF recognized IgG Fc, but not tripeptide motif-containing peptides or spike. Thus, RFs have disease-specific IgG reactivity and distinct polyreactivities that reflect the broader immune response. Moreover, the polyreactivity of a virus-induced RF appears to be attributable to a very short peptide motif. These findings refine our understanding of RFs and provide new insights into how viral infections may contribute to autoimmunity.

The landscape of antibody binding in SARS-CoV-2 infection.

The search for potential antibody-based diagnostics, vaccines, and therapeutics for pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has focused almost exclusively on the spike (S) and nucleocapsid (N) proteins. Coronavirus membrane (M), ORF3a, and ORF8 proteins are humoral immunogens in other coronaviruses (CoVs) but remain largely uninvestigated for SARS-CoV-2. Here, we use ultradense peptide microarray mapping to show that SARS-CoV-2 infection induces robust antibody responses to epitopes throughout the SARS-CoV-2 proteome, particularly in M, in which 1 epitope achieved excellent diagnostic accuracy. We map 79 B cell epitopes throughout the SARS-CoV-2 proteome and demonstrate that antibodies that develop in response to SARS-CoV-2 infection bind homologous peptide sequences in the 6 other known human CoVs. We also confirm reactivity against 4 of our top-ranking epitopes by enzyme-linked immunosorbent assay (ELISA). Illness severity correlated with increased reactivity to 9 SARS-CoV-2 epitopes in S, M, N, and ORF3a in our population. Our results demonstrate previously unknown, highly reactive B cell epitopes throughout the full proteome of SARS-CoV-2 and other CoV proteins.

Zoom Improv is accessible and enhances medical student empathy.

BACKGROUND: Empathy declines during medical training, despite its importance. METHODOLOGY: In this randomized controlled trial, we assessed the impact of Zoom improv on medical student empathy using a concurrent mixed-methods approach. Quantitative assessment with three survey tools and qualitative assessment by content analysis of Zoom session field notes were conducted. RESULTS: Zoom improv participants had higher empathy scores in perspective-taking and fantasy and lower scores in personal distress compared with the control group. Medical students who participated in Zoom improv exercised emotional expression, active listening, and giving "gifts," which apply to healthcare settings in which affirming team members with empathic concern can advance communication, patient rapport, and teamwork. DISCUSSION: This pilot study highlights promising findings for the incorporation of Zoom improv in medical education, including enhanced empathy, self-reflection, and understanding how these skills impact work in healthcare. Future studies may expand on the optimal timing to teach improv. Future studies conducted on virtual platforms may also further investigate our finding that the fantasy domain of empathy increases after Zoom improv sessions, whereas this increase in fantasy was absent from previous in-person studies. Given the increase in telehealth and virtual medical visits, exercising empathy skills through a screen during training may be an important addition to medical curricula.

Anti-membrane Antibodies Persist at Least One Year and Discriminate Between Past Coronavirus Disease 2019 Infection and Vaccination.

BACKGROUND: The consequences of past coronavirus disease 2019 (COVID-19) infection for personal and population health are emerging, but accurately identifying distant infection is a challenge. Anti-spike antibodies rise after both vaccination and infection and anti-nucleocapsid antibodies rapidly decline. METHODS: We evaluated anti-membrane antibodies in COVID-19 naive, vaccinated, and convalescent subjects to determine if they persist and accurately detect distant infection. RESULTS: We found that anti-membrane antibodies persist for at least 1 year and are a sensitive and specific marker of past COVID-19 infection. CONCLUSIONS: Thus, anti-membrane and anti-spike antibodies together can differentiate between COVID-19 convalescent, vaccinated, and naive states to advance public health and research.

Limited Biomarker Potential for IgG Autoantibodies Reactive to Linear Epitopes in Systemic Lupus Erythematosus or Spondyloarthropathy.

BACKGROUND: Autoantibodies are commonly used as biomarkers in autoimmune diseases, but there are limitations. For example, autoantibody biomarkers have poor sensitivity or specificity in systemic lupus erythematosus and do not exist in the spondyloarthropathies, impairing diagnosis and treatment. While autoantibodies suitable for strong biomarkers may not exist in these conditions, another possibility is that technology has limited their discovery. The purpose of this study was to use a novel high-density peptide array that enables the evaluation of IgG binding to every possible linear antigen in the entire human peptidome, as well as a novel machine learning approach that incorporates ELISA validation predictability in order to discover autoantibodies that could be developed into sensitive and specific markers of lupus or spondyloarthropathy. METHODS: We used a peptide array containing the human peptidome, several viral peptidomes, and key post-translational modifications (6 million peptides) to quantify IgG binding in lupus, spondyloarthropathy, rheumatoid arthritis, Sjögren's disease, and control sera. Using ELISA data for 70 peptides, we performed a random forest analysis that evaluated multiple array features to predict which peptides might be good biomarkers, as confirmed by ELISA. We validated the peptide prediction methodology in rheumatoid arthritis and COVID-19, conditions for which the antibody repertoire is well-understood, and then evaluated IgG binding by ELISA to peptides that we predicted would be highly bound specifically in lupus or spondyloarthropathy. RESULTS: Our methodology performed well in validation studies, but peptides predicted to be highly and specifically bound in lupus or spondyloarthropathy could not be confirmed by ELISA. CONCLUSIONS: In a comprehensive evaluation of the entire human peptidome, highly sensitive and specific IgG autoantibodies were not identified in lupus or spondyloarthropathy. Thus, the pathogenesis of lupus and spondyloarthropathy may not depend upon unique autoantigens, and other types of molecules should be sought as optimal biomarkers in these conditions.

Rheumatoid Factor and Anti-Modified Protein Antibody Reactivities Converge on IgG Epitopes.

OBJECTIVE: Rheumatoid arthritis (RA) patients often develop rheumatoid factors (RFs), antibodies that bind IgG Fc, and anti-modified protein antibodies (AMPAs), multireactive autoantibodies that commonly bind citrullinated, homocitrullinated, and acetylated antigens. Recently, antibodies that bind citrulline-containing IgG epitopes were discovered in RA, suggesting that additional undiscovered IgG epitopes could exist and that IgG could be a shared antigen for RFs and AMPAs. This study was undertaken to reveal new IgG epitopes in rheumatic disease and to determine if multireactive AMPAs bind IgG. METHODS: Using sera from patients with RA, systemic lupus erythematosus, Sjögren's disease (SjD), or spondyloarthropathy, IgG binding to native, citrulline-containing, and homocitrulline-containing linear epitopes of the IgG constant region was evaluated by peptide array, with highly bound epitopes further evaluated by enzyme-linked immunosorbent assay (ELISA). Binding of monoclonal AMPAs to IgG-derived peptides and IgG Fc was also evaluated by ELISA. RESULTS: Seropositive RA sera showed high IgG binding to multiple citrulline- and homocitrulline-containing IgG-derived peptides, whereas anti-SSA+ sera from SjD patients showed consistent binding to a single linear native epitope of IgG in the hinge region. Monoclonal AMPAs bound citrulline- and homocitrulline-containing IgG peptides and modified IgG Fc. CONCLUSION: The repertoire of epitopes bound by AMPAs includes modified IgG epitopes, positioning IgG as a common antigen that connects the otherwise divergent reactivities of RFs and AMPAs.

Neutrophil-derived extracellular vesicles modulate the phenotype of naïve human neutrophils.

Neutrophils (PMN) regulate inflammation in many ways, including communication with other immune cells via extracellular vesicles (EVs). EVs released by human neutrophils activated with N-formylmethionyl-leucyl-phenylalanine (fMLF) (PMN-fMLF EVs) had an outside-out orientation and contained functionally important neutrophil plasma membrane proteins, including flavocytochrome b558, and enzymatically active granule proteins, elastase, and myeloperoxidase. Treatment of naïve PMN with PMN-fMLF EVs primed fMLF-stimulated NADPH oxidase activity, increased surface expression of the complement receptors CD11b/CD18 and CD35, the specific granule membrane protein CD66, and flavocytochrome b558 , and promoted phagocytosis of serum-opsonized Staphylococcus aureus. The primed oxidase activity reflected increased surface expression of flavocytochrome b558 and phosphorylation of SER345 in p47phox , two recognized mechanisms for oxidase priming. Taken together, these data demonstrate that stimulated PMN released EVs that altered the phenotype of naïve phagocytes by priming of the NADPH oxidase activity and augmenting phagocytosis, two responses that are integral to optimal PMN host defense.

The landscape of antibody binding in SARS-CoV-2 infection.

The search for potential antibody-based diagnostics, vaccines, and therapeutics for pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has focused almost exclusively on the spike (S) and nucleocapsid (N) proteins. Coronavirus membrane (M), ORF3a, and ORF8 proteins are humoral immunogens in other coronaviruses (CoVs) but remain largely uninvestigated for SARS-CoV-2. Here we use ultradense peptide microarray mapping to show that SARS-CoV-2 infection induces robust antibody responses to epitopes throughout the SARS-CoV-2 proteome, particularly in M, in which one epitope achieved excellent diagnostic accuracy. We map 79 B cell epitopes throughout the SARS-CoV-2 proteome and demonstrate that antibodies that develop in response to SARS-CoV-2 infection bind homologous peptide sequences in the six other known human CoVs. We also confirm reactivity against four of our top-ranking epitopes by enzyme-linked immunosorbent assay (ELISA). Illness severity correlated with increased reactivity to nine SARS-CoV-2 epitopes in S, M, N, and ORF3a in our population. Our results demonstrate previously unknown, highly reactive B cell epitopes throughout the full proteome of SARS-CoV-2 and other CoV proteins.

Anti-membrane and anti-spike antibodies are long-lasting and together discriminate between past COVID-19 infection and vaccination.

The consequences of past COVID-19 infection for personal health and long-term population immunity are only starting to be revealed. Unfortunately, detecting past infection is currently a challenge, limiting clinical and research endeavors. Widely available anti-SARS-CoV-2 antibody tests cannot differentiate between past infection and vaccination given vaccine-induced anti-spike antibodies and the rapid loss of infection-induced anti-nucleocapsid antibodies. Anti-membrane antibodies develop after COVID-19, but their long-term persistence is unknown. Here, we demonstrate that anti-membrane IgG is a sensitive and specific marker of past COVID-19 infection and persists at least one year. We also confirm that anti-receptor binding domain (RBD) Ig is a long-lasting, sensitive, and specific marker of past infection and vaccination, while anti-nucleocapsid IgG lacks specificity and quickly declines after COVID-19. Thus, a combination of anti-membrane and anti-RBD antibodies can accurately differentiate between distant COVID-19 infection, vaccination, and naïve states to advance public health, individual healthcare, and research goals.

Specific COVID-19 Symptoms Correlate with High Antibody Levels against SARS-CoV-2.

Lasting immunity will be critical for overcoming COVID-19. However, the factors associated with the development of high titers of anti-SARS-CoV-2 Abs and how long those Abs persist remain incompletely defined. In particular, an understanding of the relationship between COVID-19 symptoms and anti-SARS-CoV-2 Abs is limited. To address these unknowns, we quantified serum anti-SARS- CoV-2 Abs in clinically diverse COVID-19 convalescent human subjects 5 wk (n = 113) and 3 mo (n = 79) after symptom resolution with three methods: a novel multiplex assay to quantify IgG against four SARS-CoV-2 Ags, a new SARS-CoV-2 receptor binding domain-angiotensin converting enzyme 2 inhibition assay, and a SARS-CoV-2 neutralizing assay. We then identified clinical and demographic factors, including never-before-assessed COVID-19 symptoms, that consistently correlate with high anti-SARS-CoV-2 Ab levels. We detected anti-SARS-CoV-2 Abs in 98% of COVID-19 convalescent subjects 5 wk after symptom resolution, and Ab levels did not decline at 3 mo. Greater disease severity, older age, male sex, higher body mass index, and higher Charlson Comorbidity Index score correlated with increased anti-SARS-CoV-2 Ab levels. Moreover, we report for the first time (to our knowledge) that COVID-19 symptoms, most consistently fever, body aches, and low appetite, correlate with higher anti-SARS-CoV-2 Ab levels. Our results provide robust and new insights into the development and persistence of anti-SARS-CoV-2 Abs.

Fever, Diarrhea, and Severe Disease Correlate with High Persistent Antibody Levels against SARS-CoV-2.

Lasting immunity will be critical for overcoming the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, factors that drive the development of high titers of anti-SARS-CoV-2 antibodies and how long those antibodies persist remain unclear. Our objective was to comprehensively evaluate anti-SARS-CoV-2 antibodies in a clinically diverse COVID-19 convalescent cohort at defined time points to determine if anti-SARS-CoV-2 antibodies persist and to identify clinical and demographic factors that correlate with high titers. Using a novel multiplex assay to quantify IgG against four SARS-CoV-2 antigens, a receptor binding domain-angiotensin converting enzyme 2 inhibition assay, and a SARS-CoV-2 neutralization assay, we found that 98% of COVID-19 convalescent subjects had anti-SARS-CoV-2 antibodies five weeks after symptom resolution (n=113). Further, antibody levels did not decline three months after symptom resolution (n=79). As expected, greater disease severity, older age, male sex, obesity, and higher Charlson Comorbidity Index score correlated with increased anti-SARS-CoV-2 antibody levels. We demonstrated for the first time that COVID-19 symptoms, namely fever, abdominal pain, diarrhea and low appetite, correlated consistently with higher anti-SARS-CoV-2 antibody levels. Our results provide new insights into the development and persistence of anti-SARS-CoV-2 antibodies.