Prevalence of Antiphospholipid Antibodies and Association With Incident Cardiovascular Events.

Importance: The prevalence of antiphospholipid antibodies (aPL) and their association with future atherosclerotic cardiovascular disease (ASCVD) risk has yet to be thoroughly investigated. Objective: To determine the association between measurements of aPL at a single time point and ASCVD risk in a diverse population. Design, Setting, and Participants: This cohort study measured 8 aPL (anticardiolipin [aCL] IgG/IgM/IgA, anti-beta-2 glycoprotein I [aß2GPI] IgG/IgM/IgA, and antiphosphatidylserine/prothrombin [aPS/PT] IgG/IgM) by solid-phase assays in plasma from participants of the Dallas Heart Study (DHS) phase 2, a multiethnic, population-based cohort study. Blood samples were collected between 2007 and 2009. The median follow-up was 8 years. Statistical analysis was performed from April 2022 to January 2023. Main Outcomes and Measures: Associations of aPL with future ASCVD events (defined as first nonfatal myocardial infarction, first nonfatal stroke, coronary revascularization, or death from cardiovascular cause) were assessed by Cox proportional hazards models, adjusting for known risk factors, medications, and multiple comparisons. Results: Among the 2427 participants (mean [SD] age, 50.6 [10.3] years; 1399 [57.6%] female; 1244 [51.3%] Black, 339 [14.0%] Hispanic, and 796 [32.8%] White), the prevalence of any positive aPL tested at a single time point was 14.5% (353 of 2427), with approximately one-third of those detected at a moderate or high titer; aCL IgM had the highest prevalence (156 individuals [6.4%]), followed by aPS/PT IgM (88 [3.4%]), aß2GPI IgM (63 [2.6%]), and aß2GPI IgA (62 [2.5%]). The IgA of aCL (adjusted hazard ratio [HR], 4.92; 95% CI, 1.52-15.98) and aß2GPI (HR, 2.91; 95% CI, 1.32-6.41) were independently associated with future ASCVD events. The risk further increased when applying a positivity threshold of at least 40 units (aCL IgA: HR, 9.01 [95% CI, 2.73-29.72]; aß2GPI IgA: HR, 4.09 [95% CI, 1.45-11.54]). Levels of aß2GPI IgA negatively correlated with cholesterol efflux capacity (r = -0.055; P = .009) and positively correlated with circulating oxidized LDL (r = 0.055; P = .007). aß2GPI IgA-positive plasma was associated with an activated endothelial cell phenotype as evidenced by increased surface expression of surface E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1. Conclusions and Relevance: In this population-based cohort study, aPL detectable by solid-phase assays were present in a substantial proportion of adults; positive aCL IgA and aß2GPI IgA at a single time point were independently associated with future ASCVD events. Longitudinal studies with serial aPL measurements are needed to further explore these findings.

Anti-Neutrophil Extracellular Trap Antibodies in Antiphospholipid Antibody-Positive Patients: Results From the Antiphospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking Clinical Database and Repository.

OBJECTIVE: This study aimed to elucidate the presence, antigen specificities, and potential clinical associations of anti-neutrophil extracellular trap (anti-NET) antibodies in a multinational cohort of antiphospholipid (aPL) antibody-positive patients who did not have lupus. METHODS: Anti-NET IgG/IgM levels were measured in serum samples from 389 aPL-positive patients; 308 patients met the classification criteria for antiphospholipid syndrome. Multivariate logistic regression with best variable model selection was used to determine clinical associations. For a subset of the patients (n = 214), we profiled autoantibodies using an autoantigen microarray platform. RESULTS: We found elevated levels of anti-NET IgG and/or IgM in 45% of the aPL-positive patients. High anti-NET antibody levels are associated with more circulating myeloperoxidase (MPO)-DNA complexes, which are a biomarker of NETs. When considering clinical manifestations, positive anti-NET IgG was associated with lesions affecting the white matter of the brain, even after adjusting for demographic variables and aPL profiles. Anti-NET IgM tracked with complement consumption after controlling for aPL profiles; furthermore, patient serum samples containing high levels of anti-NET IgM efficiently deposited complement C3d on NETs. As determined by autoantigen microarray, positive testing for anti-NET IgG was significantly associated with several autoantibodies, including those recognizing citrullinated histones, heparan sulfate proteoglycan, laminin, MPO-DNA complexes, and nucleosomes. Anti-NET IgM positivity was associated with autoantibodies targeting single-stranded DNA, double-stranded DNA, and proliferating cell nuclear antigen. CONCLUSION: These data reveal high levels of anti-NET antibodies in 45% of aPL-positive patients, where they potentially activate the complement cascade. While anti-NET IgM may especially recognize DNA in NETs, anti-NET IgG species appear to be more likely to target NET-associated protein antigens.

Pre-Clinical Autoimmunity in Lupus Relatives: Self-Reported Questionnaires and Immune Dysregulation Distinguish Relatives Who Develop Incomplete or Classified Lupus From Clinically Unaffected Relatives and Unaffected, Unrelated Individuals.

Systemic lupus erythematosus (SLE) is propelled by pathogenic autoantibody (AutoAb) and immune pathway dysregulation. Identifying populations at risk of reaching classified SLE is essential to curtail inflammatory damage. Lupus blood relatives (Rel) have an increased risk of developing SLE. We tested factors to identify Rel at risk of developing incomplete lupus (ILE) or classified SLE vs. clinically unaffected Rel and healthy controls (HC), drawing from two unique, well characterized lupus cohorts, the lupus autoimmunity in relatives (LAUREL) follow-up cohort, consisting of Rel meeting <4 ACR criteria at baseline, and the Lupus Family Registry and Repository (LFRR), made up of SLE patients, lupus Rel, and HC. Medical record review determined ACR SLE classification criteria; study participants completed the SLE portion of the connective tissue disease questionnaire (SLE-CSQ), type 2 symptom questions, and provided samples for assessment of serum SLE-associated AutoAb specificities and 52 plasma immune mediators. Elevated SLE-CSQ scores were associated with type 2 symptoms, ACR scores, and serology in both cohorts. Fatigue at BL was associated with transition to classified SLE in the LAUREL cohort (p≤0.01). Increased levels of BLyS and decreased levels of IL-10 were associated with type 2 symptoms (p<0.05). SLE-CSQ scores, ACR scores, and accumulated AutoAb specificities correlated with levels of multiple inflammatory immune mediators (p<0.05), including BLyS, IL-2Rα, stem cell factor (SCF), soluble TNF receptors, and Th-1 type mediators and chemokines. Transition to SLE was associated with increased levels of SCF (p<0.05). ILE Rel also had increased levels of TNF-α and IFN-γ, offset by increased levels of regulatory IL-10 and TGF-ß (p<0.05). Clinically unaffected Rel (vs. HC) had higher SLE-CSQ scores (p<0.001), increased serology (p<0.05), and increased inflammatory mediator levels, offset by increased IL-10 and TGF-ß (p<0.01). These findings suggest that Rel at highest risk of transitioning to classified SLE have increased inflammation coupled with decreased regulatory mediators. In contrast, clinically unaffected Rel and Rel with ILE demonstrate increased inflammation offset with increased immune regulation, intimating a window of opportunity for early intervention and enrollment in prevention trials.

American College of Rheumatology Clinical Guidance for Multisystem Inflammatory Syndrome in Children Associated With SARS-CoV-2 and Hyperinflammation in Pediatric COVID-19: Version 3.

OBJECTIVE: To provide guidance on the management of Multisystem Inflammatory Syndrome in Children (MIS-C), a condition characterized by fever, inflammation, and multiorgan dysfunction that manifests late in the course of SARS-CoV-2 infection. Recommendations are also provided for children with hyperinflammation during COVID-19, the acute, infectious phase of SARS-CoV-2 infection. METHODS: The Task Force is composed of 9 pediatric rheumatologists and 2 adult rheumatologists, 2 pediatric cardiologists, 2 pediatric infectious disease specialists, and 1 pediatric critical care physician. Preliminary statements addressing clinical questions related to MIS-C and hyperinflammation in COVID-19 were developed based on evidence reports. Consensus was built through a modified Delphi process that involved anonymous voting and webinar discussion. A 9-point scale was used to determine the appropriateness of each statement (median scores of 1-3 for inappropriate, 4-6 for uncertain, and 7-9 for appropriate). Consensus was rated as low, moderate, or high based on dispersion of the votes. Approved guidance statements were those that were classified as appropriate with moderate or high levels of consensus, which were prespecified before voting. RESULTS: The guidance was approved in June 2020 and updated in November 2020 and October 2021, and consists of 41 final guidance statements accompanied by flow diagrams depicting the diagnostic pathway for MIS-C and recommendations for initial immunomodulatory treatment of MIS-C. CONCLUSION: Our understanding of SARS-CoV-2-related syndromes in the pediatric population continues to evolve. This guidance document reflects currently available evidence coupled with expert opinion, and will be revised as further evidence becomes available.

Additional risk factors associated with thrombosis and pregnancy morbidity in a unique cohort of antiphospholipid antibody-positive patients.

BACKGROUND: Antiphospholipid syndrome (APS) is an autoimmune prothrombotic condition with significant morbidity. The objective of this study was to identify additional clinical and epidemiological risks of arterial thrombosis, venous thrombosis, and pregnancy morbidities in a large cohort of persistent antiphospholipid antibodies (aPLs)-positive carriers. METHODS: This was a cross-sectional cohort study of 453 consecutive patients with a documented positive aPL who attended Peking University People's Hospital. Among 453 patients screened, 297 patients had persistent positive aPL. We compared asymptomatic aPL carriers with thrombotic and obstetric APS patients. And the univariate analysis and multivariable logistic regression were used to evaluate the association between different risk factors and APS clinical manifestations. The levels of circulating markers of neutrophil extracellular traps (NETs) (cell-free DNA and citrullinated histone H3 [Cit-H3]) were assessed and compared among aPL-positive carriers with or without autoimmune disease and APS patients. RESULTS: Additional risk factors associated with arterial thrombosis among aPL-positive carriers included: smoking (odds ratio [OR] = 6.137, 95% confidence interval [CI] = 2.408-15.637, P  = 0.0001), hypertension (OR = 2.368, 95% CI = 1.249-4.491, P  = 0.008), and the presence of underlying autoimmune disease (OR = 4.401, 95% CI = 2.387-8.113, P < 0.001). Additional risks associated with venous thrombosis among aPL carriers included: smoking (OR = 4.594, 95% CI = 1.681-12.553, P  = 0.029) and the presence of underlying autoimmune disease (OR = 6.330, 95% CI = 3.355-11.940, P < 0.001). The presence of underlying autoimmune disease (OR = 3.301, 95% CI = 1.407-7.744, P  = 0.006) is the additional risk, which demonstrated a significant association with APS pregnancy morbidity. Higher circulating levels of cell-free DNA and Cit-H3 were observed among APS patients and aPL patients with autoimmune diseases compared with those aPL carriers without underlying autoimmune diseases. Furthermore, control neutrophils that are conditioned with APS patients'sera have more pronounced NET release compared with those treated with aPL carriers'sera without underlying autoimmune diseases. CONCLUSIONS: We identified several potential additional risk factors for APS clinical manifestations among a large cohort of Chinese aPL carriers. Our data may help physicians to risk stratify aPL-positive Asian patients.

American College of Rheumatology Guidance for the Management of Pediatric Rheumatic Disease During the COVID-19 Pandemic: Version 2.

OBJECTIVE: To provide clinical guidance to rheumatology providers who treat children with pediatric rheumatic disease (PRD) in the context of the coronavirus disease 2019 (COVID-19) pandemic. METHODS: The task force, consisting of 7 pediatric rheumatologists, 2 pediatric infectious disease physicians, 1 adult rheumatologist, and 1 pediatric nurse practitioner, was convened on May 21, 2020. Clinical questions and subsequent guidance statements were drafted based on a review of the queries posed by the patients as well as the families and healthcare providers of children with PRD. An evidence report was generated and disseminated to task force members to assist with 3 rounds of asynchronous, anonymous voting by email using a modified Delphi approach. Voting was completed using a 9-point numeric scoring system with predefined levels of agreement (categorized as disagreement, uncertainty, or agreement, with median scores of 1-3, 4-6, and 7-9, respectively) and consensus (categorized as low, moderate, or high). To be approved as a guidance statement, median vote ratings were required to fall into the highest tertile for agreement, with either moderate or high levels of consensus. RESULTS: To date, 39 guidance statements have been approved by the task force. Those with similar recommendations were combined to form a total of 33 final guidance statements, all of which received median vote ratings within the highest tertile of agreement and were associated with either moderate consensus (n = 5) or high consensus (n = 28). CONCLUSION: These guidance statements have been generated based on review of the available literature, indicating that children with PRD do not appear to be at increased risk for susceptibility to SARS-CoV-2 infection. This guidance is presented as a "living document," recognizing that the literature on COVID-19 is rapidly evolving, with future updates anticipated.

Serum IgG Profiling of Toddlers Reveals a Subgroup with Elevated Seropositive Antibodies to Viruses Correlating with Increased Vaccine and Autoantigen Responses.

PURPOSE: The human antibody repertoire forms in response to infections, the microbiome, vaccinations, and environmental exposures. The specificity of such antibody responses was compared among a cohort of toddlers to identify differences between seropositive versus seronegative responses. METHODS: An assessment of the serum IgM and IgG antibody reactivities in 197 toddlers of 1- and 2-years of age was performed with a microfluidic array containing 110 distinct antigens. Longitudinal profiling was done from years 1 to 2. Seropositivity to RNA and DNA viruses; bacteria; live attenuated, inactive, and subunit vaccines; and autoantigens was compared. A stratification was developed based on quantitative variations in the IgG responses. Clinical presentations and previously known genetic risk alleles for various immune system conditions were investigated in relation to IgG responses. RESULTS: IgG reactivities stratified toddlers into low, moderate, and high responder groups. The high group (17%) had elevated IgG responses to multiple RNA and DNA viruses (e.g., respiratory syncytial virus, Epstein-Barr virus, adenovirus, Coxsackievirus) and this correlated with increased responses to live attenuated viral vaccines and certain autoantigens. This high group was more likely to be associated with gestational diabetes and an older age. Genetic analyses identified polymorphisms in the IL2RB, TNFSF4, and INS genes in two high responder individuals that were associated with their elevated cytokine levels and clinical history of eczema and asthma. CONCLUSION: Serum IgG profiling of toddlers reveals correlations between the magnitude of the antibody responses towards viruses, live attenuated vaccines, and certain autoantigens. A low responder group had much weaker responses overall, including against vaccines. The serum antibody screen also identifies individuals with IgG responses to less common infections (West Nile virus, parvovirus, tuberculosis). The characterization of the antibody responses in combination with the identification of genetic risk alleles provides an opportunity to identify children with increased risk of clinical disease.

Phase II Randomized Trial of Rituximab Plus Cyclophosphamide Followed by Belimumab for the Treatment of Lupus Nephritis.

OBJECTIVE: To assess the safety, mechanism of action, and preliminary efficacy of rituximab followed by belimumab in the treatment of refractory lupus nephritis (LN). METHODS: In a multicenter, randomized, open-label clinical trial, 43 patients with recurrent or refractory LN were treated with rituximab, cyclophosphamide (CYC), and glucocorticoids followed by weekly belimumab infusions until week 48 (RCB group), or treated with rituximab and CYC but no belimumab infusions (RC group). Patients were followed up until week 96. Percentages of total and autoreactive B cell subsets in the patients' peripheral blood were analyzed by flow cytometry. RESULTS: Treatment with belimumab did not increase the incidence of adverse events in patients with refractory LN. At week 48, a complete or partial renal response occurred in 11 (52%) of 21 patients receiving belimumab, compared to 9 (41%) of 22 patients in the RC group who did not receive belimumab (P = 0.452). Lack of improvement in or worsening of LN was the major reason for treatment failure. B cell depletion occurred in both groups, but the percentage of B cells remained lower in those receiving belimumab (geometric mean number of B cells at week 60, 53 cells/µl in the RCB group versus 11 cells/µl in the RC group; P = 0.0012). Percentages of total and autoreactive transitional B cells increased from baseline to week 48 in both groups. However, percentages of total and autoreactive naive B cells decreased from baseline to week 48 in the belimumab group compared to the no belimumab RC group (P = 0.0349), a finding that is consistent with the observed impaired maturation of naive B cells and enhanced censoring of autoreactive B cells. CONCLUSION: The addition of belimumab to a treatment regimen with rituximab and CYC was safe in patients with refractory LN. This regimen diminished maturation of transitional to naive B cells during B cell reconstitution, and enhanced the negative selection of autoreactive B cells. Clinical efficacy was not improved with rituximab and CYC in combination with belimumab when compared to a therapeutic strategy of B cell depletion alone in patients with LN.

American College of Rheumatology Clinical Guidance for Multisystem Inflammatory Syndrome in Children Associated With SARS-CoV-2 and Hyperinflammation in Pediatric COVID-19: Version 2.

OBJECTIVE: To provide guidance on the management of Multisystem Inflammatory Syndrome in Children (MIS-C), a condition characterized by fever, inflammation, and multiorgan dysfunction that manifests late in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Recommendations are also provided for children with hyperinflammation during coronavirus disease 2019 (COVID-19), the acute, infectious phase of SARS-CoV-2 infection. METHODS: The Task Force was composed of 9 pediatric rheumatologists and 2 adult rheumatologists, 2 pediatric cardiologists, 2 pediatric infectious disease specialists, and 1 pediatric critical care physician. Preliminary statements addressing clinical questions related to MIS-C and hyperinflammation in COVID-19 were developed based on evidence reports. Consensus was built through a modified Delphi process that involved anonymous voting and webinar discussion. A 9-point scale was used to determine the appropriateness of each statement (median scores of 1-3 for inappropriate, 4-6 for uncertain, and 7-9 for appropriate). Consensus was rated as low, moderate, or high based on dispersion of the votes. Approved guidance statements were those that were classified as appropriate with moderate or high levels of consensus, which were prespecified before voting. RESULTS: The first version of the guidance was approved in June 2020, and consisted of 40 final guidance statements accompanied by a flow diagram depicting the diagnostic pathway for MIS-C. The document was revised in November 2020, and a new flow diagram with recommendations for initial immunomodulatory treatment of MIS-C was added. CONCLUSION: Our understanding of SARS-CoV-2-related syndromes in the pediatric population continues to evolve. This guidance document reflects currently available evidence coupled with expert opinion, and will be revised as further evidence becomes available.

Deep sequencing reveals a DAP1 regulatory haplotype that potentiates autoimmunity in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is a clinically heterogeneous autoimmune disease characterized by the development of anti-nuclear antibodies. Susceptibility to SLE is multifactorial, with a combination of genetic and environmental risk factors contributing to disease development. Like other polygenic diseases, a significant proportion of estimated SLE heritability is not accounted for by common disease alleles analyzed by SNP array-based GWASs. Death-associated protein 1 (DAP1) was implicated as a candidate gene in a previous familial linkage study of SLE and rheumatoid arthritis, but the association has not been explored further. RESULTS: We perform deep sequencing across the DAP1 genomic segment in 2032 SLE patients, and healthy controls, and discover a low-frequency functional haplotype strongly associated with SLE risk in multiple ethnicities. We find multiple cis-eQTLs embedded in a risk haplotype that progressively downregulates DAP1 transcription in immune cells. Decreased DAP1 transcription results in reduced DAP1 protein in peripheral blood mononuclear cells, monocytes, and lymphoblastoid cell lines, leading to enhanced autophagic flux in immune cells expressing the DAP1 risk haplotype. Patients with DAP1 risk allele exhibit significantly higher autoantibody titers and altered expression of the immune system, autophagy, and apoptosis pathway transcripts, indicating that the DAP1 risk allele mediates enhanced autophagy, leading to the survival of autoreactive lymphocytes and increased autoantibody. CONCLUSIONS: We demonstrate how targeted sequencing captures low-frequency functional risk alleles that are missed by SNP array-based studies. SLE patients with the DAP1 genotype have distinct autoantibody and transcription profiles, supporting the dissection of SLE heterogeneity by genetic analysis.

Anti-Neutrophil Extracellular Trap Antibodies and Impaired Neutrophil Extracellular Trap Degradation in Antiphospholipid Syndrome.

OBJECTIVE: The release of neutrophil extracellular traps (NETs) by hyperactive neutrophils has recently been recognized to play an important role in antiphospholipid syndrome (APS). This study was undertaken to evaluate autoantibodies targeting NETs in patients with primary APS, and to determine their potential functions and clinical associations. METHODS: We measured global anti-NET activity in 76 patients with primary APS, 23 patients with systemic lupus erythematosus without antiphospholipid antibodies (aPL), 11 patients with a history of unprovoked venous thrombosis without aPL, and 44 healthy controls. The ability of APS sera to degrade NETs was also assessed. RESULTS: We found markedly elevated levels of anti-NET IgG and IgM in patients with primary APS compared with healthy controls (for IgG, mean ± SD optical density 0.55 ± 0.34 versus 0.33 ± 0.17; for IgM, mean ± SD optical density 0.76 ± 0.51 versus 0.26 ± 0.23). This anti-NET activity did not correlate with levels of traditional aPL and was relatively stable over time. Mechanistically, anti-NET antibodies (especially of the IgG isotype) impaired the ability of patient sera to degrade NETs (r = 0.4, P = 0.003). Levels of anti-NET IgM inversely correlated with complement C4 (r = 0.4, P = 0.019). Clinically, anti-NET antibodies associated with certain APS clinical manifestations, and in particular recurrent venous thrombosis (odds ratio 4.3; P = 0.002). Interestingly, anti-NET antibody levels also appeared to be associated with unprovoked venous thrombosis in the general population (for IgM, mean ± SD optical density 0.67 ± 0.34 versus 0.26 ± 0.23). CONCLUSION: Our data indicate high levels of anti-NET antibodies in patients with primary APS, which may impair NET clearance and activate the complement cascade. These findings may ultimately enable more effective risk stratification.

SARS-CoV-2 Antibody Responses Do Not Predict COVID-19 Disease Severity.

OBJECTIVES: Initial reports indicate adequate performance of some serology-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assays. However, additional studies are required to facilitate interpretation of results, including how antibody levels impact immunity and disease course. METHODS: A total of 967 subjects were tested for IgG antibodies reactive to SARS-CoV-2, including 172 suspected cases of SARS-CoV-2, 656 plasma samples from healthy donors, 49 sera from patients with rheumatic disease, and 90 specimens from individuals positive for polymerase chain reaction (PCR)-based respiratory viral panel. A subgroup of SARS-CoV-2 PCR-positive cases was tested for IgM antibodies by proteome array method. RESULTS: All specificity and cross-reactivity specimens were negative for SARS-CoV-2 IgG antibodies (0/795, 0%). Positive agreement of IgG with PCR was 83% of samples confirmed to be more than 14 days from symptom onset, with less than 100% sensitivity attributable to a case with severe immunosuppression. Virus-specific IgM was positive in a higher proportion of cases less than 3 days from symptom onset. No association was observed between mild and severe disease course with respect to IgG and IgM levels. CONCLUSIONS: The studied SARS-CoV-2 IgG assay had 100% specificity and no adverse cross-reactivity. Measures of IgG and IgM antibodies did not predict disease severity in our patient population.

American College of Rheumatology Guidance for the Management of Pediatric Rheumatic Disease During the COVID-19 Pandemic: Version 1.

OBJECTIVE: To provide clinical guidance to rheumatology providers who treat children with pediatric rheumatic disease (PRD) in the context of the coronavirus disease 2019 (COVID-19) pandemic. METHODS: The task force, consisting of 7 pediatric rheumatologists, 2 pediatric infectious disease physicians, 1 adult rheumatologist, and 1 pediatric nurse practitioner, was convened on May 21, 2020. Clinical questions and subsequent guidance statements were drafted based on a review of the queries posed by the patients as well as the families and healthcare providers of children with PRD. An evidence report was generated and disseminated to task force members to assist with 3 rounds of asynchronous, anonymous voting by email using a modified Delphi approach. Voting was completed using a 9-point numeric scoring system with predefined levels of agreement (categorized as disagreement, uncertainty, or agreement, with median scores of 1-3, 4-6, and 7-9, respectively) and consensus (categorized as low, moderate, or high). To be approved as a guidance statement, median vote ratings were required to fall into the highest tertile for agreement, with either moderate or high levels of consensus. RESULTS: The task force drafted 33 guidance statements, which were voted upon during the second and third rounds of voting. Of these 33 statements, all received median vote ratings within the highest tertile of agreement and were associated with either moderate consensus (n = 6) or high consensus (n = 27). Statements with similar recommendations were combined, resulting in 27 final guidance statements. CONCLUSION: These guidance statements have been generated based on review of the available literature, indicating that children with PRD do not appear to be at increased risk for susceptibility to SARS-CoV-2 infection. This guidance is presented as a "living document," recognizing that the literature on COVID-19 is rapidly evolving, with future updates anticipated.

American College of Rheumatology Clinical Guidance for Multisystem Inflammatory Syndrome in Children Associated With SARS-CoV-2 and Hyperinflammation in Pediatric COVID-19: Version 1.

OBJECTIVE: To provide guidance on the management of multisystem inflammatory syndrome in children (MIS-C), a condition characterized by fever, inflammation, and multiorgan dysfunction that manifests late in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and to provide recommendations for children with hyperinflammation during coronavirus disease 2019 (COVID-19), the acute, infectious phase of SARS-CoV-2 infection. METHODS: A multidisciplinary task force was convened by the American College of Rheumatology (ACR) to provide guidance on the management of MIS-C associated with SARS-CoV-2 and hyperinflammation in COVID-19. The task force was composed of 9 pediatric rheumatologists, 2 adult rheumatologists, 2 pediatric cardiologists, 2 pediatric infectious disease specialists, and 1 pediatric critical care physician. Preliminary statements addressing clinical questions related to MIS-C and hyperinflammation in COVID-19 were developed based on evidence reports. Consensus was built through a modified Delphi process that involved 2 rounds of anonymous voting and 2 webinars. A 9-point scale was used to determine the appropriateness of each statement (median scores of 1-3 for inappropriate, 4-6 for uncertain, and 7-9 for appropriate), and consensus was rated as low, moderate, or high based on dispersion of the votes along the numeric scale. Approved guidance statements were those that were classified as appropriate with moderate or high levels of consensus, as prespecified prior to voting. RESULTS: The ACR task force approved a total of 128 guidance statements addressing the management of MIS-C and hyperinflammation in pediatric COVID-19. These statements were refined into 40 final clinical guidance statements, accompanied by a flow diagram depicting the diagnostic pathway for MIS-C. CONCLUSION: Our understanding of SARS-CoV-2-related syndromes in the pediatric population continues to evolve. The guidance provided in this "living document" reflects currently available evidence, coupled with expert opinion, and will be revised as further evidence becomes available.

Statin Intolerance, Anti-HMGCR Antibodies, and Immune Checkpoint Inhibitor-Associated Myositis: A "Two-Hit" Autoimmune Toxicity or Clinical Predisposition?

Immune-related adverse events induced by immune checkpoint inhibitor (ICI) therapy may affect diverse organ systems, including skeletal and cardiac muscle. ICI-associated myositis may result in substantial morbidity and occasional mortality. We present a case of a patient with advanced non-small cell lung cancer who developed grade 4 myositis with concurrent myocarditis early after initiation of anti-programmed death ligand 1 therapy (durvalumab). Autoantibody analysis revealed marked increases in anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody levels that preceded clinical toxicity, and further increased during toxicity. Notably, the patient had a history of intolerable statin myopathy, which had resolved clinically after statin discontinuation and prior to ICI initiation. This case demonstrates a potential association between statin exposure, autoantibodies, and ICI-associated myositis.

Late-Onset Immunotherapy Toxicity and Delayed Autoantibody Changes: Checkpoint Inhibitor-Induced Raynaud's-Like Phenomenon.

Immune checkpoint inhibitor (ICI)-induced immune-related adverse events (irAEs) may affect almost any organ system and occur at any point during therapy. Autoantibody analysis may provide insight into the mechanism, nature, and timing of these events. We report a case of ICI-induced late-onset Raynaud's-like phenomenon in a patient receiving combination immunotherapy. A 53-year-old woman with advanced non-small lung cancer received combination anti-cytotoxic T-lymphocyte antigen 4 and anti-programmed death 1 ICI therapy. She developed early (hypophysitis at 4 months) and late (Raynaud's at >20 months) irAEs. Longitudinal assessment of 124 autoantibodies was correlated with toxicity. Although autoantibody levels were generally stable for the first 18 months of therapy, shortly before the development of Raynaud's, a marked increase in multiple autoantibodies was observed. This case highlights the potential for delayed autoimmune toxicities and provides potential biologic insights into the dynamic nature of these events. KEY POINTS: A patient treated with dual anti-PD1 and anti-CTLA4 therapy developed Raynaud's-like signs and symptoms more than 18 months after starting therapy. In this case, autoantibody changes became apparent shortly before onset of clinical toxicity. This case highlights the potential for late-onset immune-related adverse events checkpoint inhibitors, requiring continuous clinical vigilance. The optimal duration of checkpoint inhibitor therapy in patients with profound and prolonged responses remains unclear.