Renal Response Outcomes of the EuroLupus and National Institutes of Health Cyclophosphamide Dosing Regimens in Childhood-Onset Proliferative Lupus Nephritis.

OBJECTIVE: We compared clinical characteristics and renal response in patients with childhood-onset proliferative lupus nephritis (LN) treated with the EuroLupus versus National Institutes of Health (NIH) cyclophosphamide (CYC) regimen. METHODS: A retrospective cohort study was conducted at 11 pediatric centers in North America that reported using both CYC regimens. Data were extracted from the electronic medical record at baseline and 3, 6, and 12 months after treatment initiation with CYC. To evaluate the adjusted association between CYC regimen (EuroLupus vs NIH) and renal response over time, generalized estimating equations with a logit link were used. An interaction between time and CYC regimen was included, and a contrast between CYC regimens at 12 months was used to evaluate the primary outcome. RESULTS: One hundred forty-five patients (58 EuroLupus, 87 NIH) were included. EuroLupus patients were on average older at the start of current CYC therapy, had longer disease duration, and more commonly had relapsed or refractory LN compared with the NIH group. After multivariable adjustment, there was no significant association between CYC regimen and achieving complete renal response at 12 months (odds ratio [OR] of response for the EuroLupus regimen, reference NIH regimen: 0.76; 95% confidence interval [CI] 0.29-1.98). There was also no significant association between CYC regimen and achieving at least a partial renal response at 12 months (OR 1.35, 95% CI 0.57-3.19). CONCLUSION: Our study failed to demonstrate a benefit of the NIH regimen over the EuroLupus CYC regimen in childhood-onset proliferative LN. However, future prospective outcome studies are needed.

Feasibility of Conducting Comparative Effectiveness Research and Validation of a Clinical Disease Activity Score for Chronic Nonbacterial Osteomyelitis.

OBJECTIVE: Prospective comparative effectiveness research (CER) in chronic nonbacterial osteomyelitis (CNO) is lacking. Our objectives were to (1) determine the use and safety of each consensus treatment plan (CTP) regimen for CNO, (2) assess the feasibility of using the Chronic Nonbacterial Osteomyelitis International Registry (CHOIR) data for CER, and (3) develop and validate a CNO clinical disease activity score (CDAS) using CHOIR. METHODS: Consenting children or young adults with CNO were enrolled into CHOIR. Demographic, clinical, and imaging data were prospectively collected. The CNO CDAS was developed through a Delphi survey and nominal group technique. External validation surveys were administered to CHOIR participants. RESULTS: One hundred forty (78.2%) CHOIR participants enrolled between August 2018 and September 2020 received at least 1 CTP regimen. Baseline characteristics from different CTP groups were well matched. Patient pain, patient global assessment, and clinical CNO lesion count were key variables included in the CNO CDAS. The CDAS showed a strong correlation with patient/parent report of difficulty using a limb, back, or jaw and patient/parent report of disease severity, but a weak correlation with patient/parent report of fatigue, sadness, and worry. The change in CDAS was significant in patients reporting disease worsening or improvement (P < 0.001). The CDAS significantly decreased after initiating second-line treatments from median 12.0 (IQR 8.0-15.5) to 5.0 (IQR 3.0-12.0; P = 0.002). Although second-line treatments were well tolerated, psoriasis was the most common adverse event. CONCLUSION: The CNO CDAS was developed and validated for disease monitoring and assessment of treatment effectiveness. CHOIR provided a comprehensive framework for future CER.

ANCA vasculitis expands the spectrum of autoimmune manifestations of activated PI3 kinase δ syndrome.

Activated phosphoinositide 3-kinase δ syndrome (APDS) is a combined immunodeficiency with a broad clinical phenotype, including not only an increased propensity for sinopulmonary and herpesviruses infections but also immune dysregulation, such as benign lymphoproliferation, autoimmunity, and malignancy. Autoimmune complications are increasingly recognized as initial presenting features of immune dysregulation in inborn errors of immunity (IEIs), including APDS, so awareness of the spectrum of autoimmune features inherit within these disorders is critical. We present here a patient vignette to highlight cutaneous antineutrophil cytoplasmic antibody (ANCA) vasculitis as an underrecognized autoimmune manifestation of APDS. The genetic defects underlying APDS result in increased PI3Kδ signaling with aberrant downstream signaling pathways and loss of B- and/or T-cell immunologic tolerance mechanisms, which promote the development of autoimmunity. An understanding of the molecular pathways and mechanisms that lead to immune dysregulation in APDS has allowed for significant advancements in the development of precision-medicine therapeutics, such as leniolisib, to reduce the morbidity and mortality for these patients. Overall, this case and review highlight the need to maintain a high index of suspicion for IEIs, such as APDS, in those presenting with autoimmunity in combination with a dysregulated immune phenotype for prompt diagnosis and targeted intervention.

Multisystemic Inflammatory Syndrome in Children and Kawasaki Disease: Parallels in Pathogenesis and Treatment.

PURPOSE OF REVIEW: Since it first appeared, multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease 2019 (COVID-19) has been compared to Kawasaki disease (KD). Although there were early parallels between MIS-C and KD, key differences emerged over time. Here, we aim to compare the pathogenesis, clinical presentation, treatment, and outcomes of MIS-C and KD. RECENT FINDINGS: In this article, we review and compare MIS-C and KD, highlighting differentiating features. We discuss the epidemiological and immunological factors along with clinical and laboratory features which discern MIS-C from KD. We also compare treatment and our understanding of long-term outcomes. Though parallels exist between MIS-C and KD, distinguishing the two is important for clinical management of patients, counseling about natural history, and determining long-term monitoring. While both MIS-C and KD are characterized by profound inflammation and inflammatory vasculopathy, further study is needed to determine whether they are distinct immunopathogenic disorders.

Calcinosis in juvenile dermatomyositis: Updates on pathogenesis and treatment.

Calcinosis, or the deposition of insoluble calcium salts in the skin, subcutaneous tissue, fascia, tendons, and muscles, is a feared complication of juvenile dermatomyositis. Calcinosis is estimated to affect up to 40% of patients with juvenile dermatomyositis and contributes to significant disease morbidity. Calcinosis can be challenging to treat, and the most effective treatment remains unknown because of a lack of comparative studies. We aim to review the literature published in the last 5 years to summarize updates on the pathogenesis and treatment of calcinosis in juvenile dermatomyositis and describe future areas for research.

Intra-articular delivery of AAV vectors encoding PD-L1 attenuates joint inflammation and tissue damage in a mouse model of rheumatoid arthritis.

Objective: Rheumatoid arthritis (RA) is the most common form of autoimmune inflammatory arthritis. Intra-articular gene delivery to block proinflammatory cytokines has been studied in pre-clinical models and human clinical trials. It has been demonstrated that the level of programmed death-ligand 1 (PD-L1) is associated with rheumatoid arthritis (RA). This study examined the therapeutic role of PD-L1 by intra-articular delivery via adeno-associated virus (AAV) vectors in the mouse collagen-induced arthritis (CIA) model. Methods: Mice were intra-articularly injected with AAV5 vectors encoding human PD-L1 on day 0 and immunized with bovine type II collagen to induce CIA simultaneously. On day 49 post AAV administration, joints were collected for histo-pathological and cytokine analysis. Additionally, the systemic impacts of intra-articular injection of AAV5/PD-L1 vectors were also studied. To study the therapeutic effect of PD-L1, AAV5/PD-L1 vectors were administered into the joints of RA mice on day 21. Results: After administration of AAV5/PD-L1 vectors, strong PD-L1 expression was detected in AAV transduced joints. Joints treated with PD-L1 at the time of arthritis induction exhibited significantly less swelling and improved histopathological scores when compared to untreated joints. Additionally, the infiltration of T cells and macrophages was decreased in joints of CIA mice that received AAV5/PD-L1 vectors (P<0.05). The levels of pro-inflammatory cytokines, including IL-1, IL-6, IL-17 and TNFα, were lower in AAV5/PD-L1 treated than untreated joints (P<0.05). Furthermore, the administration of AAV5/PD-L1 vectors into the joints of CIA mice did not impact serum cytokine levels and the antibody titers to type II collagen. Biodistribution of AAV vectors after intra-articular injection showed undetectable AAV genomes in other tissues except for a low level in the liver. Similar to the results of AAV5/PD-L1 vector administration on day 0, decreased joint swelling and lower histopathological damage were observed in joints treated with AAV5/PD-L1 vectors on day 21. Conclusion: The results from this study demonstrate that local AAV mediated PD-L1 gene delivery into the joints is able to prevent the development and block the progression of arthritis in CIA mice without impacting systemic immune responses. This study provides a novel strategy to effectively treat inflammatory joint diseases using local AAV gene therapy by interference with immune checkpoint pathways.

Secondary immunodeficiencies and infectious considerations of biologic immunomodulatory therapies.

Biologic immunomodulatory medications have rapidly expanded in the previous decades, providing new treatment options for individuals with a spectrum of oncologic, allergic, rheumatologic, and neurologic conditions. Biologic therapies alter immune function and can impair key host defense mechanisms, resulting in secondary immunodeficiency and increased infectious risks. Biologic medications can increase general risk for upper respiratory tract infections but can also be associated with unique infectious risks owing to distinct mechanisms of action. With the widespread use of these medications, providers in every area of medicine will likely care for individuals receiving biologic therapies and understanding their potential infectious complications can help mitigate these risks. This practical review discusses the infectious implications of biologics by class of medication and provides recommendations regarding the examination and screening both before therapy initiation and while the patient is receiving the medication. With this knowledge and background, providers can reduce risk whereas patients receive the treatment benefits of these biologic medications.

PRTN3 variant correlates with increased autoantigen levels and relapse risk in PR3-ANCA versus MPO-ANCA disease.

A GWAS of patients with anti-neutrophil cytoplasmic antibodies (ANCAs) found an association between proteinase-3 ANCA (PR3-ANCA) and a single nucleotide polymorphism (rs62132293) upstream of PRTN3, encoding PR3. The variant (G allele) was shown to be an expression quantitative trait locus in healthy controls, but the clinical impact remains unknown. Longitudinally followed patients with ANCA and healthy controls were genotyped. Gene expression was quantified by real-time quantitative PCR from leukocyte RNA. Plasma PR3 was quantified by ELISA. Among patients, variant carriers had elevated leukocyte PRTN3 expression compared with noncarriers (C/G vs. C/C and G/G vs. C/C). Healthy controls had low PRTN3 regardless of genotype. Myeloperoxidase (MPO) expression did not differ by genotype. PRTN3 expression correlated with circulating PR3, and variant carriers had higher plasma PR3 compared with noncarriers. Among variant carriers, there was an increased risk of relapse in patients with PR3-ANCA versus MPO-ANCA. The risk allele marked by rs62132293 is clinically significant as it is associated with increased autoantigen and may, in part, explain increased relapse in PR3-ANCA. Our results underscore the role of autoantigen availability in ANCA vasculitis.

The frequency of Treg subsets distinguishes disease activity in ANCA vasculitis.

Objectives: T regulatory cells (Tregs) are a heterogeneous group of immunoregulatory cells that dampen self-harming immune responses and prevent the development of autoimmune diseases. In anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis, Tregs possess diminished suppressive capacity, which has been attributed to the expression of a FOXP3 splice-variant lacking exon 2 in T cells (FOXP3Δ2 CD4+ T cells). However, the suppressive capacity of Tregs varies between subsets. We evaluated the frequency of Treg subsets in ANCA vasculitis as a potential explanation for diminished suppressive capacity. Methods: We developed a custom mass cytometry panel and performed deep immune profiling of Tregs in healthy controls, patients with active disease and in remission. Using these data, we performed multidimensional reduction and discriminant analysis to identify associations between Treg subsets and disease activity. Results: Total Tregs were expanded in ANCA vasculitis, which was associated with remission and the administration of rituximab and/or prednisone. The frequency of FOXP3Δ2 CD4+ T cells did not distinguish disease activity and this population had high expression levels of CD127 and lacked both CD25 and Helios, suggesting that they are not conventional Tregs. The frequency of CXCR3+, CD103+ and CCR7+ Tregs distinguished disease activity, and the combination of the frequency of these three Treg subsets segregated active patients from patients in remission and healthy controls. From these three subsets, the frequency of CXCR3+ Tregs distinguished patients with active disease with renal involvement. Conclusion: Treg heterogeneity can discriminate disease activity and should be explored as a biomarker of disease activity in ANCA vasculitis.

Postdischarge Glucocorticoid Use and Clinical Outcomes of Multisystem Inflammatory Syndrome in Children.

Importance: Minimal data are available regarding the postdischarge treatment of multisystem inflammatory syndrome in children (MIS-C). Objectives: To evaluate clinical characteristics associated with duration of postdischarge glucocorticoid use and assess postdischarge clinical course, laboratory test result trajectories, and adverse events in a multicenter cohort with MIS-C. Design, Setting, and Participants: This retrospective cohort study included patients with MIS-C hospitalized with severe illness and followed up for 3 months in an ambulatory setting. Patients younger than 21 years who were admitted between May 15, 2020, and May 31, 2021, at 13 US hospitals were included. Inclusion criteria were inpatient treatment comprising intravenous immunoglobulin, diagnosis of cardiovascular dysfunction (vasopressor requirement or left ventricular ejection fraction ≤55%), and availability of complete outpatient data for 3 months. Exposures: Glucocorticoid treatment. Main Outcomes and Measures: Main outcomes were patient characteristics associated with postdischarge glucocorticoid treatment, laboratory test result trajectories, and adverse events. Multivariable regression was used to evaluate factors associated with postdischarge weight gain (≥2 kg in 3 months) and hyperglycemia during illness. Results: Among 186 patients, the median age was 10.4 years (IQR, 6.7-14.2 years); most were male (107 [57.5%]), Black non-Hispanic (60 [32.3%]), and Hispanic or Latino (59 [31.7%]). Most children were critically ill (intensive care unit admission, 163 [87.6%]; vasopressor receipt, 134 [72.0%]) and received inpatient glucocorticoid treatment (178 [95.7%]). Most were discharged with continued glucocorticoid treatment (173 [93.0%]); median discharge dose was 42 mg/d (IQR, 30-60 mg/d) or 1.1 mg/kg/d (IQR, 0.7-1.7 mg/kg/d). Inpatient severity of illness was not associated with duration of postdischarge glucocorticoid treatment. Outpatient treatment duration varied (median, 23 days; IQR, 15-32 days). Time to normalization of C-reactive protein and ferritin levels was similar for glucocorticoid duration of less than 3 weeks vs 3 or more weeks. Readmission occurred in 7 patients (3.8%); none was for cardiovascular dysfunction. Hyperglycemia developed in 14 patients (8.1%). Seventy-five patients (43%) gained 2 kg or more after discharge (median 4.1 kg; IQR, 3.0-6.0 kg). Inpatient high-dose intravenous and oral glucocorticoid therapy was associated with postdischarge weight gain (adjusted odds ratio, 6.91; 95% CI, 1.92-24.91). Conclusions and Relevance: In this multicenter cohort of patients with MIS-C and cardiovascular dysfunction, postdischarge glucocorticoid treatment was often prolonged, but clinical outcomes were similar in patients prescribed shorter courses. Outpatient weight gain was common. Readmission was infrequent, with none for cardiovascular dysfunction. These findings suggest that strategies are needed to optimize postdischarge glucocorticoid courses for patients with MIS-C.

Immunological Interaction of HLA-DPB1 and Proteinase 3 in ANCA Vasculitis is Associated with Clinical Disease Activity.

BACKGROUND: PR3-ANCA vasculitis has a genetic association with HLA-DPB1. We explored immunologic and clinical features related to the interaction of HLA-DPB1*04:01 with a strongly binding PR3 peptide epitope (PR3225-239). METHODS: Patients with ANCA vasculitis with active disease and disease in remission were followed longitudinally. Peripheral blood mononuclear cells from patients and healthy controls with HLA-DPB1*04:01 were tested for HLA-DPB1*04:01 expression and interaction with a PR3 peptide identified via in silico and in vitro assays. Tetramers (HLA/peptide multimers) identified autoreactive T cells in vitro. RESULTS: The HLA-DPB1*04:01 genotype was associated with risk of relapse in PR3-ANCA (HR for relapse 2.06; 95% CI, 1.01 to 4.20) but not in myeloperoxidase (MPO)-ANCA or the combined cohort. In silico predictions of HLA and PR3 peptide interactions demonstrated strong affinity between ATRLFPDFFTRVALY (PR3225-239) and HLA-DPB1*04:01 that was confirmed by in vitro competitive binding studies. The interaction was tested in ex vivo flow cytometry studies of labeled peptide and HLA-DPB1*04:01-expressing cells. We demonstrated PR3225-239 specific autoreactive T cells using synthetic HLA multimers (tetramers). Patients in long-term remission off therapy had autoantigenic peptide and HLA interaction comparable to that of healthy volunteers. CONCLUSIONS: The risk allele HLA-DPB1*04:01 has been associated with PR3-ANCA, but its immunopathologic role was unclear. These studies demonstrate that HLA-DPB1*04:01 and PR3225-239 initiate an immune response. Autoreactive T cells specifically recognized PR3225-239 presented by HLA-DPB1*04:01. Although larger studies should validate these findings, the pathobiology may explain the observed increased risk of relapse in our cohort. Moreover, lack of HLA and autoantigen interaction observed during long-term remission signals immunologic nonresponsiveness.

Recent Advances in Pediatric Vasculitis.

This article provides an overview of the clinical presentation and diagnosis of select pediatric primary systemic vasculitides. Important advances in understanding the pathogenesis of these rare diseases also are discussed and efforts to harmonize treatment through consensus-based guidelines and multicenter and international collaborations highlighted.

Cardiac Manifestations of Multisystem Inflammatory Syndrome in Children (MIS-C) Following COVID-19.

PURPOSE OF REVIEW: To review the spectrum of cardiac manifestations and treatments of multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease 2019 (COVID-19). RECENT FINDINGS: Studies demonstrate that up to 80% of children with MIS-C may have cardiac involvement on a spectrum of severity. Cardiac manifestations include myocarditis, coronary artery aneurysms, conduction abnormalities, and arrhythmias. Current treatments, including inotropic support, immunomodulatory therapy, and anti-coagulation, have been effective at resolving these cardiac findings in the majority of patients. COVID-19 can also cause myocarditis in the acute stage of illness and recent descriptions of COVID-19 vaccine myocarditis have occurred. Cardiac manifestations are common in MIS-C and should be assessed for at presentation and during the clinical course as indicated.

Autoimmune Cytopenia as an Early and Initial Presenting Manifestation in Activated PI3 Kinase Delta Syndrome: Case Report and Review.

Activated PI3 kinase delta syndrome (APDS) is a combined immunodeficiency characterized by recurrent sinopulmonary infections, increased risk of herpesvirus infections, lymphoproliferation, autoimmunity, and increased risk of lymphoid malignancies. Gain-of-function mutations in PIK3CD and PIK3R1 result in increased phosphoinositide-3-kinase-delta activity which causes hyperactivation of lymphocytes and abnormal development and activation of T and B cells. Cytopenias are the most common autoimmune process occurring in patients with APDS and typically occur as a later manifestation of the disease. Here we present a female patient with an early autoimmune hemolytic anemia, hepatosplenomegaly, and frequent infections presenting in infancy, followed by development of significant lymphadenopathy before her diagnosis with APDS type 1. She had significant improvement in her infectious history with immunoglobulin replacement, and control of autoimmune hemolytic anemia with initiation of sirolimus after her diagnosis with APDS type 1. We utilize this case to review the literature on APDS and present the novel finding of early-onset autoimmune disease in the setting of APDS. Autoimmune cytopenias are seen in many primary immunodeficiencies, and workup of autoimmune cytopenias in young patients should include evaluation for underlying immune disorder.

ANCA autoantigen gene expression highlights neutrophil heterogeneity where expression in normal-density neutrophils correlates with ANCA-induced activation.

ANCA vasculitis is an autoimmune disease with increased expression of the autoantigen genes, myeloperoxidase (MPO) and proteinase 3 (PRTN3), but the origin and significance of expression is less distinct. To clarify this, we measured MPO and PRTN3 messenger RNA in monocytes, normal-density neutrophils, and in enriched leukocytes from peripheral blood mononuclear cells. Increased autoantigen gene expression was detected in normal-density neutrophils and enriched leukocytes from patients during active disease compared to healthy individuals, with the largest difference in enriched leukocytes. RNA-seq of enriched leukocytes comparing active-remission pairs identified a gene signature for low-density neutrophils. Cell sorting revealed low-density neutrophils contained mature and immature neutrophils depending on the presence or absence of CD10. Both populations contributed to autoantigen expression but the frequency of immature cells in low-density neutrophils did not correlate with low-density neutrophil MPO or PRTN3 expression. Low-density neutrophils were refractory to MPO-ANCA induced oxidative burst, suggesting an alternative role for low-density neutrophils in ANCA vasculitis pathogenesis. In contrast, normal-density neutrophils were activated by MPO-ANCA and monoclonal anti-PR3 antibody. Normal-density neutrophil activation correlated with MPO and PRTN3 mRNA. Increased autoantigen gene expression originating from the mature low-density and normal-density neutrophils suggests transcriptional dysregulation is a hallmark of ANCA vasculitis. Thus, the correlation between autoantigen gene expression and antibody-mediated normal-density neutrophil activation connects autoantigen gene expression with disease pathogenesis.

Baseline Description of the Juvenile Localized Scleroderma Subgroup From the Childhood Arthritis and Rheumatology Research Alliance Legacy Registry.

OBJECTIVE: Localized scleroderma (LS) is a chronic inflammatory and fibrosing skin disorder. We present baseline data on the juvenile LS (jLS) cohort from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry, a multicenter observational registry of pediatric rheumatologic disorders. METHODS: This is a cross-sectional analysis of children with jLS enrolled in the CARRA Legacy Registry between May 2010 and April 2014. Descriptive statistics were used for demographic, clinical, and laboratory features. Data analysis included two-sample t test, χ2 test, Fisher's exact test, linear/logistic regression, and analysis of variance. RESULTS: Of 381 children with jLS, 76% were female and 80% Caucasian. Mean onset age was 8.2 years, with 17% having a 2-year or greater delay to first pediatric rheumatology (PRH) visit. Linear scleroderma was the most common subtype (54%). Antinuclear antibody (ANA) positivity was associated with joint contracture (P = 0.04), muscle atrophy (P = 0.014), and extremity shortening (P = 0.007). Elevated aldolase was associated with joint contracture (P = 0.008) and elevated creatine kinase (CK) with muscle atrophy (P = 0.028) and extremity shortening (P = 0.016). Children with functional limitation (27%) had earlier first PRH visit compared with those without (P = 0.01). Poorer function correlated with muscle atrophy, joint contracture, and extremity shortening (P < 0.001). Methotrexate (97%) and corticosteroids (68%) were the most common medications used. CONCLUSION: Children with jLS without joint limitation are referred later, highlighting the insidious onset and need for educating referring providers. Poorer function correlated with muscle atrophy, joint contracture, and limb shortening. ANA positivity and elevated CK or aldolase were associated with muscle atrophy, joint contracture, and/or limb shortening, suggesting predictors of muscle involvement.