Non-criteria antiphospholipid antibodies and calprotectin as potential biomarkers in pediatric antiphospholipid syndrome.

Our study aimed to evaluate the presence, clinical associations, and potential mechanistic roles of non-criteria antiphospholipid antibodies (aPL) and circulating calprotectin, a highly stable marker of neutrophil extracellular trap release (NETosis), in pediatric APS patients. We found that 79% of pediatric APS patients had at least one non-criteria aPL at moderate-to-high titer. Univariate logistic regression demonstrated that positive anti-beta-2 glycoprotein I domain 1 (anti-D1) IgG (p = 0.008), anti-phosphatidylserine/prothrombin (aPS/PT) IgG (p < 0.001), and aPS/PT IgM (p < 0.001) were significantly associated with venous thrombosis. Positive anti-D1 IgG (p < 0.001), aPS/PT IgG (p < 0.001), and aPS/PT IgM (p = 0.001) were also associated with non-thrombotic manifestations of APS, such as thrombocytopenia. Increased levels of calprotectin were detected in children with APS. Calprotectin correlated positively with absolute neutrophil count (r = 0.63, p = 0.008) and negatively with platelet count (r = -0.59, p = 0.015). Mechanistically, plasma from pediatric APS patients with high calprotectin levels impaired platelet viability in a dose-dependent manner.

An unconventional mechanism of IL-1ß secretion that requires Type I IFN in lupus monocytes.

Systemic Lupus Erythematosus (SLE) is characterized by autoreactive B cell activation, upregulation of Type I Interferon (IFN) and widespread inflammation. Mitochondrial nucleic acids (NAs) are increasingly recognized as triggers of IFN 1 . Thus, defective removal of mitochondria from mature red blood cells (Mito + RBCs), a feature of SLE, contributes to IFN production by myeloid cells 2 . Here we identify blood monocytes (Mo) that have internalized RBCs and co-express IFN-stimulated genes (ISGs) and interleukin-1ß (IL-1ß) in SLE patients with active disease. We show that ISG expression requires the interaction between Mito + RBC-derived mitochondrial DNA (mtDNA) and cGAS, while IL-1ß production entails Mito + RBC-derived mitochondrial RNA (mtRNA) triggering of RIG-I-like receptors (RLRs). This leads to the cytosolic release of Mo-derived mtDNA that activates the NLRP3 inflammasome. Importantly, IL-1ß release depends on the IFN-inducible myxovirus resistant protein 1 (MxA), which enables the translocation of this cytokine into a trans-Golgi network (TGN)-mediated unconventional secretory pathway. Our study highlights a novel and synergistic pathway involving IFN and the NLRP3 inflammasome in SLE.

Association of Juvenile Dermatomyositis Disease Activity With the Expansion of Blood Memory B and T Cell Subsets Lacking Follicular Markers.

OBJECTIVE: This study was undertaken to identify blood markers of juvenile dermatomyositis (DM) disease activity (DA), which are needed to improve disease management. METHODS: The study comprised a total of 123 juvenile DM patients and 53 healthy controls. Results of laboratory tests (aldolase, creatinine kinase, lactate dehydrogenase [LDH], aspartate aminotransferase) and clinical measures of DA in patients with juvenile DM, including the Manual Muscle Testing in 8 muscles (MMT-8), Childhood Myositis Assessment Scale (CMAS), and disease activity scores (DAS) (total DAS for juvenile DM, the muscle DAS, and the skin DAS), were recorded when available. Surface phenotype of peripheral blood mononuclear cells was assessed using flow cytometry. Whole blood transcriptional profiles were studied using either RNA-sequencing or microarrays. Differential gene expression was determined using DESeq and compared by pathway and gene ontology analyses. RESULTS: Conventional memory (CD27+IgD-) B cells expressing low CXCR5 levels (CXCR5low/- CM B cells) were significantly increased in frequency and absolute numbers in 2 independent cohorts of juvenile DM patients compared with healthy controls. The frequency of CD4+ Th2 memory cells (CD45RA-CXCR5-CCR6-CXCR3-) was also increased in juvenile DM, especially in patients who were within <1 year from diagnosis. The frequency of CXCR5low/- CM B cells correlated with serum aldolase levels and with a blood interferon-stimulated gene transcriptional signature. Furthermore, both the frequency and absolute numbers of CXCR5low/- CM B cells correlated with clinical and laboratory measures of muscle DA (MMT-8, CMAS, aldolase, and LDH). CONCLUSION: These findings suggest that both CM B cells lacking the CXCR5 follicular marker and CXCR5- Th2 cells represent potential biomarkers of DA in juvenile DM and may contribute to its pathogenesis.

Development and Validation of a Juvenile Spondyloarthritis Disease Flare Measure: Ascertaining Flare in Patients With Inactive Disease.

OBJECTIVE: Our objective was to develop and validate a composite disease flare definition for juvenile spondyloarthritis (SpA) that would closely approximate the clinical decision made to reinitiate or not reinitiate systemic therapy after therapy de-escalation. METHODS: Retrospective chart reviews of children with SpA who underwent systemic therapy de-escalation of biologic or conventional disease-modifying antirheumatic drugs were used to develop and validate the flare outcome. Data on independent cohorts for development (1 center) and validation (4 centers) were collected from large tertiary health care systems. Core measure thresholds and candidate disease flare outcomes were assessed using sensitivity, specificity, positive predictive values (PPVs) and negative predictive values (NPVs), and the receiver operating characteristic (ROC) area under the curve (AUC), with physician assessment of active disease plus re-initiation of standard dose of systemic therapy as the reference standard. RESULTS: Of the candidate definitions, clinically meaningful worsening in ≥3 of the following 5 core measures performed best: caregiver/patient assessment of well-being; physician assessment of disease activity; caregiver/patient assessment of pain, physical function, and active joint count. The ROC AUC was 0.91, PPV 87.5%, NPV 98.1%, sensitivity 82.4%, and specificity 98.7%. Cronbach's α was 0.81, signifying internal consistency, and factor analysis demonstrated that the outcome measured 1 construct. The Juvenile SpA Flare measure had face validity according to 21 surveyed pediatric rheumatologists. Juvenile SpA Flare had an ROC AUC of 0.85, a PPV of 92.3%, and an NPV of 96.8% in the validation cohort. CONCLUSION: There is initial support for the validity of the Juvenile SpA Flare measure as a tool to identify disease flare in juvenile SpA patients de-escalating therapy, and the measure is potentially applicable in clinical practice, observational studies, and therapeutic trials.

Correction: Stoll et al. Impact of HLA-B27 and Disease Status on the Gut Microbiome of the Offspring of Ankylosing Spondylitis Patients. Children 2022, 9, 569.

The authors wish to make the following correction to this paper [...].

Health Literacy and Patient Activation in the Pediatric to Adult Transition in Systemic Lupus Erythematosus: Patient and Health Care Team Perspectives.

OBJECTIVE: To identify perceived health literacy (HL) and patient activation (PA) needs during the transition from pediatric to adult rheumatology among patients with childhood-onset systemic lupus erythematosus (cSLE). METHODS: Semistructured interviews of patients and health care professionals were conducted from November 2019 through May 2020, until thematic saturation was achieved. Interviews were audio-recorded, transcribed, coded, and analyzed using thematic analysis. RESULTS: Thirteen post-transition adult female participants with cSLE were recruited from a public safety-net hospital system or from private practice. Thirteen health care team members were recruited from two pediatric and four adult rheumatology clinical sites serving patients in the same metropolitan area. Patients and health care team members acknowledged numerous HL components as important to transition, including language fluency, education, SLE-specific knowledge, self-efficacy, and accurate knowledge of personal medical history. Our interviews found PA to be an important component of the transition process, driven by internalization of the implications of cSLE diagnosis, self-education, autonomy, introspection, and trustworthy doctor-patient relationships. Patients valued access to their online electronic medical record, recommended multimodal SLE-specific education materials, and desired increased access to social workers. Health care team members stressed the importance of early preparation for transition and use of mobile medical applications and endorsed interventions such as lupus camp and increased partnership with psychologists and social workers. CONCLUSION: HL and PA are perceived by patients and health care team members as substantially influencing transition success. Further research is needed to evaluate whether interventions to improve HL and PA positively influence cSLE transition outcomes.

Therapeutic recreation camps for youth with childhood-onset systemic lupus erythematosus: perceived psychosocial benefits.

BACKGROUND: The psychosocial burden of having a chronic disease can be substantial for adolescents with childhood-onset systemic lupus erythematosus (cSLE). Current literature is scarce on interventions that can improve psychosocial outcomes for this population. Therapeutic recreation camps have been proposed as a beneficial experience for chronically ill pediatric populations. However, their effective components have not been well characterized in patients with cSLE. In this study, we sought to understand the various components of the camp experience for adolescents with cSLE from both the patient and parent perspective. METHODS: We recruited patients with cSLE who had participated in one or more annual, weekend-long recreational lupus camp(s) near Dallas, Texas. Semi-structured in-depth telephone interviews were conducted from March-June 2020 with both the patients and parents. Questions focused on overall patient experience, psychosocial impact of camp participation, coping skills gained, and opportunities to prepare for the transition from pediatric to adult care. Interviews were coded and analyzed using inductive thematic analysis. RESULTS: We interviewed 9 current and former campers (ages 16-24), including a current camp counselor, and 3 of their parents separately. Reported benefits included a positive impact on social support through peer bonding, opportunities to develop coping mechanisms through structured activities and peer/medical staff interactions, opportunities for education about the cSLE disease experience, improved adherence through peer modeling, overall increase in self-efficacy, and better parental insight into the patient experience. Participants also provided suggestions for expansion and improvement in program development to optimize educational opportunities for both campers and parents. In addition, they advocated for longitudinal social support and community building. CONCLUSIONS: In this qualitative study, in which cSLE patients and their parents reflected on their experiences with therapeutic recreation camps, we found several perceived benefits impacting the patient and parent experience. Participants expressed a desire for more educational opportunities that could contribute to their successful transition from pediatric to adult care. Further studies are needed to demonstrate the effects of therapeutic recreation camps on the psychosocial health of this population.

The mammalian SKIV2L RNA exosome is essential for early B cell development.

The SKIV2L RNA exosome is an evolutionarily conserved RNA degradation complex in the eukaryotes. Mutations in the SKIV2L gene are associated with a severe inherited disorder, trichohepatoenteric syndrome (THES), with multisystem involvement but unknown disease mechanism. Here, we reported a THES patient with SKIV2L mutations showing severe primary B cell immunodeficiency, hypogammaglobulinemia, and kappa-restricted plasma cell dyscrasia but normal T cell and NK cell function. To corroborate these findings, we made B cell-specific Skiv2l knockout mice (Skiv2lfl/flCd79a-Cre), which lacked both conventional B-2 and innate-like B-1 B cells in the periphery and secondary lymphoid organs. This was linked to a requirement of SKIV2L RNA exosome activity in the bone marrow during early B cell development at the pro-B cell to large pre-B cell transition. Mechanistically, Skiv2l-deficient pro-B cells exhibited cell cycle arrest and DNA damage. Furthermore, loss of Skiv2l led to substantial out-of-frame V(D)J rearrangement of immunoglobulin heavy chain and severely reduced surface expression of µH, both of which are crucial for pre-BCR signaling and proliferative burst during early B cell development. Together, our data demonstrated a crucial role for SKIV2L RNA exosome in early B cell development in both human and mice by ensuring proper V(D)J recombination and Igh expression, which serves as the molecular basis for immunodeficiency associated with THES.

Impact of HLA-B27 and Disease Status on the Gut Microbiome of the Offspring of Ankylosing Spondylitis Patients.

Multiple studies have shown the microbiota to be abnormal in patients with spondyloarthritis (SpA). The purpose of this study was to explore the genetic contributions of these microbiota abnormalities. We analyzed the impact of HLA-B27 on the microbiota of children at risk for SpA and compared the microbiota of HLA-B27+ pediatric offspring of ankylosing spondylitis (AS) patients with that of HLA-B27+ children with SpA. Human DNA was obtained from the offspring for determination of HLA-B27 status and polygenic risk score (PRS). Fecal specimens were collected from both groups for sequencing of the V4 region of the 16S ribosomal RNA gene. Among the offspring of AS patients, there was slight clustering by HLA-B27 status. After adjusting for multiple comparisons, five operational taxonomic units (OTUs) representing three unique taxa distinguished the HLA-B27+ from negative children: Blautia and Coprococcus were lower in the HLA-B27+ offspring, while Faecalibacterium prausnitzii was higher. HLA-B27+ offspring without arthritis were compared to children with treatment-naïve HLA-B27+ SpA. After adjustments, clustering by diagnosis was present. A total of 21 OTUs were significantly associated with diagnosis state, including Bacteroides (higher in SpA patients) and F. prausnitzii (higher in controls). Thus, our data confirmed associations with B. fragilis and F. prausnitzii with juvenile SpA, and also suggest that the mechanism by which HLA-B27 is associated with SpA may not involve alterations of the microbiota.

Cytoplasmic RNA quality control failure engages mTORC1-mediated autoinflammatory disease.

Inborn errors of nucleic acid metabolism often cause aberrant activation of nucleic acid sensing pathways, leading to autoimmune or autoinflammatory diseases. The SKIV2L RNA exosome is cytoplasmic RNA degradation machinery that was thought to be essential for preventing the self-RNA-mediated interferon (IFN) response. Here, we demonstrate the physiological function of SKIV2L in mammals. We found that Skiv2l deficiency in mice disrupted epidermal and T cell homeostasis in a cell-intrinsic manner independently of IFN. Skiv2l-deficient mice developed skin inflammation and hair abnormality, which were also observed in a SKIV2L-deficient patient. Epidermis-specific deletion of Skiv2l caused hyperproliferation of keratinocytes and disrupted epidermal stratification, leading to impaired skin barrier with no appreciable IFN activation. Moreover, Skiv2l-deficient T cells were chronically hyperactivated and these T cells attacked lesional skin as well as hair follicles. Mechanistically, SKIV2L loss activated the mTORC1 pathway in both keratinocytes and T cells. Both systemic and topical rapamycin treatment of Skiv2l-deficient mice ameliorated epidermal hyperplasia and skin inflammation. Together, we demonstrate that mTORC1, a classical nutrient sensor, also senses cytoplasmic RNA quality control failure and drives autoinflammatory disease. We also propose SKIV2L-associated trichohepatoenteric syndrome (THES) as a new mTORopathy for which sirolimus may be a promising therapy.

Updates in childhood Sjogren's syndrome.

PURPOSE OF REVIEW: Childhood Sjogren's syndrome (cSS) is a rare, chronic autoimmune disease characterized by inflammation of the exocrine glands. cSS is underrecognized because of differences in clinical presentation compared with adults. Until recently, publications describing clinical manifestations in cSS were limited to case reports and case series with small numbers of patients. Diagnostic studies to assess glandular symptoms in adults, are less commonly obtained in children. RECENT FINDINGS: Recent cohort studies describe presenting diagnostic clinical features in large populations of cSS and demonstrate how current classification criteria, used in adults, are not applicable to children. Recurrent parotitis is the consistent predominant manifestation that is inversely correlated with age. Novel salivary biomarkers and salivary gland ultrasonography are important objective measure, which may improve diagnosis and disease monitoring. Standardized treatment recommendations are needed. SUMMARY: Findings from large cohort studies provide a framework for the future development of diagnostic criteria for cSS. Such criteria should incorporate objective measures that are easily obtained in children. Future research to improve understanding of the application of novel biomarkers and imaging and developing consensus on treatment recommendations is needed.

"You Just Have to Keep Going, You Can't Give Up": Coping mechanisms among young adults with lupus transferring to adult care.

INTRODUCTION: Coping mechanisms and emotional regulation are important contributors to psychosocial health during stressful life events. We sought to describe the coping and emotional responses of persons with childhood-onset systemic lupus erythematosus during the transfer from pediatric to adult healthcare. METHODS: Semi-structured in-depth one-on-one interviews were conducted with 13 young women aged 18-24 of minority background who had transferred to adult care in a public hospital system. Thematic analysis was used to identify themes motifs from the data. RESULTS: Participants described the use of (1) problem-focused coping such as the use of clear communication and self-education, (2) adaptive emotion-focused coping such as cognitive reframing and acceptance, (3) social coping including support-seeking, (4) meaning-making coping including positive religious framing and viewing events as learning opportunities for growth, and (5) disengaged coping including denial and social isolation. A range of emotional responses associated with the transfer were described including fear, anger, loss, and feelings of empowerment and excitement. CONCLUSION: Effective coping and emotional regulation are modifiable factors that may impact transfer-related outcomes and psychosocial health. Addressing coping mechanisms is relevant to the optimized transfer to adult care.

Erythroid mitochondrial retention triggers myeloid-dependent type I interferon in human SLE.

Emerging evidence supports that mitochondrial dysfunction contributes to systemic lupus erythematosus (SLE) pathogenesis. Here we show that programmed mitochondrial removal, a hallmark of mammalian erythropoiesis, is defective in SLE. Specifically, we demonstrate that during human erythroid cell maturation, a hypoxia-inducible factor (HIF)-mediated metabolic switch is responsible for the activation of the ubiquitin-proteasome system (UPS), which precedes and is necessary for the autophagic removal of mitochondria. A defect in this pathway leads to accumulation of red blood cells (RBCs) carrying mitochondria (Mito+ RBCs) in SLE patients and in correlation with disease activity. Antibody-mediated internalization of Mito+ RBCs induces type I interferon (IFN) production through activation of cGAS in macrophages. Accordingly, SLE patients carrying both Mito+ RBCs and opsonizing antibodies display the highest levels of blood IFN-stimulated gene (ISG) signatures, a distinctive feature of SLE.

Identifying additional risk factors for arterial and venous thrombosis among pediatric antiphospholipid antibodies carriers.

BACKGROUND: Antiphospholipid antibodies (aPL) have been extensively reported in children, but investigations into thrombotic risks associated with aPL positivity in pediatric patients is scarce. Positive aPL are not uncommon in pediatric connective tissue diseases (CTD), but identification and management of these patients is challenging due to lack of validated criteria and a paucity of data. In this study, we identify potential additional risk factors for thrombosis in a unique cohort of pediatric aPL positive carriers. METHODS: Retrospective chart review was performed on 491 pediatric patients with CTD seen in our institution from 2001 to 2019. Patients without persistently moderate to high titer aPL at least 12 weeks apart were excluded. Univariate analysis was performed to evaluate correlation between different risk factors and thrombotic events. RESULTS: Seventy-one aPL positive children with underlying CTD are included in this cohort. The majority (87%) are female and of Hispanic ethnicity (56%). Mean age of the cohort at the diagnosis of connective tissue disease is 12.7 (SD 2.6) years, and mean age of first positive aPL is 13.3 (SD 2.5) years. Average length of follow-up is 4.3 (SD 2.5) years. Four (5.6%) patients experienced arterial thrombosis, and 11 (15.5%) had venous thrombosis. Fifty-seven (80.3%) patients did not have any thromboembolic events. Among traditional risk factors and signs of endothelial injury, only Raynaud's phenomena demonstrated significant association with arterial thrombosis (OR = 8.4, 95%CI 1.13-111, P = 0.039), and hypertension or anti-hypertensive use demonstrated significant association with venous thrombosis (OR = 8.387, 95%CI 1.2 - 94, P = 0.02). CONCLUSION: Data from our cohort suggest that Raynaud's phenomenon is a potential predictor of arterial thrombosis while the presence of hypertension or anti-hypertensive medication use is a potential predictor of venous thrombosis in aPL positive pediatric carriers. Further studies investigating pediatric aPL profiles and risk factors for development of thrombosis are needed to help guide clinicians in caring for these challenging patients.

Predictors of Adverse outcomes in patients with systemic lupus erythematosus transitioning to adult care.

BACKGROUND: The transition from pediatric to adult care is a vulnerable period for individuals with chronic diseases. We sought to identify risk factors associated with poor outcomes in patients with childhood-onset systemic lupus erythematosus (cSLE) who have transitioned to adult care. METHODS: A retrospective analysis of cSLE patients was performed. Outcomes of interest were development of end-stage renal disease (ESRD) or death and time to first hospitalization following final pediatric rheumatology visit. Multivariable logistic and Cox regression models were used. RESULTS: Of 190 patients with cSLE, 21 (11%) developed ESRD and 9 (5%) died following the final pediatric rheumatology visit. In logistic regression, public insurance, history of Child Protective Services involvement, and an unscheduled hospitalization during the final year in pediatric care were predictive of ESRD or death (odds ratio (95% confidence intervals (CI)) 6.7 (1.5-30.7), 6.6 (2.3-19.1), and 3.2 (1.3-8.3), respectively). Among 114 patients with healthcare utilization data, 53% had a hospitalization in adult care. In Cox regression analysis, a pediatric outpatient opioid prescription was associated with shorter time to adult hospitalization and White or Asian race was associated with longer time to adult hospitalization (hazard ratio (CI) 3.5 (1.7-7.0) and 0.1 (0.03-0.4), respectively). CONCLUSIONS: Risks factors associated with poor outcomes in adult care amongst patients with cSLE include public insurance, history of Child Protective Services involvement, unscheduled care utilization in pediatric care, pediatric outpatient opioid prescription, Black race and Hispanic ethnicity. Efforts to improve long-term outcomes among patients with cSLE should focus on these populations.

Time to First Completed Visit and Health Care Utilization Among Young Adults Transferring From Pediatric to Adult Rheumatologic Care in a Safety-Net Hospital.

OBJECTIVE: The transfer from pediatric to adult care for young adults is a vulnerable period. Our objectives were to quantify the time between the final pediatric and the first adult visit and to evaluate unscheduled utilization in care and progression to end-stage renal disease (ESRD) or death. METHODS: We conducted a retrospective analysis of pediatric patients transferring to a large adult rheumatology clinic. Outcomes included time to first completed adult visit, unscheduled health care utilization (hospitalizations and emergency department [ED] visits), and progression to ESRD or death. Multivariable regression models assessed variables predictive of outcomes of interest. RESULTS: A total of 141 pediatric patients who transferred care were identified: 77% female, 65% Hispanic, and 60% with connective tissue diseases (CTDs). The mean time between final pediatric and first completed adult rheumatology visit was 221 days (range 0-1,207 days). In regression modeling, we found that continued insurance coverage, younger age at referral, and referral from a pediatric rheumatologist were predictive of shorter time to completed adult visit (P < 0.005). Factors associated with hospitalizations and ED visits included CTD diagnosis and Black race (odds ratio [OR] 8.54 [95% confidence interval (95% CI) 1.84-39.58] and 3.04 [95% CI 1.02-9.12] for hospitalizations and OR 3.6 [95% CI 1.59-8.14] and 6.0 [95% CI 1.60-22.69] for ED visits, respectively). ESRD or death occurred among 15% of patients with a CTD. CONCLUSION: In pediatric patients transferring to an adult rheumatology clinic, continued insurance coverage and referral from a pediatric rheumatologist decreased delays in attending an adult visit; CTD and Black race were associated with high rates of unscheduled health care utilization.

Clinical Team Perspectives on the Psychosocial Aspects of Transition to Adult Care for Patients With Childhood-Onset Systemic Lupus Erythematosus.

OBJECTIVE: The transition from pediatric to adult care for youth with childhood-onset systemic lupus erythematosus (SLE) is a vulnerable period. Adverse outcomes during this transition include gaps in care, unscheduled health care utilization, loss of insurance, and high disease activity. The objective of this study was to examine the clinical care teams' perspective on the psychosocial factors associated with transition outcomes, which are poorly understood in this population. METHODS: We conducted in-depth interviews with clinical care team members who interact with childhood-onset SLE patients during transfer from pediatric to adult rheumatology. A semistructured interview guide was used to prompt participants' perspectives about the psychosocial factors associated with the transition process for patients with childhood-onset SLE. Audio recordings were transcribed and analyzed using the constant comparative method. We stopped conducting interviews once thematic saturation was achieved. RESULTS: Thirteen in-depth interviews were conducted. Participants included pediatric rheumatologists (n = 4), adult rheumatologists from both academic and private practice settings (n = 4), nurses (n = 2), a nurse practitioner, a social worker, and a psychologist. We identified several themes deemed by clinical care teams as important during the transition, including the impact of the family, patient resilience and coping mechanisms, the role of mental health and emotional support, and the need for education, peer support, and social connectedness. CONCLUSION: We identified several psychosocial themes that clinical team members believe impact the transition of patients with childhood-onset SLE into adult care. The role of parental modeling, youth resilience, mental health and emotional care, improved childhood-onset SLE education, and structured peer support and social connectedness are highlighted, which may be amenable to interventions.

Mapping systemic lupus erythematosus heterogeneity at the single-cell level.

Patients with systemic lupus erythematosus (SLE) display a complex blood transcriptome whose cellular origin is poorly resolved. Using single-cell RNA sequencing, we profiled ~276,000 peripheral blood mononuclear cells from 33 children with SLE with different degrees of disease activity and 11 matched controls. Increased expression of interferon-stimulated genes (ISGs) distinguished cells from children with SLE from healthy control cells. The high ISG expression signature (ISGhi) derived from a small number of transcriptionally defined subpopulations within major cell types, including monocytes, CD4+ and CD8+ T cells, natural killer cells, conventional and plasmacytoid dendritic cells, B cells and especially plasma cells. Expansion of unique subpopulations enriched in ISGs and/or in monogenic lupus-associated genes classified patients with the highest disease activity. Profiling of ~82,000 single peripheral blood mononuclear cells from adults with SLE confirmed the expansion of similar subpopulations in patients with the highest disease activity. This study lays the groundwork for resolving the origin of the SLE transcriptional signatures and the disease heterogeneity towards precision medicine applications.

Distinct tissue injury patterns in juvenile dermatomyositis auto-antibody subgroups.

INTRODUCTION: Juvenile dermatomyositis (JDM) can be classified into clinical serological subgroups by distinct myositis-specific antibodies (MSAs). It is incompletely understood whether different MSAs are associated with distinct pathological characteristics, clinical disease activities, or response to treatment. METHODS: We retrospectively reviewed clinicopathological data from consecutive JDM patients followed in the pediatric rheumatology clinic at a single center between October 2016 and November 2018. Demographics, clinical data, and laboratory data were collected and analyzed. Detailed muscle biopsy evaluation of four domains (inflammation, myofiber, vessels, and connective tissue) was performed, followed by statistical analysis. RESULTS: Of 43 subjects included in the study, 26 (60.5%) had a detectable MSA. The most common MSAs were anti-NXP-2 (13, 30.2%), anti-Mi-2 (7, 16.3%), and anti-MDA-5 (5, 11.6%). High titer anti-Mi-2 positively correlated with serum CK > 10,000 at initial visit (r = 0.96, p = 0.002). Muscle biopsied from subjects with high titer anti-Mi-2 had prominent perifascicular myofiber necrosis and perimysial connective tissue damage that resembled perifascicular necrotizing myopathy, but very little capillary C5b-9 deposition. Conversely, there was no positive correlation between the levels of the anti-NXP-2 titer and serum CK (r = - 0.21, p = 0.49). Muscle biopsies from patients with anti-NXP-2 showed prominent capillary C5b-9 deposition; but limited myofiber necrosis. Only one patient had anti-TIF1γ autoantibody, whose muscle pathology was similar as those with anti-NXP2. All patients with anti-MDA-5 had normal CK and near normal muscle histology. CONCLUSIONS: Muscle biopsy from JDM patients had MSA specific tissue injury patterns. These findings may help improve muscle biopsy diagnosis accuracy and inform personalized treatment of JDM.