Human cerebrospinal fluid monoclonal CASPR2 autoantibodies induce changes in electrophysiology, functional MRI, and behavior in rodent models.

Anti-contactin associated protein receptor 2 (CASPR2) encephalitis is a severe autoimmune encephalitis with a variable clinical phenotype including behavioral abnormalities, cognitive decline, epileptic seizures, peripheral nerve hyperexcitability and neuropathic pain. The detailed mechanisms of how CASPR2 autoantibodies lead to synaptic dysfunction and clinical symptoms are largely unknown. Aiming for analyses from the molecular to the clinical level, we isolated antibody-secreting cells from the cerebrospinal fluid of two patients with CASPR2 encephalitis. From these we cloned four anti-CASPR2 human monoclonal autoantibodies (mAbs) with strong binding to brain and peripheral nerves. All were highly hypermutated and mainly of the IgG4 subclass. Mutagenesis studies determined selective binding to the discoidin domain of CASPR2. Surface plasmon resonance revealed affinities with dissociation constants KD in the pico- to nanomolar range. CASPR2 mAbs interrupted the interaction of CASPR2 with its binding partner contactin 2 in vitro and were internalized after binding to CASPR2-expressing cells. Electrophysiological recordings of rat hippocampal slices after stereotactic injection of CASPR2 mAbs showed characteristic afterpotentials following electrical stimulation. In vivo experiments with intracerebroventricular administration of human CASPR2 mAbs into mice and rats showed EEG-recorded brain hyperexcitability but no spontaneous recurrent seizures. Behavioral assessment of infused mice showed a subtle clinical phenotype, mainly affecting sociability. Mouse brain MRI exhibited markedly reduced resting-state functional connectivity without short-term structural changes. Together, the experimental data support the direct pathogenicity of CASPR2 autoantibodies. The minimally invasive EEG and MRI techniques applied here may serve as novel objective, quantifiable tools for improved animal models, in particular for subtle neuropsychiatric phenotypes or repeated measurements.

Detection of systemic autoimmune diseases in an ongoing assessment program for hand arthralgias. A comparative analysis with inflammatory and non-inflammatory arthropathies.

INTRODUCTION: Arthralgias are prevalent in systemic autoimmune rheumatic diseases (SARD), emphasizing the need for early recognition. This study aimed to estimate SARD frequency and compare clinical, laboratory, and imaging findings among SARD, non-inflammatory arthralgia (NIA), and RA in patients with hand arthralgias. METHODS: A prospective evaluation program included individuals aged ≥18 with hand arthralgias. Baseline assessments covered clinical, laboratory, ultrasound, and radiography. Follow-up diagnoses categorized patients into SARD, NIA, and RA groups. Comparison between groups was performed using parametric and non-parametric tests. Two multivariate logistic regression analyzes were performed using the final diagnosis of SARD as the dependent variable (NIA and RA). ROC curves were calculated in those variables that presented an independent association in the multivariate analysis. RESULTS: Among 1053 patients, 9.6% were SARD (SLE 47%). Comparing SARD with NIA revealed higher CRP levels, power Doppler, less rhizarthrosis in ultrasound, and more ANA positivity in SARD patients. Distinct differences were observed between SARD and RA patients in terms of pain levels, swollen joints, metacarpophalangeal involvement and morning symptoms. Diagnostic markers demonstrated specific sensitivities and specificities: ANA for SARD versus NIA (82%, 34%), US not finding rhizarthrosis for SARD versus NIA (66%, 85%), CRP (cut-off >2.5 mg/L) sensitivity 52%, specificity 60%, AUC 0.62, RA antibodies (RF, 11 IU/mL) sensitivity 76%, specificity 74%, AUC 0.8, ACPA (1.25) sensitivity 50%, specificity 98%, AUC 0.7, ANA+ sensitivity 95%, specificity 32%, AUC 0.7, and US absence of synovitis sensitivity 82%, specificity 34%, AUC 0.75. CONCLUSION: This study highlights distinct clinical, laboratory, and imaging features differentiating SARD-related hand arthralgia from non-SARD hand arthralgia and RA.

High serum prevalence of autoreactive IgG antibodies against peripheral nerve structures in patients with neurological post-COVID-19 vaccination syndrome.

Background: Patients suffering from neurological symptoms after COVID-19 vaccination (post-COVID-19 vaccination syndrome (PCVS)) have imposed an increasing challenge on medical practice, as diagnostic precision and therapeutic options are lacking. Underlying autoimmune dysfunctions, including autoantibodies, have been discussed in neurological disorders after SARS-CoV-2 infection and vaccination. Here, we describe the frequency and targets of autoantibodies against peripheral nervous system tissues in PCVS. Methods: Sera from 50 PCVS patients with peripheral neurological symptoms after COVID-19 vaccination and 35 vaccinated healthy controls were used in this study. IgG autoreactivity was measured via indirect immunofluorescence assays on mouse sciatic nerve teased fibers. The frequencies of autoantibodies were compared between groups using Fisher's exact test. Serum anti-ganglioside antibodies were measured in ganglioside blots. Autoantibody target identification was performed using immunoprecipitation coupled to mass spectrometry. Subsequent target confirmation was conducted via cell-based assays and ELISA. Results: Compared with controls, PCVS patients had a significantly greater frequency of autoantibodies against peripheral nervous system structures (9/50(18%) vs 1/35(3%); p=0.04). Autoantibodies bound to paranodes (n=5), axons (n=4), Schmidt-Lanterman incisures (n=2) and Schwann cell nuclei (n=1). Conversely, antibodies against gangliosides were absent in PCVS patients. Target identification and subsequent confirmation revealed various subunits of neurofilaments as well as DFS-70 as autoantibody epitopes. Conclusion: Our data suggest that autoantibodies against nervous system tissue could be relevant in PCVS patients. Autoantibodies against neurofilaments and cell nuclei with so far non-established links to this disease spectrum should be further elucidated to determine their biomarker potential.

Comparative Analysis of Laboratory-Scale Immunoglobulin G Purification Methods from Human Serum.

Immunoglobulin G (IgG) purification is a critical process for evaluating its role in autoimmune diseases, which are defined by the occurrence of autoantibodies. Affinity chromatography with protein G is widely considered to be the optimal technique for laboratory-scale purification. However, this technique has some limitations, including the exposure of IgG to low pH, which can compromise the quality of the purified IgG. Here, we show that alternative methods for IgG purification are possible while maintaining the quality of IgG. Different techniques for IgG purification from serum were evaluated and compared with protein G-based approaches: Melon Gel, caprylic acid-ammonium sulfate (CAAS) precipitation, anion-exchange chromatography with diethylamino ethyl (DEAE) following ammonium sulfate (AS) precipitation, and AS precipitation alone. The results demonstrated that the purification yield of these techniques surpassed that of protein G. However, differences in the purity of IgG were observed using GeLC-MS/MS. The avidity of purified IgG against selected targets (SARS-CoV-2 and topoisomerase-I) was similar between purified IgG obtained using all techniques and unpurified sera. Our work provides valuable insights for future studies of IgG function by recommending alternative purification methods that offer advantages in terms of yield, time efficiency, cost-effectiveness, and milder pH conditions than protein G.

Pathogenic relevance of antibodies against desmoglein 3 in patients with oral lichen planus.

BACKGROUND AND OBJECTIVES: Oral lichen planus (OLP) is a T cell driven disorder that significantly impairs patients' quality of life. Previous reports suggest that both cellular and humoral activities against desmoglein (dsg) 1 and 3 may be involved in OLP pathogenesis. Here, we aim to analyze the frequency of occurrence and pathological significance of anti-dsg antibodies in a large cohort of OLP patients. MATERIALS AND METHODS: OLP patients were screened for anti-dsg antibodies by enzyme-linked immunosorbent assay in three tertiary referral centers. OLP sera with anti-dsg antibodies were further analyzed by Western blot and dispase-based keratinocyte dissociation assay (DDA) to identify the targeted dsg ectodomains and to assess their pathogenicity. RESULTS: Of 151-screened individuals with OLP, only four patients (2.6%) with erosive OLP showed serum IgG against dsg1/3. Western blot analysis with recombinant dsg3 ectodomains revealed preferential recognition of the extracellular domain 5. By DDA with spontaneously immortalized human keratinocytes, none of the sera from these four patients induced acantholysis. CONCLUSIONS: Activation of humoral immunity occurs prevalently in patients with erosive OLP, probably due to epitope spreading. OLP serum antibodies are unable to induce loss of intercellular adhesion in vitro, strongly suggesting that they are not disease causing but rather an epiphenomenon.

Pigmented paravenous retinochoroidal atrophy and retinitis pigmentosa-like phenotype in the same patient: A case series.

INTRODUCTION: Concomitant manifestation of PPRCA in one eye and RP-like retinopathy in the fellow eye is a rare clinical entity, with limited published descriptions to date. The aim of this study is to describe comprehensive clinical evaluations and long-term follow-up of three patients affected by this clinical picture. METHODS: Three patients with concurrent PPRCA and RP-like retinopathy were prospectively re-evaluated and comprehensive assessments were performed. The progression of disease was assessed by comparing best corrected visual acuity (BCVA) and ellipsoid zone (EZ) width with data available from each patient's medical charts and previous SD-OCT scans. Blood samples were collected and tested to rule out autoimmune or infectious ocular diseases, for testing anti-retinal autoantibodies (ARAs) and for genetic analysis. RESULTS: Reduction in BCVA and a progressive concentric loss of the EZ band over time were detected in the eye with RP-like phenotype in all three patients, while in the eye with PPRCA none of the patients showed significant changes in BCVA and only one patient showed a progressive reduction of the EZ width. No clear etiology has been identified. Two or more ARAs subtypes were detected in two out of three patients. CONCLUSIONS: PPRCA was demonstrated to be a non-progressive or slowly progressive disease, instead the eye with RP-like phenotype showed a progressive visual impairment, highlighting the importance of shedding light on this condition. Its etiology remains unclear: a genetic trait with different phenotype between the two eyes is conceivable, as well as a potential role of ARAs.

Type 1 diabetes mellitus following COVID-19 vaccination: a report of two cases and review of literature.

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection, which led to the coronavirus 2019 (COVID-19) pandemic, has promoted the development of novel therapeutic agents and vaccines to combat the global spread of the virus. While the COVID-19 vaccines approved thus far have proven to be effective in clinical settings, there have been reports of autoimmune diseases occurring following vaccination, including autoimmune/inflammatory syndrome induced by adjuvant syndrome. We herein report two cases of type 1 diabetes mellitus that occurred following COVID-19 vaccination and provide a literature review. Both cases received multiple vaccinations as recommended to ensure optimal antibody titers. Moreover, the HLA associated with susceptibility to type 1 diabetes was prototypic in both cases. This indirect evidence suggests that the COVID-19 vaccines may be implicated in the pathogenesis of type 1 diabetes. Further case reports to establish a clearer understanding of a potential association are warranted. Supplementary Information: The online version contains supplementary material available at 10.1007/s13340-024-00695-9.

Spontaneous Hypoglycaemia due to Insulin Autoimmune Syndrome in Six Cases, Response to Steroid Therapy and Rituximab.

Introduction: Dr. Hirata of Japan first described insulin autoimmune syndrome (IAS) in 1970. Seven hundred ninety-five cases of this rare syndrome have been reported from Japan and China and 29 from India. IAS has the following characteristic features 1) severe spontaneous attacks of hyperinsulinemic hypoglycaemia, 2) high total immunoreactive insulin levels, 3) elevated insulin autoantibody (IAA) titres, 4) no prior exposure to exogenous insulin, and 5) no pathological abnormalities of the pancreatic islet cells. Methods: We treated six cases of IAS with high doses of prednisolone for 4-6 weeks and then gradually reduced the doses. Diagnosis of IAS was established by documenting Whipple's triad of symptoms and signs of hypoglycaemia, blood sugar <55 mg/dl, improvement of symptoms with dextrose infusion, inappropriately increased insulin levels >3 uU/ml, C-peptide levels >0.6 ng/ml, and increased titres of anti-insulin autoantibodies. Insulinoma and non-pancreatic tumours were ruled out by CECT (contrast-enhanced computerised tomography) or MRI (magnetic resonance imaging) of the abdomen and if necessary endoscopic ultrasonography and gallium 68 Dotanoc PET (positron enhanced tomography). Autoimmune screening and serum electrophoresis were done to rule out multiple myeloma. Monitoring of the patient's blood sugars was done by the laboratory, glucometer readings, and a freestyle libre glucose monitoring system. Results: Remission of hypoglycaemic episodes, hyperglycaemic episodes, and marked reduction of serum insulin and insulin autoantibodies in four out of six patients with diet therapy and steroids. Two patients resistant to steroids were treated with rituximab successfully. Patient 6 developed serious complications of cytomegalovirus and Pneumocystis carnii after rituximab, which were treated successfully. Conclusion: A careful history including recent infections, medications, and vaccinations provides vital clues in the evaluation. An increased awareness of IAS will prevent unnecessary and costly investigations and surgery. Although it is often self-remitting, steroids are contributory in severe cases. Immunosuppressives are used successfully in cases refractory to steroids. Continuous glucose monitoring system (CGMS), by freestyle libre glucose monitoring system, provided real-time blood sugar values, total time in hypoglycaemia, and total time in the range (TIR), which proved very valuable in managing IAS patients. Low CGMS values should be corroborated clinically and with laboratory or glucometer values.

Presence of sputum IgG against eosinophilic inflammatory proteins in asthma.

Background: Sputum immunoglobulin G (Sp-IgG) has been discovered to induce cytolytic extracellular trap cell death in eosinophils, suggesting a potential autoimmune mechanism contributing to asthma. This study aimed to explore the potential origin of Sp-IgG and identify clinically relevant subtypes of Sp-IgG that may indicate autoimmune events in asthma. Methods: This study included 165 asthmatic patients and 38 healthy volunteers. We measured Sp-IgG and its five subtypes against eosinophil inflammatory proteins (Sp-IgGEPs), including eosinophil peroxidase, eosinophil major basic protein, eosinophil-derived neurotoxin, eosinophil cationic protein, and Charcot-Leyden Crystal protein in varying asthma severity. Clinical and Mendelian randomization (MR) analyses were conducted. A positive Sp-IgGEPs signature (Sp-IgGEPs+) was defined when any of the five Sp-IgGEPs values exceeded the predefined cutoff thresholds, calculated as the mean values of healthy controls plus twice the standard deviation. Results: The levels of Sp-IgG and Sp-IgGEPs were significantly elevated in moderate/severe asthma than those in mild asthma/healthy groups (all p < 0.05). Sp-IgG levels were positively correlated with airway eosinophil and Sp-IgGEPs. MR analysis showed causality between eosinophil and IgG (OR = 1.02, 95%CI = 1.00-1.04, p = 0.020), and elevated IgG was a risk factor for asthma (OR = 2.05, 95%CI = 1.00-4.17, p = 0.049). Subjects with Sp-IgGEPs+ exhibited worse disease severity and served as an independent risk factor contributing to severe asthma (adjusted-OR = 5.818, adjusted-95% CI = 2.193-15.431, adjusted-p < 0.001). Receiver operating characteristic curve analysis demonstrated that the combination of Sp-IgGEPs+ with non-allergic status, an ACT score < 15, and age ≥ 45 years, effectively predicted severe asthma (AUC = 0.84, sensitivity = 86.20%, specificity = 67.80%). Conclusion: This study identifies a significant association between airway eosinophilic inflammation, Sp-IgG, and asthma severity. The Sp-IgGEPs panel potentially serves as the specific biomarker reflecting airway autoimmune events in asthma.

The immunology of B-1 cells: from development to aging.

B-1 cells have intricate biology, with distinct function, phenotype and developmental origin from conventional B cells. They generate a B cell receptor with conserved germline characteristics and biased V(D)J recombination, allowing this innate-like lymphocyte to spontaneously produce self-reactive natural antibodies (NAbs) and become activated by immune stimuli in a T cell-independent manner. NAbs were suggested as "rheostats" for the chronic diseases in advanced age. In fact, age-dependent loss of function of NAbs has been associated with clinically-relevant diseases in the elderly, such as atherosclerosis and neurodegenerative disorders. Here, we analyzed comprehensively the ontogeny, phenotypic characteristics, functional properties and emerging roles of B-1 cells and NAbs in health and disease. Additionally, after navigating through the complexities of B-1 cell biology from development to aging, therapeutic opportunities in the field are discussed.

Small Molecules Targeting GRP78 Mitigate Anti- GRP78 Autoantibody-Mediated Tissue Factor Procoagulant Activity in Cultured Endothelial Cells.

BACKGROUND: The 78-kDa glucose-regulated protein (GRP78) expressed on the cell surface (csGRP78) has been reported to regulate tissue factor procoagulant activity (TF PCA) in lesion-resident endothelial cells (ECs), which is further enhanced by circulating anti-GRP78 autoantibodies that bind to the Leu98-Leu115 epitope in GRP78. OBJECTIVES: Determine the effects of the engagement of the anti-GRP78 autoantibody to cell surface GRP78 on endothelial cells and the underlying mechanisms that impact TF PCA. METHODS: Immunofluorescent staining was used to determine the presence of csGRP78 in TNFα-treated endothelial cells. An established TF PCA assay was used to evaluate human ECs following treatment with anti-GRP78 autoantibodies. The Fura 2-AM assay was used to quantify changes in intracellular Ca2+ levels. Small molecules predicted to bind csGRP78 were identified using artificial intelligence. ELISAs were used to assess the ability of these GRP78 binders to mitigate TF activity and interfere with the autoantibody/csGRP78 complex. RESULTS: In TNFα-treated ECs, anti-GRP78 autoantibodies increased TF PCA. This observation was further enhanced by ER-stress-induced elevation of csGRP78 levels. Anti-GRP78 autoantibody treatment increased intracellular Ca2+ levels. Sequestering the anti-GRP78 autoantibody with a conformational peptide or blocking with heparin molecules attenuated anti-GRP78 autoantibody-induced TF PCA. We identified B07*, a GRP78 binder that diminished anti-GRP78 autoantibody-induced TF PCA on ECs. CONCLUSIONS: These findings show how anti-GRP78 autoantibodies enhance TF PCA that contributes to thrombosis and identify novel GRP78 binders that represent a potential novel therapeutic strategy for treating and managing atherothrombotic disease.

Acute presentation of autoimmune hepatitis -from acute hepatitis to ALF and ACLF.

Acute presentation of autoimmune hepatitis (AIH) occurs in 22-43% of all AIH cases, and is not a rare condition. Rather than constituting a single disease entity, it represents a clinical spectrum characterized by considerable variability in severity and the presence of preexisting chronic AIH. This spectrum ranges from acute AIH and acute severe AIH to AIH presenting as acute liver failure (ALF) or as acute-on-chronic liver failure (ACLF), contingent upon factors such as coagulopathy, hepatic encephalopathy, and underlying liver disease. Diagnosing acute presentation of AIH can be particularly challenging due to the frequent absence of classical serologic signatures such as autoantibodies and elevated IgG levels. Histopathological examination remains essential for diagnosis, typically necessitating percutaneous or transjugular liver biopsy. Corticosteroids (CS) are recommended for the management of acute AIH and acute severe AIH with coagulopathy. However, the therapeutic response to CS should be meticulously monitored. If a poor response is anticipated, liver transplantation (LT) should be promptly considered. For AIH presenting as ALF with encephalopathy or ACLF with advanced underlying liver disease, LT is generally advised. Nonetheless, there is potential for a trial of CS therapy in cases of ALF with low MELD scores or ACLF without encephalopathy. This review provides an overview of the latest findings concerning the definition, diagnosis, and management of acute presentation of AIH.

Complete Description of the Three Pathways of the Complement System in a Series of 430 Patients with Rheumatoid Arthritis.

The complement (C) system is implicated in the etiopathogenesis of rheumatoid arthritis (RA). However, there is a lack of studies characterizing all three C pathways in RA patients. This study aimed to evaluate the association between an in-depth examination of the C system and RA patient characteristics, focusing on disease activity and the presence of rheumatoid factor and anti-citrullinated protein autoantibodies (ACPA). In a cohort of 430 RA patients, functional assays of the three C pathways (classical, alternative, and lectin) and serum levels of their components were assessed. Components included C1q (classical); factor D and properdin (alternative); lectin (lectin); C1-inhibitor; C2, C4, and C4b (classical and lectin); C3, C3a, and C4b (common); and C5, C5a, and C9 (terminal). A multivariable linear regression analysis showed significant positive correlations between C-reactive protein and C system proteins and functional assays, especially in the terminal and common pathways. Disease activity, measured by scores with or without acute phase reactants, positively correlated with the classical pathway functional test and terminal pathway products. Conversely, rheumatoid factor or ACPA presence was associated with lower classical pathway values and decreased C3a and C4b levels, suggesting complement depletion. In conclusion, RA disease activity increases C molecules and functional complement assays, while rheumatoid factor or ACPA positivity is linked to C consumption. Our study offers a detailed analysis of the complement system's role in RA, potentially guiding the development of more targeted and effective treatment strategies.

Leptin/Ghrelin Axis and Antibodies Reactive to Both Hormones in Relation to Metabolic Syndrome Components in Mexican Children.

Background: Metabolic syndrome (MetS) in children is a rising health issue that is strongly associated with cardiovascular diseases and type 2 diabetes mellitus development. Low-affinity antibodies reactive to leptin and ghrelin are suggested to regulate hormone stability and function; nevertheless, the role of the leptin/ghrelin axis and antibodies reactive to both hormones in relation to MetS or its components in the pediatric population remains unknown. Methods: Fifty-eight children (7-12 years) were included and categorized according to the presence of one or more criteria for the diagnosis of MetS or according to body mass index. Body composition, biochemical variables, and metabolic risk indexes were determined. Antibodies reactive to leptin and ghrelin were quantified by an in-house enzyme-linked immunosorbent assay test. Ratios of leptin/ghrelin hormones and anti-leptin/anti-ghrelin immune complexes were obtained. Results: The biochemical variables glucose (P = 0.0009), insulin (P = 0.0001), leptin (P = 0.0036), HOMA-IR (homeostatic model assessment for insulin resistance) (P < 0.0001), and plasma atherogenic index (P < 0.0001) were significantly higher in children with two or three components of MetS (MetS 2-3) in comparison to children with none or one component (MetS 0-1). Ratios of leptin/ghrelin (P = 0.0307) and anti-leptin/anti-ghrelin immune complexes (P = 0.0338) were higher in MetS 2-3 group versus MetS 0-1 group. In MetS 2-3 group, both insulin (r = 0.4361, P = 0.0293) and HOMA-IR (r = 0.4761, P = 0.0161) were positively correlated with the leptin/ghrelin hormone ratio. Conclusions: The higher leptin/ghrelin hormone ratio scores observed in MetS 2-3 group, along with their correlation with insulin levels and HOMA-IR, highlight the role of leptin and ghrelin on insulin sensitivity and metabolic regulation. An increased ratio of anti-leptin/anti-ghrelin immune complexes suggests affinity changes in these antibodies that may lead to alterations in hormone function.

NORSE/FIRES: how can we advance our understanding of this devastating condition?

Introduction: New onset refractory status epilepticus (NORSE) is a rare and devastating condition characterised by the sudden onset of refractory status epilepticus (RSE) without an identifiable acute or active structural, toxic, or metabolic cause in an individual without a pre-existing diagnosis of epilepsy. Febrile infection-related epilepsy syndrome (FIRES) is considered a subcategory of NORSE and presents following a febrile illness prior to seizure onset. NORSE/FIRES is associated with high morbidity and mortality in children and adults. Methods and results: In this review we first briefly summarise the reported clinical, paraclinical, treatment and outcome data in the literature. We then report on existing knowledge of the underlying pathophysiology in relation to in vitro and in vivo pre-clinical seizure and epilepsy models of potential relevance to NORSE/FIRES. Discussion: We highlight how pre-clinical models can enhance our understanding of FIRES/NORSE and propose future directions for research.

Autoantibodies and damage in patients with idiopathic inflammatory myopathies: A longitudinal multicenter study from the MYONET international network.

OBJECTIVE: To study the trajectories of changes in damage over time and explore associations with autoantibody defined subgroups using a large international cohort of patients with idiopathic inflammatory myopathies (IIM). METHODS: Data from the MYONET registry, including patients who were tested for autoantibodies and had at least one assessment of damage using the Myositis Damage Index (MDI), were analyzed. Patients were sub-grouped according to their autoantibody profiles (myositis-specific, myositis-associated, or seronegative). The index date was defined as the time point for the first registered MDI assessment. The longitudinal trajectories of damage with autoantibody status as the main predictor were analyzed using linear mixed models. RESULTS: A total of 757 adult patients were included in this study. Each year of disease duration since diagnosis had an estimated MDI score increase of 0.16 units for the seronegative group (reference). Compared with the seronegative group as reference, patients with dermatomyositis-specific autoantibodies developed less damage per year of follow-up since diagnosis (average 0.08 less score, P = 0.04), whereas patients with anti-PM/Scl autoantibodies developed more damage per year of follow-up since diagnosis (average 0.28 higher score, P = 0.03) independent of sex and age at diagnosis. The seronegative subgroup and the immune-mediated necrotizing myopathy autoantibody subgroup had the strongest correlation between severity of muscle damage and HAQ-DI scores at five years of follow-up, rho=0.84, P < 0.001 and rho=0.72, P < 0.001, respectively. CONCLUSION: Our study is the first to describe patterns and trajectories of change in damage over time in relation to autoantibody defined subgroups in a large international multicenter cohort of patients with IIM. Patients with anti-PM/Scl scored a greater extent of damage, whereas patients with dermatomyositis-specific antibodies had less damage than seronegative patients. Severity in muscle damage had moderate to strong correlation with functional disability among the IMNM and seronegative subgroups with lower correlations for the other subgroups. These findings suggest that autoantibodies may be useful predictors of long-term damage.

The intersection of microbiome and autoimmunity in long COVID-19: Current insights and future directions.

Long COVID-19 affects a significant percentage of patients and is characterized by a wide range of symptoms, including weariness and mental fog as well as emotional symptoms like worry and sadness. COVID-19 is closely linked to the autoimmune disorders that are becoming more prevalent worldwide and are linked to immune system hyperactivation, neutrophil extracellular trap (NET) development, and molecular mimicry pathways. Long-term COVID-related autoimmune responses include a watchful immune system referring to the ability of immune system to constantly monitor the body for signs of infection, disease, or abnormal cells; altered innate and adaptive immune cells, autoantigens secreted by living or dead neutrophils, and high concentrations of autoantibodies directed against different proteins. The microbiome, which consists of billions of bacteria living in the human body, is essential for controlling immune responses and supporting overall health. The microbiome can affect the course of long COVID-associated autoimmunity, including the degree of illness, the rate of recovery, and the onset of autoimmune reactions. Although the precise role of the microbiome in long COVID autoimmunity is still being investigated, new studies indicate that probiotics, prebiotics, and dietary changes-interventions that target the microbiome-may be able to reduce autoimmune reactions and enhance long-term outcomes for COVID-19 survivors. More research is required to precisely understand how the microbiome affects COVID-19-related autoimmunity and to create tailored treatment plans.

Next-generation rheumatoid factor assay provides improved predictive power for the development of arthritis in patients at risk.

OBJECTIVE: Rheumatoid arthritis (RA) is characterised by the presence of autoantibodies, among which those targeting the constant region of immunoglobulin G (IgG), called rheumatoid factors (RF). Despite this link, RFs can also be found in other disorders and the healthy population, which hampers its use as a diagnostic tool. We recently showed that a subset of RA-derived RFs target a distinct epitope on the IgG-Fc, a feature that is currently not used in the clinic. METHODS: We determined immunoglobulin M (IgM)-RF levels specific against an RA-associated epitope (using our engineered next-generation RF antigen 'T3-17') in a prospective cohort of 475 patients with seropositive (for IgM-RF or aCCP) arthralgia that were followed for 5 years or until the development of arthritis. RESULTS: The presence of RFs targeting T3-17 was more strongly associated with progression to arthritis in comparison to traditional RF measurements. Within the group of patients positive for T3-17 RF the risk of arthritis development was increased as compared with wild-type RF, HR=3.2 (95% CI 2.4 to 4.3) vs HR=2.2 (95% CI 1.7 to 3.0). Predictive power of T3-17 RF was improved in combination with aCCP titres, HR=6.4 (4.7-8.7) vs HR=5.1 (3.9-6.8). This combination performed better than aCCP detection on its own. CONCLUSION: The detection of disease-specific RF is feasible and seems to improve the diagnostic power of RF and should be considered to be implemented in the clinic.

Anti-IL12p40 autoantibodies in a teenage girl with multiple recurrent abscesses.

More frequent among adults, phenocopies may be caused by somatic mutations or anti-cytokine autoantibodies, mimicking the phenotypes of primary immunodeficiencies. A fourteen-year-old girl was referred for a two-year history of weight loss and multiple recurrent abscesses, complicated recurrent pneumonia, pyelonephritis, osteomyelitis, and septic shock, without fever. She had started with nausea, hyporexia, and weight loss, then with abscesses in her hands, knee, ankle, and spleen. She also developed a rib fracture and left thoracic herpes zoster. The patient was cachectic, with normal vital signs, bilateral crackles on chest auscultation, tumefaction of the knee joint, and poorly healed wounds in hands and chest, oozing a yellowish fluid. Chest computed tomography revealed multiple bilateral bronchiectases. Laboratory workup reported chronic anemia, leukocytosis, neutrophilia, mild lymphopenia, thrombocytosis, pan-hypergammaglobulinemia, and elevated acute serum reactants. Lymphocyte subsets were low but present. Mycobacterium tuberculosis was detected via polymerase chain reaction in a bone biopsy specimen from ankle osteomyelitis. Whole-exome sequencing failed to identify a monogenic defect. Interleukin-12 was found markedly elevated in the serum of the patient. Phosphorylation of STAT4, induced by increasing doses of IL-12, was neutralized by patient serum, confirming the presence of anti-IL12 autoantibodies. IL-12 and IL-23 are crucial cytokines in the defense against intracellular microorganisms, the induction of interferon-gamma production by lymphocytes, and other inflammatory functions. Patients who develop neutralizing serum autoantibodies against IL12 manifest late in life with weight loss, multiple recurrent abscesses, poor wound healing, and fistulae. Treatment with anti-CD20 monoclonal antibodies was effective.

Concordance between radioimmunoassay and fixed cell-based assay in subjects without myasthenia gravis: optimizing the diagnostic approach.

BACKGROUND AND PURPOSE: Acetylcholine receptor antibody (AChR-Ab) detection is crucial in myasthenia gravis (MG) diagnosis and, currently, the radioimmunoassay (RIA) is the gold standard. However, RIA may detect AChR-Ab against nonpathogenic intracellular epitopes. In this study, we performed fixed cell-based assay (F-CBA) in RIA-AChR-Ab positive subjects without MG symptoms, to assess whether F-CBA could show a higher specificity compared to RIA in detecting pathogenic Abs. METHODS: We reviewed medical records of patients referred to our MG outpatient clinic because of RIA-AChR-Ab detection. MG diagnosis was based on clinical examination, electrophysiology and Ab detection. AChR-Abs were tested by RIA in the whole cohort. Serum samples from RIA-positive asymptomatic subjects were retested by F-CBA. RESULTS: Of 605 subjects who tested RIA-AChR-Ab positive, MG diagnosis was confirmed in 599. Six subjects were RIA-AChR-Ab positive although they had never had MG symptoms; in four of these subjects AChR-Abs were not detected by F-CBA, whereas the remaining two (both non-MG thymoma cases) were positive also by F-CBA. CONCLUSIONS: RIA false positivity for AChR-Ab is very rare. Previous literature has demonstrated that F-CBA has higher sensitivity than RIA for MG, especially in ocular cases. Our preliminary results show that, in rare instances, F-CBA may be more specific than RIA for MG diagnosis.