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PubMed2026

Pathogenic properties of myasthenia gravis AChR autoantibodies associate with clinical response to efgartigimod.

BACKGROUND: Efgartigimod, a neonatal Fc receptor (FcRn) blocker, effectively reduces total IgG, including pathogenic acetylcholine receptor (AChR) autoantibodies in myasthenia gravis (MG); however, clinical responses vary. To investigate this variability, we studied how efgartigimod impacts AChR-specific autoantibody profiles and associated pathogenic mechanisms, including complement activation, AChR internalisation and ACh-binding site blockade. METHODS: Serum samples (N=150) were sourced from 50 AChR autoantibody-positive generalised MG patients participating in the phase 3 ADAPT study, randomised to receive efgartigimod (N=40) or placebo (N=10) in cycles of 4-weekly infusions. Samples were collected at baseline, day 29 and day 57 during the first cycle. Live cell-based assays quantified AChR-specific IgG subclasses and isotypes and assessed their capacity to mediate pathomechanisms. RESULTS: Efgartigimod decreased all detectable AChR-specific IgG subclasses. At baseline, AChR autoantibody-mediated C3b deposition, AChR internalisation and ACh-binding site blockade were detected in 42 (84%), 41 (82%) and 10 (20%) patients, respectively. After 4-weekly infusions of efgartigimod, the magnitude of all three pathomechanisms was significantly decreased. However, the extent of this reduction varied across individuals. Double responders on both MG-activities of daily living and quantitative MG scores demonstrated a greater reduction in complement activity and AChR internalisation compared with patients who responded on only one score or were double non-responders. In addition, efgartigimod reduced IgG-dependent IgM binding to AChR. CONCLUSIONS: These findings suggest that clinical efficacy may be more closely associated with functional modulation of the AChR-specific autoantibodies than with their absolute quantity alone. These results support the evaluation of mechanistic pathway monitoring as a potential strategy to predict or guide efgartigimod treatment response.

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PubMed2026

Thyroid-joint crosstalk: a systematic review and meta-analysis of thyroid autoimmunity and dysfunction in juvenile idiopathic arthritis.

BACKGROUND: Recent observational studies outlined the concomitant presence of autoimmune diseases in children with juvenile idiopathic arthritis (JIA), including endocrine autoimmunity. Despite the growing evidence of thyroid involvement in JIA, available data are heterogeneous and fragmented. We aimed to systematically review the available evidence on the prevalence of thyroid autoantibody positivity and thyroid dysfunction in patients with JIA. METHODS: PubMed/Medline, Cochrane, and Scopus databases were approached to identify studies reporting data on thyroid autoantibody positivity and dysfunction in children with JIA. RESULTS: A total of 15 studies were included in the final analysis, encompassing 19 015 children with JIA (13 225 females, 69.6%) with a weighted mean age of 8.0 years (range 1.8-21 years). The pooled prevalence estimates of antithyroid antibody positivity and thyroid dysfunction were 0.04 (95% CI: 0.03-0.05) and 0.04 (95% CI: 0.03-0.08), respectively. The risk difference for thyroid autoantibody positivity between children with JIA and controls was 0.08 (95% CI: 0.02-0.14). Possible risk factors were analyzed: the presence of family history for thyroid autoimmune disease (odds ratio - OR 3.91, 95% CI 1.86-8.25), concurrent Antinuclear Antibodies (ANA) positivity (OR 1.62, 95% CI 1.13-2.31), and older age (MD 2.10 years, 95% CI 1.32-2.89) were associated with thyroid autoantibody positivity and/or thyroid dysfunction in children with JIA. No significant difference emerged for the specific JIA form. CONCLUSION: Thyroid dysfunction may be detected in children with JIA, with a significant risk difference in comparison to healthy controls. Specific clinical characteristics, such as family history, ANA positivity, and older age at JIA onset, may suggest which patients should benefit from thyroid autoantibody screening.

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PubMed2026

Associations Between Antiparietal Cell Antibody Values and Atrophy in a South and Southeast Asian General Population.

GOALS: To investigate the association between atrophy severity and antiparietal cell antibody (APCA) levels in South and Southeast Asia. BACKGROUND: APCA is an autoantibody that damages gastric parietal cells; autoimmune gastritis (AIG) is a chronic gastric inflammatory disease related to APCA and severe predominant corpus atrophy. Although a positive APCA result is a key clinical diagnostic tool for AIG, its rates vary widely among ethnic groups, and its exact relationship with AIG and predominant corpus atrophy remains unclear. STUDY: Associations between histopathology-assessed and endoscopy-assessed atrophy, APCA positivity rates, Helicobacter pylori status, and pepsinogen levels were investigated in 1982 symptomatic patients from Vietnam, Thailand, Myanmar, Bangladesh, and Nepal. RESULTS: Overall, 38.5% of participants were negative for Helicobacter pylori infection, while 57.6% had a current infection. A positive APCA result, defined as a titer >10, was present in 44.0% of participants (95% confidence interval: 41.8%-46.3%, 873/1982). Pathologic atrophy, corpus atrophy, and predominant corpus atrophy were found in 8.7% (169/1982), 5.1% (101/1982), and 4.1% (81/1982) of participants, respectively. Positive APCA rates significantly differed among countries (10.6% to 63.8%, P <0.001). No significant correlation was found between APCA results and the presence or severity of atrophy. CONCLUSIONS: Although APCA positivity was high among symptomatic patients from South and Southeast Asian countries, few had severe predominant corpus atrophy or positive pepsinogen tests, which suggests a low rate of AIG in this population. Long-term surveillance of APCA-positive individuals is necessary to determine the clinical significance of a positive APCA result without AIG.

Humans↗

PubMed2026

Clinical features and outcomes of patients with anti-neutrophil cytoplasmic antibody-positive systemic lupus erythematosus from a single-center retrospective study.

INTRODUCTION: The role of anti-neutrophil cytoplasmic antibodies (ANCA) in systemic lupus erythematosus (SLE) remains unclear. ANCA positivity has been linked to more severe disease and possible overlap with ANCA-associated vasculitis, but available data are inconsistent. METHODS: We conducted a retrospective single-center study of SLE patients treated at the University Hospital in Kraków (2012-2022). Patients fulfilled the 2019 EULAR/ACR criteria. ANCA positivity (anti-MPO or anti-PR3) was confirmed by ELISA. Clinical features, laboratory findings, treatment, and outcomes were analyzed. RESULTS: Among 1039 SLE patients, 18 (1.73%) were ANCA-positive (anti-MPO, 72.22%; anti-PR3, 27.78%). Most ANCA-positive SLE patients were female (88.89%), with a median age at disease onset of 35.5 years. The most common manifestations in ANCA-positive cases were hematological abnormalities (100%), constitutional symptoms (88.89%), and joint involvement (88.89%). Renal involvement was observed in 72.22% (n = 13) of ANCA-positive SLE patients; however, lupus nephritis was confirmed by kidney biopsy in only seven cases. Vasculitis was rare (5.56%). Anti-dsDNA (61.11%) and anti-SSA (50%) were the most frequent autoantibodies. No significant differences were found between anti-MPO and anti-PR3 subgroups. Most ANCA-positive patients received glucocorticoids (94.44%), cyclophosphamide (61.11%), and antimalarials (61.11%). No statistically significant differences were observed between the ANCA-positive and ANCA-negative groups (p > 0.05 for all parameters). CONCLUSIONS: ANCA positivity in SLE is rare and predominantly associated with anti-MPO antibodies. It is linked to frequent renal involvement but infrequent vasculitis. No differences were observed between ANCA subtypes, suggesting no distinct clinical phenotype. Key Points • ANCA positivity was rare in this systemic lupus erythematosus cohort (1.73%) and was predominantly associated with anti-MPO antibodies rather than anti-PR3 antibodies. • No significant differences in demographic characteristics, clinical manifestations, comorbidities, or autoantibody profiles were observed between ANCA-positive and ANCA-negative patients. Similarly, no significant differences were identified between the anti-PR3-positive and anti-MPO-positive groups. • ANCA-positive SLE was commonly associated with the need for intensive immunosuppressive treatment, highlighting its potential relevance as a marker of severe disease course.

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