Disease-specific T cell receptors maintain pathogenic T helper cell responses in postinfectious Lyme arthritis.

BACKGROUND: Antibiotic-Refractory Lyme Arthritis (ARLA) involves a complex interplay of T cell responses targeting Borrelia burgdorferi antigens succeeding towards autoantigens by epitope spreading. However, the precise molecular mechanisms driving the pathogenic T cell response in ARLA remain unclear. Our aim was to elucidate the molecular program of disease-specific Th cells. METHODS: Using flow cytometry, high-throughput T cell receptor (TCR) sequencing and scRNA-seq of CD4+ Th cells isolated from the joints of European ARLA patients, we aimed at inferring antigen specificity through unbiased analysis of TCR repertoire patterns, identifying surrogate markers for disease-specific TCRs and connecting TCR specificity to transcriptional patterns. RESULTS: PD-1hiHLA-DR+CD4+ effector T cells were clonally expanded within the inflamed joints and persisted throughout disease course. Among these cells, we identified a distinct TCRß motif restricted to HLA-DRB1*11 or *13 alleles. These alleles, being underrepresented in North American ARLA patients, were unexpectedly prevalent in our European cohort. The identified TCRß motif served as surrogate marker for a convergent TCR response specific to ARLA, distinguishing it from other rheumatic diseases. In the scRNA-seq dataset, the TCRß motif particularly mapped to peripheral T helper (TPH) cells displaying signs of sustained proliferation, continuous TCR signaling, and expressing CXCL13 and IFN-γ. CONCLUSION: By inferring disease-specific TCRs from synovial T cells we identified a convergent TCR response in the joints of ARLA patients that continuously fueled the expansion of TPH cells expressing a pathogenic cytokine effector program. The identified TCRs will aid in uncovering the major antigen targets of the maladaptive immune response. FUNDING: Supported by the German Research Foundation (DFG) MO 2160/4-1; the Federal Ministry of Education and Research (BMBF; Advanced Clinician Scientist-Program INTERACT; 01EO2108) embedded in the Interdisciplinary Center for Clinical Research (IZKF) of the University Hospital Würzburg; the German Center for Infection Research (DZIF; Clinical Leave Program; TI07.001_007) and the Interdisciplinary Center for Clinical Research (IZKF) Würzburg (Clinician Scientist Program, Z-2/CSP-30).

Level and correlates of physical activity among children and adolescents with juvenile idiopathic arthritis compared to controls: results from a German nationwide prospective observational cohort study.

BACKGROUND: Physical active lifestyles are essential throughout growth and maturation and may offer potential preventive and therapeutic benefit in patients with juvenile idiopathic arthritis (JIA). Insufficient physical activity (PA), in contrast, can lead to aggravation of disease-related symptoms. This study aimed to i) examine PA levels in children and adolescents with JIA compared to general population controls and ii) investigate correlates of pronounced physical inactivity in order to identify risk groups for sedentary behaviour. METHODS: Data from children and adolescents with JIA and population controls aged 3 to 17 years documented in the National Pediatric Rheumatologic Database (NPRD) and the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) were used. Self-reported PA was collected from parents/guardians of children up to 11 years of age or adolescents 12 years of age and older. To compare PA-related data, age- and sex-specific pairwise analyses were conducted considering NPRD/KiGGS participants' data from 2017. Correlates of physical inactivity among patients were identified using a linear regression model. RESULTS: Data of 6,297 matched-pairs (mean age 11.2 ± 4.2 years, female 67%, patients' disease duration 4.5 ± 3.7 years, persistent oligoarthritis 43%) were available for evaluation. Almost 36% of patients aged 3-17 years (vs. 20% of controls) achieved the WHO recommended amount of PA, while PA steadily decreased with age (18% of patients aged ≥ 12 years) and varied between JIA categories. Female adolescents and patients with enthesitis-related arthritis were least likely to achieve the minimum recommended level of PA. Physical inactivity was associated with female sex, higher age at disease onset, longer disease duration, more functional disability (C-HAQ) and higher disease activity (cJADAS-10). CONCLUSIONS: Depending on JIA category, children and adolescents with JIA were similarly or even more likely to achieve the WHO recommended minimum level of PA compared to general population controls. However, since a large proportion of young JIA patients appear to be insufficiently physically active, engagement in targeted efforts to promote PA is urgently needed.

P2RX7 gene variants associate with altered inflammasome assembly and reduced pyroptosis in chronic nonbacterial osteomyelitis (CNO).

Chronic nonbacterial osteomyelitis (CNO), an autoinflammatory bone disease primarily affecting children, can cause pain, hyperostosis and fractures, affecting quality-of-life and psychomotor development. This study investigated CNO-associated variants in P2RX7, encoding for the ATP-dependent trans-membrane K+ channel P2X7, and their effects on NLRP3 inflammasome assembly. Whole exome sequencing in two related transgenerational CNO patients, and target sequencing of P2RX7 in a large CNO cohort (N = 190) were conducted. Results were compared with publicly available datasets and regional controls (N = 1873). Findings were integrated with demographic and clinical data. Patient-derived monocytes and genetically modified THP-1 cells were used to investigate potassium flux, inflammasome assembly, pyroptosis, and cytokine release. Rare presumably damaging P2RX7 variants were identified in two related CNO patients. Targeted P2RX7 sequencing identified 62 CNO patients with rare variants (32.4%), 11 of which (5.8%) carried presumably damaging variants (MAF <1%, SIFT "deleterious", Polyphen "probably damaging", CADD >20). This compared to 83 of 1873 controls (4.4%), 36 with rare and presumably damaging variants (1.9%). Across the CNO cohort, rare variants unique to one (Median: 42 versus 3.7) or more (≤11 patients) participants were over-represented when compared to 190 randomly selected controls. Patients with rare damaging variants more frequently experienced gastrointestinal symptoms and lymphadenopathy while having less spinal, joint and skin involvement (psoriasis). Monocyte-derived macrophages from patients, and genetically modified THP-1-derived macrophages reconstituted with CNO-associated P2RX7 variants exhibited altered potassium flux, inflammasome assembly, IL-1ß and IL-18 release, and pyroptosis. Damaging P2RX7 variants occur in a small subset of CNO patients, and rare P2RX7 variants may represent a CNO risk factor. Observations argue for inflammasome inhibition and/or cytokine blockade and may allow future patient stratification and individualized care.