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.

Vaccination status of patients with primary immunodeficiencies in Germany-a multicentric epidemiologic analysis.

BACKGROUND: Vaccinations represent an easily accessible, safe, and important method for preventing infections. Patients with primary immunodeficiencies (PID) are more susceptible to infections and should receive an extended spectrum of immunizations in many countries. METHODS: Between January 2019 and May 2020, vaccination certificates of 70 patients with PID from the regions of Würzburg and Hanover in Germany were evaluated. The patients were additionally surveyed regarding their attitude towards vaccinations and the communication with their physicians. Medical records were analyzed. RESULTS: Of the 70 patients, 54 (77%) suffered from common variable immunodeficiency, 30 (43%) were diagnosed with accompanying autoimmunity, 62 (89%) had an increased susceptibility to infections, and 56 (80%) were on immunoglobulin substitution therapy. Seven patients (10%) had neither a vaccination certificate nor were they able to recollect of their last vaccination. Only 55 (79%) and 43 (61%) patients stated that their rheumatologist or immunologist had recommended an influenza and a pneumococcal vaccination, respectively. When asked about their overall trust in vaccinations on a scale of 0 to 10 (0 = very low, 10 = very high), the mean value was 7.8. The most common vaccination was against tetanus in 63 (90%) patients, 49 (70%) had received vaccination against pneumococci, and 39 (56%) had received an influenza vaccination. Interestingly, 26 patients (37%) were vaccinated against measles, even though this is contraindicated in most PID patients. CONCLUSION: Our data suggest that vaccination rates in this at-risk population are insufficient. Healthcare providers should emphasize vaccinations routinely when caring for these patients.

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).