OBJECTIVES:This study aimed to evaluate the safety and efficacy of teclistamab, a T cell-redirecting bispecific antibody targeting B-cell maturation antigen, in a case series of severe autoimmune diseases. METHODS:Data were retrospectively collected from patients with treatment-refractory systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIMs), systemic lupus erythematosus (SLE), undifferentiated connective tissue disease (UCTD), or IgG4-related disease (IgG4-RD) who received 1 cycle of teclistamab at 5 European centres. RESULTS:Eighteen patients (72% women, median age 48.5 years, 10 SSc, 4 IIM, 2 SLE, 1 UCTD, and 1 IgG4-RD) with a median of 5 prior therapies and a median cumulative dose of 6.36 mg/kg teclistamab were included. The median follow-up was 5.1 months (range, 0.8-21.2 months). A total of 22 cytokine release syndrome episodes (16 grade 1 and 6 grade 2) occurred in 12 patients (67%). All patients developed severe hypogammaglobulinaemia, and 5 (28%) experienced severe infections. Two patients developed an inflammatory bowel disease-like colitis. Two patients with severe SSc-associated cardiac involvement died, 1 due to sudden cardiac death and the other following diffuse alveolar haemorrhage and heart failure. B-cell depletion was observed in all patients, accompanied by significant reductions in autoantibody levels. Teclistamab was associated with major clinical responses in 11 (61%) and minimal-to-moderate responses in 4 (22%) patients, despite discontinuation of immunosuppressive therapy. CONCLUSIONS:Teclistamab demonstrated the potential to induce treatment-free responses in refractory autoimmune disease, but clinically relevant safety events, including infections and fatal outcomes in patients with advanced cardiac involvement, highlight the need for careful patient selection and monitoring.

To determine the correlation between quantitative HU values derived from DECT collagen maps and the MRI-based Pfirrmann grade. We retrospectively reviewed IVDs in patients who underwent both spinal DECT and MRI within one year. CT scans were acquired using single-source DECT at 80 and 135-kVp with automatic exposure control. Three readers scored IVDs according to Pfirrmann et al. on T2-weighted MRI images. Quantitative evaluation involved placing three standardized regions of interest in each IVD in DECT-based cMaps; in corresponding 135-kVp DECT scans and MRI images. Mean density measurements of AF and NP were compared with PF-grades using linear mixed model analysis. We included 339 IVDs of 97 patients [mean age 59.1 years]; (53 women [mean age 63.5 years] and 44 men [mean age 53.8 years]). cMap analysis revealed a significant difference of AF and NP collagen and chondroitin density between PF-grade I and V(AF: MD = - 31.1HU (95% CI - 59.5 to - 2.7), p = 0.032;NP:MD = - 37.8HU (95% CI - 73.6 to - 2.0), p = 0.038). 135-kVp DECT showed no IVD density reduction corresponding to PF-grades. MRI showed significant reduction of signal intensities in AF and NP with increasing PF-grades. IVD collagen and chondroitin density declined with increasing PF-grade in DECT-based cMaps, suggesting DECT-based cMaps as an additional tool for IVD classification.

Chimeric antigen receptor (CAR) T cell-mediated B cell depletion has demonstrated efficacy in several autoimmune diseases. Here we report clinical and molecular data obtained during the nonrandomized phase 1 part of the phase 1/2 COMPARE trial, evaluating safety and efficacy of mivocabtagene autoleucel (miv-cel), an autologous fully human CD19 CAR T cell therapy, in rheumatoid arthritis (RA). Six patients (three men, three women) with severe, treatment-refractory, anti-citrullinated protein antibody (ACPA)-positive RA received a single infusion of miv-cel after stopping all disease-modifying antirheumatic drug treatments and after standard lymphodepletion therapy. Patients were followed for 36-52 weeks for safety and efficacy. Primary endpoints were the incidence and severity of cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS) and adverse events (AEs) within the first 4 weeks after treatment. Secondary and explorative endpoints assessed clinical efficacy and cellular and humoral immune responses. CRS occurred in all patients and was limited to grade 1 and 2 events. No ICANSs or serious AEs occurred; one dose-limiting toxicity was recorded (grade 3 transaminase elevation, resolved without sequelae). The primary endpoint was met with acceptable safety findings, allowing advancement to phase 2. CAR T cell therapy resulted in depletion of CD19+ B cells across blood and tissue, coinciding with a continuous decline of autoantibodies with seroconversion in four of the six patients for ACPAs against mutated citrullinated vimentin and five of six for rheumatoid factor immunoglobulin M. Despite cessation of immunosuppressive treatments, disease activity improved in all patients (median 34% DAS28-CRP reduction at the latest follow-up with DAS28-CRP remission and American College of Rheumatology 70% response in 3 of 6 patients). CD19 CAR T cells showed acceptable short-term tolerability in patients with treatment-refractory RA, justifying further evaluation. ClinicalTrials.gov identifier: NCT06475495 .

IntroductionSystemic lupus erythematosus (SLE) and other chronic inflammatory diseases are complex, multifactorial conditions where patient heterogeneity poses a major challenge to treatment. Despite the availability of numerous omics technologies, reliable biomarkers for precision medicine remain scarce, and many cell-based approaches are difficult to integrate into clinical settings. In this proof-of-concept study, we hypothesized that interrogating the cells’ imprinting by the inflammatory environment through Unperturbed Activation Profiling (UACT) without prior restimulation would allow for the assessment of individual immune status in chronic rheumatic diseases.MethodsWe developed a highly standardized mass cytometry-based workflow to assess signaling protein phosphorylation in peripheral blood leukocytes from active SLE patients (n=20) and healthy controls (n=20) at the single-cell level. Importantly, the entire workflow from blood drawing to stabilization and preparation of barcoded samples was optimized to ensure necessary robustness of the procedure for clinical studies.ResultsWe identified leukocyte-specific in vivo-like signaling patterns in line with type I interferon-driven signatures, such as elevated pSTAT1 in naïve T cells and pSTAT3 in classical monocytes and naïve CD8 T cells. These patterns captured patient variability and immune activation, although they did not correlate with SLEDAI-2K disease activity scores. We further explored the utility of UACT for treatment monitoring in four SLE patients treated with the JAK inhibitor baricitinib under compassionate use, where baseline pSTAT3 levels across multiple cell subsets seemed to be associated with treatment response.DiscussionOur results thus demonstrate that single-cell UACT without restimulation of cells can detect immune activation in chronic inflammatory diseases, supporting both biomarker discovery and the identification of novel therapeutic targets.

Antibody-secreting cells (ASCs) play a central role in the pathophysiology of systemic lupus erythematosus (SLE). This single-arm, open-label, phase 2 clinical trial aims to evaluate the safety and efficacy of the ASC-depleting anti-CD38 monoclonal antibody daratumumab in patients with SLE (NCT04810754). The primary endpoint is the reduction in serum anti-double-stranded DNA (anti-dsDNA) antibody levels at week 12. Key secondary end points include safety, clinical efficacy, and immunologic changes. Ten female patients with active disease and inadequate responses to at least two immunosuppressive drugs have received eight subcutaneous injections of 1800 mg daratumumab weekly, with dexamethasone as premedication (20 mg for first two injections, then 10 mg). By week 12, anti-dsDNA antibody levels have been reduced by a median of 109.6 IU/ml (95% CI 38.1 - 274.5). The treatment resulted in rapid and sustained clinical improvements across all patients and organ domains, reflected by a 100% SRI-4 (Systemic Lupus Erythematosus Responder Index-4) response rate at week 12. Hypogammaglobulinemia occurred in 5/10 patients, requiring immunoglobulin substitution. Daratumumab treatment has depleted circulating ASCs, reduced type I interferon activity, and profoundly modulated the T-cell responses. These findings highlight the pivotal role of ASCs in SLE pathogenesis and support daratumumab as therapeutic option for SLE.

Proliferative lupus nephritis (LN) is triggered by deposition of autoantibodies in glomeruli and paralleled by a T cell-rich kidney infiltrate. Although these T cells have been attributed to the propagation of tissue injury, it is unclear how they are activated and whether T cell autoreactivity drives local inflammation. Kidney-infiltrating T cells are also observed in urine, where they have high resemblance to interstitial T cells. Therefore, urinary T cells are a proxy for investigating tissue pathogenesis. Here, we analyzed urinary T cells to elucidate whether a kidney-specific T cell autoimmune reaction contributes to tubulointerstitial inflammation in LN. Using single-cell RNA sequencing, we compared transcriptomes and clonotypes of T cells from the blood and urine of patients with active LN and showed that urinary T cells were mostly activated CD8 effector memory cells recruited from a circulating CX3CR1+ subset. Several urinary CD8 T cell clones were expanded. However, upon in vitro testing of their T cell receptors, we did not observe autoreactivity against autologous tubular epithelial cells. Instead, ~20% of expanded clonotypes were Epstein-Barr virus-specific or cytomegalovirus-specific, but respective viral antigens were undetectable in kidney biopsies or urine. Conversely, kidney-infiltrating T cells had access to interleukin-15 and interferon-β (IFN-β), and stimulation with these cytokines was sufficient to trigger degranulation and production of tumor necrosis factor, IFN-γ, and granzyme K. Together, these results show that CD8+CX3CR1+ T cells are recruited into the kidney in LN, where they are activated by cytokines, enabling them to contribute to local inflammation.

OBJECTIVES:Type I IFNs (IFN-I) are central to pathogenesis and monitoring of SLE, yet clinically accessible biomarkers remain limited. Building on prior validation of membrane-bound SIGLEC-1 (mbSIGLEC-1), we conducted a proof-of-concept study to evaluate soluble SIGLEC-1 (sSIGLEC-1) as a useful IFN-I biomarker in SLE. METHODS:The study prospectively enrolled 61 SLE patients and 100 blood donors as controls. In SLE patients, disease activity indices (DAIs) and routine SLE and IFN biomarkers (IFNα, IP-10, mbSIGLEC-1) were assessed longitudinally. sSIGLEC-1 was measured using chemiluminescence immunoassay; a cohort-specific threshold was defined by ROC analysis. Cross-sectional correlations between DAIs and biomarkers were analysed in all patients, longitudinal analyses included 23 patients over 57 visits. Flare-predictive value was evaluated in 27 patients with quiescent disease over 180 days. RESULTS:We determined a threshold for sSIGLEC-1 at 4.55 ng/ml (sensitivity: 70.49%, specificity: 90%). Cross-sectionally, sSIGLEC-1 correlated with mbSIGLEC-1 (r = 0.67, P < 0.001), BILAG (r = 0.37, P = 0.004) and SLEDAI (r = 0.36, P = 0.005). sSIGLEC-1 and mbSIGLEC-1 showed high sensitivity in moderate (sSIGLEC-1: 76%; mbSIGLEC-1: 84%) and severe (both: 100%) disease activity. sSIGLEC-1 correlated positively with IFN-α (r = 0.35; P = 0.006) and IP-10 (r = 0.57; P < 0.001), with similar results for mbSIGLEC-1. Longitudinally, changes in BILAG correlated to changes in sSIGLEC-1 (r = 0.36; P = 0.014) and mbSIGLEC-1 (r = 0.38; P = 0.009). Analysing flare-predictive ability, neither sSIGLEC-1 nor mbSIGLEC-1 showed significant results. CONCLUSION:Our study supports sSIGLEC-1 as a reliable and scalable biomarker of IFN-I activity in SLE. Its performance and compatibility with routine assays make it a strong candidate for clinical translation and broader application in IFN-I-driven diseases.

Recent evidence suggests that type I interferon (IFN) activity has prognostic relevance in systemic lupus erythematosus (SLE). This study investigated whether combining IFN activity with elevated peripheral blood plasmablast (PB) levels-another key feature of lupus pathophysiology-improves risk stratification for poor clinical outcomes. Clinical data were prospectively collected at a single lupus center. Flow cytometry was performed on freshly isolated peripheral blood mononuclear cells to investigate Sialic acid-binding Immunoglobulin-like Lectin 1 (SIGLEC-1) as a surrogate marker of IFN activity, alongside CD19+CD20-CD27highHLA-DR+ PB frequencies. A total of 1276 samples from 121 patients were analyzed. At baseline, 48.8% of patients exhibited high IFN activity, including 27.3% with concurrent elevation in IFN and PB activity and 21.5% with isolated IFN activity. Patients with simultaneous IFN and PB activity showed higher anti-dsDNA antibody levels, were less frequently in DORIS remission (24.2% vs. 50.0%) and required higher daily prednisolone dosages (6.3 vs. 2.0 mg) than those with isolated IFN activity. During a median follow-up of 4.5 years (range 0.8-6.6), these patients experienced more flares (132 vs. 54, OR 1.42), required longer to achieve remission (median 399 vs. 140 days), and had a higher median time-adjusted prednisolone dose (5.6 vs. 3.0 mg). Concurrent elevation in IFN and PB activity identifies SLE patients with a poorer prognosis compared to isolated IFN activity. These findings suggest that combined IFN and PB assessment may improve prognostic stratification and support personalized treatment strategies in SLE.

OBJECTIVES:This study aimed to evaluate clinical outcomes, serologic changes, and immunologic effects induced by the bispecific B cell Maturation Antigen (BCMA)x Cluster of Differentiation (CD)3 T-cell-engaging antibody teclistamab in systemic sclerosis (SSc). METHODS:Patients with severe and treatment-refractory SSc were treated with teclistamab as off-label therapy. Blood and tissue samples from skin and bone marrow were analysed with immunohistochemistry and flow cytometry, serum antibodies were quantified by enzyme-linked immunosorbent assay (ELISA). Clinical efficacy was assessed using the American College of Rheumatology Composite Response Index in Systemic Sclerosis (ACR-CRISS) responses, among others. RESULTS:Ten patients with SSc (70% female; median age 51 years [IQR: 7]) completed 1 cycle of teclistamab. Two patients with advanced SSc heart involvement died shortly after treatment initiation. B-cells and plasma cells were almost completely eliminated from bone marrow and skin, accompanied by a median reduction of 70.6% (IQR: 39%) in antitopoisomerase antibody titres, decreases in serum IgG, and vaccination titres. After a median follow-up of 3.75 months (IQR: 2.5 months), 71% and 43% of patients achieved revised ACR-CRISS 25 and 50 responses, respectively. Among patients with interstitial lung disease, radiographic and functional improvement was observed by week 12 with a median increase in forced vital capacity of 7% (IQR: 15%). Skin fibrosis similarly improved, with a median decrease in the modified Rodnan skin score of 35.9% (IQR: 17.9%), accompanied by corresponding reductions in fibroblast activation protein (FAP)-alpha-positive fibroblasts in skin biopsy specimens. CONCLUSIONS:Teclistamab induced deep tissue depletion of B-cells and plasma cells and rapid clinical and serological responses, with evidence for resolution of inflammation and potential modification of fibrotic processes. These data suggest the potential of BCMA-directed therapies to promote immune modulation and tissue remodelling.

IgA-coated fractions of the intestinal microbiota of Crohn’s disease (CD) patients have been shown to contain taxa that hallmark the compositional dysbiosis in CD microbiomes. However, the correlation between other cellular properties of intestinal bacteria and disease has not been explored further, especially for features that are not directly driven by the host immune-system, e.g. the expression of surface sugars by bacteria. By sorting and sequencing IgA-coated and lectin-stained fractions from CD patients microbiota and healthy controls, we found that lectin-stained bacteria were distinct from IgA-coated bacteria, but still displayed specific differences between CD and healthy controls. To exploit the discriminatory potential of both, immunoglobulin coated bacteria and the altered surface sugar expression of bacteria in CD, we developed a multiplexed single cell-based analysis approach for intestinal microbiota. By multi-parameter microbiota flow cytometry (mMFC) we characterized the intestinal microbiota of 55 CD patients and 44 healthy controls for 11-parameters in total, comprising host-immunoglobulin coating and the presence of distinct surface sugar moieties. The data were analyzed by machine-learning to assess disease-specific marker patterns in the microbiota phenotype. mMFC captured detailed characteristics of CD microbiota and identified patterns to classify CD patients. In addition, we identified phenotypic signatures in the CD microbiota which not only reflected remission after 6 weeks of anti-TNF treatment, but were also able to predict remission before the start of an adalimumab treatment course in a pilot study. We here present the proof-of-concept demonstrating that multi-parameter single-cell bacterial phenotyping by mMFC could be a novel tool with high translational potential to expand current microbiome investigations by phenotyping of bacteria to identify disease- and therapy-associated cellular alterations and to reveal novel target properties of bacteria for functional assays and therapeutic approaches.