@article{NentwichRufGirschicketal.2019,
  author    = {Nentwich, Julia and Ruf, Katharina and Girschick, Hermann and Holl-Wieden, Annette and Morbach, Henner and Hebestreit, Helge and Hofmann, Christine},
  title     = {Physical activity and health-related quality of life in chronic non-bacterial osteomyelitis},
  series = {Pediatric Rheumatology},
  volume    = {17},
  journal   = {Pediatric Rheumatology},
  doi       = {10.1186/s12969-019-0351-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-323710},
  year      = {2019},
  abstract  = {Background Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory disorder of the skeletal system of yet unknown etiology. Patients present with local bone pain and inflammation and - to our experience - often suffer from functional impairment with significant disabilities of daily life. The objective of this study was to assess physical activity, fitness and health-related quality of life (HRQOL) in adolescents with established diagnosis of CNO versus healthy controls (HC). Methods 15 patients with CNO and 15 age and gender matched HC aged 13-18 years, completed questionnaires, performed an incremental exercise test with gas exchange measures up to voluntary fatigue and wore an accelerometer over 7 days at home to assess physical activity behavior. Results At the time of assessment, 5 CNO patients were in clinical, one in radiological and 5 in clinical and radiological remission. 7 did not receive any therapy at the time of assessment. The results of the exercise test and of the accelerometry did not show any significant difference between CNO and HC. However, reported sports participation was lower in patients with CNO and PedsQL3.0 and 4.0 showed significant lower values in most of the scores indicating reduced HRQOL. Conclusion Although most CNO patients showed a favorable course of disease without any relevant differences in objective measurements of physical activity and fitness versus HC at the time of assessment, questionnaires revealed perceived limitations. Further studies are needed to measure HRQOL and to validate questionnaires in patients with CNO against objective measures including more participants with a higher level of disease activity.},
  language  = {en}
}
@article{NothhaftKlepperKneitzetal.2019,
  author    = {Nothhaft, Matthias and Klepper, Joerg and Kneitz, Hermann and Meyer, Thomas and Hamm, Henning and Morbach, Henner},
  title     = {Hemorrhagic bullous Henoch-Sch{\"o}nlein Purpura: case report and review of the literature},
  series = {Frontiers in Pediatrics},
  volume    = {6},
  journal   = {Frontiers in Pediatrics},
  doi       = {10.3389/fped.2018.00413},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201435},
  pages     = {413},
  year      = {2019},
  abstract  = {Henoch-Sch{\"o}nlein Purpura (HSP) or IgA vasculitis is the most common systemic vasculitis of childhood and may affect skin, joints, gastrointestinal tract, and kidneys. Skin manifestations of HSP are characteristic and include a non-thrombocytopenic palpable purpura of the lower extremities and buttocks. Rarely, HSP may initially present as or evolve into hemorrhagic vesicles and bullae. We present an otherwise healthy 5-year-old boy with an acute papulovesicular rash of both legs and intermittent abdominal pain. After a few days the skin lesions rapidly evolved into palpable purpura and hemorrhagic bullous lesions of variable size and severe hemorrhagic HSP was suspected. A histological examination of a skin biopsy showed signs of a small vessel leukocytoclastic vasculitis limited to the upper dermis and direct immunofluorescence analysis revealed IgA deposits in vessel walls, compatible with HSP. To further characterize the clinical picture and treatment options of bullous HSP we performed an extensive literature research and identified 41 additional pediatric patients with bullous HSP. Two thirds of the reported patients were treated with systemic corticosteroids, however, up to 25\% of the reported patients developed skin sequelae such as hyperpigmentation and/or scarring. The early use of systemic corticosteroids has been discussed controversially and suggested in some case series to be beneficial by reducing the extent of lesions and minimizing sequelae of disease. Our patient was treated with systemic corticosteroids tapered over 5 weeks. Fading of inflammation resulted in healing of most erosions, however, a deep necrosis developing from a large blister at the dorsum of the right foot persisted so that autologous skin transplantation was performed. Re-examination 11 months after disease onset showed complete clinical remission with re-epithelialization but also scarring of some affected areas.},
  language  = {en}
}
@article{ElHelouBiegnerBodeetal.2019,
  author    = {El-Helou, Sabine M. and Biegner, Anika-Kerstin and Bode, Sebastian and Ehl, Stephan R. and Heeg, Maximilian and Maccari, Maria E. and Ritterbusch, Henrike and Speckmann, Carsten and Rusch, Stephan and Scheible, Raphael and Warnatz, Klaus and Atschekzei, Faranaz and Beider, Renata and Ernst, Diana and Gerschmann, Stev and Jablonka, Alexandra and Mielke, Gudrun and Schmidt, Reinhold E. and Sch{\"u}rmann, Gesine and Sogkas, Georgios and Baumann, Ulrich H. and Klemann, Christian and Viemann, Dorothee and Bernuth, Horst von and Kr{\"u}ger, Renate and Hanitsch, Leif G. and Scheibenbogen, Carmen M. and Wittke, Kirsten and Albert, Michael H. and Eichinger, Anna and Hauck, Fabian and Klein, Christoph and Rack-Hoch, Anita and Sollinger, Franz M. and Avila, Anne and Borte, Michael and Borte, Stephan and Fasshauer, Maria and Hauenherm, Anja and Kellner, Nils and M{\"u}ller, Anna H. and {\"U}lzen, Anett and Bader, Peter and Bakhtiar, Shahrzad and Lee, Jae-Yun and Heß, Ursula and Schubert, Ralf and W{\"o}lke, Sandra and Zielen, Stefan and Ghosh, Sujal and Laws, Hans-Juergen and Neubert, Jennifer and Oommen, Prasad T. and H{\"o}nig, Manfred and Schulz, Ansgar and Steinmann, Sandra and Klaus, Schwarz and D{\"u}ckers, Gregor and Lamers, Beate and Langemeyer, Vanessa and Niehues, Tim and Shai, Sonu and Graf, Dagmar and M{\"u}glich, Carmen and Schmalzing, Marc T. and Schwaneck, Eva C. and Tony, Hans-Peter and Dirks, Johannes and Haase, Gabriele and Liese, Johannes G. and Morbach, Henner and Foell, Dirk and Hellige, Antje and Wittkowski, Helmut and Masjosthusmann, Katja and Mohr, Michael and Geberzahn, Linda and Hedrich, Christian M. and M{\"u}ller, Christiane and R{\"o}sen-Wolff, Angela and Roesler, Joachim and Zimmermann, Antje and Behrends, Uta and Rieber, Nikolaus and Schauer, Uwe and Handgretinger, Rupert and Holzer, Ursula and Henes, J{\"o}rg and Kanz, Lothar and Boesecke, Christoph and Rockstroh, J{\"u}rgen K. and Schwarze-Zander, Carolynne and Wasmuth, Jan-Christian and Dilloo, Dagmar and H{\"u}lsmann, Brigitte and Sch{\"o}nberger, Stefan and Schreiber, Stefan and Zeuner, Rainald and Ankermann, Tobias and Bismarck, Philipp von and Huppertz, Hans-Iko and Kaiser-Labusch, Petra and Greil, Johann and Jakoby, Donate and Kulozik, Andreas E. and Metzler, Markus and Naumann-Bartsch, Nora and Sobik, Bettina and Graf, Norbert and Heine, Sabine and Kobbe, Robin and Lehmberg, Kai and M{\"u}ller, Ingo and Herrmann, Friedrich and Horneff, Gerd and Klein, Ariane and Peitz, Joachim and Schmidt, Nadine and Bielack, Stefan and Groß-Wieltsch, Ute and Classen, Carl F. and Klasen, Jessica and Deutz, Peter and Kamitz, Dirk and Lassy, Lisa and Tenbrock, Klaus and Wagner, Norbert and Bernbeck, Benedikt and Brummel, Bastian and Lara-Villacanas, Eusebia and M{\"u}nstermann, Esther and Schneider, Dominik T. and Tietsch, Nadine and Westkemper, Marco and Weiß, Michael and Kramm, Christof and K{\"u}hnle, Ingrid and Kullmann, Silke and Girschick, Hermann and Specker, Christof and Vinnemeier-Laubenthal, Elisabeth and Haenicke, Henriette and Schulz, Claudia and Schweigerer, Lothar and M{\"u}ller, Thomas G. and Stiefel, Martina and Belohradsky, Bernd H. and Soetedjo, Veronika and Kindle, Gerhard and Grimbacher, Bodo},
  title     = {The German national registry of primary immunodeficiencies (2012-2017)},
  series = {Frontiers in Immunology},
  volume    = {10},
  journal   = {Frontiers in Immunology},
  doi       = {10.3389/fimmu.2019.01272},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226629},
  year      = {2019},
  abstract  = {Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57\% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36\% of patients. Familial cases were observed in 21\% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74\%) and immune dysregulation (22\%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE-syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49\% of all patients received immunoglobulin G (IgG) substitution (70\%-subcutaneous; 29\%-intravenous; 1\%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.},
  language  = {en}
}
@article{FroehlichSchwaneckGernertetal.2020,
  author    = {Froehlich, Matthias and Schwaneck, Eva C. and Gernert, Michael and Gadeholt, Ottar and Strunz, Patrick-Pascal and Morbach, Henner and Tony, Hans-Peter and Schmalzing, Marc},
  title     = {Autologous Stem Cell Transplantation in Common Variable Immunodeficiency: A Case of Successful Treatment of Severe Refractory Autoimmune Encephalitis},
  series = {Frontiers in Immunology},
  volume    = {11},
  journal   = {Frontiers in Immunology},
  number    = {1317},
  issn      = {1664-3224},
  doi       = {10.3389/fimmu.2020.01317},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-206972},
  year      = {2020},
  abstract  = {Common variable immunodeficiency (CVID) is the most common primary immunodeficiency in adults. It is associated with hypogammaglobulinemia, recurring infections and autoimmune phenomena. Treatment includes immunoglobulin substitution and immunosuppressants. Autoimmune neurological manifestations of CVID are rare and occur predominantly as granulomatous disease. We report the case of a 35-year-old woman with CVID who developed autoimmune encephalitis as demonstrated by double cerebral biopsy. Infectious or malignant causes could be excluded. Despite intensive immunosuppressive therapy with common regimens no significant improvement could be achieved. Ultimately, an autologous hematopoietic stem cell transplantation (HSCT) was performed, resulting in lasting complete remission of the encephalitis. To our knowledge, this is the first report of refractory autoimmune phenomena in CVID treated by autologous HSCT.},
  language  = {en}
}
@article{HedrichMorbachReiseretal.2020,
  author    = {Hedrich, Christian M. and Morbach, Henner and Reiser, Christiane and Girschick, Hermann J.},
  title     = {New Insights into Adult and Paediatric Chronic Non-bacterial Osteomyelitis CNO},
  series = {Current Rheumatology Reports},
  volume    = {22},
  journal   = {Current Rheumatology Reports},
  issn      = {1523-3774},
  doi       = {10.1007/s11926-020-00928-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-232636},
  year      = {2020},
  abstract  = {Purpose of Review To describe in detail the clinical synopsis and pathophysiology of chronic non-bacterial osteomyelitis and SAPHO syndrome. Recent Findings Chronic non-bacterial osteomyelitis (CNO) has been identified as a disease entity for almost 50 years. This inflammatory bone disorder is characterized by osteolytic as well as hyperostotic/osteosclerotic lesions. It is chronic in nature, but it can present with episodic flairs and phases of remission, which have led to the denomination "chronic recurrent osteomyelitis", with its severe multifocal form "chronic recurrent multifocal osteomyelitis" (CRMO). For almost three decades, an infectious aetiology had been considered, since especially Propionibacterium acnes had been isolated from bone lesions of individual patients. However, this concept has been challenged since long-term antibiotic therapy did not alter the course of disease and modern microbiological techniques (including PCR) failed to confirm bone infection as an underlying cause. Over recent years, a profound dysregulation of cytokine expression profiles has been demonstrated in innate immune cells of CNO patients. A hallmark of monocytes from CNO patients is the failure to produce immune regulatory cytokines interleukin-10 (IL-10) and IL-19, which have been linked with genetic and epigenetic alterations. Subsequently, a significant upregulation of pro-inflammatory, NLRP3 inflammasome-dependent cytokines (IL-1β and TNF-α), has been demonstrated. Summary The current knowledge on CNO, the underlying molecular pathophysiology, and modern imaging strategies are summarized; differential diagnoses, treatment options, outcome measures, as well as quality of life studies are discussed.},
  language  = {en}
}
@article{vonLukowiczSchlegelHaerteletal.2021,
  author    = {von Lukowicz, Hannah and Schlegel, Paul-Gerhardt and H{\"a}rtel, Christoph and Morbach, Henner and Haubitz, Imme and Wiegering, Verena},
  title     = {ESPED survey on newly diagnosed immune thrombocytopenia in childhood: how much treatment do we give?},
  series = {Molecular and Cellular Pediatrics},
  volume    = {8},
  journal   = {Molecular and Cellular Pediatrics},
  doi       = {10.1186/s40348-021-00121-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-261832},
  year      = {2021},
  abstract  = {Background Immune thrombocytopenia (ITP) is an autoimmune disease associated with isolated thrombocytopenia, which is caused by an imbalance between platelet production and platelet destruction. Petechial and mucous membrane hemorrhages are characteristic of ITP, but life-threatening bleeding rarely occurs. Depending on the bleeding symptoms, ITP can be treated with glucocorticoids (GC), intravenous immunoglobulins (IVIG), or in severe cases, platelet transfusions. Mild bleeding does not necessarily require therapy. Using the German Surveillance Unit for rare Pediatric Diseases (ESPED) we conducted a prospective survey on ITP patients in all German Children's Hospitals between September 2018 and August 2019. We collected data on ITP, including the clinical course, therapy implementation recommendations (according to the Association of German Scientific Medical Societies guidelines), outcome, and influence of treatment regimens depending on the treating physician´s experience with ITP patients. Results Of the 287 recorded cases of children with ITP, 268 questionnaires were sent to the authors. Two hundred seventeen of the questionnaires fulfilled the inclusion criteria. ITP affected boys and girls similarly, and the median age of manifestation was 3.5 years. The main reasons for hospitalization were thrombocytopenia, bleeding signs, hematomas, and/or petechiae. Bleeding scores were ≤ 3 in 96\% of children, which corresponded to a low-to-moderately low risk of bleeding. No life-threatening bleeding was documented. The most common therapies were IVIG (n = 59), GC (n = 33), or a combination of these (n = 17). Blood products (i.e., red blood cells, platelet concentrate, and fresh frozen plasma) were given to 13 patients. Compared to the established guidelines, 67 patients were over-treated, and 2 patients were under-treated. Conclusions Adherence to German ITP treatment guidelines is currently limited. To improve patient safety and medical care, better medical training and dissemination of the guidelines are required in line with targeted analyses of patients with serious bleeding events to identify potential risk constellations.},
  language  = {en}
}
@article{DirksFischerHaaseetal.2021,
  author    = {Dirks, Johannes and Fischer, Jonas and Haase, Gabriele and Holl-Wieden, Annette and Hofmann, Christine and Girschick, Hermann and Morbach, Henner},
  title     = {CD21\(^{lo/-}\)CD27\(^-\)IgM\(^-\) Double-Negative B Cells Accumulate in the Joints of Patients With Antinuclear Antibody-Positive Juvenile Idiopathic Arthritis},
  series = {Frontiers in Pediatrics},
  volume    = {9},
  journal   = {Frontiers in Pediatrics},
  issn      = {2296-2360},
  doi       = {10.3389/fped.2021.635815},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236286},
  year      = {2021},
  abstract  = {Juvenile idiopathic arthritis (JIA) encompasses a heterogeneous group of diseases. The appearance of antinuclear antibodies (ANAs) in almost half of the patients suggests B cell dysregulation as a distinct pathomechanism in these patients. Additionally, ANAs were considered potential biomarkers encompassing a clinically homogenous subgroup of JIA patients. However, in ANA+ JIA patients, the site of dysregulated B cell activation as well as the B cell subsets involved in this process is still unknown. Hence, in this cross-sectional study, we aimed in an explorative approach at characterizing potential divergences in B cell differentiation in ANA+ JIA patients by assessing the distribution of peripheral blood (PB) and synovial fluid (SF) B cell subpopulations using flow cytometry. The frequency of transitional as well as switched-memory B cells was higher in PB of JIA patients than in healthy controls. There were no differences in the distribution of B cell subsets between ANA- and ANA+ patients in PB. However, the composition of SF B cells was different between ANA- and ANA+ patients with increased frequencies of CD21\(^{lo/-}\)CD27\(^-\)IgM\(^-\) "double negative" (DN) B cells in the latter. DN B cells might be a characteristic subset expanding in the joints of ANA+ JIA patients and are potentially involved in the antinuclear immune response in these patients. The results of our explorative study might foster further research dissecting the pathogenesis of ANA+ JIA patients.},
  language  = {en}
}
@article{FortmannDirksGoedickeFritzetal.2022,
  author    = {Fortmann, Mats Ingmar and Dirks, Johannes and Goedicke-Fritz, Sybelle and Liese, Johannes and Zemlin, Michael and Morbach, Henner and H{\"a}rtel, Christoph},
  title     = {Immunization of preterm infants: current evidence and future strategies to individualized approaches},
  series = {Seminars in Immunopathology},
  volume    = {44},
  journal   = {Seminars in Immunopathology},
  number    = {6},
  doi       = {10.1007/s00281-022-00957-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324261},
  pages     = {767-784},
  year      = {2022},
  abstract  = {Preterm infants are at particularly high risk for infectious diseases. As this vulnerability extends beyond the neonatal period into childhood and adolescence, preterm infants benefit greatly from infection-preventive measures such as immunizations. However, there is an ongoing discussion about vaccine safety and efficacy due to preterm infants' distinct immunological features. A significant proportion of infants remains un- or under-immunized when discharged from primary hospital stay. Educating health care professionals and parents, promoting maternal immunization and evaluating the potential of new vaccination tools are important means to reduce the overall burden from infectious diseases in preterm infants. In this narrative review, we summarize the current knowledge about vaccinations in premature infants. We discuss the specificities of early life immunity and memory function, including the role of polyreactive B cells, restricted B cell receptor diversity and heterologous immunity mediated by a cross-reactive T cell repertoire. Recently, mechanistic studies indicated that tissue-resident memory (Trm) cell populations including T cells, B cells and macrophages are already established in the fetus. Their role in human early life immunity, however, is not yet understood. Tissue-resident memory T cells, for example, are diminished in airway tissues in neonates as compared to older children or adults. Hence, the ability to make specific recall responses after secondary infectious stimulus is hampered, a phenomenon that is transcriptionally regulated by enhanced expression of T-bet. Furthermore, the microbiome establishment is a dominant factor to shape resident immunity at mucosal surfaces, but it is often disturbed in the context of preterm birth. The proposed function of Trm T cells to remember benign interactions with the microbiome might therefore be reduced which would contribute to an increased risk for sustained inflammation. An improved understanding of Trm interactions may determine novel targets of vaccination, e.g., modulation of T-bet responses and facilitate more individualized approaches to protect preterm babies in the future.},
  language  = {en}
}
@article{DirksHaaseCantaertetal.2022,
  author    = {Dirks, Johannes and Haase, Gabriele and Cantaert, Tineke and Frey, Lea and Klaas, Moritz and Rickert, Christian H. and Girschick, Hermann and Meffre, Eric and Morbach, Henner},
  title     = {A novel AICDA splice-site mutation in two siblings with HIGM2 permits somatic hypermutation but abrogates mutational targeting},
  series = {Journal of Clinical Immunology},
  volume    = {42},
  journal   = {Journal of Clinical Immunology},
  number    = {4},
  doi       = {10.1007/s10875-022-01233-5},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324253},
  pages     = {771-782},
  year      = {2022},
  abstract  = {Hyper-IgM syndrome type 2 (HIGM2) is a B cell intrinsic primary immunodeficiency caused by mutations in AICDA encoding activation-induced cytidine deaminase (AID) which impair immunoglobulin class switch recombination (CSR) and somatic hypermutation (SHM). Whereas autosomal-recessive AID-deficiency (AR-AID) affects both CSR and SHM, the autosomal-dominant form (AD-AID) due to C-terminal heterozygous variants completely abolishes CSR but only partially affects SHM. AR-AID patients display enhanced germinal center (GC) reactions and autoimmune manifestations, which are not present in AD-AID, suggesting that SHM but not CSR regulates GC reactions and peripheral B cell tolerance. Herein, we describe two siblings with HIGM2 due to a novel homozygous AICDA mutation (c.428-1G > T) which disrupts the splice acceptor site of exon 4 and results in the sole expression of a truncated AID variant that lacks 10 highly conserved amino acids encoded by exon 4 (AID-ΔE4a). AID-ΔE4a patients suffered from defective CSR and enhanced GC reactions and were therefore indistinguishable from other AR-AID patients. However, the AID-ΔE4a variant only partially affected SHM as observed in AD-AID patients. In addition, AID-ΔE4a but not AD-AID patients revealed impaired targeting of mutational hotspot motives and distorted mutational patterns. Hence, qualitative defects in AID function and altered SHM rather than global decreased SHM activity may account for the disease phenotype in these patients.},
  language  = {en}
}
@article{FischerDirksKlaussneretal.2022,
  author    = {Fischer, Jonas and Dirks, Johannes and Klaussner, Julia and Haase, Gabriele and Holl-Wieden, Annette and Hofmann, Christine and Hackenberg, Stephan and Girschick, Hermann and Morbach, Henner},
  title     = {Effect of clonally expanded PD-1\(^h\)\(^i\)\(^g\)\(^h\) CXCR5-CD4+ peripheral T Helper cells on B cell differentiation in the joints of patients with antinuclear antibody-positive juvenile idiopathic arthritis},
  series = {Arthritis \& Rheumatology},
  volume    = {74},
  journal   = {Arthritis \& Rheumatology},
  number    = {1},
  doi       = {10.1002/art.41913},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256607},
  pages     = {150-162},
  year      = {2022},
  abstract  = {Objective Antinuclear antibody (ANA)-positive juvenile idiopathic arthritis (JIA) is characterized by synovial B cell hyperactivity, but the precise role of CD4+ T cells in promoting local B cell activation is unknown. This study was undertaken to determine the phenotype and function of synovial CD4+ T cells that promote aberrant B cell activation in JIA. Methods Flow cytometry was performed to compare the phenotype and cytokine patterns of PD-1\(^h\)\(^i\)\(^g\)\(^h\)CD4+ T cells in the synovial fluid (SF) of patients with JIA and T follicular helper cells in the tonsils of control individuals. TCRVB next-generation sequencing was used to analyze T cell subsets for signs of clonal expansion. The functional impact of these T cell subsets on B cells was examined in cocultures in vitro. Results Multidimensional flow cytometry revealed the expansion of interleukin-21 (IL-21) and interferon-γ (IFNγ)-coexpressing PD-1\(^h\)\(^i\)\(^g\)\(^h\)CXCR5-HLA-DR+CD4+ T cells that accumulate in the joints of ANA-positive JIA patients. These T cells exhibited signs of clonal expansion with restricted T cell receptor clonotypes. The phenotype resembled peripheral T helper (Tph) cells with an extrafollicular chemokine receptor pattern and high T-bet and B lymphocyte-induced maturation protein 1 expression, but low B cell lymphoma 6 expression. SF Tph cells, by provision of IL-21 and IFNy, skewed B cell differentiation toward a CD21\(^l\)\(^o\)\(^w\)\(^/\)\(^-\)CD11c+ phenotype in vitro. Additionally, SF Tph cell frequencies correlated with the appearance of SF CD21\(^l\)\(^o\)\(^w\)\(^/\)\(^-\)CD11c+CD27-IgM- double-negative (DN) B cells in situ.},
  language  = {en}
}
@article{DirksAndresPauletal.2023,
  author    = {Dirks, Johannes and Andres, Oliver and Paul, Luisa and Manukjan, Georgi and Schulze, Harald and Morbach, Henner},
  title     = {IgD shapes the pre-immune na{\"i}ve B cell compartment in humans},
  series = {Frontiers in Immunology},
  volume    = {14},
  journal   = {Frontiers in Immunology},
  doi       = {10.3389/fimmu.2023.1096019},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304758},
  year      = {2023},
  abstract  = {B cell maturation and immunoglobulin (Ig) repertoire selection are governed by expression of a functional B cell receptor (BCR). Na{\"i}ve B cells co-express their BCR as IgM and IgD isotype. However, the role of the additionally expressed IgD on na{\"i}ve B cells is not known. Here we assessed the impact of IgD on na{\"i}ve B cell maturation and Ig repertoire selection in 8 individuals from 3 different families with heterozygous loss-of-function or loss-of expression mutations in IGHD. Although na{\"i}ve B cells from these individuals expressed IgM on their surface, the IGHD variant in heterozygous state entailed a chimeric situation by allelic exclusion with almost half of the na{\"i}ve B cell population lacking surface IgD expression. Flow cytometric analyses revealed a distinct phenotype of IgD-negative na{\"i}ve B cells with decreased expression of CD19, CD20 and CD21 as well as lower BAFF-R and integrin-β7 expression. IgD-negative B cells were less responsive in vitro after engaging the IgM-BCR, TLR7/9 or CD40 pathway. Additionally, a selective disadvantage of IgD-negative B cells within the T2 transitional and mature na{\"i}ve B cell compartment as well as reduced frequencies of IgMlo/- B cells within the mature na{\"i}ve B cell compartment lacking IgD were evident. RNA-Ig-seq of bulk sorted B cell populations showed an altered selection of distinct VH segments in the IgD-negative mature na{\"i}ve B cell population. We conclude that IgD expression on human na{\"i}ve B cells is redundant for generation of na{\"i}ve B cells in general, but further shapes the naive B cell compartment starting from T2 transitional B cells. Our observations suggest an unexpected role of IgD expression to be critical for selection of distinct Ig VH segments into the pre-immune Ig repertoire and for the survival of IgMlo/- na{\"i}ve B cells known to be enriched in poly-/autoreactive B cell clones.},
  language  = {en}
}