Increased IgD and CD27 Double Negative (DN) B cell population in pediatric onset autoimmune hepatitis.

Autoimmune hepatitis (AIH) is a chronic, inflammatory liver disease of unknown aetiology which requires lifelong immunosuppression. Most therapeutic and outcome studies of AIH have been conducted predominantly in Caucasian (European Ancestry, EA) cohorts, with the exclusion of African American (AA) patients due to inadequate sample size. It is known that AA patients have a severe phenotype of autoimmune diseases and demonstrate a poor response to conventional medical therapy. Understanding cellular and molecular pathways which determine AIH severity and progression in AA patients is likely to lead to the discovery of novel, personalised and better tolerated therapies. The aim of the study is to determine the distinct effector B cell phenotypes which contribute to disease severity and progression of AIH in AA children as compared to their EA cohorts. PBMCs were isolated from blood samples collected from patients visiting Children's Healthcare of Atlanta (CHOA) and were grouped into AA, (n = 12), EA, (n = 11) and controls (n = 12) and were processed for flow cytometry. Markers of B cell development, maturation and activation were assessed namely CD19, CD21, IgD, CD27, CD38, CD11c, CD24, CD138. AA children with AIH demonstrated an expansion of CD19 + ve, Activated Naïve (aN), (CD19+ IgD-/CD27- Double Negative (DN2) ([CD19+/IgD-/CD27++CD38++) cells. Plasmablasts were significantly higher along with Signalling Lymphocytic activation molecule F7 (SLAMF7). Unswitched memory [CD19+] IgD+CD27+ (USM) B cells were significantly contracted in AA patients with AIH. B cell phenotyping reveals a distinct profile in AA AIH patients with a major skewing towards the expansion of effector pathways which have been previously characterised in severe SLE in AA patients. These results suggest that the quantification and therapeutic target of B cell pathway could contribute substantially to the clinical approach to AIH especially in the AA population.

A case report of biclonal immunoglobulin D lambda/lambda multiple myeloma in patient with liver echinococcosis.

Less than 2% of all symptomatic multiple myeloma (MM) has immunoglobulin D (IgD) as monoclonal protein. Biclonal gammopathy is much rarer. At the time of diagnosis, disease is often in advanced stage, including renal failure, anemia, hypercalcemia and lytic bone lesions. Due to the rarity of myeloma itself, but also due to the fact that anti-IgD antisera is not used in routine practice, there are only a few reports of IgD MM described in the literature. This case report describes a patient with IgD lambda MM with anemia and renal failure. Anemia, renal failure, and > 80 percent plasma cells in bone biopsy in our patient with IgD lambda MM meets International Myeloma Working Group criteria for diagnosis of MM. The patient clinical course was similar to other patients with IgD MM. The final result of serum protein immunofixation (s-IFE) showed IgD lambda and free lambda monoclonal bands. To prevent misdiagnosis, it is necessary to use anti-IgD and anti-IgE antisera whenever the serum protein immunofixation with IgA, IgM, IgG, kappa and lambda antiserums shows a kappa or lambda monoclonal band without monoclonal band in heavy chain.

Extrafollicular IgD-CD27-CXCR5-CD11c- DN3 B cells infiltrate inflamed tissues in autoimmune fibrosis and in severe COVID-19.

Although therapeutic B cell depletion dramatically resolves inflammation in many diseases in which antibodies appear not to play a central role, distinct extrafollicular pathogenic B cell subsets that accumulate in disease lesions have hitherto not been identified. The circulating immunoglobulin D (IgD)-CD27-CXCR5-CD11c+ DN2 B cell subset has been previously studied in some autoimmune diseases. A distinct IgD-CD27-CXCR5-CD11c- DN3 B cell subset accumulates in the blood both in IgG4-related disease, an autoimmune disease in which inflammation and fibrosis can be reversed by B cell depletion, and in severe COVID-19. These DN3 B cells prominently accumulate in the end organs of IgG4-related disease and in lung lesions in COVID-19, and double-negative B cells prominently cluster with CD4+ T cells in these lesions. Extrafollicular DN3 B cells may participate in tissue inflammation and fibrosis in autoimmune fibrotic diseases, as well as in COVID-19.

Withdrawal from Hemodialysis in a Patient with IgD Type Multiple Myeloma: A Case-based Review.

Several previous case reports have shown that patients with immunoglobulin D (IgD) multiple myeloma (MM) can be withdrawn from hemodialysis, however, the characteristics that can predict withdrawal in these patients have not yet been elucidated. A 57-year-old Japanese woman required hemodialysis because of renal dysfunction due to IgD-λ and Bence Jones protein-λ MM. Bortezomib-based chemotherapy nine days after admission led to her withdrawal from hemodialysis on Day 50. In our case-based review, younger age and early initiation of bortezomib-based chemotherapy emerged as possible predictors of successful hemodialysis withdrawal.

IgD-CD27- double negative (DN) B cells: Origins and functions in health and disease.

Human B cells can be divided into four main subsets based on differential expression of immunoglobulin (Ig)D and CD27. IgD-CD27- double negative (DN) B cells make up a heterogeneous group of B cells that have first been described in relation to aging and systemic lupus erythematosus but have been mostly disregarded in B cell research. Over the last few years, DN B cells have gained a lot of interest because of their involvement in autoimmune and infectious diseases. DN B cells can be divided into different subsets that originate via different developmental processes and have different functional properties. Further research into the origin and function of different DN subsets is needed to better understand the role of these B cells in normal immune responses and how they could be targeted in specific pathologies. In this review, we give an overview of both phenotypic and functional properties of DN B cells and provide insight into the currently proposed origins of DN B cells. Moreover, their involvement in normal aging and different pathologies is discussed.

IgD/FcδR is involved in T-cell acute lymphoblastic leukemia and regulated by IgD-Fc-Ig fusion protein.

T-cell acute lymphoblastic leukemia (T-ALL) has a poor prognosis as a result of severe immunosuppression and rapid tumor progression with resistance to conventional chemotherapy. Excessive IgD may play a role in T cell activation via IgD Fc receptor (FcδR). Here we aimed to investigate the effects of IgD in T-ALL and demonstrated the potential benefit by targeting IgD/FcδR in T-ALL patients with IgD-Fc-Ig fusion protein. In T-ALL patients' blood samples and cell lines, the level of IgD, the percentage of FcδR expressing cells and the binding affinity were determined by flow cytometry. T cell viability, proliferation and apoptosis were analyzed. A mouse xenograft model was used to evaluate the in vivo effect of IgD-Fc-Ig, an IgD-FcδR blocker. The levels of serum IgD and FcδR were abnormally increased in part of T-ALL patients and IgD could induce over-proliferation and inhibit apoptosis of T-ALL cells in vitro. FcδR was constitutively expressed on T-ALL cells. IgD-Fc-Ig showed similar binding affinity to FcδR and selectively blocked the stimulation effect of IgD on T-ALL cells in vitro. In vivo study exhibited that IgD-Fc-Ig may also have therapeutic benefit. IgD-Fc-Ig administration inhibited human T-ALL growth and extended survival in xenograft T-ALL mice. In conclusion, this work supports the idea of targeting IgD/FcδR in T-ALL patients with excessive IgD. IgD-Fc-Ig fusion protein might be a potential biological drug with high selectivity for T-ALL treatment.

IgD multiple myeloma: biology, diagnosis, and treatment.

IgD multiple myeloma is uncommon. Patients generally present at a younger age and have shorter progression free and overall survivals (OSs). Its rarity has inhibited development of a specific risk stratification system or informed best treatment protocols. We present interphase fluorescence in situ hybridization results from a group of 29 cases. These showed evidence of a decreased male to female ratio, decreased OS in patients aged 70 and over, better outcomes in those with kappa light chain restriction, and CD56 positive patients had longer survivals than those lacking CD56. We discuss the biology of IgD multiple myeloma, the need for prospective studies, and challenges for improvements in diagnosis and treatment. We suggest an International Register to accelerate development of best practice guidelines for diagnosis, risk stratification, and treatment.

Epstein-Barr virus perpetuates B cell germinal center dynamics and generation of autoimmune-associated phenotypes in vitro.

Human B cells encompass functionally diverse lineages and phenotypic states that contribute to protective as well as pathogenic responses. Epstein-Barr virus (EBV) provides a unique lens for studying heterogeneous B cell responses, given its adaptation to manipulate intrinsic cell programming. EBV promotes the activation, proliferation, and eventual outgrowth of host B cells as immortalized lymphoblastoid cell lines (LCLs) in vitro, which provide a foundational model of viral latency and lymphomagenesis. Although cellular responses and outcomes of infection can vary significantly within populations, investigations that capture genome-wide perspectives of this variation at single-cell resolution are in nascent stages. We have recently used single-cell approaches to identify EBV-mediated B cell heterogeneity in de novo infection and within LCLs, underscoring the dynamic and complex qualities of latent infection rather than a singular, static infection state. Here, we expand upon these findings with functional characterizations of EBV-induced dynamic phenotypes that mimic B cell immune responses. We found that distinct subpopulations isolated from LCLs could completely reconstitute the full phenotypic spectrum of their parental lines. In conjunction with conserved patterns of cell state diversity identified within scRNA-seq data, these data support a model in which EBV continuously drives recurrent B cell entry, progression through, and egress from the Germinal Center (GC) reaction. This "perpetual GC" also generates tangent cell fate trajectories including terminal plasmablast differentiation, which constitutes a replicative cul-de-sac for EBV from which lytic reactivation provides escape. Furthermore, we found that both established EBV latency and de novo infection support the development of cells with features of atypical memory B cells, which have been broadly associated with autoimmune disorders. Treatment of LCLs with TLR7 agonist or IL-21 was sufficient to generate an increased frequency of IgD-/CD27-/CD23-/CD38+/CD138+ plasmablasts. Separately, de novo EBV infection led to the development of CXCR3+/CD11c+/FCRL4+ B cells within days, providing evidence for possible T cell-independent origins of a recently described EBV-associated neuroinvasive CXCR3+ B cell subset in patients with multiple sclerosis. Collectively, this work reveals unexpected virus-driven complexity across infected cell populations and highlights potential roles of EBV in mediating or priming foundational aspects of virus-associated immune cell dysfunction in disease.

Autoantibodies elicited with SARS-CoV-2 infection are linked to alterations in double negative B cells.

Double negative (DN) B cells (CD27-IgD-) comprise a heterogenous population of DN1, DN2, and the recently described DN3 and DN4 subsets. In autoimmune disease, DN2 cells are reported to be precursors to autoreactive antibody secreting cells and expansion of DN2 cells is linked to elevated interferon levels. Severe SARS-CoV-2 infection is characterized by elevated systemic levels of pro-inflammatory cytokines and serum autoantibodies and expansion of the DN2 subset in severe SARS-CoV-2 infection has been reported. However, the activation status, functional capacity and contribution to virally-induced autoantibody production by DN subsets is not established. Here, we validate the finding that severe SARS-CoV-2 infection is associated with a reduction in the frequency of DN1 cells coinciding with an increase in the frequency of DN2 and DN3 cells. We further demonstrate that with severe viral infection DN subsets are at a heightened level of activation, display changes in immunoglobulin class isotype frequency and have functional BCR signaling. Increases in overall systemic inflammation (CRP), as well as specific pro-inflammatory cytokines (TNFα, IL-6, IFNγ, IL-1ß), significantly correlate with the skewing of DN1, DN2 and DN3 subsets during severe SARS-CoV-2 infection. Importantly, the reduction in DN1 cell frequency and expansion of the DN3 population during severe infection significantly correlates with increased levels of serum autoantibodies. Thus, systemic inflammation during SARS-CoV-2 infection drives changes in Double Negative subset frequency, likely impacting their contribution to generation of autoreactive antibodies.

Bone marrow-derived naïve B lymphocytes improve heart function after myocardial infarction: a novel cardioprotective mechanism for empagliflozin.

The role of adaptive immunity in myocardial recovery post myocardial infarction (MI), particularly the immune response by B lymphocytes, remains elusive. Bone marrow immune microenvironment in response to MI is remotely regulated by the hypothalamic pituitary adrenal (HPA) axis. We utilized the cardioprotective actions of SGLT2 inhibitor to identify and characterize bone marrow B cell subsets that respond to myocardial injury. Initially, we preformed ligation of left anterior descendant (LAD) coronary artery in male C57BL/6J mice to monitor the dynamic changes of immune cells across tissues. Mechanistic insights from mouse models demonstrated arrest of bone marrow B cell maturation and function 24 h post MI. A secondary MI model (twice MIs) in mice was established for the first time to evaluate the dosage-dependent cardioprotection of empagliflozin (EMPA). Single-cell RNA-Seq further demonstrated that EMPA restored bone marrow naïve B cell (B220+CD19+CD43-IgM+IgD+) counts and function. Additionally, we recruited 14 acute MI patients with single LAD disease, and profiled B cells post percutaneous coronary intervention (PCI) (compared to 18 matched no-MI controls). We revealed a positive correlation of increased B cell counts with enhanced ejection fraction in MI patients with PCI while lymphopenia was associated with patients with heart failure. Mechanistically, MI triggers the release of glucocorticoids from neuroendocrine system, inducing NHE1-mediated autophagic death of bone marrow B cells while repressing B cell progenitor proliferation and differentiation. Infusion of B cells derived from bone marrow significantly improved cardiac function and diminished infarct size post MI. These findings provide new mechanistic insights into regulation of adaptive immune response post MI, and support targeting bone marrow B cell development for improved ventricular remodeling and reduced heart failure after MI.

IL-4-Induced Quiescence of Resting Naive B Cells Is Disrupted in Systemic Lupus Erythematosus.

Activated naive (aNAV) B cells have been shown to be the precursor of the CD11c+T-bet+ IgD-CD27- double-negative (DN)2 or atypical memory (aMEM) B cells in systemic lupus erythematosus (SLE). To determine factors that maintain resting naive (rNAV) B cells, the transcriptomic program in naive (IGHD+IGHM +) B cells in human healthy control subjects (HC) and subjects with SLE was analyzed by single-cell RNA-sequencing analysis. In HC, naive B cells expressed IL-4 pathway genes, whereas in SLE, naive B cells expressed type I IFN-stimulated genes (ISGs). In HC, aNAV B cells exhibited upregulation of the gene signature of germinal center and classical memory (cMEM) B cells. In contrast, in SLE, aNAV B cells expressed signature genes of aMEM. In vitro exposure of SLE B cells to IL-4 promoted B cell development into CD27+CD38+ plasmablasts/plasma and IgD-CD27+ cMEM B cells. The same treatment blocked the development of CD11c+Tbet+ aNAV and DN2 B cells and preserved DN B cells as CD11c-Tbet- DN1 B cells. Lower expression of IL-4R and increased intracellular IFN-ß in naive B cells was correlated with the accumulation of CD21-IgD- B cells and the development of anti-Smith and anti-DNA autoantibodies in patients with SLE (n = 47). Our results show that IL-4R and type I IFN signaling in naive B cells induce the development of distinct lineages of cMEM versus aMEM B cells, respectively. Furthermore, diminished IL-4R signaling shifted activated B cell development from the DN1 to the DN2 trajectory in patients with SLE. Therapies that enhance IL-4R signaling may be beneficial for ISGhi SLE patients.

Clinical characteristics and outcomes of IgD myeloma: experience across UK national trials.

Immunoglobulin D (IgD) myeloma is a subtype often considered to have adverse features and inferior survival, but there is a paucity of data from large clinical studies. We compare the clinical characteristics and outcomes of patients with IgD myeloma from UK phase 3 myeloma trials analyzed in 2 groups: old (1980-2002) and recent (2002-2016) clinical trials, based on the time of adoption of novel myeloma therapies. Patients with IgD myeloma comprised 44 of 2789 (1.6%) and 70 of 5773 (1.2%) of the old and recent trials, respectively. Overall, IgD myeloma was associated with male predominance, low-level paraproteinemia (<10g/L), and λ light chain preference. The frequency of ultra-high-risk cytogenetics was similar in IgD myeloma compared with other subtypes (4.3% vs 5.3%, P > .99). Despite the old trial series being a younger group (median age: 59 vs 63 years, P = .015), there was a higher frequency of bone lesions, advanced stage at diagnosis, worse performance status, and severe renal impairment compared with the recent trials. Furthermore, the early mortality rate was significantly higher for the old trial series (20% vs 4%, P = .01). The overall response rate following induction therapy was significantly higher in the recent trials (89% vs 43%, P < .0001), and this was consistent with improved median overall survival (48 months; 95% confidence interval [CI] 35-67 months vs 22 months; 95% CI, 16-29 months). Survival outcomes for IgD myeloma have significantly improved and are now comparable to other myeloma types because of earlier diagnosis, novel therapies, and improved supportive care. This trial was registered at clinicaltrials.gov as # NCT01554852.

IgD lambda multiple myeloma causing hyperammonaemia with possibly reduced ammonium excretion.

A man in his 70s presented with impaired consciousness due to hyperammonaemia while investigating multiple tumours in his brain, chest, spine and right adrenal gland. He did not have any disorders causing hyperammonaemia, such as liver dysfunction, urea-producing bacterial infection or any medications interfering with ammonium metabolism. Blood and urine tests in addition to tumour biopsy specimens confirmed immunoglobulin D lambda multiple myeloma. His general status responded to chemotherapy using bortezomib, dexamethasone and daratumumab, and he subsequently regained full consciousness and a normalised serum ammonia level. He, unfortunately, died of refractory multiple myeloma with hyperammonaemia. The autopsy specimen revealed lambda light-chain deposits in the distal tubule epithelium with cast precipitation and intact liver cells. Urine osmolality gap analysis suggested possibly reduced urinary ammonium excretion, but further investigation is necessary to elucidate the significance of pathological renal characteristics in multiple myeloma with hyperammonaemia.

[IgD multiple myeloma mimicking free light chain myeloma complicated by factor X deficiency: a case report]. / Myélome multiple à IgD mimant un myélome à chaines légères libres et compliqué de déficit en facteur X: à propos d'un cas.

IgD myeloma is an extremely rare haemopathy with severe clinical presentation. It can be confused with non-secretory or free light chain myeloma. We here report the case of a 72-year old female patient presenting with bone pain and diffuse ecchymosis and deterioration of her general condition. Laboratory tests showed monoclonal gammopathy associated with severe acute renal failure and low total protein (TP) (48%) with factor X deficiency. Etiological assessment confirmed the diagnosis of IgD lambda myeloma stage IIIb, according to Durie and Salmon, International Staging System (ISS) score III unfavorable cytogenetics. Patient's outcome was favorable after treatment with proteasome inhibitor, anti-CD 38 and corticosteroid therapy. Adequate treatment of IgD myeloma, using new therapeutic approaches and hematopoietic stem cell autotransplantation, can improve the prognosis.

Tumour cell characteristics and microenvironment composition correspond to clinical presentation in newly diagnosed nodular lymphocyte-predominant Hodgkin lymphoma.

Different studies have characterized the microenvironment and its prognostic impact in classic Hodgkin lymphoma whereas such analyses are pending for nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL). We thus investigated characteristics of tumour cells and microenvironment in NLPHL and evaluated possible correlations with the clinical presentation. Lymph node samples from 152 NLPHL patients who had first-line treatment within the randomized German Hodgkin Study Group HD16-HD18 trials were available and analysed with regard to IgD status and nuclear size of the tumour cells as well as presence of PD1-positive follicular T helper cells and CD163-positive macrophages in the microenvironment. While large tumour cell nuclei and high numbers of PD1-positive follicular T helper cells in the microenvironment were more common in patients presenting with early/intermediate stages than in patients with advanced-stage disease (p < 0.0001, unpaired t-test; p = 0.0022, Mann-Whitney test), no differences between risk groups were observed in terms of the IgD status of the tumour cells and the content of CD163-positive macrophages in the microenvironment. PD1-positive follicular T helper cells were present in both cases with typical and variant growth patterns and rosetting around the tumour cells was observed in 96% of patients, indicating an important role of PD1-positive follicular T helper cells in NLPHL.

Abnormal lower expression of GPR183 in peripheral blood T and B cell subsets of systemic lupus erythematosus patients.

G protein-coupled receptor 183 (GPR183) has been indicated to mediate the migration and localisation of immune cells in T cell-dependent antibody responses. Systemic lupus erythematosus (SLE) is a canonical autoimmune disease involving B cell-mediated tolerance destruction and excessive pathogenic autoantibody production, in which multiple GPCRs play a role. To date, there has been no systematic study regarding the expression of GPR183 in lymphocyte subsets of SLE patients. In this research, firstly, we observed the expression trends of GRP183 in various T and B cell subsets in human tonsil tissues. These lymphocyte subsets include CD4+, CD8+, naïve T, effector T, Tfh, activated Tfh, Th1, Th2, Th17, Treg, CD19+CD27-, CD19+CD27+, naïve B, germinal centre B, memory B, and plasma cells. Further, compared with healthy controls (HCs), GPR183 expression levels in above peripheral blood lymphocyte subsets of patients with SLE were reduced overall. The differential expression of GPR183 expression between inactive and active SLE patients indicates that GPR183 expression may be concerned with the disease activity of SLE. This was further confirmed through the strong negative correlation with SLEDAI score and positive correlation with serum complement protein C3, C4 and C1q levels. Further receiver operating characteristic (ROC) curve analysis revealed that GPR183 expression in circulating CD27-IgD+ B cells may be beneficial in distinguishing between inactive and active SLE patients. In addition, type I interferon stimulation could down-regulate the expression of GPR183 in peripheral blood T and B cell subsets. Aberrant expression of GPR183 may provide some novel insights into disease activity prediction and underlying pathogenesis of SLE.

Improving naive B cell isolation by absence of CD45RB glycosylation and CD27 expression in combination with BCR isotype.

In past years ex vivo and in vivo experimental approaches involving human naive B cells have proven fundamental for elucidation of mechanisms promoting B cell differentiation in both health and disease. For such studies, it is paramount that isolation strategies yield a population of bona fide naive B cells, i.e., B cells that are phenotypically and functionally naive, clonally non-expanded, and have non-mutated BCR variable regions. In this study different combinations of common as well as recently identified B cell markers were compared to isolate naive B cells from human peripheral blood. High-throughput BCR sequencing was performed to analyze levels of somatic hypermutation and clonal expansion. Additionally, contamination from mature mutated B cells intrinsic to each cell-sorting strategy was evaluated and how this impacts the purity of obtained populations. Our results show that current naive B cell isolation strategies harbor contamination from non-naive B cells, and use of CD27-IgD+ is adequate but can be improved by including markers for CD45RB glycosylation and IgM. The finetuning of naive B cell classification provided herein will harmonize research lines using naive B cells, and will improve B cell profiling during health and disease, e.g. during diagnosis, treatment, and vaccination strategies.

Establishment of mouse model of inherited PIGO deficiency and therapeutic potential of AAV-based gene therapy.

Inherited glycosylphosphatidylinositol (GPI) deficiency (IGD) is caused by mutations in GPI biosynthesis genes. The mechanisms of its systemic, especially neurological, symptoms are not clarified and fundamental therapy has not been established. Here, we report establishment of mouse models of IGD caused by PIGO mutations as well as development of effective gene therapy. As the clinical manifestations of IGD are systemic and lifelong lasting, we treated the mice with adeno-associated virus for homology-independent knock-in as well as extra-chromosomal expression of Pigo cDNA. Significant amelioration of neuronal phenotypes and growth defect was achieved, opening a new avenue for curing IGDs.