Antibody-producing Plasma Cells Research Articles

#1339 The characteristic of memory B-cell subsets in patients with IgA-nephropathy

Abstract Background and Aims Impaired B-cell development has been postulated to play an important role in the maintaining of autoimmune inflammation what makes memory B-cells a perspective target for a new therapeutic strategy in IgA-nephropathy (IgAN). However, to date there are few and controversial data about the precise role of circulating memory B-cell subsets in clinical progression of IgAN. The aim was to estimate the immunological profile of memory B-cell subpopulations in the peripheral blood of IgAN patients. Method The peripheral blood was obtained from 20 IgAN patients (aged of 32.0 (27.0-36.0) y.o., male/female ratio as 13/7) and 15 donors (aged of 38.0 (30.0-46.0) y.o., male/female ratio as 10/5). The diagnosis was confirmed by morphological examination of the biopsy material. The phenotype of B-cells subsets was determined by a panel of CD38-PE/CD19-ECD/CD27-PC5/IgD-APC antibodies; γδT-lymphocytes—by a panel of TCRγδ-FITC/TCRαβ-PE/HLA-DR-ECD/TCRVδ1-PC7/CD3-APC-A750/TCRVδ2-PB/ CD45-KRO antibodies using flow cytometry method (Cytoflex, Beckman Coulter, USA). The concentration of B-cell activating factor (BAFF) was measured using enzyme-linked immunosorbent assay. Statistical data processing was done in Statistica 10.0 program. Results Based on cell surface markers expression the following B-cells subsets were identified in the peripheral blood: naïve B-cells (CD19+CD27−IgD+), pre-switched B-cells (CD19+CD27+IgD+), switched B-cells (CD19+CD27+IgD−), plasmablasts (CD19+CD27+CD38+) and long-lived plasma cells (CD27hiCD38hi) (Fig. 1). The altered balance in B-cells maturation characterizing by a significant lower percent of pre-switched B-cells and plasmablasts (p < 0.05) as well as a higher trend (>55%) in the naive B-cells (p < 0.01) was established in IgAN patients as compared to healthy donors reflecting the exhaustion of peripheral blood plasmablasts due to constant generation of antibody-producing plasma cells. Moreover, the lower pre-switched B-cells percentage was detected in the blood, the more BAFF production was observed in serum of IgAN patients (R = 0.50; p < 0.05) and the higher proteinuria level was detected (R = 0.47; p < 0.05). The increased total number of γδТ-cells up to 9.42 (6.25-12.44)% in IgAN patients as compared to donors (p = 0.03) was correlated with total memory CD19+CD27+B-cells numbers (R = 0.54; p < 0.05) as well as pre-switched B-cells (R = 0.45; p < 0.05), plasmablasts (R = 0.57; p < 0.01) and long-lived plasma cells (R = 0.51; p < 0.05). A detailed subsets analysis revealed an elevated level of tissue-resident mucosa-associated cells (Vδ1+ and Vδ3+T-lymphocytes) as well as enhanced HLA-DR expression on them (p < 0.05) in combination with decreased normally circulating Vδ2+T-cells numbers (p < 0.01) as compared to healthy donors what characterized Vδ1+ and Vδ3+T-cells subsets as professional antigen presenting cells and indicated their possible role in the priming of antigen specific B-cells. Conclusion Suggesting that most peripheral B-lymphocytes are naïve, the obtained data may reflect a γδT-cells role in migration of pre-switched B-cells from the circulation to mucosa sites for possible further maturation and class-switching what allows us to consider these two parameters as potential useful biomarkers of IgAN disease prognosis in clinical practice.

CD4+ T cell activation distinguishes response to anti-PD-L1+anti-CTLA4 therapy from anti-PD-L1 monotherapy

Cancer patients often receive a combination of antibodies targeting programmed death-ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen-4 (CTLA4). We conducted a window-of-opportunity study in head and neck squamous cell carcinoma (HNSCC) to examine the contribution of anti-CTLA4 to anti-PD-L1 therapy. Single-cell profiling of on- versus pre-treatment biopsies identified Tcell expansion as an early response marker. In tumors, anti-PD-L1 triggered the expansion of mostly CD8+ Tcells, whereas combination therapy expanded both CD4+ and CD8+ Tcells. Such CD4+ Tcells exhibited an activated T helper 1 (Th1) phenotype. CD4+ and CD8+ Tcells co-localized with and were surrounded by dendritic cells expressing Tcell homing factors or antibody-producing plasma cells. Tcell receptor tracing suggests that anti-CTLA4, but not anti-PD-L1, triggers the trafficking of CD4+ naive/central-memory Tcells from tumor-draining lymph nodes (tdLNs), via blood, to the tumor wherein Tcells acquire a Th1 phenotype. Thus, CD4+ Tcell activation and recruitment from tdLNs are hallmarks of early response to anti-PD-L1 plus anti-CTLA4 in HNSCC.

CD19 Chimeric Antigen Receptor T Cell Treatment: Unraveling the Role of B Cells in Systemic Lupus Erythematosus.

B cell generation of autoantibodies is a crucial step in the pathogenesis of systemic lupus erythematosus (SLE). After their differentiation in the bone marrow, B cells populate the secondary lymphatic organs, where they undergo further maturation leading to the development of memory B cells as well as antibody-producing plasmablasts and plasma cells. Targeting B cells is an important strategy to treat autoimmune diseases such as SLE, in which B cell tolerance is disturbed and autoimmune B cells and autoantibodies emerge. This review discusses the functional aspects of antibody- and cell-based B cell-depleting therapy in SLE. It thereby particularly focuses on lessons learned from chimeric antigen receptor (CAR) T cell treatment on the role of B cells in SLE for understanding B cell pathology in SLE. CAR T cells model a deep B cell depletion and thereby allow understanding the role of aberrant B cell activation in the pathogenesis of SLE. Furthermore, the effects of B cell depletion on autoantibody production can be better described, ie, explaining the concept of different cellular sources of (auto-) antibodies in the form of short-lived plasmablasts and long-lived plasma cells, which differ in their susceptibility to B cell depletion and require different targeted therapeutic approaches. Finally, the safety of deep B cell depletion in autoimmune disease is discussed.

Translating Bcell immunology to the treatment of antibody-mediated allograft rejection.

Antibody-mediated rejection (AMR), including chronic AMR (cAMR), causes ~50% of kidney allograft losses eachyear. Despite attempts to develop well-tolerated and effective therapeutics for the management of AMR, to date, none has obtained FDA approval, thereby highlighting an urgent unmet medical need. Discoveries over the past decade from basic, translational and clinical studies of transplant recipients have provided a foundation for developing novel therapeutic approaches to preventing and treating AMR and cAMR. These interventions are aimed at reducing donor-specific antibody levels, decreasing graft injury and fibrosis, and preserving kidney function. Innovative approaches emerging from basic science findings include targeting interactions between alloreactive T cells and Bcells, and depleting alloreactive memory Bcells, as well as donor-specific antibody-producing plasmablasts and plasma cells. Therapies aimed at reducing the cytotoxic antibody effector functions mediated by natural killercells and the complement system, and their associated pro-inflammatory cytokines, are also undergoing evaluation. The complexity of the pathogenesis of AMR and cAMR suggest that multiple approaches will probably be required to treat these disease processes effectively. Definitive answers await results from large, double-blind, multicentre, randomized controlled clinical trials.

Factors determining the sensitivity to proteasome inhibitors of multiple myeloma cells.

Multiple myeloma is an incurable cancer that originates from antibody-producing plasma cells. It is characterized by an intrinsic ability to produce large amounts of immunoglobulin-like proteins. The high rate of synthesis makes myeloma cells dependent on protein processing mechanisms related to the proteasome. This dependence made proteasome inhibitors such as bortezomib and carfilzomib one of the most important classes of drugs used in multiple myeloma treatment. Inhibition of the proteasome is associated with alteration of a number of important biological processes leading, in consequence, to inhibition of angiogenesis. The effect of drugs in this group and the degree of patient response to the treatment used is itself an extremely complex process that depends on many factors. At cellular level the change in sensitivity to proteasome inhibitors may be related to differences in the expression level of proteasome subunits, the degree of proteasome loading, metabolic adaptation, transcriptional or epigenetic factors. These are just some of the possibilities that may influence differences in response to proteasome inhibitors. This review describes the main cellular factors that determine the degree of response to proteasome inhibitor drugs, as well as information on the key role of the proteasome and the performance characteristics of the inhibitors that are the mainstay of multiple myeloma treatment.

Successful Use of Bortezomib for Recurrent Progressive Familial Intrahepatic Cholestasis Type II After Liver Transplantation: A Pediatric Case with a 9-Year Follow-Up.

Recurrence of progressive familial intrahepatic cholestasis (PFIC) type II poses challenges during postoperative liver transplant care. Posttransplant patients with PFIC type II risk developing recurrent cholestasis with normal gamma-glutamyl transferase activity, which mimics the original bile salt export pump (BSEP) protein deficiency and is related to a form of immunoglobulin G antibody (anti-BSEP)-mediated rejection. Bortezomib effectively induces apoptosis of actively antibody-producing plasma cells that may have a role in antibody-mediated rejection. In this case, we used bortezomib to treat PFIC type II recurrence after liver transplantation in a child.

Sample average treatment effect on the treated (SATT) analysis using counterfactual explanation identifies BMT and SARS-CoV-2 vaccination as protective risk factors associated with COVID-19 severity and survival in patients with multiple myeloma

Patients with multiple myeloma (MM), an age-dependent neoplasm of antibody-producing plasma cells, have compromised immune systems and might be at increased risk for severe COVID-19 outcomes. This study characterizes risk factors associated with clinical indicators of COVID-19 severity and all-cause mortality in myeloma patients utilizing NCATS’ National COVID Cohort Collaborative (N3C) database. The N3C consortium is a large, centralized data resource representing the largest multi-center cohort of COVID-19 cases and controls nationwide (>16 million total patients, and >6 million confirmed COVID-19+ cases to date). Our cohort included myeloma patients (both inpatients and outpatients) within the N3C consortium who have been diagnosed with COVID-19 based on positive PCR or antigen tests or ICD-10-CM diagnosis code. The outcomes of interest include all-cause mortality (including discharge to hospice) during the index encounter and clinical indicators of severity (i.e., hospitalization/emergency department/ED visit, use of mechanical ventilation, or extracorporeal membrane oxygenation (ECMO)). Finally, causal inference analysis was performed using the Coarsened Exact Matching (CEM) and Propensity Score Matching (PSM) methods. As of 05/16/2022, the N3C consortium included 1,061,748 cancer patients, out of which 26,064 were MM patients (8,588 were COVID-19 positive). The mean age at COVID-19 diagnosis was 65.89 years, 46.8% were females, and 20.2% were of black race. 4.47% of patients died within 30 days of COVID-19 hospitalization. Overall, the survival probability was 90.7% across the course of the study. Multivariate logistic regression analysis showed histories of pulmonary and renal disease, dexamethasone, proteasome inhibitor/PI, immunomodulatory/IMiD therapies, and severe Charlson Comorbidity Index/CCI were significantly associated with higher risks of severe COVID-19 outcomes. Protective associations were observed with blood-or-marrow transplant/BMT and COVID-19 vaccination. Further, multivariate Cox proportional hazard analysis showed that high and moderate CCI levels, International Staging System (ISS) moderate or severe stage, and PI therapy were associated with worse survival, while BMT and COVID-19 vaccination were associated with lower risk of death. Finally, matched sample average treatment effect on the treated (SATT) confirmed the causal effect of BMT and vaccination status as top protective factors associated with COVID-19 risk among US patients suffering from multiple myeloma. To the best of our knowledge, this is the largest nationwide study on myeloma patients with COVID-19.

A SAGA Complex-Specific Dependency in Multiple Myeloma Orchestrates Oncogenic Transcriptional Programs

Multiple myeloma (MM) is a malignancy of antibody-producing plasma cells that reside within the bone marrow. Epigenetic factors contribute to the initiation, progression, relapse and clonal heterogeneity in MM, but our knowledge of epigenetic regulators involved in MM development is far from complete. Results from the Cancer Dependency Map (DepMap) Project revealed that several components of the SAGA complex are particularly important for MM cell growth and survival. The SAGA complex serves as a coactivator in transcription and also catalyzes histone acetylation and deubiquitination via its lysine acetyltransferase (KAT) and deubiquitinase (DUB) modules, respectively. Our analysis showed that each SAGA complex component is overexpressed in at least 50% of MM patients. To investigate SAGA-specific functions, we centered on ADA2B, a subunit in the KAT module that specifically functions in the SAGA complex. We observed reduced cell viability upon ADA2B knockdown and CRISPR/Cas9-mediated knockout in MM cell lines. To identify the underlying transcriptional pathways that ADA2B regulate, we performed transcriptome sequencing using MM cell lines with and without ADA2B depletion. Our results showed several oncogenic pathways, including MYC, E2F and MM-specific MAF oncogenic programs, are tightly regulated by ADA2B. We also discovered that the protein but not transcript levels of MAF and the KATs in SAGA, GCN5 and PCAF, as well as the global level of histone H3 lysine 9 acetylation (H3K9ac) are all prominently decreased upon ADA2B depletion. To investigate whether the global reduction in H3K9ac would alter chromatin accessibility, we performed assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and found decreased accessibility at many cancer marker and cancer-promoting genes. To decipher the protein domains that are essential for ADA2B function in MM, we generated and expressed mutated versions of ADA2B in MM cell lines. Excitingly, mutations of core hydrophobic amino acid residues in the SANT domain disrupt interactions with GCN5 and PCAF and negatively affect protein stability of ADA2B. Hence, drug inhibitors that target the SANT domain could achieve suppression of ADA2B and MM cell growth. Our findings uncover novel epigenetic and transcriptional mechanisms controlling MM development, and suggest potential for new epigenetic inhibitors targeting SAGA-specific ADA2B as future treatment modalities for MM.

Role of affinity in plasma cell development in the germinal center light zone.

Protective immune responses to many pathogens depend on the development of high-affinity antibody-producing plasma cells (PC) in germinal centers (GCs). Transgenic models suggest that there is a stringent affinity-based barrier to PC development. Whether a similar high-affinity barrier regulates PC development under physiologic circumstances and the nature of the PC fate decision has not been defined precisely. Here, we use a fate-mapping approach to examine the relationship between GC B cells selected to undergo additional rounds of affinity maturation, GC pre-PC, and PC. The data show that initial PC selection overlaps with GC B cell selection, but that the PC compartment accumulates a less diverse and higher affinity collection of antibodies over time. Thus, whereas the GC continues to diversify over time, affinity-based pre-PC selection sieves the GC to enable the accumulation of a more restricted group of high-affinity antibody-secreting PC.

Bruton’s tyrosine kinase is a possible therapeutic target in microscopic polyangiitis

BackgroundBruton’s tyrosine kinase (Btk) is an enzyme expressed in leukocytes other than T lymphocytes and plasma cells and involved in B-cell receptor- and Fcγ receptor (FcγR)-mediated signal transduction. Btk inhibitors potentially suppress autoantibody production due to the expected inhibitory ability of B lymphocyte differentiation into antibody-producing plasma cells and reduce FcγR-mediated neutrophil activation, including the release of neutrophil extracellular traps (NETs). Microscopic polyangiitis (MPA) is a systemic small-vessel vasculitis characterized by the pathogenic autoantibody, antineutrophil cytoplasmic antibody (ANCA) that reacts with myeloperoxidase (MPO). MPO and MPO-ANCA immune complex (IC)-induced FcγR-mediated NETs are critically involved in MPA pathogenesis. This study aimed to demonstrate the therapeutic efficacy of the Btk inhibitor tirabrutinib on MPA.MethodsVarious doses of tirabrutinib or vehicle were orally administered to Sprague–Dawley rats daily. Four weeks later, the number of peripheral B lymphocytes was counted, and Btk phosphorylation in B lymphocytes was evaluated by flow cytometry. Human peripheral blood neutrophils were stimulated by MPO and anti-MPO antibody ICs (MPO and anti-MPO-ICs), and Btk and its downstream Vav phosphorylation were assessed by western blotting. The effects of tirabrutinib on MPO and anti-MPO-IC-induced NET formation were examined in vitro. Wistar Kyoto rats were immunized with human MPO to induce experimental MPA and given drug-free or tirabrutinib-containing feed (0.0037% or 0.012%) from day 0 or 28. All rats were euthanized on day 42 for serological and histological evaluation.ResultsTirabrutinib inhibited Btk phosphorylation without decreasing B lymphocytes in vivo. Neutrophil Btk and Vav were phosphorylated when stimulated with MPO and anti-MPO-ICs. Tirabrutinib suppressed MPO and anti-MPO-IC-induced NET formation in vitro and ameliorated experimental MPA in a dose-dependent manner in vivo. Although MPO-ANCA production was not affected, NET-forming neutrophils in the blood were significantly reduced by tirabrutinib.ConclusionsThe Btk inhibitor tirabrutinib suppressed MPO and anti-MPO-IC-induced NET formation in vitro and ameliorated experimental MPA by reducing NET-forming neutrophils but not decreasing MPO-ANCA titer in vivo. This study suggests that Btk is a possible therapeutic target in MPA.

Higher MRI lesion load in multiple sclerosis is related to the N-glycosylation changes of cerebrospinal fluid immunoglobulin G.

Intrathecal clonal expansion of antibody-producing plasma cells in multiple sclerosis (MS) perpetuates central nervous system injury and is associated with active demyelination. Immunoglobulin G (IgG) effector functions are modulated by linked N-glycan structures. The aim of the study was to detect potential differences in N-glycosylation of IgG in serum and cerebrospinal fluid (CSF) and total sera proteins between people with MS and those in whom the diagnosis of MS was excluded. Furthermore, we investigated the association with standard laboratory biomarkers of intrathecal inflammation as well as clinical and neuroradiological disease activity. This cross-sectional study included patients with suspected demyelinating disease. MS diagnosis was based on the 2017 McDonald criteria and controls were patients with excluded MS diagnosis. N-glycans were compared with Expanded Disability Status Scale (EDSS), magnetic resonance imaging (MRI) markers of disease activity and biomarkers of intrathecal inflammation (cell count, CSF-IgG concentration, percentage of intrathecal IgG, oligoclonal bands (OCB), virus-specific antibody index (MRZH reaction)). Differences between groups were observed only in the CSF-IgG N-glycome. In MS, the presence of bisecting N-acetylglucosamine (Padj=2.63E-05) and monogalactosylation (Padj=1.49E-06) were more abundant and associated with positive OCBs. N-glycans monogalactosylated at the α6 arm FA2[6]G1 (r=0.56) and FA2[6]BG1 (r=0.45) correlated with percentage of intrathecal IgG, but not total CSF-IgG. This trait was also more abundant in MRZH positive people with MS who had higher MRI lesion load (P=0.018) but unrelated to active lesions or EDSS. More abundant monogalactosylation of intrathecally synthesized IgG is the most prominent trait in MS and is associated with higher MRI lesion load.

Building the synapse engine to drive B lymphocyte function

B cell receptor (BCR)-mediated antigen-specific recognition activates B lymphocytes and drives the humoral immune response. This enables the generation of antibody-producing plasma cells, the effector arm of the B cell immune response, and of memory B cells, which confer protection against additional encounters with antigen. B cells search for cognate antigen in the complex cellular microarchitecture of secondary lymphoid organs, where antigens are captured and exposed on the surface of different immune cells. While scanning the cell network, the BCR can be stimulated by a specific antigen and elicit the establishment of the immune synapse with the antigen-presenting cell. At the immune synapse, an integrin-enriched supramolecular domain is assembled at the periphery of the B cell contact with the antigen-presenting cell, ensuring a stable and long-lasting interaction. The coordinated action of the actomyosin cytoskeleton and the microtubule network in the inner B cell space provides a structural framework that integrates signaling events and antigen uptake through the generation of traction forces and organelle polarization. Accordingly, the B cell immune synapse can be envisioned as a temporal engine that drives the molecular mechanisms needed for successful B cell activation. Here, I review different aspects of the B cell synapse engine and provide insights into other aspects poorly known or virtually unexplored.

Highly Cross-Reactive and Protective Influenza A Virus H3N2 Hemagglutinin- and Neuraminidase-Specific Human Monoclonal Antibodies.

Due to antigenic drift and shift of influenza A viruses (IAV) and the tendency to elicit predominantly strain-specific antibodies, humanity remains susceptible to new strains of seasonal IAV and is at risk from viruses with pandemic potential for which limited or no immunity may exist. The genetic drift of H3N2 IAV is specifically pronounced, resulting in two distinct clades since 2014. Here, we demonstrate that immunization with a seasonal inactivated influenza vaccine (IIV) results in increased levels of H3N2 IAV-specific serum antibodies against hemagglutinin (HA) and neuraminidase (NA). Detailed analysis of the H3N2 B cell response indicated expansion of H3N2-specific peripheral blood plasmablasts 7 days after IIV immunization which expressed monoclonal antibodies (MAbs) with broad and potent antiviral activity against many H3N2 IAV strains as well as prophylactic and therapeutic activity in mice. These H3N2-specific B cell clonal lineages persisted in CD138+ long-lived bone marrow plasma cells. These results demonstrate that IIV-induced H3N2 human MAbs can protect and treat influenza virus infection in vivo and suggest that IIV can induce a subset of IAV H3N2-specific B cells with broad protective potential, a feature that warrants further study for universal influenza vaccine development. IMPORTANCE Influenza A virus (IAV) infections continue to cause substantial morbidity and mortality despite the availability of seasonal vaccines. The extensive genetic variability in seasonal and potentially pandemic influenza strains necessitates new vaccine strategies that can induce universal protection by focusing the immune response on generating protective antibodies against conserved targets within the influenza virus hemagglutinin and neuraminidase proteins. We have demonstrated that seasonal immunization with inactivated influenza vaccine (IIV) stimulates H3N2-specific monoclonal antibodies in humans that are broad and potent in their neutralization of virus in vitro. These antibodies also provide protection from H3N2 IAV in a mouse model of infection. Furthermore, they persist in the bone marrow, where they are expressed by long-lived antibody-producing plasma cells. This significantly demonstrates that seasonal IIV can induce a subset of H3N2-specific B cells with broad protective potential, a process that if further studied and enhanced could aid in the development of a universal influenza vaccine.

Krüppel-like factor 2: a central regulator of B cell differentiation and plasma cell homing.

The development of B cells, their activation and terminal differentiation into antibody-producing plasma cells are characterized by alternating phases of proliferation and quiescence that are controlled by complex transcriptional networks. The spatial and anatomical organization of B cells and plasma cells inside lymphoid organs as well as their migration within lymphoid structures and between organs are prerequisites for the generation and the maintenance of humoral immune responses. Transcription factors of the Krüppel-like family are critical regulators of immune cell differentiation, activation, and migration. Here, we discuss the functional relevance of Krüppel-like factor 2 (KLF2) for B cell development, B cell activation, plasma cell formation and maintenance. We elaborate on KLF2-mediated regulation of B cell and plasmablast migration in the context of immune responses. Moreover, we describe the importance of KLF2 for the onset and the progression of B cell-related diseases and malignancies.

Antigen-specific B cells direct T follicular-like helper cells into lymphoid follicles to mediate Mycobacterium tuberculosis control.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a global cause of death. Granuloma-associated lymphoid tissue (GrALT) correlates with protection during TB, but the mechanisms of protection are not understood. During TB, the transcription factor IRF4 in T cells but not B cells is required for the generation of the TH1 and TH17 subsets of helper T cells and follicular helper T (TFH)-like cellular responses. A population of IRF4+ T cells coexpress the transcription factor BCL6 during Mtb infection, and deletion of Bcl6 (Bcl6fl/fl) in CD4+ T cells (CD4cre) resulted in reduction of TFH-like cells, impaired localization within GrALT and increased Mtb burden. In contrast, the absence of germinal center B cells, MHC class II expression on B cells, antibody-producing plasma cells or interleukin-10-expressing B cells, did not increase Mtb susceptibility. Indeed, antigen-specific B cells enhance cytokine production and strategically localize TFH-like cells within GrALT via interactions between programmed cell death 1 (PD-1) and its ligand PD-L1 and mediate Mtb control in both mice and macaques.

Pathophysiology of myelin oligodendrocyte glycoprotein antibody disease.

Myelin Oligodendrocyte Glycoprotein Antibody Disease (MOGAD) is a spectrum of diseases, including optic neuritis, transverse myelitis, acute disseminated encephalomyelitis, and cerebral cortical encephalitis. In addition to distinct clinical, radiological, and immunological features, the infectious prodrome is more commonly reported in MOGAD (37-70%) than NMOSD (15-35%). Interestingly, pediatric MOGAD is not more aggressive than adult-onset MOGAD, unlike in multiple sclerosis (MS), where annualized relapse rates are three times higher in pediatric-onset MS. MOGAD pathophysiology is driven by acute attacks during which T cells and MOG antibodies cross blood brain barrier (BBB). MOGAD lesions show a perivenous confluent pattern around the small veins, lacking the radiological central vein sign. Initial activation of T cells in the periphery is followed by reactivation in the subarachnoid/perivascular spaces by MOG-laden antigen-presenting cells and inflammatory CSF milieu, which enables T cells to infiltrate CNS parenchyma. CD4+ T cells, unlike CD8+ T cells in MS, are the dominant T cell type found in lesion histology. Granulocytes, macrophages/microglia, and activated complement are also found in the lesions, which could contribute to demyelination during acute relapses. MOG antibodies potentially contribute to pathology by opsonizing MOG, complement activation, and antibody-dependent cellular cytotoxicity. Stimulation of peripheral MOG-specific B cells through TLR stimulation or T follicular helper cells might help differentiate MOG antibody-producing plasma cells in the peripheral blood. Neuroinflammatory biomarkers (such as MBP, sNFL, GFAP, Tau) in MOGAD support that most axonal damage happens in the initial attack, whereas relapses are associated with increased myelin damage.

Inhibiting B cell activating factor attenuates preeclamptic symptoms in placental ischemic rats.

Preeclampsia (PE), new-onset hypertension during pregnancy, is associated with a pro-inflammatory state with activated T cells, cytolytic natural killer (NK) cells, dysregulated complement proteins, and B cells secreting agonistic autoantibodies to the angiotensin II type-1 receptor (AT1-AA). The reduced uterine perfusion pressure (RUPP) model of placental ischemia recapitulates these features of PE. Blocking CD40L-CD40 communication between T and B cells or B cell depletion with Rituximab prevents hypertension and AT1-AA production in RUPP rats. This suggests that T cell-dependent B cell activation contributes to the hypertension and AT1-AA associated with PE. B2 cells maturing into antibody producing plasma cells are the product of T cell-dependent B cell-interactions and B cell Activating Factor (BAFF) is an integral cytokine in the development of B2 cells specifically. Thus, we hypothesize that BAFF blockade will selectively deplete B2 cells, therefore reducing blood pressure, AT1-AA, activated NK Cells, and complement in the RUPP rat model of PE. Gestational Day (GD) 14 pregnant rats underwent the RUPP procedure, and a subset were treated with 1mg/kg Anti-BAFF antibodies via jugular catheters. On GD19, blood pressure was measured, B cells and NK cells were measured by flow cytometry, AT1-AA was measured by cardiomyocyte bioassay, and complement activation was measured by ELISA. Anti-BAFF therapy attenuated hypertension, AT1-AA, NK cell activation, and APRIL levels in RUPP rats without negatively impacting fetal outcomes. This study demonstrates that B2 cells contribute to hypertension, AT1-AA, and NK cell activation in response to placental ischemia during pregnancy.

Autoimmune Mechanisms in Focal Epilepsy of Unknown Cause

ABSTRACT The manifestation of immunological findings in diverse disorders presenting with seizures points to autoimmunity and inflammation in the etiology of epilepsy. Typical examples of autoimmunity-associated epilepsy are autoimmune encephalitis, Rasmussen encephalitis, and glutamic acid decarboxylase (GAD) antibody-positive temporal lobe epilepsy (TLE). The last entity is a typical example of antibody-positive focal epilepsy of unknown cause (FEUC). One of the most prominent findings emphasizing the coexistence of epilepsy and autoimmunity is the detection of anti-neuronal antibodies in patients manifesting with seizures. Emergence of antibody-producing plasma cells in the early course of GAD-antibody-positive TLE and induction of seizures in rodents upon intracerebral administration of N-methyl-D-aspartate receptor antibodies indicate that anti-neuronal antibodies may play a causal (rather than bystander) role in the induction of seizures. By contrast, innate immunity of the central nervous system (CNS) and infiltrating cytotoxic T-cells appear to participate in Rasmussen encephalitis and autoimmune encephalitis with antibodies to intracellular antigens. In addition, repetitive seizures may activate glial cells through the release of damage-associate molecular pattern mediators and activation of toll-like receptors, which in turn leads to disrupted blood–brain barrier and increased cerebral infiltration of peripheral blood immune cells. In conclusion, complex interactions of humoral and cellular immunity in the CNS appear to cause or at least contribute to seizure induction in FEUC. The nature of these interactions has recently started to be understood. Investigation of these mechanisms is substantial for the discovery of new treatment strategies and biomarkers in epilepsy.

Werner helicase is required for proliferation and DNA damage repair in multiple myeloma

Multiple myeloma (MM), characterized by extensive genomic instability and aberrant DNA damage repair, is a plasma cell malignancy due to the excessive proliferation of monoclonal antibody-producing plasma cells in the bone marrow. Despite the significant improvement in the survival of patients with the development of novel therapeutic agents, MM remains an incurable disease. Werner (WRN) helicase, a member of the RecQ helicase family that contributes to DNA replication, recombination, and repair, has been highlighted in cancer cell survival, yet the role and mechanism of WRN in MM remain unclear. Increased mRNA expression of WRN in newly diagnosed and relapsed CD138+ myeloma plasma cells than normal CD138+ plasma cells and their matched CD138- non-tumorigenic cells were detected by qPCR. Using NSC19630, a specific WRN helicase inhibitor, we further showed decreased cell viability, proliferation, and DNA repair and increased DNA damage and apoptosis in MM cells by MTT assay, cell cycle assay, apoptosis assay, and Western blotting. The results of the present study demonstrate that WRN is essential in MM cell viability, proliferation, and genomic stability, indicating its inhibition may enhance the efficacy of chemotherapy in MM.

Sars-Cov-2 Vaccinations Do Not Lead to Progression of Monoclonal Gammopathy of Undetermined Significance: Results from the Population-Based Istopmm Screening Study

Background: In patients with monoclonal gammopathy of undetermined significance (MGUS), the pre-malignant cells are antibody producing plasma cells. Stimulating humoral immunity mediated by plasma cells is an important factor in vaccine efficacy. Therefore, concerns have been raised about whether vaccine administration in patients with MGUS could trigger progression of the underlying pre-malignant clone, leading to an increase in the monoclonal-(M)-protein or even progression to full-blown malignancy. Immune stimulation has been found to be a risk factor for monoclonal gammopathies. However, immune stimulation inherent to vaccines and the subsequent antibody formation by plasma cells has, to our knowledge, not been studied in a systematic manner in MGUS. The current SARS-CoV-2 pandemic provide a unique opportunity to evaluate if SARS-CoV-2 vaccination has an impact on the risk of progression from MGUS to MM, or not. To study this we performed a prospective nationwide study based on the Iceland Screens, Treats, or Prevents Multiple Myeloma (iStopMM) study. Methods: The iStopMM study screened a total of 75,422 individuals for M protein and free light chains (FLC) between September 2016 and December 2020. The study diagnosed 3,358 individuals with MGUS and then randomized them to one of three arms. Individuals in arms 2 and 3 (N=2,037) are followed longitudinally with repeated serum protein electrophoresis (SPEP) and FLC and comprise the study population. All SARS-CoV-2 vaccinations in Iceland are centrally registered, which gives complete nationwide information on vaccination coverage, type of vaccine used, and frequency of administration. By cross-linking the vaccine data to the iStopMM database, MGUS patients who had received at least one SARS-CoV-2 vaccination and had follow-up serum samples after vaccination were identified. As M protein levels change with age, linear mixed modelling was used to estimate changes in M protein concentration as a function of age before vaccination and after vaccination. The slope of the evolution of M protein level over age was modelled as a continuous linear effect and compared before and after each vaccination to determine the effects of SAR-CoV-2 vaccination on changes in M protein levels. Results: A total of 1,814 SARS-CoV-2 vaccinated MGUS individuals were included in the study. The participants had 6,094 serum samples available with a median of 3 (range 1-21) per person (Table 1). All had at least one M protein measurement after receiving at least a single dose of vaccine. Median age at first vaccination was 71 (range 42-98) years and 53.9% were males. Median follow-up was 2.3 (range 0.5-5.5) years, and 98.9% of individuals had received at least two doses of SARS-CoV-2 vaccine. The most common vaccine (first dose) was BNT162b2 (Pfizer) 54.4%, followed by ChAdOx1 (Astra Zeneca) 38.0%, mrna-1273 (Moderna) 5.7% and AD26.COV2.S (Janssen) 1.9%. Comparing M protein levels pre- and post-vaccination showed a 1.9% increase in M protein concentration in males and 0.3% in females. However, there was no difference in the rate of M protein increase following vaccination compared to that observed before vaccination. This was true for both men and women (Figure A). After adjusting for age, sex, and calendar year, no difference in M protein concentration was observed when comparing the increase before and after vaccination (Exponentiated beta coefficient (Exp(β)): 0.99; 95% confidence interval [CI], 0.96-1.03). The same was true when analyzed for each sex separately (Exp(β): 1.00; 95% CI, 0.96-1.04 for males and Exp(β) 0.98; 95% CI, 0.93-1.04 for females). No difference was observed between the different types of vaccines used. Similarly, neither second doses of vaccine (Exp(β): 1.00; 95% CI, 0.96-1.04) nor boosters (Exp(β): 1.03; 95% CI, 0.94-1.12) had an impact on the M protein concentration. Conclusion: In this large, prospective, population-based, screening study including 1,814 individuals with MGUS who were observed before and after covid vaccinations, we found no evidence for MGUS progression after SARS-CoV-2 vaccination. The same was true when analyzed separately by sex, age, type of vaccine, and the number of doses given. Our findings indicate that SARS-CoV-2 vaccination is safe in individuals with MGUS and does not lead to progression irrespective of the number of vaccine doses administered and type of vaccine used. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal