scholarly journals CD27-CD38lowCD21low B-Cells Are Increased in Axial Spondyloarthritis

2021 ◽  
Vol 12 ◽  
Author(s):  
Rick Wilbrink ◽  
Anneke Spoorenberg ◽  
Suzanne Arends ◽  
Kornelis S. M. van der Geest ◽  
Elisabeth Brouwer ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Axial Spondyloarthritis ◽  
Disease Process ◽  
Immune Markers ◽  
Cell Compartment ◽  
Active Involvement ◽  
Transitional B Cells ◽  
Healthy Donors ◽  
Low Levels

B-cells have received little attention in axial spondyloarthritis (axSpA) and for this reason their role in pathogenesis remains unclear. However, there are indications that B-cells may be involved in the disease process. Our objective was to obtain insights into the composition of the peripheral B-cell compartment of axSpA patients compared to healthy donors (HD) and patients with primary Sjögren’s syndrome (pSS), a typical B-cell-associated autoimmune disease. Special emphasis was given to CD27-negative B-cells expressing low levels of CD21 (CD21low B-cells), since this subset is implicated in autoimmune diseases with strong involvement of B-cells. Transitional B-cells (CD38hi) were excluded from the analysis of the CD27-CD21low B-cell compartment. This study included 45 axSpA patients, 20 pSS patients and 30 HDs. Intriguingly, compared to HDs the frequency of CD27-CD38lowCD21low B-cells was significantly elevated in both axSpA and pSS patients (P<0.0001 for both comparisons). The frequency of CD27-CD38lowCD21low B-cells expressing the activation-induced immune markers T-bet and CD11c was decreased in axSpA patients compared to HDs. A higher proportion of CD27-CD38lowCD21low B-cells expressed the chemokine receptor CXCR3 in axSpA compared to HDs, suggestive for active involvement of these cells in an inflammatory process. The frequency of CD27-CD38lowCD21low B-cells in axSpA patients correlated positively with age and erythrocyte sedimentation rate. Furthermore, axSpA patients with extra-skeletal manifestations (ESM) showed increased frequencies of CD27-CD38lowCD21low B-cells compared to patients without ESM. In conclusion, our findings are suggestive of active B-cell involvement in the pathogenesis of axSpA, against prevailing dogma.

scholarly journals Immature and Transitional B Cells Are Latency Reservoirs for a Gammaherpesvirus

2010 ◽  
Vol 84 (24) ◽  
pp. 13045-13052 ◽  
Author(s):  
Carrie B. Coleman ◽  
Michael S. Nealy ◽  
Scott A. Tibbetts
Keyword(s):  
B Cells ◽  
B Cell ◽  
Human Herpesvirus ◽  
Nuclear Antigen ◽  
Cell Compartment ◽  
Memory B Cell ◽  
Murine Gammaherpesvirus ◽  
Transitional B Cells ◽  
Immature B Cells ◽  
Gammaherpesvirus 68

ABSTRACT Gammaherpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV; also known as human herpesvirus 8 [HHV-8]), Epstein-Barr virus (EBV), and murine gammaherpesvirus 68 (MHV68; also known as gammaherpesvirus 68 [γHV68] or murine herpesvirus 4 [MuHV-4]), establish lifelong latency in the resting memory B cell compartment. However, little is known about how this reservoir of infected mature B cells is maintained for the life of the host. In the context of a normal immune system, the mature B cell pool is naturally maintained by the renewable populations of developing B cells that arise from hematopoiesis. Thus, recurrent infection of these developing B cell populations could allow the virus continual access to the B cell lineage and, subsequent to differentiation, the memory B cell compartment. To begin to address this hypothesis, we examined whether MHV68 establishes latency in developing B cells during a normal course of infection. In work described here, we demonstrate the presence of viral genome in bone marrow pro-pre-B cells and immature B cells during early latency and immature B cells during long-term latency. Further, we show that transitional B cells in the spleen are latently infected and express the latency-associated nuclear antigen (LANA) throughout chronic infection. Because developing B cells normally exhibit a short life span and a high rate of turnover, these findings suggest a model in which gammaherpesviruses may gain access to the mature B cell compartment by recurrent seeding of developing B cells.

scholarly journals A checkpoint for autoreactivity in human IgM+ memory B cell development

2006 ◽  
Vol 203 (2) ◽  
pp. 393-400 ◽  
Author(s):  
Makoto Tsuiji ◽  
Sergey Yurasov ◽  
Klara Velinzon ◽  
Saskia Thomas ◽  
Michel C. Nussenzweig ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Somatic Hypermutation ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Selection ◽  
Cell Compartment ◽  
Memory B Cell ◽  
Healthy Humans ◽  
Low Levels

Autoantibodies are removed from the repertoire at two checkpoints during B cell development in the bone marrow and the periphery. Despite these checkpoints, up to 20% of the antibodies expressed by mature naive B cells in healthy humans show low levels of self-reactivity. To determine whether self-reactive antibodies are also part of the antigen-experienced memory B cell compartment, we analyzed recombinant antibodies cloned from single circulating human IgM+ memory B cells. Cells expressing antibodies specific for individual bacterial polysaccharides were expanded in the IgM+ memory compartment. In contrast, B cells expressing self-reactive and broadly bacterially reactive antibodies were removed from the repertoire in the transition from naive to IgM+ memory B cell. Selection against self-reactive antibodies was implemented before the onset of somatic hypermutation. We conclude that a third checkpoint selects against self-reactivity during IgM+ memory B cell development in humans.

scholarly journals Notch2-mediated plasticity between marginal zone and follicular B cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Markus Lechner ◽  
Thomas Engleitner ◽  
Tea Babushku ◽  
Marc Schmidt-Supprian ◽  
Roland Rad ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Marginal Zone ◽  
Close Contact ◽  
Immunological Function ◽  
Transitional B Cells ◽  
Bona Fide ◽  
Fate Decision ◽  
Follicular B Cells ◽  
Cell Follicle

AbstractFollicular B (FoB) and marginal zone B (MZB) cells are functionally and spatially distinct mature B cell populations in the spleen, originating from a Notch2-dependent fate decision after splenic influx of immature transitional B cells. In the B cell follicle, a Notch2-signal is provided by DLL-1-expressing fibroblasts. However, it is unclear whether FoB cells, which are in close contact with these DLL-1 expressing fibroblasts, can also differentiate to MZB cells if they receive a Notch2-signal. Here, we show induced Notch2IC-expression in FoB cells re-programs mature FoB cells into bona fide MZB cells as is evident from the surface phenotype, localization, immunological function and transcriptome of these cells. Furthermore, the lineage conversion from FoB to MZB cells occurs in immunocompetent wildtype mice. These findings demonstrate plasticity between mature FoB and MZB cells that can be driven by a singular signaling event, the activation of Notch2.

scholarly journals OP0186 CHANGES IN CIRCULATING B CELL LEVELS AND IMMUNOPHENOTYPE ARE ASSOCIATED WITH DEVELOPMENT OF ARTHRITIS FOLLOWING TREATMENT WITH CHECKPOINT INHIBITORS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 112.2-113
Author(s):  
M. Gatto ◽  
S. Bjursten ◽  
C. Jonell ◽  
C. Jonsson ◽  
S. Mcgrath ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Adverse Events ◽  
B Cell ◽  
Mononuclear Cells ◽  
Checkpoint Inhibitors ◽  
Therapy Monitoring ◽  
Cell Subset ◽  
Peripheral Blood Mononuclear ◽  
Transitional B Cells

Background:Inflammatory arthritis (IA) is frequent among rheumatic side effects induced by checkpoint inhibitor (CPI) therapy for metastatic malignancies1. While T cells are likely to sustain the inflammatory process2, fewer data are available concerning the role of B cells3.Objectives:To investigate the phenotype of circulating B cells in patients who develop CPI-induced IA (CPI-IA) and to compare it with features of B cells in patients not developing immune-related adverse events (irAE) upon CPI treatment.Methods:B cell subsets at baseline (before CPI initiation) and during CPI treatment were analyzed in CPI-IA patients and in patients receiving CPI but who did not develop irAE (non-irAE). Peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometry and B cells were identified as CD19+ and divided into naïve (CD27-IgD+), memory (CD27+IgD+/-), double negative (CD27-IgD-) and transitional (CD10+CD24+CD38+/hi) B cells. Levels of CD21, an activation marker on transitional B cells, were also analyzed. Non-parametric tests were used for analysis of differences between groups.Results:Six CPI-IA and 7 non-irAE patients matched for age, gender and CPI treatment were included, who had received CPI treatment due to metastatic melanoma. Flow cytometry revealed a significant increase of circulating B cells (p=0.002) (Figure 1A) and especially of transitional B cells in CPI-IA patients vs. non-irAE (median %, range: 7.8 (4.5-11.4) vs. 3.2 (1.6-4.3),p=0.007) (Figure 1B), while no remarkable changes were seen across other subsets. Transitional B cell levels significantly decreased from active to quiescent CPI-IA in all patients (p=0.008). In two CPI-IA patients for whom baseline sampling was available, the increase of transitional levels occurred early after CPI treatment and before CPI-IA onset. Levels of expression of CD21 on transitional B cells were increased in CPI-IA vs. non-irAE (p=0.01).Conclusion:Transitional B cells are expanded in CPI-IA patients and seem to increase early after start of CPI therapy. Monitoring this B cell subset might lead to closer follow-up and earlier diagnosis of CPI-IA.References:[1]Ramos-Casals M, Brahmer JR, Callahan MK, et al. Immune-related adverse events of checkpoint inhibitors. Nat Rev Dis Primers 2020;6:38[2]Murray-Brown W, Wilsdon TD, Weedon H, et al. Nivolumab-induced synovitis is characterized by florid T cell infiltration and rapid resolution with synovial biopsy-guided therapy. J Immunother Cancer 2020;8:e000281[3]Das R, Bar N, Ferreira M, et al. Early B cell changes predict autoimmunity following combination immune checkpoint blockade. J Clin Invest. 2018;128:715-2Disclosure of Interests:None declared

scholarly journals AB0025 B-CELL SUBSETS AS ADDITIONAL DIAGNOSTIC TOOL FOR PRIMARY SJOGREN’S SYNDROME AND SYSTEMIC LUPUS ERYTHEMATOSUS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1315.1-1316
Author(s):  
S. Benevolenskaya ◽  
I. Kudryavtsev ◽  
M. Serebriakova ◽  
I. Grigor’eva ◽  
A. Budkova ◽  
...  
Keyword(s):  
B Cells ◽  
Discriminant Analysis ◽  
B Cell ◽  
Sjögren’S Syndrome ◽  
Sjögren's Syndrome ◽  
Sjogren’S Syndrome ◽  
Sjogren's Syndrome ◽  
Transitional B Cells ◽  
B Cell Subsets ◽  
Sjögren‘S Syndrome

Background:Systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS) are chronic complex disorders with an autoimmune background, multifactorial etiology, multiple circulating antinuclear antibodies and damage of various organs. SLE and pSS have several similar clinical and serological aspects; likewise, SLE and Sjögren’s syndrome may coexist (so-called secondary Sjögren’s syndrome). However, applied classification criteria do not differentiate SLE and pSS. It is known that humoral immunity plays significant part in pathogenesis of those diseases; hereby, we can expect imbalances in B cell subset frequencies during SLE and pSS.Objectives:To investigate clinical utility of B cell subsets in distinguish SLE and pSS during diagnosis.Methods:A total of 25 SLE patients, 25 SS patients and 49 healthy volunteers (HV) were included in the study. The diagnosis of SLE was performed according to the 2019 EULAR – ACR classification criteria, the diagnosis of pSS - according to the 2016 EULAR – ACR criteria. Phenotyping of blood B cell subsets was done using flow cytometry. Total peripheral blood B cells were identified using CD19 expression, distinct B cell subsets were characterized by IgD, CD38 and CD27 expression. All of the statistical analysis of data was performed with STATISTICA Version 12.0 Inc. (USA).Results:We evaluated the percentages of circulating B-cell subsets using three major classification schemes based on the relative co-expression of either IgD/CD38 (so-called “Bm1-Bm5” classification), IgD/CD27 and CD38/CD27. A discriminant analysis was performed for all B cell classifications. Analysis of CD38 and CD27 co-expression demonstrated most significant separation between patients with SLE and pSS (fig. 1). Moreover, discriminant analysis carried out by using a forward stepwise model demonstrated that the top significance was documented while assessing the percentage of plasmoblasts (CD27hiCD38hi), resting memory B-cells (CD27dimCD38low), mature active B-cells (CD27dimCD38dim), naive mature B-cells (CD27dimCD38low), as well as counting the absolute numbers of transitional B-cells (CD27lowCD38hi), model percent correct was 78,6% (p <0,05, tab.1).Figure 1.Graphic distribution of SLE and pSS patients as well as HV analyzed by discriminant analysis.Conclusion:B cell subsets might provide a useful diagnostic tool for distinction SLE and pSS. More research needed to investigate clinical value of B-cell subsets in autoimmune rheumatic diseases.Table 1.Peripheral B-cell subset composition in SLE and SS patients vs. HV group assessed by discriminant analysis.ParameterF-testp-levelPlasmoblasts (CD27hiCD38hi), %7,93<0.001Resting memory B-cells (CD27dimCD38low), %13,72<0.001Transitional B-cells (CD27lowCD38hi)29,74<0.001Mature active B-cells (CD27dimCD38dim), %5,20<0.001Naive mature B-cells (CD27dimCD38low), %3,100.049Double negative (CD27lowCD38low), %1,980,14Resting memory B-cells (CD27dimCD38low)1,020,36Double negative (CD27lowCD38low)2,320,10Plasmoblasts (CD27hiCD38hi)1,020,36Naive mature B-cells (CD27dimCD38low)1,030,36Mature active B-cells (CD27dimCD38dim)1,020,36Transitional B-cells (CD27lowCD38hi), %1,030,36Disclosure of Interests:None declared

AB0144 STRATIFICATION OF PATIENTS WITH PRIMARY SJÖGREN’S SYNDROME BY MEASURING B-CELL HEALTH

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1372-1373
Author(s):  
G. M. Verstappen ◽  
J. C. Tempany ◽  
H. Cheon ◽  
A. Farchione ◽  
S. Downie-Doyle ◽  
...  
Keyword(s):  
Cell Division ◽  
Cell Differentiation ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
B Cell Differentiation ◽  
Research Support ◽  
Differentiation Capacity ◽  
Cell Responses ◽  
Healthy Donors

Background:Primary Sjögren’s syndrome (pSS) is a heterogeneous immune disorder with broad clinical phenotypes that can arise from a large number of genetic, hormonal, and environmental causes. B-cell hyperactivity is considered to be a pathogenic hallmark of pSS. However, whether B-cell hyperactivity in pSS patients is a result of polygenic, B cell-intrinsic factors, extrinsic factors, or both, is unclear. Despite controversies about the efficacy of rituximab, new B-cell targeting therapies are under investigation with promising early results. However, for such therapies to be successful, the etiology of B-cell hyperactivity in pSS needs to be clarified at the individual patient level.Objectives:To measure naïve B-cell function in pSS patients and healthy donors using quantitative immunology.Methods:We have developed standardised, quantitative functional assays of B-cell responses that measure division, death, differentiation and isotype switching, to reveal the innate programming of B cells in response to T-independent and dependent stimuli. This novel pipeline to measure B-cell health was developed to reveal the sum total of polygenic defects and underlying B-cell dysfunction at an individual level. For the current study, 25 pSS patients, fulfilling 2016 ACR-EULAR criteria, and 15 age-and gender-matched healthy donors were recruited. Standardized quantitative assays were used to directly measure B cell division, death and differentiation in response to T cell-independent (anti-Ig + CpG) and T-cell dependent (CD40L + IL-21) stimuli. Naïve B cells (IgD+CD27-) were sorted from peripheral blood mononuclear cells and were labeled with Cell Trace Violet at day 0 to track cell division until day 6. B cell differentiation was measured at day 5.Results:Application of our standardized assays, and accompanying parametric models, allowed us to study B cell-intrinsic defects in pSS patients to a range of stimuli. Strikingly, we demonstrated a hyperresponse of naïve B cells to combined B cell receptor (BCR) and Toll-like receptor (TLR)-9 stimulation in pSS patients. This hyperresponse was revealed by an increased mean division number (MDN) at day 5 in pSS patients compared with healthy donors (p=0.021). A higher MDN in pSS patients was observed at the cohort level and was likely attributed to an increased division burst (division destiny) time. The MDN upon BCR/TLR-9 stimulation correlated with serum IgG levels (rs=0.52; p=0.011). No difference in MDN of naïve B cells after T cell-dependent stimulation was observed between pSS patients and healthy donors. B cell differentiation capacity (e.g., plasmablast formation and isotype switching) after T cell-dependent stimulation was also assessed. At the cohort level, no difference in differentiation capacity between groups was observed, although some pSS patients showed higher plasmablast frequencies than healthy donors.Conclusion:Here, we demonstrate defects in B-cell responses both at the cohort level, as well as individual signatures of defective responses. Personalized profiles of B cell health in pSS patients reveal a group of hyperresponsive patients, specifically to combined BCR/TLR stimulation. These patients may benefit most from B-cell targeted therapies. Future studies will address whether profiles of B cell health might serve additional roles, such as prediction of disease trajectories, and thus accelerate early intervention and access to precision therapies.Disclosure of Interests:Gwenny M. Verstappen: None declared, Jessica Catherine Tempany: None declared, HoChan Cheon: None declared, Anthony Farchione: None declared, Sarah Downie-Doyle: None declared, Maureen Rischmueller Consultant of: Abbvie, Bristol-Meyer-Squibb, Celgene, Glaxo Smith Kline, Hospira, Janssen Cilag, MSD, Novartis, Pfizer, Roche, Sanofi, UCB, Ken R. Duffy: None declared, Frans G.M. Kroese Grant/research support from: Unrestricted grant from Bristol-Myers Squibb, Consultant of: Consultant for Bristol-Myers Squibb, Speakers bureau: Speaker for Bristol-Myers Squibb, Roche and Janssen-Cilag, Hendrika Bootsma Grant/research support from: Unrestricted grants from Bristol-Myers Squibb and Roche, Consultant of: Consultant for Bristol-Myers Squibb, Roche, Novartis, Medimmune, Union Chimique Belge, Speakers bureau: Speaker for Bristol-Myers Squibb and Novartis., Philip D. Hodgkin Grant/research support from: Medimmune, Vanessa L. Bryant Grant/research support from: CSL

scholarly journals Antibody Cloning Identifies Pathogenic and Non-Pathogenic Antibodies in Heparin-Induced Thrombocytopenia and Defines the Molecular Signatures That Differentiate the Two Types of Antibodies

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 439-439
Author(s):  
Wen Zhu ◽  
Yongwei Zheng ◽  
Mei Yu ◽  
Yaling Wu ◽  
Jianhui Wei ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Platelet Activation ◽  
Solid Phase ◽  
Variable Regions ◽  
Heparin Induced Thrombocytopenia ◽  
Tyrosine Residues ◽  
Healthy Donors ◽  
Activation Assay ◽  
Positively Charged

Heparin-induced thrombocytopenia (HIT) is a common adverse drug reaction associated with frequent life-threatening thrombotic complications. The hallmark of HIT is polyclonal antibodies (Abs) that recognize platelet alpha granule chemokine PF4 when it binds to heparin (PF4/H). These Abs can be detected in solid phase assays that use PF4/H as a target (PF4 ELISA), but only a minority of patients testing positive actually have HIT, i.e., most heparin-induced Abs are non-pathogenic. In patients who have clinical HIT, Abs that activate platelets can be detected using a platelet-activation assay such as the serotonin release assay, or the PF4-dependent p-selectin expression assay (PEA) (Chest 2016; 150:506). Thus, there are at least two distinct types of heparin-induced Abs - those that react only in PF4 ELISA and are seemingly "non-platelet-activating" and "non-pathogenic" and those that are "platelet-activating" and "pathogenic". To date, the molecular basis for the differing clinical and serologic behaviors of pathogenic and non-pathogenic Abs is uncertain. To address this issue, we performed single cell cloning to clone B cell receptors from IgG1+ B cells from HIT patients. We deposited single B cells (CD19+IgG1+) from 6 patients with "classical" and 2 patients with "spontaneous" HIT into 96 well plates containing feeder cells (from G Kelsoe, Duke U) that support B cell proliferation and Ab secretion (Immunity 2018;48:174). Clones secreting IgG were first screened in PF4 ELISA and positive results were obtained with 55 clones from 6 patients. Further screening showed that 7 of these clones (from 4 patients) were also PEA-positive (platelet-activating). Clones positive only in PF4 ELISA, positive in both PF4 ELISA and PEA, or negative in PF4 ELISA were designated NP (non-pathogenic), PA (platelet-activating) and NB (non-binding), respectively. H and L chain variable regions were defined in 7 PA, 42 NP and 34 NB clones. The following findings were made when sequences in the 3 clonal groups were compared: PA clones preferentially used JH6 (p=0.002) and the VH3/JH6 combination (p=0.0003)The PA and NP Abs all employed κ chains, whereas κ chain usage for NB clones was 61% (p&lt;0.0001).No preferred signatures were identified in κ chain complementarity determining regions (LCDR3) of PA clones that differentiate them from NP and NB Abs.PA Abs had longer heavy chain CDR3s (HCDR3) than NP (p&lt;0.001) or NB (p=0.0001) AbsPA Abs contained more positively charged amino acid residues compared to NP (p=0.058) or NB (p=0.002) Abs.PA Abs contained more tyrosine residues compared to NP (p=0.067) or NB (p&lt;0.0001) AbsFive of 7 PA clones contained an RX1-2K/RX1-2R/H (RKH) motif in HCDR3; the remaining 2 PA clones contained a string of at least 5 tyrosines (Y5 motif) in HCDR3. The RKH and Y5 motifs were not found in any of the 76 NP and NB clones. Substitution of alanine for positively charged residues of the RKH motif or of tyrosine residues in the Y5 motif in PA clones reduced PF4/H binding and platelet activation, arguing for functional significance of both motifs. Utilization of nearly identical H and L chains within 3 groups of clones and of shared H chains within 3 groups of clones (both PA and NP) was observed in multiple patients. Moreover, utilization of a shared H chain was observed within 3 NP clones from two unrelated patients. These findings indicate clonal amplification and convergence of the B cell (both PA and NP) response, likely in response to a common antigen. High throughput sequencing of IgG H chains were performed on peripheral blood mononuclear cells (PBMC) from 7 HIT patients and 3 healthy donors. Eleven of 1585 H chain sequences (0.69%) from HIT patients contained the RKH and 18 (1.1%) contained the Y5 motif. In 3 healthy donors, 4 of 1418 H chain sequences (0.28%) contained RKH and none (0%) contained Y5. The findings reflect amplification of B cells with receptors containing RKH and Y5 motifs in HIT patients (p=0.1 for excess RKH and p&lt;0.0001 for Y5 in HIT). These observations provide the first characterization of Ig structural motifs that are favored for selection in the humoral immune response leading to HIT and suggest that the RKH and Y5 CDR3 motifs in particular may contribute importantly to Ab pathogenicity. Findings made are expected to facilitate further work to define features specific to "pathogenic" HIT Abs and, possibly, to identify genetic variants that predispose individuals to experience HIT. Disclosures Padmanabhan: Terumo BCT: Consultancy; Veralox Therapeutics: Membership on an entity's Board of Directors or advisory committees; Versiti Wisconsin: Patents & Royalties: Related to HIT patents; Retham Technologies: Equity Ownership; Janssen R&D: Consultancy.

scholarly journals Marginating transitional B cells modulate neutrophils in the lung during inflammation and pneumonia

2021 ◽  
Vol 218 (9) ◽  
Author(s):  
John Podstawka ◽  
Sarthak Sinha ◽  
Carlos H. Hiroki ◽  
Nicole Sarden ◽  
Elise Granton ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Regulatory Networks ◽  
Vascular Inflammation ◽  
Transitional B Cells ◽  
Pulmonary Capillaries ◽  
Life Threatening ◽  
B Cell Subsets

Pulmonary innate immunity is required for host defense; however, excessive neutrophil inflammation can cause life-threatening acute lung injury. B lymphocytes can be regulatory, yet little is known about peripheral transitional IgM+ B cells in terms of regulatory properties. Using single-cell RNA sequencing, we discovered eight IgM+ B cell subsets with unique gene regulatory networks in the lung circulation dominated by transitional type 1 B and type 2 B (T2B) cells. Lung intravital confocal microscopy revealed that T2B cells marginate in the pulmonary capillaries via CD49e and require CXCL13 and CXCR5. During lung inflammation, marginated T2B cells dampened excessive neutrophil vascular inflammation via the specialized proresolving molecule lipoxin A4 (LXA4). Exogenous CXCL13 dampened excessive neutrophilic inflammation by increasing marginated B cells, and LXA4 recapitulated neutrophil regulation in B cell–deficient mice during inflammation and fungal pneumonia. Thus, the lung microvasculature is enriched in multiple IgM+ B cell subsets with marginating capillary T2B cells that dampen neutrophil responses.

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