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Isotype class switching

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https://www.readbyqxmd.com/read/28137874/igd-class-switching-is-initiated-by-microbiota-and-limited-to-mucosa-associated-lymphoid-tissue-in-mice
#1
Jin Huk Choi, Kuan-Wen Wang, Duanwu Zhang, Xiaowei Zhan, Tao Wang, Chun-Hui Bu, Cassie L Behrendt, Ming Zeng, Ying Wang, Takuma Misawa, Xiaohong Li, Miao Tang, Xiaoming Zhan, Lindsay Scott, Sara Hildebrand, Anne R Murray, Eva Marie Y Moresco, Lora V Hooper, Bruce Beutler
Class-switch recombination (CSR) alters the Ig isotype to diversify antibody effector functions. IgD CSR is a rare event, and its regulation is poorly understood. We report that deficiency of 53BP1, a DNA damage-response protein, caused age-dependent overproduction of secreted IgD resulting from increased IgD CSR exclusively within B cells of mucosa-associated lymphoid tissues. IgD overproduction was dependent on activation-induced cytidine deaminase, hematopoietic MyD88 expression, and an intact microbiome, against which circulating IgD, but not IgM, was reactive...
January 30, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28125732/dysregulation-of-systemic-and-mucosal-humoral-responses-to-microbial-and-food-antigens-as-a-factor-contributing-to-microbial-translocation-and-chronic-inflammation-in-hiv-1-infection
#2
Zdenek Hel, Jun Xu, Warren L Denning, E Scott Helton, Richard P H Huijbregts, Sonya L Heath, E Turner Overton, Benjamin S Christmann, Charles O Elson, Paul A Goepfert, Jiri Mestecky
HIV-1 infection is associated with an early and profound depletion of mucosal memory CD4+ T cells, a population that plays an indispensable role in the regulation of isotype switching and transepithelial transport of antibodies. In this study, we addressed whether the depletion of CD4+ T cell in HIV-1-infected individuals results in altered humoral responses specific to antigens encountered at mucosal surfaces. Comprehensive protein microarray of systemic humoral responses to intestinal microbiota demonstrated reduced IgG responses to antigens derived from Proteobacteria and Firmicutes but not Bacteroidetes...
January 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28107431/characterization-of-a-broadly-reactive-anti-cd40-agonistic-monoclonal-antibody-for-potential-use-as-an-adjuvant
#3
Cameron Martin, Suryakant D Waghela, Shehnaz Lokhandwala, Andy Ambrus, Jocelyn Bray, Christina Vuong, Vanitha Vinodkumar, Paul J Dominowski, Sharath Rai, Duncan Mwangi, Dennis L Foss, Waithaka Mwangi
Lack of safe and effective adjuvants is a major hindrance to the development of efficacious vaccines. Signaling via CD40 pathway leads to enhanced antigen processing and presentation, nitric oxide expression, pro-inflammatory cytokine expression by antigen presenting cells, and stimulation of B-cells to undergo somatic hypermutation, immunoglobulin class switching, and proliferation. Agonistic anti-CD40 antibodies have shown promising adjuvant qualities in human and mouse vaccine studies. An anti-CD40 monoclonal antibody (mAb), designated 2E4E4, was identified and shown to have strong agonistic effects on primary cells from multiple livestock species...
2017: PloS One
https://www.readbyqxmd.com/read/28086979/b-cell-repertoires-in-hla-sensitized-kidney-transplant-candidates-undergoing-desensitization-therapy
#4
John F Beausang, H Christina Fan, Rene Sit, Maria U Hutchins, Kshama Jirage, Rachael Curtis, Edward Hutchins, Stephen R Quake, Julie M Yabu
BACKGROUND: Kidney transplantation is the most effective treatment for end-stage renal disease. Sensitization refers to pre-existing antibodies against human leukocyte antigen (HLA) protein and remains a major barrier to successful transplantation. Despite implementation of desensitization strategies, many candidates fail to respond. Our objective was to determine whether measuring B cell repertoires could differentiate candidates that respond to desensitization therapy. METHODS: We developed an assay based on high-throughput DNA sequencing of the variable domain of the heavy chain of immunoglobulin genes to measure changes in B cell repertoires in 19 highly HLA-sensitized kidney transplant candidates undergoing desensitization and 7 controls with low to moderate HLA sensitization levels...
January 13, 2017: Journal of Translational Medicine
https://www.readbyqxmd.com/read/28065739/r-loop-depletion-by-over-expressed-rnase-h1-in-mouse-b-cells-increases-activation-induced-deaminase-access-to-the-transcribed-strand-without-altering-frequency-of-isotype-switching
#5
Robert W Maul, Hyongi Chon, Kiran Sakhuja, Susana M Cerritelli, Lina A Gugliotti, Patricia J Gearhart, Robert J Crouch
R-loops, three-strand structures consisting of mRNA hybridized to the complementary DNA and a single-stranded DNA loop, are formed in switch regions on the heavy-chain immunoglobulin locus. To determine if R-loops have a direct effect on any of the steps involved in isotype switching, we generated a transgenic mouse that over-expressed RNase H1, an enzyme that cleaves the RNA of RNA/DNA hybrids in B cells. R-loops in the switch μ region were depleted by 70% in ex vivo activated splenic B cells. Frequencies of isotype switching to IgG1, IgG2b, IgG2c, and IgG3 were the same as C57BL/6 control cells...
January 6, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28053999/b-cell-populations-discriminate-between-pediatric-and-adult-onset-multiple-sclerosis
#6
Alexander Schwarz, Bettina Balint, Mirjam Korporal-Kuhnke, Sven Jarius, Kathrin von Engelhardt, Alexandra Fürwentsches, Cornelia Bussmann, Friedrich Ebinger, Brigitte Wildemann, Jürgen Haas
OBJECTIVE: To comparatively assess the B-cell composition in blood and CSF of patients with pediatric-onset multiple sclerosis (pedMS) and adult-onset multiple sclerosis (adMS). METHODS: In this cross-sectional study, we obtained blood and CSF samples from 25 patients with pedMS (8-18 years) and 40 patients with adMS (23-65 years) and blood specimens from 66 controls (1-55 years). By using multicolor flow cytometry, we identified naive, transitional, isotype class-switched memory, nonswitched memory, and double-negative memory B-cell subsets as well as plasmablasts (PB) and terminally differentiated plasma cells (PC)...
January 2017: Neurology® Neuroimmunology & Neuroinflammation
https://www.readbyqxmd.com/read/28011866/the-aryl-hydrocarbon-receptor-controls-cell-fate-decisions-in-b-cells
#7
Bharat Vaidyanathan, Ashutosh Chaudhry, William T Yewdell, Davide Angeletti, Wei-Feng Yen, Adam K Wheatley, Christopher A Bradfield, Adrian B McDermott, Jonathan W Yewdell, Alexander Y Rudensky, Jayanta Chaudhuri
Generation of cellular heterogeneity is an essential feature of the adaptive immune system. This is best exemplified during humoral immune response when an expanding B cell clone assumes multiple cell fates, including class-switched B cells, antibody-secreting plasma cells, and memory B cells. Although each cell type is essential for immunity, their generation must be exquisitely controlled because a class-switched B cell cannot revert back to the parent isotype, and a terminally differentiated plasma cell cannot contribute to the memory pool...
January 2017: Journal of Experimental Medicine
https://www.readbyqxmd.com/read/27974207/dna-replication-origins-in-immunoglobulin-switch-regions-regulate-class-switch-recombination-in-an-r-loop-dependent-manner
#8
Eva-Maria Wiedemann, Mihaela Peycheva, Rushad Pavri
Class switch recombination (CSR) at the immunoglobulin heavy chain (IgH) locus generates antibody isotypes. CSR depends on double-strand breaks (DSBs) induced by activation-induced cytidine deaminase (AID). Although DSB formation and repair machineries are active in G1 phase, efficient CSR is dependent on cell proliferation and S phase entry; however, the underlying mechanisms are obscure. Here, we show that efficient CSR requires the replicative helicase, the Mcm complex. Mcm proteins are enriched at IgH switch regions during CSR, leading to assembly of facultative replication origins that require Mcm helicase function for productive CSR...
December 13, 2016: Cell Reports
https://www.readbyqxmd.com/read/27897229/global-gene-regulation-during-activation-of-immunoglobulin-class-switching-in-human-b-cells
#9
Youming Zhang, David J Fear, Saffron A G Willis-Owen, William O Cookson, Miriam F Moffatt
Immunoglobulin class switch recombination (CSR) to IgE is a tightly regulated process central to atopic disease. To profile the B-cell transcriptional responses underlying the activation of the germinal centre activities leading to the generation of IgE, naïve human B-cells were stimulated with IL-4 and anti-CD40. Gene expression and alternative splicing were profiled over 12 days using the Affymetrix Human Exon 1.0 ST Array. A total of 1,399 genes, forming 13 temporal profiles were differentially expressed...
November 29, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27881702/roles-of-aluminum-hydroxide-and-monophosphoryl-lipid-a-adjuvants-in-overcoming-cd4-t-cell-deficiency-to-induce-isotype-switched-igg-antibody-responses-and-protection-by-t-dependent-influenza-vaccine
#10
Eun-Ju Ko, Young-Tae Lee, Ki-Hye Kim, Youri Lee, Yu-Jin Jung, Min-Chul Kim, Yu-Na Lee, Taeuk Kang, Sang-Moo Kang
Vaccine adjuvant effects in the CD4-deficient condition largely remain unknown. We investigated the roles of combined monophosphoryl lipid A (MPL) and aluminum hydroxide (Alum) adjuvant (MPL+Alum) in inducing immunity after immunization of CD4 knockout (CD4KO) and wild-type (WT) mice with T-dependent influenza vaccine. MPL+Alum adjuvant mediated IgG isotype-switched Abs, IgG-secreting cell responses, and protection in CD4KO mice, which were comparable to those in WT mice. In contrast, Alum adjuvant effects were dependent on CD4(+) T cells...
January 1, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/27833954/the-role-of-autoantibodies-in-health-and-disease
#11
Isabela Siloşi, Cristian Adrian Siloşi, Mihail Virgil Boldeanu, Manole Cojocaru, Viorel Biciuşcă, Carmen Silvia Avrămescu, Inimioara Mihaela Cojocaru, Maria Bogdan, Roxana Mihaela FolcuŢi
Serum of healthy individuals contains antibodies that react with self and non-self antigens, generated in absence of external antigen stimulation. These antibodies, called natural antibodies, are particularly IgM isotype, are considered natural autoantibodies (NAA), displaying a moderate affinity for self-antigens. Although incidence of NAA in healthy individuals is not reported, it is established that autoreactive antibodies and B-cells, as well as autoreactive T-cells, are present in healthy persons. The functional abilities of NAA are not clear but is well accepted that they may participate in a variety of activities, such as maintenance of immune homeostasis, regulation of the immune response, resistance to infections, transport and functional modulation of biologically active molecules...
2016: Romanian Journal of Morphology and Embryology, Revue Roumaine de Morphologie et Embryologie
https://www.readbyqxmd.com/read/27815447/efficient-culture-of-human-naive-and-memory-b-cells-for-use-as-apcs
#12
Kuei-Ying Su, Akiko Watanabe, Chen-Hao Yeh, Garnett Kelsoe, Masayuki Kuraoka
The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the capacity to support mature B cell proliferation. We developed a culture method to support the efficient activation and proliferation of naive and memory human B cells. This culture supports extensive B cell proliferation, with ∼10(3)-fold increases following 8 d in culture and 10(6)-fold increases when cultures are split and cultured for 8 more days...
November 15, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/27799928/evaluation-of-the-antigen-experienced-b-cell-receptor-repertoire-in-healthy-children-and-adults
#13
Hanna IJspeert, Pauline A van Schouwenburg, David van Zessen, Ingrid Pico-Knijnenburg, Gertjan J Driessen, Andrew P Stubbs, Mirjam van der Burg
Upon antigen recognition via their B cell receptor (BR), B cells migrate to the germinal center where they undergo somatic hypermutation (SHM) to increase their affinity for the antigen, and class switch recombination (CSR) to change the effector function of the secreted antibodies. These steps are essential to create an antigen-experienced BR repertoire that efficiently protects the body against pathogens. At the same time, the BR repertoire should be selected to protect against responses to self-antigen or harmless antigens...
2016: Frontiers in Immunology
https://www.readbyqxmd.com/read/27596815/angioimmunoblastic-t-cell-lymphoma-with-a-clonal-plasma-cell-proliferation-that-underwent-immunoglobulin-isotype-switch-in-the-skin-coinciding-with-cutaneous-disease-progression
#14
Ana E Suárez, M J Artiga, Carlos Santonja, Santiago Montes-Moreno, P De Pablo, Luis Requena, Miguel A Piris, Socorro M Rodríguez-Pinilla
Plasma cell proliferations in specific cutaneous lesions of angioimmunoblastic T-cell lymphoma(AITL) are very uncommon. Here, we report a case of clonal plasma cell proliferation in skin with heavy-chain-immunoglobulin-isotype-switch after cutaneous disease progression. Histopathologically, initial plaque lesions were suggestive of marginal-zone B-cell-lymphoma. Nevertheless, this 77-year-old lady was diagnosed with AITL after the progression of skin lesions from plaques to nodular tumors. A lymph node biopsy confirmed the diagnosis...
December 2016: Journal of Cutaneous Pathology
https://www.readbyqxmd.com/read/27501247/germinal-centre-hypoxia-and-regulation-of-antibody-qualities-by-a-hypoxia-response-system
#15
Sung Hoon Cho, Ariel L Raybuck, Kristy Stengel, Mei Wei, Thomas C Beck, Emmanuel Volanakis, James W Thomas, Scott Hiebert, Volker H Haase, Mark R Boothby
Germinal centres (GCs) promote humoral immunity and vaccine efficacy. In GCs, antigen-activated B cells proliferate, express high-affinity antibodies, promote antibody class switching, and yield B cell memory. Whereas the cytokine milieu has long been known to regulate effector functions that include the choice of immunoglobulin class, both cell-autonomous and extrinsic metabolic programming have emerged as modulators of T-cell-mediated immunity. Here we show in mice that GC light zones are hypoxic, and that low oxygen tension () alters B cell physiology and function...
September 8, 2016: Nature
https://www.readbyqxmd.com/read/27494228/binding-of-estrogen-receptors-to-switch-sites-and-regulatory-elements-in-the-immunoglobulin-heavy-chain-locus-of-activated-b-cells-suggests-a-direct-influence-of-estrogen-on-antibody-expression
#16
Bart G Jones, Rhiannon R Penkert, Beisi Xu, Yiping Fan, Geoff Neale, Patricia J Gearhart, Julia L Hurwitz
Females and males differ in antibody isotype expression patterns and in immune responses to foreign- and self-antigens. For example, systemic lupus erythematosus is a condition that associates with the production of isotype-skewed anti-self antibodies, and exhibits a 9:1 female:male disease ratio. To explain differences between B cell responses in males and females, we sought to identify direct interactions of the estrogen receptor (ER) with the immunoglobulin heavy chain locus. This effort was encouraged by our previous identification of estrogen response elements (ERE) in heavy chain switch (S) regions...
September 2016: Molecular Immunology
https://www.readbyqxmd.com/read/27444337/increased-expression-of-taci-on-nod-b-cells-results-in-germinal-centre-reaction-anomalies-enhanced-plasma-cell-differentiation-and-immunoglobulin-production
#17
Viqar S Banday, Radha Thyagarajan, Mia Sundström, Kristina Lejon
B cells have an important pathogenic role in the development of type 1 diabetes in the non-obese diabetic (NOD) mouse. We have previously reported that NOD mice display an increased percentage of TACI(high) -expressing B cells compared with C57BL/6 mice and this trait is linked to chromosomes 1 and 8. In this paper the genetic association of the transmembrane activator, calcium modulator and cyclophilin ligand interactor (TACI) trait was confirmed using double congenic NOD.B6C1/Idd22 mice. TACI ligation by a proliferation-inducing ligand (APRIL) has been shown to influence plasma cell differentiation, immunoglobulin production and isotype switch...
November 2016: Immunology
https://www.readbyqxmd.com/read/27320916/a-damage-independent-role-for-53bp1-that-impacts-break-order-and-igh-architecture-during-class-switch-recombination
#18
Pedro P Rocha, Ramya Raviram, Yi Fu, JungHyun Kim, Vincent M Luo, Arafat Aljoufi, Emily Swanzey, Alessandra Pasquarella, Alessia Balestrini, Emily R Miraldi, Richard Bonneau, John Petrini, Gunnar Schotta, Jane A Skok
During class switch recombination (CSR), B cells replace the Igh Cμ or δ exons with another downstream constant region exon (CH), altering the antibody isotype. CSR occurs through the introduction of AID-mediated double-strand breaks (DSBs) in switch regions and subsequent ligation of broken ends. Here, we developed an assay to investigate the dynamics of DSB formation in individual cells. We demonstrate that the upstream switch region Sμ is first targeted during recombination and that the mechanism underlying this control relies on 53BP1...
June 28, 2016: Cell Reports
https://www.readbyqxmd.com/read/27158669/chronic-lymphocytic-leukemia-cells-diversify-and-differentiate-in-vivo-via-a-nonclassical-th1-dependent-bcl-6-deficient-process
#19
Piers E M Patten, Gerardo Ferrer, Shih-Shih Chen, Rita Simone, Sonia Marsilio, Xiao-Jie Yan, Zachary Gitto, Chaohui Yuan, Jonathan E Kolitz, Jacqueline Barrientos, Steven L Allen, Kanti R Rai, Thomas MacCarthy, Charles C Chu, Nicholas Chiorazzi
Xenografting primary tumor cells allows modeling of the heterogeneous natures of malignant diseases and the influences of the tissue microenvironment. Here, we demonstrate that xenografting primary chronic lymphocytic leukemia (CLL) B lymphocytes with activated autologous T cells into alymphoid mice results in considerable CLL B cell division and sizable T cell expansion. Nevertheless, most/all CD5(+)CD19(+) cells are eventually lost, due in part to differentiation into antibody-secreting plasmablasts/plasma cells...
April 7, 2016: JCI Insight
https://www.readbyqxmd.com/read/27073891/regulation-of-iga-class-switch-recombination-in-immunoglobulin-a-nephropathy-retinoic-acid-signaling-and-batf
#20
Liyu He, Xiaofei Peng, Yinyin Chen, Guoyong Liu, Zhiwen Liu, Jiefu Zhu, Yexin Liu, Hong Liu, Yumei Liang, Fuyou Liu, Lin Sun, Youming Peng
BACKGROUND: Immunoglobulin (Ig) A nephropathy (IgAN) is the xFB01;nding of immune deposits predominantly containing polymeric IgA in the glomerular mesangium on renal biopsy. Increasing evidence suggested that retinoic acid (RA) signaling selectively induces IgA isotype switching and basic leucine zipper transcription factor, ATF-like (BATF) controls the global regulators of class switch recombination (CSR) in lymphocytes. Great effort has been paid to identify whether impaired immune regulation along the 'mucosa-bone marrow (BM) axis' play an important role in the pathogenesis of IgAN...
2016: American Journal of Nephrology
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