Regulation of Immunoglobulin Class Switch in Aged Mice

Summary

Principal Investigator: Bonnie B Blomberg
Abstract: Aged humans and experimental animals have a poor immune response to infectious agents and vaccines. The antibody-mediated humoral immune response is qualitatively deficient in aged individuals with the production of antibodies of lower affinity and with self reactivity. Although problems with T cells certainly contribute to these B cell deficits in aging, intrinsic B cell changes are shown in this proposal. The ability to switch immunoglobulin (Ig) heavy chain class (isotype) is critical for proper effector functions of the Ig protein and genetic defects in the ability of humans to undergo class switch recombination (CSR) result in immunodeficiency with increased susceptibility to many pathogens. These studies will focus on the molecular and cellular mechanisms responsible for the decrease in Ig class switch in aged mice. We hypothesize that the decrease in CSR is a direct result of a decrease in the activation-induced cytidine deaminase, AID, which in turn is regulated by a decrease in the transcription factor, E47, in aged mice. This proposal will compare splenic B cells from aged vs. young mice for the presence and function of E47, AID and class switched isotypes (IgG, IgE, IgA) in vitro as well as in antigen-specific responses in vivo. In Specific Aim 1 we will extend preliminary data to establish the intrinsic splenic B cell defect in Ig class switch in aged BALB/c, C57BL/6 and E2A+/- mice. Purified splenic B cells will be activated with mitogens or anti-CD40 and various cytokines and class switch measured by ELISA for secreted Ig, fluorescent cytometry for cell surface Ig molecularly by detection of germ line transcripts (GLT) and post-switch transcripts (PST). In vivo experiments with immunization with NP-KLH or NP-Ficoll (thymus-dependent and thymus-independent antigens) and adoptive transfer of combinations of young and old B/T cells into SCID mice will be done. In Specific Aim 2, the molecular mechanisms regulating class switch in young and old mice will be investigated. E47, Id2, Notch, NFicB and AID expression in aged B cells will be characterized. Experiments will include chromatin immunoprecipitation (ChIP) with anti-E2A (for the AID gene) as well as attempts to rescue class switch in aged B cells with retroviral transduction of AID or E47. hi Specific Aim 3, the molecular mechanisms for regulation of E47 and AID will be established. Studies of protein and mRNA stability, post translational regulation, and signal transduction pathways including MAPK, will determine key molecular elements in the control of Ig class switch in aged mice.
Funding Period: 2004-04-01 - 2015-01-31
more information: NIH RePORT

Top Publications

  1. pmc Aging murine B cells have decreased class switch induced by anti-CD40 or BAFF
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Exp Gerontol 42:192-203. 2007
  2. pmc AID activity in B cells strongly correlates with polyclonal antibody affinity maturation in-vivo following pandemic 2009-H1N1 vaccination in humans
    Surender Khurana
    Division of Viral Products, Center for Biologics Evaluation and Research CBER, Food and Drug Administration FDA, Bethesda, Maryland, USA
    PLoS Pathog 8:e1002920. 2012
  3. pmc A molecular mechanism for TNF-α-mediated downregulation of B cell responses
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami, Miami, FL 33101, USA
    J Immunol 188:279-86. 2012
  4. ncbi E47 retroviral rescue of intrinsic B-cell defects in senescent mice
    Ana M Landin
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Aging Cell 10:327-37. 2011
  5. pmc Intrinsic defects in B cell response to seasonal influenza vaccination in elderly humans
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Vaccine 28:8077-84. 2010
  6. pmc Age effects on B cells and humoral immunity in humans
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Ageing Res Rev 10:330-5. 2011
  7. pmc Protein phosphatase 2A (PP2A) is increased in old murine B cells and mediates p38 MAPK/tristetraprolin dephosphorylation and E47 mRNA instability
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, P O Box 016960 R 138, Miami, FL 33101, USA
    Mech Ageing Dev 131:306-14. 2010
  8. pmc Effects of aging on B cell function
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Curr Opin Immunol 21:425-30. 2009
  9. pmc Effects of fenbendazole on the murine humoral immune system
    Ana Marie Landin
    Department of Microbiology, University of Miami Miller School of Medicine, Miami, Florida, USA
    J Am Assoc Lab Anim Sci 48:251-7. 2009
  10. pmc Old mice retain bone marrow B1 progenitors, but lose B2 precursors, and exhibit altered immature B cell phenotype and light chain usage
    Sarah Alter-Wolf
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Mech Ageing Dev 130:401-8. 2009

Detail Information

Publications17

  1. pmc Aging murine B cells have decreased class switch induced by anti-CD40 or BAFF
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Exp Gerontol 42:192-203. 2007
    ..These differences in B cell responses to CD40/IL-4 and BAFF/IL-4 may help to explain the maintenance of TI vs TD responses in senescent mice...
  2. pmc AID activity in B cells strongly correlates with polyclonal antibody affinity maturation in-vivo following pandemic 2009-H1N1 vaccination in humans
    Surender Khurana
    Division of Viral Products, Center for Biologics Evaluation and Research CBER, Food and Drug Administration FDA, Bethesda, Maryland, USA
    PLoS Pathog 8:e1002920. 2012
    ..The ability to generate high affinity antibodies could have significant impact on the elucidation of age-specific antibody responses following vaccination and eventual clinical efficacy and disease outcome...
  3. pmc A molecular mechanism for TNF-α-mediated downregulation of B cell responses
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami, Miami, FL 33101, USA
    J Immunol 188:279-86. 2012
    ..Finally, anti-TNF-α given in vivo increased B cell function in old, but not in young, follicular B cells. These results suggest new molecular mechanisms that contribute to reduced Ab responses in aging...
  4. ncbi E47 retroviral rescue of intrinsic B-cell defects in senescent mice
    Ana M Landin
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Aging Cell 10:327-37. 2011
    ..Our results provide a proof of principle for the rescue of intrinsic B-cell defects and the humoral immune response in senescence...
  5. pmc Intrinsic defects in B cell response to seasonal influenza vaccination in elderly humans
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Vaccine 28:8077-84. 2010
    ..These results could contribute to developing more effective vaccines to protect the elderly as well as identifying those most at risk...
  6. pmc Age effects on B cells and humoral immunity in humans
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Ageing Res Rev 10:330-5. 2011
    ..We here present an overview of age-related changes in human B cell markers and functions, and also discuss some controversies in the field of B cell aging...
  7. pmc Protein phosphatase 2A (PP2A) is increased in old murine B cells and mediates p38 MAPK/tristetraprolin dephosphorylation and E47 mRNA instability
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, P O Box 016960 R 138, Miami, FL 33101, USA
    Mech Ageing Dev 131:306-14. 2010
    ..This mechanism may be at least in part responsible for the age-related decrease in class switch...
  8. pmc Effects of aging on B cell function
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Curr Opin Immunol 21:425-30. 2009
    ..The reported microarray analysis of human B cell subsets may now be used to delineate B cell defects with aging and all the advances presented should lead to selecting agents for improved immune response in the elderly...
  9. pmc Effects of fenbendazole on the murine humoral immune system
    Ana Marie Landin
    Department of Microbiology, University of Miami Miller School of Medicine, Miami, Florida, USA
    J Am Assoc Lab Anim Sci 48:251-7. 2009
    ..Our findings suggest that FBZ treatment may alter sensitive immune and molecular measures as presented here, and postponing the experimental use of mice until at least 6 wk after treatment should be considered...
  10. pmc Old mice retain bone marrow B1 progenitors, but lose B2 precursors, and exhibit altered immature B cell phenotype and light chain usage
    Sarah Alter-Wolf
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Mech Ageing Dev 130:401-8. 2009
    ..This is associated with decreased surrogate light chain expression, a characteristic held in common by B1 progenitors as well as B2 precursors in old mice...
  11. pmc NK cells in the CD19- B220+ bone marrow fraction are increased in senescence and reduce E2A and surrogate light chain proteins in B cell precursors
    Anne M King
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    Mech Ageing Dev 130:384-92. 2009
    ....
  12. ncbi Aging down-regulates the transcription factor E2A, activation-induced cytidine deaminase, and Ig class switch in human B cells
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami, Miller School of Medicine, Miami, FL 33101, USA
    J Immunol 180:5283-90. 2008
    ..Our results provide a possible molecular mechanism for a B cell intrinsic defect in the humoral immune response with aging and suggest avenues for improvement of vaccine response in elderly humans...
  13. ncbi Mechanisms for decreased function of B cells in aged mice and humans
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    J Immunol 180:2741-6. 2008
    ..These and current studies should lead to improvements in B lymphocyte function in aged populations...
  14. ncbi Tristetraprolin, a negative regulator of mRNA stability, is increased in old B cells and is involved in the degradation of E47 mRNA
    Daniela Frasca
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    J Immunol 179:918-27. 2007
    ..This is the first report showing that TTP is involved in the degradation of the E47 mRNA and is up-regulated in old B cells...
  15. ncbi Accelerated Notch-dependent degradation of E47 proteins in aged B cell precursors is associated with increased ERK MAPK activation
    Anne M King
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA
    J Immunol 178:3521-9. 2007
    ..The dysregulation of E2A-encoded protein expression may contribute to the reductions seen in early B lymphopoiesis during murine senescence...
  16. pmc In senescence, age-associated B cells secrete TNFα and inhibit survival of B-cell precursors
    Michelle Ratliff
    Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
    Aging Cell 12:303-11. 2013
    ..This provides a mechanism of inappropriate B-cell 'feedback' that promotes down-regulation of B lymphopoiesis in old age...