Overview
The overall goals of our laboratory are to understand why the immune system causes autoimmune diseases and to devise methods to predict and treat them. We develop and use mouse strains that provide models for human diseases such as lupus, rheumatoid arthritis, and epidermolysis bullosa. We use a combination of genetics, molecular biological and cellular immunological tools to dissect the molecular and cellular processes that cause these diseases. Finally, we study the mechanisms that affect the persistence of antibodies and antibody-based therapeutics. The information gained from all of these approaches is then used to devise possible therapeutic approaches with a keen eye on those that can be translated to humans.
Scientific report
Autoimmune disease and antibody therapeutics
Mechanisms of systemic lupus erythematosus (SLE) and related autoimmune disorder
SLE is a poorly understood, highly variable autoimmune disorder in which B lymphocytes play a key role. They produce autoantibodies that attack multiple tissues, including the joints, skin, lungs, blood vessels, heart, liver, nervous system and kidneys. Its current treatments remain primitive, typically involving high dose corticosteroids and other immunosuppressive agents that are encumbered with significant side effects. More efficacious therapies that specifically target key mediators of SLE hinge on the basic research needed to better understand this disease.
There is increasing appreciation of the importance of Toll-like receptors (TLRs) in the immunological defense against infection. Unfortunately, these same TLRs can also function aberrantly to promote autoimmune diseases. In particular, the Toll-like receptor 7 is proving to be important for initiating SLE-like autoimmune diseases. An important goal of our laboratory is to understand the mechanism by which TLR7 causes autoimmunity. We are studying a mouse model that that spontaneously develops an SLE-like autoimmune disorder because of a mutation that results in excess expression of TLR7. We are using a number of approaches to investigate how excessive TLR7 signaling causes B lymphocytes to become autoreactive and to ultimately produce the pathogenic autoantibodies that result in SLE.
In a related line of investigation, we and our collaborators discovered that a certain cytokine, Interleukin 21 (IL-21), was considerably elevated our mouse model for SLE, the BXSB-Yaa mouse. This recently discovered cytokine is a strong potentiator of many types of immunological cell types, including B cells, but its role in SLE-like autoimmune disease was not known. Through the analysis of BXSB-Yaa mice genetically engineered to lack the IL-21 receptor, we showed that IL-21 signaling was absolutely required for the severe SLE disease that BXSB-Yaa mice normally develop. This result provides very strong support for the importance of IL-21 in SLE. Our subsequent experiments are dedicated towards characterizing the cellular mechanisms by which IL-21 promotes SLE and potentially other related forms of autoimmune disease.
Our final line of investigation is directed toward the development of "vaccines" that can counteract SLE. Through the introduction of engineered mutations that inactivate CD8 T cells and natural killer cells, we have found that CD8 T cells and natural killer cells normally prevent BXSB-Yaa mice from developing an even more severe form of autoimmune disease. We are seeking to characterize these regulatory cells and the mechanisms by which they counteract SLE. Our longer term goal is to develop ways to develop immunization strategies that augment the activity of these regulatory cells as a method of therapy.
Development of improved biological therapeuticsThe biology and pathobiology of FcRn (a.k.a. Fcgrt), a distant member of the major histocompatibility complex (MHC) class I protein family, is particularly interesting. While most class I members present peptide antigens to cytotoxic T cells, FcRn has acquired a distinct function. Rather than binding peptides and presenting them on the plasma membrane to T cells, FcRn binds antibodies of the IgG class, but only at a pH less than ~6.5. This pH is found in the intestinal lumen, and intracellularly in endosomes. FcRn was originally shown to be responsible for transport of IgG across the rodent gut, but more recent evidence suggests that FcRn is expressed in many tissues. In addition to maternal IgG transport, FcRn plays a critical role in IgG homeostasis by protecting IgG from normal protein catabolism, which results in a substantial increase in the half-life of IgG. Recent collaborative studies have shown that FcRn binds not only IgG, but also albumin, which is the dominant serum protein. In doing so, FcRn plays a critical role in both IgG and albumin homeostasis. A focus of our laboratory is to understand the biology of FcRn. Antibody-based therapeutics are emerging as a major treatment for a wide range of disorders, including autoimmune disease and cancer. One avenue of investigation is to improve the efficacy of antibody-based therapeutics by exploiting the interaction between antibodies and FcRn to extend (or shorten) the pharmokinetics of the antibodies. We have developed mouse models that are particularly valuable in evaluating the pharmacokinetics of therapeutic antibodies. These studies have shown that it is possible to substantially increase the lifespan of therapeutic antibodies by enhancing their interaction with FcRn. Finally, there are many gaps in our understanding of the cell biology of FcRn, which, if resolved, will aid in exploiting its medical potential. We are therefore seeking to identify the cell types in which FcRn normally functions in vivo.
The genetic basis of epidermolysis bullosa
Epidermolysis bullosa is a single-gene Mendelian human disorder characterized by a weakened dermal/epidermal junction. Any form of mechanical trauma leads to blister formation, inflammation and scar formation. We identified a spontaneous mutation that is a remarkable mimic of the human disorder. We have shown that the mutation is in the laminin 2 gene, recapitulating the genetic defects found in certain affected humans. With our institutional collaborator, John Sundberg, DVM, Ph.D., we are characterizing this disease model and determining whether the severity of the disease can be modified by genes distinct from laminin 2. Prior to our study, there were no viable mouse models for this devastating disease. Our ongoing characterization of this model opens the road to develop therapies to treat epidermolysis bullosa.
Lab staff
Principal Investigator: Derry Roopenian, Ph.D.
Postdoctoral Fellows: Jason Bubier, Ph.D.
Graduate Students: Caroline McPhee, D.V.M.
Senior Professional Assistants: Gregory Christianson, B.S., Thomas Sproule, B.A.
Senior Laboratory Assistant: Shari Roopenian
RAF Primary Room Technician: Bruce Carpenter
Research Administrative Assistant: Ashley Stanton
Publication listings
2006 to present
2009
2008
Shin DM , Shaffer DJ, Roopenian DC, Morse HC 3rd. 2008. Identification of Notch as a component of the transcriptional networks regulating cell growth and survival in mouse plasmacytomas. Cancer Res. 68(22):9202-11.
Qiao SW, Kobayashi K, Johansen FE, Sollid LM, Andersen JT, Milford E, Roopenian DC, Lencer WI, Blumberg RS. 2008. Dependence of antibody-mediated presentation of antigen on FcRn. Proc Natl Acad Sci 105(27):9337-9342.
Petkova SB, Yuan R, Tsaih SW, Schott W, Roopenian DC, Paigen B. 2008. Genetic influence on immune phenotype revealed strain-specific variations in peripheral blood lineages. Physiol Genomics. 34(3):304-314.
Serreze DV, Choisy-Rossi CM, Grier AE, Holl TM, Chapman HD, Gahagan JR, Osborne MA, Zhang W, King BL, Brown A, Roopenian D, Marron MP. 2008. Through regulation of TCR expression levels, an Idd7 region gene(s) interactively contributes to the impaired thymic deletion of autoreactive diabetogenic CD8+ T cells in nonobese diabetic mice. J Immunol. 180(5):3250-3259.
Akilesh S, Huber TB, Wu H, Wang G, Hartleben B, Kopp JB, Miner JH, Roopenian DC, Unanue ER, Shaw AS. 2008. Podocytes use FcRn to clear IgG from the glomerular basement membrane. Proc Natl Acad Sci 105(3):967-972.
2007
Bubier JA, Bennet SM, Sproule TJ, Lyon BL, Olland S, Young DA, Roopenian DC. 2007. Treatment of BXSB-Yaa mice with Il21-Fc fusion protein minimally attenuates SLE disease. NY Acad Sci Sept;1110:590-601.
Akilesh S, Christianson GJ, Roopenian DC, Shaw AS. 2007. Neonatal FcR expression in bone marrow-derived cells functions to protect serum IgG from catabolism. J Immunol 179(7):4580-4588.
Roopenian DC, Akilesh S. 2007. FcRn: The neonatal Fc receptor comes of age. Nat Rev Immunol 7(9):715-725.
Liu X, Ye, L, Christianson GJ,Yang JQ, Roopenian DC, Zhu X. 2007. NF-kappaB signaling regulates functional expression of the MHC class I-related neonatal Fc receptor for IgG via intronic binding sequences. J Immuno 179(5):2999-3011.
Woo Y, Wright SM, Maas SA, Alley TL, Caddle LB, Kamdar S, Affourtit J, Foreman O, Akeson EC, Shaffer D, Bronson RT, Morse HC 3rd, Roopenian D, Mills KD. 2007. The nonhomologous end joining factor Artemis suppresses multi-tissue tumor formation and prevents loss of heterozygosity. Oncogene 26(41):6010-6020.
Shatry AM, Roopenian DC, Levy RB. Survival and Function of MiHA Epitope-Specific Host CD8 TM Cells Following Ablative Conditioning and HCT. Biol Blood Marrow Transplant 13:293-298.
Seymour RE, Hasham MG, Cox GA, Shultz LD, Hogenesch H, Roopenian DC, Sundberg JP. 2007. Spontaneous mutations in the mouse Sharpin gene result in multiorgan inflammation, immune system dysregulation and dermatitis. Genes Immun 8(5):416-21.
Ostrov DA, Barnes CL, Smith LE, Binns S, Brusko TM, Brown AC, Quint PS, Litherland SA, Roopenian DC, Iczkowski KA. 2007. Characterization of HKE2: an ancient antigen encoded in the major histocompatibility complex. Tissue Antigens 69:181-188.
Qi CF, Zhou JX, Lee CH, Naghashfar Z, Xiang S, Chattopadhyay SK, Fredrickson TN, Hartley JW, Roopenian DC, Davidson WF, Janz S, Morse HC 3rd. 2007. Anaplastic, plasmablastic and plasmacytic plasmacytomas of mice: relationships to human plasma cell neoplasms and late stage differentiation of normal B cells. Cancer Research 67, 2439-2447.
2006
Brown AC, Lerner CP, Graber JH, Shaffer DJ, Roopenian, DC. 2006. Pooling and PCR As a Method to Combat Low Frequency Gene Targeting in ES Cells. Cytotechnology 51:81-88.
Petkova SB, Akilesh S, Sproule TJ, Christianson GJ, Al Khabbaz H, Brown AC, Presta LG, Meng YG, Roopenian DC. 2006. Enhanced half-life of genetically engineered human IgG1 antibodies in a humanized FcRn mouse model: potential application in humorally mediated autoimmune disease. Int Immunol 2006 18:1759-1769.
Yoshida M, Kobayashi K, Kuo TT, Bry L, Glickman JN, Claypool SM, Kaser A, Nagaishi T, Higgins DE, Mizoguchi E, Wakatsuki Y, Roopenian DC, Mizoguchi A, Lencer WI, Blumberg RS. 2006. Neonatal Fc receptor for IgG regulates mucosal immune responses to luminal bacteria.
J Clin Invest 116(8):2142-2151.
Liu XY, Pop LM, Roopenian DC, Ghetie V, Vitetta ES, Smallshaw JE. 2006. Generation and characterization of a novel tetravalent anti-CD22 antibody with improved antitumor activity and pharmacokinetics. Int Immunopharmacol 6(5):791-799.
Yan J, Parekh VV, Mendez-Fernandez Y, Olivares-Villagómez D, Dragovic SM, Hill T, Roopenian DC, Joyce S, Van Kaer L. 2006. In vivo role of ER-associated peptidase activity in tailoring peptides for presentation by MHC class Ia and class Ib molecules. J Exp Med. 203(3):647-659.
Crowley, H, Alroy, J, Sproule, TJ, Roopenian, D, and Huber, BT. 2006. The MHC class I-related FcRn ameliorates murine Lyme arthritis. Int. Immunol. 18: 409-414.
Petkova SB; Konstantinov KN; Sproule TJ; Lyons BL; Awwami MA; Roopenian DC. 2006. Human antibodies induce arthritis in mice deficient in the low-affinity inhibitory IgG receptor FcgRIIB. J Exp Med 203(2):275-280.
Kim J, Bronson CL, Hayton WL, Radmacher MD, Roopenian DC, Robinson JM, Anderson CL. 2006. Albumin turnover: FcRn-mediated recycling saves as much albumin from degradation as the liver produces. Am J Physiol Gastrointest Liver Physiol 290: G352-60.
older publications
