Mark Pezzano Ph.D.
Associate Professor Department of Biology
Deputy Director RCMI Center for the Study of the Cellular and Molecular Basis of Development
138th Street and Convent Ave
New York , NY 10031
- BS Biology 1985 William Paterson University
- Ph.D. Cell and Molecular Biology 1993 The City University of New York
The thymus represents the key organ where the development and selection of T cells occurs. This process is critical to the function of the adaptive immune response. The thymus is composed of a mixture of endoderm derived epithelial cells, mesenchyme derived fibroblasts and haematopoietic derived macrophages, and dendritic cells, which interact to provide a series of complex microenvironments responsible for regulating the attraction, migration, expansion, survival and differentiation of developing T cells. Most of these functions are mediated through the actions of as yet poorly defined subsets of thymic epithelial cells. Research in my lab is focused on defining the function of specific thymic epithelial subsets in thymocyte selection, as well as understanding the cross talk mechanisms, which regulate thymic organogenesis. TECs have recently been shown to express a wide range of tissue specific antigens (TSAs) that are critical to ensuring a self-tolerant mature T cell repertoire. Understanding the complex interactions that occur between developing thymocytes and TECs, as well as the crosstalk mechanisms that regulate TEC expansion and differentiation will be critical for intervention in autoimmune disease, thymic recovery after cancer therapy and in regulating immune function in the aging population. We will continue our productive collaboration with Jerry Guyden studying the function of thymic nurse cells in T cell development and selection (Martinez, M.*, Samms, M.*, Hendrix, T.*, Adeosun, O.*, Pezzano, M., and Guyden, J.C. (2007) The Organization of the Thymic Nurse Cell Multi-Cellular complex within the Thymus of HY-TCR Transgenic Mice Demonstrates Their Association with MHC Restriction Journal of Experimental Biology and Medicine 232 (6):780-8 (Feature Article for June). In addition we have two NIH funded research projects in the lab for which we are currently recruiting graduate students.
Crosstalk Control of Thymic Epithelial Development
The thymic epithelial cells (TECs) are responsible for regulating the development of immature thymocytes into functional self-tolerant mature T cells. A common endoderm derived TEC progenitor was recently shown to give rise to both cortical and medullary TEC subsets, however, the signaling pathways and cell-to-cell interactions that regulate this process are poorly defined. TEC development and organization is dependent on crosstalk signals received from developing thymocytes as they migrate through the epithelial network. The goal of this study will be to define both the nature and function of the SP thymocyte/TEC interactions that regulate development of the thymic medulla, the thymic microenvironment that is critically responsible for central tolerance. The medullary reconstitution induced by adoptive transfer of mature T cells into mice with blocks in T cell development, will be used to test the contribution of specific T cell/TEC interactions. We propose to: 1) use both fetal thymic organ cultures and medullary reconstitution assays in a newly developed Wnt signaling reporter mouse strain, to access the contribution of Wnt signaling in mTEC development and determine if soluble Wnt inhibitory molecules secreted by SP thymocytes inhibit the canonical Wnt signaling pathway in TECs, thereby providing a molecular switch that is necessary for mTEC development from precursor cells; 2) use MHC class I/ MHC class II double KO mice to determine if the expansion and differentiation of the thymic medulla is dependent on TCR/MHC interactions and identify the specific contributions of CD4 SP, CD8 SP and Tregs, in this process Fully understanding the signaling pathways and cellular interactions which contribute to TEC development and organization will be critical to designing rational therapeutic strategies to counteract age associated thymic involution and thymic architecture defects associated with autoimmunity. These strategies will also significantly impact the effectiveness of bone marrow transplantation for cancer treatment by counteracting the severe premature thymic degeneration associated with preparative cytoablative treatments including chemotherapy and radiation, as well as post transplant GVHD.
Characterization of Thymic Epithelial Progenitors and their Capacity to Reconstitute Thymic Function (collaborative project with Derek B. Sant' Angelo at memorial Sloan Kettering Cancer Center and funded through NCI as part of the CCNY/MSKCC Collaborative Cancer Center)
Hematopoietic stem cell transplantation (HSCT) can cure many forms of blood-derived cancers. Unfortunately, particularly in adult patients, HSCT is associated with a period of immune incompetence due to a loss of capacity to generate functional T cells. The structural and functional changes in thymic epithelial cells (TECs), induced by HSCT, directly impact the capacity of the thymus to facilitate T cell development. Clinical treatment strategies that enhance T cell reconstitution could significantly improve the survival of HSCT recipients through reduced incidence of fatal infectious complications and enhanced T-cell mediated tumor activity. The goal of this study will be to identify thymic epithelial stem cells/progenitors and test the capacity of grafting of these populations to speed the recovery of thymic function after HSCT.
Aim 1 of this project will be to purify and characterize thymic epithelial progenitor cells. Due to their slow turnover rate, stem cells in a variety of tissues have been identified by their capacity to retain labeled nucleotides, so called “label retaining cells” (LRCs). A novel transgenic model, which utilizes a histone2B-GFP fusion protein (H2B-GFP), under control of a tetracycline response element driven by a K5 promoter, was used by Elaine Fuch’s group at Rockefeller to identify epithelial stem cells in the hair follicle bulge . This model is unique because it allows sorting of viable stem cells, in the absence of defining cell surface markers. Since putative thymic epithelial progenitors also express K5, we have obtained this transgenic model and will apply the method to identify thymic epithelial stem/progenitor populations. Further separation of putative stem cell populations will be performed using previously characterized epithelial stem cell surface characteristics. Sorted subsets will be assayed for progenitor potential based on their capacity to reform a functional thymus after transfer under the kidney capsule of nude mice.
Aim 2 will assess the ex vivo growth potential of thymic epithelial progenitors and their subsequent capacity to enhance immune reconstitution following hematopoietic stem cell transplantation (HSCT). Optimal culture conditions for expansion and maintenance of sorted TEC progenitors will be assessed. Maintenance of a stem cell phenotype in expanded TEC progenitors will then be assayed by testing their capacity to reconstitute a full thymus after grafting under the nude mice kidney capsule. The capacity of similarly prepared stem cell populations to enhance thymic recovery and reconstitution of immune function in mice following HSCT will be tested using both intrathymic injection and kidney capsule grafting of synegeneic TEC stem cells, followed by quantitative and functional T cell analysis.
This work has resulted in 8 presentations and 5 published abstracts.
1. Webb, O.*, Kelly, F.*, Benitez, J.*, Li, J., Parker, M.*, Martinez, M.*, Samms, M.*, Blake, A.*, Pezzano, M. and Guyden, J.C. (2004) The Identification of Thymic Nurse Cells In Vivo and the Role of Cytoskeletal Proteins in Thymocyte Internalization Cellular Immunology 228(2):119-29.
2. Osada, M., Ito, E., Vazquez-Cintron, E*., Venkatesh, T., Friedel, R.H., and Pezzano, M. (2006) The Wnt Signaling Antagonist Kremen1 is Required for the Development of Thymic Architecture Clinical and Developmental Immunology 13 (2-4) 299-319.
3. Martinez, M.*, Samms, M.*, Hendrix, T.*, Adeosun, O.*, Pezzano, M., and Guyden, J.C. (2007) The Organization of the Thymic Nurse Cell Multi-Cellular complex within the Thymus of HY-TCR Transgenic Mice Demonstrates Their Association with MHC Restriction Journal of Experimental Biology and Medicine 232 (6):780-8 (Feature Article for June)
1. Mark Pezzano, Juncheng Li, Marcia Martinez*, Michael Samms*, and Masako Osada. Presentation of Peripheral Antigens to Developing Thymocytes by PECs. Oral Platform Presentation RCMI International Symposium on Health Disparities Baltimore Maryland Dec. 2004 A# G34.
2. Vasquez-Cintron, E.*, Osada, M, Ito, E.*, Venkatesh, T., Friedel, R.H. and Pezzano, M. Kremen-1 Knockout Mice Exhibit Altered Thymic Architecture Nov 3, 2005 ABRCMS Meeting Atlanta Georgia. (Outstanding Poster Award)
3. Pezzano, M. The Wnt Signaling Antagonist Kremen1 is required for Development of Thymic Architecture-Oral Presentation Memorial Sloan Kettering-Sloan Kettering Institute Immunology Seminar Series, Feb. 27th 2006
4. Pezzano, M. The Wnt Signaling Antagonist Kremen1 is required for Development of Thymic Architecture-Oral Presentation Biology Department and MARC program University of Texas El Paso, March 10th 2006.
5. Vasquez, E.*, Osada, M, Ito, E.*, Venkatesh, T., Friedel, R.H. and Pezzano, M. Kremen-1 Knockout Mice Exhibit Altered Thymic Architecture. Collegiate Science and Technology Entry Program (CSTEP) 14th Annual Journeys Beyond Excellence Statewide Student Conference. The Sagamore on Lake George, NY, April 21-23. (Second Place in the Outstanding Poster Awards)
6. Osada, M, Ito, E., Vasquez, E.*, Venkatesh, T., Friedel, R.H. and Pezzano, M. Kremen-1 Knockout Mice Exhibit Altered Thymic Architecture AAI Meeting May 12-16, 2006 Boston MA (Abstract J. Immunol. C67 p.2).
7. Osada, M, Ito, E., Vasquez, E.*, Venkatesh, T., Friedel, R.H. and Pezzano, M. Kremen-1 Knockout Mice Exhibit Altered Thymic Architecture (Platform Presentation) RCMI International Symposium on Health Disparities San Juan PR Dec.15 2006.
8. The Microenvironment Niche Provided by Thymic Nurse Cells Facilitates the Attraction of Thymocytes and Macrophages. Oluwaseun, O Adeosun*, Jerry Guyden, Tonya Hendrix*, Marcia Martinez*, Michael Samms* and Mark Pezzano ABRCMS 2006 06-A-1451 (Outstanding Poster Award).
9. Characterization of Kremen-1 Functional Domains. Logan Jardine*, Masako Osada and Mark Pezzano. CCAAP Poster Presentation CCNY Nov. 2006
10. Use of Medullary Reconstitution to Analyze mTEC Development. Osada, M., Fermin, H.* Sant’Angelo, D.B. and Pezzano, M. (2007) THYMUS- Workshop on T cell Development 2007 Rolduc Netherlands May 19-22 ) (BD-Outstanding Poster Award) Abstract P81.
11. Crosstalk control of thymic epithelial development. M. Pezzano, M. Osada, H. Fermin and D.B. Sant’Angelo (2007) Guest Lecture Immunology and Microbial Pathogenesis Program-Scientific Retreat. Mohonk Mountain House Conference Center, New Paltz, New York.
12. The Use of Medullary Reconstitution to Analyze mTEC Development Agnes Sisa, Masako Osada, Hector Fermin, Derek B. Sant’Angelo and Mark Pezzano Einsteins in the City II International Student Research Conference Oct 30-31st 2007.
13. Characterization of Kremen 1 Function. Logan Jardin, Masako Osada, Hector Fermin, and Mark Pezzano Einsteins in the City II International Student Research Conference Oct 30-31st 2007.
14. Use of Medullary Reconstitution to Analyze mTEC Development Masako Osada1, Agnes Sisa, Hector Fermin1, Derek. B. Sant’Angelo2 and Mark Pezzano1 International Symposium on Health Disparities Honolulu Hawaii Dec 1-4 2008.
15. DKK1 Mediated Inhibition of Wnt Signaling in Postnatal Mice Leads to Loss of TEC Progenitors and Thymic Degeneration Masako Osada, Logan Jardine, Ruth Misir, Thomas Andl, Sarah E. Millar and Mark Pezzano AAI meeting Oral Platform Presentation May 7th-11th Baltimore Maryland 2010 A# 36.32.
16. Characterization of Thymic Epithelial Stem Cells and their Capacity to Reconstitute Thymic Function Masako Osada, Logan Jardine, Ruth Misir, Derek B. Sant’ Angelo and Mark Pezzano MSKCC/CCNY Cancer Research Symposium Cancer Heath Disparities: A Translational Approach April 23 2010.