Associate Professor of Immunobiology
Scientific Director, Molecular Histology and Fluorescence Imaging Core Facility
Scientific Director, EMTrix (UM Electron Microscopy Core Facility)
BIOB 410 - Immunology
BIOB 411 - Immunology Lab
BIOM 502 - Advanced Immunology
BIOB 596 - Principles of Light Microscopy
B.A. University of La Verne, La Verne, CA., 1987
M.S. California State Polytechnic University, Pomona, 1992
Ph.D. Oregon Health & Science University, Portland, OR, 2001
Work in my lab focuses on the activation and subset differentiation of CD4+ T lymphocytes.
- The biological consequences for individual T cells after the capture of APC membrane fragments from T-APC immunological synapse, a process termed “trogocytosis”;
- The impact of the herbicide Atrazine on the activation of CD4+ T cells and the mechanism underlying a significant increase in Foxp3+ regulatory T cells
CD4+ T lymphocytes recognize antigenic peptide fragments presented on the surface of antigen presenting cells (APC) by major histocompatiblility complex (MHC) class II proteins. Triggering of the T cell antigen receptor (TCR) by binding to the MHC:peptide ligand induces dramatic morphological changes as the T cell flattens against the APC and increases contact area forming stable T-APC conjugates. This initial antigen recognition is followed by large-scale spatial and temporal molecular rearrangements of plasma membrane proteins and intracellular signaling molecules. These rearrangements lead to the formation of an ordered structure at the T-APC interface termed the immunological synapse. The synapse is involved in T cell signaling as well as the site for delivery of T cell effector functions. We have previously shown that molecules from the APC are transferred to the T cell across the immune synapse in a process called trogocytosis.
We are examining the biological significance of intercellular transfer of molecules from APC to T cells (termed trogocytosis). We have previously shown that upon dissociation from APC, T cells capture MHC:peptide molecules from the immunological synapse and imaging data suggests that these molecules continue to signal to the T cell. Our work suggests that these trogocytosed molecules sustain intracellular signaling leading to selective survival of the trogocytosis positive cells, in vitro. More recent work has shown that this trogocytosis-mediated signaling contributes to the control of the immune response by sustaining effector cytokine production and the skewing of CD4+ T cells to a TH2 and/or TFH phenotype.
Immunotoxicology of Atrazine
We are examining the impact on Atrazine on the activation and differentiation of CD4+ T cells. Atrazine is a very widely applied herbicide that the USGS estimates contaminates 70% of the ground water in the US. It has been linked to birth defects, cancer, immune developmental defects and modulation of immune cell effector functions. We have shown that Atrazine inhibits CD4+ T lymphocyte proliferation and effector function. In addition, we have shown that the frequency of Foxp3 positive regulatory T cells (Treg) doubles in atrazine-treated cultures. This is largely due to elevated levels of cAMP, as Atrazine is a potent phosphidiesterase inhibitor. We have recently found that male and female T cells repsond differently to atrazine exposure. Atrazine's other biochemical effect is to induce expression of aromatase, which converts androgens to estrogen. We are now examining the impact of Atrazine-induced elevated estrogen on the induction of Tregs and Atrazine-associated inhibion of T cell activation.
Field of Study
Thueson, L.E; Emmons, .E., Browning, D.B., Kreitinger, J.M.; Sheherd, D.M.; Wetzel S.A. (2015). In vitro Exposure To The Herbicide Atrazine Inhibits T Cell Activation, Proliferation, and Cytokine Production and Significantly Increases The Frequency Of Foxp3+ Regulatory T Cells. Toxicological Sciences. 143:418-29. PMID: 25433234
Osborne, D.G. and Wetzel, S.A. (2012) Trogocytosis leads to sustained signaling in CD4+ T cells. The Journal of Immunology, 189(10):4728-39. PMID: 23066151
Doherty, M., Osborne, D.G., Browning, D.B., Parker, D.C. Wetzel, S.A. (2010) Anergic CD4+ T cells form mature immunological synapses with enhanced accumulation of c-Cbl and Cbl-b. The Journal of Immunology, 184:3598-3608. PMCID: PMC2843782
Thauland, T.J.; Y. Koguchi, R.Varma, S.A. Wetzel, M.L. Dustin, and D.C. Parker. (2008). TH1 and TH2 cells fom morphologically distinct immunological synapses . The Journal of Immunology, 181:393-9
Blake, D.J.; Wetzel, S.A.; Jean C Pfau, J.C. (2008) Autoantibodies from mice exposed to Libby amphibole asbestos bind SSA/Ro52-enriched apoptotic blebs of murine macrophages. Toxicology, 246:172-9
Scott A. Wetzel and D.C. Parker. (2006) MHC transfer from APC to T cells following antigen recognition. Critical Reviews in Immunology. 26:1-21
Tara J. Dillon, K.D.Carey, S.A. Wetzel, D.C. Parker, P.J.S. Stork. (2005). Regulation of the Small GTPase Rap1 and Extracellular Signal-Regulated Kinases by the Costimulatory Molecule CTLA-4. Molecular Cell Biology, 25(10):4117-4128
Scott A. Wetzel, T. W. McKeithan, D.C. Parker. (2005). Peptide-specific intercellular transfer of MHC class II to CD4+ T cells directly from the immunological synapse upon cellular dissociation. The Journal of Immunology. 174(1): 80-9
Tara J. Dillon, Vladimir Karpitski, Scott A. Wetzel, David C. Parker, Andrey S. Shaw, and Philip J. S. Stork (2003). Ectopic B-Raf expression enhances extracellular signal-regulated kinase (ERK) Signaling in T cells and prevents antigen presenting cell-induced anergy. Journal of Biological Chemistry, 278:35940.
Wetzel, S.A. ; McKeithan, T.W.; Parker D.C. (2002) Live Cell Dynamics and the Role of Costimulation in Immunological Synapse Formation. The Journal of Immunology. 169(11):6092
Sperry P.J.; Cua D.J.; Wetzel S.A.; Adler-Moore, J.A. (1998) Antimicrobial activity of AmBisome and non-liposomal Amphotericin B following uptake of Candida glabrata by murine epidermal Langerhans cells. Medical Mycology 36(3):135 - 141
Primus, F.J.; Finch, M.D.; Wetzel, S.A.; Masci, A.M.; Schlom, J.; Kashmiri, S.V.S. (1994) Monoclonal Antibody Gene Transfer: Implications for Tumor - Specific Cell - Mediated Cytotoxicity. Annals of the New York Academy of Science. 716:154 - 166
1996 - 2004 Instructor, Medical School Immunology, Oregon Health & Science University, Portland, OR
1997 - 2004 Instructor, Clinical Laboratory Science Program, Oregon Health & Science University, Portland, OR
2002 – 2004 Instructor, Biotechnology Department, Portland Community College, Portland, OR
2002 – 2011 Faculty Member, International Course on 3D Microscopy of Living Cells, University of British Columbia, Vancouver, BC, Canada
2005 - 2013 Assistant Professor, Division of Biological Sciences and Center for Environmental Health Sciences, University of Montana, Missoula, MT
2013 - Present Associate Professor, Division of Biological Sciences and Center for Environmental Health Sciences, University of Montana, Missoula, MT
American Association of Immunologists
University of Montana Center for Environmental Health Sciences
UM Interdepartmental Immunology Graduate Degree Track
UM DBS Cellular, Molecular, Microbial Biology Graduate Program
UM Molecular Bioscience Gratuate Program