Wilson Lab : Christopher Wilson | Members | Research Interests | Reagent Requests| Protocols  

Wilson Lab: Research Interests

The laboratory is engaged in work addressing the development of the cellular immune system and of host defenses to infection.

Theme: Epigenetic regulation of T cell fate and function

One major focus is the elucidation of molecular mechanisms by which functional differences between naïve and memory/effector T cells are imposed, thereby allowing them to exhibit fixed and heritable patterns of effector functions. Earlier work suggested that heritable programs of T cell function and cytokine expression, particularly the expression of interferon-γ, were imposed in part by epigenetic mechanisms. To address this question directly, his laboratory has created mice in which DNA methyltransferase l is ablated conditionally at different stages of T cell development. Ongoing studies support the notion that DNA methylation differentially modulates gene expression and thereby affects developmental fate and cytokine production in T-lineage cells.

Lab Members Involved: Heidi Harowicz, Maria Schnyreva, Mike Weaver

Figure - Lee Cover, Transcriptional Threshold

This cartoon illustrates the effects of conditional disruption of the DNA methltransferase I (Dnmt1) gene in T cells, which has selective and developmental stage-specific effects on gene expression in thymocytes and T cells. When Dnmt1 is disrupted at the early DN stage by crossing mice with loxP-flanked Dnmt1 to mice expressing Cre-recombinase under the control of the lck proximal promoter (lckCre), a large fraction of TCRγδ+ T cells aberrantly express both CD8α and CD8β on the cell surface; this parallels demethylation of the CD8α and CD8β loci. By contrast, the pattern of expression of CD8 on TCRαβ-lineage cells is unperturbed. When Dnmt1 is disrupted at the DN to DP transition by Cre-recombinase expressed under the control of the CD4 enhancer/promoter/silencer, T cell development in the thymus proceeds normally. However, the expression of effector cytokines by naïve T cells is markedly enhanced, as shown for interferon-γ, which parallels demethylation in the interferon-γ promoter.

Recent Related Publications:

• Lee PP, Fitzpatrick DR, Beard C, Jessup HK, Lehar S, Makar, KW, Perez-Melgosa, M, Sweetser, MT, Schlissel, MS, Nguyen S, Cherry SR, Tsai, JH, Tucker S, Weaver, WM, Kelso A, Jaenisch R, Wilson CB. A critical role for Dnmt1 and DNA methylation in T cell development, function and survival. Immunity 15:763-774, 2001.



• Wilson, C.B., Makar, K.W., Pérez-Melgosa, M. Epigenetic Regulation of T Cell Fate and Function. J Infect Dis, 185:S37-S45, 2002.
  
  
• Fitzpatrick, D.R., Wilson, C.B. Methylation and demethylation in the regulation of genes, cells and responses in the immune system. Clin. Immunol.109:37-45, 2003.
  
  
• Makar, K.W., Perez-Melgosa, M., Shnyreva, M., Weaver, W.M., Fitzpatrick, D. R., Wilson, C.B. Active recruitment of DNA methyltransferases regulates interleukin 4 in thymocytes and T cells. Nature Immunol. 4:1183-90, 2003.
  
  
  
  

Theme: Innate Immunity and Immunity to Infection

A second focus of work addresses mechanisms governing the development of immunity following infections due to bacterial pathogens, including Listeria monocytogenes, Mycobacterium tuberculosis and Pseudomonas aeruginosa, and the viral pathogen, herpes simplex. Studies seek to elucidate the mechanisms by which microbes evade recognition by the immune system, and conversely, mechanisms by which the innate immune system senses microbial invasion and alerts the adaptive immune system during the primary immune response. The former question is being addressed through the generation of mutant herpes simplex viruses and murine models of infection, and the latter question by exploring the specificity and mechanisms by which Toll-like receptors contribute to microbial recognition and activation of the innate immune system. Ongoing studies have helped to define structural and combinatorial mechanisms that determine the specificity of Toll-like receptor recognition.

Lab Members Involved: Lynn Hajjar, Heidi Harowicz, Tobias Kollmann, Mark Orr, Sing Sing Way

Figure - Recombinant HSV targeting strategy

The above cartoon illustrates the strategy used to create recombinant herpes simplex viruses in which the ICP47 gene is replaced by one of two genes - HCMV US11 or mCMV m152. The ICP47 gene blocks MHC class I expression in humans but not in mice, whereas the recombinant viruses block MHC class I expression in mice and in humans. The recombinant viruses are being used to test the importance of viral inhibition of MHC class I expression in evasion of the immune response.

Figure - The Hypervariable Domain is Necessary and Sufficient for Species-specific Discrimination of P. aeruginosa

Pseudomonas aeruginosa undergoes a molecular adaptation within the lungs of individuals with cystic fibrosis, which results in progressive, lifelong and ultimately fatal lung inflammation. The basis for this is uncertain. The above figure shows that the intense inflammation induced by this infection is mediated by a region of human Toll-like receptor 4 (TLR4), that specifically recognizes this molecular adaptation in the structure of the LPS molecule from cystic fibrosis strains of Pseudomonas aeruginosa. (The panels of the figure show 4 different chimeric TLR4 molecules in which h stands for a portion from the human TLR4 and m stands for a portion from murine TLR4. The green lines show results with E. coli LPS (positive control), the red is P. aeruginosa LPS from cystic fibrosis patients and the blue is P. aeruginosa LPS from laboratory strains. Phylogenetic analysis suggests that this region of TLR4 is under intense evolutionary pressure implying an important role in host-microbe interactions.

Recent Related Publications:

• Edelmann KH, Wilson CB. Role of CD28/CD80-86 and CD40/CD154 costimulatory interactions in host defense to primary herpes simplex virus infection, J Virol 75:612-621, 2001.
  
  
• Hajjar AM*, Ernst, RK*, Tsai, JH, Wilson CB†, Miller, SI†. Human Toll-like receptor 4 recognizes host-specific LPS modifications, Nature Immunol 3:354-359, 2002.
  
  *contributed equally, †share senior authorship;
  
  

• Skerrett, S.J., Liggitt, H.D., Hajjar, A.M., Wilson, C.B. Cutting Edge: Myeloid Differentiation Factor 88 is Essential for Pulmonary Host Defense Against Pseudomonas aeruginosa but not Staphylococcus aureus. J. Immunol. 172:3377-3381, 2004.
  

• Kollmann, T.R., Way, S.S., Harowicz, H., Hajjar, A.M., Wilson, C.B. Deficient MHC class I cross-presentation of soluble antigen by murine neonatal dendritic cells. Blood. 103:4240-4242, 2004.
  
  
  
  
  

  Updated 7-8-04