Liang, Jie, Hsin-I Huang, Fernanda P. Benzatti, Amelia B. Karlsson, Junyi J. Zhang, Nourhan Youssef, Averil Ma, Laura P. Hale, and Gianna E. Hammer. “Inflammatory Th1 and Th17 in the Intestine Are Each Driven by Functionally Specialized Dendritic Cells with Distinct Requirements for MyD88..” Cell Rep 17, no. 5 (October 25, 2016): 1330–43. https://doi.org/10.1016/j.celrep.2016.09.091.
Gianna Hammer, PhD
The study of microbial communities that reside on and within the human body (the microbiome) is considered one of the hottest areas of science today. It is now well appreciated that the microbiome has remarkable influence on diverse aspects of human health and disease. To understand how the microbiome exerts such influence, our lab seeks to define the mechanisms by which cells of the immune system interact with microbes that reside in the intestine. To the immune system, co-existence with microbes is a remarkable paradox: while immune cells are skilled operatives fixated on eliminating microbial invaders, these same cells are somehow restrained from attacking microbial commensals. This restraint is critical to prevent inflammatory bowel disease (IBD).
Our research seeks to understand the pathogenesis of inflammatory bowel disease, and understand interactions between host and the microbiome. In particular, we study the roles of dendritic cells. Dendritic cells are exquisitely sensitive to microbes, and after engaging microbes or microbial products, dendritic cells are reprogrammed into inflammatory cells with potent ability to activate other immune cells. Because of their potent influence over the immune system, dendritic cells are in a prime position to relay signals from the microbiome, and we have found that dendritic cells are key players in pathogenesis of inflammatory bowel disease. To prevent IBD, dendritic cells require the NF-kB suppressor, A20. A20 suppresses multiple disease-associated signaling pathways, including TNF, NOD2 and Toll-like receptors. Using biochemistry and in vivo analyses, we are interrogating the roles of these receptors and signaling pathways in regulating the responses of dendritic cells to the intestinal microbiome. Additionally, we seek to identify new signaling pathways by which DCs interact with microbial communities of the intestine.
Education and Training
- Ph.D., University of California at Berkeley, 2006
Selected Grants and Awards
- Role of IRGM proteins in immunity to enteric bacteria
- Role of osteopontin in innate immunity during infections and inflammation
- Effects of storage method on intestinal allograft immune profile and viability
- SALMONELLA HIJACKING OF STAT3 AND CONSEQUENCES FOR DISEASE
- Identification of anti-commensal T cells, their pathological function, and their commensal antigen specificities in inflammatory bowel disease using a novel in vivo reporter system
- Organization and Function of Cellular Structure
- Organization and Function of Cellular Structure
- Role of Dendritic Cell-mediated T Cell Activation in Salt-sensitive Hypertension
- Dendritic cells in colorectal cancer
- IL-27 in skin host defense and regeneration
- Basic Immunology Training Program
- Microbiota induced upregulation of PDL1 on intestinal dendritic cells in intestinal tumorig
- The role of dendritic cell-mediated T cell activation in hypertension
- Dendritic cell orchestration of colitogenic T cells in inflammatory bowel disease
Hammer, Gianna, Jie Liang, Hsin-I Huang, Fernanda Benzatti, Amelia Karlsson, and Laura P. Hale. “Microbiota upregulate distinct APC functions in each intestinal dendritic cell subset, in a Myd88-independent fashion.” In Journal of Immunology, Vol. 196. AMER ASSOC IMMUNOLOGISTS, 2016.
Callahan, Joseph A., Gianna E. Hammer, Alexander Agelides, Bao H. Duong, Shigeru Oshima, Jeffrey North, Rommel Advincula, et al. “Cutting edge: ABIN-1 protects against psoriasis by restricting MyD88 signals in dendritic cells..” J Immunol 191, no. 2 (July 15, 2013): 535–39. https://doi.org/10.4049/jimmunol.1203335.
Lu, Timothy T., Michio Onizawa, Gianna E. Hammer, Emre E. Turer, Qian Yin, Ermelinda Damko, Alexander Agelidis, et al. “Dimerization and ubiquitin mediated recruitment of A20, a complex deubiquitinating enzyme..” Immunity 38, no. 5 (May 23, 2013): 896–905. https://doi.org/10.1016/j.immuni.2013.03.008.
Hammer, Gianna Elena, and Averil Ma. “Molecular control of steady-state dendritic cell maturation and immune homeostasis..” Annu Rev Immunol 31 (2013): 743–91. https://doi.org/10.1146/annurev-immunol-020711-074929.
Hammer, Gianna Elena, Emre E. Turer, Kimberly E. Taylor, Celia J. Fang, Rommel Advincula, Shigeru Oshima, Julio Barrera, et al. “Expression of A20 by dendritic cells preserves immune homeostasis and prevents colitis and spondyloarthritis..” Nat Immunol 12, no. 12 (October 23, 2011): 1184–93. https://doi.org/10.1038/ni.2135.
Kanaseki, Takayuki, Nicolas Blanchard, Gianna Elena Hammer, Federico Gonzalez, and Nilabh Shastri. “ERAAP synergizes with MHC class I molecules to make the final cut in the antigenic peptide precursors in the endoplasmic reticulum..” Immunity 25, no. 5 (November 2006): 795–806. https://doi.org/10.1016/j.immuni.2006.09.012.
Kanaseki, Takayuki, Nicolas Blanchard, Gianna Elena Hammer, Federico Gonzalez, and Nilabh Shastri. “ERAAP and MHC class I molecules collaborate to generate the exact length of antigenic peptides in the endoplasmic reticulum.” In Journal of Immunology, 176:S54–S54. AMER ASSOC IMMUNOLOGISTS, 2006.
Hammer, Gianna Elena, Federico Gonzalez, Marine Champsaur, Dragana Cado, and Nilabh Shastri. “The aminopeptidase ERAAP shapes the peptide repertoire displayed by major histocompatibility complex class I molecules..” Nat Immunol 7, no. 1 (January 2006): 103–12. https://doi.org/10.1038/ni1286.
McMahon, Christopher W., Allan J. Zajac, Amanda M. Jamieson, Laura Corral, Gianna E. Hammer, Rafi Ahmed, and David H. Raulet. “Viral and bacterial infections induce expression of multiple NK cell receptors in responding CD8(+) T cells..” J Immunol 169, no. 3 (August 1, 2002): 1444–52. https://doi.org/10.4049/jimmunol.169.3.1444.