Amy Ku

Amy Ku

Department

Immunology, Roswell Park Comprehensive Cancer Center

Thesis

Thesis Title: Tumor-induced myeloid-derived suppressor cells negatively regulate CD8+ T lymphocyte trafficking

Email

Undergraduate Education

Biochemistry, UCLA

Thesis Advisor

The success of T cell-based immunotherapy and, unexpectedly, thermal therapy, standard chemotherapy and radiation hinges on cytotoxic T cells gaining access to tumor targets.  These observations have prompted interest in strategies to improve T cell trafficking to tumors although the mechanisms that positively or negatively regulate extravasation at tumor vascular checkpoints are poorly understood.  Here, we report that the ability of tumor vessels to respond to IL-6-dependent preconditioning regimens that boost CD8 effector T cell homing is temporally and inversely related to the expansion of myeloid-derived suppressor cells (MDSC) within the tumor microenvironment.  Using real-time intravital imaging and immunofluorescence histology, IL-6 therapies were shown to convert vessels from T cell-low to -high recruitment sites in murine tumors with minimal MDSC infiltration (i.e., CT26 colorectal, B16 melanoma, EMT6 mammary tumors). This conversion requires induction of the ICAM-1 trafficking molecule on tumor vessels. Conversely, mammary (4T1, AT-3 and PyMT-MMTV) and pancreatic (Pan02) tumors with higher MDSC burdens were refractory to IL-6 therapies, but became responsive after acute MDSC depletion.  To further investigate contributions of MDSC to poor trafficking, IL-6-responsive tumors were admixed with syngeneic CD11b+Gr-1+ MDSC isolated from spleens of tumor-bearing mice at a ratio of 2:1, thus mimicking the high MDSC burden detected in IL-6-refractive tumors.  Sustained elevation of MDSC in admixed tumors resulted in failure to support increased T cell trafficking in response to IL-6–dependent therapy. 

While suppressive effects of MDSC on effector T cell function within tumor tissues is a widely-studied topic, the impact of MDSC on naïve T cells within LN has been largely overlooked as MDSC are rare within these critical sites of immune priming.  Previous reports have shown that peripheral MDSC from tumor-bearing mice downregulate the LN homing receptor L-selectin on naive CD4+ and CD8+ T lymphocytes, but the molecular mechanisms and target cell-specificity has been unclear.  Furthermore, the biological relevance of moderate fluctuations of L-selectin is questionable as the high density of L-selectin molecules normally present on T cells could theoretically buffer against the effects of such loss during trafficking.  Using stringent murine mammary tumor models of high and moderate MDSC burden (4T1 and AT-3, respectively), we demonstrate that MDSC downregulate L-selectin on naive T and B cells post-transcriptionally via a contact-dependent mechanism.  MDSC-driven loss of L-selectin occurs within 24 hours both in vitro and in vivo, and does not appear to be species-restricted as L-selectin on human lymphocytes can also be targeted by MDSC.  By employing real-time intravital microscopy and immunofluorescence histology to visualize and assess naive CD8 T cell trafficking within vascular gateways for lymphocyte trafficking known as high endothelial venules (HEV),  we found that even moderate losses of L-selectin mediated by MDSC causes a profound reduction in the quality of lymphocyte-HEV interactions.  Ultimately, this results in significantly fewer T cells trafficking and infiltrating into the LN parenchyma.  In an in vivo vaccination model, MDSC-mediated loss of L-selectin on naive CD8 T cell and subsequent reduction in lymphocyte trafficking severely diminishes antigen-driven T cell expansion within draining LN.  These data reveal that MDSC localized outside of the LN can shape the magnitude of T cell responses within the intranodal compartment, which has unanticipated implications for systemic immunity in cancer.  Taken together, these findings identify a novel role of MDSC in subverting antitumor immunity by limiting T cell trafficking at both the LN and tumor vascular loci. 

Publications

  • Ku AW, Muhitch JB, Powers CA, Diehl M, Kim M, Fisher DT, Sharda AP, Clements VK, O’Loughlin K, Minderman H , Messmer MN, Ma J, Skitzki JJ, Steeber DA, Walcheck B, Ostrand-Rosenberg S, Abrams SI, and Evans SS.  Tumor-induced MDSC act via remote control to inhibit L-selectin-dependent adaptive immunity in lymph nodes. eLife, December 8, 2016; pii: e17375. doi: 10.7554/eLife.17375. PMC5199197.
  • Ito F, Ku A, Bucsek MJ, Muhitch JB, Vardam-Kaur T, Kim M, Fisher DT, Camoriano M, Khoury T, Skitzki JJ, Gollnick SO, Evans SS.  Immune adjuvant activity of pre-resectional radiofrequency ablation protects against local and systemic recurrence in aggressive murine colorectal cancer. PLoS ONE, November 23, 2015 DOI: 10.1371/journal.pone.0143370. PMC4657935
  • Mikucki ME, Fisher DT, Matsuzaki J, Skitzki JJ, Gaulin NB, Muhitch JB, Ku AW, Frelinger JG, Odunsi K, Gajewski TF, Luster AD, Evans SS. 2015. Non-redundant requirement for CXCR3 signaling during tumoricidal T cell trafficking across tumor vascular checkpoints. Nature Communications Jun 25;6:7458. doi: 10.1038/ncomms8458. PMC4605273
  • Mikucki ME, Fisher DT, Ku AW, Appenheimer MM, Muhitch JB, Evans SS. Preconditioning thermal therapy: Flipping the switch on IL-6 for anti-tumour immunity. Int J Hyperthermia 2013; 29(5):464-73.
  • Call GB, Olson JM, Chen J, Villarasa N, Ngo KT, Yabroff AM, et al. Genomewide clonal analysis of lethal mutations in the Drosophila melanogaster eye: comparison of the X chromosome and autosomes. Genetics 2007; 177(2):689-97. PMCID: PMC2034635
  • Morizono K, Ku A, Xie Y, Harui A, Kung SK, Roth MD, Lee B, Chen IS. Redirecting lentiviral vectors pseudotyped with Sindbis virus-derived envelope proteins to DC-SIGN by modification of N-linked glycans of envelope proteins. J Virol 2010; 84(14):6923-34. PMCID: PMC2898243

Professional/Educational Meetings/Abstracts

  • 2016 APSA NE Regional Meeting, Buffalo, NY, October 29th, 2016.  Tumor-induced Myeloid-derived Suppressor Cells Act via Remote Control to Inhibit L-selection-dependent Adaptive Immunity in Lymph Nodes.  Poster presentation. eBioscience/affymetric Trainee Travel Award. 
  • 19th Annual Upstate New York Immunology Conference, Bolton Landing, NY, October 25-27, 2016.  Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Podium and poster presentation.
  • Roswell Park Tumor Immunology Department and Program Winter Retreat, Holiday Valley, NY, January 21-22, 2016.  Myeloid-derived suppressor cells negatively impact trafficking of CD8+ effector T cells in the tumor microenvironment.  Poster presentation.
  • 1st Annual Immune Imaging Symposium, Rochester, NY.  November 7, 2015.  Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Platform talk and poster presentation.
  • 11th Annual APSA and ASCI/AAP Joint Meeting, Chicago, IL. April 24-26, 2015.  Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Poster presentation, APSA Travel Award.
  • 2014 Tri-Institutional M.D./Ph.D. Conference, Rochester, NY, October 11, 2014. Myeloid-derived suppressor cells negatively impact trafficking of CD8 effector T cells in the tumor microenvironment.  Platform talk.
  • Roswell Park Tumor Immunology Department and Program Summer Retreat, Canandaigua, NY, August 11-12, 2014.  Myeloid-derived suppressor cells negatively impact trafficking of CD8+ effector T cells in the tumor microenvironment.  Poster presentation.
  • 2014 Roswell Park Comprehensive Cancer Center Science Retreat, Geneseo, NY, July 17-18, 2014. Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Poster presentation.
  • Society of Thermal Medicine 31st Annual Meeting, Minneapolis, MN, May 6-10, 2014.  Myeloid-Derived Suppressor Cells Subvert the Immunostimulatory Activity of Systemic Thermal Therapy by Blocking T cell Trafficking in the Tumor Microenvironment. Platform talk and poster presentation, NIH/STM New Investigator Award.
  • AAI Immunology 2014, Pittsburgh, PA, May 2-6, 2014.  Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Poster presentation.
  • Thirteenth Annual Buffalo Conference on Immunology, Mayville, NY, March 13-April 1, 2014.  Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Poster presentation.
  • 2014 Translational Research Cancer Centers Consortium Annual Meeting, Seven Springs, PA, February 18-20, 2014.  Negative impact of myeloid-derived suppressor cells on CD8 effector T cell trafficking within the tumor microenvironment.  Platform talk and poster presentation, AAI Young Investigator Award.          
  • 16th Annual Upstate New York Immunology Conference, Bolton Landing, NY, October 20-23, 2013.  Myeloid-derived suppressor cells negatively impact trafficking of CD8 effector T cells in the tumor microenvironment.  Platform talk and poster presentation, AAI Young Investigator Award.
  • 2013 Tri-Institutional M.D./Ph.D. Research Day, Buffalo, NY, October 19, 2013.  Myeloid-derived suppressor cells negatively impact trafficking of CD8 effector T cells in the tumor microenvironment.  Poster presentation.
  • 2013 Roswell Park Comprehensive Cancer Center Science Retreat, Geneseo, NY, June 20-21, 2013. Impact of myeloid-derived suppressor cells on effector T cell trafficking into the tumor microenvironment.  Poster presentation.
  • Tumor Immunology Department and Program Winter Retreat, Holiday Valley Ellicottville, NY, January 17-18, 2013.  Myeloid-derived suppressor cells negatively impact trafficking of CD8+ effector T cells in the tumor microenvironment.  Poster presentation.

Awards/Honors

  • “NIH-sponsored APSA Travel Award.” 11th Annual APSA and ASCI/AAP Joint Meeting, Chicago, IL, April 24-26, 2015.
  • STM Young Investigators Award. Society for Thermal Medicine 31st Annual Meeting, Minneapolis, MN, May 6-10, 2014.         
  • George L. Mayers Award for Academic Excellence in Immunology. Thirteenth Annual Buffalo Conference on Immunology, Mayville, NY, March 31-April 1, 2014.          
  • AAI Young Investigators Award. Translational Research Cancer Centers Consortium Annual Meeting, Seven Springs, PA, February 18-20, 2014.           
  • AAI Young Investigators Award. 16th Annual Upstate New York Immunology Conference, Bolton Landing, NY, October 20-23, 2013           
  • Selected as a pre-doctoral fellow to the NIH/NCI T32 Departmental training grant.  September 2013.

Medical School Activities

Extracurricular Interests