Abstract P042: Chemokine dysregulation creates the immunosuppressive tumor microenvironment and promotes human papillomavirus-associated head and neck cancer

Human papillomavirus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) is a fast-growing health problem in the United States. By analyzing the transcriptomes of HPV-positive (HPV+) and HPV-negative (HPV-) HNSCC patient tissues, we previously revealed that expression of CXCL14, constitutively expressed in basal epithelial cells, is downregulated in HPV-positive HNSCC. In contrast, the expression of proinflammatory chemokines, particularly CXCL1, CXCL2, and CXCL8, are significantly upregulated in both HPV+ and HPV- HNSCCs. We further showed that restored expression of CXCL14 in HPV+ HNSCC cells leads to tumor-free survival in vivo by increasing MHC-I antigen presentation on the cancer cell surface and CD8+ T cell activation. Interestingly, high CXCL1, CXCL2, and CXCL8 expression levels significantly correlate to poor HNSCC patient survival, showing an exact opposite pattern of the clinical outcomes associated with the CXCL14 expression levels. To determine the roles of these chemokines in HPV+ HNSCC development, CXCL1 and CXCL2 genes (no murine CXCL8 ortholog) were deleted using a CRISPR-Cas9 knockout system in HPV+ murine HNSCC cells. Using these stably engineered HNSCC cells, we investigated tumor growth, immune cell infiltration, and metastasis in immunocompetent syngeneic mice. Interestingly, the deletion of CXCL1 and CXCL2 significantly delays in vivo tumor growth, decreases myeloid-derived suppressor cell (MDSC) infiltration in the tumor, and decreases lung metastasis. However, the numbers of natural killer (NK), CD4+, and CD8+ T cells in the tumor microenvironment were not affected by CXCL1 and CXCL2 knockout. Next, mice injected with the murine HNSCC cells were treated twice daily with AZD5068, a selective inhibitor of CXCR2, which is a common receptor of CXCL1, CXCL2, and CXCL8 expressed on myeloid cells. Our result showed that the treatment of CXCR2 suppresses in vivo tumor growth in a similar pattern with CXCL1 and CXCL2 knockout. These results suggest that the dysregulation of chemokine expression in HPV-infected cells plays an important role in regulating tumor growth, antitumor immune responses, and metastasis of HPV+ HNSCC. Our findings may provide promising strategies to develop novel immunotherapies for HPV+ HNSCC patients which can likely be extended to other non-viral cancers with immunosuppressive phenotypes.

Citation Format: Daniel Vermeer, Joseph Westrich, Paul Colbert, Craig Welbon, John H. Lee, David Raben, William C. Spanos, Dohun Pyeon. Chemokine dysregulation creates the immunosuppressive tumor microenvironment and promotes human papillomavirus-associated head and neck cancer [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P042.

Fracture Sealing with Microbially-Induced Calcium Carbonate Precipitation: A Field Study

A primary environmental risk from unconventional oil and gas development or carbon sequestration is subsurface fluid leakage in the near wellbore environment. A potential solution to remediate leakage pathways is to promote microbially induced calcium carbonate precipitation (MICP) to plug fractures and reduce permeability in porous materials. The advantage of microbially induced calcium carbonate precipitation (MICP) over cement-based sealants is that the solutions used to promote MICP are aqueous. MICP solutions have low viscosities compared to cement, facilitating fluid transport into the formation. In this study, MICP was promoted in a fractured sandstone layer within the Fayette Sandstone Formation 340.8 m below ground surface using conventional oil field subsurface fluid delivery technologies (packer and bailer). After 24 urea/calcium solution and 6 microbial (Sporosarcina pasteurii) suspension injections, the injectivity was decreased (flow rate decreased from 1.9 to 0.47 L/min) and a reduction in the in-well pressure falloff (>30% before and 7% after treatment) was observed. In addition, during refracturing an increase in the fracture extension pressure was measured as compared to before MICP treatment. This study suggests MICP is a promising tool for sealing subsurface fractures in the near wellbore environment.

Hypoxia inducible factor-1 alpha links reduced oxygen availability to the generation of anti-inflammatory IL-10 expressing T cells (P1328)

Hypoxia, the state of limited oxygen availability, is a frequent metabolic constraint in physiologic and pathologic states. The impact of hypoxia and hypoxic signaling on T cell differentiation remains incompletely defined, especially regarding inhibitory pathways that may be induced to limit hypoxia-associated tissue damage. Here we identified CD4 and CD8 T cells expressing IL-10 in the context of inflammatory hypoxia in vivo. To test the consequence of limited oxygen availability on the generation of IL-10 expressing T cells, we analyzed T cell differentiation under hypoxic conditions. Hypoxic culture significantly induced IL-10 expression in both CD4 and CD8 T cells. Hypoxia further increased IL-10 expression across diverse differentiation conditions, including conditions known to induce IL-10 expression. The hypoxic enhancement of IL-10 producing T cells was independent of TGF-β and IL-27, but required signals from multiple cell types, as well as T cell-intrinsic expression of the transcription factor hypoxia inducible factor (HIF)-1α. HIF-1α was further required for IL-10 expression in regulatory T cells even in normoxia, consistent with impaired suppressive function of HIF-1α deficient Tregs in vitro and in vivo. In total, these data demonstrate that reduced oxygen availability, interpreted through the HIF-1α transcription factor, is a potent physiologic cue that can drive T cell differentiation towards IL-10 production, thereby limiting immune-mediated pathology.