Induced Tumor Heterogeneity Reveals Factors Informing Radiation and Immunotherapy Combinations.

PURPOSE: To investigate how induced tumor heterogeneity influences immune responses to radiotherapy with different proportions of mixed immune-responsive and unresponsive tumor cells in a triple-negative breast cancer model. It is hypothesized that studying the immune environment of mixed tumors and responses to radiotherapy could nominate immune active therapies to enhance immune responses after radiotherapy. EXPERIMENTAL DESIGN: Evaluate efficacy and immune responses generated by radiotherapy in tumors with different proportions of immunologically responsive and unresponsive tumor cells. Then study the cellular responses and transcriptomic differences between the tumors to nominate immunotherapy combinations with radiotherapy and evaluate the combination. RESULTS: The addition of the responsive cells to unresponsive tumors led to a greater than expected therapeutic response to radiotherapy with both innate and adaptive immune components. There was a distinct change in myeloid cells, greater inflammatory macrophage activity, and enhanced antigen presentation with responsive cells after radiotherapy. Because differences in matrix components, cell adhesion biology, and innate immune signaling correlated with myeloid cell response and phenotype, we hypothesized that radiotherapy combined with CD40 agonist antibody would sensitize unresponsive tumors. The combination therapy resulted in improved innate and adaptive immune response. Importantly, CD40 treatment increased tumor response to radiotherapy and protected against metastatic spread in a metastatic model. CONCLUSIONS: These data combined with transcriptomics from human patients support radiotherapy and myeloid cell targeting for immunologically cold tumors. The established study model presents opportunities to investigate the complex overlapping biologic mechanisms that limit immunotherapy and to implement radiotherapy with different immunotherapy combinations.

Monocytes undergo multi-step differentiation in mice during oral infection by Toxoplasma gondii.

Monocytes play a major role in the defense against pathogens. They are rapidly mobilized to inflamed sites where they exert both proinflammatory and regulatory effector functions. It is still poorly understood how this dynamic and exceptionally plastic system is controlled at the molecular level. Herein, we evaluated the differentiation process that occurs in Ly6Chi monocytes during oral infection by Toxoplasma gondii. Flow cytometry and single-cell analysis revealed distinct activation status and gene expression profiles in the bone marrow, the spleen and the lamina propria of infected mice. We provide further evidence that acquisition of effector functions, such as the capacity to produce interleukin-27, is accompanied by distinct waves of epigenetic programming, highlighting a role for STAT1/IRF1 in the bone marrow and AP-1/NF-κB in the periphery. This work broadens our understanding of the molecular events that occur in vivo during monocyte differentiation in response to inflammatory cues.

Collagen Remodeling in the Hypoxic Tumor-Mesothelial Niche Promotes Ovarian Cancer Metastasis.

Peritoneal metastases are the leading cause of morbidity and mortality in high-grade serous ovarian cancer (HGSOC). Accumulating evidence suggests that mesothelial cells are an important component of the metastatic microenvironment in HGSOC. However, the mechanisms by which mesothelial cells promote metastasis are unclear. Here, we report that the HGSOC tumor-mesothelial niche was hypoxic, and hypoxic signaling enhanced collagen I deposition by mesothelial cells. Specifically, hypoxic signaling increased expression of lysyl oxidase (LOX) in mesothelial and ovarian cancer cells to promote collagen crosslinking and tumor cell invasion. The mesothelial niche was enriched with fibrillar collagen in human and murine omental metastases. Pharmacologic inhibition of LOX reduced tumor burden and collagen remodeling in murine omental metastases. These findings highlight an important role for hypoxia and mesothelial cells in the modification of the extracellular matrix and tumor invasion in HGSOC. SIGNIFICANCE: This study identifies HIF/LOX signaling as a potential therapeutic target to inhibit collagen remodeling and tumor progression in HGSOC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/9/2271/F1.large.jpg.

Computed navigated total knee arthroplasty compared to computed tomography scans.

BACKGROUND: Successful total knee arthroplasty (TKA) includes accurate alignment. Controversy remains as to whether computer-navigated TKA improves the overall result and clinical outcome. Our aim is to compare the limb alignment and prosthesis positioning according to the pre- and postoperative computed tomography (CT) scans with the data collected from the navigation system. METHODS: We compared the pre- and postoperative limb alignments and prosthesis alignment provided by the Orthopilot navigation system, Aesculap®, with CT scans measured by the Traumacad® software of 70 TKAs. RESULTS: A positive correlation with statistical significance (P=0.00001, r=0.874) between the navigation system data and the CT images was found. Mean femoral cut was five degrees (valgus), and mean tibial cut was one degree (varus). Our study revealed that the navigation system assisted the surgeon to implant the prosthesis at a good acceptable alignment. CONCLUSION: We found that the navigation system is accurate and correlates to the pre- and postoperative CT scans. Furthermore, the navigation system can assist the surgeon to achieve good limb alignment and cutting planes of the prosthesis.

Reprogramming the immunological microenvironment through radiation and targeting Axl.

Increasing evidence suggests that ionizing radiation therapy (RT) in combination with checkpoint immunotherapy is highly effective in treating a subset of cancers. To better understand the limited responses to this combination we analysed the genetic, microenvironmental, and immune factors in tumours derived from a transgenic breast cancer model. We identified two tumours with similar growth characteristics but different RT responses primarily due to an antitumour immune response. The combination of RT and checkpoint immunotherapy resulted in cures in the responsive but not the unresponsive tumours. Profiling the tumours revealed that the Axl receptor tyrosine kinase is overexpressed in the unresponsive tumours, and Axl knockout resulted in slower growth and increased radiosensitivity. These changes were associated with a CD8+ T-cell response, which was improved in combination with checkpoint immunotherapy. These results suggest a novel role for Axl in suppressing antigen presentation through MHCI, and enhancing cytokine release, which promotes a suppressive myeloid microenvironment.

Cutting Edge: Hypoxia-Inducible Factor 1 Negatively Regulates Th1 Function.

Tissue hypoxia can occur in physiological and pathological conditions. When O2 availability decreases, the transcription factor hypoxia-inducible factor (HIF)-1α is stabilized and regulates cellular adaptation to hypoxia. The objective of this study was to test whether HIF-1α regulates T cell fate and to define the molecular mechanisms of this control. Our data demonstrate that Th1 cells lose their capacity to produce IFN-γ when cultured under hypoxia. HIF-1α(-/-) Th1 cells were insensitive to hypoxia, underlining a critical role for HIF-1α. Our results point to a role for IL-10, as suggested by the increased IL-10 expression at low O2 levels and the unchanged IFN-γ production by IL-10-deficient Th1 cells stimulated in hypoxic conditions. Accordingly, STAT3 phosphorylation is increased in Th1 cells under hypoxia, leading to enhanced HIF-1α transcription, which, in turn, may inhibit suppressor of cytokine signaling 3 transcription. This positive-feedback loop reinforces STAT3 activation and downregulates Th1 responses that may cause collateral damage to the host.

Hypoxia in the intestine or solid tumors: a beneficial or deleterious alarm signal?

The transcription factor hypoxia inducible factors (HIF)-1 functions as a master regulator of oxygen homeostasis. There is increasing evidence that HIF has an essential role to prevent tissue damage in physiological and pathological situations in which cells are deprived of O2. Here, we review the effects of decreased oxygen supply on the innate and adaptive immune responses in the gut and in solid tumors in which the oxygenation profile correlates with the grade of inflammation. Data in the literature indicate that some tumors may co-opt immune mechanisms induced by HIF-1 to promote their survival and proliferation. By contrast, HIF-1 stabilization would have a beneficial effect in the intestinal tract as it would dampen inflammation and promote its resolution. Therefore, stabilization of HIF-1 in hypoxia may have opposite effects on the integrity of the host, depending on the tissue microenvironment.