CXCL14 Promotes a Robust Brain Tumor-Associated Immune Response in Glioma

PURPOSE

The immunosuppressive tumor microenvironment present in the majority of diffuse glioma limits therapeutic response to immunotherapy. As the determinants of the glioma-associated immune response are relatively poorly understood, the study of glioma with more robust tumor-associated immune responses may be particularly useful to identify novel immunomodulatory factors that can promote T-cell effector function in glioma.

EXPERIMENTAL DESIGN

We used multiplex immune-profiling, proteomic profiling, and gene expression analysis to define the tumor-associated immune response in two molecular subtypes of glioma and identify factors that may modulate this response. We then used patient-derived glioma cultures and an immunocompetent murine model for malignant glioma to analyze the ability of tumor-intrinsic factors to promote a CD8+ T-cell response.

RESULTS

As compared with isocitrate dehydrogenase (IDH)-mutant astrocytoma, MAPK-activated pleomorphic xanthoastrocytoma (PXA) harbored increased numbers of activated cytotoxic CD8+ T cells and Iba1+ microglia/macrophages, increased MHC class I expression, enrichment of genes associated with antigen presentation and processing, and increased tumor cell secretion of the chemokine CXCL14. CXCL14 promoted activated CD8+ T-cell chemotaxis in vitro, recruited tumor-infiltrating CD8+ T cells in vivo, and prolonged overall survival in a cytotoxic T-cell-dependent manner. The immunomodulatory molecule B7-H3 was also highly expressed in PXA.

CONCLUSIONS

We identify the MAPK-activated lower grade astrocytoma PXA as having an immune-rich tumor microenvironment and suggest this tumor may be particularly vulnerable to immunotherapeutic modulation. We also identify CXCL14 as an important determinant of the glioma-associated immune microenvironment, sufficient to promote an antitumor CD8+ T-cell response.

CXCL14 and NOS1 expression in specimens from patients with stage I-IIIA nonsmall cell lung cancer after curative resection

Many studies show that CXC chemokine ligand 14 (CXCL14) is highly expressed in tumor-associated stromal cells, promoting tumor cell growth, and invasion. Because of its unclear receptors, CXCL14-initiated intracellular signal cascades remain largely unknown. However, CXCL14 can regulate nitric oxide synthase 1 (NOS1) as its intracellular molecular target. In this paper, we investigated the expression of CXCL14 and NOS1 in specimens from patients with stage I-IIIA nonsmall cell lung cancer (NSCLC) after curative resection, and evaluated the prognostic significance of this gene expression in stromal fibroblasts and cancer cells.Immunohistochemistry was used to detect the expression of CXCL14 and NOS1 in 106 formalin fixed, paraffin-embedded specimens from patients with stage I-IIIA NSCLC. The chi-square test was performed to examine the correlation of CXCL14 and NOS1 expression level with clinicopathological features. The effects of the expression of CXCL14 or NOS1 on progression-free survival (PFS) and overall survival (OS) were determined by Kaplan-Meier and Cox hazard proportional model.The percentages of high CXCL14 expression in stromal fibroblasts and that in cancer cells were 46.2% (49/106) and 23.6% (25/106), respectively. The positive expression rates of NOS1 in cancer cells were 42.5% (45/106). The result indicated that there was a significant positive correlation between CXCL14 expression level in stromal fibroblasts and that in cancer cells (χ = 4.158, P = .041). In addition, the expression of CXCL14 in stromal fibroblasts was significantly correlated with NOS1 expression in cancer cells (χ = 16.156, P < .001). The 5-year PFS rates with low and high CXCL14 expression in stromal fibroblasts were 66.7% and 14.3% (χ = 44.008, P < .001), respectively, and the 5-year OS rates with those were 87.1% and 43.5% (χ = 21.531, P < .001), respectively. The 5-year PFS rates with negative and positive expression of NOS1 in cancer cells were 62.3% and 15.6% (χ = 33.756, P < .001), respectively, and the 5-year OS rates with those were 86.4% and 40.1% (χ = 24.430, P < 0.01), respectively.Both the high expression of CXCL14 in stromal fibroblasts and the positive expression of NOS1 in cancer cells are independent negative predictors of PFS and OS in patients with stage I-IIIA NSCLC after curative resection.

Spatiotemporal expression and functional implication of CXCL14 in the developing mice cerebellum

Cerebellar granule neurons migrate from the external granule cell layer (EGL) to the internal granule cell layer (IGL) during postnatal morphogenesis. This migration process through 4 different layers is a complex mechanism which is highly regulated by many secreted proteins. Although chemokines are well-known peptides that trigger cell migration, but with the exception of CXCL12, which is responsible for prenatal EGL formation, their functions have not been thoroughly studied in granule cell migration. In the present study, we examined cerebellar CXCL14 expression in neonatal and adult mice. CXCL14 mRNA was expressed at high levels in adult mouse cerebellum, but the protein was not detected. Nevertheless, Western blotting analysis revealed transient expression of CXCL14 in the cerebellum in early postnatal days (P1, P8), prior to the completion of granule cell migration. Looking at the distribution of CXCL14 by immunohistochemistry revealed a strong immune reactivity at the level of the Purkinje cell layer and molecular layer which was absent in the adult cerebellum. In functional assays, CXCL14 stimulated transwell migration of cultured granule cells and enhanced the spreading rate of neurons from EGL microexplants. Taken together, these results revealed the transient expression of CXCL14 by Purkinje cells in the developing cerebellum and demonstrate the ability of the chemokine to stimulate granule cell migration, suggesting that it must be involved in the postnatal maturation of the cerebellum.