Probes for INS

Prostate cancer (PCa) does not appear to respond to immune checkpoint therapies where T cell infiltration may be a key limiting factor. Here we report evidence that ablating the growth regulatory kinase Erk5 can increase T cell infiltration in an established Pten-deficient mouse model of human PCa. Mice that were doubly mutant in prostate tissue for Pten and Erk5 (prostate DKO) exhibited a markedly increased median survival with reduced tumor size and proliferation compared to control Pten-mutant mice, the latter of which exhibited increased Erk5 mRNA expression. A comparative transcriptomic analysis revealed upregulation in prostate DKO mice of the chemokines Ccl5 and Cxcl10, two potent chemoattractants for T lymphocytes. Consistent with this effect, we observed a relative increase in a predominantly CD4+ T cell infiltrate in the prostate epithelial and stroma of tumors from DKO mice. Collectively, our results offer a preclinical proof of concept for ERK5 as a target to enhance T cell infiltrates in prostate cancer, with possible implications for leveraging immune therapy in this disease.

Sipuleucel-T is the only FDA-approved immunotherapy for metastatic castration-resistant prostate cancer. The mechanism by which this treatment improves survival is not fully understood. We have previously shown that this treatment can induce the recruitment of CD4 and CD8 T cells to the tumor microenvironment. In this study, we examined the functional state of these T cells through gene expression profiling. We found that the magnitude of T cell signatures correlated with the frequency of T cells as measured by immunohistochemistry. Sipuleucel-T treatment was associated with increased expression of Th1-associated genes, but not Th2-, Th17 – or Treg-associated genes. Post-treatment tumor tissues with high CD8+T cell infiltration was associated with high levels of CXCL10 expression. On in situ hybridization, CXCL10+ cells colocalized with CD8+T cells in post-treatment prostatectomy tumor tissue. Neoadjuvant sipuleucel-T was also associated with upregulation of immune inhibitory checkpoints, including CTLA4 and TIGIT, and downregulation of the immune activation marker, dipeptidylpeptidase, DPP4. Treatment-associated declines in serum PSA were correlated with induction of Th1 response. In contrast, rises in serum PSA while on treatment were associated with the induction of multiple immune checkpoints, including CTLA4, CEACAM6 and TIGIT. This could represent adaptive immune resistance mechanisms induced by treatment. Taken together, neoadjuvant sipuleucel-T can induce both a Th1 response and negative immune regulation in the prostate cancer microenvironment.

T cells in colorectal cancer (CRC) are associated with improved survival. However, checkpoint immunotherapies antagonizing the suppression of these cells are ineffective in the great majority of patients. To better understand the immune cell regulation in CRC, we compared tumor-associated T lymphocytes and macrophages to the immune cell infiltrate of normal mucosa. Human colorectal tumor specimen and tumor-distant normal mucosa tissues of the same patients were collected. Phenotypes and functionality of tissue-derived T cells and macrophages were characterized using immunohistochemistry, RNA in situ hybridization, and multiparameter flow cytometry. CRC contained significantly higher numbers of potentially immunosuppressive CD39 and Helios-expressing regulatory T cells in comparison to normal mucosa. Surprisingly, we found a concomitant increase of pro-inflammatory IFNγ -producing T cells. PD-L1+ stromal cells were decreased in the tumor tissue. Macrophages in the tumor compared to tumor-distant normal tissue appear to have an altered phenotype, identified by HLA-DR, CD14, CX3CR1, and CD64, and tolerogenic CD206+macrophages are quantitatively reduced. The prognostic effect of these observed differences between distant mucosa and tumor tissue on the overall survival was examined using gene expression data of 298 CRC patients. The combined gene expression of increased FOXP3, IFNγ, CD14, and decreased CD206 correlated with a poor prognosis in CRC patients. These data reveal that the CRC microenvironment promotes the coexistence of seemingly antagonistic suppressive and pro-inflammatory immune responses and might provide an explanation why a blockade of the PD1/PD-L1 axis is ineffective in CRC. This should be taken into account when designing novel treatment strategies.

Traumatic optic neuropathy (TON) is an acute injury of the optic nerve secondary to trauma. Loss of retinal ganglion cells (RGCs) is a key pathological process in TON, yet mechanisms responsible for RGC death remain unclear. In a mouse model of TON, real-time noninvasive imaging revealed a dramatic increase in leukocyte rolling and adhesion in veins near the optic nerve (ON) head at 9 hours after ON injury. Although RGC dysfunction and loss were not detected at 24 hours after injury, massive leukocyte infiltration was observed in the superficial retina. These cells were identified as T cells, microglia/monocytes, and neutrophils but not B cells. CXCL10 is a chemokine that recruits leukocytes after binding to its receptor C-X-C chemokine receptor (CXCR) 3. The levels of CXCL10 and CXCR3 were markedly elevated in TON, and up-regulation of CXCL10 was mediated by STAT1/3. Deleting CXCR3 in leukocytes significantly reduced leukocyte recruitment, and prevented RGC death at 7 days after ON injury. Treatment with CXCR3 antagonist attenuated TON-induced RGC dysfunction and cell loss. In vitro co-culture of primary RGCs with leukocytes resulted in increased RGC apoptosis, which was exaggerated in the presence of CXCL10. These results indicate that leukocyte recruitment in retinal vessels near the ON head is an early event in TON and the CXCL10/CXCR3 axis has a critical role in recruiting leukocytes and inducing RGC death.