Direct T cell-tumour interaction triggers TH1 phenotype activation through the modification of the mesenchymal stromal cells transcriptional programme.

BACKGROUND: Mesenchymal stromal cells (MSCs) are heterogeneous cells with immunoregulatory and wound-healing properties. In cancer, they are known to be an essential part of the tumour microenvironment. However, their role in tumour growth and rejection remains unclear. To investigate this, we co-cultured human MSCs, tumour infiltrating lymphocytes (TIL), and melanoma cells to investigate the role of MSCs in the tumour environment. METHODS: Mesenchymal stromal cells were co-cultured with melanoma antigen-specific TIL that were stimulated either with HLA-A*0201(+) melanoma cells or with a corresponding clone that had lost HLA-A*0201 expression. RESULTS: Activated TIL induced profound pro-inflammatory gene expression signature in MSCs. Analysis of culture supernatant found that MSCs secreted pro-inflammatory cytokines, including TH1 cytokines that have been previously associated with immune-mediated antitumor responses. In addition, immunohistochemical analysis on selected markers revealed that the same activated MSCs secreted both the TH1 cytokine (interleukin-12) and indoleamine 2,3 dioxygenase (IDO), a classical immunosuppressive factor. CONCLUSIONS: This study reflected that the plasticity of MSCs is highly dependent upon microenvironment conditions. Tumour-activated TIL induced TH1 phenotype change in MSCs that is qualitatively similar to the previously described immunologic constant of rejection signature observed during immune-mediated, tissue-specific destruction. This response may be responsible for the in loco amplification of antigen-specific anti-cancer immune response.

IRF-1 responsiveness to IFN-γ predicts different cancer immune phenotypes.

BACKGROUND: Several lines of evidence suggest a dichotomy between immune active and quiescent cancers, with the former associated with a good prognostic phenotype and better responsiveness to immunotherapy. Central to such dichotomy is the master regulator of the acute inflammatory process interferon regulatory factor (IRF)-1. However, it remains unknown whether the responsiveness of IRF-1 to cytokines is able to differentiate cancer immune phenotypes. METHODS: IRF-1 activation was measured in 15 melanoma cell lines at basal level and after treatment with IFN-γ, TNF-α and a combination of both. Microarray analysis was used to compare transcriptional patterns between cell lines characterised by high or low IRF-1 activation. RESULTS: We observed a strong positive correlation between IRF-1 activation at basal level and after IFN-γ and TNF-α treatment. Microarray demonstrated that three cell lines with low and three with high IRF-1 inducible translocation scores differed in the expression of 597 transcripts. Functional interpretation analysis showed mTOR and Wnt/ß-cathenin as the top downregulated pathways in the cell lines with low inducible IRF-1 activation, suggesting that a low IRF-1 inducibility recapitulates a cancer phenotype already described in literature characterised by poor prognosis. CONCLUSION: Our findings support the central role of IRF-1 in influencing different tumour phenotypes.

CXCR3/CCR5 pathways in metastatic melanoma patients treated with adoptive therapy and interleukin-2.

BACKGROUND: Adoptive therapy with tumour-infiltrating lymphocytes (TILs) induces durable complete responses (CR) in ∼20% of patients with metastatic melanoma. The recruitment of T cells through CXCR3/CCR5 chemokine ligands is critical for immune-mediated rejection. We postulated that polymorphisms and/or expression of CXCR3/CCR5 in TILs and the expression of their ligands in tumour influence the migration of TILs to tumours and tumour regression. METHODS: Tumour-infiltrating lymphocytes from 142 metastatic melanoma patients enrolled in adoptive therapy trials were genotyped for CXCR3 rs2280964 and CCR5-Δ32 deletion, which encodes a protein not expressed on the cell surface. Expression of CXCR3/CCR5 in TILs and CXCR3/CCR5 and ligand genes in 113 available parental tumours was also assessed. Tumour-infiltrating lymphocyte data were validated by flow cytometry (N=50). RESULTS: The full gene expression/polymorphism model, which includes CXCR3 and CCR5 expression data, CCR5-Δ32 polymorphism data and their interaction, was significantly associated with both CR and overall response (OR; P=0.0009, and P=0.007, respectively). More in detail, the predicted underexpression of both CXCR3 and CCR5 according to gene expression and polymorphism data (protein prediction model, PPM) was associated with response to therapy (odds ratio=6.16 and 2.32, for CR and OR, respectively). Flow cytometric analysis confirmed the PPM. Coordinate upregulation of CXCL9, CXCL10, CXCL11, and CCL5 in pretreatment tumour biopsies was associated with OR. CONCLUSION: Coordinate overexpression of CXCL9, CXCL10, CXCL11, and CCL5 in pretreatment tumours was associated with responsiveness to treatment. Conversely, CCR5-Δ32 polymorphism and CXCR3/CCR5 underexpression influence downregulation of the corresponding receptors in TILs and were associated with likelihood and degree of response.