Characteristic features of in vitro differentiation of human naïve CD4+ T cells to induced regulatory T cells (iTreg) and T helper (Th) 17 cells: Sharing of lineage-specific markers.

In vitro induced regulatory T cells (iTreg) and IL-17 producing T cells (Th17-like cells) can be generated in culture from native CD4+ T cells in peripheral blood by different sets of cytokines. In the presence of transforming growth factor (TGF)-ß plus interleukin (IL)-2, cells differentiate into Treg cells with increased expression of the forkhead box P3 (FOXP3). In the presence of TGF-ß, IL-6, IL-1ß and IL-23, cells differentiate into Th17 cells that produce IL-17A. However, protocols for the generation of human iTreg and Th17 are still controversial. In this study, we characterized the biological features of iTreg and Th17 cells differentiated from peripheral blood naïve CD4+ T cells in vitro using the established protocols. We showed that cells obtained from Treg or Th17 culture conditions shared some phenotypic markers. Cells under Treg conditions had an up-regulated FOXP3 gene and a down-regulated RAR-related orphan receptor C (RORC) gene. Cells derived from the Th17 condition exhibited a down-regulated FOXP3 gene and had significantly higher RORC gene expression than Treg cells. Both resulting cells showed intracellular production of IL-17A and IL-10. Th17 condition-cultured cells exhibited more glycolytic activity and glucose uptake compared to the Treg cells. The findings suggest that cells obtained from established protocols for the differentiation of iTreg and Th17 cells in vitro are possibly in the intermediate stage of differentiation or may be two different types of cells that share a lineage-specific differentiation program.

Crosstalk between Tumor-Infiltrating Immune Cells and Cancer-Associated Fibroblasts in Tumor Growth and Immunosuppression of Breast Cancer.

Signals from the tumor microenvironment (TME) have a profound influence on the maintenance and progression of cancers. Chronic inflammation and the infiltration of immune cells in breast cancer (BC) have been strongly associated with early carcinogenic events and a switch to a more immunosuppressive response. Cancer-associated fibroblasts (CAFs) are the most abundant stromal component and can modulate tumor progression according to their secretomes. The immune cells including tumor-infiltrating lymphocytes (TILs) (cytotoxic T cells (CTLs), regulatory T cells (Tregs), and helper T cell (Th)), monocyte-infiltrating cells (MICs), myeloid-derived suppressor cells (MDSCs), mast cells (MCs), and natural killer cells (NKs) play an important part in the immunological balance, fluctuating TME between protumoral and antitumoral responses. In this review article, we have summarized the impact of these immunological players together with CAF secreted substances in driving BC progression. We explain the crosstalk of CAFs and tumor-infiltrating immune cells suppressing antitumor response in BC, proposing these cellular entities as predictive markers of poor prognosis. CAF-tumor-infiltrating immune cell interaction is suggested as an alternative therapeutic strategy to regulate the immunosuppressive microenvironment in BC.