Search

The tumor microenvironment (TME) plays an important role in the development of tumors. Immunoregulatory cells and cytokines facilitate cancer cells to avoid immune surveillance. Overexpression of immune checkpoint molecules such as CTLA-4 and PD-1/PD-L1 inhibits immune function and enables cancer cells to avoid clearance by the immune system. Thus, minimizing tumor immunosuppression could be an important strategy for cancer therapy. Currently, many immune checkpoint-targeted drugs, such as PD-1/PD-L1 inhibitors, have been approved for marketing and have shown unique advantages in the clinical treatment of cancers. The concept of "strengthening resistance to eliminate pathogenic factors" in traditional Chinese medicine (TCM) is consistent with the immunotherapy of cancer. According to previous studies, the role of TCM in tumor immunotherapy is mainly associated with the positive regulation of natural killer cells, CD8/CD4 T cells, dendritic cells, M2 macrophages, interleukin-2, tumor necrosis factor- α , and IFN- γ , as well as with the negative regulation of Tregs, myeloid-derived suppressor cells, cancer-associated fibroblasts, PD-1/PD-L1, transforming growth factor- β , and tumor necrosis factor- β. This paper summarizes the current research on the effect of TCM targeting the TME, and further introduces the research progress on studying the effects of TCM on immune checkpoints. Modern pharmacological studies have demonstrated that TCM can directly or indirectly affect the TME by inhibiting the overexpression of immune checkpoint molecules and enhancing the efficacy of tumor immunotherapy. TCM with immunomodulatory stimulation could be the key factor to achieve benefits from immunotherapy for patients with non-inflammatory, or "cold", tumors. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Enhanced T-cell activation by immature dendritic cells loaded with HSP70-expressing heat-killed melanoma cells. Experimental Dermatology 2010; 19: 108–116. Vaccination protocols that utilize dendritic cells (DCs) to elicit therapeutic immunity against tumors are the subject of intense research. Given that the capacity of DCs to cross-present antigens is physiologically low, there is considerable interest to develop strategies that enhance that pathway. In order to best exploit the enhanced cross-presentation of antigens bound to heat shock protein 70 (HSP70), we analysed melanoma cell preparations for their HSP70 expression. Western blotting revealed strong upregulation of HSP70 after heat-killing in contrast to UV-B irradiation. When the uptake of heat-killed necrotic cells by DCs at various levels of maturation was assessed, 61 ± 7% of immature DCs (iDCs) internalized fluorescence-labelled necrotic material. Apoptotic material from UV-B-irradiated cells was internalized by only 48 ± 5% of iDCs. Maturation-inducing cytokines did not affect the uptake when added simultaneously with the tumor cell preparations. Loading DCs with heat-necrotic or apoptotic melanoma cells slightly reduced CD83 expression while leaving CD208 (DC-LAMP) expression unchanged. As determined by IFN-γ-detecting enzyme-linked-immunospot assays, iDCs loaded with heat-killed melanoma cells activated autologous T cells most effectively when used without any further maturation, whereas DCs loaded with apoptotic material required maturation. In conclusion, HSP70-expressing melanoma cells could be generated by heat-killing. Loading iDCs with heat-killed melanoma cells resulted in a superior priming of autologous T cells in vitro. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) 'pulsed' with an appropriate antigen may elicit an antitumour immune response in mouse models. However, while attempting to develop a DC immunotherapy protocol for the treatment of breast cancer based on the tumour-associated MUC1 glycoforms, we found that unpulsed DCs can affect tumour growth. Protection from RMA-MUC1 tumour challenge was achieved in C57Bl/6 MUC1 transgenic mice by immunising with syngeneic DCs pulsed with a MUC1 peptide. However, unpulsed DCs gave a similar level of protection, making it impossible to evaluate the effect of immunisation of mice with DCs pulsed with the specific peptide. Balb/C mice could also be protected from tumour challenge by immunisation with unpulsed DCs prior to challenge with murine mammary tumour cells (410.4) or these cells transfected with MUC1 (E3). Protection was achieved with as few as three injections of 50,000 naïve DCs per mouse per week, was not dependent on injection route, and was not specific to cell lines expressing human MUC1. However, the use of Rag2-knockout mice demonstrated that the adaptive immune response was required for tumour rejection. Injection of unpulsed DCs into mice bearing the E3 tumour slowed tumour growth. In vitro, production of IFN-gamma and IL-4 was increased in splenic cells isolated from mice immunised with DCs. Depleting CD4 T cells in vitro partially decreased cytokine production by splenocytes, but CD8 depletion had no effect. This paper shows that naïve syngeneic DCs may induce an antitumour immune response and has implications for DC immunotherapy preclinical and clinical trials. [ABSTRACT FROM AUTHOR]