The development of an environmentally benign process for the hydrolysis of cellulose into reducing sugars can be one of the key technologies for making full use of cellulosic biomass in the future. Here, a biomass char sulfonic acid (BC-SO 3 H)-catalyzed hydrolysis of cellulose in water was achieved under microwave irradiation. The BC-SO 3 H catalysts prepared cheaply from natural bamboo, cotton and starch, showed a much higher turnover number (TON, 1.33-1.73) for this reaction compared to a dilute H 2 SO 4 solution (TON, 0.02), which was likely due to their strong affinity to b-1,4-glycosidic bonds of cellulose. In addition, microwave irradiation played key roles in activating cellulose molecules and strengthening particle collision, which can lead to a remarkable acceleration effect on this heterogeneously catalytic process.

V-domain Ig suppressor of T cell activation (VISTA), a novel immune checkpoint regulatory molecule, suppresses T cell mediated immune responses. The aim of the present study was to profile the immunological expression, clinical significance and correlation of VISTA in human oral squamous cell carcinoma (OSCC). Human tissue microarrays, containing 165 primary OSCCs, 48 oral epithelial dysplasias and 43 normal oral mucosae, were applied to investigate the expression levels of VISTA, CD8, cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), programmed death ligand 1 (PD-L1), PI3Kα p110, IL13Rα2, phospho-STAT3 at tyrosine 705 (p-STAT3) and myeloid-derived suppressor cell (MDSC) markers (CD11b and CD33) by immunohistochemistry and digital pathology analysis. The results demonstrated that the protein level of VISTA was significantly higher in human OSCC specimens, and that VISTA expression in primary OSCCs was correlated with lymph node status. VISTA expression did not serve as an independent predictor for poor prognosis, while patient subgroup with VISTA high and CD8 low expression (22/165) had significantly poorer overall survival compared with other subgroups based on the multivariate and Cox hazard analyses among the primary OSCC patients in the present cohort. Additionally, the expression of VISTA was significantly correlated with PD-L1, CTLA-4, IL13Rα2, PI3K, p-STAT3, CD11b and CD33 according to Pearson's correlation coefficient test. Taken together, the results indicated that the VISTA high and CD8 low group, as an immunosuppressive subgroup, might be associated with a poor prognosis in primary OSCC. These findings indicated that VISTA might be a potential immunotherapeutic target in OSCC treatment.

BackgroundCancer immunotherapy offers a promising approach in cancer treatment. The adenosine A2A receptor (A2AR) could protect cancerous tissues from immune clearance via inhibiting T cells response. To date, the role of A2AR in head and neck squamous cell carcinoma (HNSCC) has not been investigated. Here, we sought to explore the expression and immunotherapeutic value of A2AR blockade in HNSCC.MethodsThe expression of A2AR was evaluated by immunostaining in 43 normal mucosae, 48 dysplasia and 165 primary HNSCC tissues. The immunotherapeutic value of A2AR blockade was assessed in vivo in genetically defined immunocompetent HNSCC mouse model.ResultsImmunostaining of HNSCC tissue samples revealed that increased expression of A2AR on tumor infiltrating immune cells correlated with advanced pathological grade, larger tumor size and positive lymph node status. Elevated A2AR expression was also detected in recurrent HNSCC and HNSCC tissues with induction chemotherapy. The expression of A2AR was found to be significantly correlated with HIF-1α, CD73, CD8 and Foxp3. Furthermore, the increased population of CD4+Foxp3+ regulatory T cells (Tregs), which partially expressed A2AR, was observed in an immunocompetent mouse model that spontaneously develops HNSCC. Pharmacological blockade of A2AR by SCH58261 delayed the tumor growth in the HNSCC mouse model. Meanwhile, A2AR blockade significantly reduced the population of CD4+ Foxp3+ Tregs and enhanced the anti-tumor response of CD8+ T cells.ConclusionsThese results offer a preclinical proof for the administration of A2AR inhibitor on prophylactic experimental therapy of HNSCC and suggest that A2AR blockade can be a potential novel strategy for HNSCC immunotherapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-017-0665-0) contains supplementary material, which is available to authorized users.

Head and neck cancer is one of the most prevalent cancers around the world. Head and neck squamous cell carcinoma (HNSCC) accounts for nearly 90% of head and neck cancer. In recent years, significant advances have been made in immunotherapy for HNSCC. Although some clinical trials targeting immune checkpoints have shown success, the molecular mechanism for regulation of programmed death 1 (PD-1) and its ligand (PD-L1) is partially understood. In an effort to explore the effect of activation of signal transducers and activators of transcriptions (STAT3) on PD-1/PD-L1, the expression and correlation between phosphorylation of STAT3 and PD-1/PD-L1 were determined with immunostaining of human and mouse HNSCC tissue sections. PD-1/PD-L1 overexpression was found to be significantly associated with p-STAT3 in human and mouse HNSCC. Targeting STAT3 by a small molecule effectively inhibited the expression of PD-L1 in the CAL27 cell line. Furthermore, we found that blockade of STAT3 signaling downregulated PD-1/PD-L1 in a Tgfbr1/Pten 2cKO HNSCC mouse model. These findings suggest that STAT3 signaling plays an important role in PD-1/PD-L1 regulation and the antitumor immune response of HNSCC.

Immunosuppression is common in head and neck squamous cell carcinoma (HNSCC). In previous studies, the TIGIT/CD155 pathway was identified as an immunecheckpoint signaling pathway that contributes to the "exhaustion" state of infiltrating T cells. Here, we sought to explore the clinical significance of TIGIT/CD155 signaling in HNSCC and identify the therapeutic effect of the TIGIT/CD155 pathway in a transgenic mouse model. TIGIT was overexpressed on tumor-infiltrating CD8 þ and CD4 þ T cells in both HNSCC patients and mouse models, and was correlated with immune-checkpoint molecules (PD-1, TIM-3, and LAG-3). TIGIT was also expressed on murine regulatory T cells (Treg) and correlated with immune suppression. Using a human HNSCC tissue microarray, we found that CD155 was expressed in tumor and tumor-infiltrating stromal cells, and also indicated poor overall survival.Multispectral IHC indicated that CD155 was coexpressed with CD11b or CD11c in tumor-infiltrating stromal cells. Anti-TIGIT treatment significantly delayed tumor growth in transgenic HNSCC mouse models and enhanced antitumor immune responses by activating CD8 þ T-cell effector function and reducing the population of Tregs. In vitro coculture studies showed that anti-TIGIT treatment significantly abrogated the immunosuppressive capacity of myeloid-derived suppressor cells (MDSC), by decreasing Arg1 transcripts, and Tregs, by reducing TGFb1 secretion. In vivo depletion studies showed that the therapeutic efficacy by anti-TIGIT mainly relies on CD8 þ T cells and Tregs. Blocking PD-1/PD-L1 signaling increased the expression of TIGIT on Tregs. These results present a translatable method to improve antitumor immune responses by targeting TIGIT/CD155 signaling in HNSCC.

Immunotherapy with immune checkpoint molecule-specific monoclonal antibody have obtained encouraging results from preclinical studies and clinical trials, which promoted us to explore whether this kind of immunotherapy could be applicable to head and neck squamous cell carcinoma (HNSCC). Lymphocyte activation gene-3 (LAG-3) is an immune checkpoint control protein that negatively regulates T cells and immune response. Here, using the human tissue samples, we report these findings that LAG-3 is overexpressed on tumorinfiltrating lymphocytes (TILs; p < 0.001) and its overexpression correlates with the high pathological grades, lager tumor size and positive lymph node status in human primary HNSCC. Survival analysis identifies LAG-3 as a prognostic factor independent of tumor size and pathological grades for primary HNSCC patients with negative lymph node status (p D 0.014). Study in immunocompetent genetically defined HNSCC mouse model reports that LAG-3 is upregulated on CD4 C T cells, CD8 C T cells and CD4 C Foxp3 C regulatory T cells (Tregs). In vivo study, administration of LAG-3-specific antibody retards tumor growth in a way associated with enhanced systemic antitumor response by potentiating the antitumor response of CD8 C T cells and decreasing the population of immunosuppressive cells. Taken together, our results offer a preclinical proof supporting the immunomodulatory effects of LAG-3 and suggest a potential therapeutic target of immunotherapy for HNSCC.

The NLRP3 inflammasome is a critical innate immune pathway responsible for producing active interleukin (IL)-1β, which is associated with tumor development and immunity. However, the mechanisms regulating the inflammatory microenvironment, tumorigenesis and tumor immunity are unclear. Herein, we show that the NLRP3 inflammasome was over-expressed in human HNSCC tissues and that the IL-1β concentration was increased in the peripheral blood of HNSCC patients. Additionally, elevated NLRP3 inflammasome levels were detected in tumor tissues of Tgfbr1/Pten 2cKO HNSCC mice, and elevated IL-1β levels were detected in the peripheral blood serum, spleen, draining lymph nodes and tumor tissues. Blocking NLRP3 inflammasome activation using MCC950 remarkably reduced IL-1β production in an HNSCC mouse model and reduced the numbers of myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs) and tumor-associated macrophages (TAMs). Moreover, inhibiting NLRP3 inflammasome activation increased the numbers of CD4 and CD8 T cells in HNSCC mice. Notably, the numbers of exhausted PD-1 and Tim3 T cells were significantly reduced. A human HNSCC tissue microarray showed that NLRP3 inflammasome expression was correlated with the expression of CD8 and CD4, the Treg marker Foxp3, the MDSC markers CD11b and CD33, and the TAM markers CD68 and CD163, PD-1 and Tim3. Overall, our results demonstrate that the NLRP3 inflammasome/IL-1β pathway promotes tumorigenesis in HNSCC and inactivation of this pathway delays tumor growth, accompanied by decreased immunosuppressive cell accumulation and an increased number of effector T cells. Thus, inhibition of the tumor microenvironment through the NLRP3 inflammasome/IL-1β pathway may provide a novel approach for HNSCC therapy.

BackgroundT-cell immunoglobulin mucin 3 (TIM3) is a negative immune checkpoint and plays a crucial part in tumor-induced immune suppression. However, the mechanism of TIM3 in regulating immunosuppression in head and neck squamous cell carcinoma (HNSCC) was still not quite clear.MethodsWe carried out the immunohistochemistry staining of HNSCC tissue microarrays. Through quantification of the histoscore, we performed the correlation analysis among the TIM3, Galectin-9, Foxp3, CD68 and CD163. The effects of TIM3 on regulatory T cells (Tregs) and macrophages were detected by utilizing the Tgfbr1/Pten 2cKO HNSCC mouse model. Flow cytometry were used to analysis the percent of Tregs, macrophages and IFN-γ.ResultsWe demonstrated the close association among TIM3/Galectin-9 pathway, regulatory T cell marker (Foxp3) and macrophage marker (CD68, CD163) in human HNSCC. In the transgenic HNSCC mouse model, blockade of TIM3 by the anti-TIM3 monoclonal antibody induced a reduction of CD4+CD25+Foxp3+ Tregs. Meanwhile, the population of TIM3+ Tregs was also decreased. However, the population of CD206+ macrophages was not significantly declined. The increased IFN-γ production on CD8+ T cells in anti-TIM3 treatment mice showed that the antitumor immune response was enhanced through suppression of these negative immune factors.ConclusionsThe present study demonstrated that TIM3 was associated with the immunosuppression in HNSCC. And targeting TIM3 can enhance anti-tumor immune response by decreasing Tregs in HNSCC.