Fucoidan, a sulfated polysaccharide purified from brown algae, has a variety of immune-modulation effects, including promoting antigen uptake and enhancing anti-viral and anti-tumor effects. However, the effect of fucoidan in vivo, especially its adjuvant effect on in vivo anti-tumor immune responses, was not fully investigated. In this study, we investigated the effect of fucoidan on the function of spleen dendritic cells (DCs) and its adjuvant effect in vivo. Systemic administration of fucoidan induced up-regulation of CD40, CD80 and CD86 expression and production of IL-6, IL-12 and TNF-α in spleen cDCs. Fucoidan also promoted the generation of IFN-γ-producing Th1 and Tc1 cells in an IL-12-dependent manner. When used as an adjuvant in vivo with ovalbumin (OVA) antigen, fucoidan promoted OVA-specific antibody production and primed IFN-γ production in OVA-specific T cells. Moreover, fucoidan enhanced OVA-induced up-regulation of MHC class I and II on spleen cDCs and strongly prompted the proliferation of OVA-specific CD4 and CD8 T cells. Finally, OVA immunization with fucoidan as adjuvant protected mice from the challenge with B16-OVA tumor cells. Taken together, these results suggest that fucoidan can function as an adjuvant to induce Th1 immune response and CTL activation, which may be useful in tumor vaccine development.

Marine-derived sulfated polysaccharides have been shown to possess certain anti-virus, anti-tumor, anti-inflammatory and anti-coagulant activities. However, the in vivo immunomodulatory effects of marine-derived pure compounds have been less well characterized. In this study, we investigated the effect of ascophyllan, a sulfated polysaccharide purified from Ascophyllum nodosum, on the maturation of mouse dendritic cells (DCs) in vitro and in vivo. Ascophyllan induced up-regulation of co-stimulatory molecules and production of pro-inflammatory cytokines in bone marrow-derived DCs (BMDCs). Moreover, in vivo administration of ascophyllan promotes up-regulation of CD40, CD80, CD86, MHC class I and MHC class II and production of IL-6, IL-12 and TNF-α in spleen cDCs. Interestingly, ascophyllan induced a higher degree of co-stimulatory molecule up-regulation and pro-inflammatory cytokine production than fucoidan, a marine-derived polysaccharide with well-defined effect for promoting DC maturation. Ascophyllan also promoted the generation of IFN-γ-producing Th1 and Tc1 cells in the presence of DCs in an IL-12-dependent manner. Finally, myeloid differentiation primary response 88 (MyD88) signaling pathway was essential for DC maturation induced by ascophyllan. Taken together, these results demonstrate that ascophyllan induces DC maturation, and consequently enhances Th1 and Tc1 responses in vivo. This knowledge could facilitate the development of novel therapeutic strategies to combat infectious diseases and cancer.

؉ mDCs, and these two receptors were both required for the recognition of S. aureus and the subsequent activation of BDCA1 ؉ mDCs. Finally, BDCA1 ؉ mDC-mediated immune responses against S. aureus were dependent on MyD88 signaling pathways. These results demonstrate that human BDCA1؉ mDCs represent a unique subset of mDCs that can respond to S. aureus to undergo maturation and activation and to induce Th1 and Tc1 immune responses.

bInterleukin-7 (IL-7) engages multiple mechanisms to overcome chronic viral infections, but the role of IL-7 in bacterial infections, especially enteric bacterial infections, remains unclear. Here we characterized the previously unexplored role of IL-7 in the innate immune response to the attaching and effacing bacterium Citrobacter rodentium. C. rodentium infection induced IL-7 production from intestinal epithelial cells (IECs). IL-7 production from IECs in response to C. rodentium was dependent on gamma interferon (IFN-␥)-producing NK1.1 ؉ cells and IL-12. Treatment with anti-IL-7R␣ antibody during C. rodentium infection resulted in a higher bacterial burden, enhanced intestinal damage, and greater weight loss and mortality than observed with the control IgG treatment. IEC-produced IL-7 was only essential for protective immunity against C. rodentium during the first 6 days after infection. An impaired bacterial clearance upon IL-7R␣ blockade was associated with a significant decrease in macrophage accumulation and activation in the colon. Moreover, C. rodentium-induced expansion and activation of intestinal CD4 ؉ lymphoid tissue inducer (LTi) cells was completely abrogated by IL-7R␣ blockade. Collectively, these data demonstrate that IL-7 is produced by IECs in response to C. rodentium infection and plays a critical role in the protective immunity against this intestinal attaching and effacing bacterium. Citrobacter rodentium is a mouse extracellular enteric pathogen that mimics human-enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E coli (EHEC). These bacterial pathogens attach intimately to intestinal epithelium and cause subcellular attaching and effacing lesions, which lead to severe diarrhea, vomiting, and fever, with high rates of fatality (1). C. rodentium infection of mice causes epithelial hyperplasia in the colon and cecum, goblet cell loss, and mucosal infiltration with macrophages, lymphocytes, and neutrophils (2). Therefore, this is an ideal model to dissect how immune cells interact with gut epithelial pathogens. The innate immune cells, including macrophages, dendritic cells (DCs), natural killer (NK) cells, neutrophils, and innate lymphoid cells (ILCs) have been shown to play an essential role in the clearance of C. rodentium infection (3-6). Moreover, the adaptive immune cells, mostly T and B cells, are also required for the clearance of this pathogen (7,8). Furthermore, the cytokines interleukin-6 (IL-6), IL-12, IL-17, IL-22, IL-23, and gamma interferon (IFN-␥) are upregulated in the colon tissues of C. rodentium-infected mice and are necessary for an effective immune defense against this pathogen (3-5, 7, 9).IL-7 is a stroma-derived cytokine that can be secreted by fetal liver cells, stromal cells in the bone marrow and thymus, and intestinal epithelial cells (IECs) (10). IL-7 acts on various cells through its receptor, a heterodimer consisting of an alpha-chain (IL-7R␣) and the common cytokine receptor gamma chain. The IL-7 receptor is expressed on lymphoid T and B precursors...

Metastatic disease is the leading cause of death due to prostate cancer (PCa). Although the hypermethylated in cancer 1 (HIC1) gene has been observed to be epigenetically modified in PCa, its intrinsic role and mechanism in PCa metastasis still remain uncertain. Here, we show that hypermethylation of the HIC1 promoter markedly reduces its suppressive function in metastatic PCa tissues as compared with primary and adjacent normal prostate tissues, and is associated with poor patient survival. PCas in cancer-prone mice homozygous for a prostate-targeted Hic1 conditional knockout showed stronger metastatic behaviour than those in heterozygous mice, as a result of epithelial-mesenchymal transition (EMT). Moreover, impairment of HIC1 expression in PCa cells induced their migration and metastasis through EMT, by enhancing expression of Slug and CXCR4, both of which are critical to PCa metastasis; the CXCL12-CXCR4 axis promotes EMT by activating the extracellular signal-regulated kinase (ERK) 1/2 pathway. Taken together, our results suggest that evaluation of HIC1-CXCR4-Slug signalling may provide a potential predictor for PCa aggressiveness. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Dendritic cell- (DC-) based vaccination has emerged as a promising antitumour immunotherapy. However, overcoming immune tolerance and immunosuppression in the tumour microenvironment (TME) is still a great challenge. Recent studies have shown that Rose Bengal (RB) can effectively induce immunogenic cell death (ICD) in cancer cells, presenting whole tumour antigens for DC processing and presentation. However, the synergistic antitumour effect of combining intralesional RB with immature DCs (RB-iDCs) remains unclear. In the present study, we investigated whether RB-iDCs have superior antitumour effects compared with either single agent and evaluated the immunological mechanism of RB-iDCs in a murine lung cancer model. The results showed that intralesional RB-iDCs suppressed subcutaneous tumour growth and lung metastasis, which resulted in 100% mouse survival and significantly increased TNF-α production by CD8+ T cells. These effects were closely related to the induction of the expression of distinct ICD hallmarks by RB in both bulk cancer cells and cancer stem cells (CSCs), especially calreticulin (CRT), thus enhancing immune effector cell (i.e., CD4+, CD8+, and memory T cells) infiltration and attenuating the accumulation of immunosuppressive cells (i.e., Tregs, macrophages, and myeloid-derived suppressor cells (MDSCs)) in the TME. This study reveals that the RB-iDC vaccine can synergistically destroy the primary tumour, inhibit distant metastasis, and prevent tumour relapse in a lung cancer mouse model, which provides important preclinical data for the development of a novel combinatorial immunotherapy.

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