Targeting C-Type Lectin Receptors for Cancer Immunity.

C-type lectin receptors (CLRs) are a large family of soluble and trans-membrane pattern recognition receptors that are widely and primarily expressed on myeloid cells. CLRs are important for cell-cell communication and host defense against pathogens through the recognition of specific carbohydrate structures. Similar to a family of Toll-like receptors, CLRs signaling are involved in the various steps for initiation of innate immune responses and promote secretion of soluble factors such as cytokines and interferons. Moreover, CLRs contribute to endocytosis and antigen presentation, thereby fine-tune adaptive immune responses. In addition, there may also be a direct activation of acquired immunity. On the other hand, glycans, such as mannose structures, Lewis-type antigens, or GalNAc are components of tumor antigens and ligate CLRs, leading to immunoregulation. Therefore, agonists or antagonists of CLRs signaling are potential therapeutic reagents for cancer immunotherapy. We aim to overview the current knowledge of CLRs signaling and the application of their ligands on tumor-associating immune response.

Structural characterization and immunomodulatory effects of polysaccharides from Phellinus linteus and Phellinus igniarius on the IL-6/IL-10 cytokine balance of the mouse macrophage cell lines (RAW 264.7).

Phellinus linteus and igniarius (L.) Quel. have been used in traditional Asian medicine for over two centuries against a variety of diseases. Polysaccharides from their fruiting bodies show strong immunomodulatory activity. In this study we characterized the structure and composition of polysaccharides from Phellinus linteus and Phellinus igniarius by HPLC, GC-MS and NMR (1-H, 13-C, COSY, NOESY and TOCSY). The polysaccharides from P. linteus and P. igniarius mainly contained glucose with minor proportions of mannose, galactose, xylose, arabinose and rhamnose. Methylation analyses showed that the glycosidic linkages were mostly 1 → 3, 1 → 6 or 1 → 3,6. The two-dimensional COSY, NOESY and TOCSY confirmed that these polysaccharides have a main chain of →3)-ß-D-Glcp-(1→ with →6)-ß-D-Glcp-(1→ side chain. In vitro assays by RT-PCR and ELISA showed that (1 → 3; 1 → 6)-ß-D-polysaccharides from P. linteus and P. igniarius decreased TNF-α in RAW 264.7 cells, suggesting an immuno-suppressive activity. Furthermore, these polysaccharides stimulated a high IL-10 response and induced strong suppression of transcription of IL-6. The results suggest that polysaccharides from P. linteus and P. igniarius could possibly find applications in restoring the IL-6/IL-10 balance, the disturbance of which is thought to be related to chronic inflammatory disease, obesity, diabetes type 2, and to mania and depression.

Polyphenol extract from Phellinus igniarius protects against acrolein toxicity in vitro and provides protection in a mouse stroke model.

The basidiomycetous mushroom Phellinus igniarius (L.) Quel. has been used as traditional medicine in various Asian countries for many years. Although many reports exist on its anti-oxidative and anti-inflammatory activities and therapeutic effects against various diseases, our current knowledge of its effect on stroke is very limited. Stroke is a neurodegenerative disorder in which oxidative stress is a key hallmark. Following the 2005 discovery by Igarashi's group that acrolein produced from polyamines in vivo is a major cause of cell damage by oxidative stress, we now describe the effects of anti-oxidative extracts from P. igniarius on symptoms of experimentally induced stroke in mice. The toxicity of acrolein was compared with that of hydrogen peroxide in a mouse mammary carcinoma cell line (FM3A). We found that the complete inhibition of FM3A cell growth by 5 µM acrolein could be prevented by crude ethanol extract of P. igniarius at 0.5 µg/ml. Seven polyphenol compounds named 3,4-dihydroxybenzaldehyde, 4-(3,4-dihydroxyphenyl-3-buten-2one, inonoblin C, phelligridin D, inoscavin C, phelligridin C and interfungin B were identified from this ethanolic extract by LCMS and 1H NMR. Polyphenol-containing extracts of P. igniarius were then used to prevent acrolein toxicity in a mouse neuroblastoma (Neuro-2a) cell line. The results suggested that Neuro-2a cells were protected from acrolein toxicity at 2 and 5 µM by this polyphenol extract at 0.5 and 2 µg/ml, respectively. Furthermore, in mice with experimentally induced stroke, intraperitoneal treatment with P. igniarius polyphenol extract at 20 µg/kg caused a reduction of the infarction volume by 62.2% compared to untreated mice. These observations suggest that the polyphenol extract of P. igniarius could serve to prevent ischemic stroke.