Activation of RAW264.7 macrophages by an acidic polysaccharide derived from Citrus grandis 'Tomentosa'.

Citrus grandis 'Tomentosa' which is a special Citrus cultivar, has been employed as cough suppressant and expectorant in traditional Chinese medicine for thousands of years. The aim of this study is to investigate the immunomodulatory role of an acidic polysaccharide (designated as CGTP-AP) purified from C. grandis 'Tomentosa'. CGTP-AP showed effective immune activation in RAW264.7 macrophages at the concentration of 1-100 μg/mL. CGTP-AP could promote the release of NO in dose- and time-dependent manners. Enzyme-Linked Immunosorbent Assay (ELISA) and RT-PCR analysis demonstrated that CGTP-AP could stimulate the secretion of TNF-α and IL-6 in a dosage-dependent way. Western blot analysis and RT-PCR analysis indicated that CGTP-AP treatment could induce the iNOS and COX-2 expression in RAW264.7 macrophages. By conducting the inhibitors experiments, the activation of NF-κB and MAPK signaling pathways by CGTP-AP treatment was confirmed. Therefore, the present results declared that CGTP-AP could be a promising candidate as a potent immunomodulator for the application in future pharmaceutical development.