Anti-inflammatory effects of sacran, a novel polysaccharide from Aphanothece sacrum, on 2,4,6-trinitrochlorobenzene-induced allergic dermatitis in vivo

Background: Sacran is a newly discovered sulfated polysaccharide extracted from an algae, Aphanothece sacrum, grown in a river of the Kyushu region in Japan. Objective: To evaluate sacran's inhibitory effect in 2,4,6- trinitrochlorobenzene (TNCB)induced allergic dermatitis in NC/Nga mice. Methods: Sacran was extracted by acid and alkaline treatment of A sacrum cyanobacterial biomaterials. To sensitize mice, 150 μL of 5% TNCB was applied epicutaneously on the abdomen of each mouse on day 1 and challenged with 15 μL of 1% TNCB applied on the ear skin of mice on day 8 and then every other day to induce skin lesions. Serum levels of inflammatory markers were measured and histopathologic examination of ear skin specimens performed. On the other hand, sacran's transepidermal water loss was evaluated in 11 volunteer women with dry skin. Results: Epicutaneous application of sacran in mice has significantly inhibited the development of allergic dermatitis skin lesions and reduced the number of scratching behavior episodes (P <.01). In addition, sacran efficiently inhibited IgE (P <.001), tumor necrosis factor α (P =.02), interleukin 4, interleukin 5, and interferon γ (P <.01; vs buffer in the TNCB group) production and eosinophilic infiltration in the chemical allergenexposed ear skin. In addition, sacran-treated body regions of human volunteers with dry skin significantly reduced transepidermal water loss levels compared with exogenous hyaluronic acid (P <.01), which is known to improve skin moisture and exert skin barrier repair activity. Conclusions: This study suggests that sacran exerts anti-inflammatory effects by improving skin barrier function and reducing T_H2 cytokine production.