Immunomodulatory Effects of Medicinal Mushroom Extracts in the Sensitized Human Keratinocyte Cell Line NCTC2544

Contact dermatitis (CD) is a common skin condition characterized by inflammation caused by exposure to allergens. In Malaysia, it accounts for a significant portion of skin diseases, with irritant contact dermatitis being the most prevalent type. Lignosus rhinocerus and Ophiocordyceps sinensis are medicinal mushrooms known for their immunomodulatory properties and therapeutic potential in autoimmune diseases. This study aimed to investigate the immunomodulatory effects of cold-water extracts from O. sinensis cultivar OCS02Ŵ (xOsTM) and L. rhinocerus TM02Ŵ cultivar (xLrŴ) on p-phenylenediamine (PPD)-sensitized NCTC 2544 keratinocytes, a well-established, non-tumorigenic keratinocyte model commonly used for allergenicity and irritation testing. Cytotoxicity, cytokine expression, reactive oxygen species (ROS) levels, and lipid peroxidation were assessed following extract treatment. The results showed that xLrŴ at 1 mg/mL exhibited no observed adverse effect level (NOAEL), while xOsTM had a half-maximal inhibitory concentration (IC50) of 650 μg/mL in NCTC 2544 keratinocytes. Conversely, PPD, a known sensitizing agent, inhibited NCTC 2544 cell growth, with an IC50 of 17.7 μg/mL. Both xLrŴ and xOsTM (at 250 μg/mL) significantly downregulated ROS levels, membrane lipid peroxidation, and the expression of interleukin (IL)-18 and IL-6 in PPD-sensitized keratinocytes (P < 0.05). This study highlights the anti-inflammatory and cytoprotective properties of xLrŴ and xOsTM, suggesting their potential application in managing inflammatory conditions in PPD-sensitized keratinocytes. Furthermore, their immunomodulatory effects on cytokine production indicate a promising role in alleviating diseases associated with chronic inflammation and immune dysfunction. In conclusion, xLrŴ and xOsTM may have therapeutic potential as immunomodulatory agents for treating CD.