Pinus koraiensis needle or cone extracts alleviate atopic dermatitis symptoms by regulating immunity and suppressing inflammation in HaCaT cells and Nc/Nga mice

Pinus koraiensis needles (PKN) and cones (PKC) have been shown to protect against inflammation and pathogenic bacteria. We investigated the efficacies and action mechanisms of topical applications of 1,3-butylene glycol (BG) extracts and oral administration of their water extracts on atopic dermatitis (AD) symptoms. After exposing HaCaT cells and Nc/Nga mice dorsal skins to 2,4-dinitrochlorobenzene (DNCB) to induce atopic dermatitis models, they were topically applied BG (AD-control), 30% PKNX, or 30% PKCX to the skin lesions and fed water extracts (0.5%) in high-fat diets for 5 weeks. Normal-control mice had no DNCB exposure. Serum immunoglobulin E (IgE), IL-4, and TNF-α levels and gene expressions of TNF-α, IL-4, IL-6, and IFN-γ in the dorsal skin and HaCaT cells were measured. The AD-control mice elevated TNF-α and IL-6 mRNA levels in HaCaT cells. Both extracts attenuated clinical AD symptoms in AD-induced Nc/Nga mice: PKNX improved hemorrhage, erythema, and lichenification of dorsal skin better than PKCX while both similarly alleviated erythema, edema, excoriation, and itching behavior. PKCX reduced IgE contents and increased filaggrin mRNA expression better than PKNX, but PKNX reduced lipid peroxides and mRNA levels of TNF-α and IL-4 in the dorsal skin. In the histological analysis of the dorsal skin, the administration of both extracts significantly decreased mast cell numbers, immune cell infiltration, gaps between the epidermis and dermis, and abnormal cell and nucleus shapes. In conclusion, both PKCX and PKNX treatment alleviated the DNCB-induced clinical symptoms of AD by alleviating immune-related symptoms and inflammation in partially different pathways. Therefore, PKNX and PKCX may be effective for AD therapy. Practical applications Atopic dermatitis (AD) is related to an overly activated immune response, and it has steadily increased last 3 decades. However, no optimal sustainable treatments are available. Pinus koraiensis needles and cones extracts have been used for anti-inflammatory and antimicrobial treatment. The present study demonstrated that their intake and topical administration onto the AD lesion alleviated clinical AD symptoms associated with reduced proinflammatory cytokines, mast cell numbers, and immune cell infiltrates to maintain dermal structure with maintaining filaggrin expression in AD-induced HaCaT cells and Nc/Nga mice. These results suggested that Pinus koraiensis needles and cones extracts can be developed and applied as beneficial alternative therapies for AD.