Anti‑photoaging and anti‑oxidative activities of natural killer cell conditioned medium following UV‑B irradiation of human dermal fibroblasts and a reconstructed skin model.

Conditioned media from various sources comprise numerous growth factors and cytokines and are known to promote the regeneration of damaged tissues. Among these, natural killer cell conditioned medium (NK‑CdM) has been shown to stimulate collagen synthesis and the migration of fibroblasts during the wound healing process. With a long‑term aim of developing a treatment for skin photoaging, the ability of NK‑CdM to prevent ultraviolet‑B (UV‑B) damage was assessed in neonatal human dermal fibroblasts (NHDFs) and an in vitro reconstructed skin model. The factors present in NK‑CdM were profiled using an antibody array analysis. Protein and mRNA levels in UV‑B exposed NHDFs treated with NK‑CdM were measured by western blotting and quantitative reverse transcription‑PCR, respectively. The total antioxidant capacity of NK‑CdM was determined to assess its ability to suppress reactive oxygen species. The anti‑photoaging effect of NK‑CdM was also assessed in a 3D reconstituted human full skin model. NK‑CdM induced proliferation of UV‑B‑treated NHDFs, increased procollagen expression, and decreased matrix metalloproteinase (MMP)‑1 expression. NK‑CdM also exhibited a potent antioxidant activity as measured by the total antioxidant capacity. NK‑CdM inhibited UV‑B‑induced collagen degradation by inactivating MAPK signaling. NK‑CdM also elicited potential anti‑wrinkle effects by inhibiting the UV‑B‑induced increase in MMP‑1 expression levels in a 3D reconstituted human full skin model. Taken together, the suppression of both UV‑B‑induced MMP‑1 expression and JNK activation by NK‑CdM suggests NK‑CdM as a possible candidate anti‑skin aging agent.