Lactobacillus plantarum L-137 upregulates hyaluronic acid production in epidermal cells and fibroblasts in mice

Heat-killed Lactobacillus plantarum L-137 (HK L-137), an immunobiotic lactic acid bacterium, has been reported to enhance IFN-gamma production through induction of IL-12. In this study, we investigated the effects of HK L-137 on skin moisturizing and production of hyaluronic acid (HA), an extracellular matrix associated with the retention of skin moisture. Oral administration of HK L-137 suppressed the loss of water content in the stratum corneum in hairless mice. Treatment of primary epidermal cells with HK L-137 increased HA production. Supernatant from immune cells stimulated by HK L-137, which contained proinflammatory cytokines such as IL-12, TNF-alpha, and IFN-gamma, upregulated HA production and hyaluronan synthase 2 (HAS2) messenger RNA expression by BALB/3T3 fibroblasts via activation of transcription factor nuclear factor kappa B (NF kappa B). Although treatment of the supernatant with anti-TNF-alpha antibody (Ab) alone did not inhibit the HA production, combination of anti-TNF-alpha Ab with anti-IFN-gamma Ab significantly inhibited the HA production. Thus, HK L-137-induced IFN-gamma plays a critical role in upregulated HA production in collaboration with TNF-alpha. HK L-137 may be useful for improvement of skin functions such as moisture retention by inducing HA production.