Li Rui, Rodrigues MyriamRubecca, Li Lijuan, Winget Jason, Wang Yu, Wang Caroline, Smith Ed, Wei Karl
Beauty Revealed, Procter & Gamble International Operations SA SG Branch, Singapore, Singapore.
Corporate Functions Analytical, Procter & Gamble Mason Business Center, Cincinnati, OH, USA.
Clin Cosmet Investig Dermatol. 2023 Jun 22;16:1595-1606. doi: 10.2147/CCID.S409534. eCollection 2023.
The skin has evolved a system to prevent pathogenic microorganism colonization and infection. This study examined the role of natural moisturizing factors (NMFs) and skin pH on () growth and colonization on the human stratum corneum (SC).
A survey study with 82 female participants was performed. Participants maintained their daily hygiene routine, except for refraining from using leave-on products on their forearms on the day of the test. Skin sampling was performed using adhesive tapes. An ex vivo method was developed to study the viability and growth of on human SC sampled from normal skin. NMFs, including pyrrolidone carboxylic acid (PCA), urocanic acid (UCA), histidine, and proline in SC samples, were measured by liquid chromatography with tandem mass spectrometry. The impact of PCA and UCA on growth and metabolic activity was measured by optical density and isothermal microcalorimetry, respectively.
Heterogeneity of viability on human SC samples was observed. Skin pH showed a significant negative association (p<0.05) with SC antibacterial activity in the ex vivo assay. One unit of skin pH decrease corresponded to 68.1% of cell death. The levels of PCA and histidine were significantly negatively associated (p<0.05) with skin pH. The addition of 5 mM and 10 mM PCA significantly inhibited growth by approximately 25% at 20 hours and reduced its metabolic activity in vitro.
The results indicate that PCA, one of the NMFs in human skin, plays an important role in regulating the human skin acid mantle in vivo and contributes to antibacterial activity against .
皮肤已经进化出一种系统来防止病原微生物的定植和感染。本研究探讨了天然保湿因子（NMFs）和皮肤pH值对人类角质层（SC）上（）生长和定植的作用。
对82名女性参与者进行了一项调查研究。参与者保持日常卫生习惯，但在测试当天避免在前臂上使用免洗产品。使用胶带进行皮肤采样。开发了一种体外方法来研究从正常皮肤采集的人类SC上（）的活力和生长情况。通过液相色谱-串联质谱法测量SC样本中的NMFs，包括吡咯烷酮羧酸（PCA）、尿刊酸（UCA）、组氨酸和脯氨酸。分别通过光密度和等温微量热法测量PCA和UCA对（）生长和代谢活性的影响。
观察到人类SC样本上（）活力的异质性。在体外试验中，皮肤pH值与SC抗菌活性呈显著负相关（p<0.05）。皮肤pH值每降低一个单位，对应（）细胞死亡68.1%。PCA和组氨酸的水平与皮肤pH值呈显著负相关（p<0.05）。添加5 mM和10 mM PCA在20小时时显著抑制（）生长约25%，并降低其体外代谢活性。
结果表明，PCA作为人类皮肤中的一种NMFs，在体内调节人类皮肤酸性保护膜中起重要作用，并有助于对（）的抗菌活性。
