[Differences of water barrier function between keloid and normal skin of keloid patients and its related mechanism].

Objective: To compare the differences of water barrier function of skin between keloid and surrounding normal skin in keloid patients and to explore the primary mechanism. Methods: A cross-sectional observational study was conducted. From October 2020 to March 2021, 30 keloid patients who met the inclusion criteria visited the Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, including 18 females and 12 males, aged 20-48 years. The transepidermal water loss (TEWL) of their keloid tissues and the surrounding normal skin of the 30 patients were measured by multi probe adapter on the reception day. Hematoxylin-eosin staining was performed on keloid skin and normal skin of 5 patients after scar repair surgeries to measure the thickness of epidermis. Immunohistochemistry was used on samples from 3 patients to detect the expressions of cytokeratin-10, involucrin, and filaggrin in epidermis of keloid skin and normal skin. Data were statistically analyzed with paired sample t test and independent sample t test. Results: On the reception day, the TEWL of keloid skin of 30 patients is 9.0 (6.9, 13.4) g·m-2 ·h-1 and the TEWL of the normal skin was 8.1(6.4, 18.1) g·m-2 ·h-1 , which showed no statistically significant differences ( t =0.44, P >0.05). The thickness of epidermis in the keloid skin of 5 patients was (194±44) μm, which was significantly greater than (44±11) μm of the normal skin ( t =6.88, P <0.01). Furthermore, increased keratinocytes, lack of normal epidermal ridge structures, and thickened stratum corneum were observed in the keloid area. The expression level of cytokeratin-10 in epidermis in the keloid skin was significantly lower than that in normal skin ( t =8.50, P <0.01), but there were no statistically significant differences in the expression levels of involucrin and filaggrin between epidermis in the keloid skin and normal skin (with t values of 0.07 and 0.96, respectively, P >0.05). Conclusions: Keloid tissues present increased keratinocytes and thickened epidermis. But their water barrier function is similar to the surrounding normal skin, suggesting that transdermal water loss may not play a critical role in the prolonged development of keloids.