[Differences of water barrier function between keloid and its surrounding normal skin in patients with keloids and...

Objective: To compare the differences of water barrier function between keloids and its surrounding normal skin in patients with keloids, and to explore the primary mechanism. Methods: A cross-sectional observational study was conducted. From October 2020 to March 2021, 30 patients with keloids who met the inclusion criteria visited Shanghai 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 keloids and the surrounding normal skin of the 30 patients were measured by multi probe adapter on the reception day. The keloid tissues and normal skin of 5 patients after keloid repair surgery were processed for hematoxylin-eosin staining to measure the thickness of epidermis. Immunohistochemistry was performed on samples from 3 of those 5 patients to detect the expressions of cytokeratin-10, involucrin, and filaggrin in keloids 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 keloids of 30 patients was 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, between which the difference was not statistically significant (t=0.44, P>0.05). After keloid repair surgery, the thickness of epidermis in the keloids of 5 patients was (194±44) μm, which was significantly thicker than that of the normal skin (44±11) μm, (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. After keloid repair surgery, the expression level of cytokeratin-10 in keloids was significantly lower than that in normal skin of 3 patients (t=8.50, P<0.01), but there were no statistically significant differences in the expression levels of involucrin or filaggrin between keloids and normal skin (with t values of 0.07 and 0.96, respectively, P>0.05). Conclusions: Keloid tissue from patients with keloids displays increased number of keratinocytes and thickened epidermis. But the water barrier function in keloid area is similar to the surrounding normal skin, suggesting that TEWL may not be the main mechanism lead to the persistent development of keloids.