[Expression of endosialin in human hypertrophic scars and its regulation on fibroblast phenotype]

Objective: To explore the expression of endosialin, i.e., CD248 in human hypertrophic scars (HSs) and its regulatory effect on the phenotype of hypertrophic scar fibroblasts (HSFs). Methods: The method of experimental research was used. From March to May, 2023, 3 pediatric patients with HS were admitted to the Department of Burns and Cutaneous Surgery of the First Affiliated Hospital of Air Force Medical University, including 2 females and 1 male, aged one year ten months to two years. The HS tissue resected during the surgery and the remaining full-thickness skin graft, i.e., normal skin tissue after full-thickness skin grafting were collected from the aforementioned pediatric patients for subsequent experiments. Using the aforementioned two types of tissue, the histological structures were observed by hematoxylin-eosin staining, collagen distribution was observed by Masson staining, and the expression of CD248 was observed and measured by immunohistochemical staining. The primary HSFs were isolated from HS tissue using explant culture technique, and the 3^rd to 5^th passages of HSFs were used in subsequent experiments. According to the random number table, HSFs were divided into immunoglobulin G78 (IgG78)-treated group and IgG control group, which were treated with 200 nmol/L human CD248 monoclonal antibody IgG78 and human IgG control antibody for 24 h, respectively. The mRNA expressions of collagen type Ⅰ (Col Ⅰ) and α-smooth muscle actin (α-SMA) in HSFs were measured by real-time fluorescence quantitative reverse transcription polymerase chain reaction, the protein expressions of Col Ⅰ and α-SMA in HSFs were detected by Western blotting, and the intracellular location and protein expressions of Col Ⅰ and α-SMA were detected by immunofluorescence method. The number of samples in each experiment was 3. Data were statistically analyzed with paired sample t test and independent sample t test. Results: Compared with those in normal skin tissue, the epidermis and dermis in HS tissue were significantly thicker, with massive accumulation and disordered arrangement of collagen in the dermis. The expression of CD248 in HS tissue was significantly upregulated compared with that in normal skin tissue (t=5.29, P<0.05). At post treatment hour 24, the mRNA expressions of Col Ⅰ and α-SMA of HSFs in IgG78-treated group were 0.39±0.05 and 0.56±0.09, respectively, which were significantly lower than 1.00±0.07 and 1.00±0.08 in IgG control group, respectively (with t values of 11.87 and 6.49, respectively, P values all <0.05). The protein expressions of Col Ⅰ and α-SMA of HSFs in IgG78-treated group were 0.617±0.011 and 0.67±0.14, respectively, which were significantly lower than 1.259±0.052 and 1.23±0.16 in IgG control group, respectively (with t values of 20.92 and 4.52, respectively, P values all <0.05). At post treatment hour 24, immunofluorescence staining showed that Col Ⅰ and α-SMA mainly located in the cytoplasm of HSFs in the two groups, and the protein expressions of Col Ⅰ and α-SMA of HSFs in IgG78-treated group were obviously downregulated compared with those in IgG control group. Conclusions: The expression of CD248 is significantly upregulated in human HS. Targeted blockade of CD248 can significantly inhibit the collagen synthesis by HSFs and the transdifferentiation of HSFs into myofibroblasts.