Study of the correlation between the expression of angiotensin Ⅱ and its receptors and collagen deposition in human keloid

Abstract

Objective: To study the correlation between the expression of angiotensin Ⅱ, angiotensin Ⅱ type 1 receptor (AT1R), angiotensin Ⅱ type 2 receptor (AT2R) and collagen deposition in human keloid. Methods: The keloid from 19 keloid patients and normal skin from 13 patients performed with free skin transplantation hospitalized in our unit from May 2014 to January 2015 were obtained. The expressions of angiotensin Ⅱ, AT1R, and AT2R were detected by immunohistochemical staining, and the results were semi-quantitatively analyzed by immunohistochemical scoring. The expression of collagen in keloid was detected by picrosirius-red staining, and the percentage of total collagen was calculated. Data were processed with t test. The expressions of angiotensin Ⅱ, AT1R, AT2R and the total content of collagen of 13 keloid patients were analyzed by Pearson correlation analysis. Results: (1) There was negative or probably positive expression of angiotensin Ⅱ in normal skin tissue, mainly distributed in the epidermal basal layer. The expression of angiotensin Ⅱ was strong in keloid, most distributed in spinous layer and basal layer of epidermis and most region of dermis, and was strongly positive in most cells, and most cells were fibroblasts. The expressions of AT1R and AT2R were similar to angiotensin Ⅱ in two types of tissue. The expressions of angiotensin Ⅱ, AT1R, and AT2R in keloid scored (305±34), (281±32), and (285±25) points, respectively, which were significantly higher than those in normal tissue [respectively (54±17), (89±47), and (97±32) points, with t values from 12.03 to 23.21, P values below 0.01]. (2) The total content of collagen in keloid was (88±4)%. There was a lot of thick and dense type Ⅰcollagen in keloid, with massive structure and distributed like bamboo segment and arranged in disorder. The expression of type Ⅲ collagen was increased, which was distributed scatteredly around type Ⅰcollagen. (3) There were positive correlations between the expressions of angiotensin Ⅱ, AT1R, AT2R and the total content of collagen in keloid (with r values from 0.452 to 0.720, P values below 0.05). Conclusions: The expressions of angiotensin Ⅱ, AT1R, and AT2R were abnormally increased in human keloid, which may play an important role in the collagen deposition of keloid.