The Expression And Significance Of Cannabinoid Receptor 2 In Non-infectious Granuloma And Malignant Melanoma

BackgroundMarijuana as a medicine has been used in China for thousands of years. Cannabinoids and its derivatives which composed the active components of marijuana are anti-inflammatory and have immunosuppressive effect.Two different types of cannabinoid receptors have been found:the cannabinoid receptor 1(CB1) mainly expressed in central nervous system,while the cannabinoid receptor 2(CB2) mostly expressed in the immune system.In recent years,Cannabinoid has been found to inhibit activation of immune cells and regulate the secretion of immune factors after binding to cannabinoid receptors on the surface of immune cells,thus play its role in immune regulation.It is also a pharmacological active substance in inhibiting cells aggregation and proliferation,anti-inflammation,anti-tumor.In non-infectious granulomas,the causes of sarcoidosis or granuloma annulare are still not very clear. The formation of granuloma is related to the aggregation and proliferation of immune cells.So activation of CB2 can inhibit the development of granuloma through supression of immunocyte functions and promotion of apoptosis.It may infer that cannabinoid receptor 2 has played a vital role in the genesis and development of granulomatous diseases.Otherwise,activation of CB2 decreases cell differentiation, proliferation,angiogenesis and metastasis,and increased apoptosis,of cutaneous malignant tumors.Currently,there is an intense renaissance in the study of the effects of cannabinoid receptor 2 focused on the genesis,development and metastasis of cutaneous tumors.ObjectiveTo investigate the expression and its significance of CB2 in human normal skin and non-infectious granuloma,malignant melanoma and discuss its usefulness for early diagnosis and prognosis evaluation of cutaneous non-specific inflammatory granuloma and malignant melanoma. Methodsimmunohistochemical staining was employed to examine the expression profiles of CB2 in human normal skin,malignant melanoma,sarcoidosis and granuloma annulare.ResultsHuman normal skin,malignant melanoma,sarcoidosis and granuloma annulare all expressed CB2.In human normal skin,CB2 was chiefly expressed in basal cell layer,prickle cell layer and horny layer and it can seldom be expressed by subcutaneous tissue.The expression of CB2 was significantly higher(P＜0.05) in sarcoidosis,granuloma annulare and malignant melanoma than human normal skin tissues,moreover,CB2 expression in malignant melanoma was significantly higher than sarcoidosis and granuloma annulare(P＜0.05).CB2 expression of sarcoidosis and granuloma annulare group also showed statistical significances(P＜0.05).ConclusionCB2 can be expressed in normal skin,malignant melanoma,sarcoidosis and granuloma annulare.However,the intensity of expression in normal skin was significantly lower than the other three diseases,and melanoma was the highest,next sarcoidosis,then granuloma annulare.It may be interred that intensive expression of CB2 in these diseases was related to higher cellular proliferation,tendency and aggregation in tissues.Thus CB2 receptor agonists can play an inhibitive role in the origin and development of non-infectious granulomatous disease and tumors by immune regulation.