Investigation of the therapeutic effect of systemic carvacrol in i̇miquimod-induced rat psoriasis model

Psoriasis is a chronic, inflammatory skin disease characterized by erythematous, scaly plaques on the skin which affects approximately 2% of the population. The pathogenesis of psoriasis has a complex mechanism and is still an area of research. In psoriasis; the difficulty of applying topical agents, the side effects of conventional treatments, the high cost of biological agents and the chronic nature of the disease increase the burden of psoriasis on both patients and states. In this study; we aimed to investigate the therapeutic effect of systemic carvacrol using histopathological, immunohistochemical, biochemical and clinical parameters in rats with psoriasis model induced with 5% imiquimod cream. In the study, 49 rats were randomly divided into 7 groups and all groups had 7 rats. A psoriasis model was created by applying 5% imiquimod cream to the back of all rats except the negative control group for 7 days. At the end of the seventh day, a group in which psoriasis model was created and a negative control group which did not undergo any treatment were compared using histopathological, immunohistochemical, biochemical and clinical parameters to confirm the psoriasis model. In the remaining groups, respectively 100mg/kg/day saline (SF), 20mg/kg/day carvacrol, 2mg/kg/week methotrexate, 100mg/kg/day 5% DMSO and 20mg/kg/day carvacrol together with 2mg/kg/week methotrexate was administered intraperitoneally for one week. At the end of the study, the data obtained from the groups were compared using histopathological, immunohistochemical, biochemical and clinical parameters. xv At the end of the seventh day, hyperkeratosis, parakeratosis, thinning of the granular layer, acanthosis, elongation of the rethes, epidermal thickness and TNF-α findings were found to be significantly higher in the psoriasis group compared to the negative control group. Apart from these findings, which are parallel to the literature, significantly more folliculitis and dermoepidermal separation were observed in the psoriasis group compared to the negative control group. These findings confirmed the psoriasis model formation. In carvacrol group parakeratosis, acanthosis, inflammation values and 14th day PASI values were found to be significantly lower compared to the SF group. In DMSO group hyperkeratosis, acanthosis, elongation of the retes, and epidermal thickness values were found to be significantly lower compared to the SF group. In our study; in histopathological and clinical parameters 20 mg/kg carvacrol, in histopathological parameters 5% DMSO caused a greater decrease compared to the reference drug methotrexate. In the group in which carvacrol and methotrexate were used together, it caused less decrease in histopathological parameters and TNF-α levels compared to the group in which only carvacrol was used. OSI values were found to be significantly higher in the psoriasis group compared to the negative control group. TAS, TOS, OSI levels in tissue samples and TT, SS, SH levels in serum samples did not differ significantly between the groups. In conclusion, the data obtained from our study show that systemically administered carvacrol and DMSO are molecules that can be effective in the treatment of psoriasis lesions.