Background/Purpose: Recently, obesity has been known to be associated with psoriasis: obesity has negative effects on the prevalence, severity, and treatment response of psoriasis. High fat diet (HFD) aggravated imiquimod-induced psoriatic inflammation through increase of γδT cells to secrete IL—17A in mice, and obese diabetic mice with psoriasis has prolonged inflammation than control mice. However, systemic inflammation other than skin has not been thoroughly investigated in obesity-associated psoriasis.

Methods: We induced obesity by HFD and psoriasis by imiquimod application in mice. Changes in body weight and fat mass was evaluated by mass spectrometry. Expression of inflammatory cytokines and lesional skin and gonadal fat tissue was evaluated with RT-PCR.

Results: With imiquimod application, there was a noticeable decrease in body weight and fat, which was significantly worse in obese than lean mice. Subcutaneous fat layer was significantly thinner in imiquimod-treated obese mice compared to control obese mice, and the expression of inflammatory cytokines, including IL-1b, was higher in the gonadal fat tissue of imiquimod-treated obese mice. In lesional skin, expression of inflammatory cytokines critical in psoriasis pathogenesis, such as Il-17a, IL-23, and IL-22 were significantly increased in obese psoriasis mice than lean psoriasis mice or obese control mice, consistent with the previous findings of obesity-induced aggravation of psoriasis inflammation.

Conclusion: We found that imiquimod exaggerates obesity-associated adipose tissue inflammation in murine psoriasis model, suggesting that systemic inflammation, such as that in adipose tissue, needs to be considered when evaluating imiquimod-induced psoriatic inflammation in mice.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/imiquimod-exaggerates-obesity-associated-adipose-tissue-inflammation-in-murine-psoriasis-model/