Effects of Overload on Imiquimod‐Induced Psoriasis Model Mice: A Basic Experimental Study

Background and Aim: Psoriasis is a skin disorder complicated by arthritis and enthesitis. The cytokines interleukin (IL)-17, IL-23, and tumor necrosis factor (TNF)-α are reportedly key effectors of psoriasis. Additionally, gamma delta (γδ) T cells exacerbate inflammation by producing inflammatory cytokines such as IL-17 and TNF-α. However, details regarding the mechanisms linking pathogenesis and mechanical stress remain unclear. This study aimed to investigate the effect of strenuous exercise on the pathology of psoriasis using mouse models of imiquimod (IMQ)-induced psoriasis.
Methods: Twenty mice were randomly assigned to four groups: IMQ − TRED− (control), IMQ − TRED+ (treadmill running mice), IMQ + TRED− group (IMQ treated mice), and IMQ + TRED+ group (IMQ treated and treadmill running mice). The tissue sections from back skin and thymus were immunostained with antibodies against IL-17, IL-23, and γδ T cells. Shoulder sections were stained using hematoxylin and eosin, and Toluidine Blue and Picrosirius Red. Additionally, the shoulder tissue sections were immunostained with antibodies against TNF-α and matrix metalloproteinase (MMP)-13. Serum cytokine level was measured to evaluate systemic inflammation.
Results: Strenuous exercise exacerbated pathological changes associated with psoriasis, including increased γδ T cell infiltration and upregulated IL-17 and IL-23 expression in the skin, as well as enhanced γδ T cell development and IL-17 expression in the thymus. Although strenuous exercise did not further worsen the modified PASI scores, histological and immunological markers of inflammation were significantly enhanced. Serum levels of TNF-α and IL-17 were significantly elevated in IMQ-induced psoriasis model mice. Moreover, pathological changes induced by strenuous exercise were observed in the enthesis, including angiogenesis and upregulated expression of TNF-α and MMP-13.
Conclusion: This study revealed that strenuous exercise exacerbates pathological changes in IMQ-induced psoriasis model mice.