Carrageenan-Induced Acute Inflammation on Back-Skin of Mice: Histopathological Features, Number of Inflammatory Cells, and Expression of COX-2, COX-1, and IL-6

Abstract

Carrageenan is a sulfated polysaccharide obtained from red seaweed (Rhodophyceae) and can trigger inflammatory activation in both humans and laboratory animals. This study aimed to investigate the expression of cyclooxygenase-2 (COX-2), cyclooxygenase-1 (COX-1), and interleukin-6 (IL-6) and the number of inflammatory cells (neutrophil) involved in a carrageenan-induced acute inflammatory model in the back skin of mice. Paraffin blocks from the back skin of female Swiss mice aged 8 weeks were used in this study. The back-skins of 4 groups of 5 mice in each group were subcutaneously injected with 1%, 2%, and 4% carrageenan powder in 0.9% buffer saline and 0.9% buffer saline as control. Skin samples on paraffin blocks were taken 6 hours after carrageenan injection. Furthermore, paraffin blocks were stained with hematoxylin-eosin (HE) to count the number of inflammatory cells. Immunohistochemistry staining using anti-COX-2, COX-1, and IL-6 antibodies was performed to determine the role of inflammatory mediators. The results showed that the number of inflammatory cells (neutrophils) increased significantly following an increase in carrageenan concentrations. The COX-2, COX-1, and IL-6 expressed by inflammatory cells increased significantly at carrageenan concentrations of 1% to 4%. Histopathological features supported the results obtained from the calculation of the number of inflammatory cells and the expression of COX-2, COX-1, and IL-6. The inflammatory markers consisting of COX-2, COX-1, and IL-6 were expressed on the back skin of mice at 6 hours post-injection with 1% to 4% carrageenan. It can be concluded that carrageenan can be used for an acute inflammatory model of the back skin of a mouse. This inflammation model is intended to facilitate the evaluation or measurement of therapeutic and inflammatory responses when test substances are administered topically or transdermal.