Establishment of Psoriasis Mouse Model by Imiquimod

Summary

Here, we present a highly efficacious and stable mouse model of psoriasis established through the utilization of imiquimod. Additionally, we detail the methodologies employed to assess the severity of psoriasis.

Abstract

Psoriasis is a common, chronic, relapsing, and inflammatory skin condition characterized by thickened skin infiltration, scales, and erythema. The pathogenesis of the disease is highly complex, involving the interplay of various factors such as genetics, immunity, and environmental factors. To investigate the mechanisms underlying psoriasis, researchers have developed multiple animal models of the disease. However, the variability in methodologies has presented challenges for constructing these models consistently. In this study, we established and comprehensively evaluated a highly efficient and stable psoriasis mouse model using imiquimod (IMQ). 8-week-old SPF-grade female C57BL/6J mice were used to establish the psoriasis mouse model. After one week of acclimatization, mice with irritated or damaged skin in the depilated areas were excluded. Starting on day two, 5% IMQ cream (62.5 mg/d) was applied daily to the depilated neck and back regions for seven consecutive days. During the experiment, daily measurements of body weight, skin photography, skin scoring, and behavioral observations were conducted. Post-experiment, spleen index determination, skin histological analysis, serum cytokine detection, and skin mRNA level detection were performed. The results showed that mice in the IMQ group developed typical psoriasis-like symptoms, including erythema, scales, and skin thickening, accompanied by increased scratching behavior, weight loss, elevated spleen index, and increased skin thickness. And significant changes in the levels of TNF-α, IL-23, and IL-17A in serum, as well as the mRNA levels of IL-23, IL-17A, IL-17F, and IFN-γ in the skin. Serum cytokine levels (TNF-α, IL-23, IL-17A) and skin mRNA expression of pro-inflammatory markers (IL-23, IL-17A, IL-17F, IFN-γ) were notably upregulated. In contrast, the control group exhibited no such alterations. By optimizing the IMQ induction duration and standardizing the administration protocol, while dynamically monitoring skin changes, this study aims to provide a standardized framework for researchers to construct reliable psoriasis models.

Introduction

Psoriasis is a common, chronic, relapsing, and inflammatory systemic skin disease, with plaque psoriasis being the most predominant clinical manifestation¹. Its clinical characteristics typically include skin infiltration, thickness, scales, and erythema², and it can also trigger a variety of complications, including psoriatic arthritis, depression, metabolic syndrome, and cardiovascular diseases¹. Additionally, psoriasis is often accompanied by chronic pruritus³. Globally, psoriasis impacts 2% to 3% of the population⁴, and its incidence is on the ri....

Protocol

The animal use protocol listed below has been reviewed and approved by the Guangxi University of Chinese Medicine Institutional Welfare and Ethical Committee (DW20191220-153). The animal certificate of the purchased mice was SCXK (Xiang) 2024-0009. In this study, 8-week-old C57BL/6J female mice, SPF grade, were randomly divided into groups, each group containing 6 mice. The cage is placed in a temperature-controlled room (23 ± 2 °C, 12 h light/dark cycle) with free access to food and water. The flow chart of the experiment is shown in Figure 1. Except for not being induced with IMQ cream, the mice in the control group received t....

Results

After continuous administration of IMQ, mice in the IMQ group displayed back skin clinical symptoms reminiscent of psoriasis (Figure 4), with the IMQ-induced area presenting the typical symptoms of erythema, scales, and thickness (Figure 5). In contrast, the control group did not exhibit any symptoms akin to those of the IMQ group. Compared to the control group, erythema and minor scales began to emerge in the IMQ group from day 3 (Figure 5A.......

Discussion

Our research utilizes IMQ to induce psoriasis-like skin lesions, thereby constructing a psoriasis model. This model can be used to study the mechanisms underlying the development of Psoriasis and to provide insights for the development of treatments for the condition. In the study by van der Fits⁷, when initially administering IMQ induction, the induction time was set at either 5 or 6 days. Nevertheless, Jabeen et al. suggested that the severity of IMQ-induced psoriasis models would reach a maximu.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
5% Imiquimod Cream	Sichuan Medshine Pharmaceutical Co.	40220602
75% Ethanol	XUE HUAN	20240401
Analytical Balance	sartorius	SQP
Depilatory Cream	Reckitt Benckiser	20240612 08X
Electronic Scale	Yingheng Technology	7915
Medical Tissue Paper	JD	20221208
Shaver	HORD shenjian	AUX-C6S
Sterilized Cotton Swab	Beilun River	20230728