Model Description

Imiquimod (IMQ) is a ligand for TLR7 and TLR8 and  it's original use was for the treatment of  non-melanoma skin cancers. The topical application of IMQ on the shaved back skin of the mouse induces a psoriasis-like skin condition exhibiting most of the human psoriasis pathology characteristic features including acanthosis, parakeratosis,  infiltration of immune cells and involvement of the IL23/ IL17/ IL22 pathway. The pathology features regress upon topical application of cortocosteroids.  

Preclinical efficacy evaluation

Study Design

IMQ is applied on the shaved back of the mice daily for 5 consequtive days. Signs of psoriasis appear from day 2 onwards as erythema, scaling and skin thickening. The severity of the signs is daily assessed. The experimental design always includes an uninduced control group (vaseline treated), a negative therapeutic control group (imiquimod-induced without treatment) and a  positive therapeutic control group (corticosteroids).

Read-out parameters
  • Daily body weight measurements reflecting the general health status 
  • Daily in vivo scoring of skin erythema, skin scaling and skin thickness reflecting the progress of the pathology
  • Spleen weight to body weight ratio measured at the end of the study reflecting the disease related immune activation
  • Histopathological scoring at the end of the study recapitulating the pathology status

Figure 1: Representative graphs of in vivo measurments of wild type animals with IMQ-induced psoriasis. Treatment with corticosteroids (Butavate) reverses disease symptoms.

 

Figure 2: Representative graphs of spleen weight to body weight measurements in wild type animals with IMQ-induced psoriasis. Treatment with corticosteroids (Butavate) reverses disease symptoms.

Figure 3: Representative graphs of histopathological assesment of wild type animals with IMQ-induced psoriasis. Treatment with corticosteroids (Butavate) reverses disease symptoms.

 

Vaseline                                                    IMQ                                                            IMQ/Butavate
  

Figure 4: Representative graphs of histopathological images of wild type animals with IMQ-induced psoriasis. Treatment with corticosteroids (Butavate) reverses disease symptoms.