Animal Model of Skin Disease

The skin is composed of two parts, the epidermis and the dermis, which are connected to the deep tissue by the subcutaneous tissue. In addition, there are epidermis-derived skin appendages on the skin, such as hair, nails, and sweat glands.

The skin accounts for 6%-16% of the total body weight and is the heaviest organ in the human body. The skin is in direct contact with the external environment, and can feel the cold, heat, pain, and pressure of the external environment. At the same time, it has an important barrier function, which can prevent the evaporation and loss of body fluids and defend against the invasion of external harmful substances. In addition, the skin also has functions such as regulating body temperature and excreting waste.

Today, I will give you a brief introduction to the animal models of solar dermatitis and psoriasis.

Solar Dermatitis Animal Model

Solar dermatitis, also known as sunburn, is an acute phototoxic dermatitis in which erythema, edema, etc. appear locally on the skin after intense sunlight exposure.

The animals were irradiated with a solar UV simulator to produce dermatitis, which was used to simulate solar dermatitis in humans.

1. Both male and female guinea pigs can be used, and the weight is about 300g. Use an electric clipper to remove the hair on the back of the guinea pig to form a hairless area of about 3cm, and apply a depilatory cream.

2. After cleaning, the guinea pigs were irradiated with long-wave ultraviolet (UVA, 320-400nm), a solar ultraviolet simulator, at a dose of 14J/cm2, for a total of 20 weeks, of which the first 10 weeks were irradiated every other day, 2h each time. After 10 weeks, the patients were irradiated 5 days a week, 2 hours each time.

3. Chronic light damage can cause wrinkles, rough skin and hypertrophy of the exposed parts. The pathological changes of the skin include disordered arrangement of epidermal cells, deformation of elastic fibers and juvenile collagen fibers.

After modeling, it was judged according to the degree of erythema and edema in the skin of the experimental area. The more severe the clinical symptoms, the higher the score.

1.point is no response;

2. is divided into mild erythema, no redness and swelling;

3. points are moderate erythema, mild edema;

4. points for severe erythema, moderate edema

Psoriasis Animal Model

Psoriasis, commonly known as psoriasis, is a clinically common chronic, recurrent, inflammatory skin disease. Psoriasis is caused by poor skin appearance and severe itching, which can seriously affect the quality of life of patients.

The etiology and pathogenesis of psoriasis have not yet been fully elucidated. It is generally believed that it is related to genetic factors, infection, metabolic disorders, immune dysfunction, and mental factors.

Psoriasis is a skin disease characterized by excessive proliferation of epidermal cells. The pathological manifestations are hyperkeratosis with parakeratosis, micro abscesses, obvious reduction or disappearance of the granular layer, thickening of spinous cells, and epidermal processes extending downward into spike-like processes; the top of the dermal papilla is club-like, and the spinous layer above it is degenerated. Thin, telangiectasia and congestion, and infiltration of lymphocytes and neutrophils can be seen around.

1. IMQ-mouse model:

Apply 5% Quirin Model Cream (IMQ) at a dose of 50mg/cm2 evenly to the depilation area, once a day for 7 days. In general, 2-3 days after application, the skin on the back of the mice thickened, and erythema and dandruff appeared. The skin on the back of the mice further thickened, with increased erythema and dandruff over time.

2. Propranolol-guinea pig model:

The application of propranolol to the skin of guinea pigs caused hyperkeratosis, parakeratosis, acanthosis, and polymorphonuclear cell infiltration in the stratum corneum, which resembled human psoriasis histological changes. Using cotton swabs to apply propranolol liniment (0.3g/cm2) to the bilateral ears of guinea pigs, every 2 days for 2 consecutive weeks, to create a model of ear skin psoriasis. This model is identical to human psoriatic skin lesions not only histopathologically, but also at the molecular level.

3. Gene-immune model:

Transgenic mice are animal models in which exogenous genes are introduced artificially. Transgenic models of psoriasis can overexpress different cytokines (such as IL-1, IL-6, IL-8, and TNFα) in the epidermis, resulting in changes in keratinocyte function and psoriasis-like manifestations. But these models are generated by manipulating a single gene, and psoriasis is a polygenic disease, because it is impossible to get a perfect psoriasis model by knocking out a gene, that is, it cannot fully reproduce the clinical and histological characteristics of psoriasis of various characteristics.

Medicilon's Psoriasis Animal Model

Medicilon establishes diverse models that captures key features of psoriasis, including:

• IL-23 induced auricle epidermal dysplasia mice models

• Estrogen induced vaginal epithelium mitosis mice models

• Imidocriptine induced mice models

• Tail scales mice models