Encyclopedia of Experiments: Immunology
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Transcript
Malassezia, an opportunistic pathogenic fungus, resides on the mouse's epidermis — the outermost skin layer. When the skin barriers are compromised, it can penetrate the epidermis, triggering inflammation.
To evaluate Malassezia-induced skin inflammation, prepare an anesthetized mouse with wounded ear skin, resulting in a disrupted epidermis.
Measure the thickness of the ears and apply Malassezia oil suspension onto the wounded ears. The oil helps Malassezia's absorption in the skin, while the wound allows fungi to enter the epidermis, causing an infection.
Within the epidermis, pattern recognition receptors on Langerhans cells and keratinocytes interact with the fungal cell wall constituents. Upon interaction, these cells release pro-inflammatory cytokines, which diffuse through the dermis and dilate the dermal blood vessels. This promotes leukocyte infiltration and fluid accumulation at the infection site, causing tissue edema and swelling of the ears. Increased thickness of the ears correlates with inflammation.
Dissect the ear and homogenize to release intracellular contents, including Malassezia. Spread the homogenized suspension on an agar plate with a growth medium and incubate. This allows individual fungi to grow into distinct colonies.
The number of colonies on the plate reflects the fungal burden from skin inflammation.
