Establishment of an Intradermal Ear Injection Model of IL-17A and IL-36γ as a Tool to Investigate the Psoriatic Cytokine Network

• Published in: Life (Basel, Switzerland) Vol. 11; no. 8; p. 846
• Main Authors: Kluwig, David, Huth, Sebastian, Abdallah, Ali T., Pfaff, Carolina M., Fietkau, Katharina, Huth, Laura, Marquardt, Yvonne, Baron, Jens M., Lüscher, Bernhard
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 19.08.2021; MDPI
• Subjects: Animals; Antibodies; Antiinfectives and antibacterials; Antimicrobial peptides; Attractants; Cytokines; Ear; ear injection; Experiments; Gene expression; Genotype & phenotype; IL-17A; IL-36γ; Inflammation; Injection; Leukocytes (neutrophilic); mouse model; Neutrophils; Peptides; Psoriasis; Sample size; Skin; Skin diseases; Thickness measurement; Tumor necrosis factor-TNF; United States > US; Germany
• ISSN: 2075-1729; 2075-1729
• DOI: 10.3390/life11080846

Psoriasis is a chronic skin disease affecting 2–3% of the global population. The proinflammatory IL-17A is a key cytokine in psoriasis. Accumulating evidence has revealed that IL-36γ plays also a pathogenic role. To understand more precisely the role of the IL-17A–IL-36γ cytokine network in skin pathology, we used an ear injection model. We injected IL-17A or IL-36γ alone and in combination into the ear pinnae of mice. This resulted in a significant increase in ear thickness measured over time. Histological evaluation of IL-17A + IL-36γ-treated skin showed a strong acanthosis, hyperparakeratosis and infiltration of neutrophils. The same histological features were found in mice after injection of IL-36γ alone, but to a lesser extent. IL-17A alone was not able to induce psoriasis-like changes. Genes encoding proteins of the S100 family, antimicrobial peptides and chemo-attractants for neutrophils were upregulated in the IL-17A + IL-36γ group. A much weaker expression was seen after the injection of each cytokine alone. These results strengthen the hypothesis that IL-17A and IL-36γ drive psoriatic inflammation via a synergistic interaction. Our established intradermal ear injection model can be utilized in the future to monitor effects of various inhibitors of this cytokine network.