Psoriatic inflammation in primary human keratinocytes
In this open innovation assay primary human keratinocyte are stimulated using a psoriasis-specific cytokine cocktail which induces an inflammatory response measured as an increase in IL-8 secretion.
Psoriasis is a chronic, immune-mediated and inflammatory disorder affecting about 3 percent of the world’s population (1). Symptoms include skin lesions, inflammatory plaques and silvery scaling due to keratinocyte hyperproliferation. Key disease mediators include TNF-alpha and IL-17 driving a local inflammatory response in skin (2). This open innovation assay models that process and provides an in vitro system capable of testing for compounds' ability to inhibit psoriasis-driving mechanisms.
Figure. IL-17 and TNF-alpha is used to induce a psoriasis-like inflammatory response in primary human keratinocytes. The test compound's ability to inhibit the IL-8 release is measured as well as the effect on the cell viability.
Assay protocol outline
Primary human keratinocyte are seeded in 384 well plates (3500 cells/well) and incubated for one day. Subsequently, the cells are stimulated with a psoriasis relevant cytokine cocktail containing TNF-alpha and IL-17 which induce an inflammatory response measured as an increase in IL-8 secretion. Test compounds are tested for ability to inhibit this inflammatory response. Cellular viability is actively assessed and used to detect general compound cytotoxicity.
The blue curve in figure illustrates the potent effect of the steroid Betamethasone inhibiting the detectable levels of IL-8 by 50% efficacy (Emax). Calculated relative EC50 (Effective Concentration at 50% effect) is 13 nM. The green curve indicates that there is no effect on cell viability. A toxic compound will reduce cell viability while a specific IL-8 release inhibitor might not. In general it is preferable to have a potent and efficacious compound which reduced the IL-8 levels without effect on cell viability.
- Profile of Psoriasis, International Federation of Psoriasis Associations. http://www.ifpa-pso.org
- Chiricozzi et al. Integrative responses to IL-17 and TNF-α in human keratinocytes account for key inflammatory pathogenic circuits in psoriasis. J Invest Dermatol. 2011 Mar;131(3):677-87. PubMed PMID: 21085185