Continuous monitoring of epidermal inflammatory response to mechanical strain - Project Summary Psoriasis is a debilitating autoimmune skin disease that affects more than 125 million adults globally. While prototypically associated with immune cell infiltration in the skin, psoriasis preferentially affects the extensor surfaces of the joints such as the outside of the elbows and knees. Current treatments for psoriasis include topical steroids, which have poor side-effect profiles with long-term use, and systemic immunomodulatory agents, which, although promising, have notable off-target immune effects. Better understanding of the nature of inflammation in the skin may help to develop more precisely targeted therapeutics for psoriasis and associated disorders. The epidermis of the skin, chiefly composed of keratinocytes, provides an essential barrier between the organism and the environment. Mechanical disruption of the barrier is associated with development of lesions in psoriasis and associated disorders; however, it isn’t understood how barrier disruption vs. mechanical sensation of strain by keratinocytes contributes to their development of psoriatic phenotype. While canonical inflammatory cells are the drivers of acute inflammation in psoriasis, their action depends on a receptive environment built up by keratinocyte signaling and behavior. In addition, there is evidence that keratinocyte autoregulatory loops may establish that autoimmune-prone environment prior to stimulation by canonical immune cells. As mechanosensing cells at the skin barrier, keratinocytes are uniquely privileged in the information available to them—unlike canonical immune cells, they have access to both mechanical stimuli and direct exposure to the status of the epidermal barrier. In this way, keratinocytes are critical messengers of mechanical and physical barrier status. However, it is difficult to tease apart contributions to inflammation, as there is currently no method for continuously monitoring inflammatory markers at minute resolution. Furthermore, there is currently no system for applying physiologic strain to 3D models of psoriasis in vitro. The technology development portion of this proposal is to design such a continuous monitoring device and develop a system for applying strain to 3D models of keratinocytes. This proposal will build the tools necessary to test the hypothesis that keratinocyte mechanosensing modulates their inflammatory behavior in psoriasis. In Aim 1, I will optimize and validate reagentless sensing devices for continuous monitoring of immunoregulatory cytokines released by keratinocytes. This aim will seek to understand what events happen on the minute-to- minute scale as keratinocytes experience mechanical strain. In Aim 2, I will build a novel tissue culture system for applying controlled strains and measuring mechanical properties of 3D human skin models. In this aim I will visualize the effect of strain on cytoskeletal and extracellular matrix mechanics, and determine how applied strains change the threshold for autoimmune activation of keratinocytes.
