Bioengineering a humanized acne microenvironment model: Proteomics analysis of host responses to Propionibacterium acnes infection in vivo

Acne is a human disease of the sebaceous hair follicle. Unlike humans, most animals produce little or no triglycerides in hair follicles to harbor Propionibacterium acnes a fact that has encumbered the development of novel treatments for acne lesions. Although genetic mutant mice with acne-like skins have been used for screening anti-acne drugs, the mice generally have deficits in immune system that turns out to be inappropriate to generate antibodies for developing acne vaccines. Here, we employed a bioengineering approach using a tissue chamber integrated with a dermis-based cell-trapped system (DBCTS) to mimic the in vivo microenvironment of acne lesions. Human sebocyte cell lines were grown in DBCTS as a scaffold and inserted into a perforated tissue chamber. After implantation of a tissue chamber bearing human sebocytes into ICR mice, P. acnes or PBS was injected into a tissue chamber to induce host immune response. Infiltrated cells such as neutrophils and macrophages were detectable in tissue chamber fluids. In addition, a proinflammatory cytokine macrophage-inflammatory protein-2 (MIP-2) was elevated after P. acnes injection. In tissue chamber fluids, 13 proteins including secreted proteins and cell matrix derived from mouse, human cells or P. acnes were identified by proteomics using isotope-coded protein label (ICPL) coupled to nano-LC-MS analysis. After P. acnes infection, four proteins including fibrinogen, α polypeptide, fibrinogen β chain, S100A9, and serine protease inhibitor A3K showed altered concentrations in the mimicked acne microenvironment. The bioengineered acne model thus provides an in vivo microenvironment to study the interaction of host with P. acnes and offers a unique set-up for screening novel anti-acne drugs and vaccines.