Mapping the Periostin splice isoforms in atopic dermatitis and an in vitro asthma model – A multi-platform analysis using mass spectrometry and RT-qPCR.

Periostin is a matricellular protein known to be alternatively spliced to produce ten isoforms with a molecular weight of 78–91 kDa. Within the extracellular matrix, periostin attaches to cell surfaces to induce signaling via integrin-binding and actively participates in fibrillogenesis, orchestrating the arrangement of collagen in the extracellular environment. In atopic diseases such as atopic dermatitis (AD) and asthma, periostin is known to participate in driving the disease-causing type 2 inflammation. The periostin isoforms expressed in these diseases and the implication of the alternative splicing events are unknown. Here, we present two universal assays to map the expression of periostin isoforms at the mRNA (RT-qPCR) and protein (PRM-based mass spectrometry) levels. We use these assays to study the splicing profile of periostin in AD lesions as well as in in vitro models of AD and asthma. In these conditions, periostin displayed overexpression with isoforms 3 and 5 standing out as highly overexpressed. Notably, isoforms 9 and 10 exhibited a divergent pattern relative to the remaining isoforms. Isoforms 9 and 10 are often overlooked in periostin research and this paper presents the first evidence of their expression at the protein level. This underlines the necessity to include isoforms 9 and 10 in future research addressing periostin splice isoforms. The assays presented in this paper hold the potential to improve our insight into the splicing profile of periostin in tissues and diseases of interest. The application of these assays to AD lesions and in vitro models demonstrated their potential for identifying isoforms of particular significance, warranting a further in-depth investigation. [Display omitted] • The study presents two new methods for mapping and measuring periostin splice isoforms in human samples. • The analyses show that isoforms 3 and 5 are significantly overexpressed while isoforms 9 and 10 are downregulated in the diseases studied. • This is the first experimental proof of the existence of isoforms 9 and 10 at the protein level. • The results demonstrate that these methods have the potential to identify isoforms that are particularly significant. • Our research accurately maps periostin isoform expression in human samples, providing the basis for further understanding. [ABSTRACT FROM AUTHOR]