Hyperosmotic stress response regulates interstitial homeostasis and pathogenic inflammation.

Hyperosmotic stress triggers an evolutionally preserved, fundamental cellular response. A growing body of evidence has highlighted the role of extra-renal, interstitial hyperosmolality in maintaining local tissue immune homeostasis and potentially driving tissue inflammation in human diseases. The hyperosmotic stress response initiates cellular shrinkage, oxidative stress, metabolic remodeling and cell cycle arrest, all of which are adjusted by a counteractive adaptative response that includes osmolyte synthesis, upregulation of ion transporters and induction of heat shock proteins. Recent studies have revealed that high osmolality can impact immune cell differentiation and activation pathways in a cell type specific manner. The fine-tuning of the immune response depends on the tissue microenvironment. Accordingly, novel therapeutic approaches that target hyperosmolality-mediated inflammation may be identified by furthering our understanding of hyperosmotic response in the context of disease. In this review, we discuss the cellular and molecular mechanisms by which hyperosmotic stress response regulates interstitial homeostasis and pathogenic inflammation.