Endoplasmic reticulum stress and the related signaling networks in severe asthma.

The endoplasmic reticulum (ER) is a specialized organelle that plays a central role in biosynthesis, correct protein folding, and posttranslational modifications of secretory and membrane proteins. Loss of homeostasis in ER functions triggers the ER stress response, resulting in activation of unfolded protein response (UPR), a hallmark of many inflammatory diseases. These pathways have been reported as critical players in the pathogenesis of various pulmonary disorders, including pulmonary fibrosis, lung injury, and chronic airway disorders. More interestingly, ER stress and the related signaling networks are emerging as important modulators of inflammatory and immune responses in the development of allergen-induced bronchial asthma, especially severe asthma.