ABSTRACT
The respiratory tract is primary contact site of the body and environment,and it is ventilated by 10-20 thousand liters of air per day.Inevitably,the respiratory system comes into contact with airborne microbes,which contain the disease-causing pathogens.Airway epithelial cells (AECs) are known to have innate sensor functions,which are similar to the "professional" immune cells,such as alveolar macrophage and sub-or intra-epithelial dendritic cells (DCs).Thus AECs are able to detect invading microbial danger including different types of respiratory viruses,and mount a potent host response,for example,activating type Ⅰ interferon signaling pathway genes.To avoid chronic inflammation and maintain the immunological homeostasis,the pulmonary system has developed intrinsic mechanisms to control local immune responses.Most recently,the role of AECs in control of local immunity has gained much attention,as 1) AECs express the pattern recognition receptors (PRRs),such as Toll-like receptors,retinoic acid inducible gene Ⅰ (RIG-Ⅰ)-like receptor,and so on,thus AECs are equipped to Participate in innate detection of microbial encounter;2) To keep immunological homeostasis in the respiratory tract,AECs behave not only as innate immune sensors but also as immune modulators in parallel,through modulating the sensitivity of innate immune sensing of both AECs per se and sub-or intra-epithelial immune cells;3) Loss of modularity capacity of AECs might be involved in the development of chronic airway diseases.In present review,how the AECs act will be intensively discussed in response to respiratory viruses and modulate the local immunity through cis-and trans-factors (direct and indirect factors),as well as the consequence of impairment of this control of local immunity,in the development and exacerbation of airway diseases,such as acute and chronic rhinosinusitis.
ABSTRACT
The nose together with the paranasal sinuses is the main part of the upper airway,which is lined with pseudostratified columnar ciliated epithelium.There are several important physiological functions such as conditioning and filtration of the inspired air and the provision of end organ for the sense of smell.Besides the nose also fulfills a physical and immunological barrier as the nasal epithelium is the first site of interaction between the host tissue and foreign invaders,such as viruses,bacteria,fungi,allergens,and harmful particulates.Hence,nasal diseases such as rhinitis (allergic and infectious) and rhinosinusitis are the most common health problems worldwide,affecting millions of people of all ages.In the past 10 to 20 years,our understanding of the immuno-pathophysiological mechanisms underlying the common nasal diseases has been significantly enhanced by in vivo and in vitro studies.This allows the development of novel therapeutic strategies designed to improve the physiological and immune defense functions of the nose,as well as for other common airway diseases.Since the dynamically external changes of atmosphere,environment (pollution) and susceptible population,we are now facing some of new features on epidemiology and the types of upper airway diseases that require us to in-deep study the diseases through basic and clinical researches,so as to further understand the prevention,diagnosis and treatment of the diseases.