Development And Phagocytosis Of Macrophages In Chicken Lungs

Macrophages play a pivotal role in innate and adaptive immunity by killing foreign organisms,presenting antigens,secreting chemical mediators,phagocytizing foreign invaders,and undergoing oxidative stress.They interact with cells such as T cells,B cells,natural killer cells,dendritic cells,neutrophils,and fibroblasts.Activated macrophages produce a number of multifunctional compounds including cytokines,reactive oxygen species(ROS)and reactive nitrogen species(RNS)such as nitric oxide(NO).The birds have significantly fewer free respiratory macrophages(FARMs)compared to the rat.The phagocytes are critical for the chicen survival immediately after hatching,as chickens start to breathe at that time,and through foraging they are exposed to adult-type microflora.Then,at the beginning of the hatching,the respiratory airway macrophage can give timely and effectively protect to the respiratory tract.This study will discuss these issue.The present test was divided into two parts: the in vivo part was vaccinated with Newcastle Disease Virus(NDV)attenuated vaccine at 1,4,7,14,21 and 28 days of ages.as the research objects.The number and distribution of macrophages and NDVs,phagocytosis in the lungs of each were determined after immunizing in each day group at at 6 h,12 h,24 h,4 d,7 d by immunohistochemical staining method.Expression levels of IL-1β、IL-6 and iNOS in chicken lungs of macrophages in the lungs was detected by qRT-PCR.Macrophages were isolated from the lungs of 1,4,7,14,21,and 28 day old chicks in vitro;the phagocytic capacity of avian macrophages was evaluated using invert fluorescent microscope and Flow Cytometry in birds that were inoculated with fluorescent microspheres.Expression levels of IL-1β,IL-6 and iNOS in avian lung macrophages,and changes of phagocytic function of macrophages in the lungs were detected by ELISA.In vivo results show: macrophages have appeared in the chicken lungs at one-day-old and increased with age,showing a peak at 28 d.Macrophages began to appear in the interatria,followed by lung development,which then diffusely scattered in the wall of the respiratory capillary and connective tissue.The expression of IL-1β and iNOS.reached a peak at 14 d and 28 d respectively.During 1 to 7 days of age IL-6 in chicken lungs expression graduate up regulated;during 7 to 21 days,it had no significant change,but showed a peak at 28 d.In vitro tests demonstrated that: the phagocytic percentage and phagocytic index increased with age.At the age of 7d,phagocytic percentage significantly up-regulated.At the age of 21 d and 28 d,phagocytic index significantly up-regulated.In addition,during 4 to 14 days of age,IL-1β and iNOS expression in avian lungs macrophages had no significant change.During 14 to 28 days of age IL-1β graduate wee up-regulated IL-6 expression increased with age.In vivo and in vitro tasts showed that macrophages gradually increased with age,and during 14 to 28 days of ages phagocytic function was not fully developed.At 28 days of age,macrophages reached a maximum,while the phagocytosis rate,phagocytic index,and iNOS all reached a maximum.After 24 hours of inoculation with NDV in each ages group,the number of macrophages and phagocytosis peaked.This study explores the development and phagocytosis of macrophages in the lungs of chickens of different ages,and lays the foundation for the further study of poultry macrophages,and to provide reference for the study of the immune development of birds.