Date Published: June 1, 2018
Publisher: JKL International LLC
Author(s): Jiao Lu, Xuefeng Duan, Wenming Zhao, Jing Wang, Haoyu Wang, Kai Zhou, Min Fang.
Immune responses are a double-edged sword. Effective and appropriate immune responses capable of controlling viral infection while also largely preserving tissue integrity, are critical for host survival. Too strong immune responses might result in immune pathology, while too weak immune responses might cause viral persistence. Physiologic ageing is accompanied with a decline in the normal functioning of the immune system, which is termed as “immunosenescence”. We show that aged mice (16-19 months old) are more resistant to influenza A virus (IAV) infection than the young mice. Strong immune responses in the young mice after IAV infection result in faster clearance of virus, but also cause severe lung injury and higher mortality rate. While in the aged mice, the delayed and milder immune responses contribute to reduced pulmonary damage, and are still capable to clear the infection even with a slower kinetics, displaying a more resistant phenotype during IAV infection. Hence, our work demonstrates that moderate immune responses as a decline with ageing in the aged mice balance the immune pathology and viral clearance, might be beneficial for the host during certain circumstances. Our results provide important insight to our basic knowledge of immunosenescence and immune defenses to invading pathogens. Further, our results indicate that age factors should be considered when investigating the vaccination and therapeutic strategies for severe IAV infection.
In this study, we demonstrated that when challenged intranasally with IAV PR8 virus, the aged mice were more resistant than the young mice. The reduced inflammation cytokines and lower strength of NK and T cell immune responses in the aged mice might contribute to the alleviated lung pathology and increased survival rate after PR8 infection.