Blockade of the C5a–C5aR axis alleviates lung damage in hDPP4-transgenic mice infected with MERS-CoV

Jiang, Yuting; Zhao, Guangyu; Song, Nianping; Li, Pei; Chen, Yuehong; Guo, Yan; Li, Junfeng; Du, Lanying; Jiang, Shibo; Guo, Renfeng; Sun, Shihui; Zhou, Yusen

The spleen is an important secondary lymphoid organ with a well-organized structure, allowing the capture, processing, and presentation of antigens, ultimately leading to successful elimination of pathogens and the induction of adaptive immunity. Thus, the spleen is pivotal for maintaining blood homeostasis and producing immune responses to viral infection 39 . The spleen is divided into the white and red pulps, which are separated by the marginal zone, where vast splenic macrophage populations, such as marginal metallophilic macrophages, marginal zone macrophages, and red pulp macrophages are now considered to play important roles in the control of infection, as well as in the induction of innate and adaptive immunity 40 . For example, red pulp macrophages can prevent autoimmunity by producing antiinflammatory cytokines, such as TGF-β and IL-10, and by inducing T-regulatory cells 41 . These cytokines may be important to curb an excessive immune response that could be deleterious to the host after pathogen clearance.