As diagrammed in Fig. 1a, 12 Chinese rhesus macaques were infected with SIVmac239 via intravenous infusion of 4000 50% tissue culture infective dose of SIVmac239 as previously described by Tian et al.4 And then they were randomized into test and control groups that received three injections of CD24Fc or NS, respectively, on day 56 of infection. Five months later, another cycle of treatment was given to the surviving monkeys, which were terminated 1 week after the last dosing for biomarker studies.4 Lung sections from all randomized animals, regardless of whether they received all the injections, were included in the analysis, as detailed in Supplementary Table 1.
CD24Fc protects against viral pneumonia in simian immunodeficiency virus-infected Chinese rhesus monkeys
Viral pneumonia is a major cause of mortality caused by both systemic and respiratory infections. The danger-associated molecular patterns (DAMPs) released during cell death in viral infection may cause a self-propagating inflammatory response with lasting lung damage. The CD24–Siglec 10/G interaction is an emerging immune checkpoint that regulates inflammation caused by DAMPs.1,2,3 While we have demonstrated that fortifying this immune checkpoint can reduce inflammation in the colon,4 joints5 and central nervous system,6 it is unclear whether CD24Fc can protect against pneumonia. To address this issue, we evaluated the lung pathology of simian immunodeficiency virus (SIV)-infected rhesus monkeys that received either normal saline (NS) or CD24Fc.