Particulate matter exposure exacerbates susceptibility to SARS-CoV-2 infection in humanized ACE2 mice.

The global outbreak of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as of 8 May 2021, has surpassed 150 700 000 infections and 3 279 000 deaths worldwide. Evidence indicates that SARS-CoV-2 RNA can be detected on particulate matter (PM), and COVID-19 cases are correlated with levels of air pollutants. However, the mechanisms of PM involvement in the spread of SARS-CoV-2 remain poorly understood. Here, we found that PM exposure increased the expression level of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in several epithelial cells and increased the adsorption of the SARS-CoV-2 spike protein. Instillation of PM in a hACE2 mouse model significantly increased the expression of ACE2 and Tmprss2 and viral replication in the lungs. Furthermore, PM exacerbated the pulmonary lesions caused by SARS-CoV-2 infection in the hACE2 mice. In conclusion, our study demonstrated that PM is an epidemiological factor of COVID-19, emphasizing the necessity of wearing anti-PM masks to cope with this global pandemic.

In vivo antimalarial activity of synthetic hepcidin against Plasmodium berghei in mice.

The present study was designed to investigate the antimalarial activity of synthetic hepcidin and its effect on cytokine secretion in mice infected with Plasmodium berghei. The mice were infected with P. berghei intravenously and treated with hepcidin according to 4-day suppression test and Rane's test. The serum levels of interleukins (IL-1ß, IL-2, IL-6, IL-10, IL-12p70, and IL-17A), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in the experimental mice were determined using a cytometric bead array (CBA) kit. The survival rate of the infected mice was also registered. Additionally, the serum iron, alanine transaminase (ALT), aspartate transaminase (AST), and total bilirubin (BIL) were detected to evaluate liver functions. Hepcidin exerted direct anti-malarial function in vivo and increased survival rate in a dose-dependent manner. In addition, the secretion of T helper cell type 1 (Th1), Th2, and Th17 cytokines, TNF-α, and IFN-γ were inhibited by hepcidin. In conclusion, our results demonstrated that synthetic hepcidin exerts in vivo antimalarial activity and possesses anti-inflammatory function, which provides a basis for future design of new derivatives with ideal anti-malarial activity.