mKate2 Labelled Respiratory Syncytial Virus

Mesenchymal stem cells (MSCs) are present in nearly all organs, including the nasal mucosa and lungs, where they play a role in regulating immune responses and mediating tissue repair. Here, researchers sought to determine whether respiratory syncytial virus (RSV) infection of MSCs would enhance their immunomodulatory functions and contribute to RSV-associated lung disease. Fluorescence microscopy, plaque assays, and RSV transcript expression demonstrated that RSV can replicate in human MSCs. RSV-infected MSCs exhibited differential expression of cytokines and chemokines, such as IL-1β, IL6, IL-8, and SDF-1, compared with epithelial cells. Notably, RSV-infected MSCs exhibited significantly increased expression of IFN-β (approximately 100-fold) and indoleamine-2,3-dioxygenase (IDO) (approximately 70-fold) compared with mock-infected MSCs. Treatment of PBMCs with culture supernatant of RSV-infected MSCs reduced their proliferation in a dose-dependent manner. The findings here suggest that RSV infection of MSCs alters their immunoregulatory function by upregulating IFN-β and IDO, thereby affecting immune cell proliferation, which may account for the lack of RSV protective immunity and the chronicity of RSV-related lung diseases such as asthma and COPD.

In this study, live cell imaging of m-Kate2 expression in infected cells at 24, 48, and 72 h postinfection showed that RSV was able to infect four different MSC batches, including two UCB MSC lines and two BM MSC lines (Figure 1).

Figure 1. RSV infection of human MSCs. Two lots of UCB MSCs as well as two lots of BM MSCs were shown to become infected with mKate2 Labelled Respiratory Syncytial Virus. (Cheung M B, et al., 2016)