SARS-CoV-2 modulates PLA2G2D/PGD2 signaling to manipulate host immune response to increase disease severity.

Background: Previous studies suggested that SARS-CoV-2 infection could cause diverse immune and metabolic dysregulations, although the underlying mechanisms remain poorly understood. In addition, viruses may escape the immune response by modulating cellular metabolism, mitochondria, and protein functions indicating that immune or metabolic components may represent novel targets for anti-viral strategies. However, whether immune and metabolic disorders interact or affect each other waits to be determined. On the other hand, previous investigations identified the critical roles of a cell membrane-bound phospholipase PLA2G2D and its downstream products PGD2 in regulating the metabolism and inflammation in respiratory system. More importantly, the expression of PLA2G2D increased during aging, indicating its potential role in age-dependent susceptibility to SARS-CoV-2 infection which was confirmed by our animal model. However, whether PLA2G2D plays a critical role in interaction between metabolic and immune disorder remains to be determined. Based on the regulatory roles of PLA2G2D, I hypothesize that SARS-CoV-2 regulates PLA2G2D expression to manipulate host immune responses. Methods: Using PLA2G2D KO and DP1 KO mice, we will analyze the different immunological responses to SARS-CoV-2 infection via histology and qRT-PCR to analyze cytokines and chemokines. In addition, to identify the modifications done to the viral outcome we can perform a plaque assay and PCR. Meanwhile, we will used CO-IP to determine protein interaction, while using seahorse and calcium assay to analyze the effects on mitochondrial function. Results: qRT-PCR would display SARS-CoV-2 infection increases PLA2G2D expression in both animal and cell models. Whereas the plaque assay and PCR would display an increase in total virus and dynamic of SARS-CoV-2 severity in mice with PLA2G2D but an increase in inflammation in PLA2G2D KO mice. In addition, we expect the metabolic pathway to display an increase in calcium levels and ROS production but a decrease in mitochondrial and ATP function. Conclusion: The results indicate that SARS-CoV-2 is altering inflammasome assembly via inhibition of DP1 signaling, resulting in decreased immune responses. Also, the results would display an increase in total virus which propagates the viral persistence. Overall, the results imply that SARS-CoV-2 regulates PLA2G2D expression to influence the outcome of disease severity via influx of viral persistence and manipulation of host immune responses.