Investigating strategies for optimizing immunity to COVID-19: examining the impact of probiotic lactic acid bacteria-derived secretomes on epithelial cell and macrophage immune activity
Strategies to promote immune defences against COVID-19 infection are urgently needed. The gastrointestinal tract is a potentially important route for COVID-19 infection and for generating protective anti-viral immunity against this pathogen. Certain features of COVID-19 contribute to its ability to evade and subvert our immune defences. Type I interferon is a key immune protein that shuts down viral replication during virus infections. However, SARS-CoV-2 evades this defence by failing to induce these protective interferons, allowing the virus to replicate and cause symptoms of COVID-19 infection. Macrophages are another key host immune defence. Severe COVID 19 infections can result in acute respiratory distress syndrome (ARDS), an outcome linked to the disastrous effects of pro-inflammatory macrophage activity and “cytokine storm” production. In our research analyzing probiotic bacteria communication with the immune system, we found that Lactobacillus rhamnosus R0011 acts on intestinal epithelial cells and macrophages via secreted molecules (a secretome). This secretome-mediated communication induced Type I interferon production and drove macrophage differentiation into a regulatory phenotype, in contrast to the pro-inflammatory macrophages causing damage in severe COVID-19 cases.