Administration of Lactobacillus plantarum GUANKE alleviates SARS-CoV-2-induced pneumonia in mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) targets epithelial cells in the respiratory tract, triggering an acute proinflammatory response and chronic lung inflammation. Probiotic supplementation has shown promise in reducing the nasopharyngeal SARS-CoV-2 viral load, diminishing symptom frequency and duration, and mitigating inflammation; thus, it is a potential strategy for treating coronavirus disease 2019 (COVID-19), which is caused by SARS-CoV-2 infection. In this study, we evaluated the effects of the oral administration of the Lactobacillus plantarum GUANKE strain, a gram-positive bacterium originally isolated from a healthy individual, on SARS-CoV-2 infection in a human ACE2 transgenic mouse model. We found that GUANKE significantly reduced inflammatory cell infiltration and pulmonary interstitial exudation in mice. The transcription of CCL2, TNFA, IL1B, IL6, and IL17C in the lungs was reduced. The protein levels of TNF-α, IL-1β, IL-6, and IL-17 in the lungs were significantly lower in GUANKE-treated mice than in control mice. The viral load in GUANKE-treated mice was lower than that in saline-treated mice, although this difference did not reach statistical significance. L. plantarum GUANKE can decrease SARS-CoV-2-induced lung inflammation in mice, suggesting its potential for use as an agent for treating SARS-CoV-2 infection.

Most otherwise healthy individuals develop only mild or moderate symptoms of coronavirus disease 2019 (COVID-19) caused by current strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and virus replication is mainly confined to the upper respiratory tract; however, the virus can infect the lower respiratory tract and promote inflammation. Probiotic supplementation has been shown to reduce nasopharyngeal SARS-CoV-2 viral load, reduce the overall number and duration of symptoms, and attenuate inflammation in clinical trials. We showed that a novel L. plantarum GUANKE strain alleviated SARS-CoV-2-induced pneumonia in mice. The transcription and production of inflammatory cytokines were suppressed, and GUANKE moderately reduced the viral load. L. plantarum GUANKE has the potential to become a candidate drug for the treatment of COVID-19 or other viral respiratory infections.