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

Abstract

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. IMPORTANCE 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.