Abstract
BackgroundThe use of probiotics to improve anti-microbial defence, such as for influenza infections, is increasingly recommended. However, no data are available on the effect of probiotics on flu-associated secondary bacterial infections. There is strong evidence of a spatiotemporal association between influenza virus infection and invasive Neisseria meningitidis. We thus investigated the effect of feeding mice Lactobacillus paracasei CNCM I-1518 in a mouse model of sequential influenza-meningococcal infection.MethodsWe intranasally infected BALB/c mice with a strain of influenza A virus (IAV) H3N2 that was first adapted to mice. Seven days later, a secondary bacterial infection was induced by intranasal administration of bioluminescent N. meningitidis. During the experiment, mice orally received either L. paracasei CNCM I-1518 or PBS as a control. The effect of L. paracasei administration on secondary bacterial infection by N. meningitidis was evaluated.ResultsOral consumption of L. paracasei CNCM I-1518 reduced the weight loss of infected mice and lowered the bioluminescent signal of infecting meningococci. This improvement was associated with higher recruitment of inflammatory myeloid cells, such as interstitial monocytes and dendritic cells, to the lungs.ConclusionsOur data highlight the role of the gut-lung axis. L. paracasei CNCM I-1518 may boost the defence against IAV infection and secondary bacterial infection, which should be further studied and validated in clinical trials.
Highlights
The use of probiotics to improve anti-microbial defence, such as for influenza infections, is increasingly recommended
Effect of L. paracasei Collection Nationale de Culture de Microorganismes (CNCM) I-1518 on the health status of mice with a secondary bacterial infection We first assessed the effect of oral administration of L. paracasei CNCM I-1518 on secondary meningococcal infection
Theses data suggest that consumption of L. paracasei before N. meningitidis infection is associated with an improvement in the health of the mice
Summary
The use of probiotics to improve anti-microbial defence, such as for influenza infections, is increasingly recommended. No data are available on the effect of probiotics on flu-associated secondary bacterial infections. There is strong evidence of a spatiotemporal association between influenza virus infection and invasive Neisseria meningitidis. Bacterial and viral respiratory infections are responsible for severe morbidity and mortality in children and adults worldwide. Influenza virus is a major source of severe viral respiratory infections in adults, causing annual epidemics that result in significant morbidity and mortality. Flu morbidity is often due to secondary respiratory infections by bacteria, such as Streptococcus pneumoniae and Neisseria meningitidis [2, 3]. The winter peaks of invasive meningococcal disease usually follow the peak of influenza-like syndromes [6] This sequential pattern of flu infection and invasive meningococcal infection has been reproduced in a murine animal model [7].
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