Lactobacillus rhamnosus dampens cytokine and chemokine secretion from primary human nasal epithelial cells infected with rhinovirus

The response of nasal epithelial cells exposed to novel Lactobacillus and alpha-haemolytic Streptococcus isolated from the upper respiratory tract of children

AIMS

To investigate the response of primary nasal epithelial cells (NECs) to novel alpha haemolytic Streptococcus and lactobacilli strains, isolated from the upper respiratory tract of children.

METHODS AND RESULTS

Submerged cultures of NECs from healthy adult donors were exposed to either novel strains; Lactobacillus rhamnosus D3189, D3160, Streptococcus salivarius D3837; or commercially available probiotic strains L. rhamnosus LB21, S. salivarius K12; or a pathogenic strain (S. pneumoniae 49619). Cytotoxicity (measured through lactate dehydrogenase release) and cytokine release were quantified 24 hours post-exposure. Exposure to novel and commercially available strains did not induce the production of IFN-β, IFN-λ1/3, IL-1β, IL-6, IL-8, or TNF-α production or the release of LDH. Conversely, the pathogenic strain S. pneumoniae 49 619 significantly elevated the expression of IL-1β, IL-8, TNF-α, and LDH in NECs.

CONCLUSIONS

The findings within this study highlight the non-pathogenic nature of these novel strains and support further investigation of the potential to develop nasally administered probiotics.

The effect of probiotic Bifidobacterium lactis Bl-04 on innate antiviral responses invitro

Consumption of certain probiotic strains may be beneficial for reducing the risk of acute upper respiratory tract infections (URTIs), however, underlying immunological mechanisms are elusive. Bifidobacterium lactis Bl-04™ has been reported in humans to significantly reduce the risk of URTIs, affect the innate immunity in the nasal mucosa, and reduce nasal lavage virus titer after a rhinovirus (RV) challenge. To study the immunological mechanisms, we investigated the effect of Bl-04 on cytokine production and transcriptomes of human monocyte-derived macrophages (Mfs) and dendritic cells (DCs), and further on RV replication and cytokine production in MRC-5 fibroblasts. The results showed that Bl-04 modulates antiviral immune responses and potentiates cytokine production during viral challenge mimic in immune cells. However, effect of Bl-04 on RV replication and cytokine production in fibroblasts was negligible. Overall, the findings suggest that Bl-04 mildly stimulates antiviral immunity in Mfs and DCs, and potentially influences viral replication in fibroblasts that however warrants further investigations.