Heat inactivation partially preserved barrier and immunomodulatory effects of Lactobacillus gasseri LA806 in an in vitro model of bovine mastitis

Abstract

Probiotics could help combat infections and reduce antibiotic use. As use of live bacteria is limited in some cases by safety or regulatory concerns, the potential of inactivated bacteria is worth investigating. We evaluated the potential of live and heat-inactivated Lactobacillus gasseri LA806 to counteract Staphylococcus aureus and Escherichia coli infection cycles in an in vitro model of bovine mastitis. We assessed the ability of live and inactivated LA806 to impair pathogen colonisation of bovine mammary epithelial cells (bMECs) and to modulate cytokine expression by pathogen-stimulated bMECs. Live LA806 induced a five-fold decrease in S. aureus adhesion and internalisation (while not affecting E. coli colonisation) and decreased pro-inflammatory cytokine expression by S. aureus-stimulated bMECs (without interfering with the immune response to E. coli). The ability of inactivated LA806 ability to diminish S. aureus colonisation was two-fold lower than that of the live strain, but its anti-inflammatory properties were barely impacted. Even though LA806 effects were impaired after inactivation, both live and inactivated LA806 have barrier and immunomodulatory properties that could be useful to counteract S. aureus colonisation in the bovine mammary gland. As S. aureus is involved in various types of infection, LA806 potential would worth exploring in other contexts.

Veillonella parvula promotes the proliferation of lung adenocarcinoma through the nucleotide oligomerization domain 2/cellular communication network factor 4/nuclear factor kappa B pathway

“…Heat inactivation can affect the surface properties and structures of bacterial cells, which can lead to changes in their adhesion ability to host cells ( 38 ). It has been reported that heat inactivation of Escherichia coli and Staphylococcus aureus caused a significant decrease in its adhesive properties ( 39 ). E.coli and S.aureus were able to adhere more strongly to surfaces after being exposed to low-temperature inactivation compared to high-temperature inactivation ( 39 ).…”

Emulsion-Based Postbiotic Formulation Is Comparable to Viable Cells in Eliciting a Localized Immune Response in Dairy Cows With Chronic Mastitis

“…Another example includes a study by Jorjão et al (2015) who reported that heat-killed Lactobacillus rhamnosus ATCC7469 cells were able to stimulate mouse macrophages to produce cytokines including IL-4, IL-6, IL-10, IL-12, among others. In other bovine mastitis-related studies, Blanchet et al (2021) demonstrated the immunomodulatory efficacy of heat-killed Lactobacillus gasseri LA806 in the process of impairing E. coli and S. aureus colonization of bovine mammary epithelial cells (bMEC) in in vitro models. A separate study by Fukuyama et al (2020) , also reported the immunomodulatory efficacy of LAB strains in stimulating Toll-like receptor-mediated inflammatory responses in in vitro bMEC models.…”

Two human milk–like synthetic bacterial communities displayed contrasted impacts on barrier and immune responses in an intestinal quadricellular model

“…Extraction of total RNA of Caco2, HT29-MTX-E12, and M cells from one hand, and THP1 cells from the other hand, was performed as previously described [ 27 ]. Gene expression analysis was performed with the SmartChip Real-Time PCR System technology and with the 384-well plate PCR system for genes with detectable, but low, expression using the SmartChip system (cycle threshold (Ct) >28) ( Table S3 ).…”