SELECTION OF LACTIC ACID BACTERIAL STRAINS ABLE TO MODULATE THE HOST CENTRAL NERVOUS SYSTEM

BULACIOS GA; SALAZAR PB; POSSE DE CHAVES E; HEBERT EM; MINAHK C; SAAVEDRA L

Salta

Congreso; Congreso de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2019

Current evidence indicates that modulation of the central nervous system (CNS) by the microbiome occurs primarily through neuroimmune andneuroendocrine mechanisms, often involving the vagus nerve. In fact, the gut-brain axis provides the intestinal bacteria and its metabolites a wayto get access to the brain, thus regulating the expression of key effectors. Although lactic acid bacteria (LAB) represent only a small percentage ofthe total gut-dwelling microorganisms, they are undoubtedly important players. Pro-inflammatory cytokines are naturally upregulated in the elderlyand gut microbiota undergoes changes during aging. Therefore, it has been proposed that administration of probiotics may decrease the synthesisof these pro-inflammatory cytokines, hence reducing inflammation and oxidative stress, ameliorating the effects of senescence and the progressionof neurodegenerative diseases often associated with aging. These facts strongly suggest that LAB may be an invaluable tool in the treatment ofaging-related pathologies such as Alzheimer?s disease (AD), where microglia and non-parenchymal macrophages drive the neurodegeneration vianeuroinflammation. The aim of the present work was to assess the capacity of different LAB strains metabolites to regulate the secretion ofcytokines, inhibit acetylcholinesterase (AChE) and protect cells from the cytotoxic effects of the Aβ oligomers, key features of AD. For thatpurpose, murine RAW 264.7 macrophages were treated with conditioned media from seven selected LAB strains prior to the LPS stimulation. ThemRNA expression levels of the tumor necrosis factor alpha (TNF)-α, interferon-gamma (IFN-γ) and interleukin IL-10 were examined by RT-PCR.The results showed that conditioned media from Lactobacillus delbrueckii subsp. lactis CRL 581 and Lactobacillus reuteri CRL 1098 significantlyinhibited TNF-α mRNA expression. In addition, CRL 1098 strain increased IL-10 mRNA expression level in LPS-stimulated RAW 264.7 cells.Then, all conditioned media were evaluated in their ability to inhibit AChE from human erythrocytes (AChE-E) by Ellman´s method. AChE-Econstitutes a model of the isoform present in the CNS. As controls, polyphenols previously characterized as efficient inhibitors of AChE as wellas strong anti-inflammatory agents were used. Conditioned media from L. delbrueckii subsp. lactis CRL 581 showed a 40% inhibition of enzymaticactivity. Finally, APP-expressing neuroblastoma cells were preincubated with conditioned media and the expression of the APP transgene wasinduced by butyric acid. Viability of cells were evaluated using alamar blue assay. Results evidenced that conditioned media from L. rhamnosusA29 and Enterococcus mundtii CRL 35 protected against Aβ induced neuron cytotoxicity. These preliminary data support our ongoinginvestigations regarding the molecular mechanism of LAB interactions in the gut brain axis.