Lactobacillus fermentum NCIMB 5221 and NCIMB 2797 as cholesterol-lowering probiotic biotherapeutics: in vitro analysis.

Cardiovascular and coronary artery disease risk are correlated with cholesterol levels and are significant health concerns. Current cholesterol-lowering approaches includes lifestyle and diet modifications, as well as statins which presents numerous shortcomings. The probiotic bacteria, Lactobacillus fermentum NCIMB 5221 and NCIMB 2797, have demonstrated cholesterol-lowering potential in animal studies. However, there is a lack in understanding the mechanism(s) behind these observed effects. The goal of this work is to investigate, in vitro, the cholesterol-lowering mechanisms of these two strains. To determine the cholesterol-lowering mechanisms, probiotic cholesterol assimilation, colon epithelial adhesion and inhibition of cholesterol uptake by colon epithelial (Caco-2) cells were investigated. L. fermentum NCIMB 2797 (P=0.012) and NCIMB 5221 (P=0.003) assimilated cholesterol and their cell surface hydrophobicity was 70.30±8.85% and 55.60±2.59%, respectively. Both L. fermentum strains showed no significant impact (P>0.05) on Caco-2 cell viability. Of most interest, Caco-2 pre-exposure to L. fermentum NCIMB 5221 significantly decreased (P=0.015) cholesterol uptake, with 85.98±2.07% uptake compared to the untreated cells. Similarly, L. fermentum NCIMB 2797 probiotic cells significantly decreased (P=0.019) cholesterol uptake by Caco-2 cells, with 86.45±1.71% uptake observed compared to the control cells. The results demonstrate that L. fermentum NCIMB 5221 and L. fermentum NCIMB 2797 have the potential via various modes of action to lower cholesterol. Additional studies are required to understand the mechanism(s) of action behind probiotic cholesterol assimilation and behind the cholesterol uptake inhibition by colon epithelial cells.

Investigation of probiotic bacteria as dental caries and periodontal disease biotherapeutics.

Oral diseases, specifically dental caries and periodontal disease, are characterised by increases in pathogenic microorganisms, increased demineralisation and increased inflammation and levels of inflammatory markers. Despite the therapeutic strategies, oral diseases have elevated prevalence rates. Recent work has demonstrated that probiotic bio-therapeutics can decrease oral pathogen counts, including caries-causing Streptococcus mutans and oral inflammation. The aim of this work was to investigate putative probiotic bacteria, selected for S. mutans inhibition and for their oral health-promoting characteristics. The probiotic bacteria were screened for S. mutans inhibition, probiotic bacteriocin activity, salivary pH modulation, probiotic nutrient (sucrose) competition, probiotic co-aggregation with S. mutans, bacterial attachment to oral epithelial keratinocytes, bacterial nitric oxide production and bacterial antioxidant activity. The results indicate that Lactobacillus reuteri strains NCIMB 701359, NCIMB 701089, NCIMB 702655 and NCIMB 702656 inhibited S. mutans to non-detectable levels (<10 cfu/ml). L. reuteri strains also demonstrated the highest antioxidant capacity of the tested strains (7.73-13.99 µM Trolox equivalents), suggesting their use as both caries and periodontal disease therapeutics. Although Lactobacillus fermentum NCIMB 5221 inhibited S. mutans at lower levels, it significantly buffered the pH (4.18) of saliva containing S. mutans, co-aggregated with S. mutans (10.09%), demonstrated high levels of sucrose consumption (138.11 mM) and successfully attached to gingival epithelial cells (11%). This study identified four L. reuteri strains and one L. fermentum strain to be further investigated as oral disease biotherapeutics.