Long-term intake of Lactobacillus helveticus enhances bioavailability of omega-3 fatty acids in the mouse retina.

Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA), are required for the structure and function of the retina. Several observational studies indicate that consumption of a diet with relatively high levels of n-3 PUFAs, such as those provided by fish oils, has a protective effect against the development of age-related macular degeneration. Given the accumulating evidence showing the role of gut microbiota in regulating retinal physiology and host lipid metabolism, we evaluated the potential of long-term dietary supplementation with the Gram-positive bacterium Lactobacillus helveticus strain VEL12193 to modulate the retinal n-3 PUFA content. A set of complementary approaches was used to study the impact of such a supplementation on the gut microbiota and host lipid/fatty acid (FA) metabolism. L. helveticus-supplementation was associated with a decrease in retinal saturated FAs (SFAs) and monounsaturated FAs (MUFAs) as well as an increase in retinal n-3 and omega-6 (n-6) PUFAs. Interestingly, supplementation with L. helveticus enriched the retina in C22:5n-3 (docosapentaenoic acid, DPA), C22:6n-3 (DHA), C18:2n-6 (linoleic acid, LA) and C20:3n-6 (dihomo gamma-linolenic acid, DGLA). Long-term consumption of L. helveticus also modulated gut microbiota composition and some changes in OTUs abundance correlated with the retinal FA content. This study provides a proof of concept that targeting the gut microbiota could be an effective strategy to modulate the retinal FA content, including that of protective n-3 PUFAs, thus opening paths for the design of novel preventive and/or therapeutical strategies for retinopathies.

Intestinal release of biofilm-like microcolonies encased in calcium-pectinate beads increases probiotic properties of Lacticaseibacillus paracasei.

In this study, we show that calcium pectinate beads (CPB) allow the formation of 20 µm spherical microcolonies of the probiotic bacteria Lacticaseibacillus paracasei (formerly designated as Lactobacillus paracasei) ATCC334 with a high cell density, reaching more than 10 log (CFU/g). The bacteria within these microcolonies are well structured and adhere to a three-dimensional network made of calcium-pectinate through the synthesis of extracellular polymeric substances (EPS) and thus display a biofilm-like phenotype, an attractive property for their use as probiotics. During bacterial development in the CPB, a coalescence phenomenon arises between neighboring microcolonies accompanied by their peripheral spatialization within the bead. Moreover, the cells of L. paracasei ATCC334 encased in these pectinate beads exhibit increased resistance to acidic stress (pH 1.5), osmotic stress (4.5 M NaCl), the freeze-drying process and combined stresses, simulating the harsh conditions encountered in the gastrointestinal (GI) tract. In vivo, the oral administration of CPB-formulated L. paracasei ATCC334 in mice demonstrated that biofilm-like microcolonies are successfully released from the CPB matrix in the colonic environment. In addition, these CPB-formulated probiotic bacteria display the ability to reduce the severity of a DSS-induced colitis mouse model, with a decrease in colonic mucosal injuries, less inflammation, and reduced weight loss compared to DSS control mice. To conclude, this work paves the way for a new form of probiotic administration in the form of biofilm-like microcolonies with enhanced functionalities.