RESUMO
Bifidobacteria colonize the human gastrointestinal tract early on in life, their interaction with the host starting soon after birth. The health benefits are strain specific and could be due to the produced polysaccharides. The consumption of probiotics may prevent obesity, irritable bowel syndrome, eczema or atopic dermatitis, and asthma. Non-replicative strains of Bifidobacterium longum (NCC3001 and NCC2705) promote the differentiation of normal human epidermal keratinocytes (NHEKs), inducing a high expression of differentiation markers (keratin -KRT1-, and transglutaminase -TGM1-) and pro-regeneration markers (cathepsins), including ß-defensin-1, which plays an important role in modulating the cutaneous immune response. Strains belonging to the genera Bifidobacterium and Lactobacillus can increase tight-junction proteins in NHEKs and enhance barrier function. Bifidobacteria and lactobacilli may be used as prophylactic or therapeutic agents towards enteric pathogens, antibiotic-associated diarrhea, lactose intolerance, ulcerative colitis, irritable bowel syndrome, colorectal cancer, cholesterol reduction, and control of obesity and metabolic disorders. Bifidobacterium bifidum showed an in vitro capability of lowering cholesterol levels thanks to its absorption into the bacterial membrane. Several strains of the species Lactobacillus acidophilus, L. delbrueckii subsp. bulgaricus, L. casei, and L. gasseri led to a reduced amount of serum cholesterol due to their ability to assimilate cholesterol (in vitro). Lactococcus lactis KF147 and Lactobacillus plantarum Lp81 have also been shown to reduce cholesterol levels by 12%. Clarifying the specific health mechanisms of Bifidobacterium and Lactobacillus strains in preventing high-cost pathologies could be useful for delineating effective guidelines for the treatment of infants and adults.
RESUMO
In this study, a novel multifunctional nanoplatform based on core-shell nanoparticles of spherical gold nanoparticles (AuNPs) capped with low and high molecular weight (200 and 700 kDa) hyaluronic acid (HA), was assembled via a green, one-pot redox synthesis method at room temperature. A multitechnique characterization approach by UV-visible spectroscopy, dynamic light scattering and atomic force microscopy pointed to the effective 'surface decoration' of the gold nanoparticles by HA, resulting in different grafting densities of the biopolymer chains at the surface of the metal nanoparticle, which in turn affected the physicochemical properties of the nanoparticles. Specifically, the spectral features of the gold plasmonic peak (and the related calculated optical size), the hydrodynamic diameter and the nanoparticle stability were found to depend on the molecular weight of the HA. The CD44-targeting capability of HA-functionalized gold nanoparticles was tested in terms of antibacterial activity and cytotoxicity. An enhanced inhibitory activity against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was found, with a HA molecular weight (MW)-dependent trend for the HA-capped AuNPs compared to the bare, glucose-capped AuNPs. Cell viability assays performed on two CD44-positive cell models, namely normal human umbilical vein endothelial (HUVEC) and prostate tumor (PC-3) cells, in comparison with neuroblastoma cells (SH-SY5Y), which do not express the CD44 receptor, demonstrated an increased cytotoxicity in neuroblastoma compared to prostate cancer cells upon the cellular treatments by HA-AuNP compared to the bare AuNP, but a receptor-dependent perturbation effect on cytoskeleton actin and lysosomal organelles, as detected by confocal microscopy. These results highlighted the promising potentialities of the HA-decorated gold nanoparticles for selective cytotoxicity in cancer therapy. Confocal microscopy imaging of the two human tumor cell models demonstrated a membrane-confined uptake of HA-capped AuNP in the cancer cells that express CD44 receptors and the different perturbation effects related to molecular weight of HA wrapping the metallic core of the plasmonic nanoparticles on cellular organelles and membrane mobility.