Erratum: Lacticaseibacillus casei AMBR2 Restores Airway Epithelial Integrity in Chronic Rhinosinusitis With Nasal Polyps.

This corrects the article on p. 560 in vol. 13, PMID: 34212544.

Lacticaseibacillus casei AMBR2 Restores Airway Epithelial Integrity in Chronic Rhinosinusitis With Nasal Polyps.

PURPOSE: A defective epithelial barrier has been demonstrated in chronic rhinosinusitis with nasal polyps (CRSwNP). Lactobacilli are shown to restore epithelial barrier defects in gastrointestinal disorders, but their effect on the airway epithelial barrier is unknown. In this study, hence, we evaluated whether the nasopharyngeal isolates Lacticaseibacillus casei AMBR2 and Latilactobacillus sakei AMBR8 could restore nasal epithelial barrier integrity in CRSwNP. METHODS: Ex vivo trans-epithelial tissue resistance and fluorescein isothiocyanate-dextran 4 kDa (FD4) permeability of nasal mucosal explants were measured. The relative abundance of lactobacilli in the maxillary sinus of CRSwNP patients was analyzed by amplicon sequencing of the V4 region of the 16S rRNA gene. The effect of spray-dried L. casei AMBR2 and L. sakei AMBR8 on epithelial integrity was investigated in vitro in primary nasal epithelial cells (pNECs) from healthy controls and patients with CRSwNP as well as in vivo in a murine model of interleukin (IL)-4 induced barrier dysfunction. The activation of Toll-like receptor 2 (TLR2) was explored in vitro by using polyclonal antibodies. RESULTS: Patients with CRSwNP had a defective epithelial barrier which positively correlated with the relative abundance of lactobacilli-specific amplicons in the maxillary sinus. L. casei AMBR2, but not L. sakei AMBR8, increased the trans-epithelial electrical resistance (TEER) of pNECs from CRSwNP patients in a time-dependent manner. Treatment of epithelial cells with L. casei AMBR2 promoted the tight junction proteins occludin and zonula occludens-1 reorganization. Furthermore, L. casei AMBR2 prevented IL-4-induced nasal permeability in vivo and in vitro. Finally, the beneficial effect of L. casei AMBR2 on nasal epithelial cells in vitro was TLR2-dependent as blocking TLR2 receptors prevented the increase in TEER. CONCLUSIONS: A defective epithelial barrier in CRSwNP may be associated with a decrease in relative abundance of lactobacilli-specific amplicons. L. casei AMBR2 would restore nasal epithelial integrity and can be a novel therapeutic strategy for CRSwNP.

Probiotic nasal spray development by spray drying.

The upper respiratory tract (URT) is the main entrance point for many viral and bacterial pathogens, and URT infections are among the most common infections in the world. Recent evidences by our own group and others imply the importance of lactobacilli as gatekeepers of a healthy URT. However, the benefits of putting health-promoting microbes or potential probiotics, such as these URT lactobacilli, in function of URT disease control and prevention is underestimated, among others because of the absence of adequate formulation modalities. Therefore, this study entails important aspects in probiotic nasal spray development with a novel URT-derived probiotic strain by spray drying. We report quantitative and qualitative analysis of several spray-dried formulations, i.e. powders for reconstitution, based on disaccharide or sugar alcohol combinations with a polymer, including their long-term stability. Four formulations with the highest survival of >109 (Colony Forming Units) CFU/g after 28 weeks were further examined upon reconstitution which confirmed sufficiency of one bottle/dosage form during 7 days and rheological properties of shear-thinning. Tests also demonstrated maintained viability and cell morphology overall upon spraying through a nasal spray bottle in all 4 formulations. Lastly, application suitability in terms of high adherence to Calu-3 cells and antimicrobial activity against common URT pathogens was demonstrated and was not impacted neither by powder production process nor by spraying of reconstituted powder through a nasal spray device.

Strain-specific differences in behaviour among Lacticaseibacillus rhamnosus cell wall mutants during direct compression.

The human body harbours a large variety of microbial communities. It is already well-known that these communities play an important role in human health. Therefore, microbial imbalances can be responsible for several health disorders by different mechanisms. In recent years, probiotic bacteria have been increasingly applied to restore imbalances and stimulate microbiome functions such as immune modulation. Tablets are the dosage form of choice for oral probiotics. Nevertheless, a probiotic tablet with a sufficient amount of viable cells remains a challenge due to the stress of the compression process. Recent research demonstrated that the applied pressure and tableting properties play an important role in the survival of Lacticaseibacillus rhamnosus GG during direct compression. This study focused on the importance of the cell surface molecules in the protection of this prototype probiotic strain during direct compression. Spray-dried powders of L. rhamnosus GG and its exopolysaccharide-deficient mutant and lipoteichoic acid mutant were blended with two different filler-binders and compacted at various compression pressures. Under each tableting condition, the survival rate and tableting properties were analysed. The results demonstrated that the cell surface molecules play an important role in the behaviour of L. rhamnosus GG during direct compression. Specifically, the long, galactose-rich exopolysaccharides of L. rhamnosus served a protective shield during tablet production, promoting the survival rate of this probiotic strain. The D-alanylation of the lipoteichoic acids plays also an important role. When the D-alanyl ester content was completely absent, the survival rate was less affected by the tableting properties. Moreover, this research revealed that the sensitivity to the tableting properties is species and strain dependent.

Lactobacilli Have a Niche in the Human Nose.

Although an increasing number of beneficial microbiome members are characterized for the human gut and vagina, beneficial microbes are underexplored for the human upper respiratory tract (URT). In this study, we demonstrate that taxa from the beneficial Lactobacillus genus complex are more prevalent in the healthy URT than in patients with chronic rhinosinusitis (CRS). Several URT-specific isolates are cultured, characterized, and further explored for their genetic and functional properties related to adaptation to the URT. Catalase genes are found in the identified lactobacilli, which is a unique feature within this mostly facultative anaerobic genus. Moreover, one of our isolated strains, Lactobacillus casei AMBR2, contains fimbriae that enable strong adherence to URT epithelium, inhibit the growth and virulence of several URT pathogens, and successfully colonize nasal epithelium of healthy volunteers. This study thus demonstrates that specific lactobacilli are adapted to the URT and could have a beneficial keystone function in this habitat.