Development of a live biotherapeutic throat spray with lactobacilli targeting respiratory viral infections

Abstract

Respiratory viruses such as influenza viruses, respiratory syncytial virus (RSV), and coronaviruses initiate infection at the mucosal surfaces of the upper respiratory tract (URT), where the resident respiratory microbiome has an important gatekeeper function. In contrast to gut-targeting administration of beneficial bacteria against respiratory viral disease, topical URT administration of probiotics is currently underexplored, especially for the prevention and/or treatment of viral infections. Here, we report the formulation of a throat spray with live lactobacilli exhibiting several in vitro mechanisms of action against respiratory viral infections, including induction of interferon regulatory pathways and direct inhibition of respiratory viruses. Rational selection of Lactobacillaceae strains was based on previously documented beneficial properties, up-scaling and industrial production characteristics, clinical safety parameters, and potential antiviral and immunostimulatory efficacy in the URT demonstrated in this study. Using a three-step selection strategy, three strains were selected and further tested in vitro antiviral assays and in formulations: Lacticaseibacillus casei AMBR2 as a promising endogenous candidate URT probiotic with previously reported barrier-enhancing and anti-pathogenic properties and the two well-studied model strains Lacticaseibacillus rhamnosus GG and Lactiplantibacillus plantarum WCFS1 that display immunomodulatory capacities. The three strains and their combination significantly reduced the cytopathogenic effects of RSV, influenza A/H1N1 and B viruses, and HCoV-229E coronavirus in co-culture models with bacteria, virus, and host cells. Subsequently, these strains were formulated in a throat spray and human monocytes were employed to confirm the formulation process did not reduce the interferon regulatory pathway-inducing capacity. Administration of the throat spray in healthy volunteers revealed that the lactobacilli were capable of temporary colonization of the throat in a metabolically active form. Thus, the developed spray with live lactobacilli will be further explored in the clinic as a potential broad-acting live biotherapeutic strategy against respiratory viral diseases.

Effects of Probiotic Supplementation during Chronic Rhinosinusitis on the Microbiome

“…The more established strains, notably those that belong to the Lactobacillaceae family, are already widely utilised and have a known safety profile. It has been proposed that lactic acid bacteria (LAB) can rebuild commensal microbiomes [ 16 , 27 , 65 ]. It is worth noting that LAB are part of the microbiome of the upper respiratory tract [ 31 , 60 , 62 ].…”

“…L. casei AMBR2 is a promising candidate for a live biotherapeutic product as a probiotic. It has the ability to inhibit the growth and inflammatory properties of pathogens such as Staphylococcus aureus and to promote epithelial barrier function [ 34 , 65 ]. Thus, there is a lot of interest in further using this strain in CRS patients.…”

Surface layer proteins in species of the family Lactobacillaceae

“…Probiotics have proven to be a good strategy for the modulation of the human intestinal and vaginal microbiota, as well as to stimulate the systemic and mucosal immune response to prevent and treat infectious diseases (De Boeck et al, 2021 ; Håkansson et al, 2019 ; Spacova et al, 2023 ). Several authors reported the SLP's role in antimicrobial properties and immune activation.…”

A perspective current and past modes of inhalation therapy

“…Similarly, polymeric nanoparticles, solid lipid nanoparticles, and dendrimers are also being explored as inhalable drug carriers (Barthold et al., 2023). However, research in the field of probiotics, postbiotics, and their potential use in inhalers treatments, continues to expand (Spacova et al., 2023). The majority have been developed as suspension for nasal administration against SARS‐CoV, influenza ssp, streptococcus and pneumococcal infection (Table 2).…”