Protective effect of intranasally inoculatedLactobacillus fermentumagainstStreptococcus pneumoniaechallenge on the mouse respiratory tract

Abstract

Lactic acid bacteria are increasingly used to restore the ecological equilibrium of different mucosal areas in humans and/or animals. Likewise, they can be used to potentially protect against pathogenic microorganisms. In the present paper, the preventive effect of intranasally inoculated Lactobacillus fermentum against challenge with Streptococcus pneumoniae was studied, using a mouse experimental model. L. fermentum inoculated four times at a dose of 10(7) colony forming units per mouse was able to decrease the number of S. pneumoniae throughout the respiratory tract. The L. fermentum treatment increased the number of activated macrophages in lung slices, and a higher lymphocyte population in the tracheal lamina propria. S. pneumoniae challenge showed a typical response against pathogen with a higher non-specific immune response. Preventive treatment, i.e. L. fermentum administration prior to S. pneumoniae challenge, showed a response close to that of L. fermentum. Anti-S. pneumoniae antibodies increased in lactobacilli-treated animals compared to the non-treated lactobacilli mice. The increase in the antibody levels suggests that the mucosal immune system could be involved in the protective effect, accomplished with competitive exclusion, nutrient competition and production of inhibitory substances. This paper will be the basis for further studies of the protective effect of lactobacilli against S. pneumoniae in the respiratory tract.

Host immunity in the protective response to nasal immunization with a pneumococcal antigen associated to live and heat-killed Lactobacillus casei

“…At present, very few adjuvants have been approved for clinical use [35], which could be partly due to the cost of development and to the regulatory restrictions imposed on vaccine adjuvants [36] to ensure their effectiveness and safe application to humans. In this sense, LAB are attractive candidates as potential adjuvants, since they are generally recognized as safe and some of them have been proved to have intrinsic adjuvant properties when administered through the mucosal route to prevent respiratory infections [18,20-22]. Our purpose was to assess the adjuvant effect of a specific live and dead probiotic strain when it is associated with a pneumococcal antigenic protein.…”

“…Moreover, non-engineered microorganisms have greater acceptability by the general population than genetically modified ones. Previous reports showed that nasally administered specific lactobacillus and lactococcus strains were able to improve the protective immune response against S. pneumoniae [18,19,40,41]. Thus, Cangemi de Gutierrez et al [18] demonstrated that the intranasal administration of L. fermentum isolates from the pharynx of BALB/c mice was able to activate macrophages in the respiratory tract and reduced nasal and lung colonization of S. pneumoniae .…”

“…The potential application of a recombinant strain in humans still presents aspects that need to be resolved such as elimination of antibiotic resistance genes, production of recombinant strains in a controlled system, safety of its application to children and immunosuppressed individuals and cost-benefit evaluation of its production, especially in developing countries. In the last few years, the use of some LAB strains in the prevention of respiratory infection has become more evident [18-21]. In this sense, the oral and nasal administration of live Lactobacillus casei CRL 431 ( L. casei ), a probiotic strain, was able to improve the immune response of the host against respiratory pathogens in a mouse model.…”

“…In this sense, the oral and nasal administration of live Lactobacillus casei CRL 431 ( L. casei ), a probiotic strain, was able to improve the immune response of the host against respiratory pathogens in a mouse model. The effect of L. casei was associated with the stimulation of the innate and adaptative immune response [18,20-22]. In addition, some studies have demonstrated that non-viable lactobacilli also have immunostimulant properties in both humans and animals [23-25], so their use in nasal vaccines is an interesting point to asses.…”

Evolution of the Human Microbiome and Impacts on Human Health, Infectious Disease, and Hominid Evolution

“…Mice were protected against Bordetella pertussis (whooping cough or pertussis) infection if given a single dose of a commensal nasal cavity microorganism prior to infection . Similarly, streptococcal and staphylococcal infections can also be minimized or avoided entirely if probiotics and commensal microorganisms are given to mice before they were infected (Cangemi de Gutierrez et al 2001;Gonzalez et al 2011). Young mice can also be protected from other non-infectious diseases, such as respiratory allergies, when first given commensal microorganisms found in dust (Fujimura et al 2014), suggesting that obtaining bugs from our environments may be important to prevent many common Western diseases, such as obesity, allergies, and Type II diabetes.…”