A randomized, double-blind, placebo-controlled study was conducted to evaluate if Lactobacillus helveticus Lafti L10 (Lallemand Health Solutions, Montreal, Que., Canada) supplementation during 14 weeks in winter can influence the duration, severity, and incidence of upper respiratory tract illness (URTI), as well as to monitor different immune parameters in the population of elite athletes. Before and after the treatment, cardiopulmonary testing and self-rated state of moods evaluation (by Profile of Mood States questionnaire) were performed and blood samples were collected. Thirty-nine elite athletes were randomized either to the placebo (n = 19) or the probiotic (n = 20) group. The probiotic group received L. helveticus Lafti L10, 2 × 10¹⁰ Colony Forming Units. Lafti L10 significantly shortened the URTI episode duration (7.25 ± 2.90 vs. 10.64 ± 4.67 days, p = 0.047) and decreased the number of symptoms in the probiotic group (4.92 ± 1.96 vs. 6.91 ± 1.22, p = 0.035). Severity and incidence of URTI did not differ between the treatments. There were no significant changes in leukocyte subpopulation abundance, transforming growth factor-β serum levels, level of interleukin-10 secreted from peptidoglican stimulated peripheral blood mononuclear cells (PBMCs), interferon-γ level secreted from concanavalin A-stimulated PBMCs or viability/proliferation of PBMCs upon antigen stimulation. Group effect for CD4+/CD8+ ratio was significant (F_[1,37] = 6.99, p = 0.020, η² = 0.350); this difference was not significant at baseline, but was evident after 14 weeks (p = 0.02). A significant interaction effect was noted for self-rated sense of vigor (F_[1,37] = 11.76, p = 0.009, η² = 0.595). Self-rated sense of vigor increased in the probiotic group (18.5 ± 4.1 vs. 21.0 ± 2.6, p = 0.012). Probiotic strain Lafti L10 can be a beneficial nutritional supplement for the reduction of URTI length in elite athletes.

Tuberculosis (TB) remains among the most deadly diseases in the world. The only available vaccine against tuberculosis is the bacille Calmette-Guérin (BCG) vaccine, which does not ensure full protection in adults. There is a global urgency for the development of an effective vaccine for preventing disease transmission, and it requires novel approaches. We are exploring the use of lactic acid bacteria (LAB) as a vector for antigen delivery to mucosal sites. Here, we demonstrate the successful expression and surface display of a Mycobacterium tuberculosis fusion antigen (comprising Ag85B and ESAT-6, referred to as AgE6) on Lactobacillus plantarum . The AgE6 fusion antigen was targeted to the bacterial surface using two different anchors, a lipoprotein anchor directing the protein to the cell membrane and a covalent cell wall anchor. AgE6-producing L. plantarum strains using each of the two anchors induced antigen-specific proliferative responses in lymphocytes purified from TB-positive donors. Similarly, both strains induced immune responses in mice after nasal or oral immunization. The impact of the anchoring strategies was reflected in dissimilarities in the immune responses generated by the two L. plantarum strains in vivo . The present study comprises an initial step toward the development of L. plantarum as a vector for M. tuberculosis antigen delivery. IMPORTANCE This work presents the development of Lactobacillus plantarum as a candidate mucosal vaccine against tuberculosis. Tuberculosis remains one of the top infectious diseases worldwide, and the only available vaccine, bacille Calmette-Guérin (BCG), fails to protect adults and adolescents. Direct antigen delivery to mucosal sites is a promising strategy in tuberculosis vaccine development, and lactic acid bacteria potentially provide easy, safe, and low-cost delivery vehicles for mucosal immunization. We have engineered L. plantarum strains to produce a Mycobacterium tuberculosis fusion antigen and to anchor this antigen to the bacterial cell wall or to the cell membrane. The recombinant strains elicited proliferative antigen-specific T-cell responses in white blood cells from tuberculosis-positive humans and induced specific immune responses after nasal and oral administrations in mice.

In this study, two Lactobacillus strains (L. rhamnosus LA68 and L. plantarum WCFS1) were evaluated for their effects on high fat diet induced pathology in mice. The aim was to determine whether the administration of lactic acid bacteria had beneficial effects on ameliorating pathology. C57BL/6 mice fed a high fat diet were orally administered with the Lactobacillus strains. Both the metabolic and immunological parameters were analyzed. The administration of both of the strains had beneficial effects on mouse weight, serum cholesterol, TNF-α levels and liver histology. LA68 lowered the total cholesterol and HDL levels more prominently, whereas WCFS1 was more potent in lowering the TG and LDL levels. Leptin and adiponectin levels were increased in all experimental groups to different extents. The administration of L. plantarum WCFS1 led to a marked increase in leptin levels, as well as an increase in CD3+CD4+ and CD3+CD8+ cells, and a decrease of CD25+ cells, and had a lowering effect on IL-6 production and cell metabolic activity. In conclusion, active administration of both Lactobacillus strains had a positive effect on HFD-induced pathology. Although both of the tested strains had beneficial effects, oral administration of WCFS1 increased leptin levels and had a more prominent immunomodulatory effect, which should be taken into consideration in case of humane usage.

The enzyme-linked immunosorbent assay (ELISA) is a commonly used analytical immunochemistry assay based on the specific bond between the antigen and the antibody. The application of this test has significantly changed the practice of medical laboratories in which it is used for detection and quantification of molecules such as hormones, peptides, antibodies, and proteins. Various technical variants of this test can detect antigen (native or foreign) or antibody, determine the intensity of the immune response whether pathological or not; the type of induced immune response as well as the innate immunity potential; and much more. These capabilities, as well as the high sensitivity and robustness of the test and a small price, make it possible to quickly and reliably diagnose diseases in most laboratories. Besides, ELISA is a test that is also used in veterinary medicine, toxicology, allergology, food industry, etc. Despite the fact that it has existed for almost 50 years, different ELISA tests with different technical solutions are still being developed, which improves and expands the application of the this exceptional test. The aim of this chapter is to empower the rider to optimize, standardize and validate an enzyme linked immunosorbent assay.