Lactic acid bacteria and respiratory health: their beneficial effects on viral infections

JULIO VILLENA ; ALEXANDER SUVOROV; HARUKI KITAZAWA; SUSANA ALVAREZ

Lactic Acid Bacteria: Microbiological and Functional Aspects

CRC Press/Taylor & Francis Group

Lugar: Boca Raton; Año: 2019; p. 505 - 519

As we have reviewed here, research from the last decade has clearly demonstrated that beneficialmicroorganisms are able to modulate respiratory tract immunity and improve the resistance againstrespiratory viral infections. Studies in animal models have demonstrated that the mucosal priming(oral or nasal stimulation) with immunomodulatory LAB is able to improve the resistance againstrespiratory viruses, including IFV, RSV, and PVM. Moreover, it was recently reported that themodulation of the antiviral immune response by immunobiotic LAB could also reduce the severityof secondary bacterial respiratory infections.Studies evaluating the impact of immunomodulatory LAB on respiratory infections in humanshave reported controversial results. While some clinical studies have shown that immunobioticconsumption appears to be a feasible way to decrease the incidence of respiratory infections; otherworks have demonstrated a lack of evidence to support a beneficial effect of immunobiotics onrespiratory health (for recent reviews, see Wang et al. 2016; Amaral et al. 2017; Long et al. 2017).Due to the lack of confirmatory studies for some strains evaluated only in animal models and thevaried data available, more randomized, double-blind, and placebo-controlled trials in different agepopulations investigating immunobiotic dose response and different routes of administration, comparingimmunobiotic strains/genera, and elucidating the immunological mechanisms are necessary.The realization of appropriate clinical studies would be of fundamental importance to validate theresults obtained in animal models and to promote the massive use of immunobiotics as an effectivestrategy to improve respiratory health worldwide. These clinical studies should also be accompaniedby biotechnological developments in parallel, which allow efficient and low-cost administrationof immunobiotics such as nutritional supplements or nasal sprays.