Ageing, immunity and influenza: a role for probiotics?

Abstract

Influenza is a major cause of death in the over 65s. Increased susceptibility to infection and reduced response to vaccination are due to immunosenscence in combination with medical history and lifestyle factors. Age-related alterations in the composition of the gut microbiota have a direct impact on the immune system and it is proposed that modulation of the gut microbiota using pre- and probiotics could offer an opportunity to improve immune responses to infections and vaccination in older people. There is growing evidence that probiotics have immunomodulatory properties, which to some extent are strain-dependent, and are strongly influenced by ageing. Randomised controlled trials suggest that probiotics may reduce the incidence and/or severity of respiratory infections, although there is limited data on older people. A small number of studies have examined the potential adjuvant effects of selected probiotics for vaccination against influenza; however, the data is inconsistent, particularly in older people. This review describes the impact of age-related changes in the gut on the immune response to respiratory infections and evaluates whether restoration of gut microbial homoeostasis by probiotics offers an opportunity to modulate the outcome of respiratory infections and vaccination against influenza in older people. Although there is promising evidence for effects of probiotics on human health, there is a lack of consistent data, perhaps partly due to strain-specific differences and an influence of the age of the host. Further research is critical in evaluating the potential use of probiotics in respiratory infections and vaccination in the ageing population.

Enhancing the natural killer cell activity and anti-influenza effect of heat-treated Lactobacillus plantarum nF1-fortified yogurt in mice

“…In previous reports, daily uptake of yogurt or fermented milk resulted in the compositional change of human gut microbiome (Unno et al, 2015;Lisko et al, 2017). Interestingly, changes in microbiome have been reported to modulate IAV infection (Ichinohe et al, 2011;Yaqoob, 2014;Chen et al, 2017a;Yitbarek et al, 2018). As gut microbiota are also suggested to play an important role in the development and function of lymphoid cells, including NK cells (Kamada and Núñez, 2013;Aziz and Bonavida, 2016), nF1-fortified yogurt may induce immunological responses enhancing the NK cell activity and exhibit both protective and prophylactic effects against IAV infection by changing gut microbiome composition.…”

Probiotics - the versatile functional food ingredients

“…In a particular study, it was found that when neonatal and infant mice were administered with Lactobacillus casei Shirota by stomach tube for 3 weeks prior to infection with influenza; the mice demonstrated a lower rate of accumulated symptoms, a greater survival rate and lower titres of influenza in nasal washings taken a few days after infection. These correlated with an increase in NK cell activity and production of IL-12 (Yaqoob 2014). iii.…”

“…In general, lactobacilli tend to fall in the immunostimulatory category, whereas bifidobacterium tend to fall in the immunoregulatory category (Yaqoob 2014).…”

Probiotics and Its Potential Role in Poultry Production: A Review

“…Probiotics have the capability to enhance the immune system by increasing the phagocytic capacity of macrophages, enhancing natural killer cell activity, stimulating immunoglobulin A (IgA) production, and modulation of cytokine production. 44,45…”