The intestinal microbiome is a complex signalling hub that incorporates environmental factors, such as diet, stress and xenobiotics, with genetics and immune signals to influence host immunity and response to infection.[1-3] Within the last decade, we have begun to understand the importance of this interdependent bilateral interaction between the host and its microbiota and how its mutually beneficial balance is crucial in host defence and immune health.
Dysbiosis, the term used to describe commensal microbial imbalance, plays a role in the pathogenesis of common gastrointestinal tract (GIT) complaints and acute upper respiratory tract infections (URTIs). It is also considered a causative factor in extraintestinal inflammatory and autoimmune disorders such as inflammatory bowel disease, and is suspected to contribute to the progression of pulmonary disease and atopic conditions.[1,2] The mechanisms that are involved in the crosstalk between the microbiome and our immune system need to be tightly controlled, in order to avoid the aberrations that contribute to the aetiology of common multifactorial disorders.
One way in which to help influence a positive benefit for immunity host-microbiome mutualism, is to support microbial balance via certain probiotic strains. Saccharomyces boulardii (SB), Lactobacillus acidophilus, L. casei, L. plantarum, L. rhamnosus, Bifidobacterium bifidum, B. breve, B. longum, B. lactis and Streptococcus thermophilus have shown to help either balance disturbed intestinal microflora, the related dysfunction of the GIT, and in turn, positive support for immune function and health.[6-11]
A daily intake of B. bifidum and B. infantis has demonstrated a reduction in the frequency of cold and flu during periods of acute stress for undergraduate students. L. acidophilus and L. casei have been shown to adhere to the intestinal mucosa and may block the adherence of enteropathogens which threaten immune health. L. plantarum is most often associated with antimicrobial bacteriocin production, which reduces the survival of competing pathogens.
SB is an extensively researched antibiotic-resistant strain of yeast that has shown probiotic effects through maintaining healthy gastrointestinal immunity, with particular relevance for antibiotic-associated diarrhoea, recurrent Clostridium difficile intestinal infections, Candida albicans attachment-inhibition and reduction of pro-inflammatory mediators in the digestive system.
In the urogenital tract, lactobacilli species such as L. rhamnosus, help to maintain healthy immunity by reducing the overgrowth of less desirable species, working synergistically with various proteins that protect the host from pathogens, including lactoferrin.
As our bodies are inhabited by a large number of microorganisms that reside on various surfaces including the skin, gastrointestinal, respiratory and urogenital tracts, it is essential to help cultivate a symbiotic relationship that benefits whole-organism physiology and immune health.
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- Langkamp-Henken B, Rowe CC, Ford AL, et al. Bifidobacterium bifidum R0071 results in a greater proportion of healthy days and a lower percentage of academically stressed students reporting a day of cold/flu: a randomised, double-blind, placebo-controlled study. Br J Nutr 2015;113(3):426-434.[Abstract]
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- Valenti P, Rosa L, Capobianco D, et al. Role of lactobacilli and lactoferrin in the mucosal cervicovaginal defense. Front Immunol 2018;9:376.[Full Text]