The immune system is a complex network of cells, tissues, organs and the substances they produce that help the body defend itself against dangerous external agents and cellular alterations; its proper functioning is essential in order to defend us from pathogens and toxic substances.
New and interesting insights have been gained recently in this field.
In particular, important evidence has emerged that brings to light herbal remedies which, although still little known, act as excellent support for our defences.
In this article we will briefly describe how the immune system works and present two valid alternatives to the common natural remedies used to support it: the beta-glucans derived from the Shiitake mushroom and “postbiotics”.
- Innate and adaptive immune system
- Beta-glucans from the Shiitake mushroom
- Postbiotics - Lactococcus lactis subsp. Lactis JCM5805
Innate and adaptive immune system
We can credit the immune system with three fundamental tasks for our body1:
- fighting external pathogens that cause disease, such as bacteria, viruses, parasites or fungi;
- recognising and neutralising harmful substances from the environment;
- fighting cellular alterations, such as tumour cells.
The correct functioning of such a complex protection system is ensured by its division into two closely linked subsets that work in synergy with each other.
The innate immune system
It is the first protection mechanism to come into play in the event of danger, its response times are rapid and its action is the same towards all foreign substances. That is why it is also called the “non-specific” immune system.
It is made up of two components:
- skin and mucous membranes, which act as a physical barrier preventing bacteria and viruses from entering;
- immune cells, among which Macrophages and Natural Killer Cells stand out. Macrophages are able to engulf viruses and bacteria and digest them, rendering them harmless, while NK cells identify the cells that have been infected by a virus and destroy them.
The adaptive immune system
It comes into play if the innate immune system fails. It acts a little more slowly than the latter, as it must first recognise the pathogen. From that moment on it will have a targeted and specific response towards it every time it encounters it. For this reason it is also identified as the “specialised” immune system.
It is made up of three types of cell: T Lymphocytes, B Lymphocytes and Antibodies.
The first of these are divided into:
- T helper cells, which activate other immune cells through chemical messengers
- Cytotoxic T cells, which detect tumour cells or cells infected by viruses and destroy them
- Memory T cells. Once the infection has healed they remember the germ that was fought and, in the event of a second exposure, they will be ready to activate the immune system against it once again.
B Lymphocytes are activated by T helper cells and produce large quantities of antibodies specific to a given germ (antigen).
Antibodies, on the other hand, are proteins with carbohydrate groups that recognise and bind the corresponding specific antigens. In doing so, they render the pathogen bearing that specific antigen harmless. Furthermore, by binding to it, they guide the work of the phagocytes.
Innovative mushrooms and probiotics to support the immune system
We can now imagine how important it is to find innovative ingredients with all-round action on the immune defences, supporting the functionality of both innate and adaptive cells.
In recent times, numerous research projects have been carried out in this field in order to identify new functional actives for this type of need.
Particularly interesting are the beta-glucans of the Shiitake mushroom and a specific Lactobacillus with postbiotic action.
Beta-glucans from the Shiitake mushroom
The Shiitake Mushroom (Lentinula edodes (Berk.) Pegler) contains beta-glucans, particular substances able to positively influence the cells of our immune system.
Beta-glucans are glucose polymers joined by β-glycosidic bonds, naturally occurring in some cereals such as oats and barley, in yeasts and in mushrooms.
They can be divided into 2 types:
- beta-glucans found in cereals: they are glucose polymers joined by β (1 →3), β(1 →4) glycosidic bonds and are linear3
- beta-glucans from yeasts and mushrooms: they are characterised by β (1 →3), β (1 →6) glycosidic bonds that lead to the formation of side branches, which make the structure more complex3
Thanks to the presence of beta-1,3- beta-1,6 branches, the beta-glucans of medicinal mushrooms have a greater immune action2 than those found in cereals.
They are called Biological Response Modifiers (in English Biological Response Modifier or BRM) because they can promote the maturation of dendritic cells, the secretion of cytokines and regulate adaptive immune responses3
But how do beta-glucans manage to influence immune cells?
Beta-glucans are absorbed in the ileum2, where they are conveyed to the underlying lymphoid tissue, in which they can interact with macrophages and dendritic cells and stimulate the immune response.
The binding of beta-glucan to specific receptors on dendritic cells and macrophages triggers their activation and maturation, increases their antigen-presenting capacity and enhances the production of pro-inflammatory cytokines that have a stimulating activity on T helper cells and cytotoxic T lymphocytes4.
Furthermore, it seems that their activity may also influence the number of B Lymphocytes. This is what emerged from a study5 that was double-blind, crossover and placebo-controlled. Forty-two elderly subjects (both sexes, average age 71 years ±5) were randomly assigned to two groups given 2.5 mg/day of (1-3,1-6)-beta-glucan or placebo orally for 6 weeks; then, after a 4-week washout period, the reverse supplementation was administered for a further 6 weeks. This study showed a significant change in the number of circulating B lymphocytes in the group treated with (1-3,1-6) beta-glucan extract from Shiitake.
The effects of beta-glucans on the immune system have been the subject of scientific research on several occasions.
A review6 of as many as 34 randomised clinical trials, involving a total of 3,251 volunteer subjects, investigated the impact of the exclusive oral administration of fungal beta-glucans in any form and at any dosage on healthy subjects or patients.
The primary physiological outcome of most of the interventions was immunomodulation, which brought 2 benefits:
- a support of the immune defences, with a reduction in the incidence and the unwelcome effects linked to colds, flu and other respiratory infections;
- a benefit in terms of allergic reactivity.
Another noteworthy aspect is psychological wellbeing, since the cohorts that received the polysaccharides in question reported an improvement in their moods and an improvement in general wellbeing.
Therefore, on the basis of several pieces of scientific evidence, we can confirm the good tolerability of supplementation with fungal beta-(1 → 3,1 → 6)-d-glucans and its action in supporting the immune defences.
Postbiotic lactobacilli
Its full name is Lactococcus lactis subsp. Lactis JCM5805 and it is a heat-inactivated lactic acid fermenting bacterium that has been shown to be able to activate plasmacytoid dendritic cells (pDC), a particular subset of cells that can stimulate both the innate and the adaptive immune system.
Plasmacytoid dendritic cells are also called Interferon Producing Cells (IPC) because, when required, they produce large quantities of type I Interferon (IFN-I). The latter is made up of particular cytokines with multiple actions, including:
- triggering apoptosis in virus-infected cells7,
- promoting Natural killer cell-mediated cytotoxicity7,
- improving type 1 T helper cell responses, the generation of follicular T helper cells and humoral responses7.
Heat-inactivated (through pasteurisation) Lactococcus lactis subsp. Lactis JCM5805 can be referred to more simply as postbiotics.
In fact, postbiotics are defined by the International Scientific Association for Probiotics and Prebiotics (ISAPP) as “preparations of inanimate microorganisms and/or their components that confer a health benefit on the host”.
In a placebo-controlled clinical study, the efficacy of Lactococcus lactis subsp. Lactis JCM5805 was assessed on a total of 657 participants. Every day, for 12 weeks, the participants took a capsule containing around 100 billion cells or a placebo capsule. Significantly fewer days with discomfort such as sore throat and cough were observed, along with a significantly higher blood level of IFN-I in the JCM5805 group compared with the placebo group8.
Another scientific paper9 carried out a randomised, double-blind, placebo-controlled experiment to assess the effect of postbiotics on the onset of flu-like symptoms during the winter season. 213 volunteers were divided into two groups, which received yogurt containing L. lactis JCM5805 or a placebo drink every day for 10 weeks.
In the JCM5805 group, the cumulative incidence days of cough and fever were significantly reduced compared with the placebo group and the intensity grades of moderate and severe symptoms also decreased.
In addition, the volunteers’ peripheral blood mononuclear cells were cultured in the presence of inactivated human influenza virus A/H1N1 (A/PR/8/34). The level of IFN-α induced by A/H1N1 tended to be higher in the JCM5805 group than in the placebo group.
These results suggest that taking JCM5805 is able to act positively on flu-like discomfort by enhancing an IFN-α-mediated response to the influenza virus.
The two pieces of scientific evidence therefore confirm the immune-defence supporting action of Lactococcus lactis subsp. Lactis JCM5805.
In conclusion, we can state that research in the field of the immune system is making important progress with the discovery of innovative and noteworthy natural actives.
Shiitake mushroom beta-glucans and postbiotic Lactobacilli have clearly demonstrated a complete contribution to the support of our defences, with action on both the innate and the adaptive immune system.
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