IMMUNE SYSTEM. What you need to know to understand it and how to improve it.
Much has been said lately about the immune system.
Without a doubt, and with the issue of covid-19, it is, now more than ever, the topic of the moment.
But what do we know about him?
Why does it keep giving us shocks and we don’t fully understand it?
In the following paragraphs we will try to explain in a relatively simple way a subject that is extremely complex and that still continues to give us surprises.
We will also make an approach so that you can help your immune system with vitamin supplementation supported by a scientific basis.
EVOLVING OVER MILLENNIA
The immune system represents hundreds of thousands of years of evolution and continuous improvement.
It has become more complex and adapted over time to function as an interconnected network at various levels.
But what is it basically?
It is a set of elements that combine with each other to create a defense structure similar to an army, where each component has a defined function.
We could imagine it as a kind of Google that learns at every moment.
In his incessant scanning work, he processes and saves information to try to protect us from pathogens.
We assume that most of our readers know what we mean, so we will make a short summary as a reminder.
The immune system is made up of molecules such as immunoglobulins, cytokines, and protein B7.
It also has specialized cell lines to a greater or lesser extent, with lymphocytes being placed at the pinnacle of improvement.
Then there are the lymphatic organs such as the thymus, bone marrow, nodes, etc.
Its main characteristic is that it acts in two ways:
- Automatically.
It is the so-called innate or non-specific immunity and is made up of genetically inherited information. - In a learned way.
Through this variant, which is known as specific or acquired immunity, it continuously collects data to update its registry of aggressors.
Another feature that makes it unique is the ability to activate the different phases of action as they are needed.
Like any intelligent and cybernetic system, it uses its resources efficiently.
THE THREE LINES OF DEFENSE
During an attack by a pathogen, the immune system will activate its three main lines of defense in a sequenced and coordinated manner.
The first line is made up of the skin and mucous membranes.
These are totally non-specific and act as a first input control.
Through their own physical mechanisms and secretions, they prevent the arrival of pathogens inside the body.
The second line of defense is formed by innate immunity, which will attack anything that represents aggression.
In this group we find phagocytes.
This non-specific system is not unique to humans, but is also found in plants and other animals.
Another characteristic of this line of defense is that it does not keep memory of the aggressors, it only has instructions to attack any foreign element to our body.
Specific or learned immunity is the third line.
Through this subsystem, pathogens are scanned and recognized from a database that is stored in the memory of specialized cells.
This subsystem is extremely complex as it can be interrelated with the other subsystems if necessary.
From here, the networks of action are becoming more and more intricate and that makes it a real challenge to be able to study it.
The most important feature of specific immunity is that it has memory and is unique to higher vertebrates.
For example, the surfaces of the mucous membranes are continuously exposed to an enormous number of microorganisms.
Some of them, such as commensal bacteria resident in the gut, coexist with the host in a mutually beneficial relationship, while others cause pathological infections.
The mammalian host relies on both innate and adaptive immunity to fight pathogen invasion, including virus infection.
During viral infections, the innate immune system uses pattern recognition receptors (PRRs) to trigger a rapid defense program to eliminate viruses while also directing appropriate adaptive immune responses .
HOW WE DEFEND OURSELVES AGAINST PATHOGENS
Attack systems are also differentiated according to the type of defense they will use and the level where the aggression has penetrated.
That is why we will have cell-mediated immunity and antibody-mediated immunity.
Cell-mediated immunity involves white blood cells, and within this group we can differentiate two levels.
If the non-specific barrier acts, the phagocyte group, which is made up of macrophages, neutrophils and dendritic cells, will be activated.
In addition, mast cells, eosinophils, basophils and natural killers can be added.
If immunity is specific, because it has already been passed to another level, lymphocytes, which are the most highly specialized cells, will be activated.
HOW TO KNOW THE STATE OF OUR IMMUNE SYSTEM
Cell-mediated immunity can be assessed by studying the levels of the various cell subpopulations in the blood that can be quantified by flow cytometry.
The percentages of T4 lymphocytes, activated T4, T8, activated T8, NK cells, among others, are studied.
With this, it is possible to assess what the cellular immune response is at the moment, and therefore what the patient’s reaction is to a bacterial or viral agent
Antibody-mediated immunity can be measured by immunological tests that specifically quantify plasma proteins, such as IgG, IgA, IgM, haptoglobin, C3, C4.
In the case of specific infections, the level of specific antibodies can also be evaluated
LATEST STUDIES SUPPORTING VITAMIN SUPPLEMENTATION FOR IMPROVED IMMUNITY
“Vitamin D is important for immune system function and vitamin D supplements have previously been shown to reduce the risk of viral respiratory tract infections,” Dr. Meltzer said.
“Our statistical analysis suggests that this may be true for COVID-19 infection.”
The cohort study conducted on 489 patients who had a vitamin D level measured in the year prior to COVID-19 testing, the relative risk of testing positive for COVID-19 was 1.77 times higher for patients with vitamin D deficient status compared to patients with sufficient vitamin D status, a difference that was statistically significant.
A wave of scientific publications has suggested that vitamin D3 supplementation could be a potentially promising and safe approach to reducing the risk of COVID-19 infections and deaths.
Meta-analyses of randomized clinical trials (RCTs) have shown that vitamin D3 supplementation reduces the risk of acute respiratory tract infections.
https://es.jamanetwork.com/journals/jamanetworkopen/fullarticle/2770157
Another study, vitamin D, inhibits the indiscriminate proliferation of B cells, blocks their differentiation and the secretion of immunoglobulins.
As it also affects the maturation of T cells into an inflammatory type, it facilitates the induction of regulatory T cells, resulting in decreased production of inflammatory cytokines such as IL-17 and IL-21.
This goes hand in hand with increased production of anti-inflammatory cytokines such as IL-10.
Vitamin D also has effects on monocytes and dendritic cells by inhibiting the production of inflammatory cytokines such as IL-1, IL-6, IL-8, IL-12, and TNFα.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406/
In addition, another study suggests that vitamin D could play a very important role in both the prevention and treatment of infection with the seasonal influenza virus .
Vitamin D would act as a modulator of the proliferation of Th cells and the production of cytokines.
This, at the same time, would stimulate regulatory T lymphocytes, which are responsible for anti-infectious action and limiting inflammatory processes.
One of the reports focused on the ability of 25(OH) vitamin D to stimulate regulatory T lymphocytes through the induction of antigen-presenting cells that expressed variations of the VDR and CYP27B1 genes.
Apparently, the significant form of vitamin D for the generation of regulatory T lymphocytes was free 25 (OH)D, that is, not bound to its transporter protein (DBP).
As a contrasting fact from this same study, inverse associations have been observed between vitamin D concentrations and disease activity in patients with inflammatory bowel disease, type 1 diabetes, multiple sclerosis, rheumatoid arthritis or autoimmune thyroiditis.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6121423/
As we can see, the incorporation of vitamins, such as Vitamin D , could be decisive in maintaining an immune system ready to fight against some aggressions.
In future articles we will go in more detail about the more specific functions of these cofactors.
The role of the resident microbiota on immunity
Humans are sometimes described as supraorganisms, serving as hosts for a collection of microorganisms referred to as “microbiota” at sites of the body exposed to the environment, and most of them reside in the gastrointestinal tract.
The dynamic interaction between humans and their microbiota and the impact of host-microbe mutualism on health and disease have been extensively reviewed.
It is estimated that at least 500 to 1000 species of bacteria inhabit the human gut, and they are estimated to contain 100 times more genes than the human genome.
Each individual person shares a core set of genes (a core microbiome) that carry out functions common to the human gut.
This functional core microbiome shared between individuals is enriched in genes involved in microbial adaptation to the host environment, as well as in the metabolism of biochemicals such as amino acids and glycans and in the biosynthesis of vitamins and organic compounds.
The gut microbiota is known to support respiratory immunity against influenza virus infection, but many questions remain about the role of the gut microbiota in the antiviral response.
THE VALUE OF NUTRITIONAL SUPPLEMENTS
We have been able to see that vitamin D supplementation in case of not having optimal levels in the blood is key to immunity.
On the other hand, the health of the intestinal microbiota is also important, which is why the use of probiotics can be another interesting strategy.
We have been able to see the role of the microbiota in the formation of innate and adaptive immunity and the maintenance of immune homeostasis, a growing number of studies have examined the therapeutic potential of commensal bacteria to modulate mucosal immune responses.
Probiotics are live microorganisms that can confer a health benefit to the host.
The most common probiotics include gut commensal bacteria such as Lactobacilli and Bifidobacteria.
Probiotics are sometimes used in combination with prebiotics, which are indigestible dietary supplements that selectively promote the growth of certain probiotics.
The combination of probiotics and prebiotics is known as “synbiotics.”
Oral intake of probiotics or synbiotics is capable of modulating the outcome of respiratory tract infections.
A systematic review evaluated the clinical evidence from 14 human randomized controlled trials (RCTs) on the use of probiotics and synbiotics for the prevention and treatment of respiratory tract infections, including the common cold.
A significant reduction in symptom severity and clinical course of disease is observed in five of six RCTs and three of nine RCTs that provided the relevant data, respectively.
In addition, several human clinical trials have shown that certain Lactobacillus potentiates vaccine-mediated immunity.
Lactobacilli form an important part of the commensal microbiota in the intestinal tract of humans and other mammals.
Recently, comparative analysis of human mucosal transcriptome responses has revealed that Lactobacillus species induced gene regulatory pathways important in immune responses, cell proliferation, and cytokine production.
In one study, daily consumption of a fermented dairy beverage improved antibody responses to flu vaccination in seniors over 70 years of age.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3659816/
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