Due to the current epidemic situation in the country and in the world, many of us devote much more attention to gaining knowledge about the immune system. Until now, it seemed to us that it is one of the naturally functioning elements that work together to protect us against bacteria or viruses.
Well, it is not the case that the immune system, although perfect in its integrated action and functionality, is not dependent on us. We have our share in its efficient or inefficient operation. We control many factors, such as diet, medications, stimulants, quantity and quality of sleep, or physical activity, which strengthens or weakens immunity. It is worth pointing out that there is no room for one-off or occasional outbursts such as “I switch to a healthy diet rich in vegetables and fruits” – for a week, “I start running” – for a week throughout the year, “I will sleep in retirement” … the life we provide to our body is very often far from the correct pattern. Although I believe that the time of isolation will bring many positive changes in this regard.
However, the purpose of this article is not to educate and account for any dietary mistakes or unfulfilled provisions, but to bring closer the difficult issue related to the functioning of the immune system and indicate the possibility of stimulating and modulating it positively, so that it can effectively fight a potential “enemy” in the event of a threat.
WHAT NATURE GIVEN US – NATURAL DEFENSE MECHANISMS
At the outset, it should be pointed out that the human body has many defense mechanisms against “intruders”. Science has divided these mechanisms into non-specific, which include, among others, sneezing reflex, sweat secretion, microbiome of the genitourinary system, tears, and specific response mechanisms, which consist of a number of elements related to the immune system, whose main task is to prevent the penetration of pathogens (bacteria, viruses, protozoa) into the body. The key line of defense here are the mucous membranes that line the ducts and the internal organs of the body, which are exposed to direct contact with bacteria, viruses, fungi and other parasites. To combat these factors, the human body has developed a complex system of mucosal-associated lymph tissue called MALT (Mucosal Associated Lymphoid Tissues), which is rich in cells of both innate and acquired immunity. The MALT system comprises the lymphoid tissue of the gastrointestinal tract and mucosa, especially in the intestine, ie the so-called GALT system (Gut Associated Lymphoid Tissues). This system is characterized by the highest immune activity and a high content of T and B lymphocytes. In the human body, about 80% of immunoglobulins are produced in the intestine and 50% of all lymphocytes.
DIGESTIVE SYSTEM AS A KEY ELEMENT IN PROTECTION OF THE BODY
The digestive tract of an adult, healthy person is inhabited by 400 different species of microorganisms covering 200-400 m2 intestinal epithelial surface. This heterogeneity of the intestinal microbiota is necessary for the proper functioning of the digestive tract, and the percentage and quality of bacteria in individual parts of the digestive system vary considerably.
Studies conducted on rodents devoid of gastrointestinal microorganisms have shown that the gut microbiome plays a very important role in many physiological processes in the intestines. Dysfunctions related to the lack of symbiotic microorganisms were associated with abnormal development of intestinal villi, defective morphology of enterocytes, or excessive mucus production. Scientific research has shown that introducing at least one strain of bacteria, e.g. of the Bactero species, into the artificially sterilized digestive systemyou are fragile significantly corrects the defects of the immune system. Other scientific works indicate that selected strains of Lactobacillus acidophilus show the ability to synthesize substances that inhibit the growth of Hel bacteriaicobacter pylori. It is worth pointing out that Symbiotic microorganisms, i.e. those inhabiting the digestive system, due to their metabolic potential (production of organic acids, bacteriocins, enzymes) prevent or significantly limit the development of pathogenic microorganisms.
Importantly, bacteria naturally colonizing the human gastrointestinal tract do not induce an inflammatory response and are not treated as pathogenic microorganisms that are classified by the immune system as “destructible”.
The organism has developed many mechanisms that allow to protect the mucous membranes, maintain homeostasis and trigger immune reactions at the time of infection with pathogenic microorganisms. However, pathogen cells have developed mechanisms to trick the cells of the immune system, allowing them to bypass defense mechanisms and penetrate into the host’s organism, which may lead to health dysfunctions. Hence, it is necessary to support protective mechanisms. One of the indications is the systematic intake of probiotic preparations.
PROBIOTICS AIDS TO COMBAT PATOGENS AND IMMUNITY TRAINERS
A good direction to strengthen the immune response is to support the body with an additional portion of “helpers” (learn more). Microorganisms with probiotic potential can play this role. Reports from world literature indicate that probiotics can stimulate and modulate the body’s internal defense mechanisms and affect the tightness of the intestinal barrier. One example is bacteria of the species Lactobacillus rhamnosus i Lactobacillus reuteriwhich were administered to children with atopic dermatitis and the indicators that indicated a reduction in the permeability of the intestinal barrier were analyzed. It has also been shown that probiotics inhibit hypersensitivity reactions to certain antigens, e.g. food antigens. Systematic admission Lactobacillus casei i Lactobacillus acidophilus increases the phagocytic (prey) activity of macrophages, a mechanism that is important when cells remove toxic compounds from the digestive system. Hence, it is important that the probiotic microorganisms supplemented with the diet should be characterized by good vitality and resistance to environmental stress prevailing in the digestive tract. Probiotics can initiate the repair of intestinal barrier function following damage from various pathological conditions and prevent the cytokine-induced epithelial damage that is characteristic of inflammatory bowel conditions. Probiotic microorganisms can also block the pathogen’s entry into the intestinal epithelial cells by increasing the mucus barrier (mucin production) and intercellular integrity. Another epidemiological problem associated with the effects of probiotics is viral infections, which often affect children. The immune system of the youngest has not yet been fully developed and the defense mechanisms are unable to cope with the attack of rotaviruses. Many literature reports indicate a positive effect of using probiotics from the species Lactobacillus rhamnosus GG, Bifidobacterium bifidum, Streptococcus thermophilus or Bifidobacterium lactis in preventing diseases of viral etiology. Another mechanism linking probiotics to the immune system is related to two chronic diseases like ulcerative colitis and Crohn’s disease. There are many hypotheses indicating the causes of these dysfunctions. They mainly concern genetic factors, diet, dysbiosis or abnormalities in lymphatic tissues. Often, “damaged” (by genetic or environmental factors), the immune system reacts against the host, generating the chronic inflammation associated with Crohn’s disease. Research shows that the participation of microorganisms in this dysfunction is very important. It has been shown that in this disease the quantitative and qualitative composition between bacteria of the species is disturbed Escherichia coli and with kind Bacterioides compared to those of the genus Lactobacillus i Bifidobacterium, to the quantitative disadvantage of the latter. Certain strains of probiotic bacteria have been shown to reduce the production of inflammatory mediators (such as IL-6 and TNF-α) when exposed to pro-inflammatory compounds such as lipopolysaccharide (LPS) in intestinal epithelial cells. A similar mechanism was also observed outside the digestive system, and it concerned the reduction of pro-inflammatory biomarkers in the plasma of patients whose diet was supplemented with bacteria of the genus Bifidobacterium. Another mechanism that binds probiotic bacteria with the immune system is the stimulation of TLR receptors (Toll-Like Receptors). Proteins belonging to this family are expressed in various cells of the immune system, which recognize specific patterns of microbial structures (including pathogens) and regulate the activation of innate and acquired immunity.
To sum up, the human immune system is influenced by many factors and relationships that are closely related to the digestive system, and above all, with the microorganisms that live in it. The key factor in these relationships of probiotic microorganisms is that they significantly influence the modulation and stimulation of the body’s immunity. What is important and consistent for all the above-described mechanisms of action is the fact that in the pro-immunological effect of probiotics, it is very important not only to select the right dose of microorganisms, but also to differentiate between strains and species (multi-strain preparations, polyprobiotics), the form of the probiotic and systematic use of them (see also).
Authors: Prof. UPP dr hab. Daria Szymanowska, Prof. dr hab. Judyta Cielecka-Piontek
Bibliography available from the author of the text: [email protected]
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