Corresponding author: Andrii Demkovych (
In the article was studied the effects of flavonol quercetin on indices of adaptive immune response in experimental animals on the 14th day of the experimental bacterial-immune periodontitis development. Indices of immune protection were determined by the relative number of lymphocytes with CD3+, CD4+, CD8+, CD19+, CD16+ and immunoregulatory index (CD4+ / CD8+) in intact animals and on the 14th day of inflammatory process development in periodontal tissues as well as the therapeutic effects of flavonol quercetin. As a result of the study, characterized changes associated with the activity of both the cell-mediated and humoral-immune response were found, both in the development of experimental periodontitis, and apply of flavonol. In particular, there was an increase in the animal’s blood relative amount of CD8+, CD16+ cells on the 14th day, and content of CD3+, CD4+, CD19+ was decreased. In this case, the immunoregulatory index (CD4+ / CD8+) as an important index of immunological activity was decreased. The apply of flavonol quercetin in the period development of bacterial-immune periodontitis animals functional activity of the T-cell line of the immune system was increased, as evidenced percentage increase of B- and T-cells due to T-helper cells decrease as well as T-killers content during this period of inflammatory reaction in the periodontal complex, in comparison with animals, which were not treated.
Inflammatory diseases of periodontal tissues are widespread in the world. The etiology and pathogenesis of periodontal diseases are complicated, insufficiently elucidated and one of the important problems of theoretical and practical medicine (
Research of membrane receptors of lymphocytes at different stages of their development, differentiation, activation, cellular proliferation, and apoptosis is a modern informative, objective and accessible method which is used with scientific, diagnostic, therapeutic and prognostic purpose (
Treatment of periodontitis does not require ordinary approaches to their decisions. In this regard, the effectiveness of plant origin substances, which are related to polyphenolic compounds that are able to modulate immune response as well as inflammatory process in the organism, have not been studied.
Quercetin is referred to flavonols with antioxidant, anti-ischemic, membrane-stabilizing and immunomodulatory properties (
Objective. To determine effects of the flavonol quercetin to adaptive immunity in respect of the experimental bacterial-immune periodontitis development.
The study was conducted on white, clinically healthy male rats weighing 150–200 g under vivarium conditions. The animals were in a standard diet balanced with basic nutrition elements, with free access to water. Experiments were carried out in compliance with the general rules and regulations of the “European Convention for the Protection of Vertebrate Animals used for Research and Other Scientific Purposes” (Strasbourg, 1986), “General Ethical Principles of Animal Experiments” (Kyiv, 2001). Experimental animals were divided into three groups: the first group – intact animals (n = 10); the second group – animals with experimental periodontitis on the 14th day of the study (n = 8), and third group – animals with experimental periodontitis on the 14th day of the study, which was treated by quercetin (n = 8).
Experimental bacterial-immune periodontitis in experimental animals was caused by the introduction into the tissues of the periodontal complex of a mixture of microorganisms diluted with egg protein (
It has been established that development of experimental bacterial-immune periodontitis occurs in accordance with changes in the cell-mediated and humoral levels of adaptive immune defense. Analysis of the immune status in rat’s blood with periodontitis showed that quercetin is able to change the activity of the cellular –mediated immune response (Table
The therapeutic use of this flavonol caused increase of common mature T-lymphocytes (CD3+) by 1.43 times (p<0.01), as compared with the animals group that were not treated by this drug (Fig.
Indices of adaptive immunity response in the experimental animals with periodontitis and treatment by quercetin (M ± m).
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Experiment duration (days) | – | 14 | 14 |
Number of the animals | 10 | 8 | 8 |
CD3+, % | 45.94±0.73 | 27.07±0.58 p1<0.01 | 38.65±0.61 p1<0.01; p2<0.01 |
CD4+, % | 33.32±0.56 | 21.73±0.48 p1<0.01 | 30.11±0.81 p1<0.05; p2<0.01 |
CD8+, % | 15.70±0.74 | 25.46±0.45 p1<0.01 | 20.79±0.93 p1<0.01; p2<0.01 |
CD19+, % | 11.65±0.39 | 8.23±0.27 p1<0.01 | 10.14±0.27 p1<0.05; p2<0.01 |
CD16+, % | 9.63±0.40 | 13.62±0.19 p1<0.01 | 10.79±0.26 p1<0.05; p2<0.01 |
Dynamics of the content of common mature T-lymphocytes in the rat’s blood on the 14th day of the research in conditions of experimental bacterial-immune periodontitis development and treatment by quercetin (% of control). Notes: * – significant of differences in relation to the intact animals (p<0.01); # – significant of differences in relation to the animals with periodontitis on the 14th day of the experiment without treatment (p<0.01).
In a result of the experimental bacterial-immune periodontitis development after quercetin treatment during 7 days was observed on the 14th day significant increase in the blood of the T-helper cell content (CD4+), in comparison with the same term in animals without administration of the drug (by 1.39 times; p<0.01). At the same time, the content of T-helper cells in the blood of the studied group remained low (Fig.
Immunoregulatory index in the experimental animals with periodontitis and treatment by quercetin (M ± m).
Experiment conditions and indices | Control, intact animals | Animals with experimental periodontitis | |
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Without treatment | After treatment by quercetin | ||
Experiment duration (days) | – | 14 | 14 |
Number of the animals | 10 | 8 | 8 |
СD4+ / СD8+ | 2.17±0.11 | 0.85±0.03 p1<0.01 | 1.44±0.12 p1<0.01; p2<0.01 |
Dynamics of the content of T-helpers in the rat’s blood on the 14th day of the research in conditions of experimental bacterial-immune periodontitis development and treatment by quercetin (% of control). Notes. * – significant of differences in relation to the intact animals (p<0.01); ● – significant of differences in relation to the intact animals (p<0.05); # – significant of differences in relation to the animals with periodontitis on the 14th day of the experiment without treatment (p<0.01).
The introduction of flavonol antioxidant resulted significant changes of the T-effectors (CD8+) content that perform both killer and suppressor functions in the blood of experimental animals with bacterial-immune periodontitis. Quercetin effectively changed the course of the inflammatory process in the periodontal tissues, but as well reduced level of CD8+ in the blood (by 1.23 times; p<0.01) in relation to animals with experimental periodontitis on the 14th day without treatment (Table
Dynamics of the content of T-effectors in the rat’s blood on the 14th day of the research in conditions of experimental bacterial-immune periodontitis development and treatment by quercetin (% of control). Notes. * – significant of differences in relation to the intact animals (p<0.01); # – significant of differences in relation to the animals with periodontitis on the 14th day of the experiment without treatment (p<0.01).
There was significant increase of the immunoregulatory index (CD4+ / CD8+) in the experimental animals treated by quercetin, as compared with the animals on the same research term but without drug administration (by 1.69 times, p<0.01) (Table
At the same time, this indices of the studied animal group remained at a rather low level (Fig.
Dynamics of immunoregulatory index on the 14th day of the research in conditions of experimental bacterial-immune periodontitis development and treatment by quercetin (% of control). Notes. * – significant of differences in relation to the intact animals (p<0.01); # – significant of differences in relation to the animals with periodontitis on the 14th day of the experiment without treatment (p<0.01).
Regarding the influence of this flavonol on the parameters of general B-lymphocytes (СD19+) in the blood of experimental animals with periodontitis it should be noted that quercetin increased their content (by 1.23 times, p<0.01), as compared with animals on the 14th day, which were not treated by quercetin (Table
Dynamics of the common B-lymphocytes content in the rat’s blood on the 14th day of the research in conditions of experimental bacterial-immune periodontitis and treatment by quercetin (% of control). Notes. * – significant of differences in relation to the intact animals (p<0.01); ● – significant of differences in relation to the intact animals (p<0.05); # – significant of differences in relation to the animals with periodontitis on the 14th day of the experiment without treatment (p<0.01).
As it was established in our previous studies, on the 14th day of the inflammatory process development in the periodontal complex, the natural killers (NK-cells, CD16 +) content in the blood was increased by 41.43% (p<0.01), as compared with control animal group. The use of flavonol quercetin with the immunomodulatory effect resulted to decrease of the NK-cells content (by 1.26 times; p<0.01) in blood, with respect to the same parameters of the animal group that were not treated (Fig.
Dynamics of the natural killers content in the rat’s blood on the 14th day of the research in conditions of experimental bacterial-immune periodontitis development and treatment by quercetin (% of control). Notes. * – significant of differences in relation to the intact animals (p<0.01); ● – significant of differences in relation to the intact animals (p<0.05); # – significant of differences in relation to the animals with periodontitis on the 14th day of the experiment without treatment (p<0.01).
An analysis of the changes peculiarity in the cellular level of adaptive immunity for the experimental bacterial-immune periodontitis has been carried out, which will contribute to deepening the essential understanding of the inflammatory process development and search of pathogenetic treatment (
The general assessment of the immune status of rats with experimental bacterial-immune inflammation in the tissues of the periodontal complex showed that the degree and direction of changes in all its parts were different. It is known that T-lymphocytes, which recognize antigens with the participation of cellular receptors, play a key role in immune responses.
Regarding the changes in the content of T-effectors, which perform the functions of both killers and suppressors (CD8+), their number in the blood of animals under these experimental conditions increased. It is these cells that suppress the activity of cellular and humoral immunity, influencing the mechanisms of intercellular interaction. Their presence in the blood in the acute phase of the inflammatory process indicates the activation of immunological reactivity in response to antigenic stimulation. The consequence of a decrease in the content of T-helpers and an increase in the content of T-suppressors in the blood of experimental animals were changes in the immunoregulatory index (CD4+ / CD8+). The obtained results indicate the appearance of an immunosuppressive state in rats under the condition of bacterial-immune periodontitis, which developed in the late period of the inflammatory reaction due to both T-helpers and cytotoxic T-suppressors / killers. Quantitative and qualitative changes in lymphocytes and monocytes occur within certain limits, which allows to maintain “cellular homeostasis”, but at the same time respond sharply to any adverse environmental influences.
The antioxidant activity of the drug is related to its ability to suppress lipid peroxidation, reduce the concentration of free radicals and toxic peroxidation products, and activates catalase and superoxide dismutase activity (
Therapeutic use of this flavonol led to an increase in the content of all mature T-lymphocytes (CD3+), an increase in the content of the helper fraction of the cellular immune system (CD4+) in the blood, a decrease in CD8 +, an increase in the immunoregulatory index (CD4+ / CD8+) in animals without drug administration. Regarding the effect on the content of B-lymphocytes (CD19+) in the blood of experimental animals with periodontitis in this model of the inflammatory process, it should be noted that quercetin increased their content compared with animals on the 14th day who did not receive the drug. Therefore, the use of flavonol quercetin contributes to the normalization of a number of indicators of humoral immune protection and cytokine spectrum.
Development of a destructive inflammatory process in the periodontal complex due to bacterial and immune factors is accompanied by decrease in the blood of active T-lymphocytes, T-helpers, B-lymphocytes content as well as increase of the T-killer and NK-cells.
The application of the flavonol quercetin for the bacterial-immune periodontitis development promotes the normalization of the cellular adaptive immunity indices and reversion of the inflammatory process in the periodontal complex.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.