The relevance of this study is associated with the rapid development of cosmetological procedures in aesthetic medicine [1][2]. Injection techniques have entered into active use and established themselves as a leading choice in instrumental cosmetology [3][4][5]. In particular, mesotherapy is popular for correcting age-related changes in the skin of the face and the body associated with senescence [6][7]. Skin aging is stipulated by both structural and functional changes, and the capability of correcting skin quality with peptide mesotherapy deserves careful consideration [8][9]. From the persistent clinical effect after using peptide mesotherapy cocktails logically follows the assumption about the impact of peptide complexes on the functional potential of immunocompetent cells and the homeostasis of the body as a whole [10]. However, there are no literature data characterizing the indicators of the innate and adaptive immune responses that arise in reply to the injection of peptide complexes for aesthetic purposes.

The purpose of the study was to investigate changes in the functioning of the immune system prior to a mesotherapy course with peptide complexes and in 3 and 6 months after its accomplishment.

The observation group consisted of 26 women (from 35 to 55 years old), who for the first time received a course of mesotherapy procedures with drugs containing peptides. Exclusion criteria were carrying out the same manipulations in the past, hormone replacement therapy, administration of combined oral contraceptives, pregnancy, lactation, acute infections, and somatic pathologies.

The course of mesotherapy was carried out with an interval of 14 days and consisted of 5 procedures. The Hydro Line Extra NucleoSpire Revitalizing complex B was used, the composition of which was represented by vitamins (B1, B2, B3, B4, B5, B6, B8, B9, H), L-amino acids (alanine, arginine, asparagine, glutamine, glutamic acid, glycine, histidine, cysteine, cystine, leucine, lysine, phenylalanine, methionine, proline, valine, tryptophan, serine, threonine), glutathione, micronutrients (Mg, Mn, Ni, Co, Zn, Cu, and Mo), unstabilized hyaluronic acid of biosynthetic origin, and buffer system.

Along with assessing the clinical effect, the parameters of the innate and adaptive immune responses, based on the assessment of markers CD3, CD4, CD8, CD16, CD19, CD25, and intracellular content of FoxP3, were investigated prior to the procedure course, right after its accomplishment, as well as in 3 and 6 months after the procedure accomplishment. The oxygen-dependent metabolic activity in neutrophils was assessed with the NBT test. The content of serum immunoglobulins A, M, and G were determined with the radial immunodiffusion reaction in a Mancini gel; the IgE level was determined by ELISA (enzyme-linked immunosorbent assay). The skin condition including its hydration, depth of creases and wrinkles was assessed using an Aramo Smart Lite 300 device (Korea). The investigation was carried out at the Ekaterininskaya Clinic LLC and the Network of European Laboratories LLC.

Clinical results showed that right after the accomplishment of the mesotherapy procedure course, the quality of the skin significantly improved, which was attested by a decrease in the relief of skin creases, as at the prior stage, the examined index was up to 78.00% [ 73.00; 90.00] while after the course accomplishment, it was 45.5% [ 37.75; 53. 25], p<0.0001. In addition, an increase in skin hydration parameters was also revealed, when comparing values at the prior stage of examination (55.5% [ 46.5; 62.0]) and after the procedure course accomplishment (71.0% [ 63.0; 80.2], p<0.0001). Immunological indicators demonstrated a statistically significant redistribution of the subpopulation composition of the lymphoid lineage of immunopoiesis in the peripheral bloodstream. In particular, an increase in the relative number of mature T-lymphocytes and a simultaneous decrease in B-cells and CD16+ subpopulations were noted. In the cellular unit of adaptive immunity, an increase in both CD4+ and CD8+ subpopulations was manifested. Besides, a decrease in the amount of T cells with CD25 expression was revealed, which attested to the process of early T cell activation. Furthermore, a statistically significant increase in the proportion of peripheral regulatory T-lymphocytes CD4+CD25+FoxP3+ was found, which are responsible for intraimmune suppression. In the data of the general blood test, a decrease in the total amount of leukocytes in peripheral blood flow was revealed, as at the prior stage, the examined index was 6.30 [ 4.88; 7.12],10⁹/l and then it reached the value 5.40 [ 4.62; 6.28],10⁹/l; p=0.0016 right after the course accomplishment. A decrease in lymphocytes was also found: at the prior stage, the examined index was 36.00 [ 30.00; 44.00], 10⁹/l and reached the value 28.50 [ 23.00; 34.75]; p=0.0004 after procedure accomplishment. Thus, the absolute values of the total number of T cells and their subpopulation characteristics were reduced. The cellular component of the humoral adaptive immune response was manifested by a decrease in the relative and absolute content of B lymphocytes. Nevertheless, the activation of antibody production was revealed attested by an increase in the level of all classes (IgA, IgM, IgG, IgE) of serum immunoglobulins. Indicators of the innate immune response were characterized by a decrease in the number of circulating immune complexes in both absolute and relative values. Activation of spontaneous oxygen-producing activity was shown in the neutrophil unit accompanied by no changes under conditions of additional neutrophil stimulation.

In 3 months after the accomplishment of the mesotherapy course, no significant changes in the clinical picture were recorded. In particular, parameters characterizing the depth of skin creases were 45.5% [ 37.75; 53.25] and 45.50% [ 38.00; 58.00], p<0.0001 at stages right after the accomplishment of course procedures and 3 months later, respectively. The hydration index was 71.0% [ 63.0; 80.2] right after the accomplishment of course procedures and in 3 months it was 60.50% [ 51.75; 70.00] p<0.0001. There were no changes noted in the immunological indicators, which reflect the characteristics of the quantitative and functional potencies of the immune system, when compared with the results recorded at the stage right after the accomplishment of the procedure course.

In 6 months after the accomplishment of the course, the indicators of the clinical picture manifested a tendency toward a decrease in the achieved effects. An increase in the depth of skin creases and wrinkles was revealed as right after the accomplishment of the procedure course the examined index was 45.5% [ 37.75; 53.25] while in 6 months it was 63.0% [ 45.5; 68.5], p <0.0001. Besides, a decrease in skin hydration parameters was noted, as right after the accomplishment of the procedure course the examined index was 71.0% [ 63.0; 80.2], and in 6 months it was 49.5% [ 42.7; 55.2]; p <0.0001.

Immunological parameters manifested a decrease in the proportion of T-lymphocytes when comparing results obtained right after the course accomplishment (68.00 [ 64.50; 70.25]%) and after the three-month period (65.00 [ 60.00; 67.75]%, p = 0.0387). That decrease was mediated by both CD4+ and CD8+ subpopulations when comparing values for CD4+ obtained right after the course accomplishment (36.00 [ 34.00; 37.25]%) and three months later (33.50 [ 32.00; 35.25]%, p=0.0032); and values for CD8+ obtained right after the course accomplishment (34.00[  31.00; 36.25]%, and three months later (32.00 [ 29.50; 35.00]%, p=0.0038). At the same time, there was also noted an increase in the expression of markers of early T-cell activation CD3+CD25+ when comparing results obtained right after the course accomplishment (0.08 [ 0.07; 0.11], 10⁹/l) and three months later (0.12 [ 0.09; 0.17] 10⁹/l, p=0.0097). In addition, the absolute number of T-regulatory lymphocytes (CD4+CD25+FoxP3+) increased, as right after the course accomplishment, the examined index was 0.08 [ 0.07; 0.10], 10⁹/l and three months later it was 0.09 [ 0.08; 0.13], 10⁹/l, p=0.0019. In the humoral part of the immune response, there was an increase in circulating B-lymphocytes when comparing results obtained right after the course accomplishment (0.31 [ 0.24; 0.42], 10⁹/l) and three months later (0.45 [ 0.33; 0.52], 10⁹/l, p=0.0011). In addition, a decrease in antibody production was noted, which was only confirmed for IgG, as the value right after the course accomplishment was 15.25 [ 12.88; 16.92], g/l, and three months later it was 13.80 [ 12.08; 16.15], g/l, p=0.0387. In the innate immune system, an increase in the number of natural killer cells was revealed when comparing results obtained right after course accomplishment (0.18 [ 0.13; 0.24], 10⁹/l) and in three months (0.24 [ 0.20; 0.33], 10⁹/l, p = 0,0032). Moreover, the spontaneous oxygen-producing activity of neutrophils also decreased when comparing NSTsp. right after natural killer course accomplishment (10.00 [ 7.75; 12.00] a.u.) and in three months (8.00 [ 5.75; 10.00], p=0.0097). Thus, based on the dynamics of changes described above, in 6 months after the natural killer course accomplishment, no statistically significant differences were identified.

Mesotherapy involves a course of intradermal injections of drugs for aesthetic purposes. The obtained clinical results, recorded using electronic dermatoscopy, confirm that the patients achieved a positive and lasting cosmetic effect after a course of mesotherapy with peptide complexes related to a significant improvement in skin quality. Due to the fact that peptide complexes with an immunotropic effect were used, it has been logical to assume their possible effect on innate and adaptive immunity and the impact on the homeostasis of the body as a whole. The results of the study make it possible to confirm the involvement of innate and adaptive immunity, which is reflected in the processes of differentiation of lymphocyte populations and in a decrease in activation potential. An increase in antibody production and activation of spontaneous oxygen-producing activity were revealed right after the procedure course accomplishment. When specifying the parameters of the innate immune response, a decrease in the number of natural killer cells was found, as well as a tendency to an increase in the oxygen-dependent mechanisms of neutrophil phagocytosis was noted. These changes in the functioning of the immune system were stable for 3 months after the accomplishment of the course of mesotherapy procedures and returned to previous parameters six months later.

As a result of the study, an improvement in skin quality after procedures of the mesotherapy course and long-term preservation of the effects was documented, as well as the dynamics of changes in both the innate and adaptive immune units were noted after a course of peptide administration. It is important to note the fact of the complete restoration of the characteristics of the immune status after 6 months, with noticeably lasting clinical results after the accomplishment of the procedure course.