Results and Prospects of Using Activator of Hematopoietic Stem Cell Differentiation in Complex Therapy for Patients with COVID-19

The paper presents the results of a standard and complex treatment method using the peptide drug thymus thymalin in patients with COVID-19. One of the mechanisms of the immunomodulatory effect of thymalin is considered to be the ability of this peptide drug to influence the differentiation of human hematopoietic stem cells (HSCs). It was found that, as a result of standard treatment, patients in the control group showed a decrease in the concentration of the pro-inflammatory cytokine IL-6, C-reactive protein, D-dimer. The addition of thymalin to standard therapy accelerated the decline in both these indicators and the indicators of the T cell system. This has helped reduce the risk of blood clots in COVID-19 patients. The revealed properties of the thymus peptide preparation are the rationale for its inclusion in the complex treatment of coronavirus infection. Graphical Abstract Peptideswith potential biological activity against SARS-CoV-2 virus [ 29 ]. Note: Nitrogen atoms are shown in blue, oxygen atoms - in red, carbon atoms – in gray, hydrogen atoms – in white, and phosphorus atoms – in yellow

Patient Characteristics The single-center, open-label, prospective, randomized, controlled trial included patients hospitalized in St. Petersburg City General Hospital No. 2 with a clinical diagnosis of U07.1, COVID-19, virus identified, during April - July 2020. Patients were randomized using the envelope method. The inclusion criteria for the study were: moderate and severe forms of the course of the disease, the presence of absolute (< 1.2*109/L) and/or relative (< 19%) lymphopenia in the clinical blood test, the presence of bilateral polysegmental pneumonia, confirmed by spiral computed tomography with a CT1-CT3 lesion index with symptoms of respiratory failure (SpO2 ≤ 95%). All patients were divided into 2 groups: the main group consisted of 42 patients (25 women and 17 men) who received treatment according to the standard regimen in combination with thymalin; the control group included 50 patients (27 women and 23 men) who received treatment according to the standard regimen. The average age of patients in the main group was 59.8 ± 7.8 years, and in the control group 61.7 ± 5.4 years.

Patients of both groups underwent the following laboratory studies before and after therapy: clinical blood test, a coagulogram (fibrinogen, prothrombin time, D-dimer), blood biochemical composition (C-reactive protein, glucose, ferritin), and an immunogram (CD3, CD4, CD8, interleukin-6). For the study, fasting blood test was taken by venipuncture from the cubital vein into special vacuum tubes. The collection of biological material was carried out completely in accordance with the requirements of the preanalytical stage of the hematological study. Laboratory studies were performed using reagents from the following manufacturers: hematological studies and determination of CD3, CD4, CD8 lymphocytes were done using an automatic hematological analyzer Cell-Dyn Sapphire, manufactured by Abbott Laboratories (USA); ESR measurement was done on the Test 1 analyzer manufactured by Alifax (Italy); coagulogram was analyzed on an automatic coagulometer ACL9000, manufactured by Instrumentation Laboratory (USA); the level of glucose and C-reactive protein was determined using a biochemical analyzer ARCHITECT c4000, manufactured by Abbott Laboratories (USA); ferritin concentration was measured on an ARCHITECT i2000 immunochemiluminescence analyzer, manufactured by Abbott Laboratories (USA); and the level of interleukin-6 was determined on equipment designed for ELISA, with reagents from the “Vector-Best” company.

It should be noted that there were no deaths in any of the groups. During the observation period using spiral computed tomography in the control group, the progression of pathological changes was noted in 5 cases, and in the main group in 2 cases. The results of laboratory studies of patients in both groups are presented in Tables 1 , 2 and 3 . Table 1 Laboratory indicators of the immune system in patients Indicators Norm Control group (n = 50) (X̄±SE) Main group (n = 42) (X̄±SE) Before treatment After standard treatment Before treatment After standard treatment with thymalin Leukocytes (× 10 9 /l) 4,00–9,00 8,92 ± 0,78 9,33 ± 0,63 7,85 ± 0,51 7,02 ± 0,71 Lymphocytes (× 10 9 /l) 1,20–3,00 0,96 ± 0,12 1,08 ± 0,13 0,89 ± 0,13 1,38 ± 0,17* ^ CD3 (× 10 9 /l) 0,88–2,40 0,44 ± 0,04 0,47 ± 0,05 0,47 ± 0,04 0,77 ± 0,08*# CD4 (× 10 9 /l) 0,54–1,46 0,26 ± 0,03 0,28 ± 0,07 0,27 ± 0,05 0,51 ± 0,09*# CD8 (× 10 9 /l) 0,21–1,20 0,16 ± 0,03 0,17 ± 0,02 0,18 ± 0,02 0,20 ± 0,01 CD4/CD8 1,00–3,50 1,63 1,66 1,5 2,55* ^ IL-6 (pg/ml) 0,00–7,00 23,71 ± 2,75 16,80 ± 2,22* 20,35 ± 3,82 3,69 ± 0,41**# * p ≤ 0.05 compared with the corresponding column “before treatment” in each group ** p ≤ 0.01 compared with the corresponding column "before treatment" in each group # p ≤ 0.01 compared to the control group "after standard treatment" ^ p ≤ 0.05 compared with the control group "after standard treatment" Table 2 Laboratory biochemical and hematological parameters of peripheral blood in patients Indicators Norm Control group (n = 50) (X̄±SE) Main group (n = 42) (X̄±SE) Before treatment After standard treatment Before treatment After standard treatment with thymalin CRP (mg/dl) 0,00–0,50 14,27 ± 2,12 8,62 ± 1,32* 13,11 ± 1,92 1,35 ± 0,17**# D-dimer (ng/ml) 0,00–232 1705,71 ± 143,21 815,62 ± 72,43* 1820,35 ± 172,35 319,47 ± 47,31**# Fibrinogen (g/l) 2,38 − 4,98 6,44 ± 0,37 5,43 ± 0,66 6,29 ± 0,45 4,11 ± 0,29** Ferritin (ng/ml) 21,80–274,70 747,78 ± 58,25 725,32 ± 83,52 695,25 ± 75,35 425,32 ± 44,22* ^ Prothrombin time (sec) 9,4–12,5 14,39 ± 0,24 13,43 ± 1,12 14,87 ± 0,56 11,2 ± 0,49** * p ≤ 0.05 compared with the corresponding column “before treatment” in each group ** p ≤ 0.01 compared with the corresponding column "before treatment" in each group # p ≤ 0.01 compared to the control group "after standard treatment" ^ p ≤ 0.05 compared with the control group "after standard treatment" Table 3 Laboratory parameters of peripheral blood in patients Indicators Norm Control group (n = 50) (X̄±SE) Main group (n = 42) (X̄±SE) Before treatment After standard treatment Before treatment After standard treatment with thymalin Neutrophils (× 10 9 /l) 2,00–5,50 4,28 ± 0,35 3,95 ± 0,41 4,72 ± 0,37 3,68 ± 0,44 Eosinophils (× 10 9 /l) 0,00–0,30 0,15 ± 0,02 0,13 ± 0,01 0,12 ± 0,03 0,06 ± 0,02*# Basophils (× 10 9 /l) 0,00–0,10 0,08 ± 0,01 0,06 ± 0,01 0,09 ± 0,02 0,03 ± 0,01** ^ Monocytes (× 10 9 /l) 0–0,60 0,53 ± 0,04 0,55 ± 0,08 0,50 ± 0,07 0,66 ± 0,05* ^ Platelets (× 10 9 /l) 150–400 351,12 ± 43,19 368,32 ± 27,15 279,35 ± 22,77 315,44 ± 28,25* Plateletcrit (PCT) (% per liter) 0,14–0,39 0,14 ± 0,01 0,16 ± 0,02 0,16 ± 0,02 0,21 ± 0,01* ^ Neutrophils/Lymphocytes – 4,46 3,66 5,30 2,67* Platelets/Leukocytes – 39,36 39,48 35,59 44,93* Eosinophils/Basophils – 1,88 2,17 1,33 2,00 ESR (mm/h) 2–30 63,84 ± 7,25 58,33 ± 3,55 54,42 ± 3,82 44,41 ± 3,73* ^ * p ≤ 0.05 compared with the corresponding column “before treatment” in each group ** p ≤ 0.01 compared with the corresponding column "before treatment" in each group # p ≤ 0.01 compared to the control group "after standard treatment" ^ p ≤ 0.05 compared with the control group "after standard treatment" Table 1 shows the results of treatment of patients in both groups. This shows the concentration of IL-6 in the control group decreased by 1.41 times when compared with the corresponding indicator before treatment (p ≤ 0.05). However, this therapy did not improve the parameters of the T cell system. The inclusion of thymalin in standard therapy in patients of the main group led to a statistically significant increase in the number of lymphocytes by 55%, T lymphocytes by 63.8%, CD4 by 88.9%, and the CD4/CD8 ratio increased by a factor of 1.7 when compared with the corresponding indicators before treatment. The concentration of IL-6 after the introduction of thymalin decreased by 5.5 times. Thus, the administration of thymalin to patients with COVID-19 contributed to a statistically significant change in the number of lymphocytes, which reached normal values, and the number of T lymphocytes and T helpers approached the lower limits of the normal range. Especially noteworthy is the significant decrease in the cytokine IL-6 after the introduction of thymalin. Table 2 presents the biochemical and hematological parameters of peripheral blood in patients with COVID-19. The table shows that in the patients of the control group, the content of C-reactive protein and D-dimer significantly decreased by 1.7 and 2.1 times, respective