ROLE OF TLR2, TLR4 GENE POLYMORPHISM IN DEVELOPING MICROVASCULAR COMPLICATIONS IN ADOLESCENTS WITH TYPE 1 DIABETES MELLITUS

Long-term complications of type 1 diabetes mellitus (T1DM) in children and adolescents are an important problem in modern medicine. Recently, the role of immune mechanisms, in particular, chronic inflammation, in the development of both T1DM and its microvascular complications has been actively discussed. Activation of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) leads to hyperproduction of proinflammatory cytokines, chemokines, adhesion molecules involved in the formation of diabetic microvascular complications. At the same time, TLR2 and TLR4 gene polymorphism alters the immune susceptibility to the endogenous ligands, which may increase the risk of diabetic microangiopathies. The aim of this study is to evaluate the frequency of genotypes and alleles of TLR2 and TLR4 genes distribution and to determine the content of TNFα, IL-1, VCAM-1, fractalkine, endothelin-1 in adolescents with T1DM with microvascular complications. We examined 139 adolescents with T1DM from 14 to 18 years old and 56 healthy teenagers. Patients with T1DM were divided into two groups: Group I – patients with poor glycemic control (HbA1C > 9.0%), (n = 64); Group II – patients with satisfactory glycemic control of T1DM (HbA1C ≤ 9.0%), (n = 75), including adolescents with optimal (HbA1C < 7.5%) and suboptimal glycemic control (7.5% ≤ HbA1C ≤ 9.0%) (ISPAD clinical practice consensus guidelines 2014). According to the presence of microvascular complications, the groups were subdivided into subgroups: Iа (n = 49), IIа (n = 38) – adolescents with verified microvascular disorders: diabetic retinopathy, nephropathy and neuropathy; Ib (n = 15), IIb (n = 37) – without microvascular complications. Allelic variants of TLR genes were determined using test systems GosNII genetics (Moscow). The content of cytokines in blood serum was carried out by the method of enzyme-linked immunosorbent assay “BIOSCIENCE”. Data were analyzed using software packages Statistica version 6.0. The assessment of TLR2 (Arg753Gln) and TLR4 (Thr399Ile) polymorphism distribution did not reveal significant differences between the observed subgroups and the control. In Ia and IIa subgroups (with complications) Asp299Gly variant was noted to be significantly less common when compared to subgroups Ib, IIb and controls. The presence of Gly allele in TLR4 gene was found to disrupt the expression of TNFα and VCAM-1 and can be considered protective for the development of microvascular complications. 

1. Abbas S.A., Raza S.T., Mir S.S., Siddiqi Z., Zaidi A., Zaidi Z.H., Mahdi F. Role of variants rs5030717 and rs5030718 of TLR4 in the risk prediction of nephropathy, hypertension and dyslipidaemia in type 2 diabetes mellitus. Br. J. Biomed. Sci., 2018, Vol. 75, no. 4, pp. 163-168.

2. Cho Y.H., Craig M.E., Hing S., Gallego P.H., Poon M., Chan A., Donaghue K.C. Microvascular complications assessment in adolescents with 2- to 5-yr duration of type 1 diabetes from 1990 to 2006. Pediatr. Diabetes, 2011, Vol. 12, no. 8, pp. 682-689.

3. Degirmenci, I., Ozbayer, C., Kebapci, M.N. Common variants of genes encoding TLR4 and TLR4 pathway members TIRAP and IRAK1 are effective on MCP1, IL6, IL1β, and TNFα levels in type 2 diabetes and insulin resistance. Inflamm. Res., 2019, Vol. 68, pp. 801-814.

4. Demirel F., Tepe D., Kara O., Esen I. Microvascular complications in adolescents with type 1 diabetes mellitus. J. Clin. Res. Pediatr. Endocrinol., 2013, Vol. 5, no. 3, pp. 145-149.

5. Devaraj S., Jialal I. Increased secretion of IP-10 from monocytes under hyperglycemia is via the TLR2 and TLR4 pathway. Cytokine, 2009, Vol. 47, no. 1, pp. 6-10.

6. ISPAD Clinical Practice Consensus Guidelines 2014 Compendium. Pediatr. Diabetes, 2014, Vol. 15, Suppl. 20, pp. 154-179.

7. Joussen A.M., Doehmen S., Le M.L., Koizumi K., Radetzky S., Krohne T.U., Poulaki V., Semkova I., Kociok N. TNF-alpha mediated apoptosis plays an important role in the development of early diabetic retinopathy and longterm histopathological alterations. Mol. Vis., 2009, Vol. 15, pp. 1418-1428.

8. Jung D.-S., Lee S.H., Kwak S.-J., Li J.J., Kim D.H., Nam B.-Y., Kang H.Y., Chang T.I., Park J.T., Han S.H., Yoo T.-H., Kang S.-W. Apoptosis occurs differentially according to glomerular size in diabetic kidney disease. Nephrol. Dial. Transplant., 2012, Vol. 27, no. 1, pp. 259-266.

9. Levkovich M.A., Galkina G.A., Voropay A.A. Тhe role of immunity factors in the formation of angiopathy in diabetes mellitus in adolescents. Russian Journal of Immunology, 2016, Vol. 10, no. 19, pp. 310-312. (In Russ.)

10. Long H., O’Connor B.P., Zemans R.L., Zhou X., Yang I.V., Schwartz D.A. The Toll-like receptor 4 polymorphism Asp299Gly but not Thr399Ile influences TLR4 signaling and function. PLoS One, 2014, Vol. 9, no. 4, e93550. doi: 10.1371/journal.pone.0093550.

11. Murakoshi M., Gohda T., Suzuki Y. Circulating tumor necrosis factor receptors: a potential biomarker for the progression of diabetic kidney disease. Int. J. Mol. Sci., 2020, Vol. 21, no. 6, 1957. doi: 10.3390/ijms21061957.

12. Myśliwska J., Ryba-Stanisławowska M., Smardzewski M., Słomiński B., Myśliwiec M., Siebert J. Enhanced apoptosis of monocytes from complication-free juvenile-onset diabetes mellitus type 1 may be ameliorated by TNF-α inhibitors. Mediators Inflamm., 2014, Vol. 2014, 946209. doi: 10.1155/2014/946209.

13. Olivares-González L., Velasco S., Campillo I., Rodrigo R. Retinal inflammation, cell death and inherited retinal dystrophies. Int. J. Mol. Sci., 2021, Vol. 22, no. 4, 2096. doi: 10.3390/ijms22042096.

14. Rajamani U., Jialal I. Hyperglycemia induces Toll-like receptor-2 and -4 expression and activity in human microvascular retinal endothelial cells: implications for diabetic retinopathy. J. Diabetes Res., 2014, Vol. 2014, 790902. doi: 10.1155/2014/790902.

15. Rivera J.C., Dabouz R., Noueihed B., Omri S., Tahiri H., Chemtob S. Ischemic Retinopathies: Oxidative Stress and Inflammation. Oxid. Med. Cell. Longev., 2017, Vol. 2017, 3940241. doi: 10.1155/2017/3940241.

16. Singh K., Kant S., Singh V.K., Agrawal N.K., Gupta S.K., Singh K. Toll-like receptor 4 polymorphisms and their haplotypes modulate the risk of developing diabetic retinopathy in type 2 diabetes patients. Mol. Vis., 2014, Vol. 20, pp. 704-713.

17. Voropay A.A., Levkovich M.A., Galkina G.A. Predictors of early development of microvascular complications in adolescents with type 1 diabetes mellitus. Allergology and Immunology. 2017, Vol. 18, no 1. p. 59. (In Russ.)

18. Xu W.Q., Wang Y.S. The role of Toll-like receptors in retinal ischemic diseases. Int. J. Ophthalmol., 2016, Vol. 9, no. 9, pp. 1343-1351.