engleski

Immunomodulation effects of vitamin D in Diabetes mellitus.

For the last two decades the role od Vitamin D3 has been recognised not only as a regulatory component of a bone – kidney metabolism, but also as an important immunomodulator. Lower levels of vitamin D are detected before an egzacebation in rheumatic diseases:psoriatic arthritis, rheumatoid arthritis and ankylosing spondylitis. Same has been shown in cardiovascular diseases and diabetes mellitus typ 1 and 2, egzacerbation of Hashimoto ; sthyroiditis and ulcerative colitis, multiplesclerosis and in some kinds of cancer also. Lowel levels of vitamin D3 have been confirmed many years before on setof autoimmunedisease. Type 1 diabetes occures when T-cells attack insulin-producing beta cells in the islets of Langerhans of the pancreas. T cells acitivated by viruses or other environmental triggers make an autoimmune attack only on beta cells. That leads to impaired beta cells function or death of beta cells. Dendritic cells clean up dead or impaired beta cells including once –hidden antigens that can cause an immune response. Dendritis and other immune cells bearing beta –cells antigens return to the pancreatic lymph nodes to program immature T-cells to attack beta cells.Loop is established and the now- agressive mature T cells leave the lymph node to mount a fresh attack on beta cells. In type 2 of diabetes vitamin D3 act on three differents mechamisms: 1.Direct acting on beta cell 2. Influence on insulin resistence 3. Via proinflamatry cytokines mechanism 1. Vitamin D improves glucose induced insulin secretion. Modification of function of beta cells acting throughout direct activation of transcriptions protein for genes for insulin secretion. Suplementation by vitamin D can restore insulin secretion for long time. Vitamin D can also regulate intensity and capacity of insulin secretion throught regulation of extra and intracellular concetration of calcium.It can improve disposal index of insulin secretion and delay appearing of diabetes. 2. Improvesthe effect of insulin on the skeletal muscle receptors (10), affects the insulin promoters genes and the transcriptional activation of the insulin genes. It also increases insulin sensitivity by increasing the number of receptors and insulin efficacy. Vitamin D activates the transcription factors important for glucose entry in to cells, too. 3. Proinflamatory role: Transcriptional and translational factors in the nucleus control release of chemokines and cytokines by participating in the promotion of chemokine and cytokine genes through the proliferation of T cell response. Itinhibits the release of TGF beta, IFN- gamma, IL-9 IL-7, reduces oxidative stress, inverses the inflammatory pathway Th1 Th2, and increases the number and the receptors tolerance capacity. During high glycemic-exhaustion of cells, eliminates appearance of oxidative stress elements, that leads to apoptosis –„cytokine insulin resistance. Vitamin D may inhibitapoptosis of the beta cell via the suppressor mTOR signal pathway. Studies and vitamin D Some studies confirmed relation of vitamin D3 deficiency with an increased BMI. The Norwegian Population Study with 10229 people found the reverse relation between 25 (OH) D3 with BMI. All longitudinal studies from 1994 to 2008, (N = 2656) showed negative predictions on BMI (reduction for 1kg / m2 increased level 25 (OH) D3 from 2.8 to 19.9 nmol/L)Deveray confirmed the association of insulin resistance (IR) with level 25 (OH) D3 in adult preterm infants. In Metabolic Syndrome (MB), the concentration of 25 (OH) D3 is negatively associated with glucose and IR. High levels of 25 (OH) D3 in T2DM - only improves insulin sensitivity, while the other parameters of IR (thickness) remain unchanged. Tromse study 93 (40000 ij tj / g) showed that ↑ 25 (OH) D3 did not result in a fall in weight. Lee et al confirmed that higher BMI is connect with lower Vitamin D. Higher IR and body constitution affects absorption of vitamin D3, its metabolism and storage. Low adiponectin level and vitamin D3 are found in studies of adolescent children and adolescents in Norway, Afico American, Black Population Malaysian Columbian. Manny of that studies have a low level of evidence and they are not comparrable because some of them are just observational, the others are randomised, some retrospective, or prospective and its difficult to distinguish the direct effect for the possible impact they have. Despite all the true connections, it has not been proven direct connection between low level of vitamin D with all consequences.

vitamin D, Diabetes mellitus, Immunomodulation effects

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