The investigation of relationship among proinflammatory, TH1, TH2, TH17 cytokine response and circulating 25-hydroxy and 1,25-dihydroxyvitamin D3 levels in dogs with parvoviral enteritis

Opinions about the possible role of vitamin D on the immunity system, apart from its classic role in calcium homeostasis, have been proposed for many years. In recent years, it has been determined that all immune cells have vitamin D receptors and that 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) is synthesized externally in many immune cells. Following this, 1,25(OH)2D3, the active form of vitamin D, has been shown to play an important role in the immune system by binding to vitamin D receptors in both the cells from which it is produced and other immune cells. It is generally accepted that 1,25(OH)2D3 induces innate immunity and suppresses adaptive immunity in vitro. However, there are no studies showing whether this state is valid in vivo. In this study, to establishment of in vivo status, the parvoviral enteritis of dogs was determined as an infection model. It is aimed to determine: (i) whether the possible extrarenal production of 1,25(OH)2D3 in the immune cells causes an increase in circulating 1,25(OH)2D3 in this disease which has significant inflammation; (ii): the cytokine panel of natural and acquired immunity; (iii): the relation of vitamin D with this response. For this purpose, blood samples were obtained from 20 parvoviral enteritis patients and 10 healthy dogs which brought to Firat University, Animal Hospital. Virological examination revealed that all 20 dogs with suspected parvoviral enteritis were virus (CPV-2) (+) and the healthy dogs were virus (CPV-2) (-). Hematologic examination showed that leukopenia was apparent in dogs with parvoviral enteritis. In biochemical examinations, it was determined that 25-hidroksivitamin D3 (25(OH)D3) significantly increased in dogs with parvoviral enteritis while there was no significant difference between the groups at serum 1,25(OH)2D3 levels. IL-2, IL-4, IL-5, IL-10, IL-17 and TNF-α levels increased significantly in dogs with parvoviral enteritis while calcium and phosphorus levels decreased. As a result, it was determined that innate immunity and Th1 response were partially suppressed and the Th2 and Th17 responses were significantly increased in dogs with parvoviral enteritis. There was no increase in circulating 1,25(OH)2D3 levels despite significant inflammation of this disease. Therefore, in vivo relationship of the extrarenal 1,25(OH)2D3 with immunological parameters studied in this project has not been assessed. However, immunopathogenesis of the disease thought to be important factor on suppression in the production of extrarenal 1,25(OH)2D3, probably due to the suppression of the virus on immunological cells. In this regard, we believe that studies to measure 25(OH)D3 and 1,25(OH)2D3 levels at different stages of the disease are necessary.