Impaired regulatory T-cell homeostasis due to vitamin D deficiency in undifferentiated connective tissue disease.

OBJECTIVE: The aim of this study was to perform a quantitative and functional analysis of natural CD4+CD25(high)Foxp3+ regulatory T cells (nTregs) and CD4+IL-17+ T cells, and to assess the serum levels of proinflammatory cytokines in patients with undifferentiated connective tissue disease (UCTD) before and after 5 weeks of 0.5 µg/day alfacalcidol supplementation. METHODS: Twenty-five patients with UCTD were enrolled in an open-label trial of alfacalcidol. Plasma levels of 25-hydroxyvitamin D [25(OH)D] were assessed by a high-performance liquid chromatography (HPLC) method. Flow cytometry was used for the quantification of nTregs and the IL-17 expression of T-helper (Th)17 cells. The serum concentrations of cytokines interleukin (IL)-12, interferon (IFN)-γ, IL-23, IL-17, IL-6, and IL-10 were measured by an enzyme-linked immunosorbent assay (ELISA). RESULTS: Treatment with alfacalcidol raised 25(OH)D levels from a mean of 23.5 ± 5.6 to 34.5 ± 7.4 ng/mL (p = 0.059; NS). Alfacalcidol treatment decreased both Th1- (IL-12 and IFN-γ) and Th17-related (IL-23, IL-17, IL-6) cytokine levels in UCTD patients, while the soluble IL-10 level increased (IL-12: 156.7 ± 75.2 vs. 87.5 ± 42.1 pg/mL, p < 0.001; IFN-γ: 41.5 ± 12.0 vs. 21.7 ± 9.9 pg/mL, p < 0.001; IL-23: 385.2 ± 82.2 vs. 210.0 ± 69.3 pg/mL, p < 0.001; IL-17: 37.8 ± 9.6 vs. 17.8 ± 4.5 pg/mL, p = 0.009; IL-6: 39.4 ± 11.3 vs. 23.5 ± 6.3 pg/mL, p < 0.001, IL-10: 8.4 ± 3.0 vs. 21.4 ± 9.7 pg/mL, p < 0.001). Alfacalcidol improved the Th17/nTreg imbalance, as it inhibited the IL-17 expression of Th17 cells, and increased the number of nTregs. The alfacalcidol might increase the capacity of nTreg cells to suppress the proliferation of autologous CD4+CD25⁻ cells. CONCLUSION: Our findings support the idea that vitamin D influences the Th17/nTreg imbalance in vitamin D-insufficient patients with UCTD and could be beneficial in the management of the disease.

The distribution of orally administered (-)-deprenyl-propynyl-14C and (-)-deprenyl-phenyl-3H in rat brain.

Using alternatively labelled (-)-deprenyl (3H label in the ring and 14C in the propargyl group) the distribution of the compound was studied in 15 brain regions and the plasma of rats over a period of 96 h, after oral administration of 1.5 mg/kg of (-)-deprenyl. The compound is rapidly absorbed (within 15-30 min) from the gastrointestinal tract, as indicated by its high plasma level. It penetrates to the central nervous system, where it reaches a peak level within 45-60 min. During the first 2 h in the plasma the 14C label, whilst in cerebral tissues during the whole period of the experiment the 3H tracer dominates. The difference in the ratio of 3H to 14C radioactivity (compared to the 0 time relation) develops as early as in the first 15 min, which indicates the operation of a rapid "first pass" biotransformation of the compound. Our data represent the tissue molar concentration -time curves of (-)-deprenyl calculated from both the 3H and 14C radiolabels. A ratio of 1 of the concentrations of the two tracers would indicate that the molecule remained unchanged. The changes in the ratio, therefore, suggest the formation of considerable quantities of metabolites (methylamphetamine and amphetamine) and their presence in the brain. The difference between the area under the curves (AUC0-t for 3H and AUC0-t for 14C) represents the amount of metabolites expected to be formed during the experiment. The concentration of the metabolites should be taken into account while evaluating the pharmacological effect of (-)-deprenyl. We proved earlier that a dose of 1.5 mg/kg of (-)-deprenyl completely blocks MAO-B activity in the central nervous system. The fast metabolism of the inhibitor indicates that a minor part of the orally administered (-)-deprenyl is sufficient to produce a high level of selective MAO-B inhibition in the brain.

Effect of MAO inhibitors on the uptake and metabolism of dopamine in rat and human brain.

Complex pharmacological effect of l-deprenyl cannot be explained by its MAO-B inhibitory action only. In contrast to other parent MAO inhibitors (J-512, J-516, LK-63, U-1424) l-, and d-deprenyl inhibit the hypothalamic noradrenaline and striatal dopamine (DA) reuptake without influencing the uptake of serotonin, both in rat and in human brain. Long-term treatment 19 x 0.25 mg/kg or 0.5 mg/kg, sc with l-deprenyl elicits 37 +/- 2.8 and 43 +/- 3.2% inhibition, respectively, of DA reuptake capacity in the rat striatal cell-free homogenate. To compare the potencies of deprenyl isomers on DA and DOPAC levels of rat striatum drugs were given 0.25, 2 and 8 mg/kg ip and their effects measured 4 and 48 h after treatment. DA content was increased only by 8 mg/kg d-deprenyl 4 h after its injection, but DOPAC level was decreased by both isomers. After 48 h, actions of d-deprenyl terminated but the effect of l-deprenyl was still present.