To the Editor: Our scepticism about the value of many of the burgeoning number of clinical guidelines is reinforced by the position statement on vitamin D and health for adults.1 It was surprising not to find an explicit statement that there is Level I evidence that vitamin D monotherapy does not prevent falls2 or fractures3 or reduce mortality.4 Instead, Nowson and colleagues conclude that “there ...

The immunomodulatory effects of vitamin D have been described following chronic oral administration to mice or supplementation of cell cultures with 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the active form of vitamin D. In this study, topically applied 1,25(OH)₂D₃, enhanced the suppressive capacity of CD4⁺CD25⁺ cells from the draining lymph nodes. The effects of topical 1,25(OH)₂D₃ were compared with those of UVB irradiation, which is the environmental factor required for 1,25(OH)₂D₃ production in skin. CD4⁺ cells from the skin-draining lymph nodes (SDLN) of either 1,25(OH)₂D₃-treated or UVB-irradiated mice had reduced capacity to proliferate to Ags presented in vitro, and could suppress Ag-specific immune responses upon adoptive transfer into naive mice. This regulation was lost upon removal of CD4⁺CD25⁺ cells. Furthermore, purified CD4⁺CD25⁺ cells from the SDLN of 1,25(OH)₂D₃-treated or UVB-irradiated mice compared with equal numbers of CD4⁺CD25⁺ cells from control mice had increased capacity to suppress immune responses in both in vitro and in vivo assay systems. Following the sensitization of recipient mice with OVA, the proportion of CD4⁺Foxp3⁺ cells of donor origin significantly increased in recipients of CD4⁺CD25⁺ cells from the SDLN of 1,25(OH)₂D₃-treated mice, indicating that these regulatory T cells can expand in vivo with antigenic stimulation. These studies suggest that 1,25(OH)₂D₃ may be an important mediator by which UVB-irradiation exerts some of its immunomodulatory effects.

Natural compounds are emerging as effective agents for the treatment of malignant diseases. Curcumin (diferuloylmethane), the active constituent of turmeric extract, has gained significant interest as a plant-based compound with anti-cancer properties. Curcumin is physiologically very well tolerated, with negligible systemic toxicity observed even after high oral doses administration. Despite curcumin's superior properties as an anti-cancer agent its applications are limited due to its low solubility and physico-chemical stability, rapid systemic clearance and low cellular uptake. This review focuses on the development of curcumin nano-particle formulation to improve its therapeutic index through enhanced cellular uptake, localization to targeted areas and improved bioavailability. The feasibility of nano-formulation in delivering curcumin and the limitations and challenges in designing and administrating the nano-sized curcumin particles are also covered in this review. Nanotechnology is a promising tool to enhance efficacy and delivery of drugs. In this context, formulation of curcumin as nano-sized particles could reduce the required therapeutic dosages and subsequently reduced its cell toxicity. These nanoparticles are capable to provide local delivery of curcumin targeted to specific areas and thereby preventing systemic clearance. In addition, using specific coating, better pharmacokinetic and internalization of nano-curcumin could be achieved. However, the potential toxicity of nano-carriers for curcumin delivery is an important issue, which should be taken into account in curcumin nano-formulation.