25-Hydroxyvitamin D, cholesterol, and ultraviolet irradiation.

Vitamin D deficiency may have implications for cardiovascular health. The purpose of this study was to determine the relationship of 25-hydroxyvitamin D (25[OH]D) to cholesterol and lipoprotein particles and to determine whether increasing 25(OH)D through ultraviolet (UV) irradiation impacted on these parameters in healthy young men and women. This was a randomized trial of 51 adults exposed to suberythemal doses of whole-body irradiation using UV lamps that emitted UV-A and UV-B radiation, compared with a control group, twice weekly for 12 weeks. 25-Hydroxyvitamin D, cholesterol, and lipoprotein subfractions were measured at baseline and after 12 weeks. There was a significant (P < .03) positive association between 25(OH)D and apolipoprotein A-I (Apo A-I) and lipoprotein A-I (Lp A-I). The ratio of low-density lipoprotein to high-density lipoprotein was significantly (P < or = .044) negatively correlated with 25(OH)D levels. The levels of 25(OH)D increased significantly in the treated compared with control group (P < .05). Overall, there were no significant differences between the treated and control groups in any lipoproteins or apolipoproteins after administration of UV irradiation. Subgroup analysis for Apo A-II confined to those with 25(OH)D insufficiency (25[OH]D <75 nmol/L [30 ng/mL]) revealed decreases in Apo A-II in the treated group and increases in the control group that were statistically significantly different between the groups (P = .026). We found a significant positive correlation between 25(OH)D and Apo A-I and Lp A-I and a significant negative correlation between 25(OH)D and the ratio of low-density lipoprotein to high-density lipoprotein. In those with vitamin D insufficiency, we found small decreases in Apo A-II in the treated relative to the control group. Overall, though, twice weekly exposure to UV radiation resulting in an increase in serum 25(OH)D had no significant impact on lipoprotein composition.

Skin basement membrane zone: a depository for circulating microbial antigen evoking psoriasis and autoimmunity.

BACKGROUND: Elevated levels of antibody to streptococcal exoenzymes have been found in patients with psoriasis or psoriatic arthritis. Research on the role of streptococcal antigen in psoriasis has been hampered by a potential molecular mimicry between streptococcal epitopes and human epidermal keratin. OBJECTIVE AND METHODS: Evidence of microbial product was sought in skin biopsies of psoriasis patients thought clinically to have either streptococcal carrier state or gastrointestinal candidal colonization. A polyclonal antibody to streptococcal-derived exoenzymes unlikely to share antigenic structures with normal human skin, and an anticandidal antibody, were used with linked streptavidin biotin amplification stain. RESULTS: The predicted microbial product appeared heavily in lesional epidermis, but unexpectedly also as a thin deposit along the skin basement membrane zone (SBMZ) of apparently unaffected skin. Staining was negative for nonpsoriatic subjects. CONCLUSIONS: The findings support a direct effect of microbial antigen in psoriasis. They also suggest an important role for SBMZ as a very large adhesive surface in the first step of a process of percutaneous epidermal elimination of foreign antigens and microbial toxins. The many autoimmune phenomena seen so often at the SBMZ are probably a physiologic part of this important immune function. Efforts to enhance the adhesive properties of SBMZ should be exploitable for both diagnostic and therapeutic benefit.

Sunscreen ingredients inhibit inducible nitric oxide synthase (iNOS): a possible biochemical explanation for the sunscreen melanoma controversy.

Sunscreen products are rated upon their ability to inhibit visible redness of the skin 24 h after measured doses of ultraviolet (UV) exposure (Sun Protection Factor, SPF). Although sunscreens prevent UV-induced redness, their ability to protect against melanoma or the development of moles is less clear. UV-induced redness occurs in part by the action of nitric oxide (NO), synthesized in the skin. NO is also an important immunoregulatory molecule in the induction of the cell-mediated tumour immune response. In this study, various sunscreen ingredients were tested for their ability to inhibit the production of NO. Four of the five sunscreens tested directly inhibited the conversion of arginine to citrulline by inducible nitric oxide synthase (iNOS) in vitro. These findings suggest that sunscreens may prevent redness partly by UV absorption and partly by inhibition of the skin's inflammatory response. As such, sunscreens might promote instead of protect against melanoma.