Stimulation of cytokine production by P. acnes and P. acnes GroEL may be important in the pathogenesis of inflammatory acne vulgaris and may have wider implications for the immunomodulation of the human immune system by commensal skin microorganisms.

The inflammatory stage of acne vulgaris is usually of greatest concern to the patient. A number of morphologically different inflammatory lesions may form that can be painful and unsightly. In 30% of patients, such lesions lead to scarring(1). Inflammatory acne and acne scarring can have significant psychological effects on the patient, including depression, anxiety, and poor self-image(2). Although inflammatory acne has been well characterized clinically, the mechanisms by which inflammatory lesions arise are still poorly understood. The human skin commensal bacterium, Propionibacterium acnes, has long been associated with inflammatory acne. This organism has been implicated over and above all of the other cutaneous microflora in contributing to the inflammatory response characteristic of acne. However, its precise role in the disease and its interaction with the human immune system remain to be elucidated.

Sunlight-exposure recommendations are inappropriate for individuals of South Asian ethnicity who live at the UK latitude. More guidance is required to meet the vitamin D requirements of this sector of the population. This study was registered at www.isrctn.org as ISRCTN 07565297.

Sunlight exposure, with resulting cutaneous synthesis, is a major source of vitamin D for many, while dietary intake is low in modern diets. The constitutive pigment in skin determines skin type, observed as white, brown, or black skin. The melanin pigment absorbs ultraviolet radiation (UVR) and protects underlying skin from damage caused by UVR. It also reduces the UVR available for vitamin D synthesis in the skin. It has been shown that the white-skinned population of the UK are able to meet their vitamin D needs with short, daily lunchtime exposures to sunlight. We have followed the same methodology, based on a 10-year UK all-weather UVR climatology, observation (sun exposure, diet, vitamin D status), and UVR intervention studies with Fitzpatrick skin type V (brown) adults, to determine whether sunlight at UK latitudes could provide an adequate source of vitamin D for this section of the population. Results show that to meet vitamin D requirements, skin type V individuals in the UK need ~25 min daily sunlight at lunchtime, from March to September. This makes several assumptions, including that forearms and lower legs are exposed June–August; only exposing hands and face at this time is inadequate. For practical and cultural reasons, enhanced oral intake of vitamin D should be considered for this population.