Placebo-controlled Assessment of the Effect of a Food Supplement on Skin Protection After Exposure to UV Radiation
Condition: Photobiology
Study type: Interventional
Phase: Phase 1

Summary: 
      A probiotic bacterial strain was tested in a randomized, double blind , placebo controlled
      clinical trial with 54 healthy male volunteers. Half the volunteers received the dietary
      supplement the other half placebo during 6 weeks prior to exposure to solar-simulated UV
      irradition (2x1,5MED). Blister roofs and skin biopsies were recovered 1, 4 and 10 days after
      UV exposure from unirradiated and irradiated skin and used for immunohistochemical analysis
      and mixed epidermal cell lymphocyte reaction
    

Detailed description: 
      Langerhans cells (LC), the dendritic cells (DC) from epidermis, constitute the first line of
      immune defense against environmental attacks. Under steady state conditions, LC turnover is
      very low. The LCs reside in the epidermis in an immature state and can be distinguished from
      other epidermal cells by their surface expression of HLA-DR, CD1a and langerin. Upon
      stimulation by inflammatory mediators LCs are activated and acquire CCR7 expression, the
      chemokine receptor for CCL21 that mediates their migration to lymph nodes. Moreover,
      activated LCs display a mature phenotype characterized by increased expression of
      co-stimulatory molecules and acquisition of maturation markers that facilitate their
      interaction with T-cells and aid in the elicitation of the immune response.

      It has long been known that, in addition to being carcinogenic via DNA damage and mutations,
      solar UV radiation induces local and systemic immune suppression which represents a major
      risk for skin cancer induction and progression in sun-exposed areas. The process is mostly
      related to direct LC damage through induction of apoptosis and impairment of
      antigen-presenting function. Moreover, UV radiation elicits an inflammatory response and
      subsequent recruitment of immune cells, including CD36+ monocytic cells. These cells colonize
      the epidermis in the days following UV exposure and are the major source of immunosuppressive
      cytokines such as IL-10. All these mechanisms ultimately lead to impaired cell-mediated
      reactions and establishment of immune tolerance.

      Nutritional intervention, particularly with dietary antioxidants and vitamins, has been
      proposed to protect against UV-induced skin damage and to a certain extent skin cancer
      occurrence. In recent years, there has been an increasing interest for probiotics, defined as
      live microorganisms which, when consumed in adequate amounts, confer a health benefit upon
      the host. Particular focus has been on species of lactic acid bacteria including Lactobacilli
      and Bifidobacteria that are part of the natural human intestinal microbiota. Indeed, it is
      well documented that the endogenous intestinal microbiota plays a crucial role in immune
      maturation, gut integrity and defense against pathogens. Recently, it has been shown that
      some probiotic bacteria possess the ability to modulate the immune system at both the local
      and systemic levels and thereby improve immune defense mechanisms and/or down-regulate immune
      disorders such as intestinal inflammations or allergies.

      The Probiotic used as the dietary supplement, was isolated from healthy adult microbiota and
      was shown to have a strong anti-pathogenic activity against a wide range of entero-pathogens.
      Furthermore, a pre-clinical study demonstrated that it can maintain the epidermal LC density.

      Here, we analyzed, in a randomized double blind, placebo controlled, clinical trial, whether
      this dietary supplement could also modulate the cutaneous immune homeostasis after
      solar-simulated UV exposure in humans.For this purpose, we analyzed whether this dietary
      supplement could interfere with LC allostimulatory function and activation/maturation
      phenotypic status of skin DC, after solar-simulated UV irradiation.
    

Intervention name(s): dietary supplement
Intervention type(s): Behavioral
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double
Primary purpose: Treatment
Keywords: Probiotic bacteria; cutaneous immune homeostasis; UV radiation; dietary supplement