The Annual Meeting of the Society for Investigative Dermatology was, as usual, a very vibrant meeting with over 940 presentations (talks and posters) covering all aspects of dermatology. Acne, its causes and treatment, featured strongly, as did psoriasis and its genetics, although for readers of this journal, the use of retinoids in treating psoriasis seems to be well beyond its peak of several years ago. This conference report gives an account of some of the relevant presentations.
The Acne Symposium
The Acne Symposium is now an annual event at the SID, and is sponsored by CIRD Galderma. Acne remains a global problem, with 40-50 million Americans affected at any given time, for example. Several groups have worked in this field over the last few years to push forward our knowledge-base of this area. The talks in this year's symposium mainly focused on the inflammatory pathways in acne and how retinoids work to modify these pathways.
The recipient of the CIRD Galderma Award for 2007 was Dr Philip Liu (UCLA, Los Angeles, CA) for his work on acne inflammation. It is known that Propionibacter acnes activates monocytes through TLR2 (Toll-like Receptor 2), which is expressed on monocytes in acne lesions. Topical retinoids such as all-trans-retinoic acid, (ATRA, Accutane), Differin, and Tazorac, produce anti-inflammatory activities by downregulating TLR2 and CD14 mRNA, and this seems to be a specific action for TLR2, since there is very little measurable change in TLR4, for example. The investigators in this group added to this by showing that downregulation of TLR2 by ATRA leads to a functional consequence, since it decreases cytokine production. This was shown in vitro by treating monocytes with ATRA and measuring a reduction in TLR2-induced cytokines. A cell viability assay indicated that the effect of ATRA did not result from cytotoxicity. In vivo, treatment with ATRA reduces P. acnes-induced inflammatory cytokines perhaps through the in vitro mechanism outlined in this work.
A report from Professor Diane Thibutot's laboratory (Pennsylvania State University, Hershey, PA) produced, for the first time, the gene profile of skin of acne lesions using an Affymetrix gene chip containing 14,000 genes. They found that 211 genes were upregulated and 18 were downregulated. Of the upregulated genes, 41 are involved in inflammation, notably that for IL-8 (54-fold increase) and those for matrix metalloproteins, MMP-1 and MMP-3 (increased 92- and 64-fold, respectively). Apoptosis genes were also upregulated (e.g. granzyme B; G protein coupled...