Topical heat shock protein 70 prevents imiquimod-induced psoriasis-like inflammation in mice.

Psoriasis is a chronic inflammatory skin disease with systemic manifestations and potential genetic etiology. The newest treatments utilize antibodies against one of several cytokines known to underlie the inflammatory signaling molecules that produce the skin and systemic symptoms. However, these agents must be regularly injected, and they may compromise the normal responses of the immune system. Furthermore, they do not address the causes of the abnormal immunoregulatory responses of the disease because the etiology is not yet completely understood. In this short-term treatment study, the potential anti-inflammatory activity of an alfalfa-derived Hsp70-containing skin cream (aHsp70) was tested on imiquimod (IMQ)-induced psoriasis-like lesions in wild-type mice. Treatment of the mice with the aHsp70 skin cream simultaneously with the imiquimod application mitigated the induction of psoriatic-like lesions and correlated with altered expression of various skin cytokines.

Structural response of Photosystem 2 to iron deficiency: characterization of a new photosystem 2-IdiA complex from the cyanobacterium Thermosynechococcus elongatus BP-1.

Iron deficiency triggers various processes in cyanobacterial cells of which the synthesis of an additional antenna system (IsiA) around photosystem (PS) 1 is well documented [T.S. Bibby, J. Nield, J. Barber, Iron deficiency induces the formation of an antenna ring around trimeric photosystem I in cyanobacteria, Nature 412 (2001) 743-745, E.J. Boekema, A. Hifney, A.E. Yakushevska, M. Piotrowski, W. Keegstra, S. Berry, K.P. Michel, E.K. Pistorius, J. Kruip, A giant chlorophyll-protein complex induced by iron deficiency in cyanobacteria, Nature 412 (2001) 745-748]. Here we show that PS2 also undergoes prominent structural changes upon iron deficiency: Prerequisite is the isolation and purification of a PS2-IdiA complex which is exclusively synthesized under these conditions. Immunoblotting in combination with size exclusion chromatography shows that IdiA is only bound to dimeric PS2. Using single particle analysis of negatively stained specimens, IdiA can be localized in averaged electron micrographs on top of the CP43 subunit facing the cytoplasmic side in a model derived from the known 3D structure of PS2 [B. Loll, J. Kern, W. Saenger, A. Zouni, J. Biesiadka, Towards complete cofactor arrangement in the 3.0 A resolution structure of photosystem II, Nature 438 (2005) 1040-4]. The presence of IdiA as integral part of PS2 is the first example of a new PS2 protein being expressed under stress conditions, which is missing in highly purified PS2 complexes isolated from iron-sufficient cells.