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The researchers (left to right) Ester Ruiz, Laura Sòria, Lluís Santamaria, Ester Gil and David Cabrerizo (Photo:UB)

New evidence on molecular mechanisms involved in psoriasis outset

Two translational research studies published in the high impact scientific magazines Journal of Allergy and Clinical Immunology and Journal of Investigative Dermatology have described new immunologic mechanisms in psoriasis, a chronic cutaneous inflammatory disease which affects around the 2% of the population. The studies have been led by Lluís Francesc Santamaria, Director of the group of Translationary Immunology of the University of Barcelona (UB) based at the Barcelona Science Park, together with researchers of the Hospital del Mar and the Municipal Institute for Medical Research, among others.


The first study (doi: 10.1016/j.jaci.2016.02.008) focused on the evaluation of the molecular effects ofStreptococcus pyogenes, the bacteria which causes tonsillitis, and it is involved in the development of the psoriasis with drops (PG), a kind of psoriasis which is characterized by the appearance of small plaques, mainly in the body and extremities, and is usually found in young people. Although the causes of this disease are unknown, it usually happens after a tonsillitis infection, which seems to provoke an excessive autoimmune reaction. “The goal of the study was to elucidate the molecular response from the PG patients when facing the bacteria causing the infection, and if the initial immune response is favoured by the genetic and environmental antecedents of these patients”, said Lluís Francesc Santamaria, teacher of Immunology of the UB.

Although Streptococcus pyogenes being involved in the psoriasis outset was already known, people didn’t know about the molecular response from the immune system cells when facing its presence on skin. “In the study we have determined that the response in PG patients activates IL-17 protein, which would provoke the inflammatory response that leads to clinic manifestations of the illness. In addition, this reaction happens especially in samples that have HLACw6 allele. This new mechanism could help figuring out the sharp course and serious effects of the illness in some future” says Lluís Francesc Santamaria.

The second study (doi: has been published in the Journal of Investigative Dermatology, the international magazine with highest impact on Dermatology, and it shows another factor that helps understanding the IL-17 molecular response in psoriasis. According to the researchers, this cytokine induces enzyme expression on the patients’ skin. The enzyme expression is the MCPIP1 ribonuclease, which regulates the key genes expression in the development of the illness. “According to the important clinic efficiency of the IL-17 blocking in patients with psoriasis, the gene identification which are induced by IL-17 is very relevant to understand the appearance of the pathology”, says the researcher.

A model developed by researchers

The team of the UB has used a model with patients’ skin and lymph cells and healthy subjects, developed by the same researchers, reproducing the immune mechanisms involved in the psoriasis outset –in the laboratory. “It is important to work with the clinic material of the ill to understand a chronic inflammatory illness like psoriasis, because the animal models are not always predictive in humans”, said the researcher.

The Translational Immunology Research Group was recently honoured with the award Antoni Caparrós 2015, given by the Board of Trustees and Bosch i Gimpera Foundation (FBG) for the best project in knowledge transfer: “Transfer between academy and industry in translational immunology of psoriasis”, for their collaborations on the research of new psoriasis treatments with pharmaceutical industry, from the research lines by Lluís Francesc Santamaria.


• Reference articles:

E. Ruiz-Romeu, M. Ferran, A. Giménez-Arnau, B. Bugara, B. Lipert, J. Jura, E. Florencia, E. Prens, A. Celada, R. Pujol, L.F. Santamaria-Babí (2016). “MCPIP1 RNase is aberrantly distributed in psoriatic epidermis and rapidly induced by IL-17A”. Journal of Investigative Dermatology. May 2016. Doi:

E. Ruiz-Romeu, M. Ferran, M. Sagristà, J. Gómez, A. Giménez-Arnau, K. Herszenyi, P. Hóllo, A. Celada, R. Pujol, L.F. Santamaria-Babí (2016). “Streptococcus pyogenes-induced cutaneous lymphocyte antigen-positive T cell-dependent epidermal cell activation triggers TH17 responses in patients with guttate psoriasis”. J Allergy Clin Immunol. April 2016. Doi: 10.1016/j.jaci.2016.02.008