Immune plexins and semaphorins: old proteins, new immune functions

Plexins and semaphorins are a large family of proteins that are involved in cell movement and response. The importance of plexins and semaphorins has been emphasized by their discovery in many organ systems including the nervous (Nkyimbeng-Takwi and Chapoval, 2011; McCormick and Leipzig, 2012; Yaron and Sprinzak, 2012), epithelial (Miao et al., 1999; Fujii et al., 2002), and immune systems (Takamatsu and Kumanogoh, 2012) as well as diverse cell processes including angiogenesis (Serini et al., 2009; Sakurai et al., 2012), embryogenesis (Perala et al., 2012), and cancer (Potiron et al., 2009; Micucci et al., 2010). Plexins and semaphorins are transmembrane proteins that share a conserved extracellular semaphorin domain (Hota and Buck, 2012). The plexins and semaphorins are divided into four and eight subfamilies respectively based on their structural homology. Semaphorins are relatively small proteins containing the extracellular semaphorin domain and short intra-cellular tails. Plexins contain the semaphorin domain and long intracellular tails (Hota and Buck, 2012). The majority of plexin and semaphorin research has focused on the nervous system, particularly the developing nervous system, where these proteins are found to mediate many common neuronal cell processes including cell movement, cytoskeletal rearrangement, and signal transduction (Choi et al., 2008; Takamatsu et al., 2010). Their roles in the immune system are the focus of this review

B(1) and B(2) kinin receptor blockade improves psoriasis-like disease

BACKGROUND AND PURPOSE: Evidence indicates that the entire kallikrein‐kinin system is present in the skin, and it is thought to exert a relevant role in cutaneous diseases, including psoriasis. Thus, the present study was designed to evaluate the relevance of kinin receptors in the development and progression of a psoriasis mice model. EXPERIMENTAL APPROACH: Kinin B(1) and B(2) receptor knockout mice as well as C57BL/6 wild type (WT) mice treated with kinin receptor antagonists (SSR240612C or FR173657) were submitted to the Imiquimod (IMQ)‐induced psoriasis model. KEY RESULTS: Both kinin receptors were upregulated following 6 days of IMQ treatment. Kinin B(1) and B(2) receptor deficiency as well as the use of selective antagonists, show morphological and histological improvement of the psoriasis hallmarks. This protective effect was associated with a decrease in undifferentiated and proliferating keratinocytes, decreased cellularity (neutrophils, macrophages, CD4(+) T lymphocytes), reduced γδ T cells as well as lower accumulation of IL‐17. The lack of B(2) receptors resulted in reduced CD8(+) T cells in the psoriatic skin. Relevantly, blocking kinin receptors reflected the improvement of psoriasis disease in the well‐being behaviour of the mice. CONCLUSIONS AND IMPLICATIONS: The present results have provided clear experimental evidence that kinins exert a critical role in IMQ‐induced psoriasis. Both B(1) and B(2) kinin receptors exacerbate the disease development, influencing keratinocyte proliferation and immunopathology. Therefore, the use of antagonists for one or even both kinin receptors might constitute a new strategy for psoriasis clinical treatment