Cyclophilin A Plays Potential Roles in a Rat Model of Asthma and Suppression of Immune Response

Cyclophilin A (CypA) inhibits CD4⁺ T cell signal transduction via interleukin-2-inducible T-cell kinase (Itk), a tyrosine kinase required for T helper (Th) 2 cells function. Furthermore, mice with CypA silencing developed allergic diseases associated with increased Th2 cytokines production. CD4⁺ T cells with a Th2-cytokine pattern have been demonstrated to have a pivotal role in the pathogenesis of asthma. However, the effects of CypA in regulating immunity in asthma and in relieving asthmatic symptoms in vivo are entirely unknown.

Recombinant CypA protein (rCypA) was generated and purified. Ovalbumin (OVA)-challenged asthmatic rats model and acetylcholine chloride (ACh)-induced contraction of tracheal spirals were established. The pulmonary resistance (RL) value of asthmatic rats in vivo and the isometric tension of tracheal spirals ex vivo were recorded by MFLab 3.01 software. The levels of Th1 and Th2 cytokines and the quantities of immunoglobulin (IgA, IgG, IgM and IgE) in the supernatants of rat spleen lymphocytes were detected and analysed by bio-plex Suspension Array System and ELISA, respectively. CD4⁺ T cells were separated by MicroBeads, and the levels of interleukin (IL)-4 and interferon-γ (IFN-γ) were detected by ELISA.

rCypA (10 ng/kg) significantly reduced RL within 2-7 min in OVA-challenged asthmatic rats in vivo, and there were no significant differences compared with terbutaline (TB) and hydrocortisone (HC). Furthermore, rCypA (10 ng/mL) significantly reduced the isometric tension in the ACh-induced contraction of the tracheal spiral ex vivo, and the effect of rCypA was better than that of TB. Additionally, rCypA suppressed the secretion of both Th1 and Th2 cytokines, and the suppressive effects of rCypA were stronger than those of HC, especially on Th2 cytokines.

These findings indicate that CypA may serve as a potential novel therapeutic strategy for asthma.