Analyses of the toxic properties of recombinant human Cyclophilin A in mice.

Cyclophilin A (CypA), an 18 kDa multi-functional protein with cis-trans isomerase activity, is both a ligand for cyclosporine A and a proinflammatory factor. CypA is also a chemoattractant for hemopoietic stem cells and progenitors of different lineages, and can mediate regenerative processes in an organism. Accumulated experimental data have suggested there are practical applications for this protein in the treatment of several diseases (i.e. neutralization of cyclosporine A side effects, etc.). However, the range of CypA safe doses as well as its toxic effects remain unknown. The study here investigated the acute toxicity of a single intraperitoneal (IP) or subcutaneous (SC) dosing of recombinant human CypA (rhCypA) in both female and male mice and its effect on gene expression of acute phase proteins (APP) in the female mice after IP treatment. The results showed that toxicity of rhCypA was most evident in female and male mice dosed IP with 750 mg/kg, and manifested as kidney injury and increased granulocyte/lymphocyte ratios in the blood. Enhanced expression of Sаа1 and Sаа2 genes was induced with doses of 0.1-2 mg/mouse of rhCypA. Injection of the maximal dose (750 mg/kg) significantly stimulated expression of all the APP genes studied.

A novel elastin-like polypeptide drug carrier for cyclosporine A improves tear flow in a mouse model of Sjögren's syndrome.

As a potent macrolide immunosuppressant, cyclosporine A (CsA) is used to treat multiple autoimmune diseases, including non-autoimmune and autoimmune-mediated dry eye disease, rheumatoid arthritis and psoriasis. Despite its potency, CsA has poor solubility, poor bioavailability, and can cause serious adverse reactions such as nephrotoxicity and neurotoxicity. To overcome these limitations, we invented a new strategy to carry CsA by fusing its cognate human receptor, cyclophilin A (CypA), to a 73 kDa elastin-like polypeptide (ELP) termed A192 using recombinant protein expression. Derived from human tropoelastin, ELPs are characterized by the ability to phase separate above a temperature that is a function of variables including concentration, molecular weight, and hydrophobicity. The resultant fusion protein, termed CA192, which assembles into a dimeric species in solution, effectively binds and solubilizes CsA with a Kd of 189 nM, comparable to that of endogenous CypA with a Kd of 35.5 nM. The release profile of CsA from CA192 follows a one phase decay model with a half-life of 957.3 h without a burst release stage. Moreover, CA192-CsA inhibited IL-2 expression induced in Jurkat cells through the calcineurin-NFAT signaling pathway with an IC50 of 1.2 nM, comparable to that of free CsA with an IC50 of 0.5 nM. The intravenous pharmacokinetics of CA192 followed a two-compartment model with a mean residence time of 7.3 h. Subcutaneous administration revealed a bioavailability of 30% and a mean residence time of 15.9 h. When given subcutaneously for 2 weeks starting at 14 weeks in male non-obese diabetic (NOD) mice, a model of autoimmune dacryoadenitis used to study Sjögren's syndrome (SS), CA192-CsA (2.5 mg/kg, every other day) significantly (p = 0.014) increased tear production relative to CA192 alone. Moreover, CA192 delivery reduced indications of CsA nephrotoxicity relative to free CsA. CA192 represents a viable new approach to deliver this effective but nephrotoxic agent in a modality that preserves therapeutic efficacy but suppresses drug toxicity.

Cyclophilin A Maintains Glioma-Initiating Cell Stemness by Regulating Wnt/ß-Catenin Signaling.

Purpose: Glioma-initiating cells (GIC) are glioma stem-like cells that contribute to glioblastoma (GBM) development, recurrence, and resistance to chemotherapy and radiotherapy. They have recently become the focus of novel treatment strategies. Cyclophilin A (CypA) is a cytosolic protein that belongs to the peptidyl-prolyl isomerase (PPIase) family and the major intracellular target of the immunosuppressive drug cyclosporin A (CsA). In this study, we investigate the functions of CypA and its mechanism of action in GICs' development.Experimental Design: We analyzed differences in CypA expression between primary tumors and neurospheres from the GDS database, both before and after GIC differentiation. A series of experiments was conducted to investigate the role of CypA in GIC stemness, self-renewal, proliferation, radiotherapy resistance, and mechanism. We then designed glutathione S-transferase (GST) pulldown and coimmunoprecipitation assays to detect signaling activity.Results: In this study, we demonstrated that CypA promotes GIC stemness, self-renewal, proliferation, and radiotherapy resistance. Mechanistically, we found that CypA binds ß-catenin and is recruited to Wnt target gene promoters. By increasing the interaction between ß-catenin and TCF4, CypA enhances transcriptional activity.Conclusions: Our results demonstrate that CypA enhances GIC stemness, self-renewal, and radioresistance through Wnt/ß-catenin signaling. Due to its promotive effects on GICs, CypA is a potential target for future glioma therapy. Clin Cancer Res; 23(21); 6640-9. ©2017 AACR.

Cyclophilin A modulates bone marrow-derived CD117(+) cells and enhances ischemia-induced angiogenesis via the SDF-1/CXCR4 axis.

BACKGROUND: Critical limb ischemia (CLI) is a major health problem with no adequate treatment. Since CLI is characterized by insufficient tissue vascularization, efforts have focused on the discovery of novel angiogenic factors. Cyclophilin A (CyPA) is an immunophilin that has been shown to promote angiogenesis in vitro and to enhance bone marrow (BM) cell mobilization in vivo. However, its potential as an angiogenic factor in CLI is still unknown. Thus, this study aimed to evaluate whether CyPA might induce neo-angiogenesis in ischemic tissues. METHODS AND RESULTS: Wild-type C57Bl/6j mice underwent acute hind-limb ischemia (HLI) and received a single intramuscular administration of recombinant CyPA or saline. Limb perfusion, capillary density and arteriole number in adductor muscles were significantly increased after CyPA treatment. Interestingly, BM-derived CD117(+) cell recruitment was significantly higher in ischemic adductor tissue of mice treated with CyPA versus saline. Therefore, the effect of CyPA on isolated BM-derived CD117(+) cells in vitro was evaluated. Low concentrations of CyPA stimulated CD117(+) cell proliferation while high concentrations promoted cell death. Moreover, CyPA enhanced CD117(+) cell adhesion and migration in a dose-dependent manner. Mechanistic studies revealed that CyPA up-regulated CXCR4 in CD117(+) cells and in adductor muscles after ischemia. Additionally, SDF-1/CXCR4 axis inhibition by the CXCR4 antagonist AMD3100 decreased CyPA-mediated CD117(+) cell recruitment in the ischemic limb. CONCLUSION: CyPA induces neo-angiogenesis by recruiting BM-derived CD117(+) cell into ischemic tissues, at least in part, through SDF-1/CXCR4 axis.

Over-expression and potential role of cyclophilin A in human periodontitis.

BACKGROUND AND OBJECTIVE: We previously demostrated that EMMPRIN participates in the periodontitis and its interaction with Cyclophilin A possibly exists in animal periodontitis models. This study is aimed to address the expression and potential role of cyclophilin A (CypA) in human periodontitis. MATERIAL AND METHODS: Gingival tissues and peripheral blood were collected from patients with moderate to severe periodontitis or from healthy donors. Western blotting and immunohistochemistry were performed to detect the expression and distribution of CypA in the gingival tissues. Peripheral blood mononuclear cells (PBMCs) and neutrophils were isolated from the peripheral blood by Ficoll-Paque density-gradient centrifugation. Chemotaxis assays were applied to evaluate the effects of different concentrations of CypA (100, 300 and 500 ng/mL) on the migration of PBMCs and neutrophils. Supernatants of human THP-1 cells were collected after treatment with 200 ng/mL of CypA for different periods of time (1, 3, 6, 12 and 24 h) to detect the levels of interleukin (IL)-1ß, IL-8 and tumor necrosis factor alpha (TNF-α) by ELISA. RESULTS: Western blot analyses revealed an increase of CypA expression in inflamed gingival tissues compared with healthy tissues. Immunohistochemistry identified that the over-expressed CypA was localized in the infiltrating cells and/or in the extracellular matrix in the inflamed gingival connective tissues. The positive infiltrating cells contained mononuclear cells and lobulated-nuclei neutrophils. Chemotactic assays showed that 300 ng/mL of CypA apparently facilitated the chemotaxis of PBMCs/neutrophils from healthy donors, compared with the no-treatment control (p < 0.01 for PBMCs, p < 0.05 for neutrophils), whereas 100 and 500 ng/mL of CypA only weakly enhanced the chemotaxis of PBMCs/neutrophils (p > 0.05 for PBMCs/neutrophils, not significant). The PBMCs/neutrophils from patients with periodontitis exhibited a stronger ability to migrate when stimulated with 300 ng/mL of CypA than did PBMCs/neutrophils from healthy donors (p < 0.05 for PBMCs, p < 0.01 for neutrophils). ELISA revealed that the level of TNF-α secreted by THP-1 cells was elevated after treatment with 200 ng/mL of CypA for 12 h compared with the no-treatment 0-h control (p < 0.05). The IL-8 level was sharply raised after 3 h of stimulation with 200 ng/mL of CypA (p < 0.01 compared with 0 h), but no significant change was observed at the other time points (p > 0.05). There was no statistical difference at any of the treatment time points for the secretion of IL-1ß (p > 0.05 for 1, 3, 6, 12 and 24 h compared with 0 h). CONCLUSIONS: CypA participates in the pathogenesis of human periodontitis. It may be involved in the inflammatory response of periodontal tissues through inducing the chemotaxis of PBMCs/neutrophils and the secretion of TNF-α/IL-8.