A rapamycin-binding protein polymer nanoparticle shows potent therapeutic activity in suppressing autoimmune dacryoadenitis in a mouse model of Sjögren's syndrome

Abstract

Sjögren’s syndrome (SjS) is a chronic autoimmune disease characterized initially by lymphocytic infiltration and destruction of exocrine glands, followed by systemic organ damage and B-cell lymphoma. Conventional treatment is based on management of symptoms and there is a shortage of therapies that address the underlying causes of inflammation at source exocrine tissue. The aim of this study was to test a novel protein polymer-based platform consisting of diblock copolymers composed from Elastin-like Polypeptides (ELPs) fused with FKBP12, to deliver a potent immunosuppressant with dose-limiting toxicity, rapamycin (Rapa) also known as Sirolimus, and evaluate its effects on the inflamed lacrimal gland (LG) of non-obese diabetic mouse (NOD), a classic mouse model of SjS. Both soluble and diblock copolymer ELPs were fused to FKBP12 and characterized with respect to purity, hydrodynamic radii, drug entrapment and release. Both formulations showed successful association with Rapa; however, the nanoparticle formulation, FSI, released drug with nearly a 5 fold longer terminal half-life of 62.5h. The strong interaction of FSI nanoparticles with Rapa was confirmed in vivo by a shift in the monoexponential pharmacokinetic profile for free drug to a biexponential profile for the nanoparticle formulation. When acutely administered by injection into NOD mice via the tail vein, this FSI formulation significantly suppressed lymphocytic infiltration in the LG relative to the control group while reducing toxicity. There was also a significant effect on inflammatory and mammalian target of Rapamycin (mTOR) pathway genes in the LG and surprisingly, our nanoparticle formulation was significantly better at decreasing a proposed tear biomarker of SjS, cathepsin S (CATS) compared to free drug. These findings suggest that FSI is a promising tool for delivering Rapa for treatment of SjS in a murine model and may be further explored to meet the unmet medical challenge of SjS.

Genetically engineered nanocarriers for drug delivery

“…57 Recombinant protein fusion technology is one of the major advantages in genetically engineered nanocarrier delivery and has been widely used in many applications. 31,42,43 Compared with chemically synthesized carriers that require complicated and low-efficiency chemical conjugation reactions with many byproducts, genetically engineered nanocarriers utilize fast and efficient molecular cloning technique to link the drug or other functional domains onto the carriers at the DNA level. When biosynthesized, the resulting fusion products have nearly perfect homogeneity and monodispersity in large (mg to g) quantities.…”

“…In the last 2-3 years, multiple articles have been published focusing on these nanocarriers in the delivery of genes and drugs. 6,26,27,29,31,[41][42][43] …”

“…It was discovered that FSI-Rapa showed not only significantly less cytotoxicity but greater efficacy in tumor regression and autoimmune response suppression than the free drug, respectively, in the two models ( Figure 3C and D). 42,43 In addition, the blood half-lives of ELPs in mice were estimated by a multi-compartmental pharmacokinetic model using the data from noninvasive micro-PET (positron emission tomography) imaging. Depending on molecular weight and assembled structure, the blood half-lives of ELPs vary from 2 to 6 hours in vivo ( Figure 3E).…”

Immunosuppressive and anti‐inflammatory properties of engineered nanomaterials

“…Cyclosporine Liposomes (Freise et al, 1994;Shah et al, 2006); polymeric NP (Gref et al, 2001;Italia et al, 2007;Azzi et al, 2010;Tang et al, 2012); lipid NP (Muller et al, 2008) Preclinical Tacrolimus Lipid NP (Pople and Singh, 2012); polymeric NP (Tammam et al, 2012); liposomes (Erdogan et al, 2002;Zhang et al, 2010) Preclinical Rapamycin/sirolimus Polymeric NP (Yuan et al, 2008;Woo et al, 2012;Shah et al, 2013); micelles (Yanez et al, 2008;Chen et al, 2013); liposomes (Rouf et al, 2009;Ghanbarzadeh et al, 2013) Preclinical Mycophenolic acid Polymeric NP (Shirali et al, 2011); nanogels (Look et al, 2013); dendrimers (Hu et al, 2009) Preclinical Corticosteroids Liposomes Linker et al, 2008;Schweingruber et al, 2011;Ulmansky et al, 2012); polymeric NP (Ishihara et al, 2005;Matsuo et al, 2009); solid lipid NP (Jensen et al, 2010;Zhang and Smith, 2011); dendrimers (Khandare et al, 2005) Preclinical Non-steroidal anti-inflammatory Dendrimers (Chauhan et al, 2004;Na et al, 2006;Chandrasekar et al, 2007;Cheng et al, 2007); nanocolloid (Milkova et al, 2013); lipid NP (Castelli et al, 2005); liposomes (Paavola et al, 2000;Srinath et al, 2000;Turker et al, 2008)…”

“…The adverse effects observed in patients treated with mTOR inhibitors include, but are not limited to, dose-dependent hyperlipidaemias, kidney toxicity, dermatological complications and bone marrow suppression (Campistol et al, 2010;Kahan, 2011). Formulation of rapamycin using nanotechnology has helped to overcome its poor solubility, improve its safety profile and increase its therapeutic efficacy Chen et al, 2013;Shah et al, 2013). Delivery of rapamycin by elastin-like polymeric nanoparticles has been associated with reduced kidney toxicity and injection site reactions, yet demonstrated therapeutic efficacy comparable to, or in some parameters even exceeding, that of the free drug in a mouse model of Sjogren syndrome, a systemic autoimmune disorder destroying exocrine glands, which produce tears and saliva (Shah et al, 2013).…”