The immunosuppressive activity of polymeric micellar formulation of cyclosporine A: in vitro and in vivo studies

Pharmacologic Interventions to Immunologic and Immune-Mediated Conditions in Horses

Immunomodulators can stimulate, suppress, or regulate one or many aspects of the immune response. Use of a variety of immunostimulants, immunosuppressors, and anti-inflammatory drugs are described in horses, but the evidence supporting their efficacy is variable. Corticosteroids and nonsteroidal anti-inflammatory drugs are the best characterized immunomodulators in horses, but further study is needed to fully define their ideal dosing protocols and indications and to characterize the efficacy of other immunomodulators in equine medicine.

The Study of Cyclosporin A Nanocrystals Uptake and Transport across an Intestinal Epithelial Cell Model

Cyclosporin A nanocrystals (CsA-NCs) interaction with Caco-2 cells were investigated in this study, including cellular uptake and transport across Caco-2 cell monolayers. CsA-NCs of 165 nm, 240 nm and 450 nm were formulated. The dissolution of CsA-NCs was investigated by paddle method. The effect of size, concentration and incubation time on cellular uptake and dissolution kinetics of CsA-NCs in cells were studied. Uptake mechanisms were also evaluated using endocytotic inhibitors and low temperature (4 °C). The cell monolayers were incubated with each diameter CsA-NCs to evaluate the effect of size on the permeation characteristics of CsA across the intestinal mucosa. The results of dissolution study showed that 165 nm CsA-NC had the highest dissolution rate followed by 240 CsA-NC and finally 450 nm CsA-NC. The saturation of cell uptake of CsA-NCs was observed with the increase of incubation concentration and time. 240 nm and 450 nm CsA-NCs had the lowest and highest uptake efficiency at different time and drug concentration, respectively. The uptake of all three-sized CsA-NCs declined significantly in some different degree after the pre-treatment with different endocytosis inhibitors. 165 nm CsA-NC showed a highest transport capacity across monolayers at the same concentration and time. The results suggest that the size of CsA-NCs can not only affect the efficiency of cellular uptake, but also the type of endocytosis. Decreasing particle size of CsA-NCs can improve transport capacity of CsA through cell monolayer.

Implantable Immunosuppressant Delivery to Prevent Rejection in Transplantation

An innovative immunosuppressant with a minimally invasive delivery system has emerged in the biomedical field. The application of biodegradable and biocompatible polymer forms, such as hydrogels, scaffolds, microspheres, and nanoparticles, in transplant recipients to control the release of immunosuppressants can minimize the risk of developing unfavorable conditions. In this review, we summarized several studies that have used implantable immunosuppressant delivery to release therapeutic agents to prolong allograft survival. We also compared their applications, efficacy, efficiency, and safety/side effects with conventional therapeutic-agent administration. Finally, challenges and the future prospective were discussed. Collectively, this review will help relevant readers understand the different approaches to prevent transplant rejection in a new era of therapeutic agent delivery.

Pharmacokinetic and Tissue Distribution of Orally Administered Cyclosporine A-Loaded poly(ethylene oxide)-block-Poly(ε-caprolactone) Micelles versus Sandimmune® in Rats

PURPOSE

We have previously reported on a polymeric micellar formulation of Cyclosporine A (CyA) based on poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO_5K-b-PCL_13K) capable of changing drug biodistribution and pharmacokinetic profile following intravenous administration. The objective of the present study was to explore the potential of this formulation in changing the tissue distribution and pharmacokinetics of the encapsulated CyA following oral administration making comparisons with Sandimmune®.

METHODS

The in vitro CyA release and stability CyA-loaded PEO-b-PCL micelles (CyA-micelles) were evaluated in biorelevant media. The pharmacokinetics and tissue distribution of orally administered CyA-micelles or Sandimmune® and tissue distribution of traceable Cyanine-5.5 (Cy5.5)-conjugated PEO-b-PCL micelles were then investigated in healthy rats.

RESULTS

CyA-micelles showed around 60-70% CyA release in simulated intestinal and gastric fluids within 24 h, while Sandimmune® released its entire CyA content in the simulated intestinal fluid. CyA-micelles and Sandimmune® showed similar pharmacokinetics, but different tissue distribution profile in rats. In particular, the calculated AUC for CyA-micelles was higher in liver, comparable in heart, and lower in spleen, lungs, and kidneys when compared to that for Sandimmune®.

CONCLUSIONS

The results point to the influence of excipients in Sandimmune® on CyA disposition and more inert nature of PEO-b-PCL micelles in defining CyA biological interactions.

Insights into the modulatory role of cyclosporine A and its research advances in acute inflammation

Cyclosporine A(CsA), a classic immunosuppressant, is mainly applied for solid organ transplantation and some autoimmune diseases by suppressing T lymphocytes. Early studies showed that the application of CsA is primarily focused on chronic but not acute inflammation, nevertheless, increasing evidence supporting a role for CsA in acute inflammation, although most of proofs come from experimental models. It has long been known to us that the nuclear factor of activated T cells (NFAT) is the target of CsA to regulate T lymphocytes. However, NFAT also contributes to the regulation of innate immune cells, thus, CsA can not only target lymphocytes but also innate immune cells such as monocytes/macrophages, dendritic cells and neutrophils, which provides a basis for CsA to act on acute inflammation. Moreover, some other pathophysiological events in acute inflammation such as decreased vascular activity, mitochondrial dysfunction and endogenous cell apoptosis can also be alleviated by CsA. There being a moderate successes in the application of CsA for experimental acute inflammation such as sepsis, trauma/hemorrhagic shock and ischemic/reperfusion injury, yet data of the clinical treatment is not clear. In this review, we will critically analyze the existing hypotheses, summarize the application of CsA and its possible mechanisms in various acute inflammation over the past few decades, hope to provide some clues for the clinical treatment of acute inflammation.

Mesenchymal stem cell-derived exosomes suppress proliferation of T cells by inducing cell cycle arrest through p27kip1/Cdk2 signaling

Mouse mesenchymal stem cells (MSCs) have been shown to suppress T cells. Especially, MSC-cultured media have shown suppressive functions against various immune cells including the T cells. However, the underlying immunosuppressive mechanisms of the MSC-cultured medium are not yet fully understood. In this study, we confirmed the T cell-suppression capacity of MSC culture supernatant (MSC-CS) through both apoptosis and cell cycle arrest, and hypothesized that the exosomes were the major immunosuppressive agents in the MSC-CS. MSC-derived exosomes (MSC-exo) exhibited potent suppressive effects on T cell proliferation while the rest of the supernatant fraction did not. Interestingly, the exosomes derived from MSC only induced the cell cycle arrest, and it was through the upregulation of p27kip1 protein and downregulation of Cdk2 protein. In conclusion, the exosomes secreted from MSCs could suppress the activated T cell proliferation through the induction of cell cycle arrest.

Mitigation of Tacrolimus-Associated Nephrotoxicity by PLGA Nanoparticulate Delivery Following Multiple Dosing to Mice while Maintaining its Immunosuppressive Activity

The aim of this study was to assess the ability of PLGA nanoparticles (NPs) to reduce the tacrolimus (TAC)-associated nephrotoxicity following multiple dose administration. The mean diameter of prepared NPs was in the range of 227 to 263 nm with an 8.32% drug loading (w/w). Moreover, in vitro release profile of TAC-loaded NPs showed a sustained release of the drug with only less than 30% release within 12 days. Flow cytometry as well as fluorescence microscopy results confirmed the uptake of FITC-labelled PLGA NPs by dendritic cells. The ex vivo study showed that TAC-loaded NPs caused a significant suppression of the proliferation of CD4⁺ and CD8⁺ cells, which was comparable to the control formulation (Prograf). In vivo immunosuppressive activity as well as the kidney function were assessed following drug administration to mice. The animals received TAC subcutaneously at a daily dose of 1 mg/kg for 30 days delivered as the control formulation (Prograf) or TAC-loaded NPs. The results revealed significantly lower drug-associated toxicity with an activity comparable to Prograf for TAC-loaded PLGA NPs. These findings show a potential for PLGA NPs in reducing the nephrotoxicity of TAC while preserving the immunosuppressive activity.

The hurdles of nanotoxicity in transplant nanomedicine

Nanomedicine has matured significantly in the past 20 years and a number of nanoformulated therapies are cleared by regulatory agencies for use across the globe. Transplant medicine is one area that has significantly benefited from the advancement of nanomedicine in recent times. However, while nanoparticle-based therapies have improved toxicological profiles of some drugs, there are still a number of aspects regarding the biocompatibility and toxicity of nanotherapies that require further research. The goal of this article is to review toxicological profiles of immunosuppressant therapies and their conversion into nanomedicine formulations as well as introduce future challenges associated with current in vitro and in vivo toxicological models.

Modulation of innate immunity by cyclosporine A

Cyclosporine A has long been known to suppress T cell responses by inhibiting the production of IL-2, which drives T cell proliferation, enabling its use as a therapeutic for transplantation or autoimmunity. However, cyclosporine A also impacts on innate immune cells including dendritic cells, macrophages and neutrophils. In dendritic cells, which are essential for T cell priming, cyclosporine A can modulate both expression of surface molecules that engage with T cells and cytokine secretion, leading to altered induction of T cell responses. In macrophages and neutrophils, which play key antimicrobial roles, cyclosporine A reduces the production of cytokines that can play protective roles against pathogens. Some of these molecules, if produced in the context of chronic disease, can also contribute to pathology. There have been a number of elegant recent studies addressing the mechanisms by which cyclosporine A can modulate innate immunity. In particular, cyclosporine A inhibits the release of mitochondrial factors that stimulate the production of type 1 interferons by innate immune cells. This review addresses the emerging literature on modulation of innate immune responses by cyclosporine A, its resultant impact on adaptive immune responses and how this offers potential for new therapeutic applications.

Reformulating cyclosporine A (CsA): More than just a life cycle management strategy

Cyclosporine A (CsA) is a well-known immunosuppressive agent that gained considerable importance in transplant medicine in the late 1970s due to its selective and reversible inhibition of T-lymphocytes. While CsA has been widely used to prevent graft rejection in patients undergoing organ transplant it was also used to treat several systemic and local autoimmune disorders. Currently, the neuro- and cardio-protective effects of CsA (CiCloMulsion®; NeuroSTAT®) are being tested in phase II and III trials respectively and NeuroSTAT® received orphan drug status from US FDA and Europe in 2010. The reformulation strategies focused on developing Cremophor® EL free formulations and address variable bioavailability and toxicity issues of CsA. This review is an attempt to highlight the progress made so far and the room available for further improvements to realize the maximum benefits of CsA.

Establishment of animal models with orthotopic hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most serious health problems worldwide. Many researchers have investigated HCC at the level of genes, ribonucleic acid, proteins, cells, and animals. The resultant development of animal models and monitoring methods has improved the effectiveness of guidelines provided to researchers working with preclinical HCC models. HCC in animal models and clinical patients is monitored by various current imaging modalities such as ultrasound (US) imaging, computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), positron emission tomography (PET) and bioluminescence imaging (BLI). These techniques are currently used for both preclinical and clinical assessment, and provide valuable diagnostic information. In this article, we have mainly reviewed the established animal models and the assessment of orthotopic HCC using imaging modalities. Additionally, we have introduced a method of orthotopic HCC rat model developed in our laboratory. We have furthermore evaluated the occurrence of tumor mass using molecular imaging techniques.

Nanocarrier possibilities for functional targeting of bioactive peptides and proteins: state-of-the-art

This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.