Sustained Alleviation of Autoimmunity by Activating α2B-adrenergic Receptors.

Catecholamines binding to α- and ß-adrenergic receptors on immune cells have recently been shown to play an important role in regulating immune responses. Although α2-adrenergic receptors are known to modulate the immune response in different ways, the therapeutic exploration of their utility has been limited by the lack of agonists selective for the three α2-adrenergic subtypes. We report in this study the identification of the agonist AGN-762, which activates α2B- and α2C-adrenergic subtypes, but not the α2A subtype. We show that AGN-762 reduced clinical disease in an experimental autoimmune encephalitis model of autoimmune disease via direct or indirect effects on T regulatory cells. The activity of AGN-762 was abrogated by depletion of T regulatory cells, which express the α2B-adrenergic receptor. Furthermore, a drug-induced shift to an anti-inflammatory phenotype was demonstrated in immune cells in the spleen of drug-treated experimental autoimmune encephalitis mice. AGN-762 does not display sedative and cardiovascular side effects associated with α2A subtype agonists. Immune modulation by selective α2-adrenergic agonists represents a novel, to our knowledge, approach for treating autoimmune disease.

Preclinical Safety and Efficacy Assessments for Novel Femtosecond Lasers in Corneal Refractive Surgery.

Preclinical safety requirements and test methods have been standardized over time to guide medical device developers in the path needed to manufacture safe devices and achieve regulatory approval. Today, femtosecond lasers are commonly used in cataract and refractive surgeries. Currently, an industry standard to guide developers in preclinical testing of ophthalmic lasers does not exist. Consequently, the data presented in regulatory submissions may vary between manufacturers, making the regulatory review process more ambiguous. Here, the authors present a comprehensive discussion of preclinical test methods applied to the evaluation of an ophthalmic laser. We include in vitro and ex vivo models, as well as an in vivo rabbit model subject to corneal refractive treatments, for consideration in a preclinical safety evaluation plan. Scientific rationale to support the ocular endpoints of evaluation in the rabbit model to demonstrate safety is also presented and discussed.

Preclinical Safety Evaluation of Ophthalmic Viscosurgical Devices in Rabbits and a Novel Mini-Pig Model.

INTRODUCTION: To establish the preclinical safety and equivalency of ophthalmic viscosurgical devices (OVDs) comprised of bacterially sourced sodium hyaluronate (HA) to animal sourced HA using pyrogenicity and aqueous exchange models in rabbits and a novel mini-pig model to evaluate corneal endothelial cell protection in vivo. METHODS: HEALON OVD and HEALON5 OVD containing animal-derived HA and HEALON PRO OVD and HEALON5 PRO OVD containing bacterial-derived HA were used. Two rabbit aqueous exchange studies were conducted where aqueous humor was exchanged with OVDs in six animals each to observe potential ocular inflammation, intraocular pressure (IOP) response, corneal health and pachymetry until 7 days post procedure, as well as overall assessment of the OVDs. Endothelial cell protection was evaluated in a Yucatan mini-pig cataract surgery model where HEALON PRO and HEALON5 PRO OVDs were compared to HEALON and HEALON5 OVDs, respectively. Following cataract surgery with use of OVDs in six animals per study, animals were evaluated for ocular and general health, IOP, corneal thickness, ocular inflammation, and endothelial cell protection on days 1, 3, 7 and 14 post-surgery. RESULTS: All rabbit studies demonstrated equivalence between bacterial-derived and animal-derived OVDs. Mild, post-surgical irritation, IOP increase, and corneal thickness measurements were not significantly different in HEALON PRO OVD and HEALON5 PRO OVD compared to HEALON and HEALON5 OVDs, respectively. The mini-pig model developed to investigate endothelial cell protection was successful in demonstrating equivalence between the OVDs studied. Changes in IOP mirrored actual surgical procedures, while corneal pachymetry and endothelial cell density remained constant for all OVDs used. Slit lamp observations showed expected inflammation following surgical procedures, likely due to challenges encountered during surgical procedures. CONCLUSION: Rabbit pyrogenicity and aqueous exchanged paired with a novel simulated cataract surgery mini-pig model demonstrate equivalence of OVDs regardless of HA source. Albeit with challenges, the mini-pig model was shown to be a promising tool for endothelial cell evaluation during the development of new OVDs for ophthalmic use. FUNDING: Johnson & Johnson Surgical Vision, Inc.

Correlations of In Vitro Assays for Assessing Cytotoxicity and Biocompatibility of Contact Lens Multipurpose Solutions.

OBJECTIVES: To demonstrate correlations among in vitro assays used for assessing cytotoxicity of contact lens multipurpose solution (MPS) and propose the use of multiple assays as a part of preclinical evaluation for MPS biocompatibility assessment. METHODS: The effect of four different MPS on cell cytotoxicity, metabolic activity, and membrane integrity was performed by evaluating toxicity, expression of tight junction protein zonula occludens-1, and transepithelial electrical resistance in human corneal epithelial cells and Chinese hamster fibroblast cells. RESULTS: Cytotoxicity of four MPS was assayed with five different experimental systems at various concentrations. In vitro MPS-induced cytotoxicity was dependent on assay choice, concentration of MPS used, and duration of treatment. Overall, MPS-1 and MPS-2 were comparable to MPS-4 and better than MPS-3 in maintaining corneal barrier integrity and cell viability. CONCLUSIONS: In vitro cytotoxicity testing with MPS exposure to monolayer of cells in culture could be used as a tool to understand the potential cytotoxicity profiles of MPS and possibly a predictor of clinical outcome. Furthermore, MPS effects on in vitro cytotoxicity are best demonstrated by performing multiple assays to evaluate cell viability, metabolic activity, and membrane integrity during development.

Human neural precursor cells promote neurologic recovery in a viral model of multiple sclerosis.

Using a viral model of the demyelinating disease multiple sclerosis (MS), we show that intraspinal transplantation of human embryonic stem cell-derived neural precursor cells (hNPCs) results in sustained clinical recovery, although hNPCs were not detectable beyond day 8 posttransplantation. Improved motor skills were associated with a reduction in neuroinflammation, decreased demyelination, and enhanced remyelination. Evidence indicates that the reduced neuroinflammation is correlated with an increased number of CD4(+)CD25(+)FOXP3(+) regulatory T cells (Tregs) within the spinal cords. Coculture of hNPCs with activated T cells resulted in reduced T cell proliferation and increased Treg numbers. The hNPCs acted, in part, through secretion of TGF-ß1 and TGF-ß2. These findings indicate that the transient presence of hNPCs transplanted in an animal model of MS has powerful immunomodulatory effects and mediates recovery. Further investigation of the restorative effects of hNPC transplantation may aid in the development of clinically relevant MS treatments.

Intraspinal transplantation of mouse and human neural precursor cells.

This unit describes the preparation and transplantation of human neural precursor cells (hNPCs) and mouse neural precursor cells (mNPCs) into the thoracic region of the mouse spinal cord. The techniques in this unit also describe how to prepare the mouse for surgery by performing a laminectomy to expose the spinal cord for transplantation. NPCs genetically labeled with eGFP transplanted into the spinal cord of a mouse following viral-mediated demyelination can efficiently be detected via eGFP expression. Transplantation of these cells into the spinal cord is an efficacious way to determine their effects in neurological disorders such as multiple sclerosis, Alzheimer's disease, and spinal cord injury.

The anti-interferon activity of conserved viral dUTPase ORF54 is essential for an effective MHV-68 infection.

Gammaherpesviruses such as KSHV and EBV establish lifelong persistent infections through latency in lymphocytes. These viruses have evolved several strategies to counteract the various components of the innate and adaptive immune systems. We conducted an unbiased screen using the genetically and biologically related virus, MHV-68, to find viral ORFs involved in the inhibition of type I interferon signaling and identified a conserved viral dUTPase, ORF54. Here we define the contribution of ORF54 in type I interferon inhibition by ectopic expression and through the use of genetically modified MHV-68. ORF54 and an ORF54 lacking dUTPase enzymatic activity efficiently inhibit type I interferon signaling by inducing the degradation of the type I interferon receptor protein IFNAR1. Subsequently, we show in vitro that the lack of ORF54 causes a reduction in lytic replication in the presence of type I interferon signaling. Investigation of the physiological consequence of IFNAR1 degradation and importance of ORF54 during MHV-68 in vivo infection demonstrates that ORF54 has an even greater impact on persistent infection than on lytic replication. MHV-68 lacking ORF54 expression is unable to efficiently establish latent infection in lymphocytes, although it replicates relatively normally in lung tissues. However, infection of IFNAR-/- mice alleviates this phenotype, emphasizing the specific role of ORF54 in type I interferon inhibition. Infection of mice and cells by a recombinant MHV-68 virus harboring a site specific mutation in ORF54 rendering the dUTPase inactive demonstrates that dUTPase enzymatic activity is not required for anti-interferon function of ORF54. Moreover, we find that dUTPase activity is dispensable at all stages of MHV-68 infection analyzed. Overall, our data suggest that ORF54 has evolved anti-interferon activity in addition to its dUTPase enzymatic activity, and that it is actually the anti-interferon role that renders ORF54 critical for establishing an effective persistent infection of MHV-68.

Construction and characterization of an infectious murine gammaherpesivrus-68 bacterial artificial chromosome.

Here we describe the cloning of a sequenced WUMS isolate of murine gammaherpesvirus-68 (MHV-68, γHV-68, also known as MuHV-4) as a bacterial artificial chromosome (BAC). We engineered the insertion of the BAC sequence flanked by loxP sites into the left end of the viral genome before the M1 open reading frame. The infectious viruses were reconstituted following transfection of the MHV-68 BAC DNA into cells. The MHV-68 BAC-derived virus replicated indistinguishably from the wild-type virus in cultured cells. Excision of the BAC insert was efficiently achieved by coexpressing the Cre recombinase. Although the BAC insertion did not significantly affect acute productive infection in the lung, it severely compromised the ability of MHV-68 to establish splenic latency. Removal of the BAC sequence restored the wild-type level of latency. Site-specific mutagenesis was carried out by RecA-mediated recombination to demonstrate that this infectious BAC clone can be used for genetic studies of MHV-68.