Gliadin Nanoparticles Induce Immune Tolerance to Gliadin in Mouse Models of Celiac Disease.

BACKGROUND & AIMS: Celiac disease could be treated, and potentially cured, by restoring T-cell tolerance to gliadin. We investigated the safety and efficacy of negatively charged 500-nm poly(lactide-co-glycolide) nanoparticles encapsulating gliadin protein (TIMP-GLIA) in 3 mouse models of celiac disease. Uptake of these nanoparticles by antigen-presenting cells was shown to induce immune tolerance in other animal models of autoimmune disease. METHODS: We performed studies with C57BL/6; RAG1-/- (C57BL/6); and HLA-DQ8, huCD4 transgenic Ab0 NOD mice. Mice were given 1 or 2 tail-vein injections of TIMP-GLIA or control nanoparticles. Some mice were given intradermal injections of gliadin in complete Freund's adjuvant (immunization) or of soluble gliadin or ovalbumin (ear challenge). RAG-/- mice were given intraperitoneal injections of CD4+CD62L-CD44hi T cells from gliadin-immunized C57BL/6 mice and were fed with an AIN-76A-based diet containing wheat gluten (oral challenge) or without gluten. Spleen or lymph node cells were analyzed in proliferation and cytokine secretion assays or by flow cytometry, RNA sequencing, or real-time quantitative polymerase chain reaction. Serum samples were analyzed by gliadin antibody enzyme-linked immunosorbent assay, and intestinal tissues were analyzed by histology. Human peripheral blood mononuclear cells, or immature dendritic cells derived from human peripheral blood mononuclear cells, were cultured in medium containing TIMP-GLIA, anti-CD3 antibody, or lipopolysaccharide (controls) and analyzed in proliferation and cytokine secretion assays or by flow cytometry. Whole blood or plasma from healthy volunteers was incubated with TIMP-GLIA, and hemolysis, platelet activation and aggregation, and complement activation or coagulation were analyzed. RESULTS: TIMP-GLIA did not increase markers of maturation on cultured human dendritic cells or induce activation of T cells from patients with active or treated celiac disease. In the delayed-type hypersensitivity (model 1), the HLA-DQ8 transgenic (model 2), and the gliadin memory T-cell enteropathy (model 3) models of celiac disease, intravenous injections of TIMP-GLIA significantly decreased gliadin-specific T-cell proliferation (in models 1 and 2), inflammatory cytokine secretion (in models 1, 2, and 3), circulating gliadin-specific IgG/IgG2c (in models 1 and 2), ear swelling (in model 1), gluten-dependent enteropathy (in model 3), and body weight loss (in model 3). In model 1, the effects were shown to be dose dependent. Splenocytes from HLA-DQ8 transgenic mice given TIMP-GLIA nanoparticles, but not control nanoparticles, had increased levels of FOXP3 and gene expression signatures associated with tolerance induction. CONCLUSIONS: In mice with gliadin sensitivity, injection of TIMP-GLIA nanoparticles induced unresponsiveness to gliadin and reduced markers of inflammation and enteropathy. This strategy might be developed for the treatment of celiac disease.

Structural proteins of West Nile virus are a major determinant of infectious particle production and fitness in astrocytes.

The molecular basis for the increased resistance of astrocytes to a non-neuropathogenic strain of West Nile virus (WNV), WNV-MAD78, compared with the neuropathogenic strain WNV-NY remains unclear. Here, we demonstrated that the reduced susceptibility of astrocytes to WNV-MAD78 is due to a combination of both cellular activities as well as viral determinants. Analyses of the viral particle indicated that astrocyte-derived WNV-MAD78 particles were less infectious than those of WNV-NY. Additionally, inhibition of cellular furin-like proteases increased WNV-MAD78 infectious particle production in astrocytes, suggesting that high levels of furin-like protease activity within these cells acted in a cell- and strain-specific manner to inhibit WNV-MAD78 replication. Moreover, analysis of recombinant viruses indicated that the structural proteins of WNV-MAD78 were responsible for decreased particle infectivity and the corresponding reduction in infectious particle production compared with WNV-NY. Thus, the composition of the WNV virion was also a major determinant for viral fitness within astrocytes and may contribute to WNV propagation within the central nervous system. Whether the WNV-MAD78 structural genes reduce virus replication and particle infectivity through the same mechanism as the cellular furin-like protease activity or whether these two determinants function through distinct pathways remains to be determined.

IFN-dependent and -independent reduction in West Nile virus infectivity in human dermal fibroblasts.

Although dermal fibroblasts are one of the first cell types exposed to West Nile virus (WNV) during a blood meal by an infected mosquito, little is known about WNV replication within this cell type. Here, we demonstrate that neuroinvasive, WNV-New York (WNV-NY), and nonneuroinvasive, WNV-Australia (WNV-AUS60) strains are able to infect and replicate in primary human dermal fibroblasts (HDFs). However, WNV-AUS60 replication and spread within HDFs was reduced compared to that of WNV-NY due to an interferon (IFN)-independent reduction in viral infectivity early in infection. Additionally, replication of both strains was constrained late in infection by an IFN-ß-dependent reduction in particle infectivity. Overall, our data indicates that human dermal fibroblasts are capable of supporting WNV replication; however, the low infectivity of particles produced from HDFs late in infection suggests that this cell type likely plays a limited role as a viral reservoir in vivo.

Generation of West Nile virus infectious clones containing amino acid insertions between capsid and capsid anchor.

West Nile virus (WNV) is a positive-sense RNA arbovirus responsible for recent outbreaks of severe neurological disease within the US and Europe. Large-scale analyses of antiviral compounds that inhibit virus replication have been limited due to the lack of an adequate WN reporter virus. Previous attempts to insert a reporter into the 3' untranslated region of WNV generated unstable viruses, suggesting that this region does not accommodate additional nucleotides. Here, we engineered two WNV infectious clones containing insertions at the Capsid (C)/Capsid Anchor (CA) junction of the viral polyprotein. Recombinant viruses containing a TAT(1-67) or Gaussia Luciferase (GLuc) gene at this location were successfully recovered. However, rapid loss of most, if not all, of the reporter sequence occurred for both viruses, indicating that the reporter viruses were not stable. While the GLuc viruses predominantly reverted back to wild-type WNV length, the TAT viruses retained up to 75 additional nucleotides of the reporter sequence. These additional nucleotides were stable over at least five passages and did not significantly alter WNV fitness. Thus, the C/CA junction of WNV can tolerate additional nucleotides, though insertions are subject to certain constraints.

Small molecule inhibitors of Ago2 decrease Venezuelan equine encephalitis virus replication.

Venezuelan equine encephalitis virus (VEEV) is classified as a Category B Select Agent and potential bioterror weapon for its severe disease course in humans and equines and its potential for aerosol transmission. There are no current FDA licensed vaccines or specific therapies against VEEV, making identification of potential therapeutic targets a priority. With this aim, our research focuses on the interactions of VEEV with host microRNA (miRNA) machinery. miRNAs are small non-coding RNAs that act as master regulators of gene expression by downregulating or degrading messenger RNA, thus suppressing production of the resultant proteins. Recent publications implicate miRNA interactions in the pathogenesis of various viral diseases. To test the importance of miRNA processing for VEEV replication, cells deficient in Ago2, an important component of the RNA-induced silencing complex (RISC), and cells treated with known Ago2 inhibitors, notably acriflavine (ACF), were utilized. Both conditions caused decreased viral replication and capsid expression. ACF treatment promoted increased survival of neuronal cells over a non-treated, infected control and reduced viral titers of fully virulent VEEV as well as Eastern and Western Equine Encephalitis Viruses and West Nile Virus, but not Vesicular Stomatitis Virus. ACF treatment of VEEV TC-83 infected mice resulted in increased in vivo survival, but did not affect survival or viral loads when mice were challenged with fully virulent VEEV TrD. These results suggest that inhibition of Ago2 results in decreased replication of encephalitic alphaviruses in vitro and this pathway may be an avenue to explore for future therapeutic development.