Tomoko Yamaguchi

Fiber-Modified Adenovirus Vectors Decrease Liver Toxicity through Reduced IL-6 Production

Adenovirus (Ad) vectors are one of the most commonly used viral vectors in gene therapy clinical trials. However, they elicit a robust innate immune response and inflammatory responses. Improvement of the therapeutic index of Ad vector gene therapy requires elucidation of the mechanism of Ad vector-induced inflammation and cytokine/chemokine production as well as development of the safer vector. In the present study, we found that the fiber-modified Ad vector containing poly-lysine peptides in the fiber knob showed much lower serum IL-6 and aspartate aminotransferase levels (as a maker of liver toxicity) than the conventional Ad vector after i.v. administration, although the modified Ad vector showed higher transgene production in the liver than the conventional Ad vector. RT-PCR analysis showed that spleen, not liver, is the major site of cytokine, chemokine, and IFN expression. Splenic CD11c+ cells were found to secret cytokines. The tissue distribution of Ad vector DNA showed that spleen distribution was much reduced in this modified Ad vector, reflecting reduced IL-6 levels in serum. Liver toxicity by the conventional Ad vector was reduced by anti-IL-6R Ab, suggesting that IL-6 signaling is involved in liver toxicity and that decreased liver toxicity of the modified Ad vector was due in part to the reduced IL-6 production. This study contributes to an understanding of the biological mechanism in innate immune host responses and liver toxicity toward systemically administered Ad vectors and will help in designing safer gene therapy methods that can reduce robust innate immunity and inflammatory responses.

Engagement of 4-1BB Inhibits the Development of Experimental Allergic Conjunctivitis in Mice

The 4-1BB receptor acts as a costimulator in CD8+ T cell activation. Agonistic stimulation through this molecule by treatment with anti-4-1BB Abs has been demonstrated to inhibit various experimentally induced diseases in animals. However, the effect of anti-4-1BB Abs on experimental allergic diseases has not been reported. We investigated the effect of anti-4-1BB Abs on the development and progression of experimental allergic conjunctivitis in mice. To examine the effects of Abs during the induction or effector phase, actively immunized mice or passively immunized mice by splenocyte transfer were treated with agonistic anti-4-1BB Abs, blocking anti-4-1BB ligand Abs, or normal rat IgG. Eosinophil infiltration into the conjunctiva was significantly reduced in wild-type mice by the anti-4-1BB Ab treatment during either induction or effector phase. Th2 cytokine production by splenocytes and total serum IgE were significantly reduced by the anti-4-1BB Ab treatment, while IFN-γ production was increased. The anti-4-1BB Ab treatment induced a relative increase of CD8-positive cell numbers in the spleens. Moreover, inhibition of eosinophil infiltration by the treatment with anti-4-1BB Abs was also noted in actively immunized IFN-γ knockout mice. Taken altogether, in vivo treatment with agonistic anti-4-1BB Abs in either induction or effector phase inhibits the development of experimental allergic conjunctivitis, and this inhibition is likely to be mediated by suppression of Th2 immune responses rather than up-regulation of IFN-γ.

Induction of type I interferon by adenovirus-encoded small RNAs

Transduction with replication-incompetent recombinant adenovirus (Ad) vectors results in a rapid activation of innate immune responses, such as inflammatory cytokine production and subsequent tissue damage. The precise mechanisms of the innate immune responses induced by Ad vectors remain to be clarified. Possible components of Ad vectors that activate innate immune responses are the capsid protein, the viral genome (DNA), and viral transcripts. In the present study, we demonstrate that virus-associated RNAs (VA-RNAs), which are small RNAs transcribed by RNA polymerase III, induce the production of type I IFN (IFN-α and IFN-β), but they do not induce the production of inflammatory cytokines (IL-6 and IL-12), in mouse embryonic fibroblasts (MEFs) and granulocyte-macrophage colony-stimulating factor–generated bone marrow-derived dendritic cells (GM-DCs). We also show that IFN-β promoter stimulator-1 is involved in VA-RNA–dependent IFN-β production in MEFs and is partially involved in type I IFN production in GM-DCs. This study provides important insight into the mechanisms of Ad vector-triggered innate immune responses, which may lead to more advanced and rational Ad vector designs for gene therapies and vaccine applications.

Involvement of programmed death-ligand 2 (PD-L2) in the development of experimental allergic conjunctivitis in mice

Background/aim: Involvement of programmed death-1 (PD-1) and its ligands has been demonstrated in experimental allergic airway disease. Here, the authors aimed to examine whether PD-1 and its ligands are involved in the development of experimental allergic conjunctivitis (EC) in mice. Methods: EC was induced in Balb/c mice by active immunisation with short ragweed pollen (RW) in alum. 10 days later (day 10), the mice were challenged with eye drops containing RW. 24 hours after the challenge, conjunctivas, spleens, and sera were harvested for histological analysis, cytokine assays, and measurement of RW specific Ig levels. The actively immunised mice were treated with anti-PD-1, anti-PD-L1, anti-PD-L2 antibodies (Abs), or normal rat immunoglobulin G (nrIgG) during either the induction (day 0, 2, 4, 6, and 8) or the effector (2 hours before RW challenge on day 10) phase. Results: Ab treatment during the induction phase did not affect eosinophil infiltration although immune responses were modulated. In contrast, treatment with anti-PD-L2 Ab, but not anti-PD-1 or anti-PD-L1 Ab, during the effector phase significantly increased eosinophil infiltration into the conjunctiva without affecting systemic immune responses. Conclusions: Similar to allergic airway inflammation, PD-L2 is involved in the development of EC during the effector phase but not the induction phase.

Cyclosporin A inhibits eosinophilic infiltration into the conjunctiva mediated by type IV allergic reactions.

Background:  Eosinophils are important effector cells in severe allergic conjunctivitis such as vernal keratoconjunctivitis. Infiltration of eosinophils into the conjunctiva is mediated by type I and type IV allergic reactions. Cyclosporin A (CsA) eye drops are administered therapeutically for severe allergic conjunctivitis, but the mechanism by which CsA acts, that is, by inhibiting type I, type IV or both types of allergic reactions, is not known. We investigated whether CsA eye drops inhibit type I, type IV or both types of allergic reactions in the conjunctiva.

CCAAT/enhancer binding protein-mediated regulation of TGFβ receptor 2 expression determines the hepatoblast fate decision

Human embryonic stem cells (hESCs) and their derivatives are expected to be used in drug discovery, regenerative medicine and the study of human embryogenesis. Because hepatocyte differentiation from hESCs has the potential to recapitulate human liver development in vivo, we employed this differentiation method to investigate the molecular mechanisms underlying human hepatocyte differentiation. A previous study has shown that a gradient of transforming growth factor beta (TGFβ) signaling is required to segregate hepatocyte and cholangiocyte lineages from hepatoblasts. Although CCAAT/enhancer binding proteins (c/EBPs) are known to be important transcription factors in liver development, the relationship between TGFβ signaling and c/EBP-mediated transcriptional regulation in the hepatoblast fate decision is not well known. To clarify this relationship, we examined whether c/EBPs could determine the hepatoblast fate decision via regulation of TGFβ receptor 2 (TGFBR2) expression in the hepatoblast-like cells differentiated from hESCs. We found that TGFBR2 promoter activity was negatively regulated by c/EBPα and positively regulated by c/EBPβ. Moreover, c/EBPα overexpression could promote hepatocyte differentiation by suppressing TGFBR2 expression, whereas c/EBPβ overexpression could promote cholangiocyte differentiation by enhancing TGFBR2 expression. Our findings demonstrated that c/EBPα and c/EBPβ determine the lineage commitment of hepatoblasts by negatively and positively regulating the expression of a common target gene, TGFBR2, respectively.

Mice lacking the IFN-γ receptor or fyn develop severe experimental autoimmune uveoretinitis characterized by different immune responses

Endogenous interferon (IFN)-γ negatively regulates experimental autoimmune uveoretinitis (EAU), a Th1-mediated disease. Although it is well known that IFN-γ exerts its effects by binding to the IFN-γ receptor (IFN-γR), the role that IFN-γR plays in the development of EAU has not been investigated. Fyn has been reported to inhibit Th2 differentiation. We aimed to investigate how endogenous IFN-γR and fyn, which influence Th1/Th2 differentiation, participate in the development of EAU. Sex-matched 6- to 10-week-old C57BL/6 wild-type (WT), IFN-γR knockout (GRKO) and fyn knockout (fyn KO) mice were compared. Mice were immunized subcutaneously with human interphotoreceptor retinoid-binding protein peptide 1–20 emulsified in Freund’s complete adjuvant together with an intraperitoneal injection of Bordetella pertussis toxin. Three weeks later, mice were sacrificed, and their eyes and spleens were harvested for histopathologic analyses and examination of cellular immune responses, respectively. Cellular immune responses were evaluated by measuring the proliferative responses and cytokine production [interleukin (IL)-4, IL-5, IL-6, IL-13, IFN-γ and tumor necrosis factor (TNF)-α] of splenocytes. The incidence of EAU was 40.0% in WT mice, 59.3% in GRKO mice and 78.6% in fyn KO mice. The average EAU score was 0.294 in WT mice, 0.917 in GRKO mice and 1.063 in fyn KO mice. Upon EAU induction, significant infiltration of eosinophils into the eyes was observed in GRKO and fyn KO mice compared to WT mice. Splenocytes from GRKO mice proliferated against the antigen and a mitogen more vigorously than those from WT and fyn KO mice. Stimulation of splenocytes with the antigen induced a higher production of IL-4, IL-6, IL-13 and IFN-γ in GRKO mice compared to WT and fyn KO mice. In contrast, IL-5 and TNF-α were most abundantly produced by splenocytes from fyn KO mice compared to WT and GRKO mice. The incidence and mean severity of EAU were significantly higher in GRKO and fyn KO mice than in WT mice, suggesting that endogenous IFN-γR and fyn negatively regulate the development of EAU. The different cytokine production patterns by the GRKO and fyn KO mice indicate that the negative regulatory mechanism mediated by IFN-γR and fyn may differ.

An effective gene-knockdown using multiple shRNA-expressing adenovirus vectors

Viral vectors expressing short hairpin RNA (shRNA) are attractive for efficient and tissue-specific RNA interference (RNAi) delivery. We and others previously reported that recombinant adenovirus (Ad) vector-mediated RNAi has great potential for a variety of applications in molecular biology studies and gene therapy. In the present study, we have developed an efficient Ad vector-mediated RNAi system, in which an Ad vector carries four shRNA-expression cassettes (Ad-multi-shRNA vector), a simple and effective strategy for enhancing the RNAi response per Ad vector particle. The data demonstrated that the Ad-multi-shRNA vectors showed an enhanced RNAi effect compared to conventional Ad vectors containing a single shRNA-expression cassette. An application of the Ad-multi-shRNA vector carrying four same shRNA-sequences against the RET finger protein, an oncogene known to desensitize cells to oxidative stress and cisplatin, resulted in an enhanced cytotoxic effect of cisplatin, demonstrating the advantages of the Ad-multi-shRNA vector for silencing target genes. Furthermore, an Ad-multi-shRNA carrying four different shRNA-sequences efficiently silenced the multiple target genes simultaneously. These data suggest the potential usefulness of the Ad-multi-shRNA vector not only in basic research but also in clinical gene therapy.

Development of an adenovirus vector lacking the expression of virus-associated RNAs.

A major limitation of the use of adenovirus (Ad) vectors is the innate immune response, which causes inflammatory cytokine production and tissue damages. To overcome this limitation, it is necessary to develop safer Ad vectors that are less likely to induce innate immunity. The Ad genome encodes two non-coding small RNAs, virus-associated (VA)-RNA I and VA-RNA II, which are transcribed by RNA polymerase III and promote Ad replication. Recently, we reported that VA-RNAs are produced in the cells transduced with a conventional first-generation (E1-deleted) Ad vector (FG-Ad) and trigger innate immune responses through intracellular nucleic acid sensors. In the present study, we have developed a VA-RNA-deleted Ad (AdΔVR) vector, in which the transcriptional control elements of the VA-RNA-expression were deleted. Although conventional HEK293 cells did not support the propagation of the AdΔVR vectors, HEK293 transformants inducibly expressing VA-RNA I (VR293 cells) with appropriate induction of VA-RNA I expression allowed the propagation of the AdΔVR vector. The AdΔVR vector showed high transduction efficiency comparable to that of the conventional FG-Ad vector in the cultured cells. The AdΔVR vector may be a safer alternative to the FG-Ad vector.

Generation of Brain Microvascular Endothelial-Like Cells from Human Induced Pluripotent Stem Cells by Co-Culture with C6 Glioma Cells

The blood brain barrier (BBB) is formed by brain microvascular endothelial cells (BMECs) and tightly regulates the transport of molecules from blood to neural tissues. In vitro BBB models from human pluripotent stem cell (PSCs)-derived BMECs would be useful not only for the research on the BBB development and function but also for drug-screening for neurological diseases. However, little is known about the differentiation of human PSCs to BMECs. In the present study, human induced PSCs (iPSCs) were differentiated into endothelial cells (ECs), and further maturated to BMECs. Interestingly, C6 rat glioma cell-conditioned medium (C6CM), in addition to C6 co-culture, induced the differentiation of human iPSC-derived ECs (iPS-ECs) to BMEC-like cells, increase in the trans-endothelial electrical resistance, decreased in the dextran transport and up-regulation of gene expression of tight junction molecules in human iPS-ECs. Moreover, Wnt inhibitors attenuated the effects of C6CM. In summary, we have established a simple protocol of the generation of BMEC-like cells from human iPSCs, and have demonstrated that differentiation of iPS-ECs to BMEC-like cells is induced by C6CM-derived signals, including canonical Wnt signals.