Novel vectors and approaches for gene therapy in liver diseases

Gene therapy is becoming an increasingly valuable tool to treat many genetic diseases with no or limited treatment options. This is the case for hundreds of monogenic metabolic disorders of hepatic origin, for which liver transplantation remains the only cure. Furthermore, the liver contains 10-15% of the body's total blood volume, making it ideal for use as a factory to secrete proteins into the circulation. In recent decades, an expanding toolbox has become available for liver-directed gene delivery. Although viral vectors have long been the preferred approach to target hepatocytes, an increasing number of non-viral vectors are emerging as highly efficient vehicles for the delivery of genetic material. Herein, we review advances in gene delivery vectors targeting the liver and more specifically hepatocytes, covering strategies based on gene addition and gene editing, as well as the exciting results obtained with the use of RNA as a therapeutic molecule. Moreover, we will briefly summarise some of the limitations of current liver-directed gene therapy approaches and potential ways of overcoming them.

Invaplex functions as an intranasal adjuvant for subunit and DNA vaccines co-delivered in the nasal cavity of nonhuman primates

Development of intranasal vaccines for HIV-1 and other mucosal pathogens has been hampered by the lack of adjuvants that can be given safely to humans. We have found that an intranasal Shigella vaccine (Invaplex) which is well tolerated in humans can also function as an adjuvant for intranasal protein and DNA vaccines in mice. To determine whether Invaplex could potentially adjuvant similar vaccines in humans, we simultaneously administered a simian immunodeficiency virus (SIV) envelope (Env) protein and DNA encoding simian-human immunodeficiency virus (SHIV) with or without Invaplex in the nasal cavity of female rhesus macaques. Animals were intranasally boosted with adenoviral vectors expressing SIV env or gag,pol to evaluate memory responses. Anti-SIV antibodies in sera and nasal, genital tract and rectal secretions were quantitated by ELISA. Intracellular cytokine staining was used to measure Th1-type T cells in blood. Macaques given DNA/protein immunizations with 0.5 mg Invaplex developed greater serum IgG, nasal IgA and cervicovaginal IgA responses to SIV Env and SHIV Gag,Pol proteins when compared to non-adjuvanted controls. Rectal IgA responses to Env were only briefly elevated and not observed to Gag,Pol. Invaplex increased frequencies of IFNγ-producing CD4 and CD8 T cells to the Env protein, but not T cell responses induced by the DNA. Ad-SIV boosting increased Env-specific polyfunctional T cells and Env- and Gag,Pol-specific antibodies in serum and all secretions. The data suggest that Invaplex could be highly effective as an adjuvant for intranasal protein vaccines in humans, especially those intended to prevent infections in the genital or respiratory tract.

A hepatitis B virus transgenic mouse model with a conditional, recombinant, episomal genome

Background & Aims

Development of new and more effective therapies against hepatitis B virus (HBV) is limited by the lack of suitable small animal models. The HBV transgenic mouse model containing an integrated overlength 1.3-mer construct has yielded crucial insights, but this model unfortunately lacks covalently closed circular DNA (cccDNA), the episomal HBV transcriptional template, and cannot be cured given that HBV is integrated in every cell.

Methods

To solve these 2 problems, we generated a novel transgenic mouse (HBV1.1X), which generates an excisable circular HBV genome using Cre/LoxP technology. This model possesses a HBV1.1-mer cassette knocked into the ROSA26 locus and is designed for stable expression of viral proteins from birth, like the current HBV transgenic mouse model, before genomic excision with the introduction of Cre recombinase.

Results

We demonstrated induction of recombinant cccDNA (rcccDNA) formation via viral or transgenic Cre expression in HBV1.1X mice, and the ability to regulate HBsAg and HBc expression with Cre in mice. Tamoxifen-inducible Cre could markedly downregulate baseline HBsAg levels from the integrated HBV genome. To demonstrate clearance of HBV from HBV1.1X mice, we administered adenovirus expressing Cre, which permanently and significantly reduced HBsAg and core antigen levels in the murine liver via rcccDNA excision and a subsequent immune response.

Conclusions

The HBV1.1X model is the first Cre-regulatable HBV transgenic mouse model and should be of value to mimic chronic HBV infection, with neonatal expression and tolerance of HBV antigens, and on-demand modulation of HBV expression.

Lay summary

Hepatitis B virus (HBV) can only naturally infect humans and chimpanzees. Mouse models have been developed with the HBV genome integrated into mouse chromosomes, but this prevents mice from being cured. We developed a new transgenic mouse model that allows for HBV to be excised from mouse chromosomes to form a recombinant circular DNA molecule resembling the natural circular HBV genome. HBV expression could be reduced in these mice, enabling curative therapies to be tested in this new mouse model.

PERK Inhibition Mitigates Restenosis and Thrombosis: A Potential Low-Thrombogenic Antirestenotic Paradigm

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Drug-eluting stents impede neointimal smooth muscle cell hyperplasia but exacerbate endothelial cell dysfunction and thrombogenicity. It has been a challenge to identify a common target to inhibit both. Findings in this study suggest PERK as such a target.

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A PERK inhibitor administered either via an endovascular (in biomimetic nanocarriers) or perivascular (in hydrogel) route effectively mitigated neointimal hyperplasia in rats.

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Oral gavage of the PERK inhibitor partially preserved the normal blood flow in a mouse model of induced thrombosis.

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Dampening PERK activity inhibited STAT3 while activating SRF in smooth muscle cells, and also reduced prothrombogenic tissue factor and growth impairment of endothelial cells.

Developing endothelial-protective, nonthrombogenic antirestenotic treatments has been a challenge. A major hurdle to this has been the identification of a common molecular target in both smooth muscle cells and endothelial cells, inhibition of which blocks dysfunction of both cell types. The authors’ findings suggest that the PERK kinase could be such a target. Importantly, PERK inhibition mitigated both restenosis and thrombosis in preclinical models, implicating a low-thrombogenic antirestenotic paradigm.

IRF-1 inhibits NF-κB activity, suppresses TRAF2 and cIAP1 and induces breast cancer cell specific growth inhibition

Interferon Regulatory Factor (IRF)-1, originally identified as a transcription factor of the human interferon (IFN)-β gene, mediates tumor suppression and may inhibit oncogenesis. We have shown that IRF-1 in human breast cancer cells results in the down-regulation of survivin, tumor cell death, and the inhibition of tumor growth in vivo in xenogeneic mouse models. In this current report, we initiate studies comparing the effect of IRF-1 in human nonmalignant breast cell and breast cancer cell lines. While IRF-1 in breast cancer cells results in growth inhibition and cell death, profound growth inhibition and cell death are not observed in nonmalignant human breast cells. We show that TNF-α or IFN-γ induces IRF-1 in breast cancer cells and results in enhanced cell death. Abrogation of IRF-1 diminishes TNF-α and IFN-γ-induced apoptosis. We test the hypothesis that IRF-1 augments TNF-α-induced apoptosis in breast cancer cells. Potential signaling networks elicited by IRF-1 are investigated by evaluating the NF-κB pathway. TNF-α and/or IFN-γ results in decreased presence of NF-κB p65 in the nucleus of breast cancer cells. While TNF-α and/or IFN-γ can induce IRF-1 in nonmalignant breast cells, a marked change in NF-κB p65 is not observed. Moreover, the ectopic expression of IRF-1 in breast cancer cells results in caspase-3, -7, -8 cleavage, inhibits NF-κB activity, and suppresses the expression of molecules involved in the NF-κB pathway. These data show that IRF-1 in human breast cancer cells elicits multiple signaling networks including intrinsic and extrinsic cell death and down-regulates molecules involved in the NF-κB pathway.

Differential regulation of autophagy and cell viability by ceramide species

The present studies sought to determine whether the anti-folate pemetrexed (Alimta) and the sphingosine-1-phosphate receptor modulator FTY720 (Fingolimod, Gilenya) interacted to kill tumor cells. FTY720 and pemetrexed interacted in a greater than additive fashion to kill breast, brain and colorectal cancer cells. Loss of p53 function weakly enhanced the toxicity of FTY720 whereas deletion of activated RAS strongly or expression of catalytically inactive AKT facilitated killing. Combined drug exposure reduced the activity of AKT, p70 S6K and mTOR and activated JNK and p38 MAPK. Expression of activated forms of AKT, p70 S6K and mTOR or inhibition of JNK and p38 MAPK suppressed the interaction between FTY720 and pemetrexed. Treatment of cells with FTY720 and pemetrexed increased the numbers of early autophagosomes but not autolysosomes, which correlated with increased LC3II processing and increased p62 levels, suggestive of stalled autophagic flux. Knock down of ATG5 or Beclin1 suppressed autophagosome formation and cell killing. Knock down of ceramide synthase 6 suppressed autophagosome production and cell killing whereas knock down of ceramide synthase 2 enhanced vesicle formation and facilitated death. Collectively our findings argue that pemetrexed and FTY720 could be a novel adjunct modality for breast cancer treatment.

Detection of viral acute lower respiratory tract infection in hospitalized infants using real-time PCR

Introduction

Acute lower respiratory tract infection in children causes significant morbidity in the developing countries. Documentation of virus infection using PCR and clinical characteristics of patients affected with viral pneumonia are reviewed in this study.

Methods

51 children less than three years admitted to the Pediatric Hospital, Cairo University with viral pneumonia were included. All patients had undergone nasopharyngeal aspirate for PCR viral detection.

Results

A total of 51 cases were enrolled in the study, of which 7 cases were negative while 44 children were positive for viruses. The most common respiratory virus was Rhinovirus in 32 patients (72.2%), then parainfluenza virus (PIV) in 12 (27.3%), of which subtypes PIV1 were 2 (4.5%), PIV3 were 5 (11.4%) and PIV4 were 5 (11.4%) cases. The third common viruses were respiratory syncytial virus (RSV) in 9 (20.5%) cases of which 3 (6.8%) were RSVA and 6 (13.6%) were RSVB and adenovirus in 9 cases (20.5%). Boca virus was found in 8 (18.2%) patients, corona virus 2 (4.5%) patients, H1N1 2 (4.5%) patients, enterovirus 2 patients (4.5%) and human metapneumovirus in one case (2.3%). Influenza B and PIV2 were not detected. Coinfection was found in 28 (63.7%). Mortality occurred in 12 (23.5%). There was no significant relation between virus type or coinfection with disease severity.

Conclusions

RV was the most commonly detected virus in children under 3 years admitted with acute lower respiratory tract infections. Coinfection was present in the majority of our patients; however it was not related significantly to parameters of disease severity.

Munc18c mediates exocytosis of pre-docked and newcomer insulin granules underlying biphasic glucose stimulated insulin secretion in human pancreatic beta-cells

Objective

Pancreatic beta-cells express three Munc18 isoforms. Much is known about the roles of Munc18a (pre-docked secretory granules-SGs) and Munc18b (newcomer SGs and SG–SG fusion) in insulin exocytosis. Although shown to influence glucose-stimulated insulin secretion (GSIS) in rodents the precise role of Munc18c in insulin SG exocytosis has not been elucidated. We here examined the role of Munc18c in human pancreatic beta-cells.

Methods

Munc18c-shRNA/RFP lenti-virus (versus control virus) was used to knock down the expression level of Munc18c in human islets or single beta-cells. Insulin secretion and granule exocytosis were measured by performing islets perifusion, single-cell patch clamp capacitance measurements and total internal reflection fluorescence microscopy (TIRFM).

Results

Munc18c is most abundant in the cytosol of human beta-cells. Endogenous function of Munc18c was assessed by knocking down (KD) its islet expression by 70% employing lenti-shRNA virus. Munc18c-KD caused reduction in cognate syntaxin-4 islet expression but not in other exocytotic proteins, resulting in the reduction in GSIS in first- (by 42%) and second phases (by 35%). Single cell analyses of RFP-tagged Munc18c-KD beta-cells by patch clamp capacitance measurements showed inhibition in both readily-releasable pool (by 52%) and mobilization from the reserve pool (by 57%). TIRFM to assess single SG behavior showed that Munc18c-KD inhibition of first phase GSIS was attributed to reduction in exocytosis of pre-docked and newcomer SGs, and second phase inhibition attributed entirely to reduction in newcomer SG fusion (SGs that undergo minimal residence or docking time at the plasma membrane before fusion).

Conclusion

Munc18c is involved in the distinct molecular machineries that affect exocytosis of both predocked and newcomer SG pools that underlie Munc18c's role in first and second phases of GSIS, respectively.

Adenovirus serotype 5 E1A expressing tumor cells elicit a tumor-specific CD8+ T cell response independent of NKG2D

The expression of the Adenovirus serotype 2 or serotype 5 (Ad2/5) E1A gene in tumor cells upregulates ligands that are recognized by the NKG2D activating receptor, which is expressed on NK cells and T cells, and reduces their tumorigenicity, a process dependent on NK cells and T cells. In some model systems, the forced overexpression of NKG2D ligands on tumor cells induced antigen-specific CD8+ T cells that mediated anti-tumor immunity. We wanted to determine if the interaction of NKG2D ligands on tumor cells that express E1A with NKG2D on immune cells contributed to the ability of E1A to induce a CD8+ T cell anti-tumor response or reduce tumorigenicity. To address these questions, we used the MCA-205 tumor cell line or MCA-205 cells that expressed Ad5 E1A (MCA-205-E1A cells), a fusion protein of E1A and ovalbumin (MCA-205-E1A-OVA) or OVA (MCA-205-OVA). We found that the expression of E1A or E1A–OVA, but not OVA, upregulated the expression of the NKG2D ligand RAE-1 on the surface of MCA-205 cells. Additionally, MCA-205-E1A cells and MCA-205-E1A-OVA cells were more sensitive to NK cell lysis than MCA-205 or MCA-205-OVA cells in WT B6 mice, but not NKG2D deficient B6 mice. Next, we adoptively transferred WT or NKG2D deficient OT-1 T cells (CD8 T cells that recognize OVA residues 257–264) into WT B6 mice or B6 mice that were deficient in NKG2D respectively and measured the expansion of OT-1 cells following immunization with MCA-205-E1A-OVA or MCA-205-OVA cells. We found that the expansion of OT-1 cells following immunization of either OVA-expressing MCA-205 cell lines was not affected by the presence or absence of NKG2D in B6 mice. Finally, we found that the capacity of E1A to reduce the tumorigenicity of MCA-205 cells was not impaired in B6-NKG2D deficient mice as compared to WT B6 mice. Our results suggest that the ability of E1A to reduce the tumorigenicity of MCA-205 cells, or induce an antigen-specific CD8+ T cell response, is independent of the interaction of NKG2D ligands with the NKG2D receptor.