The CMV enhancer stimulates expression of foreign genes from the human EF-1 alpha promoter

Endogenous and exogenous thioredoxin 1 prevents goblet cell hyperplasia in a chronic antigen exposure asthma model

BACKGROUND

Goblet cell hyperplasia with mucus hypersecretion contribute to increased morbidity and mortality in bronchial asthma. We have reported that thioredoxin 1 (TRX1), a redox (reduction/oxidation)-active protein acting as a strong antioxidant, inhibits pulmonary eosinophilic inflammation and production of chemokines and Th2 cytokines in the lungs, thus decreasing airway hyperresponsiveness (AHR) and airway remodeling in mouse asthma models. In the present study, we investigated whether endogenous or exogenous TRX1 inhibits goblet cell hyperplasia in a mouse asthma model involving chronic exposure to antigen.

METHODS

We used wild-type Balb/c mice and Balb/c background human TRX1-transgenic mice constitutively overproducing human TRX1 protein in the lungs. Mice were sensitized 7 times (days 0 to 12) and then challenged 9 times with ovalbumin (OVA) (days 19 to 45). Every second day from days 18 to 44 (14 times) or days 35 to 45 (6 times), Balb/c mice were treated with 40 microg recombinant human TRX1 (rhTRX1) protein. Goblet cells in the lungs were examined quantitatively on day 34 or 45.

RESULTS

Goblet cell hyperplasia was significantly prevented in TRX1-transgenic mice in comparison with TRX1 transgene-negative mice. rhTRX1 administration during OVA challenge (days 18 to 44) significantly inhibited goblet cell hyperplasia in OVA-sensitized and -challenged wild-type mice. Moreover, rhTRX1 administration after the establishment of goblet cell hyperplasia (days 35 to 45) also significantly ameliorated goblet cell hyperplasia in OVA-sensitized and -challenged wild-type mice.

CONCLUSIONS

Our results suggest that TRX1 prevents the development of goblet cell hyperplasia, and also ameliorates established goblet cell hyperplasia.

Transcriptional targeting to brain cells: Engineering cell type-specific promoter containing cassettes for enhanced transgene expression

Transcriptional targeting using a mammalian cellular promoter to restrict transgene expression to target cells is often desirable for gene therapy. This strategy is, however, hindered by relatively weak activity of some cellular promoters, which may lead to low levels of gene expression, thus declining therapeutic efficacy. Here we outline the advances accomplished in the area of transcriptional targeting to brain cells, with a particular focus on engineering gene cassettes to augment cell type-specific expression. Among the effective approaches that improve gene expression while retaining promoter specificity are promoter engineering to change authentic sequences of a cellular promoter and the combined use of a native cellular promoter and other cis-acting elements. Success in achieving high level and sustained transgene expression only in the cell types of interest would be of importance in allowing gene therapy to have its impact on patient treatment.

Thioredoxin prevents the development and progression of elastase-induced emphysema

Thioredoxin 1 (TRX1) is a redox (reduction/oxidation)-active protein that scavenges reactive oxygen species. Here we examined whether endogenous or exogenous administration of TRX1 prevented the development and progression of elastase-induced pulmonary emphysema. Mice were treated with intratracheal elastase via microspray on day 0, and were given recombinant human TRX1 (rhTRX1) every other day from days -1 to 21. To determine the effects of TRX1 on the progression of established emphysema, mice were treated intratracheally with elastase on day 0, and rhTRX1 was administered from days 14 to 21. Histopathologic examination was performed on day 21. TRX1-transgenic but not transgene-negative mice demonstrated a decrease in the physiological indicators of elastase-induced emphysema. TRX1 administration from days -1 to 19 significantly decreased the signs of elastase-induced emphysema. Moreover, TRX1 administration beginning 14 days after elastase treatment significantly slowed the progression of emphysema. TRX1 may be of clinical benefit for the treatment of COPD.

Astrocytic expression of transgene in the rat brain mediated by baculovirus vectors containing an astrocyte-specific promoter

Therapeutic gene expression in glial cells has been tested for the treatment of neurological diseases in animal models. Many of such studies used the promoter of the glial fibrillary acidic protein (GFAP) to restrict gene expression to astrocytes. We have investigated in the current study whether it is possible to improve the transcriptional activity of the cellular promoter, while maintaining its cell-type specificity. We constructed an expression cassette containing a hybrid cytomegalovirus (CMV) enhancer/GFAP promoter and placed it into baculovirus vectors, a type of viral vectors capable of transducing astrocytes. In another vector design, we used inverted terminal repeats (ITRs) from adeno-associated virus (AAV) to flank the expression cassette. The recombinant baculoviruses with the hybrid promoter improved gene expression levels over two orders of magnitude in glial cell lines and by 10-fold in the rat brain when compared to the baculoviruses with the GFAP promoter alone. The expression was further improved by ITR flanking, reaching levels higher than that mediated by the baculovirus vectors with the CMV immediate-early enhancer/promoter (CMV promoter). Using these recombinant baculoviruses, we observed extended in vivo transgene expression in the rat brain at 90 days postinjection, by which time the gene expression from baculovirus vectors with the GFAP or CMV promoter had already become undetectable. The astrocyte specificity of the GFAP promoter was preserved in the engineered expression cassette with the CMV enhancer and the AAV ITRs, as demonstrated by immunohistological analysis of brain samples and an axonal retrograde transport assay. Taken together, our findings suggest that these baculovirus vectors may serve as useful tools for astrocyte-specific gene expression in the brain.

Improved neuronal transgene expression from an AAV-2 vector with a hybrid CMV enhancer/PDGF-beta promoter

BACKGROUND

Adeno-associated virus type 2 (AAV-2) vectors are highly promising tools for gene therapy of neurological disorders. After accommodating a cellular promoter, AAV-2 vectors are able to drive sustained expression of transgene in the brain. This study aimed to develop AAV-2 vectors that also facilitate a high level of neuronal expression by enhancing the strength of a neuron-specific promoter, the human platelet-derived growth factor beta-chain (PDGF) promoter.

METHODS AND RESULTS

A hybrid promoter approach was adopted to fuse the enhancer of human cytomegalovirus immediately early (CMV) promoter to the PDGF promoter. In cultured cortex neurons, AAV-2 vectors containing the hybrid promoter augmented transgene expression up to 20-fold over that mediated by titer-matched AAV-2 vectors with the PDGF promoter alone and 4-fold over the CMV enhancer/promoter. Injection of AAV-2 vectors with the hybrid promoter into the rat striatum resulted in neuron-specific transgene expression, the level of which was about 10-fold higher than those provided by the two control AAV-2 expression cassettes at 4 weeks post-injection and maintained for at least 12 weeks. Gene expression in the substantia nigra through possible retrograde transport of the AAV-2 vectors injected into the striatum was not obvious. After direct injection of AAV-2 vectors into the substantia nigra, transgene expression driven by the hybrid promoter was observed specifically in dopaminergic neurons and its level was about 3 and 17 times higher than that provided by the PDGF promoter alone and the CMV enhancer/promoter, respectively.

CONCLUSIONS

Enhanced transgene capacity plus neuron-specificity of the AAV-2 vectors developed in this study might prove valuable for gene therapy of Parkinson's disease.

Neuronal gene transfer by baculovirus-derived vectors accommodating a neurone-specific promoter

Recombinant baculoviruses have been employed as gene delivery vectors for mammalian cells, including neurones, during recent years. The aim of the current study was to develop a new recombinant baculovirus vector capable of enhancing gene expression in neurones. A hybrid promoter constructed by fusing the enhancer of human cytomegalovirus (CMV) immediately early promoter to the human platelet-derived growth factor (PDGF) beta-chain promoter was placed into a baculovirus expression cassette. In cultured neurones, baculovirus vectors containing the hybrid promoter augmented transgene expression up to 100-fold greater than that mediated by titre-matched baculovirus vectors with the PDGF promoter alone. Double immunostaining of tissue sections collected from the striatum and the retina injected with the new baculovirus vector demonstrated its specificity in driving gene expression almost exclusively in neurones, confirming the feasibility of using a tissue-specific promoter in the context of baculovirus vectors to provide cell type-specific transgene expression. The attributes of the new baculovirus vector might have practical implications for gene therapy in the nervous system.

Intradermal Delivery of IL-12 Naked DNA Induces Systemic NK Cell Activation and Th1 Response In Vivo That Is Independent of Endogenous IL-12 Production

In this study four murine IL-12 naked DNA expression plasmids (pIL-12), containing both the p35 and p40 subunits, were shown to induce systemic biological effects in vivo after intradermal injection. Three of the four IL-12 expression vectors augmented NK activity and induced expression of the IFN-γ and IFN-γ-inducible Mig genes. Both IL-12 p70 heterodimer and IFN-γ proteins were documented in the serum within 24 h after intradermal injection of the pIL-12o− plasmid, which also induced the highest level of NK activity in the spleen and liver among the IL-12 constructs. Interestingly, both p40 mRNA expression at the injection site and serum protein levels followed a biphasic pattern of expression, with peaks on days 1 and 5. Subsequent studies revealed that the ability of intradermally injected pIL-12o− to augment NK lytic activity was prevented by administration of a neutralizing anti-IL-12 mAb. Finally, injection of the pIL-12o− into BALB/c IL-12 p40−/− mice also resulted in a biphasic pattern of IL-12 p70 appearance in the serum, and induced IFN-γ protein and activated NK lytic activity in liver and spleen. These results demonstrate that injection of delivered naked DNA encoding the IL-12 gene mediates the biphasic systemic production of IL-12-inducible genes and augments the cytotoxic function of NK cells in lymphoid and parenchymal organs as a direct result of transgene expression. The results also suggest that these naked DNA plasmids may be useful adjuvants for vaccines against infectious and neoplastic diseases.