Antisense- and RNA interference-based therapeutic strategies in allergy

Pulmonary delivery of ORMDL3 short hairpin RNA - a potential tool to regulate allergen-induced airway inflammation

Aim/Purpose: Exposure to various allergens has been shown to increase expression of ORMDL3 in the lung in models of allergic asthma. Studies using genetically modified (transgenic or knock out) mice have revealed some of the functions of ORMDL3 in asthma pathogenesis, although amid debate. The goal of this study was to use targeted post-transcriptional downregulation of ORMDL3 in allergen-challenged wild-type (WT) mice by RNA interference to further elucidate the functional role of ORMDL3 in asthma pathogenesis and evaluate a potential therapeutic option.Methods: Allergen (ovalbumin [OVA])-challenged WT mice were administered intranasally (i.n) with a single dose of five short hairpin RNA (shRNA) constructs with different target sequence for murine ORMDL3 cloned in a lentiviral vector or with the empty vector (control). Mice were evaluated for allergen-induced airway hyperresponsiveness (AHR) and various features of airway inflammation after 72 hours.Results: I.n administration of a single dose of ORMDL3 shRNAs to OVA-challenged mice resulted in reduction of ORMDL3 gene expression in the lungs associated with a significant reduction in AHR to inhaled methacholine and in the number of inflammatory cells recruited in the airways, specifically eosinophils, as well as in airway mucus secretion compared to OVA-challenged mice that received the empty vector. Administration of ORMDL3 shRNAs also significantly inhibited levels of IL-13, eotaxin-2 and sphingosine in the lungs. Additionally, ORMDL3 shRNAs significantly inhibited the allergen-mediated increase in monohexyl ceramides C22:0 and C24:0.Conclusions: Post-transcriptional down regulation of ORMDL3 in allergic lungs using i.n-delivered ORMDL3 shRNA (akin to inhaled therapy) attenuates development of key features of airway allergic disease, confirming the involvement of ORMDL3 in allergic asthma pathogenesis and serving as a model for a potential therapeutic strategy.

Mechanisms of Antisense Transcription Initiation with Implications in Gene Expression, Genomic Integrity and Disease Pathogenesis

Non-coding antisense transcripts arise from the strand opposite the sense strand. Over 70% of the human genome generates non-coding antisense transcripts while less than 2% of the genome codes for proteins. Antisense transcripts and/or the act of antisense transcription regulate gene expression and genome integrity by interfering with sense transcription and modulating histone modifications or DNA methylation. Hence, they have significant pathological and physiological relevance. Indeed, antisense transcripts were found to be associated with various diseases including cancer, diabetes, cardiac and neurodegenerative disorders, and, thus, have promising potentials for prognostic and diagnostic markers and therapeutic development. However, it is not clearly understood how antisense transcription is initiated and epigenetically regulated. Such knowledge would provide new insights into the regulation of antisense transcription, and hence disease pathogenesis with therapeutic development. The recent studies on antisense transcription initiation and its epigenetic regulation, which are limited, are discussed here. Furthermore, we concisely describe how antisense transcription/transcripts regulate gene expression and genome integrity with implications in disease pathogenesis and therapeutic development.

Alternative approaches for the treatment of airway diseases: focus on nanoparticle medicine

Despite the various treatment options and international guidelines currently available for the appropriate therapeutic management of asthma, a large population of patients with asthma continues to have poorly controlled disease. There is therefore a need for novel approaches to achieve better asthma control, especially for severe asthmatics. This review discusses the use of nanoparticles for the specific targeting of inflammatory pathways as a promising approach for the effective control of severe persistent asthma as well as other chronic inflammatory diseases.

Oligonucleotide Therapy for Obstructive and Restrictive Respiratory Diseases

Inhaled oligonucleotide is an emerging therapeutic modality for various common respiratory diseases, including obstructive airway diseases like asthma and chronic obstructive pulmonary disease (COPD) and restrictive airway diseases like idiopathic pulmonary fibrosis (IPF). The advantage of direct accessibility for oligonucleotide molecules to the lung target sites, bypassing systemic administration, makes this therapeutic approach promising with minimized potential systemic side effects. Asthma, COPD, and IPF are common chronic respiratory diseases, characterized by persistent airway inflammation and dysregulated tissue repair and remodeling, although each individual disease has its unique etiology. Corticosteroids have been widely prescribed for the treatment of asthma, COPD, and IPF. However, the effectiveness of corticosteroids as an anti-inflammatory drug is limited by steroid resistance in severe asthma, the majority of COPD cases, and pulmonary fibrosis. There is an urgent medical need to develop target-specific drugs for the treatment of these respiratory conditions. Oligonucleotide therapies, including antisense oligonucleotide (ASO), small interfering RNA (siRNA), and microRNA (miRNA) are now being evaluated both pre-clinically and clinically as potential therapeutics. The mechanisms of action of ASO and siRNA are highly target mRNA specific, ultimately leading to target protein knockdown. miRNA has both biomarker and therapeutic values, and its knockdown by a miRNA antagonist (antagomir) has a broader but potentially more non-specific biological outcome. This review will compile the current findings of oligonucleotide therapeutic targets, verified in various respiratory disease models and in clinical trials, and evaluate different chemical modification approaches to improve the stability and potency of oligonucleotides for the treatment of respiratory diseases.

Molecular-Docking-Based Anti-Allergic Drug Design

Allergens are foreign proteins that when come in contact of part(s) of human body stimulate the production of immunoglobulin types of proteins (antibodies). These allergens react with antibodies (immunoglobulin type E or IgE) produces allergic reactions, also known as immediate-type hypersensitivity reactions. As much as 20% of the general population may be affected by grass pollen as a major cause of allergic disease. EXPB class of proteins are known in the immunological literature as group-1 grass pollen allergens Molecular docking method can be used to identify the predicated the interaction of pollen allergen EXPB1 (Zea m 1), a beta-expansin and group-1 pollen allergen from maize with IgE molecules of human. The World Health Organization recognised allergen immunotherapy, as therapeutics for allergic diseases. RNA Interference (RNAi) is a biological process in which RNA molecules e.g. Small Interfering RNAs (siRNAs) inhibit gene expression, by cleavage and destruction of specific mRNA molecules. Use of Small Interfering RNA (siRNA) is a novel method in the induction of RNA Interference (RNAi), which is a potent method for therapeutics of allergic reactions. Due to various effects of STAT 6 proteins during hypersensitivity reactions caused by pollen allergens, mRNA of STAT6 gene is selected as target gene for allergy therapeutics via Post-Transcriptional Gene Silencing (PTGS). Using molecular docking study a specific sense siRNA is identified as anti allergic drug to treat allergic asthma during immediate type of hypersensitivity reaction, caused by Zea m 1 pollen allergen.

Small interfering RNAs targeted to interleukin-4 and respiratory syncytial virus reduce airway inflammation in a mouse model of virus-induced asthma exacerbation

Asthma exacerbations are caused primarily by viral infections. Antisense and small interfering RNA (siRNA) technologies have gained attention as potential antiasthma and antiviral approaches. In this study we analyzed whether gene silencing of interleukin (IL)-4 expression and respiratory syncytial virus (RSV) replication by RNA interference is able to suppress allergen- and virus-induced responses in a mouse model of virus-induced asthma exacerbation. Knockdown efficacy of IL-4 siRNA molecules was analyzed in the human HEK293T cell line by cotransfection of six different siRNAs with a plasmid carrying mouse IL-4. The most potent siRNA was then used in a mouse model of RSV-induced asthma exacerbation. BALB/c mice were sensitized intraperitoneally with ovalbumin (OVA) and then infected 12 days later intranasally with RSV Long strain (1×10(6) TCID50/mouse), followed 1 day later by intranasal challenge with OVA for 3 days. Mice were pretreated intranasally three times with either siRNA to IL-4 or GFP control, 2 days before, and on the first two OVA challenge days. siRNAs to RSV or rhinovirus control were inoculated intranasally once, 3 hr before RSV infection. Combined anti-IL-4 and anti-RSV siRNAs were able to significantly reduce total cell counts and eosinophilia in bronchoalveolar lavage fluid, development of airway hyperresponsiveness, and airway inflammation and to downregulate IL-4 mRNA expression and RSV viral RNA, but to upregulate IFN-γ levels in lung tissues. We conclude that anti-helper T cells type 2 and antiviral siRNAs may constitute a new therapeutic approach for treatment of virus induced asthma exacerbations.

Molecular biomarkers for grass pollen immunotherapy

Grass pollen allergy represents a significant cause of allergic morbidity worldwide. Component-resolved diagnosis biomarkers are increasingly used in allergy practice in order to evaluate the sensitization to grass pollen allergens, allowing the clinician to confirm genuine sensitization to the corresponding allergen plant sources and supporting an accurate prescription of allergy immunotherapy (AIT), an important approach in many regions of the world with great plant biodiversity and/or where pollen seasons may overlap. The search for candidate predictive biomarkers for grass pollen immunotherapy (tolerogenic dendritic cells and regulatory T cells biomarkers, serum blocking antibodies biomarkers, especially functional ones, immune activation and immune tolerance soluble biomarkers and apoptosis biomarkers) opens new opportunities for the early detection of clinical responders for AIT, for the follow-up of these patients and for the development of new allergy vaccines.

Small interfering RNA targeting T-cell Ig mucin-3 decreases allergic airway inflammation and hyperresponsiveness

Since CD4+ T cells play a pivotal role in the development of airway inflammation and hyperresponsiveness, targeting activated CD4+ T cell subsets and increasing the cells with regulatory function would be a logical therapeutic approach. We showed that this outcome can be achieved by local therapy with Tim-3, which is a negative regulator of CD4+ T cells. Tim-3 expression was up-regulated by ovalbumin (OVA) induction. Attenuating Tim-3 expression by RNA interference suppressed allergen-induced immune responses. Intranasal application of Tim-3 shRNA diminished airway inflammation and hyperresponsiveness. Multiple mechanisms were involved in the inhibitory effects, including regulation the imbalance of Th1/Th17 and increasing Treg cell expression. Our results indicate that the Tim-3 pathway is highly involved in the regulation of asthma. Targeting Tim-3 by siRNA may hold therapeutic potential in preventing the development of allergic asthma.

Mechanisms of antisense transcription initiation from the 3' end of the GAL10 coding sequence in vivo

In spite of the important regulatory functions of antisense transcripts in gene expression, it remains unknown how antisense transcription is initiated. Recent studies implicated RNA polymerase II in initiation of antisense transcription. However, how RNA polymerase II is targeted to initiate antisense transcription has not been elucidated. Here, we have analyzed the association of RNA polymerase II with the antisense initiation site at the 3' end of the GAL10 coding sequence in dextrose-containing growth medium that induces antisense transcription. We find that RNA polymerase II is targeted to the antisense initiation site at GAL10 by Reb1p activator as well as general transcription factors (e.g., TFIID, TFIIB, and Mediator) for antisense transcription initiation. Intriguingly, while GAL10 antisense transcription is dependent on TFIID, its sense transcription does not require TFIID. Further, the Gal4p activator that promotes GAL10 sense transcription is dispensable for antisense transcription. Moreover, the proteasome that facilitates GAL10 sense transcription does not control its antisense transcription. Taken together, our results reveal that GAL10 sense and antisense transcriptions are regulated differently and shed much light on the mechanisms of antisense transcription initiation.

RNAi Therapeutic Platforms for Lung Diseases

RNA interference (RNAi) is rapidly becoming an important method for analyzing gene functions in many eukaryotes and holds promise for the development of therapeutic gene silencing. The induction of RNAi relies on small silencing RNAs, which affect specific messenger RNA (mRNA) degradation. Two types of small RNA molecules, i.e. small interfering RNAs (siRNAs) and microRNAs (miRNAs), are central to RNAi. Drug discovery studies and novel treatments of siRNAs are currently targeting a wide range of diseases, including various viral infections and cancers. Lung diseases in general are attractive targets for siRNA therapeutics because of their lethality and prevalence. In addition, the lung is anatomically accessible to therapeutic agents via the intrapulmonary route. Recently, increasing evidence indicates that miRNAs play an important role in lung abnormalities, such as inflammation and oncogenesis. Therefore, miRNAs are being targeted for therapeutic purposes. In this review, we present strategies for RNAi delivery and discuss the current state-of-the-art RNAi-based therapeutics for various lung diseases.

Locally instilled tumor necrosis factor-α antisense oligonucleotide inhibits allergic inflammation via the induction of Tregs

BACKGROUND

Anti-tumor necrosis factor (TNF)-α therapeutics has the potential to alleviate allergic inflammation. However, in previous studies, the systemic administration of anti-TNF-α agents was frequently accompanied by many adverse effects, such as infection, immunogenicity and malignancy. Efforts are made in the present study to evaluate whether or not local administration of TNF-α antisense oligonucleotide would inhibit allergic airway inflammation and influence systemic immune responses in an ovalbumin-induced asthmatic murine model.

METHODS

The treatment effects of TNF-α antisense oligonucleotide on mice, as well as the alternative proportion of regulatory T cells and T(H) 2 cells, were examined and compared with untreated mice.

RESULTS

Local administration of TNF-α antisense oligonucleotide resulted in significantly inhibited TNF-α expression, remarkably decreased inflammatory cell infiltration and dramatically reduced mucus hypersecretion. These treatment effects were associated with induced CD4(+) CD25(+) Foxp3(+) regulatory T cells, reduced T(H) 2 cells and generally decreased T(H) 2-type cytokines expression in bronchoalveolar lavage fluid. Systemic immunosuppression was not triggered by local antisense oligonucleotide administration because the proportion of CD4(+) CD25(+) Foxp3(+) regulatory T cells in the blood, thymus or spleen was not affected. Attenuated 4-1BBL expression was likely involved in the alternative proportion of T cells.

CONCLUSIONS

These findings demonstrate that local administration of TNF-α antisense oligonucleotide contributes to anti-inflammatory action via the enhancement of regulatory T cells-mediated immune tolerance, which is not accompanied by systemic immunosuppression associated with systemically-induced regulatory T cells.

Intravitreal treatment with antisense oligonucleotides targeting tumor necrosis factor-α in murine herpes simplex virus type 1 retinitis

BACKGROUND

Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine known to participate in intraocular inflammatory disease. This study investigated whether treatment with intravitreal antisense-oligonucleotides (ASON) targeting TNF-α mRNA affects the progression of herpes simplex virus 1 (HSV-1) retinitis in mice.

METHODS

The in vivo uptake of the oligonucleotid after intravitreal injection was determined with FITC-labeled TNF-α ASON. HSV-retinitis was induced on day 0 by the injection of HSV-1 (KOS strain) into the anterior chamber (AC) of the right eyes of BALB/c mice (von Szily model). The left contralateral eyes were injected intravitreally on day 7 with TNF-α ASON, sequence-unspecific control ASON (CON), or buffer. The clinical course of retinitis, ocular inflammatory cell-infiltration, TNF-α expression in the eye by ELISA, delayed-type hypersensitivity (DTH) reaction, virus-neutralizing antibody titers in the serum, uptake of [3H]thymidine from regional lymph node (rln) cells, and viral content in the eyes were determined.

RESULTS

In vivo, strong fluorescence of FITC- TNF-α ASON was detected in the choroid and retina up to 3 days after intravitreal injection, but none in the rln. After treatment of eyes with ASON, decreased expression of TNF-α in the eye, and reduced incidence and severity of retinitis on day 10 after infection (P < 0.05) could be found. The other parameters were not significantly influenced after TNF-α ASON treatment.

CONCLUSIONS

TNF-α participates in the pathology of HSV-1 retinitis. Local inhibition of TNF-α mRNA by intraocular TNF-α ASON injection did not influence the systemic HSV-specific immune response or the antiviral response in the eye, but reduced ocular inflammatory bystander damage.

Oligonucleotides: a multi-targeted approach for the treatment of respiratory diseases

Reversing inflammatory lung disease remains the foremost challenge in treating respiratory diseases such as asthma and chronic obstructive pulmonary disease. Reducing (or modifying) the underlying inflammatory process with mono-target drugs has proven challenging. The era of designing ‘one target for one disease’ has evolved such that a growing body of evidence suggests a single drug that is capable of specifically targeting multiple targets and pathways would be better at arresting progression of these respiratory diseases and be an important advancement in current therapy. Oligonucleotide-based drugs represent an emerging class of drug candidates. Their properties, a broader range of targets over conventional small-molecule drugs and recent clinical proof-of-concept support their development as novel multi-targeting agents for the treatment of respiratory diseases.

Comparison of three techniques for generation of tolerogenic dendritic cells: siRNA, oligonucleotide antisense, and antibody blocking

In recent years, a new view of dendritic cells (DCs) as a main regulator of immunity to induce and maintain tolerance has been established. In vitro manipulation of their development and maturation is a topic of DC therapeutic application, which utilizes their inherent tolerogenicity. In this field, the therapeutic potential of antisense, siRNA, and blocking antibody are an interesting goal. In the present study, the efficiency of these three methods--siRNA, antisense, and blocking antibody--against CD40 molecule and its function in DCs and BCL1 cell line are compared. DCs were separated from mouse spleen and then cultured in vitro using Lipofectamine 2000 to deliver both silencers; the efficacy of transfection was estimated by flow cytometry. mRNA expression and protein synthesis were assessed by real time-PCR and flow cytometry, respectively. By Annexin V and propidium iodine staining, we could evaluate the viability of transfected cells. Knocking down the CD40 gene into separate groups of DCs by siRNA, antisense, and blocking antibody treated DCs can cause an increase in IL-4, decrease in IL-12, IFN-γ production, and allostimulation activity. Our results indicated that, in comparison to antisense and blocking antibody, siRNAs appear to be quantitatively more efficient in CD40 downregulation and their differences are significant.

Emerging oligonucleotide therapies for asthma and chronic obstructive pulmonary disease

Chronic respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) are disorders of the airways largely related to the presence of persistent inflammation. The approval of inhaled corticosteroids in the early 1970s pioneered a new age of therapy in treating chronic inflammatory airway diseases. This was the first time that an anti-inflammatory product was available to reduce the characteristic lung inflammation in airways and the associated obstruction, inflammation and hyper-responsiveness. Fast forward 40 years: corticosteroids are still an important therapeutic intervention; however, they exhibit limited use in moderate to severe asthma and COPD. Oligonucleotide therapies are an emerging class which include the antisense, the RNAi (siRNA and miRNA), the immunomodulatory, the aptamer and the decoy approaches. As these approaches are rather recent in the respiratory field, most are still early in development. Nevertheless, with limitations of current small molecule therapies and the hurdles faced with biologics, the use of oligonucleotides is relevant and the door is open to the development of this category of therapeutics. This review focuses on the major classes of oligonucleotides that are currently in late stage preclinical or clinical development for the treatment of asthma and COPD, and discusses the implications for their use as therapies for respiratory diseases.

Comparison of the anti-allergic activity of Syk inhibitors with optimized Syk siRNAs in FcepsilonRI-activated RBL-2H3 basophilic cells

Spleen tyrosine kinase (Syk) binds ITAM-bearing receptors in a wide variety of cell types. One such example is the activation of mast cells, basophils and eosinophils via the stimulation of the FcepsilonRI receptor by IgE/allergen complexes. The possible role of Syk in inflammatory signaling cascades has led to the development of pharmacological agents designed to block the Syk catalytic domain as potential novel therapeutics. Whilst the enzymatic activity of Syk lends towards the design of small-molecule inhibitors, other attention has focused on the possibility of targeting Syk expression using anti-sense oligonucleotides as an alternate means of anti-inflammatory therapy. In this study, we compared the ability of multiple optimized Syk siRNA sequences and small-molecule Syk inhibitors to block FcepsilonRI-mediated signal transduction, degranulation and TNFalpha secretion in the basophilic cell line RBL-2H3. We also characterized the specificity of each siRNA sequence with regards to off-target induction of the interferon-inducible gene IFIT1. We identified a single siRNA sequence, which displayed a favorable profile of efficient Syk knockdown, blockage of FcepsilonRI-mediated signal transduction, degranulation and TNFalpha secretion and a lack of IFIT1 induction. The effect of this siRNA was comparable to that of the Syk kinase domain inhibitors BAY61-3606 and R406. The identification of an active and specific Syk siRNA could be a basis for the development of therapeutic Syk siRNAs against inflammatory diseases.

A short hairpin DNA analogous to miR-125b inhibits C-Raf expression, proliferation, and survival of breast cancer cells

The noncoding RNA miR-125b has been described to reduce ErbB2 protein expression as well as proliferation and migration of cancer cell lines. As additional target of miR-125b, we identified the c-raf-1 mRNA by sequence analysis. We designed a short hairpin-looped oligodeoxynucleotide (ODN) targeted to the same 3' untranslated region of c-raf-1 mRNA as miR-125b. The fully complementary ODN antisense strand is linked to a second strand constituting a partially double-stranded structure of the ODN. Transfection of the c-raf-1-specific ODN (ODN-Raf) in a breast cancer cell line reduced the protein levels of C-Raf, ErbB2, and their downstream effector cyclin D1 similar to miR-125b. MiR-125b as well as ODN-Raf showed no effect on the c-raf-1 mRNA level in contrast to small interfering RNA. Unlike miR-125b, ODN-Raf induced a cytopathic effect. This may be explained by the structural properties of ODN-Raf, which can form G-tetrads. Thus, the short hairpin-looped ODN-Raf, targeting the same region of c-raf-1 as miR-125b, is a multifunctional molecule reducing the expression of oncoproteins and stimulating cell death. Both features may be useful to interfere with tumor growth.

Specific post-transcriptional inhibition of mRNA for ligand binding chain of IgE high affinity receptor

IgE high affinity receptor (FcεRI) plays an important role in triggering type I allergic reactions. In this study, we have investigated the ability of four synthetic and sequence-specific RNA interfering antisense oligodeoxynucleotides (AS-ODNs) to reduce the expression of FcεRIα gene in granulocytes of allergy sufferers in vitro. Only AS1 out of four AS-ODNs specifically inhibited the FcεRIα gene expression and the dose response assay revealed that AS1 was capable of specific inhibition of target mRNA expression over a linear concentration range without affecting the expression of house keeping genes such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Together, these results indicate that sequence-specific RNA interfering ODNs can be effectively used to silence the expression of key genes like IgE high affinity receptor that are involved in chronic inflammatory diseases.

Matrix metalloproteinase 12 silencing: a therapeutic approach to treat pathological lung tissue remodeling?

Among the large matrix metalloproteinases (MMPs) family, MMP-12, also referred to as macrophage elastase, plays a significant role in chronic pulmonary pathologies characterized by an intense tissue remodeling such as asthma and COPD. This review will summarize knowledge about MMP-12 structure, functions and mechanisms of activation and regulation, including potential MMP-12 modulation by microRNA. As MMP-12 is involved in many tissue remodeling diseases, efforts have been made to develop specific synthetic inhibitors. However, at this time, very few chemical inhibitors have proved to be efficient and specific to a particular MMP. The relevance of silencing MMP-12 by RNA interference is highlighted. The specificity of this approach using siRNA or shRNA and the strategies to deliver these molecules in the lung are discussed.

Short hairpin RNAs against eotaxin or interleukin-5 decrease airway eosinophilia and hyper-responsiveness in a murine model of asthma

BACKGROUND

Eosinophilia plays the major role in the pathogenesis of asthma and correlates with the up-regulation of eotaxin, which, together with interleukin (IL)-5, is important for differentiation, chemo-attraction, degranulation, and survival of eosinophils in local tissue. In a previous study, we found that administration of lentivirus-delivered short hairpin RNA (shRNA) to suppress the expression of IL-5 inhibited airway inflammation. The present study aimed to investigate the role of eotaxin shRNA and the synergistic effect of eotaxin and IL-5 shRNAs on airway inflammation in an ovalbumin (OVA)-induced murine model of asthma.

METHODS

Lentivirus-delivered shRNAs were used to suppress the expression of eotaxin and/or IL-5 in local tissue in an OVA-induced murine asthma model.

RESULTS

Intra-tracheal administration of lentivirus containing eotaxin shRNA expressing cassette (eoSEC3.3) efficiently moderated the characteristics of asthma, including airway hyper-responsiveness, cellular infiltration of lung tissues, and eotaxin and IL-5 levels in bronchio-alveolar lavage fluid. Administration of lentiviruses expressing IL-5 or eotaxin shRNAs (IL5SEC4 + eoSEC3.3) also moderated the symptoms of asthma in a mouse model.

CONCLUSIONS

Local delivery of lentiviruses expressing IL-5 and eotaxin shRNAs provides a potential tool in moderating airway inflammation and also has the potential for developing clinical therapy based on the application of shRNAs of chemokines and cytokines involved in T helper 2 cell inflammation and eosinophilia.

Novel targets of therapy in asthma

PURPOSE OF REVIEW

The use of inhaled corticosteroids, short and long acting beta2-adrenoceptor agonists and inhibitors of leukotrienes provide most asthmatic patients with good disease control. However, none of these therapies are specifically directed to the underlying causal pathways of asthma. In this review the role of selective inhibitors of the inflammatory cascade are presented with a particular emphasis on biologics.

RECENT FINDINGS

Apart from antihuman immunoglobulin E, biologics have had little impact on this disease. However, with the definition of critical pathways in driving ongoing inflammation and airway remodelling, the situation is about to change with several exciting new approaches being on the horizon. Specific cytokines that are considered central to the Th2 inflammatory response as therapeutic targets are discussed along with some entirely new approaches such as restoration of mucosal innate immunity and epithelial barrier function and the application of radiofrequency ablation of airway smooth muscle or thermal bronchoplasty.

SUMMARY

What is becoming clear in filling the pipeline with new asthma therapies that treat the underlying disease causes is the need for closer working between clinical academics and industry to ensure that there is a rapid and sustained transfer of knowledge on novel targets through to their validation, proof of concept studies and clinical trials.

RNA interference against interleukin-5 attenuates airway inflammation and hyperresponsiveness in an asthma model

Interleukin-5 (IL-5) accompanies the development of airway inflammation and hyperresponsiveness through the activation of eosinophils. Therefore, interference of IL-5 expression in lung tissue seems to be an accepted approach in asthma therapy. In this study, we designed a small interfering RNA (siRNA) to inhibit the expression of IL-5. The siRNAs against IL-5 were constructed in a lentivirus expressing system, and 1.5x10(6) IFU (inclusion-forming unit) lentiviruses were administered intratracheally to ovalbumin (OVA)-sensitized murine asthmatic models. Our results show that lentivirus-delivered siRNA against IL-5 efficiently inhibited the IL-5 messenger ribonucleic acid (mRNA) expression and significantly attenuated the inflammation in lung tissue. Significant decrease of eosinophils and inflammatory cells were found in peripheral blood, bronchoalveolar lavage fluid (BALF), and lung tissue. In addition, significant inhibition of airway hyperresponsiveness (AHR) was found in the mice treated with siRNA against IL-5. These observations demonstrate that siRNA delivered by means of the lentivirus system is possibly an efficacious therapeutic approach for asthma.

Post-transcriptional silencing of CCR3 downregulates IL-4 stimulated release of eotaxin-3 (CCL26) and other CCR3 ligands in alveolar type II cells

Trafficking and inflammation in airway diseases are, in part, modulated by members of the CC chemokine family, eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26), which transduce signals through their CCR3 receptor. In this context, we hypothesized that transfecting alveolar type II epithelial cells with CCR3-targeted siRNA or antisense (AS-ODN) sequences will downregulate cellular synthesis and release of the primary CCR3 ligands CCL26 and CCL24 and will modulate other CCR3 ligands. The human A549 alveolar type II epithelium-like cell culture model was used for transfection and subsequent effects on CCR3 agonists. siRNAs were particularly effective. PCR showed a 60-80% decrease in mRNA and immunoblots showed up to 75-84% reduction of CCR3 in siRNA treated cells. CCR3-siRNA treatments reduced IL-4 stimulated CCL26 release and constitutive CCL24 release by 65% and 80%, respectively. Release of four additional CCR3 agonists RANTES, MCP-2, MCP-3 and MCP-4 was also significantly reduced by CCR3-siRNA treatments of the alveolar type II cells. Activation of eosinophils, assessed as superoxide anion generation, was reduced when eosinophils were treated with supernatants of A549 cells pretreated with CCR3-targeted siRNAs or AS-ODNs. Collectively, the data suggest that post-transcriptional regulation of CCR3 receptors may be a potential therapeutic approach for interrupting proinflammatory signaling.

Subconjunctival antisense oligonucleotides targeting TNF-alpha influence immunopathology and viral replication in murine HSV-1 retinitis

BACKGROUND

To investigate the role of tumor necrosis factor-alpha (TNF-alpha) in immunopathology and viral replication in the contralateral eye in the von Szily model of herpes simplex virus (HSV)-1 acute retinitis.

METHODS

In vivo distribution was analyzed after subconjunctival injection of FITC-labeled antisense oligonucleotides (ASON). After HSV-1 (KOS) was injected in the right anterior chamber (AC) in BALB/c mice, the course of the contralateral retinitis was evaluated. The left eyes were treated with either TNF-alpha ASON, sequence-unspecific control (CON), or buffer. The ocular TNF-alpha content was quantified by ELISA. The delayed-type hypersensitivity (DTH) reaction, uptake of [3H]thymidine from regional lymph nodes (rln)- and spleen cells, serum-neutralizing antibodies, and viral titer in the eyes were evaluated.

RESULTS

After subconjunctival injection, FITC-labeled ASON were found in the choroid and retina. In the TNF-alpha ASON-treated eyes, TNF-alpha expression and the incidence and severity of retinitis were reduced on day 8 postinfection (PI) (p < 0.05). On day 10 PI, higher viral titers were only seen in the eyes of the TNF-alpha ASON group (p < 0.05), and retinitis was slightly more severe on day 12 PI. While the HSV-1 specific [3H]thymidine uptake from rln cells was higher in the TNF-alpha ASON mice (p < 0.05), the [3H]thymidine uptake from spleen cells, the DTH response, and the neutralizing-antibody titers did not differ between the groups.

CONCLUSIONS

After regional blockade of TNF-alpha in experimental HSV-1 retinitis TNF-alpha seems to possess an antiviral capacity against HSV-1 in the contralateral eye and participates in the immunopathology of HSV-1-induced acute retinitis.

Treatment strategies for allergy and asthma

Allergic diseases have reached epidemic proportions worldwide. An understanding of the cellular and soluble mediators that are involved in allergic inflammatory responses not only helps in understanding the mechanisms of current treatments, but is also important for the identification of new targets that are amenable to both small-molecule and biological interventions. There is now considerable optimism with regards to tackling the allergy epidemic in light of improvements in systemic and mucosal allergen-specific immunotherapy, the identification of key cytokines and their receptors that drive T-helper-2-cell polarization, a clearer understanding of the pathways of leukocyte recruitment and the signalling pathways that are involved in cell activation and mediator secretion, and new approaches to vaccine development.

Small interfering RNA against interleukin-5 decreases airway eosinophilia and hyper-responsiveness

Interleukin-5 (IL-5) has been suggested to be involved in the development of airway hyper-responsiveness (AHR). Both clinical and experimental investigations have shown strong correlation between the presence of eosinophils and AHR. In this study, we used small interfering RNA (siRNA) as an approach to inhibiting the expression of IL-5 and reducing AHR. siRNAs targeting IL-5 were characterized in vitro, and siRNA-expressing lentiviruses were administered intratracheally to OVA-sensitized BALB/c mice. AHR, cytokine levels, serum levels of OVA-specific antibodies and infiltration of inflammatory cells were analyzed to investigate the effects of siRNA in an OVA-induced murine model of asthma. Lentivirus-delivered siRNA targeting IL-5 efficiently moderated the characteristics of asthma, including AHR, cellular infiltration of lung tissues, eotaxin levels in the bronchoalveolar lavage fluid and IL-5 mRNA levels in lungs in the mouse model of asthma. However, there was no effect on OVA-specific IgE level. These data demonstrate that siRNA delivered by the lentiviral system is an efficacious therapeutic strategy for asthma.

siRNA specific to Pdx-1 disturbed the formation of the islet in early zebrafish embryos

Pdx-1, an important transcription factor highlighting in the early pancreatic development, islet functions and pancreatic disorders, needs to be more investigated in zebrafish, and siRNA is still seldom applied in zebrafish embryo-related research. Our aim was to explore the role of pdx-1 in pancreatic development of zebrafish embryos by using siRNA approach. Microinjection, reverse transcriptase-PCR (RT-PCR), in situ hybridization and immunofluorescent staining were used in this research, and the morphology of the islet in normal zebrafish embryos, and in those treated with the siRNA specific to pdx-1 (siPDX-1) or siGFP was observed and compared. The expression of pdx-1 was detected in the stages of 1-cell, 2-cell, 4-cell, 8-cell, 16-cell, 16-hour by RT-PCT. The in situ hybridization and immunofluorescent staining results showed that siPDX-1 disturbed the formation of the islet in zebrafish embryos. Pdx-1 played multiple roles in maintaining the phenotype of the islet during embryogenesis in zebrafish.

Primary prevention of allergic diseases: current concepts and mechanisms

: Atopic diseases, the new "epidemic of the twenty-first century" and a central health problem of industrial nations, call for the development of innovative primary prevention strategies. The present review provides an overview of current experimental and immunomodulatory procedures and their underlying mechanisms.

Gene silencing in the therapy of influenza and other respiratory diseases: Targeting to RNase P by use of External Guide Sequences (EGS)

Respiratory diseases provide an attractive target for gene silencing using small nucleic acids since the respiratory epithelium can be reached by inhalation therapy. Natural surfactant appears to facilitate the uptake and distribution of these types of molecules making aerosolized nucleic acids a possible new class of therapeutics. This article will review the rationale for the use of External Guide Sequence (EGS) in targeting specific mRNA molecules for RNase P-mediated intracellular destruction. Specific destruction of target mRNA results in gene-specific silencing similar to that instigated by siRNA via the RISC complex. The application of EGS molecules specific for influenza genes are discussed as well as the potential for synergy with siRNA. Furthermore, EGS could be adapted to target other respiratory diseases of viral etiology as well as conditions such as asthma.

Interactions between genes and the environment. Epigenetics in allergy

Epigenetics is defined as those inheritable changes occurring in gene expression, without actual modification in the genic DNA sequence. Epigenetic factors are chemically stable, potentially reversible, and can be modulated or induced by environmental factors. In the case of allergic disease, epigenetics could explain not only the discordances observed between monozygous twins but also phenomena such as incomplete penetrance, variable expression, gender and progenitor effects, and sporadic cases. In this sense, the hypothesis of hygiene is of great relevance in that it integrates genetic and epidemiological data in the context of environmental exposures. Among the different epigenetic factors, mention must be made of DNA methylation, covalent histone modifications, and other mechanisms that include different protein complexes and RNA-mediated modifications. The regulatory effect of these phenomena upon immune response has important implications for allergic diseases. At present, different lines of pharmacological research are being conducted, based on the modulation of epigenetic factors, modifying expression of the genes that encode for proteins implicated in allergic processes. Among such modulators, mention can be made of antisense oligonucleotides, ribozymes and interference RNA. The applications of epigenetics to the diagnosis and treatment of allergic disorders offer a very promising future of this specialty.

A review of antisense therapeutic interventions for molecular biological targets in asthma

Modern tools of genomics and proteomics reveal potential therapeutic antisense targets in asthma, increasing the interest in the development of anti-mRNA drugs. In allergic asthma experimental models, antisense oligonucleotides (ASO) are administered by inhalation or systemically. ASO can be used for a large number of molecular targets: cell membrane receptors (G-protein coupled receptors, cytokine and chemokine receptors), membrane proteins, ion channels, cytokines and related factors, signaling non-receptor protein kinases (tyrosine kinases, and serine/threonine kinases) and regulators of transcription belonging to Cys4 zinc finger of nuclear receptor type or beta-scaffold factors with minor groove contacts classes/superclasses of transcription factors. A respirable ASO against the adenosine A(1) receptor was investigated in human trials. RNase P-associated external guide sequence (EGS) delivered into pulmonary tissues represents a potentially new therapeutic approach in asthma as well as ribozyme strategies. Small interfering RNA (siRNA) targeting key molecules involved in the patho-physiology of allergic asthma are expected to be of benefit as RNAi immunotherapy. Antagomirs, synthetic analogs of microRNA (miRNA), have important roles in regulation of gene expression in asthma. RNA interference (RNAi) technologies offer higher efficiency in suppressing the expression of specific genes, compared with traditional antisense approaches.

Syk inhibitors as treatment for allergic rhinitis

Allergic rhinitis is characterized by a hypersensitive immune response in the upper airways to seasonal or perennial allergens leading to episodes of sneezing, itching, runny nose and nasal congestion. These symptoms are mainly the manifestations of a large number of mediators released by mast cells and basophils localized in the nasal mucosa, following their activation via allergen-specific immunoglobulin E (IgE) receptors. Current medications antagonize the action of distinct mediators such as histamine and leukotrienes for symptom relief, or block the production of pro-inflammatory cytokines to suppress allergic inflammation. Notably, rather than neutralizing individual mediators, Syk kinase inhibitors can block the allergen-induced release of all mast cell mediators and the production of most eicosanoids and cytokines. Thus, Syk kinase represents an attractive therapeutic target for acute and chronic allergic inflammation. Syk kinase inhibitors are now entering clinical trials. Using cell-based structure-activity relationships with primary human mast cells, a series of 2,4-diaminopyrimidine Syk kinase inhibitors was developed. One of these compounds, referred to as R112, exhibited suitable characteristics for intranasal delivery and was tested for safety and efficacy in allergic rhinitis patients. In a park environment, R112 showed remarkable amelioration of acute allergic rhinitis symptoms with rapid onset of action. These results demonstrate the clinical significance of inhibiting Syk in allergic upper airway disorders.

Endothelin-1 antisense oligonucleotide suppresses the proliferation of glomerular mesangial cells stimulated with angiotensin-II

Antisense oligonucleotide (AON) has been applied to modern molecular pharmacology. We have previously demonstrated that angiotensin-II (Ang-II) is an active stimulator of endothelin-1 (ET-1) production in glomerular mesangial cells. This study was designed to investigate the specific effect of ET-1 AON on inducing proliferation of cultured rat mesangial cells stimulated with Ang-II. ET-1 was measured by radioimmunoassays. The results were: (1) Ang-II enhanced ET-1 production of mesangial cells; (2) ET-1 production of mesangial cells was significantly suppressed by ET-1 AON, and this production was not affected by either ET-1 sense or scramble oligonucleotide in different concentrations; (3) Ang-II increased [3H]-thymidine uptake of mesangial cells, which was suppressed to 25% by ET-1 AON but not by ET-1 sense or scramble oligonucleotide. Our results indicate that ET-1 AON effectively suppresses the ET-1 production and the Ang-II-stimulated proliferation of mesangial cells, and therefore may offer treatment for proliferative glomerulonephritis.

Control of cytokine gene expression using small RNA interference: blockade of interleukin-10 and interferon-gamma gene expression in pig cells

The ability of small RNA interference (RNAi) to reduce specific gene expression was tested using interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) production by cultured swine blood mononuclear cells stimulated by Escherichia coli lipopolysaccharide or concanavalin A. Antisense (AS) phosphorothioate oligodeoxynucleotides (ODNs) corresponding to a sequence in the region of the AUG initiation codon of swine IL-10 or IFN-gamma mRNA inhibited production of IL-10 (>or=93.5%) and IFN-gamma (>or=99%) mRNAs. Interleukin-10 and IFN-gamma protein production was inhibited more than 95% by the AS ODNs. Scrambled and sense ODNs RNAi used as negative controls did not alter mRNA expression for either cytokine but slightly reduced IL-10 protein production. Cytokine-specific and control RNAi did not inhibit beta(2)-microglobulin mRNA expression in mitogen-stimulated blood mononuclear cells. Thus AS ODNs RNAi specifically inhibit expression of pig IL-10 and IFN-gamma mRNAs by cultured, mitogen-stimulated blood mononuclear cells and may be an attractive alternative method for studying cytokine function.