GATA-3-specific DNAzyme - A novel approach for stratified asthma therapy

Copaiba oil minimizes inflammation and promotes parenchyma re-epithelization in acute allergic asthma model induced by ovalbumin in BALB/c mice

Introduction: Asthma is a condition of airflow limitation, common throughout the world, with high mortality rates, especially as it still faces some obstacles in its management. As it constitutes a public health challenge, this study aimed to investigate the effect of copaiba oil (e.g., Copaifera langsdorffii), as a treatment resource, at doses of 50 and 100 mg/kg on certain mediators of acute lung inflammation (IL-33, GATA3, FOXP3, STAT3, and TBET) and early mechanisms of lung remodeling (degradation of elastic fiber tissues, collagen deposition, and goblet cell hyperplasia). Methods: Using an ovalbumin-induced acute allergic asthma model in BALB/c mice, we analyzed the inflammatory mediators through immunohistochemistry and the mechanisms of lung remodeling through histopathology, employing orcein, Masson's trichrome, and periodic acid-Schiff staining. Results: Copaiba oil treatment (CO) reduced IL-33 and increased FOXP3 by stimulating the FOXP3/GATA3 and FOXP3/STAT3 pathways. Additionally, it upregulated TBET, suggesting an additional role in controlling GATA3 activity. In the respiratory epithelium, CO decreased the fragmentation of elastic fibers while increasing the deposition of collagen fibers, favoring epithelial restructuring. Simultaneously, CO reduced goblet cell hyperplasia. Discussion: Although additional research is warranted, the demonstrated anti-inflammatory and re-epithelializing action makes CO a viable option in exploring new treatments for acute allergic asthma.

Multicomponent DNAzyme Nanomachines: Structure, Applications, and Prospects

Nucleic acids (NAs) are important components of living organisms responsible for the storage and transmission of hereditary information. They form complex structures that can self-assemble and bind to various biological molecules. DNAzymes are NAs capable of performing simple chemical reactions, which makes them potentially useful elements for creating DNA nanomachines with required functions. This review focuses on multicomponent DNA-based nanomachines, in particular on DNAzymes as their main functional elements, as well as on the structure of DNAzyme nanomachines and their application in the diagnostics and treatment of diseases. The article also discusses the advantages and disadvantages of DNAzyme-based nanomachines and prospects for their future applications. The review provides information about new technologies and the possibilities of using NAs in medicine.

Inhaled RNA drugs to treat lung diseases: Disease-related cells and nano-bio interactions

In recent years, RNA-based therapies have gained much attention as biomedicines due to their remarkable therapeutic effects with high specificity and potency. Lung diseases offer a variety of currently undruggable but attractive targets that could potentially be treated with RNA drugs. Inhaled RNA drugs for the treatment of lung diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, and acute respiratory distress syndrome, have attracted more and more attention. A variety of novel nanoformulations have been designed and attempted for the delivery of RNA drugs to the lung via inhalation. However, the delivery of RNA drugs via inhalation poses several challenges. It includes protection of the stability of RNA molecules, overcoming biological barriers such as mucus and cell membrane to the delivery of RNA molecules to the targeted cytoplasm, escaping endosomal entrapment, and circumventing unwanted immune response etc. To address these challenges, ongoing researches focus on developing innovative nanoparticles to enhance the stability of RNA molecules, improve cellular targeting, enhance cellular uptake and endosomal escape to achieve precise delivery of RNA drugs to the intended lung cells while avoiding unwanted nano-bio interactions and off-target effects. The present review first addresses the pathologic hallmarks of different lung diseases, disease-related cell types in the lung, and promising therapeutic targets in these lung cells. Subsequently we highlight the importance of the nano-bio interactions in the lung that need to be addressed to realize disease-related cell-specific delivery of inhaled RNA drugs. This is followed by a review on the physical and chemical characteristics of inhaled nanoformulations that influence the nano-bio interactions with a focus on surface functionalization. Finally, the challenges in the development of inhaled nanomedicines and some key aspects that need to be considered in the development of future inhaled RNA drugs are discussed.

Structure of a 10-23 deoxyribozyme exhibiting a homodimer conformation

Deoxyribozymes (DNAzymes) are in vitro evolved DNA sequences capable of catalyzing chemical reactions. The RNA-cleaving 10-23 DNAzyme was the first DNAzyme to be evolved and possesses clinical and biotechnical applications as a biosensor and a knockdown agent. DNAzymes do not require the recruitment of other components to cleave RNA and can turnover, thus they have a distinct advantage over other knockdown methods (siRNA, CRISPR, morpholinos). Despite this, a lack of structural and mechanistic information has hindered the optimization and application of the 10-23 DNAzyme. Here, we report a 2.7 Å crystal structure of the RNA-cleaving 10-23 DNAzyme in a homodimer conformation. Although proper coordination of the DNAzyme to substrate is observed along with intriguing patterns of bound magnesium ions, the dimer conformation likely does not capture the true catalytic form of the 10-23 DNAzyme.

Structure of a 10-23 Deoxyribozyme Exhibiting a Homodimer Conformation

Deoxyribozymes (DNAzymes) are in vitro evolved DNA sequences capable of catalyzing chemical reactions. The RNA cleaving 10-23 DNAzyme was the first DNAzyme to be evolved and possesses clinical and biotechnical applications as a biosensor and a knockdown agent. DNAzymes do not require the recruitment of other components to cleave RNA and can turnover, thus they have a distinct advantage over other knockdown methods (siRNA, CRISPR, morpholinos). Despite this, a lack of structural and mechanistic information has hindered the optimization and application of the 10-23 DNAzyme. Here, we report a 2.7 Å crystal structure of the RNA cleaving 10-23 DNAzyme in a homodimer conformation. Although proper coordination of the DNAzyme to substrate is observed along with intriguing patterns of bound magnesium ions, the dimer conformation likely does not capture the true catalytic form of the 10-23 DNAzyme.

XNAzymes targeting the SARS-CoV-2 genome inhibit viral infection

The unprecedented emergence and spread of SARS-CoV-2, the coronavirus responsible for the COVID-19 pandemic, underscores the need for diagnostic and therapeutic technologies that can be rapidly tailored to novel threats. Here, we show that site-specific RNA endonuclease XNAzymes - artificial catalysts composed of single-stranded synthetic xeno-nucleic acid oligonucleotides (in this case 2'-deoxy-2'-fluoro-β-D-arabino nucleic acid) - may be designed, synthesised and screened within days, enabling the discovery of a range of enzymes targeting SARS-CoV-2 ORF1ab, ORF7b, spike- and nucleocapsid-encoding RNA. Three of these are further engineered to self-assemble into a catalytic nanostructure with enhanced biostability. This XNA nanostructure is capable of cleaving genomic SARS-CoV-2 RNA under physiological conditions, and when transfected into cells inhibits infection with authentic SARS-CoV-2 virus by RNA knockdown. These results demonstrate the potential of XNAzymes to provide a platform for the rapid generation of antiviral reagents.

A modular XNAzyme cleaves long, structured RNAs under physiological conditions and enables allele-specific gene silencing

Nucleic-acid catalysts (ribozymes, DNA- and XNAzymes) cleave target (m)RNAs with high specificity but have shown limited efficacy in clinical applications. Here we report on the in vitro evolution and engineering of a highly specific modular RNA endonuclease XNAzyme, FR6_1, composed of 2'-deoxy-2'-fluoro-β-D-arabino nucleic acid (FANA). FR6_1 overcomes the activity limitations of previous DNA- and XNAzymes and can be retargeted to cleave highly structured full-length (>5 kb) BRAF and KRAS mRNAs at physiological Mg2+ concentrations with allelic selectivity for tumour-associated (BRAF V600E and KRAS G12D) mutations. Phosphorothioate-FANA modification enhances FR6_1 biostability and enables rapid KRAS mRNA knockdown in cultured human adenocarcinoma cells with a G12D-allele-specific component provided by in vivo XNAzyme cleavage activity. These results provide a starting point for the development of improved gene-silencing agents based on FANA or other XNA chemistries.

In Vitro and In Vivo Validation of GATA-3 Suppression for Induction of Adipogenesis and Improving Insulin Sensitivity

Impaired adipogenesis is associated with the development of insulin resistance and an increased risk of type 2 diabetes (T2D). GATA Binding Protein 3 (GATA3) is implicated in impaired adipogenesis and the onset of insulin resistance. Therefore, we hypothesize that inhibition of GATA3 could promote adipogenesis, restore healthy fat distribution, and enhance insulin signaling. Primary human preadipocytes were treated with GATA3 inhibitor (DNAzyme hgd40). Cell proliferation, adipogenic capacity, gene expression, and insulin signaling were measured following well-established protocols. BALB/c mice were treated with DNAzyme hgd40 over a period of 2 weeks. Liposomes loaded with DNAzyme hgd40, pioglitazone (positive), or vehicle (negative) controls were administered subcutaneously every 2 days at the right thigh. At the end of the study, adipose tissues were collected and weighed from the site of injection, the opposite side, and the omental depot. Antioxidant enzyme (superoxide dismutase and catalase) activities were assessed in animals’ sera, and gene expression was measured using well-established protocols. In vitro GATA3 inhibition induced the adipogenesis of primary human preadipocytes and enhanced insulin signaling through the reduced expression of p70S6K. In vivo GATA3 inhibition promoted adipogenesis at the site of injection and reduced MCP-1 expression. GATA3 inhibition also reduced omental tissue size and PPARγ expression. These findings suggest that modulating GATA3 expression offers a potential therapeutic benefit by correcting impaired adipogenesis, promoting healthy fat distribution, improving insulin sensitivity, and potentially lowering the risk of T2D.

GATA3 as an immunomodulator in obesity-related metabolic dysfunction associated with fatty liver disease, insulin resistance, and type 2 diabetes

Obesity is the leading risk factor associated with Metabolic dysfunction Associated with Fatty Liver Disease (MAFLD), Insulin Resistance (IR), and type 2 diabetes (T2DM). Notably, MAFLD affects 25% of the world's adult population, ranging from 13.5% in Africa to 31.8% in the Middle East. The prevalence of MAFLD is 80-90% in obese adults and 30-50% in patients with diabetes. According to the recent WHO update, more than 400 million people will experience T2DM by 2025. Furthermore, the worldwide obesity incidence rate has risen in the preceding years. Adipogenesis deterioration is a critical step in the induction of obesity correlated with MAFLD, IR and T2DM. The well-known transcription factor GATA3 is highly expressed in the preadipocytes-adipocytes transition of embryonic stem cells and obese people with IR. In this regard, the reduction of GATA3 improves the differentiation of adipocytes. Omental adipose tissue inflammation by upregulation of macrophages infiltration is strongly linked with body mass index in insulin tolerance of obese people. In particular, the dynamic interaction between macrophages and adipocytes significantly regulates obese adipose tissue's inflammatory status and influences IR by reducing the differentiation of adipocytes, macrophage function, and glucose transport. Emerging evidence demonstrated that GATA3 is a master regulator for macrophage polarization and infiltration. Hence, we will shed light on GATA3 as an emerging target for immunomodulation in human obesity associated with MAFLD, IR, and T2DM by reducing macrophages' recruitment and inflammation of muscles and liver.

Advances in the design of new types of inhaled medicines

Inhalation of small molecule drugs has proven very efficacious for the treatment of respiratory diseases due to enhanced efficacy and a favourable therapeutic index compared with other dosing routes. It enables targeted delivery to the lung with rapid onset of therapeutic action, low systemic drug exposure, and thereby reduced systemic side effects. An increasing number of pharmaceutical companies and biotechs are investing in new modalities-for this review defined as therapeutic molecules with a molecular weight >800Da and therefore beyond usual inhaled small molecule drug-like space. However, our experience with inhaled administration of PROTACs, peptides, oligonucleotides (antisense oligonucleotides, siRNAs, miRs and antagomirs), diverse protein scaffolds, antibodies and antibody fragments is still limited. Investigating the retention and metabolism of these types of molecules in lung tissue and fluid will contribute to understanding which are best suited for inhalation. Nonetheless, the first such therapeutic molecules have already reached the clinic. This review will provide information on the physiology of healthy and diseased lungs and their capacity for drug metabolism. It will outline the stability, aggregation and immunogenicity aspects of new modalities, as well as recap on formulation and delivery aspects. It concludes by summarising clinical trial outcomes with inhaled new modalities based on information available at the end of 2021.

Novel Insights into the Therapeutic Potential of Lung-Targeted Gene Transfer in the Most Common Respiratory Diseases

Over the past decades, a better understanding of the genetic and molecular alterations underlying several respiratory diseases has encouraged the development of new therapeutic strategies. Gene therapy offers new therapeutic alternatives for inherited and acquired diseases by delivering exogenous genetic materials into cells or tissues to restore physiological protein expression and/or activity. In this review, we review (1) different types of viral and non-viral vectors as well as gene-editing techniques; and (2) the application of gene therapy for the treatment of respiratory diseases and disorders, including pulmonary arterial hypertension, idiopathic pulmonary fibrosis, cystic fibrosis, asthma, alpha-1 antitrypsin deficiency, chronic obstructive pulmonary disease, non-small-cell lung cancer, and COVID-19. Further, we also provide specific examples of lung-targeted therapies and discuss the major limitations of gene therapy.

The Role of CD4+ T Cells and Microbiota in the Pathogenesis of Asthma

Asthma, a chronic respiratory disease involving variable airflow limitations, exhibits two phenotypes: eosinophilic and neutrophilic. The asthma phenotype must be considered because the prognosis and drug responsiveness of eosinophilic and neutrophilic asthma differ. CD4+ T cells are the main determinant of asthma phenotype. Th2, Th9 and Tfh cells mediate the development of eosinophilic asthma, whereas Th1 and Th17 cells mediate the development of neutrophilic asthma. Elucidating the biological roles of CD4+ T cells is thus essential for developing effective asthma treatments and predicting a patient's prognosis. Commensal bacteria also play a key role in the pathogenesis of asthma. Beneficial bacteria within the host act to suppress asthma, whereas harmful bacteria exacerbate asthma. Recent literature indicates that imbalances between beneficial and harmful bacteria affect the differentiation of CD4+ T cells, leading to the development of asthma. Correcting bacterial imbalances using probiotics reportedly improves asthma symptoms. In this review, we investigate the effects of crosstalk between the microbiota and CD4+ T cells on the development of asthma.

A GATA3 Targeting Nucleic Acid Nanocapsule for In Vivo Gene Regulation in Asthma

Allergic asthma is one of the leading chronic lung diseases of both children and adults worldwide, resulting in significant morbidity and mortality in affected individuals. Many patients have severe asthma, which is refractory to treatment, illustrating the need for the development of new therapeutics for this disease. Herein, we describe the use of a peptide cross-linked nucleic acid nanocapsule (NAN) for the delivery of a GATA3-specific DNAzyme to immune cells, with demonstration of modulated transcriptional activity and behavior of those cells. The NAN, built from peptide cross-linked surfactants, is chemically designed to degrade under inflammation conditions releasing individual DNAzyme-surfactant conjugates in response to proteolytic enzymes. Using the NAN, GATA3 DNAzymes were delivered efficiently to human peripheral blood mononuclear cells, with clear evidence of uptake by CD4+ helper T cells without the need for harsh transfection agents. Knockdown of GATA3 was achieved in vitro using human Jurkat T cells, which express GATA3 under homeostatic conditions. Additionally, mice treated with DNAzyme-NANs during house dust mite (HDM)-induced asthma developed less severe allergic lung inflammation than HDM-only control mice, as measured by pulmonary eosinophilia. This study suggests that peptide cross-linked GATA3 DNAzyme-NANs may have the potential to decrease the severity of asthma symptoms in human patients, and development of this technology for human use warrants further investigation.

Regulation of Eosinophilia in Asthma-New Therapeutic Approaches for Asthma Treatment

Asthma is a complex and chronic inflammatory disease of the airways, characterized by variable and recurring symptoms, reversible airflow obstruction, bronchospasm, and airway eosinophilia. As the pathophysiology of asthma is becoming clearer, the identification of new valuable drug targets is emerging. IL-5 is one of these such targets because it is the major cytokine supporting eosinophilia and is responsible for terminal differentiation of human eosinophils, regulating eosinophil proliferation, differentiation, maturation, migration, and prevention of cellular apoptosis. Blockade of the IL-5 pathway has been shown to be efficacious for the treatment of eosinophilic asthma. However, several other inflammatory pathways have been shown to support eosinophilia, including IL-13, the alarmin cytokines TSLP and IL-33, and the IL-3/5/GM-CSF axis. These and other alternate pathways leading to airway eosinophilia will be described, and the efficacy of therapeutics that have been developed to block these pathways will be evaluated.

GATA-3 as a Potential Therapeutic Target for Insulin Resistance and Type 2 Diabetes Mellitus

Impaired adipogenesis plays an important role in the development of obesity-associated insulin resistance and type 2 diabetes as it leads to ectopic fat deposition. The anti-adipogenic transcription factor GATA-3 was identified as one of the potential molecular targets responsible for the impairment of adipogenesis. The expression of GATA-3 is higher in insulinresistant obese individuals compared to BMI-matched insulin-sensitive counterparts. Adipose tissue inflammation is a crucial mediator of this process. Hyperglycemia mediates the activation of the immune system, partially through upregulation of GATA- 3, causing exacerbation of the inflammatory state associated with obesity. This review discusses the evidence supporting the inhibition of GATA-3 as a useful therapeutic strategy in obesity-associated insulin resistance and type 2 diabetes, through up-regulation adipogenesis and amelioration of the immune response.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

Suppression of GATA-3 increases adipogenesis, reduces inflammation and improves insulin sensitivity in 3T3L-1 preadipocytes

Impaired adipogenesis plays an important role in the development of obesity-associated insulin resistance and type 2 diabetes. Adipose tissue inflammation is a crucial mediator of this process. GATA-3 plays important roles in adipogenesis and inflammation. The aim of this study is to investigate the impact of GATA-3 suppression on improving adipogenesis, lowering inflammation and reversing insulin resistance. GATA-3 levels were measured in subcutaneous (SC) and omental (OM) adipose tissues obtained from insulin sensitive (IS) and insulin resistant (IR) obese individuals during weight reduction surgeries. The effect of GATA-3 suppression on adipogenesis, expression of inflammatory cytokines and insulin resistance biomarkers was performed in 3T3L-1 mouse preadipocytes via transfection with GATA-3-specific DNAzyme. GATA-3 expression was higher in OM compared to SC adipose tissues and in stromal vascular fraction-derived differentiating preadipocytes from IR obese individuals compared to their IS counterparts. Suppression of GATA-3 expression in 3T3L-1 mouse preadipocytes with GATA-3 specific inhibitor reversed 4-hydroxynonenal-induced impaired adipogenesis and triggered changes in the expression of insulin signaling-related genes. GATA-3 inhibition also modulated the expression of IL-6 and IL-10 and lowered the expression of insulin resistance biomarkers (PAI-1 and resistin) and insulin resistance phosphoproteins (p-BAD, p-PTEN and p-GSK3β). Inhibiting GATA-3 improves adipocytes differentiation, modulates the secretion of inflammatory cytokines and improves insulin sensitivity in insulin resistant cells. Suppression of GATA-3 could be a promising tool to improve adipogenesis, restore insulin sensitivity and lower obesity-associated inflammation in insulin resistant individuals.

Bronchial Asthma: Current Trends in Treatment

Asthma is a heterogenous disease which pathophysiology is still poorly understood. Asthma was traditionally divided into allergic (extrinsic) and non-allergic (intrinsic) types, while patients with allergic type responded better to corticosteroids. Since 2013 the definition of asthma has changed. Recently, better insight into clinical consi -derations and underlying inflammatory phenotypes has been gained. Defining these phenotypes has already led to more specific clinical trials and, therefore, to more personalized and successfully targeted therapy. For future, much more effort is put in identifying new phenotype-specific biomarkers which could be helpful in stratification of heterogeneous patients with asthma.

DNAzyme-Mediated Genetically Encoded Sensors for Ratiometric Imaging of Metal Ions in Living Cells

Genetically encoded fluorescent proteins (FPs) have been used for metal ion detection. However, their applications are restricted to a limited number of metal ions owing to the lack of available metal-binding proteins or peptides that can be fused to FPs and the difficulty in transforming the binding of metal ions into a change of fluorescent signal. We report herein the use of Mg²⁺ -specific 10-23 or Zn²⁺ -specific 8-17 RNA-cleaving DNAzymes to regulate the expression of FPs as a new class of ratiometric fluorescent sensors for metal ions. Specifically, we demonstrate the use of DNAzymes to suppress the expression of Clover2, a variant of the green FP (GFP), by cleaving the mRNA of Clover2, while the expression of Ruby2, a mutant of the red FP (RFP), is not affected. The Mg²⁺ or Zn²⁺ in HeLa cells can be detected using both confocal imaging and flow cytometry. Since a wide variety of metal-specific DNAzymes can be obtained, this method can likely be applied to imaging many other metal ions, expanding the range of the current genetically encoded fluorescent protein-based sensors.

The emergence of new biologics for severe asthma

Patients with severe asthma experience severe symptoms and frequent exacerbations despite intensive treatment with inhaled and oral glucocorticoids. Biologics for severe asthma aim to reduce asthma-related and glucocorticoid-induced morbidity. Recently, new biologics targeting interleukin (IL)-5, IL-5 receptor and IL-4/IL-13, which are all cytokines involved in so-called type 2 airway inflammation, were approved for severe asthma. They show a reduction in exacerbation rate and an oral glucocorticoid-sparing effect. Studies with upstream biologics targeting alarmin cytokines such as thymic stromal lymphopoietin (TSLP) and IL-33 are underway, and newly designed bispecific antibodies targeting more than one pathway are in early phases of development. Such pathway-targeted add-on treatments will soon become standard of care for all patients with severe asthma.

Current and future targeted therapies for severe asthma: Managing treatment with biologics based on phenotypes and biomarkers

Asthma is a respiratory disorder with considerable heterogeneity in aetiology, triggers, clinical characteristics and response to therapy. This diversity reflects different inflammatory pathways that can be subdivided into clinically similar categories called phenotypes, or pathogenically comparable groups called endotypes. In recent years, a great amount of research has been dedicated to the investigation and understanding of the heterogeneity of asthma pathophysiology and to the identification of treatable traits, biomarkers, mediators and therapeutic targets. Severe asthma is defined as an uncontrolled disease despite a maximal conventional therapeutic approach. While, to date, some target therapies showing improvements in lung function, asthma symptoms and a reduction of the annual rate of exacerbations in patients with severe asthma have been already approved, other treatments are currently being studied, specifically targeting Type 2 asthma. Further progress however, is still needed to tackle the molecular pathways for non-Type 2 asthma. The aim of the present narrative review is to discuss and examine the indication, mechanisms of action and therapeutic effects of currently available and emerging biologic agents for the treatment of severe asthma.

Beyond DNA and RNA: The Expanding Toolbox of Synthetic Genetics

The remarkable physicochemical properties of the natural nucleic acids, DNA and RNA, define modern biology at the molecular level and are widely believed to have been central to life's origins. However, their ability to form repositories of information as well as functional structures such as ligands (aptamers) and catalysts (ribozymes/DNAzymes) is not unique. A range of nonnatural alternatives, collectively termed xeno nucleic acids (XNAs), are also capable of supporting genetic information storage and propagation as well as evolution. This gives rise to a new field of "synthetic genetics," which seeks to expand the nucleic acid chemical toolbox for applications in both biotechnology and molecular medicine. In this review, we outline XNA polymerase and reverse transcriptase engineering as a key enabling technology and summarize the application of "synthetic genetics" to the development of aptamers, enzymes, and nanostructures.

Pulmonary group 2 innate lymphoid cells: surprises and challenges

Group 2 innate lymphoid cells (ILC2s) are a recently described subset of innate lymphocytes with important immune and homeostatic functions at multiple tissue sites, especially the lung. These cells expand locally after birth and during postnatal lung maturation and are present in the lung and other peripheral organs. They are modified by a variety of processes and mediate inflammatory responses to respiratory pathogens, inhaled allergens and noxious particles. Here, we review the emerging roles of ILC2s in pulmonary homeostasis and discuss recent and surprising advances in our understanding of how hormones, age, neurotransmitters, environmental challenges, and infection influence ILC2s. We also review how these responses may underpin the development, progression and severity of pulmonary inflammation and chronic lung diseases and highlight some of the remaining challenges for ILC2 biology.

Severe refractory asthma: current treatment options and ongoing research

Patients with severe asthma have a greater risk of asthma-related symptoms, morbidities, and exacerbations. Moreover, healthcare costs of patients with severe refractory asthma are at least 80% higher than those with stable asthma, mainly because of a higher use of healthcare resources and chronic side effects of oral corticosteroids (OCS). The advent of new promising biologicals provides a unique therapeutic option that could achieve asthma control without OCS. However, the increasing number of available molecules poses a new challenge: the identification and selection of the most appropriate treatment. Thanks to a better understanding of the basic mechanisms of the disease and the use of predictive biomarkers, especially regarding the Th2-high endotype, it is now easier than before to tailor therapy and guide clinicians toward the most suitable therapeutic choice, thus reducing the number of uncontrolled patients and therapeutic failures. In this review, we will discuss the different biological options available for the treatment of severe refractory asthma, their mechanism of action, and the overlapping aspects of their usage in clinical practice. The availability of new molecules, specific for different molecular targets, is a key topic, especially when considering that the same targets are sometimes part of the same phenotype. The aim of this review is to help clarify these doubts, which may facilitate the clinical decision-making process and the achievement of the best possible outcomes.

RNA-Cleaving DNAzymes: Old Catalysts with New Tricks for Intracellular and In Vivo Applications

DNAzymes are catalytically active DNA molecules that are normally isolated through in vitro selection methods, among which RNA-cleaving DNAzymes that catalyze the cleavage of a single RNA linkage embedded within a DNA strand are the most studied group of this DNA enzyme family. Recent advances in DNA nanotechnology and engineering have generated many RNA-cleaving DNAzymes with unique recognition and catalytic properties. Over the past decade, numerous RNA-cleaving, DNAzymes-based functional probes have been introduced into many research areas, such as in vitro diagnostics, intracellular imaging, and in vivo therapeutics. This review focus on the fundamental insight into RNA-Cleaving DNAzymes and technical tricks for their intracellular and in vivo applications, highlighting the recent progress in the clinical trial of RNA-Cleaving DNAzymes with selected examples. The challenges and opportunities for the future translation of RNA-cleaving DNAzymes for biomedicine are also discussed.

Systemic delivery of mesenchymal stem cells condition media in repeated doses acts as magic bullets in restoring IFN-γ/IL-4 balance in asthmatic rats

AIMS

With respect to recent advantage in stem cell application, given the concern reported previously after stem cell transplantation, mesenchymal stem cell-derived conditioned media (MSC-CM) could be a potential approach to guarantee more safety and efficient outcomes than the current stem cell-based regenerative therapies.

MAIN METHODS

Male rats were assigned into four experimental groups (n = 6); healthy rats (C group), OVA sensitized rats (S group), OVA sensitized rats received a single dose of 50 μl CM intravenously (S group + SD-CM) and OVA sensitized rats received repeated doses of 50 μl CM intravenously (S group + RD-CM). Two weeks post-allergen challenge, the therapeutic effects of systemic administrated CM in single and repeated dosages were investigated by monitoring the transcription of T-bet, GATA-3, IL-4 and IFN-γ genes along with pathological changes in asthmatic lung tissue. IL-4 and IFN-γ levels and IFN-γ/IL-4 ratio were further evaluated in sera.

KEY FINDINGS

Our data revealed that the systemic introduction of CM in repeated dosages could significantly reduce pathological injures in OVA-sensitized rats by the modulation of expression of T-bet and GATA-3 in lung tissues and interleukins levels (p < 0.001 to p < 0.05). In contrary, CM in single dosage did not yield any beneficial effect.

SIGNIFICANCE

Overall, we indicated that systemic administration of CM in repeated dosages, but not in single dose, could be strategic approach in amelioration of asthmatic changes, presumably by the regulating the differentiation of naive CD4 T cells into Th1/Th2 effector cells via modulation of T-bet and GATA-3 expression in OVA-sensitized male rats.

Histone modifications and their role in epigenetics of atopy and allergic diseases

This review covers basic aspects of histone modification and the role of posttranslational histone modifications in the development of allergic diseases, including the immune mechanisms underlying this development. Together with DNA methylation, histone modifications (including histone acetylation, methylation, phosphorylation, ubiquitination, etc.) represent the classical epigenetic mechanisms. However, much less attention has been given to histone modifications than to DNA methylation in the context of allergy. A systematic review of the literature was undertaken to provide an unbiased and comprehensive update on the involvement of histone modifications in allergy and the mechanisms underlying this development. In addition to covering the growing interest in the contribution of histone modifications in regulating the development of allergic diseases, this review summarizes some of the evidence supporting this contribution. There are at least two levels at which the role of histone modifications is manifested. One is the regulation of cells that contribute to the allergic inflammation (T cells and macrophages) and those that participate in airway remodeling [(myo-) fibroblasts]. The other is the direct association between histone modifications and allergic phenotypes. Inhibitors of histone-modifying enzymes may potentially be used as anti-allergic drugs. Furthermore, epigenetic patterns may provide novel tools in the diagnosis of allergic disorders.

Biologic Therapy and Novel Molecular Targets of Severe Asthma

Treatment options for severe or uncontrolled asthma are increasing, especially pertaining to novel biologic therapies. The 2 primary asthma endotypes, T2 high and T2 low, are defined by the level of type 2 T helper and innate lymphoid cell activity and mediators. Most therapies for severe asthma target T2 high asthma, including the 3 biologics approved for use in the United States and Europe: omalizumb, mepolizumb, and reslizumab. Other biologics, with various molecular targets, are under investigation. Unfortunately, treatment options for T2 low asthma are limited. Although these therapies may improve asthma symptoms, exacerbation rates, and lung function parameters, they have not been shown to modify the disease process or provide lasting benefits after discontinuation. Biomarkers identified thus far to help guide individualized therapy in severe asthma are helpful, but imperfect discriminators for picking the best option for individual patients. This review will discuss the mechanisms of action, indications, and therapeutic effects of currently available and emerging biologics for the treatment of severe or uncontrolled asthma.

Pharmacological targeting of allergen-specific T lymphocytes

Allergic disorders are the result of a complex pathophysiology, involving major cellular lineages and a multitude of humoral factors of the innate and adaptive immune system, and have the tendency to involve multiple organs. Consequently, even standard pharmacological treatment of allergies is rarely specific but usually targets more than one pathway/cellular system at a time. Accordingly, many of the classic anti-allergic drugs have a critical impact also on T helper cells, which are pivotal not only during the sensitization but also the maintenance phase of allergic diseases. Recent years have seen a dramatic increase of novel drugs with the potency to interfere, more or less specifically, with T lymphocyte function, which might, possibly together with classic anti-allergic drugs, help harnessing one of the central cellular players in allergic responses. A major theme in the years to come will be a thoughtful combination of previously established with recently developed treatment modalities.