Immune Modulation in Asthma: Current Concepts and Future Strategies

Clinical remission and control in severe asthma: agreements and disagreements

Over the last two decades, we have witnessed great advancements in our understanding of the immunological pathways of asthma, leading to the development of targeted therapies, such as biologic drugs, that have radically and definitively changed the clinical outcomes of severe asthma. Despite the numerous therapeutic options available, ~4-10% of all people with asthma have severe or uncontrolled asthma, associated with an increased risk of developing chronic oral corticosteroid use, fixed airflow limitation, exacerbations, hospitalization and, finally, increased healthcare costs. The new concept of disease modification in asthma comes from the evolution of asthma management, which encompasses phenotyping patients with different inflammatory endotypes characterizing the disease, followed by the advent of more effective therapies capable of targeting the proximal factors of airway inflammation. This treat-to-target approach aims to achieve remission of the disease. Because the novel treatment paradigm for severe asthma with the advent of biologic therapies is no longer clinical control but rather clinical remission - a step closer to the concept of cure - a deeper and more accurate understanding of the critical causal mechanisms and endotypes of asthma is necessary to achieve the goal of clinical remission, which has the potential to generate real life-changing benefits for patients. This review aims to frame the evolution of the debated concept of clinical remission and provide clinicians with insights that may be helpful in achieving remission in the greatest number of patients.

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

Photobiomodulation Mitigates PM2.5-Exacerbated Pathologies in a Mouse Model of Allergic Asthma

Exposure to particulate matter (PM), especially PM2.5, is known to exacerbate asthma, posing a significant public health risk. This study investigated the asthma-reducing effects of photobiomodulation (PBM) in a mice model mimicking allergic airway inflammation exacerbated by PM2.5 exposure. The mice received sensitization with ovalbumin (OVA) and were subsequently treated with PM2.5 at a dose of 0.1 mg/kg every 3 days, for 9 times over 3 weeks during the challenge. PBM, using a 610 nm wavelength LED, was applied at 1.7 mW/cm2 to the respiratory tract via direct skin contact for 20 min daily for 19 days. Results showed that PBM significantly reduced airway hyperresponsiveness, plasma immunoglobulin E (IgE) and OVA-specific IgE, airway inflammation, T-helper type 2 cytokine, histamine and tryptase in bronchoalveolar lavage fluid (BALF), and goblet cell hyperplasia in PM2.5-exposed asthmatic mice. Moreover, PBM alleviated subepithelial fibrosis by reducing collagen deposition, airway smooth muscle mass, and expression of fibrosis-related genes. It mitigated reactive oxygen species generation, oxidative stress, endoplasmic reticulum stress, apoptotic cell death, ferroptosis, and modulated autophagic signals in the asthmatic mice exposed to PM2.5. These findings suggest that PBM could be a promising intervention for PM2.5-induced respiratory complications in patients with allergic asthma.

Blood eosinophils and fractional exhaled nitric oxide are prognostic and predictive biomarkers in childhood asthma

BACKGROUND

Blood eosinophils and fractional exhaled nitric oxide (Feno) are prognostic biomarkers for exacerbations and predict lung function responses to dupilumab in adolescents and adults with asthma.

OBJECTIVE

We evaluated the relationship between baseline blood eosinophils and Feno and response to dupilumab in children with asthma.

METHODS

Children aged 6 to 11 years with uncontrolled moderate-to-severe asthma (n = 408) were randomized to receive dupilumab 100/200 mg by body weight or volume-matched placebo every 2 weeks for 52 weeks. Annualized exacerbation rate (AER) reduction and least squares mean change in prebronchodilator percent predicted forced expiratory volume in 1 second (ppFEV1) at week 12 were assessed according to cutoff baseline levels for Feno (<20 ppb vs ≥20 ppb) and blood eosinophil count (<150, ≥150 to <300, ≥300 to <500, and ≥500 cells/μL). Quadrant analyses in populations defined by biomarker thresholds and spline models across continuous end points assessed the relationship with Feno and eosinophil count. Interaction testing evaluated the independent roles of Feno and blood eosinophils as predictive markers.

RESULTS

Exacerbation risk and magnitude of AER reduction increased in subgroups with higher baseline biomarker levels. Quadrant analyses revealed that disease of patients with either elevated Feno or eosinophil counts demonstrated a clinical response to dupilumab. Interaction testing indicated blood eosinophil counts or Feno independently added value as predictive biomarkers.

CONCLUSIONS

In children with uncontrolled moderate-to-severe asthma, blood eosinophil counts and Feno are clinically relevant biomarkers to identify those at risk for asthma exacerbations, as well as those with disease with clinical response to dupilumab.

TRIAL REGISTRATION

Liberty Asthma VOYAGE ClinicalTrials.gov NCT02948959.

Remission in asthma

PURPOSE OF REVIEW

To review the current concepts of remission in asthma.

RECENT FINDINGS

Until 2023, asthma guidelines have been promoting the concept of disease control, recommending the step-wise addition of drugs until the best possible disease control is achieved. With the advent of highly effective, anti-inflammatory disease-modifying antiasthmatic drugs (DMAADs), treatment goals of asthma have changed. Several national guidelines have now announced remission as a general treatment goal in asthma. Currently, all guidelines agree that asthma remission is defined by the presence of at least three characteristics over a period of at least one 1 year: absence of exacerbations, no systemic corticosteroid use for the treatment of asthma and minimal asthma-related symptoms. In the future, a generally accepted, evidence-based and easy-to-use definition of remission will be needed for daily clinical practice. It is clear, however, that precise phenotyping (including measurement of biomarkers) is an essential prerequisite to achieve clinical remission in each individual patient.

SUMMARY

Remission has been included as the treatment goal in asthma in several national guidelines, reflecting the paradigm shift in asthma, from short-term symptom control to long-term symptom prevention. An international consensus on the criteria for asthma remission is expected in the near future.

Circular RNAs: emerging players in asthma and COPD

Circular RNAs (circRNAs) belong to a unique class of endogenously expressed non-protein-coding RNAs with a distinct circularized structure, characterized by the absence of 5'-cap and 3'-polyadenylate ends. They are generally formed through back-splicing from pre-mRNAs. They serve as regulators of transcription and splicing, and act as sponges for microRNAs (miRNAs) and RNA-binding proteins, thereby modulating the expression of target genes. As a result, they exert a substantial impact on a diverse array of cellular and biological processes, including cell proliferation, migration, inflammation, and oxidative stress. Asthma and COPD are chronic airway conditions that currently have no cure. In recent years, emerging evidence suggests that altered expression of circRNAs in airway, bronchial and immune cells is involved in asthma and COPD pathogenesis. Studies exploring circRNA dysregulation in asthma have showcased their involvement in regulating the proliferation, migration, and inflammation of airway smooth muscle and bronchial epithelial cells, as well as impacting goblet cell metaplasia, Th2 cell differentiation, and macrophage activation, primarily through interactions with miRNAs. Similarly, in COPD, circRNAs have shown altered expression patterns in the blood and lungs of patients, and these changes have been linked to modulating inflammation, oxidative stress, and airway remodeling in preclinical models. Furthermore, certain circRNAs have demonstrated promising potential as diagnostic and prognostic biomarkers for both asthma and COPD. This review delves into the current understanding of the function and molecular mechanisms of circRNAs in asthma and COPD, along with exploring their potential as biomarkers in these respiratory conditions.

[Diagnosis and treatment of asthma: a guideline for respiratory specialists 2023 - published by the German Respiratory Society (DGP) e. V.]

The management of asthma has fundamentally changed during the past decades. The present guideline for the diagnosis and treatment of asthma was developed for respiratory specialists who need detailed and evidence-based information on the new diagnostic and therapeutic options in asthma. The guideline shows the new role of biomarkers, especially blood eosinophils and fractional exhaled NO (FeNO), in diagnostic algorithms of asthma. Of note, this guideline is the first worldwide to announce symptom prevention and asthma remission as the ultimate goals of asthma treatment, which can be achieved by using individually tailored, disease-modifying anti-asthmatic drugs such as inhaled steroids, allergen immunotherapy or biologics. In addition, the central role of the treatment of comorbidities is emphasized. Finally, the document addresses several challenges in asthma management, including asthma treatment during pregnancy, treatment of severe asthma or the diagnosis and treatment of work-related asthma.

Investigation on the use of fused deposition modeling for the production of IR dosage forms containing Timapiprant

The present work focused on evaluating the feasibility of fused deposition modeling (FDM) in the development of a dosage form containing Timapiprant (TMP), also known as CHF6532, which is a novel active molecule indicated in the potential treatment of eosinophilic asthma upon oral administration. The resulting product could be an alternative, with potential towards personalization, of immediate release (IR) tablets used in the clinical studies. Formulations based on different polymeric carriers were screened, leading to the identification of a polyvinyl alcohol-based one, which turned out acceptable for versatility in terms of active ingredient content, printability and dissolution performance (i.e. capability to meet the dissolution specification set, envisaging >80% of the drug dissolved within 30 min). Following an in-depth evaluation on the influence of TMP solid state and of the voids volume resulting from printing on dissolution, few prototypes with shapes especially devised for therapy customization were successfully printed and were compliant with the dissolution specification set.

The Correlation of PM2.5 Exposure with Acute Attack and Steroid Sensitivity in Asthma

Bronchial asthma is a common chronic inflammatory disease of the respiratory system. Asthma primarily manifests in reversible airflow limitation and airway inflammation, airway remodeling, and persistent airway hyperresponsiveness. PM2.5, also known as fine particulate matter, is the main component of air pollution and refers to particulate matter with an aerodynamic diameter of ≤2.5 μm. PM2.5 can be suspended in the air for an extensive time and, in addition, can contain or adsorb heavy metals, toxic gases, polycyclic aromatic hydrocarbons, bacterial viruses, and other harmful substances. Epidemiological studies have demonstrated that, in addition to increasing the incidence of asthma, PM2.5 exposure results in a significant increase in the incidence of hospital visits and deaths due to acute asthma attacks. Furthermore, PM2.5 was reported to induce glucocorticoid resistance in asthmatic individuals. Although various countries have implemented strict control measures, due to the wide range of PM2.5 sources, complex components, and unknown pathogenic mechanisms involving the atmosphere, environment, chemistry, and toxicology, PM2.5 damage to human health still cannot be effectively controlled. In this present review, we summarized the current knowledge base regarding the relationship between PM2.5 toxicity and the onset, acute attack prevalence, and steroid sensitivity in asthma.

Molecular and Immunomodulatory Actions of New Antiasthmatic Agents: Exploring the Diversity of Biologics in Th2 Endotype Asthma

Asthma is a major respiratory disorder characterised by chronic inflammation and airway remodelling. It affects about 1-8% of the global population and is responsible for over 461,000 deaths annually. Until recently, the pharmacotherapy of severe asthma involved high doses of inhaled corticosteroids in combination with β-agonist for prolonged action, including theophylline, leukotriene antagonist or anticholinergic yielding limited benefit. Although the use of newer agents to target Th2 asthma endotypes has improved therapeutic outcomes in severe asthmatic conditions, there seems to be a paucity of understanding the diverse mechanisms through which these classes of drugs act. This article delineates the molecular and immunomodulatory mechanisms of action of new antiasthmatic agents currently being trialled in preclinical and clinical studies to remit asthmatic conditions. The ultimate goal in developing antiasthmatic agents is based on two types of approaches: either anti-inflammatory or bronchodilators. Biologic and most small molecules have been shown to modulate specific asthma endotypes, targeting thymic stromal lymphopoietin, tryptase, spleen tyrosine kinase (Syk), Janus kinase, PD-L1/PD-L2, GATA-3, and CD38 for the treatment and management of Th2 endotype asthma.

IgE is associated with exacerbations and lung function decline in COPD

Background

Both allergen-specific IgE and total IgE in serum play a major role in asthma. However, the role of IgE in chronic obstructive pulmonary disease (COPD) is poorly understood. It was the aim of this study to systematically analyze the relationship between serum IgE levels and disease characteristics in large COPD cohorts.

Methods

COSYCONET is a comprehensively characterized cohort of patients with COPD: total IgE and IgE specific to common aeroallergens were measured in serum of 2280 patients, and related to clinical characteristics of the patients. WISDOM is another large COPD population (2477 patients): this database contains the information whether total IgE in serum was elevated (≥ 100 IU/l) or normal in patients with COPD.

Results

Both in COSYCONET and WISDOM, total IgE was elevated (≥ 100 IU/l) in > 30% of the patients, higher in men than in women, and higher in currently than in not currently smoking men. In COSYCONET, total IgE was elevated in patients with a history of asthma and/or allergies. Men with at least one exacerbation in the last 12 months (50.6% of all men in COSYCONET) had higher median total IgE (71.3 IU/l) than men without exacerbations (48.3 IU/l): this difference was also observed in the subgroups of not currently smoking men and of men without a history of asthma. Surprisingly, a history of exacerbations did not impact on total IgE in women with COPD. Patients in the highest tertiles of total IgE (> 91.5 IU/ml, adjusted OR: 1.62, 95% CI 1.12–2.34) or allergen-specific IgE (> 0.19 IU/ml, adjusted OR: 2.15, 95% CI 1.32–3.51) were at risk of lung function decline (adjusted by: age, gender, body mass index, initial lung function, smoking status, history of asthma, history of allergy).

Conclusion

These data suggest that IgE may play a role in specific COPD subgroups. Clinical trials using antibodies targeting the IgE pathway (such as omalizumab), especially in men with recurrent exacerbations and elevated serum IgE, could elucidate potential therapeutic implications of our observations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01847-0.

[Guideline for the Diagnosis and Treatment of Asthma - Addendum 2020 - Guideline of the German Respiratory Society and the German Atemwegsliga in Cooperation with the Paediatric Respiratory Society and the Austrian Society of Pneumology]

The present addendum of the guideline for the diagnosis and treatment of asthma (2017) complements new insights into the diagnosis and management of asthma as well as for the newly approved drugs for the treatment of asthma. Current, evidence-based recommendations on diagnostic and therapeutic approaches are presented for children and adolescents as well as for adults with asthma.

Oral corticosteroid prescription for asthma by general practitioners: A three-year analysis in Germany

BACKGROUND

Regular treatment of patients with asthma with oral corticosteroids (OCS) remains common despite potential severe side effects and alternative treatment options. However, there is limited data on the prevalence of OCS prescriptions for patients with asthma in Germany.

METHODS

Records from 1039 General practitioners for the years 2015-2017 in the German IMS® Disease Analyzer database were retrospectively analysed for patients with at least two confirmed asthma diagnoses (ICD-10) per observed year, representing approximately 30,000 patients per year. Asthma treatment steps (1-5) were assigned according to the German national guideline, based on prescribed therapies.

RESULTS

In the years 2015-2017, 20.3-21.3% of patients were classified as being in treatment step 1, 4.7-5.2% in step 2, 38.8-40.1% in step 3, 31.7-32.1% in step 4 and 2.7-3.2% in step 5. Proportions of patients treated with OCS >30 days/year were 9.4% (2015), 9.6% (2016) and 8.9% (2017), reducing to 8.1%, 8.2% and 7.4%, respectively, when patients with other inflammatory diseases possibly requiring OCS treatment were excluded. Use of OCS >30 days/year was more prevalent in patients aged >65 years (14.1-15.0%) than those aged 18-65 years (6.8-7.8%). Median daily prednisolone dose was 10-15 mg/day. Approximately 30% of patients treated with OCS >30 days/year were not in step 5 (based on their prescribed inhaled therapies).

CONCLUSION

These data suggest that a substantial proportion of patients with asthma in non-specialised care in Germany receive OCS prescriptions regularly, despite the availability of less harmful alternative treatment options.

The Treatment of Mild and Moderate Asthma in Adults

BACKGROUND

Asthma is a chronic inflammatory airway disease that usually causes variable airway obstruction. It affects 5-10% of the German population.

METHODS

This review is based on relevant publications retrieved by a selective search, as well as on national and international guidelines on the treatment of mild and moderate asthma in adults.

RESULTS

The goal of treatment is to attain optimal asthma control with a minimal risk of exacerbations and mortality, loss of pulmonary function, and drug side effects. This can be achieved with a combination of pharmacotherapy and non-drug treatment including patient education, exercise, smoking cessation, and rehabilitation. Pharmacohterapy is based on inhaled corticosteroids (ICS) and bronchodilators. It is recommended that mild asthma should be treated only when needed, either with a fixed combination of ICS and formoterol or with short-acting bronchodilators. For moderate asthma, maintenance treatment is recommended, with an inhaled fixed combinations of ICS and long-acting beta-mimetics, possibly supplemented with longacting anticholinergic agents. Allergen immunotherapy, i.e., desensitization treatment, should be considered if the allergic component of asthma is well documented and the patient is not suffering from uncontrolled asthma. Asthma control should be monitored at regular intervals, and the treatment should be adapted accordingly.

CONCLUSION

The treatment of asthma in adults should be individually tailored, with anti-inflammatory treatment as its main component.