Severe asthma in childhood: diagnostic and management challenges

TIPE2 inhibits PDGF-BB-induced phenotype switching in airway smooth muscle cells through the PI3K/Akt signaling pathway

Background

Childhood asthma is a common respiratory disease characterized by airway inflammation. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) has been found to be involved in the progression of asthma. This study aimed to explore the role of TIPE2 in the regulation of airway smooth muscle cells (ASMCs), which are one of the main effector cells in the development of asthma.

Materials and methods

ASMCs were transfected with pcDNA3.0-TIPE2 or si-TIPE2 for 48 h and then treated with platelet-derived growth factor (PDGF)-BB. Cell proliferation of ASMCs was measured using the MTT assay. Cell migration of ASMCs was determined by a transwell assay. The mRNA expression levels of calponin and smooth muscle protein 22α (SM22α) were measured using qRT-PCR. The levels of TIPE2, calponin, SM22α, PI3K, p-PI3K, Akt, and p-Akt were detected by Western blotting.

Results

Our results showed that PDGF-BB treatment significantly reduced TIPE2 expression at both the mRNA and protein levels in ASMCs. Overexpression of TIPE2 inhibited PDGF-BB-induced ASMC proliferation and migration. In addition, overexpression of TIPE2 increased the expression of calponin and SM22α in PDGF-BB-stimulated ASMCs. However, an opposite effect was observed with TIPE2 knockdown. Furthermore, TIPE2 overexpression blocked PDGF-BB-induced phosphorylation of PI3K and Akt, whereas the expression of p-PI3K and p-Akt were aggravated by TIPE2 knockdown. Additionally, the effects of TIPE2 overexpression and TIPE2 knockdown were altered by IGF-1 and LY294002 treatments, respectively.

Conclusions

Our findings demonstrate that TIPE2 inhibits PDGF-BB-induced ASMC proliferation, migration, and phenotype switching via the PI3K/Akt signaling pathway. Thus, TIPE2 may be a potential therapeutic target for the treatment of asthma.

Monoclonal Antibody Therapy in Childhood Asthma

PURPOSE OF REVIEW

There has been an explosion of monoclonal antibodies in the treatment of severe uncontrolled adult asthma. Studies have now been published in severe pediatric asthma. There are numerous questions that need to be answered in determining whether these modalities are appropriate and safe in children.

RECENT FINDINGS

This is a narrative review examining the latest pediatric literature on monoclonal antibodies, both approved and in the pipeline, for uncontrolled asthma. Presently, all of the biologics are positioned to treat patients with underlying type 2 high disease. Two monoclonal antibodies are approved for children 6 years of age and older, omalizumab and mepolizumab, with more likely approved in the near future. The effect of these agents in controlling severe pediatric asthma is promising. Data is limited to long-term efficacy and safety, and whether any agent has an effect on the natural history of asthma.

Does allergy explain why some children have severe asthma?

Asthma is a common disease in childhood with a minority of affected children having severe therapy-resistant asthma (STRA). Children with STRA can be differentiated from those with mild-moderate disease by greater allergic sensitization, increased eosinophilic airway inflammation, increased airway remodelling and reduced corticosteroid responsiveness. The aetiology of STRA in children is multifactorial but allergy seems to play a key role. Many children with asthma have coexisting allergic disease, and severe rhinitis seems to be an important driver of STRA in children. Allergies to foods, moulds, pollen and pets have also been associated with severe asthma exacerbations. Identifying allergens that are driving asthma symptoms in children with STRA may provide additional strategies for improving their disease control. Avoidance strategies may be possible. Additional monoclonal antibody therapy with Omalizumab or Mepolizumab may be helpful in children with clinically important polysensitization.

An Update on Anti-IgE Therapy in Pediatric Respiratory Diseases

Anti-IgE treatment represents a major breakthrough in the therapeutic management of severe allergic asthma. Omalizumab is the unique biologic treatment registered for asthma therapy in children. The clinical efficacy and safety of omalizumab treatment in the pediatric population has been extensively documented in specific trials and consistently expanded from real-life studies. In addition, new experimental evidence suggests that omalizumab may also interfere with the cellular and molecular mechanisms underlying airway remodeling. Novel investigational anti-IgE monoclonal antibodies with improved pharmacodynamic properties are in the pipeline, potentially offering alternative mechanisms of modulating IgE pathway.

The aim of this review is to update current knowledge on anti-IgE therapy in pediatric respiratory diseases.

Difficult-to-control asthma: epidemiology and its link with environmental factors

PURPOSE OF REVIEW

The aim of the present review was to discuss the epidemiology of inadequate asthma control with an examination of contributing environmental factors.

RECENT FINDINGS

Despite advances in asthma therapies, a proportion of patients with asthma continue to have difficulty in gaining adequate asthma control. Asthma severity and control in childhood are of particular importance as they translate to asthma morbidity in adulthood. Children with comorbid severe allergic rhinitis were more likely to have uncontrolled asthma. Recent data suggest that mouse allergen, more so than cockroach allergen, may be the most relevant urban allergen exposure. Tobacco smoke exposure, even passive exposure, leads to increased asthma symptoms and decreased response to inhaled corticosteroids. Efforts to ban smoking in public places have resulted in promising asthma results for entire populations. Energy-saving efforts to tighten a home's air leaks can lead to increased indoor pollutant levels and, therefore, must be accompanied by efforts to reduce, filter, or exchange indoor pollutants. Obesity is independently associated with decreased asthma control. Furthermore, the detrimental effects of pollutant exposure are enhanced in an overweight individual with asthma.

SUMMARY

Lack of asthma control can be because of a complex web of factors including adherence, intrinsic factors, and environmental exposures. Further research into intervention strategies is needed to achieve improved rates of asthma control.