Viral infections in wheezing disorders

Promising Immunomodulatory Effects of Bacterial Lysates in Allergic Diseases

In light of an escalating prevalence of allergic disorders, it is crucial to fully comprehend their pathophysiology and etiology. Such knowledge would play a pivotal role in the search for new therapeutic approaches concerning not only diseases' symptoms, but also their underlying causes. The hygiene hypothesis indicates a high correlation between limited exposure to pathogens in early childhood and the risk of developing allergic disorders. Bearing in mind the significance of respiratory and digestive systems' mucous membrane's first-line exposure to pathogens as well as its implications on the host's immune response, a therapy targeted at aforesaid membranes could guarantee promising and extensive treatment outcomes. Recent years yielded valuable information about bacterial lysates (BLs) known for having immunomodulatory properties. They consist of antigen mixtures obtained through lysis of bacteria which are the most common etiologic agents of respiratory tract infections. They interact with dendritic cells located in the mucous membranes of the upper respiratory tract and the gastrointestinal tract by toll-like receptors. The dendritic cells present acquired antigens resulting in innate immune response development on the release of chemokines, both stimulating monocytes and NK cells maturation and promoting polymorphonuclear neutrophil migration. Moreover, they influence the adaptive immune system by stimulating an increase of specific antibodies against administered bacterial antigens. The significance of BLs includes not only an anti-inflammatory effect on local infections but also restoration of Th1/Th2 balance, as demonstrated mainly in animal models. They decrease Th2-related cytokine levels (IL-4, IL-13) and increase Th1-related cytokine levels (IFN-γ). The reestablishment of the balance of the immune response leads to lowering atopic reactions incidence which, in addition to reduced risk of inflammation, provides the alleviation and improvement of clinical manifestations of allergic disorders. In this review, we hereby describe mechanisms of BLs action, considering their significant immunomodulatory role in innate immunity. The correlation between local, innate, and adaptive immune responses and their impact on the clinical course of allergic disorders are discussed as well. To conclude our review, we present up-to-date literature regarding the outcomes of BLs implemented in atopic dermatitis, allergic rhinitis, and asthma prevention and treatment, especially in children.

Trained immunity induction by the inactivated mucosal vaccine MV130 protects against experimental viral respiratory infections

MV130 is an inactivated polybacterial mucosal vaccine that confers protection to patients against recurrent respiratory infections, including those of viral etiology. However, its mechanism of action remains poorly understood. Here, we find that intranasal prophylaxis with MV130 modulates the lung immune landscape and provides long-term heterologous protection against viral respiratory infections in mice. Intranasal administration of MV130 provides protection against systemic candidiasis in wild-type and Rag1-deficient mice lacking functional lymphocytes, indicative of innate immune-mediated protection. Moreover, pharmacological inhibition of trained immunity with metformin abrogates the protection conferred by MV130 against influenza A virus respiratory infection. MV130 induces reprogramming of both mouse bone marrow progenitor cells and in vitro human monocytes, promoting an enhanced cytokine production that relies on a metabolic shift. Our results unveil that the mucosal administration of a fully inactivated bacterial vaccine provides protection against viral infections by a mechanism associated with the induction of trained immunity.

Can bacterial lysates be useful in prevention of viral respiratory infections in childhood? The results of experimental OM-85 studies

Respiratory tract infections (RTI) are mainly viral in origin and among the leading cause of childhood morbidity globally. Associated wheezing illness and asthma are still a clear unmet medical need. Despite the continuous progress in understanding the processes involved in their pathogenesis, preventive measures and treatments failed to demonstrate any significant disease-modifying effect. However, in the last decades it was understood that early-life exposure to microbes, may reduce the risk of infectious and allergic disorders, increasing the immune response efficacy. These results suggested that treatment with bacterial lysates (BLs) acting on gut microbiota, could promote a heterologous immunomodulation useful in the prevention of recurrent RTIs and of wheezing inception and persistence. This hypothesis has been supported by clinical and experimental studies showing the reduction of RTI frequency and severity in childhood after oral BL prophylaxis and elucidating the involved mechanisms. OM-85 is the product whose anti-viral effects have been most extensively studied in vitro, animal, and human cell studies and in translational animal infection/disease models. The results of the latter studies, describing the potential immune training-based activities of such BL, leading to the protection against respiratory viruses, will be reported. In response to human rhinovirus, influenza virus, respiratory syncytial virus and severe acute respiratory coronavirus-2, OM-85 was effective in modulating the structure and the functions of a large numbers of airways epithelial and immune cells, when administered both orally and intranasally.

Childhood asthma : factors predicting severity and persistence of symptoms

BACKGROUND

Asthma is the most common chronic disease in infants. In young children, asthma still raises many questions and many points are still being debated.

AIM

The aim of this study is to identifies, in asthmatic children, factors predictors of severity and persistence of symptoms.

METHODS

A retrospective study of asthmatic infants<3 years enrolled in the pediatric department of Sfax over a period of 5 years (2007-2011). We were interested to social and environmental factors, the allergic background, clinical severity of the disease, results of allergic skin tests, treatment and respiratory outcome.

RESULTS

We collected 180 children with a sex ratio of 2.2. Family history of atopy and exposition to passive tobacco were noted in 45 % and 52% of cases respectively. The mean age of onset of wheezing was 6.6 months. Skin tests were positives in 32% of cases. At the time of diagnosis, asthma was classified intermittent (21%), mild to moderate (55.6%) and severe (22.2%).  Inhaled corticosteroids was initiated in 142 infants (78.8%). Skin tests performed in 84 patients, were positive in 32%. Factors associated with severe asthma were passive smoking, early age of onset, number of hospitalizations for exacerbation and existence of an aggravating factor. Factors predictors of persistence were an early age of onset, caesarean delivery, passive smoking and positive skin tests.

CONCLUSION

Factors associated with persistence of asthma at the individual level remains uncertain. However, atopy and passive smoking are major indicators.

Respiratory syncytial virus and airway microbiota - A complex interplay and its reflection on morbidity

The immunopathology of respiratory syncytial virus (RSV) infection varies considerably, severe disease occurring only in a minority of the affected children. The variability of the clinical presentation is in part explained by viral and environmental factors but, in infants and young children, disease severity is certainly linked to the physiologic immaturity of the innate and adaptive immune system. There is evidence that the maturation of the host immune response is positively influenced by the composition of the nasopharyngeal microbiome that, promoting an efficient reaction, can counteract the predisposition to develop viral respiratory infections and lower the risk of disease severity. However, interaction between the nasopharyngeal microbiota and respiratory viruses can be bidirectional since microbial dysbiosis may also represent a reflection of the disease-induced alterations of the local milieu. Moreover, viruses like RSV can also increase the virulence of potential pathogens in nasopharynx, a main reservoir of bacteria, and therefore promote their spread to the lower airways causing superinfection. Moreover, if negative changes in microbial community composition in early life may constitute a heightened risk toward severe RSV respiratory infection, on the contrary specific groups of microorganisms seem to be associated with protection. A better understanding into the potential negative and positive role of the different nasopharyngeal bacterial species on RSV infection may improve primary prevention and possibly care of this highly contagious disorder.

Bacterial lysate add-on therapy to reduce exacerbations in severe asthma: A double-blind placebo-controlled trial

Background

Asthma exacerbations are frequently induced by respiratory tract infections (RTIs). Bacterial lysates have been described to possess immune‐modulatory effects and reduce RTIs as well as asthma symptoms in children. However, whether bacterial lysates have similar effects in adult asthma patients is unknown.

Aims

To reduce asthma exacerbations by add‐on bacterial lysate therapy in adults with severe asthma and to characterize the clinical and immune‐modulatory effects of this treatment.

Methods

Asthma patients (GINA 4) with ≥2 annual exacerbations in the previous year were included. The intervention regimen consisted of OM‐85/placebo for 10 consecutive days per month for 6 months during two winter seasons. Primary end‐point was the number of severe asthma exacerbations within 18 months. The study was approved by the national and local ethical review board and registered in the Dutch Trial Registry (NL5752). All participants provided written informed consent.

Results

Seventy‐five participants were included (38 OM‐85; 37 placebo). Exacerbation frequencies were not different between the groups after 18 months (incidence rate ratio 1.07, 95%CI [0.68–1.69], p = 0.77). With the use of OM‐85, FEV1% increased by 3.81% (p = 0.04) compared with placebo. Nasopharyngeal swabs taken during RTIs detected a virus less frequently in patients using OM‐85 compared to placebo (30.5% vs. 48.0%, p = 0.02).

In subjects with type 2 inflammation adherent to the protocol (22 OM‐85; 20 placebo), a non‐statistically significant decrease in exacerbations in the OM‐85 group was observed (IRR = 0.71, 95%CI [0.39–1.26], p = 0.25). Immune‐modulatory effects included an increase in several plasma cytokines in the OM‐85 group, especially IL‐10 and interferons. Peripheral blood T‐ and B cell subtyping, including regulatory T cells, did not show differences between the groups.

Conclusion

Although OM‐85 may have immune‐modulatory effects, it did not reduce asthma exacerbations in this heterogeneous severe adult asthma group. Post hoc analysis showed a potential clinical benefit in patients with type 2 inflammation.

Upregulation of neuropeptides and obstructive airway disorder in infancy: A review with focus on post-RSV wheezing and NEHI

Obstructive airway disorders, common in infancy and early childhood, include some entities that are recognized to have neuro immune mediators as their underlying pathogenetic mechanisms. The best characterized example amongst post-viral wheezing phenotypes is the disorder that follows respiratory syncytial virus (RSV) infection and leads to intermittent, long-term wheezing. The underlying mechanisms of the airway reactivity related to RSV infection have been extensively studies and are associated with dysregulation of the nonadrenergic-noncholinergic (NANC) system, via upregulation of neurotransmitters, typically Substance P. Neuroendocrine hyperplasia of infancy (NEHI), while a less common entity, is a disorder characterized by more severe and long-term obstructive airway disease. NEHI is pathophysiologically characterized by abundance of neuroendocrine cells in the airways containing the neuroimmune mediator bombesin, the release of which is presumed to be the driver of the persistent small airway obstruction and functional air-trapping. Here we review the NANC and neuroendocrine cells, the neurotransmitter systems and their studied roles in pulmonary diseases with a focus on their role in lung development, and subsequent various pediatric lung diseases. We focus on the juxtaposition of the separate neuroimmune mechanisms underlying the pathogenesis of post-RSV recurrent wheezing and NEHI's persistent small airway obstruction. We finally propose a unifying concept of neuropeptides in obstructive disorders that may encompass these two entities and possibly others.

Distinct Antiviral Properties of Two Different Bacterial Lysates

Oral bacterial lysates (OBLs) can reduce the frequency and severity of recurrent respiratory tract infections in children from viral and bacterial origins. OBL-induced early innate immune reaction was already shown, but the specific features of different OBLs have never been studied and compared. A study was conducted to assess in vitro the protective effects on rhinovirus- (RV-) infected human bronchial epithelial cells (BECs) of two slightly different OBLs: OM-85 and Pulmonarom. Furthermore, since immune cells represent the key arm for antiviral defence, the capacity of these OBLs to induce selected cytokine production in mouse bone marrow-derived DCs (BMDCs) was also evaluated. Although different OBLs may share some mechanisms to protect host cells from virus infection, some product-specific antimicrobial activities were observed on RV-infected human BECs and mouse BMDCs. These results are consistent with a product-specific response possibly triggered by different pathogen-associated molecular patterns (PAMPs) contained in OBLs.

Bacterial lysate therapy for the prevention of wheezing episodes and asthma exacerbations: a systematic review and meta-analysis

Wheezing and asthma are a growing cause of morbidity in children and adults. Treatment is aimed at prevention of disease exacerbations and preservation of lung function. Respiratory viruses are involved in ∼40-60% of exacerbations. Bacterial lysates prevent recurrent respiratory tract infections and might reduce exacerbations. Moreover, immunomodulatory effects have been observed in human and animal studies. Here we aimed to assess the effects of bacterial lysate therapy on preschool wheezing episodes and asthma exacerbation frequency. We performed a systematic literature review based on the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) statement and a meta-analysis using Cochrane Review Manager. Out of 2016 retrieved articles, 22 studies were included, of which five provided sufficient data for a meta-analysis.The use of bacterial lysates showed a decrease of both wheezing episodes (mean difference -2.35 (-3.03- -1.67), p<0.001) and asthma exacerbations in children (mean difference -0.90 (-1.23- -0.57), p<0.001). Additionally, antibiotic use was reduced, and the duration of wheezing episodes was also decreased. No data for adults with asthma are currently available. The immunomodulatory effect seems to be dependent on increased T-helper (Th)1-cell activation and Th2-cell suppression.These favourable effects of bacterial lysates indicate that they show promise as add-on therapy in preschool wheezing and childhood asthma.

Viral infections and wheezing-asthma inception in childhood: is there a role for immunomodulation by oral bacterial lysates?

Severe and recurrent infections of the respiratory tract in early childhood constitute major risk factors for the development of bronchial hyper-responsiveness and obstructive respiratory diseases in later life. In the first years of life, the vast majority of respiratory tract infections (RTI) leading to wheezing and asthma are of a viral origin and severity and recurrence are the consequence of a greater exposure to infectious agents in a period when the immune system is still relatively immature. Therefore, boosting the efficiency of the host immune response against viral infections seems to be a rational preventative approach. In the last decades it has been demonstrated that living in farm environments, i.e. early-life exposure to microbes, may reduce the risk of allergic and infectious disorders, increasing the immune response efficacy. These findings have suggested that treatment with bacterial lysates could promote a nonspecific immunomodulation useful in the prevention of recurrent RTIs and of wheezing inception and persistence. Experimental and clinical studies showing the reduction of RTI frequency and severity in childhood and elucidating the involved mechanisms can support this hypothesis.

Rhinovirus Type in Severe Bronchiolitis and the Development of Asthma

Background

Respiratory syncytial virus (RSV)- and rhinovirus (RV)-induced bronchiolitis are associated with an increased risk of asthma, but more detailed information is needed on virus types.

Objective

To study whether RSV or RV types are differentially associated with the future use of asthma control medication.

Methods

Over 2 consecutive winter seasons (2008-2010), we enrolled 408 children hospitalized for bronchiolitis at age less than 24 months into a prospective, 3-center, 4-year follow-up study in Finland. Virus detection was performed by real-time reverse transcription PCR from nasal wash samples. Four years later, we examined current use of asthma control medication.

Results

A total of 349 (86%) children completed the 4-year follow-up. At study entry, the median age was 7.5 months, and 42% had RSV, 29% RV, 2% both RSV and RV, and 27% non-RSV/-RV etiology. The children with RV-A (adjusted hazard ratio, 2.3; P = .01), RV-C (adjusted hazard ratio, 3.5; P < .001), and non-RSV/-RV (adjusted hazard ratio, 2.0; P = .004) bronchiolitis started the asthma control medication earlier than did children with RSV bronchiolitis. Four years later, 27% of patients used asthma control medication; both RV-A (adjusted odds ratio, 3.0; P = .03) and RV-C (adjusted odds ratio, 3.7; P < .001) etiology were associated with the current use of asthma medication. The highest risk was found among patients with RV-C, atopic dermatitis, and fever (adjusted odds ratio, 5.0; P = .03).

Conclusions

Severe bronchiolitis caused by RV-A and RV-C was associated with earlier initiation and prolonged use of asthma control medication. The risk was especially high when bronchiolitis was associated with RV-C, atopic dermatitis, and fever.

Risk factors and prognosis of recurrent wheezing in Chinese young children: a prospective cohort study

Background

Nearly all the investigations into the risk factors for wheezing and asthma were conducted in developed countries with a high prevalence rate of asthma and allergy, but the studies in developing countries are limited. In this study, we aimed to investigate the risk factors for different wheezing phenotypes in Chinese young children and to explore the prognosis of recurrent wheezing.

Methods

This cohort study contained the recruitment stage and the follow-up stage conducted by phone questionnaire survey. According to the information collected at the follow-up for wheezing episodes and remission age, our cohort was divided into transient wheezing, persistent wheezing and late-onset wheezing. The wheezing symptoms and potential risk factors were compared between these three wheezing groups.

Results

From the initial 109 participants, 78.0% completed the follow-up survey. The frequency of current wheezing at followup was significantly reduced in all three groups compared to the recruitment stage (p < 0.01). We observe a trend that the rhinovirus (RV) and respiratory syncytial virus (RSV) infection rates were higher in the persistent wheezing group, and the overall infection rates appear to be the lowest in late-onset wheezing group at recruitment. At follow-up stage, the rates of rhinitis ever and current rhinitis were both higher in the persistent wheezing (63.0%, 50.0%) and late-onset wheezing groups (88.2%, 58.8%), compared to the transient wheezing group (14.3%, 14.3%). The incidence of current wheezing episodes increased cumulatively if the participant had concomitant risk factors of rhinitis ever, aeroallergens sensitization at recruitment, either alone or together with previous RV infection at the time of recruitment.

Conclusion

While the incidence of wheezing declined overall with age, but in addition to transient wheezers, additional subsets of children manifest persistent wheeze or late onset wheeze, and moreover the risk factors for wheezing display phenotypic variability between these subgroups. Rhinitis ever and aeroallergens sensitization, either alone or together with previous RV infection, were the most significant predictors for persistent wheezing in children in an eastern environment, such as in China.

An update on paediatric respiratory diseases

During the 2017 European Respiratory Society International Congress in Milan, Italy, exciting topics on childhood lung disease were reviewed in the session “Paediatric year in review: update on paediatric pulmonology”. These brief reviews highlighted publications in the field of paediatric lung disease and were presented by well-known experts within the field.

An update of paediatric lung diseases including interstitial lung disease, virus causing wheezing disorders and diaphragmatic hernia together with new imaging diagnosis toolshttp://ow.ly/TclX30iZazK