Gastroesophageal reflux-associated aspiration alters the immune response in asthma

Effects of biological therapies on patients with Type-2 high asthma and comorbid obesity

Over 20 million adults and 6 million children in the United States (US) have asthma, a chronic respiratory disease characterized by airway inflammation, bronchoconstriction, and mucus hypersecretion. Obesity, another highly prevalent disease in the US, is a major risk factor for asthma and a significant cause of diminished asthma control, increased submucosal eosinophilia, and reduced quality of life. A large subgroup of these patients experiences severe symptoms and recurrent exacerbations despite maximal dosage of standard asthma therapies. In the past two decades, the development of biological therapies has revolutionized the field and advanced our understanding of type 2 inflammatory biomarkers. However, patients with obesity and comorbid asthma are not principally considered in clinical trials of biologics. Large landmark cluster analyses of patients with asthma have consistently identified specific asthma phenotypes that associate with obesity but may be differentiated by age of asthma onset and inflammatory cell profiles in sputum. These patterns suggest that biologic processes driving asthma pathology are heterogenous among patients with obesity. The biological mechanisms driving pathology in patients with asthma and comorbid obesity are not well understood and likely multifactorial. Future research needs to be done to elicit the cellular and metabolic functions in the relationship of obesity and asthma to yield the best treatment options for this multiplex condition. In this review, we explore the key features of type 2 inflammation in asthma and discuss the effectiveness, safety profile, and research gaps regarding the currently approved biological therapies in asthma patients with obesity.

Vulnerability to acid reflux of the airway epithelium in severe asthma

BACKGROUND

Severe asthma is associated with multiple co-morbidities, including gastro-oesophageal reflux disease (GORD) which can contribute to exacerbation frequency and poor quality of life. Since epithelial dysfunction is an important feature in asthma, we hypothesised that in severe asthma the bronchial epithelium is more susceptible to the effects of acid reflux.

METHODS

We developed an in vitro model of GORD using differentiated bronchial epithelial cells (BECs) from normal or severe asthmatic donors exposed to a combination of pepsin, acid pH, and bile acids using a multiple challenge protocol (MCP-PAB). We also analysed bronchial biopsies and undertook RNA-sequencing of bronchial brushings from controls and severe asthmatics without or with GORD.

RESULTS

Exposure of BECs to the MCP-PAB caused structural disruption, increased permeability, IL-33 expression, inflammatory mediator release and changes in gene expression for multiple biological processes. Cultures from severe asthmatics were significantly more affected than those from healthy donors. Analysis of bronchial biopsies confirmed increased IL-33 expression in severe asthmatics with GORD. RNA-sequencing of bronchial brushings from this group identified 15 of the top 37 dysregulated genes found in MCP-PAB treated BECs, including genes involved in oxidative stress responses.

CONCLUSIONS

By affecting epithelial permeability, GORD may increase exposure of the airway submucosa to allergens and pathogens, resulting in increased risk of inflammation and exacerbations.

CLINICAL IMPLICATION

These results suggest the need for research into alternative therapeutic management of GORD in severe asthma.

Associations between the severity of reflux esophagitis in children and changes in oxidative stress, serum inflammation, vasoactive intestinal peptide and motilin

Changes in the levels of serum oxidative stress indexes, gastrointestinal hormones and inflammatory factors in children with different severity of reflux esophagitis (RE) were detected. Sixty child patients diagnosed with gastroesophageal reflux disease (GERD) via gastroscopy were selected and divided into non-erosive reflux disease group (NERD group, n=12) and RE group (n=48) according to whether there was esophageal mucosal injury. In RE group, the patients were further divided into grade I RE group (n=15), grade II RE group (n=18) and grade III RE group (n=15) based on the severity of mucosal injury. None of the child patients took PPI and domperidone within 2 weeks before enrollment. The content of malondialdehyde (MDA) and total superoxide dismutase (T-SOD) in the esophageal mucosa was detected. The changes in the levels of serum vasoactive intestinal peptide (VIP), motilin, interleukin-1β (IL-1β), IL-8 and tumor necrosis factor-α (TNF-α) were determined. The DeMeester score was the highest in grade III RE group, followed by grade II RE group, grade I RE group and NERD group (P<0.05). The content of MDA in the esophageal mucosa was higher in RE group than that in NERD group, and the T-SOD activity declined with the increased severity of injury (P<0.05). In the three RE groups, the level of plasma VIP was significantly higher, while the motilin level was remarkably lower than those in NERD group (P<0.05). With the increased severity of disease, the expression levels of serum IL-1β, IL-8 and TNF-α in RE group were gradually raised (P<0.05). RE patients have strong oxidative stress and inflammatory response, an increased level of serum VIP, a regulator of gastrointestinal motility, and a decreased level of motilin. Controlling the changes in the above factors using effective treatment means can improve the development of GERD.

Asthma: Diagnosis and Treatment

Asthma is an obstructive lung disease affecting >230 million people worldwide and a significant cause of morbidity in patients of all ages. It is a heterogeneous disease with a complex pathophysiology and phenotype. Diagnosis is made with thorough history-taking and physical examination, and the condition is characterised by variable airflow obstruction and airway hyper-responsiveness. Understanding the severity of the disease is important, and treatment is aimed at symptom control and the prevention of future exacerbations. Pharmacologic treatment with beta-agonists for intermittent asthma and inhaled corticosteroids and a combination of inhaled corticosteroids and long-acting beta-2 agonists for persistent asthma are recommended. Additional and alternative treatments with leukotriene modifiers, anticholinergics, biologics, and bronchial thermoplasty are also available. However, understanding an individual’s disease phenotype, endotype, and comorbidities is necessary for asthma treatment, with appropriate consultation with asthma specialists required for those with severe asthma.

Murine model of oropharyngeal gastric fluid aspiration-A new assessment method for intrapulmonary liquid distribution using digital pixel calculation

AIM OF THE STUDY

The aim of this study was to investigate a new method for visualization and quantification of intrapulmonary liquid distribution after oropharyngeal gastric fluid aspiration in mice.

MATERIAL AND METHODS

Eleven mice received oropharyngeal aspiration with a gastric fluid, India ink, and saline solution. Digital imaging and pixel calculation were used to analyze intrapulmonary fluid distribution selectively.

RESULTS

Digital pixel analysis and orophanryngeal aspiration are both safe techniques in mice and deliver reproducible/valid results. Analysis revealed an average aspirate distribution of 86.8% of the total lung area. The proportional amount of the left lung was significantly greater than that of the right lung (P = 0.023). The lobe with the lowest mean distribution was the right lower lobe (79.2% ± 4.4%).

CONCLUSION

Digital pixel calculation is a reliable method for quantitative, macroscopic evaluation of fluid distribution in the lung. This method is a useful tool for training purposes and it can be used to ensure interinvestigator reproducibility.

Gastroesophageal Reflux in the Intensive Care Unit Patient

The incidence of gastroesophageal reflux disease (GERD) in the critically ill patient in the intensive care unit is unknown. Interventions used in critically ill patients, such as sedation, tracheal tubes, mechanical ventilation, enteral feedings, positioning, and medications, along with specific patient characteristics and comorbid conditions contribute to an increased risk for gastroesophageal reflux (GER) in this population. Critical care nurses have an integral role in helping identify critically ill patients at risk for GER or with known GERD, in preventing complications associated with these conditions.

A preliminary investigation of laparoscopic fundoplication treatment on gastroesophageal reflux disease-related respiratory symptoms

BACKGROUND

Extraesophageal syndromes are more difficult to identify and treat than the usual esophageal symptoms. The current study explores the efficacy of laparoscopic Nissen fundoplication (LNF) on gastroesophageal reflux disease (GERD)-related respiratory symptoms (RSs) during a 12-month follow-up observation.

METHODS

From April 2008 to September 2009, LNF was performed on 198 patients (107 men and 91 women) with GERD-related RSs according to underlying esophageal motility. A questionnaire form ranging from 0 to 5 was the basic requirement for recording pretreatment and posttreatment and for making detailed evaluation of the symptoms. All scores of GERD-related RSs, such as heartburn, regurgitation, coughing, breathe holding, wheezing, shortness of breath, and choking, significantly decreased at the 12th month.

RESULTS

All the patients who participated in the current study were adults and elders aged 22 to 84 years with a mean age of 49 ± 12.89. The median length of stay was 4.3 days with a range of 2 to 8 days. The median score of heartburn, regurgitation, coughing, wheezing, shortness of breath, choking, and chest pain decreased from 4.92 ± 1.99, 4.98 ± 1.81, 7.23 ± 1.87, 7.50 ± 1.88, 5.83 ± 2.13, 5.94 ± 2.22, and 4.92 ± 1.88 to 1.62 ± 2.33, 0.64 ± 1.43, 2.79 ± 2.82, 2.53 ± 2.96, 1.37 ± 2.10, 1.28 ± 2.09, and 1.57 ± 2.55 (P<0.01), respectively. A total of 173 patients had various relieved symptom scores, 16 patients (8.1%) had different scale recurrence of symptoms after laparoscopic fundoplication treatment, and 13 patients had to retreat to omeprazole as an auxiliary medical therapy. Three other patients rejected any therapy, and no deaths occurred. A single patient converted from laparoscopic surgery to open surgery. Several short-term symptoms included retrosternal uneasiness or pain (n = 63; 31.8%), dysphagia (n = 45; 22.7%), abdominal distension (n = 87; 43.9%), and diarrhea (n = 23; 11.6%). Early dysphagia lasting <6 weeks was common, and 45 patients (22.7%) underwent an early esophagogastroduodenoscopy or contrast swallow. Five patients (2.5%) who had prolonged dysphagia during the 6-month clinical review required esophageal dilatation, and the outcomes were successful.

CONCLUSIONS

LNF can be an effective means for treating RSs in patients with GERD.

Chronic aspiration shifts the immune response from adaptive immunity to innate immunity in a murine model of asthma

OBJECTIVE AND DESIGN

The hypothesis that aspiration of gastric fluid drives the anti-ovalbumin response toward a Th2 reaction even in animals not prone to Th2 responses was evaluated.

SUBJECTS

Forty-eight male C57BL/6 mice were used.

METHODS

Mice were sensitized and challenged with ovalbumin starting 5 weeks prior to the initiation of weekly aspirations of either gastric fluid or normal saline as a control. Weekly aspiration continued during the course of exposure to ovalbumin.

TREATMENT

Aspiration consisted of 50 μl of gastric fluid with 50 μl of 0.9 % normal saline used as a control. Antigen exposure consisted of sensitization to ovalbumin via intraperitoneal injection on days 0 and 14 and challenge on day 21 with aerosolized antigen for 30 min.

RESULTS

No evidence of a shift toward a Th2 response as a result of gastric fluid aspiration was seen in the Th1-prone strain utilized, although a profound down-regulation of a broad array of T cell-associated cytokines and chemokines and up-regulation of macrophage-associated markers was observed as a result of aspiration.

CONCLUSIONS

These data provide support for the hypothesis that the clinical association between asthma and gastroesophageal reflux disease (GERD) does not involve an exacerbation of asthma by GERD-associated aspiration of gastric fluid, but may cause immune reactions unrelated to the asthma pathology.