Nutritional Interventions to Improve Asthma-Related Outcomes through Immunomodulation: A Systematic Review

Dietary Polyphenols, Plant Metabolites, and Allergic Disorders: A Comprehensive Review

Given the ongoing rise in the occurrence of allergic disorders, alterations in dietary patterns have been proposed as a possible factor contributing to the emergence and progression of these conditions. Currently, there is a significant focus on the development of dietary therapies that utilize natural compounds possessing anti-allergy properties. Dietary polyphenols and plant metabolites have been intensively researched due to their well-documented anti-inflammatory, antioxidant, and immunomodulatory characteristics, making them one of the most prominent natural bioactive chemicals. This study seeks to discuss the in-depth mechanisms by which these molecules may exert anti-allergic effects, namely through their capacity to diminish the allergenicity of proteins, modulate immune responses, and modify the composition of the gut microbiota. However, further investigation is required to fully understand these effects. This paper examines the existing evidence from experimental and clinical studies that supports the idea that different polyphenols, such as catechins, resveratrol, curcumin, quercetin, and others, can reduce allergic inflammation, relieve symptoms of food allergy, asthma, atopic dermatitis, and allergic rhinitis, and prevent the progression of the allergic immune response. In summary, dietary polyphenols and plant metabolites possess significant anti-allergic properties and can be utilized for developing both preventative and therapeutic strategies for targeting allergic conditions. The paper also discusses the constraints in investigating and broad usage of polyphenols, as well as potential avenues for future research.

Plant stanol consumption increases anti-COVID-19 antibody responses, independent of changes in serum cholesterol concentrations: a randomized controlled trial

BACKGROUND

People with overweight/obesity generally have impaired immune responses, resulting among others in increased risk of severe complaints and hospitalization after infections with severe acute respiratory syndrome coronavirus 2 (COVID-19), as well as decreased antibody production after vaccinations. Plant stanol ester previously increased the combined IgM/IgG antibody titers toward a hepatitis A vaccination in patients with allergic asthma, but the underlying mechanism is unknown.

OBJECTIVES

We evaluated whether plant stanol ester consumption improved the immune response in subjects with overweight/obesity after a COVID-19 vaccination.

METHODS

A double-blind, randomized, placebo-controlled trial was performed. Thirty-two subjects with overweight/obesity consumed products with added plant stanols (4 g/d; provided as plant stanol ester) or control ≥2 wk before receiving their COVID-19 vaccination until 4 wk after vaccination. Antibody titers were analyzed weekly and statistically analyzed using mixed models. Serum metabolic markers and cytokine profiles were also analyzed.

RESULTS

IgM concentrations against the COVID-19 Spike protein were increased in the plant stanol ester group compared with the control group, with the largest difference observed 2 wk after vaccination [31.2 (0.43, 62.1) BAU/mL, or +139%; Group × Time: P = 0.031]. Subjects that produced very low IgM antibodies produced, as expected, hardly any IgG antibodies. In those with IgG seroconversion, IgG Spike concentrations were also increased in the plant stanol ester group compared with the control group [71.3 (2.51, 140.1) BAU/mL; Group P = 0.043]. Stimulated cytokine concentrations decreased in the plant stanol ester group compared with the control group in all 3 cytokine domains (that is, proinflammatory, T helper [Th1]/Th17, and Th2/regulatory T cells). Between-group differences in serum LDL cholesterol or other metabolic markers were not observed.

CONCLUSIONS

Consuming plant stanols (4 g/d) affects immune responses to COVID-19 vaccinations, translating into increased serum anti-COVID-19 IgM concentrations in subjects with overweight/obesity. Only in IgG seroconverted subjects, serum anti-COVID-19 IgG concentrations also increase. These effects are independent of reductions in LDL cholesterol. These results suggest that this high-risk group for COVID-19 complications could benefit from plant stanol consumption. This trial was registered at clinicaltrials.gov as NCT04844346.

Non-pharmacological interventions for asthma prevention and management across the life course: Umbrella review

BACKGROUND

The impact of non-pharmacological interventions (NPIs) on asthma prevention and management is insufficiently examined. We aim to comprehensively evaluate and synthesize existing evidence regarding the effectiveness of various NPIs throughout the life course.

METHODS

We conducted a systematic search and screening of reviews that examined the effectiveness of various NPIs on asthma prevention and control in the Cochrane Library, PubMed, Embase, and Ovid databases. Data extraction was performed by considering the type of NPIs and the life course stages of the target population. Recommendations were provided by considering the quality of review assessed using the AMSTAR2 tool and the consistency of findings across reviews.

RESULTS

We identified 145 reviews and mapped the evidence on the impact of 25 subtypes of NPIs on asthma prevention and control based on five stages of life course. Reviews indicated a shift of focus and various impacts of major NPIs on asthma prevention and control across life courses, while a few types of NPIs, such as physical exercise, appeared to be beneficial in children, adolescents and adults. Consistent and high-level evidence was observed only for psychological intervention on asthma control and quality of life among adults and older adults. Potential benefit with high-level evidence was reported on certain NPIs, such as vitamin D in reducing risk of developing asthma in offsprings in the prenatal stage, digital health interventions in improving asthma control from childhood to older adulthood, and breathing exercise in improving quality of life, asthma-related symptoms and lung function in adulthood and older adulthood.

CONCLUSION

This study emphasizes the significance of delivering NPIs to improve asthma prevention and management and highlights the heterogeneity regarding the impact of NPIs across life courses. High-quality research is urgently needed to further strengthen the evidence base of NPIs and tailored interventions should be considered in guideline development.

Effect of dietary interventions on markers of type 2 inflammation in asthma: A systematic review

INTRODUCTION

Type 2 (T2) inflammation is a key mechanism in the pathophysiology of asthma. Diet may have immunomodulatory effects, and a role for diet in T2 inflammation has been suggested in the literature. Indeed, diet and food allergies play a role in children with atopic asthma, but less is known about diet in relation to adult asthma, which is often non-atopic.

OBJECTIVE

To review the effect of dietary interventions on markers of T2 inflammation in adults with asthma.

METHODS

The databases PubMed, Embase, Cochrane Library, and CINAHL were searched for eligible studies until December 2022. We included studies of all types of foods, nutrients, diets or supplements, either as an exposure or as an intervention, in adults and adolescents with asthma. Outcomes of interest included the T2 biomarkers FeNO, eosinophils, IL-4, IL-5, IL-13, eosinophil cationic protein and eosinophil peroxidase. The methodological quality of eligible studies was systematically evaluated, and the results were summarised according to dietary clusters.

RESULTS

The systematic search identified studies on the dietary clusters antioxidants (n = 14), fatty acids, (n = 14), Mediterranean-style diets (n = 5), phytotherapy (n = 7), prebiotics & probiotics (n = 8), vitamin D (n = 7), and other dietary factors (n = 5). Studies within the phytotherapy and omega-3 poly-unsaturated fatty acids (PUFA) clusters showed possible improvements in T2 inflammation. Furthermore, we found little evidence for an effect of antioxidants, prebiotics & probiotics, and Mediterranean-style diets on T2 inflammation. However, heterogeneity in study protocols, methodological shortcomings and limited power of almost all studies make it difficult to fully determine the impact of different dietary approaches on T2 inflammation in asthma.

CONCLUSIONS

Overall, the current evidence does not support a specific dietary intervention to improve T2 inflammation in asthma. Interventions involving phytotherapy and omega-3 PUFA currently have the best evidence and warrant further evaluation in well-designed and adequately powered studies, while taking into account T2-high phenotypes of asthma.

Dietary Inflammatory Index and Clinical Outcome Measures in Adults With Moderate-to-Severe Asthma

BACKGROUND

Diet is increasingly recognized as a modifiable factor in lung health, predominantly due to the immunomodulatory effects of nutrients. The Dietary Inflammatory Index (DII) is a score developed to express the inflammatory potential of a diet.

OBJECTIVE

We aimed to assess the association of the DII and food groups, with clinical, functional, and inflammatory asthma outcomes in adults with asthma.

METHODS

Patients with moderate-to-severe asthma were included in this cross-sectional study between June 2019 and October 2021, and completed a 3-day food diary, to calculate the DII and intake of food groups (ie, fruits, whole grains, processed meats, and sugar-sweetened beverages). Functional outcomes included pulmonary function tests and the 6-minute walking distance, whereas clinical outcomes were assessed using questionnaires on asthma control, quality of life, and health care utilization. Inflammatory markers were exhaled nitric oxide and blood leukocytes, eosinophils, and IL-6. Multivariable regression analyses were used to examine the association of DII and food groups with asthma outcomes.

RESULTS

A total of 109 patients participated (35% male, mean ± standard deviation age 51.8 ± 14.2 years, body mass index 27.4 ± 5.3 kg/m2). Overall, 62% had a DII score >0, indicating a proinflammatory diet, which was not related to asthma severity. A more proinflammatory diet was consistently associated with lower forced vital capacity (%pred), but inconsistent results were observed with respect to airway obstruction. Neither the DII nor food groups were associated with clinical outcomes. Except for higher levels of exhaled nitric oxide in relation to an anti-inflammatory diet, we found no associations between inflammatory markers and the DII.

CONCLUSION

Results from this cross-sectional study among patients with moderate-to-severe asthma do not support the hypothesis that a proinflammatory diet is associated with worse asthma outcomes, although limitations in study design and dietary intake estimation should be considered. Future well-designed experimental studies are needed to assess whether targeting the inflammatory potential of diet could lead to better outcomes in adults with asthma.

Dietary Polyphenols-Natural Bioactive Compounds with Potential for Preventing and Treating Some Allergic Conditions

In light of the constantly increasing prevalence of allergic diseases, changes in dietary patterns have been suggested as a plausible environmental explanation for the development and progression of these diseases. Nowadays, much attention has been paid to the development of dietary interventions using natural substances with anti-allergy activities. In this respect, dietary polyphenols have been studied extensively as one of the most prominent natural bioactive compounds with well-documented anti-inflammatory, antioxidant, and immunomodulatory properties. This review aims to discuss the mechanisms underlying the potential anti-allergic actions of polyphenols related to their ability to reduce protein allergenicity, regulate immune response, and gut microbiome modification; however, these issues need to be elucidated in detail. This paper reviews the current evidence from experimental and clinical studies confirming that various polyphenols such as quercetin, curcumin, resveratrol, catechins, and many others could attenuate allergic inflammation, alleviate the symptoms of food allergy, asthma, and allergic rhinitis, and prevent the development of allergic immune response. Conclusively, dietary polyphenols are endowed with great anti-allergic potential and therefore could be used either for preventive approaches or therapeutic interventions in relation to allergic diseases. Limitations in studying and widespread use of polyphenols as well as future research directions are also discussed.

Relationship between chronic obstructive pulmonary disease and adiponectin concentrations: An updated meta-analysis and single-cell RNA sequencing

BACKGROUND

Adipose tissue, being an organ of the endocrine system, can influence the severity of chronic obstructive pulmonary disease (COPD). Even though several inflammatory markers can potentially significantly influence lung function, the precise function of adipokines, like adiponectin, in COPD is still disputed. To analyze the association of COPD with adiponectin concentrations, a meta-analysis of the most recent literature and single-cell sequencing data were conducted.

METHODS

Studies in Embase, PubMed, Cochrane Library, and Web of Science were browsed to obtain relevant data, which were then assessed with the aid of R 4.1.3 and STATA 11.0 software. Standardized mean differences and correlation coefficients aided the analysis of effect values. Moreover, a single-cell sequencing GSE136831 dataset was retrieved to ascertain the mRNA expression of adiponectin gene (ADIPOQ) in the lung tissue of COPD patients to confirm the difference in the expression of adiponectin between the case and control groups.

RESULTS

This meta-analysis comprised 18 publications involving 24 studies. The overall combined data established the concentration of plasma/serum adiponectin as significantly higher in patients with COPD compared to healthy subjects. Subgroup analyses based on disease status, specimen type, ethnicity, study design method, measurement method, and age of COPD patients demonstrated that all patients with COPD had elevated levels of adiponectin compared to healthy controls. When subgroup analysis was performed for gender alone, the results depicted that male COPD patients had significantly higher adiponectin than healthy males, while female patients of COPD had elevated adiponectin compared to healthy females. Furthermore, it was found that plasma/serum adiponectin appeared to be positively correlated with tumor necrosis factor-α, and it was negatively correlated with FEV1% and FEV1/FVC. The results of single-cell sequencing data suggested that ADIPOQ mRNA was mainly expressed in alveolar epithelial cells, and the level of ADIPOQ mRNA was higher in lung tissues of patients with COPD than in lung tissues of healthy subjects.

CONCLUSION

This meta-analysis suggests that the levels of plasma/serum adiponectin are significantly elevated in patients with COPD versus controls. Tumor necrosis factor-α, FEV1/FVC, and FEV1% may all be associated with the concentrations of adiponectin.

Scorpio and centipede ameliorate asthma by inhibiting the crosstalk between ferroptosis and inflammation in airway epithelial cells

Objectives

We previously revealed that scorpio and centipede (SC) improve the inflammatory response in asthma, whereas it is unclear whether ferroptosis is involved in this process.

Materials and Methods

The asthmatic mouse model was established and lung tissues were collected for histopathological examination. The levels of tumor necrosis factor-α (TNF-α), interleukin- (IL-)1β, Fe2+, malondialdehyde (MDA), glutathione peroxidase 4 (GPX4), ferritin heavy chain 1(FTH1), and reactive oxygen species (ROS) were assessed in asthmatic mice and mouse airway epithelial cells.

Results

Our results showed that ferroptosis was induced in asthmatic mice, as evidenced by the reduction of FTH1 and GPX4 expression and the increase of MDA and Fe2+ levels (all P<0.05). Ferrostatin-1 repressed inflammation and ferroptosis of asthmatic mice. Additionally, SC significantly inhibited the levels of TNF-α, IL-1β, MDA, and Fe2+, while enhancing FTH1 and GPX4 expression. However, SC plus erastin showed the reverse results. Moreover, ferroptosis remarkably increased in asthmatic airway epithelial cells, while SC suppressed ferroptosis of the cells (all P<0.05).

Conclusion

SC ameliorated asthma by inhibiting the crosstalk between ferroptosis and inflammation in airway epithelial cells.

Adipose Tissue Inflammation and Pulmonary Dysfunction in Obesity

Obesity is a chronic disease caused by an excess of adipose tissue that may impair health by altering the functionality of various organs, including the lungs. Excessive deposition of fat in the abdominal area can lead to abnormal positioning of the diaphragm and consequent reduction in lung volume, leading to a heightened demand for ventilation and increased exposure to respiratory diseases, such as chronic obstructive pulmonary disease, asthma, and obstructive sleep apnoea. In addition to mechanical ventilatory constraints, excess fat and ectopic deposition in visceral depots can lead to adipose tissue dysfunction, which promotes metabolic disorders. An altered adipokine-secretion profile from dysfunctional adipose tissue in morbid obesity fosters systemic, low-grade inflammation, impairing pulmonary immune response and promoting airway hyperresponsiveness. A potential target of these adipokines could be the NLRP3 inflammasome, a critical component of the innate immune system, the harmful pro-inflammatory effect of which affects both adipose and lung tissue in obesity. In this review, we will investigate the crosstalk between adipose tissue and the lung in obesity, highlighting the main inflammatory mediators and novel therapeutic targets in preventing pulmonary dysfunction.

Diet, Asthma, and Severe Asthma Exacerbations in a Prospective Study of Puerto Rican Youth

BACKGROUND

Poor diet quality may contribute to the disproportionate asthma burden in Puerto Rican youth.

OBJECTIVE

To examine whether an unhealthy diet at one or two study visits conducted over about 5 years was associated with asthma, severe asthma exacerbations, and worse lung function in Puerto Rican youth.

METHODS

This was a prospective study of 406 Puerto Rican youth aged 6 to 14 years at a baseline visit and 9 to 20 years at a follow-up visit. As in prior work, diet was assessed using a dietary score ranging from -2 to +2. The exposure of interest was an unhealthy diet, defined as a nonpositive dietary score (0 to -2) at one or both visits. Outcomes of interest were asthma (defined as physician-diagnosed asthma and one of more episode of wheeze in the year before the second visit), one or more severe asthma exacerbation in the year before the second visit, and change in percent predicted lung function measures (FEV₁, FVC, and FEV₁/FVC) between the first and second visits.

RESULTS

In a multivariable analysis, an unhealthy diet at both visits was associated with increased odds of asthma (adjusted odds ratio = 3.38; 95% confidence interval, 1.74-6.57) and severe asthma exacerbations (adjusted odds ratio = 2.65; 95% confidence interval, 1.16-6.03), but not with change in lung function.

CONCLUSIONS

An unhealthy diet at both visits was associated with increased odds of asthma and severe asthma exacerbations, compared with a healthy diet at both visits. Our findings support health policies promoting a healthy diet in Puerto Rican youth, a population at high risk for asthma.

Nutrition in Asthma

An emerging body of evidence suggests that diet plays an important role in both the development and management of asthma. The relationship between dietary intake and asthma risk has been explored in epidemiological studies, though intervention trials examining the effects of nutrient intake and dietary patterns on asthma management are scarce. Evidence for diets high in fruits and vegetables, antioxidants, omega-3 fatty acids and soluble fiber such as the Mediterranean diet is conflicting. However, some studies suggest that these diets may reduce the risk of asthma, particularly in young children, and could have positive effects on disease management. In contrast, a Westernized dietary pattern, high in saturated fatty acids, refined grains, and sugars may promote an inflammatory environment resulting in the onset of disease and worsening of asthma outcomes. This review will summarize the state of the evidence for the impact of whole dietary patterns, as well as individual nutrients on the prevalence and management of asthma.

The Relationship Between Vitamin D and Asthma Exacerbation

Asthma is a chronic airway inflammatory condition that affects millions of people worldwide. It presents with reversible bronchoconstriction that makes it difficult for patients to breathe. Asthma flare-ups have several triggers, but the symptoms are similar, including wheezing, coughing, shortness of breath, and chest tightness. Severe asthma exacerbation is described as symptomatic asthma that is unresponsive to inhaled asthma medications and is only responsive to steroids in oral or intravenous forms. Asthma-related deaths occur during episodes of asthma exacerbation. Vitamin D is a steroid-derived vitamin produced by the body and found in some foods. Administration of doses of vitamin D can also help maintain an adequate level of the vitamin. Vitamin D plays a vital role in regulating the level of calcium in the body and bone remodeling processes. It also has an immunomodulatory effect on innate and adaptive immunity within the body and that partially explains its links to inflammation-induced epithelial changes seen in asthma. We conducted this literature review by selecting articles from PubMed and Cumulated Index to Nursing and Allied Health Literature (CINAHL) Plus databases to investigate the relationship between vitamin D level and asthma exacerbation. From the studies, we found that asthmatic patients have low vitamin D levels during an asthma exacerbation. However, supplementing vitamin D may not reduce the rates of asthma exacerbation except in adult asthmatic patients with low levels of vitamin D.