Effect of nasal allergen challenge in allergic rhinitis on mitochondrial function of peripheral blood mononuclear cells

Distinct mitochondrial respiration profiles in pediatric patients with febrile illness versus sepsis

OBJECTIVE

Mitochondrial dysfunction, linked to sepsis-related organ failure, is unknown in febrile illness.

METHODS

Prospective study of children in an Emergency Department (ED) with febrile illness or without infection (ED controls); secondary analysis of ICU patients with sepsis or without infection (ICU controls). Mitochondrial oxygen consumption measured in peripheral blood mononuclear cells using respirometry, with primary outcome of spare respiratory capacity (SRC). Mitochondrial content measured as citrate synthase (CS: febrile illness and ED controls) and mitochondrial to nuclear DNA ratio (mtDNA:nDNA: all groups).

RESULTS

SRC was lower in febrile illness (6.7 ± 3.0 pmol/sec/106 cells) and sepsis (5.7 ± 4.7) than ED/PICU controls (8.5 ± 3.7; both p < 0.05), but not different between febrile illness and sepsis (p = 0.26). Low SRC was driven by increased basal respiration in febrile illness and decreased maximal uncoupled respiration in sepsis. Differences were no longer significant after adjustment for patient demographics. Febrile illness demonstrated lower CS activity than ED controls (p = 0.07) and lower mtDNA:nDNA than both ED/PICU controls and sepsis (both p < 0.05).

CONCLUSION

Mitochondrial SRC was reduced in both febrile illness and sepsis, but due to distinct mitochondrial profiles and impacted by demographics. Further work is needed to determine if mitochondrial profiles could differentiate febrile illness from early sepsis.

IMPACT STATEMENT

Mitochondrial dysfunction has been linked to organ failure in sepsis, but whether mitochondrial alterations are evident in febrile illness without sepsis is unknown. In our study, while mitochondrial spare respiratory capacity (SRC), an index of cellular bioenergetic reserve under stress, was reduced in children with both febrile illness and sepsis compared to children without infections, low SRC was driven by increased basal respiration in febrile illness compared with decreased maximal uncoupled respiration in sepsis. Additional research is needed to understand if distinct mitochondrial profiles could be used to differentiate febrile illness from early sepsis in children.

Two-stage association study of mitochondrial DNA variants in allergic rhinitis

BACKGROUND

Correlations between mitochondrial DNA (mtDNA) and allergic rhinitis (AR) have not been reported before. This study aimed to better understand the mitochondrial genome profile with AR and to investigate the associations between AR in China and the mitochondrial genome at a single variant and gene level.

METHODS

Mitochondrial sequencing was conducted on a total of 134 unrelated individual subjects (68 patients with AR, 66 healthy controls) at discovery stage. Heteroplasmy was analyzed using the Mann-Whitney U test. Sequence kernel association tests (SKAT) were conducted to study the association between mitochondrial genes and AR. Single-variant analysis was performed using logistic regression analysis and further validated in 120 subjects (69 patients with AR, 51 healthy controls). Candidate genes were further explored based on differences in mRNA and protein abundance in nasal mucosal tissue.

RESULTS

In the discovery stage, 886 variants, including 836 SNV and 50 indels, were identified with mitochondrial sequencing. No statistically significant differences were identified for the mitochondrial heteroplasmy or SKAT analysis between these two groups after applying a Boferroni correction. One nonsynonymous variants, rs3135028 (MT8584.G/A) in ATP6, was related to a reduced risk of AR in both the discovery and validation cohorts. Furthermore, mRNA levels of MT-ATP6 in nasal mucosal tissue were significantly lower in AR individuals than in controls (P < 0.05).

CONCLUSIONS

In a two-stage analysis of associations between AR and mtDNA variations, mitochondrial gene maps of Chinese patients with AR indicated that the ATP6 gene was probably associated with AR at the single-variant level.

The human milk proteome and allergy of mother and child: Exploring associations with protein abundances and protein network connectivity

Background

The human milk proteome comprises a vast number of proteins with immunomodulatory functions, but it is not clear how this relates to allergy of the mother or allergy development in the breastfed infant. This study aimed to explore the relation between the human milk proteome and allergy of both mother and child.

Methods

Proteins were analyzed in milk samples from a subset of 300 mother-child dyads from the Canadian CHILD Cohort Study, selected based on maternal and child allergy phenotypes. For this selection, the definition of "allergy" included food allergy, eczema, allergic rhinitis, and asthma. Proteins were analyzed with non-targeted shotgun proteomics using filter-aided sample preparation (FASP) and nanoLC-Orbitrap-MS/MS. Protein abundances, based on label-free quantification, were compared using multiple statistical approaches, including univariate, multivariate, and network analyses.

Results

Using univariate analysis, we observed a trend that milk for infants who develop an allergy by 3 years of age contains higher abundances of immunoglobulin chains, irrespective of the allergy status of the mother. This observation suggests a difference in the milk's immunological potential, which might be related to the development of the infant's immune system. Furthermore, network analysis showed overall increased connectivity of proteins in the milk of allergic mothers and milk for infants who ultimately develop an allergy. This difference in connectivity was especially noted for proteins involved in the protein translation machinery and may be due to the physiological status of the mother, which is reflected in the interconnectedness of proteins in her milk. In addition, it was shown that network analysis complements the other methods for data analysis by revealing complex associations between the milk proteome and mother-child allergy status.

Conclusion

Together, these findings give new insights into how the human milk proteome, through differences in the abundance of individual proteins and protein-protein associations, relates to the allergy status of mother and child. In addition, these results inspire new research directions into the complex interplay of the mother-milk-infant triad and allergy.

Butyrate as a bioactive human milk protective component against food allergy

BACKGROUND

Food allergy (FA) is a growing health problem worldwide. Effective strategies are advocated to limit the disease burden. Human milk (HM) could be considered as a protective factor against FA, but its mechanisms remain unclear. Butyrate is a gut microbiota-derived metabolite able to exert several immunomodulatory functions. We aimed to define the butyrate concentration in HM, and to see whether the butyrate concentration detected in HM is able to modulate the mechanisms of immune tolerance.

METHODS

HM butyrate concentration from 109 healthy women was assessed by GS-MS. The effect of HM butyrate on tolerogenic mechanisms was assessed in in vivo and in vitro models.

RESULTS

The median butyrate concentration in mature HM was 0.75 mM. This butyrate concentration was responsible for the maximum modulatory effects observed in all experimental models evaluated in this study. Data from mouse model show that in basal condition, butyrate up-regulated the expression of several biomarkers of gut barrier integrity, and of tolerogenic cytokines. Pretreatment with butyrate significantly reduced allergic response in three animal models of FA, with a stimulation of tolerogenic cytokines, inhibition of Th2 cytokines production and a modulation of oxidative stress. Data from human cell models show that butyrate stimulated human beta defensin-3, mucus components and tight junctions expression in human enterocytes, and IL-10, IFN-γ and FoxP3 expression through epigenetic mechanisms in PBMCs from FA children. Furthermore, it promoted the precursors of M2 macrophages, DCs and regulatory T cells.

CONCLUSION

The study's findings suggest the importance of butyrate as a pivotal HM compound able to protect against FA.

New Insights into the Implication of Mitochondrial Dysfunction in Tissue, Peripheral Blood Mononuclear Cells, and Platelets during Lung Diseases

Lung diseases such as chronic obstructive pulmonary disease, asthma, pulmonary arterial hypertension, or idiopathic pulmonary fibrosis are major causes of morbidity and mortality. Complex, their physiopathology is multifactorial and includes lung mitochondrial dysfunction and enhanced reactive oxygen species (ROS) release, which deserves increased attention. Further, and importantly, circulating blood cells (peripheral blood mononuclear cells-(PBMCs) and platelets) likely participate in these systemic diseases. This review presents the data published so far and shows that circulating blood cells mitochondrial oxidative capacity are likely to be reduced in chronic obstructive pulmonary disease (COPD), but enhanced in asthma and pulmonary arterial hypertension in a context of increased oxidative stress. Besides such PBMCs or platelets bioenergetics modifications, mitochondrial DNA (mtDNA) changes have also been observed in patients. These new insights open exciting challenges to determine their role as biomarkers or potential guide to a new therapeutic approach in lung diseases.

Mitochondrial Function in Peripheral Blood Mononuclear Cells (PBMC) Is Enhanced, Together with Increased Reactive Oxygen Species, in Severe Asthmatic Patients in Exacerbation

Asthma is a chronic inflammatory lung syndrome with an increasing prevalence and a rare but significant risk of death. Its pathophysiology is complex, and therefore we investigated at the systemic level a potential implication of oxidative stress and of peripheral blood mononuclear cells’ (PBMC) mitochondrial function. Twenty severe asthmatic patients with severe exacerbation (GINA 4–5) and 20 healthy volunteers participated at the study. Mitochondrial respiratory chain complexes activities using different substrates and reactive oxygen species (ROS) production were determined in both groups by high-resolution respirometry and electronic paramagnetic resonance, respectively. Healthy PBMC were also incubated with a pool of plasma of severe asthmatics or healthy controls. Mitochondrial respiratory chain complexes activity (+52.45%, p = 0.015 for V_ADP) and ROS production (+34.3%, p = 0.02) were increased in asthmatic patients. Increased ROS did not originate mainly from mitochondria. Plasma of severe asthmatics significantly increased healthy PBMC mitochondrial dioxygen consumption (+56.8%, p = 0.031). In conclusion, such asthma endotype, characterized by increased PMBCs mitochondrial oxidative capacity and ROS production likely related to a plasma constituent, may reflect activation of the immune system. Further studies are needed to determine whether increased PBMC mitochondrial respiration might have protective effects, opening thus new therapeutic approaches.

Desmoglein 3 gene mediates epidermal growth factor/epidermal growth factor receptor signaling pathway involved in inflammatory response and immune function of anaphylactic rhinitis

OBJECTIVE

To investigate the effects of desmoglein 3 (DSG3) gene mediating epidermal growth factor/epidermal growth factor receptor (EGF/EGFR) signaling pathway on inflammatory response and immune function of anaphylactic rhinitis (AR).

METHODS

Ten of the seventy male BALB/c mice were randomly selected as the normal control group, and the remaining 60 were used to construct the AR mice model. AR model mice were divided into 6 groups: model group (instilled with 5 μL saline), empty vector group (instilled with 5 μL of liposome and empty vector mixture), siRNA-DSG3 group (instilled with 5 μL of liposome and siRNA-DSG3 carrier mixture), AG1478 group (instilled with 5 μL of EGF/EGFR inhibitor AG1478), siRNA-DSG3+AG1478 group (instilled with 5 μL of liposome and siRNA-DSG3 carrier and EGF/EGFR inhibitor AG1478 mixture) and oe-DSG3 group, 10 in each group. After taking serum, each group of mice was sacrificed to get nasal mucosa tissues. HE staining was used to observe the pathological changes of nasal mucosa tissues in each group. The expression levels of DSG3, EGF and EGFR in nasal mucosa tissues of mice in each group were detected by qRT-PCR and western blot methods respectively. TUNEL staining was used to observe the apoptosis of nasal mucosa cells in mice. The expression of IgE, INF-γ, TNF-α, IL-2, IL-4 and IL-6 in serum of mice was determined by ELISA method. The immune adhesion function of red blood cells was detected by complement sensitization yeast hemagglutination method.

RESULTS

All the mice with AR showed different degrees of nasal mucosa injury and inflammatory cell infiltration, and silencing DSG3 or inhibiting the activity of EGF signaling pathway could alleviate the nasal mucosa injury. Compared with control group, the INF-γ and IL-2 levels of serum in AR model mice were significantly decreased; IgE, TNF-α, IL-4 and IL-6 levels were significantly increased (all P < 0.05); the mRNA expression levels and protein levels of DSG3, EGF and EGFR were significantly increased (all P < 0.05); C₃b receptor rosette rate and Ic rosette rate were significantly decreased (all P < 0.05). Detected by ELISA method, the expression levels of IgE, TNF-α, IL-4 and IL-6 were increased, while the expression levels of INF-γ and IL-2 were decreased after DSG3 silencing or using AG1478. Detected by qRT-PCR and western blot methods, the expression of DSG3, EGF and EGFR did decrease after DSG3 silencing. There was no significant difference in the EGF and EGFR expression between DSG3 silencing and using AG1478, and the expression decreased even more under the double effect. The mRNA and protein expression levels of DSG3, EGF and EGFR in the nasal mucosa tissues of mice with overexpression of DSG3 plasmid were significantly higher than those of normal mice (all P < 0.05).

CONCLUSION

Silencing DSG3 gene can inhibit the activation of EGF signaling pathway, alleviate the inflammation of AR nasal mucosa, and enhance red blood cells immune adherence function.

Hepatic Mitochondrial Dysfunction and Immune Response in a Murine Model of Peanut Allergy

Background: Evidence suggests a relevant role for liver and mitochondrial dysfunction in allergic disease. However, the role of hepatic mitochondrial function in food allergy is largely unknown. We aimed to investigate hepatic mitochondrial dysfunction in a murine model of peanut allergy. Methods: Three-week-old C3H/HeOuJ mice were sensitized by the oral route with peanut-extract (PNT). We investigated: 1. the occurrence of effective sensitization to PNT by analysing acute allergic skin response, anaphylactic symptoms score, body temperature, serum mucosal mast cell protease-1 (mMCP-1) and anti-PNT immunoglobulin E (IgE) levels; 2. hepatic involvement by analysing interleukin (IL)-4, IL-5, IL-13, IL-10 and IFN-γ mRNA expression; 3. hepatic mitochondrial oxidation rates and efficiency by polarography, and hydrogen peroxide (H₂O₂) yield, aconitase and superoxide dysmutase activities by spectrophotometry. Results: Sensitization to PNT was demonstrated by acute allergic skin response, anaphylactic symptoms score, body temperature decrease, serum mMCP-1 and anti-peanut IgE levels. Liver involvement was demonstrated by a significant increase of hepatic Th2 cytokines (IL-4, IL-5 and IL-13) mRNA expression. Mitochondrial dysfunction was demonstrated by lower state 3 respiration rate in the presence of succinate, decreased fatty acid oxidation in the presence of palmitoyl-carnitine, increased yield of ROS proven by the inactivation of aconitase enzyme and higher H₂O₂ mitochondrial release. Conclusions: We provide evidence of hepatic mitochondrial dysfunction in a murine model of peanut allergy. These data could open the way to the identification of new mitochondrial targets for innovative preventive and therapeutic strategies against food allergy.

Advances in rhinitis: Models and mechanisms

OBJECTIVE

To summarize studies highlighting recent advances in rhinitis-related research in the past 2 years.

DATA SOURCES

Original research articles were procured and examined from the Rhinitis and Upper Airway Disease section of the 2015 to 2017 Annals of Allergy, Asthma & Immunology issues. Additional original research articles were identified from PubMed and Google Scholar using the following search terms: allergic rhinitis, rhinitis, chronic rhinosinusitis, environmental exposure unit, and nasal allergen challenge. Only research articles published in the past 2 years were procured.

STUDY SELECTIONS

Articles conducting research in allergic rhinitis (AR) or chronic rhinosinusitis or using controlled allergen challenge facilities or the nasal allergen challenge model were selected.

RESULTS

Studies in the past 2 years have focused on using skin prick tests and early-life phenotyping to predict AR development in children. They also have elucidated the role of a subset of CD4⁺ T cells, basophils, and mast cells in non-eosinophilic chronic rhinosinusitis with nasal polyps, a relatively new chronic rhinosinusitis subtype in the Asian population. Several advances have been made in understanding the role of several cytokines and peripheral cell mitochondrial function in AR using controlled allergen challenge facilities and direct nasal allergen challenges.

CONCLUSION

Findings from the recent literature highlight the utility of early-life predictors of AR in possibly targeting high-risk groups for prophylactic interventions. Studies also emphasize the use of controlled allergen challenge facilities and the nasal allergen challenge model as robust experimental models to study AR pathogenesis.

Mitochondrial Function in Allergic Disease

PURPOSE OF THE REVIEW

The connections between allergy, asthma and metabolic syndrome are becoming increasingly clear. Recent research suggests a unifying mitochondrial link between the diverse phenotypes of these interlinked morbidities. The scope of this review is to highlight cellular mechanisms, epidemiology and environmental allergens influencing mitochondrial function and its importance in allergy and asthma. We briefly also consider the potential of mitochondria-targeted therapies in prevention and cure.

RECENT FINDINGS

Recent research has shown allergy, asthma and metabolic syndrome to be linked to mitochondrial dysfunction. Environmental pollutants and allergens are observed to cause mitochondrial dysfunction, primarily by inducing oxidative stress and ROS production. Malfunctioning mitochondria change the bioenergetics of the cell and its metabolic profile to favour systemic inflammation, which drives all three types of morbidities. Given the existing experimental evidence, approaches targeting mitochondria (e.g. antioxidant therapy and mitochondrial replacement) are being conducted in relevant disease models-with some progressing towards clinical trials, making mitochondrial function the focus of translational therapy research in asthma, allergy and linked metabolic syndrome.