Allergen induces CD11c+ dendritic cell autophagy to aggravate allergic rhinitis through promoting immune imbalance

Role of autophagy and mitophagy of group 2 innate lymphoid cells in allergic and local allergic rhinitis

Background

Roles of ILC2s in allergic rhinitis (AR) and local allergic rhinitis (LAR) are unclear. In this study, we are determined to find the levels of autophagy and mitophagy of ILC2s in allergic nasal inflammation.

Methods

ELISA was used to detect type 2 inflammatory cytokines. Hematoxylin and eosin (H&E) staining were used to compare the eosinophil (EOS) infiltration of nasal tissue specimens. Flow cytometry was used to detect the levels of ILC2s and Th2 cells. Immunohistochemistry (IHC) and Western blot (WB) were used to detect the levels of Beclin1, LC3, p62, PINK1, Parkin, FUNDC1, and BNIP3 in nasal mucosa. The levels of autophagy related proteins and mitophagy related proteins of the ILC2s were detected by WB. The number of autophagosomes of ILC2s was observed by transmission electron microscopy. The co-localization levels of GFP-LC3 and Mito tracker in ILC2s were observed by confocal microscopy using immunofluorescence.

Results

We found that the level of type 2 inflammation in AR and LAR mice was significantly increased. The levels of autophagy and mitophagy of AR and LAR mice in nasal mucosa and ILC2s were both increased.

Conclusions

ILC2s may be associated with the occurrence and development of nasal allergic inflammation. The abnormal increase of autophagy and mitophagy levels in the nose may be associated with the incidence of AR and LAR. Abnormal autophagy and mitophagy levels of ILC2s cells may be one of the causes of allergic nasal inflammation.

Tissue-specific antigen-presenting cells contribute to distinct phenotypes of allergy

Antigen-presenting cells (APCs) are critical cells bridging innate and adaptive immune responses by taking up, processing, and presenting antigens to naïve T cells. At steady state, APCs thus control both tissue homeostasis and the induction of tolerance. In allergies however, APCs drive a Th2-biased immune response that is directed against otherwise harmless antigens from the environment. The main types of APCs involved in the induction of allergy are dendritic cells, monocytes, and macrophages. However, these cell types can be further divided into local, tissue-specific populations that differ in their phenotype, migratory capacity, T-cell activating potential, and production of effector molecules. Understanding if distinct populations of APCs contribute to either tissue-specific immune tolerance, allergen sensitization, or allergic inflammation will allow us to better understand disease pathology and develop targeted treatment options for different stages of allergic disease. Therefore, this review describes the main characteristics, phenotypes, and effector molecules of the APCs involved in the induction of allergen-specific Th2 responses in affected barrier sites, such as the skin, nose, lung, and gastrointestinal tract. Furthermore, we highlight open questions that remain to be addressed to fully understand the contribution of different APCs to allergic disease.

Atorvastatin attenuates allergic inflammation by blocking prostaglandin biosynthesis in rats with allergic rhinitis

BACKGROUND

Prostaglandins (PGs) are bioactive lipid mediators derived from the nuclear and plasma membranes via the cyclooxygenase (COX) pathway of arachidonic acid (AA) metabolism. PGs bridge the interactions between various immunomodulatory cells in allergic rhinitis (AR) and are considered key players in regulating pro-inflammatory and anti-inflammatory responses. AA conversion to PGs involves rate-limiting enzymes that may be blocked by statins. The mechanisms by which statins regulate these enzymes in AR remain unclear. We investigated the effects of oral atorvastatin on PGs production in AR.

METHODS

An ovalbumin-induced AR rat model was constructed and the changes in nasal symptom score and nasal mucosa histopathological characteristics of AR rats under different atorvastatin doses were assessed. qRT-PCR, western blotting, and immunofluorescence were used to detect the mRNA and protein expression levels of rate-limiting enzymes and downstream molecules of AA metabolism in the nasal mucosa and liver.

RESULTS

Oral atorvastatin significantly alleviated symptoms and eosinophil infiltration in the nasal mucosa, inhibited goblet cell hyperplasia and mast cell recruitment, and decreased mucus secretion in AR rats. Increasing atorvastatin dose increased the anti-inflammatory effects. High-dose atorvastatin inhibited upregulation of the inflammatory mediator PGD₂ in the nasal mucosa of AR rats. Compared to the control group, the mRNA and protein expression of the rate-limiting enzymes COX-2, PGDS, and PGES in AA metabolism in the AR group were upregulated but downregulated after the oral administration of high-dose atorvastatin. Atorvastatin also showed dose-dependent inhibition of ERK1/2 and downstream NF-κB phosphorylation in the nasal mucosa and liver of AR rats.

CONCLUSIONS

Atorvastatin inhibited allergic inflammation and attenuated AR nasal symptoms by downregulating PGD₂ and rate-limiting enzyme expression in PGD₂ biosynthesis, possibly by blocking the RAS/ERK/NF-κB signaling pathway.

Update on pathomechanisms and treatments in allergic rhinitis

Allergic rhinitis (AR) is a global health problem with increasing prevalence and association with an enormous medical and socioeconomic burden. New recognition of immune cells such as type 2 innate lymphocytes (ILC2s), T helper (Th2) 2 cells, follicular helper T cells, follicular regulatory T cells, regulatory T cells, B cells, dendritic cells, and epithelial cells in AR pathogenesis has been updated in this review paper. An in-depth understanding of the mechanisms underlying AR will aid the identification of biomarkers associated with disease and ultimately provide valuable parameters critical to guide personalized targeted therapy. As the only etiological treatment option for AR, allergen-specific immunotherapy (AIT) has attracted increasing attention, with evidence for effectiveness of AIT recently demonstrated in several randomized controlled trials and long-term real-life studies. The exploration of biologics as therapeutic options has only involved anti-IgE and anti-type 2 inflammatory agents; however, the cost-effectiveness of these agents remains to be elucidated precisely. In the midst of the currently on-going COVID-19 pandemic, a global life-threatening disease, although some studies have indicated that AR is not a risk factor for severity and mortality of COVID-19, this needs to be confirmed in multi-centre, real-life studies of AR patients from different parts of the world.

Allergen immunotherapy enhances the immunosuppressive effects of Treg cells to alleviate allergic rhinitis by decreasing PU-1+ Treg cell numbers

OBJECTIVE

To investigate the role of Tregs and their subtypes in the treatment of allergic rhinitis with allergen immunotherapy (AIT) as well as the underlying mechanism.

METHODS

1. Thirty-one healthy controls, 29 Allergic rhinitis (AR) patients and 16 AR patients treated with AIT were recruited. The total nasal symptom scores (TNSSs) were calculated. The serum levels of IgE, IL-2, TNF-α, IFN-γ, IL-4, IL-5, IL-6, IL-10 and IL-17 were measured. 2. Changes in the proportions of CD4+ T cells, Treg cells, Treg subtypes and Th1/Th2/Th9/Th17/Tfh cells in the peripheral blood of the subjects in the three groups were measured. 3. The correlations of Treg cells, Treg subtypes and TNSS with the levels of various cytokines in the AR group and AIT group were analysed.

RESULTS

1. Compared with the control group, the TNSS and IgE, IL-5 and IL-6 levels in the AR group were significantly increased, while the IL-2, IFN-γ and IL-10 levels were significantly decreased (P < 0.05). Compared with the AR group, the TNSS and IgE, IL-5 and IL-6 levels in the AIT group were significantly decreased, while the IL-2, IFN-γ and IL-10 levels were significantly increased (P < 0.05). 2. Compared with the control group, the proportions of Tregs, GATA3+ Tregs and Th1 cells in the AR group were significantly reduced, while the proportions of PU-1+ Tregs, T-bet+ Tregs and Th2 cells were significantly increased (P < 0.05). Compared with the AR group, the proportions of Tregs and Th1 cells in the AIT group were significantly increased, while the proportions of PU-1+ Tregs and Th2 cells were decreased (P < 0.05). 3. Correlation analysis showed that Treg cell proportions were negatively correlated with the TNSS, sIgE levels, IL-5 levels and IL-6 levels but positively correlated with the IL-2 and IL-10 levels (P < 0.05). PU-1+ Treg cell proportions were positively correlated with the TNSS, sIgE levels, IL-5 levels and IL-6 levels but negatively correlated with the Treg cell proportions, IL-2 levels and IL-10 levels (P < 0.05).

CONCLUSIONS

AIT can reduce the proportions of PU-1+ Treg subtypes in AR patients. PU-1+ Treg cell numbers can potentially be used as an indicator to monitor the therapeutic effect of AIT on AR.

Low Surface Accessible Area NanoCoral TiO2 for the Reduction of Foreign Body Reaction During Implantation

The entry of implants triggers the secretion of damage associated molecular patterns (DAMPs) that recruit dendritic cells (DCs) and results in subsequent foreign body reaction (FBR). Though several studies have illustrated that the surface accessible area (SAA) of implants plays a key role in the process of DAMPs release and absorption, the effect of SAA on the immune reaction still remains unknown. Here, a series of TiO2 plates with different SAA is fabricated to investigate the relationship between SAA and FBR. Compared with larger SAA surface, the aggregation of DC is significantly inhibited by lower SAA surface. Total internal reflection microscopy (TIRFM) and molecular dynamic (MD) simulation show that although high mobility group box 1 (HMGB1) is adsorbed more on plates with lower SAA, the exposure ratio of cysteine (CYS) residue in HMGB1 is significantly decreased in lower SAA group. The lower exposure of CYS reduces the activation of Toll-like receptors 4 (TLR4), which down-regulates the expression of myeloid differentiation factor (Myd88)-TNF receptor associated factor 6 (TRAF6) to inhibit nuclear factor kappa B (NF-κB) signaling. Generally, this study reveals the mechanism of how SAA, a nanoscale property, affects FBR from perspective of DAMPs, and provides a new direction for designing better biocompatible implants.