Endoplasmic reticulum stress impairs the immune regulation property of macrophages in asthmatic patients

Modulation of Mettl5 alleviates airway allergy by regulating the epigenetic profile of M2 macrophages

M2 macrophages (M2 cells) are known to be involved in both Th2 responses and immune regulation. However, the underlying mechanisms remain unclear. Functional abnormalities in macrophages are associated with airway allergy (AA). The objective of this study was to investigate the role of methyltransferase-like 5 (Mettl5) in macrophages and its potential to alleviate AA. In this study, an airway allergy (AA) mouse model was established using dust mite extracts (DME) as the specific antigen. M2 cells were collected from mice with and without AA. The role of Mettl5 in modulating the immune activities of M2 cells was assessed using both epigenetic and immunological approaches. We found that Mettl5 levels were elevated in airway M2 cells from mice with AA. The presence of Mettl5 in airway M2 cells was positively correlated with airway Th2 polarization in these mice. Airway M2 cells from AA mice exhibited impaired immune-suppressive function, which was resolved by ablating the Mettl5 gene in macrophages. Mettl5 was responsible for the hypermethylation of the Il10 promoter in airway M2 cells of AA mice. Exposure to DME induced Mettl5, which in turn recruited USP21 to deubiquitinate GATA3, thereby boosting IL-4 expression in M2 cells. Inhibiting Mettl5 restored the immune-suppressive capacity of airway M2 cells and mitigated experimental AA. In conclusion, Mettl5 plays a critical role in subverting the immune-regulatory capacity and enhancing IL-4 expression in M2 cells. Inhibition of Mettl5 can mitigate experimental AA by restoring the immune-regulatory functions of M2 cells.

Quercetin improves macrophage immune regulatory functions to alleviate airway Th2 polarization

BACKGROUND

Th2 polarization is a central driver of allergic airway inflammation, yet the epigenetic mechanisms underlying its dysregulation remain poorly defined. Quercetin is a bioactive flavonoid with immunomodulatory properties. This study investigates whether quercetin alleviates Th2-driven pathology in allergic airway inflammation by targeting IL-10 promoter hypermethylation in airway M2 macrophages.

METHODS

Using a murine model of house dust mite (Derf2)-induced allergic airway inflammation, we isolated airway M2 macrophages via flow cytometry and assessed their immunosuppressive capacity using CFSE-based T cell proliferation assays. Epigenetic regulation of Il10 was analyzed by bisulfite sequencing and chromatin immunoprecipitation. Quercetin (intranasal) was administered daily for 7 days.

RESULTS

Allergic mice exhibited impaired M2 cell-mediated T cell suppression (proliferation index: 85% vs. 34% in controls, P < 0.01) and IL-10 deficiency in bronchoalveolar lavage fluid (8.5 pg/ml vs. 28.2 pg/ml, P <0.001). Il10 promoter hypermethylation (72% vs. 35% methylation at CpG sites -200 to +100) and reduced KDM5A recruitment were observed in M2 cells from allergic mice. Quercetin treatment reversed these epigenetic defects, restoring KDM5A binding (P < 0.05) and Il10 transcription (2.1-fold increase, P < 0.01), thereby reducing Th2 cytokines and airway hyperresponsiveness.

CONCLUSIONS

Our findings identify KDM5A-mediated Il10 promoter demethylation as a critical mechanism for M2 cell immunoregulation in allergic airway inflammation. Quercetin alleviates Th2-driven pathology by restoring Il10 expression via epigenetic reprogramming of M2 macrophages. This study advances the understanding of natural compounds in targeting epigenetic checkpoints and provides a rationale for quercetin-based therapies in allergic diseases.

IL-10 signaling modulates PRKN methylation and influences STAT3 activity to drive regulatory macrophage differentiation

The pathogenesis of many immune disorders is linked to regulatory macrophage dysfunction. The mechanism underlying it is unclear. The objective of this study is to examine the mechanism by which the PRKN ubiquitin protein ligase (PRKN) inhibits the development of regulatory macrophages (Mreg). In this study, dust mite antigens were used as the specific allergens to establish an airway allergy (AA) mouse model. Flow cytometry cell sorting was used to isolate macrophages from the airway tissues. According to the results, the Prkn gene inhibition led to an increase in the number of Mregs in macrophages. Mregs demonstrated the capacity to suppress Th2 polarization, in which IL-10 played a critical role. Pan macrophages isolated from Prkn-deficient mice were more capable of suppressing the activities of other immune cells. PRKN was required for maintaining the hyperubiquitous status of signal transducer and transcriptional activator-3 (STAT3) in macrophages. Exposure to dust mite antigen increased the expression of PRKN in macrophages. IL-10 suppressed PRKN in macrophages by inducing its promoter hypermethylation. PRKN inhibition mitigated the experimental AA. To sum up, PRKN maintains the hyper ubiquitous status of STAT3 and restricts the expression of IL-10 in macrophages, which compromises their immune suppressive functions. Inhibition of PRKN increases Mreg development and mitigates AA. The data suggest that the regulation of Mreg has translation potential to be used in the treatment of immune disorders such as AA.

Impaired inducibility of immune regulatory capacity of peripheral B cells of patients with recurrent pregnancy loss

The pathogenesis of recurrent pregnancy loss (RPL) is unclear. RPL may have an association with disruption of immune tolerance. The aim of this study is to characterize the inducibility of immune regulatory ability in peripheral naïve B cells of patients with RPL. In this study, blood samples were taken from patients with RPL. B220+ B cells were isolated by flow cytometry cell sorting. The gene profile of B cells was analyzed using RNA sequencing (RNAseq). The results showed that peripheral B220+ B cells of RPL patients had lower expression of IL10 and exacerbated ER stress. The induction of IL10 expression in peripheral B220+ B cells of RPL patients were impaired. High ubiquitination of c-Maf inducing protein (CMIP) was detected in RPL B cells. Exposure to thapsigargin (an ER stress agonist) decreased the amount of CMIP in B cells. The effects of ER stress on reducing CMIP quantity in B cells were mediated by the histone H2B E3 ubiquitin ligase ring finger protein 20 (RNF20). Inhibition of RNF20 or ER stress restored the inducibility of immune regulatory functions of B220+ B cells of RPL patients. In summary, peripheral B cells in patients with RPL show impaired immune regulation capacity, in which exacerbated ER stress plays a crucial role. Regulation of ER stress or inhibition of RNF20 can restore the immune regulatory capacity in the B cells.

Probiotic nucleotides increase IL-10 expression in airway macrophages to mitigate airway allergy

BACKGROUND

Dysfunctional immune regulation plays a crucial role in the pathogenesis of airway allergies. Macrophages are one of the components of the immune regulation cells. The aim of this study is to elucidate the role of lysine demethylase 5 A (KDM5A) in maintaining macrophages' immune regulatory ability.

METHODS

DNA was extracted from Lactobacillus rhamnosus GG to be designated as LgDNA. LgDNA was administered to the mice through nasal instillations. M2 macrophages (M2 cells) were isolated from the airway tissues using flow cytometry.

RESULTS

We found that airway M2 cells of mice with airway Th2 polarization had reduced amounts of IL-10 and KDM5A. Mice with Kdm5a deficiency in M2 cells showed the airway Th2 polarization. The expression of Kdm5a in airway M2 cells was enhanced by nasal instillations containing LgDNA. KDM5A mediated the effects of LgDNA on inducing the Il10 expression in airway M2 cells. Administration of LgDNA mitigated experimental airway allergy.

CONCLUSIONS

M2 macrophages in the airway tissues of mice with airway allergy show low levels of KDM5A. By upregulating KDM5A expression, LgDNA can increase Il10 expression and reconcile airway Th2 polarization.

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) restores immune regulatory functions of airway macrophages of patients with asthma

Allergic asthma is characterized by the polarization of Th2 cells and impaired immune regulation. Macrophages occupy the largest proportion of airway immune cells. This study aims to discover the mechanism that hinders the immune regulatory functions of airway macrophages. In this study, macrophages were isolated from cells in bronchoalveolar lavage fluids (BALF) collected from asthma patients and normal control (NC) subjects. The results indicated that macrophages occupied the largest portion of the cellular components in BALF. The frequency of IL-10+ macrophage was significantly lower in asthma patients than in NC subjects. The expression of IL-10 in macrophages of BALF was associated with the levels of asthma-related parameters. The immune-suppressive functions of BALF M0 cells were defective in asthma patients. The inducibility of IL-10 expression was impaired in BALF macrophages of asthma patients, which could be restored by exposing to CpG. In conclusion, the induction of IL-10 in macrophages of BALF in asthma patients was impaired, and it could be restored by exposure to CpG.

TRIM41 contributes to the pathogenesis of airway allergy by compromising dendritic cells' tolerogenic properties

Dendritic cells (DC) play a crucial role in the initiation of immune responses. TRIM41, an E3 ubiquitin ligase, can facilitate targeting protein degradation. The purpose of this study is to analyze the role of TRIM41 in the pathogenesis of airway allergy (AA) and the impact of regulating TRIM41 on suppressing AA. We observed that the airway DCs of AA mice had a higher expression of Trim41. The expression of Trim41 in airway DCs was associated with the DCs' tolerogenic functions of AA mice. The AA responses, including increased amounts of eosinophil peroxidase, mast cell protease-1, Th2 cytokines, and specific IgE in bronchoalveolar lavage fluids, were positively correlated with the Trim41 expression in mouse airway DCs. TRIM41 induced c-Maf degradation and interfered with the Il10 expression in airway DCs, which could be counteracted by inhibiting TRIM41. Regulation of TRIM41 mitigated experimental AA responses.

Psychological stress to ovalbumin peptide-specific T-cell receptor transgenic mice impairs the suppressive ability of type 1 regulatory T cell

Numerous diseases of the immune system can be traced back to the malfunctioning of the regulatory T cells. The aetiology is unclear. Psychological stress can cause disruption to the immune regulation. The synergistic effects of psychological stress and immune response on immune regulation have yet to be fully understood. The intention of this study is to analyse the interaction between psychological stress and immune responses and how it affects the functional status of type 1 regulatory T (Tr1) cells. In this study, ovalbumin peptide T-cell receptor transgenic mice were utilised. Mice were subjected to restraint stress to induce psychological stress. An airway allergy murine model was established, in which a mouse strain with RING finger protein 20 (Rnf20)-deficient CD4+ T cells were used. The results showed that concomitant exposure to restraint stress and immune response could exacerbate endoplasmic reticulum stress in Tr1 cells. Corticosterone was responsible for the elevated expression of X-box protein-1 (XBP1) in mouse Tr1 cells after exposure to both restraint stress and immune response. XBP1 mediated the effects of corticosterone on inducing Rnf20 in Tr1 cells. The reduction of the interleukin-10 expression in Tr1 cells was facilitated by Rnf20. Inhibition of Rnf20 alleviated experimental airway allergy by restoring the immune regulatory ability of Tr1 cells. In conclusion, the functions of Tr1 cells are negatively impacted by simultaneous exposure to psychological stress and immune response. Tr1 cells' immune suppressive functions can be restored by inhibiting Rnf20, which has the translational potential for the treatment of diseases of the immune system.

Effects of Natural Products through Inhibiting Endoplasmic Reticulum Stress on Attenuation of Idiopathic Pulmonary Fibrosis

With ever-increasing intensive studies of idiopathic pulmonary fibrosis (IPF), significant progresses have been made. Endoplasmic reticulum stress (ERS)/unfolded protein reaction (UPR) is associated with the development and progression of IPF, and targeting ERS/UPR may be beneficial in the treatment of IPF. Natural product is a tremendous source of new drug discovery, and accumulating studies have reported that many natural products show potential therapeutic effects for IPF via modulating one or more branches of the ERS signaling pathway. Therefore, this review focuses on critical roles of ERS in IPF development, and summarizes herbal preparations and bioactive compounds which protect against IPF through regulating ERS.

Direct exposure to CpG and specific antigens mitigate airway allergy through modulating dendritic cell properties

BACKGROUND

CpG oligodeoxynucleotide (CpG-ODN; CpG, in short) has been employed as an adjuvant in allergen specific immunotherapy (AIT) to treat allergic diseases. The underlying mechanism needs to be further explained. The aim of this study is to examine the mechanism by which CpG and dust mite extracts (DME, a specific antigen) alleviate experimental airway allergy.

METHODS

DME was used as the specific allergen to establish an airway allergy mouse model. The mice were directly exposed to DME and CpG through nasal instillations (the CpG.DME therapy). The response of DCs and allergic responses in the airways were assessed using immunological approaches.

RESULTS

The airway allergy reaction was effectively suppressed by CpG.DME therapy. The administration of CpG or DME alone did not have any significant suppressive effects on the airway allergic response. Direct exposure to CpG.DME induced type 1 DCs (DC1s) and plasmacytoid DCs (pDCs), while CpG alone induced DC1s and DME alone induced DC2s in the airway tissues. Both DC1s and pDCs were required for the induction of type 1 regulatory T cells in the airway tissues by CpG.DME therapy. Depletion of either pDCs or DC1s abolished the induction of Tr1 cells, and abolished the suppressive effects on airway allergic response by the CpG.DME therapy.

CONCLUSIONS

Direct exposure to CpG.DME induces DC1s and pDCs in the airway tissues. DC1s in synergy with pDCs induce type 1 regulatory T cells. The CpG.DME therapy is effective in suppressing allergic responses in mice with airway allergy.

Allergen specific immunotherapy regulates macrophage property in the airways

BACKGROUND

Allergen specific immunotherapy (AIT) has been widely used in allergy clinics. The therapeutic effects of it are to be improved. Macrophages occupy the largest proportion of airway immune cells. The aim of this study is to measure the effects of nasal instillation AIT (nAIT) on airway allergy by regulating macrophage functions.

METHODS

An airway allergy mouse model was established with the ovalbumin-alum protocol. nAIT was conducted for mice with airway allergy through nasal instillation. The effects of nAIT were compared with subcutaneous injection AIT (SCIT) and sublingual AIT (SLIT).

RESULTS

Mice with airway allergy showed the airway allergic response, including lung inflammation, airway hyper responsiveness, serum specific IgE, increase in the amounts of eosinophil peroxidase, mouse mast cell protease-1, and Th2 cytokines in bronchoalveolar lavage fluid. nAIT had a much better therapeutic effect on the airway allergic response than SCIT and SLIT. Mechanistically, we observed better absorption of allergen in macrophages, better production of IL-10 by macrophages, and better immune suppressive functions in macrophages in mice received nAIT than SCIT and SLIT.

CONCLUSIONS

The nAIT has a much better therapeutic effect on suppressing the airway allergic response, in which macrophages play a critical role.

Edaravone alleviated allergic airway inflammation by inhibiting oxidative stress and endoplasmic reticulum stress

Oxidative stress and endoplasmic reticulum stress (ERS) was associated with the development of asthma. Edaravone (EDA) plays a classical role to prevent the occurrence and development of oxidative stress-related diseases. Herein, we investigated the involvement and signaling pathway of EDA in asthma, with particular emphasis on its impact on type 2 innate lymphoid cells (ILC2) and CD4+T cells, and then further elucidated whether EDA could inhibit house dust mite (HDM)-induced allergic asthma by affecting oxidative stress and ERS. Mice received intraperitoneally injection of EDA (10 mg/kg, 30 mg/kg), dexamethasone (DEX) and N-acetylcysteine (NAC), with the latter two used as positive control drugs. DEX and high dose of EDA showed better therapeutic effects in alleviating airway inflammation and mucus secretion in mice, along with decreasing eosinophils and neutrophils in bronchoalveolar lavage fluid (BALF) than NAC. Further, the protein levels of IL-33 in lung tissues were inhibited by EDA, leading to reduced activation of ILC2s in the lung. EDA treatment alleviated the activation of CD4+ T cells in lung tissues of HDM-induced asthmatic mice and reduced Th2 cytokine secretion in BALF. ERS-related markers (p-eIF2α, IRE1α, CHOP, GRP78) were decreased after treatment of EDA compared to HDM group. Malondialdehyde (MDA), glutathione (GSH), hydrogen peroxide (H2O2), and superoxide dismutase (SOD) were detected to evaluate the oxidant stress in lung tissues. EDA showed a protective effect against oxidant stress. In conclusion, our findings demonstrated that EDA could suppress allergic airway inflammation by inhibiting oxidative stress and ERS, suggesting to serve as an adjunct medication for asthma in the future.