Type II alveolar epithelial cell-specific loss of RhoA exacerbates allergic airway inflammation through SLC26A4

Mechanism of action of miR-15b-5p in alleviating asthma airway remodeling through the HMGB1/TLR4/IL-33 signaling axis

The pathophysiologic processes of asthma are characterized not only by significant changes in miRNA expression but also by the modulation of HMGB1 and its downstream effectors. However, the specific roles of miR-15b-5p and HMGB1 in asthma remain poorly understood. This study explores the regulatory role of miR-15b-5p in asthma by targeting HMGB1. We utilized HMGB1-conditioned knockout mice (Sftpc-cre; HMGB1flox/flox) in type II alveolar epithelial cells (AT2), induced with house dust mite (HDM), to establish a mouse model of asthma. Results demonstrated that AT2 cell-specific deletion of HMGB1 attenuated allergen-induced airway hyperresponsiveness and reduced airway inflammation. Concurrently, miR-15b-5p levels were significantly reduced in wild-type (WT) asthmatic mice, while HMGB1, TLR4, and IL-33 levels were elevated. Administration of miR-15b-5p agomir mirrored the effects of HMGB1 knockdown, reducing peribronchiolar inflammatory cells and ameliorating airway inflammation and remodeling. A luciferase reporter gene assay system was employed to predict and verify HMGB1 as a direct target of miR-15b-5p. Overexpression of miR-15b-5p significantly inhibited apoptosis and activation of HMGB1, TLR4, and IL-33, and decreased NLRP3, Caspase-1, and IL-1β expression. In vitro, miR-15b-5p overexpression and HMGB1 knockdown attenuated HDM-induced cellular inflammation and production of Cleaved-caspase-9, Cleaved-caspase-3, and Bax, while enhancing mitochondrial membrane potential. This study suggests that miR-15b-5p acts as a protective mechanism against allergic airway inflammation by inhibiting the HMGB1/TLR4/IL-33 signaling pathway in AT2 cells. Targeting the HMGB1/TLR4/IL-33 signaling by miR-15b-5p may offer a potential therapeutic strategy for asthma.

Mechanism of miR-130b-3p in relieving airway inflammation in asthma through HMGB1-TLR4-DRP1 axis

Asthma is a chronic inflammatory respiratory disease characterized by recurrent breathing difficulties caused by airway obstruction and hypersensitivity. Although there is diversity in their specific mechanisms, microRNAs (miRNAs) have a significant impact on the development of asthma. Currently, the contribution of miR-130b-3p to asthma remains elusive. The goal of this study was to examine whether miR-130b-3p attenuates house dust mite (HDM)-induced asthma through High-mobility group box protein 1 (HMGB1)/Toll-like receptor 4 (TLR4)/mitochondrial fission protein (DRP1) signaling pathway. We elucidate that miR-130b-3p can bind to the HMGB1 3'UTR, attenuating HMGB1 mRNA and protein levels, and nucleo-cytoplasmic translocation of HMGB1. We observed that miR-130b-3p agomir or HMGB1 CKO attenuated HDM-induced airway inflammation and hyperresponsiveness, and decreased Th2-type cytokines in bronchoalveolar lavage fluid (BALF) and mediastinal lymph nodes. Further, HMGB1 CKO contributes to alleviating Th2 inflammation in AT-II cells (CD45.2-/CD31-/Epcam-+/proSP-C+/MHC-II+) from lung single cell suspensions of asthmatic mice by flow cytometry. Our findings identified miR-130b-3p as a potent regulator in asthma that exerts its anti-inflammatory effects by targeting HMGB1 and the subsequent HMGB1/TLR4/DRP1axis, presenting a prospective novel therapeutic avenue for asthma management.

Deficiency of DEK proto-oncogene alleviates allergic rhinitis by inhibiting RhoA/Ezrin-mediated mitochondrial fission

BACKGROUND

Allergic rhinitis (AR) is a kind of immune disease mediated by IgE. We are intrigued by the potential role of DEK proto-oncogene (DEK) in inflammation-related diseases. We investigated the effects and mechanisms of DEK in treating AR, aiming to identify potential new treatment targets for AR.

METHODS

The AR mouse model was induced by house dust mite (HDM) (1 mg/mL). HNEpCs stimulated by HDM (1 mg/mL) were pretreated for 24 h with or without DEK lentivirus. The effect of DEK knockout or knockdown on AR was evaluated in vitro and in vivo using western blotting, ELISA, flow cytometry, real-time quantitative PCR, immunohistochemistry, HE staining, PAS staining, Diff staining, and immunofluorescence.

RESULTS

After DEK knockdown, the inflammatory response of AR mice was reduced. In addition, DEK deletion mitigated nasal tissue damage and mitochondrial division. Our further studies showed that DEK deletion or inhibition led to the down-regulation of RhoA activity and decreased phosphorylation of Ezrin and Drp1 proteins, and inhibited mitochondrial division. Overall, DEK deficiency mitigated AR by down-regulating RhoA/Ezrin/Drp1 pathway activity.

CONCLUSION

DEK alleviates AR through RhoA/Ezrin/Drp1 signaling pathway, which provides a new perspective for developing improved therapies and understanding the pathogenesis of AR.

Availability of Receptors for Advanced Glycation End-Products (RAGE) Influences Differential Transcriptome Expression in Lungs from Mice Exposed to Chronic Secondhand Smoke (SHS)

The receptor for advanced glycation end-products (RAGE) has a central function in orchestrating inflammatory responses in multiple disease states including chronic obstructive pulmonary disease (COPD). RAGE is a transmembrane pattern recognition receptor with particular interest in lung disease due to its naturally abundant pulmonary expression. Our previous research demonstrated an inflammatory role for RAGE following acute exposure to secondhand smoke (SHS). However, chronic inflammatory mechanisms associated with RAGE remain ambiguous. In this study, we assessed transcriptional outcomes in mice exposed to chronic SHS in the context of RAGE expression. RAGE knockout (RKO) and wild-type (WT) mice were delivered nose-only SHS via an exposure system for six months and compared to control mice exposed to room air (RA). We specifically compared WT + RA, WT + SHS, RKO + RA, and RKO + SHS. Analysis of gene expression data from WT + RA vs. WT + SHS showed FEZ1, Slpi, and Msln as significant at the three-month time point; while RKO + SHS vs. WT + SHS identified cytochrome p450 1a1 and Slc26a4 as significant at multiple time points; and the RKO + SHS vs. WT + RA revealed Tmem151A as significant at the three-month time point as well as Gprc5a and Dynlt1b as significant at the three- and six-month time points. Notable gene clusters were functionally analyzed and discovered to be specific to cytoskeletal elements, inflammatory signaling, lipogenesis, and ciliogenesis. We found gene ontologies (GO) demonstrated significant biological pathways differentially impacted by the presence of RAGE. We also observed evidence that the PI3K-Akt and NF-κB signaling pathways were significantly enriched in DEGs across multiple comparisons. These data collectively identify several opportunities to further dissect RAGE signaling in the context of SHS exposure and foreshadow possible therapeutic modalities.

Chloride/Multiple Anion Exchanger SLC26A Family: Systemic Roles of SLC26A4 in Various Organs

Solute carrier family 26 member 4 (SLC26A4) is a member of the SLC26A transporter family and is expressed in various tissues, including the airway epithelium, kidney, thyroid, and tumors. It transports various ions, including bicarbonate, chloride, iodine, and oxalate. As a multiple-ion transporter, SLC26A4 is involved in the maintenance of hearing function, renal function, blood pressure, and hormone and pH regulation. In this review, we have summarized the various functions of SLC26A4 in multiple tissues and organs. Moreover, the relationships between SLC26A4 and other channels, such as cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, and sodium chloride cotransporter, are highlighted. Although the modulation of SLC26A4 is critical for recovery from malfunctions of various organs, development of specific inducers or agonists of SLC26A4 remains challenging. This review contributes to providing a better understanding of the role of SLC26A4 and development of therapeutic approaches for the SLC26A4-associated hearing loss and SLC26A4-related dysfunction of various organs.

Effective delivery of miR-511-3p with mannose-decorated exosomes with RNA nanoparticles confers protection against asthma

Our previous studies have shown that miR-511-3p treatment has a beneficial effect in alleviating allergic airway inflammation. Here, we sought to explore its therapeutic potential in animal models and gain a deeper understanding of its therapeutic value for asthma. miR-511-3p knockout mice (miR-511-3p-/-) were generated by CRISPR/Cas and showed exacerbated airway hyper-responsiveness and Th2-associated allergic airway inflammation compared with wild-type (WT) mice after exposed to cockroach allergen. RNA nanoparticles with mannose decorated EV-miR-511-3p were also created by loading miR-511-3p mimics into the mannose decorated EVs with engineered RNA nanoparticle PRNA-3WJ (Man-EV-miR-511-3p). Intra-tracheal inhalation of Man-EV-miR-511-3p, which could effectively penetrate the airway mucus barrier and deliver functional miR-511-3p to lung macrophages, successfully reversed the increased airway inflammation observed in miR-511-3p-/- mice. Through microarray analysis, complement C3 (C3) was identified as one of the major targets of miR-511-3p. C3 was increased in LPS-treated macrophages but decreased after miR-511-3p treatment. Consistent with these findings, C3 expression was elevated in the lung macrophages of an asthma mouse model but decreased in mice treated with miR-511-3p. Further experiments, including miRNA-mRNA pulldown and luciferase reporter assays, confirmed that miR-511-3p directly binds to C3 and activates the C3 gene. Thus, miR-511-3p represents a promising therapeutic target for asthma, and RNA nanotechnology reprogrammed EVs are efficient carriers for miRNA delivery for disease treatment.

Isthmin-1 attenuates allergic Asthma by stimulating adiponectin expression and alveolar macrophage efferocytosis in mice

BACKGROUND

Allergic asthma is a common respiratory disease that significantly impacts human health. Through in silico analysis of human lung RNASeq, we found that asthmatic lungs display lower levels of Isthmin-1 (ISM1) expression than healthy lungs. ISM1 is an endogenous anti-inflammatory protein that is highly expressed in mouse lungs and bronchial epithelial cells, playing a crucial role in maintaining lung homeostasis. However, how ISM1 influences asthma remains unclear. This study aims to investigate the potential involvement of ISM1 in allergic airway inflammation and uncover the underlying mechanisms.

METHODS

We investigated the pivotal role of ISM1 in airway inflammation using an ISM1 knockout mouse line (ISM1-/-) and challenged them with house dust mite (HDM) extract to induce allergic-like airway/lung inflammation. To examine the impact of ISM1 deficiency, we analyzed the infiltration of immune cells into the lungs and cytokine levels in bronchoalveolar lavage fluid (BALF) using flow cytometry and multiplex ELISA, respectively. Furthermore, we examined the therapeutic potential of ISM1 by administering recombinant ISM1 (rISM1) via the intratracheal route to rescue the effects of ISM1 reduction in HDM-challenged mice. RNA-Seq, western blot, and fluorescence microscopy techniques were subsequently used to elucidate the underlying mechanisms.

RESULTS

ISM1-/- mice showed a pronounced worsening of allergic airway inflammation and hyperresponsiveness upon HDM challenge. The heightened inflammation in ISM1-/- mice correlated with enhanced lung cell necroptosis, as indicated by higher pMLKL expression. Intratracheal delivery of rISM1 significantly reduced the number of eosinophils in BALF and goblet cell hyperplasia. Mechanistically, ISM1 stimulates adiponectin secretion by type 2 alveolar epithelial cells partially through the GRP78 receptor and enhances adiponectin-facilitated apoptotic cell clearance via alveolar macrophage efferocytosis. Reduced adiponectin expression under ISM1 deficiency also contributed to intensified necroptosis, prolonged inflammation, and heightened severity of airway hyperresponsiveness.

CONCLUSIONS

This study revealed for the first time that ISM1 functions to restrain airway hyperresponsiveness to HDM-triggered allergic-like airway/lung inflammation in mice, consistent with its persistent downregulation in human asthma. Direct administration of rISM1 into the airway alleviates airway inflammation and promotes immune cell clearance, likely by stimulating airway adiponectin production. These findings suggest that ISM1 has therapeutic potential for allergic asthma.

Type II alveolar epithelial cell aryl hydrocarbon receptor protects against allergic airway inflammation through controlling cell autophagy

Rationale

Aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, has been considered as an important regulator for immune diseases. We have previously shown that AhR protects against allergic airway inflammation. The underlying mechanism, however, remains undetermined.

Objectives

We sought to determine whether AhR specifically in type II alveolar epithelial cells (AT2) modulates allergic airway inflammation and its underlying mechanisms.

Methods

The role of AhR in AT2 cells in airway inflammation was investigated in a mouse model of asthma with AhR conditional knockout mice in AT2 cells (Sftpc-Cre;AhR^f/f ). The effect of AhR on allergen-induced autophagy was examined by both in vivo and in vitro analyses. The involvement of autophagy in airway inflammation was analyzed by using autophagy inhibitor chloroquine. The AhR-regulated gene profiling in AT2 cells was also investigated by RNA sequencing (RNA-seq) analysis.

Results

Sftpc-Cre;AhR^f/f mice showed exacerbation of allergen-induced airway hyperresponsiveness and airway inflammation with elevated Th2 cytokines in bronchoalveolar lavage fluid (BALF). Notably, an increased allergen-induced autophagy was observed in the lung tissues of Sftpc-Cre;AhR^f/f mice when compared with wild-type mice. Further analyses suggested a functional axis of AhR-TGF-β1 that is critical in driving allergic airway inflammation through regulating allergen-induced cellular autophagy. Furthermore, inhibition of autophagy with autophagy inhibitor chloroquine significantly suppressed cockroach allergen-induced airway inflammation, Th2 cytokines in BALFs, and expression of autophagy-related genes LC3 and Atg5 in the lung tissues. In addition, RNA-seq analysis suggests that autophagy is one of the major pathways and that CALCOCO2/NDP52 and S1009 are major autophagy-associated genes in AT2 cells that may contribute to the AhR-mediated cockroach allergen-induced airway inflammation and, subsequently, allergic asthma.

Conclusion

These results suggest that AhR in AT2 cells functions as a protective mechanism against allergic airway inflammation through controlling cell autophagy.

Function-specific IL-17A and dexamethasone interactions in primary human airway epithelial cells

Asthmatics have elevated levels of IL-17A compared to healthy controls. IL-17A is likely to contribute to reduced corticosteroid sensitivity of human airway epithelium. Here, we aimed to investigate the mechanistic underpinnings of this reduced sensitivity in more detail. Differentiated primary human airway epithelial cells (hAECs) were exposed to IL-17A in the absence or presence of dexamethasone. Cells were then collected for RNA sequencing analysis or used for barrier function experiments. Mucus was collected for volume measurement and basal medium for cytokine analysis. 2861 genes were differentially expressed by IL-17A (Padj < 0.05), of which the majority was not sensitive to dexamethasone (< 50% inhibition). IL-17A did inhibit canonical corticosteroid genes, such as HSD11B2 and FKBP5 (p < 0.05). Inflammatory and goblet cell metaplasia markers, cytokine secretion and mucus production were all induced by IL-17A, and these effects were not prevented by dexamethasone. Dexamethasone did reverse IL-17A-stimulated epithelial barrier disruption, and this was associated with gene expression changes related to cilia function and development. We conclude that IL-17A induces function-specific corticosteroid-insensitivity. Whereas inflammatory response genes and mucus production in primary hAECs in response to IL-17A were corticosteroid-insensitive, corticosteroids were able to reverse IL-17A-induced epithelial barrier disruption.

Dendritic cell immunoreceptor drives atopic dermatitis by modulating oxidized CaMKII-involved mast cell activation

Allergens have been identified as potential triggers in patients with atopic dermatitis (AD). AD patients are highly sensitive to cockroach allergen. The underlying mechanism, however, remains undetermined. Here, we established a cockroach allergen-induced AD-like mouse model and demonstrated that repeated exposure to cockroach allergen led to aggravated mouse skin inflammation, characterized by increased type 2 immunity, type 2 innate lymphoid cells (ILC2s), and mast cells. Increased skin mast cells were also observed in AD patients. AD mice with mast cell-deficient mice (kitW-sh/W-sh) showed diminished skin inflammation, suggesting that mast cells are required in allergen-induced skin inflammation. Furthermore, dendritic cell immuno-receptor (DCIR) is up-regulated in skin mast cells of AD patients and mediates allergen binding and uptake. DCIR-/- mice or reconstituted kitW-sh/W-sh mice with DCIR-/- mast cells showed a significant reduction in AD-like inflammation. Both in vitro and in vivo analyses demonstrated that DCIR-/- mast cells had reduced IgE-mediated mast cell activation and passive cutaneous anaphylaxis. Mechanistically, DCIR regulates allergen-induced IgE-mediated mast cell ROS generation and oxidation of calmodulin kinase II (ox-CaMKII). ROS-resistant CaMKII (MM-VVδ) prevents allergen-induced mast cell activation and inflammatory mediator release. Our study reveals a previously unrecognized DCIR-ROS-CaMKII axis that controls allergen-induced mast cell activation and AD-like inflammation.

JMJD3 deficiency alleviates lipopolysaccharide‑induced acute lung injury by inhibiting alveolar epithelial ferroptosis in a Nrf2‑dependent manner

Acute respiratory distress syndrome (ARDS) is a deadly illness which presents with severe hypoxemia as well as diffuse alveolar damage. Jumonji domain‑containing 3 (JMJD3), which belongs to the UTX/UTY JmjC‑domain protein subfamily, is involved in infection, development, aging and immune disorders. However, the role of JMJD3 in acute lung injury (ALI) is still unclear. The present study explored the roles and potential mechanisms of JMJD3 in ALI. Alveolar epithelial cell‑specific knockout of JMJD3 mice and A549 alveolar epithelial cells were used to investigate the function of JMJD3 in ALI. Lipopolysaccharide (LPS) was used to establish an in vivo and in vitro ALI model. The expression of JMJD3 in murine lung tissue and alveolar epithelial cells was detected. Pathological injury of lung tissue and alveolar epithelial cells was also investigated following inhibition of JMJD3. The results showed that JMJD3 expression was significantly increased in murine lung tissues and in A549 cells following LPS stimulation. JMJD3‑deficient mice in alveolar epithelial cells exhibited alleviated lung pathological injury and ferroptosis following h stimulation. Mechanistically, it was found that JMJD3 knockout could increase the expression of nuclear factor erythroid‑2‑related factor‑2 (Nrf2) in lung tissues challenged with h. However, Nrf2 overexpression by adenovirus could further enhance the anti‑ferroptotic effect from JMJD3 silence in h‑treated A549 cells. Taken together, the present study revealed that JMJD3 deficiency may relieve LPS‑induced ALI by blocking alveolar epithelial ferroptosis in a Nrf2‑dependent manner, which may serve as a novel therapeutic target against ALI.