FoxO1 is a critical regulator of M2-like macrophage activation in allergic asthma

Total alkaloids in Fritillaria cirrhosa D. Don alleviate OVA-induced allergic asthma by inhibiting M2 macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Fritillaria cirrhosa D. Don (FCD) is a traditional Chinese medicine used to treat respiratory disorders, known for its effects in clearing heat, moistening the lungs, resolving phlegm, and relieving cough. Additionally, the total alkaloids extracted from FCD can alleviate asthma symptoms and reduce airway inflammation. However, no studies have investigated the effects of total alkaloids on lung macrophages.

AIM OF THE STUDY

This study explored whether the total alkaloids of FCD (TAs-FCD) reduce M2 macrophage polarization and, consequently, attenuate airway remodeling in asthmatic mice. This study further elucidated its mechanism of action in treating allergic asthma.

MATERIALS AND METHODS

The extracted TAs-FCD was analyzed for its composition using UPLC-Q-TOF/MS. Network pharmacology was employed to identify the active ingredients and potential mechanisms of TAs-FCD in the treatment of allergic asthma. A mouse model of ovalbumin-induced allergic asthma was established, adopted, and validated through in vivo experiments. Hematoxylin-eosin staining (H&E), immunohistochemistry (IHC), immunofluorescence staining (IF), enzyme-linked immunosorbent assay (ELISA), Western blotting (WB), and real-time fluorescence quantitative polymerase chain reaction (q-PCR) were used to investigate the role of TAs-FCD in inhibiting M2 macrophage polarization in the context of allergic asthma.

RESULTS

A total of 66 active ingredients were screened from 116 compounds using SWISSADME. The targets of these 66 compounds were predicted by SwissTargetPrediction, resulting in 808 unique drug targets after excluding duplicates. Additionally, 1756 targets related to allergic asthma were identified from the DisGeNET, Genecard, and OMIM databases. This led to 267 cross-targets between the active ingredient targets and allergic asthma targets, including interleukin (IL)-1β, tumor necrosis factor (TNF), and STAT3. Animal experiments demonstrated that TAs-FCD improved histopathological injury in mouse lungs, reduced peri-airway collagen fiber accumulation, airway mucus secretion, and airway smooth muscle proliferation. TAs-FCD also lowered IL-1β, TNF-α and IL-4 levels in lung tissues and alleviated airway inflammation. Furthermore, TAs-FCD significantly reduced levels of Arg1 and CD206, which are closely associated with M2 macrophages, and downregulated the expression of p-STAT3 and p-JAK2.

CONCLUSION

TAs-FCD may inhibit M2 macrophage polarization by regulating the JAK2/STAT3 pathway, thereby alleviating airway remodeling and inflammation in allergic asthmatic mice.

SIRT5 exacerbates eosinophilic chronic rhinosinusitis by promoting polarization of M2 macrophage

BACKGROUND

Previous studies implied that local M2 polarization of macrophage promoted mucosal edema and exacerbated TH2 type inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP). However, the specific pathogenic role of M2 macrophages and the intrinsic regulators in the development of CRS remains elusive.

OBJECTIVE

We sought to investigate the regulatory role of SIRT5 in the polarization of M2 macrophages and its potential contribution to the development of CRSwNP.

METHODS

Real-time reverse transcription-quantitative PCR and Western blot analyses were performed to examine the expression levels of SIRT5 and markers of M2 macrophages in sinonasal mucosa samples obtained from both CRS and control groups. Wild-type and Sirt5-knockout mice were used to establish a nasal polyp model with TH2 inflammation and to investigate the effects of SIRT5 in macrophage on disease development. Furthermore, in vitro experiments were conducted to elucidate the regulatory role of SIRT5 in polarization of M2 macrophages.

RESULTS

Clinical investigations showed that SIRT5 was highly expressed and positively correlated with M2 macrophage markers in eosinophilic polyps. The expression of SIRT5 in M2 macrophages was found to contribute to the development of the disease, which was impaired in Sirt5-deficient mice. Mechanistically, SIRT5 was shown to enhance the alternative polarization of macrophages by promoting glutaminolysis.

CONCLUSIONS

SIRT5 plays a crucial role in promoting the development of CRSwNP by supporting alternative polarization of macrophages, thus providing a potential target for CRSwNP interventions.

Functional Polymorphisms Regulate FOXO1 Transcript Expression and Contribute to the Risk and Symptom Severity of HDM-Induced Allergic Rhinitis

INTRODUCTION

FOXO1 plays an important role in regulating immune processes that contribute to allergic inflammation; however, genetic variants influencing FOXO1 expression in AR pathogenesis remains unclear. This study aimed to investigate the functional effect of FOXO1 single nucleotide polymorphisms (SNPs) on AR development by performing genetic association and functional analysis studies.

METHODS

This study belongs to a part of an ongoing Singapore/Malaysia cross-sectional genetics and epidemiological study (SMCSGES). We assessed the associations of FOXO1 transcript expression levels in peripheral blood mononuclear cells (PBMC) with AR phenotype, total nasal symptom score (TNSS), and SNP genotype in a sub-cohort of n = 658 individuals from the SMCSGES population. Associations of FOXO1 SNPs with AR were assessed in a cohort of n = 5,072 individuals from the SMCSGES population. In vitro promoter luciferase assay was used to evaluate the effect of AR-associated SNPs on FOXO1 promoter activity.

RESULTS

FOXO1 transcript expression in PBMC was significantly associated with the risk of AR (p < 0.05) and TNSS among AR patients (p < 0.0001). We identified a significant association between tag-SNPs rs9549246 and FOXO1 transcript expression in PBMC from the SMCSGES sub-cohort and the multiethnic eQTLGen consortium (false discovery rate-adjusted p < 0.05). The minor allele "A" of tag-SNP rs9549246 was significantly associated with a higher risk of AR (p = 0.04422, odds ratio = 1.21, 95% confidence interval = 1.01-1.45) in the SMCSGES genotyping cohort (n = 5,072). In vitro luciferase assay showed the minor allele "A" of rs35594717 (tagged by rs9549246) was significantly associated with a higher FOXO1 promoter activity (p < 0.05).

CONCLUSION

FOXO1 transcript expression in PBMC has a strong association with the risk and symptom severity of AR. Genetic variants tagged by rs9549246 were shown to affect the expression of FOXO1 and contribute to the development of AR in the SMCSGES population.

Unwinding circular RNA's role in inflammatory pulmonary diseases

Circular RNAs (circRNAs) have emerged as pivotal regulators of gene expression and cellular processes in various physiological and pathological conditions. In recent years, there has been a growing interest in investigating the role of circRNAs in inflammatory lung diseases, owing to their potential to modulate inflammation-associated pathways and contribute to disease pathogenesis. Inflammatory lung diseases, like asthma, chronic obstructive pulmonary disease (COPD), and COVID-19, pose significant global health challenges. The dysregulation of inflammatory responses demonstrates a pivotal function in advancing these diseases. CircRNAs have been identified as important players in regulating inflammation by functioning as miRNA sponges, engaging with RNA-binding proteins, and participating in intricate ceRNA networks. These interactions enable circRNAs to regulate the manifestation of key inflammatory genes and signaling pathways. Furthermore, emerging evidence suggests that specific circRNAs are differentially expressed in response to inflammatory stimuli and exhibit distinct patterns in various lung diseases. Their involvement in immune cell activation, cytokine production, and tissue remodeling processes underscores their possible capabilities as therapeutic targets and diagnostic biomarkers. Harnessing the knowledge of circRNA-mediated regulation in inflammatory lung diseases could lead to the development of innovative strategies for disease management and intervention. This review summarizes the current understanding of the role of circRNAs in inflammatory lung diseases, focusing on their regulatory mechanisms and functional implications.

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Expression of constitutively active TβRI leads to attenuation of ovalbumin-induced allergic airway inflammation associated with augmented M2 polarization of alveolar macrophage

BACKGROUND

Transforming growth factor-β (Tgf-β) plays an important role in the pathogenesis of asthma through the regulation of T cells and airway epithelium. Its functions in alveolar macrophage (AM) during allergic airway inflammation remain unknown.

METHODS

A murine asthma model was induced with ovalbumin (ova) in TβRICA/Fsp1-Cre transgenic mice expressing constitutively active Tgf-β receptor type I (TβRICA) under the control of Fsp1-Cre transgene. Cells in the bronchoalveolar lavage (BAL) were collected to study immune cell infiltration in the lungs. Cytokine levels in BAL fluid were measured by enzyme-linked immunoassay (ELISA). Lungs were sectioned and stained with hematoxylin and eosin, periodic acid-Schiff, and trichrome for histopathologic evaluation. AMs were assessed by flow cytometry and were sorted for quantitative polymerase chain reaction analysis.

RESULTS

Our data indicated that TβRICA transcripts were induced in AMs of TβRICA/Fsp1-Cre mice. Following the ova challenges, TβRICA/Fsp1-Cre mice exhibited reduced cellular infiltration of the airway, reduced pulmonary fibrosis, and reduced bronchial mucus secretion as compared to ova-challenged wild-type mice. An alternatively activated macrophage (M2) polarization was significantly elevated in the lungs of ova-challenged TβRICA/Fsp1-Cre mice as reflected by increased numbers of AMs expressing M2 subtype marker, CD163, in the lungs and enhanced expression of CCR2 and CD206 in AMs. Moreover, TβRICA/Fsp1-Cre AMs showed augmented expression of transcription factors, Foxo1, and IRF4, which are known to be positive regulators for M2 polarization.

CONCLUSIONS

Expression of TβRICA in AMs promoted M2 polarization and ameliorated allergic airway inflammation in an ova-induced asthma mouse model.

Investigating Forkhead Box O Transcription Factor 1 Gene's Relation to Immunoglobulin E in House Dust Mite-Allergic Asthma Patients

House dust mite (HDM)-allergic asthma is an abnormal immune response to extrinsic aeroallergens found in human vicinities. Studying the role of the associated immunity biomarkers and their interplay helps in discovering novel therapeutic strategies that can be used in adjunct with effective long-term immunotherapy. This study investigates the total serum IgE, FoxO1, and Sirtuin 1 (SIRT1) gene expressions in HDM-allergic asthma patients. We enrolled 40 patients for each of the following three groups: an HV group of healthy volunteers and HDM/AA and HDM/SCIT groups of HDM-allergic asthma patients who did not and who did receive immunotherapy before recruitment in this study, respectively. The results elucidated that total IgE was strikingly elevated in the HDM/AA group and showed little decline in the HDM/SCIT group. Both FoxO1 and SIRT1 gene expressions showed the highest levels in the HDM/SCIT group. There was a negative correlation between total IgE and both FoxO1 and SIRT1 in the HDM/AA group while there was a positive correlation with SIRT1 in the HDM/SCIT group. In conclusion, the interplay of the three immunity biomarkers related to HDM-allergic asthma after the course of immunotherapy treatment suggests further, broader studies on the feasibility of their role as immunity biomarkers in the control and remission of HDM-allergic asthma.

Sex-specific lung inflammation and mitochondrial damage in a model of electronic cigarette exposure in asthma

The prevalence of electronic cigarette (EC) use among adult with asthma has continued to increase over time, in part due to the belief of being less harmful than smoking. However, the extent of their toxicity and the involved mechanisms contributing to the deleterious impact of EC exposure on patients with preexisting asthma have not been delineated. In the present project, we tested the hypothesis that EC use contributes to respiratory damage and worsening inflammation in the lungs of patients with asthma. To define the consequences of EC exposure in established asthma, we used a mouse model with/without preexisting asthma for short-term exposure to EC aerosols. C57/BL6J mice were sensitized and challenged with a DRA (dust mite, ragweed, Aspergillus fumigates, 200 µg/mL) mixture and exposed daily to EC with nicotine (2% nicotine in 30:70 propylene glycol: vegetable glycerin) or filtered air for 2 wk. The mice were evaluated at 24 h after the final EC exposure. After EC exposure in asthmatic mice, lung inflammatory cell infiltration and goblet cell hyperplasia were increased, whereas EC alone did not cause airway inflammation. Our data also show that mitochondrial DNA (mtDNA) content and a key mtDNA regulator, mitochondrial transcription factor A (TFAM), are reduced in asthmatic EC-exposed mice in a sex-dependent manner. Together, these results indicate that TFAM loss in lung epithelium following EC contributes to male-predominant sex pathological differences, including mitochondrial damage, inflammation, and remodeling in asthmatic airways.NEW & NOTEWORTHY Respiratory immunity is dysregulated in preexisting asthma, and further perturbations by EC use could exacerbate asthma severity. However, the extent of their toxicity and the involved mechanisms contributing to the deleterious impact of EC exposure on patients with preexisting asthma have not been delineated. We found that EC has unique biological impacts in lungs and potential sex differences with loss of TFAM, a key mtDNA regulator, in lung epithelial region from our animal EC study.

Canonical and non-canonical functions of NLRP3

BACKGROUND

Since its discovery, NLRP3 is almost never separated from its major role in the protein complex it forms with ASC, NEK7 and Caspase-1, the inflammasome. This key component of the innate immune response mediates the secretion of proinflammatory cytokines IL-1β and IL-18 involved in immune response to microbial infection and cellular damage. However, NLRP3 has also other functions that do not involve the inflammasome assembly nor the innate immune response. These non-canonical functions have been poorly studied. Nevertheless, NLRP3 is associated with different kind of diseases probably through its inflammasome dependent function as through its inflammasome independent functions.

AIM OF THE REVIEW

The study and understanding of the canonical and non-canonical functions of NLRP3 can help to better understand its involvement in various pathologies. In parallel, the description of the mechanisms of action and regulation of its various functions, can allow the identification of new therapeutic strategies.

KEY SCIENTIFIC CONCEPTS OF THE REVIEW

NLRP3 functions have mainly been studied in the context of the inflammasome, in myeloid cells and in totally deficient transgenic mice. However, for several year, the work of different teams has proven that NLRP3 is also expressed in other cell types where it has functions that are independent of the inflammasome. If these studies suggest that NLRP3 could play different roles in the cytoplasm or the nucleus of the cells, the mechanisms underlying NLRP3 non-canonical functions remain unclear. This is why we propose in this review an inventory of the canonical and non-canonical functions of NLRP3 and their impact in different pathologies.

FOXO1 orchestrates the intestinal homeostasis via neuronal signaling in group 3 innate lymphoid cells

The neuro-immune regulation is associated with homeostasis of the intestine. Intestinal group 3 innate lymphoid cells (ILC3s) are tissue-resident lymphocytes whose functions are affected by the intestine niche. However, how a gut neuronal signal coordinates the immune response of ILC3s is largely unknown. Here, we found that cyclic adenosine monophosphate (cAMP) signaling exacerbated the inflammatory response and attenuated the expression level of the transcription factor forkhead box O1 (FOXO1) in ILC3s. Deficiency of FOXO1 drove the hyperactivation of ILC3s and resulted in gut inflammation independently of T cells. Mechanistically, FOXO1 promoted the transcription of neuropeptide receptor VIPR2 and inhibited the transcription of adrenoceptor ADRA2A in ILC3s. FOXO1-related regulation of VIPR2 and ADRA2A signaling balanced the activation of ILC3s under steady condition or during colitis. Moreover, chronic stress elevated cAMP level and downregulated FOXO1 level, exacerbating intestinal inflammation. Our findings reveal that FOXO1 balances the activation of ILC3s via VIP and adrenergic signaling and regulates intestinal homeostasis.

Macrophages Orchestrate Airway Inflammation, Remodeling, and Resolution in Asthma

Asthma is a heterogenous chronic inflammatory lung disease with endotypes that manifest different immune system profiles, severity, and responses to current therapies. Regardless of endotype, asthma features increased immune cell infiltration, inflammatory cytokine release, and airway remodeling. Lung macrophages are also heterogenous in that there are separate subsets and, depending on the environment, different effector functions. Lung macrophages are important in recruitment of immune cells such as eosinophils, neutrophils, and monocytes that enhance allergic inflammation and initiate T helper cell responses. Persistent lung remodeling including mucus hypersecretion, increased airway smooth muscle mass, and airway fibrosis contributes to progressive lung function decline that is insensitive to current asthma treatments. Macrophages secrete inflammatory mediators that induce airway inflammation and remodeling. Additionally, lung macrophages are instrumental in protecting against pathogens and play a critical role in resolution of inflammation and return to homeostasis. This review summarizes current literature detailing the roles and existing knowledge gaps for macrophages as key inflammatory orchestrators in asthma pathogenesis. We also raise the idea that modulating inflammatory responses in lung macrophages is important for alleviating asthma.

Constructing ferroptosis-related competing endogenous RNA networks and exploring potential biomarkers correlated with immune infiltration cells in asthma using combinative bioinformatics strategy

BACKGROUND

Asthma is a common chronic respiratory disease worldwide. Recent studies have revealed the critical effects of the ceRNA network and ferroptosis on patients with asthma. Thus, this study aimed to explore the potential ferroptosis-related ceRNA network, investigate the immune cell infiltration level in asthma through integrated analysis of public asthma microarray datasets, and find suitable diagnostic biomarkers for asthma.

METHODS

First, three asthma-related datasets which were downloaded from the Gene Expression Omnibus (GEO) database were integrated into one pooled dataset after correcting for batch effects. Next, we screened differentially expressed lncRNAs (DElncRNAs) between patients and healthy subjects, constructed a ceRNA network using the StarBase database and screened ferroptosis-related genes from the predicted target mRNAs for Disease Ontology (DO), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. We also performed Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) on the batch effect-corrected mRNA expression profile. Then, Least Absolute Shrinkage and Selection Operator (LASSO) regression was used to screen potential diagnostic biomarkers, and the diagnostic efficacy was assessed using a receiver operating characteristic (ROC) curve. Finally, we determined the proportion of 22 immune cells in patients with asthma using CIBERSORT and investigated the correlation between key RNAs and immune cells.

RESULTS

We obtained 19 DElncRNAs, of which only LUCAT1 and MIR222HG had corresponding target miRNAs. The differentially expressed ferroptosis-related genes were involved in multiple programmed cell death-related pathways. We also found that the mRNA expression profile was primarily enriched in innate immune system responses. We screened seven candidate diagnostic biomarkers for asthma using LASSO regression (namely, BCL10, CD300E, IER2, MMP13, OAF, TBC1D3, and TMEM151A), among which the area under the curve (AUC) value for CD300E and IER2 were 0.722 and 0.856, respectively. Finally, we revealed the infiltration ratio of different immune cells in asthma and found a correlation between LUCAT1, MIR222HG, CD300E, and IER2 with some immune cells.

CONCLUSION

This study explored a potential lncRNA-miRNA-mRNA regulatory network and its underlying diagnostic biomarkers (CD300E and IER2) in asthma and identified the immune cells most associated with them, providing possible diagnostic markers and immunotherapeutic targets for asthma.

Myeloid-specific fatty acid transport protein 4 deficiency induces a sex-dimorphic susceptibility for nonalcoholic steatohepatitis in mice fed a high-fat, high-cholesterol diet

Newborns with FATP4 mutations exhibit ichthyosis prematurity syndrome (IPS), and adult patients show skin hyperkeratosis, allergies, and eosinophilia. We have previously shown that the polarization of macrophages is altered by FATP4 deficiency; however, the role of myeloid FATP4 in the pathogenesis of nonalcoholic steatohepatitis (NASH) is not known. We herein phenotyped myeloid-specific Fatp4-deficient (Fatp4M-/-) mice under chow and high-fat, high-cholesterol (HFHC) diet. Bone-marrow-derived macrophages (BMDMs) from Fatp4M-/- mice showed significant reduction in cellular sphingolipids in males and females, and additionally phospholipids in females. BMDMs and Kupffer cells from Fatp4M-/- mice exhibited increased LPS-dependent activation of proinflammatory cytokines and transcription factors PPARγ, CEBPα, and p-FoxO1. Correspondingly, these mutants under chow diet displayed thrombocytopenia, splenomegaly, and elevated liver enzymes. After HFHC feeding, Fatp4M-/- mice showed increased MCP-1 expression in livers and subcutaneous fat. Plasma MCP-1, IL4, and IL13 levels were elevated in male and female mutants, and female mutants additionally showed elevation of IL5 and IL6. After HFHC feeding, male mutants showed an increase in hepatic steatosis and inflammation, whereas female mutants showed a greater severity in hepatic fibrosis associated with immune cell infiltration. Thus, myeloid-FATP4 deficiency led to steatotic and inflammatory NASH in males and females, respectively. Our work offers some implications for patients with FATP4 mutations and also highlights considerations in the design of sex-targeted therapies for NASH treatment.NEW & NOTEWORTHY FATP4 deficiency in BMDMs and Kupffer cells led to increased proinflammatory response. Fatp4M-/- mice displayed thrombocytopenia, splenomegaly, and elevated liver enzymes. In response to HFHC feeding, male mutants were prone to hepatic steatosis, whereas female mutants showed exaggerated fibrosis. Our study provides insights into a sex-dimorphic susceptibility to NASH by myeloid-FATP4 deficiency.

Calcaratarin D, a labdane diterpenoid, attenuates mouse asthma via modulating alveolar macrophage function

BACKGROUND AND PURPOSE

Alveolar macrophages (AMs) contribute to airway inflammation and remodelling in allergic asthma. Calcaratarin D (CalD), a labdane diterpenoid from rhizomes of the medicinal plant Alpinia calcarata, has recently been shown to possess anti-inflammatory properties. The present study evaluated protective effects of CalD in a house dust mite (HDM)-induced asthma mouse model.

EXPERIMENTAL APPROACH

The effects of CalD on AMs in contributing to anti-inflammatory effects in asthma were investigated through in vivo, ex vivo, and in vitro experiments.

KEY RESULTS

CalD reduced total bronchoalveolar lavage fluid and differential cell count, serum IgE levels, mucus hypersecretion, and airway hyperresponsiveness in HDM-challenged mice. Additionally, CalD affected a wide array of pro-inflammatory cytokines and chemokines and oxidative damage markers in isolated lung tissues. CalD suppressed the HDM-induced increase in Arg1 (M2 macrophage marker) in AMs from lung tissue and reduced lung polyamine levels. CalD weakened antigen presentation capability of AMs by reducing CD80 expression, reduced AM-derived CCL17 and CCL22 levels, and lessened Th2 cytokines from CD4⁺ T-cells from asthma lung digest. CalD blocked the HDM-induced FoxO1/IRF4 pathway and restored impaired the Nrf2/HO-1 antioxidant pathway in lung tissues. CalD inhibited IL-4/IL-13-stimulated JAK1/STAT6 pathway, FoxO1 protein expression, and chemokine production in primary AMs. Structure-activity relationship study revealed the α,β-unsaturated γ-butyrolactone in CalD is capable of forming covalent bonds with cellular protein targets essential for its action.

CONCLUSION AND IMPLICATIONS

Our results demonstrate for the first time that CalD is a novel anti-inflammatory natural compound for allergic asthma that modulates AM function.

Resident macrophages of the lung and liver: The guardians of our tissues

Resident macrophages play a unique role in the maintenance of tissue function. As phagocytes, they are an essential first line defenders against pathogens and much of the initial characterization of these cells was focused on their interaction with viral and bacterial pathogens. However, these cells are increasingly recognized as contributing to more than just host defense. Through cytokine production, receptor engagement and gap junction communication resident macrophages tune tissue inflammatory tone, influence adaptive immune cell phenotype and regulate tissue structure and function. This review highlights resident macrophages in the liver and lung as they hold unique roles in the maintenance of the interface between the circulatory system and the external environment. As such, we detail the developmental origin of these cells, their contribution to host defense and the array of tools these cells use to regulate tissue homeostasis.

Non-invasive sampling procedure revealing the molecular events at different abutments of bone-anchored hearing systems–A prospective clinical pilot study

Purpose

To investigate the molecular activities in different compartments around the bone-anchored hearing system (BAHS) with either electropolished or machined abutments and to correlate these activities with clinical and microbiological findings.

Materials and methods

Twelve patients received machined or electropolished abutments after implant installation of BAHS. Peri-abutment fluid and tissue were collected from baseline to 12 months. Gene expression of cytokines and factors related to tissue healing and inflammation, regeneration and remodelling, as well as bacterial recognition were determined using quantitative-polymerase chain reaction (qPCR). The clinical status was evaluated using the Holgers scoring system, and bacterial colonisation was investigated by culturing.

Results

The gene expression of inflammatory cytokines (IL-8, IL-1β, and IL-10) and bacteria-related Toll-like receptors (2 and 4) was higher in the peri-abutment fluid than at baseline and in the peri-abutment tissue at 3 and 12 months. Conversely, the expression of genes related to tissue regeneration (Coll1a1 and FOXO1) was higher in the tissue samples than in the peri-abutment fluid at 3 and 12 months. Electropolished abutments triggered higher expression of inflammatory cytokines (IL-8 and IL-1β) (in peri-abutment fluid) and regeneration factor FOXO1 (in peri-abutment tissue) than machined abutments. Several cytokine genes in the peri-abutment fluid correlated positively with the detection of aerobes, anaerobes and Staphylococcus species, as well as with high Holger scores.

Conclusion

This study provides unprecedented molecular information on the biological processes of BAHS. Despite being apparently healed, the peri-abutment fluid harbours prolonged inflammatory activity in conjunction with the presence of different bacterial species. An electropolished abutment surface appears to be associated with stronger proinflammatory activity than that with a machined surface. The analysis of the peri-abutment fluid deserves further verification as a non-invasive sampling and diagnostic procedure of BAHS.

The Essential Role of FoxO1 in the Regulation of Macrophage Function

Macrophages are widely distributed in various tissues and organs. They not only participate in the regulation of innate and adaptive immune response, but also play an important role in tissue homeostasis. Dysregulation of macrophage function is closely related to the initiation, development and prognosis of multiple diseases, including infection and tumorigenesis. Forkhead box transcription factor O1 (FoxO1) is an important member among the forkhead box transcription factor family. Through directly binding to the promoter regions of downstream target genes, FoxO1 is implicated in cell proliferation, apoptosis, metabolic activities and other biological processes. In this review, we summarized the regulatory role of FoxO1 in macrophage phagocytosis, migration, differentiation and inflammatory activation. We also emphasized that macrophage reciprocally modulated FoxO1 activity via a post-translational modification (PTM) dominant manner.

Targeting ETosis by miR-155 inhibition mitigates mixed granulocytic asthmatic lung inflammation

Asthma is phenotypically heterogeneous with several distinctive pathological mechanistic pathways. Previous studies indicate that neutrophilic asthma has a poor response to standard asthma treatments comprising inhaled corticosteroids. Therefore, it is important to identify critical factors that contribute to increased numbers of neutrophils in asthma patients whose symptoms are poorly controlled by conventional therapy. Leukocytes release chromatin fibers, referred to as extracellular traps (ETs) consisting of double-stranded (ds) DNA, histones, and granule contents. Excessive components of ETs contribute to the pathophysiology of asthma; however, it is unclear how ETs drive asthma phenotypes and whether they could be a potential therapeutic target. We employed a mouse model of severe asthma that recapitulates the intricate immune responses of neutrophilic and eosinophilic airway inflammation identified in patients with severe asthma. We used both a pharmacologic approach using miR-155 inhibitor-laden exosomes and genetic approaches using miR-155 knockout mice. Our data show that ETs are present in the bronchoalveolar lavage fluid of patients with mild asthma subjected to experimental subsegmental bronchoprovocation to an allergen and a severe asthma mouse model, which resembles the complex immune responses identified in severe human asthma. Furthermore, we show that miR-155 contributes to the extracellular release of dsDNA, which exacerbates allergic lung inflammation, and the inhibition of miR-155 results in therapeutic benefit in severe asthma mice. Our findings show that targeting dsDNA release represents an attractive therapeutic target for mitigating neutrophilic asthma phenotype, which is clinically refractory to standard care.

Vitamin D3 reverses the transcriptional profile of offspring CD4+ T lymphocytes exposed to intrauterine inflammation

Chorioamnionitis profoundly influences multiple fetal organs as well as the immune system. Maternal vitamin D (VitD) supplementation may modulate the immune function of offspring. Here, we sought to uncover the immunomodulatory potential of intrauterine inflammation and VitD in offspring CD4⁺ T cells. Pregnant C57BL/6 mice were treated with intrauterine lipopolysaccharide (LPS) injections, with or without VitD. Splenic CD4⁺ T cells were negatively selected using anti-biotin microbeads at 28 days after birth. Differentially expressed genes (DEGs) in the offspring CD4⁺ T cells were identified via RNA sequencing. In total, 181 DEGs induced by LPS exposure were identified in offspring CD4⁺ T cells. Furthermore, 2461 DEGs were detected after VitD supplementation in addition to LPS exposure. VitD supplementation showed an unexpected ability to counteract the LPS-induced transcriptional responses. VitD supplementation downregulated lymphocyte differentiation (GO: 0030098) and lymphocyte activation (GO: 0046649), and upregulated the responses to viruses (GO: 0009615) and bacteria (GO:0009617) in offspring CD4⁺ T cells with intrauterine LPS exposure. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that several pathways, including the T cell receptor signaling pathway, the mitogen-activated protein kinase (MAPK) signaling pathway, Th17 cell differentiation, and autophagy, were downregulated by intrauterine VitD intervention following LPS exposure. Subsequently, we confirmed the counteracting effect of VitD against LPS on the expression of several genes (Insr, Foxo1, and Peli1) using qRT-PCR and western blot analyses. We also demonstrated that intrauterine VitD supplementation interferes with offspring Th17 cell differentiation induced by intrauterine LPS exposure. Our study revealed that VitD reverses the transcriptional and Th17 differential profiles of offspring CD4⁺ T lymphocytes induced by intrauterine LPS, and indicated the contribution of maternal VitD supplementation to immune protection in offspring affected by intrauterine inflammation.

The hMeDIP-Seq identified INPP4A as a novel biomarker for eosinophilic chronic rhinosinusitis with nasal polyps

Background: Eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) is an endotype of chronic rhinosinusitis with nasal polyps characterized by more severe symptoms, a stronger association with asthma and a greater recurrence risk. It is unknown whether DNA hydroxymethylation could influence ECRSwNP. Methods: Hydroxymethylated DNA immunoprecipitation sequencing was carried out in three distinct groups (control, ECRSwNP and NECRSwNP). Additional qRT-PCR, immunohistochemistry and analysis of the receiver operating characteristic curve were performed. Results: Between ECRSwNP and NECRSwNP, 26 genes exhibited differential DNA hydroxymethylation. Consistent with their hydroxymethylation level, GNAL, INPP4A and IRF4 expression levels were significantly different between ECRSwNP and the other two groups. The receiver operating characteristic curve revealed that INPP4A mRNA has a high predictive accuracy for ECRSwNP. Conclusion: DNA hydroxymethylation regulates the expression of multiple genes in ECRSwNP. INPP4A mRNA was markedly decreased in ECRSwNP polyps and can predict ECRSwNP.

Propofol alleviates postoperative cognitive dysfunction by inhibiting inflammation via up-regulating miR-223-3p in aged rats

OBJECTIVE

Postoperative cognitive dysfunction (POCD) affects 15-25% of surgical patients and causes significant morbidity and mortality. This study aims to investigate the mechanism of propofol reducing POCD in aged rats.

METHOD

Rats in Operate group and Propofol group were anesthetized with isoflurane and propofol, respectively, and then underwent cardiac surgery. Rats in Antagomir group were anesthetized with propofol and underwent cardiac surgery with preoperative injection of miR-223-3p antagomir. Barnes maze and Morris water maze (MWM) were used to test spatial learning and memory of rats. Immunofluorescence was used to detect the level of microglial cell marker IBA1. In addition, qRT-PCR was performed to measure the expression of miR-223-3p and inflammatory factors TNF-α, IL-1β and IL-6. Western blotting was conducted to detect the protein expression of Foxo1, TNF-α, IL-1β and IL-6.

RESULT

Isoflurane-anesthetized rats undergoing cardiac surgery showed significantly reduced spatial learning and memory, promoted microglia activation, decreased miR-223-3p expression and increased inflammatory response in the hippocampus, while isoflurane-anesthetized rats without surgery showed insignificant changes in these indices. Compared to isoflurane anesthesia, propofol anesthesia exhibited less effect on spatial learning and memory of rats with cardiac surgery and contributed to a relative reduction in activated microglia in the hippocampus, a notable increase in miR-223-3p expression, and a decrease in inflammation. The results were reversed after miR-223-3p antagomir was injected into propofol-anesthetized surgical rats. miR-223-3p negatively regulated Foxo1 to suppress the expression of inflammatory factors.

CONCLUSION

Propofol reduced inflammation by up-regulating miR-223-3p, thereby reducing POCD in aged rats.

Vagal-α7nAChR signaling is required for lung anti-inflammatory responses and arginase 1 expression during an influenza infection

Vagal circuit-α7 nicotinic acetylcholine receptor (α7nAChR, coded by Chrna7) signaling can modulate lung proinflammatory responses. Arginase 1 (ARG1) plays a crucial role in the resolution of lung inflammation. However, whether vagal-α7nAChR signaling can regulate lung inflammation and ARG1 expression during an influenza infection is elusive. Here, we found that lung and spleen IL-4+ cells and lung ARG1 expression were reduced; however, bronchoalveolar lavage (BAL) protein and leukocytes and lung inflammatory cytokines were increased in PR8 (A/Puerto Rico/8/1934, H1N1)-infected vagotomized mice when compared to the control. In PR8-infected α7nAChR-deficient mice, lung Arg1, Il10, and Socs3 expression and BAL Ly6C+CD206+ cells were reduced. PR8-infected Chrna7+/+ recipient mice reconstituted with Chrna7-/- bone marrow had a lower survival as compared to PR8-infected Chrna7+/+ recipient mice reconstituted with Chrna7+/+ bone marrow. Mechanistically, the activation of α7nAChR by its agonist GTS-21 could enhance IL-4-induced Arg1 expression, reduced Nos2, and TNF-α expression in PR8-infected bone marrow-derived macrophages (BMDM). Stimulation with IL-4 increased phosphorylation of STAT6 and activation of α7nAChR increased STAT6 binding with the ARG1 promoter and relieved IL-4-induced H3K27me3 methylation by increasing JMJD3 expression in PR8-infected BMDM. Inhibition of JMJD3 increased H3K27me3 methylation and abolished α7nAChR activation and IL-4 induced ARG1 expression. Activation of α7nAChR also reduced phosphorylation of AKT1 and contained FOXO1 in the nucleus. Knockdown of Foxo1a reduced α7nAChR activation and IL-4 induced Arg1 expression in PR8-infected BMDM. Therefore, vagal-α7nAChR signaling is a novel therapeutic target for treating lung inflammatory responses during an influenza infection.

On Deep Landscape Exploration of COVID-19 Patients Cells and Severity Markers

COVID-19 is a disease with a spectrum of clinical responses ranging from moderate to critical. To study and control its effects, a large number of researchers are focused on two substantial aims. On the one hand, the discovery of diverse biomarkers to classify and potentially anticipate the disease severity of patients. These biomarkers could serve as a medical criterion to prioritize attention to those patients with higher prone to severe responses. On the other hand, understanding how the immune system orchestrates its responses in this spectrum of disease severities is a fundamental issue required to design new and optimized therapeutic strategies. In this work, using single-cell RNAseq of bronchoalveolar lavage fluid of nine patients with COVID-19 and three healthy controls, we contribute to both aspects. First, we presented computational supervised machine-learning models with high accuracy in classifying the disease severity (moderate and severe) in patients with COVID-19 starting from single-cell data from bronchoalveolar lavage fluid. Second, we identified regulatory mechanisms from the heterogeneous cell populations in the lungs microenvironment that correlated with different clinical responses. Given the results, patients with moderate COVID-19 symptoms showed an activation/inactivation profile for their analyzed cells leading to a sequential and innocuous immune response. In comparison, severe patients might be promoting cytotoxic and pro-inflammatory responses in a systemic fashion involving epithelial and immune cells without the possibility to develop viral clearance and immune memory. Consequently, we present an in-depth landscape analysis of how transcriptional factors and pathways from these heterogeneous populations can regulate their expression to promote or restrain an effective immune response directly linked to the patients prognosis.

Isoalantolactone alleviates ovalbumin‑induced asthmatic inflammation by reducing alternatively activated macrophage and STAT6/PPAR‑γ/KLF4 signals

Isoalantolactone (IAL), a sesquiterpene lactone, has anti‑inflammatory activity in lipopolysaccharide (LPS)‑induced sepsis. However, it remains to be elucidated whether IAL influences asthmatic inflammation. The present study found that IAL inhibited ovalbumin (OVA)‑induced asthmatic inflammation and attenuated OVA‑induced eosinophil infiltration, immunoglobulin E generation and the production of interleukin (IL)‑4, IL‑5, C‑C motif chemokine ligand (CCL)17 and CCL22. In addition, IAL treatment with IL‑4 reduced the expression of arginase‑1, Ym‑1, CCL17 and CCL22 in bone marrow‑derived macrophages in vitro. Furthermore, IAL inhibited IL‑4‑induced STAT6 phosphorylation and the expression of peroxisome proliferator‑activated receptor γ and Krüppel‑like factor 4. Collectively, the results suggested that IAL attenuated asthmatic inflammation and is a potential therapeutic agent for the treatment of asthma.

CSF1/CSF1R-mediated Crosstalk Between Choroidal Vascular Endothelial Cells and Macrophages Promotes Choroidal Neovascularization

Purpose

This study examined the role of the CSF1/CSF1Raxis in the crosstalk between choroidal vascular endothelial cells (CVECs) and macrophages during the formation of choroidal neovascularization (CNV).

Methods

Quantitative reverse transcriptase (QRT)-PCR, Western blot and ELISA measured the production and release of CSF1 from human choroidal vascular endothelial cells (HCVECs) under hypoxic conditions. Western blot detected CSF1 released from HCVECs under hypoxic conditions that activated the PI3K/AKT/FOXO1 axis in human macrophages via binding to CSF1R. Transwell migration assay, qRT-PCR, and Western blot detected the effect of CSF1 released from HCVECs on macrophage migration and M2 polarization via the CSF1R/PI3K/AKT/FOXO1 pathway. Incorporation of 5-ethynyl-20-deoxyuridine, transwell migration, and tube formation assays detected the effects of CSF1/CSF1R on the behaviors of HCVECs. Fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), and immunofluorescence detected the effect of blockade of CSF1/CSF1R on mouse laser-induced CNV. Color fundus photograph, ICGA, and FFA detected CNV lesions in neovascular AMD (nAMD) patients. ELISA detected CSF1 and CSF1R in the aqueous humor of age-related cataract and nAMD patients.

Results

CSF1 released from HCVECs under hypoxic conditions activated the PI3K/AKT/FOXO1 axis in human macrophages via binding to CSF1R, promoting macrophage migration and M2 polarization via up-regulation of the CSF1R/PI3K/AKT/FOXO1 pathway. Human macrophages promoted the proliferation, migration, and tube formation of HCVECs in a CSF1/CSFR1-dependent manner under hypoxic conditions. CSF1/CSF1R blockade ameliorated the formation of mouse laser-induced CNV. CSF1 and CSF1R were increased in the aqueous humor of nAMD patients.

Conclusions

Our results affirmed the crucial role of CSF1/CSF1R in boosting the formation of CNV and offered potential molecular targets for the treatment of nAMD.

Therapeutic efficacy of pulmonary live tuberculosis vaccines against established asthma by subverting local immune environment

Background

Substantial recent advances in the comprehension of the molecular and cellular mechanisms behind asthma have evidenced the importance of the lung immune environment for disease outcome, making modulation of local immune responses an attractive therapeutic target against this pathology. Live attenuated mycobacteria, such as the tuberculosis vaccine BCG, have been classically linked with a type 1 response, and proposed as possible modulators of the type 2 response usually associated with asthma.

Methods

In this study we used different acute and chronic murine models of asthma to investigate the therapeutic efficacy of intranasal delivery of the live tuberculosis vaccines BCG and MTBVAC by regulating the lung immune environment associated with airway hyperresponsiveness (AHR).

Findings

Intranasal administration of BCG, or the novel tuberculosis vaccine candidate MTBVAC, abrogated AHR-associated hallmarks, including eosinophilia and lung remodeling. This correlated with the re-polarization of allergen-induced M2 macrophages towards an M1 phenotype, as well as with the induction of a strong allergen-specific Th1 response. Importantly, vaccine treatment was effective in a scenario of established chronic asthma where a strong eosinophil infiltration was already present prior to immunization. We finally compared the nebulization efficiency of clinical formulations of MTBVAC and BCG using a standard commercial nebulizer for potential aerosol application.

Interpretation

Our results demonstrate that pulmonary live tuberculosis vaccines efficiently revert established asthma in mice. These data support the further exploration of this approach as potential therapy against asthma.

Funding

Spanish Ministry of Science [grant numbers: BIO2014-5258P, RTI2018-097625-B-I00], Instituto de Salud Carlos III, Gobierno de Aragón/Fondo Social Europeo, University of Zaragoza [grant number: JIUZ-2018-BIO-01].

Role of IL-25, IL-33, and TSLP in triggering united airway diseases toward type 2 inflammation

Under the concept of "united airway diseases," the airway is a single organ wherein upper and lower airway diseases are commonly comorbid. The upper and lower airways are lined with respiratory epithelium that plays a vital role in immune surveillance and modulation as the first line of defense to various infective pathogens, allergens, and physical insults. Recently, there is a common hypothesis emphasizing epithelium-derived cytokines, namely IL-25, IL-33, and TSLP, as key regulatory factors that link in immune-pathogenic mechanisms of allergic rhinitis (AR), chronic rhinosinusitis (CRS), and asthma, mainly involving in type 2 inflammatory responses and linking innate and adaptive immunities. Herein, we review studies that elucidated the role of epithelium-derived triple cytokines in both upper and lower airways with the purpose of expediting better clinical treatments and managements of AR, CRS, asthma, and other associated allergic diseases via applications of the modulators of these cytokines.

Mechanisms of allergen-specific immunotherapy and allergen tolerance

Allergen-specific immunotherapy (AIT) is the mainstay treatment for the cure of allergic disorders, with depicted efficacy and safety by several trials and meta-analysis. AIT impressively contributes to the management of allergic rhinitis, asthma and venom allergies. Food allergy is a new arena for AIT with promising results, especially via novel administration routes. Cell subsets with regulatory capacities are induced during AIT. IL-10 and transforming growth factor (TGF)-β are the main suppressor cytokines, in addition to surface molecules such as cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1) within the micro milieu. Modified T- and B-cell responses and antibody isotypes, increased activity thresholds for eosinophils, basophils and mast cells and consequent limitation of inflammatory cascades altogether induce and maintain a state of sustained allergen-specific unresponsiveness. Established tolerance is reflected into the clinical perspectives as improvement of allergy symptoms together with reduced medication requirements and evolved disease severity. Long treatment durations, costs, reduced patient compliance and risk of severe, even life-threatening adverse reactions during treatment stand as major limiting factors for AIT. By development of purified non-allergenic, highly-immunogenic modified allergen extracts, and combinational usage of them with novel adjuvant molecules via new routes may shorten treatment durations and possibly reduce these drawbacks. AIT is the best model for custom-tailored therapy of allergic disorders. Better characterization of disease endotypes, definition of specific biomarkers for diagnosis and therapy follow-up, as well as precision medicine approaches may further contribute to success of AIT in management of allergic disorders.

Multi-omics analysis identifies FoxO1 as a regulator of macrophage function through metabolic reprogramming

Macrophages are plastic cells that can switch among different states according to bioenergetic or biosynthetic requirements. Our previous work demonstrated that the transcription factor Forkhead Box Protein 1 (FoxO1) plays a pivotal role in regulating the function of macrophages, but the underlying mechanisms are still unclear. Here we identify FoxO1 as a regulator of macrophage function through metabolic reprogramming. Transcriptomic and proteomic analyses showed that the deficiency of FoxO1 results in an alternatively activated (M2) phenotype of macrophages, with lower expression of inflammatory response- and migration-associated genes. Using the high content screening and analysis technology, we found that deletion of FoxO1 in macrophages slows their migration rate and impairs their function to limit tumor cell growth in vitro. Next, we demonstrated that glycolysis is inhibited in FoxO1-deficient macrophages, which leads to the observed functional changes and the reduced tumor suppression capability. This prospective study shows that FoxO1 serves as a bridge between metabolism and macrophage function.

Depletion of microRNA-451 in response to allergen exposure accentuates asthmatic inflammation by regulating Sirtuin2

The incidence of asthma has increased from 5.5% to near 8% of the population, which is a major health concern. The hallmarks of asthma include eosinophilic airway inflammation that is associated with chronic airway remodeling. Allergic airway inflammation is characterized by a complex interplay of resident and inflammatory cells. MicroRNAs (miRNAs) are small noncoding RNAs that function as posttranscriptional modulators of gene expression. However, the role of miRNAs, specifically miR-451, in the regulation of allergic airway inflammation is unexplored. Our previous findings showed that oxidant stress regulates miR-451 gene expression in macrophages during an inflammatory process. In this paper, we examined the role of miR-451 in regulating macrophage phenotype using an experimental poly-allergenic murine model of allergic airway inflammation. We found that miR-451 contributes to the allergic induction of CCL17 in the lung and plays a key role in proasthmatic macrophage activation. Remarkably, administration of a Sirtuin 2 (Sirt2) inhibitor diminished alternate macrophage activation and markedly abrogated triple-allergen [dust mite, ragweed, Aspergillus fumigatus (DRA)]-induced lung inflammation. These data demonstrate a role for miR-451 in modulating allergic inflammation by influencing allergen-mediated macrophages phenotype.