Update on the role of alternatively activated macrophages in asthma

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.

Schistosoma japonicum cystatin alleviates paraquat poisoning caused acute lung injury in mice through activating regulatory macrophages

BACKGROUND

Paraquat (PQ) is a widely used herbicide that poisons human by accident or intentional ingestion. PQ poisoning causes systemic inflammatory response syndrome (SIRS) resulting in acute lung injury (ALI) with an extremely high mortality rate. Blood trematode Schistosoma japonicum-produced cystatin (Sj-Cys) is a strong immunomodulatory protein that has been experimentally used to treat inflammation related diseases. In this study, Sj-Cys recombinant protein (rSj-Cys) was used to treat PQ-induced lung injury and the immunological mechanism underlying the therapeutic effect was investigated.

METHODS

PQ-induced acute lung injury mouse model was established by intraperitoneally injection of 20 mg/kg of paraquat. The poisoned mice were treated with rSj-Cys and the survival rate was observed up to 7 days compared with the group without treatment. The pathological changes of PQ-induced lung injury were observed by examining the histochemical sections of affected lung tissue and the wet to dry ratio of lung as a parameter for inflammation and edema. The levels of the inflammation related cytokines IL-6 and TNF-α and regulatory cytokines IL-10 and TGF-β were measured in sera and in affected lung tissue using ELISA and their mRNA levels in lung tissue using RT-PCR. The macrophages expressing iNOS were determined as M1 and those expressing Arg-1 as M2 macrophages. The effect of rSj-Cys on the transformation of inflammatory M1 to regulatory M2 macrophages was measured in affected lung tissue in vivo (EKISA and RT-PCR) and in MH-S cell line in vitro (flow cytometry). The expression levels of TLR2 and MyD88 in affected lung tissue were also measured to determine their role in the therapy of rSj-Cys on PQ-induced lung injury.

RESULT

We identified that treatment with rSj-Cys significantly improved the survival rate of mice with PQ-induced lung injury from 30 % (untreated) to 80 %, reduced the pathological damage of poisoning lung tissue, associated with significantly reduced levels of proinflammatory cytokines (IL-6 from 1490 to 590 pg/ml, TNF-α from 260 to 150 pg/ml) and increased regulatory cytokines (IL-10 from360 to 550 pg/ml, and TGF-β from 220 to 410 pg/ml) in both sera (proteins) and affected lung tissue (proteins and mRNAs). The polarization of macrophages from M1to M2 type was found to be involved in the therapeutic effect of rSj-Cys on the PQ-induced acute lung injury, possibly through inhibiting TLR2/MyD88 signaling pathway.

CONCLUSIONS

Our study demonstrated the therapeutic effect of rSj-Cys on PQ poisoning caused acute lung injury by inducing M2 macrophage polarization through inhibiting TLR2/MyD88 signaling pathway. The finding in this study provides an alternative approach for the treatment of PQ poisoning and other inflammatory diseases.

Comparative Evaluation of Antioxidative and Anti-inflammatory Properties of Acerola-Mediated Silver Nanogel and Copper Oxide Nanogel

BACKGROUND

The tropical plant acerola of the genus Malpighia includes shrubs and trees with fruit that is high in nutrients and bioactive chemicals. Acerola stands out due to its exceptionally high ascorbic acid content, ranging from 1500 to 4500 mg/100 g. Vitamin C intake greatly influences gingival health. The addition of nanoparticles along with vitamin C-rich acerola exhibits high antioxidant and anti-inflammatory properties, thereby positively improving gingival health.

METHOD

The antioxidant and anti-inflammatory properties of aqueous extracts of the acerola plant (Malpighia emarginata) were assessed. Silver nanoparticles (AgNPs) and copper oxide nanoparticles (CuONPs) were synthesized using the aqueous extract of acerola cherry gel by the phytogenic fabrication method. The antioxidant potential of silver and copper nanoparticles was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide, ferric reducing antioxidant power (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and nitric oxide scavenging activities.

RESULTS

Increasing concentrations of nanoparticles showed an increase in scavenging activity. Overall, CuONPs and AgNPs exhibited remarkable radical quenching efficacies. The anti-inflammatory effectiveness of CuONPs and AgNPs was monitored, showing suppression of protein denaturation as demonstrated by bovine serum albumin (BSA), egg albumin (EA), and membrane stabilization assays. The results revealed that increasing the doses of CuONPs and AgNPs had a positive impact on the anti-inflammatory activity of the nanoparticles.

CONCLUSION

The present study revealed that both nanoparticles provided better antioxidant and anti-inflammatory activities. This study also elaborates on the pharmacological potential of both nanoparticles, which could be further explored for application in all healthcare sectors.

Therapeutic Effects of IL-1RA, M2 Cells, and Their Synergistic Impact on a Mouse Model of Rheumatoid Arthritis

Purpose

Rheumatoid arthritis (RA) is a type of autoimmune disease that results in chronic inflammation of the joint synovial tissue, leading to joint damage and significant disability. Despite ongoing research, the exact cause of RA remains unclear, and current treatments have limitations. This study explores the potential of utilizing interleukin-1 receptor antagonist (IL-1RA) and anti-inflammatory macrophages polarized in the vicinity of the supernatant from allogeneic mesenchymal stem cells (MSCs) as a novel therapeutic approach for RA.

Methods

An expression cassette containing the IL-1RA gene was constructed and expressed in E. coli BL21. The resulting protein was purified and stabilized for use in in vivo experiments. Bone marrow MSCs were isolated and used to produce anti-inflammatory M2 macrophages from the isolated peripheral blood monocytes. The macrophages were then used to treat mice with RA induced by collagen type II.

Results

The combination of IL-1RA and M2 macrophages improved clinical and histopathological symptoms of the disease, reduced levels of inflammatory factors, and modulated the immune system in the treated mouse groups. The results showed that this combinatory therapy had a synergistic effect for RA treatment.

Conclusion

The simultaneous use of IL-1RA and M2 cells could be a promising approach for the treatment of RA. This combinatory therapy has the potential to improve the disease and decrease the severity of inflammation in patients with RA.

Involvement of Muscarinic M3 Receptor in the Development of M2 Macrophages in Allergic Inflammation

INTRODUCTION

The muscarinic M3 receptor antagonist, tiotropium, has a bronchodilatory effect on asthma patients. Additionally, tiotropium inhibits allergic airway inflammation and remodeling in a murine asthma model. However, the underlying mechanisms of this M3 receptor antagonist remain unclear. Therefore, we investigated the effect of muscarinic M3 receptor blockage on M2 macrophage development during allergic airway inflammation.

METHODS

BALB/c mice were sensitized and challenged with ovalbumin to develop a murine model of allergic airway inflammation mimicking human atopic asthma. During the challenge phase, mice were treated with or without tiotropium. Lung cells were isolated 24 h after the last treatment and gated using CD68-positive cells. Relm-α and Arginase-1 (Arg1) (M2 macrophage markers) expression was determined by flow cytometry. Mouse bone marrow mononuclear cell-derived macrophages (mBMMacs) and human peripheral blood mononuclear cells (PBMCs)-derived macrophages were stimulated with IL-4 and treated with a muscarinic M3 receptor antagonist in vitro.

RESULTS

The total cells, eosinophils, and IL-5 and IL-13 levels in BAL fluids were markedly decreased in the asthma group treated with tiotropium compared to that in the untreated asthma group. The Relm-α and Arg1 expression in macrophages was reduced considerably in the asthma group treated with tiotropium compared to that in the untreated asthma group, suggesting that the development of M2 macrophages was inhibited by muscarinic M3 receptor blockage. Additionally, muscarinic M3 receptor blockage in vitro significantly inhibited M2 macrophage development in both mBMMacs- and PBMCs-derived macrophages.

CONCLUSIONS

Muscarinic M3 receptor blockage inhibits M2 macrophage development and prevents allergic airway inflammation. Moreover, muscarinic M3 receptors might be involved in the differentiation of immature macrophages into M2 macrophages.

Functional roles of circular RNAs in lung injury

Lung injury leads to respiratory dysfunction, low quality of life, and even life-threatening conditions. Circular RNAs (circRNAs) are endogenous RNAs produced by selective RNA splicing. Studies have reported their involvement in the progression of lung injury. Understanding the roles of circRNAs in lung injury may aid in elucidating the underlying mechanisms and provide new therapeutic targets. Thus, in this review, we aimed to summarize and discuss the characteristics and biological functions of circRNAs, and their roles in lung injury from existing research, to provide a theoretical basis for the use of circRNAs as a diagnostic and therapeutic target for lung injury.

The phenotype and related gene expressions of macrophages in adipose tissue of T2D mice following MSCs infusion

BACKGROUND

Infusion of mesenchymal stem cells (MSCs) induces polarization of M2 macrophages in adipose tissue of type 2 diabetes (T2D) mice. Studies have shown that M2 macrophages were divided into four sub-phenotypes (M2a, M2b, M2c and M2d) with different functions, and manuscripts have also confirmed that macrophages co-cultured with MSCs were not matched with known four phenotype macrophages. Therefore, our study explored the phenotype and related gene expressions of macrophages in the adipose tissue of T2D mice with/without MSCs infusion.

METHODS

We induced a T2D mouse model by using high-fat diets and streptozotocin (STZ) injection. The mice were divided into three groups: the control group, the T2D group, and the MSCs group. MSCs were systemically injected once a week for 6 weeks. The phenotype of macrophages in adipose tissue was detected via flow cytometric analysis. We also investigated the gene expression of macrophages in different groups via SMART-RNA-sequencing and quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR).

RESULTS

The present study found that the macrophages of adipose tissue in the MSCs group were polarized to the M2 phenotype mixed with four sub-phenotypes. Besides, M2a and M2c held a dominant position, while M2b and M2d (tumor-associated macrophages, TAMs) exhibited a decreasing trend after infusion of MSCs. Moreover, the MSCs group did not appear to express higher levels of tumor-associated, inflammation-associated, or fibrosis-associated genes in comparison to the T2D group.

CONCLUSION

The present results unveiled that the macrophage phenotype was inclined to be present in a hybridity state of four M2 sub-phenotypes and the genes related to tumor-promoting, pro-inflammation and pro-fibrosis were not increased after MSCs injection.

Inhalation of Citrus Reticulata essential oil alleviates airway inflammation and emphysema in COPD rats through regulation of macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory respiratory disease. Citrus Reticulata peel, the dried ripe peel of Citrus Reticulata species, has been found to have anti-inflammatory and cough attenuation effects. However, the therapeutic effects and its precise underlying mechanisms of atomizing inhalation using Citrus Reticulata essential oil (CREO) have not yet been fully elucidated.

AIM OF THE STUDY

The aim of this study was to assess the therapeutic effects of Citrus Reticulata essential oil and its associated anti-inflammatory mechanisms in COPD rat model.

METHODS

A total of 80 SD rats were randomized into four groups: control group (Con), COPD model group (COPD), COPD + ipratropium bromide (IB), and COPD + citrus reticulata essential oil (CREO). To induce COPD in rats, cigarette smoke (CS) exposure was used, while CREO and IB groups were administered through atomizing inhalation. The clinical signs, pathological lesions of the lung, percentages of antigen-presenting lung macrophages (CD11b/c+/CD86+ cells) and CD8+ T cells, and the content and mRNA expression of cytokines of the lung were analyzed.

RESULTS

The findings revealed that atomizing inhalation of Citrus reticulata essential oil had therapeutic effects on COPD rats. The treatment resulted in improvement in the body weight and mental status of COPD rats, reduced pathological injury of the lung, and increased proportion of CD11b/c+/CD86+ cells in lung macrophages, while also decreasing the number of CD8+ T cells. In addition, the Citrus Reticulata essential oil reduced the contents of IL-18, IL-17A, IL-12p70, and GM-CSF, downregulated the relative mRNA expression of IFN-γ, IL-4, and MMP-12, and upregulated the mRNA expression of IL-10.

CONCLUSIONS

Citrus reticulata essential oil can alleviate histological injury of the lung and regulate macrophages and CD8+ T cells in COPD rats. The study suggests that citrus reticulata essential oil could be a potential therapeutic agent for COPD.

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.

Chromofungin, a chromogranin A-derived peptide, protects against sepsis-induced acute lung injury by inhibiting LBP/TLR4-dependent inflammatory signaling

Chromofungin (CHR) is a biologically active peptide derived from chromogranin A that exhibits anti-inflammatory effects. However, it remains unclear whether and how CHR protects against sepsis-induced acute lung injury (ALI). A murine model of sepsis-induced ALI was established through cecal ligation and puncture, with intraperitoneal injection of CHR. Lung inflammation and macrophage polarization were examined by measuring the levels of cytokines and markers of M1 (CD86, inducible nitric oxide synthase [iNOS]) or M2 macrophages (arginase-1 [Arg1], resistin-like molecule α1 [Fizz1] and CD206). In vitro, mouse MH-S cells pretreated with CHR was employed to explore the interplay between the lipopolysaccharide-binding protein (LBP)/toll-like receptor 4 (TLR4) signaling pathway and M1/M2 polarity. The results revealed CHR's ability to enhance the 7-day survival rate and protect lung pathological injury in sepsis-induced ALI. CHR increased the expression of interleukin-4 and interleukin-10 but decreased the expression of tumour necrosis factor-α and interleukin-1β. In addition, CHR notably facilitated M2 macrophage polarization, while significantly suppressingM1 polarization of alveolar macrophages. Mechanistic investigations delineated CHR's role in macrophage polarization by downregulating nuclear factor-κB expression through modulation of the LBP/TLR4 signaling pathway. Therefore, CHR may represent a novel strategy for the prevention of sepsis-induced ALI.

Sensor Array-Enabled Identification of Drugs for Repolarization of Macrophages to Anti-Inflammatory Phenotypes

Macrophages are key components of the innate immune system that have essential functions in physiological processes and diseases. The phenotypic plasticity of macrophages allows cells to be polarized into a multidimensional spectrum of phenotypes, broadly classed as pro-inflammatory (M1) and anti-inflammatory (M2) states. Repolarization of M1 to M2 phenotypes alters the immune response to ameliorate autoimmune and inflammation-associated diseases. Detection of this repolarization, however, is challenging to execute in high-throughput applications. In this work, we demonstrate the ability of a single polymer fabricated to provide a six-channel sensor array that can determine macrophage polarization phenotypes. This sensing platform provides a sensitive and high-throughput tool for detecting drug-induced M1-to-M2 repolarization, allowing the identification of new therapeutic leads for inflammatory diseases. The ability of this sensor array to discriminate different M2 subtypes induced by drugs can also improve the efficacy evaluation of anti-inflammatory drugs and avoid adverse effects.

M1/M2 macrophages and their overlaps - myth or reality?

Macrophages represent heterogeneous cell population with important roles in defence mechanisms and in homoeostasis. Tissue macrophages from diverse anatomical locations adopt distinct activation states. M1 and M2 macrophages are two polarized forms of mononuclear phagocyte in vitro differentiation with distinct phenotypic patterns and functional properties, but in vivo, there is a wide range of different macrophage phenotypes in between depending on the microenvironment and natural signals they receive. In human infections, pathogens use different strategies to combat macrophages and these strategies include shaping the macrophage polarization towards one or another phenotype. Macrophages infiltrating the tumours can affect the patient's prognosis. M2 macrophages have been shown to promote tumour growth, while M1 macrophages provide both tumour-promoting and anti-tumour properties. In autoimmune diseases, both prolonged M1 activation, as well as altered M2 function can contribute to their onset and activity. In human atherosclerotic lesions, macrophages expressing both M1 and M2 profiles have been detected as one of the potential factors affecting occurrence of cardiovascular diseases. In allergic inflammation, T2 cytokines drive macrophage polarization towards M2 profiles, which promote airway inflammation and remodelling. M1 macrophages in transplantations seem to contribute to acute rejection, while M2 macrophages promote the fibrosis of the graft. The view of pro-inflammatory M1 macrophages and M2 macrophages suppressing inflammation seems to be an oversimplification because these cells exploit very high level of plasticity and represent a large scale of different immunophenotypes with overlapping properties. In this respect, it would be more precise to describe macrophages as M1-like and M2-like.

Mechanisms and Effects of Macrophage Polarization and Its Specifics in Pulmonary Environment

Macrophages are a specific group of cells found in all body tissues. They have specific characteristics in each of the tissues that correspond to the functional needs of the specific environment. These cells are involved in a wide range of processes, both pro-inflammatory and anti-inflammatory ("wound healing"). This is due to their specific capacity for so-called polarization, a phenotypic change that is, moreover, partially reversible compared to other differentiated cells of the human body. This promises a wide range of possibilities for its influence and thus therapeutic use. In this article, we therefore review the mechanisms that cause polarization, the basic classification of polarized macrophages, their characteristic markers and the effects that accompany these phenotypic changes. Since the study of pulmonary (and among them mainly alveolar) macrophages is currently the focus of scientific interest of many researchers and these macrophages are found in very specific environments, given mainly by the extremely high partial pressure of oxygen compared to other locations, which specifically affects their behavior, we will focus our review on this group.

Jingfang Granule alleviates bleomycin-induced acute lung injury via CD200-CD200R immunoregulatory pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Jingfang granules (JF), one famous traditional Chinese formula in "She Sheng Zhong Miao Fang" written by Shi-Che Zhang during the Ming Dynasty era, has been widely used to prevent epidemic diseases in history and now was recommended for the treatment of coronavirus disease 2019 (COVID-19) in China. However, the roles of JF against acute lung injury and its mechanisms remain unclear.

AIM OF THE STUDY

Acute lung injury (ALI) and its progressive acute respiratory distress syndrome (ARDS) are a continuum of lung inflammatory disease with high morbidity and mortality in clinic, especially in COVID-19 patients. The present study aims to investigate the effect of JF on ALI and clarify its underlying mechanisms for clinical application in COVID-19 control.

METHODS

Bleomycin-induced ALI mice were given oral gavage daily for seven days with or without Jingfang granules (2, 4 g/kg). The body weight, lung wet/dry weight ratios, lung appearance and tissue histopathology were evaluated. Quantitative real-time PCR, biochemical bronchoalveolar lavage fluids analysis was used to determine the gene expression of proinflammation factor and infiltrated inflammatory cells in lung. Immunofluorescence image and western blot were used to detect the markers of alveolar macrophages (AMs), endothelial cell apoptosis and changes of CD200-CD200R pathway.

RESULTS

Firstly, histopathological analysis showed that JF significantly attenuated pulmonary injury and inflammatory response in ALI mice. Then, cytokine detection, inflammatory cells assay, and JNKs and p38 pathway analysis indicated that the recruitment and activation of alveolar macrophages was the main reason to cause ALI and JF could reverse this variation. Next, immunofluorescence staining and TUNEL assay showed that JF upregulated the expression of CD200 and suppressed the apoptosis of alveolar endothelial cells. Finally, double immunofluorescence staining of CD200 and CD11c indicated that the seriously damaged tissue had the lower CD200 while more AMs infiltration, which was confirmed by RT-PCR analysis of CD200/CD200R.

CONCLUSIONS

Jingfang granules can protect lung from acu te injury and mitigate the recruitment and overactive AMs-induced inflammation via CD200-CD200R immunoregulatory signal axis, which will provide an experimental basis for Jingfang granules clinical applications in COVID-19.

Mollugin ameliorates murine allergic airway inflammation by inhibiting Th2 response and M2 macrophage activation

Mollugin, isolated from Rubia cordifolia L, is a pharmacological compound with anti-inflammatory activity. This study aimed to investigate whether mollugin protects mice against shrimp tropomyosin (ST)-induced allergic airway inflammation. Mice were sensitized with ST combined with Al(OH)₃ administered intraperitoneally (i.p.) once weekly for 3 wk followed by ST challenge for 5 d. Mice were i.p.-administered daily with mollugin for 7 d. Results showed that mollugin attenuated ST-induced infiltration of eosinophils and epithelial mucus secretion in the lung tissues and suppressed lung eosinophil peroxidase activity. Additionally, mollugin lowered the Th2 cytokine, IL-4 and IL-5, production and downregulated the mRNA levels of Il-4, Il-5, Il-13, eotaxin, Ccl-17, Muc5ac, arginase-1, Ym-1, and Fizz-1 in the lung tissues. Network pharmacology was employed to predict core targets, and the molecular docking approach was used to verify the compound targets. The results of the molecular docking study of mollugin into p38 MAPK or poly(ADP-ribose) polymerase 1 (PARP1) binding sites revealed that its mechanism was possibly similar to that of SB203580 (a p38 MAPK inhibitor) or olaparib (a PARP1 inhibitor). Immunohistochemistry analysis revealed that mollugin mitigated ST-induced elevation of arginase-1 expression and macrophage levels in the lungs and bronchoalveolar lavage fluid, respectively. Furthermore, arginase-1 mRNA level and phosphorylation of p38 MAPK were inhibited in IL-4-stimulated peritoneal macrophages. In ST-stimulated mouse primary splenocytes, mollugin notably inhibited IL-4 and IL-5 production and downregulated PARP1 and PAR protein expression. According to our findings, mollugin ameliorated allergic airway inflammation by inhibiting Th2 response and macrophage polarization.

Emerging role of macrophages in non-infectious diseases: An update

In the past three decades, a huge body of evidence through various research studies conducted on animal models, has demonstrated that the macrophages are centralized of all the leukocytes involved in diseases and, particularly, their role in non-infectious diseases has been studied extensively for which they have also been referred to as the "double-edged swords". The most versatile of all immunocytes, macrophages play a key role in health and diseases. Various experimental models have demonstrated the conventional paradigms such as the M1/M2 dichotomy, which is not as obvious and presents a complex characterization of the macrophages in the disease immunology. In human diseases, this M1-M2 continuum shows a complex web of mechanisms, which are majorly divided into the pro-inflammatory roles (derived mainly by the cytokines: IL-1, IL-6, IL-12, IL-23, and tumor necrosis factor) and anti-inflammatory roles (CCl-17, CCl-22, CCL-2, transforming growth factor (TGF), and interleukin-10), which are involved in the wound healing and pathogen-suppression. The conventional division of these macrophages as M1 and M2 is derived from the opposing functions of these macrophages; where M1 is involved in the tissue damage and pro-inflammatory roles and M2 promotes cell proliferation and the resolution of inflammation. Both these pathways down-regulate each other in diseases through a plethora of enzymatic and cytokine mediators.

The Role of Macrophage Autophagy in Asthma: A Novel Therapeutic Strategy

Asthma is a chronic respiratory disease frequently associated with airway inflammation and remodeling. The development of asthma involves various inflammatory phenotypes that impact therapeutic effects, and macrophages are master innate immune cells in the airway that exert diverse functions including phagocytosis, antigen presentation, and pathogen clearance, playing an important role in the pathogeneses of asthma. Recent studies have indicated that autophagy of macrophages affects polarization of phenotype and regulation of inflammation, which implies that regulating autophagy of macrophages may be a potential strategy for the treatment of asthma. Thus, this review summarizes the signaling pathways and effects of macrophage autophagy in asthma, which will provide a tactic for the development of novel targets for the treatment of this disease.

Inhibitory effects of Ephedra alte on IL-6, hybrid TLR4, TNF-α, IL-1β, and extracted TLR4 receptors: in silico molecular docking

Inflammation is a physiological reaction of the immune system required to remove the presence of pathogenic germs. Many herbal-derived extracts and phytoconstituents show anti-inflammatory effects. Among these natural phytoconstituents is Ephedra alte (E. alte), which shows pepsin enzyme inhibitory, antibacterial, and antioxidant activities. In this work, molecular docking study is conducted on five major human anti-inflammatory cytokines receptors (IL-6, hybrid TLR4, TNF-α, IL-1β, and extracted TLR4) to explore the molecular recognition process and complex ligand-receptor interactions of E. alte phytoconstituents. Human TLR4 receptor has been computationally extracted, for the first time, from the hybrid TLR4 human and VLRB inshore hagfish. Among E. alte phytoconstituents, only β-Sitosterol and Androstan-3-one have better LBE (Lowest Binding Energy) scores with inhibition constant (K i) values than those of other tested compounds. The β-Sitosterol and Androstan-3-one results indicate that these compounds could be efficient inhibitors of inflammation and reduce the oxidative stress by interfering with the activity of the five studied proteins.

Intravenous Mesenchymal Stem Cell Administration Modulates Monocytes/Macrophages and Ameliorates Asthmatic Airway Inflammation in a Murine Asthma Model

Although asthma is a common chronic airway disease that responds well to anti-inflammatory agents, some patients with asthma are unresponsive to conventional treatment. Mesenchymal stem cells (MSCs) have therapeutic potential for the treatment of inflammatory diseases owing to their immunomodulatory properties. However, the target cells of MSCs are not yet clearly known. This study aimed to determine the effect of human umbilical cord-derived MSCs (hUC-MSCs) on asthmatic lungs by modulating innate immune cells and effector T cells using a murine asthmatic model. Intravenously administered hUC-MSCs reduced airway resistance, mucus production, and inflammation in the murine asthma model. hUC-MSCs attenuated not only T helper (Th) 2 cells and Th17 cells but also augmented regulatory T cells (Tregs). As for innate lymphoid cells (ILC), hUC-MSCs effectively suppressed ILC2s by downregulating master regulators of ILC2s, such as Gata3 and Tcf7. Finally, regarding lung macrophages, hUC-MSCs reduced the total number of macrophages, particularly the proportion of the enhanced monocyte-derived macrophage population. In a closer examination of monocyte-derived macrophages, hUC-MSCs reduced the M2a and M2c populations. In conclusion, hUC-MSCs can be considered as a potential anti- asthmatic treatment given their therapeutic effect on the asthmatic airway inflammation in a murine asthma model by modulating innate immune cells, such as ILC2s, M2a, and M2c macrophages, as well as affecting Tregs and effector T cells.

Developing a Diagnostic Model to Predict the Risk of Asthma Based on Ten Macrophage-Related Gene Signatures

OBJECTIVE

Asthma (AS) is a chronic inflammatory disease of the airway, and macrophages contribute to AS remodeling. Our study aims at screening macrophage-related gene signatures to build a risk prediction model and explore its predictive abilities in AS diagnosis.

METHODS

Three microarray datasets were downloaded from the GEO database. The Limma package was used to screen differentially expressed genes (DEGs) between AS and controls. The ssGSEA algorithm was used to determine immune cell proportions. The Pearson correlation coefficient was computed to select the macrophage-related DEGs. The LASSO and RFE algorithms were implemented to filter the macrophage-related DEG signatures to establish a risk prediction model. Receiver operating characteristic (ROC) curves were used to assess the diagnostic ability of the prediction model. Finally, the qPCR was used to detect the expression of selected differential genes in sputum from healthy people and asthmatic patients.

RESULTS

We obtained 1,189 DEGs between AS and controls from the combined datasets. By evaluating immune cell proportions, macrophages showed a significant difference between the two groups, and 439 DEGs were found to be associated with macrophages. These genes were mainly enriched in the gene ontology-biological process of immune and inflammatory responses, as well as in the KEGG pathways of cytokine-cytokine receptor interaction and biosynthesis of antibiotics. Finally, 10 macrophage-related DEG signatures (EARS2, ATP2A2, COLGALT1, GART, WNT5A, AK5, ZBTB16, CCL17, ADORA3, and CXCR4) were screened as an optimized gene set to predict AS diagnosis, and they showed diagnostic abilities with AUCs of 0.968 and 0.875 in ROC curves of combined and validation datasets, respectively. The mRNA expressions of EARS2, ATP2A2, COLGALT1, and GART in the control group were higher than in AS group, while the expressions of WNT5A, AK5, ZBTB16, CCL17, ADORA3, and CXCR4 in the control group were lower than that in the AS group.

CONCLUSION

We proposed a diagnostic model based on 10 macrophage-related genes to predict AS risk.\.

Anti-Inflammatory, Antioxidative, and Nitric Oxide-Scavenging Activities of a Quercetin Nanosuspension with Polyethylene Glycol in LPS-Induced RAW 264.7 Macrophages

Quercetin (Qu) is a dietary antioxidant and a member of flavonoids in the plant polyphenol family. Qu has a high ability to scavenge reactive oxygen species (ROS) and reactive nitrogen species (RNS) molecules; hence, exhibiting beneficial effects in preventing obesity, diabetes, cancer, cardiovascular diseases, and inflammation. However, quercetin has low bioavailability due to poor water solubility, low absorption, and rapid excretion from the body. To address these issues, the usage of Qu nanosuspensions can improve physical stability, solubility, and pharmacokinetics. Therefore, we developed a Qu and polyethylene glycol nanosuspension (Qu-PEG NS) and confirmed its interaction by Fourier transform infrared analysis. Qu-PEG NS did not show cytotoxicity to HaCaT and RAW 264.7 cells. Furthermore, Qu-PEG NS effectively reduced the nitrogen oxide (NO) production in lipopolysaccharide (LPS)-induced inflammatory RAW 264.7 cells. Additionally, Qu-PEG NS effectively lowered the levels of COX-2, NF-κB p65, and IL-1β in the LPS-induced inflammatory RAW 264.7 cells. Specifically, Qu-PEG NS exhibited anti-inflammatory properties by scavenging the ROS and RNS and mediated the inhibition of NF-κB signaling pathways. In addition, Qu-PEG NS had a high antioxidant effect and antibacterial activity against Escherichia coli and Bacillus cereus. Therefore, the developed novel nanosuspension showed comparable antioxidant, anti-inflammatory, and antibacterial functions and may also improve solubility and physical stability compared to raw quercetin.

Targeting interleukin 4 receptor alpha on tumor-associated macrophages reduces the pro-tumor macrophage phenotype

Tumor-associated macrophages (TAMs) are an abundant tumor-promoting cell type in the tumor microenvironment (TME). Most TAMs exhibit a pro-tumor M2-like phenotype supportive of tumor growth, immune evasion, and metastasis. IL-4 and IL-13 are major cytokines that polarize macrophages to an M2 subset and share a common receptor, IL-4 receptor alpha (IL-4R alpha). Treatment of human ex vivo polarized M2 macrophages and M2 macrophage precursors with IL-4R alpha antagonist antibody Dupilumab (Dupixent^Ⓡ) reduces M2 macrophage features, including a shift in cell surface marker protein expression and gene expression. In animal models of prostate cancer, both pharmacologic inhibition of IL-4R alpha and genetic deletion of IL-4R alpha utilizing an Il4ra -/- mouse model result in decreased CD206 on TAMs. These data support IL-4R alpha as a target to reduce the pro-tumor, M2-like macrophage phenotype as a novel adjunct cancer therapy.

Formation of eicosanoids and other oxylipins in human macrophages

In this review it is attempted to summarize current studies about formation of eicosanoids and other oxylipins in different human macrophages. There are several reports on M1 and M2 cells, also other phenotypes have been described. The eicosanoids formed in the largest amounts are the COX products TxB₂ and PGE₂. Thus shortlived bioactive TxA₂ is a dominating product both in M1- and in M2-lineages, one exception seems to be M_{GM-CSF, TGFβ} cells. 5-LOX products are produced in both M1 and M2 macrophages, as well as in not fully polarized cells of both lineages. M_M-CSF as well as M2 macrophages produced LTC₄ more readily compared to M1 lineage cells. In M_{GM-CSF, TGFβ} cells LTB₄ is a major eicosanoid, in line with high expression of LTA₄ hydrolase. Recent reports described increased formation of leukotrienes in macrophages subjected to trained immunity with inflammatory transcriptional reprogramming. Also in macrophages derived from monocytes collected from post-COVID-19 patients. 15-LOX-1 is strongly upregulated in CD206⁺ M2 cells (M2a), differentiated in presence of IL-4. These macrophages also express 15-LOX-2. In incubations with pathogenic E. coli as well as other stimuli 15(S)-HETE and 17(S)-HDHA were major oxylipins formed. Also, the SPM precursor 5,15-diHETE and the SPM RvD5 were produced in considerable amounts, while other SPMs were less abundant. In M2 macrophages incubated with E. coli or S. aureus the cytosolic 15-LOX-1 enzyme accumulated to punctuate structures in a Ca²⁺ dependent manner with a relatively slow time course, leading to formation of mediators from endogenous substrate. Chalcones, flavone-like anti-inflammatory natural products, induced translocation of 15-LOX-1 in M2 cells, with high formation of 15-LOX derived oxylipins.

Low Dose Rate Radiation Regulates M2-like Macrophages in an Allergic Airway Inflammation Mouse Model

We investigated the effects of low dose rate radiation (LDR) on M1 and M2 macrophages in an ovalbumin-induced mouse model of allergic airway inflammation and asthma. After exposure to LDR (1 Gy, 1.818 mGy/h) for 24 days, mice were euthanized and the changes in the number of M1 and M2 macrophages in the bronchoalveolar lavage fluid and lung, and M2-associated cytokine levels, were assessed. LDR treatment not only restored the M2-rich microenvironment but also ameliorated asthma-related progression in a macrophage-dependent manner. In an ovalbumin-induced mouse model, LDR treatment significantly inhibited M2, but not M1, macrophage infiltration. M2-specific changes in macrophage polarization during chronic lung disease reversed the positive effects of LDR. Moreover, the levels of cytokines, including chemokine (C-C motif) ligand (CCL) 24, CCL17, transforming growth factor beta 1, and matrix metalloproteinase-9, decreased in ovalbumin-sensitized/challenged mice upon exposure to LDR. Collectively, our results indicate that LDR exposure suppressed asthmatic progression, including mucin accumulation, inflammation, and Type 2 T helper (Th2) cytokine (interleukin (IL)-4 and IL-13) production. In conclusion, LDR exposure decreased Th2 cytokine secretion in M2 macrophages, resulting in a reduction in eosinophilic inflammation in ovalbumin-sensitized/challenged mice.

Interstitial lung disease progression in patients with anti-aminoacyl transfer-RNA-synthetase autoantibodies is characterized by higher levels of sCD163

BACKGROUND

Patients with anti-tRNA autoantibodies are characterized by arthritis, mechanic´s hands, fever, Raynaud´s phenomenon, and interstitial lung disease (ILD), in at least two clinical scenarios: the antisynthetase syndrome (ASSD) and interstitial pneumonia with autoimmune features (IPAF). The anti-tRNA-ILD treatment is centered on the administration of corticosteroids and a wide variety of immunosuppressive drugs; however, the effectiveness of the treatment depends on factors not fully understood. This research work aimed to quantify the serum levels of two molecules related to pulmonary fibrosis and explore their relationship with the progression of ILD associated with ASSD METHODOLOGY: Serum levels of sCD163 and TGF-β1 from baseline and after six months of treatment of ILD patients' positives to anti-tRNA were included in the current study. At six months, patients were classified as with or without ILD progression RESULTS: Forty patients were included (anti-Jo1, anti-PL7, anti-PL12, and anti-Ej). Five patients (12.5%) had ILD progression and were characterized by higher levels of sCD163 at baseline. Baseline sCD163 serum levels showed good discriminatory capacity in patients with ILD progression. On the other hand, at follow-up, serum TGF-β1 levels significantly increased in both patients' groups, with and without progression CONCLUSION: Basal levels of sCD163 were higher in patients who later developed ILD progression and kinetics of both molecules suggests the participation of M2 macrophages in the development of ILD.

Mesenchymal stem cells exert their anti-asthmatic effects through macrophage modulation in a murine chronic asthma model

Despite numerous previous studies, the full action mechanism of the pathogenesis of asthma remains undiscovered, and the need for further investigation is increasing in order to identify more effective target molecules. Recent attempts to develop more efficacious treatments for asthma have incorporated mesenchymal stem cell (MSC)-based cell therapies. This study aimed to evaluate the anti-asthmatic effects of MSCs primed with Liproxstatin-1, a potent ferroptosis inhibitor. In addition, we sought to examine the changes within macrophage populations and their characteristics in asthmatic conditions. Seven-week-old transgenic mice, constitutively overexpressing lung-specific interleukin (IL)-13, were used to simulate chronic asthma. Human umbilical cord-derived MSCs (hUC-MSCs) primed with Liproxstatin-1 were intratracheally administered four days prior to sampling. IL-13 transgenic mice demonstrated phenotypes of chronic asthma, including severe inflammation, goblet cell hyperplasia, and subepithelial fibrosis. Ly6C⁺M2 macrophages, found within the pro-inflammatory CD11c⁺CD11b⁺ macrophages, were upregulated and showed a strong correlation with lung eosinophil counts. Liproxstatin-1-primed hUC-MSCs showed enhanced ability to downregulate the activation of T helper type 2 cells compared to naïve MSCs in vitro and reduced airway inflammation, particularly Ly6C⁺M2 macrophages population, and fibrosis in vivo. In conclusion, intratracheal administration is an effective method of MSC delivery, and macrophages hold great potential as an additional therapeutic target for asthma.

Alternatively activated macrophages promote airway inflammation through JAK3-STAT5-Fra2 in asthma

BACKGROUND

Fos-related antigen-2 (Fra-2) is a transcription factor belonging to the activator protein 1 (AP-1) family, which is associated with many chronic airway diseases such as asthma. Alternatively activated (M2) macrophages are associated with Fra2 in airway diseases such as pulmonary fibrosis. However, there is no specific study that explores the relationship between M2 macrophages and Fra2 in asthma.

OBJECTIVE

We hypothesized that a potential mechanism of allergic asthma could be that Fra2 is highly expressed in M2 macrophages through JAK3-STAT5 and facilitates the production of downstream T-helper 2 (Th2) cytokines, thus promoting the pathogenesis of asthma.

METHODS

Peripheral venous blood and airway tissue samples of patients with asthma and controls were obtained. Moreover, a C57BL/6 mouse model of asthma was established. Fra2 expression was detected using immunohistochemistry and immunofluorescence. Macrophages were obtained by flow sorting, and expression of the JAK3-STAT5-Fra2 signaling pathway was determined using PCR and western blotting. Enzyme-linked immunosorbent assay was used to determine M2 macrophage-associated Th2-type cytokine levels.

RESULTS

Fra2 was highly expressed in patients with asthma and asthmatic mice. The JAK3-STAT5 was a signal pathway related to the high expression of Fra2 in M2 macrophages. Moreover, we found that Fra2 could affect the production of Th2 cytokines downstream of M2 macrophages, including interleukin 4 (IL-4) and IL-13.

CONCLUSION

M2 macrophages could promote airway inflammation through JAK3-STAT5-Fra2 to induce allergic asthma. Our study offers a new insight to further understand the pathogenesis of asthma and also provides a new direction for targeted treatment.

Clinical and cytokine patterns of uncontrolled asthma with and without comorbid chronic rhinosinusitis: a cross-sectional study

Background

Asthma is significantly related to chronic rhinosinusitis (CRS) both in prevalence and severity. However, the clinical patterns of uncontrolled asthma with and without comorbid CRS are still unclear. This study aimed to explore the clinical characteristics and cytokine patterns of patients with uncontrolled asthma, with and without comorbid CRS.

Methods

22 parameters associated with demographic characteristics, CRS comorbidity, severity of airflow obstruction and airway inflammation, and inflammation type of asthma were collected and assessed in 143 patients with uncontrolled asthma. Different clusters were explored using two-step cluster analysis. Sputum samples were collected for assessment of Th1/Th2/Th17 and epithelium-derived cytokines.

Results

Comorbid CRS was identified as the most important variable for prediction of different clusters, followed by pulmonary function parameters and blood eosinophil level. Three clusters of patients were determined: Cluster 1 (n = 46) characterized by non-atopic patients with non-eosinophilic asthma without CRS, demonstrating moderate airflow limitation; Cluster 2 (n = 54) characterized by asthma patients with mild airflow limitation and CRS, demonstrating higher levels of blood eosinophils and immunoglobulin E (IgE) than cluster 1; Cluster 3 (n = 43) characterized by eosinophilic asthma patients with severe airflow limitation and CRS (46.5% with nasal polyps), demonstrating worst lung function, lowest partial pressure of oxygen (PaO₂), and highest levels of eosinophils, fraction of exhaled nitric oxide (FeNO) and IgE. Sputum samples from Cluster 3 showed significantly higher levels of Interleukin (IL)-5, IL-13, IL-33, and tumor necrosis factor (TNF)-α than the other two clusters; and remarkably elevated IL-4, IL-17 and interferon (IFN)-γ compared with cluster 2. The levels of IL-10 and IL-25 were not significantly different among the three clusters.

Conclusions

Uncontrolled asthma may be endotyped into three clusters characterized by CRS comorbidity and inflammatory cytokine patterns. Furthermore, a united-airways approach may be especially necessary for management of asthma patients with Type 2 features.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02028-3.

Altered Pattern of Macrophage Polarization as a Biomarker for Severity of Childhood Asthma

Purpose

Asthma causes a substantial morbidity and mortality burden in children and the pathogenesis of childhood asthma is not completely understood. Macrophages are heterogeneous with divergent M1/M2 polarization phenotypes in response to various stimulations during the inflammatory process. We aimed to investigate the pattern of macrophage polarization and its association with severity and exacerbation in asthmatic children.

Patients and Methods

Normal and asthmatic children aged 4–18 years were enrolled for 12 months. Children with asthma were further subgrouped according to their severity and the requirement for hospitalization during exacerbations. Clinical data were obtained from medical records. Peripheral blood samples were collected to analyze macrophage polarization, including M1, M2, and subsets, by flow cytometry.

Results

Fifty-one asthmatic cases and 27 normal controls were included in this study. The level of PM-2K⁺CD14⁺ but not PM-2K⁺CD14⁻ was decreased in asthmatic children. The levels of M2a (CCR7⁻CXCR1⁺), M2b (CCR7⁻CD86⁺), and M2c (CCR7⁻CCR2⁺) subsets, but not M1 (CCR7⁺CD86⁺), were increased in asthmatic children. The levels of M1 were decreased, but the levels of M2c were increased, in children with moderate asthma compared to those with mild asthma. The levels of PM-2K⁺CD14⁺ cells and M1 subsets were decreased, but the M2c subset cells were increased in asthmatic children requiring hospitalization during exacerbations.

Conclusion

Macrophage polarization may be involved in the pathogenesis of childhood asthma and is a potential biomarker of childhood asthma disease severity.

Dietary Docosahexaenoic Acid as a Potential Treatment for Semi-acute and Chronic Particle-Induced Pulmonary Inflammation in Balb/c Mice

Acute and chronic inflammation are vital contributing factors to pulmonary diseases which can be triggered by exposure to occupational and man-made particles; however, there are no established treatments. One potential treatment shown to have anti-inflammatory capabilities is the dietary supplement docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid found in fish oil. DHA's anti-inflammatory mechanisms are unclear for particle-induced inflammation; therefore, this study evaluated DHA as a prophylactic treatment for semi-acute and chronic particle-induced inflammation in vivo. Balb/c mice were fed a control or 1% DHA diet and exposed to dispersion media, an inflammatory multi-walled carbon nanotube (MWCNT), or crystalline silica (SiO₂) either once (semi-acute) or once a week for 4 weeks (chronic). The hypothesis was that DHA will decrease pulmonary inflammatory markers in response to particle-induced inflammation. Results indicated that DHA had a trending anti-inflammatory effect in mice exposed to MWCNT. There was a general decrease in inflammatory signals within the lung lavage fluid and upregulation of M2c macrophage gene expression in the spleen tissue. In contrast, mice exposed to SiO₂ while on the DHA diet significantly increased most inflammatory markers. However, DHA stabilized the phagolysosomal membrane upon prolonged treatment. This indicated that DHA treatment may depend upon certain inflammatory particle exposures as well as the length of the exposure.

The Flagellin:Allergen Fusion Protein rFlaA:Betv1 Induces a MyD88- and MAPK-Dependent Activation of Glucose Metabolism in Macrophages

TLR5 ligand flagellin-containing fusion proteins are potential vaccine candidates for many diseases. A recombinant fusion protein of flagellin A and the major birch pollen allergen Bet v 1 (rFlaA:Betv1) modulates immune responses in vitro and in vivo. We studied the effects of rFlaA:Betv1 on bone marrow-derived macrophages (BMDMs). BMDMs differentiated from BALB/c, C57BL/6, TLR5^-/-, or MyD88^-/- mice were pre-treated with inhibitors, stimulated with rFlaA:Betv1 or respective controls, and analyzed for activation, cytokine secretion, metabolic state, RNA transcriptome, and modulation of allergen-specific Th2 responses. Stimulation of BMDMs with rFlaA:Betv1 resulted in MyD88-dependent production of IL-1β, IL-6, TNF-α, IL-10, CD69 upregulation, and a pronounced shift towards glycolysis paralleled by activation of MAPK, NFκB, and mTOR signaling. Inhibition of either mTOR (rapamycin) or SAP/JNK-MAPK signaling (SP600125) resulted in dose-dependent metabolic suppression. In BMDM and T cell co-cultures, rFlaA:Betv1 stimulation suppressed rBet v 1-induced IL-5 and IL-13 secretion while inducing IFN-γ production. mRNA-Seq analyses showed HIF-1a, JAK, STAT, phagosome, NLR, NFκB, TNF, TLR, and chemokine signaling to participate in the interplay of cell activation, glycolysis, and immune response. rFlaA:Betv1 strongly activated BMDMs, resulting in MyD88-, MAPK-, and mTOR-dependent enhancement of glucose metabolism. Our results suggest macrophages are important target cells to consider during restauration of allergen tolerance during AIT.

Immunobiology of T Cells in Sjögren's Syndrome

Sjögren's syndrome (SjS) is a systemic autoimmune disease marked by xerostomia (dry mouth), keratoconjunctivitis sicca (eye dryness), and other systematic disorders. Its pathogenesis involves an inflammatory process that is characterized by lymphocytic infiltration into exocrine glands and other tissues. Although the development of ectopic lymphoid tissue and overproduction of autoantibodies by hyperactive B cells suggest that they may promote SjS development, treatment directed towards them fails to induce significant laboratory or clinical improvement. T cells are overwhelming infiltrators in most phases of the disease, and the involvement of multiple T cell subsets of suggests the extraordinary complexity of SjS pathogenesis. The factors, including various cellular subtypes and molecules, regulate the activation and suppression of T cells. T cell activation induces inflammatory cell infiltration, B cell activation, tissue damage, and metabolic changes in SjS. Knowledge of the pathways that link these T cell subtypes and regulation of their activities are not completely understood. This review comprehensively summarizes the research progress and our understanding of T cells in SjS, including CD4⁺ T cells, CD8⁺ T_RM cells, and innate T cells, to provide insights into for clinical treatment.

Periostin in Allergy and Inflammation

Matricellular proteins are involved in the crosstalk between cells and their environment and thus play an important role in allergic and inflammatory reactions. Periostin, a matricellular protein, has several documented and multi-faceted roles in health and disease. It is differentially expressed, usually upregulated, in allergic conditions, a variety of inflammatory diseases as well as in cancer and contributes to the development and progression of these diseases. Periostin has also been shown to influence tissue remodelling, fibrosis, regeneration and repair. In allergic reactions periostin is involved in type 2 immunity and can be induced by IL-4 and IL-13 in bronchial cells. A variety of different allergic diseases, among them bronchial asthma and atopic dermatitis (AD), have been shown to be connected to periostin expression. Periostin is commonly expressed in fibroblasts and acts on epithelial cells as well as fibroblasts involving integrin and NF-κB signalling. Also direct signalling between periostin and immune cells has been reported. The deposition of periostin in inflamed, often fibrotic, tissues is further fuelling the inflammatory process. There is increasing evidence that periostin is also expressed by epithelial cells in several of the above-mentioned conditions as well as in cancer. Augmented periostin expression has also been associated with chronic inflammation such as in inflammatory bowel disease (IBD). Periostin can be expressed in a variety of different isoforms, whose functions have not been elucidated yet. This review will discuss potential functions of periostin and its different isoforms in allergy and inflammation.

Platelets, Not an Insignificant Player in Development of Allergic Asthma

Allergic asthma is a chronic and heterogeneous pulmonary disease in which platelets can be activated in an IgE-mediated pathway and migrate to the airways via CCR3-dependent mechanism. Activated platelets secrete IL-33, Dkk-1, and 5-HT or overexpress CD40L on the cell surfaces to induce Type 2 immune response or interact with TSLP-stimulated myeloid DCs through the RANK-RANKL-dependent manner to tune the sensitization stage of allergic asthma. Additionally, platelets can mediate leukocyte infiltration into the lungs through P-selectin-mediated interaction with PSGL-1 and upregulate integrin expression in activated leukocytes. Platelets release myl9/12 protein to recruit CD4⁺CD69⁺ T cells to the inflammatory sites. Bronchoactive mediators, enzymes, and ROS released by platelets also contribute to the pathogenesis of allergic asthma. GM-CSF from platelets inhibits the eosinophil apoptosis, thus enhancing the chronic inflammatory response and tissue damage. Functional alterations in the mitochondria of platelets in allergic asthmatic lungs further confirm the role of platelets in the inflammation response. Given the extensive roles of platelets in allergic asthma, antiplatelet drugs have been tested in some allergic asthma patients. Therefore, elucidating the role of platelets in the pathogenesis of allergic asthma will provide us with new insights and lead to novel approaches in the treatment of this disease.

Interactions between NCR+ILC3s and the Microbiome in the Airways Shape Asthma Severity

Asthma is a heterogeneous disease whose development is shaped by a variety of environmental and genetic factors. While several recent studies suggest that microbial dysbiosis in the gut may promote asthma, little is known about the relationship between the recently discovered lung microbiome and asthma. Innate lymphoid cells (ILCs) have also been shown recently to participate in asthma. To investigate the relationship between the lung microbiome, ILCs, and asthma, we recruited 23 healthy controls (HC), 42 patients with non-severe asthma, and 32 patients with severe asthma. Flow cytometry analysis showed severe asthma associated with fewer natural cytotoxicity receptor (NCR)+ILC3s in the lung. Similar changes in other ILC subsets, macrophages, and monocytes were not observed. The asthma patients did not differ from the HC in terms of the alpha and beta-diversity of the lung and gut microbiomes. However, lung function correlated positively with both NCR+ILC3 frequencies and microbial diversity in the lung. Sputum NCR+ILC3 frequencies correlated positively with lung microbiome diversity in the HC, but this relationship was inversed in severe asthma. Together, these data suggest that airway NCR+ILC3s may contribute to a healthy commensal diversity and normal lung function.

Schistosoma mansoni infection is associated with decreased risk of respiratory allergy symptoms and low production of CCL2

OBJECTIVES

We measured the production of cytokines, chemokines and antibodies involved in allergic responses and sCD23 levels during Schistosoma mansoni infection.

METHODS

Individuals (n = 164) were selected using the ISAAC questionnaire and parasitological exams. The subjects were divided as follows: those infected individuals with allergy-related symptoms (A-I), those with allergy-related symptoms only (A-NI); those only infected (NA-I); and those non-infected individuals without allergy-related symptoms (NA-NI). We used supernatants from cell culture (mitogenic stimulation) to measure cytokine and chemokine levels using cytometric bead arrays. Serum levels of anti-Ascaris lumbricoides (Asc) and anti-Blomia tropicalis IgE were measured using ImmunoCAP, and sCD23 was measured using ELISA.

RESULTS

Schistosoma mansoni infection was associated with a lower risk of allergy-related symptoms. In A-I, there were higher levels of TNF-α, IL-10, IL-6, IFN-γ and CXCL8 than in NA-NI group, with TNF-α and IL-6 also at higher levels compared to A-NI group. Levels of IL-6, CXCL8, total and anti-Asc IgE, as well as the numbers of eosinophils, were higher in NA-I than in NA-NI, and the antibodies were also lower in A-NI than in NA-I group. In AI and NA-I, there was less production of CCL2 than in NA-NI. There were no differences in the levels of IL-2, IL-4, IL-17, CCL5, sCD23 and anti-Blomia IgE.

CONCLUSIONS

Patients with allergy-related symptoms and infected (simultaneously) had higher levels of IL-10; due to the infection, there was increased production of IL-6 and CXCL8 and less CCL2. These data may characterize deviation to Th1 or attenuation of the Th2 response in allergy sufferers in areas endemic for schistosomiasis.

The Macrophage Response Is Driven by Mesenchymal Stem Cell-Mediated Metabolic Reprogramming

Mesenchymal stem cells (MSCs) are multipotent adult stromal cells widely studied for their regenerative and immunomodulatory properties. They are capable of modulating macrophage plasticity depending on various microenvironmental signals. Current studies have shown that metabolic changes can also affect macrophage fate and function. Indeed, changes in the environment prompt phenotype change. Therefore, in this review, we will discuss how MSCs orchestrate macrophage’s metabolic plasticity and the impact on their function. An improved understanding of the crosstalk between macrophages and MSCs will improve our knowledge of MSC’s therapeutic potential in the context of inflammatory diseases, cancer, and tissue repair processes in which macrophages are pivotal.

The airway epithelium during infancy and childhood: A complex multicellular immune barrier. Basic review for clinicians

The airway epithelium is a complex multicellular layer that extends from the nasopharynx to the small airways. It functions as an immune respiratory barrier during early life that develops, matures, and regenerates to adapt to the changes in the environment. While airway epithelial abnormalities have been identified in several clinical disorders, there is increasing interest in understanding its basic regulation and structure in humans. Indeed, recent advances in technology (e.g. single-cell analysis and new human airway epithelial cell models) have allowed us to identify additional cellular subtypes and functions that overall have greatly improved our understanding of the airway epithelium during health and disease. In this review we summarize key features of the airway epithelium including: 1) multilayer structure and cell heterogeneity; 2) adaptability to different environmental and developmental stimuli; 3) innate recognition; and 4) orchestration of immune responses. We discuss these features with a translational and clinical prospective focusing on the development of human respiratory immunity, particularly during early life.

Assessment of the safety and anti-inflammatory effects of three Bacillus strains in the respiratory tract

Chronic respiratory diseases are part of accumulating health problems partly due to worldwide increase in air pollution. By their antimicrobial and immunomodulatory properties, some probiotics constitute promising alternatives for the prevention and treatment of chronic respiratory diseases. We have isolated Bacillus strains from Korean fermented foods and selected three potentially probiotic strains (two Bacillus subtilis and one Bacillus amyloliquefaciens) based on safety, antimicrobial efficacy, activity against airborne pathogens and their immunomodulatory properties in vivo. Safety evaluation included in silico analysis for confirming absence of virulence genes. Safety for the respiratory tract was confirmed by an in vivo pathogenicity test using a murine model. Antimicrobial activity was displayed against several airborne pathogens. Potential antimicrobial metabolites such as 2,3-butanediol and propylene glycol were identified as possible antagonistic agents. Immunomodulatory properties in vitro were confirmed by upregulation of IL-10 expression in a macrophage cell line. Intranasal instillation and inhalation in an ovalbumin (OVA)-induced lung inflammation murine model reduced T helper type 2 (Th2) cytokines at transcriptional and protein levels in the lungs. The safety and potentially beneficial role of these Bacillus strains could be demonstrated for the respiratory tract of a murine model.

Macrophages in Lung Injury, Repair, and Fibrosis

Fibrosis progression in the lung commonly results in impaired functional gas exchange, respiratory failure, or even death. In addition to the aberrant activation and differentiation of lung fibroblasts, persistent alveolar injury and incomplete repair are the driving factors of lung fibrotic response. Macrophages are activated and polarized in response to lipopolysaccharide- or bleomycin-induced lung injury. The classically activated macrophage (M1) and alternatively activated macrophage (M2) have been extensively investigated in lung injury, repair, and fibrosis. In the present review, we summarized the current data on monocyte-derived macrophages that are recruited to the lung, as well as alveolar resident macrophages and their polarization, pyroptosis, and phagocytosis in acute lung injury (ALI). Additionally, we described how macrophages interact with lung epithelial cells during lung repair. Finally, we emphasized the role of macrophage polarization in the pulmonary fibrotic response, and elucidated the potential benefits of targeting macrophage in alleviating pulmonary fibrosis.

Docosahexaenoic acid impacts macrophage phenotype subsets and phagolysosomal membrane permeability with particle exposure

Inhalation of particles results in pulmonary inflammation; however, treatments are currently lacking. Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid shown to exhibit anti-inflammatory capabilities. The impact of DHA on particle-induced inflammation is unclear; therefore, the aim of this study was to examine the hypothesis that DHA downregulates macrophage inflammatory responses by altering phagolysosomal membrane permeability (LMP) and shifting macrophage phenotype. Isolated Balb/c alveolar macrophages (AM) were polarized into M1, M2a, M2b, or M2c phenotypes in vitro, treated with DHA, and exposed to a multi-walled carbon nanotube (MWNCT) or crystalline silica (SiO₂). Results showed minimal cytotoxicity, robust effects for silica particle uptake, and LMP differences between phenotypes. Docosahexaenoic acid prevented these effects to the greatest extent in M2c phenotype. To determine if DHA affected inflammation similarly in vivo, Balb/c mice were placed on a control or 1% DHA diet for 3 weeks, instilled with the same particles, and assessed 24 hr following instillation. Data demonstrated that in contrast to in vitro findings, DHA increased pulmonary inflammation and LMP. These results suggest that pulmonary responses in vivo may not necessarily be predicted from single-cell responses in vitro.

β-Glucan-induced reprogramming of human macrophages inhibits NLRP3 inflammasome activation in cryopyrinopathies

Exposure of mononuclear phagocytes to β-glucan, a naturally occurring polysaccharide, contributes to the induction of innate immune memory, which is associated with long-term epigenetic, metabolic, and functional reprogramming. Although previous studies have shown that innate immune memory induced by β-glucan confers protection against secondary infections, its impact on autoinflammatory diseases, associated with inflammasome activation and IL-1β secretion, remains poorly understood. In particular, whether β-glucan-induced long-term reprogramming affects inflammasome activation in human macrophages in the context of these diseases has not been explored. We found that NLRP3 inflammasome-mediated caspase-1 activation and subsequent IL-1β production were reduced in β-glucan-reprogrammed macrophages. β-Glucan acted upstream of the NLRP3 inflammasome by preventing potassium (K+) efflux, mitochondrial ROS (mtROS) generation, and, ultimately, apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization and speck formation. Importantly, β-glucan-induced memory in macrophages resulted in a remarkable attenuation of IL-1β secretion and caspase-1 activation in patients with an NLRP3-associated autoinflammatory disease, cryopyrin-associated periodic syndromes (CAPS). Our findings demonstrate that β-glucan-induced innate immune memory represses IL-1β-mediated inflammation and support its potential clinical use in NLRP3-driven diseases.

Biflavonoid-rich fraction from Daphne pseudomezereum var. koreana Hamaya exerts anti-inflammatory effect in an experimental animal model of allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Daphne pseudomezereum var. koreana Hamaya is distributed in the Gangwon-do of South Korea and is traditionally used to treat chronic inflammatory diseases, including rheumatoid arthritis.

AIM OF THE STUDY

We investigated the anti-inflammatory effect of biflavonoid-rich fraction (BF) obtained from an extract of D. pseudomezereum leaves on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and mouse model of ovalbumin (OVA)-induced allergic asthma.

MATERIALS AND METHODS

Neochamaejasmin B (NB) and chamaejasmin D (CD) were spectroscopically characterized as major components of BF obtained from the leaves of D. pseudomezereum. RAW264.7 cells pretreated with NB, CD and BF and activated by LPS (500 ng/ml) were used to assess the anti-inflammatory effects of these materials in vitro. To evaluate the protective effect of BF on allergic asthma, female BALB/c mice were sensitized to OVA by intraperitoneal (i.p.) injection and treated with BF by oral administration (15 or 30 mg/kg).

RESULTS

Pretreatment with BF inhibited LPS-stimulated nitric oxide (NO), TNF-α and IL-6, and led to upregulation of heme oxygenase-1 (HO-1) in RAW264.7 macrophages. Orally administered BF significantly inhibited the recruitment of eosinophils and the production of IL-5, IL-6, IL-13 and MCP-1 as judged by the analysis of BALF from OVA-induced asthma animal model. BF also decreased the levels of IgE in the serum of asthmatic mice. BF suppressed the influx of inflammatory cells into nearby airways and the hypersecretion of mucus by the airway epithelium of asthmatic mice. In addition, the increase in Penh in asthmatic mice was reduced by BF administration. Furthermore, BF led to Nrf2 activation and HO-1 induction in the lungs of mice.

CONCLUSIONS

These data have shown the anti-asthmatic effects of BF, and therefore we expect that BF may be a potential candidate as a natural drug/nutraceutical for the prevention and treatment of allergic asthma.

1,4NQ-BC enhances the lung inflammation by mediating the secretion of IL-33 which derived from macrophages

Black carbon (BC) is a product of incomplete combustion of fossil fuels and vegetation. The compelling evidence has demonstrated that it has a close relationship with several respiratory and cardiovascular diseases. BC provides the reactive sites and surfaces to absorb various chemicals, such as polycyclic aromatic hydrocarbons (PAH). Naphthoquinone is a typical PAHs which was found in particulate matter (PM) and 1,4NQ-BC owned high oxidative potential and cytotoxicity. IL-33 is an alarmin which increases innate immunity through Th2 responses. It was reported that IL-33 was a potent inducer of pro-inflammatory cytokines, like IL-6. In our previous study, it was revealed that 1,4NQ-BC instilled intratracheally to mice could trigger the lung inflammation and stimulate the secretion of IL-33 in lung tissue. We found that IL-33 could induce inflammation in lung itself. When the macrophages were eliminated, the secretion of IL-33 was reduced and the pathological damage in the lung was relieved after exposure to 1,4NQ-BC. Both MAPK and PI3K/AKT signal pathways were involved in the process of IL-33 secretion and the lung inflammation induced by 1,4NQ-BC. The findings herein support the notion that after exposure to 1,4NQ-BC, the increased secretion of IL-33 was mainly derived from macrophages through both MAPK and PI3K/AKT signal pathways.

miR-142-5p and miR-130a-3p regulate pulmonary macrophage polarization and asthma airway remodeling

Macrophages are key regulators of the development and progression of asthma, facilitating deleterious airway remodeling in affected patients. Immune cell function is tightly regulated by microRNAs (miRNAs), but how these miRNAs impact macrophage-mediated airway remodeling in the context of asthma remains to be determined. In this study, we utilized an ovalbumin (OVA)-based murine model of asthma to evaluate the importance of miRNAs within these macrophages. We found that macrophages from mice that had been sensitized with and exposed to OVA expressed higher levels of M2-like phenotypic markers and exhibited significantly altered expression of both miR-142-5p and miR-130a-3p. When these isolated pulmonary macrophages were cultured in vitro, we determined that transfecting them with miR-142-5p antisense oligonucleotide (ASO) or miR-130a-3p mimics was sufficient to inhibit the ability of interleukin-4 to induce M2 cytokine production. We additionally confirmed the in vivo relevance of these miRNAs in a Ccr2^-/- murine model system mimicking asthma. Specifically, we determined that transfecting monocytes with miR-142-5p ASO and/or miR-130a-3p mimics was sufficient to disrupt the ability of these cells to promote airway remodeling. As such, these findings reveal that miR-142-5p and miR-130a-3p dysregulation are important factors governing the polarization of macrophages and associated airway remodeling in OVA-sensitized mice.

The Role of IgG4 in the Fine Tuning of Tolerance in IgE-Mediated Allergy and Cancer

Among the four immunoglobulin G (IgG) subclasses, IgG4 is the least represented in serum of a healthy human and it is considered an “odd” antibody. The IgG4 antibody has unique structural features that affect its biological function. These include the ability to undergo antigen-binding fragment (Fab)-arm exchange, to create fragment crystallizable (Fc) – Fc binding with other IgG4 and other IgG subclass antibodies, have a unique affinity profile for Fc gamma receptors (FcγRs) and no binding to complement component C1q. Altogether, these characteristics support anti-inflammatory roles of IgG4 leading to immune tolerance. Under conditions of chronic antigenic stimulation and Th2-type inflammation, both tissue and serum IgG4 levels are increased. This review seeks to highlight how in allergen immunotherapy IgG4 can confer a protective role as a “blocking” antibody and safeguard from subsequent allergen exposure, while IgG4 can confer immunomodulatory functions to support malignancy. While Th2 conditions drive polarization of macrophages to the M2a subtype, chronic antigen stimulation drives B cell class switching to IgG4 to further support phenotypical macrophage changes towards an M2b-like state. M2b-like macrophages can secrete chemokine (C-C motif) ligand 1 (CCL1) and interleukin-10 (IL-10) to support regulatory cell recruitment and to further shape a tolerogenic microenvironment. Thereby, IgG4 have a Janus-faced role, favorable in allergy but detrimental in cancer.

Airway Epithelial Dynamics in Allergy and Related Chronic Inflammatory Airway Diseases

Allergic rhinitis, chronic rhinosinusitis, and asthma are highly prevalent, multifactorial chronic airway diseases. Several environmental and genetic factors affect airway epithelial dynamics leading to activation of inflammatory mechanisms in the airways. This review links environmental factors to host epithelial immunity in airway diseases. Understanding altered homeostasis of the airway epithelium might provide important targets for diagnostics and therapy of chronic airway diseases.

Alternatively activated macrophages; a double-edged sword in allergic asthma

BACKGROUND

Macrophages are heterogenous phagocytic cells with an important role in the innate immunity. They are, also, significant contributors in the adaptive immune system. Macrophages are the most abundant immune cells in the lung during allergic asthma, which is the most common chronic respiratory disease of both adults and children. Macrophages activated by Th1 cells are known as M1 macrophages while those activated by IL-4 and IL-13 are called alternatively activated macrophages (AAM) or M2 cells. AAM are subdivided into four distinct subtypes (M2a, M2b, M2c and M2d), depending on the nature of inducing agent and the expressed markers. BODY: IL-4 is the major effector cytokine in both alternative activation of macrophages and pathogenesis of asthma. Thus, the role of M2a macrophages in asthma is a major concern. However, this is controversial. Therefore, further studies are required to improve our knowledge about the role of IL-4-induced macrophages in allergic asthma, through precisive elucidation of the roles of specific M2a proteins in the pathogenesis of asthma. In the current review, we try to illustrate the different functions of M2a macrophages (protective and pathogenic roles) in the pathogenesis of asthma, including explanation of how different M2a proteins and markers act during the pathogenesis of allergic asthma. These include surface markers, enzymes, secreted proteins, chemokines, cytokines, signal transduction proteins and transcription factors.

CONCLUSIONS

AAM is considered a double-edged sword in allergic asthma. Finally, we recommend further studies that focus on increased selective expression or suppression of protective and pathogenic M2a markers.