Granzyme K- and amphiregulin-expressing cytotoxic T cells and activated extrafollicular B cells are potential drivers of IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD), an example of a type I immune disease, is an immune-mediated fibrotic disorder characterized by dysregulated resolution of severe inflammation and wound healing. However, truly dominant or pathognomonic autoantibodies related to IgG4-RD are not identified.

OBJECTIVE

We sought to perform single-cell RNA sequencing and T-cell receptor and B-cell receptor sequencing to obtain a comprehensive, unbiased view of tissue-infiltrating T and B cells.

METHODS

We performed unbiased single-cell RNA-sequencing analysis for the transcriptome and T-cell receptor sequencing and B-cell receptor sequencing on sorted CD3+ T or CD19+ B cells from affected tissues of patients with IgG4-RD. We also conducted quantitative analyses of CD3+ T-cell and CD19+ B-cell subsets in 68 patients with IgG4-RD and 30 patients with Sjögren syndrome.

RESULTS

Almost all clonally expanded T cells in these lesions were either Granzyme K (GZMK)-expressing CD4+ cytotoxic T cells or GZMK+CD8+ T cells. These GZMK-expressing cytotoxic T cells also expressed amphiregulin and TGF-β but did not express immune checkpoints, and the tissue-infiltrating CD8+ T cells were phenotypically heterogeneous. MKI67+ B cells and IgD-CD27-CD11c-CXCR5- double-negative 3 B cells were clonally expanded and infiltrated affected tissue lesions. GZMK+CD4+ cytotoxic T cells colocalized with MKI67+ B cells in the extrafollicular area from affected tissue sites.

CONCLUSIONS

The above-mentioned cells likely participate in T-B collaborative events, suggesting possible avenues for targeted therapies. Our findings were validated using orthogonal approaches, including multicolor immunofluorescence and the use of comparator disease groups, to support the central role of cytotoxic CD4+ and CD8+ T cells expressing GZMK, amphiregulin, and TGF-β in the pathogenesis of inflammatory fibrotic disorders.

The ST2+ Treg/amphiregulin axis protects from immune-mediated hepatitis

Introduction

The alarmin IL-33 has been implicated in the pathology of immune-mediated liver diseases. IL-33 activates regulatory T cells (Tregs) and type 2 innate lymphoid cells (ILC2s) expressing the IL-33 receptor ST2. We have previously shown that endogenous IL-33/ST2 signaling activates ILC2s that aggravate liver injury in murine immune-mediated hepatitis. However, treatment of mice with exogenous IL-33 before induction of hepatitis ameliorated disease severity. Since IL-33 induces expression of amphiregulin (AREG) crucial for Treg function, we investigated the immunoregulatory role of the ST2+ Treg/AREG axis in immune-mediated hepatitis.

Methods

C57BL/6, ST2-deficient (Il1rl1-/-) and Areg-/- mice received concanavalin A to induce immune-mediated hepatitis. Foxp3Cre+ x ST2fl/fl mice were pre-treated with IL-33 before induction of immune-mediated hepatitis. Treg function was assessed by adoptive transfer experiments and suppression assays. The effects of AREG and IL-33 on ST2+ Tregs and ILC2s were investigated in vitro. Immune cell phenotype was analyzed by flow cytometry.

Results and discussion

We identified IL-33-responsive ST2+ Tregs as an effector Treg subset in the murine liver, which was highly activated in immune-mediated hepatitis. Lack of endogenous IL-33 signaling in Il1rl1-/- mice aggravated disease pathology. This was associated with reduced Treg activation. Adoptive transfer of exogenous IL-33-activated ST2+ Tregs before induction of hepatitis suppressed inflammatory T-cell responses and ameliorated disease pathology. We further showed increased expression of AREG by hepatic ST2+ Tregs and ILC2s in immune-mediated hepatitis. Areg-/- mice developed more severe liver injury, which was associated with enhanced ILC2 activation and less ST2+ Tregs in the inflamed liver. Exogenous AREG suppressed ILC2 cytokine expression and enhanced ST2+ Treg activation in vitro. In addition, Tregs from Areg-/- mice were impaired in their capacity to suppress CD4+ T-cell activation in vitro. Moreover, application of exogenous IL-33 before disease induction did not protect Foxp3Cre+ x ST2fl/fl mice lacking ST2+ Tregs from immune-mediated hepatitis. In summary, we describe an immunoregulatory role of the ST2+ Treg/AREG axis in immune-mediated hepatitis, in which AREG suppresses the activation of hepatic ILC2s while maintaining ST2+ Tregs and reinforcing their immunosuppressive capacity in liver inflammation.

A distinct "repair" role of regulatory T cells in fracture healing

Regulatory T cells (Tregs) suppress immune responses and inflammation. Here, we described the distinct nonimmunological role of Tregs in fracture healing. The recruitment from the circulation pool, peripheral induction, and local expansion rapidly enriched Tregs in the injured bone. The Tregs in the injured bone displayed superiority in direct osteogenesis over Tregs from lymphoid organs. Punctual depletion of Tregs compromised the fracture healing process, which leads to increased bone nonunion. In addition, bone callus Tregs showed unique T-cell receptor repertoires. Amphiregulin was the most overexpressed protein in bone callus Tregs, and it can directly facilitate the proliferation and differentiation of osteogenic precursor cells by activation of phosphatidylinositol 3-kinase/protein kinase B signaling pathways. The results of loss- and gain-function studies further evidenced that amphiregulin can reverse the compromised healing caused by Treg dysfunction. Tregs also enriched in patient bone callus and amphiregulin can promote the osteogenesis of human pre-osteoblastic cells. Our findings indicate the distinct and nonredundant role of Tregs in fracture healing, which will provide a new therapeutic target and strategy in the clinical treatment of fractures.

Increased CD8+ tissue resident memory T cells, regulatory T cells and activated natural killer cells in systemic sclerosis lungs

OBJECTIVE

Multiple observations indicate a role for lymphocytes in driving autoimmunity in SSc. While T and NK cells have been studied in SSc whole blood and bronchoalveolar lavage fluid, their role remains unclear, partly because no studies have analysed these cell types in SSc-interstitial lung disease (ILD) lung tissue. This research aimed to identify and analyse the lymphoid subpopulations in SSc-ILD lung explants.

METHODS

Lymphoid populations from 13 SSc-ILD and 6 healthy control (HC) lung explants were analysed using Seurat following single-cell RNA sequencing. Lymphoid clusters were identified by their differential gene expression. Absolute cell numbers and cell proportions in each cluster were compared between cohorts. Additional analyses were performed using pathway analysis, pseudotime and cell ligand-receptor interactions.

RESULTS

Activated CD16+ NK cells, CD8+ tissue resident memory T cells and Treg cells were proportionately higher in SSc-ILD compared with HC lungs. Activated CD16+ NK cells in SSc-ILD showed upregulated granzyme B, IFN-γ and CD226. Amphiregulin, highly upregulated by NK cells, was predicted to interact with epidermal growth factor receptor on several bronchial epithelial cell populations. Shifts in CD8+ T cell populations indicated a transition from resting to effector to tissue resident phenotypes in SSc-ILD.

CONCLUSIONS

SSc-ILD lungs show activated lymphoid populations. Activated cytotoxic NK cells suggest they may kill alveolar epithelial cells, while their expression of amphiregulin suggests they may also induce bronchial epithelial cell hyperplasia. CD8+ T cells in SSc-ILD appear to transition from resting to the tissue resident memory phenotype.

Amphiregulin improves ventricular remodeling after myocardial infarction by modulating autophagy and apoptosis

Myocardial infarction (MI) is defined as sudden ischemic death of myocardial tissue. Amphiregulin (Areg) regulates cell survival and is crucial for the healing of tissues after damage. However, the functions and mechanisms of Areg after MI remain unclear. Here, we aimed to investigate Areg's impact on myocardial remodeling. Mice model of MI was constructed and Areg-/- mice were used. Expression of Areg was analyzed using western blotting, RT-qPCR, flow cytometry, and immunofluorescence staining. Echocardiographic analysis, Masson's trichrome, and triphenyltetrazolium chloride staining were used to assess cardiac function and structure. RNA sequencing was used for unbiased analysis. Apoptosis and autophagy were determined by western blotting, TUNEL staining, electron microscopy, and mRFP-GFP-LC3 lentivirus. Lysosomal acidity was determined by Lysotracker staining. Areg was elevated in the infarct border zone after MI. It was mostly secreted by macrophages. Areg deficiency aggravated adverse ventricular remodeling, as reflected by worsening cardiac function, a lower survival rate, increased scar size, and interstitial fibrosis. RNA sequencing analyses showed that Areg related to the epidermal growth factor receptor (EGFR), phosphoinositide 3-kinase/protein kinase B (PI3K-Akt), mammalian target of rapamycin (mTOR) signaling pathways, V-ATPase and lysosome pathways. Mechanistically, Areg exerts beneficial effects via increasing lysosomal acidity to promote autophagosome clearance, and activating the EGFR/PI3K/Akt/mTOR signaling pathway, subsequently inhibiting excessive autophagosome formation and apoptosis in cardiomyocytes. This study provides a novel evidence for the role of Areg in inhibiting ventricular remodeling after MI by regulating autophagy and apoptosis and identifies Areg as a potential therapeutic target in ventricular remodeling after MI.

Amphiregulin in lung diseases: A review

Amphiregulin is a member of the EGFR family, which is involved in many physiological and pathological processes through its binding with EGFR. Studies have found that amphiregulin plays an important role in the occurrence and development of lung diseases. This paper mainly reviews the structure and function of amphiregulin and focuses on the important role of amphiregulin in lung diseases.

Amphiregulin Exerts Proangiogenic Effects in Developing Murine Lungs

Interrupted lung angiogenesis is a hallmark of bronchopulmonary dysplasia (BPD); however, druggable targets that can rescue this phenotype remain elusive. Thus, our investigation focused on amphiregulin (Areg), a growth factor that mediates cellular proliferation, differentiation, migration, survival, and repair. While Areg promotes lung branching morphogenesis, its effect on endothelial cell (EC) homeostasis in developing lungs is understudied. Therefore, we hypothesized that Areg promotes the proangiogenic ability of the ECs in developing murine lungs exposed to hyperoxia. Lung tissues were harvested from neonatal mice exposed to normoxia or hyperoxia to determine Areg expression. Next, we performed genetic loss-of-function and pharmacological gain-of-function studies in normoxia- and hyperoxia-exposed fetal murine lung ECs. Hyperoxia increased Areg mRNA levels and Areg+ cells in whole lungs. While Areg expression was increased in lung ECs exposed to hyperoxia, the expression of its signaling receptor, epidermal growth factor receptor, was decreased, indicating that hyperoxia reduces Areg signaling in lung ECs. Areg deficiency potentiated hyperoxia-mediated anti-angiogenic effects. In contrast, Areg treatment increased extracellular signal-regulated kinase activation and exerted proangiogenic effects. In conclusion, Areg promotes EC tubule formation in developing murine lungs exposed to hyperoxia.

Glucose upregulates amphiregulin in oral dysplastic keratinocytes: A potential role in diabetes-associated oral carcinogenesis

BACKGROUND

Compelling evidence implicates diabetes-associated hyperglycemia as a promoter of tumor progression in oral potentially malignant disorders (OPMD). Yet, information on hyperglycemia-induced cell signaling networks in oral oncology remains limited. Our group recently reported that glucose-rich conditions significantly enhance oral dysplastic keratinocyte viability and migration through epidermal growth factor receptor (EGFR) activation, a pathway strongly linked to oral carcinogenesis. Here, we investigated the basal metabolic phenotype in these cells and whether specific glucose-responsive EGFR ligands mediate these responses.

METHODS

Cell energy phenotype and lactate concentration were evaluated via commercially available assays. EGFR ligands in response to normal (5 mM) or high (20 mM) glucose were analyzed by quantitative real-time PCR, ELISA, and western blotting. Cell viability and migration assays were performed in the presence of pharmacological inhibitors or RNA interference.

RESULTS

When compared to normal keratinocytes, basal glycolysis in oral dysplastic keratinocytes was significantly elevated. In highly glycolytic cells, high glucose-activated EGFR increasing viability and migration. Notably, we identified amphiregulin (AREG) as the predominant glucose-induced EGFR ligand. Indeed, enhanced cell migration in response to high glucose was blunted by EGFR inhibitor cetuximab and AREG siRNA. Conversely, AREG treatment under normal glucose conditions significantly increased cell viability, migration, lactate levels, and expression of glycolytic marker pyruvate kinase M2.

CONCLUSION

These novel findings point to AREG as a potential high glucose-induced EGFR activating ligand in highly glycolytic oral dysplastic keratinocytes. Future studies are warranted to gain more insight into the role of AREG in hyperglycemia-associated OPMD tumor progression.

Inhibitory Effect of Jinkui Shenqi Pills on Glucocorticoid-Enhanced Axial Length Elongation in Experimentally Myopic Guinea Pigs

OBJECTIVE

To explore the underlying mechanism of inhibition by Jinkui Shenqi Pills (JKSQP) on glucocorticoid-enhanced axial length elongation in experimental lens-induced myopia (LIM) guinea pigs.

METHODS

Sixty 2-week old male guinea pigs were randomly divided into 4 groups with 15 guinea pigs in each group, according to the random numbers generated by SPSS software: control, LIM, saline and JKSQP groups. The control group includes animals with no treatment, while the guinea pigs in the other 3 groups received lens-induced myopization on the right eyes throughout the experiment (for 8 weeks). The saline and JKSQP groups were given daily intraperitoneal injections of 10 mg/kg hydrocortisone for 2 consecutive weeks at the same time, and then orally administered either saline or JKSQP [13.5 g/(kg•d) for 6 consecutive weeks. Body weight, anal temperature and animal appearance were observed and recorded to evaluate the GC-associated symptoms. The ocular parameters, including refraction and axial length, were measured by streak retinoscopy and A-scan ultrasonography, respectively. The levels of plasma hormones associated with the hypothalamic-pituitary-adrenal axis (HPAA), including free triiodothyronine, free thyroxine, estradiol and testosterone, were measured by radioimmunoassay, and cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate were measured by enzyme-linked immunosorbent assay. In addition, the mRNA and protein expressions of retinal amphiregulin (AREG) was measured by quantitative real-time polymerase chain reaction and Western blotting, respectively.

RESULTS

JKSQP effectively increased body weight and anal temperature, improved animal appearance and suppressed axial length elongation in glucocorticoid-enhanced myopic guinea pigs with normalization of 4 HPAA-associated plasma hormones (all P<0.05). The plasma level of cAMP was significantly increased, whereas the plasma level of cGMP and the mRNA and protein expressions of retinal AREG were decreased after treatment with JKSQP (all P<0.05).

CONCLUSION

JKSQP exhibited a significant inhibitory effect on axial length elongation with decreased expression of AREG in the retina, and normalized 4 HPAA-associated plasma hormones and the expression of cAMP and cGMP in GC-enhanced myopic guinea pigs.

Glutamine metabolism controls amphiregulin-facilitated chemoresistance to cisplatin in human chondrosarcoma

Chondrosarcoma is the second most common type of bone cancer. At present, the most effective clinical course of action is surgical resection. Cisplatin is the chemotherapeutic medication most widely used for the treatment of chondrosarcoma; however, its effectiveness is severely hampered by drug resistance. In the current study, we compared cisplatin-resistant chondrosarcoma SW1353 cells with their parental cells via RNA sequencing. Our analysis revealed that glutamine metabolism is highly activated in resistant cells but glucose metabolism is not. Amphiregulin (AR), a ligand of the epidermal growth factor receptor, enhances glutamine metabolism and supports cisplatin resistance in human chondrosarcoma by promoting NADPH production and inhibiting reactive oxygen species (ROS) accumulation. The MEK, ERK, and NrF2 signaling pathways were shown to regulate AR-mediated alanine-serine-cysteine transporter 2 (ASCT2; also called SLC1A5) and glutaminase (GLS) expression as well as glutamine metabolism in cisplatin-resistant chondrosarcoma. The knockdown of AR expression in cisplatin-resistant chondrosarcoma cells was shown to reduce the expression of SLC1A5 and GLS in vivo. These results indicate that AR and glutamine metabolism are worth pursuing as therapeutic targets in dealing with cisplatin-resistant human chondrosarcoma.

EGF, TGF-α and Amphiregulin Differently Regulate Endometrium-Derived Mesenchymal Stromal/Stem Cells

The prototypical receptor tyrosine kinase epidermal growth factor receptor (EGFR) is regulated by a set of its ligands, which determines the specificity of signaling and intracellular fate of the receptor. The EGFR signaling system is well characterized in immortalized cell lines such as HeLa derived from tumor tissues, but much less is known about EGFR function in untransformed multipotent stromal/stem cells (MSCs). We compared the effect of epidermal growth factor (EGF), transforming growth factor-α (TGF-α) and amphiregulin (AREG) on physiological responses in endometrial MSCs (enMSC) and HeLa cells. In addition, using Western blotting and confocal microscopy, we studied the internalization and degradation of EGFR stimulated by the three ligands in these cell lines. We demonstrated that unlike HeLa, EGF and TGF-α, but not AREG, stimulated enMSC proliferation and prevented decidual differentiation in an EGFR-dependent manner. In HeLa cells, EGF targeted EGFR for degradation, while TGF-α stimulated its recycling. Surprisingly, in enMSC, both ligands caused EGFR degradation. In both cell lines, AREG-EGFR internalization was not registered. In HeLa cells, EGFR was degraded within 2 h, restoring its level in 24 h, while in enMSC, degradation took more than 4-8 h, and the low EGFR level persisted for several days. This indicates that EGFR homeostasis in MSCs may differ significantly from that in immortalized cell lines.

Transcriptional and chromatin profiling of human blood innate lymphoid cell subsets sheds light on HIV-1 pathogenesis

Innate lymphoid cells (ILCs) are a diverse population of cells that include NK cells and contribute to tissue homeostasis and repair, inflammation, and provide protection from infection. The interplay between human blood ILCs, as well as their responses to HIV-1 infection, remains poorly understood. This study used transcriptional and chromatin profiling to explore these questions. Transcriptional profiling and flow cytometry analysis support that there are four main ILC subsets found in human blood. Unlike in mice, human NK cells expressed the tissue repair protein amphiregulin (AREG). AREG production was induced by TCF7/WNT, IL-2, and IL-15, and inhibited by TGFB1, a cytokine increased in people living with HIV-1. In HIV-1 infection, the percentage of AREG+ NK cells correlated positively with the numbers of ILCs and CD4+ T cells but negatively with the concentration of inflammatory cytokine IL-6. NK-cell knockout of the TGFB1-stimulated WNT antagonist RUNX3 increased AREG production. Antiviral gene expression was increased in all ILC subsets from HIV-1 viremic people, and anti-inflammatory gene MYDGF was increased in an NK-cell subset from HIV-1-infected people whose viral load was undetectable in the absence of antiretroviral therapy. The percentage of defective NK cells in people living with HIV-1 correlated inversely with ILC percentage and CD4+ T-cell counts. CD4+ T cells and their production of IL-2 prevented the loss of NK-cell function by activating mTOR. These studies clarify how ILC subsets are interrelated and provide insight into how HIV-1 infection disrupts NK cells, including an uncharacterized homeostatic function in NK cells.

Schwann cell-derived amphiregulin enhances nerve regeneration via supporting the proliferation and migration of Schwann cells and the elongation of axons

Peripheral nerves have limited regeneration ability following nerve injury. Applying growth factors with neurotrophic roles is beneficial for accelerating peripheral nerve regeneration. Here we show that after rat sciatic nerve injury, growth factor amphiregulin (AREG) is upregulated in Schwann cells of sciatic nerves. Elevated AREG stimulates the proliferation and migration of Schwann cells by activating ERK1/2 cascade. Schwann cell-secreted AREG further facilitates the outgrowth of neurites and the elongation of injured axons. Administration of AREG to injured sciatic nerves stimulates the proliferation of Schwann cells to replace lost cell population, encourages the migration of Schwann cells to form cell cords, and facilitates the regrowth of axons. Overall, our results identify AREG as an important neurotrophic factor and thus provide a promising therapeutic avenue towards peripheral nerve injury.

Autocrine amphiregulin signaling sustains castration-resistant Ly6d+ prostate cancer cells

Mechanisms underlying the development of castration-resistant prostate cancer (CRPC) remain incompletely understood. A recent study by Steiner et al. shows that Ly6d⁺ prostate tumor cells survive androgen deprivation through an autocrine amphiregulin signaling pathway.

Role of MR1-driven signals and amphiregulin on the recruitment and repair function of MAIT cells during skin wound healing

Tissue repair processes maintain proper organ function following mechanical or infection-related damage. In addition to antibacterial properties, mucosal associated invariant T (MAIT) cells express a tissue repair transcriptomic program and promote skin wound healing when expanded. Herein, we use a human-like mouse model of full-thickness skin excision to assess the underlying mechanisms of MAIT cell tissue repair function. Single-cell RNA sequencing analysis suggested that skin MAIT cells already express a repair program at steady state. Following skin excision, MAIT cells promoted keratinocyte proliferation, thereby accelerating healing. Using skin grafts, parabiosis, and adoptive transfer experiments, we show that MAIT cells migrated into the wound in a T cell receptor (TCR)-independent but CXCR6 chemokine receptor-dependent manner. Amphiregulin secreted by MAIT cells following excision promoted wound healing. Expression of the repair function was probably independent of sustained TCR stimulation. Overall, our study provides mechanistic insights into MAIT cell wound healing function in the skin.

Quercetin inhibits the amphiregulin/EGFR signaling-mediated renal tubular epithelial-mesenchymal transition and renal fibrosis in obstructive nephropathy

Quercetin is a widely distributed, bioactive flavonoid compound, which displays potential to inhibit fibrosis in several diseases. The purpose of our study was to determine the effect of quercetin treatment on renal fibrosis and investigate the mechanism. Human proximal tubular epithelial cells (HK-2) stimulated by transforming growth factor-β1 (TGF-β1) and a rat model of unilateral ureter obstruction (UUO) that contributes to fibrosis were used to investigate the role and molecular mechanism of quercetin. PD153035 (N-[3-Bromophenyl]-6,7-dimethoxyquinazolin-4-amine) was used to inactivate EGFR (epidermal growth factor receptor). The level of fibrosis, proliferation, apoptosis, and oxidative stress in HK-2 were measured. All data are presented as means ± standard deviation (SD). p-value < .05 was considered statistically significant. In UUO rats, quercetin reduced the area of fibrosis as well as inflammation, oxidative stress, and cell apoptosis. In cultured HK-2 cells, quercetin significantly ameliorated the EMT induced by TGF-β1, which was accompanied by increased amphiregulin (AREG) expression. Moreover, quercetin inhibited AREG binding to the EGFR receptor, thereby further affecting other downstream pathways. Quercetin may alleviate fibrosis in vitro and in vivo by inhibiting the activation of AREG/EGFR signaling indicating a potential therapeutic effect of quercetin in renal fibrosis.

Amphiregulin mediates non-cell-autonomous effect of senescence on reprogramming

Cellular senescence is an irreversible growth arrest with a dynamic secretome, termed the senescence-associated secretory phenotype (SASP). Senescence is a cell-intrinsic barrier for reprogramming, whereas the SASP facilitates cell fate conversion in non-senescent cells. However, the mechanisms by which reprogramming-induced senescence regulates cell plasticity are not well understood. Here, we investigate how the heterogeneity of paracrine senescence impacts reprogramming. We show that senescence promotes in vitro reprogramming in a stress-dependent manner. Unbiased proteomics identifies a catalog of SASP factors involved in the cell fate conversion. Amphiregulin (AREG), frequently secreted by senescent cells, promotes in vitro reprogramming by accelerating proliferation and the mesenchymal-epithelial transition via EGFR signaling. AREG treatment diminishes the negative effect of donor age on reprogramming. Finally, AREG enhances in vivo reprogramming in skeletal muscle. Hence, various SASP factors can facilitate cellular plasticity to promote reprogramming and tissue repair.

Increased amphiregulin expression by CD4+ T cells from individuals with asymptomatic Leishmania donovani infection

Objectives

There is an urgent need to be able to identify individuals with asymptomatic Leishmania donovani infection, so their risk of progressing to VL and transmitting parasites can be managed. This study examined transcriptional markers expressed by CD4⁺ T cells that could distinguish asymptomatic individuals from endemic controls and visceral leishmaniasis (VL) patients.

Methods

CD4⁺ T cells were isolated from individuals with asymptomatic L. donovani infection, endemic controls and VL patients. RNA was extracted and RNAseq employed to identify differentially expressed genes. The expression of one gene and its protein product during asymptomatic infection were evaluated.

Results

Amphiregulin (AREG) was identified as a distinguishing gene product in CD4⁺ T cells from individuals with asymptomatic L. donovani infection, compared to VL patients and healthy endemic control individuals. AREG levels in plasma and antigen-stimulated whole-blood assay cell culture supernatants were significantly elevated in asymptomatic individuals, compared to endemic controls and VL patients. Regulatory T (Treg) cells were identified as an important source of AREG amongst CD4⁺ T-cell subsets in asymptomatic individuals.

Conclusion

Increased Treg cell AREG expression was identified in individuals with asymptomatic L. donovani infection, suggesting the presence of an ongoing inflammatory response in these individuals required for controlling infection and that AREG may play an important role in preventing inflammation-induced tissue damage and subsequent disease in asymptomatic individuals.

Tissue remodeling by an opportunistic pathogen triggers allergic inflammation

Different effector arms of the immune system are optimized to protect from different classes of pathogens. In some cases, pathogens manipulate the host immune system to promote the wrong type of effector response-a phenomenon known as immune deviation. Typically, immune deviation helps pathogens to avoid destructive immune responses. Here, we report on a type of immune deviation whereby an opportunistic pathogen, Pseudomonas aeruginosa (P. aeruginosa), induces the type 2 immune response resulting in mucin production that is used as an energy source by the pathogen. Specifically, P. aeruginosa-secreted toxin, LasB, processed and activated epithelial amphiregulin to induce type 2 inflammation and mucin production. This "niche remodeling" by P. aeruginosa promoted colonization and, as a by-product, allergic sensitization. Our study thus reveals a type of bacterial immune deviation by increasing nutrient supply. It also uncovers a mechanism of allergic sensitization by a bacterial virulence factor.

Macrophage-intrinsic DUOX1 contributes to type 2 inflammation and mucus metaplasia during allergic airway disease

The NADPH oxidase DUOX1 contributes to epithelial production of alarmins, including interleukin (IL)-33, in response to injurious triggers such as airborne protease allergens, and mediates development of mucus metaplasia and airway remodeling in chronic allergic airways diseases. DUOX1 is also expressed in non-epithelial lung cell types, including macrophages that play an important role in airway remodeling during chronic lung disease. We therefore conditionally deleted DUOX1 in either lung epithelial or monocyte/macrophage lineages to address its cell-specific actions in innate airway responses to acute airway challenge with house dust mite (HDM) allergen, and in chronic HDM-driven allergic airway inflammation. As expected, acute responses to airway challenge with HDM, as well as type 2 inflammation and related features of airway remodeling during chronic HDM-induced allergic inflammation, were largely driven by DUOX1 with the respiratory epithelium. However, in the context of chronic HDM-driven inflammation, DUOX1 deletion in macrophages also significantly impaired type 2 cytokine production and indices of mucus metaplasia. Further studies revealed a contribution of macrophage-intrinsic DUOX1 in macrophage recruitment upon chronic HDM challenge, as well as features of macrophage activation that impact on type 2 inflammation and remodeling.

EGFR Signaling in Lung Fibrosis

In this review article, we will first provide a brief overview of the ErbB receptor-ligand system and its importance in developmental and physiological processes. We will then review the literature regarding the role of ErbB receptors and their ligands in the maladaptive remodeling of lung tissue, with special emphasis on idiopathic pulmonary fibrosis (IPF). Here we will focus on the pathways and cellular processes contributing to epithelial-mesenchymal miscommunication seen in this pathology. We will also provide an overview of the in vivo studies addressing the efficacy of different ErbB signaling inhibitors in experimental models of lung injury and highlight how such studies may contribute to our understanding of ErbB biology in the lung. Finally, we will discuss what we learned from clinical applications of the ErbB1 signaling inhibitors in cancer in order to advance clinical trials in IPF.

Innate lymphoid cells and COVID-19 severity in SARS-CoV-2 infection

Background

Risk of severe COVID-19 increases with age, is greater in males, and is associated with lymphopenia, but not with higher burden of SARS-CoV-2. It is unknown whether effects of age and sex on abundance of specific lymphoid subsets explain these correlations.

Methods

Multiple regression was used to determine the relationship between abundance of specific blood lymphoid cell types, age, sex, requirement for hospitalization, duration of hospitalization, and elevation of blood markers of systemic inflammation, in adults hospitalized for severe COVID-19 (n = 40), treated for COVID-19 as outpatients (n = 51), and in uninfected controls (n = 86), as well as in children with COVID-19 (n = 19), recovering from COVID-19 (n = 14), MIS-C (n = 11), recovering from MIS-C (n = 7), and pediatric controls (n = 17).

Results

This observational study found that the abundance of innate lymphoid cells (ILCs) decreases more than 7-fold over the human lifespan - T cell subsets decrease less than 2-fold - and is lower in males than in females. After accounting for effects of age and sex, ILCs, but not T cells, were lower in adults hospitalized with COVID-19, independent of lymphopenia. Among SARS-CoV-2-infected adults, the abundance of ILCs, but not of T cells, correlated inversely with odds and duration of hospitalization, and with severity of inflammation. ILCs were also uniquely decreased in pediatric COVID-19 and the numbers of these cells did not recover during follow-up. In contrast, children with MIS-C had depletion of both ILCs and T cells, and both cell types increased during follow-up. In both pediatric COVID-19 and MIS-C, ILC abundance correlated inversely with inflammation. Blood ILC mRNA and phenotype tracked closely with ILCs from lung. Importantly, blood ILCs produced amphiregulin, a protein implicated in disease tolerance and tissue homeostasis. Among controls, the percentage of ILCs that produced amphiregulin was higher in females than in males, and people hospitalized with COVID-19 had a lower percentage of ILCs that produced amphiregulin than did controls.

Conclusions

These results suggest that, by promoting disease tolerance, homeostatic ILCs decrease morbidity and mortality associated with SARS-CoV-2 infection, and that lower ILC abundance contributes to increased COVID-19 severity with age and in males.

Funding

This work was supported in part by the Massachusetts Consortium for Pathogen Readiness and NIH grants R37AI147868, R01AI148784, F30HD100110, 5K08HL143183.

Anti-tumor efficacy of an MMAE-conjugated antibody targeting cell surface TACE/ADAM17-cleaved Amphiregulin in breast cancer

Background

The Epidermal Growth Factor Receptor (EGFR) ligand, Amphiregulin (AREG), is a key proliferative effector of estrogen receptor signaling in breast cancer and also plays a role in other malignancies. AREG is a single-pass transmembrane protein proteolytically processed by TACE/ADAM17 to release the soluble EGFR ligand, leaving a residual transmembrane stalk that is subsequently internalized.

Methods

Using phage display, we identified antibodies that selectively recognize the residual transmembrane stalk of cleaved AREG. Conjugation with fluorescence labels and monomethyl auristatin E (MMAE) was used to study their intracellular trafficking and anti-cancer effects, respectively.

Results

We report the development of an antibody-drug conjugate (ADC), GMF-1A3-MMAE, targeting an AREG neo-epitope revealed following ADAM17-mediated cleavage. The antibody does not interact with uncleaved AREG, providing a novel means of targeting cells with high rates of AREG shedding. Using fluorescent dye conjugation, we demonstrated that the antibody is internalized by cancer cells in a manner dependent on the presence of cell surface cleaved AREG. Antibodies conjugated with MMAE were cytotoxic in vitro and induced rapid regression of established breast tumor xenografts in immunocompromised mice. We further demonstrate that these antibodies recognize the AREG neo-epitope in formalin-fixed, paraffin-embedded tumor tissue, suggesting their utility as a companion diagnostic for patient selection.

Conclusions

This ADC targeting AREG has potential utility in the treatment of breast and other tumors in which proteolytic AREG shedding is a frequent event.

Propofol induces apoptosis and ameliorates 5‑fluorouracil resistance in OSCC cells by reducing the expression and secretion of amphiregulin

Among the different types of oral cancer, >90% of cases are oral squamous cell carcinoma (OSCC). 5-fluorouracil (5-FU) is a commonly used treatment for OSCC, but cells typically display resistance to the drug. Propofol, an intravenous anesthetic agent, exhibits certain anticancer effects, including the inhibition of cancer cell proliferation, migration and invasion. Secreted proteins, such as growth factors and cytokines are involved in cancer development and progression, but the effect of propofol on secreted proteins in OSCC is not completely understood. An MTT assay, flow cytometry and western blotting were performed to determine the anticancer effects of propofol. The secretion profile of OSCC was determined using an antibody array, and clinical importance was assessed using the Gene Expression Profiling Interactive Analysis database. The results were verified by performing reverse transcription-quantitative PCR (RT-qPCR) and western blotting. 5-FU-resistant cells were established to determine the role of the gene of interest in drug resistance. The results demonstrated that propofol decreased cell viability and promoted cell apoptosis. The antibody array results showed that propofol attenuated the secretion of multiple growth factors. The bioinformatics results indicated that amphiregulin (AREG) was expressed at significantly higher levels in cancer tissues, which was also related to poor prognosis. The results of RT-qPCR and western blotting revealed that propofol decreased AREG expression. Pretreatment with exogenous recombinant AREG increased EGFR activation and conferred propofol resistance. Moreover, the results indicated that the expression and activation of AREG was also related to 5-FU resistance, but propofol ameliorated 5-FU drug resistance. Therefore, the present study suggested that propofol combination therapy may serve as an effective treatment strategy for OSCC.

Positive effects of amphiregulin on human oocyte maturation and its molecular drivers in patients with polycystic ovary syndrome

STUDY QUESTION

Does use of medium containing amphiregulin improve meiotic maturation efficiency in oocytes of women with polycystic ovary syndrome (PCOS) undergoing in vitro maturation (IVM) preceded by a capacitation culture step capacitation IVM (CAPA-IVM)?

SUMMARY ANSWER

Use of medium containing amphiregulin significantly increased the maturation rate from oocytes retrieved from follicles with diameters <6 or ≥6 mm pre-cultured in capacitation medium.

WHAT IS KNOWN ALREADY

Amphiregulin concentration in follicular fluid is correlated with human oocyte developmental competence. Amphiregulin added to the meiotic trigger has been shown to improve outcomes of IVM in a range of mammalian species.

STUDY DESIGN, SIZE, DURATION

This prospective, randomized cohort study included 30 patients and was conducted at an academic infertility centre in Vietnam from April to December 2019. Patients with PCOS were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the first stage, sibling oocytes from each patient (671 in total) were allocated in equal numbers to maturation in medium with (CAPA-AREG) or without (CAPA-Control) amphiregulin 100 ng/ml. After a maturation check and fertilization using intracytoplasmic sperm injection (ICSI), all good quality Day 3 embryos were vitrified. Cumulus cells (CCs) from both groups were collected at the moment of ICSI denudation and underwent a molecular analysis to quantify key transcripts of oocyte maturation and to relate these to early embryo development. On return for frozen embryo transfer (second stage), patients were randomized to have either CAPA-AREG or CAPA-Control embryo(s) implanted. Where no embryo(s) from the randomized group were available, embryo(s) from the other group were transferred. The primary endpoint of the study was meiotic maturation efficiency (proportion of metaphase II [MII] oocytes; maturation rate).

MAIN RESULTS AND THE ROLE OF CHANCE

In the per-patient analysis, the number of MII oocytes was significantly higher in the CAPA-AREG group versus the CAPA-Control group (median [interquartile range] 7.0 [5.3, 8.0] versus 6.0 [4.0, 7.0]; P = 0.01). When each oocyte was evaluated, the maturation rate was also significantly higher in the CAPA-AREG group versus the CAPA-Control group (67.6% versus 55.2%; relative risk [RR] 1.22 [95% confidence interval (CI) 1.08-1.38]; P = 0.001). No other IVM or embryology outcomes differed significantly between the two groups. Rates of clinical pregnancy (66.7% versus 42.9%; RR 1.56 [95% CI 0.77-3.14]), ongoing pregnancy (53.3% versus 28.6%; RR 1.87 [95% CI 0.72-4.85]) and live birth (46.7% versus 28.6%; RR 1.63 [95% CI 0.61-4.39]) were numerically higher in the patients who had CAPA-AREG versus CAPA-Control embryos implanted, but each fertility and obstetric outcome did not differ significantly between the groups. In the CAPA-AREG group, there were significant shifts in CC expression of genes involved in steroidogenesis (STAR, 3BHSD), the ovulatory cascade (DUSP16, EGFR, HAS2, PTGR2, PTGS2, RPS6KA2), redox and glucose metabolism (CAT, GPX1, SOD2, SLC2A1, LDHA) and transcription (NRF2). The expression of three genes (TRPM7, VCAN and JUN) in CCs showed a significant correlation with embryo quality.

LIMITATIONS, REASONS FOR CAUTION

This study included only Vietnamese women with PCOS, limiting the generalizability. Although 100 ng/ml amphiregulin addition to the maturation culture step significantly improved the MII rate, the sample size in this study was small, meaning that these findings should be considered as exploratory. Therefore, a larger patient cohort is needed to confirm whether the positive effects of amphiregulin translate into improved fertility outcomes in patients undergoing IVM.

WIDER IMPLICATIONS OF THE FINDINGS

Data from this study confirm the beneficial effects of amphiregulin during IVM with respect to the trigger of oocyte maturation. The gene expression findings in cumulus indicate that multiple pathways might contribute to these beneficial effects and confirm the key role of the epidermal growth factor system in the stepwise acquisition of human oocyte competence.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED; grant number FWO.106-YS.2017.02) and by the Fund for Research Flanders (FWO; grant number G.OD97.18N). L.N.V. has received speaker and conference fees from Merck, grants, speaker and conference fees from Merck Sharpe and Dohme, and speaker, conference and scientific board fees from Ferring. T.M.H. has received speaker fees from Merck, Merck Sharp and Dohme and Ferring. J.S. reports speaker fees from Ferring Pharmaceuticals and Biomérieux Diagnostics and grants from FWO Flanders, is co-inventor on granted patents on CAPA-IVM methodologies in USA (US10392601B2), Europe (EP3234112B1) and Japan (JP 6806683 registered 08-12-2020) and is a co-shareholder of Lavima Fertility Inc., a spin-off company of the Vrije Universiteit Brussel (VUB, Brussels, Belgium). NA, TDP, AHL, MNHN, SR, FS, EA and UDTH report no financial relationships with any organizations that might have an interest in the submitted work in the previous three years, and no other relationships or activities that could appear to have influenced the submitted work.

TRIAL REGISTRATION NUMBER

NCT03915054.

Amphiregulin in cellular physiology, health, and disease: Potential use as a biomarker and therapeutic target

Amphiregulin (AREG), which acts as one of the ligands for epidermal receptor growth factor receptor (EGFR), plays a crucial role in tissue repair, inflammation, and immunity. AREG is synthesized as membrane-anchored pre-protein, and is excreted after proteolytic cleavage, and serves as an autocrine or paracrine factor. After engagement with the EGFR, AREG triggers a cascade of signaling events required for many cellular physiological processes including metabolism, cell cycle, and proliferation. Under different inflammatory and pathogenic conditions, AREG is expressed by various activated immune cells that orchestrate both tolerance and host resistance mechanisms. Several factors including xenobiotics, cytokines, and inflammatory lipids have been shown to trigger AREG gene expression and release. In this review, we discuss the structure, function, and regulation of AREG, its role in tissue repair, inflammation, and homeostasis as well as the potential of AREG as a biomarker and therapeutic target.

Four-Week Repeated Intravenous Dose Toxicity of Self-Assembled-Micelle Inhibitory RNA-Targeting Amphiregulin in Mice

The present study investigated the potential subchronic toxicity of self-assembled-micelle inhibitory RNA-targeting amphiregulin (SAMiRNA-AREG) in mice. The test reagent was administered once-daily by intravenous injection for 4 weeks at 0, 100, 200, or 300 mg/kg/day doses. Additional recovery groups (vehicle control and high dose groups) were observed for a 2-week recovery period. During the test period, mortality, clinical signs, body weight, food consumption, ophthalmology, urinalysis, hematology, serum biochemistry, gross pathology, organ weight, and histopathology were examined. An increase in the percentages of basophil and large unstained cells was observed in the 200 and 300 mg/kg/day groups of both sexes. In addition, the absolute and relative weights of the spleen were higher in males given 300 mg/kg/day relative to the concurrent controls. However, these findings were considered of no toxicological significance because the changes were minimal, were not accompanied by other relevant results (eg, correlating microscopic changes), and were not observed at the end of the 2-week recovery period indicating recovery of the findings. Based on the results, SAMiRNA-AREG did not cause treatment-related adverse effects at dose levels of up to 300 mg/kg/day in mice after 4-week repeated intravenous doses. Under these conditions, the no-observed-adverse-effect level of the SAMiRNA-AREG was ≥300 mg/kg/day in both sexes and no target organs were identified.

Mechanisms for Alternaria alternata Function in the Skin During Induction of Peanut Allergy in Neonatal Mice With Skin Barrier Mutations

Neonatal mice with heterozygous mutations in genes encoding the skin barrier proteins filaggrin and mattrin (flaky tail mice [FT^+/-]) exhibit oral peanut-induced anaphylaxis after skin sensitization. As we have previously reported, sensitization in this model is achieved via skin co- exposure to the environmental allergen Alternaria alternata (Alt), peanut extract (PNE), and detergent. However, the function of Alt in initiation of peanut allergy in this model is little understood. The purpose of this study was to investigate candidate cytokines induced by Alt in the skin and determine the role of these cytokines in the development of food allergy, namely oncostatin M (Osm), amphiregulin (Areg), and IL-33. RT-qPCR analyses demonstrated that skin of FT^+/- neonates expressed Il33 and Osm following Alt or Alt/PNE but not PNE exposure. By contrast, expression of Areg was induced by either Alt, PNE, or Alt/PNE sensitization in FT^+/- neonates. In scRNAseq analyses, Osm, Areg, and Il33 were expressed by several cell types, including a keratinocyte cluster that was expanded in the skin of Alt/PNE-exposed FT^+/- pups as compared to Alt/PNE-exposed WT pups. Areg and OSM were required for oral PNE-induced anaphylaxis since anaphylaxis was inhibited by administration of neutralizing anti-Areg or anti-OSM antibodies prior to each skin sensitization with Alt/PNE. It was then determined if intradermal injection of recombinant IL33 (rIL33), rAreg, or rOSM in the skin could substitute for Alt during skin sensitization to PNE. PNE skin sensitization with intradermal rIL33 was sufficient for oral PNE-induced anaphylaxis, whereas skin sensitization with intradermal rAreg or rOSM during skin exposure to PNE was not sufficient for anaphylaxis to oral PNE challenge. Based on these studies a pathway for IL33, Areg and OSM in Alt/PNE sensitized FT^+/- skin was defined for IgE induction and anaphylaxis. Alt stimulated two pathways, an IL33 pathway and a pathway involving OSM and Areg. These two pathways acted in concert with PNE to induce food allergy in pups with skin barrier mutations.

Serum Amphiregulin and Heparin-Binding Epidermal Growth Factor as Biomarkers in Patients with Idiopathic Inflammatory Myopathy

Background. The epidermal growth factors amphiregulin (AREG) and heparin-binding epidermal growth factor (HB-EGF) are implicated in the pathogenesis of several autoimmune diseases, but their clinical and pathological roles in idiopathic inflammatory myopathy (IIM) are unclear. Methods. Serum AREG and HB-EGF levels were measured by ELISA in patients with IIM (n = 37), systemic sclerosis (n = 17), and rheumatoid arthritis (n = 10), and for seven age- and sex-matched healthy controls (HCs). Associations between serum AREG or HB-EGF levels and the clinical parameters were analyzed. Results. Serum AREG levels in IIM patients were significantly elevated compared to those in HCs (median, 20.7 and 10.7 pg/mL, respectively; p = 0.025). In particular, serum AREG levels in IIM patients with interstitial lung disease (ILD) were higher than those of HCs (22.4 pg/mL, p = 0.027). The disease duration in patients with elevated serum AREG levels was significantly shorter compared to those who had normal serum AREG levels (7 and 21 months, respectively; p = 0.0012). Serum HB-EGF levels were significantly increased in IIM patients with elevated CK levels (136.2 pg/mL; p = 0.020) and patients with anti-Mi-2 antibody (183.7 pg/mL; p = 0.045) compared to those in HCs (74.9 pg/mL). Conclusion. These results suggested that AREG could be a promising biomarker associated with early-phase IIM-related ILD, and that HB-EGF expression was associated with muscle injury and regeneration in IIM.

Amphiregulin promotes hair regeneration of skin-derived precursors via the PI3K and MAPK pathways

Objectives

There are significant clinical challenges associated with alopecia treatment, including poor efficiency of related drugs and insufficient hair follicles (HFs) for transplantation. Skin‐derived precursors (SKPs) exhibit great potential as stem cell‐based therapies for hair regeneration; however, the proliferation and hair‐inducing capacity of SKPs gradually decrease during culturing.

Materials and Methods

We describe a 3D co‐culture system accompanied by kyoto encyclopaedia of genes and genomes and gene ontology enrichment analyses to determine the key factors and pathways that enhance SKP stemness and verified using alkaline phosphatase assays, Ki‐67 staining, HF reconstitution, Western blot and immunofluorescence staining. The upregulated genes were confirmed utilizing corresponding recombinant protein or small‐interfering RNA silencing in vitro, as well as the evaluation of telogen‐to‐anagen transition and HF reconstitution in vivo.

Results

The 3D co‐culture system revealed that epidermal stem cells and adipose‐derived stem cells enhanced SKP proliferation and HF regeneration capacity by amphiregulin (AREG), with the promoted stemness allowing SKPs to gain an earlier telogen‐to‐anagen transition and high‐efficiency HF reconstitution. By contrast, inhibitors of the phosphoinositide 3‐kinase (PI3K) and mitogen‐activated protein kinase (MAPK) pathways downstream of AREG signalling resulted in diametrically opposite activities.

Conclusions

By exploiting a 3D co‐culture model, we determined that AREG promoted SKP stemness by enhancing both proliferation and hair‐inducing capacity through the PI3K and MAPK pathways. These findings suggest AREG therapy as a potentially promising approach for treating alopecia.

Innate lymphoid cells and disease tolerance in SARS-CoV-2 infection

Risk of severe COVID-19 increases with age, is greater in males, and is associated with lymphopenia, but not with higher burden of SARS-CoV-2. It is unknown whether effects of age and sex on abundance of specific lymphoid subsets explain these correlations. This study found that the abundance of innate lymphoid cells (ILCs) decreases more than 7-fold over the human lifespan — T cell subsets decrease less than 2-fold — and is lower in males than in females. After accounting for effects of age and sex, ILCs, but not T cells, were lower in adults hospitalized with COVID-19, independent of lymphopenia. Among SARS-CoV-2-infected adults, the abundance of ILCs, but not of T cells, correlated inversely with odds and duration of hospitalization, and with severity of inflammation. ILCs were also uniquely decreased in pediatric COVID-19 and the numbers of these cells did not recover during follow-up. In contrast, children with MIS-C had depletion of both ILCs and T cells, and both cell types increased during follow-up. In both pediatric COVID-19 and MIS-C, ILC abundance correlated inversely with inflammation. Blood ILC mRNA and phenotype tracked closely with ILCs from lung. Importantly, blood ILCs produced amphiregulin, a protein implicated in disease tolerance and tissue homeostasis, and the percentage of amphiregulin-producing ILCs was higher in females than in males. These results suggest that, by promoting disease tolerance, homeostatic ILCs decrease morbidity and mortality associated with SARS-CoV-2 infection, and that lower ILC abundance accounts for increased COVID-19 severity with age and in males.

Notch4 signaling limits regulatory T-cell-mediated tissue repair and promotes severe lung inflammation in viral infections

A cardinal feature of COVID-19 is lung inflammation and respiratory failure. In a prospective multi-country cohort of COVID-19 patients, we found that increased Notch4 expression on circulating regulatory T (Treg) cells was associated with disease severity, predicted mortality, and declined upon recovery. Deletion of Notch4 in Treg cells or therapy with anti-Notch4 antibodies in conventional and humanized mice normalized the dysregulated innate immunity and rescued disease morbidity and mortality induced by a synthetic analog of viral RNA or by influenza H1N1 virus. Mechanistically, Notch4 suppressed the induction by interleukin-18 of amphiregulin, a cytokine necessary for tissue repair. Protection by Notch4 inhibition was recapitulated by therapy with Amphiregulin and, reciprocally, abrogated by its antagonism. Amphiregulin declined in COVID-19 subjects as a function of disease severity and Notch4 expression. Thus, Notch4 expression on Treg cells dynamically restrains amphiregulin-dependent tissue repair to promote severe lung inflammation, with therapeutic implications for COVID-19 and related infections.

The GABAA Receptor Influences Pressure Overload-Induced Heart Failure by Modulating Macrophages in Mice

Background

Myocardial macrophages have key roles in cardiac remodeling and dysfunction. The gamma-aminobutyric acid subtype A (GABAA) receptor was recently found to be distributed in macrophages, allowing regulation of inflammatory responses to various diseases. This study aimed to clarify the role of GABAA receptor-mediated macrophage responses in pressure overload-induced heart failure.

Methods and Results

C57BL/6J mice underwent transverse aortic constriction for pressure-overload hypertrophy (POH) and were intraperitoneally treated with a specific GABAA receptor agonist (topiramate) or antagonist (bicuculline). Echocardiography, histology, and flow cytometry were performed to evaluate the causes and effects of myocardial hypertrophy and fibrosis. Activation of the GABAA receptor by topiramate reduced ejection fraction and fractional shortening, enlarged the end-diastolic and end-systolic left ventricular internal diameter, aggravated myocardial hypertrophy and fibrosis, and accelerated heart failure in response to pressure overload. Mechanistically, topiramate increased the number of Ly6Clow macrophages in the heart during POH and circulating Ly6Chigh classic monocyte infiltration in late-phase POH. Further, topiramate drove Ly6Clow macrophages toward MHCIIhigh macrophage polarization. As a result, Ly6Clow macrophages activated the amphiregulin-induced AKT/mTOR signaling pathway, and Ly6ClowMHCIIhigh macrophage polarization increased expression levels of osteopontin and TGF-β, which led to myocardial hypertrophy and fibrosis. Conversely, GABAA receptor blockage with bicuculline reversed these effects.

Conclusions

Control of the GABAA receptor activity in monocytes/macrophages plays an important role in myocardial hypertrophy and fibrosis after POH. Blockade of the GABAA receptor has the potential to improve pressure overload-induced heart failure.

Genotoxicity evaluation of self-assembled-micelle inhibitory RNA-targeting amphiregulin (SAMiRNA-AREG), a novel siRNA nanoparticle for the treatment of fibrotic disease

The self-assembled-micelle inhibitory RNA-targeting amphiregulin (SAMiRNA-AREG) is a novel small-interfering RNA (siRNA) nanoparticle that is used for treatment of pulmonary fibrosis. We investigated the potential genotoxicity of SAMiRNA-AREG based on the guidelines published by the Organization for Economic Cooperation and Development. In the bacterial reverse mutation assay (Ames test), SAMiRNA-AREG did not induce mutations in Salmonella typhimurium TA100, TA1535, TA98, and TA1537 and Escherichia coli WP2uvrA at concentrations of up to 3000 μg/plate with or without metabolic activation. The SAMiRNA-AREG (concentrations up to 500 μg/mL) did not induce chromosomal aberrations in cultured Chinese hamster lung cells with or without metabolic activation. In the in vivo mouse bone marrow micronucleus assay, the SAMiRNA-AREG (concentrations up to 300 mg/kg body weight) did not affect the proportions of polychromatic erythrocytes and total erythrocytes, nor did it increase the number of micronucleated polychromatic erythrocytes in ICR mice. Collectively, these results suggest that SAMiRNA-AREG is safe with regard to genotoxicity such as mutagenesis or clastogenesis under the present experimental conditions. These results might support the safety of SAMiRNA-AREG as a potential therapeutic agent for pharmaceutical development.

Estrogens in Hepatocellular Carcinoma: Friends or Foes?

Simple Summary

Today, we know that estrogen hormones are required for the development and function of many organs, such as the liver, in both males and females. However, in some circumstances, estrogen excess may be implicated in the appearance of various chronic diseases, including cancer. This review will inspect the results of several studies to better understand the mechanisms responsible for estrogens to change from protective into harmful hormones in human liver.

Abstract

Estrogens are recognized as key players in physiological regulation of various, classical and non-classical, target organs, and tissues, including liver development, homeostasis, and function. On the other hand, multiple, though dispersed, experimental evidence is highly suggestive for the implication of estrogen in development and progression of hepatocellular carcinoma. In this paper, data from our own studies and the current literature are reviewed to help understanding this apparent discrepancy.

Butyrate modulates adipose-derived stem cells isolated from polygenic obese and diabetic mice to drive enhanced immunosuppression

BACKGROUND AIMS

Adipose-derived stem cells (ASCs) offer promising therapeutic possibilities for immunomodulation. Butyrate (BA) exerts potent anti-inflammatory effects and exhibits multiple regulatory functionalities in adipose tissue (AT). The authors aimed to explore whether BA modulates ASCs to augment their immunosuppressive capabilities.

METHODS

The authors examined the potency of BA and ASCs for controlling anti-CD3 plus CD28-stimulated splenocyte proliferation in vitro, both in combination and with pre-treatment. Further, the authors investigated genes specifically upregulated by BA-treated ASCs, which were harvested from ASC-splenocyte co-culture after the removal of floating splenocytes. In addition, the authors investigated the influence of oral BA supplementation on the ex vivo immunosuppressive potency of ASCs from BALB/c and Tsumura, Suzuki, obese, diabetes (TSOD) mice.

RESULTS

BA enhanced the immunosuppressive potency of ASCs when directly added to ASC-splenocyte co-cultures or via pre-conditioning treatment. The percentages of ASC-induced Foxp3⁺ regulatory T cells increased, whereas the numbers of ASC-suppressed T helper 17 cells further decreased after BA exposure. The messenger RNA expression levels of inducible nitric oxide (NO) synthase (iNOS), chemokines, IL-10 and amphiregulin in ASCs co-cultured with activated splenocytes were upregulated after incubation with BA. This was accompanied by an amplification of iNOS-inducing cytokines, interferon gamma and tumor necrosis factor alpha in the ASC-splenocyte co-culture, triggering ASCs to produce high NO levels under the influence of BA. Mechanistically, the authors detected BA-mediated acetylated histone H3 in ASCs. BA treatment consistently improved the immunosuppressive potency of ASCs derived from both BALB/c and TSOD mice.

CONCLUSIONS

The use of BA to counteract metaflammation by restoring the defective immunomodulation of ASCs from dysregulated AT in obese donors is recommended.

Mesenchymal Stem and Stromal Cells Harness Macrophage-Derived Amphiregulin to Maintain Tissue Homeostasis

The cross-talk between mesenchymal stem and stromal cells (MSCs) and macrophages is critical for the restoration of tissue homeostasis after injury. Here, we demonstrate a pathway through which MSCs instruct macrophages to resolve inflammation and preserve tissue-specific stem cells, leading to homeostasis in mice with autoimmune uveoretinitis and sterile-injury-induced corneal epithelial stem cell deficiency. Distinct from their conventional role in macrophage reprogramming to anti-inflammatory phenotype by a PGE2-dependent mechanism, MSCs enhance the phagocytic activity of macrophages, which partly depends on the uptake of MSC mitochondria-containing extracellular vesicles. The MSC-primed macrophages increase the secretion of amphiregulin (AREG) in a phagocytosis-dependent manner. AREG is essential for MSC-primed macrophages to suppress immune responses through regulatory T (Treg) cells and to protect corneal epithelial stem cells via apoptosis inhibition and proliferation promotion. Hence, the data reveal that MSCs harness macrophage-derived AREG to maintain tissue homeostasis after injury and provide a therapeutic target in immune-mediated disease and regenerative medicine.

Amphiregulin Regulates Melanocytic Senescence

Oncogene-induced senescence (OIS) is a decisive process to suppress tumor development, but the molecular details of OIS are still under investigation. Using an established OIS model of primary melanocytes transduced with BRAF V600E and compared to control cells, amphiregulin (AREG) was shown to be induced. In addition, AREG expression was observed in nevi, which by definition, are senescent cell clusters, compared to melanocytes. Interestingly, treatment of melanocytes with recombinant AREG did induce senescence. This led to the assumption that extracellular AREG has an important function in this process. Inhibition of the epidermal growth factor receptor (EGFR) using Gefitinib identified AREG as one of EGFR ligands responsible for senescence. Furthermore, depletion of AREG expression in senescent BRAF V600E melanocytes resulted in a significant reduction of senescent melanocytes. This study reveals AREG as an essential molecular component of signaling pathways leading to senescence in melanocytes.

Expression of Amphiregulin in Enchondromas and Central Chondrosarcomas

OBJECTIVES

The aim of this study was to evaluate the role of amphiregulin protein, an epidermal growth factor receptor ligand, in cartilaginous tumors.

METHODS

Amphiregulin expression was examined in 31 enchondromas and 67 chondrosarcomas using immunohistochemistry analysis.

RESULTS

Overall, 15 enchondromas (48.40%) and 24 chondrosarcomas (35.82%) were positive for amphiregulin. According to the receiver operating characteristic curve test, no difference in amphiregulin expression was observed between enchondromas and low-grade chondrosarcomas (p=0.0880). Additionally, 39 lesions (16 in short bones, 13 in long bones, and 10 in flat bones) were positive for amphiregulin, exhibiting a higher percentage of positive cells (p=0.0030) and intensity of immunohistochemical expression (p=0.0055) in short bone lesions than in others. Among 25 enchondromas localized in short bones, 15 expressed amphiregulin; however, all 6 cases localized in long bones were negative for this marker (p=0.0177).

CONCLUSIONS

Amphiregulin did not help in distinguishing enchondromas from low-grade chondrosarcomas. The present study is the first to document the expression of this immunohistochemical marker in enchondromas. Furthermore, amphiregulin expression in enchondromas was localized in short bones, indicating a phenotypic distinction from that in long bones. This distinction may contribute to an improved understanding of the pathogenesis of these lesions.

Whole Transcriptome Analysis of Myeloid Dendritic Cells Reveals Distinct Genetic Regulation in Patients with Allergies

Dendritic cells (DCs) play critical roles in atopic diseases, orchestrating both innate and adaptive immune systems. Nevertheless, limited information is available regarding the mechanism through which DCs induce hyperresponsiveness in patients with allergies. This study aims to reveal novel genetic alterations and future therapeutic target molecules in the DCs from patients with allergies using whole transcriptome sequencing. Transcriptome sequencing of human BDCA-3+/CD11c+ DCs sorted from peripheral blood monocytes obtained from six patients with allergies and four healthy controls was conducted. Gene expression profile data were analyzed, and an ingenuity pathway analysis was performed. A total of 1638 differentially expressed genes were identified at p-values < 0.05, with 11 genes showing a log2-fold change ≥1.5. The top gene network was associated with cell death/survival and organismal injury/abnormality. In validation experiments, amphiregulin (AREG) showed consistent results with transcriptome sequencing data, with increased mRNA expression in THP-1-derived DCs after Der p 1 stimulation and higher protein expression in myeloid DCs obtained from patients with allergies. This study suggests an alteration in the expression of DCs in patients with allergies, proposing related altered functions and intracellular mechanisms. Notably, AREG might play a crucial role in DCs by inducing the Th2 immune response.

Foxp3+ Regulatory T Cells Inhibit CCl4-Induced Liver Inflammation and Fibrosis by Regulating Tissue Cellular Immunity

Foxp3+ regulatory T (Treg) cells are pivotal in maintaining immunological self-tolerance and tissue homeostasis; however, it remains unclear how tissue Treg cells respond to liver injury and regulate chronic inflammation, which can cause liver fibrosis. We report here that hepatic Treg cells play a critical role in preventing liver pathology by suppressing inflammatory cellular immunity that can promote liver damage and fibrosis. Chronic liver inflammation induced by injections of carbon tetrachloride (CCl₄) led to preferential expansion of hepatic Treg cells that prevented liver fibrosis. In contrast, depletion of Treg cells in the CCl₄-induced liver fibrosis model exacerbated the severity of liver pathology. Treg depletion unleashed tissue cellular immunity and drove the activation and expansion of the pro-fibrotic IL-4-producing T helper 2 cells, as well as CCR2^high Ly-6C^high inflammatory monocytes/macrophages in the inflamed liver. Although Treg expression of amphiregulin plays a key role in tissue remodeling and repair in various inflammation models, amphiregulin from hepatic Treg cells, the largest producer among liver immune cells, was dispensable for maintaining liver homeostasis and preventing liver fibrosis during CCl₄-induced chronic inflammation. Our results indicate that Treg cells control chronic liver inflammation and fibrosis by regulating the aberrant activation and functions of immune effector cells. Harnessing Treg functions, which effectively regulate tissue cellular immunity, may be a therapeutic strategy for preventing and treating liver fibrosis.

Prenatal smoke exposure dysregulates lung epithelial cell differentiation in mouse offspring: role for AREG-induced EGFR signaling

Prenatal smoke exposure is a risk factor for impaired lung development in children. Recent studies have indicated that amphiregulin (AREG), which is a ligand of the epidermal growth factor receptor (EGFR), has a regulatory role in airway epithelial cell differentiation. In this study, we investigated the effect of prenatal smoke exposure on lung epithelial cell differentiation and linked this with AREG-EGFR signaling in 1-day-old mouse offspring. Bronchial and alveolar epithelial cell differentiations were assessed by immunohistochemistry. Areg, epidermal growth factor (Egf), and mRNA expressions of specific markers for bronchial and alveolar epithelial cells were assessed by RT-qPCR. The results in neonatal lungs were validated in an AREG-treated three-dimensional mouse lung organoid model. We found that prenatal smoke exposure reduced the number of ciliated cells and the expression of the cilia-related transcription factor Foxj1, whereas it resulted in higher expression of mucus-related transcription factors Spdef and Foxm1 in the lung. Moreover, prenatally smoke-exposed offspring had higher numbers of alveolar epithelial type II cells (AECII) and lower expression of the AECI-related Pdpn and Gramd2 markers. This was accompanied by higher expression of Areg and lower expression of Egf in prenatally smoke-exposed offspring. In bronchial organoids, AREG treatment resulted in fewer ciliated cells and more basal cells when compared with non-treated bronchiolar organoids. In alveolar organoids, AREG treatment led to more AECII cells than non-treated AECII cells. Taken together, the observed impaired bronchial and alveolar cell development in prenatally smoke-exposed neonatal offspring may be induced by increased AREG-EGFR signaling.

Human chorionic gonadotropin-induced amphiregulin stimulates aromatase expression in human granulosa-lutein cells: a mechanism for estradiol production in the luteal phase

STUDY QUESTION

Does amphiregulin (AREG), the most abundant and important epidermal growth factor receptor (EGFR) ligand in the follicular fluid, regulate aromatase expression in human granulosa-lutein (hGL) cells?

SUMMARY ANSWER

AREG mediates the hCG-induced up-regulation of aromatase expression and estradiol (E2) production in hGL cells.

WHAT IS KNOWN ALREADY

AREG expression and secretion are rapidly induced by hCG in hGL cells and mediate physiological functions of LH/hCG in the ovary. EGFR protein is expressed in follicles not only in the pre-ovulatory phase but also throughout the luteal phase of the menstrual cycle. After the LH surge, the human corpus luteum secretes high levels of E2, which regulates various luteal cell functions. Aromatase is an enzyme responsible for a key step in the biosynthesis of E2. However, whether AREG regulates aromatase expression and E2 production in hGL cells remains unexplored.

STUDY DESIGN, SIZE, DURATION

This study is an experimental study performed over a 1-year period. In vitro investigations examined the role of AREG in the regulation of aromatase expression and E2 production in primary hGL cells.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Primary hGL cells were obtained from women undergoing IVF treatment in an academic research center. Aromatase mRNA and protein levels were examined after exposure of hGL cells to recombinant human AREG, hCG or LH. The EGFR tyrosine kinase inhibitor AG1478, PI3K inhibitor LY294002 and siRNAs targeting EGFR, LH receptor, StAR and AREG were used to verify the specificity of the effects and to investigate the underlying molecular mechanisms. Reverse transcription quantitative real-time PCR (RT-qPCR) and western blot were used to measure the specific mRNA and protein levels, respectively. Follicular fluid and serum were collected from 65 infertile women during IVF treatment. Pearson's correlation analysis was performed to examine the correlation coefficient between two values.

MAIN RESULTS AND THE ROLE OF CHANCE

Treatment of hGL cells with AREG-stimulated aromatase expression and E2 production. Using pharmacological inhibitors and specific siRNAs, we revealed that AREG-stimulated aromatase expression and E2 production via EGFR-mediated activation of the protein kinase B (AKT) signaling pathway. In addition, inhibition of EGFR activity and AREG knockdown attenuated hCG-induced up-regulation of aromatase expression and E2 production. Importantly, the protein levels of AREG in the follicular fluid were positively correlated with the E2 levels in serum after 2 days of oocyte pick-up and in the follicular fluid of IVF patients.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The in vitro setting of this study is a limitation that may not reflect the real intra-ovarian microenvironment. Clinical data were obtained from a small sample size.

WIDER IMPLICATIONS OF THE FINDINGS

Our results provide the first evidence that hCG-induced AREG contributes to aromatase expression and E2 production in the luteal phase of the menstrual cycle. A better understanding of the hormonal regulation of female reproductive function may help to develop new strategies for the treatment of clinical infertility.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China for Young Scientists (81601253), the specific fund of clinical medical research of Chinese Medical Association (16020160632) and the Foundation from the First Affiliated Hospital of Zhengzhou University for Young Scientists to Lanlan Fang. This work was also supported by an operating grant from the National Natural Science Foundation of China (81820108016) to Ying-Pu Sun. All authors declare no conflict of interest.

Clinical and molecular characteristics and treatment outcomes of advanced right-colon, left-colon and rectal cancers: data from 1180 patients in a phase III trial of panitumumab with an extended biomarker panel

BACKGROUND

Primary tumour location (PTL) is being adopted by clinicians to guide treatment decisions in metastatic colorectal cancer (mCRC). Here we test PTL as a predictive marker for panitumumab efficacy, and examine its relationship with an extended biomarker profile. We also examine rectal tumours as a separate location.

PATIENTS AND METHODS

mCRC patients from the second-line PICCOLO trial of irinotecan versus irinotecan/panitumumab (IrPan). PTL was classified as right-PTL, left-PTL or rectal-PTL. PTL was assessed as a predictive biomarker for IrPan effect in RAS-wild-type (RAS-wt) patients (compared with irinotecan alone), then tested for independence alongside an extended biomarker profile (BRAF, epiregulin/amphiregulin (EREG/AREG) and HER3 mRNA expression).

RESULTS

PTL data were available for 1180 patients (98.5%), of whom 558 were RAS-wt. High HER3 expression was independently predictive of panitumumab overall survival improvement, but PTL and EREG/AREG were not. IrPan progression-free survival (PFS) improvement compared with irinotecan was seen in left-PTL [hazard ratio (HR) = 0.61, P = 0.002) but not right-PTL (HR = 0.98, P = 0.90) (interaction P = 0.05; RAS/BRAF-wt interaction P = 0.10), or in rectal-PTL (HR = 0.82, P = 0.20) (interaction P = 0.14 compared with left-PTL; RAS/BRAF-wt interaction P = 0.04). Patients with right-PTL and high EREG/AREG or HER3 expression, had IrPan PFS improvement (high EREG/AREG HR = 0.20, P = 0.04; high HER3 HR = 0.33, P = 0.10) compared with irinotecan. Similar effect was seen for rectal-PTL patients (high EREG/AREG HR = 0.44, P = 0.03; high HER3 HR = 0.34, P = 0.05).

CONCLUSIONS

RAS-wt patients with left-PTL are more likely to have panitumumab PFS advantage than those with right-PTL or rectal-PTL. However, an extended biomarker panel demonstrated significant heterogeneity in panitumumab PFS effect within a tumour location. AREG/EREG and HER3 mRNA expression identifies patients with right-PTL or rectal-PTL who achieve similar PFS effect with panitumumab as left-colon patients. Testing could provide a more reliable basis for clinical decision making. Further validation and development of these biomarkers is required to optimise routine patient care.

CLINICAL TRIAL REGISTRATION

ISRCTN identifier: ISRCTN93248876.

EPA and DHA Fatty Acids Induce a Remodeling of Tumor Vasculature and Potentiate Docetaxel Activity

n-3 long chain Polyunsaturated Fatty Acids (n-3 LCPUFA) have been shown to improve the efficacy of conventional chemotherapies used for breast cancer treatment. In addition to their reported ability to increase the chemosensitivity of cancer cells, we hypothesized that n-3 LCPUFA could induce a remodeling of the vascular network in mammary tumors. A contrast-enhanced ultrasound method was used to monitor the vascular architecture during docetaxel treatment of mammary tumors in rats fed either a control or an n-3 LCPUFA-enriched diet (docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA)). The vascular network was remodeled in favor of smaller vessels (microvascularization), which represented 54% of the vasculature in n-3 LCPUFA tumors but only 26% in control tumors after 2 weeks of chemotherapy. Importantly, vascularization changes occurred both before and during docetaxel treatment. The density of smaller vessels quantified before chemotherapy was correlated with improved tumor size reduction by docetaxel treatment. Furthermore, transcript levels of the angiogenesis-specific genes epiregulin and amphiregulin were reduced by ~4.5- and twofold in tumors obtained from rats fed an n-3 LCPUFA-enriched diet compared to those of rats fed a control diet, respectively. Their expression levels were negatively correlated with tumor regression after chemotherapy. Taken together, this preclinical data strengthen the potential usefulness of n-3 LCPUFA as a complementary clinical strategy to improve drug efficiency via remodeling of the tumor vasculature.

Fibroblast-Derived Extracellular Vesicles Induce Colorectal Cancer Progression by Transmitting Amphiregulin

Extracellular vesicles (EV), structures surrounded by a biological membrane, transport biologically active molecules, and represent a recently identified way of intercellular communication. Colorectal cancer (CRC), one of the most common cancer types in the Western countries, is composed of both tumor and stromal cells and the amount of stromal fibroblasts negatively correlates with patient survival. Here we show that normal colon fibroblasts (NCF) release EVs with a characteristic miRNA cargo profile when stimulated with TGFβ, one of the most important activating factors of fibroblasts, without a significant increase in the amount of secreted EVs. Importantly, fibroblast-derived EVs induce cell proliferation in epidermal growth factor (EGF)-dependent patient-derived organoids, one of the best current systems to model the intra-tumoral heterogeneity of human cancers. In contrast, fibroblast-derived EVs have no effect in 3D models where EGF is dispensible. This EV-induced cell proliferation did not depend on whether NCFs or cancer-associated fibroblasts were studied or on the pre-activation by TGFβ, suggesting that TGFβ-induced sorting of specific miRNAs into EVs does not play a major role in enhancing CRC proliferation. Mechanistically, we provide evidence that amphiregulin, transported by EVs, is a major factor in inducing CRC cell proliferation. We found that neutralization of EV-bound amphiregulin blocked the effects of the fibroblast-derived EVs. Collectively, our data suggest a novel mechanism for fibroblast-induced CRC cell proliferation, coupled to EV-associated amphiregulin.

Amphiregulin promotes cisplatin chemoresistance by upregulating ABCB1 expression in human chondrosarcoma

Chondrosarcomas are well known for their resistance to chemotherapeutic agents, including cisplatin, which is commonly used in chondrosarcomas. Amphiregulin (AR), a ligand of epidermal growth factor receptor (EGFR), plays an important role in drug resistance. We therefore sought to determine the role of AR in cisplatin chemoresistance. We found that AR inhibits cisplatin-induced cell apoptosis and promotes ATP-binding cassette subfamily B member 1 (ABCB1) expression, while knockdown of ABCB1 by small interfering RNA (siRNA) reverses these effects. High phosphoinositide 3-kinase (PI3K), Akt and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) phosphorylation levels were observed in cisplatin-resistant cells. Pretreating chondrosarcoma cells with PI3K, Akt and NF-κB inhibitors or transfecting the cells with p85, Akt and p65 siRNAs potentiated cisplatin-induced cytotoxicity. In a mouse xenograft model, knockdown of AR expression in chondrosarcoma cells increased the cytotoxic effects of cisplatin and also decreased tumor volume and weight. These results indicate that AR upregulates ABCB1 expression through the PI3K/Akt/NF-κB signaling pathway and thus contributes to cisplatin resistance in chondrosarcoma.

Tissue regulatory T cells and neural repair

Inflammation and immune responses after tissue injury play pivotal roles in the pathology, resolution of inflammation, tissue recovery, fibrosis and remodeling. Regulatory T cells (Tregs) are the cells responsible for suppressing immune responses and can be activated in secondary lymphatic tissues, where they subsequently regulate effector T cell and dendritic cell activation. Recently, Tregs that reside in non-lymphoid tissues, called tissue Tregs, have been shown to exhibit tissue-specific functions that contribute to the maintenance of tissue homeostasis and repair. Unlike other tissue Tregs, the role of Tregs in the brain has not been well elucidated because the number of brain Tregs is very small under normal conditions. However, we found that Tregs accumulate in the brain at the chronic phase of ischemic brain injury and control astrogliosis through secretion of a cytokine, amphiregulin (Areg). Brain Tregs resemble other tissue Tregs in many ways but, unlike the other tissue Tregs, brain Tregs express neural-cell-specific genes such as the serotonin receptor (Htr7) and respond to serotonin. Administering serotonin or selective serotonin reuptake inhibitors (SSRIs) in an experimental mouse model of stroke increases the number of brain Tregs and ameliorates neurological symptoms. Knowledge of brain Tregs will contribute to the understanding of various types of neuroinflammation.

Amphiregulin modulates murine lung recovery and fibroblast function following exposure to agriculture organic dust

Exposure to agricultural bioaerosols can lead to chronic inflammatory lung diseases. Amphiregulin (AREG) can promote the lung repair process but can also lead to fibrotic remodeling. The objective of this study was to determine the role of AREG in altering recovery from environmental dust exposure in a murine in vivo model and in vitro using cultured human and murine lung fibroblasts. C57BL/6 mice were intranasally exposed to swine confinement facility dust extract (DE) or saline daily for 1 wk or allowed to recover for 3-7 days while being treated with an AREG-neutralizing antibody or recombinant AREG. Treatment with the anti-AREG antibody prevented resolution of DE exposure-induced airway influx of total cells, neutrophils, and macrophages and increased levels of TNF-α, IL-6, and CXCL1. Neutrophils and activated macrophages (CD11c+CD11bhi) persisted after recovery in lung tissues of anti-AREG-treated mice. In murine and human lung fibroblasts, DE induced the release of AREG and inflammatory cytokines. Fibroblast recellularization of primary human lung mesenchymal matrix scaffolds and wound closure was inhibited by DE and enhanced with recombinant AREG alone. AREG treatment rescued the DE-induced inhibitory fibroblast effects. AREG intranasal treatment for 3 days during recovery phase reduced repetitive DE-induced airway inflammatory cell influx and cytokine release. Collectively, these studies demonstrate that inhibition of AREG reduced, whereas AREG supplementation promoted, the airway inflammatory recovery response following environmental bioaerosol exposure, and AREG enhanced fibroblast function, suggesting that AREG could be targeted in agricultural workers repetitively exposed to organic dust environments to potentially prevent and/or reduce disease.