The protective roles of integrin α4ß7 and Amphiregulin-expressing innate lymphoid cells in lupus nephritis.

Type 2 innate lymphoid cells (ILC2s) have emerged as key regulators of the immune response in renal inflammatory diseases such as lupus nephritis. However, the mechanisms underlying ILC2 adhesion and migration in the kidney remain poorly understood. Here, we revealed the critical role of integrin α4ß7 in mediating renal ILC2 adhesion and function. We found that integrin α4ß7 enables the retention of ILC2s in the kidney by binding to VCAM-1, E-cadherin, or fibronectin on structural cells. Moreover, integrin α4ß7 knockdown reduced the production of the reparative cytokine amphiregulin (Areg) by ILC2s. In lupus nephritis, TLR7/9 signaling within the kidney microenvironment downregulates integrin α4ß7 expression, leading to decreased Areg production and promoting the egress of ILC2s. Notably, IL-33 treatment upregulated integrin α4ß7 and Areg expression in ILC2s, thereby enhancing survival and reducing inflammation in lupus nephritis. Together, these findings highlight the potential of targeting ILC2 adhesion as a therapeutic strategy for autoimmune kidney diseases.

Profound Defect of Amphiregulin Secretion by Regulatory T Cells in the Gut of HIV-Treated Patients.

The persistence of a leaky gut in HIV-treated patients leads to chronic inflammation with increased rates of cardiovascular, liver, kidney, and neurological diseases. Tissue regulatory T (tTreg) cells are involved in the maintenance of intestinal homeostasis and wound repair through the IL-33 pathway. In this study, we investigated whether the persistence of gut mucosal injury during HIV infection might be explained in part by a flaw in the mechanisms involved in tissue repair. We observed an increased level of IL-33 in the gut of HIV-infected patients, which is associated with an increased level of fibrosis and a low peripheral reconstitution of CD4+ T cells. Our results showed that intestinal Treg cells from HIV-infected patients were enriched in tTreg cells prone to support tissue repair. However, we observed a functional defect in tTreg cells caused by the lack of amphiregulin secretion, which could contribute to the maintenance of intestinal damage. Our data suggest a mechanism by which the lack of amphiregulin secretion by tTreg may contribute to the lack of repair of the epithelial barrier.

Oral immune dysfunction is associated with the expansion of FOXP3+PD-1+Amphiregulin+ T cells during HIV infection.

Residual systemic inflammation and mucosal immune dysfunction persist in people living with HIV, despite treatment with combined anti-retroviral therapy, but the underlying immune mechanisms are poorly understood. Here we report that the altered immune landscape of the oral mucosa of HIV-positive patients on therapy involves increased TLR and inflammasome signaling, localized CD4+ T cell hyperactivation, and, counterintuitively, enrichment of FOXP3+ T cells. HIV infection of oral tonsil cultures in vitro causes an increase in FOXP3+ T cells expressing PD-1, IFN-γ, Amphiregulin and IL-10. These cells persist even in the presence of anti-retroviral drugs, and further expand when stimulated by TLR2 ligands and IL-1ß. Mechanistically, IL-1ß upregulates PD-1 expression via AKT signaling, and PD-1 stabilizes FOXP3 and Amphiregulin through a mechanism involving asparaginyl endopeptidase, resulting in FOXP3+ cells that are incapable of suppressing CD4+ T cells in vitro. The FOXP3+ T cells that are abundant in HIV-positive patients are phenotypically similar to the in vitro cultured, HIV-responsive FOXP3+ T cells, and their presence strongly correlates with CD4+ T cell hyper-activation. This suggests that FOXP3+ T cell dysregulation might play a role in the mucosal immune dysfunction of HIV patients on therapy.

Microbiota-derived short chain fatty acid promotion of Amphiregulin expression by dendritic cells is regulated by GPR43 and Blimp-1.

Dendritic cells (DC) are the most important antigen-presenting cells, which guide T cell activation and function, and dysregulated DC function might be one of the crucial causes of inflammatory bowel disease (IBD). It has been well-known that microbiota and their metabolites play an essential role in regulating the biology and function of DC, thus contributing to the pathogenesis of IBD. However, the underlying mechanisms remain largely unknown. Amphiregulin (AREG), a molecule of the epidermal growth factor (EGF) family, is primarily described as an epithelial cell-derived cytokine and recognized as a critical regulator of cell proliferation and tissue repair. Here, we found that DC expression of AREG depended on butyrate (a microbiota-derived short chained fatty acid), which required the interaction between butyrate and G-protein-coupled receptor 43 (GPR43). Furthermore, we found that butyrate-GPR43 interaction failed to induce AREG expression in DC deficient in B lymphocyte induced maturation protein 1 (Blimp-1). Notably, DC-derived AREG was indispensable for the protection against experimental colitis in mice. Additionally, AREG expression was significantly decreased in DC from IBD patients. Our data provide novel evidences to interpret how AREG expression is regulated in DC, and shed new light on the mechanisms whereby microbiota regulate DC function.

Single-cell analysis of RORα tracer mouse lung reveals ILC progenitors and effector ILC2 subsets.

Lung group 2 innate lymphoid cells (ILC2s) drive allergic inflammation and promote tissue repair. ILC2 development is dependent on the transcription factor retinoic acid receptor-related orphan receptor (RORα), which is also expressed in common ILC progenitors. To elucidate the developmental pathways of lung ILC2s, we generated RORα lineage tracer mice and performed single-cell RNA sequencing, flow cytometry, and functional analyses. In adult mouse lungs, we found an IL-18Rα+ST2- population different from conventional IL-18Rα-ST2+ ILC2s. The former was GATA-3intTcf7EGFP+Kit+, produced few cytokines, and differentiated into multiple ILC lineages in vivo and in vitro. In neonatal mouse lungs, three ILC populations were identified, namely an ILC progenitor population similar to that in adult lungs and two distinct effector ILC2 subsets that differentially produced type 2 cytokines and amphiregulin. Lung ILC progenitors might actively contribute to ILC-poiesis in neonatal and inflamed adult lungs. In addition, neonatal lung ILC2s include distinct proinflammatory and tissue-repairing subsets.

Targeting amphiregulin (AREG) derived from senescent stromal cells diminishes cancer resistance and averts programmed cell death 1 ligand (PD-L1)-mediated immunosuppression.

Aging is characterized by a progressive loss of physiological integrity, while cancer represents one of the primary pathological factors that severely threaten human lifespan and healthspan. In clinical oncology, drug resistance limits the efficacy of most anticancer treatments, and identification of major mechanisms remains a key to solve this challenging issue. Here, we highlight the multifaceted senescence-associated secretory phenotype (SASP), which comprises numerous soluble factors including amphiregulin (AREG). Production of AREG is triggered by DNA damage to stromal cells, which passively enter senescence in the tumor microenvironment (TME), a process that remarkably enhances cancer malignancy including acquired resistance mediated by EGFR. Furthermore, paracrine AREG induces programmed cell death 1 ligand (PD-L1) expression in recipient cancer cells and creates an immunosuppressive TME via immune checkpoint activation against cytotoxic lymphocytes. Targeting AREG not only minimized chemoresistance of cancer cells, but also restored immunocompetency when combined with classical chemotherapy in humanized animals. Our study underscores the potential of in vivo SASP in driving the TME-mediated drug resistance and shaping an immunosuppressive niche, and provides the proof of principle of targeting major SASP factors to improve therapeutic outcome in cancer medicine, the success of which can substantially reduce aging-related morbidity and mortality.

Increased TSLP, IL-33, IL-25, IL-19, IL 21 and amphiregulin (AREG) levels in chronic rhinosinusitis with nasal polyp.

OBJECTIVE: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease. The surrogate indicating biomarkers in patients with CRSwNP need further evaluation. The aim of this study was to investigate the association of thymic stromal lymphopoietin (TSLP) and amphiregulin (AREG) cytokines in patients with CRSwNP. METHODS: Sinonasal tissue samples were collected from 33 patients with CRSwNP and 29 controls. Levels of AREG, IL-19, IL-21, IL-25, IL-33 and TSLP in nasal polyp and control sinonasal tissues were determined following the enzyme-linked immunosorbent assay method. RESULTS: We found that AREG, IL-19, IL-21, IL-25, IL-33 and TSLP levels were significantly higher in the CRSwNP group compared to the control group (p < 0.000; p < 0.000; p < 0.000; p < 0.000; p < 0.003; p < 0.021, respectively). CONCLUSIONS: Our findings indicated that AREG, IL-19, IL-21, IL-25, IL-33 and TSLP were significantly increased in tissue samples of CRSwNP patients and may be considered as molecular indicators and targets for therapeutic developments for patients with CRSwNP.

Multiple myeloma-derived exosomes are enriched of amphiregulin (AREG) and activate the epidermal growth factor pathway in the bone microenvironment leading to osteoclastogenesis.

BACKGROUND: Multiple myeloma (MM) is a clonal plasma cell malignancy associated with osteolytic bone disease. Recently, the role of MM-derived exosomes in the osteoclastogenesis has been demonstrated although the underlying mechanism is still unknown. Since exosomes-derived epidermal growth factor receptor ligands (EGFR) are involved in tumor-associated osteolysis, we hypothesize that the EGFR ligand amphiregulin (AREG) can be delivered by MM-derived exosomes and participate in MM-induced osteoclastogenesis. METHODS: Exosomes were isolated from the conditioned medium of MM1.S cell line and from bone marrow (BM) plasma samples of MM patients. The murine cell line RAW264.7 and primary human CD14+ cells were used as osteoclast (OC) sources. RESULTS: We found that AREG was specifically enriched in exosomes from MM samples and that exosomes-derived AREG led to the activation of EGFR in pre-OC, as showed by the increase of mRNA expression of its downstream SNAIL in both RAW264.7 and CD14+ cells. The presence of neutralizing anti-AREG monoclonal antibody (mAb) reverted this effect. Consequently, we showed that the effect of MM-derived exosomes on osteoclast differentiation was inhibited by the pre-treatment of exosomes with anti-AREG mAb. In addition, we demonstrated the ability of MM-derived AREG-enriched exosomes to be internalized into human mesenchymal stromal cells (MSCs) blocking osteoblast (OB) differentiation, increasing MM cell adhesion and the release of the pro-osteoclastogenic cytokine interleukin-8 (IL8). Accordingly, anti-AREG mAb inhibited the release of IL8 by MSCs suggesting that both direct and indirect effects are responsible for AREG-enriched exosomes involvement on MM-induced osteoclastogenesis. CONCLUSIONS: In conclusion, our data indicate that AREG is packed into MM-derived exosomes and implicated in OC differentiation through an indirect mechanism mediated by OBs.

Amphiregulin potentiates airway inflammation and mucus hypersecretion induced by urban particulate matter via the EGFR-PI3Kα-AKT/ERK pathway.

Ambient particulate matter (PM) promotes the development and exacerbation of chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD) and asthma, by increasing inflammation and mucus hypersecretion. However, the biological mechanisms underlying PM-induced airway inflammation and mucus hypersecretion remain unclear. Amphiregulin (AREG) is an important ligand for epidermal growth factor receptor (EGFR) and participates in the regulation of several biological functions. Here, the PM-exposed human bronchial epithelial cell (HBEC) model was used to define the role of AREG in PM-induced inflammation and mucus hypersecretion and its related signaling pathways. The expression of AREG was significantly increased in a dose-dependent manner in HBECs subjected to PM exposure. Moreover, PM could induce inflammation and mucus hypersecretion by upregulating the expression of IL-1α, IL-1ß, and Muc-5ac in HBECs. The EGFR, AKT, and ERK signaling pathways were also activated in a time- and dose-dependent manner. The AREG siRNA markedly attenuated PM-induced inflammation and mucus hypersecretion, and activation of the EGFR-AKT/ERK pathway. Exogenous AREG significantly increased the expression of IL-1α, IL-1ß, and Muc-5ac, and induced activation of the EGFR-AKT/ERK pathway in HBECs. Further, under PM exposure, exogenous AREG significantly potentiated PM-induced inflammation and mucus hypersecretion, and activation of the EGFR-AKT/ERK pathway. Tumor-necrosis factor-alpha converting enzyme (TACE) and EGFR specific inhibitor pretreatment showed that AREG was secreted by TACE-mediated cleavage to regulate PM-induced inflammation and mucus hypersecretion by binding to the EGFR. Moreover, according to the inhibitory effect of specific inhibitors of the class I PI3K isoforms, AKT and ERK, PM-induced inflammation and mucus hypersecretion was regulated by PI3Kα activation and its downstream AKT and ERK pathways. This study strongly suggests the adverse effect of AREG in PM-induced inflammation and mucus hypersecretion via the EGFR-PI3Kα-AKT/ERK pathway. These findings contribute to a better understanding of the biological mechanisms underlying exacerbation of chronic respiratory diseases induced by PM exposure.

Amphiregulin-Producing Pathogenic Memory T Helper 2 Cells Instruct Eosinophils to Secrete Osteopontin and Facilitate Airway Fibrosis.

Memory T cells provide long-lasting protective immunity, and distinct subpopulations of memory T cells drive chronic inflammatory diseases such as asthma. Asthma is a chronic allergic inflammatory disease with airway remodeling including fibrotic changes. The immunological mechanisms that induce airway fibrotic changes remain unknown. We found that interleukin-33 (IL-33) enhanced amphiregulin production by the IL-33 receptor, ST2hi memory T helper 2 (Th2) cells. Amphiregulin-epidermal growth factor receptor (EGFR)-mediated signaling directly reprogramed eosinophils to an inflammatory state with enhanced production of osteopontin, a key profibrotic immunomodulatory protein. IL-5-producing memory Th2 cells and amphiregulin-producing memory Th2 cells appeared to cooperate to establish lung fibrosis. The analysis of polyps from patients with eosinophilic chronic rhinosinusitis revealed fibrosis with accumulation of amphiregulin-producing CRTH2hiCD161hiCD45RO+CD4+ Th2 cells and osteopontin-producing eosinophils. Thus, the IL-33-amphiregulin-osteopontin axis directs fibrotic responses in eosinophilic airway inflammation and is a potential target for the treatment of fibrosis induced by chronic allergic disorders.

Epidermal Growth Factor Receptor Expression Licenses Type-2 Helper T Cells to Function in a T Cell Receptor-Independent Fashion.

Gastro-intestinal helminth infections trigger the release of interleukin-33 (IL-33), which induces type-2 helper T cells (Th2 cells) at the site of infection to produce IL-13, thereby contributing to host resistance in a T cell receptor (TCR)-independent manner. Here, we show that, as a prerequisite for IL-33-induced IL-13 secretion, Th2 cells required the expression of the epidermal growth factor receptor (EGFR) and of its ligand, amphiregulin, for the formation of a signaling complex between T1/ST2 (the IL-33R) and EGFR. This shared signaling complex allowed IL-33 to induce the EGFR-mediated activation of the MAP-kinase signaling pathway and consequently the expression of IL-13. Lack of EGFR expression on T cells abrogated IL-13 expression in infected tissues and impaired host resistance. EGFR expression on Th2 cells was TCR-signaling dependent, and therefore, our data reveal a mechanism by which antigen presentation controls the innate effector function of Th2 cells at the site of inflammation.

Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia.

To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2-3weeks) which either underwent unilateral or bilateral lens-induced myopization (group 1) or which were primarily myopic at baseline (group 2) received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15µg) three times in intervals of 9days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00ng, respectively). In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.

Regulatory T cells and skeletal muscle regeneration.

Skeletal muscle regeneration results from the activation and differentiation of myogenic stem cells, called satellite cells, located beneath the basal lamina of the muscle fibers. Inflammatory and immune cells have a crucial role in the regeneration process. Acute muscle injury causes an immediate transient wave of neutrophils followed by a more persistent infiltration of M1 (proinflammatory) and M2 (anti-inflammatory/proregenerative) macrophages. New studies show that injured muscle is also infiltrated by a specialized population of regulatory T (Treg) cells, which control both the inflammatory response, by promoting the M1-to-M2 switch, and the activation of satellite cells. Treg cells accumulate in injured muscle in response to specific cytokines, such as IL-33, and promote muscle growth by releasing growth factors, such as amphiregulin. Muscle repair during aging is impaired due to reduced number of Treg cells and can be enhanced by IL-33 supplementation. Migration of Treg cells could also contribute to explain the effect of heterochronic parabiosis, whereby muscle regeneration of aged mice can be improved by a parabiotically linked young partners. In mdx dystrophin-deficient mice, a model of human Duchenne muscular dystrophy, muscle injury, and inflammation is mitigated by expansion of the Treg-cell population but exacerbated by Treg-cell depletion. These findings support the notion that immunological mechanisms are not only essential in the response to pathogenic microbes and tumor cells but also have a wider homeostatic role in tissue repair, and open new perspectives for boosting muscle growth in chronic muscle disease and during aging.

Progesterone-Based Therapy Protects Against Influenza by Promoting Lung Repair and Recovery in Females.

Over 100 million women use progesterone therapies worldwide. Despite having immunomodulatory and repair properties, their effects on the outcome of viral diseases outside of the reproductive tract have not been evaluated. Administration of exogenous progesterone (at concentrations that mimic the luteal phase) to progesterone-depleted adult female mice conferred protection from both lethal and sublethal influenza A virus (IAV) infection. Progesterone treatment altered the inflammatory environment of the lungs, but had no effects on viral load. Progesterone treatment promoted faster recovery by increasing TGF-ß, IL-6, IL-22, numbers of regulatory Th17 cells expressing CD39, and cellular proliferation, reducing protein leakage into the airway, improving pulmonary function, and upregulating the epidermal growth factor amphiregulin (AREG) in the lungs. Administration of rAREG to progesterone-depleted females promoted pulmonary repair and improved the outcome of IAV infection. Progesterone-treatment of AREG-deficient females could not restore protection, indicating that progesterone-mediated induction of AREG caused repair in the lungs and accelerated recovery from IAV infection. Repair and production of AREG by damaged respiratory epithelial cell cultures in vitro was increased by progesterone. Our results illustrate that progesterone is a critical host factor mediating production of AREG by epithelial cells and pulmonary tissue repair following infection, which has important implications for women's health.

Amphiregulin Confers Regulatory T Cell Suppressive Function and Tumor Invasion via the EGFR/GSK-3ß/Foxp3 Axis.

Previous studies mainly focused on the role of the epidermal growth factor receptor (EGFR) in tumor cells, whereas the effects of the EGFR on immune responses has not been determined. Our study shows that the EGFR signaling pathway play a role in the regulation of regulatory T cells (Treg cells) in cancer patients. The EGF-like growth factor Amphiregulin (AREG) protein was frequently up-regulated in a tissue microarray, which was associated with worse overall survival. Additionally, in sera, tissue specimens, and effusions of lung or gastric cancer patients, up-regulated AREG protein enhanced the suppressive function of Treg cells. AREG maintained the Treg cell suppressive function via the EGFR/GSK-3ß/Foxp3 axis in vitro and in vivo Furthermore, inhibition of EGFR by the tyrosine kinase inhibitor gefitinib restored the activity of GSK-3ß and attenuated Treg cell function. ß-TrCP was involved in GSK-3ß-mediated Foxp3 degradation, and mass spectrometry identified Lys356 as the ubiquitination site of Foxp3 by ß-TrCP. These findings demonstrate the posttranslational regulation of Foxp3 expression by AREG in cancer patients through AREG/EGFR/GSK-3ß signaling, which could lead to Foxp3 protein degradation in Treg cells and a potential therapeutic target for cancer treatment.

Amphiregulin in Cancer: New Insights for Translational Medicine.

Although there is a large body of literature regarding amphiregulin (AREG) in human cancer, most knowledge focuses on its cell-autonomous functions in epithelial malignancies. Recent studies revealed that AREG is also present in the tumor microenvironment (TME) and contributes to therapeutic resistance. We discuss emerging concepts of AREG tumor biology and highlight their implications for translational medicine.