Staphylococcus aureus activates the Aryl Hydrocarbon Receptor in Human Keratinocytes

Staphylococcus (S.) aureus is an important pathogen causing various infections including - as most frequently isolated bacterium - cutaneous infections. Keratinocytes as the first barrier cells of the skin respond to S. aureus by the release of defense molecules such as cytokines and antimicrobial peptides. Although several pattern recognition receptors expressed in keratinocytes such as Toll-like and NOD-like receptors have been reported to detect the presence of S. aureus, the mechanisms underlying the interplay between S. aureus and keratinocytes are still emerging. Here we report that S. aureus induced gene expression of CYP1A1 and CYP1B1, responsive genes of the aryl hydrocarbon receptor (AhR). AhR activation by S. aureus was further confirmed by AhR gene reporter assays. AhR activation was mediated by factor(s) < 2 kDa secreted by S. aureus. Whole transcriptome analyses and real-time PCR analyses identified IL-24, IL-6 and IL-1beta as cytokines induced in an AhR-dependent manner in S. aureus-treated keratinocytes. AhR inhibition in a 3D organotypic skin equivalent confirmed the crucial role of the AhR in mediating the induction of IL-24, IL-6 and IL-1beta upon stimulation with living S. aureus. Taken together, we further highlight the important role of the AhR in cutaneous innate defense and identified the AhR as a novel receptor mediating the sensing of the important skin pathogen S. aureus in keratinocytes.

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Role of NF-kB RelB in Aryl Hydrocarbon Receptor-Mediated Ligand Specific Effects

International Journal of Molecular Sciences ◽

10.3390/ijms20112652 ◽

2019 ◽

Vol 20 (11) ◽

pp. 2652 ◽

Cited By ~ 2

Author(s):

Yasuhiro Ishihara ◽

Sarah Y. Kado ◽

Christiane Hoeper ◽

Shelly Harel ◽

Christoph F. A. Vogel

Keyword(s):

Aryl Hydrocarbon Receptor ◽

Functional Expression ◽

Dependent Manner ◽

Induced Expression ◽

Aryl Hydrocarbon ◽

Regulatory Enzymes ◽

Basal Expression ◽

Expression Of Genes ◽

Ahr Gene

Here, we investigate the role of RelB in the regulation of genes which were identified to be induced in an aryl hydrocarbon receptor (AhR)-dependent manner and critically involved in regulation of immune responses. We analyzed the expression of genes of the AhR gene battery, cytokines, and immune regulatory enzymes in bone marrow-derived macrophages (BMM) and thymus of B6 wildtype (wt) mice and RelB knockout (RelB−/−) mice after treatment with various AhR ligands. The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced expression of indoleamine 2,3-dioxygenase 1 (IDO1) and IDO2 was significantly repressed in thymus of RelB−/− mice but not in BMM derived from RelB−/− mice. Interestingly, the induced and basal expression of the cytokines interleukin (IL)-17A, IL-22, and CCL20 required the functional expression of RelB. The RelB-dependent expression of CCL20 was induced by the AhR ligands TCDD and 6-formylindolo[3,2-b]carbazole (FICZ), whereas indole-3-carbinol (I3C) suppressed CCL20 in lipopolysaccharide (LPS)-activated wt BMM. The LPS-induced expression of IL-6 and IL-10 was enhanced by TCDD and FICZ, whereas I3C significantly suppressed these cytokines in BMM. The exposure to FICZ led to higher increases of IL-17A and IL-22 mRNA compared to the effect of TCDD or I3C in thymus of wt mice. On the other hand, TCDD was the strongest inducer of CYP1A1, AhR Repressor (AhRR), and IDO2. In summary, these findings provide evidence for the important role of RelB in the transcriptional regulation of cytokines and enzymes induced by AhR ligands.

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Staphylococcus epidermidis Activates Aryl Hydrocarbon Receptor Signaling in Human Keratinocytes: Implications for Cutaneous Defense

Journal of Innate Immunity ◽

10.1159/000492162 ◽

2018 ◽

Vol 11 (2) ◽

pp. 125-135 ◽

Cited By ~ 4

Author(s):

Franziska Rademacher ◽

Maren Simanski ◽

Bettina Hesse ◽

Gregor Dombrowsky ◽

Nikolas Vent ◽

...

Keyword(s):

Aryl Hydrocarbon Receptor ◽

Staphylococcus Epidermidis ◽

Molecular Mechanisms ◽

Human Keratinocytes ◽

Skin Equivalent ◽

Dependent Manner ◽

Cytochrome P450 1A1 ◽

Aryl Hydrocarbon ◽

Skin Explants

Bacterial challenge of keratinocytes with the abundant skin commensal Staphylococcus epidermidis induces distinct innate immune responses, but the underlying molecular mechanisms are still emerging. We report that the aryl hydrocarbon receptor (AhR) was activated in human primary keratinocytes infected with S. epidermidis, leading to induction of the AhR-responsive gene cytochrome P450 1A1 (CYP1A1). In addition, functional AhR was required for S. epidermidis-mediated induction of IL-1β expression in keratinocytes. AhR-dependent gene induction of IL-1β and CYP1A1 was mediated by factor(s) < 2 kDa secreted by S. epidermidis. Blockade of the AhR in a 3D organotypic skin equivalent infected with S. epidermidis attenuated the S. epidermidis-induced CYP1A1 and IL-1β expression. Moreover, S. epidermidis also induced expression of IL-1α and of the antimicrobial peptide human β-defensin-3 in an AhR-dependent manner in a 3D skin equivalent. An increased outgrowth of S. epidermidis on the surface of skin explants treated with a specific AhR inhibitor further indicate a pivotal role of the AhR in mediating an epidermal defense response. Taken together, our data expand the role of the AhR in innate immunity and support a previously unappreciated contribution for the AhR in cutaneous defense.

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Aryl hydrocarbon receptor is essential for the pathogenesis of pulmonary arterial hypertension

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2023899118 ◽

2021 ◽

Vol 118 (11) ◽

pp. e2023899118

Author(s):

Takeshi Masaki ◽

Makoto Okazawa ◽

Ryotaro Asano ◽

Tadakatsu Inagaki ◽

Tomohiko Ishibashi ◽

...

Keyword(s):

Pulmonary Arterial Hypertension ◽

Arterial Hypertension ◽

Aryl Hydrocarbon Receptor ◽

Vascular Lesions ◽

Dependent Manner ◽

Sprague Dawley ◽

Aryl Hydrocarbon ◽

Sprague Dawley Rats ◽

Pulmonary Arterial

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by arteriopathy in the small to medium-sized distal pulmonary arteries, often accompanied by infiltration of inflammatory cells. Aryl hydrocarbon receptor (AHR), a nuclear receptor/transcription factor, detoxifies xenobiotics and regulates the differentiation and function of various immune cells. However, the role of AHR in the pathogenesis of PAH is largely unknown. Here, we explore the role of AHR in the pathogenesis of PAH. AHR agonistic activity in serum was significantly higher in PAH patients than in healthy volunteers and was associated with poor prognosis of PAH. Sprague–Dawley rats treated with the potent endogenous AHR agonist, 6-formylindolo[3,2-b]carbazole, in combination with hypoxia develop severe pulmonary hypertension (PH) with plexiform-like lesions, whereas Sprague–Dawley rats treated with the potent vascular endothelial growth factor receptor 2 inhibitors did not. Ahr-knockout (Ahr−/−) rats generated using the CRISPR/Cas9 system did not develop PH in the SU5416/hypoxia model. A diet containing Qing-Dai, a Chinese herbal drug, in combination with hypoxia led to development of PH in Ahr+/+ rats, but not in Ahr−/− rats. RNA-seq analysis, chromatin immunoprecipitation (ChIP)-seq analysis, immunohistochemical analysis, and bone marrow transplantation experiments show that activation of several inflammatory signaling pathways was up-regulated in endothelial cells and peripheral blood mononuclear cells, which led to infiltration of CD4+ IL-21+ T cells and MRC1+ macrophages into vascular lesions in an AHR-dependent manner. Taken together, AHR plays crucial roles in the development and progression of PAH, and the AHR-signaling pathway represents a promising therapeutic target for PAH.

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