Analysis of gene expression in peripheral blood eosinophils from patients with atopic dermatitis and in vitro cytokine-stimulated blood eosinophils

Epigenetic Methylation Changes in Pregnant Women: Bisphenol Exposure and Atopic Dermatitis

Bisphenol is a chemical substance widely used in plastic products and food containers. In this study, we observed a relationship between DNA methylation and atopic dermatitis (AD) in the peripheral blood mononuclear cells (PBMCs) of pregnant women exposed to bisphenol A (BPA) and its alternatives, bisphenol S (BPS) and bisphenol F (BPF). DNA methylation is an epigenetic mechanism that regulates gene expression, which can be altered by environmental factors, and affects the onset and progression of diseases. We found that genes belonging to the JAK-STAT and PI3K-AKT signaling pathways were hypomethylated in the blood of pregnant women exposed to bisphenols. These genes play important roles in skin barrier function and immune responses, and may influence AD. Therefore, we suggest that not only BPA, but also BPS and BPF, which are used as alternatives, can have a negative impact on AD through epigenetic mechanisms.

Structural Perspective of NR4A Nuclear Receptor Family and Their Potential Endogenous Ligands

There are 48 nuclear receptors in the human genome, and many members of this superfamily have been implicated in human diseases. The NR4A nuclear receptor family consisting of three members, NR4A1, NR4A2, and NR4A3 (formerly annotated as Nur77, Nurr1, and NOR1, respectively), are still orphan receptors but exert pathological effects on immune-related and neurological diseases. We previously reported that prostaglandin A1 (PGA1) and prostaglandin A2 (PGA2) are potent activators of NR4A3, which bind directly to the ligand-binding domain (LBD) of the receptor. Recently, the co-crystallographic structures of NR4A2-LBD bound to PGA1 and PGA2 were reported, followed by reports of the neuroprotective effects of these possible endogenous ligands in mouse models of Parkinson's disease. Based on these structures, we modeled the binding structures of the other two members (NR4A1 and NR4A3) with these potential endogenous ligands using a template-based modeling method, and reviewed the similarity and diversity of ligand-binding mechanisms in the nuclear receptor family.

Functional association of NR4A3 downregulation with impaired differentiation in myeloid leukemogenesis

The coincident downregulation of NR4A1 and NR4A3 has been implicated in myeloid leukemogenesis, but it remains unknown how these two genes function in myeloid cells and how their combined downregulation promotes myeloid leukemogenesis. Since NR4A1 abrogation is thought to confer a survival and proliferation advantage to myeloid cells, we hypothesized that downregulation of NR4A3 may have a complementary effect on myeloid cell differentiation. First, we tested the association between differentiation status of leukemic cells and NR4A3 expression using two large clinical datasets from patients with different acute myeloid leukemia (AML) subtypes. The analysis revealed a close association between differentiation status and different subtypes of AML Then, we probed the effects of differentiation-inducing treatments on NR4A3 expression and NR4A3 knockdown on cell differentiation using two myeloid leukemia cell lines. Differentiation-inducing treatments caused upregulation of NR4A3, while NR4A3 knockdown prevented differentiation in both cell lines. The cell culture findings were validated using samples from chronic myeloid leukemia (CML) patients at chronic, accelerated and blastic phases, and in acute promyelocytic leukemia (APL) patients before and after all trans-retinoic acid (ATRA)-based differentiation therapy. Progressive NR4A3 downregulation was coincident with impairments in differentiation in patients during progression to blastic phase of CML, and NR4A3 expression was increased in APL patients treated with ATRA-based differentiating therapy. Together, our findings demonstrate a tight association between impaired differentiation status and NR4A3 downregulation in myeloid leukemias, providing a plausible mechanistic explanation of how myeloid leukemogenesis might occur upon concurrent downregulation of NR4A1 and NR4A3.

Review-Current Concepts in Inflammatory Skin Diseases Evolved by Transcriptome Analysis: In-Depth Analysis of Atopic Dermatitis and Psoriasis

During the last decades, high-throughput assessment of gene expression in patient tissues using microarray technology or RNA-Seq took center stage in clinical research. Insights into the diversity and frequency of transcripts in healthy and diseased conditions provide valuable information on the cellular status in the respective tissues. Growing with the technique, the bioinformatic analysis toolkit reveals biologically relevant pathways which assist in understanding basic pathophysiological mechanisms. Conventional classification systems of inflammatory skin diseases rely on descriptive assessments by pathologists. In contrast to this, molecular profiling may uncover previously unknown disease classifying features. Thereby, treatments and prognostics of patients may be improved. Furthermore, disease models in basic research in comparison to the human disease can be directly validated. The aim of this article is not only to provide the reader with information on the opportunities of these techniques, but to outline potential pitfalls and technical limitations as well. Major published findings are briefly discussed to provide a broad overview on the current findings in transcriptomics in inflammatory skin diseases.

Oral administration of Cervus nippon mantchuricus extract suppresses 2,4-dinitrochlorobenzene-induced atopic dermatitis in BALB/c mice and inflammatory effects in mast cells

Cervus nippon mantchuricus extract, known as nok‑gol (NGE) in Korean, is useful for the treatment of various inflammatory diseases, including bone resorption and neutropenia. However, NGE has not been widely investigated, and its efficacy and safety remain to be fully elucidated. In the present study, histological analysis, blood analysis, reverse transcription‑semi-quantitative polymerase chain reaction analysis and enzyme‑linked immunosorbent assays were performed to verify the inhibitory effect of NGE on atopic dermatitis (AD) in BALB/c mice and on inflammatory effects in HMC‑1 human mast cells. NGE suppressed the development of AD in mice, and decreased the infiltration of inflammatory cells, mast cells and CD4+ T cells into AD skin lesions. NGE also decreased leukocyte levels induced by 2,4‑dinitrochlorobenzene (DNCB). NGE alleviated AD‑like inflammatory symptoms in mice by suppressing the production of CD4+ T cells. NGE downregulated the mRNA expression of inflammatory cytokines induced by DNCB. It also decreased the serum immunoglobulin E concentration and inflammatory cytokine levels in DNCB‑treated BALB/c mice. The in vitro experiments demonstrated that NGE reduced the phorbol 12‑myristate 13‑acetate + ionomycin‑induced expression of pro‑inflammatory cytokines interleukin (IL)‑4, IL‑13, tumor necrosis factor‑α, and IL‑6 in HMC‑1 cells. Taken together, the results of the present study indicated that NGE suppressed the progression of DNCB‑induced AD in BALB/c mice and reduced inflammatory effects in HMC‑1 cells. This suggests that NGE may be a useful drug for the treatment of AD.

DP1 receptor signaling prevents the onset of intrinsic apoptosis in eosinophils and functions as a transcriptional modulator

Prostaglandin (PG) D₂ is the ligand for the G-protein coupled receptors DP1 (D-type prostanoid receptor 1) and DP2 (also known as chemoattractant receptor homologous molecule, expressed on Th2 cells; CRTH2). Both, DP1 and DP2 are expressed on the cellular surface of eosinophils; although it has become quite clear that PGD₂ induces eosinophil migration mainly via DP2 receptors, the role of DP1 in eosinophil responses has remained elusive. In this study, we addressed how DP1 receptor signaling complements the pro-inflammatory effects of DP2. We found that PGD₂ prolongs the survival of eosinophils via a DP1 receptor-mediated mechanism that inhibits the onset of the intrinsic apoptotic cascade. The DP1 agonist BW245c prevented the activation of effector caspases in eosinophils and protected mitochondrial membranes from depolarization which-as a consequence-sustained viability of eosinophils. DP1 activation in eosinophils enhanced the expression of the anti-apoptotic gene BCL-X_L , but also induced pro-inflammatory genes, such as VLA-4 and CCR3. In HEK293 cells that overexpress recombinant DP1 and/or DP2 receptors, activation of DP1, but not DP2, delayed cell death and stimulated proliferation, along with induction of serum response element (SRE), a regulator of anti-apoptotic, early-response genes. We conclude that DP1 receptors promote the survival via SRE induction and induction of pro-inflammatory genes. Therefore, targeting DP1 receptors, along with DP2, may contribute to anti-inflammatory therapy in eosinophilic diseases.

Circulating Human Eosinophils Share a Similar Transcriptional Profile in Asthma and Other Hypereosinophilic Disorders

Eosinophils are leukocytes that are released into the peripheral blood in a phenotypically mature state and are capable of being recruited into tissues in response to appropriate stimuli. Eosinophils, traditionally considered cytotoxic effector cells, are leukocytes recruited into the airways of asthma patients where they are believed to contribute to the development of many features of the disease. This perception, however, has been challenged by recent findings suggesting that eosinophils have also immunomodulatory functions and may be involved in tissue homeostasis and wound healing. Here we describe a transcriptome-based approach-in a limited number of patients and controls-to investigate the activation state of circulating human eosinophils isolated by flow cytometry. We provide an overview of the global expression pattern in eosinophils in various relevant conditions, e.g., eosinophilic asthma, hypereosinophilic dermatological diseases, parasitosis and pulmonary aspergillosis. Compared to healthy subjects, circulating eosinophils isolated from asthma patients differed in their gene expression profile which is marked by downregulation of transcripts involved in antigen presentation, pathogen recognition and mucosal innate immunity, whereas up-regulated genes were involved in response to non-specific stimulation, wounding and maintenance of homeostasis. Eosinophils from other hypereosinophilic disorders displayed a very similar transcriptional profile. Taken together, these observations seem to indicate that eosinophils exhibit non-specific immunomodulatory functions important for tissue repair and homeostasis and suggest new roles for these cells in asthma immunobiology.

Opposing regulation of PROX1 by interleukin-3 receptor and NOTCH directs differential host cell fate reprogramming by Kaposi sarcoma herpes virus

Lymphatic endothelial cells (LECs) are differentiated from blood vascular endothelial cells (BECs) during embryogenesis and this physiological cell fate specification is controlled by PROX1, the master regulator for lymphatic development. When Kaposi sarcoma herpes virus (KSHV) infects host cells, it activates the otherwise silenced embryonic endothelial differentiation program and reprograms their cell fates. Interestingly, previous studies demonstrated that KSHV drives BECs to acquire a partial lymphatic phenotype by upregulating PROX1 (forward reprogramming), but stimulates LECs to regain some BEC-signature genes by downregulating PROX1 (reverse reprogramming). Despite the significance of this KSHV-induced bidirectional cell fate reprogramming in KS pathogenesis, its underlying molecular mechanism remains undefined. Here, we report that IL3 receptor alpha (IL3Rα) and NOTCH play integral roles in the host cell type-specific regulation of PROX1 by KSHV. In BECs, KSHV upregulates IL3Rα and phosphorylates STAT5, which binds and activates the PROX1 promoter. In LECs, however, PROX1 was rather downregulated by KSHV-induced NOTCH signal via HEY1, which binds and represses the PROX1 promoter. Moreover, PROX1 was found to be required to maintain HEY1 expression in LECs, establishing a reciprocal regulation between PROX1 and HEY1. Upon co-activation of IL3Rα and NOTCH, PROX1 was upregulated in BECs, but downregulated in LECs. Together, our study provides the molecular mechanism underlying the cell type-specific endothelial fate reprogramming by KSHV.

Kaposi's sarcoma (KS) is one of the most common neoplasms in HIV-positive individuals and organ transplant recipients. KS-associated herpes virus (KSHV), also known as human herpes virus (HHV)-8, has been identified as the causative agent and infects endothelial cells to form KS. Importantly, we and others have discovered that when KSHV infects endothelial cells of blood vessels, it reprograms host cells to resemble endothelial cells in lymphatic vessels. On the other hand, when KSHV infects endothelial cells in lymphatic vessels, the virus directs the host cells to partially obtain the phenotypes of blood vessel endothelial cells. These host cell reprogramming represent abnormal pathological processes, which are not as complete as the physiological process occurring during embryonic development. Currently, it is not clear how and why this cancer causing virus modifies the fate of its host cells. In this study, we aimed to dissect the molecular mechanism underlying the virus-induced host cell fate reprogramming and found two important cellular signaling pathways, interleukin-3 and Notch, playing key roles in the pathological events. Our current study provides a better understanding of KS tumorigenesis with a potential implication in a new KS therapy.

Strain-dependent resistance to allergen-induced lung pathophysiology in mice correlates with rate of apoptosis of lung-derived eosinophils

Although exposed to similar allergic and environmental stimuli, not all humans develop asthma. Similarly, mouse strains vary in the degree of pathophysiology seen following induction of experimental asthma. Three mouse strains (CBA/Ca, BALB/c, and C57BL/6) were used to determine if the extent and duration of inflammation influenced the degree of lung tissue damage in an OVA-induced allergic asthma model. Airways obstruction, leukocyte infiltration, edema, eosinophil accumulation, and degranulation were less severe in wild-type (wt) CBA/Ca mice than wt BALB/c and C57BL/6 mice. F1 hybrids of CBA/Ca mice crossed with BALB/c or C57BL/6 mice had bronchoalveolar lavage leukocyte (BAL) and cell-free protein profiles similar to those of the respective disease-susceptible parental strain. IL-5 transgene expression on each of the three genetic backgrounds accentuated the difference between CBA/Ca and the other two strains. Importantly, even when overexpressing IL-5, CBA/Ca mice did not develop substantial airways obstruction. Eosinophils recovered from the airways of allergic wt and IL-5 transgenic (Tg) CBA/Ca mice entered apoptosis at a faster rate than eosinophils from the other parental strains and F1 hybrids. In contrast, eosinophils harvested from the peritoneal cavities of untreated CBA/Ca IL-5 Tg mice had a relatively low rate of apoptosis in vitro. The CBA/Ca mouse strain is therefore relatively resistant to experimental asthma, and this may be a consequence of a propensity for apoptosis of eosinophils recruited into the allergic lung. Restricting survival of a key effector cell may thus limit pathogenesis in this experimental model and in humans.

The NR4A nuclear receptor family in eosinophils

It is well-known that many members of the family of nuclear receptors have been implicated in human diseases, and metabolic disorders in particular. The NR4A nuclear receptor family consists of three members, Nur77, Nurr1, and NOR1. All of these are orphan receptors, and Nur77 and NOR1 exert possible pathological roles in immune diseases through the modulation of leukocyte functions. CD30 stimulation, which induces eosinophil-specific apoptosis, markedly enhances expression of Nur77 and NOR1 in eosinophils. This suggests the possibility of pharmacological modulation of Nur77- or NOR1-specific apoptotic pathways via receptor-dependent transactivation. In this review, we discuss treatment of allergic diseases by low molecular weight compounds acting through the NR4A receptor family to cause eosinophil apoptosis. NR4A nuclear receptor genes were selected following comprehensive analysis of differentially expressed genes in eosinophils of atopic dermatitis patients compared with healthy volunteers.

Much atopy about the skin: genome-wide molecular analysis of atopic eczema

BACKGROUND

Atopic eczema (AE) is a chronic inflammatory skin disorder with an increasing prevalence in industrialized countries.

METHODS

Genox Research Incorporation was founded in 1996 to identify new genes involved in allergic diseases in collaboration with the National Children's Hospital in Tokyo. In the AE project, they have discovered several hundred new genes and partial DNA sequences by mainly using microarrays. Here, I review the results obtained using transcriptome analysis, performed by Genox and other investigators.

RESULTS

Transcriptome analysis using skin lesion, CD4+ T cells, monocytes and eosinophils derived from AE patients identified some differentially expressed genes which became biologically relevant in the following studies. Missing linkages between these genes have been found due to the recent development of genomics.

CONCLUSION

Many AE-related genes found in the genome-wide studies still remain to be determined regarding their functions and to be systemically organized. After the comprehensive characterization of these genes by further studies, we will identify the precise molecular mechanisms involved in AE and other diseases.

NR4A orphan nuclear receptor family in peripheral blood eosinophils from patients with atopic dermatitis and apoptotic eosinophils in vitro

To identify novel genes related to the clinical signs of atopic dermatitis (AD), differentially expressed genes were sought in peripheral blood eosinophils from both AD patients and healthy volunteers. RNA was prepared from eosinophils, expression of various genes was monitored using the Affymetrix GeneChip, and expression was quantified by real-time RT-PCR. Two genes, Nur77 and NOR1, members of NR4A orphan nuclear receptor family, were expressed at a significantly higher level in AD patients than in healthy volunteers. Expression of another gene in the NR4A receptor family, Nurr1, was also higher in AD patients than in healthy volunteers. When peripheral blood leukocytes from healthy volunteers were fractionated, NOR1 expression was highest in eosinophils, but expression of Nur77 and Nurr1 genes was not eosinophil-specific. Extremely intense apoptosis was induced in both eosinophils and an eosinophil cell line, AML14.3D10, by treatment with antibody (Ab) to both CD30 and Fas. Rapid expression of the genes for the NR4A receptor family was observed with anti-CD30 Ab treatment but not with anti-Fas Ab. The NR4A orphan nuclear receptor family gene expression and the subsequent eosinophil apoptosis were downregulated by the MAPK inhibitor, U0126. These results suggest that the expression of the NR4A receptor family genes through CD30 signaling may regulate eosinophil apoptosis in allergic conditions such as AD.

Expansion of activated eosinophils in infants with severe atopic dermatitis

BACKGROUND

There is increasing concern in Japan over infants with atopic dermatitis (AD) who present with severe systemic complications, such as hypoproteinemia, electrolyte disturbances, and delayed growth and development. They are often associated with extremely increased numbers of circulating eosinophils. However, the clinical significance of eosinophil expansion has not been thoroughly investigated.

METHODS

This study attempted to determine the significance of eosinophilia and eosinophil activation in infant cases of AD by comparing multiple clinical parameters, indexes of eosinophil activation, and levels of serum cytokines. CD69 expression was determined by flow cytometry. The clinical severity of AD was graded by the severity SCORing of atopic dermatitis (SCORAD) method. Patients were classified into two groups, with and without CD69 on eosinophils. Nuclear lobes were evaluated under a microscopy. Serum levels of eosinophil-derived neurotoxin (EDN), interleukin (IL)-12, IL-18, IL-4, IL-5 and interferon (IFN)-gamma were determined by enzyme-linked immunosorbent assay.

RESULTS

Patients with CD69-positive eosinophils had significantly higher numbers of eosinophils and platelets, total IgE, and eosinophil nuclear lobes. They also showed growth failure, developmental delay, low serum albumin, and electrolyte disturbances. EDN and IL-18 levels were significantly increased in this group, but the levels of IL-4, IL-5 and IL-12 were not significantly different between the two groups. IFN-gamma was not detectable in all patients with AD. Surface expression of CD69 indicates intense systemic allergic inflammation induced in severe cases of AD.

CONCLUSIONS

Evaluation of eosinophil activation and early therapeutic intervention is mandatory for the treatment of severe AD during infancy.

Expression of a Human SOCS Protein, HSOCP-1, in Peripheral Blood Eosinophils from Patients with Atopic Dermatitis

To identify new genes related to atopic dermatitis (AD), we screened for differentially expressed genes in peripheral blood eosinophils derived from AD patients and healthy volunteers. RNA was prepared from peripheral blood eosinophils obtained from both AD patients and healthy volunteers, and the expression of various genes was monitored using fluorescent differential display and real-time RT-PCR. One of the expressed sequence tags (ESTs) was expressed at a significantly higher level in AD patients than in healthy volunteers. A full-length cDNA was identified that encoded a human suppressor of cytokine signaling (SOCS) protein, HSOCP-1, also named hASB-8. The expression of HSOCP-1 was increased in cultured peripheral blood eosinophils after IL-4 stimulation, and overexpression of HSOCP-1 caused cell death in an eosinophil cell line, AML14.3D10. p34(SEI-1) was identified as a HSOCP-1-interacting protein by a yeast two-hybrid system. It is a protein that also interacts with the cyclin-dependent kinase inhibitor p16(INK4), suggesting that HSOCP-1 is involved in cell cycle control and apoptosis.

Eosinophils and atopic dermatitis

In spite of the progress regarding the description of immunological phenomena associated with atopic dermatitis (AD), the pathogenesis of this disease still remains unclear. The presence of eosinophils in the inflammatory infiltrate of AD has long been established. Eosinophil numbers as well as eosinophil granule protein levels in peripheral blood are elevated in most AD patients and appear to correlate with disease activity. Moreover, eosinophil granule proteins, which possess cytotoxic activity, are deposited in the skin lesions. These observations indicate a role of eosinophils in the pathogenesis of AD. Furthermore, AD is associated with increased production of T helper 2 cytokines including interleukin (IL)-5, which specifically acts on eosinophils, resulting in accelerated eosinophilopoiesis, chemotaxis, cell activation, and delayed apoptosis. Therefore, IL-5 is an interesting target for experimental therapy in this inflammatory disorder of the skin. Such studies might result in new insights into the pathogenetic role of eosinophils in AD.