Decreased expression of the aryl hydrocarbon receptor in ocular Behcet's disease

JAK-STAT Signaling Pathway in Non-Infectious Uveitis

Non-infectious uveitis (NIU) refers to various intraocular inflammatory disorders responsible for severe visual loss. Cytokines participate in the regulation of ocular homeostasis and NIU pathological processes. Cytokine receptors transmit signals by activating Janus kinase (JAK) and signal transducer and activator of transcription (STAT) proteins. Increasing evidence from human NIU and experimental models reveals the involvement of the JAK-STAT signaling pathway in NIU pathogenesis. Several small-molecule drugs that potentially inhibit multiple cytokine-dependent pathways are under investigation for treating autoimmune diseases, implicating possible applications for NIU treatment. This review summarizes the current understanding of the diverse roles of the JAK-STAT signaling pathway in ocular homeostasis and NIU pathology, providing a rationale for targeting JAKs and STATs for NIU treatment. Moreover, available evidence for the safety and efficacy of JAK inhibitors for refractory uveitis and potential approaches for treatment optimization are discussed.

More than Meets the Eye: The Aryl Hydrocarbon Receptor is an Environmental Sensor, Physiological Regulator and a Therapeutic Target in Ocular Disease

The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor originally identified as an environmental sensor of xenobiotic chemicals. However, studies have revealed that the AHR regulates crucial aspects of cell growth and metabolism, development and the immune system. The importance of the AHR and AHR signaling in eye development, toxicology and disease is now being uncovered. The AHR is expressed in many ocular tissues including the retina, choroid, cornea and the orbit. A significant role for the AHR in age-related macular degeneration (AMD), autoimmune uveitis, and other ocular diseases has been identified. Ligands for the AHR are structurally diverse organic molecules from exogenous and endogenous sources. Natural AHR ligands include metabolites of tryptophan and byproducts of the microbiome. Xenobiotic AHR ligands include persistent environmental pollutants such as dioxins, benzo (a) pyrene [B (a) P] and polychlorinated biphenyls (PCBs). Pharmaceutical agents including the proton pump inhibitors, esomeprazole and lansoprazole, and the immunosuppressive drug, leflunomide, activate the AHR. In this review, we highlight the role of the AHR in the eye and discuss how AHR signaling is involved in responding to endogenous and environmental stimuli. We also present the emerging concept that the AHR is a promising therapeutic target for eye disease.

2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin potential impacts on peripheral blood mononuclear cells of endometriosis women

Endometriosis happens following the implantation of endometrial-derived tissues outside the uterine cavity. It has been suggested that 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) is involved in endometriosis development. Furthermore, aryl hydrocarbon receptor (AHR), as a TCDD receptor, has been demonstrated to regulate immune responses. Nonetheless, data regarding the mechanisms, through which TCDD influences the immune system in endometriosis, are still inconclusive. Therefore, frequency of regulatory T cells (Tregs) and the expression of FOXP3, AHR and indoleamine 2, 3-dioxygenase 1 (IDO1) from endometriosis and non-endometriosis individuals were investigated in the absence and presence of TCDD; also, the concentration of IL-6 and kynurenine in the supernatant of cultures was assessed. The impact of TCDD-treated PBMCs on the migration capacity of menstrual blood-derived stromal stem cells (MenSCs) and monocyte chemoattractant protein-1 (MCP-1) and IL-6 production was determined. Here, we found that AHR and IDO1 expression levels were lower in endometriosis PBMCs; however, TCDD treatment increased AHR, FOXP3, IDO1, IL-6, and Treg levels in the endometriosis group (P ≤ 0.05-0.0001). TCDD-treated PBMCs increased the migration capacity of MenSCs and up-regulated MCP-1 and IL-6 levels in the PBMCs/MenSCs co-culture (P ≤ 0.01-0.0001). In conclusion, these results shed light on the probable mechanisms, through which AHR activation by chemical toxicants can impact inflammatory immune mediators involved in the development of endometriosis; also, these data support the idea that TCDD could promote endometriosis progression.

Analysis of Nuclear Receptor Coactivator 5 (NCOA5) Messenger RNA Expression and rs2903908 Single Nucleotide Polymorphism of NCOA5 in an Egyptian Cohort with Behçet's Disease: A Single-Center Case-control Study

The nuclear receptor coactivator 5 (NCOA5) has been linked to several inflammatory disorders, including Behçet's disease (BD). We evaluated the expression of NCOA5 messenger RNA (mRNA) using real-time reverse transcription-polymerase chain reaction, and analyzed the rs2903908 T > C of NCOA5 using TaqMan allelic discrimination assay in 49 Egyptian BD patients and 50 controls. The NCOA5 mRNA levels were higher in patients compared to controls (p = .02), female patients compared to males (p = .037), and in patients with ocular involvement (p = .049). Non-CC genotype carriers had a higher frequency of articular manifestations compared with CC carriers (p = .047). Genotypes CC + CT were associated with reduced risk of cutaneous involvement (OR = 0.27, p = .04). CC carriers with active BD or cutaneous manifestations displayed significantly lower NCOA5 mRNA expression than TT carriers. Our results demonstrate that NCOA5 is linked to BD clinical findings and activity.

Aryl hydrocarbon receptor deficiency causes the development of chronic obstructive pulmonary disease through the integration of multiple pathogenic mechanisms

Emphysema, a component of chronic obstructive pulmonary disease (COPD), is characterized by irreversible alveolar destruction that results in a progressive decline in lung function. This alveolar destruction is caused by cigarette smoke, the most important risk factor for COPD. Only 15%-20% of smokers develop COPD, suggesting that unknown factors contribute to disease pathogenesis. We postulate that the aryl hydrocarbon receptor (AHR), a receptor/transcription factor highly expressed in the lungs, may be a new susceptibility factor whose expression protects against COPD. Here, we report that Ahr-deficient mice chronically exposed to cigarette smoke develop airspace enlargement concomitant with a decline in lung function. Chronic cigarette smoke exposure also increased cleaved caspase-3, lowered SOD2 expression, and altered MMP9 and TIMP-1 levels in Ahr-deficient mice. We also show that people with COPD have reduced expression of pulmonary and systemic AHR, with systemic AHR mRNA levels positively correlating with lung function. Systemic AHR was also lower in never-smokers with COPD. Thus, AHR expression protects against the development of COPD by controlling interrelated mechanisms involved in the pathogenesis of this disease. This study identifies the AHR as a new, central player in the homeostatic maintenance of lung health, providing a foundation for the AHR as a novel therapeutic target and/or predictive biomarker in chronic lung disease.

The Aryl Hydrocarbon Receptor: A Mediator and Potential Therapeutic Target for Ocular and Non-Ocular Neurodegenerative Diseases

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, which senses environmental, dietary or metabolic signals to mount a transcriptional response, vital in health and disease. As environmental stimuli and metabolic products have been shown to impact the central nervous system (CNS), a burgeoning area of research has been on the role of the AHR in ocular and non-ocular neurodegenerative diseases. Herein, we summarize our current knowledge, of AHR-controlled cellular processes and their impact on regulating pathobiology of select ocular and neurodegenerative diseases. We catalogue animal models generated to study the role of the AHR in tissue homeostasis and disease pathogenesis. Finally, we discuss the potential of targeting the AHR pathway as a therapeutic strategy, in the context of the maladies of the eye and brain.

Therapeutic potential of aryl hydrocarbon receptor in autoimmunity

Aryl hydrocarbon receptor (AhR), a type of transcriptional factor, is widely expressed in immune cells. The activation of AhR signaling pathway depends on its ligands, which exist in environment and can also be produced by metabolism. Normal expressions of AhR and AhR-mediated signaling may be essential for immune responses, and effects of AhR signaling on the development and function of innate and adaptive immune cells have also been revealed in previous studies. Recent studies also indicate that aberrant AhR signaling may be related to autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), autoimmune uveitis (AU), autoimmune diabetes, Behcet's disease (BD) and myasthenia gravis (MG). Moreover, administration of AhR ligands or drugs has been proven effective for improving pathological outcomes in some autoimmune diseases or models. In this review, we summarize the effects of AhR on several innate and adaptive immune cells associated with autoimmunity, and the mechanism on how AhR participates in autoimmune diseases. In addition, we also discuss therapeutic potential and application prospect of AhR in autoimmune diseases, so as to provide valuable information for exploring novel and effective approaches to autoimmune disease treatments.

Chemistry and Properties of Indolocarbazoles

The indolocarbazoles are an important class of nitrogen heterocycles which has evolved significantly in recent years, with numerous studies focusing on their diverse biological effects, or targeting new materials with potential applications in organic electronics. This review aims at providing a broad survey of the chemistry and properties of indolocarbazoles from an interdisciplinary point of view, with particular emphasis on practical synthetic aspects, as well as certain topics which have not been previously accounted for in detail, such as the occurrence, formation, biological activities, and metabolism of indolo[3,2- b]carbazoles. The literature of the past decade forms the basis of the text, which is further supplemented with older key references.

Aryl Hydrocarbon Receptor Regulates Apoptosis and Inflammation in a Murine Model of Experimental Autoimmune Uveitis

Uveitis is characterized as a common cause of blindness worldwide. Aryl hydrocarbon receptor (AhR), a ligand-activated nuclear receptor, has been implicated to play a role in human uveitis, although the exact mechanisms remain poorly understood. The purpose of this study was to enhance our knowledge concerning the role of AhR during intraocular inflammation. We immunized wild-type and AhR-knockout C57BL/6J mice with IRBP_651–670 to induce experimental autoimmune uveitis (EAU). Disease severity was evaluated with both clinical and histopathological grading. Blood–retinal barrier (BRB) integrity was tested by Evans blue and tight junction proteins qualifications. Apoptosis was measured using TdT-mediated dUTP nick end labeling staining. Macrophage/microglia activation and polarization were studied by immunofluorescence and Western blot. Following EAU induction, AhR^−/− mice had more severe clinical and histopathological manifestations of uveitis than AhR^+/+ mice. Increased vascular permeability and apoptotic cells were observed in AhR^−/− EAU mice when compared with AhR^+/+ EAU mice. In addition, AhR^−/− EAU mice showed evidence of a significantly increased macrophage/microglia cells and a stronger polarization from the M2 to the M1 phenotype as compared to AhR^+/+ EAU mice. The levels of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β were increased in AhR^−/− EAU mice, which was associated with the activation of NF-κB and signal transducers and activators of transcription (STAT) pathways. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an agonist of AhR, caused a significant decrease in the clinical and histopathological manifestations, preserved BRB integrity, reduced apoptotic cells, inhibited macrophage/microglia activation, and shifted their polarization from M1 toward M2. Moreover, decreased expression of pro-inflammatory cytokines including TNF-α, IL-6, and IL-1β and inhibition of NF-κB and STAT pathways were found in EAU mice following TCDD treatment. In conclusion, AhR activation with TCDD exhibits an immunomodulatory effect by reducing BRB breakdown, inhibiting retinal cell apoptosis, and reducing pro-inflammatory cytokine expression during EAU. The underlying mechanism may involve the modulation of macrophages/microglia polarization and the downregulation of NF-κB and STAT pathways.

Concurrent presence of buccal mucosal and ophthalmologic lesions in Behcet's syndrome

BACKGROUND

Behcet's syndrome is a disease with different aspects in its clinical manifestations. The purpose of this study was to evaluate the simultaneous presence of oral mucosal and ophthalmologic lesions in patients with Behcet's syndrome.

METHODS

From April 2012 to December 2014, 50 cases of Behcet's syndrome who referred to the Departments of Ophtalmology, Oral Diseases and Infectious Diseases of Babol University Medical Sciences were entered into the study. The diagnosis of the disease was performed using the Iranian criteria for the diagnosis of Behcet's syndrome. The demographic findings as well as clinical manifestations were recorded.

RESULTS

Thirt-six (72%) were males and 14 (28%) were females. The mean age of the patients was 35.6±9 years. Oral aphthous (94%), ocular lesion (76%) and genital ulcers (70%) were the most clinical findings. The clinical onset of the disease in 43 (86%) was oral lesions and in 5 (10%) was ocular lesions. Among the forty-eight cases with oral lesions, 77% had ocular lesions concurrently. HLA-B5 was positive in 35 (70%) cases. Ocular lesion was seen in 33 of 35 (91.4%) cases versus 6 of 15 (40%) with HLA-B5 positive and negative cases, respectively (p<0.05). Oral lesion was seen in 94.3% cases with positive HLA-B5 and in 100% cases with negative HLA-B5 (p>0.05).

CONCLUSIONS

The results show that concurrent ophthalmic and oral lesions in Behcet's syndrome are relatively high. HLA-B5 positive cases are associated with more ophthalmologic lesions.

Increased expression of the aryl hydrocarbon receptor in allergic nasal mucosa, contributing to chemokine secretion in nasal epithelium

BACKGROUND

Pollutants produced by industrial and traffic-related activities have been linked to allergic responses. These noxious agents induce their effects through the aryl hydrocarbon receptor (AhR).

OBJECTIVE

We analyzed the expression and distribution pattern of AhR in normal and allergic nasal mucosa, and cytokine-driven regulation of its expression. The production levels of chemokine in cultured nasal epithelial cells were evaluated after stimulation with AhR ligand.

METHODS

The expression levels and distribution pattern of AhR in normal, mild, and moderate-severe persistent allergic nasal mucosa were assessed by using real-time polymerase chain reaction, Western blot, and immunohistochemistry. The expression levels of AhR were determined in cultured nasal epithelial cells treated with T-helper 2 cytokines. In cultured epithelial cells stimulated with 2-(10H-indole-30-carbonyl)-thiazole-4-carboxylic acid methyl ester, the expression levels of granulocyte macrophage colony-stimulating factor, thymus and activation regulated chemokine, macrophage inflammatory protein 1 α, monocyte chemotactic protein 1, regulated on activation normal T-cell expressed and secreted, eotaxin, and interleukin 8 were measured with real-time polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Expression of AhR was observed in normal and allergic nasal mucosa where it is distributed in the epithelial layer, submucosal glands, endothelial cells, and inflammatory cells. Its expression levels are increased in allergic nasal mucosa and upregulated after stimulation with T-helper 2 cytokines. The stimulation with 2-(10H-indole-30-carbonyl)-thiazole-4-carboxylic acid methyl ester resulted in increased production of chemokines in cultured epithelial cells.

CONCLUSION

Analysis of the study results indicated that increased expression levels of AhR may play a role in the pathogenesis of allergic rhinitis, which contributes to chemokine production in nasal mucosa.