HSD11B1 overexpression in dendritic cells and stromal cells relates to endometriosis by inhibiting dendritic cell proliferation and maturation

AIMS

This study aims to explore the alterations of dendritic cells (DCs) subpopulations in ectopic endometrial lesions and unveil the underlying mechanisms.

MATERIALS AND METHODS

Patients with endometriosis (n = 81) and women without endometriosis (n = 19) were recruited in this study. Dendritic cells (DCs) in the endometrial samples were counted after immunohistochemistry staining. The proportion of myeloid DCs and plasmacytoid DCs was calculated by flow cytometry. Primary DCs were isolated from tissues, and the cell viability and apoptosis were examined by MTT assay and flow cytometry. Cytokines were detected by the enzyme-linked immunosorbent assay. Differentially expressed genes were filtered by analyzing two datasets that were downloaded from GEO database and detected by RT-qPCR in tissues and isolated DCs. The function of HSD11B1 was examined in an endometrial stromal cell-DCs co-culture system and in vitro cultured DCs.

RESULTS

Reduced myeloid DCs and increased CD11c-CD304-DCs were found in ectopic endometrium compared to control endometrium and eutopic endometrium from endometriosis patients. Myeloid DCs isolated from ectopic endometrium expressed less CD80, CD83, CD86 and had reduced proliferation, increased apoptosis, and reduced cytokine production. The expression of HSD11B1 was significantly increased in both ectopic endometrium and isolated myeloid DCs. Overexpression of HSD11B1 in immature DCs could repress DCs maturation and cytokine production. Endometrial stromal cells overexpressing HSD11B1 secreted increased cortisol, which repressed DCs maturation.

CONCLUSIONS

HSD11B1 is upregulated in ectopic endometrial lesions, which may contribute to endometriosis through repressing myeloid DCs maturation.

IL-10 and TGF-β, but Not IL-17A or IFN-γ, Potentiate the IL-15-Induced Proliferation of Human T Cells: Association with a Decrease in the Expression of β2m-Free HLA Class I Molecules Induced by IL-15

IL-15 is a homeostatic cytokine for human T and NK cells. However, whether other cytokines influence the effect of IL-15 is not known. We studied the impact that IL-10, TGF-β, IL-17A, and IFN-γ have on the IL-15-induced proliferation of human T cells and the expression of HLA class I (HLA-I) molecules. Peripheral blood lymphocytes (PBLs) were labeled with CFSE and stimulated for 12 days with IL-15 in the absence or presence of the other cytokines. The proportion of proliferating T cells and the expression of cell surface HLA-I molecules were analyzed using flow cytometry. The IL-15-induced proliferation of T cells was paralleled by an increase in the expression of HC-10-reactive HLA-I molecules, namely on T cells that underwent ≥5-6 cycles of cell division. It is noteworthy that the IL-15-induced proliferation of T cells was potentiated by IL-10 and TGF-β but not by IL-17 or IFN-γ and was associated with a decrease in the expression of HC-10-reactive molecules. The cytokines IL-10 and TGF-β potentiate the proliferative capacity that IL-15 has on human T cells in vitro, an effect that is associated with a reduction in the amount of HC-10 reactive HLA class I molecules induced by IL-15.

The Roles of Skin Langerhans Cells in Immune Tolerance and Cancer Immunity

Langerhans cells (LC) are a unique population of tissue-resident macrophages with dendritic cell (DC) functionality that form a network of cells across the epidermis of the skin. Their location at the skin barrier suggests an important role for LC as immune sentinels at the skin surface. The classification of LC as DC over the past few decades has driven the scientific community to extensively study how LC function as DC-like cells that prime T cell immunity. However, LC are a unique type of tissue-resident macrophages, and recent evidence also supports an immunoregulatory role of LC at steady state and during specific inflammatory conditions, highlighting the impact of cutaneous environment in shaping LC functionality. In this mini review, we discuss the recent literature on the immune tolerance function of LC in homeostasis and disease conditions, including malignant transformation and progression; as well as LC functional plasticity for adaption to microenvironmental cues and the potential connection between LC population heterogeneity and functional diversity. Future investigation into the molecular mechanisms that LC use to integrate different microenvironment cues and adapt immunological responses for controlling LC functional plasticity is needed for future breakthroughs in tumor immunology, vaccine development, and treatments for inflammatory skin diseases.

Immunomodulatory Role of Neuropeptides in the Cornea

The transparency of the cornea along with its dense sensory innervation and resident leukocyte populations make it an ideal tissue to study interactions between the nervous and immune systems. The cornea is the most densely innervated tissue of the body and possesses both immune and vascular privilege, in part due to its unique repertoire of resident immune cells. Corneal nerves produce various neuropeptides that have a wide range of functions on immune cells. As research in this area expands, further insights are made into the role of neuropeptides and their immunomodulatory functions in the healthy and diseased cornea. Much remains to be known regarding the details of neuropeptide signaling and how it contributes to pathophysiology, which is likely due to complex interactions among neuropeptides, receptor isoform-specific signaling events, and the inflammatory microenvironment in disease. However, progress in this area has led to an increase in studies that have begun modulating neuropeptide activity for the treatment of corneal diseases with promising results, necessitating the need for a comprehensive review of the literature. This review focuses on the role of neuropeptides in maintaining the homeostasis of the ocular surface, alterations in disease settings, and the possible therapeutic potential of targeting these systems.

The impact of perceived stress on the hair follicle: Towards solving a psychoneuroendocrine and neuroimmunological puzzle

While popular belief harbors little doubt that perceived stress can cause hair loss and premature graying, the scientific evidence for this is arguably much thinner. Here, we investigate whether these phenomena are real, and show that the cyclic growth and pigmentation of the hair follicle (HF) provides a tractable model system for dissecting how perceived stress modulates aspects of human physiology. Local production of stress-associated neurohormones and neurotrophins coalesces with neurotransmitters and neuropeptides released from HF-associated sensory and autonomic nerve endings, forming a complex local stress-response system that regulates perifollicular neurogenic inflammation, interacts with the HF microbiome and controls mitochondrial function. This local system integrates into the central stress response systems, allowing the study of systemic stress responses affecting organ function by quantifying stress mediator content of hair. Focusing on selected mediators in this "brain-HF axis" under stress conditions, we distill general principles of HF dysfunction induced by perceived stress.

Corneal Endothelial Cell Loss in Glaucoma and Glaucoma Surgery and the Utility of Management with Descemet Membrane Endothelial Keratoplasty (DMEK)

The corneal endothelium has a crucial role in maintaining a clear and healthy cornea. Corneal endothelial cell loss occurs naturally with age; however, a diagnosis of glaucoma and surgical intervention for glaucoma can exacerbate a decline in cell number and impairment in morphology. In glaucoma, the mechanisms for this are not well understood and this accelerated cell loss can result in corneal decompensation. Given the high prevalence of glaucoma worldwide, this review aims to explore the abnormalities observed in the corneal endothelium in differing glaucoma phenotypes and glaucoma therapies (medical or surgical including with new generation microinvasive glaucoma surgeries). Descemet membrane endothelial keratoplasty (DMEK) is increasingly being used to manage corneal endothelial failure for glaucoma patients and we aim to review the recent literature evaluating the use of this technique in this clinical scenario.

Kinetics of hydrocortisone sodium phosphate penetration into the human aqueous humor after topical application

AIM OF THE STUDY

Hydrocortisone is a soft steroid with low anti-inflammatory properties and a short duration of action, used to manage several ocular conditions. The clinical benefits and side effects associated with hydrocortisone are well documented, but its basic pharmacokinetic in the eye is yet to be fully elucidated. The purpose of this study is to investigate the anterior chamber penetration capabilities of hydrocortisone when used in different concentrations as eye drops treatment.

MATERIALS AND METHODS

This is a double-blind, single-centre, randomised clinical trial performed at the Department of Medicine and Surgery of the University of Perugia (Italy) on consecutive patients who undergone phacoemulsification with intraocular lens implantation. Patients were randomly assigned on the morning of surgery to receive a single instillation of 0.33% (group A) or 0.001% (group B) hydrocortisone sodium phosphate solution. Group of patients C did not receive any treatment and was used to measure the hydrocortisone endogenous levels. Before surgery, one aliquot of aqueous humor for each patient was aspirated. The time of collection for each sample was recorded. Hydrocortisone concentrations were then stratified into six interval classes of 30 minutes each.

RESULTS

The mean concentration of hydrocortisone was significantly higher in group A (25.2 ± 12.4 ng/mL) compared with group B (7.11 ± 1.51 ng/mL) and compared with the mean hydrocortisone endogenous levels (3.92 ± 1.18 ng/mL) (P < .0001). No statistically significant differences of hydrocortisone mean concentrations between group B and the mean endogenous levels were found.

CONCLUSIONS

Considering the frequent need for prolonged topical steroid therapies and the possible consequent undesirable side effects, ophthalmologists should consider the lowest clinically effective dose of hydrocortisone useful to obtain the desired therapeutic effect and in an adequate time, to minimise the amount of steroids into the anterior chamber and to avoid side effects like intra-ocular pressure increase or cataract development.

Tolerogenic and immunogenic states of Langerhans cells are orchestrated by epidermal signals acting on a core maturation gene module

Langerhans cells (LCs), residing in the epidermis, are able to induce potent immunogenic responses and also to mediate immune tolerance. We propose that tolerogenic and immunogenic responses of LCs are directed by signaling from the epidermis and involve counter-acting gene circuits that are coupled to a core maturation gene module. We base our analysis on recent genetic and genomic findings facilitating the understanding of the molecular mechanisms controlling these divergent immune functions. Comparing gene regulatory network (GRN) analyses of various types of dendritic cells (DCs) including LCs we integrate signaling-dependent (TGFβ, EpCAM, β-Catenin) and transcription factor (IRF4, IRF1, NFκB) regulated gene circuits that appear to orchestrate the distinctive LC functional states. Our model proposes, that while epidermal signaling in the steady-state promotes LC tolerogenic function, the disruption of cell-cell contacts coupled with inflammatory signaling induces LC immunogenic programing. The conceptual framework emphasizes the sensing of discrete epidermal and inflammatory cues by resident LCs in dictating their genomic programing and cell state dynamics.

Developmental characteristics of the cytokine profile in aqueous humor and its relationship with the inflammatory response in children

Background

Although influencing the severity of postoperative intraocular inflammation of congenital cataract, the developmental characteristics of cytokine profile in the aqueous humor during childhood had not been described. And its relationship with the inflammatory response after intraocular surgery remained unsolved.

Methods

Preoperative aqueous humor samples were collected from 65 eyes of congenital cataract patients (CC group) and 13 eyes of age-related cataract patients (ARC group) from January 2015 to May 2017. The concentrations of 22 cytokines were measured. Differences in concentrations between the CC and ARC groups were described. Correlation analysis, least absolute shrinkage and selection operator (LASSO) and multivariate linear regression were then used to investigate the dynamic changes in the cytokine profile with age and their relationships with the postoperative inflammatory response.

Results

The concentrations of granulocyte colony stimulating factor (G-CSF), interferon (IFN)-α2, interleukin (IL)-1α and IL-7 were higher in the CC group than in the ARC group, while the concentrations of epidermal growth factor (EGF), granulocyte-macrophage colony stimulating factor (GM-CSF), IL-10, IL-12p70, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, and tumor necrosis factor (TNF)-α were more abundant in the ARC group (P<0.05). Within the CC group, the concentrations of EGF and IL-3 were positively correlated with age, while negative correlations were observed for monocyte chemotactic protein-1 (MCP-1) and IL-8 (P<0.05). Further multivariate analysis revealed that age was an independent associated factor of MCP-1 (β=−0.337, P<0.001). IL-3 (β=−0.490, P=0.006) and EGF (β=−0.415, P=0.044) were significantly correlated with the postoperative inflammatory response [evaluation of posterior capsule opacification (EPCO)] at 3 and 12 months after surgery, respectively.

Conclusions

This study demonstrated the dynamic change in the cytokine profile of the aqueous humor in children and its relationship with the postoperative inflammatory response. These findings can serve as the foundation for further investigation into the mechanisms that underlie the early development of intraocular immunology.

An immune response to the avascular lens following wounding of the cornea involves ciliary zonule fibrils

The lens and central cornea are avascular. It was assumed that the adult lens had no source of immune cells and that the basement membrane capsule surrounding the lens was a barrier to immune cell migration. Yet, microfibril‐associated protein‐1 (MAGP1)‐rich ciliary zonules that originate from the vasculature‐rich ciliary body and extend along the surface of the lens capsule, form a potential conduit for immune cells to the lens. In response to cornea debridement wounding, we find increased expression of MAGP1 throughout the central corneal stroma. The immune cells that populate this typically avascular region after wounding closely associate with this MAGP1‐rich matrix. These results suggest that MAGP1‐rich microfibrils support immune cell migration post‐injury. Using this cornea wound model, we investigated whether there is an immune response to the lens following cornea injury involving the lens‐associated MAGP1‐rich ciliary zonules. Our results provide the first evidence that following corneal wounding immune cells are activated to travel along zonule fibers that extend anteriorly along the equatorial surface of the lens, from where they migrate across the anterior lens capsule. These results demonstrate that lens‐associated ciliary zonules are directly involved in the lens immune response and suggest the ciliary body as a source of immune cells to the avascular lens.

I-alowCD11bhigh DC Regulates the Immune Response in the Eyes of Experimental Autoimmune Uveitis

Regulatory dendritic cells (DC_reg) have been reported to be a negative regulator in the immune response. These cells are widely distributed in the liver, spleen, and lung. However, the status and function of DC_reg in the eyes and disease are still not very clear. Herein, we found that the number of I-a^lowCD11b^high DC increased in the eye and spleen at the recovery stage of experimental autoimmune uveitis (EAU), which is a mouse model for autoimmune uveitis. These cells expressed lower levels of CD80, CD86, and CD54 than the mature DCs and expressed interleukin 10 (IL-10), indoleamine 2,3-dioxygenase (IDO), and transforming growth factor beta (TGF-β) as well. Moreover, these DC_reg can regulate the development of EAU by promoting CD4⁺CD25⁺Foxp3⁺ regulatory T cells. The increased interferon-gamma (IFN-γ) in the aqueous humor of EAU participates in inducing DC_reg to alleviate the symptom of EAU. Furthermore, DC_reg was found to exist in the eyes of normal mice. Aqueous humor, containing a certain concentration of IL-10, TGF-β, prostaglandin E2 (PGE2), IDO, and nitric oxide (NO), induced the tolerance of DC_reg in normal eyes. It can be concluded that DC_reg exists in the eyes and plays a protective role in inflamed eyes. These DC_reg induced by IFN-γ might be used as a strategy to develop therapy for EAU management.

Evaluation of thrombospondin-1 gene polymorphisms in corneal allograft rejection in Asian Indian patients

Purpose:

To evaluate the frequency and the association of Thrombospondin 1 (THBS1) gene single nucleotide polymorphisms (SNPs) in Asian Indian patients with optical full thickness corneal grafting surgery.

Methods:

Prospective case–control analysis of optical penetrating keratoplasty patients with and without immune rejection and controls for genotyping of 3 THBS1 gene SNPs (rs1478604 A>G; rs2228261 C>T; rs2228262 A>G) by Amplification Refractory Mutation System-Polymerase Chain Reaction (ARMS PCR).

Results:

Among 58 patients [45 with immune allograft rejection (DNA isolation was possible in 38 samples) and 13 without immune corneal allograft rejection] and 65 controls, allele frequencies observed for rs1478604 (A>G) are A: 69.7% and 72.6%, G: 30.2% and 27.3%; for rs2228261 (C>T) are T: 70.2% and 62.3%, C: 29.7% and 37.6%; and for rs2228262 (A>G) A: 97.4% and 98.4%; G 2.5% and 1.5% respectively. Genotype frequencies were rs1478604 (A>G) AA: 57.8% and 59.3%, AG 23.6% and 26.5%; GG 18.4% and 14%; for rs2228261 (C>T) TT: 40.5% and 33.8%, TC: 59% and 56.9%, CC: 0% and 9.2%; for rs2228262 (A>G) AA: 94.8% and 96.8%, AG: 5.1% and 3.1% in rejection and controls respectively. The allele and genotype frequency for the 3 described THSB1 SNPs did not show any difference between the corneal graft immune rejection patients and controls.

Conclusion:

Asian Indian population evaluated for THBS1 gene SNPs by ARMS PCR genotyping in Asian Indian population did not show any genetic association to immune rejection occurrence in our study.

Novel gene targets for miRNA146a and miRNA155 in anterior uveitis

BACKGROUND/AIMS

Anterior uveitis (AU) is the most common form of intraocular inflammation. MicroRNAs (miRNA) are small, non-coding RNAs functioning as post-transcriptional repressors of gene expression. Knowledge of miRNAs can implicate specific genes and pathogenic signalling pathways in disease. This study examines miRNA expression, function and target genes in AU pathogenesis.

METHODS

AU and healthy control (HC) peripheral blood mononuclear cells (PBMC) were initially screened for expression of five miRNAs by real-time PCR. Regulation of the aberrantly expressed miRNAs by TLR1/2, TLR3, TLR4, IL1β and TNFα was quantified by real-time PCR and paired cytokine outputs measured by ELISA. Functional effects of miRNA overexpression using transfected THP1 cells examined IL6, IL8, IL10 and IL1β cytokine outputs by ELISA. Target genes were identified using TargetScan online computational algorithm and relevant targets verified by cloning of the 3'UTR and luciferase reporter gene assays.

RESULTS

Increased expression of miRNA146a (p<0.01), miRNA155 (p<0.05) and miRNA125a5p (p<0.01) was demonstrated in AU PBMC compared with HC. miRNA155 was increased following TLR1/2 (p<0.05) and TLR4 (p<0.05) stimulation and miRNA146a increased in response to IL1β (p<0.05). In a proinflammatory environment, miRNA155 overexpression in THP1 cells yielded increased cytokine output whereas miRNA146a overexpression showed decreased cytokine output. CD80, PRKCE and VASN were confirmed as novel targets for miRNA146a and SMAD2, TYRP1 and FBXO22 for miRNA155.

CONCLUSION

This study identifies overexpression of proinflammatory miRNA155, regulatory miRNA146a and miRNA125a-5p in AU. CD80, PRKCE and VASN are novel miRNA146a targets and SMAD2, TYRP1 and FBXO22 are novel targets for miRNA155.

The role of TGF-beta signaling in dendritic cell tolerance

Transforming growth factor beta (TGF-β) is a pleiotropic cytokine present in vertebrate and invertebrate organisms that functions in numerous physiological and pathological processes. TGF-β impacts all the cells of the immune system, and of the three known TGF-β isoforms, TGF-β1 is the predominant isoform expressed in immune cells. TGF-β1 is known to play a pivotal role in the function of all immune cells especially in the regulation of T cell development and in the induction of immunological tolerance in dendritic cells (DCs). Based on the importance of DCs in regulation of the innate and adaptive arms of the immune system, in this review we explore the regulatory functions of TGF-β required for establishment and maintenance of DC-mediated immune tolerance.

TGF-β induces phosphorylation of phosphatase and tensin homolog: implications for fibrosis of the trabecular meshwork tissue in glaucoma

Fundamental cell signaling mechanisms that regulate dynamic remodeling of the extracellular matrix (ECM) in mechanically loaded tissues are not yet clearly understood. Trabecular meshwork (TM) tissue in the eye is under constant mechanical stress and continuous remodeling of ECM is crucial to maintain normal aqueous humor drainage and intraocular pressure (IOP). However, excessive ECM remodeling can cause fibrosis of the TM as in primary open-angle glaucoma (POAG) patients, and is characterized by increased resistance to aqueous humor drainage, elevated IOP, optic nerve degeneration and blindness. Increased levels of active transforming growth factor-β2 (TGF-β2) in the aqueous humor is the main cause of fibrosis of TM in POAG patients. Herein, we report a novel finding that, in TM cells, TGF-β-induced increase in collagen expression is associated with phosphorylation of phosphatase and tensin homolog (PTEN) at residues Ser380/Thr382/383. Exogenous overexpression of a mutated form of PTEN with enhanced phosphatase activity prevented the TGF-β-induced collagen expression by TM cells. We propose that rapid alteration of PTEN activity through changes in its phosphorylation status could uniquely regulate the continuous remodeling of ECM in the normal TM. Modulating PTEN activity may have high therapeutic potential to alleviating the fibrosis of TM in POAG patients.

c-Rel is Required for the Induction of pTregs in the Eye but Not in the Gut Mucosa

Regulatory T (Treg) cells play an integral role in maintaining immune homeostasis and preventing autoimmune diseases. Forkhead box P3 expression marks the commitment of progenitor cells to the Treg lineage. Although the essential function of the nuclear factor (NF)-κB family transcription factor c-Rel in the regulation of natural Treg cells has been firmly established, little is known about whether c-Rel is involved in the in vivo generation of peripheral Treg cells (pTregs), which develop from mature CD4+ conventional T cells outside of the thymus. We sought to answer this question through the induction of pTregs in the eye and gut mucosa using ovalbumin-specific T cell receptor transgenic mice that do or do not express c-Rel. Our results showed that Tregs can be induced in the eye in a c-Rel-dependent manner when immune-mediated inflammation occurs. However, c-Rel is dispensable for the induction of pTregs in the gut mucosa after oral antigen administration. Thus, c-Rel may play distinct roles in regulating the development of pTregs in different organs. Abbreviations ACAID: Anterior Chamber-Associated Immune Deviation; ATF: activating transcription factor; CREB: cAMP responsive element-binding protein; DMEM: Dulbecco minimum essential medium; HBSS: Hanks Balanced Salt Solution; NFAT: Nuclear Factor of Activated T cells; PBS: Phosphate-buffered saline; PE: Phycoerythrin; WT: wild type.

Therapeutic Use of Soluble Fas Ligand Ameliorates Acute and Recurrent Herpetic Stromal Keratitis in Mice

PURPOSE

The present study was designed to test the therapeutic value of soluble FasL (sFasL) in an acute model of herpetic stromal keratitis (HSK) and, more importantly, a recurrent model of HSK using BALB/c, BALB-lpr, and National Institutes of Health (NIH) mice.

METHODS

Mice were infected either acutely with the KOS strain of herpes simplex virus 1 (HSV-1) or latently with the McKrae strain of HSV-1. Acutely infected mice as well as ultraviolet-B (UV-B) reactivated mice (recurrent infection) were treated with sFasL, or soluble TNF-related apoptosis inducing ligand (sTRAIL), or BSA daily or 3 times/wk by using either a combination of subconjunctival injection and topical ointment, or with topical ointment alone. These mice then were evaluated for corneal opacity and neovascularization for 6 weeks.

RESULTS

Following acute and recurrent HSV-1 infection, wild-type BALB/c mice treated with sFasL displayed significantly reduced incidence of corneal opacity and neovascularization compared to the control animals. However, BALB-lpr mice, which are deficient in Fas+ inflammatory cells, displayed no such differences in ocular disease, as expected. Latently infected NIH mice treated with sFasL displayed similar results. Flow cytometric analysis revealed that the corneal inflammatory infiltrate in those treated with sFasL was significantly less than in sTRAIL- or BSA-treated mice. Furthermore, corneas from sFasL-treated mice displayed relatively more cells undergoing apoptosis.

CONCLUSIONS

This study provides evidence that sFasL treatment has potential therapeutic benefit in reducing inflammatory infiltrate and neovascularization in primary and recurrent forms of HSK, and that it does so by augmenting the restriction of Fas+ inflammatory cells mediated by membrane FasL.

Impaired Fas-Fas Ligand Interactions Result in Greater Recurrent Herpetic Stromal Keratitis in Mice

Herpes simplex virus-1 (HSV-1) infection of the cornea leads to a potentially blinding condition termed herpetic stromal keratitis (HSK). Clinical studies have indicated that disease is primarily associated with recurrent HSK following reactivation of a latent viral infection of the trigeminal ganglia. One of the key factors that limit inflammation of the cornea is the expression of Fas ligand (FasL). We demonstrate that infection of the cornea with HSV-1 results in increased functional expression of FasL and that mice expressing mutations in Fas (lpr) and FasL (gld) display increased recurrent HSK following reactivation compared to wild-type mice. Furthermore, both gld and lpr mice took longer to clear their corneas of infectious virus and the reactivation rate for these strains was significantly greater than that seen with wild-type mice. Collectively, these findings indicate that the interaction of Fas with FasL in the cornea restricts the development of recurrent HSK.

Role of dendritic cell subsets in immunity and their contribution to noninfectious uveitis

Dendritic cells (DCs) are a heterogeneous population. Murine DCs consist of conventional DCs (cDCs) and plasmacytoid DCs (pDCs). In humans, the analogous populations are myeloid DCs (mDCs) and pDCs. Though distinct in phenotypes and functions, studies have shown that these DC subsets may interact or "crosstalk" during immune responses. For example, cDCs may facilitate pDC maturation, and pDCs may enhance antigen presentation of cDCs in certain pathogenic conditions or even take on a cDC phenotype themselves. The role of DCs in noninfectious uveitis has been studied primarily in the experimental autoimmune uveitis mouse model and to a more limited extent in patients. Recent evidence shows that the number, phenotype, and function of DC subsets are altered in this disease. We provide an overview of selected recent developments of pDCs and cDCs/mDCs, with special attention to their interaction and the dual roles of DC subsets in noninfectious uveitis.

Levels of blood CD1c+ mDC1 and CD1chi mDC1 subpopulation reflect disease activity in noninfectious uveitis

PURPOSE

Myeloid dendritic cells (mDCs) play an important role in autoimmune diseases. However, the role of blood CD1c(+) myeloid dendritic cells 1 (mDC1s), the subset of human blood mDCs, is not well understood in noninfectious uveitis.

METHODS

Fresh peripheral blood samples from human noninfectious uveitis patients (n = 32) and healthy controls (HCs) (n = 64) were stained with FITC-Lineage 1 (Lin1), PERCP-HLADR, and PE-CD1c antibodies. The levels of mDC1 were quantified by using flow cytometric analysis. Longitudinal data from patients (n = 16) were analyzed to correlate the levels of mDC1 with disease activity.

RESULTS

Blood CD1c(+) mDC1 and its subpopulation, CD1c(hi) mDC1, were increased in uveitis patients compared with HCs. Longitudinal data demonstrated that both the CD1c(+) mDC1 and CD1c(hi) mDC1 subpopulation reflected a dynamic change in clinical uveitis activity: CD1c expression was increased in active uveitis but decreased when uveitis became inactive.

CONCLUSIONS

Given these observations, an alteration in blood CD1c(+) mDC1 and the CD1c(hi) mDC1 subpopulation could be a potential biomarker to monitor clinical uveitis activity within patients.

Pharmacotherapy for uveitis: current management and emerging therapy

Uveitis, a group of conditions characterized by intraocular inflammation, is a major cause of sight loss in the working population. Most uveitis seen in Western countries is noninfectious and appears to be autoimmune or autoinflammatory in nature, requiring treatment with immunosuppressive and/or anti-inflammatory drugs. In this educational review, we outline the ideal characteristics of drugs for uveitis and review the data to support the use of current and emerging therapies in this context. It is crucial that we continue to develop new therapies for use in uveitis that aim to suppress disease activity, prevent accumulation of damage, and preserve visual function for patients with the minimum possible side effects.

Autoimmune and autoinflammatory mechanisms in uveitis

The eye, as currently viewed, is neither immunologically ignorant nor sequestered from the systemic environment. The eye utilises distinct immunoregulatory mechanisms to preserve tissue and cellular function in the face of immune-mediated insult; clinically, inflammation following such an insult is termed uveitis. The intra-ocular inflammation in uveitis may be clinically obvious as a result of infection (e.g. toxoplasma, herpes), but in the main infection, if any, remains covert. We now recognise that healthy tissues including the retina have regulatory mechanisms imparted by control of myeloid cells through receptors (e.g. CD200R) and soluble inhibitory factors (e.g. alpha-MSH), regulation of the blood retinal barrier, and active immune surveillance. Once homoeostasis has been disrupted and inflammation ensues, the mechanisms to regulate inflammation, including T cell apoptosis, generation of T_reg cells, and myeloid cell suppression in situ, are less successful. Why inflammation becomes persistent remains unknown, but extrapolating from animal models, possibilities include differential trafficking of T cells from the retina, residency of CD8⁺ T cells, and alterations of myeloid cell phenotype and function. Translating lessons learned from animal models to humans has been helped by system biology approaches and informatics, which suggest that diseased animals and people share similar changes in T cell phenotypes and monocyte function to date. Together the data infer a possible cryptic infectious drive in uveitis that unlocks and drives persistent autoimmune responses, or promotes further innate immune responses. Thus there may be many mechanisms in common with those observed in autoinflammatory disorders.

Cortisol biosynthesis in the human ocular surface innate immune response

Innate immune responses have a critical role in regulating sight-threatening ocular surface (OcS) inflammation. While glucocorticoids (GCs) are frequently used to limit tissue damage, the role of intracrine GC (cortisol) bioavailability via 11-beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in OcS defense, remains unresolved. We found that primary human corneal epithelial cells (PHCEC), fibroblasts (PHKF) and allogeneic macrophages (M1, GM-CSF; M2, M-CSF) were capable of generating cortisol (M1>PHKF>M2>PHCEC) but in corneal cells, this was independent of Toll-like receptor (TLR) activation. While PolyI∶C induced maximal cytokine and chemokine production from both PHCEC (IFNγ, CCL2, CCL3, and (CCL4), IL6, CXCL10, CCL5, TNFα) and PHKF (CCL2, IL-6, CXCL10, CCL5), only PHKF cytokines were inhibited by GCs. Both Poly I∶C and LPS challenged-corneal cells induced M1 chemotaxis (greatest LPS-PHKF (250%), but down-regulated M1 11β-HSD1 activity (30 and 40% respectively). These data were supported by clinical studies demonstrating reduced human tear film cortisol∶cortisone ratios (a biomarker of local 11β-HSD1 activity) in pseudomonas keratitis (1∶2.9) versus healthy controls (1∶1.3; p<0.05). This contrasted with putative TLR3-mediated OcS disease (Stevens-Johnson Syndrome, Mucous membrane pemphigoid) where an increase in cortisol∶cortisone ratio was observed (113.8∶1; p<0.05). In summary, cortisol biosynthesis in human corneal cells is independent of TLR activation and is likely to afford immunoprotection under physiological conditions. Contribution to ocular mucosal innate responses is dependent on the aetiology of immunological challenge.

Quantification and comparison of baseline cortisol levels between aqueous and plasma from healthy anesthetized hound dogs utilizing mass spectrometry

OBJECTIVE

The purpose of this study is to quantify and compare the resting cortisol levels between aqueous (Aq) and plasma of anesthetized hound dogs utilizing mass spectrometry.

ANIMALS

Nine hound breed dogs weighing between 20.8 and 29.2 kg (x = 26.3 kg, SD ± 2.6 kg) were utilized from a previous project.

PROCEDURES

All dogs underwent two anesthesia sessions to harvest Aq from each eye respectively. A paired blood sample was taken immediately after aqueous centesis. The Aq and plasma were analyzed for cortisol levels using mass spectrometry. Correlation of cortisol levels in dog serum and ocular fluid was determined with Sigma Stat using Pearson's correlation analysis. The level of significance for correlation analysis was set at P < 0.05.

RESULTS

The plasma resting cortisol levels in the dog ranged from 3.59 to 89.35 nm (x = 31.68 nm, SD ± 28.53 nm), while the Aq cortisol levels ranged from 0.82 to 5.62 nm (x = 2.73 nm, SD ± 1.94 nm). The correlation of cortisol levels in Aq compared to plasma was significant (P = 0.008) with a correlation coefficient of r = 0.779. Based on these results, 61% (r = 0.779(2) ) of the variation in Aq cortisol levels is explained by the variations in plasma cortisol levels.

CONCLUSION AND CLINICAL RELEVANCE

This study identified significant levels of cortisol in the Aq of the canine eye and positively correlated them with plasma cortisol levels. The dog may offer a representative model for further studies to help clarify the overall role of cortisol in the anterior chamber.

Gene therapy for noninfectious uveitis

Noninfectious intraocular inflammatory disease remains a significant cause of visual loss, even with current systemic immunosuppression. Alternative novel treatments are thus required, particularly for severe forms of posterior uveitis. Encouraging results from several phase I/II clinical trials of gene therapy for monogenic retinal disorders have paved the way for the development of this approach for other ocular conditions. Gene therapy for uveitis offers the possibility of potent, self-regulating, long-term disease control following a single treatment and without systemic side effects. To date, gene therapy approaches using interleukin-10, interleukin-1 receptor antagonist, interferon-alpha, soluble TNF-alpha receptors, and alpha-MSH gene transfer have been used successfully to attenuate experimental animal models of uveitis. This review evaluates these preclinical studies, considers the route to clinical application, and explores future targets and approaches.

Aqueous humor suppression of dendritic cell function helps maintain immune regulation in the eye during human uveitis

PURPOSE

Noninfectious uveitis is characterized by a dysregulated inflammatory or immune response in the eye. It is unclear whether this represents a failure of immune privilege or an overwhelming inflammatory drive that has exceeded the capacity of regulatory mechanisms that are still functioning. The authors investigated immune regulation in the human eye during intraocular inflammation (uveitis) and its impact on dendritic cell (DC) function and subsequent T-cell responses.

METHODS

Myeloid DCs were isolated from the aqueous humor (AqH) and peripheral blood of patients with active uveitis and characterized by flow cytometry. The effect of uveitis AqH was interrogated in an in vitro model of peripheral blood monocyte-derived DCs from healthy controls.

RESULTS

Myeloid DCs isolated from uveitic AqH were characterized by elevated major histocompatibility complex classes I and II (MHC I/II), but reduced CD86 compared with matched peripheral blood DCs. Exposure of peripheral blood monocyte-derived DCs from healthy controls to the inflammatory AqH supernatant recapitulated this phenotype. Despite interferon gamma (IFNγ)-dependent upregulation of MHC I, inflammatory AqH was overall suppressive to DC function, with reduced CD86 expression and diminished T-cell responses. This suppressive effect was equal to or greater than that induced by noninflammatory AqH, but was glucocorticoid independent (in contrast to noninflammatory AqH).

CONCLUSIONS

These data indicate that the ocular microenvironment continues to regulate DC function during uveitis, despite IFNγ-driven upregulation of MHC expression, supporting the hypothesis that immune regulation within the eye is maintained during inflammation.

Mice with mutations in Fas and Fas ligand demonstrate increased herpetic stromal keratitis following corneal infection with HSV-1

HSV-1 infection of the cornea leads to a potentially blinding immunoinflammatory lesion of the cornea, termed herpetic stromal keratitis. It has also been shown that one of the factors limiting inflammation of the cornea is the presence of Fas ligand (FasL) on corneal epithelium and endothelium. In this study, the role played by FasL expression in the cornea following acute infection with HSV-1 was determined. Both BALB/c and C57BL/6 (B6) mice with HSV-1 infection were compared with their lpr and gld counterparts. Results indicated that mice bearing mutations in the Fas Ag (lpr) displayed the most severe disease, whereas the FasL-defective gld mouse displayed an intermediate phenotype. It was further demonstrated that increased disease was due to lack of Fas expression on bone marrow-derived cells. Of interest, although virus persisted slightly longer in the corneas of mice bearing lpr and gld mutations, the persistence of infectious virus in the trigeminal ganglia was the same for all strains infected. Further, B6 mice bearing lpr and gld mutations were also more resistant to virus-induced mortality than were wild-type B6 mice. Thus, neither disease nor mortality correlated with viral replication in these mice. Collectively, the findings indicate that the presence of FasL on the cornea restricts the entry of Fas(+) bone marrow-derived inflammatory cells and thus reduces the severity of HSK.

Immune tolerance and autoimmune uveoretinitis: the role of the ocular microenvironment

Two major self-antigens, S-antigen and interphotoreceptor retinoid-binding protein, which can induce uveoretinitis, exist in the eye. However, immunologic tolerance to these self-antigens is generated and maintained. Two major mechanisms have been demonstrated by which tolerance to tissue-specific self-antigens is maintained. One is central tolerance in the thymus where autoreactive T cells are deleted by medullary thymic epithelial cells expressing the autoimmune regulator gene (Aire) and the other is peripheral tolerance mediated by regulatory T cells such as Foxp3(+)CD25(+)CD4(+) T cells. In addition, the eye is an immune privileged site where indigenous immunomodulatory mechanisms allow immune protection of the eye in a manner that is largely devoid of immunogenic inflammation.