Comparative anatomy of nitrergic intrinsic choroidal neurons (ICN) in various avian species

Intrinsic choroidal neurons (ICN) represent a peculiar feature of eyes in higher primates and birds. They account for up to 2000 in human and duck eyes but are virtually absent or rare in all other mammalian species investigated so far. It has been suggested that ICN are involved in regulation of ocular blood supply, hence influencing intraocular pressure, and changes in choroidal thickness, thus influencing accommodation. The present study was undertaken in order to compare differences in various avian species with respect to ICN as well as to provide data on some avian species relevant for experimental ophthalmic research, i.e. chicken and quail. Choroids from 12 avian species were processed for NADPH-diaphorase histochemistry or, in some cases, neuronal nitric oxide synthase immunocytochemistry. ICN were quantified and normalized to mean choroidal area. Three choroids of each galliformes (i.e. chicken, quail, turkey) and anseriformes (i.e. Muscovy duck, Mallard duck, goose) were rastered in squares of 1 mm(2) and x/y coordinates were transferred into a 3D-diagram with the amount of ICN represented in the z-axis. ICN were detected in all species investigated. They were predominantly small cells with soma diameters of 20-30 mum. In turkey, and to a lesser amount in chicken, a subpopulation of ICN with somal diameters of up to 70 mum was observed. Highest mean cell counts were found in goose (6195(.)4; turkey 3558(.)4; chicken 1681(.)4; Muscovy duck 785(.)4; Mallard duck 640(.)8; quail 440(.)2). Normalized to choroidal area, highest mean cell counts were (per mm(2)): 12(.)62 in goose, 4(.)42 in both chicken and turkey, 2(.)86 in quail, 2(.)66 in Mallard duck and 1(.)89 in Muscovy duck. In galliformes, ICN were found to be accumulated temporo-cranial, while in anseriformes they were arranged in a more belt-like fashion, passing from cranio-nasal to temporo-caudal. Our results show that besides Muscovy duck, other avian species appear as suitable models for further functional experiments on ICN. The temporo-cranial accumulation of ICN in galliformes and the belt-like arrangement in anseriformes may reflect special functional requirements in regions of high visual acuity. (C) 2003 Elsevier Ltd. All rights reserved

Perceived Stress Levels in Adult Patients With Uveitis

Background: The aim of this study was to examine perceived stress levels in adult patients with uveitis. Patients and Methods: One hundred seventy-three adult consecutive uveitis patients (age range 18 to 85 years) were analyzed in a cross-sectional design for their perceived stress, according to the Perceived Stress Questionnaire (PSQ). Stress levels were classified into normal stress, moderate stress, and high stress. Results: In the majority of uveitis patients a normal stress level (82%) within the last 2 years was detected. In a subgroup analysis, perceived stress of the patients with active uveitis compared with patients with non-active uveitis was significantly higher within the last 2 years (n=80 active/n = 45 non-active; p = 0.005). Conclusions: Overall 18% of the uveitis patient had raised perceived stress, similar to the general population but patients with active uveitis were significantly more stressed. Therefore, consideration of stress levels may be important in the therapy of uveitis patients

Characterization of Antigen-Presenting Macrophages and Dendritic Cells in the Healthy Human Sclera

PURPOSE. The sclera is mainly made of collagen and fibroblasts. The aim of this study was to analyze whether immune cells are present in the healthy human sclera. METHODS. Ten human anterior episcleral or stromal tissue samples from globe donors were immunohistochemically examined using confocal microscopy. The expression of the macrophage markers CD68, CD163 and CD11b, CD45 (a general leukocyte marker), MHCII (expressed by antigen-presenting cells [APCs]), CD11c (dendritic cell marker), lymphatic endothelium hyaluronan receptor-1 (LYVE1; expressed on lymphatic endothelium and macrophage subsets), chemokine receptor 7 (CCR7, a homing receptor for leukocytes), CXCL12 (expressed by activated leukocytes), CCR2 (a marker for inflammatory monocytes), and glial fibrillary acidic protein (GFAP; expressed by astrocytes) was analyzed and quantified. RESULTS. In the episclera, a high number of cells (>= 40 cells/mm(2)) were immunoreactive for CD68, CD45, MHCII, CCR7, LYVE1, and CD11b. Lower numbers (<20 cells/mm(2)) were positive for CXCL12, CCR2, and GFAP. The episclera showed a significantly higher number of cells compared to the stroma (P = 0.008). MHCII+ cells could be double positive for CCR7, CD45, CD11c, or CD11b and seldom CXCL12. Macrophages were most likely from the M1 type (CD68+, CD163 -). CONCLUSIONS. The healthy human sclera contains several macrophage populations, which can function as APCs, with the highest density being present in the episclera. Most cells express macrophage markers and may function as APCs. The presence of these cells might indicate that scleral immune cells are important for maintaining physiological functions in the eye and may potentially contribute to blood vessel homeostasis

Is the human sclera a tendon-like tissue? A structural and functional comparison

Collagen rich connective tissues fulfill a variety of important functions throughout the human body, most of which having to resist mechanical challenges. This review aims to compare structural and functional aspects of tendons and sclera, two tissues with distinct location and function, but with striking similarities regarding their cellular content, their extracellular matrix and their low degree of vascularization. The description of these similarities meant to provide potential novel insight for both the fields of orthopedic research and ophthalmology. (c) 2021 Elsevier GmbH. All rights reserved

C, Cursiefen C: The normal human choroid is endowed with a significant number of lymphatic vessel endothelial hyaluronate receptor 1 (LYVE-1)-positive macrophages. Investigative Ophthalmology &amp; Visual Science 2008

PURPOSE. Lymphatic vessel endothelial hyaluronic acid receptor (LYVE-1) is a newly discovered lymphatic endothelium-specific marker that is also expressed by a subpopulation of macrophages. To date, there is no report on its expression in the posterior human uvea. The purpose of this study was to investigate the expression of LYVE-1 in normal human choroids. METHODS. Eyes of body/cornea donors (55-89 years of age; 4 -9 hours postmortem) were obtained. Choroids were dissected and prepared for cryosections followed by immunohistochemistry with anti-human LYVE-1 antiserum and immunogold labeling. In addition, anti-human antibodies against macrophage markers (CD68, MHC class II) and lymphatic (podoplanin) and blood vascular endothelium (CD31, vWF) were used. For documentation, light-, fluorescence-, confocal laser scanning-, and electron-microscopy were used. RESULTS. The normal human choroidal stroma contained 274 Ϯ 86 LYVE-1 positive cells/mm 2 . The cells displayed irregular shapes with a relatively uniform diameter of 32 m. Costaining with CD68 and negativity for CD31, podoplanin, and melan-A/ HMB45, as well as electron microscopic features, suggest these LYVE-1 ϩ cells to be macrophages. Besides that, no classic LYVE-1 ϩ /podoplanin ϩ lymphatic vessels were detected within the normal adult human choroid. CONCLUSIONS. The normal adult human choroid does not contain typical lymph vessels, but is endowed with a significant number of LYVE-1 positive macrophages. These cells may be involved in choroidal hyaluronic acid metabolism or contribute to temporary formation of lymphatic channels under inflammatory conditions. (Invest Ophthalmol Vis Sci. 2008;49: 5222-5229) DOI:10.1167/iovs.08-1721 L ymphangiogenesis research has been hampered for several decades due to lack of specific markers for lymphatic vessels. 6 Indeed, the normally avascular cornea has become a very useful model system for the study of mechanisms of lymphangiogenesis. 17 Also, data from existing electron microscopic studies in human tissue have not provided any data about lymphatics. 16,18 -23 Until recently, electron microscopy was the method of choice for the unambiguous detection of lymphatics; nevertheless, its reliability is not absolute, and it is definitely not suitable for clinical routine. 3,24 The marker most commonly used to study lymphangiogenesis, is the lymphatic vascular endothelium-specific hyaluronate receptor (LYVE)-1. Besides lymphatic vascular endothelium, it also reacts with macrophages involved in hyaluronate metabolism and angiogenesis. MATERIALS AND METHODS Specimen In accordance with the Declaration of Helsinki, eyes of body/cornea donors (55-89 years of age; 4 -9 hours postmortem; n ϭ 17) were obtained from either the Cornea Bank of the Department of Ophthalmology or the Department of Anatomy I (University of ErlangenNuremberg). Choroids were dissected and fixed by immersion in phosphate-buffered saline (PBS) containing 4% PFA for 4 hours at room temperature (RT), rinsed in PBS (four times 5 minutes), and transferred into PBS containing 15% sucrose (overnight at 4°C). The choroids were frozen face down at Ϫ80°C in liquid nitrogen-cooled methylbutane and stored at Ϫ20°C for further processing. From th

The lymphangiogenic and hemangiogenic privilege of the human sclera

Purpose: Most organs of the human body are supplied with a dense network of blood and lymphatic vessels. However, some tissues are either hypovascular or completely devoid of vessels for proper function, such as the ocular tissues sclera and cornea, cartilage and tendons. Since many pathological conditions are affecting the human sclera, this review is focussing on the lymphangiogenic and hemangiogenic privilege in the human sclera. Methods: This article gives an overview of the current literature based on a PubMed search as well as observations and experience from clinical practice. Results: The healthy human sclera is the outer covering layer of the eye globe consisting mainly of collagenous extracellular matrix and fibroblasts. Physiologically, the sclera shows only a superficial network of blood vessels and a lack of lymphatic vessels. This vascular privilege is actively regulated by balancing anti- and proangiogenic factors expressed by cells within the sclera. In pathological situations, such as open globe injuries or ciliary body melanomas with extraocular extension, lymphatic vessels can secondarily invade the sclera and the inner eye. This mechanism most likely is important for tumor cell metastasis, wound healing, immunologic defense against intruding microorganism, and autoimmune reactions against intraocular antigens. Conclusions: The human sclera is characterized by a tightly regulated vascular network that can be compromised in pathological situations, such as injuries or intraocular tumors affecting healing outcomes Therefore, the molecular and cellular mechanisms underlying wound healing following surgical interventions deserve further attention, in order to devise more effective therapeutic strategies. (C) 2020 Elsevier GmbH. All rights reserved

Scleraxis expressing scleral cells respond to inflammatory stimulation

The sclera is an ocular tissue rich of collagenous extracellular matrix, which is built up and maintained by relatively few, still poorly characterized fibroblast-like cells. The aims of this study are to add to the characterization of scleral fibroblasts and to examine the reaction of these fibroblasts to inflammatory stimulation in an ex vivo organotypic model. Scleras of scleraxis-GFP (SCX-GFP) mice were analyzed using immunohistochemistry and qRT-PCR for the expression of the tendon cell associated marker genes scleraxis (SCX), mohawk and tenomodulin. In organotypic tissue culture, explanted scleras of adult scleraxis GFP reporter mice were exposed to 10 ng/ml recombinant interleukin 1-ss (IL1-ss) and IL1-ss in combination with dexamethasone. The tissue was then analyzed by immunofluorescence staining of the inflammation- and fibrosis-associated proteins IL6, COX-2, iNOS, connective tissue growth factor, MMP2, MMP3, and MMP13 as well as for collagen fibre degradation using a Collagen Hybridizing Peptide (CHP) binding assay. The mouse sclera displayed a strong expression of scleraxis promoter-driven GFP, indicating a tendon cell-like phenotype, as well as expression of scleraxis, tenomodulin and mohawk mRNA. Upon IL1-ss stimulation, SCX-GFP+ cells significantly upregulated the expression of all proteins analysed. Moreover, IL1-ss stimulation resulted in significant collagen degradation. Adding the corticosteroid dexamethasone significantly reduced the response to IL1-ss stimulation. Collagen degradation was significantly enhanced in the IL1-ss group. Dexamethasone demonstrated a significant rescue effect. This work provides insights into the characteristics of scleral cells and establishes an ex vivo model of scleral inflammation