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Ali MJ. Etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO). Prog Retin Eye Res 2023; 96:101193. [PMID: 37394093 DOI: 10.1016/j.preteyeres.2023.101193] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 06/27/2023] [Accepted: 06/29/2023] [Indexed: 07/04/2023]
Abstract
Primary acquired nasolacrimal duct obstruction, or PANDO, is a common adult lacrimal drainage disorder. The current treatment modality of dacryocystorhinostomy to bypass the obstructed nasolacrimal duct has excellent outcomes. However, the understanding of the disease etiopathogenesis needs to be revisited. There are not many studies that specifically assessed any hypothesis or ones that convincingly put forth the presumed or confirmed interpretations regarding the PANDO pathogenesis or the mechanisms or pathways involved therein. Histopathological evidence points to recurrent inflammation of the nasolacrimal duct, subsequent fibrosis, and the resultant obstruction. The disease etiopathogenesis is considered multifactorial. Several implicated suspects include anatomical narrowing of the bony nasolacrimal duct, vascular factors, local hormonal imbalance, microbial influence, nasal abnormalities, autonomic dysregulation, surfactants, lysosomal dysfunction, gastroesophageal reflux, tear proteins, and deranged local host defenses. The present work reviewed the literature on the etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO) to gain insights into the present state of the understanding and the high-value translational implications of precisely decoding the disease etiology.
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Affiliation(s)
- Mohammad Javed Ali
- Govindram Seksaria Institute of Dacryology, L.V. Prasad Eye Institute, Hyderabad, India.
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Atkova EL, Astrakhanstev AF, Subbot AM, Yartsev VD. [Dynamic pathomorphological characteristics of the nasolacrimal duct in its stenosis]. Arkh Patol 2023; 85:22-28. [PMID: 37814846 DOI: 10.17116/patol20238505122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
OBJECTIVE Pathological description of the process of stenosis of the nasolacrimal duct at its various stages. MATERIAL AND METHODS The material for the study was obtained from the wall of the nasolacrimal duct during surgery in 50 patients whose condition was attributed to the 1st, 2nd or 3rd clinical stage of dacryostenosis. The material was fixed in formalin and sent for pathohistological and immunohistochemical (IHC) studies. RESULTS In the 1st stage, the integrity of the epithelium of the nasolacrimal duct was preserved, the density of goblet cells was reduced. Seromucinous glands were single in the lamina propria in the area of stenosis. Diffuse lymphoid-plasmacytic infiltration was observed along the periphery of the terminal sections of the glands and in the subepithelial zone. The infiltrate includes CD68+ tissue macrophages and CD20+ and CD3+ lymphocytes, with a predominance of B-lymphocytes over T-lymphocytes. In the 2nd stage, changes in the epithelial layer in the stenosis zone were detected. In the IHC study, only individual leukocytes were observed in these zones, and T cells were found mainly in the subepithelial zone, B cells - deeper, monocytes - evenly in all layers. In the adjacent zones, the picture of the infiltrate corresponded to the 1st stage. In the 3rd stage, fragments of the nasolacrimal duct wall were represented by dense fibrous connective tissue with pronounced atrophic changes, areas of squamous metaplasia or proliferation of the basal layer, goblet cells were not detected. There was no infiltrate in the area of stenosis during IHC study. In the cellular elements of the infiltrate in areas adjacent to the stenosis zone, CD20+ and CD3+ lymphocytes were present in equal proportions, the arrangement in layers corresponded to that of the 2nd stage. CONCLUSION The results of the study showed that dacryostenosis is a progressive pathological process associated with the progredient development of chronic productive inflammation in the lacrimal ducts.
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Affiliation(s)
- E L Atkova
- M.M. Krasnov Scientific Research Institute of Eye Diseases, Moscow, Russia
| | - A F Astrakhanstev
- D.I. Mastbaum Bureau of Forensic Medical Examination, Ryazan, Russia
| | - A M Subbot
- M.M. Krasnov Scientific Research Institute of Eye Diseases, Moscow, Russia
| | - V D Yartsev
- M.M. Krasnov Scientific Research Institute of Eye Diseases, Moscow, Russia
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Kirkegaard MK. Ocular adnexal lymphoma: Subtype‐specific clinical and genetic features. Acta Ophthalmol 2022; 100 Suppl 270:3-37. [DOI: 10.1111/aos.15248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marina Knudsen Kirkegaard
- Department of Pathology, Eye Section, Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
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Schuh JCL. Mucosa-Associated Lymphoid Tissue and Tertiary Lymphoid Structures of the Eye and Ear in Laboratory Animals. Toxicol Pathol 2020; 49:472-482. [PMID: 33252012 DOI: 10.1177/0192623320970448] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mucosa-associated lymphoid tissue (MALT) of special senses is poorly described and can be confused with nonspecific mononuclear cell infiltrates and tertiary lymphoid structures (TLS). In the eye, MALT consists mostly of conjunctiva-associated lymphoid tissue (CALT) and lacrimal drainage-associated lymphoid tissue (LDALT). In humans, CALT and LDALT are important components of the normal eye-associated lymphoid tissue (EALT), but EALT is less frequently described in ocular tissues of animals. The EALT are acquired postnatally in preferential mucosal sites, expand with antigenic exposure, form well-developed lymphoid follicles, and are reported to senesce. Lymphoid follicles that are induced concurrently with chronic inflammation are more appropriately considered TLS but must be differentiated from inflammation in MALT. Less understood is the etiology for formation of lymphoid tissue aggregates in the ciliary body, limbus, or choroid of healthy eyes in animals and humans. In the healthy eustachian tube and middle ear of animals and humans, MALT may be present but is infrequently described. Concurrent with otitis media, lymphoid follicles in the eustachian tube are probably expanded MALT, but lymphoid follicles in the middle ear may be TLS. The purpose of this comparative review is to familiarize toxicologic pathologists with MALT in the special senses and to provide considerations for differentiating and reporting eye and ear MALT from immune or inflammatory cell infiltrates or inflammation in nonclinical studies, and the circumstances for reporting TLS in compartments of the eye and ear.
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Bâră RI, Voinea LM, Vrapciu AD, Rusu MC. Adding myofibroblasts to the lacrimal pump. Acta Histochem 2020; 122:151536. [PMID: 32156483 DOI: 10.1016/j.acthis.2020.151536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/01/2020] [Accepted: 03/03/2020] [Indexed: 01/03/2023]
Abstract
The lacrimal sac (LS) empties in the nasolacrimal duct to drain the tears in the inferior nasal meatus. Different studies indicated the role of the lacrimal pump in the lacrimal drainage. Although controversial, the lacrimal pump mechanism is an extrinsic one, either active, or passive. An intrinsic contractile potential of the LS was not documented previously. We thus aimed a retrospective immunohistochemical study to test the alpha-smooth muscle actin (α-SMA) and h-caldesmon expression in the LS wall. We used archived paraffin-embedded samples of LS from ten adult patients. The α-SMA + phenotype was detected in basal epithelial cells, in subepithelial ribbons of stromal cells, in vascular smooth muscle cells, as well as in pericytes. H-caldesmon was exclusively expressed in pericytes, vascular smooth muscle cells and myoepithelial cells of the subepithelial glands. The most striking feature we found in all samples was a consistent stromal network of α-SMA+/h-caldesmon- myofibroblasts. This finding supports an intrinsic scaffold useful for the lacrimal pump.
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Affiliation(s)
- Raluca Iustina Bâră
- Department of Ophtalmology, Faculty of Medicine, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania; Department of Ophtalmology, Bucharest University Emergency Hospital, Bucharest, Romania.
| | - Liliana Mary Voinea
- Department of Ophtalmology, Bucharest University Emergency Hospital, Bucharest, Romania; Department of Ophthalmology, Faculty of Medicine, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania.
| | - Alexandra Diana Vrapciu
- Division of Anatomy, Faculty of Dental Medicine, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania.
| | - Mugurel Constantin Rusu
- Division of Anatomy, Faculty of Dental Medicine, "Carol Davila" University of Medicine and Pharmacy, 8 Eroilor Sanitari Blvd., RO-050474, Bucharest, Romania.
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Lohrberg M, Pabst R, Wilting J. Co-localization of lymphoid aggregates and lymphatic networks in nose- (NALT) and lacrimal duct-associated lymphoid tissue (LDALT) of mice. BMC Immunol 2018; 19:5. [PMID: 29368640 PMCID: PMC5784693 DOI: 10.1186/s12865-018-0242-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 01/16/2018] [Indexed: 11/19/2022] Open
Abstract
Background The lymphatic vascular pattern in the head of mice has rarely been studied, due to problems of sectioning and immunostaining of complex bony structures. Therefore, the association of head lymphoid tissues with the lymphatics has remained unknown although the mouse is the most often used species in immunology. Results Here, we studied the association of nasal and nasolacrimal duct lymphatics with lymphoid aggregates in 14-day-old and 2-month-old mice. We performed paraffin sectioning of whole, decalcified heads, and immunostaining with the lymphatic endothelial cell-specific antibodies Lyve-1 and Podoplanin. Most parts of the nasal mucous membrane do not contain any lymphatics. Only the region of the inferior turbinates contains lymphatic networks, which are connected to those of the palatine. Nose-associated lymphoid tissue (NALT) is restricted to the basal parts of the nose, which contain lymphatics. NALT is continued occipitally and can be found at both sides along the sphenoidal sinus, again in close association with lymphatic networks. Nasal lymphatics are connected to those of the ocular region via a lymphatic network along the nasolacrimal duct (NLD). By this means, lacrimal duct-associated lymphoid tissue (LDALT) has a dense supply with lymphatics. Conclusions NALT and LDALT play a key role in the immune system of the mouse head, where they function as primary recognition sites for antigens. Using the dense lymphatic networks along the NLD described in this study, these antigens reach lymphatics near the palatine and are further drained to lymph nodes of the head and neck region. NALT and LDALT develop in immediate vicinity of lymphatic vessels. Therefore, we suggest a causative connection of lymphatic vessels and the development of lymphoid tissues.
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Affiliation(s)
- Melanie Lohrberg
- Institute for Anatomy and Cell Biology, University Medical Hospital Göttingen, Kreuzbergring 36, D-37075, Göttingen, Germany. .,Institute for Neuropathology, University Medical Hospital Göttingen, Robert-Koch-Strasse 40, D-37075, Göttingen, Germany.
| | - Reinhard Pabst
- Institute for Immunomorphology, Medical School Hannover, Carl-Neuberg-Str. 1, Hannover, D-30625, Germany
| | - Jörg Wilting
- Institute for Anatomy and Cell Biology, University Medical Hospital Göttingen, Kreuzbergring 36, D-37075, Göttingen, Germany
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Klećkowska-Nawrot JE, Goździewska-Harłajczuk K, Łupicki D, Marycz K, Nawara T, Barszcz K, Kowalczyk A, Rosenberger J, Łukaszewicz E. The differences in the eyelids microstructure and the conjunctiva-associated lymphoid tissue between selected ornamental and wild birds as a result of adaptation to their habitat. ACTA ZOOL-STOCKHOLM 2017. [DOI: 10.1111/azo.12223] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joanna E. Klećkowska-Nawrot
- Department of Animal Physiology and Biostructure; Faculty of Veterinary Medicine; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Karolina Goździewska-Harłajczuk
- Department of Animal Physiology and Biostructure; Faculty of Veterinary Medicine; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Dariusz Łupicki
- Museum of Natural History of the Faculty of Biology and Animal Science; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Krzysztof Marycz
- Electron Microscopy Laboratory; Faculty of Biology and Animal Science; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Tomasz Nawara
- Electron Microscopy Laboratory; Faculty of Biology and Animal Science; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Karolina Barszcz
- Department of Morphological Sciences; Faculty of Veterinary Medicine; Warsaw University of Life Sciences; Warsaw Poland
| | - Artur Kowalczyk
- Division of Poultry Breeding; Faculty of Biology and Animal Science; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Joanna Rosenberger
- Division of Poultry Breeding; Faculty of Biology and Animal Science; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
| | - Ewa Łukaszewicz
- Division of Poultry Breeding; Faculty of Biology and Animal Science; Wroclaw University of Environmental and Life Sciences; Wroclaw Poland
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Abstract
Mucosal immunity defends the ocular surface against antigenic challenge and microbial invasion. The principal effector site is the lacrimal gland, where immunoglobulin A (IgA) antibodies are produced. Nasal-associated lymphoid tissue and posterior cervical lymph nodes function as major inductive sites for tear IgA responses. Neural connections and systemic hormones maintain the integrity and function of the ocular surface. Neuroenzyme activities in the lacrimal gland are influenced by ocular infections, leading to reduced expression of acetylcholine and modulation of receptors on acinar cells and on plasma cells, thereby decreasing fluid and immunoglobulin secretion. T lymphocyte-dependent responses result in production of interleukin-4 in lacrimal glands, thereby influencing cholinergic enzyme activity affecting immune processes and lacrimal physiology. Furthermore, neuropeptides released into lymphoid structures or inflamed tissues are chemotactic for antigen-presenting cells and affect their interactions with T cells. Thus, in developing therapeutic approaches for treating dry-eye conditions and vaccination strategies to elicit protective ocular mucosal immune responses, the entire lacrimal functional unit should be considered.
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Abstract
Allergic conjunctivitis (AC) can be divided into the primary form (caused by an allergic reaction occurring primarily in the conjunctivae) and the secondary form (induced by allergic reaction originating primarily in the nasal mucosa, where the released mediators can reach conjunctiva through the lacrimal system, the blood, the lymphatic network, or the neurogenic network). Patients with primary AC develop an immediate, late, or delayed conjunctival response (CR) during conjunctival provocation tests. Patients with secondary AC develop an immediate, late, or delayed type of secondary CR, induced by the nasal allergic reaction, due to the nasal allergen challenge. Various hypersensitivity mechanisms may be involved in the particular CR types. The secondarily induced AC and CRs can only be confirmed by nasal provocations tests, performed by rhinomanometry combined with recording of conjunctival signs. The existence of the primary and secondarily induced AC has an impact on treatment of this disorder.
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Phillips TE, Sharp J, Rodgers K, Liu H. M cell-targeted ocular immunization: effect on immunoglobulins in tears, feces, and serum. Invest Ophthalmol Vis Sci 2009; 51:1533-9. [PMID: 19892871 DOI: 10.1167/iovs.09-4491] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
PURPOSE This study investigates whether antigen-sampling M cells, present in the follicle-associated epithelium (FAE) above organized conjunctiva-associated lymphoid tissue in rabbits, bind and retro-transport secretory IgA (sIgA) from the tear film. The hypothesis that IgA-mediated uptake of antigens promotes local and systemic production of immunoglobulins was tested. METHODS sIgA binding and retro-translocation by M cells was characterized by immunocytochemistry. Immunoglobulin concentrations in tears, feces and serum were measured using enzyme-linked immunoassays (ELISA) after topical and systemic immunization with either goat IgG anti-rabbit IgA or nonspecific goat IgG. RESULTS Endogenous sIgA was found associated with the apical membrane of conjunctival M cells. Exogenous anti-IgA immunoglobulins were translocated across M cells. Significant levels of sIgA against goat IgG were present in tears of pre-immune animals. Topical application of either goat IgG specific for rabbit IgA or nonspecific goat IgG led to similar increases in antigen-specific IgA in tear, feces, and serum. The antigen-specific IgG response in tears mirrored the serum response for both immunogens consistent with transudation of this immunoglobulin. The IgM response in tears and serum was weak for both immunogens. Systemic immunization did not sustain or enhance the local mucosal IgA responses. CONCLUSIONS Conjunctival M cells bind and translocate sIgA from the tear film. Topical conjunctival immunization leads to generation of antigen-specific immunoglobulins from both local and distant mucosae and in serum. Natural antibodies, present in the tear film before immunization, may have contributed to similar immune responses to goat anti-rabbit IgA and nonspecific goat IgG.
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Affiliation(s)
- Thomas E Phillips
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211-7400, USA.
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Sjö LD, Ralfkiaer E, Juhl BR, Prause JU, Kivelä T, Auw-Haedrich C, Bacin F, Carrera M, Coupland SE, Delbosc B, Ducrey N, Kantelip B, Kemeny JL, Meyer P, Sjö NC, Heegaard S. Primary lymphoma of the lacrimal sac: an EORTC ophthalmic oncology task force study. Br J Ophthalmol 2006; 90:1004-9. [PMID: 16672329 PMCID: PMC1857190 DOI: 10.1136/bjo.2006.090589] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To define the clinical and histopathological characteristics of primary lacrimal sac lymphoma in a predominantly white population. METHODS Specimens of lacrimal sac lymphoma and follow up data were solicited from members of the Ophthalmic Oncology Task Force of the European Organization for Research and Treatment of Cancer (EORTC) and the European Ophthalmic Pathology Society (EOPS). Specimens were stained with haematoxylin and eosin and an immunohistochemical panel against leucocyte antigens was applied. Diagnosis was reached by consensus of five experienced pathologists according to the World Health Organization classification system. The histopathological findings were correlated with the clinical data. RESULTS Of 15 primary lacrimal sac lymphomas, five (33%) were diffuse large B cell lymphoma (DLBCL), five (33%) were extranodal marginal zone B cell lymphoma of mucosa associated lymphoid tissue (MALT lymphoma), three were classified as "transitional MALT lymphoma," being in transition from MALT lymphoma to DLBCL, and two were unclassified B cell lymphomas. Nine of the patients were female, and the median age at the time of diagnosis was 71 years (range 45-95 years). The most frequent presenting symptoms were epiphora (85%), swelling in the region of the lacrimal sac (79%), and dacryocystitis (21%). All but one patient presented in stage I. Systemic spread occurred in three of nine patients (33%). The 5 year overall survival was 65%. CONCLUSIONS DLBCL and MALT lymphoma are equally common in the lacrimal sac in contrast with the remaining periorbital and/or orbital region where MALT lymphoma predominates.
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MESH Headings
- Aged
- Aged, 80 and over
- Antigens, CD/metabolism
- Antigens, Neoplasm/metabolism
- Female
- Humans
- Lacrimal Apparatus Diseases/diagnosis
- Lacrimal Apparatus Diseases/pathology
- Lacrimal Apparatus Diseases/therapy
- Lymphoma, B-Cell/diagnosis
- Lymphoma, B-Cell/pathology
- Lymphoma, B-Cell/therapy
- Lymphoma, B-Cell, Marginal Zone/diagnosis
- Lymphoma, B-Cell, Marginal Zone/pathology
- Lymphoma, B-Cell, Marginal Zone/therapy
- Lymphoma, Large B-Cell, Diffuse/diagnosis
- Lymphoma, Large B-Cell, Diffuse/pathology
- Lymphoma, Large B-Cell, Diffuse/therapy
- Male
- Middle Aged
- Retrospective Studies
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Affiliation(s)
- L D Sjö
- Eye Pathology Institute, University of Copenhagen, Denmark
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Knop N, Knop E. Ultrastructural anatomy of CALT follicles in the rabbit reveals characteristics of M-cells, germinal centres and high endothelial venules. J Anat 2005; 207:409-26. [PMID: 16191169 PMCID: PMC1571552 DOI: 10.1111/j.1469-7580.2005.00470.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2005] [Indexed: 01/26/2023] Open
Abstract
Conjunctiva-associated lymphoid tissue (CALT) is a part of the eye-associated lymphoid tissue (EALT) at the ocular surface. Its lymphoid follicles are usually characterized by using light microscopy, but its ultrastructure remains largely unknown. In this study, flat whole-mount conjunctival tissues (n = 42) from 21 young adult rabbits were investigated native in reflected light, and further stained and cleared (n = 6), in paraffin histology sections (n = 6), scanning electron microscopy (SEM, n = 4) and transmission electron microscopy (TEM, n = 4). Secondary lymphoid follicles accumulated into a dense group nasally towards the lacrimal punctum of the lower lid. High endothelial venules (HEV) with typical ultrastructure occurred in the parafollicular zone. The bright germinal centre (GC) contained lymphoblasts, follicular dendritic cells, apoptotic cells and tingible body macrophages. The follicle-associated epithelium (FAE) was devoid of goblet cells and contained groups of lymphoid cells. TEM showed these cells to be located in cytoplasmic pockets of superficial electron-lucent cells with a thin cytoplasmic luminal lining that contained a fine filament meshwork and numerous endocytotic vesicles. These M-cells were sitting between and on top of the ordinary dense epithelial cells that were located basally and formed pillar-like structures. In stereoscopic SEM, the surface cells were very large, had a polygonal outline and covered cavernous spaces. The rabbit has a CALT with typical follicular morphology, including HEV for regulated lymphocyte migration and epithelial cells with ultrastructural characteristics of M-cells that allow antigen transport as indicated by the GC-reaction. The arrangement of these M-cells on top of and between epithelial pillar cells may reflect a special structural requirement of the multilayered CALT FAE.
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Affiliation(s)
- Nadja Knop
- Department for Cell Biology in Anatomy, Hannover Medical School, HannoverGermany
| | - Erich Knop
- Research Laboratory of the Eye Clinic CVK, Charite – University School of MedicineBerlin, Germany
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Abstract
Because the cornea is optimized for refraction, it relies on supporting tissues for moistening and nutrition and in particular for immune protection. Its main support tissue is the conjunctiva, in addition to the lacrimal gland, the latter which provides soluble mediators via the tear film. The cornea and conjunctiva constitute a moist mucosal surface and there is increasing evidence that apart from innate defence mechanisms, also lymphoid cells contribute to the normal homeostasis of the corneal surface. A Medline-based literature search was performed in order to review the existing literature on the existence, composition and functions of mucosa-associated lymphoid tissue (MALT) at the ocular surface for corneal protection. The existence of lymphoid cells at the ocular surface and appendage has been known for many years, but for a long time they were believed erroneously to be inflammatory cells. More recent research has shown that in addition to the known presence of lymphoid cells in the lacrimal gland, they also form MALT in the conjunctiva as conjunctiva-associated lymphoid tissue (CALT) and in the lacrimal drainage system as lacrimal drainage-associated lymphoid tissue (LDALT). Together this constitutes an eye-associated lymphoid tissue (EALT), which is a new component of the mucosal immune system of the body. When the topographical distribution of CALT is projected onto the ocular surface, it overlies the cornea during eye closure and is hence in a suitable position to assist the corneal immune protection during blinking and overnight. It can detect corneal antigens and prime respective effector cells, or distribute protective factors as secretory IgA.
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Affiliation(s)
- Erich Knop
- Research Laboratory of the Eye Clinic CVK, Charite - University School of Medicine, Berlin, Germany.
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Knop E, Knop N, Brewitt H. [Dry eye disease as a complex dysregulation of the functional anatomy of the ocular surface. New concepts for understanding dry eye disease]. Ophthalmologe 2004; 100:917-28. [PMID: 14669027 DOI: 10.1007/s00347-003-0935-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Dry eye disease is a disorder of the tear film that results in epithelial damage and in a disruption of the normal homeostasis at the ocular surface. It is widespread and causes symptoms ranging from discomfort to blindness. METHODS A review of the existing literature was used to compare different past and recent concepts for the understanding of dry eye disease with a focus on aspects of the integrating functional anatomy of the ocular surface. RESULTS The understanding of the pathogenesis of dry eye disease has proceeded from the mere recognition of a lack of tears to a consideration of their quality and to the concept of wetting of the ocular surface. However, several other aspects as epithelial differentiation, innervation, hormonal status or immune protection contribute to the intact functional anatomy of the ocular surface. Recently it has been recognized that immunologically regulated mechanisms of inflammation represent a primary or secondary pathogenetic factor for dry eye disease. This is conceivably regulated by the cells of the physiological mucosal immune defence system, the eye-associated lymphoid tissue (EALT). Androgens represent an important trophic factor for the ocular surface and their deficiency predisposes to inflammation. CONCLUSION Dry eye disease represents a complex dysregulation of the functional anatomy of the ocular surface that can start from different alterations (e.g. insufficient secretion, defects in wetting or innervation). Immune-based inflammation is able to interconnect and negatively reinforce these different pathomechanisms, resulting in a vicious circle.
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Affiliation(s)
- E Knop
- Augenklinik-Forschungslabor, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum.
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Knop E, Knop N. [Eye-associated lymphoid tissue (EALT) is continuously spread throughout the ocular surface from the lacrimal gland to the lacrimal drainage system]. Ophthalmologe 2004; 100:929-42. [PMID: 14669028 DOI: 10.1007/s00347-003-0936-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Components of the mucosal immune system (MALT) have been identified in the conjunctiva (as CALT) and the lacrimal drainage system (as LDALT). Their structural and functional relation with the established immune protection by the lacrimal gland is unclear. MATERIAL AND METHODS Macroscopically normal and complete tissues of the conjunctiva, lacrimal drainage system and lacrimal gland from human body donors were investigated by analysis of translucent whole mounts, and using histology, immunohistology as well as scanning and transmission electron microscopy. RESULTS A typical diffuse lymphoid tissue, composed of effector cells of the immune system (T-lymphocytes and IgA producing plasma cells) under an epithelium that contains the IgA transporter SC, is not isolated in the conjunctiva and lacrimal drainage system. It is anatomically continuous from the lacrimal gland along its excretory ducts into the conjunctiva and from there via the lacrimal canaliculi into the lacrimal drainage system. Lymphoid follicles occur in a majority (about 60%) and with bilateral symmetry. The topography of CALT corresponds to the position of the cornea in the closed eye. CONCLUSION These results show that the MALT of the lacrimal gland, conjunctiva and lacrimal drainage system constitute an anatomical and functional unit for immune protection of the ocular surface. Therefore it should be integrated as an "eye-associated lymphoid tissue" (EALT) into the MALT system of the body. EALT can detect ocular surface antigens by the lymphoid follicles and can supply other organs and the ocular surface including the lacrimal gland with specific effector cells via the regulated recirculation of lymphoid cells.
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Affiliation(s)
- E Knop
- Augenklinik-Forschungslabor, Charite-Universitätsmedizin Berlin, Campus Virchow Klinikum.
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