The Conjunctiva-Associated Lymphoid Tissue in Chronic Ocular Surface Diseases

• Published in: Microscopy and microanalysis Vol. 23; no. 4; pp. 697 - 707
• Main Authors: Mastropasqua, Rodolfo, Agnifili, Luca, Fasanella, Vincenzo, Nubile, Mario, Gnama, Agbeanda A., Falconio, Gennaro, Perri, Paolo, Di Staso, Silvio, Mariotti, Cesare
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01.08.2017; Oxford University Press
• Subjects: Allergies; Animals; Antigens; Bronchus; Confocal microscopy; Conjunctiva; Conjunctivitis - pathology; Conjunctivitis - physiopathology; Cornea; Cytokines; Deregulation; Disease Models, Animal; Dry Eye Syndromes - complications; Eye; Follicles; Gain; Glaucoma; Glaucoma - complications; Humans; Immune system; Immunology; Impact damage; Incidence; Inflammation; Lymphoid cells; Lymphoid tissue; Lymphoid Tissue - pathology; Microscopy; Mucosa; Mucosal-associated lymphoid tissue; Pathogenesis; Quality of life; Review Article; Stimulation; Tumor necrosis factor-TNF; ocular surface disease; in vivo confocal microscopy; glaucoma therapy dry eye disease; ocular allergy; conjunctiva-associated lymphoid tissue
• ISSN: 1431-9276; 1435-8115
• DOI: 10.1017/S1431927617000538

Ocular surface diseases (OSDs) represent a widely investigated field of research given their growing incidence and the negative impact on quality of life. During OSDs, cytokines generated by damaged epithelia trigger and deregulate the lymphoid cells composing the eye-associated lymphoid tissues, inducing an immune-mediated chronic inflammation that amplifies and propagates the disease during time. The conjunctiva-associated lymphoid tissue (CALT), given its particular position that permits immune cells covering the cornea, might play a crucial role in the development of OSDs. Despite the recognized inflammatory role of mucosa-associated lymphoid tissues in other stations taking contact with the external environment (gut or bronchus), CALT did not gain the deserved consideration. In the last years, the diffusion of the in vivo confocal microscopy (IVCM) stimulated the interest to CALT, especially in dry eye, ocular allergy, and glaucoma. Though the initial stimuli were different, IVCM documented similar changes, represented by increased lymphoid cells within the diffuse layer, follicles and interfollicular spaces. These findings, which need to be validated by immunohistology, support the CALT stimulation during OSDs. However, while an involvement of the CALT in OSDs is hypothesizable, the exact role of this structure in their pathogenesis remains unclear and warrants further investigations.