Characterization of M Cells in Tear Duct-Associated Lymphoid Tissue of Mice: A Potential Role in Immunosurveillance on the Ocular Surface.

The ocular mucosal tissues are exposed to potentially harmful foreign antigens in the air and tear fluid. The tear duct-associated lymphoid tissue (TALT) may contribute to immune surveillance in the eye region. Follicle-associated epithelium (FAE) of TALTs is classified as stratified squamous epithelium and consists of squamous epithelial cells arranged in layers on the basement membrane. In contrast, most mucosa-associated lymphoid tissue is covered by a monolayer of epithelium containing microfold (M) cells. Therefore, antigen uptake and the presence of M cells in TALT are not fully understood. The present study found that a small population of FAE cells in the TALT expressed intestinal M-cell markers, namely Sox8, Tnfaip2, GP2, and OPG. This cell population was identified as functional M cells because of their uptake capacity of luminal nanoparticles. In addition, RANKL, which is essential for M-cell differentiation, was expressed by stroma-like cells at the subepithelial region and its receptor RANK by the FAE in the TALT. The administration of RANKL markedly increased the number of Sox8+ M cells. In contrast, deficiency in OPG, an endogenous inhibitor of RANKL, increased the number of M cells in the TALT. These data demonstrate that the RANKL-RANK axis is essential for M-cell differentiation in the TALT. Furthermore, immunization via eye drops elicited the production of antigen-specific antibodies in tears, which was enhanced by RANKL administration. Thus, TALT M cells play an important role in the immunosurveillance of the eye region.

Co-localization of lymphoid aggregates and lymphatic networks in nose- (NALT) and lacrimal duct-associated lymphoid tissue (LDALT) of mice.

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.

Nasolacrimal duct opening to the inferior nasal meatus in human fetuses.

The purpose of this study is to describe the Hasner's membrane which is the main factor of congenital nasolacrimal duct obstruction. Hasner's membrane at the nasal end of the fetal nasolacrimal duct (NLD) is considered to rupture at and after birth. However, topographical anatomy around the membrane as well as a mechanism of rupture seems to be still obscure. We observed frontal or sagittal sections of 20 late-stage fetuses (28-33 weeks) and found the on-going rupture in 2 specimens. The present sections demonstrated that 1) the nasal dilation was not a simple ball-like structure but extended posteriorly and laterally; 2) dilation of the NLD consistently involved the lacrimal sac; 3) Hasner's membrane and ductal mucosal layer contained no macrophages and no or few arteries and nerves. The posterior extension of the NLD end ranged from 1-2 mm, while the lateral extension 3-5 mm although a site of the thinnest membrane varied in location between specimens. Moreover, the thickest NLD due to dilation was in the slightly orbital or upper side of the nasal end. Therefore, before surgical treatment of Hasner's membrane, evaluation using medical images seems to be necessary. Since the nasal epithelium on Hasner's membrane was most likely to destroy earlier than the NLD mucosal lining, observations of the membrane from the nasal cavity seemed helpful for diagnosis at which site would be broken and when.

Smad4 in T cells plays a protective role in the development of autoimmune Sjögren's syndrome in the nonobese diabetic mouse.

We investigated the role of Smad4, a signaling molecule of the TGF-beta pathway, in T cells on the pathology of Sjögren's syndrome (SS) in nonobese diabetic (NOD) mice, an animal model of SS. T cell-specific Smad4-deleted (Smad4fl/fl,CD4-Cre; Smad4 tKO) NOD mice had accelerated development of SS compared with wild-type (Smad4+/+,CD4-Cre; WT) NOD mice, including increased lymphocyte infiltration into exocrine glands, decreased tear and saliva production, and increased levels of autoantibodies at 12 weeks of age. Activated/memory T cells and cytokine (IFN-γ, IL-17)-producing T cells were increased in Smad4 tKO NOD mice, however the proportion and function of regulatory T (Treg) cells were not different between Smad4 tKO and WT NOD mice. Effector T (Teff) cells from Smad4 tKO NOD mice were less sensitive than WT Teff cells to suppression by Treg cells. Th17 differentiation capability of Teff cells was similar between Smad4 tKO and WT NOD mice, but IL-17 expression was increased under inducible Treg skewing conditions in T cells from Smad4 tKO NOD mice. Our results demonstrate that disruption of the Smad4 pathway in T cells of NOD mice increases Teff cell activation resulting in upregulation of Th17 cells, indicating that Smad4 in T cells has a protective role in the development of SS in NOD mice.

Derangements of lacrimal drainage-associated lymphoid tissue (LDALT) in human chronic dacryocystitis.

AIMS: To study the changes in the lacrimal drainage-associated lymphoid tissue of the lacrimal sac in human chronic dacryocystitis and its possible implications in understanding the immune defense mechanisms and etiopathogenesis of primary acquired nasolacrimal duct obstruction. METHODS: Retrospective interventional study involving 200 lacrimal sacs of 164 consecutive patients seen between July 2009 and July 2012. Data collected include demographics, clinical presentation, laterality, age at presentation, duration of symptoms, diagnostic irrigation, indications for a dacyrocystectomy, pattern and severity of lymphoid infiltrate, types of lymphoid follicles and their locations, plasma cells, and other cellular infiltrates. The associated epithelial, stromal, and luminal changes with an emphasis on acini, mucosal glands, blood vessels, lymphatics, and goblet cells were also noted. Immunohistochemistry using CD3, CD20, CD138, and immunoglobulin A were used to substantiate the lymphoid tissues of the lacrimal sac. RESULTS: A total of 200 lacrimal sacs were obtained from dacryocystectomy of 164 patients. The patients included 60.5% (99/164) females and 39.6% (65/164) males, with a mean age of 58.4 years at presentation. Laterality showed a predominance of left lacrimal sacs (55%, 110/200) as compared to the right lacrimal sacs (45%, 90/200). Symptoms of epiphora and discharge of more than 6 months duration were considered to be chronic. Lymphoid infiltrate pattern was diffuse in majority of the sacs (81%, 162/200), with subepithelial and intraepithelial together being the commonest location (46.5%, 93/200). Distinct lymphoid follicles were seen in 28% (56/200). Most of the sacs showed mild plasma cell infiltration (66.5%, 133/200). IgA-rich secretions were noted in the lumen and the lining epithelium in 34.5% (69/200). Other common changes noted include increase in the goblet cells (82%, 164/200), dilated lymphatics (94%, 188/200), proliferating blood vessels (99%, 198/200), thickened epithelium (54.5%, 109/200), and stromal fibrosis (88%, 176/200). CONCLUSION: This study presents the largest series to date (n = 200 lacrimal sacs) exclusively on changes in lacrimal drainage-associated lymphoid tissue in human chronic dacryocystitis. This study could be the starting point for further exploration into the molecular biology, immunological implications, and possible implications of LDALT derangements on etiopathogenesis of primary acquired nasolacrimal duct obstruction.

Allergic conjunctivitis and the impact of allergic rhinitis.

Although nasal allergy has been prominent in allergy research, ocular allergy is increasingly recognized as a distinct symptom complex that imposes its own disease burden and reduction in patients' quality of life. In the past year, knowledge of the relationships between allergic conjunctivitis and allergic rhinitis has increased. Allergic conjunctivitis is highly prevalent and has a close epidemiologic relationship with allergic rhinitis. Both conditions also exhibit similar pathophysiologic mechanisms. Pathways of communication are thought to increase the likelihood of an inflammatory reaction at both sites following allergen exposure of nasal or ocular tissue. Clinical trials of intranasal therapies have demonstrated efficacy in allergic conjunctivitis and rhinitis. Newer intranasal steroids decrease ocular symptoms, potentially achieving efficacy by suppressing the naso-ocular reflex, downregulation of inflammatory cell expression, or restoration of nasolacrimal duct patency. Proposed pathophysiologic interactions between allergic rhinitis and ocular allergy underscore the need for therapies with efficacy in both symptom sets.

Nasolacrimal duct closure modulates ocular mucosal and systemic CD4(+) T-cell responses induced following topical ocular or intranasal immunization.

Both topical ocular and topical intranasal immunizations have been reported to stimulate the ocular mucosal immune system (OMIS) and the systemic immune system. Nasolacrimal ducts (NLDs) are the connecting bridges between the OMIS and nasal cavity-associated lymphoid tissue (NALT). These ducts drain topical ocularly administrated solutions into the inferior meatus of the nose to reach the NALT. Inversely, NLDs also drain intranasally administrated solutions to the mucosal surface of the eye and thus the OMIS. This unique anatomical connection between the OMIS and NALT systems provoked us to test whether the OMIS and NALT are immunologically interdependent. In this report, we show that both topical ocular administration and topical intranasal administration of a mixture of immunodominant CD4(+) T-cell epitope peptides from herpes simplex virus type 1 (HSV-1) glycoprotein D (gD) emulsified with the CpG(2007) mucosal adjuvant are capable of inducing local (in conjunctiva) as well as systemic (in spleen) HSV-peptide-specific CD4(+) T-cell responses. Interestingly, surgical closure of NLDs did not significantly alter local ocular mucosal CD4(+) T-cell responses induced following topical ocular immunization but did significantly enhance systemic CD4(+) T-cell responses (as measured by both T-cell proliferation and gamma interferon (IFN-gamma) production; P < 0.005). In contrast, NLD closure significantly decreased ocular mucosal, but not systemic, CD4(+) T-cell responses following intranasal administration of the same vaccine solution (P < 0.001). The study suggests that NALT and the OMIS are immunologically interconnected.

[Nasolacrimal ducts and the dry eye]. / Ableitende Tränenwege und Trockenes Auge.

BACKGROUND: The knowledge regarding the pathogenesis, diagnosis, and treatment of dry eye has made large advances in recent years. However, many questions are still unanswered. Although the nasolacrimal ducts are part of the tear system they have been paid nearly no attention regarding dry eye. METHODS: The present knowledge about the nasolacrimal ducts is presented and discussed in a context with dry eye. A PubMED search was conducted for articles published from 1966 to the present; in addition, review articles as well as book chapters were considered and discussions with investigators in the field were performed. RESULTS: As a draining and secretory system, the nasolacrimal ducts play a role in tear transport and non-specific immune defense. Moreover, components of tear fluid are absorbed in the nasolacrimal passage and are transported into a vascular system that surrounds the nasolacrimal sac and nasolacrimal duct. This system is comparable to a cavernous body and it is connected to the blood vessels of the outer eye. Also it is subject to vegetative control. Organized mucosa-associated lymphoid tissue (MALT) is present in the nasolacrimal ducts displaying the cytomorphological and immunophenotypic features of MALT. CONCLUSIONS: The normally constant absorption of tear fluid components into the blood vessels of the surrounding cavernous body that are connected to the blood vessels of the outer eye, could be a feedback signal for tear fluid production, which comes to a halt if these tear components are not absorbed. Thus, dry eye could be initiated. Defective stimulation of tear duct-associated lymphoid tissue (TALT) could result in abnormal immune deviation at the ocular surface leading to an autoimmunological response that causes dry eye pathology.

Distribution of T-cell subsets and immunoglobulin-containing cells in nasal-associated lymphoid tissue (NALT) of chickens.

The present study demonstrated the localization of the T-cell subsets (CD4+ and CD8+) and immunoglobulin (Ig)-containing cells (IgA, IgM, and IgG) in the nasal mucosa and its accessory structures. These lymphoid structures may be compared with nasal-associated lymphoid tissue (NALT) of rats and mice. In the chicken NALT, T-cell subsets were more widely distributed than Ig-containing cells, especially in large lymphoid accumulations restricted to the respiratory mucosa in the nasal cavity and the nasolacrimal duct. These lymphoid accumulations in the mucosa of the nasal cavity and nasolacrimal duct consisted of widely distributed CD8+ cells and deeply aggregated CD4+ cells adjacent to large germinal centers. In these lymphoid accumulations, IgG-containing cells were more frequently observed than IgM- and IgA-containing cells. T-cell subsets, predominantly CD8+ cells were more widely distributed in the duct epithelium of the lateral nasal glands than Ig-containing cells. Moreover, numerous CD8+ cells and a few Ig-containing cells were found in the chicken salivary glands, especially around the orifice of their ducts into the oral cavity. Therefore, it seems likely that the chicken NALT plays an important part in the upper respiratory tract, with a close relationship to the paraocular immune system.

The presence of a local immune system in the upper blind and lower part of the human nasolacrimal duct.

The nasolacrimal duct is exposed to exogenous agents, including potentially harmful microorganisms, coming from the eye surface by the lacrimal sac, and from the nasal cavity by the inferior meatus of the nose. The upper blind and lower part of the human nasolacrimal duct were examined immunohistochemically to ascertain the presence and localization of immunoglobulin-producing cells and the epithelial expression of IgA, IgM, and IgG in order to verify the possible antimicrobial properties of this duct. IgA-, IgM-, and IgG-positive immunocompetent cells were recognizable in the lamina propria of the upper blind and lower part of the human nasolacrimal duct, while an evident immunoreactivity for sIgA, IgM, and IgG was demonstrated in the cytoplasm of the apical epithelial cells. The results suggest that all the effector components of the mucosal immune system are present in that area of the human nasal mucosa next to the opening of the nasolacrimal duct as well as in the human lacrimal sac.