Impaired neurotransmission in lacrimal and salivary glands of a murine model of Sjögren's syndrome

5-N-ethyl Carboxamidoadenosine Stimulates Adenosine-2b Receptor-Mediated Mitogen-Activated Protein Kinase Pathway to Improve Brain Mitochondrial Function in Amyloid Beta-Induced Cognitive Deficit Mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with loss in memory as one of the cardinal features. 5-N-ethyl carboxamidoadenosine (NECA), an agonist of adenosine-2b receptor, exerts neuroprotective activity against several experimental conditions. Further, NECA activates mitogen-activated protein kinase (MAPK) and also attenuates mitochondrial toxicity in mammalian tissues other than brain. Moreover, there is no report on the role of A2b/MAPK-mediated signaling pathway in Aβ-induced mitochondrial toxicity in the brain of the experimental animals. Therefore, the present study evaluated the neuroprotective activity of NECA with or without MAPK inhibitor against Aβ-induced cognitive deficit and mitochondrial toxicity in the experimental rodents. Further, the effect of NECA with or without MAPK inhibitor was evaluated on Aβ-induced mitochondrial toxicity in the memory-sensitive mice brain regions. Intracerebroventricular (ICV) injection of Aβ 1-42 was injected to healthy male mice through Hamilton syringe via polyethylene tube to induce AD-like behavioral manifestations. NECA attenuated Aβ-induced cognitive impairments in the rodents. In addition, NECA ameliorated Aβ-induced Aβ accumulation and cholinergic dysfunction in the selected memory-sensitive mouse HIP, PFC, and AMY. Further, NECA significantly attenuated Aβ-induced mitochondrial toxicity in terms of decrease in the mitochondrial function, integrity, and bioenergetics in the brain regions of these animals. However, MAPKI diminished the therapeutic effects of NECA on behavioral, biochemical, and molecular observations in AD-like animals. Therefore, it can be speculated that NECA exhibits neuroprotective activity perhaps through MAPK activation in AD-like rodents. Moreover, A2b-mediated MAPK activation could be a promising target in the management of AD.

The Effect of Periocular Fatty Acids and 0.15% Hyaluronate Eye Drops Application on Keratoconjunctivitis Sicca in Dogs: An Exploratory Study

The aim of this exploratory study was to evaluate the efficacy of a periophthalmic cream of a pool of fatty acids (FAG®) in association with 0.15% hyaluronate eye drops in alleviating the clinical symptoms of keratoconjunctivitis sicca (KCS) in a case series of dogs. The study was conducted on 10 dogs diagnosed with idiopathic KCS. All dogs had been previously treated with topical tobramycin alone, which had been ineffective in improving clinical signs. The affected eyes were treated with 2 applications daily of a periophthalmic cream of FAG® and 1 drop 3 times a day of 0.15% of hyaluronate eye drops for 8 weeks. Schirmer tear test I (STT I) values were recorded and ocular signs (conjunctival hyperemia, ocular discharge, corneal opacity, vascularization and pigmentation, and discomfort level) were collected, scored on a 3-point scale (grade 0, grade 1, and grade 2). Differences between scores and STT data recorded at baseline and at 8 weeks of therapy were statistically analysed. The effect of treatment was pronounced (increase in STT values by more than 4 mm/min, no signs of inflammation) in 8/18 eyes; moderate (increase in STT values of 3-4 mm/min or mild improvement in signs of corneal/conjunctival inflammation) in 3/18 eyes; and unsatisfactory in 7 of 18 eyes. Median of STT values significantly improved compared with baseline levels, while statistically significant decreases in clinical-sign scores of conjunctival hyperemia, ocular discharge, and discomfort were recorded. However, in moderate and advanced stages, reduction of neovascularization or corneal pigmentation was not observed throughout the treatment period. No noticeable adverse reactions were recorded. Preliminary results indicate that the application of periocular FAG and topical 0.15% hyaluronate eye drops may be a suitable treatment for KCS in dogs in selected cases. A larger comparative study is necessary to further confirm these findings.

Insight into pathogenesis of Sjögren's syndrome: Dissection on autoimmune infiltrates and epithelial cells

Sjögren's syndrome (SS) is a chronic autoimmune disease with broad clinical spectrum, extending from benign exocrinopathy to severe systemic disease and lymphoma development. The glandular and extraglandular dysfunction of SS is associated with lymphocytic infiltrates that invade the epithelial structures of affected organs. The in-depth study of autoimmune lesions in the minor salivary glands (MSG), which are the major target-organ of SS responses, revealed that the lymphocytic infiltrates vary in severity and composition among SS-patients, are full-blown at diagnosis and remain unchanged thereafter. Although the pathogenetic pathways underlying SS have not yet elucidated, it is well-established that glandular epithelial cells are central regulators of local autoimmune responses. Moreover, chronic inflammation affects epithelial function and phenotype, which strengthens or weakens their immunoregulatory/secretory function, leading to deterioration of autoimmune phenomena. Herein, the current findings regarding the autoimmune lesions, the role of epithelial cells and their interaction with infiltrating lymphocytic cells are discussed.

The core mechanism of dry eye disease is inflammation

PURPOSE

The purpose of this article is to review the evidence for the hypothesis that the core mechanism of dry eye disease (DED) is inflammation, including evidence from recent basic, clinical, and translational research involving human patients, animal models, and cell cultures.

METHODS

Using the key words "dry eye + inflammation," the authors conducted a comprehensive search of the PubMed and Web of Science databases for scientific articles published in English between January 1, 1900 and August 30, 2013 on the role of inflammation in DED in cell cultures, animal models, and humans. The resulting articles were then categorized and reviewed.

RESULTS

The literature search revealed a total of 458 publications, almost all published after 1992. The percentages of original studies and review articles are 77.29% (354) and 22.71% (104), respectively. Among the original studies, the number of reports on human DED is 200 (43.7%), on animal models is 115 (25.1%), and cell cultures is 39 (8.5%). A yearly distributing plot revealed that 76% were published from 2003 to 2011, 53% from 2008 to 2012, and 11% during the first 9 months of 2013. This distribution signifies a rapidly growing awareness of the importance of inflammation in DED pathogenesis.

CONCLUSIONS

Inflammation plays a key role in the pathogenesis of DED as evidenced by research using tissue culture, animal models, and subjects with DED. Developing biomarkers for inflammation of the ocular surface will provide improved understanding of the mechanisms leading to DED, classification of the severity of DED, and objective metrics for outcome measures of treatment. The chronicity of the disease suggests that dysregulation of immune mechanisms leads to a cycle of continued inflammation, accompanied by alterations in both innate and adaptive immune responses. Given the underlying mechanism for DED, developing effective and safe anti-inflammatory treatments is likely to be beneficial for patients with DED.

Ocular surface disease and dacryoadenitis in aging C57BL/6 mice

Dry eye in humans displays increased prevalence in the aged and in women. Here, we investigated the ocular surfaces and lacrimal glands of aged mice of both sexes. We surveyed three different ages [young, middle-aged (6 to 9 months), and elderly] by investigating severity markers of dry eye disease (DED). We observed an age-dependent dry eye phenotype as early as 6 to 9 months: increased corneal surface irregularity, increased corneal barrier disruption, conjunctival CD4(+) T-cell infiltration, and loss of mucin-filled goblet cells. Expression of interferon-γ, IL-17 mRNA transcripts was increased in the conjunctiva and IL-17A, matrix metallopeptidase 9, and chemokine ligand 20 in the corneas of elderly mice. Elderly male mice develop more of a skewed response of type 1 T helper cell, whereas female mice have a bias toward type 17 T helper cell in the conjunctiva. In the lacrimal gland, an increase in CD4(+) and CD8(+) T cells and B cells and a decrease in activated dendritic cells were observed. Adoptive transfer of CD4(+) T cells isolated from elderly mice transferred DED into young immunodeficient recipients, which was more pronounced from male donors. Our findings show the development of DED in aging mice. Pathogenic CD4(+) T cells that develop with aging are capable of transferring DED from older mice to naive immunodeficient recipients. Taken together, our results indicate that age-related autoimmunity contributes to development of DED with aging.

Autoimmune dacryoadenitis and sialadenitis induced in rabbits by intravenous injection of autologous lymphocytes activated ex vivo against lacrimal antigens

PURPOSE

Autologous peripheral blood lymphocytes, activated in a mixed cell reaction when cocultured with purified rabbit lacrimal epithelial cells, are known to induce a severe autoimmune dacryoadenitis when injected directly into the donor animal's remaining inferior lacrimal gland (LG) or subcutaneously at a site remote from the LG. The purpose of the present study was to determine the ability of intravenously (IV) injected autologous stimulated lymphocytes to home to the LG and salivary gland (SG) and induce disease.

METHODS

One inferior LG was surgically excised from each rabbit. Acinar epithelial cells were purified, cultured for 2 days, gamma-irradiated, and cocultured for 5 days with purified autologous peripheral blood lymphocytes. The activated lymphocytes were used for autoadoptive transfer.

RESULTS

Tear production was reduced 50% by 4 weeks and tear breakup time was 70% less than normal. Ocular surface defects assessed by rose bengal staining were present but not as pronounced as after direct injection. Four weeks after IV injection, as after direct injection, glands contained large infiltrates composed of predominantly CD4(+) T cells close to interlobular and intralobular ducts; however, they also contained unique areas of streaming lymphocytes. Histopathology at 8 weeks was more severe than at 4 weeks, and SG also showed clusters of abnormal epithelial cells and streaming lymphocytes.

CONCLUSIONS

Lymphocytes activated against lacrimal antigens and injected IV can home to the LG and SG and initiate autoimmune processes, suggesting that these sites constitutively contain not only antigen-presenting cells displaying potentially pathogenic autoantigen epitopes but also chemokines and homing molecules that recruit CD4(+) T cells. This new rabbit model more closely mimics Sjögren syndrome, in that SG manifestations accompany the LG disease. It should be well suited to elucidating Sjögren pathogenesis and pathophysiology and to evaluating experimental therapies.

Use of nucleofection to efficiently transfect primary rabbit lacrimal gland acinar cells

Lacrimal gland acinar cells are an important cell type to study due to their role in production and release of tear proteins, a function essential for ocular surface integrity and normal visual acuity. However, mechanistic studies are often limited by problems with transfection using either plasmid DNA or siRNA. Although various gene delivery methods are available, many have been unproductive due to consistently low transfection efficiencies. We have developed a method using nucleofection that can result in 50% transfection efficiency and 60% knockdown efficiency for plasmid DNA and siRNA, respectively. These results are vastly improved relative to previous studies, demonstrating that nucleofection offers an efficient transfection technique for primary lacrimal gland acinar cells.