Effect of inflammation on lacrimal gland function

Proteomic analysis revealed the altered tear protein profile in a rabbit model of Sjögren's syndrome-associated dry eye

Sjögren's syndrome (SS) is an autoimmune disease that results in pathological dryness of mouth and eye. The diagnosis of SS depends on both clinical evaluation and specific antibodies. The goal of this study was to use quantitative proteomics to investigate changes in tear proteins in a rabbit model of SS-associated dry eye, induced autoimmune dacryoadenitis (IAD). Proteomic analysis was performed by iTRAQ and nano LC-MS/MS on tears collected from the ocular surface, and specific proteins were verified by high resolution MRM. It was found that in the tears of IAD rabbits at 2 and 4 weeks after induction, S100 A6, S100 A9, and serum albumin were upregulated, whereas serotransferrin (TF), prolactin-inducible protein (PIP), polymeric immunoglobulin receptor (pIgR), and Ig gamma chain C region were downregulated. High resolution MRM with mTRAQ labeling verified the changes in S100 A6, TF, PIP, and pIgR. Our results indicated significant changes of tear proteins in IAD rabbits, suggesting these proteins could potentially be used as biomarkers for the diagnosis and prognosis of dry eye. Several of these proteins were also found in the tears of non-SS dry eye patients indicating a common basis of ocular surface pathology, however, pIgR appears to be unique to SS.

Clinical-dosimetric relationship between lacrimal gland dose and ocular toxicity after intensity-modulated radiotherapy for sinonasal tumours

OBJECTIVE

To characterise the relationship between lacrimal gland dose and ocular toxicity among patients treated by intensity-modulated radiotherapy (IMRT) for sinonasal tumours.

METHODS

40 patients with cancers involving the nasal cavity and paranasal sinuses were treated with IMRT to a median dose of 66.0 Gy. Toxicity was scored using the Radiation Therapy Oncology Group morbidity criteria based on conjunctivitis, corneal ulceration and keratitis. The paired lacrimal glands were contoured as organs at risk, and the mean dose, maximum dose, V10, V20 and V30 were determined. Statistical analysis was performed using logistic regression and the Akaike information criterion (AIC).

RESULTS

The maximum and mean dose to the ipsilateral lacrimal gland were 19.2 Gy (range, 1.4-75.4 Gy) and 14.5 Gy (range, 11.1-67.8 Gy), respectively. The mean V10, V20 and V30 values were 50%, 25% and 17%, respectively. The incidence of acute and late Grade 3+ toxicities was 23% and 19%, respectively. Based on logistic regression and AIC, the maximum dose to the ipsilateral lacrimal gland was identified as a more significant predictor of acute toxicity (AIC, 53.89) and late toxicity (AIC, 32.94) than the mean dose (AIC, 56.13 and 33.83, respectively). The V20 was identified as the most significant predictor of late toxicity (AIC, 26.81).

CONCLUSION

A dose-response relationship between maximum dose to the lacrimal gland and ocular toxicity was established. Our data suggesting a threshold relationship may be useful in establishing dosimetric guidelines for IMRT planning that may decrease the risk of acute and late lacrimal toxicities in the future.

ADVANCES IN KNOWLEDGE

A threshold relationship between radiation dose to the lacrimal gland and ocular toxicity was demonstrated, which may aid in treatment planning and reducing the morbidity of radiotherapy for sinonasal tumours.

Decrease in hyperosmotic stress-induced corneal epithelial cell apoptosis by L-carnitine

PURPOSE

To characterize the osmoprotective properties of L-carnitine on human corneal epithelial cell volume and apoptosis during hyperosmotic stress.

METHODS

Human corneal limbal epithelial (HCLE) cells were exposed to culture medium at 300 mOsm (isotonic) or 500 mOsm (hyperosmotic) with or without L-carnitine (10 mM). Induction of apoptosis was detected by quantifying the proteolytic activity of caspase-8, caspase-9, and caspase-3/7 using caspase activity assays, the expression of tumor necrosis factor (TNF)-α with enzyme-linked immunosorbent assay, and annexin V/propidium iodide staining of HCLE cells evaluated with confocal microscopy and flow cytometry. Cell volume changes in response to hyperosmotic stress were analyzed using flow cytometry.

RESULTS

After the HCLE cells were exposed to hyperosmotic medium (500 mOsm), the percentage of shrunken cells and damaged/dead cells (stained positively for annexin V and/or propidium iodide) was six- and three-fold, respectively, higher than that under isotonic conditions (300 mOsm). This was paralleled by an increase in TNF-α concentration in media and caspase-8, -9, and -3/7 activities (six-, four-, ten-, and twelve-fold, respectively; all showing p < 0.001). Addition of L-carnitine during hyperosmotic stress partly restored cell volume and significantly reduced the concentration of TNF-α released (p = 0.005) and caspase-9 activity (p = 0.0125). Addition of L-carnitine reduced the percentage of hyperosmolarity-induced damaged/dead cells to levels observed under isotonic conditions.

CONCLUSIONS

L-carnitine can regulate human corneal epithelial cell volume under hyperosmotic stress and ameliorate hyperosmotic stress-induced apoptosis.

Mediator profiles in tears during the conjunctival response induced by allergic reaction in the nasal mucosa

BACKGROUND

The allergic reaction occurring primarily in the nasal mucosa can induce a secondary conjunctival response of an immediate (SICR), late (SLCR), or delayed (SDYCR) type in some patients with allergic conjunctivitis (AC).

OBJECTIVES

To investigate the concentration changes of histamine, tryptase, eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), leukotrienes (LTB 4, LTC4, LTE4), myeloperoxidase (MPO), interferon-γ (IFN-γ), and interleukins (IL-2, IL-4, IL-5) in tears during the SICR, SLCR, and SDYCR.

METHODS

In 32 patients with AC, 11 SICR (p<0.01), 13 SLCR (p<0.001), and eight SDYCR (p<0.01) to nasal challenges with allergens (NPTs), the NPTs and 32 control tests with PBS were repeated and supplemented with the determination of these factors in tears.

RESULTS

The SICRs were associated with significant concentration changes in tears (p<0.05) of histamine, tryptase, ECP, LTC4, and IL-4. The SLCRs were accompanied by significant changes in concentrations of histamine, ECP, LTB4, LTC4, MPO, IL-4, and IL-5. The SDYCRs were associated with significant concentration changes in tears (p<0.05) of LTB4, MPO, IFN-γ, and IL-2. No significant changes in these factors were recorded in tears during the 32 PBS controls (p>0.1) or in the ten control patients (p>0.1).

CONCLUSIONS

These results provide evidence for causal involvement of nasal allergy in some patients with AC, inducing secondary conjunctival response of immediate (SICR), late SLCR, or delayed SDYCR type, associated with different mediator, cytokine, and cellular profiles in the tears, suggesting involvement of different hypersensitivity mechanisms. These results also emphasize the diagnostic value of nasal allergen challenge combined with monitoring of the conjunctival response in some patients with AC.

Patients undergoing long-term treatment with antihypertensive eye drops responded positively with respect to their ocular surface disorder to oral supplementation with antioxidants and essential fatty acids

Background

Glaucoma and dry eye disorders (DEDs) are frequent comorbidities. The antioxidant and anti-inflammatory properties of essential polyunsaturated fatty acids have been extensively studied in relation to eye diseases.

Objective

Our objective was to determine the effects of oral supplementation with a combined formulation of antioxidants and essential polyunsaturated fatty acids on expression of cytokines and chemokines in tears from patients with DEDs or primary open-angle glaucoma (POAG).

Methods

Participants (n = 97) were distributed into three groups: (1) individuals with nonsevere DEDs (DEDG), (2) individuals with nonadvanced POAG (POAGG), and (3) healthy controls. These groups were randomized into two subgroups: one received a daily antioxidant and essential polyunsaturated fatty acid supplement (two pills) for 3 months (+S), and the other did not (−NS). Participants were interviewed and ophthalmologically examined. Concentrations of specific cytokines and chemokines in reflex tears were determined by multiplexed particle-based flow cytometry. The data were analyzed statistically (SPSS version 15.0).

Results

Comparison of the results from the DEDG and POAGG patients showed significant differences in tear expression of granulocyte-macrophage colony-stimulating factor (P = 0.008), tumor necrosis factor α (P = 0.005), vascular endothelial growth factor (P = 0.038), interleukin-4 (P = 0.030), and interleukin-6 (P = 0.044). The main signs and symptoms of dry eyes such as dryness, burning, photophobia, eye heaviness, and blurred vision, as well as positive changes in eyelashes, hair, nails and skin, were significantly improved in DEDG +S and POAGG +S patients relative to unsupplemented patients.

Conclusion

Inflammation biomarkers were differentially expressed in glaucomatous tears, but the differences changed upon antioxidant/essential polyunsaturated fatty acid supplementation. Chronic instillation of antihypertensive eye drops must be considered for integrating protocols to glaucoma standards of care.

Effects of a nutraceutical formulation based on the combination of antioxidants and ω-3 essential fatty acids in the expression of inflammation and immune response mediators in tears from patients with dry eye disorders

BACKGROUND

Women, and those older than 65 years of age, are particularly susceptible to dry eye disorders (DEDs). Inflammation is clearly involved in the pathogenesis of DEDs, and there is mounting evidence on the antioxidant and antiinflammatory properties of essential polyunsaturated fatty acids (EPUFAs).

OBJECTIVE

To analyze whether a combined formulation of antioxidants and long-chain EPUFAs may improve the evolution of DEDs.

METHODS

We used a prospective study to address the relationship between risk factors, clinical outcomes, and expression levels of inflammation and immune response (IIR) mediators in human reflex tear samples. Participants included: (1) patients diagnosed with nonsevere DEDs (DED group [DEDG]); and (2) healthy controls (control group [CG]). Participants were randomly assigned to homogeneous subgroups according to daily oral intake (+S) or not (-NS) of antioxidants and long-chain EPUFAs for 3 months. After an interview and a systematized ophthalmic examination, reflex tears were collected simultaneously from both eyes; samples were later subjected to a multiplexed particle-based flow cytometry assay. A specific set of IIR mediators was analyzed. All data were statistically processed through the SPSS 15.0 software program.

RESULTS

Significantly higher expressions of interleukin (IL)-1β, IL6, and IL10 and significantly lower vascular endothelial growth factor expressions were found in the DEDG as compared to the CG. In the DEDG, significant negative correlations were detected between the Schirmer test and IL-1β, IL6, IL8, and vascular endothelial growth factor levels, and between the fluorescein breakup time with IL6 and IL8 levels. However, levels of IL-1β, IL6, and IL10 in tears were significantly lower in the DEDG+S versus the DEDG-NS and in the CG+S versus the CG-NS. Subjective symptoms of dry eye significantly improved in the DEDG+S versus the DEDG-NS.

CONCLUSION

IIR mediators showed different expression patterns in DED patients, and these patterns changed in response to a combined formulation of antioxidant and EPUFAs supplementation. Our findings may be considered for future protocols integrating clinical/biochemical data to help manage DED patients.

Deletion of interferon-γ delays onset and severity of dacryoadenitis in CD25KO mice

Introduction

To investigate the role of interferon-gamma (IFN-γ) in the onset and severity of dacryoadenitis in the CD25 knockout (KO) mouse model of Sjögren Syndrome.

Methods

CD25/IFN-γ double KO (γDKO) mice were created by crossbreeding CD25KO and IFN-γKO mice. Mice were used at 8, 12, and 16 weeks. Lacrimal gland (LG) infiltrating lymphocytes were characterized with flow cytometry. Tear epidermal growth factor (EGF) concentration was measured with enzyme-linked immunosorbent assay (ELISA). Quantitative polymerase chain reaction (PCR) evaluated T-cell-related cytokines in LGs. Serum autoantibodies against M3R in LG lysates were detected with Western blot.

Results

γDKO LG showed lower lymphocytic infiltration at 8 weeks than in the CD25KO parental strain (˜20% versus ˜60%, respectively), which increased to CD25KO levels at 16 weeks. Flow-cytometry analysis showed an increase in CD4⁺ and CD8⁺ T cells with aging in γDKO LG, similar to that in CD25KO. γDKO had lower levels of interleukin (IL)-17A, transforming growth-factor (TGF)-β1, IL-21, and CCL20, and higher IL-1β and IL-13 mRNA transcripts in the LG than in the parental CD25KO strain. Autoantibodies to M3R were observed in both strains and significantly increased with aging in both strains. CD25KO mice had very low tear EGF concentrations at all ages, whereas the ear EGF concentration in γDKO mice significantly decreased with aging and inversely correlated with the presence of M3R autoantibodies and the degree of LG CD4 and CD8⁺ T-cell infiltration.

Conclusions

The deletion of IFN-γ in the CD25KO mice strain delays glandular destruction and preserves glandular function. M3R autoantibodies increased with aging in both the γDKO and the CD25KO strains. The decrease in LG function in γDKO correlated with the degree of T-cell infiltration and the presence of M3R autoantibodies.

Oxidative stress induced inflammation initiates functional decline of tear production

Oxidative damage and inflammation are proposed to be involved in an age-related functional decline of exocrine glands. However, the molecular mechanism of how oxidative stress affects the secretory function of exocrine glands is unclear. We developed a novel mev-1 conditional transgenic mouse model (Tet-mev-1) using a modified tetracycline system (Tet-On/Off system). This mouse model demonstrated decreased tear production with morphological changes including leukocytic infiltration and fibrosis. We found that the mev-1 gene encodes Cyt-1, which is the cytochrome b(560) large subunit of succinate-ubiquinone oxidoreductase in complex II of mitochondria (homologous to succinate dehydrogenase C subunit (SDHC) in humans). The mev-1 gene induced excessive oxidative stress associated with ocular surface epithelial damage and a decrease in protein and aqueous secretory function. This new model provides evidence that mitochondrial oxidative damage in the lacrimal gland induces lacrimal dysfunction resulting in dry eye disease. Tear volume in Tet-mev-1 mice was lower than in wild type mice and histopathological analyses showed the hallmarks of lacrimal gland inflammation by intense mononuclear leukocytic infiltration and fibrosis in the lacrimal gland of Tet-mev-1 mice. These findings strongly suggest that oxidative stress can be a causative factor for the development of dry eye disease.

Isolation and characterization of progenitor cells in uninjured, adult rat lacrimal gland

PURPOSE

The purpose of this study was to investigate the presence of progenitor cells in the uninjured, adult rat lacrimal gland (LG).

METHODS

The presence of progenitor cells was examined in LG sections from male rats using antibodies against selected stem cell markers and α-smooth muscle actin (SMA), which marks myoepithelial cells (MECs), by immunofluorescence microscopy (IF). Small, immature cells were isolated after digestion of LG with collagenase and culture in RPMI 1640 for 2 weeks. Immature cells were examined for expression of stem cell markers by IF. Immature cell were grown in neuronal, epithelial, and myoepithelial cell media, and examined by light morphology and IF using antibodies to markers of different cell lineages.

RESULTS

In the intact LGs, MECs expressed the stem cell markers nestin, Musashi 1, ABCG2, Pax6, Chx 10, ΔN p63, and Sox 2. All markers colocalized with SMA. Isolated immature cells contained Ki-67, nestin, Musashi 1, Pax 6, and CHX 10. In neuronal media, immature cells differentiated and assumed a neuronal cell morphology expressing neurofilament 200. In media for human corneal endothelial cells, immature cells differentiated, assumed cobblestone morphology, and labeled with the epithelial marker AE1/AE3. In RPMI media immature cells differentiated into cells with MEC-like morphology, and expressed the MEC markers SMA, α-actinin, adenylate cyclase II, and vimentin.

CONCLUSIONS

We conclude that uninjured, adult LG contains progenitor cells that may be MECs, which can be isolated and differentiated into multiple lineages.

Identification of orexins and cognate receptors in the lacrimal gland of sheep

The aim of the present work was to study, by means of immunohistochemical and RT-PCR techniques, the presence and distribution of immunopositivity for orexin A and B (OXA and OXB) and orexin type 1 and 2 receptors (OX(1)R and OX(2)R) in the lacrimal gland of sheep as well as the gene expressions for prepro-orexin (PPOX) and cognate receptors. In serial sections, positive staining for OXA and OXB were localized in the same nervous fibers within the connective tissue septa. Positive staining for OX(1)R was evidenced in the wall of small arteries while that for OX(2)R was observed in the secretory portion of the acinar gland cells with a characteristic localization in the apical cytoplasm. RT-PCR analysis showed the presence of transcripts for PPOX, OX(1)R and OX(2)R in the sheep lacrimal gland; the gene expression of OX(1)R was two-fold greater (p<0.01) than that of OX(2)R. Taken together the present findings raise intriguing questions on the potential role of the orexinergic system in the regulation of lacrimal gland functions that require further investigations.

Effect of topically applied epithelial sodium channel inhibitors on tear production in normal mice and in mice with induced aqueous tear deficiency

PURPOSE

Dry eye syndromes affect a significant proportion of the population worldwide with reported prevalence ranging from 6% to more than 34%. Patients with dry eye can experience intense pain due to eye irritation, gritty/scratchy feeling in the eyes, blurry vision, and light sensitivity. Available treatments for dry eye syndromes remain mainly palliative. The purpose of the present study was to test the hypothesis that inhibiting sodium absorption via the epithelial sodium channel (ENaC) will increase ocular hydration in both normal as well as in animals with experimentally induced dry eye.

METHODS

ENaC inhibitors were dissolved in an aqueous buffer that mimics the composition of tears and were applied topically to the ocular surface of isoflurane-anesthetized mice. The effect of ENaC inhibitors was compared with that of the secretagogue uridine triphosphate (UTP; 1%), a purinergic receptor agonist which was shown to increase tear volume in animals. Tear production was measured for 10 s using phenol red-impregnated cotton threads. Fluorescein staining that assesses ocular surface damage was performed at baseline and then at days 1, 2, and 3 after the induction of dry eye in mice.

RESULTS

Our data show that the inhibition of ENaC led to a time- and concentration-dependent increase in tear volume in normal mice. The effect of ENaC inhibition after a single application outperformed UTP, as it was long-lasting with tear volume still above baseline values 8 h postdosing. ENaC inhibition, which led to increased tear production, improved fluorescein scores in our dry eye model, when compared with nontreated or animals treated with buffer or UTP.

CONCLUSION

We conclude that the inhibition of ENaC provides long-lasting increases in ocular surface hydration and that ENaC blockers could provide an effective new therapy for chronic dry eye.

Changes of chloride channels in the lacrimal glands of a rabbit model of Sjögren syndrome

PURPOSE

To test the hypothesis that expressions of Na-K-2Cl cotransporter-1 (NKCC1), cystic fibrosis transmembrane conductance regulator (CFTR), and chloride channel 2 γ subunit (ClC2γ) in the lacrimal glands (LGs) of rabbits with induced autoimmune dacryoadenitis (IAD) are changed.

METHODS

LGs were obtained from adult female rabbits with IAD and age-matched female control rabbits. LGs were processed for laser capture microdissection, real-time reverse transcription-polymerase chain reaction, Western blot, and immunofluorescence.

RESULTS

In rabbits with IAD, messenger RNA (mRNA) abundance and protein expressions of NKCC1 and CFTR from whole LGs were significantly lower than those in controls. mRNA abundance of NKCC1, CFTR, and ClC2γ from rabbits with IAD was significantly different from that in acinar and ductal cells from controls. NKCC1 was localized to the basolateral membranes of all acinar and ductal cells, with weaker staining intensity in ductal cells, and the staining pattern from rabbits with IAD appeared similar to that from controls. CFTR was found as punctate aggregates in the apical cytoplasm of all acinar and ductal cells, with the intensity in ductal cells much stronger and no significant difference between controls and rabbits with IAD. ClC2γ was also localized to the apical cytoplasm as punctate aggregates of all acinar cells but not in ductal cells, and a similar staining pattern was observed in rabbits with IAD compared with control rabbits.

CONCLUSIONS

Our data demonstrated significant changes of mRNA and protein expressions of NKCC1, CFTR, and ClC2γ in rabbits with IAD, suggesting that these changes may contribute to the altered lacrimal secretion, particularly Cl transport, in rabbits with IAD.

Periocular and intra-articular injection of canine adipose-derived mesenchymal stem cells: an in vivo imaging and migration study

PURPOSE

Immune-mediated diseases affect millions of people worldwide with an economic impact measured in the billions of dollars. Mesenchymal stem cells (MSCs) are being investigated in the treatment of certain immune mediated diseases, but their application in the treatment of the majority of these disorders remains largely unexplored. Keratoconjunctivitis sicca can occur as a result of progressive immune-mediated destruction of lacrimal tissue in dogs and humans, and immune-mediated joint disease is common to both species. In dogs, allogeneic MSC engraftment and migration have yet to be investigated in vivo in the context of repeated injections.

METHODS

With these aims in mind, the engraftment of allogeneic canine MSCs after an injection into the periocular and intra-articular regions was followed in vivo using magnetic resonance and fluorescent imaging.

RESULTS

The cells were shown to be resident near the site of the injection for a minimum of 2 weeks. Analysis of 61 tissues demonstrated preferential migration and subsequent engraftment of MSCs in the thymus as well as the gastrointestinal tract. These results also detail a novel in vivo imaging technique and demonstrate the differential spatial distribution of MSCs after migration away from the sites of local delivery.

CONCLUSION

The active engraftment of the MSCs in combination with their previously documented immunomodulatory capabilities suggests the potential for therapeutic benefit in using MSCs for the treatment of periocular and joint diseases with immune involvement.

Detection of BrdU-label retaining cells in the lacrimal gland: implications for tissue repair

The purpose of the present study was to determine if the lacrimal gland contains 5-bromo-2'-deoxyuridine (BrdU)-label retaining cells and if they are involved in tissue repair. Animals were pulsed daily with BrdU injections for 7 consecutive days. After a chase period of 2, 4, or 12 weeks, the animals were sacrificed and the lacrimal glands were removed and processed for BrdU immunostaining. In another series of experiments, the lacrimal glands of 12-week chased animals were either left untreated or were injected with interleukin 1 (IL-1) to induce injury. Two and half days post-injection, the lacrimal glands were removed and processed for BrdU immunostaining. After 2 and 4 weeks of chase period, a substantial number of lacrimal gland cells were BrdU(+) (11.98 ± 1.84 and 7.95 ± 1.83 BrdU(+) cells/mm(2), respectively). After 12 weeks of chase, there was a 97% decline in the number of BrdU(+) cells (0.38 ± 0.06 BrdU(+) cells/mm(2)), suggesting that these BrdU-label retaining cells may represent slow-cycling adult stem/progenitor cells. In support of this hypothesis, the number of BrdU labeled cells increased over 7-fold during repair of the lacrimal gland (control: 0.41 ± 0.09 BrdU(+) cells/mm(2); injured: 2.91 ± 0.62 BrdU(+) cells/mm(2)). Furthermore, during repair, among BrdU(+) cells 58.2 ± 3.6 % were acinar cells, 26.4 ± 4.1% were myoepithelial cells, 0.4 ± 0.4% were ductal cells and 15.0 ± 3.0% were stromal cells. We conclude that the murine lacrimal gland contains BrdU-label retaining cells that are mobilized following injury to generate acinar, myoepithelial and ductal cells.

Corneal perforation as a primary manifestation of keratoconus in a patient with underlying rheumatoid arthritis

Purpose

The purpose of this study is to report a case of corneal perforation in a patient with undiagnosed keratoconus and underlying rheumatoid arthritis.

Methods

This is a retrospective case study based on the patient’s medical records and followed by a brief review of the literature.

Results

A 53-year-old patient was referred to our department for acute pain and sudden decrease of visual acuity in his left eye. Corneal perforation was detected and attributed to a previously undiagnosed and untreated keratoconus. Additional laboratory work-up and clinical examination revealed a coexisting rheumatoid arthritis. Amniotic membrane was originally transplanted in order to maintain the structural integrity and promote healing of the perforated eye. Subsequently, the patient underwent a penetrating keratoplasty, though with unfavorable results due to postoperative endophthalmitis.

Conclusions

Rheumatoid arthritis may be associated with higher risk of corneal perforation in patients with ectatic degenerative diseases such as keratoconus.

A review on recent advances in dry eye: Pathogenesis and management

Keratoconjunctivitis sicca, more commonly known as dry eye, is an extremely common and often unrecognized disease. It is the condition in ophthalmology that in its mild grade of severity will affect most of the population at one time or other. Due to a wide variety of presentations and symptoms, it often frustrates the ophthalmologists as well as patients. Due to multifactorial and elusive etiology, it is often challenging to treat dry eye. Ocular surface disorders are also clinically important to treat especially in terms of visual acuity. Xero-dacryology is therefore becoming a very important branch of ophthalmology. Recent studies have given insight into the inflammatory etiology of dry eye. The conventional and main approach to the treatment of dry eye is providing lubricating eye drops or tear substitutes. However, the newer treatment approach is to target the underlying cause of dry eye instead of conventional symptomatic relief. In light of the above knowledge, the present article focuses on newer theories on pathogenesis of dry eye and their impact on dry eye management. METHOD OF LITERATURE SEARCH: A systematic literature review was performed using PubMed databases in two steps. The first step was oriented to articles published for dry eye. The second step was focused on the role of inflammation and anti-inflammatory therapy for dry eye. The search strategy was not limited by year of publication. A manual literature search was also undertaken from authentic reference books on ocular surface disease.

Na(+)/K(+)-ATPase in the lacrimal glands of rabbits and its changes during induced autoimmune dacryoadenitis

PURPOSE

To test the hypothesis that expression of Na(+)/K(+)-ATPase subunits in the lacrimal glands (LGs) of rabbits with induced autoimmune dacryoadenitis (IAD) changes.

METHODS

LGs were obtained from adult female rabbits with IAD and age-matched female control rabbits. The LGs were processed for laser capture microdissection (LCM), real time RT-PCR, western blot, and immunofluorescence for the detection of mRNA and proteins of the α1, α2, β1, β2, and β3 subunits of Na(+)/K(+)-ATPase.

RESULTS

In the rabbits with IAD, mRNA levels of α1, β1, and β3 from whole LGs were significantly lower. In samples of acini and epithelial cells from various duct segments, collected by LCM, mRNA levels of α1, β1, β2, and β3 were significantly lower in the rabbits with IAD, although mRNA for α2 could not be detected. However, western blots demonstrated that all five subunits were significantly higher in the rabbits with IAD, although their distribution patterns were similar to those of the control rabbits, as demonstrated by immunofluorescence.

CONCLUSIONS

The data presented herein demonstrated significant changes in mRNA and protein expressions of Na(+)/K(+)-ATPase subunits in rabbits with IAD, suggesting that these changes may play a role in the pathogenesis of Sjögren's syndrome and altered LG secretion, as observed in these animals.

pKa determinations of xanthene derivates in aqueous solutions by multivariate analysis applied to UV-Vis spectrophotometric data

Xanthenes form to an important class of dyes which are widely used. Most of them present three acid-base groups: two phenolic sites and one carboxylic site. Therefore, the pKa determination and the attribution of each group to the corresponding pKa value is a very important feature. Attempts to obtain reliable pKa through the potentiometry titration and the electronic absorption spectrophotometry using the first and second orders derivative failed. Due to the close pKa values allied to strong UV-Vis spectral overlap, multivariate analysis, a powerful chemometric method, is applied in this work. The determination was performed for eosin Y, erythrosin B, and bengal rose B, and also for other synthesized derivatives such as 2-(3,6-dihydroxy-9-acridinyl) benzoic acid, 2,4,5,7-tetranitrofluorescein, eosin methyl ester, and erythrosin methyl ester in water. These last two compounds (esters) permitted to attribute the pKa of the phenolic group, which is not easily recognizable for some investigated dyes. Besides the pKa determination, the chemometry allowed for estimating the electronic spectrum of some prevalent protolytic species and the substituents effects evaluation.

Severe dry eye syndrome after radiotherapy for head-and-neck tumors

PURPOSE

To investigate the incidence of severe dry eye syndrome (DES) after external beam radiotherapy for head-and-neck cancer and its dependence on the parameters relevant to external beam radiotherapy.

METHODS AND MATERIALS

The present retrospective study included 78 patients treated for primary extracranial head-and-neck tumors between 1965 and 2000, whose lacrimal apparatus/entire globe was exposed to fractionated external beam radiotherapy. The dose received by the major lacrimal gland was used for analysis. The end point of the present study was the ophthalmologic diagnosis of severe DES leading to vision compromise.

RESULTS

Of the 78 patients, 40 developed severe DES leading to visual compromise. The incidence of DES increased steadily from 6% at 35-39.99 Gy to 50% at 45-49.99 Gy and 90% at 60-64.99 Gy. With a mean of 0.9 years (range, 1 month to 3 years), the latency of DES was observed to be a function of the total dose and the dose per fraction. On univariate and multivariate analysis, the total dose (p < .0001 and p < .0001, respectively) and dose per fraction (p ≤ .0001 and p = .0044, respectively) were significant. However, age, gender, and the use of chemoradiotherapy were not. The actuarial analysis indicated a 5-year probability of freedom from DES of 93% for doses <45 Gy, 29% for 45-59.9 Gy, and 3% doses ≥60 Gy. A logistic normal tissue complication probability model fit to our data obtained a dose of 34 and 38 Gy corresponding to a 5% and 10% incidence of DES.

CONCLUSION

With a dose of 34 Gy corresponding to a 5% incidence of DES, the risk of severe DES increased, and the latency decreased with an increase in the total dose and dose per fraction to the lacrimal gland. The effect of chemoradiotherapy and hyperfractionation on the risk of DES needs additional investigation.

Ocular fibroblast diversity: implications for inflammation and ocular wound healing

PURPOSE

Various ocular and orbital tissues differ in their manifestations of inflammation, although the reasons for this are unclear. Such differences may be due to behaviors exhibited by resident cell types, including fibroblasts. Fibroblasts mediate immune function and produce inflammatory mediators. Chronic stimulation of ocular fibroblasts can lead to prolonged inflammation and, in turn, to impaired vision and blindness. Interleukin (IL)-1β, which is produced by various cells during inflammation, is a potent activator of fibroblasts and inducer of the expression of inflammatory mediators. The hypothesis for this study was that that human fibroblasts derived from distinct ocular tissues differ in their responses to IL-1β and that variations in the IL-1 signaling pathway account for these differences.

METHODS

Human fibroblasts were isolated from the lacrimal gland, cornea, and Tenon's capsule and treated with IL-1β in vitro. Cytokine and prostaglandin (PG)E(2) production were measured by ELISA and EIA. Cyclooxygenase (Cox)-2 expression was detected by Western blot. Components of the IL-1 signaling pathway were detected by flow cytometry, ELISA, Western blot, and immunofluorescence.

RESULTS

Cytokine and PGE(2) production and Cox-2 expression were greatest in corneal fibroblasts. VEGF production was greatest in Tenon's capsule fibroblasts. Variations in IL-1 receptor and receptor antagonist expression, IκBα degradation and p65 nuclear translocation, however, did not account for these differences, but overexpression of the NF-κB member RelB dampened Cox-2 expression in all three fibroblast types.

CONCLUSIONS

The results highlight the inherent differences between ocular fibroblast strains and provide crucial insight into novel, tissue-specific treatments for ocular inflammation and disease, such as RelB overexpression.

A method to extract cytokines and matrix metalloproteinases from Schirmer strips and analyze using Luminex

PURPOSE

The Schirmer's test is commonly used in the clinic for the diagnosis of dry eye disease by measuring tear volume. This report describes a procedure which can be used to recover tears from the Schirmer strip for the measurement of multiple tear cytokines as well as matrix metalloproteinases (MMPs) by Luminex technology.

METHODS

Cytokine and MMP recovery was determined by using spiked Schirmer strips presoaked with known cytokines or MMPs prepared in PBS with 1% BSA. In a clinical study, tears were collected from 5 subjects using Schirmer strips. Strips were stored on ice immediately after removal from the subject and stored dry at -20 °C for 16-24 h. Cytokines were extracted from the Schirmer strip in 0.5 M NaCl with 0.5% Tween-20. Concentrations of cytokines and MMPs in collected tear samples were analyzed by Luminex using both a 10-cytokine and a 5-MMP kit.

RESULTS

The standard curves for the assay in both the kit assay buffer and extraction buffer were identical for 9 of the 10 cytokines and all 5 MMPs. In the clinical sample all the cytokines (interleukin 1α [IL-1α], IL-1β, IL-1ra, IL-4, IL-6, IL-8, IL-10, IL-13, monocyte chemotactic protein-1 [MCP-1], and tumor necrosis factor-α [TNF-α]) and 5 MMPs (MMP-1, MMP-2, MMP-7, MMP-9, and MMP-10) tested were detected in at least 50% of the 10 subject samples. Recoveries from extracted Schirmer strips were >60% for 8 of the 10 cytokines and all MMPs.

CONCLUSIONS

Numerous cytokines and MMPs were detected in the tear samples collected using the Schirmer strip, including many that have been implicated in ocular surface disease. This procedure may be used to evaluate the cytokine and MMP content in tear samples in clinical studies, especially for the evaluation of dry eye therapeutics. Because the Schirmer test is routine in the assessment of dry eye, this method offers the opportunity to evaluate both the quantity and quality of the tears.

Changes of aquaporins in the lacrimal glands of a rabbit model of Sjögren's syndrome

AIMS

To test the hypothesis that the expression of aquaporins (AQPs) 4 and 5 is altered in the lacrimal glands (LG) of rabbits with induced autoimmune dacryoadenitis (IAD).

MATERIALS AND METHODS

LGs were obtained from adult female rabbits with IAD, and age-matched female control rabbits. LGs were processed for laser capture microdissection (LCM), real time RT-PCR, Western blot, and immunofluorescence for the detection and quantification of protein and mRNAs of AQP4 and AQP5 in whole LGs, and purified acinar cells and duct cells from specific duct segments.

RESULTS

In rabbits with IAD, abundances of mRNAs for AQP4 and AQP5 from whole LGs were significantly lower than controls. Levels of mRNA for AQP4 were lower in most duct segments from rabbits with IAD. However, the mRNA abundance for AQP5 was significantly lower in acini from rabbits with IAD, while its abundance was higher in each duct segment. Western blot showed that the expression of AQP4 in LGs from rabbits with IAD was 36% more abundant than normal controls, whereas AQP5 was 72% less abundant. Immunofluorescence indicated that AQP4 immunoreactivity (AQP4-IR) was present on the basolateral membranes of acinar and ductal cells in control and diseased LGs, with ductal cells showing stronger AQP4-IR than acinar cells. AQP5-IR was found on apical and basolateral membranes of acinar cells, and showed a "mosaic" pattern, i.e., with some acini and/or acinar cells showing stronger AQP5-IR than others. Minimal AQP5-IR was detected in ductal cells from control animals, while its intensity was significantly increased in rabbits with IAD.

CONCLUSIONS

These data strongly support our hypothesis that expressions of AQPs are altered in rabbits with IAD, and that specific ductal segment play important roles in lacrimal secretion.

Isolation and propagation of mesenchymal stem cells from the lacrimal gland

PURPOSE

Previously, it was reported that the murine lacrimal gland is capable of repair after experimentally induced injury and that the number of stem/progenitor cells was increased during the repair phase (2-3 days after injury). The aim of the present study was to determine whether these cells can be isolated from the lacrimal gland and propagated in vitro.

METHODS

Lacrimal gland injury was induced by injection of interleukin (IL)-1, and injection of saline vehicle served as control. Two and half days after injection, the lacrimal glands were removed and used to prepare explants or acinar cells for tissue culture. Cells derived from the explants and the acinar cells were grown in DMEM supplemented with 10% fetal bovine serum. Cells were stained for the stem cells markers, nestin, vimentin, ABCG2, and Sca-1. Cell proliferation was measured using an antibody against Ki67 or a cell-counting kit. The adipogenic capability of these cells was also tested in vitro.

RESULTS

Results show that nestin-positive cells can be isolated from IL-1-injected, but not saline-injected, lacrimal glands. A population of nestin-positive cells was also positive for vimentin, an intermediate filament protein expressed by mesenchymal cells. In addition, cultured cells expressed two other markers of stem cells, ABCG2 and Sca-1. These cells proliferated in vitro and can be induced to form adipocytes, attesting to their mesenchymal stem cell property.

CONCLUSIONS

Murine lacrimal glands contain mesenchymal stem cells that seem to play a pivotal role in tissue repair.

A mouse dry eye model induced by topical administration of benzalkonium chloride

PURPOSE

To develop a dry eye model of mouse induced by topical administration of benzalkonium chloride (BAC) and investigate the possible mechanisms.

METHODS

BAC at concentration of 0.2% was applied to the mouse ocular surface for 7 days. Phenol red thread tear test, tear break-up time (BUT) test, corneal inflammatory index scoring, fluorescein and rose bengal test were performed to evaluate the toxic effects of BAC on the ocular surface. Global specimens were collected on day (D) 7 and labeled with a series of antibodies including cytokeratin 10 (K10) and mucin 5AC (MUC5AC). Apoptosis of ocular surface epithelium was evaluated by in situ terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Histologic analysis and transmission electron microscopy (TEM) were performed on D7.

RESULTS

BAC at a concentration of 0.2% successfully induced a dry eye condition with decreased tear volume and BUTs, increased corneal fluorescein and rose bengal scores. The Inflammatory index was increased in accompaniment with higher tumor necrosis factor-α (TNF-α) expression and more inflammatory infiltration in the cornea. Immunolabeling revealed positive K10 expression in BAC-treated corneal epithelium and fewer MUC5AC-positive cells in the BAC-treated conjunctival fornix. TUNEL assay showed more apoptotic cells in the corneal basal epithelium. TEM showed that the size and intervals of the microvillis were both reduced in the corneal epithelium.

CONCLUSIONS

Topical administration of 0.2% BAC in mouse induces changes resembling that of dry eye syndrome in humans, and thus, represents a novel model of dry eye.

Mechanisms involved in injury and repair of the murine lacrimal gland: role of programmed cell death and mesenchymal stem cells

The non-keratinized epithelia of the ocular surface are constantly challenged by environmental insults, such as smoke, dust, and airborne pathogens. Tears are the sole physical protective barrier for the ocular surface. Production of tears in inadequate quantity or of inadequate quality results in constant irritation of the ocular surface, leading to dry eye disease, also referred to as keratoconjunctivitis sicca (KCS). Inflammation of the lacrimal gland, such as occurs in Sjogren syndrome, sarcoidosis, chronic graft-versus-host disease, and other pathological conditions, results in inadequate secretion of the aqueous layer of the tear film and is a leading cause of dry eye disease. The hallmarks of lacrimal gland inflammation are the presence of immune cell infiltrates, loss of acinar epithelial cells (the secreting cells), and increased production of proinflammatory cytokines. To date, the mechanisms leading to acinar cell loss and the associated decline in lacrimal gland secretion are still poorly understood. It is also not understood why the remaining lacrimal gland cells are unable to proliferate in order to regenerate a functioning lacrimal gland. This article reviews recent advances in exocrine tissue injury and repair, with emphasis on the roles of programmed cell death and stem/progenitor cells.

Influence of bilateral medial collateral ligament injury on mRNA expression in distal corneal tissues of control and ovariohysterectomized rabbits

PURPOSE

Corneal tissues are reported to be impacted by physiological changes (eg, menopause), systemic autoimmune diseases, and osteoarthritic-like conditions. In this study, changes in specific mRNA levels in the cornea after a ligament injury in normal and rabbits subjected to surgical menopause were examined.

METHODS

Skeletally mature female rabbits were either sham-operated (control) or were subjected to surgical menopause (OVX). Eight weeks post-OVX, subsets of control and OVX animals were subjected to bilateral injuries to their medial collateral ligaments (MCL) of the knee, and 6 and 14 weeks postinjury, corneal tissues were harvested. Using reverse transcriptase-polymerase chain reaction, mRNA levels for several relevant molecules, including matrix molecules, growth factors, cytokines, proteinases, and hormone receptors, were assessed.

RESULTS

mRNA levels for estrogen receptor, decorin, collagens, several growth factors, and inflammatory cytokines decreased in central corneal tissue 6 weeks after distal MCL injury in control animals. The central corneal tissues of animals subjected to OVX alone also exhibited decreases in mRNA levels for a similar set of molecules. When OVX animals were further subjected to MCL injury, the mRNA levels for many of these molecules did not vary from those in the uninjured OVX group. Interestingly, mRNA levels for most molecules were still altered 14 weeks post-MCL injury in the control and OVX animals, a time when the MCL has healed.

CONCLUSIONS

Corneal tissues respond to changes resulting from OVX and/or injury. OVX combined with a ligament injury does not appear to have an additive impact on corneal mRNA levels for most of the molecules assessed.

Curcumin protects against hyperosmoticity-induced IL-1beta elevation in human corneal epithelial cell via MAPK pathways

Increased tear osmolarity is an essential feature of dry eye disease. Curcumin, a natural polyphenol extracted from herb turmeric, has recently been reported to have anti-inflammatory effects. However, its anti-inflammatory effects have not been investigated in dry eye disease. It has been reported that elevated osmolarity achieved by adding sodium chloride to the culture medium of corneal epithelial cells increased the production of IL-1beta, a proinflammation cytokine. This in vitro dry eye model was used to test the anti-inflammatory effects of curcumin. In the present study, a 450 mOsM hyperosmotic medium was produced by adding sodium chloride to the culture medium to reach a final concentration of 90mM. Human corneal epithelial cells cultured in this hyperosmotic medium for 24h showed an increase of IL-1beta, IL-6 and TNF-alpha levels in the conditioned medium. IL-1beta was also upregulated at mRNA levels. Activation of p38 MAP kinase (p38), JNK MAP kinase (JNK) and NF-kappaB in cultured corneal epithelial cells were also induced by hyperosmotic conditions. Curcumin at concentrations of 1-30muM did not affect the cell viability of cultured corneal epithelial cells. Pretreatment of curcumin (5muM) completely abolished the increased production of IL-1beta induced by the hyperosmotic medium. Increased phosphorylation of p38 caused by high osmolarity was also completely abolished by curcumin, whereas the phosphorylation of JNK was only partially inhibited. SB 203580 (p38 inhibitor), but not SP 600125 (JNK inhibitor), completely suppressed hyperosmoticity-induced IL-1beta production, indicating that the inhibition of production of IL-1beta by curcumin may be achieved through the p38 signal pathway. Curcumin completely abolished a hyperosmoticity-induced increase of NF-kappaB p65. NF-kappaB inhibitor suppressed hyperosmoticity-induced IL-1beta production. p38 inhibitor suppressed hyperosmoticity-induced NF-kappaB activation, indicating that NF-kappaB activation was dependent on p38 activation. The present study suggests that curcumin might have therapeutic potential for treating dry eye disease.

Lymphocytic infiltration leads to degradation of lacrimal gland extracellular matrix structures in NOD mice exhibiting a Sjögren's syndrome-like exocrinopathy

We previously reported that lacrimal glands (LGs) of male non-obese diabetic (NOD) mice, an established mouse model of autoimmune inflammatory LG disease that displays many features of human LGs in patients afflicted with Sjögren's syndrome (SjS), exhibit significant degradation of extracellular matrix (ECM) structures as well as increased expression of matrix metalloproteinases (MMPs). The purpose of the current study was to expand the spectrum of proteases identified, to clarify their probable origin as well as to identify the contribution of these changes to disease pathogenesis. We explored in depth the changes in ECM structures and ECM protease expression at the onset of disease (6 weeks) versus late stage disease (18 weeks) in male NOD mouse LGs, relative to LGs of age-matched male NODscid, a severely immunocompromised congenic strain, and healthy BALB/c mice. LG tissues were examined using routine histological, immunohistochemical, Western Blot and gene expression analyses novel multiphoton imaging technologies. We further characterized the profile of infiltrating immune cells under each condition using flow cytometry. Our results show that the initial infiltrating cells at 6 weeks of age are responsible for increased MMP and cathepsin H expression and therefore initiate the LG ECM degradation in NOD mice. More importantly, NODscid mice exhibited normal LG ECM structures, indicating the lymphocytes seen in the LGs of NOD mice are responsible for the degradation of the LG ECM. The disease-related remodeling of LG ECM structures may play a crucial role in altering the acinar signaling environment, disrupting the signaling scaffolds within the cells, which are required to mobilize the exocytotic trafficking machinery, ultimately leading to a loss of LG function in patients afflicted with SjS.

Seasonal and perennial allergic conjunctivitis: the possible role of nasal allergy

BACKGROUND

There is a link between conjunctiva and nose. Nasal allergy is suspected to be involved in some cases of conjunctivitis. This work aims to investigate the possible role of nasal allergy in seasonal (SAC) and perennial (PAC) allergic conjunctivitis and the value of nasal challenges with allergens (nasal provocation tests [NPTs]) for the diagnostic procedures of the conjunctivitis.

METHODS

In 61 adults suffering from SAC or PAC with a positive history and skin tests, but responding insufficiently to the local treatment, 122 NPTs and 61 control nasal challenges with phosphate-buffered saline (PBS) were performed using rhinomanometry combined with recording of ocular response. In 16 control subjects suffering only from allergic rhinitis without a history of conjunctivitis, 16 positive NPTs were repeated and supplemented with registration of ocular features.

RESULTS

Of the 61 patients, 55 developed 103 positive nasal responses of various types (P < 0.01), 82 of which were accompanied by significant conjunctival response (P < 0.01) without any corneal involvement. No significant ocular responses were recorded during 61 control PBS challenges (P > 0.05) as well as during 16 challenges in control subjects (P > 0.1).

CONCLUSIONS

These results illustrate a possible involvement of nasal allergy in some patients with allergic conjunctivitis (SAC and PAC) and the value of the nasal challenges with allergen combined with registration of the ocular features in the diagnostic approach to these disorders.

Systemic Immunomodulatory Therapy in Severe Dry Eye Secondary to Inflammation

PURPOSE

To report four patients with unusually severe acute keratitis sicca secondary to lacrimal tissue and ocular surface inflammation who eventually required systemic immunosuppressive therapy.

METHODS

Observational case series of four patients with extremely severe acute dry eye syndrome who were profoundly disabled by pain and photophobia (to the extent of staying in dark rooms) despite aggressive conventional therapy. Clinical data including visual acuities, other treatments administered for dry eye, systemic medical conditions, Schirmer and rose bengal staining results, degree of conjunctival injection, and medications were recorded. All four patients were treated with systemic immunomodulatory therapy.

RESULTS

All four patients were female with a mean age at presentation of 40 years (range 22-58 years), and all had systemic autoimmune diseases: systemic lupus erythematosus (SLE) and Sjogren's syndrome (n = 2), Sjogren's syndrome (n = 1), rheumatoid arthritis (RA) and psoriasis (n = 1). Schirmer test values at onset ranged from 0 to 2 mm. All patients had failed aggressive lubrication, topical cyclosporine, lid care, and punctual plugs. In two patients, serum tears and hyphrecation punctal occlusion were tried without success. Various systemic immunosuppressive agents were used to control inflammation of the lacrimal glands: methotrexate and cyclosporine A (patient 1), cyclosporine A (patient 2), prednisone (patient 3), and methotrexate and infliximab (patient 4). Treatment with systemic immunomodulatory agents resulted in resolution of the acute inflammatory assault on the lacrimal glands and control of signs and symptoms of keratoconjunctivitis sicca in all four patients, and visual acuities improved in all of them. Post-treatment Schirmer values ranged from 7 to 10 mm.

CONCLUSION

Systemic immunosuppressive agents may be required in the treatment of recalcitrant primary and secondary Sjogren's syndrome caused by systemic autoimmune conditions. We show that systemic immunomodulatory therapy leads to significantly improved tear production and resolution of the keratoconjunctivitis in these rare but severe cases.

Predicted phenotypes of dry eye: proposed consequences of its natural history

This paper reviews current knowledge of the pathophysiology of dry eye and predicts that the clinical picture in late disease differs in both severity and quality from that in early disease. It is hypothesized that hybrid forms evolve, in which aqueous-deficient dry eye (ADDE) takes on features of evaporative dry eye (EDE) and vice versa. As a consequence, early and late forms may require different diagnostic criteria and respond to different therapeutic regimes. Tear hyperosmolarity plays a key role in the damage mechanism of dry eye, and ADDE is recognized to be a low-volume, hyperosmolar state. As ADDE advances, a progressive decrease in lacrimal secretion occurs, exacerbated by loss of the corneal reflex. This causes a decrease in tear volume, thinning of the aqueous tear film, and retarded spreading of the tear film lipid layer. The latter is hypothesized to cause an increase in evaporative water loss and an added evaporative component to the dry eye. Thus, in advanced disease, the hybrid state would be an organic ADDE, accompanied by a functional EDE in the absence of meibomian gland dysfunction. This functional EDE would respond to agents that expand the tear volume, restore corneal sensitivity, or provide an artificial tear film lipid layer.

Altered expression of genes functioning in lipid homeostasis is associated with lipid deposition in NOD mouse lacrimal gland

Functional atrophy and accompanying lymphocytic infiltration and destruction of the lacrimal gland (LG) are characteristics of Sjögren's Syndrome (SjS). The male NOD mouse is an experimental model for the autoimmune exocrinopathy that develops in the LG of SjS patients. Acinar cells in LG of male NOD mice aged 3-4 months were previously shown to accumulate lipid droplets. In the current study, analysis of lipid components revealed that the accumulated lipids were mostly cholesteryl esters (CE). Gene expression microarray analysis followed by real-time RT-PCR revealed alterations in the expression of several genes involved in lipid homeostasis in LG of 12-week-old male NOD mice relative to matched BALB/c controls. A series of upregulated genes including apolipoprotein E, apolipoprotein F, hepatic lipase, phosphomevalonate kinase, ATP-binding cassette D1 and ATP-binding cassette G1 were identified. Comparison of liver mRNAs to LG mRNAs in BALB/c and NOD mice revealed that the differential expressions were LG-specific. Gene expression profiles were also characterized in LGs of female mice, younger mice and immune-incompetent NOD SCID mice. Investigation of the cellular distribution of Apo-E and Apo-F proteins suggested that these proteins normally coordinate to mediate lipid efflux from the acinar cells but that dysfunction of these processes due to missorting of Apo-F may contribute to CE deposition. Finally, the initiation and extent of lipid deposition were correlated with lymphocytic infiltration in the LG of male NOD mice. We propose that impaired lipid efflux contributes to lipid deposition, an event that may contribute to the development and/or progression of dacryoadenitis in the male NOD mouse.

Neurologic evaluation of acute lacrimomimetic effect of cyclosporine in an experimental rabbit dry eye model

PURPOSE

To evaluate neurologically acute lacrimation caused by cyclosporine (CsA) eyedrops in rabbit.

METHODS

Normal adult male New Zealand White rabbits and those that underwent parasympathectomy each received a single instillation of 0.1% CsA or vehicle eyedrops. Schirmer tear test (STT) results, flow rate of lacrimal gland (LG) fluid from the excretory lacrimal duct of the main LG, and blink rate (over a 3-minute period) were measured before and after instillation of CsA or vehicle. Light microscopy was performed to examine the main LG in vitro. Protein release from LG fragments was assessed after incubation with CsA for 30 minutes.

RESULTS

In normal rabbits, the STT value and the flow rate of LG fluid were significantly increased after treatment with CsA compared with vehicle (P < 0.05). In contrast, no changes were found in denervated eyes. The blink rate of CsA-treated eyes was significantly higher than that of vehicle-treated eyes in normal rabbits (P < 0.005), whereas that of denervated eyes decreased significantly after CsA instillation compared with before administration (P < 0.005). Light microscopy showed that the cytoplasm of acinar cells was packed with secretory granules in denervated LG tissue 7 days after parasympathectomy. The same finding was observed 3 hours after CsA instillation. CsA had no stimulatory effect on protein release by acinar cells in LG fragments at all concentrations tested.

CONCLUSIONS

These results suggest that CsA has no direct effect on tear fluid secretion from the LG in an acute model. Instead, CsA increases reflex tear flow.

The role of inflammation and antiinflammation therapies in keratoconjunctivitis sicca

PURPOSE

To review and integrate recent advances in identifying the role of inflammation in the pathogenesis of dry eye conditions and the biological rationale and practical clinical aspects of newer, antiinflammatory theories.

METHODS

A comprehensive literature survey.

RESULTS AND CONCLUSION

Keratoconjunctivitis Sicca (KCS) is a multifactorial and complex disorder in which ocular surface inflammations play a central role. Identification of specific CD4-T-Cell pathways and the recent recognition of targeting of alpha-fodrin suggest a case for novel new therapeutic aspects such as anti-CD4 monoclonal antibodies, systemic linoleic and gamma-linolenic acids, and omega-6 essential fatty acids. Replacement of tear volume with nonpreserved wetting agents and standard typical antiinflammatory corticosteroid and/or cyclosporine A continues to be central current conventional therapy for KCS.