Suppression of lymphocyte proliferation and regulation of dendritic cell phenotype by soluble mediators from rat lacrimal epithelial cells

Analysis of the heterogeneity and complexity of murine extraorbital lacrimal gland via single-cell RNA sequencing

PURPOSE

The lacrimal gland is essential for maintaining ocular surface health and avoiding external damage by secreting an aqueous layer of the tear film. However, a healthy lacrimal gland's inventory of cell types and heterogeneity remains understudied.

METHODS

Here, 10X Genome-based single-cell RNA sequencing was used to generate an unbiased classification of cellular diversity in the extraorbital lacrimal gland (ELG) of C57BL/6J mice. From 43,850 high-quality cells, we produced an atlas of cell heterogeneity and defined cell types using classic marker genes. The possible functions of these cells were analyzed through bioinformatics analysis. Additionally, the CellChat was employed for a preliminary analysis of the cell-cell communication network in the ELG.

RESULTS

Over 37 subclasses of cells were identified, including seven types of glandular epithelial cells, three types of fibroblasts, ten types of myeloid-derived immune cells, at least eleven types of lymphoid-derived immune cells, and five types of vascular-associated cell subsets. The cell-cell communication network analysis revealed that fibroblasts and immune cells play a pivotal role in the dense intercellular communication network within the mouse ELG.

CONCLUSIONS

This study provides a comprehensive transcriptome atlas and related database of the mouse ELG.

Multiple Natural and Experimental Inflammatory Rabbit Lacrimal Gland Phenotypes

Purpose

To investigate lacrimal gland (LG) immunophysiological and immune-mediated inflammatory process (IMIP) phenotype diversity.

Methods

Ex vivo matured dendritic cells (mDC) were loaded with acinar cell microparticles (M_P). Peripheral blood lymphocytes (PBL) were activated in mixed cell reactions with mDC and injected directly into autologous, unilateral LG (1° ATD-LG) of two rabbit cohorts, one naïve, one immunized with a LG lysate membrane fraction (P_i). Autoimmune IgG titers were assayed by ELISA, MCR PBL stimulation indices (SI) by [³H]-thymidine incorporation. Schirmer tests without and with topical anesthetic (STT-I, STT-I_A) and rose Bengal (RB) staining tests were performed. H&E and immunohistochemically stained sections were examined. RNA yields and selected transcript abundances were measured. Immune cell number and transcript abundance data were submitted to Principal Component Analysis (PCA).

Results

Immunizing P_i dose influenced SI but not IgG titers. STT scores were decreased, and rose Bengal scores increased, by day 118 after immunization. Previous immunization exacerbated scores in 1° ATD-eyes and exacerbated 1° ATD-LG atrophy. IMIP were evident in 2° ATD-LG as well as 1° ATD-LG. PCA described diverse immunophysiological phenotypes in control LG and diverse IMIP phenotypes in ATD-LG. IgG titers and SI pre-adoptive transfer were significantly associated with certain post-adoptive transfer IMIP phenotype features, and certain LG IMIP features were significantly associated with RB and STT I_A scores.

Conclusions

The underlying variability of normal states may contribute to the diversity of experimental IMIP phenotypes. The ability to generate and characterize diverse phenotypes may lead to phenotype-specific diagnostic and therapeutic paradigms.

Potentially pathogenic immune cells and networks in apparently healthy lacrimal glands

Lacrimal glands of people over 40 years old frequently contain lymphocytic infiltrates. Relationships between histopathological presentation and physiological dysfunction are not straightforward. Data from rabbit studies have suggested that at least two immune cell networks form in healthy lacrimal glands, one responding to environmental dryness, the other to high temperatures. New findings indicate that mRNAs for several chemokines and cytokines are expressed primarily in epithelial cells; certain others are expressed in both epithelial cells and immune cells. Transcript abundances vary substantially across glands from animals that have experienced the same conditions, allowing for correlation analyses, which detect clusters that map to various cell types and to networks of coordinately functioning cells. A core network--expressing mRNAs including IL-1α, IL-6, IL-17A, and IL-10--expands adaptively with exposure to dryness, suppressing IFN-γ, but potentially causing physiological dysfunction. High temperature elicits concurrent increases of mRNAs for prolactin (PRL), CCL21, and IL-18. PRL is associated with crosstalk to IFN-γ, BAFF, and IL-4. The core network reacts to the resulting PRL-BAFF-IL-4 network, creating a profile reminiscent of Sjögren's disease. In a warmer, moderately dry setting, PRL-associated increases of IFN-γ are associated with suppression of IL-10 and augmentations of IL-1α and IL-17, creating a profile reminiscent of severe chronic inflammation.

Electroporating Human Corneal Epithelial Cells With Interleukin 10 and Fas Ligand pDNA

PURPOSE

To develop an optimal electroporation protocol for plasmid (pDNA) transfection of a human corneal epithelial cell (hCEC) line and investigate the immunomodulatory capacity of interleukin 10 and Fas ligand (FasL) transfection on hCECs.

DESIGN

A controlled experimental study.

METHODS

Human corneal epithelial cells were electroporated with pDNA encoding enhanced green fluorescent protein, interleukin 10, or FasL. Supernatants were analyzed for cytokine secretion using enzyme-linked immunosorbent assay. To test potential immunosuppression, electroporated hCECs were cocultured with allogeneic peripheral blood mononuclear cells, and the supernatants analyzed for interferon γ production.

RESULTS

Maximum transfection efficiencies were obtained using optimized settings, and transgene expression was detected up to 13 days following transfection. Interleukin 10 levels peaked at day 4 and FasL at day 2 following electroporation. Coculture supernatants showed significantly lower levels of interferon γ in the modulated groups compared with control.

CONCLUSIONS

Our results demonstrate highly efficient transfection of hCECs using an optimized electroporation protocol. Interleukin 10 and FasL may provide a means of immune modulation of corneal epithelial cells.

Influence of sex hormones and genetic predisposition in Sjögren's syndrome: a new clue to the immunopathogenesis of dry eye disease

Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration, destruction of lacrimal and salivary glands and the presence of serum autoantibodies. Most women that suffer from SS are post-menopausal however, not all post-menopausal women develop SS, suggesting that other factors, in addition to the decrease in ovarian hormones, are necessary for the development of SS. The purposes of this study were to investigate a) the time course of lymphocytic infiltration and apoptosis in the lacrimal gland after ovariectomy, b) if a predisposed genetic background for SS aggravates the effects of decreasing levels of sex hormones in the lacrimal glands and c) if physiological doses of estrogen or androgen prevent the effects observed after ovariectomy. Six weeks old mice that are genetically predisposed to SS (NOD.B10.H2(b)) and control (C57BL/10) mice were either sham operated, ovariectomized (OVX), OVX + 17β estradiol (E(2)) or OVX + Dihydrotestosterone (DHT). Lacrimal glands were collected at 3, 7, 21 or 30 days after surgery and processed for immunohistochemistry to measure CD4(+), CD8(+) T cells, B220(+) B cells, nuclear DNA degradation and cleaved caspase-3 activity. Quantification of the staining was done by light microscopy and Image Pro Plus software. The results of our study show that lymphocytic infiltration preceded lacrimal gland apoptosis after ovariectomy. Moreover, removal of ovarian sex hormones accelerated these effects in the genetically predisposed animal and these effects were more severe and persistent compared to control animals. In addition, sex hormone replacement at physiological levels prevented these symptoms. The mechanisms by which decreased levels of sex hormones caused lymphocytic infiltration and apoptosis and the interaction of lack of sex hormones with the genetic elements remain to be elucidated.

Distinct dacryoadenitides autoadoptively transferred to rabbits by different subpopulations of lymphocytes activated ex vivo

PURPOSE

To test whether CD4+ T cells proliferate in mixed cell reactions with autologous lacrimal gland (LG) acinar cells and whether these cells can autoadoptively transfer disease.

METHODS

Purified acinar cells were gamma irradiated and cocultured with peripheral blood lymphocytes. Activated CD4+ T cells were sorted by fluorescence-activated cell sorting (FACS). Unfractionated activated peripheral blood lymphocytes (UF), CD4+-enriched and CD4+-depleted T cells from an autologous mixed cell reaction were injected into the donor rabbit's remaining LG. After 4 weeks, ocular examinations were performed, and the rabbits were euthanized; LGs were removed for histopathology, immunohistochemistry, and real-time reverse transcription-polymerase chain reaction studies.

RESULTS

CD4 T cells increased in the autologous mixed cell reaction from 20% to 80%. Tear production decreased in the induced disease/UF (ID/UF) group and declined even more in the ID/CD4+-enriched group. Tear breakup times decreased and rose bengal staining increased in all groups. All LGs exhibited significant histopathology and increased messenger RNAs for tumor necrosis factor α. The ID/UF group exhibited the largest increases of CD4+ and rabbit T-lymphocyte antigen-positive cells. The ID/CD4+-enriched group contained fewer infiltrating CD4 cells but more eosinophils, severely altered acinar morphology, and increased fibrosis. LG of the ID/CD4+-depleted group exhibited large increases of CD18, major histocompatibility complex II, and CD4+ cells. Messenger RNAs for interleukin 2, interleukin 4, and CD4+ increased in the ID/CD4+-enriched group compared with the CD4+-depleted group.

CONCLUSIONS

Autoreactive CD4+ effector cells activated ex vivo and autoadoptively transferred, caused what seems to be a distinct dacryoadenitis. The CD4+-depleted cell fraction also contained pathogenic effector cells capable of inducing disease.

Increased expression of cathepsins and obesity-induced proinflammatory cytokines in lacrimal glands of male NOD mouse

PURPOSE

Lacrimal glands (LGs) of male NOD mice, a model of Sjögren's syndrome (SjS), exhibit immune cell infiltration and lipid deposition. The mechanism of SjS was further investigated by characterizing gene expression profiles of NOD mouse LGs in comparison with those of healthy control mice. Differentially expressed genes were further investigated at the protein level to correlate changes in location and abundance with development of disease.

METHODS

Microarray followed by real-time RT-PCR was conducted to compare the gene expression in 12-week-old male NOD mouse LG relative to that in matched BALB/c mouse LG. Immunofluorescence and Western blot analyses were used to localize and quantify proteins of interest. Enzymatic assays measured catalytic activity of cathepsins.

RESULTS

Cathepsin H (Ctsh), S (Ctss), and Z (Ctsz) and proinflammatory factors, including tumor necrosis factor (Tnf), interleukin 6 (Il6), and interleukin 1 beta (Il1b), were upregulated at the mRNA level. Increased cathepsin S immunofluorescence was detected in lysosomes and secretory vesicle-like organelles in LG acinar cells and CD68-positive infiltrating macrophages in NOD mouse LG. Cathepsin S (CATS) and cathepsin H (CATH) activities were significantly higher in NOD mouse LG lysate than in control lysates, and CATS was also significantly elevated in NOD mouse tears.

CONCLUSIONS

Expression of CATS and CATH increases in parallel with proinflammatory cytokines during the development of autoimmune inflammatory disease in the NOD mouse disease model. Tear CATS may represent a biomarker for diagnosis of dacryoadenitis in SjS.

Adeno-associated virus-mediated IL-10 gene transfer suppresses lacrimal gland immunopathology in a rabbit model of autoimmune dacryoadenitis

PURPOSE

To evaluate the effect of adeno-associated virus (AAV) vector-mediated viral (v)IL-10 gene expression on lacrimal gland (LG) immunopathology and ocular surface disease in a rabbit model of induced autoimmune dacryoadenitis (ID).

METHODS

Autologous peripheral blood lymphocytes, activated in a mixed-cell reaction when cocultured with purified rabbit lacrimal epithelial cells, induce a Sjögren's-like autoimmune dacryoadenitis when injected directly back into the donor animal's inferior LG. Four weeks after disease induction, AAV vector expressing the vIL-10 gene under control of a tetracycline-inducible promoter was injected into the inferior LG of the treatment group (ID/Rx), and doxycycline was fed orally to induce transgene expression. The ID group serving as control also received doxycycline. All LGs were removed 16 weeks after disease induction.

RESULTS

Clinical symptoms showed overall improvement in the ID/Rx group compared with the ID group. Histopathologic examination of the ID group's LG revealed scattered large lymphocytic foci and areas of altered or distorted acini, whereas the ID/Rx group had scattered small lymphocytic foci. The number of CD18(+) cells was almost fivefold lower in the ID/Rx group than in the ID group. Although the total number of RTLA(+) cells did not differ between the groups, the CD4/CD8 ratio was 16-fold smaller in the ID/Rx group.

CONCLUSIONS

Animals with experimentally induced autoimmune dacryoadenitis appeared to benefit from AAV-mediated vIL-10 gene transfer therapy. Quantitative immunohistochemical analysis suggested that the therapy might not have been simply immunosuppressive but rather supported the induction of CD8(+) regulatory cells.