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Santa Jeremy Ono

Publications and source records attributed to Santa Jeremy Ono.

At least 19 recordsLinked to original sources
PubMed2006

Inhibition of MHC class II gene expression in uveal melanoma cells is due to methylation of the CIITA gene or an upstream activator.

Most cells with an intact interferon-gamma receptor and signaling pathway are able to express MHC class II molecules when treated with cytokines such as interferon-gamma and tumor necrosis factor-a. Interestingly, primary uveal melanocytes and most ocular melanoma cells are resistant to interferon-gamma mediated induction of class II MHC genes. This unusual phenotype is hypothesized to be germane to the immune-privileged status to the eye. Via a series of experiments, we have probed the molecular basis of this class II MHC resistant phenotype. We have analyzed the methylation status of the gene encoding the class II transactivator (CIITA), and asked whether treatment of class II MHC resistant ocular melanoma cells with the demethylating agent 5'-azacytidine can restore interferon-gamma inducibility of these class II MHC genes in these cells. The data obtained suggest that the specific blockade in cytokine-induced class II MHC gene expression is due to a suppression of the gene encoding the class II transactivator (CIITA). Treatment with 5' azacytidine restores the ability of these cells to express class II MHC genes upon interferon-gamma treatment. Whilst this is reminiscent of what occurs in another immune-privileged tissue--the placental trophoblast--we show here that silencing of the CIITA gene in uveal melanocytes either involves methylation of distinct nucleotides from those detected in trophoblasts, or involves an upstream activator of CIITA gene expression.

Azacitidine↗
PubMed2005

IFN-gamma gene expression is controlled by the architectural transcription factor HMGA1.

We report for the first time that IFNG gene expression requires high mobility group (HMG)A1, the architectural transcription factor mediating enhanceosome formation. This finding is supported by our direct studies of T cells isolated from the HMGA1-transgenic mice displaying an up-regulation of IFN-gamma production and of HMGA1-deficient mice exhibited a decreased IFN-gamma induction. In parallel transfection studies in EL4 cells, we observed elevated IFNG gene promoter activity in cells stably over-expressing HMGA1 and a reduction of such activity in cells expressing dominant-negative HMGA1. In vitro binding assays further demonstrated a specific interaction of HMGA1 to defined regions of the IFNG gene proximal promoter.

Animals↗
PubMed2005

Allergic conjunctivitis: update on pathophysiology and prospects for future treatment.

Allergic conjunctivitis is in actuality a group of diseases affecting the ocular surface and is usually associated with type 1 hypersensitivity reactions. Two acute disorders, seasonal allergic conjunctivitis and perennial allergic conjunctivitis, exist, as do 3 chronic diseases, vernal keratoconjunctivitis, atopic keratoconjunctivitis, and giant papillary conjunctivitis. The ocular surface inflammation (usually mast cell driven) results in itching, tearing, lid and conjunctival edema-redness, and photophobia during the acute phase and can lead to a classic late-phase response (with associated eosinophilia and neutrophilia) in a subset of individuals. As is the case in other allergic diseases, a chronic disease can also develop, accompanied by remodeling of the ocular surface tissues. In severe cases the patient experiences extreme discomfort and sustains damage to the ocular surface. For such cases, there is no highly effective and safe treatment regimen. Topical administration of corticosteroids is used in severe cases but is associated with an increased risk for the development of cataracts and glaucoma. Thus there is a worldwide search for new biotargets for the treatment of these diseases. Here we provide a brief update of the clinical symptoms associated with these diseases, the rationale for disease classification, recent advances in our understanding of the pathogenesis of the diseases, and an update on both preclinical and clinical advances toward refined therapies for these diseases.

Administration, Topical↗
PubMed2005

Induction of BCL-6 gene expression by interferon-gamma and identification of an IRE in exon I.

BCL-6 is a POZ domain zinc-finger transcription factor that appears to play important roles in the development of the immune system and its regulation. Mutations within BCL-6 gene can therefore contribute to the genesis of a variety of lymphomas, and can also manifest as a classic Th2-type hyperimmune response. In addition to its roles in B- and T-cell development, and in germinal centre formation, the factor is also critical for the development of peripheral memory T cells. In this study, we report that BCL-6 expression is induced by IFN-gamma in Jurkat cells and in nontransformed T cells polarized toward the Th1 phenotype. The IFN-gamma-responsive region has been mapped within the first exon between nucleotide +180 and +200. In vivo footprinting of the first exon reveals that a stretch of DNA between nucleotide +180 to +195 (which we term the X-box) is constitutively occupied in vivo in the presence or absence of IFN-gamma. A guanine at +195 residing at the boundary of the X-box and a downstream IFN-gamma-activated sequence (GAS 1; between nucleotides +192 to +200) is occupied in IFN-gamma-treated cells, indicating the interaction of an IFN-gamma-inducible/modified factor to this region. Consistent with this, electrophoretic mobility shift assays detect STAT-1alpha interactions with the downstream GAS1 motif. The cumulative data suggest that the X-box-binding protein facilitate the binding of STAT-1alpha to the GAS 1 site. The discovery that the BCL-6 transcription factor is inducible by IFN-gamma may help explain some of the postulated biological roles of BCL-6 in T cell development and differentiation, and help explain the Th2-biased phenotype of BCL-6-deficient mice.

Animals↗
PubMed2005

Circulating anti-retinal antibodies as immune markers in age-related macular degeneration.

Age-related macular maculopathy (ARM) and age-related macular degeneration (AMD) are the leading causes of blindness in the Western world. Despite the magnitude of this clinical problem, very little is known about the pathogenesis of the disease. In this study, we analysed the sera (using indirect immunohistochemistry and Western blot analysis) from a very large cohort of such patients and normal age-matched controls to detect circulating anti-retinal antibodies. Patients with bilateral drusen (n = 64) and with chorioretinal neovascularization (CNV) (n = 51) were recruited in addition to age-matched control subjects (n = 39). The sera were analysed for anti-retinal immunoglobulins on retinal sections. The data were then correlated with the clinical features graded according to the International Classification and Grading System of ARM and AMD. The sera of patients with drusen (93.75%) and CNV (82.27%) were found to have a significantly (P = 0.02) higher titre of autoantibodies to the retina in comparison with controls (8.69%), indicating significant evidence of involvement of the immune process in early stages of AMD. Subsequent statistical analysis of the drusen group showed significant progressive staining (P = 0.0009) in the nuclei layers from early to late stages of ARM. Western blotting confirmed the presence of anti-retinal immunoglobulins to retinal antigens. As anti-retinal immunoglobulins are present in patients with bilateral drusen and exudative AMD, these antibodies could play a significant role in the pathogenesis of AMD. Whilst we do not have evidence that these antibodies precede disease onset, the possibility that their presence might contribute to disease progression needs to be investigated. Finally, the eventual identification of the target antigens detected by these antibodies may permit the future development of new diagnostic methods for ARM and AMD.

Aged↗
PubMed2005

Macrophage inflammatory protein-1alpha as a costimulatory signal for mast cell-mediated immediate hypersensitivity reactions.

Regulation of the immune response requires the cooperation of multiple signals in the activation of effector cells. For example, T cells require signals emanating from both the TCR for antigen (upon recognition of MHC/antigenic peptide) and receptors for costimulatory molecules (e.g., CD80 and CD60) for full activation. Here we show that IgE-mediated reactions in the conjunctiva also require multiple signals. Immediate hypersensitivity reactions in the conjunctiva were inhibited in mice deficient in macrophage inflammatory protein-1alpha (MIP-1alpha) despite normal numbers of tissue mast cells and no decrease in the levels of allergen-specific IgE. Treatment of sensitized animals with neutralizing antibodies with specificity for MIP-1alpha also inhibited hypersensitivity in the conjunctiva. In both cases (MIP-1alpha deficiency and antibody treatment), the degranulation of mast cells in situ was affected. In vitro sensitization assays showed that MIP-1alpha is indeed required for optimal mast cell degranulation, along with cross-linking of the high-affinity IgE receptor, FcepsilonRI. The data indicate that MIP-1alpha constitutes an important second signal for mast cell degranulation in the conjunctiva in vivo and consequently for acute-phase disease. Antagonizing the interaction of MIP-1alpha with its receptor CC chemokine receptor 1 (CCR1) or signal transduction from CCR1 may therefore prove to be effective as an antiinflammatory therapy on the ocular surface.

Animals↗
PubMed2005

A specific CCR3 chemokine receptor antagonist inhibits both early and late phase allergic inflammation in the conjunctiva.

Allergic inflammation manifests as one of a number of diseases, including asthma, dermatitis, food allergy, vernal keratoconjunctivitis, and systemic anaphylaxis. Together these diseases affect nearly 25% of the Western world and are a leading health-care problem. The diseases are often biphasic, with an early phase driven primarily by mast cell degranulation and a late phase characterized by leukocyte recruitment. While chemokines are well known to be critical for leukocyte recruitment, their importance in early-phase reactions is poorly defined. We show here that administration of a single oral dose of a high affinity and highly selective CCR3 antagonist ablates both the early and late phase reactions in a mouse model of allergic conjunctivitis. A direct analysis of mast cells in the conjunctiva demonstrates that antagonism of the CCR3 receptor stabilizes the mast cell in vivo, thereby leading to the impaired early phase reaction. The late phase reaction is also strongly inhibited as characterized by both reduced eosinophilia and neutrophilia. These results constitute the first direct evidence that antagonism of CCR3 has clear potential for the treatment of allergic diseases.

Administration, Oral↗
PubMed2005

Role of CC chemokines and their receptors in multiple aspects of mast cell biology: comparative protein profiling of FcepsilonRI- and/or CCR1-engaged mast cells using protein chip technology.

Apart from the FcepsilonRI-mediated mechanism, mast cells are activated by chemokines. Evidence has accumulated indicating that there is cross-talk between the FcepsilonRI-mediated signalling pathway and CC chemokine receptor (CCR)-mediated signalling pathways in mast cells. We have found that costimulation with IgE/antigen and CC chemokine ligand 3 (CCL3) enhances degranulation but inhibits chemotaxis of rat basophilic leukaemia (RBL)-2H3 cells expressing human CCR1 (RBL-CCR1 cells). We hypothesize that this signalling cross-talk in mast cells may play important roles in the orchestration and focusing of the allergic response. In this study, we have sought information about global protein networks either enhanced or inhibited following cross-talk between the FcepsilonRI-mediated and CCR-mediated signalling pathways in mast cells. We believe this information may be useful for providing an understanding of mast cell function and in the establishment of new anti-inflammatory drugs for allergic diseases. Proteomics is a promising tool for studying protein profiles within biological samples and facilitates an understanding of the complex responses of an organism to a stimulus. Here, we show comparative data of protein profiles derived from FcepsilonRI-engaged and/or CCR1-engaged RBL-CCR1 cells using protein chip array technology, a proteomic technology. We also discuss our view of the role of CC chemokines and CCRs in regulating multiple aspects of mast cell biology.

Animals↗
PubMed2004

Impact of engagement of FcepsilonRI and CC chemokine receptor 1 on mast cell activation and motility.

CC chemokines participate in the recruitment and activation of immune cells through CC chemokine receptors (CCRs). Here, we report that cross-talk between CCR1-mediated signaling pathway and FcepsilonRI-mediated signaling pathway affects degranulation positively but affects chemotaxis of mast cells adversely. Costimulation via FcepsilonRI engagement with IgE/antigen and CCR1 engagement with recombinant human CCL3 synergistically enhanced degranulation in rat basophilic leukemia-2H3 cells expressing human CCR1 (RBL-CCR1). Interestingly, FcepsilonRI engagement inhibited CCL3-mediated chemotaxis and membrane ruffling of RBL-CCR1 cells. Small GTP-binding proteins of the Rho family, Rac, Cdc42, and Rho control chemotaxis by mediating the reorganization of the actin cytoskeleton. Both a Rho inhibitor C3 exoenzyme and a Rho kinase (ROCK) inhibitor Y-27632 inhibited chemotaxis of RBL-CCR1 cells toward CCL3, indicating that activation of the Rho/ROCK signaling pathway is required for the CCL3-mediated chemotaxis of the cells. Costimulation with IgE/antigen and CCL3 enhanced Rac and Cdc42 activation but decreased ROCK activation in RBL-CCR1 cells compared with that in the cells stimulated with CCL3 alone. These results suggest that costimulation via FcepsilonRI and CCR1 engagements induced 1) inhibition of membrane ruffling, 2) decreased ROCK activation, and 3) reciprocal imbalance between Small GTP-binding proteins of the Rho family, which result in the inhibition of chemotaxis of RBL-CCR1 cells. The cross-talk between FcepsilonRI-mediated signaling pathway and CCR-mediated signaling pathway would induce optimal activation and arrested chemotaxis of mast cells, thus contributing to allergic inflammation.

Animals↗
PubMed2004

Epigenetic silencing of the CIITA gene and posttranscriptional regulation of class II MHC genes in ocular melanoma cells.

PURPOSE: Primary uveal melanocytes and many ocular melanoma cells are resistant to interferon (IFN)-gamma-mediated induction of major histocompatibility complex (MHC) class II molecule expression. This suppression of class II MHC induction is considered to be one of the ways in which the eye is able to inhibit inflammatory responses. However, the mechanism(s) of this suppression is unknown. In this study, we have probed the molecular basis of this phenotype and report two distinct mechanisms underlying this phenotype. METHODS: Primary ocular melanocytes and ocular melanoma cell lines (retaining this IFN-gamma-resistant class II MHC phenotype) were examined for the expression of class II MHC molecules on the cell surface by flow cytometry. Class II MHC gene expression was further examined using Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses. RESULTS: The IFN-gamma signal-transduction pathway was found to be intact by electrophoretic mobility shift assay (EMSA) and transfection of reporter constructs. The lack of class II MHC gene expression appears to result from at least two mechanisms: (1) a specific inhibition of CIITA (class II transactivator) gene expression (reminiscent of trophoblasts), and (2) posttranscriptional regulation of class II MHC genes. CONCLUSIONS: The inability of primary uveal melanocytes and ocular melanoma cells to express class II MHC molecules after treatment with IFN-gamma has been found to map to two distinct points in the class II MHC biosynthetic pathway. The predominant mechanism appears to involve the silencing of the endogenous gene encoding the class II transactivator (CIITA). Here, the blockade does not involve signal transduction from the IFN-gamma receptor, but rather involves a specific silencing of the CIITA gene. A second mechanism involves the posttranscriptional regulation of class II MHC genes.

Cell Nucleus↗
PubMed2004

MHC class II gene expression is not induced in HPIV3-infected respiratory epithelial cells.

The major histocompatibility complex (MHC) class II transactivator (CIITA) typically is required for both constitutive and inducible expression of MHC class II genes. However, transcription of class II MHC genes has been observed in specific cell types (e.g., thymic epithelial cells) in CIITA-deficient mice as well as in specific situations (e.g., following viral infections or in natural killer [NK]/target cell interaction). These observations have been interpreted by some to indicate that a CIITA-independent pathway of class II gene expression might be germane to processes such as the acquisition of tolerance during thymic selection or in the evasion of immune surveillance by a subset of viruses. One of the most striking examples of CIITA-independent, inducible class II gene expression has involved the de novo expression of class II MHC molecules on respiratory epithelial cells following infection by human parainfluenza virus type 3 (HPIV3). We report here that despite careful analysis using multiple techniques, we have been unable to detect HPIV3-dependent, CIITA-independent (or CIITA-dependent) induction of class II MHC genes. Thus, whereas there may still be an intriguing role for CIITA-independent gene expression in facets of the immune response, this is unlikely to manifest in the analysis of HPIV3 infection of respiratory epithelial cells.

Animals↗
PubMed2003

Molecular dissection of the architectural transcription factor HMGA2.

HMGA2 protein belongs to the High Mobility Group A (HMGA) family of architectural transcription factors. These proteins establish a network of protein-protein and protein-DNA interactions resulting in the formation of enhanceosomes at promoters and enhancers regulating the expression of several genes. HMGA2 dysregulation, as a result of specific chromosomal rearrangements, has been identified in a variety of common benign mesenchymal tumors, and transgenic mice expressing a truncated form of HMGA2 protein demonstrated a causal relationship between the expression of the HMGA2 protein and tumorigenesis. In this paper, using several recombinant mutant proteins, we have investigated the role played by the different domains of HMGA2 in protein-protein and protein-DNA interaction. Using the IFN-beta gene as a model, we have shown that a short region of HMGA2, comprising the second DNA-binding domain, is critical for enhancing the NF-kappaB complex formation, for binding to the PRDII element, and also for protein-protein interaction with the NF-kappaB p50 subunit. Moreover, we have analyzed the interaction of HMGA2 mutant proteins with different DNA targets demonstrating that the absence of the C-terminal tail alters HMGA2/DNA complexes in a subset of DNA sequences. Our results suggest possible implications for the role of HMGA2 in tumorigenesis.

DNA↗
PubMed2003

Chemokines: roles in leukocyte development, trafficking, and effector function.

Chemokines, representing a large superfamily of 8- to 15-kd proteins, were originally discovered through their ability to recruit various cell types into sites of inflammation. It is now clear that these molecules play a much wider role in immune homeostasis, playing key roles in driving the maturation, homing, and activation of leukocytes. In this review we analyze the roles chemokines play in the development, recruitment, and activation of leukocytes. Because signaling from the receptors drives these processes, signal transduction from chemokine receptors will also be reviewed. Taken together, we highlight the various points at which chemokines contribute to allergic inflammation and at which their targeting might contribute to new therapies for type I hypersensitivity reactions.

Cell Differentiation↗
PubMed2003

Detailed criteria for the assessment of clinical symptoms in a new murine model of severe allergic conjunctivitis.

PURPOSE: The aims of this research were to: (1) generate a rapid protocol for the sensitization of rodents to a defined allergen without footpad injections yet leading to both acute- and late-phase hypersensitivity reactions in the ocular surface; and (2) define detailed criteria for the assessment of clinical symptoms in the acute-phase response. METHODS: With the approved methods for the use of experimental animals in research and existing sensitization protocols as a starting point, we developed and tested a new protocol with respect to its ability to generate an acute- and late-phase response on ocular challenge. Clinical symptoms were assessed by a trained ophthalmologist under masked conditions, and late-phase responses determined by histologic analysis of conjunctival tissue sections. RESULTS: A new protocol for the rapid sensitization of mice, avoiding footpad injections, yet yielding both acute- and late-phase allergic responses, was developed. Detailed criteria for the assessment of disease severity were established and tested. CONCLUSION: This protocol establishes a murine model of allergic conjunctivitis that will be useful for both the study of the molecular and cellular basis of allergic reactions in the ocular surface and the testing of new therapies for this disease.

Ambrosia↗
PubMed2003

Immunity in the eye: lessons in organ-specific responses.

Fifty-five years have past since Sir Peter Medawar first demonstrated that the fate of allografts differs in the skin, brain, subcutaneous tissue, and anterior chamber of the eye. Indeed, these and other experiments performed at the University of Birmingham and University College London not only helped define key paradigms in transplantation biology but introduced the concept of immune privilege in the eye and in other tissues. In the ensuing years, the work from dozens of laboratories has confirmed that immune responses in eye, although sharing many features with immunity in other tissues, are atypical in many respects. This has been hypothesized to stem from the requirement in the eye to hold inflammation in check to preserve visual function. Indeed, inflammatory reactions in different regions of the eye can result in visual impairment and blindness, manifesting in diseases such as vernal keratoconjunctivitis, uveitis, corneal endotheliitis, Mooren's ulcer, and pemphigoid. The investigation of the cell and molecular basis of the unique nature of immunity in the eye has revealed a remarkably complex network of interactions that controls inflammation while affording immunity. The most recent data generated in this field and the concepts arising from their interpretation were discussed at a symposium held at the University College London in late 2002. Here, we highlight some of the findings discussed at the meeting and introduce in-depth reviews published in this issue of the journal.

Animals↗
PubMed2003

Novel mechanisms of class II major histocompatibility complex gene regulation.

Class II MHC molecules present processed peptides from exogenous antigens to CD4+ helper T lymphocytes. In so doing, they are central to immunity, driving both the humoral and cell mediated arms of the immune response. Class II MHC molecules, and the genes encoding them, are expressed primarily in cells of the immune system (B cells, thymic epithelial cells, activated T cells and professional antigen presenting cells). The expression is also under developmental control. Research over the past 20 years have provided a clear understanding of the cis-elements and transcription factors that regulate the expression of Class II MHC genes. Perhaps the most critical advance has been the discovery of CIITA, a non- DNA binding activator of transcription that is a master control gene for class II gene expression. Current research is focused on understanding the situations where class II MHC gene expression occurs in a CIITA-independent pathway, and the molecular basis for this expression. Finally, significant emphasis is being placed on targeting class II MHC transcription factors to either inhibit or stimulate the immune response to transplanted tissue or in cell based vaccines. This communication outlines recent advances in this field and discusses likely areas for future research.

Animals↗