A Non-invasive Way to Isolate and Phenotype Cells from the Conjunctiva

Traditionally, ocular surface cytology is studied with techniques such as spatula technology and brush technology. The problem with these techniques is ...

A Chronic Autoimmune Dry Eye Rat Model with Increase in Effector Memory T Cells in Eyeball Tissue

Dry eye disease is a very common condition that causes morbidity and healthcare burden and decreases the quality of life. There is a need for a suitable ...

Nanyang Technological University

N-methyl-D-aspartate receptors (NMDARs) are ligand-gated ion channels that play an important role in neuronal development, plasticity, and excitotoxicity. NMDAR antagonists are neuroprotective in animal models of neuronal diseases, and the NMDAR open-channel blocker memantine is used to treat Alzheimer's disease. In view of the clinical application of these pharmaceuticals and the reported expression of NMDARs in immune cells, we analyzed the drug's effects on T-cell function. NMDAR antagonists inhibited antigen-specific T-cell proliferation and cytotoxicity of T cells and the migration of the cells toward chemokines. These activities correlated with a reduction in T-cell receptor (TCR)-induced Ca(2+) mobilization and nuclear localization of NFATc1, and they attenuated the activation of Erk1/2 and Akt. In the presence of antagonists, Th1 effector cells produced less interleukin-2 (IL-2) and gamma interferon (IFN-γ), whereas Th2 cells produced more IL-10 and IL-13. However, in NMDAR knockout mice, the presumptive expression of functional NMDARs in wild-type T cells was inconclusive. Instead, inhibition of NMDAR antagonists on the conductivity of Kv1.3 and KCa3.1 potassium channels was found. Hence, NMDAR antagonists are potent immunosuppressants with therapeutic potential in the treatment of immune diseases, but their effects on T cells have to be considered in that Kv1.3 and KCa3.1 channels are their major effectors.

Immunosuppression by N-methyl-D-aspartate receptor antagonists is mediated through inhibition of Kv1.3 and KCa3.1 channels in T cells.

B cells are important effectors and regulators of adaptive and innate immune responses, inflammation and autoimmunity, for instance in anti-NMDA-receptor (NMDAR) encephalitis. Thus, pharmacological modulation of B-cell function could be an effective regimen in therapeutic strategies. Since the non-competitive NMDAR antagonist memantine is clinically applied to treat advanced Alzheimer`s disease and ketamine is supposed to improve the course of resistant depression, it is important to know how these drugs affect B-cell function.

NMDA-receptor antagonists block B-cell function but foster IL-10 production in BCR/CD40-activated B cells.

Cigarette smoke contains numerous toxic, carcinogenic and mutagenic chemicals, stable and unstable free radicals and reactive oxygen species (ROS) which cause biological oxidative damage. Continuous exposure to those chemicals leads to immense amount of damage to the human health either directly or indirectly. A hypothesis is advanced here that a possible explanation for developing autoimmune hepatitis (AIH) is due to regular smoking for long years of time. To examine this hypothesis, I relied on an experience of a case of a patient, as well as critical reading of the literature on smoking and different autoimmune disorders. Among the autoimmune diseases, rheumatoid arthritis (RA), multiple sclerosis (MS), thyroid disease, primary biliary cirrhosis (PBC) are reported mostly among tobacco-exposed animals. The observational and theoretical knowledge strengthen the hypothesis that smoking can be one of the causes of generating autoimmune hepatitis. This hypothesis could lead to a new diagnostic category, as well as therapeutic approaches for changing the regular smoking behavior.

Bitter correlationship between autoimmune hepatitis and smoking.

Memantine is approved for the treatment of advanced Alzheimer´s disease (AD) and reduces glutamate-mediated neuronal excitotoxicity by antagonism of N-methyl-D-aspartate receptors. In the pathophysiology of AD immune responses deviate and infectious side effects are observed during memantine therapy. However, the particular effects of memantine on human T lymphocytes are unresolved. Here, we provide evidence that memantine blocks Kv1.3 potassium channels, inhibits CD3-antibody- and alloantigen-induced proliferation and suppresses chemokine-induced migration of peripheral blood T cells of healthy donors. Concurrent with the in vitro data, CD4+ T cells from AD patients receiving therapeutic doses of memantine show a transient decline of Kv1.3 channel activity and a long-lasting reduced proliferative response to alloantigens in mixed lymphocyte reactions. Furthermore, memantine treatment provokes a profound depletion of peripheral blood memory CD45RO+ CD4+ T cells. Thus, standard doses of memantine profoundly reduce T cell responses in treated patients through blockade of Kv1.3 channels. This may normalize deviant immunopathology in AD and contribute to the beneficial effects of memantine, but may also account for the enhanced infection rate.

Immunomodulation by memantine in therapy of Alzheimer's disease is mediated through inhibition of Kv1.3 channels and T cell responsiveness.

Understanding the immunopathogenesis of autoimmune and inflammatory diseases is a prerequisite for specific and effective therapeutical intervention. This review focuses on animal models of two common ocular inflammatory diseases, dry eye disease (DED), affecting the ocular surface, and uveitis with inflammation of the inner eye. In both diseases autoimmunity plays an important role, in idiopathic uveitis immune reactivity to intraocular autoantigens is pivotal, while in dry eye disease autoimmunity seems to play a role in one subtype of disease, Sjögren' syndrome (SjS). Comparing the immune mechanisms underlying both eye diseases reveals similarities, and significant differences. Studies have shown genetic predispositions, T and B cell involvement, cytokine and chemokine signatures and signaling pathways as well as environmental influences in both DED and uveitis. Uveitis and DED are heterogeneous diseases and there is no single animal model, which adequately represents both diseases. However, there is evidence to suggest that certain T cell-targeting therapies can be used to treat both, dry eye disease and uveitis. Animal models are essential to autoimmunity research, from the basic understanding of immune mechanisms to the pre-clinical testing of potential new therapies.

Dry eye disease and uveitis: A closer look at immune mechanisms in animal models of two ocular autoimmune diseases.

Non-recirculating resident memory (TRM) and recirculating T cells mount vigorous immune responses to both self and foreign antigens in barrier tissues like the skin, lung and gastrointestinal tract. Using impression cytology followed by flow cytometry we identified two TRM subsets and four recirculating T-subsets in the healthy human ocular surface. In dry eye disease, principal component analysis (PCA) revealed two clusters of patients with distinct T-cell signatures. Increased conjunctival central memory and naïve T cells characterized Cluster-1 patients, and increased CD8(+) TRMs and CD4(+) recirculating memory T cells characterized Cluster-2 patients. Interestingly these T-cell signatures are associated with different clinical features: the first signature correlated with increased ocular redness, and the second with reduced tear break up times. These findings open the door to immune-based characterization of dry eye disease and T-subset specific immunotherapies to suppress T-subsets involved in disease. They may also help with patient stratification during clinical trials of immunomodulators.

Tissue resident memory T cells in the human conjunctiva and immune signatures in human dry eye disease.

Corrigendum to "Dry eye disease and uveitis: A closer look at immune mechanisms in animal models of two ocular autoimmune diseases" [AUTREV 15-12 (2016) 1181-1192].

Tanima Bose

Lee Kong Chian School of Medicine

Nanyang Technological University

A Non-invasive Way to Isolate and Phenotype Cells from the Conjunctiva

A Chronic Autoimmune Dry Eye Rat Model with Increase in Effector Memory T Cells in Eyeball Tissue

Tanima Bose

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Nanyang Technological University

A Non-invasive Way to Isolate and Phenotype Cells from the Conjunctiva

A Chronic Autoimmune Dry Eye Rat Model with Increase in Effector Memory T Cells in Eyeball Tissue

Lee Kong Chian School of Medicine