Treatment of uveitis with recombinant human interleukin-13

Ocular Vascular Diseases: From Retinal Immune Privilege to Inflammation

The eye is an immune privileged tissue that insulates the visual system from local and systemic immune provocation to preserve homeostatic functions of highly specialized retinal neural cells. If immune privilege is breached, immune stimuli will invade the eye and subsequently trigger acute inflammatory responses. Local resident microglia become active and release numerous immunological factors to protect the integrity of retinal neural cells. Although acute inflammatory responses are necessary to control and eradicate insults to the eye, chronic inflammation can cause retinal tissue damage and cell dysfunction, leading to ocular disease and vision loss. In this review, we summarized features of immune privilege in the retina and the key inflammatory responses, factors, and intracellular pathways activated when retinal immune privilege fails, as well as a highlight of the recent clinical and research advances in ocular immunity and ocular vascular diseases including retinopathy of prematurity, age-related macular degeneration, and diabetic retinopathy.

Incorporating microglia-like cells in human induced pluripotent stem cell-derived retinal organoids

Microglia are the primary resident immune cells in the retina. They regulate neuronal survival and synaptic pruning making them essential for normal development. Following injury, they mediate adaptive responses and under pathological conditions they can trigger neurodegeneration exacerbating the effect of a disease. Retinal organoids derived from human induced pluripotent stem cells (hiPSCs) are increasingly being used for a range of applications, including disease modelling, development of new therapies and in the study of retinogenesis. Despite many similarities to the retinas developed in vivo, they lack some key physiological features, including immune cells. We engineered an hiPSC co-culture system containing retinal organoids and microglia-like (iMG) cells and tested their retinal invasion capacity and function. We incorporated iMG into retinal organoids at 13 weeks and tested their effect on function and development at 15 and 22 weeks of differentiation. Our key findings showed that iMG cells were able to respond to endotoxin challenge in monocultures and when co-cultured with the organoids. We show that retinal organoids developed normally and retained their ability to generate spiking activity in response to light. Thus, this new co-culture immunocompetent in vitro retinal model provides a platform with greater relevance to the in vivo human retina.

Unexpected connections of the IL-23/IL-17 and IL-4/IL-13 cytokine axes in inflammatory arthritis and enthesitis

The IL-23/IL-17 cytokine axis is related to spondyloarthropathy (SpA) pattern diseases that target the skin, eye, gut and joints. These share overlapping target tissues with Th2 type or allergic diseases, including the skin, eye and gut but SpA diseases exhibit distinct microanatomical topography, molecular characteristics, and clinical features including uveitis, psoriasis, apical pulmonary involvement, lower gastrointestinal involvement with colitis, and related arthritides including psoriatic arthritis and ankylosing spondylitis. Inflammatory arthritis is conspicuously absent from the Th2 diseases which are characterised IL-4/IL-13 dependent pathway activation including allergic rhino-conjunctivitis, atopic eczema, allergic asthma and food allergies. This traditional understanding of non-overlap of musculoskeletal territory between that atopic diseases and the IL-17 -mediated SpA diseases is undergoing a critical reappraisal with the recent demonstration of IL-4/IL-13 blockade, may be associated with the development of SpA pattern arthritis, psoriasiform skin disease and occasional anterior uveitis. Given the known plasticity within Th paradigm pathways, these findings suggest dynamic Th2 cytokine and Th17 cytokine counter regulation in vivo in humans. Unexpected, this is the case in peripheral enthesis and when the IL-4/13 immunological brake on IL-23/17 cytokines is removed, a SpA phenotype may emerge. We discuss hitherto unexpected observations in SpA, showing counter regulation between the Th17 and Th2 pathways at sites including the entheses that collectively indicate that the emergent reverse translational therapeutic data is more than coincidental and offers new insights into the "Th paradigms" in atopy and SpA.

Determination of Genes Related to Uveitis by Utilization of the Random Walk with Restart Algorithm on a Protein-Protein Interaction Network

Uveitis, defined as inflammation of the uveal tract, may cause blindness in both young and middle-aged people. Approximately 10–15% of blindness in the West is caused by uveitis. Therefore, a comprehensive investigation to determine the disease pathogenesis is urgent, as it will thus be possible to design effective treatments. Identification of the disease genes that cause uveitis is an important requirement to achieve this goal. To begin to answer this question, in this study, a computational method was proposed to identify novel uveitis-related genes. This method was executed on a large protein–protein interaction network and employed a popular ranking algorithm, the Random Walk with Restart (RWR) algorithm. To improve the utility of the method, a permutation test and a procedure for selecting core genes were added, which helped to exclude false discoveries and select the most important candidate genes. The five-fold cross-validation was adopted to evaluate the method, yielding the average F1-measure of 0.189. In addition, we compared our method with a classic GBA-based method to further indicate its utility. Based on our method, 56 putative genes were chosen for further assessment. We have determined that several of these genes (e.g., CCL4, Jun, and MMP9) are likely to be important for the pathogenesis of uveitis.

A novel platform for biologically active recombinant human interleukin-13 production

Interleukin-13 (IL-13) is a pleiotropic regulatory cytokine with the potential for treating several human diseases, including type-1 diabetes. Thus far, conventional expression systems for recombinant IL-13 production have proven difficult and are limited by efficiency. In this study, transgenic plants were used as a novel expression platform for the production of human IL-13 (hIL-13). DNA constructs containing hIL-13 cDNA were introduced into tobacco plants. Transcriptional expression of the hIL-13 gene in transgenic plants was confirmed by reverse transcriptase-polymerase chain reaction and Northern blotting. Western blot analysis showed that the hIL-13 protein was efficiently accumulated in transgenic plants and present in multiple molecular forms, with an expression level as high as 0.15% of total soluble protein in leaves. The multiple forms of plant-derived recombinant hIL-13 (rhIL-13) are a result of differential N-linked glycosylation, as revealed by enzymatic and chemical deglycosylation, but not of disulphide-linked oligomerization. In vitro trypsin digestion indicated that plant rhIL-13 was more resistant than unglycosylated control rhIL-13 to proteolysis. The stability of plant rhIL-13 to digestion was further supported with simulated gastric and intestinal fluid digestion. In vitro bioassays using a factor-dependent human erythroleukaemic cell line (TF-1 cells) showed that plant rhIL-13 retained the biological functions of the authentic hIL-13 protein. These results demonstrate that transgenic plants are superior to conventional cell-based expression systems for the production of rhIL-13. Moreover, transgenic plants synthesizing high levels of rhIL-13 may prove to be an attractive delivery system for direct oral administration of IL-13 in the treatment of clinical diseases such as type-1 diabetes.

Increased interleukin-13 expression in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a systemic granulomatous disorder of unknown origin. Lymphocytic inflammation is dominated by expression of Th1 type cytokines such as tumour necrosis factor alpha (TNFalpha). Interleukin 13 (IL-13) is a Th2 cytokine which is expressed by CD4+ T cells and has been shown to suppress TNFalpha in human blood monocytes. The role of IL-13 as a possible anti-inflammatory cytokine in sarcoidosis was investigated.

METHODS

mRNA expression of IL-13, IL-4, IL-10, and TNFalpha in bronchoalveolar lavage (BAL) fluid cells and peripheral mononuclear blood cells (PBM) of 18 patients with sarcoidosis and nine healthy controls was assessed using RT-PCR. In addition, IL-13 protein levels in BAL cell culture supernatants from 12 patients and all controls were measured and immunocytochemistry of IL-13 protein was performed in BAL fluid cells of eight patients. TNFalpha concentrations were measured with and without stimulation with recombinant human (rh) IL-13, rhIL-10, and lipopolysaccharide (LPS).

RESULTS

IL-13 mRNA expression was significantly increased in BAL cells and PBM of patients compared with controls (p<0.05). No significant difference was found in IL-4 mRNA or IL-10 mRNA expression in BAL fluid cells or PBM between the two groups. TNFalpha mRNA expression was significantly higher in BAL fluid cells of patients than controls (p<0.05). IL-13 protein levels in BAL cell culture supernatants were slightly raised in half the patients investigated but in only two controls. Immunocytochemistry detected IL-13 protein in alveolar macrophages of patients. IL-13 led to decreased TNFalpha concentrations (p<0.05).

CONCLUSIONS

IL-13 expression is increased in BAL cells and PBM in sarcoidosis and IL-13 is secreted from BAL cells. Alveolar macrophages may be the cellular source. These data suggest that IL-13 might have an anti-inflammatory effect by acting on TNFalpha.

Cytokines in immunotherapy of experimental uveitis

A better understanding of the basic mechanisms of uveitis and of the role of cytokines in experimental ocular inflammation autoimmune diseases should allow us to define new approaches for therapy. Modulation of the cytokine network by either blocking cytokine activity or administration of regulatory Th2 cytokines has shown its efficacy in several experimental autoimmune diseases including uveitis. However, cytokines present pleiotropic activities and thus may exert different effects depending on the autoimmune diseases, making interventions on their production complex. Anti-cytokine therapy or a combination of anti-cytokine drugs, antibodies, and cytokine gene therapy to synergize the therapeutical effects of other treatments appear to be of interest. Improvements in drug delivery and in biotechnology will also allow us to elaborate new and safe immunomodulatory strategies.

Cytokines in posterior uveitis: an update

T helper (Th) lymphocytes differentiate into two distinct subsets--Th1 and Th2--as defined by functional abilities and cytokine profiles. The functional differences between Th subsets are explained primarily through the activities of the cytokines they secrete. Interferon-gamma (IFN-gamma) is the signature cytokine of Th1 cells, which also produce interleukin-2 (IL-2) and tumor necrosis factor-beta (TNF-beta). IL-4 is the corresponding signature cytokine of Th2 cells, which also secrete IL-5, IL-6, IL-9, and IL-13. Recently, a few transcription factors have been identified that not only control the expression of cytokines of a particular type but also repress cytokines of other types. Human Th1 and Th2 cells not only produce a different set of cytokines but also exhibit distinct functional properties and the preferential expression of some activation markers. Pathophysiologically, the two subsets have been found to be mutually antagonistic. Various Th1 and Th2 cytokines appear to play an important role in the etiopathogenesis of posterior uveitis and its animal model, experimental autoimmune uveitis (EAU). The exact contribution of these mediators to uveitis remains to be defined. Recent studies suggest that a shift from Th1- to Th2-dominated response could be of therapeutic benefit. This review evaluates various studies in which uveitopathogenic and therapeutic potentials of various Th1 and Th2 cytokines have been investigated.

In vitro interleukin-13 production by peripheral blood in patients with newly diagnosed insulin-dependent diabetes mellitus and their first degree relatives

It is generally accepted that proinflammatory cytokines secreted by macrophages/monocytes as well as cytotoxic T cells are responsible for pancreatic B-cell destruction in animal models of autoimmune diabetes and presumably in insulin-dependent diabetes mellitus (IDDM) in humans. The aim of the present study was to evaluate the production of interleukin (IL)-13-a Th2 cells derived anti-inflammatory cytokine, by peripheral blood of newly diagnosed IDDM patients and their first degree relatives with a low or high risk of IDDM development. The study was carried out in 20 patients with a recent onset of type 1 diabetes, their first degree relatives with high (with DRB1*03 and/or DRB1*04 HLA class II alleles and two or more autoantibodies directed against pancreatic B-cell antigens) (n = 20) or a low (with DQB1*0602 allele) risk of type 1 diabetes development (n = 10) and a control age matched group of healthy volunteers (n = 18). IL-13 concentrations in supernatant of 72 h cultures of peripheral blood after incubation with phytohemagglutinin (PHA) or PHA+ insulin were quantified by enzyme-linked immunosorbent assay (ELISA). The levels of IL-13 in the supernatants were significantly lower in at high risk of IDDM first degree relatives of diabetic patients (P < 0.02), higher in subjects with low genetic risk of diabetes type 1 (P < 0.02), and normal in IDDM patients in comparison to the control group. We have also observed that the adding of human insulin to the cultures resulted in a significant increase of in vitro IL-13 production in prediabetics, but not in the other studied groups. In conclusion our findings suggest that the IL-13 alterations could play an important role in the pathogenesis of type 1 diabetes. We would speculate that IL-13 as an anti-inflammatory cytokine and a mediator of the Th2 pathway could be the potential therapeutic approach in the prevention of type 1 diabetes.