The Role of Insulin-like Growth Factor (IGF) System in the Corneal Epithelium Homeostasis-From Limbal Epithelial Stem Cells to Therapeutic Applications.

The corneal epithelium, comprising three layers of cells, represents the outermost portion of the eye and functions as a vital protective barrier while concurrently serving as a critical refractive structure. Maintaining its homeostasis involves a complex regenerative process facilitated by the functions of the lacrimal gland, tear film, and corneal nerves. Crucially, limbal epithelial stem cells located in the limbus (transitional zone between the cornea and the conjunctiva) are instrumental for the corneal epithelium integrity by replenishing and renewing cells. Re-epithelialization failure results in persistent defects, often associated with various ocular conditions including diabetic keratopathy. The insulin-like growth factor (IGF) system is a sophisticated network of insulin and other proteins essential for numerous physiological processes. This review examines its role in maintaining the corneal epithelium homeostasis, with a special focus on the interplay with corneal limbal stem cells and the potential therapeutic applications of the system components.

The immunology of corneal limbal stem cells: the up-to-date approach to stem cell transplantation.

Limbal epithelial stem cells (LSC, LESC) are multipotent cells used as regenerative treatment of the cornea in patients with limbal epithelial stem cell deficiency (LSCD, LESCD). There are different types of stem cell grafting including cultivated limbal epithelial transplantation (CET) and simple limbal epithelial transplantation (SLET). The outcomes of the techniques have been assessed as similar, with differences in the sample size required during the procedures. The most important culture components for stem cell cultivation include 3T3 murine fibroblasts, human amniotic membrane (HAM), fibrin gel, and culture medium. The culture medium may be enriched with serum or not; however, xenobiotic-free materials are preferred because of the low risk of pathogen transmission. Multiple studies have defined molecules important for maintaining the function of LSC including C/EBP δ, Bmi-1, p63 α, interleukins (IL-6), epithelial structural proteins - keratins, and antibodies against epidermal growth factor receptor (EGFR). The cell phenotype of LSC has been described with factors of transplantation success rate such as a high percentage of p63 positive cells. The article emphasizes the role of recipient tissue preparation, modern cultivation techniques and pathophysiological processes in LSC transplantation effectiveness.

Novel therapies for diabetic retinopathy.

Diabetes mellitus (DM) is a metabolic disease characterized by high blood glucose levels as well as microvascular and macrovascular changes. According to the latest statistics the growth of DM incidence is very fast. Diabetic retinopathy (DR) - one of the common DM complications - is the leading cause of blindness among professionally active people. Traditional treatment of DR including drugs controlling hyperglycemia, laser therapy, vitrectomy, and intravitreal injections of anti-VEGF is effectively administered with the effect of neovascularization and macular edema prevention. However, new potential DR therapies - focusing on a longer therapeutic effect and potentially fewer side effects - are being widely investigated. Gene therapy - targeting retinal vasculopathy or targeting retinal protection, mesenchymal stem cell injections, SGLT2 inhibitors, and islet cell transplantation have been proved to stop DR progression. The majority of the new treatment research was performed on an animal model and did not reach the final study stage. A further future human model and randomized studies with optimized delivery vectors will hopefully confirm positive outcomes of the new DR therapies.

Novel approach to antiangiogenic factors in age-related macular degeneration therapy.

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss among the population above 85 worldwide. There are two main types of AMD: neovascular and dry AMD. Neovascular AMD leads to macular changes resulting from abnormal choroidal neovascularization. Untreated neovascular AMD leads to scar formation and irreversible sight deterioration. Dry AMD in consequence leads to atrophic changes of the macula. The last decades brought a breakthrough in the therapy of neovascular age-related macular degeneration by introduction of, firstly, photodynamic therapy and, later, anti-VEGF agents administered intravitreally in order to stop neoangiogenesis. However, the treatment of dry AMD is still challenging. Among the directions in dry AMD treatment, the most promising are complement cascade inhibitors and complement cascade targeted gene therapy. In the article we outline the main directions in up-to-date experimental and practical approaches to wet and dry AMD therapy with the emphasis on antiangiogenic factors and gene therapy focused on the inhibition of pathological angiogenesis.

The Feasibility of Surface Electromyography in Monitoring Orbicularis Oculi Recovery after Anterior Approach Levator Aponeurosis Advancement.

INTRODUCTION: In this article, we propose a new application for eyelid surface electromyography (sEMG). By placing the electrode in the mid-pretarsal area of the upper eyelid, one can easily perform a fast examination and achieve repeatable results. We believe that this technique may increase the feasibility of eyelid sEMG in clinical practice. METHODS: 126 sEMG examinations of the upper eyelid were performed by using the above-described method. Thirty-nine controls and 29 ptotic patients were enrolled. The controls underwent one measurement while the ptotic patients were employed for four sessions: Before anterior approach levator aponeurosis advancement (LAA), 2 weeks, 3 months, and more than 6 months after surgery. The relaxation and maximal contraction of the orbicularis oculi muscle (OOM) using root mean square (RMS) values were measured. RESULTS: The results showed a statistically significant decrease in RMS values of the maximal contraction of the OOM 2 weeks after surgery (p < 0.05) and 3 months after surgery (p = 0.03). Six months postoperatively, there were no statistically significant differences in OOM activity compared to preoperative values (p = 0.2). CONCLUSIONS: Eyelid sEMG may be a useful diagnostic tool in post-operative OOM recovery monitoring. sEMG parameters of the maximal contraction of the OOM normalize within 6 months after anterior approach LAA. Electrode placement in the mid-pretarsal area of the upper eyelid offers several advantages and therefore may enhance the feasibility of sEMG in clinical practice.

New perspectives of immunomodulation and neuroprotection in glaucoma.

Glaucoma is the neurodegenerative disease of retinal ganglion cells. The main risk factor for glaucoma is increased intraocular pressure. The processes leading to cell death due to presence of the injury factor comprise multiple molecular mechanisms, as well as the immunological response. The knowledge of immunological mechanisms occurring in glaucomatous degeneration makes it possible to introduce glaucoma treatment modulating the cellular degradation. The glaucoma treatment of the future will make it possible not only to lower the intraocular pressure, but also to moderate the intracellular mechanisms in order to prevent retinal cell degeneration. Citicoline is a drug modulating glutamate excitotoxicity that is already in use. Rho kinase inhibitors were found to stimulate neurite growth and axon regeneration apart from lowering intraocular pressure. The complementary action of brimonidine is to increase neurotrophic factor (NTF) concentrations and inhibit glutamate toxicity. Immunomodulatory therapies with antibodies and gene therapies show promising effects in the current studies. The supplementation of NTFs prevents glaucomatous damage. Resveratrol and other antioxidants inhibit reactive oxygen species formation. Cell transplantation of stem cells, Schwann cells and nerve extracts was reported to be successful so far. Our review presents the most promising new strategies of neuroprotection and immunomodulation in glaucoma.

Immunological and molecular basics of the primary open angle glaucoma pathomechanism.

Glaucoma is a degenerative process of the optic nerve. Increased intraocular pressure is believed to be the main factor leading to the glaucomatous damage. The in vitro and in vivo animal glaucoma research models provide insight into the molecular changes in the retina in response to the injury factor. The damage is a complex process incorporating molecular and immunological changes. Such changes involve NF kB activity and complement activation. The processes affect the human antigen, JNK, MAPK, p53, MT2 and DBA/2J molecular pathways, activate the autophagy processes and compromise neuroprotective mechanisms. Activation and inhibition of immunological responses contribute to cell injury. The immunological mechanisms of glaucomatous degeneration include glial response, the complement, tumor necrosis factor α (TNF-α) pathways and toll-like receptors athways. Oxidative stress and excitotoxicity are factors contributing to cell death in glaucoma. The authors present an up-to-date review of the mechanisms involved and update on research focusing on a possible innovative glaucoma treatment.

Bionic eye review - An update.

PURPOSE: To date, reviews of bionic eye have concentrated on implants which were used in human trials in the developed countries. This is the main restriction of this systematic review examines, however this review discusses worldwide advances in retinal prosthetic research, assesses engineering features and clinical progress of recent implant trials, and identifies potential future research areas in the field of bionic implants. METHODS: A literature review searching PubMed, Google Scholar, and IEEExplore was performed using the PRISMA Guidelines for Systematic Review. We included peer-reviewed papers in the review which demonstrated progress in human or animal trials and papers with described innovative bionic eye engineering design. For each trial, a characteristic of the device, engineering solution, and latest clinical outcomes were presented. RESULTS: Eleven prosthetic projects fulfilled met our inclusion criteria and were ordered by stimulation location. Four have recently finished human trials, three are having conducted multi- or singlecenter human trials, and three are in preclinical animal testing stage. FDA has approved Argus II (FDA 2013, CE 2011); the Alpha-IMS (CE 2013) has been approved and obtained BCVA with Landolt-C test has taken into a multicenter clinical research. New approaches will be presented using alternating magnetic fields, low-intensity focused ultrasounds, optogenetics, implementing ionic gradients across neural cell membranes or influencing neurotransmitter levels will be presented in the review. CONCLUSION: Several bionic eye have successfully achieved visual perception in animals and/or humans. However, many things need to be improved and engineering difficulties are to be resolved before bionic eye will be capable of fully and safely bring back vision functions. New approaches could improve medical outcome of future bionic eye.

Therapeutic potential of curcumin in eye diseases.

Curcumin (diferuloylmethane) derived from the rhizome of Curcuma longa L. has been used for thousands of years in traditional Chinese medicine and Ayurvedic medicine in Asian countries to treat liver diseases, rheumatoid diseases, diabetes, atherosclerosis, infectious diseases and cancer. It exhibits a wide range of pharmacological properties, which include antioxidant, anti-inflammatory, antimutagenic, antimicrobial and anticancer activity. Herein the mechanisms of curcumin impact on oxidative stress, angiogenesis and inflammatory processes are described indicating that curcumin use may inhibit those pathological conditions and restore body homeostasis. Its effectiveness was also proved for major eye diseases. In this review, the influence of curcumin on eye diseases, such as glaucoma, cataract, age-related macular degeneration, diabetic retinopathy, corneal neovascularization, corneal wound healing, dry eye disease, conjunctivitis, pterygium, anterior uveitis are reported. The analysis of a number of clinical and preclinical investigations indicates that curcumin may be used as a therapeutic agent in the treatment of various eye disorders.

In search of chondrocyte-specific antigen.

The purpose of this work was to establish, whether rat chondrocyte associated antigen, transmembrane Tmp21 protein belonging to the p24 protein family may immunize rats and thus be included into the panel of immunogens potentially involved in cartilage pathology. For immunization of rats extract from cultured chondrocytes containing surface chondrocyte proteins suspended in incomplete Freund's adjuvant was used. Control animals were injected with incomplete Freund's adjuvant without chondrocyte extract. Morphological observations indicated that both in control and experimental animals occurred subperiosteal resorption of bone, suggesting that it arised as the response to adjuvant. In trachea, however, resorption of cartilage and inflammatory changes in the respiratory epithelium and lamina propria were present only in animals exposed to antigen. Unexpectedly, sera from immunized rats strongly reacted with other antigen, which we were able to identify by Western blot and protein sequencing as cartilage oligomeric matrix protein (COMP). COMP is attached to chondrocyte membrane by integrins and its presence in chondrocyte extract is not surprising. Antibody response to COMP raises a question whether the observed changes in tracheal cartilage and epithelium represent anti-COMP reaction or were caused by some other, no specified factors. COMP is used as the marker of osteoarthritis progression, but its role in polychondritis, cartilage pathology involving i.a. tracheal cartilage resorption remains unknown. Thus, our observations may serve as the starting point for future studies in this direction.

Antigenic and immunogenic properties of chondrocytes. Implications for chondrocyte therapeutic transplantation and pathogenesis of inflammatory and degenerative joint diseases.

In physiological conditions chondrocytes are protected from contact with immunocompetent cells by the extracellular matrix, and transplanted fragments of allogeneic cartilage are not rejected. Cartilage produced by allogeneic chondrocytes, however, evokes the immune response of the recipient and is gradually destroyed. Immunisation by allogeneic chondrocytes is induced by the contact of their surface molecules with cells of the immune system. Chondrocytes constitutively express class I and, in some species, class II major histocompatibility complex (MHC) molecules. Expression of MHC class II molecules is induced in vitro by pro-inflammatory cytokines and in vivo in the course of the rejection of transplanted allogeneic cartilage. Low level of MHC class II molecules is found on the surface of human articular chondrocytes in patients with rheumatoid arthritis and osteoarthritis. Cartilage produced by transplanted allogeneic chondrocytes is destroyed by monocytes/macrophages and cytotoxic T and natural killer (NK) cells. NK cells show spontaneous cytotoxic reactivity against isolated chondrocytes and participate in the rejection of transplanted isolated chondrocytes. Chondrocytes express molecules that can serve as potential antigens in inflammatory joint diseases. Chondrocytes express cartilage-specific membrane antigen (CH65), human cartilage glycoprotein-39 (HC gp-39), hyaluronan binding adhesion molecule CD44, thymocyte antigen-1 (Thy-1) - CD90, signal transducer - CD24, lymphocyte function-associated antigen-3 (LFA-3) - CD58, and type I transmembrane protein Tmp21. On the other hand, although chondrocytes express major histocompatibility complex (MHC) class I and class II molecules, they can also exert immunosuppressive and immunomodulatory effects on immunocompetent cells. Isolated chondrocytes do not trigger an efficient allogeneic immune response in vitro and suppress, in a contact-dependent manner, proliferation of activated T cells. This suppression is associated with the expression by chondrocytes of multiple negative regulators of immune response. Chondrocytes express programmed death-ligand (PD-L), chondromodulin-I and indoleamine 2,3-dioxygenase (IDO), molecules that promote self-tolerance and suppress the immune system.

The impact of age, sex, blepharitis, rosacea and rheumatoid arthritis on Demodex mite infection.

INTRODUCTION: Two human-specific Demodex species have been described: Demodex folliculorum and Demodex brevis. A medical condition caused by the presence of Demodex is called demodicosis. MATERIAL AND METHODS: The study material comprised eyelashes collected from 1499 patients. RESULTS: Demodex sp. infection was revealed in 47% of patients (487 women and 216 men). We determined the following rates of infection by age groups: 1-25 (8% of infected subjects), 26-40 (36%), 41-55 (50%), 56-70 (67%), over 70 (77%). The sex of the subjects was not identified as a factor conducive to infection (p = 0.108), while their age was positively correlated with the risk of infection (p < 0.005). The 1499 study subjects included patients with blepharitis, rosacea, and rheumatoid arthritis. The study investigated the extent to which the above-mentioned conditions affect the risk of Demodex infection. Applying the method of logistic regression, the infection probability was estimated, depending on the age, sex, and comorbidities such as blepharitis, rosacea, and rheumatoid arthritis. Patients suffering from blepharitis were found to have a nearly 2.5-fold higher risk of Demodex infection than those without blepharitis, and the risk for rosacea patients was determined as three-fold higher than that of the general population. CONCLUSIONS: Blepharitis and rosacea are risk factors for Demodex infection.

The effect of pentoxifylline on L-1 sarcoma tumor growth and angiogenesis in Balb/c mice.

Methyloxantines are present in many herbs and vegetal foods, among them in tea, coffee and chocolate. Previous studies revealed that theophylline and theobromine have anti-angiogenic properties. Anti-tumor properties of theobromine were also described. Pentoxifylline (3,7-dimethyl-1-(5-oxohexyl)xanthine, PTX) is a synthetic xanthine derivative. It is a phosphodiesterase inhibitor and has various anti-inflammatory abilities. Pentoxifylline is widely used in therapy of inflammatory arterial diseases such as intermittent claudication of upper and lower limbs as well as in coronary heart disease. The aim of our research was to evaluate the effect of pentoxifylline (individually and in combination with non-steroidal anti-inflammatory drug sulindac), on L-1 sarcoma angiogenic activity and tumor formation in syngeneic Balb/c mice. Pre-incubation of tumor cells for 90 min with various PTX concentrations resulted in dose-dependent decrease of their ability to induce newly-formed blood vessels after transplantation into the skin of recipient mice. Administration of PTX to mice, recipients of tumor cells, slows tumor growth and reduces its volume. Synergistic inhibitory effect of PTX and sulindac, expressed as % of tumors sixth and thirteen day after subcutaneous grafting of L-1 sarcoma into syngeneic Balb/c mice, was observed.

Stem cells in regenerative medicine - from laboratory to clinical application - the eye.

Stem cells are currently one of the most researched and explored subject in science. They consstitue a very promising part of regenerative medicine and have many potential clinical applications. Harnessing their ability to replicate and differentiate into many cell types can enable successful treatment of diseases that were incurable until now. There are numerous types of stem cells (e.g. ESCs, FSCs, ASCs, iPSCs) and many different methods of deriving and cultivating them in order to obtain viable material. The eye is one of the most interesting targets for stem cell therapies. In this article we summarise different aspects of stem cells, discussing their characteristics, sources and methods of culture. We also demonstrate the most recent clinical applications in ophthalmology based on an extensive current literature review. Tissue engineering techniques developed for corneal limbal stem cell deficiency, age-related macular degeneration (AMD) and glaucoma are among those presented. Both laboratory and clinical aspects of stem cells are discussed.

Synergistic Activity for Natural and Synthetic Inhibitors of Angiogenesis Induced by Murine Sarcoma L-1 and Human Kidney Cancer Cells.

Tumor angiogenesis is an important link in the process of tumor growth and metastasis. A number of substances with an anti-angiogenic activity has been described, but their efficiency remains low. Many researchers believe that a better therapeutic effect could be achieved using a cocktail of several anti-angiogenic agents, having different points of action. A lot of synthetic and natural products of plant and animal origin have anti-tumor and anti-angiogenic properties. The aim of the present study was to evaluate the effect of some combinations of angiogenesis inhibitors on the growth and neovascularization of murine sarcoma L-1 , and on angiogenesis induced in the mouse skin by grafting of human renal cancer. The influence of theobromine, sulindac and its metabolite sulindac sulfone, chlorogenic acid, and shark liver oil on the afferent and efferent angiogenesis pathways was tested. Individually, all of these substances suppressed tumor growth and angiogenesis. Synergy was found for a combination of theobromine, sulindac, and chlorogenic acid (L-1 sarcoma tumor growth), and for theobromine with sulindac sulfone or with shark liver oil, which were given to the mice grafted with human renal cancer cells (angiogenesis). No synergistic effects were shown after preincubation with tumor cells and inhibitors.

Angiogenesis modulation by exogenous antioxidants.

Co-operation of the endogenous and exogenous defense system maintains redox homeostasis and is essential for health. The endogenous defense system includes enzymatic (e.g. superoxide dismutase, catalase) and non-enzymatic, low molecular-weight scavengers (e.g. glutathione, ascorbic acid). Pathogenesis of many serious diseases (e.g. cancer, ischemic heart disease) includes oxidative stress which can disturb angiogenesis, the process of formation of new blood vessels sprouting from the existing one. Antioxidants, through reduction of oxidative stress and influence on neovascularization, may modulate progress and results of therapy in those diseases where such processes play an important role. Herein the impact of exogenous antioxidants on angiogenesis and factors modulating this process is presented. Most synthetic antioxidants whose activity has been described (namely N-acetylcysteine, pentoxifylline, synthetic analogue of curcumin, synthetic analogue of epigallocatechin-3 gallate [EGCG], tripertenoids) exert an inhibitory effect on neovascularization. A similar effect was also exhibited by several natural origin antioxidants (e.g. resveratrol, EGCG), which suggests that their application in therapy might normalize excessive angiogenesis. Some natural origin antioxidants e.g. purple coneflower and preparations consisting of natural antioxidants such as Padma 28 and Immunal forte increase a too low baseline level of angiogenesis and decreases a too high level. These preparations exert a regulatory effect on and may normalize neovascularization. They can be used in the case of diseases associated with too low or too high angiogenesis.

Immunomodulation on the ocular surface: a review.

The increasing understanding of immune mechanisms changed our perception of the ocular surface, which is now considered a compartment of the common mucosal immune system. It offered the possibility to alter the physiological immune response on the ocular surface and effectively combat inflammation, which impairs stability of the tear film and causes tear hyperosmolarity, causing symptoms of dry eye disease. The paper provides an overview of ocular surface anatomy and physiology, explains the underlying mechanisms of dry eye disease and discusses novel and promising treatment modalities, such as cyclosporine A, biological therapies using autologous serum and various growth factors as well as experimental treatment methods which are currently being investigated.

The modulatory influence of some Echinacea-based remedies on antibody production and cellular immunity in mice.

UNLABELLED: Echinacea purpurea-containing remedies are herbal medicines used in respiratory tract infections and several inflammatory conditions as enhancers of non-specific and modulators of specific cellular immunity. They also exert anti-inflammatory, anti-viral, and anti-microbial activity. The aim of the present study was to compare the in vivo influence of orally administered three Echinacea purpurea-based remedies (IMMUNAL drops, ECHINACEA FORTE drops, IMMUNAL FORTE tablets) on some parameters of cellular and humoral immunity in mice. RESULTS: Feeding mice for seven days with IMMUNAL drops resulted in enhanced anti-SRBC antibody production and modulatory effect on proliferative response to PHA of their splenic lymphocytes. No stimulatory effect was observed on splenocytes chemokinesis. Mice fed with ECHINACEA FORTE drops presented enhanced response to PHA of their splenocytes. However, contrary to the previous group, no enhancement of antibody production was observed. In this group, lymphocyte-induced immunological angiogenesis (LIA) and chemokinesis (spontaneous migration - SM) of spleen lymphocytes was diminished after feeding mice with both doses (LIA) or with a higher dose (SM) of remedy. Lymphocyte-induced immunological angiogenesis activity of splenocytes collected from animals fed with prophylactic and therapeutic IMMUNAL FORTE tablet doses did not differ from the controls.

Reactive oxygen species and synthetic antioxidants as angiogenesis modulators: Clinical implications.

Angiogenesis is important for normal functioning of organism and its disturbances are observed in many diseases, called angiogenesis-related states. Reactive oxygen species (ROSs) play an important role in physiology, but high level of cellular ROSs is cytotoxic and mutagenic for the cells, i.e. it can lead to oxidative stress. In this review we discuss close relationship between ROSs and angiogenesis process. Substances counteracting free radicals or their action and oxidative stress are known as antioxidants. We postulate that antioxidants, by affecting angiogenesis, may modulate therapy results in the case of angiogenesis-related disease. Herein, we present some antioxidant preparations of synthetic (N-acetylcysteine, curcumin and its analogs, Probucol, oleane tripertenoid, EGCG synthetic analogs) and nature-identical (vitamin E and C) origin. Then, we analyze their angiogenic properties and their multidirectional molecular effect on angiogenesis. Most preparations reduce neovascularization and diminish the level of proangiogenic molecules, downregulating signaling pathways related to angiogenesis. Moreover, we discuss studies concerning anticancer properties of presented synthetic antioxidants and their application in several angiogenesis-related diseases. We conclude that therapy in angiogenesis-related diseases should be planned with consideration of the angiogenic status of the patient.

Is it appropriate to perform anterior segment reconstruction in amblyopic eye following penetrating trauma in childhood?

We present a case of diagnostic and surgical management in an amblyopic eye following penetrating trauma in childhood. The 75-year-old female patient experienced the trauma at the age of 4. The eye was amblyopic, but after thorough investigations (ultrasonography, ultrabiomicroscopy, visual evoked potentials) the eye underwent anterior segment reconstruction. Visual evoked potentials allowed us to assess optic nerve function, while ultrabiomicroscopy allowed us to plan the surgical procedure. Although we observed quite a small visual acuity improvement, the subjective improvement reported by the patient was fairly significant (NEI VFQ-25 questionnaire). The cosmetic effect of the black pupil was also important.