Protein kinase CK2: a potential therapeutic target for diverse human diseases.

CK2 is a constitutively active Ser/Thr protein kinase, which phosphorylates hundreds of substrates, controls several signaling pathways, and is implicated in a plethora of human diseases. Its best documented role is in cancer, where it regulates practically all malignant hallmarks. Other well-known functions of CK2 are in human infections; in particular, several viruses exploit host cell CK2 for their life cycle. Very recently, also SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been found to enhance CK2 activity and to induce the phosphorylation of several CK2 substrates (either viral and host proteins). CK2 is also considered an emerging target for neurological diseases, inflammation and autoimmune disorders, diverse ophthalmic pathologies, diabetes, and obesity. In addition, CK2 activity has been associated with cardiovascular diseases, as cardiac ischemia-reperfusion injury, atherosclerosis, and cardiac hypertrophy. The hypothesis of considering CK2 inhibition for cystic fibrosis therapies has been also entertained for many years. Moreover, psychiatric disorders and syndromes due to CK2 mutations have been recently identified. On these bases, CK2 is emerging as an increasingly attractive target in various fields of human medicine, with the advantage that several very specific and effective inhibitors are already available. Here, we review the literature on CK2 implication in different human pathologies and evaluate its potential as a pharmacological target in the light of the most recent findings.

Role of Matrix Metalloproteinase 9 in Ocular Surface Disorders.

OBJECTIVES: (1) To explore the role and significance of Matrix Metalloproteinase 9 (MMP-9), a proteolytic enzyme, in various ocular surface diseases of inflammatory, infectious, and traumatic etiology (2), to further elucidate the molecular mechanisms responsible for its overexpression in ocular surface disease states, and (3) to discuss possible targets of therapeutic intervention. METHODS: A literature review was conducted of primary sources from 1995 onward using search results populated from the US National Library of Medicine search database. RESULTS: MMP-9 overexpression has been found in in vitro and in vivo models of dry eye disease (DED), corneal ulceration, microbial keratitis, corneal neovascularization, ultraviolet light-induced radiation, and a host of additional surface pathologies. MMP-9 is involved in an intricate signal transduction cascade that includes induction by many proinflammatory molecules including interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-a), nuclear factor kappa light chain enhancer of activated B cells (NF-kB), platelet-activating factor, activator protein 1 (AP-1), and transforming growth factor beta (TGF-B). MMP-9 expression is blunted by a diverse array of molecular factors, such as tissue inhibitors of metalloproteinases, cyclosporine A (CyA), PES_103, epigalloccatechin-3-gallate (EGCG), N-acetylcysteine (NaC), ascorbate, tetracyclines, and corticosteroids. Inhibition of MMP-9 frequently led to improvement of ocular surface disease. CONCLUSIONS: Novel insights into the mechanistic action of MMP-9 provide potential for new therapeutic modulations of ocular surface diseases mediated by its overexpression.

Utility of angiotensin-converting enzyme activity in aqueous humor in the diagnosis of ocular sarcoidosis.

PURPOSE: Many studies include elevated activity of angiotensin-converting enzyme (ACE) in serum in sarcoidosis and in ocular sarcoidosis as well, but there are only a few analyzing ACE activities in aqueous humor. The aim of this study is to illuminate the diagnostic value of ACE in aqueous humor in patients with ocular sarcoidosis. METHODS: We analyzed twenty patients with ocular sarcoidosis and 18 patients with nonocular involvement. All patients have biopsy-positive sarcoidosis of the lungs and/or mediastinal lymph nodes. Blood samples for ACE serum levels were obtained from all patients. Aqueous humor samples were taken by paracentesis with a 25-gauge needle in local anesthesia. With appropriate statistical tests, we compared ACE activity in serum and aqueous humor in patients with and without ocular sarcoidosis. RESULTS: The majority of our patients with ocular sarcoidosis were female (12/20), also in the group with systemic sarcoidosis and without ocular involvement (12/6). Mean age of the whole analyzed group of sarcoidosis patients was 45 ± 6 years. There is no statistically significant difference in ACE activity in serum between two groups of patients (with and without ocular sarcoidosis). There is statistically significant difference in ACE activity in aqueous humor among patients with ocular and nonocular sarcoidosis. ACE activity in aqueous humor is significantly higher in patients with ocular sarcoidosis. CONCLUSION: Increased ACE activity in aqueous humor can point to a diagnosis of ocular sarcoidosis, without the need for ocular biopsy.

Occupational pesticide exposure and adverse health effects at the clinical, hematological and biochemical level.

AIMS: Although epidemiological studies have investigated associations between occupational pesticide exposures and different adverse health outcomes, they have rarely assessed individuals at two time-points of a same crop season with different pesticide use. MATERIAL AND METHODS: Clinical symptoms, physical examination signs, hematological and clinical chemistry parameters were measured in 189 intensive agriculture workers and 91 healthy control subjects from Almeria coastline (Southeastern Spain) to evaluate potential effects of pesticide exposure. KEY FINDINGS: Greenhouse workers showed an increased risk of ocular and skin signs relative to controls at the period of high pesticide exposure (OR: 4.80 and 2.87, respectively); however, no differences were observed for clinical symptoms. A greater risk for ECG changes (OR: 3.35) and altered spirometry (OR: 5.02) was found at the period of low exposure. Erythrocyte acetylcholinesterase was significantly decreased in greenhouse workers relative to controls in both periods. Assessment of hematological parameters revealed increased counts of erythrocytes, leukocytes, platelets and hemoglobin in greenhouse workers relative to controls, and also in the period of high versus low pesticide exposure. Changes in clinical chemistry parameters included decreased levels of glucose, creatinine, total cholesterol, triglyceride and alkaline phosphatase in greenhouse workers relative to controls; however, these parameters were raised in the period of high versus low pesticide exposure. SIGNIFICANCE: These findings suggest that chronic occupational exposure to pesticides of lower toxicity than former compounds under integrated production systems elicit mild toxic effects, particularly targeting the skin and eyes, as well as subtle subclinical (biochemical) changes of unknown long-term consequences.

Subconjunctival injection of XG-102, a JNK inhibitor peptide, in patients with intraocular inflammation: a safety and tolerability study.

PURPOSE: We aimed to investigate the safety, tolerability, and systemic diffusion of a single escalating dose of XG-102 (a 31-D-amino-acid peptide inhibiting JNK pathway activation), administered subconjunctivally in the treatment of post-surgery or post-trauma intraocular inflammation. METHODS: This is a dose-escalating, tolerance Phase Ib study. Twenty patients with post-surgery or post-traumatic intraocular inflammation were assigned to 1 of the 4 dose escalating (45, 90, 450, or 900 µg XG-102) groups of 5 patients each. Patients were evaluated at 24, 48 h, 8, and 28 days following the administration of XG-102, including laboratory tests, standard eye examinations, vital signs, and occurrence of adverse events. A single plasma quantification of XG-102 was performed 30 min after administration, according to previous pharmacokinetics studies performed on volunteers. RESULTS: A total of 17 non-serious adverse events, considered unrelated to the study treatment, were reported for 10 patients. The adverse event incidence was not related to the drug dose. All patients experienced a decrease in intraocular inflammation as of 24 h post-administration and this decrease was sustained up to 28 days thereafter. No patient required local injection or systemic administration of corticoids following the administration of XG-102. XG-102 was undetectable in the first 3 dose groups. In the fourth-dose group (900 µg) the XG-102 plasma levels were above the limit of detection for 3 patients and above the limit of quantification for 1 patient. CONCLUSIONS: In this first clinical trial using XG-102, administered as a single subconjunctival injection as adjunct therapy, in patients with recent post-surgery or post-trauma intraocular inflammation is safe and well tolerated. Further studies are required to evaluate its efficacy.

ADAMTS-18: a metalloproteinase with multiple functions.

ADAMTS-18 is a member of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family of proteases, which are known to play important roles in development, angiogenesis and coagulation; dysregulation and mutation of these enzymes have been implicated in many disease processes, such as inflammation, cancer, arthritis and atherosclerosis. Mutations of ADAMTS-18 have been linked to abnormal early eye development and reduced bone mineral density. In this review, we briefly summarize the structural organization and the expression of ADAMTS-18. We will also focus on the emerging role of ADAMTS-18 in several pathophysiological conditions which include: hematological diseases, tumorgenesis, osteogenesis, eye-related diseases, central nervous system disorders, and last but not least a research perspective of ADAMTS-18 and its potential as a promising diagnostic and therapeutic target.

An ocular form of myasthenia gravis with a high titer of anti-MuSK antibodies during a long-term follow-up.

We herein report a case of ocular myasthenia gravis (MG) that was highly positive for anti-muscle-specific tyrosine kinase (MuSK) antibodies. The examined patient exhibited bilateral ptosis and lateral gaze palsy without any generalized symptoms and was diagnosed with ocular MG with anti-MuSK antibodies. She responded to treatment with prednisolone and immunosuppressants and experienced only ocular symptoms for four years and eight months after onset. Ocular MG with anti-MuSK antibodies lasting for a long term has rarely been described. Our findings suggest that it may be reasonable to test for the presence of anti-MuSK antibodies in patients who present with external ophthalmoplegia.

Pediatric uveitis secondary to probable, presumed, and biopsy-proven sarcoidosis.

PURPOSE: To describe pediatric patients with uveitis diagnosed as having sarcoidosis. METHODS: Medical records of pediatric patients evaluated between 1987 and 2008 were reviewed to identify those with ocular inflammation in whom a diagnosis of sarcoidosis was considered. A classification system including ocular findings and results of laboratory testing was devised and used to classify likelihood of sarcoidosis. RESULTS: Four hundred sixty children younger than 17 years were evaluated. Based on the classification system designed, 13 patients (2.8%) had probable, presumed, or definite sarcoidosis. The mean age was 11.6 years (range: 5 to 16 years). Elevated angiotensin-converting enzyme was measured in 6 patients and lysozyme in 5 patients. Five of 12 patients in whom chest imaging was performed had signs of sarcoidosis. Anterior segment involvement was non-granulomatous more often than granulomatous. Seven patients had multifocal choroiditis and 4 patients had retinal periphlebitis. CONCLUSION: Ocular sarcoidosis is uncommon in children, even at a tertiary referral center. Pulmonary involvement was detected in slightly less than half of the patients who had imaging, in contrast to previous reports of almost universal lung involvement in children 8 to 15 years old. The classification system of presumed, probable, and definite sarcoidosis presented may be useful in clinical practice.

Enzyme assay and clinical assessment in subjects with a Chinese hotspot late-onset Fabry mutation (IVS4 + 919G→A).

Newborn screening for Fabry disease in Taiwan Chinese has revealed a high incidence of the late-onset GLA mutation IVS4 + 919G→A (∼1 in 1,500-1,600 males). We studied 94 adults with this mutation [22 men, 72 women; mean age: men 57.8 ± 6.0 (range 42-68), women 39.1 ± 14.1 years (range 19-82)]. Plasma α-galactosidase A activity assay was 10.4 ± 11.2% of normal in the men and 48.6 ± 19.5% of normal in the women. Echocardiography in 90 of the adults revealed left ventricular hypertrophy (LVH) in 19 (21%), including 14 of 21 men (67%) and 5 of 69 women (7%). Microalbuminuria, based on the urine albumin-to-creatinine ratio measured on at least two occasions, was present in 17 of 86 subjects (20%) (men: 5/20, 25%; women 12/66, 18%). At least one ocular manifestation consistent with Fabry disease was present in 41 of 52 subjects (79%) who underwent ophthalmologic examination, including 8 (15%) with conjunctival vessel tortuosity, 15 (29%) with cornea verticillata, 10 (19%) with Fabry cataract, and 34 (65%) with retinal vessel tortuosity. Among subjects over 40 years of age, men were more likely than women to have LVH [14/21 (67%) vs 5/25 (20%), p < 0.001]. Cardiovascular, renal and ocular abnormalities are highly prevalent in adult Taiwan Chinese subjects with the Fabry mutation IVS4 + 919G→A. Our findings contribute to the limited understanding of the course of this late-onset disease variant and underscore the need for close follow up in such patients.

Potential role of calcineurin in pathogenic conditions.

Since its initial discovery as Ca(2+)/calmodulin (CaM)-dependent serine/threonine protein phosphatase, calcineurin (CaN) has been extensively studied in many mammalian tissues. CaN has been shown to be involved in various biological and Ca(2+)-dependent signal transduction pathways. Over the last decade, our laboratory has been interested and has carried out numerous experiments on this specific protein phosphatase. While, a lot of research has been performed studying CaN's involvement in ischemia, the immune system, and various mammalian tissues, not much is known about the potential role of CaN in various eye diseases. This review focuses on the studies that have been carried out in our laboratory on CaN, and specifically CaN's involvement in the eye. We demonstrated that CaN is localized in various eye tissues (cornea, iris, ciliary body, vitreous body, retina, choroid, sclera, and optic nerve) and that both its protein expression and activity were observed in high amounts in the retina, optic nerve and cornea. Recently, we have cloned and characterized the CaN A and B subunits in the bovine retina. These initial findings suggest that CaN may play a potential role in visual transduction and various ocular diseases, including cancer.

Autoimmunity against carbonic anhydrase II affects retinal cell functions in autoimmune retinopathy.

Autoantibodies against various retinal proteins, including anti-carbonic anhydrase II (CAII) autoantibodies, have been found in patients with cancer-associated retinopathy and autoimmune retinopathy without diagnosed cancer. We studied sera from retinopathy patients that showed reactivity with a 30-kDa retinal protein, which was identified as carbonic anhydrase II (CAII), and immunolabeled cells in human retina. The goal of the study was to examine whether patients' autoantibodies induce pathogenic effects on the catalytic function of CAII, which may have metabolic consequences on cell survival. Our findings revealed that anti-CAII autoantibodies have the capacity to induce cellular damage by impairing CAII cellular function through inhibiting the catalytic activity of CAII in a dose dependent manner, decreasing intracellular pH, increasing intracellular calcium, which in effect decreases retinal cell viability. The destabilized catalytic function of CAII and alterations in cytosolic pH were found very early, suggesting that autoantibodies are the inducers of apoptosis. In summary, our study showed that anti-CAII autoantibodies provoke pathogenic effects on retinal cells by decreasing cell survival by blocking the CAII cellular functions. The current experiments may facilitate better understanding the role of the immune system in retinal degeneration and help to develop better strategies for therapy of autoimmune retinopathy.

Tear proteins in health, disease, and contact lens wear.

Although well known as manifestations of sorrow, emotions, frustration, and blackmail, tears have a more prosaic and important function as a lubricant and as a blood substitute for the cornea. Tears transport oxygen and carbon dioxide and play a central role in the cellular economy of the ocular surface and conjunctiva. In addition to proteins, tears contain lipids and glycoproteins, which increase the wetting effect of the aqueous component and delay evaporation. The total protein concentration of tears is about 10% of that of the plasma. About 80 proteins and polypeptide components have been detected by electrophoresis. Among 30 proteins identified in tears, about 50% are enzymes. Some of the tear enzymes are secreted by the lacrimal glands; others are produced by or released from epithelial cells of the cornea and the conjunctiva. Finally, a few enzymes originate from plasma and appear in tears only in cases with increased permeability of the conjunctival vessels. The aim of this review is to provide clinical and biochemical information about tear enzymes both for ophthalmologists and for biochemists interested in clinical and experimental tear enzymology.

Human secretory phospholipase A(2), group IB in normal eyes and in eye diseases.

PURPOSE: Secretory phospholipases A(2) (sPLA(2)) are enzymes involved in lipid turnover. We recently identified sPLA(2) group IB (GIB) in the rat retina as well as in cerebral neurons and found upregulation to occur in response to light damage and seizures, respectively. The purpose of the present study was to identify human GIB (hGIB) in the normal human eye and investigate the pattern of expression in patients with eye diseases involving hGIB-rich cells. METHODS: Human GIB mRNA was identified in the human retina by means of in situ hybridization and polymerase chain reaction. Antibodies against hGIB were obtained and immunohistochemical staining was performed on paraffin-embedded sections of normal and pathological eyes. Donor eyes from patients with descemetization of the cornea, Fuchs' corneal endothelial dystrophy, age-related macular degeneration, malignant choroidal melanoma, retinitis pigmentosa and glaucoma were evaluated. RESULTS: Expression of hGIB was found in various cells of the eye. The most abundant expression was found in retinal pigment epithelium (RPE) cells, the inner photoreceptor segments, ganglion cells and the corneal endothelium. We explored diseases involving hGIB-rich cells and found downregulation of hGIB in proliferating RPE cells as well as in diseased corneal endothelial cells. CONCLUSIONS: Human GIB is highly expressed in cells with neurodermal origin. The pattern of expression of hGIB in diseases involving hGIB-rich cells demonstrated a downregulation of hGIB in migrating RPE cells and in diseased corneal endothelium.

Matrix metalloproteinases as valid clinical targets.

The matrix metalloproteinase family of enzymes has been a pharmaceutical target for over 20 years. In that time, many drugs have been developed but none have successfully passed clinical trials. A significant problem has been development of dose-limiting side-effects that were revealed during long-term clinical trials in diseases such as arthritis and various cancers. There are, however, other clinical settings where evidence for MMP function contributing to the pathophysiology of disease is strong. A number of these settings will be discussed here together with evidence from animal models that MMP inhibition is a valid strategy to be considered. A major advantage with many of these settings is that drug exposure may not have to be long-term and/or systemic thus reducing the possibility that side-effects will stymie MMPI-based therapy.

Vascular endothelial growth factor receptors: molecular mechanisms of activation and therapeutic potentials.

Angiogenesis-associated eye diseases are among the most common cause of blindness in the United States and worldwide. Recent advances in the development of angiogenesis-based therapies for treatment of angiogenesis-associated diseases have provided new hope in a wide variety of human diseases ranging from eye diseases to cancer. One group of growth factor receptors critically implicated in angiogenesis is vascular endothelial growth factor receptors (VEGFR), a subfamily of receptor tyrosine kinases (RTKs). VEGFR-1 and VEGFR-2 are closely related receptor tyrosine kinases and have both common and specific ligands. VEGFR-1 is a kinase-impaired RTK and its kinase activity is suppressed by a single amino acid substitution in its kinase domain and by its carboxyl terminus. VEGFR-2 is highly active kinase, stimulates a variety of signaling pathways and broad biological responses in endothelial cells. The mechanisms that govern VEGFR-2 activation, its ability to recruit signaling proteins and to undergo downregulation are highly regulated by phosphorylation activation loop tyrosines and its carboxyl terminus. Despite their differential potentials to undergo tyrosine phosphorylation and kinase activation, both VEGFR-1 and VEGFR-2 are required for normal embryonic development and pathological angiogenesis. VEGFR-1 regulates angiogenesis by mechanisms that involve ligand trapping, receptor homodimerization and heterodimerization. This review highlights recent insights into the mechanism of activation of VEGFR-1 and VEGFR-2, and focuses on the signaling pathways employed by VEGFR-1 and VEGFR-2 that regulate angiogenesis and their therapeutic potentials in angiogenesis-associated diseases.

Expression of hyaluronan synthase in intraocular proliferative diseases: regulation of expression in human vascular endothelial cells by transforming growth factor-beta.

PURPOSE: To investigate the role of hyaluronan (HA) and elucidate the mechanisms that regulate the expression of hyaluronan-synthesizing enzymes in vascular endothelial cells (VECs) in intraocular proliferative diseases. METHODS: Cultured VECs were used. Hyaluronan synthase (HAS) expression was determined on the mRNA products obtained by reverse transcription polymerase chain reaction (RT-PCR). The effect of transforming growth factor-beta(1)(TGF-beta(1)) and/or platelet-derived growth factor-BB (PDGF-BB) on HAS expression was examined by quantitative RT-PCR and Western blot analysis. HAS expression in intraocular proliferative membranes was observed by immunohistochemistry. RESULTS: Cultured VECs expressed the three HAS isoforms. Stimulation of VECs with TGF-beta(1) induced a marked increase in the expression level of HAS2 mRNA and protein. The stimulatory effect of PDGF-BB was less potent. A synergistic or additive effect between TGF-beta(1) and PDGF-BB-induced HA synthesis was not observed. Furthermore, HAS1 and HAS2 exhibited differential expression in VECs and non-VECs populating intraocular proliferative membranes. CONCLUSIONS: The expression of each HAS isoform is regulated differently by growth factors and cytokines in VECs. Importantly, HA-synthesizing enzymes were expressed in cells populating proliferative membranes obtained from eyes of patients with proliferative vitreoretinal diseases, and thus may be key molecules in the events that control progression of the proliferative diseases.

Matrix metalloproteinases in disease and repair processes in the anterior segment.

The pathogenesis of many anterior segment disorders and ocular complications following surgery are secondary to the wound healing response. The extent of clinical damage observed is closely related to the amount of scarring and tissue contraction. Matrix metalloproteinases (MMPs) are a family of enzymes that play a vital role in all stages of the wound healing process. They degrade all extracellular matrix components and also have the ability to synthesize collagen and extracellular matrix members, and are therefore important in the remodeling of a wound. Overexpression of MMPs results in excessive extracellular matrix degradation, leading to tissue destruction and loss of organ function. In the case of the anterior segment, this may mean the loss of visual function. This review focuses on the role MMPs have in the development of various anterior segment disorders. The importance of MMPs in the wound healing response and its potential modulation to manipulate the scarring response is being recognized, and current developments will be described.

Ocular manifestations of sarcoidosis.

Sarcoidosis remains an enigmatic disease with serious ocular morbidity. Recent literature continues to expand our knowledge of the ocular manifestations and their sequelae. Advances in diagnostic clinical testing are reviewed, including updates on angiotensin-converting enzyme levels, gallium scanning, bronchoalveolar lavage, and transbronchial lung biopsy.