Role of Metallothioneins 1 and 2 in Ocular Neovascularization

Methazolamide Can Treat Atherosclerosis by Increasing Immunosuppressive Cells and Decreasing Expressions of Genes Related to Proinflammation, Calcification, and Tissue Remodeling

It has been reported that carbonic anhydrase I (CA1) is a target for the diagnosis and therapy of atherosclerosis (AS) since CA1 can promote AS aortic calcification. We also found that methazolamide (MTZ), a drug for glaucoma treatment and an inhibitor of carbonic anhydrases, can treat AS by inhibiting calcification in aortic tissues. This study focused on the therapeutic mechanism of MTZ and the pathogenic mechanism of AS. In this study, a routine AS animal model was established in ApoE-/- mice, which were treated with MTZ. The aortic tissues were analyzed using single-cell sequencing. MTZ significantly increased the proportions of B-1/MZB B cells with high expressions of Nr4A1 and Ccr7, CD8+CD122+ Treg-like cells with high Nr4A1 expression, and smooth muscle cells with high Tpm2 expression. These cells or their marker genes were reported to exert immunosuppressive, anti-proinflammatory, and atheroprotective effects. MTZ also decreased the proportions of endothelial cells with high expressions of Retn, Apoc1, Lcn2, Mt1, Serpina3, Lpl, and Lgals3; nonclassical CD14+CD16++ monocytes with high expressions of Mt1, Tyrobp, Lgals3, and Cxcl2; and Spp1+ macrophages with high expressions of Mmp-12, Trem2, Mt1, Lgals3, Cxcl2, and Lpl. These cells or their marker genes have been reported to promote inflammation, calcification, tissue remodeling, and atherogenesis. A significant decrease in the proportion of CD8+CD183 (CXCR3)+ T cells, the counterpart of murine CD8+CD122+ T cells, was detected in the peripheral blood of newly diagnosed AS patients rather than in that of patients receiving anti-AS treatments. These results suggest that MTZ can treat AS by increasing immunosuppressive cells and decreasing expressions of genes related to inflammation, calcification, and tissue remodeling.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Metallothioneins, a Part of the Retinal Endogenous Protective System in Various Ocular Diseases

Metallothioneins are the metal-rich proteins that play important roles in metal homeostasis and detoxification. Moreover, these proteins protect cells against oxidative stress, inhibit proapoptotic mechanisms and enhance cell differentiation and survival. Furthermore, MTs, mainly MT-1/2 and MT-3, play a vital role in protecting the neuronal retinal cells in the eye. Expression disorders of these proteins may be responsible for the development of various age-related eye diseases, including glaucoma, age-related macular degeneration, diabetic retinopathy and retinitis pigmentosa. In this review, we focused on the literature reports suggesting that these proteins may be a key component of the endogenous protection system of the retinal neurons, and, when the expression of MTs is disrupted, this system becomes inefficient. Moreover, we described the location of different MT isoforms in ocular tissues. Then we discussed the changes in MT subtypes' expression in the context of the common eye diseases. Finally, we highlighted the possibility of the use of MTs as biomarkers for cancer diagnosis.

Changes in aqueous and vitreous inflammatory cytokine levels in proliferative diabetic retinopathy: a systematic review and meta-analysis

BACKGROUND

Diabetic retinopathy is a major complication of diabetes mellitus, where in its most advanced form ischemic changes lead to the development of retinal neovascularization, termed proliferative diabetic retinopathy (PDR). While the development of PDR is often associated with angiogenic and inflammatory cytokines, studies differ on which cytokines are implicated in disease pathogenesis and on the strength of these associations. We therefore conducted a systematic review and meta-analysis to quantitatively assess the existing body of data on intraocular cytokines as biomarkers in PDR.

METHODS

A comprehensive search of the literature without year limitation was conducted to January 18, 2021, which identified 341 studies assessing vitreous or aqueous cytokine levels in PDR, accounting for 10379 eyes with PDR and 6269 eyes from healthy controls. Effect sizes were calculated as standardized mean differences (SMD) of cytokine concentrations between PDR and control patients.

RESULTS

Concentrations (SMD, 95% confidence interval, and p-value) of aqueous IL-1β, IL-6, IL-8, MCP-1, TNF-α, and VEGF, and vitreous IL-2, IL-4, IL-6, IL-8, angiopoietin-2, eotaxin, erythropoietin, GM-CSF, GRO, HMGB-1, IFN-γ, IGF, IP-10, MCP-1, MIP-1, MMP-9, PDGF-AA, PlGF, sCD40L, SDF-1, sICAM-1, sVEGFR, TIMP, TNF-α, and VEGF were significantly higher in patients with PDR when compared to healthy nondiabetic controls. For all other cytokines no differences, failed sensitivity analyses or insufficient data were found.

CONCLUSIONS

This extensive list of cytokines speaks to the complexity of PDR pathogenesis, and informs future investigations into disease pathogenesis, prognosis, and management.

Single cell RNA sequencing (scRNA-Seq) deciphering pathological alterations in streptozotocin-induced diabetic retinas

Diabetic retinopathy (DR) is an irreversible and progressive diabetic complication leading to visual impairment, even blindness. Due to the delicate and complicated structure of the retina, the pathology of DR has not been completely elucidated yet. We constructed a transcriptome atlas of >14,000 single cells from healthy and streptozotocin (STZ)-induced diabetic murine retinas to decipher pathological alterations of DR. We found four stress-inducible genes Cirbp, Rmb3, Mt1 and Mt2 commonly induced in most types of retinal cells. Bipolar cells were little affected on both number and gene expression. Diabetes increased expression of inflammatory factor genes in retinal microglia, and stimulated expression of immediate early genes (IEGs) in retinal astrocytes. A large number of genes were deregulated in diabetic vascular endothelial cells (ECs), and the differentially expressed genes were paired to the pathways functioning in metabolism, shear stress and vascular permeability. These pathways were mapped by more deregulated genes in a subpopulation of ECs specifically presented in diabetic retinas (diabetic retinal ECs, DRECs). Moreover, several inflammation pathways were activated in DRECs, and the most significant one is the IL-17 signaling pathway. According to the EC markers, DRECs were mainly capillary ECs, confirmed by immunofluorescent staining of S100a9, a target gene of the IL-17 signaling pathway. This study deciphered pathological alterations of DR, and provided clues for potential targets for DR therapy.

Transcriptomic analysis of the mouse retina after acute and chronic normobaric and hypobaric hypoxia

Oxygen delivery to the retinal pigment epithelium and the outer retina is essential for metabolism, function, and survival of photoreceptors. Chronically reduced oxygen supply leads to retinal pathologies in patients and causes age-dependent retinal degeneration in mice. Hypoxia can result from decreased levels of inspired oxygen (normobaric hypoxia) or reduced barometric pressure (hypobaric hypoxia). Since the response of retinal cells to chronic normobaric or hypobaric hypoxia is mostly unknown, we examined the effect of six hypoxic conditions on the retinal transcriptome and photoreceptor morphology. Mice were exposed to short- and long-term normobaric hypoxia at 400 m or hypobaric hypoxia at 3450 m above sea level. Longitudinal studies over 11 weeks in normobaric hypoxia revealed four classes of genes that adapted differentially to the hypoxic condition. Seventeen genes were specifically regulated in hypobaric hypoxia and may affect the structural integrity of the retina, resulting in the shortening of photoreceptor segment length detected in various hypoxic groups. This study shows that retinal cells have the capacity to adapt to long-term hypoxia and that consequences of hypobaric hypoxia differ from those of normobaric hypoxia. Our datasets can be used as references to validate and compare retinal disease models associated with hypoxia.

Both Autocrine Signaling and Paracrine Signaling of HB-EGF Enhance Ocular Neovascularization

OBJECTIVE

The incidence of blindness is increasing because of the increase in abnormal ocular neovascularization. Anti-VEGF (vascular endothelial growth factor) therapies have led to good results, although they are not a cure for the blindness. The purpose of this study was to determine what role HB-EGF (heparin-binding epidermal growth factor-like growth factor) plays in ocular angiogenesis.

APPROACH AND RESULTS

We examined the role played by HB-EGF in ocular neovascularization in 2 animal models of neovascularization: laser-induced choroidal neovascularization (CNV) and oxygen-induced retinopathy. We also studied human retinal microvascular endothelial cells in culture. Our results showed that the neovascularization was decreased in both the CNV and oxygen-induced retinopathy models in HB-EGF conditional knockout mice compared with that in wild-type mice. Moreover, the expressions of HB-EGF and VEGF were increased after laser-induced CNV and oxygen-induced retinopathy, and their expression sites were located around the neovascular areas. Exposure of human retinal microvascular endothelial cells to HB-EGF and VEGF increased their proliferation and migration, and CRM-197 (cross-reactive material-197), an HB-EGF inhibitor, decreased the HB-EGF-induced and VEGF-induced cell proliferation and migration. VEGF increased the expression of HB-EGF mRNA. VEGF-dependent activation of EGFR (epidermal growth factor receptor)/ERK1/2 (extracellular signal-regulated kinase 1/2) signaling and cell proliferation of endothelial cells required stimulation of the ADAM17 (a disintegrin and metalloprotease) and ADAM12. CRM-197 decreased the grades of the fluorescein angiograms and size of the CNV areas in marmoset monkeys.

CONCLUSIONS

These findings suggest that HB-EGF plays an important role in the development of CNV. Therefore, further investigations of HB-EGF are needed as a potential therapeutic target in the treatment of exudative age-related macular degeneration.

Does the Microbiome Cause B27-related Acute Anterior Uveitis?

The microbiome is strongly implicated in a broad spectrum of immune-mediated diseases. Data support the concept that HLA molecules shape the microbiome. We provide hypotheses to reconcile how HLA-B27 might affect the microbiome and in turn predispose to acute anterior uveitis. These theories include bacterial translocation, antigenic mimicry, and dysbiosis leading to alterations in regulatory and effector T-cell subsets. Received 31 October 2015; revised 7 January 2016; accepted 8 January 2016; published online 22 March 2016.