Chi-Ju-Di-Huang-Wan protects rats against retinal ischemia by downregulating matrix metalloproteinase-9 and inhibiting p38 mitogen-activated protein kinase

Intracellular Zn2+ promotes extracellular matrix remodeling in dexamethasone-treated trabecular meshwork

Given the widespread application of glucocorticoids in ophthalmology, the associated elevation of intraocular pressure (IOP) has long been a vexing concern for clinicians, yet the underlying mechanisms remain inconclusive. Much of the discussion focuses on the extracellular matrix (ECM) of trabecular meshwork (TM). It is widely agreed that glucocorticoids impact the expression of matrix metalloproteinases (MMPs), leading to ECM deposition. Since Zn2+ is vital for MMPs, we explored its role in ECM alterations induced by dexamethasone (DEX). Our study revealed that in human TM cells treated with DEX, the level of intracellular Zn2+ significantly decreased, accompanied by impaired extracellular Zn2+ uptake. This correlated with changes in several Zrt-, Irt-related proteins (ZIPs) and metallothionein. ZIP8 knockdown impaired extracellular Zn2+ uptake, but Zn2+ chelation did not affect ZIP8 expression. Resembling DEX's effects, chelation of Zn2+ decreased MMP2 expression, increased the deposition of ECM proteins, and induced structural disarray of ECM. Conversely, supplementation of exogenous Zn2+ in DEX-treated cells ameliorated these outcomes. Notably, dietary zinc supplementation in mice significantly reduced DEX-induced IOP elevation and collagen content in TM, thereby rescuing the visual function of the mice. These findings underscore zinc's pivotal role in ECM regulation, providing a novel perspective on the pathogenesis of glaucoma.NEW & NOTEWORTHY Our study explores zinc's pivotal role in mitigating extracellular matrix dysregulation in the trabecular meshwork and glucocorticoid-induced ocular hypertension. We found that in human trabecular meshwork cells treated with dexamethasone, intracellular Zn2+ significantly decreased, accompanied by impaired extracellular Zn2+ uptake. Zinc supplementation rescues visual function by modulating extracellular matrix proteins and lowering intraocular pressure, offering a direction for further exploration in glaucoma management.

The Effect of S-Allyl L-Cysteine on Retinal Ischemia: The Contributions of MCP-1 and PKM2 in the Underlying Medicinal Properties

Retinal ischemia plays a vital role in vision-threatening retinal ischemic disorders, such as diabetic retinopathy, age-related macular degeneration, glaucoma, etc. The aim of this study was to investigate the effects of S-allyl L-cysteine (SAC) and its associated therapeutic mechanism. Oxidative stress was induced by administration of 500 μM H2O2 for 24 h; SAC demonstrated a dose-dependent neuroprotective effect with significant cell viability effects at 100 μM, and it concurrently downregulated angiogenesis factor PKM2 and inflammatory biomarker MCP-1. In a Wistar rat model of high intraocular pressure (HIOP)-induced retinal ischemia and reperfusion (I/R), post-administration of 100 μM SAC counteracted the ischemic-associated reduction of ERG b-wave amplitude and fluorogold-labeled RGC reduction. This study supports that SAC could protect against retinal ischemia through its anti-oxidative, anti-angiogenic, anti-inflammatory, and neuroprotective properties.

Matrix Metalloproteinases in Glaucoma: An Updated Overview

Matrix metalloproteinases (MMPs) are important regulators of the extracellular matrix (ECM) and are involved in many stages of cellular growth and development. An imbalance of MMP expression is also the basis of many diseases, including eye diseases, such as diabetic retinopathy (DR), glaucoma, dry eye, corneal ulcer, keratoconus. This paper describes the role of MMPs in the glaucoma and their role in the glaucomatous trabecular meshwork (TM), aqueous outflow channel, retina, and optic nerve (ON). This review also summarizes several treatments for glaucoma that target MMPs imbalance and suggests that MMPs may represent a viable therapeutic target for glaucoma.

Complementary Chinese Herbal Medicine Therapy Improves Survival in Patients With Pemphigus: A Retrospective Study From a Taiwan-Based Registry

Pemphigus is a life-threatening and skin-specific inflammatory autoimmune disease, characterized by intraepidermal blistering between the mucous membranes and skin. Chinese herbal medicine (CHM) has been used as an adjunct therapy for treating many diseases, including pemphigus. However, there are still limited studies in effects of CHM treatment in pemphigus, especially in Taiwan. To more comprehensively explore the effect of long-term CHM treatment on the overall mortality of pemphigus patients, we performed a retrospective analysis of 1,037 pemphigus patients identified from the Registry for Catastrophic Illness Patients database in Taiwan. Among them, 229 and 177 patients were defined as CHM users and non-users, respectively. CHM users were young, predominantly female, and had a lesser Charlson comorbidity index (CCI) than non-CHM users. After adjusting for age, sex, prednisolone use, and CCI, CHM users had a lower overall mortality risk than non-CHM users (multivariate model: hazard ratio (HR): 0.422, 95% confidence interval (CI): 0.242–0.735, p = 0.0023). The cumulative incidence of overall survival was significantly higher in CHM users than in non-users (p = 0.0025, log rank test). Association rule mining and network analysis showed that there was one main CHM cluster with Qi–Ju–Di–Huang–Wan (QJDHW), Dan–Shen (DanS; Radix Salviae miltiorrhizae; Salvia miltiorrhiza Bunge), Jia–Wei–Xiao–Yao-–San (JWXYS), Huang–Lian (HL; Rhizoma coptidis; Coptis chinensis Franch.), and Di–Gu–Pi (DGP; Cortex lycii; Lycium barbarum L.), while the second CHM cluster included Jin–Yin–Hua (JYH; Flos lonicerae; Lonicera hypoglauca Miq.) and Lian–Qiao (LQ; Fructus forsythiae; Forsythia suspensa (Thunb.) Vahl). In Taiwan, CHMs used as an adjunctive therapy reduced the overall mortality to approximately 20% among pemphigus patients after a follow-up of more than 6 years. A comprehensive CHM list may be useful in future clinical trials and further scientific investigations to improve the overall survival in these patients.

Emodin protected against retinal ischemia insulted neurons through the downregulation of protein overexpression of β-catenin and vascular endothelium factor

Background

Emodin has been proved to have an anti-ischemic effect on the brain, however little research has been done on its effect on vision-threatening retinal ischemia. Thus, an investigation was carried out into the hypothetical efficacy of emodin against retinal ischemia and the role of β-catenin/VEGF in its therapeutic mechanism.

Methods

Retinal ischemia, followed by reperfusion (IR), was inducted by raising the intraocular pressure of a Wistar rat’s eye to 120 mmHg for 60 min. Additionally, pre-ischemic/post-ischemic intravitreous injections of emodin (4, 10 and 20 μM) or vehicle were carried out on the eye with retinal ischemia. MTT assay, electroretinograms, cresyl violet staining retinal thickness measurements, and fluorogold retrograde labelling of retinal ganglion cells (RGCs) as well as Western blotting were carried out.

Results

Cultured RGC-5 cells subjected to oxygen glucose deprivation (OGD) were used to confirm the effective concentrations of emodin (administered 1 h pre-OGD, pre-OGD emodin). The most effective and significant (P = 0.04) dose of pre-OGD emodin was observed at 0.5 μM (cell viability: 47.52 ± 3.99%) as compared to pre-OGD vehicle treatment group (38.30 ± 2.51%). Furthermore, pre-ischemic intravitreous injection of 20 μM emodin (Emo20 + IR = 0.99 ± 0.18, P < 0.001) significantly attenuated the ischemia induced reduction in ERG b-wave amplitude, as compared to pre-ischemic intravitreous vehicle (Vehicle+IR = 0.04 ± 0.02). Post-ischemic intravitreous 20 μM emodin also significantly (P < 0.001) attenuated the ischemia associated b-wave reduction (IR + Em20 = 0.24 ± 0.09). Compared with pre-ischemic intravitreous vehicle (Vehicle+IR; whole retina thickness = 71.80 ± 1.08 μm; inner retina thickness = 20.97 ± 0.85 μm; RGC =2069.12 ± 212.82/0.17mm²), the significant (P < 0.001) protective effect was also present with pre-ischemic administration of emodin. This was shown by observing cresyl violet stained retinal thickness (Emo20 + IR: whole retina = 170.10 ± 0.10 μm; inner retina = 70.65 ± 2.06 μm) and retrograde fluorogold immunolabeled RGC density (4623.53 ± 179.48/0.17mm²). As compared to the normal control (the ratio of β-catenin/VEGF to β-actin was set as 1 in the Sham group), the β-catenin/VEGF protein level significantly (P < 0.001) increased after retinal ischemia and when pre-ischemic intravitreous vehicle (Vehicle+IR = 1.64 ± 0.14/7.67 ± 2.57) was carried out. However, these elevations were significantly (P = 0.02) attenuated by treatment with emodin 20 μM (Emo20 + IR = 1.00 ± 0.19/1.23 ± 0.44).

Conclusions

The present results suggest that emodin might protect against retinal ischemia insulted neurons such as RGCs by significantly downregulating the upregulation of β-catenin/VEGF protein that occurs during ischemia.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12906-020-03136-7.

Fortified S-Allyl L-Cysteine: Animal Safety, Effect on Retinal Ischemia, and Role of Wnt in the Underlying Therapeutic Mechanism

Purpose

Retinal ischemia is a medical condition associated with numerous retinal vascular disorders, such as age-related macular degeneration, glaucoma, and diabetic retinopathy. This in vitro cell and in vivo animal study investigated not only the protective effect of S-allyl L-cysteine (SAC, an active component of garlic) against retinal ischemia but also its associated protective mechanisms.

Methods

Retinal ischemia was mimicked by raising the intraocular pressure to 120 mmHg for 1 hour in one eye. The effects of pre-/postischemic administration of vehicle vs. SAC 0.18 mg vs. SAC 0.018 mg vs. SAC 0.0018 mg treatments on retina cells were evaluated through cellular viability (MTT assay), flash electroretinograms (ERGs), and fluorogold retrograde labelling (retinal ganglion cell (RGC) counting). Also, protein immunoblot was utilized to assess the role of Wnt, hypoxia inducible factor (HIF)-1α, and vascular endothelium factor (VEGF) in the proposed anti-ischemic mechanism. Lastly, the safety of drug consumption was investigated for changes in the animal's body weight, ERG waves, and blood biochemical parameters (e.g., glucose levels).

Results

The characteristic ischemic changes including significant reduction in ERG b-wave ratio and RGC number were significantly counteracted by pre- and postischemic low dose of SAC. Additionally, ischemia-induced overexpression of Wnt/HIF-1α/VEGF protein was ameliorated significantly by preischemic low dose of SAC. In terms of the animal safety, no significant body weight and electrophysiological differences were observed among defined different concentrations of SAC without following ischemia. In low SAC dosage and vehicle groups, various blood biochemical parameters were normal; however, high and medium concentrations of SAC significantly lowered the levels of uric acid, Hb, and MCHC.

Conclusion

This study shows that preischemic administration of low SAC dosage has been proved to be safe and most effective against rat retinal ischemia electrophysiologically and/or histopathologically. Moreover, counteracting the ischemia-induced overexpression of Wnt/HIF-1α/VEGF might presently explain SAC's anti-ischemic mechanism.

The protective effects of lycopus lucidus turcz in diabetic retinopathy and its possible mechanisms

The aim of the present study was to investigate the effect of Lycopus lucidus Turcz (LT) on diabetic retinopathy (DR) and its underlying mechanisms. SD rats and human retinal microvascular endothelial cells (HRECs) were applied for establishment DR model. HE and TUNEL staining were used to evaluate the pathological changes and apoptosis of retinal ganglion cells. Additionally, retinal vessels were detected by immunofluorescence staining with CD31 and VEGF. The function of BRB was observed using Evans blue. Moreover, the oxidative stress, inflammation and angiogenesis associated factors were measured respectively. The expression of p38-MAPK/NF-κB signalling proteins were detected by Western blot. The results demonstrated that pathological changes and retinal optic disc cells apoptosis in retinas of diabetic rats, both of which were reduced in the LT-treated group. And LT treatment attenuated the levels of oxidative stress, inflammation and angiogenesis factors. Importantly, the expression levels of p-p38, p-ERK, p-JNK and NF-κB were decreased. After treatment with TNF-α combined with LT, the levels of inflammatory factors were decreased but higher than the negative control. Taken together, the results suggested that LT treatment is of therapeutic benefit by ameliorating oxidative stress, inflammation and angiogenesis of DR via p38-MAPK/NF-κB signaling pathway.

Dry Eye: The Effect of Chi-Ju-Di-Huang-Wan Plus Si Wu Tang and the Underlying Mechanism

Objectives: In this pilot study, the effect of 970 mg Chi-Ju-Di-Huang-Wan (CJDHW) plus 30 mg four-substance decoction (Si Wu Tang; CJDHWSWT) was evaluated, in terms of its ability to alleviate dry eye symptoms and its therapeutic mechanism. Methods: This double-masked prospective investigation has recruited dry eye patients who have been randomly selected into two groups, namely treatment (n = 15) versus nontreatment (n = 15). In the treatment group, a daily oral intake of CJDHWSWT plus eye drops systane ultra was given for 90 consecutive days. In the nontreatment group, only defined eye drops were prescribed. The examinations included Schirmer's test, fluorescein-stained superficial punctate keratitis (SPK), artificial tear consumption, tear vascular endothelium growth factor (VEGF) level, and ocular surface disease index. The drug safety tests included liver and kidney functions, and complete blood counts. The candidates were observed during the screening visit and the following three monthly follow-ups. The data were analyzed by unpaired Student's t-test. Results: Compared to no significance in the nontreatment group, CJDHWSWT significantly (p = 0.03) increased the tear secretion after 3 months of intake. Furthermore, in contrast to no significance in the treatment group, there were significant alterations, including (i) increased fluorescein-stained SPK areas (p = 0.03); (ii) increased artificial tear instillation amount (p = 0.03); (iii) elevated tear VEGF protein levels (p = 0.03) in the nontreatment group; and (iv) significant improvement in clinically relevant phenomenon (e.g., reading limit and uncomfortable feeling in windy conditions), after treatment of artificial tear plus oral intake of CJDHWSWT. As shown by the post-treatment normal defined laboratory data, there were no adverse drug effects. Conclusions: This study has supported that CJDHWSWT is safe and effective in relieving dry eye's clinically relevant symptoms/phenomena. CJDHWSWT avoided the tear VEGF upregulation probably induced by dry eye-associated hypoxia/ischemia.

Protective effects of taurine against renal ischemia/reperfusion injury in rats by inhibition of gelatinases, MMP-2 and MMP-9, and p38 mitogen-activated protein kinase signaling

Dysregulated expression of matrix metalloproteinases (MMPs) is closely associated with the pathogenesis of renal ischemia/reperfusion injury (I/R). The production of excessive reactive oxygen species (ROS) causes tissue damage. Increased ROS production causes activation of p38 mitogen-activated protein kinase (MAPK) signaling, which participates in gene regulation of MMPs, especially MMP-2 and MMP-9 (gelatinases). Taurine (2-aminoethanesulfonic acid) in mammalian cells functions in bile acid conjugation, maintenance of calcium homeostasis, osmoregulation, membrane stabilization, and antioxidation, antiinflammatory, and antiapoptotic action. We investigated the effects of taurine and the possible role of p38 MAPK signaling on regulation of MMP-2 and MMP-9 in a renal I/R injury model in rats. Rats were divided into three groups: sham, I/R, and I/R + taurine treated. After a right nephrectomy, I/R was induced by clamping the left renal pedicle for 1 h followed by 6 h reperfusion. Taurine was administered 45 min prior to induction of ischemia. Renal function was assessed by serum creatinine and blood urea nitrogen (BUN) levels. Tubule injury and structural changes were evaluated by light microscopy. Malondialdehyde (MDA) levels were analyzed by high performance liquid chromatography (HPLC). Superoxide dismutase (SOD) activity levels were measured using a colorimetric kit. mRNA expression of MMP-2 and MMP-9 was determined by real-time polymerase chain reaction. MMP-2 and MMP-9 activities were measured using a fluorimetric kit. Phosphorylated p38 (p-p38) and total p38 MAPK protein expressions were evaluated by western blot. Taurine pretreatment significantly attenuated renal dysfunction and histologic damage, such as renal tubule dilation and loss of brush borders. The pretreatment also decreased the MDA level and attenuated the reduction of SOD activity in the kidney during I/R. Taurine pretreatment also decreased significantly both MMP-2 and MMP-9 mRNA expression and MMP-9 activity induced by I/R. In addition, the activity of p38 MAPK signaling was down-regulated significantly by taurine administration. Inhibition of MMP-2 and MMP-9 expression and MMP-9 activity caused by taurine may be associated with suppression of p38 MAPK activation during I/R induced renal injury in rats. Therefore, taurine administration may prove to be a strategy for attenuating renal I/R injury.