Trapa bispinosa Roxb. extract lowers advanced glycation end-products and increases live births in older patients with assisted reproductive technology: a randomized controlled trial.

BACKGROUND: Advanced glycation end-products (AGE), which accumulate with insulin resistance and aging, impair folliculogenesis and may decrease endometrial receptivity. Hishi (Trapa bispinosa Roxb.) extract, a safe herbal medicine, strongly inhibits AGE formation in vitro. We determined whether Hishi lowers AGE and increases live births in older assisted reproductive technology (ART) patients. METHODS: This prospective randomized open-label controlled trial included 64 patients 38 to 42 years old undergoing ART with or without Hishi extract between June 11, 2015 and July 12, 2019. None had over 2 ART failures, diabetes, uterine anomalies, or exhausted ovarian reserve. After allocation, the Hishi group received Hishi extract (100 mg/day) until late pregnancy or failure. The control group received no extract. Both groups underwent 1 cycle of conventional infertility treatment; 1 long-protocol cycle of ovarian stimulation, oocyte retrieval, in vitro fertilization/intracytoplasmic sperm injection, and fresh embryo transfer (ET); and, if needed, cryopreserved ET until live birth or embryo depletion. Serum AGE were measured before and during ART, as were AGE in follicular fluid (FF). RESULTS: Cumulative live birth rate among 32 Hishi patients was 47%, significantly higher than 16% among 31 controls (p<0.01; RR, 4.6; 95% CI, 1.4 - 15.0; 1 control dropped out). Live birth rate per ET, including fresh and cryopreserved, was significantly higher with Hishi (28% in 47 ET vs. 10% in 49 ET; p<0.05; RR, 3.4; 95% CI, 1.1-10.4). Among variables including age, day-3 FSH, anti-Müllerian hormone, and Hishi, logistic regression identified only Hishi as significantly associated with increased cumulative live birth (p<0.05; OR, 5.1; 95% CI, 1.4 - 18.3). Hishi significantly enhanced oocyte developmental potential, improved endometrial receptivity in natural cycles, and decreased AGE in serum and FF. Larger serum AGE decreases with Hishi were associated with more oocytes becoming day-2 embryos. CONCLUSIONS: Hishi decreased AGE in serum and FF and improved oocyte developmental potential and endometrial receptivity, increasing live births in older patients. Treatment of infertility by AGE reduction represents a new addition to infertility treatment. Therapeutic trials of Hishi for other AGE-associated diseases might be considered. TRIAL REGISTRATION: UMIN registration in Japan ( UMIN000017758 ) on June 1, 2015. https://www.umin.ac.jp/ctr/index.htm.

Oral L-carnitine supplementation increases trimethylamine-N-oxide but reduces markers of vascular injury in hemodialysis patients.

OBJECTIVES: Food or supplement-derived L-carnitine is changed to trimethylamine (TMA) by interstinal microbiota, which is further metabolized to trimethylamine-N-oxide (TMAO), being involved in the promotion of atherosclerosis in animal models. Meanwhile, carnitine deficiency has played a role in accelerated atherosclerosis in hemodialysis (HD) patients. However, effects of oral L-carnitine supplementation on circulating levels of TMAO and markers of vascular injury and oxidative stress in patients on HD remain unclear. In this study, we addressed the issue. METHODS: Thirty-one HD patients with carnitine deficiency were treated with oral L-carnitine (900 mg/d) for 6 months. At baseline and after treatment, clinical variables including circulating levels of carnitine fractions, TMA, TMAO, advanced glycation end products (AGE), soluble forms of intracellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), and malondialdehyde (MDA) were measured. RESULTS: Oral L-carnitine supplementation significantly increased total, free, acyl carnitine, and plasma TMA and TMAO levels, whereas it decreased markers of vascular injury and oxidative stress such as sICAM-1, sVCAM-1, and MDA levels. TMA and TMAO levels at baseline were correlated with each other, and free carnitine was independently associated with TMAO levels. Furthermore, change in AGE values from baseline ([INCREMENT]AGE) was positively correlated with [INCREMENT]sICAM-1 (P = 0.043) and was a sole independent determinant of [INCREMENT]sICAM-1 (R = 0.133, P = 0.043). CONCLUSIONS: This study demonstrated that although oral L-carnitine supplementation was associated with increased TMAO levels, it might be beneficial on vascular injury in patients on HD. Vasculoprotective properties of L-carnitine supplementation in HD patients might be ascribed partly to its inhibitory actions on AGE.

Amelioration of experimental autoimmune uveoretinitis by inhibition of glyceraldehyde-derived advanced glycation end-product formation.

AGEs are permanently modified macromolecule derivatives that form through nonenzymatic glycation of amino groups of proteins. Glycer-AGEs are highly toxic and play an important role in the pathogenesis of chronic inflammatory diseases. However, the contribution of glycer-AGEs to the pathogenesis of uveitis is unclear. In this study, we measured serum levels of glycer-AGEs in 100 patients with endogenous uveitis (22 with HLA-B27-associated uveitis, 20 with VKH disease, 14 with Behçet's disease, and 44 with sarcoidosis) and 33 healthy volunteers. We then examined the effect of the AGE inhibitor in a mouse model of human endogenous uveitis (EAU) by continuous oral administration of pyridoxamine at 200 or 400 mg/kg/day. Regardless of the etiology, serum glycer-AGE levels were significantly higher in patients with uveitis than in healthy subjects. Treatment with 400 mg/kg pyridoxamine significantly reduced the clinical and histological severity of EAU and was accompanied by a significant decrease in serum and retinal glycer-AGE levels and suppression of translocation of NF-κB p65 into the nucleus of retinal cells. Serum glycer-AGE levels may therefore serve as a biomarker of human uveitis, as well as systemic inflammation, and may contribute to the progression of uveitis, including diabetic iritis, via the activation of NF-κB.

Sulforaphane inhibits advanced glycation end product-induced pericyte damage by reducing expression of receptor for advanced glycation end products.

Advanced glycation end products (AGEs) not only inhibit DNA synthesis but also play a role in diabetic retinopathy by evoking apoptosis and inflammation in retinal pericytes via interaction with a receptor for AGE (RAGE). Similarly, sulforaphane, which is a naturally occurring isothiocyanate that is found in widely consumed cruciferous vegetables, protects against oxidative stress-induced tissue damage. Therefore, we hypothesized that sulforaphane could inhibit AGE-induced pericytes injury through its antioxidative properties. Advanced glycation end product stimulated superoxide generation as well as RAGE gene and protein expression in bovine-cultured retinal pericytes, and these effects were prevented by the treatment with sulforaphane. Antibodies directed against RAGE also blocked AGE-evoked reactive oxygen species generation in pericytes. Sulforaphane and antibodies directed against RAGE significantly inhibited the AGE-induced decrease in DNA synthesis, apoptotic cell death, and up-regulation of monocyte chemoattractant protein 1 messenger RNA levels in pericytes. For the first time, the present study demonstrates that sulforaphane could inhibit DNA synthesis, apoptotic cell death, and inflammatory reactions in AGE-exposed pericytes, partly by suppressing RAGE expression via its antioxidative properties. Blockade of the AGE-RAGE axis in pericytes by sulforaphane might be a novel therapeutic target for the treatment of diabetic retinopathy.

DNA aptamer raised against advanced glycation end products inhibits melanoma growth in nude mice.

Epidemiological studies have suggested that diabetes is associated with an increased risk of cancer. However, the underlying molecular mechanism remains unclear. We investigated here whether DNA aptamer directed against advanced glycation end products (AGE-aptamer) inhibited melanoma growth in nude mice. G361 melanoma cells were injected intradermally into the upper flank of athymic nude mice. Mice received continuous intraperitoneal infusion (0.136 µg/day) of either AGE-aptamer (n=9) or Control-aptamer (n=8) by an osmotic mini pump. Tumor volume was measured at 4-day interval, and G361 melanoma was excised at day 43 after the aptamer treatment. We further examined the effects of AGE-aptamer on proliferation of AGE-exposed endothelial cells and G361 cells. AGE-aptamer significantly inhibited the in vivo-tumor growth of G361 melanoma. Immunohistochemical and western blotting analyses of G361 melanoma revealed that AGE-aptamer decreased expression levels of proliferating nuclear antigen, CD31 and Mac-3, markers of endothelial cells and macrophages, respectively. AGE-aptamer significantly decreased the number of tumor-associated vessels. AGE, receptor for AGE (RAGE) and vascular endothelial growth factor levels were also reduced in AGE-aptamer-treated G361 melanoma. AGE-aptamer inhibited the AGE-induced proliferation and tube formation of endothelial cells as well as the growth of G361 cells in vitro. The present findings suggest that AGE-aptamer could inhibit the AGE-RAGE axis in G361 melanoma and resultantly suppress the tumor growth in nude mice by blocking the angiogenesis. AGE-aptamer might be a novel therapeutic strategy for preventing the progression of malignant melanoma in diabetes.

Glucagon-like peptide-1 receptor agonist inhibits asymmetric dimethylarginine generation in the kidney of streptozotocin-induced diabetic rats by blocking advanced glycation end product-induced protein arginine methyltranferase-1 expression.

Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in diabetic nephropathy. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, contributes to diabetic nephropathy. We have found that glucagon-like peptide-1 (GLP-1) inhibits the AGE-induced inflammatory reactions in endothelial cells. However, effects of GLP-1 on the AGE-RAGE-ADMA axis are unknown. This study examined the effects of GLP-1 on reactive oxygen species (ROS) generation, gene expression of protein arginine methyltransfetase-1 (PRMT-1), an enzyme that mainly generates ADMA, and ADMA levels in human proximal tubular cells. Streptozotocin-induced diabetic rats received continuous i.p. infusion of 0.3 µg of vehicle or 1.5 µg of the GLP-1 analog exendin-4 per kilogram of body weight for 2 weeks. We further investigated whether and how exendin-4 treatment reduced ADMA levels and renal damage in streptozotocin-induced diabetic rats. GLP-1 inhibited the AGE-induced RAGE and PRMT-1 gene expression, ROS, and ADMA generation in tubular cells, which were blocked by small-interfering RNAs raised against GLP-1 receptor. Exendin-4 treatment decreased gene expression of Rage, Prmt-1, Icam-1, and Mcp-1 and ADMA level; reduced urinary excretions of 8-hydroxy-2'-deoxyguanosine and albumin; and improved histopathologic changes of the kidney in diabetic rats. Our present study suggests that GLP-1 receptor agonist may inhibit the AGE-RAGE-mediated ADMA generation by suppressing PRMT-1 expression via inhibition of ROS generation, thereby protecting against the development and progression of diabetic nephropathy.

MK615 decreases RAGE expression and inhibits TAGE-induced proliferation in hepatocellular carcinoma cells.

AIM: To investigate the proliferative effect of advanced glycation end-products (AGEs) and the role of their cellular receptor (RAGE) on hepatocellular carcinoma (HCC) cells, and the inhibitory effects of MK615, an extract from Japanese apricot, against AGEs were also evaluated. METHODS: Two HCC cell lines, HuH7 and HepG2, were used. Expression of RAGE was investigated by polymerase chain reaction, Western blotting, and flow cytometry (FACS). The effect of MK615 on RAGE expression was also evaluated by FACS. The proliferative effects of a control (unglycated bovine serum albumin), glucose-derived AGEs (Glc-AGE), and glyceraldehyde-derived AGEs (Glycer-AGE), and the anti-proliferative effect of MK615 against AGEs, were evaluated using MTT assays. RESULTS: Expression of RAGE was confirmed at both the mRNA and protein levels in both HuH7 and HepG2. FACS revealed that the level of RAGE expression was higher in HuH7 than in HepG2. Treatment with 0.1 µg/mL MK615 decreased the expression level of RAGE from 24.3% to 3.7% in HuH7 and from 6.2% to 4.8% in HepG2. The growth indices for the control, Glc-AGE, and Glycer-AGE were 1.06 ± 0.08, 0.99 ± 0.04, and 1.38 ± 0.05, respectively, in HuH7 (P = 0.037), and were 1.03 ± 0.04, 1.04 ± 0.03, and 1.07 ± 0.05, respectively, in HepG2 (P > 0.05). When the cells were cultured simultaneously with Glycer-AGE and MK615, MK615 abrogated the proliferative effect of Glycer-AGE in HuH7. CONCLUSION: Only Glycer-AGE has a proliferative effect on HuH7, which expresses a higher level of RAGE. MK615 suppresses the proliferative effect of Glycer-AGE on HuH7 by decreasing the expression of RAGE.