Blueberry Stem Extract Prevents Lacrimal Hyposecretion in Non-obese Diabetic Mice via Activation of AMPK.

BACKGROUND/AIM: Tears secreted from the lacrimal gland are essential for preserving the ocular surface. Thus, dysfunction of the lacrimal gland in Sjögren's syndrome (SS) can lead to dry eye, resulting in a reduced quality of life. We previously reported that blueberry 'leaf' water extract prevents lacrimal hyposecretion in male non-obese diabetic (NOD) mice in a SS-like model. In this study, we investigated the effect of blueberry 'stem' water extract (BStEx) on lacrimal hyposecretion in NOD mice. MATERIALS AND METHODS: Male NOD mice were fed 1% BStEx or control (AIN-93G) for 2, 4, or 6 weeks from 4 weeks of age. Pilocarpine-induced tear secretion was measured using a phenol red-impregnated thread. The lacrimal glands were histologically evaluated by HE staining. Inflammatory cytokine levels in the lacrimal glands were measured using ELISA. Immunostaining was performed to examine aquaporin 5 (AQP5) localization. The expression levels of autophagy-related proteins, AQP5, and phosphorylated AMPK were measured using western blotting. RESULTS: After feeding BStEx to mice for 4 or 6 weeks, tear volume was observed to have increased in the BStEx group compared with that in the control group. There were no significant differences in inflammatory cell infiltration, autophagy-related protein expression, or the localization and expression of AQP5 in the lacrimal glands between the two groups. In contrast, AMPK phosphorylation increased in the BStEx group. CONCLUSION: BStEx prevented lacrimal hyposecretion in the SS-like model of male NOD mice, probably by opening tight junctions via the activation of AMPK in lacrimal acinar cells.

Blueberry Leaf Extract Prevents Lacrimal Hyposecretion in Sjögren's Syndrome-like Model of Non-obese Diabetic Mice.

BACKGROUND/AIM: This study evaluated the effect of blueberry leaf hot water extract (BLEx) on Sjögren's syndrome (SS)-like lacrimal hyposecretion in male non-obese diabetic (NOD) mice. MATERIALS AND METHODS: NOD or BALB/c mice were fed 1% BLEx or control (AIN-93G) for 2 weeks from the age of 4 to 6 weeks. Pilocarpine-induced tear volume was measured using a phenol red-impregnated thread. The lacrimal glands were evaluated histologically by H&E staining. The IL-1ß and TNF-α levels in the lacrimal gland tissue were measured by ELISA. The mRNA expression levels of secretion-related proteins were measured by real-time PCR. LC3 I/II and arginase 1 expression levels were measured by western blot. RESULTS: After feeding with BLEx, pilocarpine-induced tear secretion in NOD mice was increased. In contrast, the mRNA expression levels of the cholinergic muscarinic M3 receptor, aquaporin 5, and ion channels related to lacrimal secretion were not changed by BLEx administration. In addition, the protein expression of arginase 1, which was recently reported to be involved in tear hyposecretion in NOD mice, was also not improved by BLEx administration. Although infiltration in the lacrimal gland of NOD mice was not decreased, the levels of TNF-α and the autophagy-related protein LC3 were significantly suppressed by BLEx treatment. CONCLUSION: BLEx treatment may ameliorate lacrimal hyposecretion in NOD mice by delaying the progression of autoimmune disease by suppressing autophagy in lacrimal glands.

Blueberry stem extract and stem active components prevent blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro.

Blue light causes retinal damage that can lead to ocular diseases such as age-related macular degeneration. In this study, we determined the protective effect of blueberry stem extract (BStEx) and active components on blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage in vitro. Photoreceptor cells cultured in the presence of BStEx or components were exposed to blue light to induce cell damage. BStEx, fractions of BStEx containing proanthocyanidins, chlorogenic acid, catechin, and epicatechin prevented the cell damage and/or inhibited the generation of reactive oxygen species (ROS). Furthermore, BStEx reduced apoptosis and cell death, and inhibited the phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase leading to cellular apoptosis induced by blue light exposure. These findings suggest that BStEx and components exert a protective effect against blue light-induced photoreceptor cell damage through the inhibition of MAPK phosphorylation and ROS production.

Effects of Dietary Blueberry (Vaccinium ashei Reade) Leaves on Mildly Postprandial Hypertriglyceridemia.

Prevention of postprandial hypertriglyceridemia is an important consideration for reducing the risk of developing cardiovascular disease. While blueberry fruits have been reported to ameliorate lipid metabolism in humans, there are only few research reports on the effects of blueberry leaves (BL). Here, we investigated the efficacy of BL on postprandial hyperlipidemia in subjects with high fasting triacylglycerol (TG) concentrations. Randomized, double-blind, cross-over design study was conducted. The subjects consumed a BL containing beverage or a placebo beverage before a fat-enriched test meal. Blood samples were collected prior to and 1, 2, 3, 4, and 5 hours after consuming the test beverage. The postprandial serum TG and remnant-like particle cholesterol (RLP-C) concentrations were significantly lower in the BL beverage compared with those in the placebo beverage. Additionally, BL was more effective in subjects with high fasting ghrelin with gastric emptying function. In current study, fasting ghrelin correlated with the increase in postprandial serum TG, suggesting that BL ameliorates hypertriglyceridemia through delayed gastric emptying. In conclusion, this pilot study suggests that BL may be useful as an early dietary therapy for treating postprandial hyperlipidemia.

Blueberry Leaf Polyphenols Prevent Body Fat Accumulation in Mice Fed High-fat, High-sucrose Diet.

Blueberry leaf is currently a popular dietary supplement. Effects of dietary blueberry leaf and its active components on body fat accumulation were examined. C57BL/6J mice were fed high-fat, high-sucrose diet with or without 3% blueberry leaf extract (BLEx) or 3% concentrated-polyphenolic BLEx (CP BLEx) for 8 weeks. Compared to mice fed a high-fat, high-sucrose diet without blueberry leaf, BLEx and CP BLEx significantly reduced body weight and adipose tissue weight gain. Adipocytes were also smaller and and liver lipid accumulatioin was significantly inhibited in mice fed either BLEx or CP BLEx. These effects tended to be more pronounced in mice fed CP BLEx compared to in mice fed BLEx. Together, results suggest that blueberry leaf inhibits body fat accumulation typically observed in mice fed a high-fat, high-sucrose diet, and that inhibition is attributable to polyphenolic components in leaf extracts.

Direct-Injection Electron Ionization-Mass Spectrometry Metabolomics Method for Analyzing Blueberry Leaf Metabolites That Inhibit Adult T-cell Leukemia Proliferation.

Metabolic profiling is often used to identify possible correlations between a compound's metabolic profile and biological activity. Direct-injection electron ionization-mass spectrometry "fingerprinting" is useful for characterizing biological materials. We demonstrate the utility of direct-injection electron ionization-mass spectrometry for metabolic profiling using 100 different extracts of leaves from 20 blueberry cultivars collected at 5 time points from April to December 2008. A qualitative direct-injection electron ionization-mass spectrometry method was used to profile the major and/or minor constituents in the blueberry leaf extracts. Blueberry leaf extracts could be distinguished by principal component analysis based on the absolute intensity of characteristic fragment ions. Twenty cultivars were categorized into four species, and the most appropriate discriminative marker m/z value for identifying each cultivar was selected statistically. Correlated m/z values indicating the collection month were determined in the same analysis, and air temperature variance factors were extracted from score plots by principal component analysis. We previously reported that blueberry extracts inhibit the proliferation of adult T-cell leukemia cells. Leaves of Vaccinium virgatum collected in December of 2008 exhibited significantly greater inhibition of adult T-cell leukemia cell proliferation than other species. Highly bioactive cultivars or species were identified by direct-injection electron ionization-mass spectrometry metabolomics analysis of blueberry leaf extracts. The components extracted based on our direct-injection electron ionization-mass spectrometry analyses could be used to construct a model to predict anti-adult T-cell leukemia bioactivity. This is the first study to report a relationship between seasonal variation and bioactivity of natural products using a direct-injection electron ionization-mass spectrometry metabolomics method.