Date palm (Phoenix dactylifera L.) fruit's polyphenols as potential inhibitors for human amylin fibril formation and toxicity in type 2 diabetes.

BACKGROUND: ß-Cell death is the key feature of type 2 diabetes mellitus (T2DM). The misfolding of human Islet Amyloid Polypeptide (hIAPP) is regarded as one of the causative factors of T2DM. Recent studies suggested that a diet based on date fruits presents various health benefits, as these fruits are naturally enriched in plant polyphenols. METHOD: In this study, we used a broad biophysical approach, using cell biology techniques and bioinformatic tools, to demonstrate that various polyphenols from date palm (Phoenix dactylifera L.) fruit significantly inhibited hIAPP aggregation and cytotoxicity. RESULT: Our results suggest that all of the polyphenols showed inhibitory effects, albeit varied, on the formation of toxic hIAPP amyloids. Correlation between cell viability assay, permeabilization of synthetic phospholipid vesicles tests, and ANS florescence measurements, revealed that both classes of polyphenols protected INS-1E cells from the toxicity of amylin aggregates. Docking results showed that the used polyphenols physically interacted with both hIAPP amyloidogenic region (residues Ser20-Ser29) and the non-amyloidogenic regions via hydrophobic and hydrogen interactions, thus reducing aggregation levels. CONCLUSION: These findings highlight the benefits of consuming dates and the great potential of its polyphenols as a potential therapy for the prevention and treatment of T2DM as well as for many other amyloid-related diseases.

Dietary Intake of Rosmarinic Acid Increases Serum Inhibitory Activity in Amyloid A Aggregation and Suppresses Deposition in the Organs of Mice.

Serum amyloid A (SAA) is one of the most important precursor amyloid proteins and plays a vital step in AA amyloidosis, although the underlying aggregation mechanism has not been elucidated. Since SAA aggregation is a key step in this pathogenesis, inhibitors are useful to prevent and treat AA amyloidosis, serving as tools to investigate the pathogenic mechanism. In this study, we showed that rosmarinic acid (RA), which is a well-known inhibitor of the aggregation of amyloid ß (Aß), displayed inhibitory activity against SAA aggregation in vitro using a microliter-scale high-throughput screening (MSHTS) system with quantum-dot nanoprobes. Therefore, we evaluated the amyloid aggregation inhibitory activity of blood and the deposition of SAA in organs by feeding mice with Melissa officinalis extract (ME) containing RA as an active substance. Interestingly, the inhibitory activity of ME-fed mice sera for SAA and Aß aggregation, measured with the MSHTS system, was higher than that of the control group. The amount of amyloid deposition in the organs of ME-fed mice was lower than that in the control group, suggesting that the SAA aggregation inhibitory activity of serum is associated with SAA deposition. These results suggest that dietary intake of RA-containing ME enhanced amyloid aggregation inhibitory activity of blood and suppressed SAA deposition in organs. This study also demonstrated that the MSHTS system could be applied to in vitro screening and to monitor comprehensive activity of metabolized foods adsorbed by blood.

Natural product-based amyloid inhibitors.

Many chronic human diseases, including multiple neurodegenerative diseases, are associated with deleterious protein aggregates, also called protein amyloids. One common therapeutic strategy is to develop protein aggregation inhibitors that can slow down, prevent, or remodel toxic amyloids. Natural products are a major class of amyloid inhibitors, and several dozens of natural product-based amyloid inhibitors have been identified and characterized in recent years. These plant- or microorganism-extracted compounds have shown significant therapeutic potential from in vitro studies as well as in vivo animal tests. Despite the technical challenges of intrinsic disordered or partially unfolded amyloid proteins that are less amenable to characterizations by structural biology, a significant amount of research has been performed, yielding biochemical and pharmacological insights into how inhibitors function. This review aims to summarize recent progress in natural product-based amyloid inhibitors and to analyze their mechanisms of inhibition in vitro. Major classes of natural product inhibitors and how they were identified are described. Our analyses comprehensively address the molecular interactions between the inhibitors and relevant amyloidogenic proteins. These interactions are delineated at molecular and atomic levels, which include covalent, non-covalent, and metal-mediated mechanisms. In vivo animal studies and clinical trials have been summarized as an extension. To enhance natural product bioavailability in vivo, emerging work using nanocarriers for delivery has also been described. Finally, issues and challenges as well as future development of such inhibitors are envisioned.

Long-term consumption of fish oil partially protects brain tissue from age-related neurodegeneration.

The purpose of this study was to determine the effect of fish oil supplementation on aging in the cerebral cortex, hippocampus and cerebellum of rats. Results of biochemical and histological analyses of brain tissue collected from young rats (age: 2 months) prior to the experiment were compared with the results obtained from the 14-month-old animals assigned to the control and supplemented group. Total polyunsaturated fatty acid (PUFA) composition and thiobarbituric acid reactive substance (TBARS) levels were assessed in the examined brain regions. Furthermore, the presence of lipofuscin and amyloid-ß, as well as the number of apoptotic and proliferative cells, was determined in the brain tissue. The analyses revealed that the number of proliferative neurons was significantly higher in the fish oil treated group in the cerebral cortex, hippocampus proper and dentate gyrus. Furthermore, in animals fed the fish oil-supplemented diet, amyloid-ß plaques were not observed in the examined brain regions. These results suggest that fish oil supplementation has a neuroprotective effect on the process of proliferation and may protect against spontaneous amyloidosis in the brain.

Malnutrition at diagnosis predicts mortality in patients with systemic immunoglobulin light-chain amyloidosis independently of cardiac stage and response to treatment.

BACKGROUND: Nutrition status was shown to be a prognostic factor in patients with immunoglobulin light-chain amyloidosis (AL). However, malnutrition was associated with cardiac involvement, thus suggesting potential interactions. This study aim was to clarify the association among nutrition status, cardiac stage, and mortality in AL. METHODS: One hundred twenty-eight consecutive newly diagnosed, treatment-naïve patients with histologically confirmed AL were enrolled. Anthropometric, biochemical, and clinical variables were assessed. RESULTS: At multivariable Cox proportional hazard analysis, body mass index (BMI) < 22 kg/m(2) (HR = 1.98, 95% CI = 1.09-3.56) and unintentional 6-month weight loss (WL) ≥ 10% (HR = 1.94, 95% CI = 1.00-3.74) resulted in independent predictors of survival after controlling for hematologic response to treatment (HR = 0.27, 95% CI = 0.14-0.53) and cardiac stage (Mayo Clinic stage III, HR = 4.42, 95% CI = 2.61-7.51). There was no effect modification of malnutrition on mortality by cardiac stage (P for interaction = .27). Moderate and severe malnutrition (prevalence: 21.9% and 7.8%, respectively) similarly increased the risk of death (HR = 3.09, 95% CI = 1.75-5.46; 2.88, 95% CI = 1.23-6.72, respectively). CONCLUSIONS: In AL, malnutrition at diagnosis is a frequent comorbidity that affects the prognosis independently of hematologic response to treatment and cardiac stage. Nutrition status should be systematically considered in future intervention trials in AL. Nutrition support trials are warranted.

Reversible pathologic and cognitive phenotypes in an inducible model of Alzheimer-amyloidosis.

Transgenic mice that express mutant amyloid precursor protein (APPsi) using tet-Off vector systems provide an alternative model for assessing short- and long-term effects of Aß-targeting therapies on phenotypes related to the deposition of Alzheimer-type amyloid. Here we use such a model, termed APPsi:tTA, to determine what phenotypes persist in mice with high amyloid burden after new production of APP/Aß has been suppressed. We find that 12- to 13-month-old APPsi:tTA mice are impaired in cognitive tasks that assess short- and long-term memories. Acutely suppressing new APPsi/Aß production produced highly significant improvements in performing short-term spatial memory tasks, which upon continued suppression translated to superior performance in more demanding tasks that assess long-term spatial memory and working memory. Deficits in episodic-like memory and cognitive flexibility, however, were more persistent. Arresting mutant APPsi production caused a rapid decline in the brain levels of soluble APP ectodomains, full-length APP, and APP C-terminal fragments. As expected, amyloid deposits persisted after new APP/Aß production was inhibited, whereas, unexpectedly, we detected persistent pools of solubilizable, relatively mobile, Aß42. Additionally, we observed persistent levels of Aß-immunoreactive entities that were of a size consistent with SDS-resistant oligomeric assemblies. Thus, in this model with significant amyloid pathology, a rapid amelioration of cognitive deficits was observed despite persistent levels of oligomeric Aß assemblies and low, but detectable solubilizable Aß42 peptides. These findings implicate complex relationships between accumulating Aß and activities of APP, soluble APP ectodomains, and/or APP C-terminal fragments in mediating cognitive deficits in this model of amyloidosis.

Effects of the main green tea polyphenol epigallocatechin-3-gallate on cardiac involvement in patients with AL amyloidosis.

BACKGROUND: Amyloid light chain (AL) amyloidosis is a rare disease with poor prognosis and limited therapeutic alternatives. Recently, one clinical case with cardiac involvement, as well as a compelling evidence of green tea polyphenol, epigallocatechin-3-gallate (EGCG), inducing the formation of benign aggregation products that do not polymerize into fibrils were published. This is a report of the cardiac effects of green tea consumption in these patients. METHODS: Patients with known cardiac involvement in AL amyloidosis were examined by routine cardiovascular examinations that took place every 3-6 months. Of 59 patients with cardiac involvement, 11 revealed a decrease of at least 2 mm of interventricular wall thickness, after initiation of regular green tea consumption (GT). A matched historic control group (n = 22) was selected. Comprehensive echocardiography was conducted at every control examination and analyzed offline by two independent examiners. RESULTS: GT patients showed an improvement in New York Heart Association (NYHA) class from a median of 3 (25th, 75th percentiles: 2, 3) to 2 (2, 3), P = 0.038. Septal thickness decreased from 18 (18, 20) to 16 (16, 17) mm, P = 0.021. Left ventricular mass index decreased from 175 (154, 180) to 133 (128, 154) g/m(2), P = 0.007. Comparing both groups, an increase in left ventricular ejection fraction could be found in the GT group, 65 (51, 73) versus 53 (47, 59)%, P = 0.012. These changes could not be observed in the control group. CONCLUSION: Consumption of green tea polyphenol EGCG in patients with cardiac involvement with AL amyloidosis causes a significant decrease in left ventricular wall thickness and mass, as well as an improvement in NYHA functional classification and left ventricular ejection fraction.

Effect of dietary unsaturated fatty acids on senile amyloidosis in senescence-accelerated mice.

Effects of dietary oils on aging were investigated in senescence-accelerated mice. For 26 weeks, mice were fed purified diets containing 4% olive oil, safflower oil, perilla oil, or fish oil. Serum total, high-density lipoprotein cholesterol, and apolipoprotein A-II (ApoA-II) were significantly lower in the fish oil group than in the perilla oil group, and these were significantly lower than in the olive oil or safflower oil group. The olive oil and safflower oil groups had significantly fewer ApoA-II amyloid fibril (AApoAII) deposits and anti-single-strand DNA (ssDNA) antibodies than the fish oil or perilla oil group, and the fish oil diet induced significantly more AApoAII deposits and anti-ssDNA antibodies than did the perilla oil diet. Survival decreased earlier in the fish oil group than in the other groups (as seen in the survival curve). The results suggest that greater the degree of unsaturation of dietary fatty acids, greater is the tendency for accelerated senescence.

Early vitamin E supplementation in young but not aged mice reduces Abeta levels and amyloid deposition in a transgenic model of Alzheimer's disease.

Increased brain oxidative stress is a key feature of Alzheimer's disease (AD) and manifests predominantly as lipid peroxidation. However, clinical evidence that antioxidants can affect the clinical course of the disease is limited. In the present study, we investigated the effect of the antioxidant Vitamin E on the AD-like phenotype when given to a transgenic mouse model (Tg2576) of the disease before or after the amyloid plaques are deposited. One group of Tg2576 received Vitamin E starting at 5 months of age until they were 13 months old, the second group started at 14 months of age until they were 20 months old. Brain levels of 8,12-iso-iPF2alpha-VI, a specific marker of lipid peroxidation, were significantly reduced in both groups of mice receiving Vitamin E compared with placebo. Tg2576 administered with Vitamin E at a younger age showed a significant reduction in Abeta levels and amyloid deposition. By contrast, mice receiving the diet supplemented with Vitamin E at a later age did not show any significant difference in either marker when compared with placebo. These results support the hypothesis that oxidative stress is an important early event in AD pathogenesis, and antioxidant therapy may be beneficial only if given at this stage of the disease process.

Dietary fat modulation of apoA-II metabolism and prevention of senile amyloidosis in the senescence- accelerated mouse.

Senescence-accelerated mouse-prone (SAMP1; SAMP1@Umz) is an animal model of senile amyloidosis with apolipoprotein A-II (apoA-II) amyloid fibril (AApoAII) deposits. This study was undertaken to investigate the effects of dietary fats on AApoAII deposits in SAMP1 mice when purified diets containing 4% fat as butter, safflower oil, or fish oil were fed to male mice for 26 weeks. The serum HDL cholesterol was significantly lower (P < 0.01) in mice on the diet containing fish oil (7.4 +/- 3.0 mg/dl) than in mice on the butter diet (38.7 +/- 12.5 mg/dl), which in turn had significantly lower (P < 0.01) HDL levels than mice on the safflower oil diet (51.9 +/- 5.6 mg/dl). ApoA-II was also significantly lower (P < 0.01) in mice on the fish oil diet (7.6 +/- 2.7 mg/dl) than on the butter (26.9 +/- 7.3 mg/dl) or safflower oil (21.6 +/- 3.7 mg/dl) diets. The mice fed fish oil had a significantly greater ratio (P < 0.01) of apoA-I to apoA-II, and a smaller HDL particle size than those fed butter and safflower oil. Severe AApoAII deposits in the spleen, heart, skin, liver, and stomach were shown in the fish oil group compared with those in the butter and safflower oil groups (fish oil > butter > safflower oil group, P < 0.05). These findings suggest that dietary fats differ in their effects on serum lipoprotein metabolism, and that dietary lipids may modulate amyloid deposition in SAMP1 mice.

Crohn's disease associated with renal amyloidosis successfully treated with an elemental diet.

We report a case of Crohn's disease associated with nephrotic syndrome due to renal amyloidosis in a 21-year-old man in whom remission of both Crohn's disease and the nephrotic syndrome has been maintained with an elemental diet. The patient developed toxic megacolon and nephrotic syndrome due to renal amyloidosis. Intensive intravenous prednisolone therapy with total parenteral nutrition was dramatically effective in treating the toxic megacolon and inducing remission in Crohn's disease and afterward, remission of the nephrotic syndrome. Remission of both conditions has been maintained for more than 2 years with the elemental diet. To our knowledge, this is the first confirmed case of Crohn's disease complicated with renal amyloidosis in which only slight proteinuria (below 0.3 g/day) was shown with an elemental diet used for a long period.

Preservation of peripheral nerve function in severe uremia during treatment with low protein high calorie diet and surplus of essential amino acids.

Twelve patients with severe chronic renal failure (serum creatinine 7.0-27 mg %), and marked uremic symptoms on a 40 g protein diet, were treated with a caloric-rich diet containing 16-20 g protein, supplemented with the 8 essential amino acids (1.1-2.2 g N) and histidine (0.23-0.45 g N)in the form of tablets for periods between 3 and 34 months. During the treatment the serum urea-N fell, and the uremic symptoms subsided or diminished without the patient exhibiting signs of malnutrition. The nerve function was followed with quantitative and semiquantitative neurological tests (among others, determination of vibratory perception thresholds and nerve conduction times). Initially all patients but 2 had signs of neuropathy as measured by these methods. During the course of treatment no deterioration of peripheral nerve function was recorded in any of the patients, several of whom had had serum creatinine conceptrations above 15 mg % for long periods. We conclude that conservative treatment with N-poor diet in far advanced chronic renal failure may prevent the further development of peripheral neuropathy provided that adequatecaloried and essential amino acids (2-3 times the minimal requirements) are supplied. The results suggest that, in addition to uremic toxines, malnutrition is a factor of importance for the developments of of uremic neuropathy.