Examining the potential clinical value of curcumin in the prevention and diagnosis of Alzheimer’s disease

Tau hyperphosphorylation and P-CREB reduction are involved in acrylamide-induced spatial memory impairment: Suppression by curcumin

Acrylamide (ACR) is an axonal toxicant that produces peripheral neuropathy in laboratory animals and humans. Epidemiological study found that diet ACR exposure was associated with a mild cognitive decline in men. However, limited information is available as regards its potential and underlying mechanism to cause memory alterations. Curcumin is a polyphenol with neuroprotective and cognitive-enhancing properties. In this study, we aimed to investigate the mechanism of ACR-induced spatial memory impairment and the beneficial effect of curcumin. ACR exposure at 10 mg/kg/d for 7 weeks caused slight gait abnormality and spatial memory deficits, which was associated with an activation of glial cells, a reduction of phosphorylated cAMP response elements binding protein (P-CREB) and an aggregation of hyperphosphorylated tau including p-tau (Ser262), AT8 (p-tau Ser202/Thr205) and PHF1 (p-tau Ser396/404) in the hippocampus and cortex. ACR markedly regulate the expression of glycogen synthase kinase-3β (GSK-3β) and cyclin-dependent kinase-5 (cdk5) to accelerate tau hyperphosphorylation. ACR inhibited the protein phosphatase 2A (PP2A) and lysosomal protease cathepsin D to decrease the p-tau dephosphorylation and degradation. The P-CREB and brain derived neurotrophic factor (BDNF) were significantly decreased by ACR. The upstream signalings of P-CREB, extracellular signal-related kinase (ERK) and Akt were markedly inhibited. The protein kinase RNA-like endoplasmic reticulum kinase (PERK) -eukaryotic initiation factor-2α (eIF2α) - activating transcription factor 4 (ATF4) signaling which negatively regulate memory processes by suppressing CREB was activated by ACR. Curcumin alleviated ACR-induced spatial memory impairment through reversing tau abnormalities and P-CREB reduction in the hippocampus. These results offered deeper insight into the mechanisms of and presented a potential new treatment for ACR-induced neurotoxicity.

Preventive Effects of Dairy Products on Dementia and the Underlying Mechanisms

Alongside the rapid population aging occurring worldwide, the prevention of age-related memory decline and dementia has become a high priority. Dairy products have many physiological effects owing to their contents of lactic acid bacteria and the fatty acids and peptides generated during their fermentation. In particular, several recent studies have elucidated the effects of fermented dairy products on cognitive function. Epidemiological and clinical evidence has indicated that fermented dairy products have preventive effects against dementia, including Alzheimer’s disease. Recent preclinical studies have identified individual molecules generated during fermentation that are responsible for those preventive effects. Oleamide and dehydroergosterol have been identified as the agents responsible for reducing microglial inflammatory responses and neurotoxicity. In this review, the protective effects of fermented dairy products and their components on cognitive function, the mechanisms underlying those effects, and the prospects for their future clinical development will be discussed.

Is boiled food spice curcumin still biologically active? An experimental exploration

Background

As the major active component of turmeric (Curcuma longa), curcumin is widely used as a spice and food coloring agent, and also possesses multiple biological activities and therapeutic potential for neurodegenerative diseases. To answer the paradox between curcumin’s biological activities and poor systemic bioavailability, we proposed that degradation products of curcumin may make important contributions to its biological activities, which needs to be verified. In addition, curcumin is usually heated or boiled used as a spice, it is necessary to explore whether boiled curcumin, which degrades readily, is still biologically active.

Methods

Thus, in the present study we investigated the protective effects of curcumin and boiled curcumin mixture on H2O2-induced oxidative damage in PC12 cells, a widely used model for neurons.

Results

Results showed that in spite of high degradation rates, boiled curcumin mixture still possessed similar protective activities like parent curcumin, and could effectively rescue PC12 cells against H2O2-induced damage, via decreasing production of reactive oxygen species and malondialdehyde, reducing caspase-3 and caspase-9 activities. Moreover, curcumin’s degradation products including ferulic acid, vanillin and vanillic acid could also improve PC12 cells survival rate.

Conclusion

Our findings indicated that boiled curcumin mixtures still possessed protective activity for PC12 cells, and supported the contribution of degradation products to biological activities of curcumin.

Use of Curcumin, a Natural Polyphenol for Targeting Molecular Pathways in Treating Age-Related Neurodegenerative Diseases

Progressive accumulation of misfolded amyloid proteins in intracellular and extracellular spaces is one of the principal reasons for synaptic damage and impairment of neuronal communication in several neurodegenerative diseases. Effective treatments for these diseases are still lacking but remain the focus of much active investigation. Despite testing several synthesized compounds, small molecules, and drugs over the past few decades, very few of them can inhibit aggregation of amyloid proteins and lessen their neurotoxic effects. Recently, the natural polyphenol curcumin (Cur) has been shown to be a promising anti-amyloid, anti-inflammatory and neuroprotective agent for several neurodegenerative diseases. Because of its pleotropic actions on the central nervous system, including preferential binding to amyloid proteins, Cur is being touted as a promising treatment for age-related brain diseases. Here, we focus on molecular targeting of Cur to reduce amyloid burden, rescue neuronal damage, and restore normal cognitive and sensory motor functions in different animal models of neurodegenerative diseases. We specifically highlight Cur as a potential treatment for Alzheimer's, Parkinson's, Huntington's, and prion diseases. In addition, we discuss the major issues and limitations of using Cur for treating these diseases, along with ways of circumventing those shortcomings. Finally, we provide specific recommendations for optimal dosing with Cur for treating neurological diseases.

The Mechanisms of Action of Curcumin in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder of the elderly. As the prevalence of AD rises in the 21st century, there is an urgent need for the development of effective pharmacotherapies. Currently, drug treatments target the symptoms of the disease and do not modify or halt the disease progress. Thus, natural compounds have been investigated for their ability to treat AD. This review examines the efficacy of curcumin, a polyphenol derived from turmeric herb, to treat AD. We summarize the in vivo and in vitro research describing the mechanisms of action in which curcumin modifies AD pathology: curcumin inhibits the formation and promotes the disaggregation of amyloid-β plaques, attenuates the hyperphosphorylation of tau and enhances its clearance, binds copper, lowers cholesterol, modifies microglial activity, inhibits acetylcholinesterase, mediates the insulin signaling pathway, and is an antioxidant. In conclusion, curcumin has the potential to be more efficacious than current treatments. However, its usefulness as a therapeutic agent may be hindered by its low bioavailability. If the challenge of low bioavailability is overcome, curcumin-based medications for AD may be in the horizon.

Memory and Brain Amyloid and Tau Effects of a Bioavailable Form of Curcumin in Non-Demented Adults: A Double-Blind, Placebo-Controlled 18-Month Trial

OBJECTIVE

Because curcumin's anti-inflammatory properties may protect the brain from neurodegeneration, we studied its effect on memory in non-demented adults and explored its impact on brain amyloid and tau accumulation using 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile positron emission tomography (FDDNP-PET).

METHODS

Forty subjects (age 51-84 years) were randomized to a bioavailable form of curcumin (Theracurmin® containing 90 mg of curcumin twice daily [N = 21]) or placebo (N = 19) for 18 months. Primary outcomes were verbal (Buschke Selective Reminding Test [SRT]) and visual (Brief Visual Memory Test-Revised [BVMT-R]) memory, and attention (Trail Making A) was a secondary outcome. FDDNP-PET signals (15 curcumin, 15 placebo) were determined in amygdala, hypothalamus, medial and lateral temporal, posterior cingulate, parietal, frontal, and motor (reference) regions. Mixed effects general linear models controlling for age and education, and effect sizes (ES; Cohen's d) were estimated.

RESULTS

SRT Consistent Long-Term Retrieval improved with curcumin (ES = 0.63, p = 0.002) but not with placebo (ES = 0.06, p = 0.8; between-group: ES = 0.68, p = 0.05). Curcumin also improved SRT Total (ES = 0.53, p = 0.002), visual memory (BVMT-R Recall: ES = 0.50, p = 0.01; BVMT-R Delay: ES = 0.51, p = 0.006), and attention (ES = 0.96, p < 0.0001) compared with placebo (ES = 0.28, p = 0.1; between-group: ES = 0.67, p = 0.04). FDDNP binding decreased significantly in the amygdala with curcumin (ES = -0.41, p = 0.04) compared with placebo (ES = 0.08, p = 0.6; between-group: ES = 0.48, p = 0.07). In the hypothalamus, FDDNP binding did not change with curcumin (ES = -0.30, p = 0.2), but increased with placebo (ES = 0.26, p = 0.05; between-group: ES = 0.55, p = 0.02).

CONCLUSIONS

Daily oral Theracurmin may lead to improved memory and attention in non-demented adults. The FDDNP-PET findings suggest that symptom benefits are associated with decreases in amyloid and tau accumulation in brain regions modulating mood and memory.

Can Curcumin Counteract Cognitive Decline? Clinical Trial Evidence and Rationale for Combining ω-3 Fatty Acids with Curcumin

The rate of cognitive decline in the elderly is highly variable. One potential factor contributing to accelerated cognitive decline is chronic systemic inflammation, because it has been linked to cognitive impairment and increased dementia risk. Certain lifestyle factors, such as excess body weight and sedentary behavior, can exacerbate a proinflammatory state in older adults, resulting in chronic low-grade inflammation. Supplementing the diet with curcumin, an anti-inflammatory polyphenolic compound from the curry spice turmeric, is a potential approach to prevent accelerated cognitive decline by counteracting chronic inflammatory processes. Although the anti-inflammatory effects of curcumin are well established, the potential cognitive benefits of curcumin were discovered more recently. Several animal and epidemiologic studies on the effect of curcumin supplementation on cognition showed promising results; however, randomized controlled trials in humans are limited. In this review, we identified 5 randomized controlled trials, of which only 2 observed a beneficial effect of curcumin supplementation on cognition by improving working memory. By critically examining the methodologies of those studies, we identified some limitations, one of which is that none of the studies explored the possibility that anti-inflammatory mechanisms were mediating cognitive benefits (i.e., no study tested participants with low-grade inflammation or measured inflammatory biomarkers). Other factors influencing the likelihood of conclusive outcomes include choice of study population (cognitively unimpaired compared with impaired), study duration, curcumin dose and its bioavailability, and neurocognitive test battery. On the basis of these findings, we offer recommendations for future studies to examine the potential cognitive benefits of curcumin in humans, which include evaluating its effects on cerebral endothelial vasodilator function and boosting its cognitive effects by combining it with long-chain omega-3 (n-3) fatty acids.

Phytochemicals and cognitive/behavioral function in patients with Alzheimer's disease: a scoping review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to explore the existing literature related to phytochemicals and cognitive/behavioral function in patients with Alzheimer's disease, to examine and conceptually map the evidence, and to identify any gaps.The question of this review is: what is the evidence on phytochemicals and cognitive/behavioral function in patients with Alzheimer's disease?

Curcumin potentiates the function of human α7-nicotinic acetylcholine receptors expressed in SH-EP1 cells

Effects of curcumin, a biologically active ingredient of turmeric, were tested on the Ca²⁺ transients induced by the activation of α₇ subunit of the human nicotinic acetylcholine (α₇ nACh) receptor expressed in SH-EP1 cells. Curcumin caused a significant potentiation of choline (1 mM)-induced Ca²⁺ transients with an EC₅₀ value of 133 nM. The potentiating effect of curcumin was not observed in Ca²⁺ transients induced by high K⁺ (60 mM) containing solutions or activation of α₄β₂ nACh receptors and the extent of curcumin potentiation was not altered in the presence of Ca²⁺ channel antagonists nifedipine (1 μM), verapamil (1 μM), ω-conotoxin (1 μM), and bepridil (10 μM). Noticeably the effect of curcumin was not observed when curcumin and choline were co-applied without curcumin pre-incubation. The effect of curcumin on choline-induced Ca²⁺ transients was not reversed by pre-incubation with inhibitors of protein C, A, and CaM kinases. Metabolites of curcumin such as tetrahydrocurcumin, demethylcurcumin, and didemethylcurcumin also caused potentiation of choline-induced Ca²⁺ transients. Notably, specific binding of [¹²⁵I]-bungarotoxin was not altered in the presence of curcumin. Collectively, our results indicate that curcumin allosterically potentiate the function of the α7-nACh receptor expressed in SH-EP1 cells.

Curcumin Acts as a Positive Allosteric Modulator of α7-Nicotinic Acetylcholine Receptors and Reverses Nociception in Mouse Models of Inflammatory Pain

Effects of curcumin, a major ingredient of turmeric, were tested on the function of the α₇-subunit of the human nicotinic acetylcholine (α₇-nACh) receptor expressed in Xenopus oocytes and on nociception in mouse models of tonic and visceral pain. Curcumin caused a significant potentiation of currents induced by acetylcholine (ACh; 100 μM) with an EC₅₀ value of 0.2 µM. The effect of curcumin was not dependent on the activation of G-proteins and protein kinases and did not involve Ca²⁺-dependent Cl^- channels expressed endogenously in oocytes. Importantly, the extent of curcumin potentiation was enhanced significantly by decreasing ACh concentrations. Curcumin did not alter specific binding of [¹²⁵I]α-bungarotoxin. In addition, curcumin attenuated nociceptive behavior in both tonic and visceral pain models without affecting motor and locomotor activity and without producing tolerance. Pharmacological and genetic approaches revealed that the antinociceptive effect of curcumin was mediated by α₇-nACh receptors. Curcumin potentiated the antinociceptive effects of the α₇-nACh receptor agonist N-(3R)-1-azabicyclo[2.2.2]oct-3-yl-4-chlorobenzamide (PNU282987). Collectively, our results indicate that curcumin is a positive allosteric modulator of α₇-nACh receptor and reverses nociception in mouse models of tonic and visceral pain.

The Potential Protective Effect of Curcumin on Amyloid-β-42 Induced Cytotoxicity in HT-22 Cells

Background

We aimed to investigate the effect and mechanism of curcumin (CUR) in Alzheimer's disease (AD).

Methods

Mouse hippocampal neuronal cell line HT-22 was treated with Aβ1–42 and/or CUR, and then cell viability was evaluated by cell counting kit 8, Beclin-l level was detected using western blotting, and the formation of autophagosomes was observed by transmission electron microscopy (TEM). Furthermore, transcriptome sequencing and analysis were performed in cells with Aβ1–42 alone or Aβ1–42 + CUR.

Results

Aβ1–42 treatment significantly inhibited cell viability compared with untreated cells (P < 0.01). After treatment for 48 h, CUR remarkably promoted cell viability compared with cell treated with Aβ1–42 alone (P < 0.01). Compared with cells treated with Aβ1–42 alone, the expression of Beclin-1 was slightly reduced in cells with combined treatment of Aβ1–42 with CUR (P < 0.05). Consistently, TEM results showed that CUR inhibited the formation of autophagosomes in cells treated with Aβ1–42. Furthermore, the protein-protein interaction network showed five key genes, including MYC, Cdh1, Acaca, Egr1, and CCnd1, likely involved in CUR effects.

Conclusions

CUR might have a potential neuroprotective effect by promoting cell viability in AD, which might be associated with cell autophagy. Furthermore, MYC, Cdh1, and Acaca might be involved in the progression of AD.

Curcumin nanoconjugate inhibits aggregation of N-terminal region (Aβ-16) of an amyloid beta peptide

A highly stable system of a polymeric nanoparticle-encapsulated curcumin with gold nanoparticles decorated on the surface for inhibition of Aβ1–16 aggregation.

Alzheimer's Disease: A Journey from Amyloid Peptides and Oxidative Stress, to Biomarker Technologies and Disease Prevention Strategies-Gains from AIBL and DIAN Cohort Studies

Worldwide there are over 46 million people living with dementia, and this number is expected to double every 20 years reaching about 131 million by 2050. The cost to the community and government health systems, as well as the stress on families and carers is incalculable. Over three decades of research into this disease have been undertaken by several research groups in Australia, including work by our original research group in Western Australia which was involved in the discovery and sequencing of the amyloid-β peptide (also known as Aβ or A4 peptide) extracted from cerebral amyloid plaques. This review discusses the journey from the discovery of the Aβ peptide in Alzheimer's disease (AD) brain to the establishment of pre-clinical AD using PET amyloid tracers, a method now serving as the gold standard for developing peripheral diagnostic approaches in the blood and the eye. The latter developments for early diagnosis have been largely achieved through the establishment of the Australian Imaging Biomarker and Lifestyle research group that has followed 1,100 Australians for 11 years. AIBL has also been instrumental in providing insight into the role of the major genetic risk factor apolipoprotein E ɛ4, as well as better understanding the role of lifestyle factors particularly diet, physical activity and sleep to cognitive decline and the accumulation of cerebral Aβ.

Revolution of Alzheimer Precision Neurology. Passageway of Systems Biology and Neurophysiology

The Precision Neurology development process implements systems theory with system biology and neurophysiology in a parallel, bidirectional research path: a combined hypothesis-driven investigation of systems dysfunction within distinct molecular, cellular, and large-scale neural network systems in both animal models as well as through tests for the usefulness of these candidate dynamic systems biomarkers in different diseases and subgroups at different stages of pathophysiological progression. This translational research path is paralleled by an "omics"-based, hypothesis-free, exploratory research pathway, which will collect multimodal data from progressing asymptomatic, preclinical, and clinical neurodegenerative disease (ND) populations, within the wide continuous biological and clinical spectrum of ND, applying high-throughput and high-content technologies combined with powerful computational and statistical modeling tools, aimed at identifying novel dysfunctional systems and predictive marker signatures associated with ND. The goals are to identify common biological denominators or differentiating classifiers across the continuum of ND during detectable stages of pathophysiological progression, characterize systems-based intermediate endophenotypes, validate multi-modal novel diagnostic systems biomarkers, and advance clinical intervention trial designs by utilizing systems-based intermediate endophenotypes and candidate surrogate markers. Achieving these goals is key to the ultimate development of early and effective individualized treatment of ND, such as Alzheimer's disease. The Alzheimer Precision Medicine Initiative (APMI) and cohort program (APMI-CP), as well as the Paris based core of the Sorbonne University Clinical Research Group "Alzheimer Precision Medicine" (GRC-APM) were recently launched to facilitate the passageway from conventional clinical diagnostic and drug development toward breakthrough innovation based on the investigation of the comprehensive biological nature of aging individuals. The APMI movement is gaining momentum to systematically apply both systems neurophysiology and systems biology in exploratory translational neuroscience research on ND.

Use of curcumin in diagnosis, prevention, and treatment of Alzheimer's disease

This review summarizes and describes the use of curcumin in diagnosis, prevention, and treatment of Alzheimer's disease. For diagnosis of Alzheimer's disease, amyloid-β and highly phosphorylated tau protein are the major biomarkers. Curcumin was developed as an early diagnostic probe based on its natural fluorescence and high binding affinity to amyloid-β. Because of its multi-target effects, curcumin has protective and preventive effects on many chronic diseases such as cerebrovascular disease, hypertension, and hyperlipidemia. For prevention and treatment of Alzheimer's disease, curcumin has been shown to effectively maintain the normal structure and function of cerebral vessels, mitochondria, and synapses, reduce risk factors for a variety of chronic diseases, and decrease the risk of Alzheimer's disease. The effect of curcumin on Alzheimer's disease involves multiple signaling pathways: anti-amyloid and metal iron chelating properties, antioxidation and anti-inflammatory activities. Indeed, there is a scientific basis for the rational application of curcumin in prevention and treatment of Alzheimer's disease.

Curcumin: pharmaceutical solids as a platform to improve solubility and bioavailability

The remarkable improvements in the pharmacokinetics and high bioavailability of curcumin polymorphs, amorphous, cocrystals, eutectics, and coamorphous solids are discussed. The importance of pharmaceutical solids in the advanced formulation development of herbal and bioactive molecule curcumin is presented.

Optical Coherence Tomography in Alzheimer's Disease and Other Neurodegenerative Diseases

Over the past decade, a surge of evidence has documented various pathological processes in the retina of patients suffering from mild cognitive impairment, Alzheimer's disease (AD), Parkinson's disease (PD), and other neurodegenerative diseases. Numerous studies have shown that the retina, a central nervous system tissue formed as a developmental outgrowth of the brain, is profoundly affected by AD. Harboring the earliest detectable disease-specific signs, amyloid β-protein (Aβ) plaques, the retina of AD patients undergoes substantial ganglion cell degeneration, thinning of the retinal nerve fiber layer, and loss of axonal projections in the optic nerve, among other abnormalities. More recent investigations described Aβ plaques in the retina located within sites of neuronal degeneration and occurring in clusters in the mid- and far-periphery of the superior and inferior quadrants, regions that had been previously overlooked. Diverse structural and/or disease-specific changes were also identified in the retina of PD, Huntington's disease, and multiple sclerosis patients. The pathological relationship between the retina and brain prompted the development of imaging tools designed to noninvasively detect and monitor these signs in living patients. One such tool is optical coherence tomography (OCT), uniquely providing high-resolution two-dimensional cross-sectional imaging and three-dimensional volumetric measurements. As such, OCT emerged as a prominent approach for assessing retinal abnormalities in vivo, and indeed provided multiple parameters that allowed for the distinction between normal aged individuals and patients with neurodegenerative diseases. Beyond the use of retinal optical fundus imaging, which recently allowed for the detection and quantification of amyloid plaques in living AD patients via a wide-field view of the peripheral retina, a major advantage of OCT has been the ability to measure the volumetric changes in specified retinal layers. OCT has proven to be particularly useful in analyzing retinal structural abnormalities consistent with disease pathogenesis. In this review, we provide a summary of OCT findings in the retina of patients with AD and other neurodegenerative diseases. Future studies should explore the combination of imaging early hallmark signs together with structural-functional biomarkers in the accessible retina as a practical means of assessing risk, disease progression, and therapeutic efficacy in these patients.

6-(Methylsulfonyl) hexyl isothiocyanate as potential chemopreventive agent: molecular and cellular profile in leukaemia cell lines

Numerous laboratory and epidemiological studies show that the risk of developing several types of cancer can be reduced with the employment of natural substances that act with multiple mechanisms. In this context, an important role is played by the isothiocyanates. Recently, 6-(methylsulfonyl)hexyl isothiocyanate (6-MITC), present in the root of Wasabia Japonica, has stimulated the interest of researchers as a chemopreventive agent. In this particular study we have focused on evaluating 6-MITC’s in vitro cytotoxic, cytostatic and cytodifferentiating activities, as well as its pro-apoptotic potential. These effects were investigated by way of flow cytometric analysis of Jurkat and HL-60 cells as well as of healthy lymphocytes extracted from the blood of AVIS donors, in order to verify a potential selectivity of action. The results demonstrate that 6-MITC exerts a stronger cytotoxic effect on tumour cells than on healthy cells. The apoptosis induction exerted by 6-MITC on transformed cells is triggered by an extrinsic pathway, as demonstrated by the statistically significant increase in the percentage of cells with activated caspase-8. It was also observed that 6-MITC is able to limit tumour growth by slowing down and blocking the cell cycle of Jurkat and HL-60 cells respectively, in a dose- and time-related manner, while exerting no activity of any kind on the replication of healthy cells. Finally, by measuring the expression levels of CD-14 and CD-15, 6-MITC showed the ability to induce cytodifferentiation of HL-60 cells into macrophage and granulocytic phenotypes.

Are Astrocytes the Predominant Cell Type for Activation of Nrf2 in Aging and Neurodegeneration?

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates hundreds of antioxidant genes, and is activated in response to oxidative stress. Given that many neurodegenerative diseases including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, Huntington’s disease and multiple sclerosis are characterised by oxidative stress, Nrf2 is commonly activated in these diseases. Evidence demonstrates that Nrf2 activity is repressed in neurons in vitro, and only cultured astrocytes respond strongly to Nrf2 inducers, leading to the interpretation that Nrf2 signalling is largely restricted to astrocytes. However, Nrf2 activity can be observed in neurons in post-mortem brain tissue and animal models of disease. Thus this interpretation may be false, and a detailed analysis of the cell type expression of Nrf2 in neurodegenerative diseases is required. This review describes the evidence for Nrf2 activation in each cell type in prominent neurodegenerative diseases and normal aging in human brain and animal models of neurodegeneration, the response to pharmacological and genetic modulation of Nrf2, and clinical trials involving Nrf2-modifying drugs.

Curcumin attenuates the development of thoracic aortic aneurysm by inhibiting VEGF expression and inflammation

Angiogenesis is an important process in the pathogenesis of aortic aneurysm. The aim of the present study was to investigate the angiogenic balance and the expression of vascular endothelial growth factor (VEGF) in thoracic aortic aneurysm (TAA). A previous study demonstrated that curcumin exerts a marked effect on aortic aneurysm development. Therefore, the present study determined whether curcumin is able to modulate angiogenesis and inflammatory signaling in TAA by collecting human TAA samples and establishing a rat TAA model using periaortic application of CaCl2. TAA rats were treated with curcumin or 1% carboxymethyl cellulose and were sacrificed 4 weeks after the operation. All tissue specimens were analyzed by histological staining, immunohistochemistry and western blotting. Human TAA samples exhibited increased neovascularization and VEGF expression when compared with normal aortic walls. In rat tissues, treatment with curcumin resulted in reduced aneurysm size and restored the wavy structure of the elastic lamellae. In addition, curcumin decreased neovascularization and the expression of VEGF. Immunohistochemical analysis indicated that curcumin significantly inhibited infiltration of cluster of differentiation (CD)3+ and CD68+ cells in TAA. Furthermore, curcumin treatment decreased the expression of vascular cell adhesion molecule‑1, intracellular adhesion molecule‑1, monocyte chemoattractant protein‑1 and tumor necrosis factor‑α. Collectively, the results demonstrated that angiogenesis and VEGF expression were increased in the aortic wall in TAA. Treatment with curcumin inhibited TAA development in rats, which was associated with suppression of VEGF expression. In addition, curcumin attenuated inflammatory cell infiltration and suppressed inflammatory factor expression in the periaortic tissue of TAA.

A review of curcumin as a biological stain and as a self-visualizing pharmaceutical agent

Curcumin has been widely used to color textiles but, unlike other natural dyes such as hematoxylin or saffron, it rarely has been discussed as a biological stain. Aspects of the physicochemistry of curcumin relevant to biological staining and self-visualization, i.e., its acidic properties, lipophilicity, metal and pseudometal complexes, and optical properties, are summarized briefly here. Reports of staining of non-living biological specimens in sections and smears, both fixed and unfixed, including specimens embedded in resin, are summarized here. Staining of amyloid, boron and chromatin are outlined and possible reaction mechanisms discussed. Use of curcumin as a vital stain also is described, both in cultured monolayers and in whole organisms. Staining mechanisms are considered especially for the selective uptake of curcumin into cancer cells. Staining with curcumin labeled nanoparticles is discussed. Toxicity and safety issues associated with the dye also are presented.

Castanea sativa Mill. bark extract exhibits chemopreventive properties triggering extrinsic apoptotic pathway in Jurkat cells

Background

Chemoprevention represents the possibility to prevent, stop or reverse the cancerogenetic process. In this context the interest towards natural extracts and botanical drugs has constantly grown due to their phytochemical content. Castanea sativa Mill. (CSM) extracts showed to exert positive effect in the prevention/counteraction of chronic/degenerative diseases, therefore, we evaluated the potential chemopreventive effect of CSM bark extract.

Methods

Flow cytometry (FCM) analyses of Jurkat cells treated with CSM bark extract (0–500 μg·mL⁻¹) for 24–72 h allowed evaluating its cytotoxicity and ability to induce apoptosis through the intrinsic or extrinsic pathways. Moreover, to evaluate CSM bark extract selectivity towards cancer cells, its cytotoxic and pro-apoptotic effect was also evaluated in human peripheral blood lymphocytes (PBL).

Results

CSM bark extract induced apoptosis in Jurkat cells in a dose- and time- dependent manner activating the extrinsic pathways as evidenced by the increase of activated caspase-8 positive cells. Moreover, IC₅₀ calculated after 24 h treatment resulted 304 and 128 μg·mL⁻¹ in PBL and Jurkat cells respectively.

Conclusions

Our data suggest that CSM bark extract might be considered an interesting potential anti-cancer agent, since it induces apoptosis in cancer cells without appreciable cytotoxic effects on non-transformed cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1756-6) contains supplementary material, which is available to authorized users.

Bridging Type 2 Diabetes and Alzheimer's Disease: Assembling the Puzzle Pieces in the Quest for the Molecules With Therapeutic and Preventive Potential

Type 2 diabetes (T2D) and Alzheimer's disease (AD) are two age-related amyloid diseases that affect millions of people worldwide. Broadly supported by epidemiological data, the higher incidence of AD among type 2 diabetic patients led to the recognition of T2D as a tangible risk factor for the development of AD. Indeed, there is now growing evidence on brain structural and functional abnormalities arising from brain insulin resistance and deficiency, ultimately highlighting the need for new approaches capable of preventing the development of AD in type 2 diabetic patients. This review provides an update on overlapping pathophysiological mechanisms and pathways in T2D and AD, such as amyloidogenic events, oxidative stress, endothelial dysfunction, aberrant enzymatic activity, and even shared genetic background. These events will be presented as puzzle pieces put together, thus establishing potential therapeutic targets for drug discovery and development against T2D and diabetes-induced cognitive decline-a heavyweight contributor to the increasing incidence of dementia in developed countries. Hoping to pave the way in this direction, we will present some of the most promising and well-studied drug leads with potential against both pathologies, including their respective bioactivity reports, mechanisms of action, and structure-activity relationships.

Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids

The innate immune system of patients with Alzheimer's disease and mild cognitive impairment (MCI) is deregulated with highly increased or decreased transcription of inflammatory genes and consistently depressed phagocytosis of amyloid-β_1-42 (Aβ) by monocytes and macrophages. Current immune therapies target single mechanisms in the adaptive immune system but not innate immunity. Here, we summarize recent advances in therapy by ω-3, ω-6, and epoxy fatty acids; specialized proresolving mediators; and vitamin D₃ that have proven immune effects and emerging cognitive effects in patients with MCI. The hypothesis of this approach is that macrophages of normal participants, but not those of patients with Alzheimer's disease and MCI, possess effective phagocytosis for Aβ and protect homeostasis of the brain and, furthermore, that defective MCI macrophages recover phagocytic function via ω-3. Recent studies of fish-derived ω-3 supplementation in patients with MCI have shown polarization of Apoε3/ε3 patients' macrophages to an intermediate M1-M2 phenotype that is optimal for Aβ phagocytosis and the stabilization of cognitive decline. Therefore, accumulating preclinical and preliminary clinical evidence indicates that ω-3 supplementation should be tested in a randomized controlled clinical trial and that the analysis should involve the apolipoprotein E genotype and intervening conditions during trial.-Fiala, M., Kooij, G., Wagner, K., Hammock, B., Pellegrini, M. Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids.

Neuroprotection of Brain Cells by Lipoic Acid Treatment after Cellular Stress

We have previously observed that in vivo lipoic acid (LA) treatment induced a protective effect onto primary cortical neurons after brain injury. In an effort to better understand LA action mechanism in the brain, in the present study, we stressed brain cells in vitro and ex vivo and then analyzed by inmmunocytochemistry and biochemical assays, the changes induced by LA on cell survival and on the concentration of oxidative stress markers, such as glutathione (GSH), oxidized glutathione (GSSG), and malondialdehyde (MDA). The stressors used were lipopolysaccharide (LPS), dopamine, and l-buthionine-S,R-sulfoximine (BSO). Our results showed that LA decreased cell death and increased GSH/GSSG ratio in cells stressed by LPS + dopamine, suggesting that the mechanism underlying LA action is regeneration of GSSG to GSH. When cells were stressed by BSO, LA diminished cell death and decreased GSH/GSSG ratio. In this case, it could be concluded that, due to the low GSH basal levels, GSSG reduction is not possible and therefore it might be thought that cell death prevention might be mediated through other mechanisms. Finally, we induced chemical oxidative damage in brain homogenate. After LA treatment, GSH and GSH/GSSG ratio increased and MDA concentration decreased, demonstrating again that LA was not able to increase de novo GSH synthesis but is able to increase GSSG conversion to GSH.

Curcumin for neuropsychiatric disorders: a review of in vitro, animal and human studies

Turmeric has been used in traditional medicine for centuries to treat a range of ailments. Its primary active constituent curcumin, can influence an array of biological activities. Many of these, such as its anti-inflammatory, antioxidant, neuroprotective, and monoaminergic effects are dysregulated in several neuropsychiatric disorders. In this systematic review, in vitro, animal, and human studies investigating the potential of curcumin as a treatment for neuropsychiatric disorders such as major depressive disorder, post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), bipolar disorder, psychotic disorders, and autism are reviewed, and directions for future research are proposed. It is concluded that curcumin is a promising, natural agent for many of these conditions, however, further research utilising robust, clinical designs are essential. The problem associated with the poor oral bioavailability of standard curcumin also requires consideration. Currently the greatest support for the efficacy of curcumin is for the treatment of major depressive disorder.

Insulin Resistance and Neurodegeneration: Progress Towards the Development of New Therapeutics for Alzheimer's Disease

Alzheimer's disease (AD) should be regarded as a degenerative metabolic disease caused by brain insulin resistance and deficiency, and overlapping with the molecular, biochemical, pathophysiological, and metabolic dysfunctions in diabetes mellitus, non-alcoholic fatty liver disease, and metabolic syndrome. Although most of the diagnostic and therapeutic approaches over the past several decades have focused on amyloid-beta (Aβ42) and aberrantly phosphorylated tau, which could be caused by consequences of brain insulin resistance, the broader array of pathologies including white matter atrophy with loss of myelinated fibrils and leukoaraiosis, non-Aβ42 microvascular disease, dysregulated lipid metabolism, mitochondrial dysfunction, astrocytic gliosis, neuro-inflammation, and loss of synapses vis-à-vis growth of dystrophic neurites, is not readily accounted for by Aβ42 accumulations, but could be explained by dysregulated insulin/IGF-1 signaling with attendant impairments in signal transduction and gene expression. This review covers the diverse range of brain abnormalities in AD and discusses how insulins, incretins, and insulin sensitizers could be utilized to treat at different stages of neurodegeneration.

Emerging ocular biomarkers of Alzheimer disease

Interest in reliable biomarkers of Alzheimer disease, the leading cause of dementia, has been fuelled by challenges in diagnosing the disease and monitoring disease progression as well as the response to therapy. A range of ocular manifestations of Alzheimer disease, including retinal and lens amyloid-beta accumulation, retinal nerve fiber layer loss, and retinal vascular changes, have been proposed as potential biomarkers of the disease. Herein, we examine the evidence regarding the potential value of these ocular biomarkers of Alzheimer disease.

Targeting mTOR to reduce Alzheimer-related cognitive decline: from current hits to future therapies

INTRODUCTION

The mTOR pathway is involved in the regulation of a wide repertoire of cellular functions in the brain and its dysregulation is emerging as a leitmotif in a large number of neurological disorders. In AD, altered mTOR signaling contributes to the inhibition of autophagy deposition of Aβ and tau aggregates and to the alteration of several neuronal metabolic pathways. Areas covered: In this review, we report all the current findings on the use of mTOR inhibitors (rapamycin, rapalogues) in the treatment of AD. These results support the role of mTOR inhibitors as potential therapeutic agents able to reduce AD hallmarks and recover cognitive performances. Expert commentary: Despite mTOR inhibitors appearing to be ideal compounds to counteract AD, further studies are needed in order to gain knowledge on the involvement of aberrant mTOR in AD, and to standardize a valuable therapeutic approach that can be translated to humans.

Curcumin upregulates S100 expression and improves regeneration of the sciatic nerve following its complete amputation in mice

The repair of peripheral nerve injury after complete amputation is difficult, and even with anastomosis, the rapid recovery of nerve function remains challenging. Curcumin, extracted from plants of the genus Curcuma, has been shown to have anti-oxidant and anti-inflammatory properties and to improve sciatic nerve crush injury in rats. Here, we determined whether curcumin had neuroprotective effects following complete peripheral nerve amputation injury. BALB/c mice underwent complete sciatic nerve amputation, followed by an immediate epineurium anastomosis. Mice were intragastrically administered curcumin at doses of 40 (high), 20 (moderate), and 10 mg/kg/d (low) for 1 week. We found that myelin in the mice of the high- and moderate-dose curcumin groups appeared with regular shape, uniform thickness, clear boundary, and little hyperplasia surrounding the myelin. High and moderate doses of curcumin markedly improved both action potential amplitude of the sciatic nerves and the conduction velocity of the corresponding motor neurons, and upregulated mRNA and protein expression of S100, a marker for Schwann cell proliferation, in L_4–6 spinal cord segments. These results suggest that curcumin is effective in promoting the repair of complete sciatic nerve amputation injury and that the underlying mechanism may be associated with upregulation of S100 expression.

Curcumin and Resveratrol in the Management of Cognitive Disorders: What is the Clinical Evidence?

A growing body of in vitro and in vivo evidences shows a possible role of polyphenols in counteracting neurodegeneration: curcumin and resveratrol are attractive substances in this regard. In fact, epidemiological studies highlight a neuroprotective effect of turmeric (rhizome of Curcuma longa L.), the main source of curcumin. Moreover, the consumption of red wine, the main source of resveratrol, has been related to a lower risk of developing dementia. In this review, we analyzed the published clinical trials investigating curcumin and resveratrol in the prevention or treatment of cognitive disorders. The ongoing studies were also described, in order to give an overview of the current search on this topic. The results of published trials (five for curcumin, six for resveratrol) are disappointing and do not allow to draw conclusions about the therapeutic or neuroprotective potential of curcumin and resveratrol. These compounds, being capable of interfering with several processes implicated in the early stages of dementia, could be useful in preventing or in slowing down the pathology. To this aim, an early diagnosis using peripheral biomarkers becomes necessary. Furthermore, the potential preventive activity of curcumin and resveratrol should be evaluated in long-term exposure clinical trials, using preparations with high bioavailability and that are well standardized.

Curcumin ameliorates insulin signalling pathway in brain of Alzheimer's disease transgenic mice

Deficits in glucose, impaired insulin signalling and brain insulin resistance are common in the pathogenesis of Alzheimer's disease (AD); therefore, some scholars even called AD type 3 diabetes mellitus. Curcumin can reduce the amyloid pathology in AD. Moreover, it is a well-known fact that curcumin has anti-oxidant and anti-inflammatory properties. However, whether or not curcumin could regulate the insulin signal transduction pathway in AD remains unclear. In this study, we used APPswe/PS1dE9 double transgenic mice as the AD model to investigate the mechanisms and the effects of curcumin on AD. Immunohistochemical (IHC) staining and a western blot analysis were used to test the major proteins in the insulin signal transduction pathway. After the administration of curcumin for 6 months, the results showed that the expression of an insulin receptor (InR) and insulin receptor substrate (IRS)-1 decreased in the hippocampal CA1 area of the APPswe/PS1dE9 double transgenic mice, while the expression of phosphatidylinositol-3 kinase (PI3K), phosphorylated PI3K (p-PI3K), serine-threonine kinase (AKT) and phosphorylated AKT (p-AKT) increased. Among the curcumin groups, the medium-dose group was the most effective one. Thus, we believe that curcumin may be a potential therapeutic agent that can regulate the critical molecules in brain insulin signalling pathways. Furthermore, curcumin could be adopted as one of the AD treatments to improve a patient's learning and memory ability.

Visual and Ocular Manifestations of Alzheimer's Disease and Their Use as Biomarkers for Diagnosis and Progression

Alzheimer's disease (AD) is the most common form of dementia affecting the growing aging population today, with prevalence expected to rise over the next 35 years. Clinically, patients exhibit a progressive decline in cognition, memory, and social functioning due to deposition of amyloid β (Aβ) protein and intracellular hyperphosphorylated tau protein. These pathological hallmarks of AD are measured either through neuroimaging, cerebrospinal fluid analysis, or diagnosed post-mortem. Importantly, neuropathological progression occurs in the eye as well as the brain, and multiple visual changes have been noted in both human and animal models of AD. The eye offers itself as a transparent medium to cerebral pathology and has thus potentiated the development of ocular biomarkers for AD. The use of non-invasive screening, such as retinal imaging and visual testing, may enable earlier diagnosis in the clinical setting, minimizing invasive and expensive investigations. It also potentially improves disease management and quality of life for AD patients, as an earlier diagnosis allows initiation of medication and treatment. In this review, we explore the evidence surrounding ocular changes in AD and consider the biomarkers currently in development for early diagnosis.