Curcumin induces stress response and hormetically modulates wound healing ability of human skin fibroblasts undergoing ageing in vitro

A lipoprotein complex conjugated mesoporous silica as potent antibiotic adjuvant for synergistic antibacterial therapy of MRSA

Nowadays, the emergence of antibiotic-resistant bacteria has posed a global threat to public health. However, the deployment of alternative antibiotics is lagging far behind the fast evolving antibiotic resistance, which demands effective strategies to restore drug-resistance sensitivity to available antibiotics. Here, a well-known antitumor lipoprotein complex consisted of bovine α-lactalbumin and oleic acid (BAMLET) was electrostatically adsorbed on the surface of mesoporous silica nanomaterials (MSN), forming an antibiotic adjuvant to re-sensitize methicillin-resistant Staphylococcus aureus (MRSA) to aminoglycoside antibiotics. It was found MSN of distinctive particle size may cause conformational changes of bound lipoprotein complex affecting the bactericidal performance of formed BAMLET@MSN conjugates (BMSN). Moreover, MSN was loaded with curcumin to endow obtained BMSN improved bioavailability and antioxidant capacity. The mechanistic studies revealed that antibacterial activities of BMSN originated from bacterial cell membrane disruption and biofilm inhibition, which promoted antibiotic entry and restored antibiotic bactericidal efficacy in the cell. Finally, transcriptomic analysis of MRSA indicated that BMSN interfered with bacterial amino acid metabolism, carbohydrate synthesis, and ATP translocation in bacteria. Therefore, the constructed BMSN/curcumin as potent antibiotic adjuvant provided a manipulable nanoplatform to tackle the antibiotic resistance crisis.

In vitro antiviral activity of eugenol on Singapore grouper iridovirus

The high mortality rate of Singapore grouper iridovirus (SGIV) posing a serious threat to the grouper aquaculture industry and causing significant economic losses. Therefore, finding effective drugs against SGIV is of great significance. Eugenol (C10H12O2) is a phenolic aromatic compound, has been widely studied for its anti-inflammatory, antioxidant and antiviral capacity. In this study, we explored the effect of eugenol on SGIV infection and its possible mechanisms using grouper spleen cells (GS) as an in vitro model. We found that treatment of GS cells with 100 μM eugenol for 4 h exhibited the optimal inhibitory effect on SGIV. Eugenol was able to reduce the expression level of inflammatory factors by inhibiting the activation of MAPK pathway and also inhibited the activity of NF-κB and AP-1 promoter. On the other hand, eugenol attenuated cellular oxidative stress by reducing intracellular ROS and promoted the expression of interferon-related genes. Therefore, we conclude that eugenol inhibits SGIV infection by enhancing cellular immunity through its anti-inflammatory and antioxidant functions.

Advancements in Dermatological Applications of Curcumin: Clinical Efficacy and Mechanistic Insights in the Management of Skin Disorders

Curcumin, derived from Curcuma longa (turmeric), exhibits significant potential in dermatology, addressing conditions like atopic dermatitis, psoriasis, chronic wounds, skin cancer, and infections through its anti-inflammatory, antioxidant, anticancer, and antimicrobial properties. This review synthesizes evidence on curcumin's mechanisms, including modulation of immune responses and promotion of wound healing, showcasing its efficacy in reducing inflammation, cytokine levels, and enhancing skin barrier functions. Studies highlight curcumin's ability to selectively target tumor cells, suggesting a multifaceted approach to cancer therapy with minimal side effects. Despite promising therapeutic benefits, challenges remain in bioavailability, potency, and targeted delivery, underscoring the need for further research to optimize dosages, delivery methods, and assess long-term safety. The integration of curcumin into dermatological practice requires a balanced consideration of evidence-based efficacy and safety. Curcumin's comprehensive utility in dermatology, coupled with the necessity for advanced scientific exploration, emphasizes the importance of combining traditional knowledge with contemporary research to improve patient care in dermatology. This approach could significantly enhance outcomes for individuals with skin-related conditions, marking curcumin as a versatile and promising agent in the field.

Enemies or Allies? Hormetic and Apparent Non-Dose-Dependent Effects of Natural Bioactive Antioxidants in the Treatment of Inflammation

This review aims to analyze the emerging number of studies on biological media that describe the unexpected effects of different natural bioactive antioxidants. Hormetic effects, with a biphasic response depending on the dose, or activities that are apparently non-dose-dependent, have been described for compounds such as resveratrol, curcumin, ferulic acid or linoleic acid, among others. The analysis of the reported studies confirms the incidence of these types of effects, which should be taken into account by researchers, discarding initial interpretations of imprecise methodologies or measurements. The incidence of these types of effects should enhance research into the different mechanisms of action, particularly those studied in the field of basic research, that will help us understand the causes of these unusual behaviors, depending on the dose, such as the inactivation of the signaling pathways of the immune defense system. Antioxidative and anti-inflammatory activities in biological media should be addressed in ways that go beyond a mere statistical approach. In this work, some of the research pathways that may explain the understanding of these activities are revised, paying special attention to the ability of the selected bioactive compounds (curcumin, resveratrol, ferulic acid and linoleic acid) to form metal complexes and the activity of these complexes in biological media.

Biomedical Promise of Sustainable Microwave-Engineered Symmetric Curcumin Derivatives

Curcumin is a polyphenol of the Curcuma longa plant, which can be used for various medicinal purposes, such as inflammation and cancer treatment. In this context, two symmetric curcumin derivatives (D1-(1E,6E)-1,7-bis(4-acetamidophenyl)hepta-1,6-diene-3,5-dione and D2-p,p-dihydroxy di-cinnamoyl methane) were obtained by the microwave-based method and evaluated for their antitumoral effect on human cervix cancer in comparison with toxicity on non-tumoral cells, taking into account that they were predicted to act as apoptosis agonists or anti-inflammatory agents. The HeLa cell line was incubated for 24 and 72 h with a concentration of 50 μg/mL of derivatives that killed almost half of the cells compared to the control. In contrast, these compounds did not alter the viability of MRC-5 non-tumoral lung fibroblasts until 72 h of incubation. The nitric oxide level released by HeLa cells was higher compared to MRC-5 fibroblasts after the incubation with 100 μg/mL. Both derivatives induced the decrease of catalase activity and glutathione levels in cancer cells without targeting the same effect in non-tumoral cells. Furthermore, the Western blot showed an increased protein expression of HSP70 and a decreased expression of HSP60 and MCM2 in cells incubated with D2 compared to control cells. We noticed differences regarding the intensity of cell death between the tested derivatives, suggesting that the modified structure after synthesis can modulate their function, the most prominent effect being observed for sample D2. In conclusion, the outcomes of our in vitro study revealed that these microwave-engineered curcumin derivatives targeted tumor cells, much more specifically, inducing their death.

Molecular bases for the use of functional foods in the management of healthy aging: Berries, curcumin, virgin olive oil and honey; three realities and a promise

As the number of older people has grown in recent decades, the search for new approaches to manage or delay aging is also growing. Among the modifiable factors, diet plays a crucial role in healthy aging and in the prevention of age-related diseases. Thus, the interest in the use of foods, which are rich in bioactive compounds such as functional foods with anti-aging effects is a growing market. This review summarizes the current knowledge about the molecular mechanisms of action of foods considered as functional foods in aging, namely berries, curcumin, and virgin olive oil. Moreover, honey is also analyzed as a food with well-known healthy benefits, but which has not been deeply evaluated from the point of view of aging. The effects of these foods on aging are analyzed from the point of view of molecular mechanisms including oxidative stress, mitochondrial dysfunction, inflammation, genomic stability, telomere attrition, cellular senescence, and deregulated nutrient-sensing. A comprehensive study of the scientific literature shows that the aforementioned foods have demonstrated positive effects on certain aspects of aging, which might justify their use as functional foods in elderly. However, more research is needed, especially in humans, designed to understand in depth the mechanisms of action through which they act.

Natural Phytochemicals as SIRT Activators-Focus on Potential Biochemical Mechanisms

Sirtuins are a family of proteins with enzymatic activity. There are seven mammalian sirtuins (SIRT1-SIRT7) that are found in different cellular compartments. They are a part of crucial cellular pathways and are regulated by many factors, such as chemicals, environmental stress, and phytochemicals. Several in vitro and in vivo studies have presented their involvement in anti-inflammatory, antioxidant, and antiapoptotic processes. Recent findings imply that phytochemicals such as resveratrol, curcumin, quercetin, fisetin, berberine, and kaempferol may regulate the activity of sirtuins. Resveratrol mainly activates SIRT1 and indirectly activates AMPK. Curcumin influences mainly SIRT1 and SIRT3, but its activity is broad, and many pathways in different cells are affected. Quercetin mainly modulates SIRT1, which triggers antioxidant and antiapoptotic responses. Fisetin, through SIRT1 regulation, modifies lipid metabolism and anti-inflammatory processes. Berberine has a wide spectrum of effects and a significant impact on SIRT1 signaling pathways. Finally, kaempferol triggers anti-inflammatory and antioxidant effects through SIRT1 induction. This review aims to summarize recent findings on the properties of phytochemicals in the modulation of sirtuin activity, with a particular focus on biochemical aspects.

In Silico Modeling Study of Curcumin Diffusion and Cellular Growth

Curcumin can enhance cutaneous wound healing by improving fibroblast proliferation. However, its therapeutic properties are dose-dependent: high concentrations produce cytotoxic effects, whereas low concentrations benefit cell proliferation. Similarly, the type of administration and its moderation are key aspects, as an erroneous distribution may result in null or noxious activity to the organism. In silico models for curcumin diffusion work as predictive tools for evaluating curcumin’s cytotoxic effects and establishing therapeutic windows. A 2D fibroblast culture growth model was created based on a model developed by Gérard and Goldbeter. Similarly, a curcumin diffusion model was developed by adjusting experimental release values obtained from Aguilar-Rabiela et al. and fitted to Korsmeyer–Peppas and Peleg’s hyperbolic models. The release of six key curcumin concentrations was achieved. Both models were integrated using Morpheus software, and a scratch-wound assay simulated curcumin’s dose-dependent effects on wound healing. The most beneficial effect was achieved at 0.25 μM, which exhibited the lowest cell-division period, the highest confluence (~60% for both release models, 447 initial cells), and the highest final cell population. The least beneficial effect was found at 20 μM, which inhibited cell division and achieved the lowest confluence (~34.30% for both release models, 447 initial cells). Confluence was shown to decrease as curcumin concentration increased, since higher concentrations of curcumin have inhibitory and cytotoxic effects.

Hormesis: wound healing and fibroblasts

Hormetic dose responses are reported here to occur commonly in the dermal wound healing process, with the particular focus on cell viability, proliferation, migration and collagen deposition of human and murine fibroblasts with in vitro studies. Hormetic responses were induced by a wide range of substances, including endogenous agents, pharmaceutical preparations, plant-derived extracts including many well-known dietary supplements, as well as physical stressor agents such as low-level laser treatments. Detailed mechanistic studies have identified common signaling pathways and their cross-pathway communications that mediate the hormetic dose responses. These findings complement and extend a similar comprehensive assessment concerning the occurrence of hormetic dose responses in keratinocytes. These findings demonstrate the generality of the hormetic dose response for key wound healing endpoints, suggesting that the hormesis concept has a fundamental role in wound healing, with respect to guiding strategies for experimental evaluation as well as therapeutic applications.

Protease-responsive hydrogel, cross-linked with bioactive curcumin-derived carbon dots, encourage faster wound closure

The pharmacological effects of curcumin can be ascribed to its dose-dependent activity. Therapeutic application of curcumin is hindered by its poor solubility and low bioavailability. Carbon dots are gaining attention in biomedical applications in view of their unique photo-physical properties. Some carbon dots derived from bioactive molecules have shown superior activity than the parent compound. With an aim to address the limitations of curcumin, herein we compared the wound healing activity of curcumin-derived carbon dots (CurCD) with curcumin. The improved solubility and stability of CurCD, combined with its superior proliferative, proangiogenic and anti-bacterial activity suggested that CurCD would be more beneficial than curcumin in wound healing. To enable the sustained release of CurCD at the wound site, a protease-responsive hydrogel (GHCD) was prepared with CurCD acting as a cross-linker. A comparative study using a skin excision model revealed that GHCD supported faster wound closure with improved angiogenesis and complete restoration of the epithelium. Apart from the establishment of CurCD as a wound healing agent, the study provides a novel carbon dot based approach for molecules with limitations of solubility and bioavailability.

Regulation of Gene Expression through Food—Curcumin as a Sirtuin Activity Modulator

The sirtuin family comprises NAD⁺-dependent protein lysine deacylases, mammalian sirtuins being either nuclear (SIRT1, SIRT2, SIRT6, and SIRT7), mitochondrial (SIRT3, SIRT4, and SIRT5) or cytosolic enzymes (SIRT2 and SIRT5). They are able to catalyze direct metabolic reactions, thus regulating several physiological functions, such as energy metabolism, stress response, inflammation, cell survival, DNA repair, tissue regeneration, neuronal signaling, and even circadian rhythms. Based on these data, recent research was focused on finding molecules that could regulate sirtuins’ expression and/or activity, natural compounds being among the most promising in the field. Curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) can induce, through SIRT, modulation of cancer cell senescence, improve endothelial cells protection against atherosclerotic factors, enhance muscle regeneration in atrophy models, and act as a pro-longevity factor counteracting the neurotoxicity of amyloid-beta. Although a plethora of protective effects was reported (antioxidant, anti-inflammatory, anticancer, etc.), its therapeutical use is limited due to its bioavailability issues. However, all the reported effects may be explained via the bioactivation theory, which postulates that curcumin’s observed actions are modulated via its metabolites and/or degradation products. The present article is focused on bringing together the literature data correlating the ability of curcumin and its metabolites to modulate SIRT activity and its consequent beneficial effects.

Cisplatin Chemotherapy and Cochlear Damage: Otoprotective and Chemosensitization Properties of Polyphenols

Significance: Cisplatin is an important component of treatment regimens for different cancers. Notwithstanding that therapeutic success often results from partial efficacy or stabilizing the disease, chemotherapy failure is driven by resistance to drug treatment and occurrence of side effects, such as progressive irreversible ototoxicity. Cisplatin's side effects, including ototoxicity, are often dose limiting. Recent Advances: Cisplatin ototoxicity results from several mechanisms, including redox imbalance caused by reactive oxygen species production and lipid peroxidation, activation of inflammation, and p53 and its downstream pathways that culminate in apoptosis. Considerable efforts in research have targeted development of molecular interventions that can be concurrently administered with cisplatin or other chemotherapies to reduce side effect toxicities while preserving or enhancing the antineoplastic effects. Evidence from studies has indicated some polyphenols, such as curcumin, can help to regulate redox signaling and inflammatory effects. Furthermore, polyphenols can exert opposing effects in different types of tissues, that is, normal cells undergoing stressful conditions versus cancer cells. Critical Issues: This review article summarizes evidence of curcumin antioxidant effect against cisplatin-induced ototoxicity that is converted to a pro-oxidant activity in cisplatin-treated cancer cells, thus providing an ideal chemosensitivity combined with otoprotection. Polyphenols can modulate the adaptive responses to stress in the cisplatin-exposed cochlea. These adaptive effects can result from the interaction/cross talk between the cell's defenses, inflammatory molecules, and the key signaling molecules of signal transducers and activators of transcription 3 (STAT-3), nuclear factor κ-B (NF-κB), p53, and nuclear factor erythroid 2-related factor 2 (Nrf-2). Future Directions: We provide molecular evidence for alternative strategies for chemotherapy with cisplatin addressing the otoprotection and chemosensitization properties of polyphenols. Antioxid. Redox Signal. 36, 1229-1245.

Anti-Candidal Activity of the Parasitic Plant Orobanche crenata Forssk

Candida albicans (C. albicans) and Candida glabrata (C. glabrata) are part of the human microbiome. However, they possess numerous virulence factors, which confer them the ability to cause both local and systemic infections. Candidiasis can involve multiple organs, including the eye. In the present study, we investigated the anti-candidal activity and the re-epithelizing effect of Orobanche crenata leaf extract (OCLE). By the microdilution method, we demonstrated an inhibitory effect of OCLE on both C. albicans and C. glabrata growth. By crystal violet and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, we showed the ability of OCLE to inhibit the biofilm formation and the viability of yeast cells, respectively. By germ tube and adhesion assays, we proved the capacity of OCLE to affect the morphological transition of C. albicans and the adhesion of both pathogens to human retinal pigment epithelial cells (ARPE-19), respectively. Besides, by MTT and wound healing assay, we evaluated the cytotoxic and re-epithelizing effects of OCLE on ARPE-19. Finally, the Folin-Ciocalteu and the ultra-performance liquid chromatography-tandem mass spectrometry revealed a high content of phenols and the presence of several bioactive molecules in the extract. Our results highlighted new properties of O. crenata, useful in the control of Candida infections.

Curcumin and rheumatoid arthritis: A systematic review of literature

BACKGROUND

Curcumin is a natural polyphenol and the main compound from the rhizome of Turmeric (Curcuma longa) and other Curcuma species. It has been widely used for different medical purposes, such as improvement of pain and inflammatory conditions in various diseases.

PURPOSE

This systematic review was aimed to assess all studies regarding the efficacy of the pure form of curcumin (unformulated curcumin) on rheumatoid arthritis (RA).

METHODS

The comprehensive search of the literature was done until September 2020 on the MEDLINE, Embase, Scopus and Web of Knowledge databases. Out of 2079 initial records, 51 articles (13 in vitro and 37 animal and one human) were met our inclusion criteria.

RESULTS

Most studies have shown the curative effects of curcumin on clinical and inflammatory parameters of RA and reported different mechanisms; inhibition of mitogen-activated protein kinase family, extracellular signal-regulated protein kinase, activator protein-1 and nuclear factor kappa B are the main mechanisms associated with the anti-inflammatory function of curcumin in RA. The results of the only human study showed that curcumin significantly improved morning stiffness, walking time and joint swelling.

CONCLUSION

In conclusion, curcumin seems to be useful, and it is recommended that more human studies be performed to approve the cellular and animal results and determine the effective and optimal doses of curcumin on RA patients.

In silico investigations on curcuminoids from Curcuma longa as positive regulators of the Wnt/β-catenin signaling pathway in wound healing

Background

Curcuma longa (Turmeric) is a traditionally used herb in wound healing. The efficacy of fresh turmeric paste to heal wounds has already been investigated in multiple ethnobotanical studies. Wnt/β-catenin signaling pathway plays a significant role in wound healing and injury repair processes which has been evident in different in vitro studies. This study aims to analyze the potentiality of curcuminoids (curcumin I, curcumin II and curcumin III) from Curcuma longa to bind and enhance the activity of two intracellular signaling proteins- casein kinase-1 (CK1) and glycogen synthase kinase-3β (GSK3B) involved in Wnt/β-catenin signaling pathway. This study is largely based on a computer-based molecular docking program which mimics the in vivo condition and works on a specific algorithm to interpret the binding affinity and poses of a ligand molecule to a receptor. Subsequently, drug likeness property, ADME/Toxicity profile, pharmacological activity, and site of metabolism of the curcuminoids were also analyzed.

Results

Curcumin I showed better affinity of binding with CK1 (− 10.31 Kcal/mol binding energy) and curcumin II showed better binding affinity (− 7.55 Kcal/mol binding energy) for GSK3B. All of the ligand molecules showed quite similar pharmacological properties.

Conclusion

Curcumin has anti-oxidant, anti-carcinogenic, anti-mutagenic, anti-coagulant, and anti-infective properties. Curcumin has also anti-inflammatory and wound healing properties. It hastens wound healing by acting on different stages of the natural wound healing process. In this study, three curcumins from Curcuma longa were utilized in this experiment in a search for a drug to be used in wound healing and injury repair processes. Hopefully, this study will raise research interest among researchers.

Exploitation of traditional healing properties, using the nanotechnology's advantages: The case of curcumin

Curcumin (CUR) has a long history of use as an antimicrobial, anti-inflammatory and wound healing agent, for the treatment of various skin conditions. Encapsulation in nanocarriers may overcome the administration limitations of CUR, such as lipophilicity and photodegradation. Lipid nanocarriers with different matrix fluidity (Solid Lipid Nanoparticles; SLN, Nanostructured Lipid Carriers; NLC, and Nanoemulsion; NE) were prepared for the topical delivery of curcumin (CUR). The occlusive properties and film forming capacity, as well as the release profile of incorporated CUR, its protection against photodegradation and wound healing were studied in vitro, using empty nanocarriers or free CUR as control. The results suggest that incorporation of CUR in nanocarriers offers a significant protection against photodegradation that is not influenced by the matrix fluidity. However, this characteristic regulates properties such as the occlusion, the release rate and wound healing ability of CUR. Nanoparticles of low fluidity provided better surface occlusion, film forming capacity and retention of the incorporated CUR. All nanocarriers but especially NLC, achieved faster wound healing at lower dose of incorporated CUR. In conclusion, nanotechnology may enhance the action of CUR against skin conditions. Important characteristics of the nanocarrier such as matrix fluidity should be taken into consideration in the design of CUR nanosystems of optimal efficiency.

Hormesis Mediates Acquired Resilience: Using Plant-Derived Chemicals to Enhance Health

This review provides an assessment of hormesis, a highly conserved evolutionary dose-response adaptive strategy that leads to the development of acquired resilience within well-defined temporal windows. The hormetic-based acquired resilience has a central role in affecting healthy aging, slowing the onset and progression of numerous neurodegenerative and other age-related diseases, and reducing risks and damage due to heart attacks, stroke, and other serious conditions of public health and medical importance. The review provides the historical foundations of hormesis, its dose-response features, its capacity for generalization across biological models and endpoints measured, and its mechanistic foundations. The review also provides a focus on the adaptive features of hormesis, i.e., its capacity to upregulate acquired resilience and how this can be mediated by numerous plant-derived extracts, such as curcumin, ginseng, Ginkgo biloba, resveratrol, and green tea, that induce a broad spectrum of chemopreventive effects via hormesis.

Comparison of the protective effect of cytosolic and mitochondrial Peroxiredoxin 5 against glutamate-induced neuronal cell death

Objectives: Although glutamate is an essential factor in the neuronal system, excess glutamate can produce excitotoxicity. We previously reported that Peroxiredoxin 5 (Prx5) protects neuronal cells from glutamate toxicity via its antioxidant effects. However, it is unclear whether cytosolic or mitochondrial Prx5 provides greater neuroprotection. Here, we investigated differences in the neuroprotective effects of cytosolic and mitochondrial Prx5.

Methods: We analyzed patterns of cytosolic and mitochondrial H₂O₂ generation in glutamate toxicity using HyPer protein. And then, we confirmed the change of intracellular ROS level and apoptosis with respective methods. The mitochondrial dynamics was assessed with confocal microscope imaging and western blotting.

Results: We found that the level of mitochondrial H₂O₂ greatly increased compared to cytosolic H₂O₂ and it affected cytosolic H₂O₂ generation after glutamate treatment. In addition, we confirmed that mitochondrial Prx5 provides more effective neuroprotection than cytosolic Prx5.

Discussion: Overall, our study reveals the mechanisms of cytosolic and mitochondrial ROS in glutamate toxicity. Our findings suggest that mitochondrial ROS and Prx5 are attractive therapeutic targets and that controlling these factors be useful for the prevention of neurodegenerative diseases.

Tracing skin aging process: a mini- review of in vitro approaches

Skin is a rather complex, yet useful organ of our body. Besides, skin aging is a complicated process that gains a growing interest as mediates many molecular processes in our body. Thus, an efficient skin model is important to understand skin aging function as well as to develop an effective innovative product for skin aging treatment. In this mini review, we present in vitro methods for assessments of skin aging in an attempt to pinpoint basic molecular mechanisms behind this process achieving both a better understanding of aging function and an effective  evaluation of potential products or ingredients that counteract aging. Specifically, this study presents in vitro assays such as 2D or 3D skin models, to evaluate skin aging-related processes such as skin moisturization, photoaging, wound healing, menopause, and skin microbiome as novel efforts in the designing of efficacy assessments in the development of skincare products.

Curcumin protects thymus against D-galactose-induced senescence in mice

Senescence-related decline of thymus affects immune function in the elderly population and contributes to the prevalence of many relevant diseases like cancer, autoimmune diseases, and other chronic diseases. In this study, we investigated the therapeutic effects of curcumin, an agent that could counter aging, and explored its optimal intake and the alteration of autoimmune regulator (Aire) after curcumin treatment in the D-galactose (D-gal)-induced accelerated aging mice. ICR mice were intraperitoneally injected with D-gal for 8 weeks to establish the accelerated aging model and given curcumin with 50, 100, and 200 mg/kg body weight per day by gavage, respectively, for 6 weeks. It indicated that the D-gal-treated mice developed structural changes in the thymi compared with the control group without D-gal and curcumin treatment. As the supplements of curcumin, it resulted in a restoration of the normal thymic anatomy with an increase of proliferating cells and a reduction of apoptotic cells in the thymi of the D-gal-induced aging model mice. Curcumin administration could also expand the expression level of Aire from mRNA level and protein level. The current study demonstrated that curcumin could ameliorate senescence-related thymus involution via upregulating Aire expression, suggesting that curcumin can rejuvenate senescence-associated alterations of thymus induced by D-gal accumulation.

Antifibrotic effects of sulforaphane treatment on gingival elasticity reduces orthodontic relapse after rotational tooth movement in beagle dogs

Objective

Increased gingival elasticity has been implicated as the cause of relapse following orthodontic rotational tooth movement and approaches to reduce relapse are limited. This study aimed to investigate the effects of sulforaphane (SFN), an inhibitor of osteoclastogenesis, on gene expression in gingival fibroblasts and relapse after rotational tooth movement in beagle dogs.

Methods

The lower lateral incisors of five beagle dogs were rotated. SFN or dimethylsulfoxide (DMSO) were injected into the supra-alveolar gingiva of the experimental and control group, respectively, and the effect of SFN on relapse tendency was evaluated. Changes in mRNA expression of extracellular matrix components associated with gingival elasticity in beagles were investigated by real-time polymerase chain reaction. Morphology and arrangement of collagen fibers were observed on Masson's trichrome staining of buccal gingival tissues of experimental and control teeth.

Results

SFN reduced the amount and percentage of relapse of orthodontic rotation. It also decreased the gene expression of lysyl oxidase and increased the gene expression of matrix metalloproteinase (MMP) 1 and MMP 12, compared with DMSO control subjects. Histologically, collagen fiber bundles were arranged irregularly and were not well connected in the SFN-treated group, whereas the fibers extended in parallel and perpendicular directions toward the gingiva and alveolar bone in a more regular and well-ordered arrangement in the DMSO-treated group.

Conclusions

Our findings demonstrated that SFN treatment may be a promising pharmacologic approach to prevent orthodontic rotational relapse caused by increased gingival elasticity of rotated teeth in beagle dogs.

Protective effects of natural compounds against oxidative stress in ischemic diseases and cancers via activating the Nrf2 signaling pathway: A mini review

Oxidative stress, an imbalance between reactive oxygen species and antioxidants, has been seen in the pathological states of many disorders such as ischemic diseases and cancers. Many natural compounds (NCs) have long been recognized to ameliorate oxidative stress due to their inherent antioxidant activities. The modulation of oxidative stress by NCs via activating the Nrf2 signaling pathway is summarized in the review. Three NCs, ursolic acid, betulinic acid, and curcumin, and the mechanisms of their cytoprotective effects are investigated in myocardial ischemia, cerebral ischemia, skin cancer, and prostate cancer. To promote the therapeutic performance of NCs with poor water solubility, the formulation approach, such as the nano drug delivery system, is elaborated as well in this review.

Impact of curcumin on replicative and chronological aging in the Saccharomyces cerevisiae yeast

Curcumin is a biologically active compound of vegetable origin which has a hormetic effect. Pro-health and anti-aging properties of curcumin have been known for years. The main benefit of curcumin is thought to be its anti-oxidative action. Despite vast amount of data confirming age-delaying activity of curcumin in various groups of organisms, so far little has been discovered about curcumin's impact on cell aging in the experimental model of the Saccharomyces cerevisiae budding yeast. We have been able to demonstrate that curcumin significantly increases oxidative stress and accelerates replicative and chronological aging of yeast cells devoid of anti-oxidative protection (with SOD1 and SOD2 gene deletion) and deprived of DNA repair mechanisms (RAD52). Interestingly, curcumin delays aging, probably through hormesis, of the wild-type strain BY4741.

NRF2 as a Therapeutic Target in Neurodegenerative Diseases

Increased reactive oxygen species production and oxidative stress have been implicated in the pathogenesis of numerous neurodegenerative conditions including among others Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, Friedrich’s ataxia, multiple sclerosis, and stroke. The endogenous antioxidant response pathway protects cells from oxidative stress by increasing the expression of cytoprotective enzymes and is regulated by the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2). In addition to regulating the expression of antioxidant genes, NRF2 has also been shown to exert anti-inflammatory effects and modulate both mitochondrial function and biogenesis. This is because mitochondrial dysfunction and neuroinflammation are features of many neurodegenerative diseases as well NRF2 has emerged as a promising therapeutic target. Here, we review evidence for a beneficial role of NRF2 in neurodegenerative conditions and the potential of specific NRF2 activators as therapeutic agents.

Biphasic Dose-Response and Hormetic Effects of Stress Hormone Hydrocortisone on Telomerase-Immortalized Human Bone Marrow Stem Cells In Vitro

Although high levels of stress hormones are associated with well-known negative health outcomes, their low levels can have health-promoting effects by virtue of the phenomenon of mild stress-induced hormesis. We have studied the effects of a wide range (between 100 nmol/L and 150 μmol/L) of hydrocortisone (HC) on human bone marrow stem cells in vitro. Telomerase-immortalized human mesenchymal stem cells (hTERT-MSCs) were exposed to various doses of HC for different durations (1-6 days) and analyzed for survival and metabolic activity by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, for cell migratory ability by a wound-healing assay and for osteoblastic and adipogenic differentiation abilities in vitro. Our findings indicate that hTERT-MSCs exposed to HC resulted in a biphasic hormetic dose–response in some measures but not all. Although the mitochondrial and metabolic MTT activity assay clearly showed low-level stimulatory (between 0.1 and 1 µmol/L) and high-level inhibitory effects (from about 10 µmol/L onward), the cytostatic and differentiation-inducing effects were mostly linear at concentrations between 1 and 100 µmol/L. Further long-term studies will elucidate whether chronic or intermittent exposure of human cells to stress hormones has physiologically beneficial hormetic effects.

Targeting normal and cancer senescent cells as a strategy of senotherapy

Senotherapy is an antiageing strategy. It refers to selective killing of senescent cells by senolytic agents, strengthening the activity of immune cells that eliminate senescent cells or alleviating the secretory phenotype (SASP) of senescent cells. As senescent cells accumulate with age and are considered to be at the root of age-related disorders, senotherapy seems to be very promising in improving healthspan. Genetic approaches, which allowed to selectively induce death of senescent cells in transgenic mice, provided proof-of-concept evidence that elimination of senescent cells can be a therapeutic approach for treating many age-related diseases. Translating these results into humans is based on searching for synthetic and natural compounds, which are able to exert such beneficial effects. The major challenge in the field is to show efficacy, safety and tolerability of senotherapy in humans. The question is how these therapeutics can influence senescence of non-dividing post-mitotic cells. Another issue concerns senescence of cancer cells induced during therapy as there is a risk of resumption of senescent cell division that could terminate in cancer renewal. Thus, development of an effective senotherapeutic strategy is also an urgent issue in cancer treatment. Different aspects, both beneficial and potentially detrimental, will be discussed in this review.

Genetic background, epigenetic factors and dietary interventions which influence human longevity

Longevity is mainly conditioned by genetic, epigenetic and environmental factors. Different genetic modifications seem to be positively associated to longevity, including SNPs in SIRT1, APOE, FOXO3A, ACE, ATM, NOS1 and NOS2 gene. Epigenetic changes as DNA hyper- and hypo-methylation influence significantly human longevity by activating/deactivating different genes involved in physiological mechanisms. Several studies have confirmed that centenarians have a lower DNA methylation content compared to young subjects, which showed more homogeneously methylated DNA region. Also the up-regulation of miR-21 seems to be more associated with longevity in different populations of long-lived subjects, suggesting its role as potential epigenetic biomarkers. A non-pharmacological treatment that seems to contrast age-related diseases and promote longevity is represented by dietary intervention. It has been evaluated the effects of dietary restriction of both single nutrients or total calories to extend lifespan. However, in daily practice it is very difficult to guarantee adherence/compliance of the subjects to dietary restriction and at the same time avoid dangerous nutritional deficiencies. As consequence, the attention has focused on a variety of substances both drugs and natural compounds able to mime the beneficial effects of caloric restriction, including resveratrol, quercetin, rapamycin, metformin and 2-deoxy-D-glucose.

Toxin-induced hormesis may restrain aging

Mild environmental stress might have beneficial effects in aging by activating maintenance and repair processes in cells and organs. These beneficial stress effects fit to the concept of hormesis. Prominent stressors acting in a hormetic way are physical exercises, fasting, cold and heat. This review will introduce some toxins, which have been found to induce hormetic responses in animal models of aging research. To highlight the molecular signature of these hormetic effects we will depict signaling pathways affected by low doses of toxins on cellular and organismic level. As prominent examples for signaling pathways involved in both aging processes as well as toxin responses, PI3K/Akt/mTOR- and AMPK-signal transduction will be described in more detail. Due to the striking overlap of signaling pathways mediating toxin induced responses and aging processes we propose considering the ability of low doses of toxins to slow down the rate of aging.

The Role of Curcumin in the Modulation of Ageing

It is believed that postponing ageing is more effective and less expensive than the treatment of particular age-related diseases. Compounds which could delay symptoms of ageing, especially natural products present in a daily diet, are intensively studied. One of them is curcumin. It causes the elongation of the lifespan of model organisms, alleviates ageing symptoms and postpones the progression of age-related diseases in which cellular senescence is directly involved. It has been demonstrated that the elimination of senescent cells significantly improves the quality of life of mice. There is a continuous search for compounds, named senolytic drugs, that selectively eliminate senescent cells from organisms. In this paper, we endeavor to review the current knowledge about the anti-ageing role of curcumin and discuss its senolytic potential.

Phytochemicals Rosmarinic Acid, Ampelopsin, and Amorfrutin-A Can Modulate Age-Related Phenotype of Serially Passaged Human Skin Fibroblasts in vitro

One of the aims of the EU-funded Research and Innovation Action (RIA), titled “Ageing with Elegans” (AwE) is to enhance better understanding of the factors causing health and disease in aging and develop evidence-based preventive, diagnostic, therapeutic, and other strategies. The work package-5 of this project is focused on testing the effects of phytochemicals of natural and synthetic origin on aging, longevity, and health of human cells in vitro, after the initial screening using the animal model systems of nematodes and rats and mice. Accordingly, the first series of three compounds, rosmarinic acid (ROSM), ampelopsin (AMPEL), and amorfrutin-A (AMOR), were selected to test for their short-term and long-term effects on human skin fibroblasts undergoing aging and senescence in vitro. The lifelong modulatory effects of these compounds were tested individually at two doses (0.5 and 1.0 μM), selected after a short-term dose response check of a 20,000-fold range (0.01–200 μM). The results show that these compounds do have some beneficial effects in terms of supporting the long-term lifelong growth and enhanced stress tolerance of serially passaged cells. These effects seem to be achieved by reducing the extent of loss of telomeres, of 5-methyl-cytosine (5-mC) and of 5-hydroxymethyl-cytosine (5-hmC), by reducing the accumulation of oxidative DNA damage product 8-OHdG. There is also some indication that these compounds induce at least one of the stress responses in terms of the increased synthesis of heat shock protein Hsp70. Thus, these phytochemicals may be potential hormetins, which bring about their health beneficial effects by the phenomenon of mild stress-induced hormesis.

Hormetic effects of curcumin: What is the evidence?

Curcumin (diferuloylmethane), a component of the yellow powder prepared from the roots of Curcuma longa or Zingiberaceae (known as turmeric) is not only widely used to color and flavor food but also used as a pharmaceutical agent. Curcumin demonstrates anti-inflammatory, anticarcinogenic, antiaging, and antioxidant activity, as well as efficacy in wound healing. Notably, curcumin is a hormetic agent (hormetin), as it is stimulatory at low doses and inhibitory at high doses. Hormesis by curcumin could be also a particular function at low doses (i.e., antioxidant behavior) and another function at high dose (i.e., induction of autophagy and cell death). Recent findings suggest that curcumin exhibits biphasic dose-responses on cells, with low doses having stronger effects than high doses; examples being activation of the mitogen-activated protein kinase signaling pathway or antioxidant activity. This indicates that many effects induced by curcumin are dependent on dose and some effects might be greater at lower doses, indicative of a hormetic response. Despite the consistent occurrence of hormetic responses of curcumin in a wide range of biomedical models, epidemiological and clinical trials are needed to assess the nature of curcumin's dose-response in humans. Fortunately, more than one hundred clinical trials with curcumin and curcumin derivatives are ongoing. In this review, we provide the first comprehensive analysis supportive of the hormetic behavior of curcumin and curcumin derivatives.

Wound Healing Properties of Selected Natural Products

Wound healing is a complex process of recovering the forms and functions of injured tissues. The process is tightly regulated by multiple growth factors and cytokines released at the wound site. Any alterations that disrupt the healing processes would worsen the tissue damage and prolong repair process. Various conditions may contribute to impaired wound healing, including infections, underlying diseases and medications. Numerous studies on the potential of natural products with anti-inflammatory, antioxidant, antibacterial and pro-collagen synthesis properties as wound healing agents have been performed. Their medicinal properties can be contributed by the content of bioactive phytochemical constituents such as alkaloids, essential oils, flavonoids, tannins, saponins, and phenolic compounds in the natural products. This review highlights the in vitro, in vivo and clinical studies on wound healing promotions by the selected natural products and the mechanisms involved.

Non-specific protein modifications may be novel mechanism underlying bioactive phytochemicals

In a variety of experimental models, dietary phytochemicals have been demonstrated to exhibit pronounced and versatile bioactivities. Importantly, the possibility of such phytochemicals for human application has been supported in part by epidemiological surveys, which have demonstrated that frequent ingestion of vegetables and fruits containing abundant phytochemicals lowers the risk of onset of various diseases. However, the action mechanisms underlying those dietary phytochemical activities remain to be fully elucidated. For example, even though the anti-oxidant effects of natural polyphenols have long received widespread attention from food scientists, their roles in and contribution to those bioactivities remain controversial because of their poor bioavailability, resulting in extremely low concentrations in the bloodstream. Meanwhile, another important question is why phytochemicals have beneficial effects for animals, including humans, since they are biosynthesized by plants as compounds necessary for adaptation to environmental stress. In regard to that fundamental question, we recently reported novel and unique mechanisms of action of zerumbone, a sesquiterpene with anti-inflammatory and chemopreventive properties. This agent was found to partially exhibit bioactivity through its non-specific interactions with cellular proteins. More strikingly, a non-specific protein binding action of zerumbone was revealed to partially contribute to its anti-inflammatory functions via activation of heat shock factor 1. The present review article highlights and introduces our recent findings regarding the proteo-stress-mediated mechanisms of this phytochemical, along with the concept of hormesis.

Curcumin elevates sirtuin level but does not postpone in vitro senescence of human cells building the vasculature

It is believed that curcumin, a component of the turmeric that belongs to hormetins, possesses anti-aging propensity. This property of curcumin can be partially explained by its influence on the level of sirtuins. Previously, we have shown that relatively high (2.5-10 µM) doses of curcumin induce senescence of cancer cells and cells building the vasculature. In the present study we examined whether curcumin at low doses (0.1 and 1 µM) is able to delay cell senescence and upregulate the level of sirtuins in human cells building the vasculature, namely vascular smooth muscle (VSMC) and endothelial (EC) cells. To this end we used cells senescing in a replicative and premature manner. We showed that low doses of curcumin in case of VSMC neither postponed the replicative senescence nor protected from premature senescence induced by doxorubicin. Moreover, curcumin slightly accelerated replicative senescence of EC. Despite some fluctuations, a clear increasing tendency in the level of sirtuins was observed in curcumin-treated young, senescing or already senescent cells. Sirtuin activation could be caused by the activation of AMPK resulting from superoxide elevation and ATP reduction. Our results show that curcumin at low doses can increase the level of sirtuins without delaying senescence of VSMC.

Chronic exposure to rapamycin and episodic serum starvation modulate ageing of human fibroblasts in vitro

Mild stress-induced activation of stress response (SR) pathways, such as autophagy, heat shock response, oxidative SR, DNA damage response, and inflammatory response, can be potentially health beneficial. Using the model system of cellular ageing and replicative senescence in vitro, we have studied the ageing modulatory effects of the two conditions, rapamycin and serum starvation. Chronic exposure to 0.1, 1 and 10 nM rapamycin positively modulated the survival, growth, morphology, telomere length, DNA methylation levels, 8-oxo-dG level in DNA, N⁶-methyl-adenosine level in RNA, and ethanol stress tolerance of serially passaged normal human skin fibroblasts. Furthermore, episodic (once a week) serum starvation of human skin fibroblasts extended their replicative lifespan by about 22%, along with the maintenance of early passage youthful morphology even in late passage cultures. Although the results of this study may be considered preliminary, it can be inferred that intermittent and episodic induction of SR, rather than chronic up-regulation of SR, is more effective and applicable in the practice of hormesis for healthy ageing and longevity.

Berberine protects against 6-OHDA-induced neurotoxicity in PC12 cells and zebrafish through hormetic mechanisms involving PI3K/AKT/Bcl-2 and Nrf2/HO-1 pathways

Berberine (BBR) is a renowned natural compound that exhibits potent neuroprotective activities. However, the cellular and molecular mechanisms are still unclear. Hormesis is an adaptive mechanism generally activated by mild oxidative stress to protect the cells from further damage. Many phytochemicals have been shown to induce hormesis. This study aims to investigate whether the neuroprotective activity of BBR is mediated by hormesis and the related signaling pathways in 6-OHDA-induced PC12 cells and zebrafish neurotoxic models. Our results demonstrated that BBR induced a typical hormetic response in PC12 cells, i.e. low dose BBR significantly increased the cell viability, while high dose BBR inhibited the cell viability. Moreover, low dose BBR protected the PC12 cells from 6-OHDA-induced cytotoxicity and apoptosis, whereas relatively high dose BBR did not show neuroprotective activity. The hormetic and neuroprotective effects of BBR were confirmed to be mediated by up-regulated PI3K/AKT/Bcl-2 cell survival and Nrf2/HO-1 antioxidative signaling pathways. In addition, low dose BBR markedly mitigated the 6-OHDA-induced dopaminergic neuron loss and behavior movement deficiency in zebrafish, while high dose BBR only slightly exhibited neuroprotective activities. These results strongly suggested that the neuroprotection of BBR were attributable to the hormetic mechanisms via activating cell survival and antioxidative signaling pathways.

Sirtuins, a promising target in slowing down the ageing process

Ageing is a plastic process and can be successfully modulated by some biomedical approaches or pharmaceutics. In this manner it is possible to delay or even prevent some age-related pathologies. There are some defined interventions, which give promising results in animal models or even in human studies, resulting in lifespan elongation or healthspan improvement. One of the most promising targets for anti-ageing approaches are proteins belonging to the sirtuin family. Sirtuins were originally discovered as transcription repressors in yeast, however, nowadays they are known to occur in bacteria and eukaryotes (including mammals). In humans the family consists of seven members (SIRT1-7) that possess either mono-ADP ribosyltransferase or deacetylase activity. It is believed that sirtuins play key role during cell response to a variety of stresses, such as oxidative or genotoxic stress and are crucial for cell metabolism. Although some data put in question direct involvement of sirtuins in extending human lifespan, it was documented that proper lifestyle including physical activity and diet can influence healthspan via increasing the level of sirtuins. The search for an activator of sirtuins is one of the most extensive and robust topic of research. Some hopes are put on natural compounds, including curcumin. In this review we summarize the involvement and usefulness of sirtuins in anti-ageing interventions and discuss the potential role of curcumin in sirtuins regulation.

Curcumin and Viscum album Extract Decrease Proliferation and Cell Viability of Soft-Tissue Sarcoma Cells: An In Vitro Analysis of Eight Cell Lines Using Real-Time Monitoring and Colorimetric Assays

BACKGROUND

The cytostatic effects of the polyphenol curcumin and Viscum album extract (VAE) were assessed in soft-tissue sarcoma (STS) cells.

METHODS

Eight human STS cell lines were used: fibrosarcoma (HT1080), liposarcoma (SW872, T778, MLS-402), synovial sarcoma (SW982, SYO1, 1273), and malignant fibrous histiocytoma (U2197). Primary human fibroblasts served as control cells. Cell proliferation, viability, and cell index (CI) were analyzed by BrdU assay, MTT assay, and real-time cell analysis (RTCA).

RESULTS

As indicated by BrdU and MTT, curcumin significantly decreased the cell proliferation of five cell lines (HT1080, SW872, SYO1, 1273, and U2197) and the viability of two cell lines (SW872 and SW982). VAE led to significant decreases of proliferation in eight cell lines (HT1080, SW872, T778, MLS-402, SW982, SYO1, 1293, and U2197) and reduced viability in seven STS lines (HT1080, SW872, T778, MLS-402, SW982, SYO1, and 1273). As indicated by RTCA for 160 h, curcumin decreased the CI of all synovial sarcoma cell lines as well as T778 and HT1080. VAE diminished the CI in most of the synovial sarcoma (SW982, SYO1) and liposarcoma (SW872, T778) cell lines as well as HT1080. Primary fibroblasts were not affected adversely by the two compounds in RTCA.

CONCLUSION

Curcumin and VAE can inhibit the proliferation and viability of STS cells.

The nephroprotection exerted by curcumin in maleate-induced renal damage is associated with decreased mitochondrial fission and autophagy

We have previously reported that the antioxidant curcumin exerts nephroprotection in maleate-induced renal damage, a model associated with oxidative stress. However, the mechanisms involved in curcumin protective effect were not explored, to assess this issue, curcumin was administered daily by gavage (150 mg/kg) five days before a single maleate (400 mg/kg)-injection. Curcumin prevented maleate-induced proteinuria, increased heat shock protein of 72 KDa (Hsp72) expression, and decreased plasma glutathione peroxidase activity. Maleate-induced oxidative stress by increasing the nicotinamide-adenine dinucleotide phosphate oxidase 4 (NOX4) and mitochondrial complex I-dependent superoxide anion (O₂ •^- ) production, formation of malondialdehyde (MDA)- and 3-nitrotyrosine (3-NT)-protein adducts and protein carbonylation and decreased GSH/GSSG ratio. Curcumin treatment ameliorated all the above-described changes. The maleate-induced epithelial damage, evaluated by claudin-2 and occludin expressions, was ameliorated by curcumin. It was found that maleate-induced oxidative stress promoted mitochondrial fission, evaluated by dynamin-related protein (Drp) 1 and fission (Fis) 1 expressions and by electron-microscopy, and autophagy, evaluated by phospho-threonine 389 from p70 ribosomal protein S6 kinase (p-Thr 389 p70S6K), beclin 1, microtubule-associated protein 1A/1B-light chain 3 phosphatidylethanolamine conjugate (LC3-II), autophagy-related gene 5 and 12 (Atg5-Atg12) complex, p62, and lysosomal-associated membrane protein (LAMP)-2 expressions in isolated proximal tubules and by electron-microscopy and LC-3 immunolabelling. Curcumin treatment ameliorated these changes. Moreover, curcumin alone induced autophagy in proximal tubules. These data suggest that the nephroprotective effect exerted by curcumin in maleate-induced renal damage is associated with decreased mitochondrial fission and autophagy. © 2016 BioFactors, 42(6):686-702, 2016.

Use of Polyphenolic Compounds in Dermatologic Oncology

Polyphenols are a widely used class of compounds in dermatology. While phenol itself, the most basic member of the phenol family, is chemically synthesized, most polyphenolic compounds are found in plants and form part of their defense mechanism against decomposition. Polyphenolic compounds, which include phenolic acids, flavonoids, stilbenes, and lignans, play an integral role in preventing the attack on plants by bacteria and fungi, as well as serving as cross-links in plant polymers. There is also mounting evidence that polyphenolic compounds play an important role in human health as well. One of the most important benefits, which puts them in the spotlight of current studies, is their antitumor profile. Some of these polyphenolic compounds have already presented promising results in either in vitro or in vivo studies for non-melanoma skin cancer and melanoma. These compounds act on several biomolecular pathways including cell division cycle arrest, autophagy, and apoptosis. Indeed, such natural compounds may be of potential for both preventive and therapeutic fields of cancer. This review evaluates the existing scientific literature in order to provide support for new research opportunities using polyphenolic compounds in oncodermatology.

Low doses of nanodiamonds and silica nanoparticles have beneficial hormetic effects in normal human skin fibroblasts in culture

Nanodiamonds (ND) and silica nanoparticles (SiO2-NP) have been much investigated for their toxicity at high doses, little is known about their biological activity at low concentrations. Here we report the biphasic dose response of ND and SiO2-NP in modulating normal human facial skin fibroblasts (FSF1) in culture. ND and SiO2-NP at low concentration (up to 0.5 μg/ml) had beneficial effects on FSF1 in terms of increasing their proliferation and metabolic activity. Exposure of FSF1 cells to low levels of NP enhanced their wound healing ability in vitro and slowed down aging during serial passaging as measured by maintenance of youthful morphology, reduction in the rate of loss of telomeres, and the over all proliferative characteristics. Furthermore, NP treatment induced the activation of Nrf2- and FOXO3A-mediated cellular stress responses, including an increased expression of heme oxygenease (HO-1), sirtuin (SIRT1), and DNA methyltransferase II (DNMT2). These results imply that ND and SiO2-NP at low doses are potential hormetins, which exert mild stress-induced beneficial hormetic effects through improved survival, longevity, maintenance, repair and function of human cells.

Lung extracellular matrix and redox regulation

Pulmonary fibrosis affects millions worldwide and, even though there has been a significant investment in understanding the processes involved in wound healing and maladaptive repair, a complete understanding of the mechanisms responsible for lung fibrogenesis eludes us, and interventions capable of reversing or halting disease progression are not available. Pulmonary fibrosis is characterized by the excessive expression and uncontrolled deposition of extracellular matrix (ECM) proteins resulting in erosion of the tissue structure. Initially considered an 'end-stage' process elicited after injury, these events are now considered pathogenic and are believed to contribute to the course of the disease. By interacting with integrins capable of signal transduction and by influencing tissue mechanics, ECM proteins modulate processes ranging from cell adhesion and migration to differentiation and growth factor expression. In doing so, ECM proteins help orchestrate complex developmental processes and maintain tissue homeostasis. However, poorly controlled deposition of ECM proteins promotes inflammation, fibroproliferation, and aberrant differentiation of cells, and has been implicated in the pathogenesis of pulmonary fibrosis, atherosclerosis and cancer. Considering their vital functions, ECM proteins are the target of investigation, and oxidation-reduction (redox) reactions have emerged as important regulators of the ECM. Oxidative stress invariably accompanies lung disease and promotes ECM expression directly or through the overproduction of pro-fibrotic growth factors, while affecting integrin binding and activation. In vitro and in vivo investigations point to redox reactions as targets for intervention in pulmonary fibrosis and related disorders, but studies in humans have been disappointing probably due to the narrow impact of the interventions tested, and our poor understanding of the factors that regulate these complex reactions. This review is not meant to provide a comprehensive review of this field, but rather to highlight what has been learned and to raise interest in this area in need of much attention.

On-chip assay of the effect of topographical microenvironment on cell growth and cell-cell interactions during wound healing

Wound healing is an essential physiological process for tissue homeostasis, involving multiple types of cells, extracellular matrices, and growth factor/chemokine interactions. Many in vitro studies have investigated the interactions between cues mentioned above; however, most of them only focused on a single factor. In the present study, we design a wound healing device to recapitulate in vivo complex microenvironments and heterogeneous cell situations to investigate how three types of physiologically related cells interact with their microenvironments around and with each other during a wound healing process. Briefly, a microfluidic device with a micropillar substrate, where diameter and interspacing can be tuned to mimic the topographical features of the 3D extracellular matrix, was designed to perform positional cell loading on the micropillar substrate, co-culture of three types of physiologically related cells, keratinocytes, dermal fibroblasts, and human umbilical vein endothelial cells, as well as an investigation of their interactions during wound healing. The result showed that cell attachment, morphology, cytoskeleton distribution, and nucleus shape were strongly affected by the micropillars, and these cells showed collaborative response to heal the wound. Taken together, these findings highlight the dynamic relationship between cells and their microenvironments. Also, this reproducible device may facilitate the in vitro investigation of numerous physiological and pathological processes such as cancer metastasis, angiogenesis, and tissue engineering.

Hormetic Effect of Berberine Attenuates the Anticancer Activity of Chemotherapeutic Agents

Hormesis is a phenomenon of biphasic dose response characterized by exhibiting stimulatory or beneficial effects at low doses and inhibitory or toxic effects at high doses. Increasing numbers of chemicals of various types have been shown to induce apparent hormetic effect on cancer cells. However, the underlying significance and mechanisms remain to be elucidated. Berberine, one of the major active components of Rhizoma coptidis, has been manifested with notable anticancer activities. This study aims to investigate the hormetic effect of berberine and its influence on the anticancer activities of chemotherapeutic agents. Our results demonstrated that berberine at low dose range (1.25 ~ 5 μM) promoted cell proliferation to 112% ~170% of the untreated control in various cancer cells, while berberine at high dose rage (10 ~ 80 μM) inhibited cell proliferation. Further, we observed that co-treatment with low dose berberine could significantly attenuate the anticancer activity of chemotherapeutic agents, including fluorouracil (5-FU), camptothecin (CPT), and paclitaxel (TAX). The hormetic effect and thereby the attenuated anticancer activity of chemotherapeutic drugs by berberine may attributable to the activated protective stress response in cancer cells triggered by berberine, as evidenced by up-regulated MAPK/ERK1/2 and PI3K/AKT signaling pathways. These results provided important information to understand the potential side effects of hormesis, and suggested cautious application of natural compounds and relevant herbs in adjuvant treatment of cancer.

What is hormesis and its relevance to healthy aging and longevity?

This paper provides a broad overview of hormesis, a specific type of biphasic dose response, its historical and scientific foundations as well as its biomedical applications, especially with respect to aging. Hormesis is a fundamental component of adaptability, neutralizing many endogenous and environmental challenges by toxic agents, thereby enhancing survival. Hormesis is highly conserved, broadly generalizable, and pleiotrophic, being independent of biological model, endpoint measured, inducing agent, level of biological organization and mechanism. The low dose stimulatory hormetic response has specific characteristics which defines both the quantitative features of biological plasticity and the potential for maximum biological performance, thereby estimating the limits to which numerous medical and pharmacological interventions may affect humans. The substantial degrading of some hormetic processes in the aged may profoundly reduce the capacity to respond effectively to numerous environmental/ischemic and other stressors leading to compromised health, disease and, ultimately, defining the bounds of longevity.

Mitochondria-targeted antioxidants

Redox homeostasis is maintained by the antioxidant defense system, which is responsible for eliminating a wide range of oxidants, including reactive oxygen species (ROS), lipid peroxides, and metals. Mitochondria-localized antioxidants are widely studied because the mitochondria, the major producers of intracellular ROS, have been linked to the cause of aging and other chronic diseases. Mitochondria-targeted antioxidants have shown great potential because they cross the mitochondrial phospholipid bilayer and eliminate ROS at the heart of the source. Growing evidence has identified mitochondria-targeted antioxidants, such as MitoQ and tiron, as potentially effective antioxidant therapies against the damage caused by enhanced ROS generation. This literature review summarizes the current knowledge on mitochondria-targeted antioxidants and their contribution to the body's antioxidant defense system. In addition to addressing the concerns surrounding current antioxidant strategies, including difficulties in targeting antioxidant treatment to sites of pathologic oxidative damage, we discuss promising therapeutic agents and new strategic approaches.