Hormesis: Wound healing and keratinocytes

Role of miR-143-3p in the Development of Hemorrhoids and Postoperative Wound Healing

BACKGROUND

Hemorrhoids refer to a common anorectal disorder that is usually associated with vascular proliferation. The present study investigated the role of miR-143-3p in the development of hemorrhoids and postoperative wound healing, aiming to provide novel ideas for the study of the pathogenesis of hemorrhoids and their clinical treatment.

METHODS

Hemorrhoid tissues and normal perianal tissues were collected from 42 patients who underwent hemorrhoid surgery. The expressions of miR-143-3p, vascular endothelial markers (CD31, vWF, and VEGFR2), and inflammatory factors (TNF-α, IL-1β, and IL-6) in these tissues were determined using RT-qPCR. The correlation of miR-143-3p with CD31, vWF, and VEGFR2 was analyzed using Pearson's method. The proliferation of HUVEC and HaCaT cells was detected using the CCK-8 assay. The migration of HUVEC and HaCaT cells was detected using Transwell assay. The apoptosis of HUVEC cells was detected using flow cytometry.

RESULTS

Reduced expression of miR-143-3p in hemorrhoid tissues was negatively correlated to the mRNA levels of CD31, vWF, and VEGFR2. The mRNA levels of CD31, vWF, and VEGFR2 in the HUVEC cells were reduced after miR-143-3p overexpression. Overexpression of miR-143-3p inhibited the proliferation and migration of HUVEC cells while promoting apoptosis in these cells. Upregulation of miR-143-3p decreased the mRNA levels of TNF-α, IL-1β, and IL-6 in HaCaT cells while promoting cell proliferation and migration in these cells.

CONCLUSIONS

Downregulation of miR-143-3p was noted in hemorrhoids, which could be linked to the regulation of angiogenesis. MiR-143-3p might have an anti-inflammatory role in postoperative wound healing.

Kaempferol, a widely ingested dietary flavonoid and supplement, enhances biological performance via hormesis, especially for ageing-related processes

Kaempferol is a polyphenol in various fruits and vegetables. It is also commercially developed and sold to consumers as a supplement. It has been extensively assessed in clinical trials for clinical utility based upon its numerous experimentally based chemopreventive properties. Kaempferol has been evaluated at the levels of molecule, cell, and individual animal, showing a broad spectrum of biological effects. Kaempferol-induced hormetic concentration responses are common, being reported in many cell types and biological models for numerous endpoints. While the hormetic effects of kaempferol are biologically diverse, there has been a strong focus on age-related endpoints affecting numerous organ systems and endpoints, indicating that kaempferol is a senolytic agent, showing similar properties as quercetin and fisetin. This paper offers the first integrated evaluation of kaempferol-induced hormetic dose responses, their quantitative characteristics, mechanistic explanations, extrapolative strengths or limitations, and related experimental design, biomedical, therapeutic, ageing, and public health, including ageing related applications.

Understanding the pleiotropic effects of CXCL10/IP-10 in the immunopathogenesis of inflammatory rheumatic diseases: Implications for better understanding disease mechanisms

Chemokines play a critical role in immune responses, acting as chemotactic factors and effectors in different immune processes. CXCL10/IFN-gamma-inducible protein 10 (IP-10) is an inflammatory chemokine that regulates immune cell activation and recruitment by binding to its receptor CXCR3. Additionally, CXCL10 inhibits angiogenesis by interacting with endothelial cells (ECs). In the context of inflammatory rheumatic diseases, CXCL10 influences multiple pathways including chemotaxis, angiostasis, bone destruction, joint inflammation, and regulation of fibroblast-like synoviocyte properties. High levels of CXCL10 have been detected in the serum and tissues of individuals with autoimmune conditions like systemic sclerosis (SSc), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and among others (ankylosing spondylitis, Behçet's syndrome). The CXCL10 may inhibit fibroblast recruitment after tissue injury, delaying wound healing; inhibiting angiogenesis, and uncontrolled pulmonary fibrosis in SSc. In RA disease, the CXCL10-CXCR3 axis could increase the inflammatory cell infiltration, including T lymphocytes and macrophages, into inflamed joints, enhancing arthritis severity and bone and cartilage destruction. The interaction between CXCR3 and ligand-CXCL10 on directing the CD4+ T lymphocytes polarization and observed that CXCL10 skew T lymphocytes polarization into Th1/Th17 effector cells that could lead to an increase in the inflammatory responses in the SLE. This study aims to explore the role of CXCL10 in rheumatic diseases and its potential as both a therapeutic target and a biomarker for these conditions. Understanding the involvement of CXCL10 in the immunopathogenesis of inflammatory rheumatic diseases may provide valuable insights for the development of targeted therapies and diagnostic strategies.

Do the hormetic effects of chlorogenic acid mediate some of the beneficial effects of coffee?

The present paper provides the first documentation and assessment of the capacity of chlorogenic acid to induce hormetic dose-response relationships. The findings suggest that chlorogenic acid may induce anabolic (i.e., growth) and catabolic (i.e., protective) hormetic dose responses in several cell types via a range of complementary and cross-talking pathways, affecting a spectrum of endpoints of biomedical and therapeutic importance. This paper also addresses the issue of whether the widely recognized beneficial effects of coffee consumption, as reported in multiple epidemiological studies, may be related to the hormetic effects of chlorogenic acid and its metabolites and their interactions. The present analysis suggests that some beneficial effects of coffee consumption may be due to the effects of chlorogenic acid and/or its metabolites on the gastrointestinal tract via their capacity to impact gastrointestinal integrity, structure, and functionality. These effects collectively contribute to the attenuation of the gastrointestinal tract and concurrent systemic oxidative stress, positively affecting a range of organ-specific effects.

Elucidating the dual roles of apoptosis and necroptosis in diabetic wound healing: implications for therapeutic intervention

Wound healing is a complex and multistep biological process that involves the cooperation of various cell types. Programmed cell death, including apoptosis and necrotizing apoptosis, plays a crucial role in this process. Apoptosis, a controlled and orderly programmed cell death regulated by genes, helps eliminate unnecessary or abnormal cells and maintain internal environmental stability. It also regulates various cell functions and contributes to the development of many diseases. In wound healing, programmed cell death is essential for removing inflammatory cells and forming scars. On the other hand, necroptosis, another form of programmed cell death, has not been thoroughly investigated regarding its role in wound healing. This review explores the changes and apoptosis of specific cell groups during wound healing after an injury and delves into the potential underlying mechanisms. Furthermore, it briefly discusses the possible mechanisms linking wound inflammation and fibrosis to apoptosis in wound healing. By understanding the relationship between apoptosis and wound healing and investigating the molecular mechanisms involved in apoptosis regulation, new strategies for the clinical treatment of wound healing may be discovered.

Sulforaphane and Benzyl Isothiocyanate Suppress Cell Proliferation and Trigger Cell Cycle Arrest, Autophagy, and Apoptosis in Human AML Cell Line

Isothiocyanates (ITCs) are naturally occurring sulfur-containing compounds with diverse biological effects. This study investigated the effects of sulforaphane (SFN, an aliphatic ITC) and benzyl isothiocyanate (BITC, an aromatic ITC) on human acute myeloid leukemia SKM-1 cells, focusing on cell proliferation, cell death, and drug resistance. Both drug-sensitive SKM-1 cells and their drug-resistant SKM/VCR variant, which overexpresses the drug transporter P-glycoprotein, were used. SFN and BITC reduced cell viability in a dose-dependent manner, with BITC showing greater potency. IC50 values ranged from 7.0-8.0 µM for SFN and 4.0-5.0 µM for BITC in both cell types, with only slight differences between the variants. Both ITCs induced autophagy as evidenced by increased LC3-II production and caused a significant increase in the sub-G0/G1 cell population, especially with BITC. Apoptosis was more pronounced after BITC treatment, whereas SFN had a weaker effect. These results suggest that autophagy may act as a defense mechanism in response to ITC-induced apoptosis in human AML cells.

Proteomic analysis reveals the mechanism that low molecular weight hyaluronic acid enhances cell migration in keratinocyte

Hyaluronic acid (HA), as an extracellular matrix, is known to promote wound healing, and its bioactivity is affected by molecular weight. However, the mechanism of LMW-HA on cells migration remains unclear. In this study, we investigated the effect of LMW-HA on cells migration and the underlying mechanism by employing proteomics. The scratch assay showed that LMW-HA can significantly enhance the migration of keratinocytes in vitro, and ten differentially expressed proteins (DEPs) were found to be associated with wound healing through proteomics and network pharmacology. The result of bioinformatic analysis indicated that these DEPs are involved in positive regulation of cell motility and cellular component movement. Moreover, protein targets of key pathways were further validated. The findings suggest that LMW-HA can promote wound healing by accelerating epithelization via the HIF-1α/VEGF pathway, which provides new insight and reference for HA to enhance cells migration.

Hollow Bismuth Nanoparticle-Loaded Gelatin Hydrogel Regulates M2 Polarization of Macrophages to Promote Infected Wound Healing

Open wounds face severe bacterial infection, which affects the quality of healing. Photothermal antimicrobial therapy has received increasing attention as a broad-spectrum antimicrobial treatment that can avoid drug resistance. A variety of metallic materials have been used in the development of photothermal agents. However, there are few studies on bismuth as a photothermal agent and its use in tissue repair, so there is still a lack of clear understanding of its biomedical function. Here, a hollow bismuth nanosphere prepared from bismuth metal was developed for drug loading and photothermal antibacterial effect. The photothermal conversion efficiency of the hollow bismuth spheres reached 16.1%, and the bismuth-loaded gelatin-oxidized dextran (ODex)-based hydrogel achieves good antibacterial effects both in vivo and in vitro. The bismuth-loaded hydrogel can also promote the angiogenesis of human umbilical vein endothelial cells (HUVECs) and improve the proliferation of human keratinocytes cells (HaCaT) and the quality of wound healing. This discovery provides a new idea for the application of metal bismuth in the field of tissue repair and regeneration.

Injectable Photocrosslinked Hydrogel Dressing Encapsulating Quercetin-Loaded Zeolitic Imidazolate Framework-8 for Skin Wound Healing

Background: Wound management is a critical component of clinical practice. Promoting timely healing of wounds is essential for patient recovery. Traditional treatments have limited efficacy due to prolonged healing times, excessive inflammatory responses, and susceptibility to infection. Methods: In this research, we created an injectable hydrogel wound dressing formulated from gelatin methacryloyl (GelMA) that encapsulates quercetin-loaded zeolitic imidazolate framework-8 (Qu@ZIF-8) nanoparticles. Next, its ability to promote skin wound healing was validated through in vitro experiments and animal studies. Results: Research conducted both in vitro and in vivo indicated that this hydrogel dressing effectively mitigates inflammation, inhibits bacterial growth, and promotes angiogenesis and collagen synthesis, thus facilitating a safe and efficient healing process for wounds. Conclusions: This cutting-edge scaffold system provides a novel strategy for wound repair and demonstrates significant potential for clinical applications.

Refrigerated amniotic membrane maintains its therapeutic qualities for 48 hours

During wound healing, the migration of keratinocytes is critical for wound closure. The application of amniotic membrane (AM) on wounds with challenging contexts (e.g., chronification and diabetic foot ulcer) has proven very successful. However, the use of AM for clinical practice has several restraints when applied to patients; the most important restriction is preserving AM's therapeutic properties between its thawing and application onto the patient's wound. Moreover, AM collection and processing requires a cleanroom, together with specialized staff and equipment, and facilities that are not usually available in many hospitals and healthcare units. In this publication, we kept previously cryopreserved AM at different temperatures (37°C, 20°C, and 4°C) in different media (DMEM high glucose and saline solution with or without human albumin) and for long incubation time periods after thawing (24 h and 48 h). HaCaT keratinocytes and TGF-β1-chronified HaCaT keratinocytes were used to measure several parameters related to wound healing: migration, cell cycle arrest rescue, and the expression of key genes and migration-related proteins. Our findings indicate that AM kept in physiological saline solution at 4°C for 24 h or 48 h performed excellently in promoting HaCaT cell migration compared to AM that had been immediately thawed (0 h). Indeed, key proteins, extracellular signal-regulated kinase (ERK) and c-Jun, were induced by AM at 4°C in saline solution. Similarly, cell proliferation and different genes related to survival, inflammation, and senescence had, in all cases, the same response as to standard AM. These data suggest that the handling method in saline solution at 4°C does not interfere with AM's therapeutic properties.

Sea cucumber-derived extract can protect skin cells from oxidative DNA damage and mitochondrial degradation, and promote wound healing

Our skin serves as the primary barrier against external environmental insults, the latter of which can cause oxidative stress within cells, while various bioactive peptides sourced from natural resources hold promise in protecting cells against such oxidative stress. In this study, we investigate the efficacy of a low molecular weight extract from the sea cucumber Apostichopus japonicus, denoted as Sample-P, in facilitating cell migration and wound healing under oxidative stress conditions in skin cells. The naturally derived compound is a highly complex mix of peptides exhibiting antioxidative properties, as highlighted through liquid chromatography-mass spectrometry peptide screening and an in vitro antioxidant assay. Our results demonstrate that Sample-P is capable of promoting cell migration while preventing severe stress responses such as visible through mTOR expression. To further identify the molecular pathways underpinning the overall protective mechanism of Sample-P, we have utilised a proteomics approach. Our data reveal that Sample-P regulates protein expression associated with ribosomal pathways, glycolysis/gluconeogenesis and protein processing in the endoplasmic reticulum (ER), which help in preserving DNA integrity and safeguarding cellular organelles, such as mitochondria and the ER, under oxidative stress conditions in skin cells. In summary, in the presence of H2O2, Sample-P exhibits antioxidative properties at both molecular and cellular levels, rendering it a promising candidate for topical skin treatment to wound healing and to address age-related skin conditions.

The chemoprotective hormetic effects of rosmarinic acid

Rosmarinic acid is a polyphenol found in numerous fruits and vegetables, consumed in supplement form, and tested in numerous clinical trials for therapeutic applications due to its putative chemopreventive properties. Rosmarinic acid has been extensively studied at the cellular, whole animal, and molecular mechanism levels, presenting a complex array of multi-system biological effects. Rosmarinic acid-induced hormetic dose responses are widespread, occurring in numerous biological models and cell types for a broad range of endpoints. Consequently, this article provides the first assessment of rosmarinic acid-induced hormetic concentration/dose responses, their quantitative features, mechanistic foundations, extrapolative strengths/limitations, and their biomedical, clinical, and public health implications.

Oocyte maturation, blastocyst and embryonic development are mediated and enhanced via hormesis

The present paper provides the first integrative assessment of the capacity of dietary, endogenous and other agents to induce hormetic dose responses in oocytes, their supportive cells such as granulosa cells, blastocyst formation and early stage embryo development with the goal of improving fertility and reproductive success. The analysis showed that numerous agents enhance oocyte maturation and blastocyst/embryonic development in an hormetic fashion. These findings indicate that numerous agents improve oocyte-related biological functioning under normal conditions as well as enhancing its capacity to prevent damage from numerous chemical toxins and related stressor agents, including heat and age-related processes in pre-post conditioning and concurrent exposures. The present assessment suggests that hormetic-based lifestyles and dietary interventions may offer the potential to enhance healthy reproductive performance with applications to animal husbandry and human biology. The present findings also significantly extend the generality of the hormesis dose response concept to multiple fundamental biological processes (i.e., oocyte maturation, fertilization and blastocyst/embryo development).

Investigating hormesis, aging, and neurodegeneration: From bench to clinics

Mitochondria-derived reactive oxygen species production at a moderate physiological level plays a fundamental role in the anti-aging signaling, due to their action as redox-active sensors for the maintenance of optimal mitochondrial balance between intracellular energy status and hormetic nutrients. Iron regulatory protein dysregulation, systematically increased iron levels, mitochondrial dysfunction, and the consequent oxidative stress are recognized to underlie the pathogenesis of multiple neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Central to their pathogenesis, Nrf2 signaling dysfunction occurs with disruption of metabolic homeostasis. We highlight the potential therapeutic importance of nutritional polyphenols as substantive regulators of the Nrf2 pathway. Here, we discuss the common mechanisms targeting the Nrf2/vitagene pathway, as novel therapeutic strategies to minimize consequences of oxidative stress and neuroinflammation, generally associated to cognitive dysfunction, and demonstrate its key neuroprotective and anti-neuroinflammatory properties, summarizing pharmacotherapeutic aspects relevant to brain pathophysiology.

Hormesis determines lifespan

This paper addresses how long lifespan can be extended via multiple interventions, such as dietary supplements [e.g., curcumin, resveratrol, sulforaphane, complex phytochemical mixtures (e.g., Moringa, Rhodiola)], pharmaceutical agents (e.g., metformin), caloric restriction, intermittent fasting, exercise and other activities. This evaluation was framed within the context of hormesis, a biphasic dose response with specific quantitative features describing the limits of biological/phenotypic plasticity for integrative biological endpoints (e.g., cell proliferation, memory, fecundity, growth, tissue repair, stem cell population expansion/differentiation, longevity). Evaluation of several hundred lifespan extending agents using yeast, nematode (Caenorhabditis elegans), multiple insect and other invertebrate and vertebrate models (e.g., fish, rodents), revealed they responded in a manner [average (mean/median) and maximum lifespans] consistent with the quantitative features [i.e., 30-60% greater at maximum (Hormesis Rule)] of the hormetic dose response. These lifespan extension features were independent of biological model, inducing agent, endpoints measured and mechanism. These findings indicate that hormesis describes the capacity to extend life via numerous agents and activities and that the magnitude of lifespan extension is modest, in the percentage, not fold, range. These findings have important implications for human aging, genetic diseases/environmental stresses and lifespan extension, as well as public health practices and long-term societal resource planning.

Periplaneta americana extract promotes hard palate mucosal wound healing via the PI3K/AKT signaling pathway in male mice

OBJECTIVES

This study aimed to investigate the effect of Periplaneta americana extract, a traditional Chinese medicine, on hard palate mucosal wound healing and explore the underlying mechanisms.

DESIGN

Hard palate mucosal wound model was established and the effects of Periplaneta americana extract on hard palate mucosal wound healing were investigated by stereomicroscopy observation and histological evaluation in vivo. Human oral keratinocytes and human gingival fibroblasts, which play key roles in hard palate mucosal wound healing, were selected as the main research cells in vitro. The effects of Periplaneta americana extract on cell proliferation, migration, and collagen formation were determined by cell counting kit-8 (CCK-8) assay, Transwell assay, and Van Gieson staining. The underlying mechanism was revealed by RNA sequencing, and results were verified by western blot assay.

RESULTS

Stereomicroscopy observation and H&E staining confirmed that Periplaneta americana extract accelerated the healing rate of hard palate mucosal wound (p < 0.001) in vivo. Transwell assay and Van Gieson staining assay showed that Periplaneta americana extract promoted the migration and collagen formation of human oral keratinocytes (p < 0.001) and human gingival fibroblasts (p < 0.001) in vitro. Mechanistically, RNA sequencing and western blot assay demonstrated that Periplaneta americana extract promoted hard palate mucosal wound healing via PI3K/AKT signaling, and the beneficial effects of Periplaneta americana extract were abrogated by the PI3K inhibitor LY294002.

CONCLUSIONS

Periplaneta americana extract shows promising effects for the promotion of hard palate mucosal wound healing and may be a novel candidate for clinical translation.

Adipose-Derived Mesenchymal Stem Cell-Derived Exosomes Biopotentiated Extracellular Matrix Hydrogels Accelerate Diabetic Wound Healing and Skin Regeneration

Wound healing is an urgent clinical challenge, particularly in the case of chronic wounds. Traditional approaches to wound healing have limited therapeutic efficacy due to lengthy healing times, risk of immune rejection, and susceptibility to infection. Recently, adipose-derived mesenchymal stem cell-derived exosomes (ADSC-exos) have emerged as a promising modality for tissue regeneration and wound repair. In this study, the development of a novel extracellular matrix hydrogel@exosomes (ECM@exo) is reported, which entails incorporation of ADSC-exos into an extracellular matrix hydrogel (ECM hydrogel). This solution forms a hydrogel at physiological temperature (≈37 °C) upon local injection into the wound site. ECM@exo enables sustained release of ADSC-exos from the ECM hydrogel, which maintains high local concentrations at the wound site. The ECM hydrogel displays good biocompatibility and biodegradability. The in vivo and in vitro results demonstrate that ECM@exo treatment effectively reduces inflammation and promotes angiogenesis, collagen deposition, cell proliferation, and migration, thereby accelerating the wound healing process. Overall, this innovative therapeutic approach offers a new avenue for wound healing via a biological hydrogel with controlled exosome release.

Efficacy and Key Materials of East Asian Herbal Medicine Combined with Conventional Medicine on Inflammatory Skin Lesion in Patients with Psoriasis Vulgaris: A Meta-Analysis, Integrated Data Mining, and Network Pharmacology

Psoriasis is a chronic inflammatory disease that places a great burden on both individuals and society. The use of East Asian herbal medicine (EAHM) in combination with conventional medications is emerging as an effective strategy to control the complex immune-mediated inflammation of this disease from an integrative medicine (IM) perspective. The safety and efficacy of IM compared to conventional medicine (CM) were evaluated by collecting randomized controlled trial literature from ten multinational research databases. We then searched for important key materials based on integrated drug data mining. Network pharmacology analysis was performed to predict the mechanism of the anti-inflammatory effect. Data from 126 randomized clinical trials involving 11,139 patients were used. Compared with CM, IM using EAHM showed significant improvement in the Psoriasis Area Severity Index (PASI) 60 (RR: 1.4280; 95% CI: 1.3783-1.4794; p < 0.0001), PASI score (MD: -3.3544; 95% CI: -3.7608 to -2.9481; p < 0.0001), inflammatory skin lesion outcome, quality of life, serum inflammatory indicators, and safety index of psoriasis. Through integrated data mining of intervention data, we identified four herbs that were considered to be representative of the overall clinical effects of IM: Rehmannia glutinosa (Gaertn.) DC., Isatis tinctoria subsp. athoa (Boiss.) Papan., Paeonia × suffruticosa Andrews, and Scrophularia ningpoensis Hemsl. They were found to have mechanisms to inhibit pathological keratinocyte proliferation and immune-mediated inflammation, which are major pathologies of psoriasis, through multiple pharmacological actions on 19 gene targets and 8 pathways in network pharmacology analysis. However, the quality of the clinical trial design and pharmaceutical quality control data included in this study is still not optimal; therefore, more high-quality clinical and non-clinical studies are needed to firmly validate the information explored in this study. This study is informative in that it presents a focused hypothesis and methodology for the value and direction of such follow-up studies.

The Role of Physical Therapies in Wound Healing and Assisted Scarring

Wound healing (WH) is a complex multistep process in which a failure could lead to a chronic wound (CW). CW is a major health problem and includes leg venous ulcers, diabetic foot ulcers, and pressure ulcers. CW is difficult to treat and affects vulnerable and pluripathological patients. On the other hand, excessive scarring leads to keloids and hypertrophic scars causing disfiguration and sometimes itchiness and pain. Treatment of WH includes the cleaning and careful handling of injured tissue, early treatment and prevention of infection, and promotion of healing. Treatment of underlying conditions and the use of special dressings promote healing. The patient at risk and risk areas should avoid injury as much as possible. This review aims to summarize the role of physical therapies as complementary treatments in WH and scarring. The article proposes a translational view, opening the opportunity to develop these therapies in an optimal way in clinical management, as many of them are emerging. The role of laser, photobiomodulation, photodynamic therapy, electrical stimulation, ultrasound therapy, and others are highlighted in a practical and comprehensive approach.

Biopharmaceutical applications of microbial polysaccharides as materials: A review

Biological characteristics of natural polymers make microbial polysaccharides an excellent choice for biopharmaceuticals. Due to its easy purifying procedure and high production efficiency, it is capable of resolving the existing application issues associated with some plant and animal polysaccharides. Furthermore, microbial polysaccharides are recognized as prospective substitutes for these polysaccharides based on the search for eco-friendly chemicals. In this review, the microstructure and properties of microbial polysaccharides are utilized to highlight their characteristics and potential medical applications. From the standpoint of pathogenic processes, in-depth explanations are provided on the effects of microbial polysaccharides as active ingredients in the treatment of human diseases, anti-aging, and drug delivery. In addition, the scholarly developments and commercial applications of microbial polysaccharides as medical raw materials are also discussed. The conclusion is that understanding the use of microbial polysaccharides in biopharmaceuticals is essential for the future development of pharmacology and therapeutic medicine.

Lithium and hormesis: Enhancement of adaptive responses and biological performance via hormetic mechanisms

Biomedical and consumer interest in the health-promoting properties of pure single entities of known or unknown chemical constituents and mixtures has never been greater. Since its "rediscovery" in the 1950s, lithium is an example of such a constituent that represents an array of scientific and public health challenges and medical potentials that may now be understood best when seen through the lens of the dose-response paradigm known as hormesis. The present paper represents the first review of the capacity of lithium to induce hormetic dose responses in a broad range of biological models, organ systems, and endpoints. Of significance is that the numerous hormetic findings occur with extensive concentration/dose response evaluations with the optimal dosing being similar across multiple organ systems. The particular focus of these hormetic dose-response findings was targeted to research with a broad spectrum of stem cell types and neuroprotective effects. These findings suggest that lithium may have critically valuable systemic effects with respect to those therapeutically treated with lithium as well as for exposures that may be achieved via dietary intervention.

Beyond the exposure phase: Microplastic depuration and experimental implications

Currently, most studies focus on the effect of microplastics (MPs) in the exposure phase, but pay limited attention to the depuration phase. Depuration is a promising practice to achieve safe aquaculture production, which is also helpful to understand the long-term impact of MPs. Therefore, investigating the post-exposure scenarios of MPs has great practical significance. In order to provide implications for future research, this work attempted to systematize the current findings and knowledge gaps regarding the depuration of MPs. More specifically, three methods, including direct fitting, one-compartment kinetic model and interval observation, for estimating the retention time of MPs to further determine the minimum depuration time were introduced, in which the one-compartment kinetic model could also be used to calculate the depuration rate constant and biological half-life of MPs. Moreover, the post-exposure effect of MPs generally presented three scenarios: incomplete reversal (legacy effect), return to control level (recovery) and stimulatory response (hormesis-like effect). In addition, the possible tissue translocation of MPs, the influence of food abundance and body shape on MPs egestion, and the potential interaction with environmental factors, have aroused great scientific concerns and need further exploration and clarification.

Hormesis: Wound healing and keratinocytes

Hormetic dose responses (i.e., a biphasic dose/concentration response characterized by a low dose stimulation and a high dose inhibition) are shown herein to be commonly reported in the dermal wound healing process, with the particular focus on cell viability, proliferation, and migration of human keratinocytes in in vitro studies. Hormetic responses are induced by a wide range of substances, including endogenous agents, numerous drug and nanoparticle preparations and especially 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 suggest that the concept of hormesis plays a fundamental role in wound healing, with important potential implications for agent screening and evaluation, as well as clinical strategies.