Highly Selective Activation of Heat Shock Protein 70 by Allosteric Regulation Provides an Insight into Efficient Neuroinflammation Inhibition

Arteannuin B, a sesquiterpene lactone from Artemisia annua, attenuates inflammatory response by inhibiting the ubiquitin-conjugating enzyme UBE2D3-mediated NF-κB activation

BACKGROUND

Anomalous activation of NF-κB signaling is associated with many inflammatory disorders, such as ulcerative colitis (UC) and acute lung injury (ALI). NF-κB activation requires the ubiquitination of receptor-interacting protein 1 (RIP1) and NF-κB essential modulator (NEMO). Therefore, inhibition of ubiquitation of RIP1 and NEMO may serve as a potential approach for inhibiting NF-κB activation and alleviating inflammatory disorders.

PURPOSE

Here, we identified arteannuin B (ATB), a sesquiterpene lactone found in the traditional Chinese medicine Artemisia annua that is used to treat malaria and inflammatory diseases, as a potent anti-inflammatory compound, and then characterized the putative mechanisms of its anti-inflammatory action.

METHODS

Detections of inflammatory mediators and cytokines in LPS- or TNF-α-stimulated murine macrophages using RT-qPCR, ELISA, and western blotting, respectively. Western blotting, CETSA, DARTS, MST, gene knockdown, LC-MS/MS, and molecular docking were used to determine the potential target and molecular mechanism of ATB. The pharmacological effects of ATB were further evaluated in DSS-induced colitis and LPS-induced ALI in vivo.

RESULTS

ATB effectively diminished the generation of NO and PGE2 by down-regulating iNOS and COX2 expression, and decreased the mRNA expression and release of IL-1β, IL-6, and TNF-α in LPS-exposed RAW264.7 macrophages. The anti-inflammatory effect of ATB was further demonstrated in LPS-treated BMDMs and TNF-α-activated RAW264.7 cells. We further found that ATB obviously inhibited NF-κB activation induced by LPS or TNF-α in vitro. Moreover, compared with ATB, dihydroarteannuin B (DATB) which lost the unsaturated double bond, completely failed to repress LPS-induced NO release and NF-κB activation in vitro. Furthermore, UBE2D3, a ubiquitin-conjugating enzyme, was identified as the functional target of ATB, but not DATB. UBE2D3 knockdown significantly abolished ATB-mediated inhibition on LPS-induced NO production. Mechanistically, ATB could covalently bind to the catalytic cysteine 85 of UBE2D3, thereby inhibiting the function of UBE2D3 and preventing ubiquitination of RIP1 and NEMO. In vivo, ATB treatment exhibited robust protective effects against DSS-induced UC and LPS-induced ALI.

CONCLUSION

Our findings first demonstrated that ATB exerted anti-inflammatory functions by repression of NF-κB pathway via covalently binding to UBE2D3, and raised the possibility that ATB could be effective in the treatment of inflammatory diseases and other diseases associated with abnormal NF-κB activation.

Identification of Skp1 as a target of mercury sulfide for neuroprotection

Mercury sulfide (HgS) exerts extensive biological effects on neuronal function. To investigate the direct target of HgS in neuronal cells, we developed a biotin-tagged HgS probe (bio-HgS) and employed an affinity purification technique to capture its target proteins. Then, we identified S-phase kinase-associated protein 1 (Skp1) as a potential target of HgS. Unexpectedly, we discovered that HgS covalently binds to Skp1 through a "Cys62-HgS-Cys120" mode. Moreover, our findings revealed that HgS inhibits the ubiquitin-protease system through Skp1 to up-regulate SNAP-25 expression, thereby triggering synaptic vesicle exocytosis to regulate locomotion ability in C. elegans. Collectively, our findings may promote a comprehensive interpretation of the pharmacological mechanism of mercury sulfide on neuroprotective function.

Handelin alleviates cachexia- and aging-induced skeletal muscle atrophy by improving protein homeostasis and inhibiting inflammation

BACKGROUND

Handelin is a bioactive compound from Chrysanthemum indicum L. that improves motor function and muscle integrity during aging in Caenorhabditis elegans. This study aimed to further evaluate the protective effects and molecular mechanisms of handelin in a mouse muscle atrophy model induced by cachexia and aging.

METHODS

A tumour necrosis factor (TNF)-α-induced atrophy model was used to examine handelin activity in cultured C2C12 myotubes in vitro. Lipopolysaccharide (LPS)-treated 8-week-old model mice and 23-month-old (aged) mice were used to examine the therapeutic effects of handelin on cachexia- and aging-induced muscle atrophy, respectively, in vivo. Protein and mRNA expressions were analysed by Western blotting, ELISA and quantitative PCR, respectively. Skeletal muscle mass was measured by histological analysis.

RESULTS

Handelin treatment resulted in an upregulation of protein levels of early (MyoD and myogenin) and late (myosin heavy chain, MyHC) differentiation markers in C2C12 myotubes (P < 0.05), and enhanced mitochondrial respiratory (P < 0.05). In TNF-α-induced myotube atrophy model, handelin maintained MyHC protein levels, increased insulin-like growth factor (Igf1) mRNA expression and phosphorylated protein kinase B protein levels (P < 0.05). Handelin also reduced atrogin-1 expression, inhibited nuclear factor-κB activation and reduced mRNA levels of interleukin (Il)6, Il1b and chemokine ligand 1 (Cxcl1) (P < 0.05). In LPS-treated mice, handelin increased body weight (P < 0.05), the weight (P < 0.01) and cross-sectional area (CSA) of the soleus muscle (P < 0.0001) and improved motor function (P < 0.05). In aged mice, handelin slightly increased the weight of the tibialis anterior muscle (P = 0.06) and CSA of the tibialis anterior and gastrocnemius muscles (P < 0.0001). In the tibialis anterior muscle of aged mice, handelin upregulated mRNA levels of Igf1 (P < 0.01), anti-inflammatory cytokine Il10 (P < 0.01), mitochondrial biogenesis genes (P < 0.05) and antioxidant-related enzymes (P < 0.05) and strengthened Sod and Cat enzyme activity (P < 0.05). Handelin also reduced lipid peroxidation and protein carbonylation, downregulated mRNA levels of Fbxo32, Mstn, Cxcl1, Il1b and Tnf (P < 0.05), and decreased IL-1β levels in serum (P < 0.05). Knockdown of Hsp70 or using an Hsp70 inhibitor abolished the ameliorating effects of handelin on myotube atrophy.

CONCLUSIONS

Handelin ameliorated cachexia- and aging-induced skeletal muscle atrophy in vitro and in vivo, by maintaining homeostasis of protein synthesis and degradation, possibly by inhibiting inflammation. Handelin is a potentially promising drug candidate for the treatment of muscle wasting.

Drug screening identified that handelin inhibits feline calicivirus infection by inhibiting HSP70 expression in vitro

Feline calicivirus (FCV) is considered one of the major pathogens of cats worldwide and causes upper respiratory tract disease in all cats. In some cats, infection is by a highly virulent strain of FCV (vs.-FCV), which can cause severe and fatal systemic disease symptoms. At present, few antiviral drugs are approved for clinical treatment against FCV. Therefore, there is an imminent need for effective FCV antiviral agents. Here, we used observed a cytopathic effect (CPE) assay to screen 1746 traditional Chinese medicine monomer compounds and found one that can effectively inhibit FCV replication, namely, handelin, with an effective concentration (EC50) value of approximately 2.5 µM. Further study showed that handelin inhibits FCV replication via interference with heat shock protein 70 (HSP70), which is a crucial host factor and plays a positive role in regulating viral replication. Moreover, handelin and HSP70 inhibitors have broad-spectrum antiviral activity. These findings indicate that handelin is a potential candidate for the treatment of FCV infection and that HSP70 may be an important drug target.

Functional material-mediated wireless physical stimulation for neuro-modulation and regeneration

Nerve injuries and neurological diseases remain intractable clinical challenges. Despite the advantages of stem cell therapy in treating neurological disorders, uncontrollable cell fates and loss of cell function in vivo are still challenging. Recently, increasing attention has been given to the roles of external physical signals, such as electricity and ultrasound, in regulating stem cell fate as well as activating or inhibiting neuronal activity, which provides new insights for the treatment of neurological disorders. However, direct physical stimulations in vivo are short in accuracy and safety. Functional materials that can absorb energy from a specific physical field exerted in a wireless way and then release another localized physical signal hold great advantages in mediating noninvasive or minimally invasive accurate indirect physical stimulations to promote the therapeutic effect on neurological disorders. In this review, the mechanism by which various physical signals regulate stem cell fate and neuronal activity is summarized. Based on these concepts, the approaches of using functional materials to mediate indirect wireless physical stimulation for neuro-modulation and regeneration are systematically reviewed. We expect that this review will contribute to developing wireless platforms for neural stimulation as an assistance for the treatment of neurological diseases and injuries.

Handelin protects human skin keratinocytes against ultraviolet B-induced photodamage via autophagy activation by regulating the AMPK-mTOR signaling pathway

Handelin is a natural ingredient extracted from Chrysanthemum boreale flowers that has been shown to decrease stress-related cell death, prolong lifespan, and promote anti-photoaging. However, whether handelin inhibits ultraviolet (UV) B stress-induced photodamage remains unclear. In the present study, we investigate whether handelin has protective properties on skin keratinocytes under UVB irradiation. Human immortalized keratinocytes (HaCaT keratinocytes) were pretreated with handelin for 12 h before UVB irradiation. The results indicated that handelin protects keratinocytes against UVB-induced photodamage by activating autophagy. However, the photoprotective effect of handelin was suppressed by an autophagic inhibitor (wortmannin) or the transfection of keratinocytes with a small interfering RNA targeting ATG5. Notably, handelin reduced mammalian target of rapamycin (mTOR) activity in UVB-irradiated cells in a manner similar to that shown by the mTOR inhibitor rapamycin. Adenosine monophosphate-activated protein kinase (AMPK) activity was also induced by handelin in UVB-damaged keratinocytes. Finally, certain effects of handelin, including autophagy induction, mTOR activity inhibition, AMPK activation, and reduction of cytotoxicity, were suppressed by an AMPK inhibitor (compound C). Our data suggest that handelin effectively prevents photodamage by protecting skin keratinocytes against UVB-induced cytotoxicity via the regulation of AMPK/mTOR-mediated autophagy. These findings provide novel insights that can aid the development of therapeutic agents against UVB-induced keratinocyte photodamage.

Molecular Chaperones' Potential against Defective Proteostasis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neuronal degenerative condition identified via a build-up of mutant aberrantly folded proteins. The native folding of polypeptides is mediated by molecular chaperones, preventing their pathogenic aggregation. The mutant protein expression in ALS is linked with the entrapment and depletion of chaperone capacity. The lack of a thorough understanding of chaperones' involvement in ALS pathogenesis presents a significant challenge in its treatment. Here, we review how the accumulation of the ALS-linked mutant FUS, TDP-43, SOD1, and C9orf72 proteins damage cellular homeostasis mechanisms leading to neuronal loss. Further, we discuss how the HSP70 and DNAJ family co-chaperones can act as potential targets for reducing misfolded protein accumulation in ALS. Moreover, small HSPB1 and HSPB8 chaperones can facilitate neuroprotection and prevent stress-associated misfolded protein apoptosis. Designing therapeutic strategies by pharmacologically enhancing cellular chaperone capacity to reduce mutant protein proteotoxic effects on ALS pathomechanisms can be a considerable advancement. Chaperones, apart from directly interacting with misfolded proteins for protein quality control, can also filter their toxicity by initiating strong stress-response pathways, modulating transcriptional expression profiles, and promoting anti-apoptotic functions. Overall, these properties of chaperones make them an attractive target for gaining fundamental insights into misfolded protein disorders and designing more effective therapies against ALS.

The novel TAK1 inhibitor handelin inhibits NF-κB and AP-1 activity to alleviate elastase-induced emphysema in mice

AIMS

Emphysema, one of the two major components of chronic obstructive pulmonary disease (COPD), is driven by aberrant inflammatory responses and associated with irreversible lung parenchymal destruction. As effective therapy for preventing or treating COPD/emphysema is yet unavailable, development of molecular targets and therapeutic agents for COPD/emphysema is required.

MAIN METHODS AND KEY FINDINGS

We identified handelin-a guaianolide dimer of sesquiterpene lactones- from a chemical library of 431 natural products as it exhibited potent inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) and reactive oxygen species (ROS) production, LPS-induced activation of nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK)/AP-1, and expression of proinflammatory mediators in macrophage cells. In silico docking and biochemical studies enabled the identification of the ATP-binding pocket of transforming growth factor beta-activated kinase 1 (TAK1), a kinase upstream of NF-κB and MAPK/AP-1 pathways, as a molecular target for handelin. Moreover, oral administration of handelin (10 mg/kg) suppressed elastase-induced development of emphysematous phenotypes, including lung function disturbance, airspace enlargement, and increases in the level of neutrophils and CD8+ T cells in lung tissues, without overt toxicity. Consistent with in vitro results, analyses of lung tissues revealed that treatment with handelin suppressed elastase-induced NF-κB and AP-1 activation in the lungs, followed by downregulation of their targets including interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase 9 (MMP9).

SIGNIFICANCE

These findings suggest that handelin, as a TAK1 inhibitor, effectively prevents development of emphysema in an elastase-induced mouse model by inhibiting a proinflammatory mediators mediated by NF-κB and AP-1.

Emerging Role of Alarmins in Food Allergy: An Update on Pathophysiological Insights, Potential Use as Disease Biomarkers, and Therapeutic Implications

Food allergies are immuno-mediated adverse reactions to ingestion or contact with foods, representing a widespread health problem. The immune response can be IgE-mediated, non-IgE-mediated, or with a mixed mechanism. The role of innate immunity and alarmins in the pathogenesis of diseases such as asthma and atopic dermatitis is well known. Some authors have investigated the correlation between alarmins and food allergies, often obtaining interesting results. We analyzed articles published in English from the last 22 years present on PubMed concerning the role of alarmins in the pathogenesis of food allergies and their potential use as disease biomarkers, response biomarkers to therapy, or potential therapeutic targets. Nuclear alarmins (TSLP, IL-33, IL-25) appear to have a critical role in IgE-mediated allergies but are also implicated in entities such as eosinophilic esophagitis. Calprotectin and defensins may play a role as disease biomarkers and could help predict response to therapy, although results in the literature are often conflicting. Despite the promising results, more studies on humans still need to be conducted. Deepening our knowledge regarding alarmins and their involvement in food allergies could lead to the development of new biological therapies, significantly impacting patients' quality of life.

Macrophage Inactivation by Small Molecule Wedelolactone via Targeting sEH for the Treatment of LPS-Induced Acute Lung Injury

Soluble epoxide hydrolase (sEH) plays a critical role in inflammation by modulating levels of epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids (EpFAs). Here, we investigate the possible role of sEH in lipopolysaccharide (LPS)-mediated macrophage activation and acute lung injury (ALI). In this study, we found that a small molecule, wedelolactone (WED), targeted sEH and led to macrophage inactivation. Through the molecular interaction with amino acids Phe362 and Gln384, WED suppressed sEH activity to enhance levels of EETs, thus attenuating inflammation and oxidative stress by regulating glycogen synthase kinase 3beta (GSK3β)-mediated nuclear factor-kappa B (NF-κB) and nuclear factor E2-related factor 2 (Nrf2) pathways in vitro. In an LPS-stimulated ALI animal model, pharmacological sEH inhibition by WED or sEH knockout (KO) alleviated pulmonary damage, such as the increase in the alveolar wall thickness and collapse. Additionally, WED or sEH genetic KO both suppressed macrophage activation and attenuated inflammation and oxidative stress in vivo. These findings provided the broader prospects for ALI treatment by targeting sEH to alleviate inflammation and oxidative stress and suggested WED as a natural lead candidate for the development of novel synthetic sEH inhibitors.

Handelin Reduces Ultraviolet A-Induced Photoaging by Inhibiting Reactive Oxygen Species Generation and Enhancing Autophagy

Photoaging is mainly caused by the exposure of the skin to ultraviolet (UV) radiation. Among them, damage to human dermal fibroblast (HDF) cells caused by ultraviolet A (UVA) is the main cause of skin aging. Researchers have dedicated to identifying natural compounds from plants to fight against UV radiation-induced photoaging. We previously found that extracts from wild chrysanthemum could prevent acute damage and photoaging induced by UV irradiation. As one of the most abundant ingredients in wild chrysanthemum extract, handelin was hypothesized to have the potential to prevent UVA-induced photoaging of skin fibroblast. In the present study, we report the great potential of handelin in combating UVA-induced photoaging of fibroblasts. We firstly demonstrated that handelin was safe for skin fibroblast as high as a concentration of 0.0125 μM, showing no toxicity on the cells and improved cell viability. Furthermore, handelin can reduce UVA-induced cellular senescence, indicated by a reduced proportion of senescence-associated beta-galactose positive cells and the expression of P21. We then verified that handelin pretreatment markedly attenuated the production of reactive oxygen species (ROS) generation after UVA irradiation. Meanwhile, we found that handelin enhances autophagy after UVA irradiation, and autophagy is involved in the quality control of intracellular proteins after UV-induced damage (partially indirectly via ROS). Therefore, these results suggest that handelin has a very high potential as an effective ingredient against UVA-induced skin aging. Moreover, this provides an important basis for further research on the photoprotective mechanism of handelin.

Direct targeting of sEH with alisol B alleviated the apoptosis, inflammation, and oxidative stress in cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a pathological condition characterized by a rapid decrease in glomerular filtration rate and nitrogenous waste accumulation during hemodynamic regulation. Alisol B, from Alisma orientale, displays anti-tumor, anti-complement, and anti-inflammatory effects. However, its effect and action mechanism on AKI is still unclear. Herein, alisol B significantly attenuated cisplatin (Cis)-induced renal tubular apoptosis through decreasing expressions levels of cleaved-caspase 3 and cleaved-PARP and the ratio of Bax/Bcl-2 depended on the p53 pathway. Alisol B also alleviated Cis-induced inflammatory response (e.g. the increase of ICAM-1, MCP-1, COX-2, iNOS, IL-6, and TNF-α) and oxidative stress (e.g. the decrease of SOD and GSH, the decrease of HO-1, GCLC, GCLM, and NQO-1) through the NF-κB and Nrf2 pathways. In a target fishing experiment, alisol B bound to soluble epoxide hydrolase (sEH) as a direct cellular target through the hydrogen bond with Gln384, which was further supported by inhibition kinetics and surface plasmon resonance (equilibrium dissociation constant, K _D = 1.32 μM). Notably, alisol B enhanced levels of epoxyeicosatrienoic acids and decreased levels of dihydroxyeicosatrienoic acids, indicating that alisol B reduced the sEH activity in vivo. In addition, sEH genetic deletion alleviated Cis-induced AKI and abolished the protective effect of alisol B in Cis-induced AKI as well. These findings indicated that alisol B targeted sEH to alleviate Cis-induced AKI via GSK3β-mediated p53, NF-κB, and Nrf2 signaling pathways and could be used as a potential therapeutic agent in the treatment of AKI.

Effects of Avenanthramide on the Small Intestinal Damage through Hsp70-NF-κB Signaling in an Ovalbumin-Induced Food Allergy Model

A food allergy is caused by an abnormal immune reaction and can induce serious intestinal inflammation and tissue damage. Currently, the avoidance of food allergens is still the most effective way to prevent or reduce allergic symptoms, so the development of new strategies to treat allergies is important. Avenanthramide (AVA) is a bioactive polyphenol derived from oats with a wide range of biological activities; however, it is still not clear whether or how AVA alleviates intestinal damage under allergic situations. The aim of this study was to explore the effect of AVA on the small intestinal damage in an ovalbumin (OVA)-induced food allergy model and its mechanism. In experiment 1, 10 mg/kg bw and 20 mg/kg bw doses of AVA both decreased the serum levels of OVA-specific IgE, histamine, and prostaglandin D induced by OVA. The AVA administration relieved inflammation indicated by the lower serum concentrations of pro-inflammatory cytokines including interleukin-1β, IL-6, and tumor necrosis factor-α. The levels of tight junction proteins including Claudin-1, ZO-1, and Occludin in the jejunum were elevated after AVA administration, accompanied by the improved intestinal morphology. Furthermore, AVA elevated the protein expression of heat shock protein 70 (Hsp70) and inhibited the phosphorylation of nuclear factor kappa-B (NF-κB), thus the apoptozole, which a Hsp70 inhibitor, was applied in experiment 2 to assess the contribution of Hsp70-NF-κB signaling to the effects of AVA. In the experiment 2, the inhibition of Hsp70 signaling treatment abolished the beneficial effects of AVA on the small intestinal damage and other allergic symptoms in mice challenged with OVA. Taken together, our results indicated that AVA exerted an intestinal protection role in the OVA-induced allergy, the mechanism of which was partly mediated by the Hsp70-NF-κB signaling.

Exploration of the cysteine reactivity of human inducible Hsp70 and cognate Hsc70

Hsp70s are multifunctional proteins and serve as the central hub of the protein quality control network. Hsp70s are also related to a number of diseases and have been established as drug targets. Human HspA1A (hHsp70) and HspA8 (hHsc70) are the major cytosolic Hsp70s, and they have both overlapping and distinct functions. hHsp70 contains five cysteine residues, and hHsc70 contains four cysteine residues. Previous studies have shown these cysteine residues can undergo different cysteine modifications such as oxidation or reaction with electrophiles to regulate their function, and hHsp70 and hHsc70 have different cysteine reactivity. To address the mechanism of the differences in cysteine reactivity between hHsp70 and hHsc70, we studied the factors that determine this reactivity by Ellman assay for the quantification of accessible free thiols and NMR analysis for the assessment of structural dynamics. We found the lower cysteine reactivity of hHsc70 is probably due to its lower structural dynamics and the stronger inhibition effect of interaction between the α-helical lid subdomain of the substrate-binding domain (SBDα) and the β-sheet substrate-binding subdomain (SBDβ) on cysteine reactivity of hHsc70. We determined that Gly557 in hHsp70 contributes significantly to the higher structural dynamics and cysteine reactivity of hHsp70 SBDα. Exploring the cysteine reactivity of hHsp70 and hHsc70 facilitates an understanding of the effects of redox reactions and electrophiles on their chaperone activity and regulation mechanisms, and how these differences allow them to undertake distinct cellular roles.

Eupalinolide B attenuates lipopolysaccharide-induced acute lung injury through inhibition of NF-κB and MAPKs signaling by targeting TAK1 protein

Acute lung injury (ALI) is a life-threatening disease characterized by severe inflammatory response, which has no pharmacological therapy in clinic. In this study, we found that eupalinolide B (EB), a sesquiterpene lactone isolated from Eupatorium lindleyanum, significantly ameliorated lipopolysaccharide (LPS)-induced ALI in mice, which manifests as reduction in lung injury score, activity of myeloperoxidase, and release of cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1). In RAW264.7 murine macrophages, EB effectively inhibited LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE₂) by down-regulating the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2), respectively. Mechanistically, EB not only blocked LPS-induced phosphorylation of inhibitor of nuclear factor kappa B kinase-α/β (IKKα/β), phosphorylation and degradation of inhibitor of nuclear factor-kappa B alpha (IκBα), and phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-κB) P65, but also suppressed LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs) in vitro or in vivo. Through cellular thermal shift assay and western blotting, EB was demonstrated to target and inactivate transforming growth factor β activated kinase-1 (TAK1), which is an important upstream kinase for the activation of NF-κB and MAPKs pathways. Additionally, EB-mediated actions were markedly abolished by dithiothreitol in LPS-exposed RAW264.7 cells, suggesting a crucial role of the α,γ-unsaturated lactone for the anti-inflammatory activity of EB. In conclusion, our findings showed that EB could effectively alleviate ALI in mice, and attenuate inflammatory response by inhibiting the activation of TAK1, and TAK1-mediated activation of NF-κB and MAPKs cascades.

HSP70 Ameliorates Septic Acute Kidney Injury via Binding with TRAF6 to Inhibit of Inflammation-Mediated Apoptosis

Purpose

Methods

Results

Conclusion

New insights into the role and therapeutic potential of HSP70 in diabetes

Emerging evidence indicates that HSP70 represents a key mechanism in the pathophysiology of β-cell dysfunction, insulin resistance, and various diabetic complications, including micro- and macro-vascular alterations, as well as impaired hemostasis. Hyperglycemia, a hallmark of both types of diabetes, increases the circulating levels of HSP70 (eHSP70), but there is still divergence about whether diabetes up- or down-regulates the intracellular fraction of this protein (iHSP70). Here, we consider that iHSP70 levels reduce in diabetic arterial structures and that the vascular system is in direct contact with all other systems in the body suggesting that a systemic response might also be happening for iHSP70, which is characterized by decreased levels of HSP70 in the vasculature. Furthermore, although many pathways have been proposed to explain HSP70's functions in diabetes, and organs/tissues/cells-specific variations occur, the membrane-bound receptor of the innate immune system, Toll-like receptor 4, and its downstream signal transduction pathways appear to be a constant, not only when we explore the actions of eHSP70, but also when we assess the contributions of iHSP70. In this review, we focus on discussing the multiple roles of HSP70 across organs/tissues/cells affected by hyperglycemia to further explore the possibility of targeting this protein with pharmacological and non-pharmacological approaches in the context of diabetes.

Dehydrocostus Lactone Suppresses Dextran Sulfate Sodium-Induced Colitis by Targeting the IKKα/β-NF-κB and Keap1-Nrf2 Signalling Pathways

Dehydrocostus lactone (DCL) is a major sesquiterpene lactone isolated from Aucklandia lappa Decne, a traditional Chinese herbal medicine that used to treat gastrointestinal diseases. This study aimed to examine the therapeutic effects of DCL on dextran sulfate sodium (DSS)-induced colitis with a focus on identifying the molecular mechanisms involved in DCL-mediated anti-inflammatory activity in macrophages. First, oral administration of DCL (5–15 mg/kg) not only ameliorated symptoms of colitis and colonic barrier injury, but also inhibited the expression of proinflammatory cytokines and myeloperoxidase in colon tissues in DSS-challenged mice. Furthermore, DCL also exhibited significant anti-inflammatory activity in LPS/IFNγ-stimulated RAW264.7 macrophages. Importantly, DCL significantly suppressed the phosphorylation and degradation of IκBα and subsequent NF-κB nuclear translocation, and enhanced the nuclear accumulation of Nrf2 in LPS/IFNγ-treated RAW264.7 cells. Mechanistically, DCL could directly interact with IKKα/β and Keap1, thereby leading to the inhibition of NF-κB signalling and the activation of Nrf2 pathway. Furthermore, DCL-mediated actions were abolished by dithiothreitol, suggesting a thiol-mediated covalent linkage between DCL and IKKα/β or Keap1. These findings demonstrated that DCL ameliorates colitis by targeting NF-κB and Nrf2 signalling, suggesting that DCL may be a promising candidate in the clinical treatment of colitis.

Handelin extends lifespan and healthspan of Caenorhabditis elegans by reducing ROS generation and improving motor function

Aging and aging-related disorders contribute to formidable socioeconomic and healthcare challenges. Several promising small molecules have been identified to target conserved genetic pathways delaying aging to extend lifespan and healthspan in many organisms. We previously found that extract from an edible and medicinal plant Chrysanthemum indicum L. (C. indicum L.) protect skin from UVB-induced photoaging, partially by reducing reactive oxygen species (ROS) generation. Thus, we hypothesized that C. indicum L. and its biological active compound may extend lifespan and health span in vivo. We find that both water and ethanol extracts from C. indicum L. extended lifespan of Caenorhabditis elegans, with better biological effect on life extending for ethanol extracts. As one of the major biological active compounds, handelin extended lifespan of C. elegans too. RNA-seq analysis revealed overall gene expression change of C. elegans post stimulation of handelin focus on several antioxidative proteins. Handelin significantly reduced ROS level and maintained the number and morphology of mitochondria. Moreover, handelin improveed many C. elegans behaviors related to healthspan, including increased pharyngeal pumping and body movement. Muscle fiber imaging analyses revealed that handelin maintains muscle architecture by stabilizing myofilaments. In conclusion, our present study finds a novel compound handelin, from C. indicum L., which bring about biologically beneficial effects by mild stress response, termed as hormetin, that can extend both lifespan and healthspan in vivo on C. elegans. Further study on mammal animal model of natural aging or sarcopenia will verify the potential clinical value of handelin.

Systemic Response of Antioxidants, Heat Shock Proteins, and Inflammatory Biomarkers to Short-Lasting Exercise Training in Healthy Male Subjects

Regular physical activity can enhance immune function and effectively prevents the spread of the cytokine response, thus reducing systemic low-grade inflammation and improving various immune markers. Moreover, regular exercise maintains redox homeostasis in skeletal muscle and other tissues, including immune cells, but the interconnection between the anti-inflammatory effects of exercise with the redox status of immune cells is still poorly understood. With the aim to verify the overall beneficial effect of regular training on the immune system, we have examined the acute and short-term effect of a 5-day exercise program on the modulation of protein and lipid oxidation, antioxidants (i.e., superoxide dismutase-1 (SOD1) and superoxide dismutase-2 (SOD2), glutathione peroxide 1 (GPx1), thioredoxin reductase-1 (TrxR1), and catalase (CAT)), and heat shock protein expression (i.e., heat shock protein-70 (HSP70) and heat shock protein-27 (HSP27)), at both mRNA and protein levels, as well as the activation of the nuclear factor kappa light chain enhancer of activated B cells (NFκB) in peripheral blood mononuclear cells (PBMCs). Moreover, plasmatic markers of oxidative stress, inflammation, and stress response (i.e., protein carbonyl content, interleukin-6 (IL6), interleukin-8 (IL8), interleukin-10 (IL10), interleukin-17E (IL17E), interleukin-17F (IL17F), interleukin-21 (IL21), interleukin-22 (IL22), and interleukin-23 (IL23)) were analyzed in active untrained young adult subjects. Even in the absence of an increased amount of protein or lipid oxidation, we confirmed a PBMC upregulation of SOD1 (1.26 ± 0.07 fold change, p < 0.05), HSP70 (1.59 ± 0.28 fold change, p < 0.05), and HSP27 gene expression (1.49 ± 0.09 fold change, p < 0.05) after 3 hours from the first bout of exercise, followed by an increase in proteins' amount at 24 hours (SOD1, 1.80 ± 0.34 fold change; HSP70, 3.40 ± 0.58 fold change; and HSP27, 1.81 ± 0.20 fold change, p < 0.05) and return to basal levels after the 5 days of aerobic training. Indeed, the posttraining basal levels of oxidized molecules in plasma and PBMCs were statistically lower than the pretraining levels (carbonyl content, 0.50 ± 0.05 fold change, p < 0.01), paralleled by a lower expression of SOD2, Gpx1, and TrxR1, at mRNA (SOD2, 0.63 ± 0.06; GPx1, 0.69 ± 0.07; and TrxR1, 0.69 ± 0.12 fold change, p < 0.05) and protein (TrxR1, 0.49 ± 0.11 fold change, p < 0.05) levels. These results verified the existence of an early phase of redox adaptation to physical exercise already achievable after 5 days of moderate, regular aerobic training. More interestingly, this phenomenon was paralleled by the degree of NFκB activation in PBMCs and the decrease of plasmatic proinflammatory cytokines IL8, IL21, and IL22 in the posttraining period, suggesting an interconnected, short-term efficacy of aerobic exercise towards systemic oxidative stress and inflammation.

Protocatechuic aldehyde protects cardiomycoytes against ischemic injury via regulation of nuclear pyruvate kinase M2

Rescuing cells from stress damage emerges a potential therapeutic strategy to combat myocardial infarction. Protocatechuic aldehyde (PCA) is a major phenolic acid in Chinese herb Danshen (Salvia miltiorrhiza root). This study investigated whether PCA regulated nuclear pyruvate kinase isoform M2 (PKM2) function to protect cardiomyocytes. In rats subjected to isoprenaline, PCA attenuated heart injury and protected cardiomyocytes from apoptosis. Through DARTS and CETSA assays, we identified that PCA bound and promoted PKM2 nuclear translocation in cardiomyocytes exposed to oxygen/glucose deprivation (OGD). In the nucleus, PCA increased the binding of PKM2 to β-catenin via preserving PKM2 acetylation, and the complex, in cooperation with T-cell factor 4 (TCF4), was required for transcriptional induction of genes encoding anti-apoptotic proteins, contributing to rescuing cardiomyocyte survival. In addition, PCA ameliorated mitochondrial dysfunction and prevented mitochondrial apoptosis dependent on PKM2. Consistently, PCA increased the binding of PKM2 to β-catenin, improved heart contractive function, normalized heart structure and attenuated oxidative damage in mice subjected to artery ligation, but the protective effects were lost in Pkm2-deficient heart. Together, we showed that PCA regulated nuclear PKM2 function to rescue cardiomyocyte survival via β-catenin/TCF4 signaling cascade, suggesting the potential of pharmacological intervention of PKM2 shuttle to protect the heart.

Identification of peroxiredoxin 6 as a direct target of withangulatin A by quantitative chemical proteomics in non-small cell lung cancer

Peroxiredoxin 6 (PRDX6), as a bifunctional enzyme with glutathione peroxidase activity (GPx) and Ca2+-independent phospholipase A2 (iPLA2) activity, has a higher expression in various cancer cells, which leads to the increase of antioxidant properties and promotes tumorigenesis. However, only a few inhibitors of PRDX6 have been discovered to date, especially the covalent inhibitors of PRDX6. Here, we firstly identified Withangulatin A (WA), a natural small molecule, as a novel covalent inhibitor of PRDX6. SILAC-ABPP identified that WA could directly bind to PRDX6 and inactivate the enzyme activity of PRDX6 by the α, β-unsaturated ketone moiety. Moreover, WA also facilitated the generation of ROS, and inhibited the GPx and iPLA2 activities. However, WA-1, with a reduced α, β-unsaturated ketone moiety, had no significant inhibition of the GPx and iPLA2 activities. Biolayer interferometry and LC-MS/MS analysis further demonstrated the selectively covalent binding of WA to the cysteine 47 residue (Cys47) of PRDX6, while mutation of Cys47 blocked the binding of WA to PRDX6. Notably, WA-mediated cytotoxicity and inhibition of the GPx and iPLA2 activities were almost abolished by the deficiency of PRDX6. Therefore, this study indicates that WA is a novel PRDX6 covalent inhibitor, which could covalently bind to the Cys47 of PRDX6 and holds great potential in developing anti-tumor agents for targeting PRDX6.

Currently Available Strategies for Target Identification of Bioactive Natural Products

In recent years, biologically active natural products have gradually become important agents in the field of drug research and development because of their wide availability and variety. However, the target sites of many natural products are yet to be identified, which is a setback in the pharmaceutical industry and has seriously hindered the translation of research findings of these natural products as viable candidates for new drug exploitation. This review systematically describes the commonly used strategies for target identification via the application of probe and non-probe approaches. The merits and demerits of each method were summarized using recent examples, with the goal of comparing currently available methods and selecting the optimum techniques for identifying the targets of bioactive natural products.

Elucidating direct kinase targets of compound Danshen dropping pills employing archived data and prediction models

Research on direct targets of traditional Chinese medicine (TCM) is the key to study the mechanism and material basis of it, but there is still no effective methods at present. We took Compound Danshen dropping pills (CDDP) as a study case to establish a strategy to identify significant direct targets of TCM. As a result, thirty potential active kinase targets of CDDP were identified. Nine of them had potential dose-dependent effects. In addition, the direct inhibitory effect of CDDP on three kinases, AURKB, MET and PIM1 were observed both on biochemical level and cellular level, which could not only shed light on the mechanisms of action involved in CDDP, but also suggesting the potency of drug repositioning of CDDP. Our results indicated that the research strategy including both in silico models and experimental validation that we built, were relatively efficient and reliable for direct targets identification for TCM prescription, which will help elucidating the mechanisms of TCM and promoting the modernization of TCM.

Stress and immunity in poultry: light management and nanotechnology as effective immune enhancers to fight stress

The poultry industry plays a significant role in boosting the economy of several countries, particularly developing countries, and acts as a good, cheap, and affordable source of animal protein. A stress-free environment is the main target in poultry production. There are several stressors, such as cold stress, heat stress, high stocking density, and diseases that can affect birds and cause several deleterious changes. Stress reduces feed intake and growth, as well as impairs immune response and function, resulting in high disease susceptibility. These effects are correlated with higher corticosteroid levels that modulate several immune pathways such as cytokine-cytokine receptor interaction and Toll-like receptor signaling along with induction of excessive production of reactive oxygen species (ROS) and thus oxidative stress. Several approaches have been considered to boost bird immunity to overcome stress-associated effects. Of these, dietary supplementation of certain nutrients and management modifications, such as light management, are commonly considered. Dietary supplementations improve bird immunity by improving the development of lymphoid tissues and triggering beneficial immune modulators and responses. Since nano-minerals have higher bioavailability compared to inorganic or organic forms, they are highly recommended to be included in the bird's diet during stress. Additionally, light management is considered a cheap and safe approach to control stress. Changing light from continuous to intermittent and using monochromatic light instead of the normal light improve bird performance and health. Such changes in light management are associated with a reduction of ROS production and increased antioxidant production. In this review, we discuss the impact of stress on the immune system of birds and the transcriptome of oxidative stress and immune-related genes, in addition, how nano-minerals supplementations and light system modulate or mitigate stress-associated effects.

Small molecule induces mitochondrial fusion for neuroprotection via targeting CK2 without affecting its conventional kinase activity

Mitochondrial fusion/fission dynamics plays a fundamental role in neuroprotection; however, there is still a severe lack of therapeutic targets for this biological process. Here, we found that the naturally derived small molecule echinacoside (ECH) significantly promotes mitochondrial fusion progression. ECH selectively binds to the previously uncharacterized casein kinase 2 (CK2) α' subunit (CK2α') as a direct cellular target, and genetic knockdown of CK2α' abolishes ECH-mediated mitochondrial fusion. Mechanistically, ECH allosterically regulates CK2α' conformation to recruit basic transcription factor 3 (BTF3) to form a binary protein complex. Then, the CK2α'/BTF3 complex facilitates β-catenin nuclear translocation to activate TCF/LEF transcription factors and stimulate transcription of the mitochondrial fusion gene Mfn2. Strikingly, in a mouse middle cerebral artery occlusion (MCAO) model, ECH administration was found to significantly improve cerebral injuries and behavioral deficits by enhancing Mfn2 expression in wild-type but not CK2α'^+/- mice. Taken together, our findings reveal, for the first time, that CK2 is essential for promoting mitochondrial fusion in a Wnt/β-catenin-dependent manner and suggest that pharmacologically targeting CK2 is a promising therapeutic strategy for ischemic stroke.

Online energy-resolved MS boosts the potential of LC-MS towards metabolite characterization of salidroside and tyrosol

Although currently serving as the workhorse for metabolite characterization, one of the most challenging tasks for LC-MS is isomeric differentiation because isomers frequently yield identical quasi-molecular ions and fragmented ion species. Our previous studies have demonstrated that online energy-resolved MS (ER-MS) is an orthogonal technique for MS/MS experiments to facilitate isomeric identification. Herein, attempts were made for the in-depth characterization of the metabolic profiles of an effective natural product named salidroside (SA) in rats using LC coupled with three-dimensional mass spectrometry (LC-3D MS) that was configured by MS¹, MS² and online ER-MS as 1^st, 2^nd, and 3^rd dimensions, respectively. Moreover, the metabolism characterization of its aglycone, namely, tyrosol (Try) was conducted in parallel to aid in proposing metabolic pathways. High-resolution MS¹ and MS² spectra were acquired by IT-TOF-MS, and subsequent data processing provided theoretical formula and sub-structures for each metabolite. Subsequently, online ER-MS was conducted for precursor > product ion transitions-of-interest to offer linkage information among the sub-structures via building breakdown graphs. As a result, ten (M1-10) and nine (M1, M2, and M5-11) metabolites were detected in SA- and Tyr-administrated biological samples, respectively, and their structures were qualitatively identified. Crucial metabolism occurred for either component. SA initially underwent hydrolysis to produce Tyr, and subsequently hydroxylation, oxidation, glucuronidation, and sulfation were observed as the primary metabolic pathways. To summarize, the metabolic fate of SA was understood in depth, and Tyr, as the hydrolytic product, was responsible for the occurrences of most metabolites (M1, M2, and M5-10). More importantly, identification confidences of the metabolites were significantly advanced by LC-3D MS, suggesting that it is eligible to serve as an integral part of the analyst's toolbox.

Confirmative Structural Annotation for Metabolites of (R)-7,3'-Dihydroxy-4'-methoxy-8-methylflavane, A Natural Sweet Taste Modulator, by Liquid Chromatography-Three-Dimensional Mass Spectrometry

Flavonoids occupy the largest family of natural products and possess a broad spectrum of health benefits. Their metabolites are sometimes the truly effective molecules in vivo. It is still challenging, however, to unambiguously identify flavonoid metabolites using conventional LC-MS/MS. Herein, we aimed to pursue auxiliary structural clues to m/z values in both MS¹ and MS² spectra through LC coupled to three-dimensional MS (LC-3D MS). MS¹, as the first dimension, was in charge of suggesting theoretical molecular formulas, MS², the as second dimension, was responsible for offering substructures, and exactly, online energy-resolved MS (ER-MS), as the third dimension, provided optimal collision energies (OCEs) that reflected the linkage manners among the substructures. Metabolic characterization of a natural sweet taste modulator, namely, (R)-7,3'-dihydroxy-4'-methoxy-8-methylflavane (DHMMF), was conducted as a proof-of-concept. Extensive efforts, such as full MS¹ and MS² scans on IT-TOF-MS and predictive selected-reaction monitoring mode on Qtrap-MS, were made for in-depth metabolite mining. Seventeen metabolites (M1-M17) were captured from DHMMF-treated biological samples, including 17 (M1-M17), 10 (M4-M9, M11, M13, M14, and M16), and 2 (M5 and M10) metabolites from urine, plasma, and feces, respectively. Their structures were configured by integrating MS¹, MS², and OCE information. Except M10, all metabolites were new compounds. LC-MS/MS-guided chromatographic purification yielded three glucuronyl-conjugated metabolites (M5, M8, and M11), and NMR spectroscopic assays consolidated the structures transmitted from LC-3D MS. Demethylation, glucuronidation, and sulfation occurred as the primary metabolic pathways of DHMMF. Above all, LC-3D MS bridged LC-MS/MS from putatively structural annotation toward confidence-enhanced identification, beyond the metabolite characterization of flavonoids.

Hsp70 and NF-kB Mediated Control of Innate Inflammatory Responses in a Canine Macrophage Cell Line

The pathogenesis of many inflammatory diseases is associated with the uncontrolled activation of nuclear factor kappa B (NF-κB) in macrophages. Previous studies have shown that in various cell types, heat shock protein 70 (Hsp70) plays a crucial role in controlling NF-κB activity. So far, little is known about the role of Hsp70 in canine inflammatory processes. In this study we investigated the potential anti-inflammatory effects of Hsp70 in canine macrophages as well as the mechanisms underlying these effects. To this end, a canine macrophage cell line was stressed with arsenite, a chemical stressor, which upregulated Hsp70 expression as detected by flow cytometry and qPCR. A gene-edited version of this macrophage cell line lacking inducible Hsp70 was generated using CRISPR-Cas9 technology. To determine the effects of Hsp70 on macrophage inflammatory properties, arsenite-stressed wild-type and Hsp70 knockout macrophages were exposed to lipopolysaccharide (LPS), and the expression of the inflammatory cytokines IL-6, IL-1β and tumor necrosis factor-α (TNF-α) and levels of phosphorylated NF-κB were determined by qPCR and Western Blotting, respectively. Our results show that non-toxic concentrations of arsenite induced Hsp70 expression in canine macrophages; Hsp70 upregulation significantly inhibited the LPS-induced expression of the pro-inflammatory mediators TNF-α and IL-6, as well as NF-κB activation in canine macrophages. Furthermore, the gene editing of inducible Hsp70 by CRISPR-Cas9-mediated gene editing neutralized this inhibitory effect of cell stress on NF-κB activation and pro-inflammatory cytokine expression. Collectively, our study reveals that Hsp70 may regulate inflammatory responses through NF-κB activation and cytokine expression in canine macrophages.

Autophagy and Hsp70 activation alleviate oral epithelial cell death induced by food-derived hypertonicity

Stable intracellular and intercellular osmolarity is vital for all physiological processes. Although it is the first organ that receives food, the osmolarity around the mouth epithelium has never been systematically investigated. We found that oral epithelial cells are a population of ignored cells routinely exposed to hypertonic environments mainly composed of saline, glucose, etc. in vivo after chewing food. By using cultured oral epithelial cells as an in vitro model, we found that the hypotonic environments caused by both high NaCl and high glucose induced cell death in a dose- and time-dependent manner. Transcriptomics revealed similar expression profiles after high NaCl and high glucose stimulation. Most of the common differentially expressed genes were enriched in "mitophagy" and "autophagy" according to KEGG pathway enrichment analysis. Hypertonic stimulation for 1 to 6 h resulted in autophagosome formation. The activation of autophagy protected cells from high osmolarity-induced cell death. The activation of Hsp70 by the pharmacological activator handelin significantly improved the cell survival rate after hypertonic stimulation. The protective role of Hsp70 activation was partially dependent on autophagy activation, indicating a crosstalk between Hsp70 and autophagy in hypertonic stress response. The extract of the handelin-containing herb Chrysanthemum indicum significantly protected oral epithelial cells from hypertonic-induced death, providing an inexpensive way to protect against hypertonic-induced oral epithelial damage. In conclusion, the present study emphasized the importance of changes in osmolarity in oral health for the first time. The identification of novel compounds or herbal plant extracts that can activate autophagy or HSPs may contribute to oral health and the food industry.

Leucinostatin acts as a co-inducer for heat shock protein 70 in cultured canine retinal pigment epithelial cells

Dysregulation of retinal pigment epithelium (RPE) cells is the main cause of a variety of ocular diseases. Potentially heat shock proteins, by preventing molecular and cellular damage and modulating inflammatory disease, may exert a protective role in eye disease. In particular, the inducible form of heat shock protein 70 (Hsp70) is widely upregulated in inflamed tissues, and in vivo upregulation of Hsp70 expression by HSP co-inducing compounds has been shown to be a potential therapeutic strategy for inflammatory diseases. In order to gain further understanding of the potential protective effects of Hsp70 in RPE cells, we developed a method for isolation and culture of canine RPE cells. Identity of RPE cells was confirmed by detection of its specific marker, RPE65, in qPCR, flow cytometry, and immunocytochemistry analysis. The ability of RPE cells to express Hsp70 upon experimental induction of cell stress, by arsenite, was analyzed by flow cytometry. Finally, in search of a potential Hsp70 co-inducer, we investigated whether the compound leucinostatin could enhance Hsp70 expression in stressed RPE cells. Canine RPE cells were isolated and cultured successfully. Purity of cells that strongly expressed RPE65 was over 90%. Arsenite-induced stress led to a time- and dose-dependent increase in Hsp70 expression in canine RPE cells in vitro. In addition, leucinostatin, which enhanced heat shock factor-1-induced transcription from the heat shock promoter in DNAJB1-luc-O23 reporter cell line, also enhanced Hsp70 expression in arsenite-stressed RPE cells, in a dose-dependent fashion. These findings demonstrate that leucinostatin can boost Hsp70 expression in canine RPE cells, most likely by activating heat shock factor-1, suggesting that leucinostatin might be applied as a new co-inducer for Hsp70 expression.

Allosteric regulation of protein 14-3-3ζ scaffold by small-molecule editing modulates histone H3 post-translational modifications

Background: Histone post-translational modifications (PTMs) are involved in various biological processes such as transcriptional activation, chromosome packaging, and DNA repair. Previous studies mainly focused on PTMs by directly targeting histone-modifying enzymes such as HDACs and HATs.

Methods and Results: In this study, we discovered a previously unexplored regulation mechanism for histone PTMs by targeting transcription regulation factor 14-3-3ζ. Mechanistic studies revealed 14-3-3ζ dimerization as a key prerequisite, which could be dynamically induced via an allosteric effect. The selective inhibition of 14-3-3ζ dimer interaction with histone H3 modulated histone H3 PTMs by exposing specific modification sites including acetylation, trimethylation, and phosphorylation, and reprogrammed gene transcription profiles for autophagy-lysosome function and endoplasmic reticulum stress.

Conclusion: Our findings demonstrate the feasibility of editing histone PTM patterns by targeting transcription regulation factor 14-3-3ζ, and provide a distinctive PTM editing strategy which differs from current histone modification approaches.

Nitric oxide regulates intussusceptive-like angiogenesis in wound repair in chicken embryo and transgenic zebrafish models

Angiogenesis is the formation of new blood vessels that occurs by two distinct processes following sprouting angiogenesis (SA) and intussusceptive angiogenesis (IA). Nitric oxide (NO) is known for its pro-angiogenic functions. However, no clear mechanisms are delineated on its role in promoting angiogenesis in reparative wound healing. We propose that NO regulates SA to IA transition and vice versa in wound milieu. We have used three models which include a new chick embryo extra-vasculature (CEV) burn wound model, adult Tie2-GFP transgenic Zebrafish caudal fin regeneration model and Zebrafish skin wound model to study the mechanisms underlying behind the role of NO in wound healing. Wounds created in CEV were treated with NO donor (Spermine NONOate (SPNO)), NOS inhibitor (L-nitro-l-arginine-methyl ester (l-NAME)), NaNO₂, NaNO₃, and beetroot juice, a nitrite-rich juice respectively and the pattern of wound healing was assessed. Morphological and histological techniques tracked the wound healing at the cellular level, and the molecular changes were investigated by using real-time RT-PCR gene expression analysis. The result concludes that NO donor promotes wound healing by activating SA at an early phase of healing while NOS inhibitor induces wound healing via IA. At the later phase of wound healing NO donor followed IA while NOS inhibitor failed to promote wound repair. The current work underpinned a differential regulation of NO on angiogenesis in wound milieu and this study would provide new insights in designing therapeutics for promoting wound repair.

Shikimic acid from Artemisia absinthium inhibits protein glycation in diabetic rats

This study investigated the impact of Shikimic Acid (SA) obtained from leaves of Artemisia absinthium on protein glycation in the retina of diabetic rats. The GC/MS analysis of A. absinthium showed that the most abundant bioactive compound was SA (C₇H₁₀O₅) with a measured retention Index (RI) of 1960 compared to that of the reference sample (1712). Male albino rats were divided into two main groups, Group I (control) and Group II (diabetic); Group II was further divided into four subgroups: Group IIa (diabetic control), Group IIb (diabetic rats were given SA orally [50 mg/kg, body weight (bw)/day], Group IIc diabetic rats were given SA orally [100 mg/kg, bw/day], and Group IId (diabetic rats were given metformin orally [100 mg/kg, bw/day] as positive control). The data obtained suggested that SA reduced glucose and glycated hemoglobin levels. In addition, SA also decreased the formation of glucose-derived advanced glycation end products. Interestingly, SA showed interference with the release of inflammatory mediators in retina and possess antioxidant potential. In conclusion, SA protected the tissues from detrimental effects of hyperglycemia and enhanced antioxidant activity. SA could be a potential lead in the process of drug development in the future to prevent retinopathy in diabetic subjects.