7-deacetylgedunin suppresses inflammatory responses through activation of Keap1/Nrf2/HO-1 signaling

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

Nrf2 Signaling Pathway: Focus on Oxidative Stress in Spinal Cord Injury

Spinal cord injury (SCI) is a serious, disabling injury to the central nervous system that can lead to motor, sensory, and autonomic dysfunction below the injury plane. SCI can be divided into primary injury and secondary injury according to its pathophysiological process. Primary injury is irreversible in most cases, while secondary injury is a dynamic regulatory process. Secondary injury involves a series of pathological events, such as ischemia, oxidative stress, inflammatory events, apoptotic pathways, and motor dysfunction. Among them, oxidative stress is an important pathological event of secondary injury. Oxidative stress causes a series of destructive events such as lipid peroxidation, DNA damage, inflammation, and cell death, which further worsens the microenvironment of the injured site and leads to neurological dysfunction. The nuclear factor erythrocyte 2-associated factor 2 (Nrf2) is considered to be a key pathway of antioxidative stress and is closely related to the pathological process of SCI. Activation of this pathway can effectively inhibit the oxidative stress process and promote the recovery of nerve function after SCI. Therefore, the Nrf2 pathway may be a potential therapeutic target for SCI. This review deeply analyzed the generation of oxidative stress in SCI, the role and mechanism of Nrf2 as the main regulator of antioxidant stress in SCI, and the influence of cross-talk between Nrf2 and related pathways that may be involved in the pathological regulation of SCI on oxidative stress, and summarized the drugs and other treatment methods based on Nrf2 pathway regulation. The objective of this paper is to provide evidence for the role of Nrf2 activation in SCI and to highlight the important role of Nrf2 in alleviating SCI by elucidating the mechanism, so as to provide a theoretical basis for targeting Nrf2 pathway as a therapy for SCI.

Molecular docking, characterization, ADME/toxicity prediction, and anti-ulcer activity of new quercetin derivatives on indomethacin-induced gastric ulcer in mice

Gastric ulcer (GU) is a serious upper gastrointestinal tract disorder that affects people worldwide. The drugs now available for GU treatment have a high rate of relapses and drug interactions, as well as mild to severe side effects. As a result, new natural therapeutic medications for treating GU with fewer negative side effects are desperately needed. Because of quercetin's (QCT) diverse pharmacological effects and unique structural features, we decided to semi-synthesize new QCT derivatives and test them for antiulcer activity. Docking assays were performed on the synthesized compounds to determine their affinity for TLR-4/MD-2, MyD88/TIR, and NF-κB domains, an important inflammatory pathway involved in GU development and progression. Mice were given oral famotidine (40 mg/kg/day), QCT, QCT pentamethyl (QPM), or QCT pentaacetyl (QPA) (50 mg/kg/day) for 5 days before GU induction by a single intraperitoneal injection of indomethacin (INDO; 18 mg/kg). QPM and QPA have a stronger binding affinity for TLR-4/MD-2, MyD88/TIR and NF-κB domains than QCT. In comparison, they demonstrated the greatest reduction in ulcer score and index, gastric MDA and nitric oxide (NO) contents, MyD88 and NF-κB expressions, and gastric TLR-4 immunostaining. They also enhanced the levels of GSH, CAT, COX-1, and COX-2 in the gastric mucosa, as well as HO-1 and Nrf2 expression, with histological regression in gastric mucosal lesions, with QPA-treated mice demonstrating the best GU healing. QPA is safe against all of the target organs and adverse pathways studied, with good ADME properties. However, further in vitro experiments are necessary to demonstrate the inhibitory effects of QPM and QPA on the protein targets of interest. In addition, preclinical research on its bioavailability and safety is essential before clinical management can be undertaken. Overall, the new QPA derivative could one day serve as the basis for a new class of potential antiulcer drugs.

Traditional Uses, Chemical Constituents and Pharmacological Activities of the Toona sinensis Plant

Toona sinensis (A. Juss.) Roem., which is widely distributed in China, is a homologous plant resource of medicine and food. The leaves, seeds, barks, buds and pericarps of T. sinensis can be used as medicine with traditional efficacy. Due to its extensive use in traditional medicine in the ancient world, the T. sinensis plant has significant development potential. In this review, 206 compounds, including triterpenoids (1-133), sesquiterpenoids (134-135), diterpenoids (136-142), sterols (143-147), phenols (148-167), flavonoids (168-186), phenylpropanoids (187-192) and others (193-206), are isolated from the T. sinensis plant. The mass spectrum cracking laws of representative compounds (64, 128, 129, 154-156, 175, 177, 179 and 183) are reviewed, which are conducive to the discovery of novel active substances. Modern pharmacological studies have shown that T. sinensis extracts and their compounds have antidiabetic, antidiabetic nephropathy, antioxidant, anti-inflammatory, antitumor, hepatoprotective, antiviral, antibacterial, immunopotentiation and other biological activities. The traditional uses, chemical constituents, compound cracking laws and pharmacological activities of different parts of T. sinensis are reviewed, laying the foundation for improving the development and utilization of its medicinal value.

Forsythoside B alleviates osteoarthritis through the HMGB1/TLR4/NF-κB and Keap1/Nrf2/HO-1 pathways

Osteoarthritis (OA) is a joint pain and dysfunction syndrome resulting from severe joint degeneration. Inflammation and degeneration of the articular cartilage are two main features of OA and have tight interactions during OA progression. Conventional treatment with nonsteroidal anti-inflammatory drugs has been widely utilized clinically, whereas the side effects have restricted their application. Forsythoside B has been found with anti-inflammatory effects and antiapoptosis in inflammatory diseases, whereas in OA it remains poorly understood. Interleukin (IL)-1β (10 ng/mL) was taken to induce an OA cell model on HC-A chondrocytes and an OA rat model was constructed for in vivo experiments. Forsythoside B was adopted to treat HC-A chondrocytes and OA rats. As shown by the data, Forsythoside B hampered IL-1β-elicited rat chondrocyte apoptosis, oxidative stress, and facilitated proliferation. The profiles of inflammatory factors, NOD-like receptor family pyrin domain containing 3 inflammasomes, Kelch-like epichlorohydrin-associated protein-1 (Keap1), and nuclear factor-κB (NF-κB) phosphorylation were suppressed by Forsythoside B, whereas the nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels were promoted. Further, Forsythoside B mitigated cartilage damage and degeneration. Moreover, the oxidative stress and inflammation mediators in the cartilage tissue of OA rats were remarkably abated. Collectively, Forsythoside B hinders the NF-κB and Keap1/Nrf2/HO-1 pathways to curb IL-1β-elicited OA rat oxidative stress and inflammation both in vivo and ex vivo, ameliorating OA development. All over, this study provides an underlying strategy for treating OA, which might help the clinical treatment of OA patients.

Dexmedetomidine Alleviates Brain Ischemia/Reperfusion Injury by Regulating Metastasis-associated Lung Adenocarcinoma Transcript 1/MicroRNA-140-5p/ Nuclear Factor Erythroid-derived 2-like 2 Axis

BACKGROUND

Dexmedetomidine (Dex) is widely used in perioperative anesthesia, and recent studies have reported that it protects organs from ischemia/reperfusion (I/R) injury.

OBJECTIVES

This study was performed to investigate the role of Dex in alleviating cerebral I/R injury and its regulatory effects on metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/microRNA-140-5p (miR-140-5p)/nuclear factor erythroid-derived 2-like 2 (Nrf2) axis.

METHODS

In vivo rat middle cerebral artery occlusion (MCAO) model and in vitro oxygen-glucose deprivation/re-oxygenation (OGD/R)-induced neuronal injury model were constructed. Dex was injected into the animals or used to culture HT22 cells to observe the pharmacological effects. The neurological defect, brain water content, infarct volume of the rats, and neuron viability were evaluated. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were detected. Besides, the regulatory effects of Dex on MALAT1, miR-140-5p, and Nrf2 expression levels and regulatory relationships among them were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, and dual- luciferase reporter assay.

RESULTS

Dex significantly alleviated the neurological injury of rats with MCAO and promoted the viability of neurons. Dex treatment suppressed miR-140-5p expression, but elevated MALAT1 and Nrf2 expressions. MALAT1 knockdown down-regulated Nrf2 expression and promoted oxidative stress in neurons. Additionally, miR-140-5p directly targeted Nrf2, and it also functioned as a downstream target miRNA of MALAT1.

CONCLUSION

Dex, via regulating MALAT1/miR-140-5p/Nrf2 axis, plays a neuroprotective role against I/R-induced brain injury.

Regulation of toll-like receptor (TLR) signaling pathways in atherosclerosis: from mechanisms to targeted therapeutics

Atherosclerosis, one of the life-threatening cardiovascular diseases (CVDs), has been demonstrated to be a chronic inflammatory disease, and inflammatory and immune processes are involved in the origin and development of the disease. Toll-like receptors (TLRs), a class of pattern recognition receptors that trigger innate immune responses by identifying pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), regulate numerous acute and chronic inflammatory diseases. Recent studies reveal that TLRs have a vital role in the occurrence and development of atherosclerosis, including the initiation of endothelial dysfunction, interaction of various immune cells, and activation of a number of other inflammatory pathways. We herein summarize some other inflammatory signaling pathways, protein molecules, and cellular responses associated with TLRs, such as NLRP3, Nrf2, PCSK9, autophagy, pyroptosis and necroptosis, which are also involved in the development of AS. Targeting TLRs and their regulated inflammatory events could be a promising new strategy for the treatment of atherosclerotic CVDs. Novel drugs that exert therapeutic effects on AS through TLRs and their related pathways are increasingly being developed. In this article, we comprehensively review the current knowledge of TLR signaling pathways in atherosclerosis and actively seek potential therapeutic strategies using TLRs as a breakthrough point in the prevention and therapy of atherosclerosis.

Oxidative stress following spinal cord injury: From molecular mechanisms to therapeutic targets

Spinal cord injury (SCI) is a medical condition that results from severe trauma to the central nervous system; it imposes great psychological and economic burdens on affected patients and their families. The dynamic balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining normal cellular physiological functions. As important intracellular signaling molecules, ROS regulate numerous physiological activities, including vascular reactivity and neuronal function. However, excessive ROS can cause damage to cellular macromolecules, including DNA, lipids, and proteins; this damage eventually leads to cell death. This review discusses the mechanisms of oxidative stress in SCI and describes some signaling pathways that regulate oxidative injury after injury, with the aim of providing guidance for the development of novel SCI treatment strategies.

Magnolol as STAT3 inhibitor for treating multiple sclerosis by restricting Th17 cells

OBJECTIVE

Multiple sclerosis (MS) is an immune disease in the central nervous system (CNS) associated with Th17 cells. Moreover, STAT3 initiates Th17 cell differentiation and IL-17A expression through facilitating RORγt in MS. Here, we reported that magnolol, isolated from Magnolia officinalis Rehd. Et Wils, was regarded as a candidate for MS treatment verified by both in vitro and in vivo studies.

METHODS

In vivo, experimental autoimmune encephalomyelitis (EAE) model in mice was employed to evaluate the alleviation of magnolol on myeloencephalitis. In vitro, FACS assay was employed to evaluate the effect of magnolol on Th17 and Treg cell differentiation and IL-17A expression; network pharmacology-based study was applied to probe the involved mechanisms; western blotting, immunocytochemistry, and luciferase reporter assay was used to further confirm the regulation of magnolol on JAK/STATs signaling pathway; surface plasmon resonance (SPR) assay and molecular docking were applied to manifest affinity with STAT3 and binding sites; overexpression of STAT3 was employed to verify whether magnolol attenuates IL-17A through STAT3 signaling pathway.

RESULTS

In vivo, magnolol alleviated loss of body weight and severity of EAE mice; magnolol improved lesions in spinal cords and attenuated CD45 infiltration, and serum cytokines levels; correspondingly, magnolol focused on inhibiting Th17 differentiation and IL-17A expression in splenocyte of EAE mice; moreover, magnolol selectively inhibited p-STAT3(Y705) and p-STAT4(Y693) of both CD4⁺ and CD8⁺ T cells in splenocyte of EAE mice. In vitro, magnolol selectively inhibited Th17 differentiation and IL-17A expression without impact on Treg cells; network pharmacology-based study revealed that magnolol perhaps diminished Th17 cell differentiation through regulating STAT family members; western blotting further confirmed that magnolol inhibited p-JAK2(Y1007) and selectively antagonized p-STAT3(Y705) and slightly decreased p-STAT4(Y693); magnolol antagonized both STAT3 nucleus location and transcription activity; magnolol had a high affinity with STAT3 and the specific binding site perhaps to be at SH2 domain; overexpression of STAT3 resulted in failed inhibition of magnolol on IL-17A.

CONCLUSION

Magnolol selectively inhibited Th17 differentiation and cytokine expression through selectively blocking of STAT3 resulting in decreased the ratio of Th17/Treg cells for treating MS, suggesting that the potential of magnolol for treating MS as novel STAT3 inhibitor.

Regulation of innate immunity by Nrf2

The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2) has been mainly investigated as a regulator of redox homeostasis. However, research over the past years has implicated Nrf2 as an important regulator of innate immunity. Here, we discuss the role of Nrf2 in the innate immune response, highlighting the interaction between Nrf2 and major components of the innate immune system. Indeed, Nrf2 has been shown to widely control the immune response by interacting directly or indirectly with important innate immune components, including the toll-like receptors-Nuclear factor kappa B (NF-kB) pathway, inflammasome signaling, and the type-I interferon response. This indicates an essential role for Nrf2 in diseases related to microbial infections, inflammation, and cancer. Yet, further studies are required to determine the exact mechanism underpinning the interactions between Nrf2 and innate immune players in order to allow a better understanding of these diseases and leverage new therapeutic strategies.

Importance of Gedunin in Antagonizing Rheumatoid Arthritis via Activating the Nrf2/ARE Signaling

Objective

This study assessed the anti-arthritic effect and protection of Gedunin (GDN) on joint tissues and revealed the possible mechanism in suppressing rheumatoid arthritis (RA).

Methods

LPS-induced macrophages and TNF-α-stimulated synovial fibroblasts (MH7A) or IL-1β-stimulated primary rheumatoid arthritis synovial fibroblasts (RASFs) were used to evaluate the antiinflammatory effect of GDN. In addition, CIA-induced arthritis was employed here to evaluate the anti-arthritic effect. MTT and BRDU assays were utilized to evaluate the cell viability and proliferation, Q-PCR was conducted to detect the mRNA expression of cytokines, FACS was adopted to monitor ROS production, while western blotting (WB) and siRNA interference were applied in confirming the anti-arthritic effects of GDN via the Nrf2 signaling. Results. In vitro, cell viability was inhibited in macrophages and MH7A cells, but not in RASFs; but the proliferation of RASFs was significantly suppressed in time- and dose-dependent manners. GDN suppressed cytokine levels in LPS-stimulated macrophages and TNF-α-stimulated MH7A cells or RASFs. GDN suppressed ROS expression. Furthermore, GDN treatment notably dose-dependently decreased the mRNA and protein expression of iNOS in LPS-induced macrophages. sip62 interference results showed that GDN cause the less expression of HO-1 and Keap1 and also fail to inhibit cytokines after sip62 interference. In vivo, GDN effectively inhibited paw swelling, arthritis score, and arthritis incidence and cytokines.

Conclusions

Our study suggested that GDN exhibited strong antagonistic effect on arthritis both in vitro and in vivo via activation of Nrf2 signaling. Our work will provide a promising therapeutic strategy for RA.

7-deacetyl-gedunin suppresses proliferation of Human rheumatoid arthritis synovial fibroblast through activation of Nrf2/ARE signaling

BACKGROUND

Rheumatoid arthritis (RA) is an chronic autoimmune disease and characterized by high incidence. However, there is no effective therapies for RA. Therefore, it is urgent to discover new drugs for RA treatment. Nuclear factor erythroid 2 (NF-E2)-related factor (Nrf2) can effectively protect against arthritic inflammatory diseases through diverse stages, such as regulating redox balance, detoxification, metabolism and inflammation. Dimethyl fumarate (DMF), targets the Nrf2 pathway, was approved by FDA for the clinical treatment of multiple sclerosis (MS), which is another autoimmune disease. The latest report shown that DMF ameliorates complete Freund's adjuvant-induced arthritis in rats through activation of the Nrf2/HO-1 signaling pathway. Hence, Nrf2 serves as an important target for inflammation interference and oxidative stress of macrophages and RASFs in RA; therefore, it can be adopted as an effective therapeutic approach in the future. Rheumatoid arthritis synovial fibroblasts (RASFs) play crucial roles in the RA pathogenesis. Our results revealed that 7-deacetyl-gedunin (7-d-GDN), derived from fruits of Toona sinensis (A. Juss.) Roem, significantly inhibited RASFs proliferation in dose- and time- dependent manners and inhibited cell viability in MH7A cells, which is a kind of immortal cell line from joints of patients with RA. Additionally, 7-d-GDN remarkably down-regulated MMP-1/3/9/13 in RASFs, IL-6 and IL-33 in MH7A cells. Besides, 7-d-GDN sharply inhibited reactive oxygen species (ROS) in RASFs. Further mechanistic study demonstrated that 7-d-GDN induced heme oxygenase-1 (HO-1), NAD(P)H dehydrogenase quinone 1(NQO1), which all participated in suppressing of oxidative stress. Additionally, 7-d-GDN increased sequestosome 1 (SQSTM1, p62), causing down-regulating Kelch-like ECH-associated protein 1 (Keap1), which resulting in NF-E2-related factor 2 (Nrf2) cytoplasm accumulation and subsequently translocation into nucleus. Collectively, 7-d-GDN exerts the anti-inflammatory effect through regulating anti-oxidative enzymes via p62/ Nrf2/ARE signaling. All suggest that the potential of 7-d-GDN in suppression of inflammation, especially antagonizing RA severity. Our works support for drugs discovery in RA treatment.

Pistachio hull polysaccharide protects Nile tilapia against LPS-induced excessive inflammatory responses and oxidative stress, possibly via TLR2 and Nrf2 signaling pathways

Polysaccharides are polymeric carbohydrates found in living organisms, which have several physiological functions. In the present study, Nile tilapia (Oreochromis niloticus) were fed diets containing three levels (0%, 0.2%, and 0.6%) of Pistacia vera hull polysaccharide (PHP) for 45 days and then injected with PBS or bacterial lipopolysaccharide (LPS). Before the LPS challenge, Nile tilapia fed 0.2% and 0.6% PHP showed significantly increased mean final weight and weight gain compared to those received 0% PHP. The specific growth rate and feed conversion ratio were significantly improved in the treatment fed 0.6% PHP compared to the remaining groups. After LPS challenge, the activities of liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase exhibited the highest values in the 0.6% PHP group. Malondialdehyde (MDA) levels were significantly augmented in the model (fed 0% PHP diet and injected with LPS) and 0.2% PHP groups compared to the control. However, MDA showed decreased levels in the 0.6% PHP group. LPS induced higher mRNA and/or protein levels of Toll-like receptor 2 (TLR2), nuclear factor kappa B (NF-κB), myeloid differentiation primary response protein 88 (Myd88), tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interferon γ (IFN-γ) in Nile tilapia liver. However, PHP administration significantly upregulated the expression of interleukin 10 (IL-10), nuclear erythroid 2-related factor 2 (Nrf2), SOD, and CAT, but markedly suppressed TLR2, NF-κB, Myd88, and pro-inflammatory cytokine expression and/or production in the liver. The findings of the current study indicated that PHP has positive effects on growth performance, immune gene-related expression, and antioxidative activities. We can conclude that PHP can attenuate LPS-induced oxidative stress and inflammatory responses in vivo, possibly via induction of Nrf2 and blockade of TLR2/Myd88/NF-κB pathways in Nile tilapia.

Virtual screening by targeting proteolytic sites of furin and TMPRSS2 to propose potential compounds obstructing the entry of SARS-CoV-2 virus into human host cells

BACKGROUND AND AIM

The year 2020 begins with the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that cause the disease COVID-19, and continue till today. As of March 23, 2021, the outbreak has infected 124,313,054 worldwide with a total death of 2,735,707. The use of traditional medicines as an adjuvant therapy with western drugs can lower the fatality rate due to the COVID-19. Therefore, in silico molecular docking study was performed to search potential phytochemicals and drugs that can block the entry of SARS-CoV-2 into host cells by inhibiting the proteolytic cleavage activity of furin and TMPRSS2.

EXPERIMENTAL PROCEDURE

The protein-protein docking of the host proteases furin and TMPRSS2 was carried out with the virus spike (S) protein to examine the conformational details and residues involved in the complex formation. Subsequently, a library of 163 ligands containing phytochemicals and drugs was virtually screened to propose potential hits that can inhibit the proteolytic cleavage activity of furin and TMPRSS2.

RESULTS AND CONCLUSION

The phytochemicals like limonin, gedunin, eribulin, pedunculagin, limonin glycoside and betunilic acid bind at the active site of both furin and TMPRSS2. Limonin and gedunin found mainly in the citrus fruits and neem showed the highest binding energy at the active site of furin and TMPRSS2, respectively. The polyphenols found in green tea can also be useful in suppressing the furin activity. Among the drugs, the drug nafamostat may be more beneficial than the camostat in suppressing the activity of TMPRSS2.

Pseudocedrela kotschyi: a review of ethnomedicinal uses, pharmacology and phytochemistry

CONTEXT

Pseudocedrela kotschyi (Schweinf) Harms (Meliaceae) is an important medicinal plant found in tropical and subtropical countries of Africa. Traditionally, P. kotschyi is used in the treatment of various diseases including diabetes, malaria, abdominal pain and diarrhoea.

OBJECTIVE

To provide an overview of traditional medicinal claims, pharmacological properties, and phytochemical principles of P. kotschyi as a basis for its clinical applications and further research and development of new drugs.

METHODS

Through interpreting already published scientific manuscripts retrieved from different scientific search engines, namely, Medline, PubMed, EMBASE, Science Direct and Google scholar databases, an up-to-date review on the medicinal potentials of P. kotschyi from inception until September, 2020 was compiled. 'Pseudocedrela kotschyi', 'traditional uses', 'pharmacological properties' and 'chemical constituents' were used as search words.

RESULTS

At present, more than 30 chemical constituents have been isolated and identified from the root and stem bark of P. kotschyi, among which limonoids and triterpenes are the main active constituents. Based on prior research, P. kotschyi has been reported to possess anti-inflammatory, analgesic, antipyretic, anthelminthic, antimalaria, anti-leishmaniasis, anti-trypanosomiasis, hepatoprotective, antioxidant, antidiabetic, antidiarrheal, antimicrobial, and anticancer effects.

CONCLUSIONS

P. kotschyi is reported to be effective in treating a variety of diseases. Current phytochemical and pharmacological studies mainly focus on antimalaria, anti-leishmaniasis, anti-trypanosomiasis and anticancer potential of the root and stem bark of P. kotschyi. Although experimental data support the beneficial medicinal properties of this plant, there is still a paucity of information on its toxicity profile. Nonetheless, this review provides the basis for future research work.

Single-bulb garlic oil regulates toll-like receptors and Nrf2 cross-talk and IL-17 production in mice fed with high-fat diet

The present study aimed to evaluate the effect of single-bulb garlic oil (SGO) on toll-like receptors 3 and 4 (TLR3 and TLR 4) and nuclear erythroid factor-like 2 (Nrf2) signaling pathway resulted from a high-fat diet and its underlying mechanism. Twenty-four Balb/c mice allocated into six groups: 1) N: mice fed with standard chow; 2) HFD: mice fed a high-fat diet for 45 days without any treatment; 3) HFD + Simv: mice fed a high-fat diet for 45 days and treated with simvastatin; 4–6) HFD + SGO 100, 200, 400 (mice fed a high-fat diet for 45 days and treated with single-bulb garlic oil at dose: 100, 200, and 400 mg/kg body weight for 30 days), respectively. At the end of treatment, spleen and hepar were isolated. The flow cytometry analysis was performed to analyze the relative number of nrf2, superoxide dismutase (SOD), malondialdehyde (MDA), TLR3, TLR4 and interleukin (IL-17). The results showed that HFD induction significantly reduced Nrf-2 and antioxidant enzyme levels. Furthermore, HFD induction increased TLR3 and TLR4 signaling and IL-17 production. Interestingly, 200 mg/kg BW of SGO increased the relative number Nrf-2 followed by SOD and HO-1 elevation at a dose of 100 mg/kg BW. SGO100 notably decrease the relative number of TLR3 (CD11b⁺TLR3⁺) and TLR4 (CD11b⁺TLR4⁺). The production of IL-17 by CD4 and CD8 were also reduced after receiving SGO at 200 mg/kg BW. This study suggests that the protective effect of SGO treatment on HFD mice was achieved by modulating TLR-Nrf2 cross-talks and decreasing IL-17 production. Our findings support a potential beneficial role of SGO for treating metabolic disease caused by a high-fat diet.

Khaya grandifoliola C. DC. (Meliaceae: Sapindales): Ethnobotany, phytochemistry, pharmacological properties, and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Khaya grandifoliola is a well-known tree species in Africa with a conservation status of 'vulnerable' due to its overexploitation by the wood industry. Several studies have recorded numerous ethnobotanical uses of this plant, as well as the scientific validation of the efficacy of extracts from different plant parts used for the treatment of various ailments. However, this useful information is scattered throughout the literature and thus there is no opportunity to identify the existing knowledge gaps.

AIM OF THE STUDY

This review aims to highlight the medicinal importance of Khaya grandifoliola including its known phytochemistry, biological activities and toxicology, to encourage a refocused conservation strategy since all current efforts are geared towards maintaining its continuous supply to the wood industry.

MATERIALS AND METHODS

Articles on K. grandifoliola were sourced from online databases such as Google Scholar, Medicine, PubMed, Science Direct, Scopus, SciFinder and other science journal websites up to May 2020. The search was conducted using various combinations of keywords such as biotechnological uses, biological activity, ethnobotany, ethnomedicine, indigenous uses, pharmacological activity, phytochemistry, proximate composition, toxicity, and traditional uses of K. grandifoliola. All downloaded articles were screened to determine their relevance to the scope of the review and the selected papers were included.

RESULTS

The review revealed a host of ethnomedicinal uses such as anticancer, antidiabetic, antimicrobial, anti-sickling, anti-ulcerogenic, and hepatoprotective, many of which are supported by scientific data. More importantly, toxicity tests revealed that many of the extracts are safe at various therapeutic doses. Important knowledge gaps that should be explored include phytochemical characterization and validation of some ethnobotanical claims on the folkloric usage of the plant.

CONCLUSIONS

Notwithstanding the importance of K. grandifoliola in the wood industry, this review reveals that its use as a medicine is equally important. Its medicinal uses are also well supported with scientific studies as well as favourable toxicological studies though some scientific knowledge gaps require further studies.

Limonin induces apoptosis of HL-60 cells by inhibiting NQO1 activity

Limonin is an important bioactive substance in citrus fruits, especially in seeds, which has great potential in cancer prevention and treatment. In order to explore the anticancer activity based on interaction between limonin and NQO1, Human promyelocytic leukemia cells (HL-60) were studied in vitro. We found that limonin could inhibit proliferation and promote apoptosis of HL-60 cells, and the effect was positively correlated with its dosage. Western blot results showed that limonin could activate the endogenous apoptosis pathway mediated by mitochondria via up-regulating pro-apoptotic proteins (Bax, cytochrome c, Caspase3, and Caspase9) and down-regulating anti-apoptotic proteins (Bcl-2), thus inhibiting the proliferation of HL-60 cells and promoting apoptosis, which further proved the anticancer activity of limonin from the molecular mechanism. At the same time, limonin down-regulated the expression of NQO1, indicating that limonin may indirectly act on the apoptosis pathway by regulating the expression activity of antioxidant enzymes in vivo, thus exerting its inhibitory effect on tumor cells, which provides an idea for the molecular mechanism that natural products can indirectly exert their anticancer effect by regulating the activity of antioxidant enzymes.

Possible Susceptibility Genes for Intervention against Chemotherapy-Induced Cardiotoxicity

Recent therapeutic advances have significantly improved the short- and long-term survival rates in patients with heart disease and cancer. Survival in cancer patients may, however, be accompanied by disadvantages, namely, increased rates of cardiovascular events. Chemotherapy-related cardiac dysfunction is an important side effect of anticancer therapy. While advances in cancer treatment have increased patient survival, treatments are associated with cardiovascular complications, including heart failure (HF), arrhythmias, cardiac ischemia, valve disease, pericarditis, and fibrosis of the pericardium and myocardium. The molecular mechanisms of cardiotoxicity caused by cancer treatment have not yet been elucidated, and they may be both varied and complex. By identifying the functional genetic variations responsible for this toxicity, we may be able to improve our understanding of the potential mechanisms and pathways of treatment, paving the way for the development of new therapies to target these toxicities. Data from studies on genetic defects and pharmacological interventions have suggested that many molecules, primarily those regulating oxidative stress, inflammation, autophagy, apoptosis, and metabolism, contribute to the pathogenesis of cardiotoxicity induced by cancer treatment. Here, we review the progress of genetic research in illuminating the molecular mechanisms of cancer treatment-mediated cardiotoxicity and provide insights for the research and development of new therapies to treat or even prevent cardiotoxicity in patients undergoing cancer treatment. The current evidence is not clear about the role of pharmacogenomic screening of susceptible genes. Further studies need to done in chemotherapy-induced cardiotoxicity.

Natural phenylethanoid glycosides isolated from Callicarpa kwangtungensis suppressed lipopolysaccharide-mediated inflammatory response via activating Keap1/Nrf2/HO-1 pathway in RAW 264.7 macrophages cell

ETHNOPHARMACOLOGICAL RELEVANCE

Callicarpa kwangtungensis, as a characteristic traditional herb in China, has been widely used as indigenous medicine for thousands of years in the treatment of upper respiratory tract infection, tonsillitis, pneumonia and traumatic bleeding in China. Phenylethanoid glycosides (PhGs), as natural polyphenols, are especially abundant in this herb and can be regarded as the representative active ingredients in C. kwangtungensis.

AIM OF THIS STUDY

This study was performed to investigate the anti-inflammatory pharmacodynamic basis of six PhGs (acteoside, forsythoside B, poliumoside, alyssonoside, parvifloroside A, and syringalide A 3'-α-L-rhanmnopyranoside) isolated from C. kwangtungensis from the perspective of antioxidation.

MATERIALS AND METHODS

Six PhGs were isolated from the anti-inflammatory extracts of C. kwangtungensis by various chromatographic techniques and their anti-inflammatory activity on RAW 264.7 murine macrophages induced by LPS was investigated by measuring the release of tumor necrosis factor (TNF-α), the colonic interleukin-6 (IL-6), nitric oxide (NO) and reactive oxygen species (ROS). Further, the underlying anti-inflammatory mechanism of two PhGs (forsythoside B and alyssonoside) was explored by determining the expression of Kelch-like ECH-association protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (OH-1) and quinone oxidoreductase 1 (NQO1). Besides, molecular simulation was also employed to evaluate the binding capacity of two PhGs with Keap1.

RESULTS

Compared with the model group, six PhGs revealed obviously inhibitory effects on TNF-α, IL-6, NO and the generation of ROS in RAW 264.7 macrophages. Moreover, forsythoside B and alyssonoside could act as the inhibitors of Keap1-Nrf2 interaction, then activated the nuclear translocation of Nrf2 and promoted the upregulated protein expression of HO-1 and NQO1, finally suppressed LPS-induced inflammatory response in RAW 264.7 macrophages. Molecular modeling exhibited hydrogen bonds played a crucial role for the binding of PhGs with the Nrf2 binding site in Keap1 protein.

CONCLUSIONS

Natural PhGs-induced protection against LPS-induced inflammatory response via activating Keap1/Nrf2/HO-1 signaling pathway in RAW 264.7 macrophages were confirmed, which provided experimental and theoretical basis for the deeper use of C. Kwangtungensis in the treatment and prevention of diseases related to inflammation and oxidative stress.

Polyphenols from Toona sinensiss Seeds Alleviate Neuroinflammation Induced by 6-Hydroxydopamine Through Suppressing p38 MAPK Signaling Pathway in a Rat Model of Parkinson's Disease

Polyphenols from Toona sinensis seeds (PTSS) have demonstrated anti-inflammatory effects in various diseases, while the anti-neuroinflammatory effects still remain to be investigated. We aimed to investigate the effects of PTSS on Parkinson's disease and underlying mechanisms using a rat model. We employed 6-hydroxydopamine (6-OHDA) to male Sprague Dawley (SD) rats and PC12 cells to construct the in vivo and vitro models of PD and dopaminergic (DA) neuron injury, respectively. Cell viability was detected by cell counting kit-8 (CCK-8) assay and protein levels of inflammatory mediators and some p38 MAPK pathway molecules were investigated by immunohistochemistry and Western blot analyses. The results showed that 6-OHDA significantly increased protein levels of inflammatory mediators, such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and tumor necrosis factor α (TNF-α), which could be reversed by PTSS through suppressing the p38 MAPK pathway. The anti-inflammatory effects of PTSS were significantly enhanced by the specific p38 inhibitor of SB203580 in vitro. The present work suggests that PTSS can exert anti-inflammatory effects on PD models, which may be attributed to the suppression of p38 MAPK signaling pathway.

Transcriptional activation of antioxidant gene expression by Nrf2 protects against mitochondrial dysfunction and neuronal death associated with acute and chronic neurodegeneration

Mitochondria are both a primary source of reactive oxygen species (ROS) and a sensitive target of oxidative stress; damage to mitochondria can result in bioenergetic dysfunction and both necrotic and apoptotic cell death. These relationships between mitochondria and cell death are particularly strong in both acute and chronic neurodegenerative disorders. ROS levels are affected by both the production of superoxide and its toxic metabolites and by antioxidant defense mechanisms. Mitochondrial antioxidant activities include superoxide dismutase 2, glutathione peroxidase and reductase, and intramitochondrial glutathione. When intracellular conditions disrupt the homeostatic balance between ROS production and detoxification, a net increase in ROS and an oxidized shift in cellular redox state ensues. Cells respond to this imbalance by increasing the expression of genes that code for proteins that protect against oxidative stress and inhibit cytotoxic oxidation of proteins, DNA, and lipids. If, however, the genomic response to mitochondrial oxidative stress is insufficient to maintain homeostasis, mitochondrial bioenergetic dysfunction and release of pro-apoptotic mitochondrial proteins into the cytosol initiate a variety of cell death pathways, ultimately resulting in potentially lethal damage to vital organs, including the brain. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a translational activating protein that enters the nucleus in response to oxidative stress, resulting in increased expression of numerous cytoprotective genes, including genes coding for mitochondrial and non-mitochondrial antioxidant proteins. Many experimental and some FDA-approved drugs promote this process. Since mitochondria are targets of ROS, it follows that protection against mitochondrial oxidative stress by the Nrf2 pathway of gene expression contributes to neuroprotection by these drugs. This document reviews the evidence that Nrf2 activation increases mitochondrial antioxidants, thereby protecting mitochondria from dysfunction and protecting neural cells from damage and death. New experimental results are provided demonstrating that post-ischemic administration of the Nrf2 activator sulforaphane protects against hippocampal neuronal death and neurologic injury in a clinically-relevant animal model of cardiac arrest and resuscitation.

Oxidative Stress-Responsive MicroRNAs in Heart Injury

Reactive oxygen species (ROS) are important molecules in the living organisms as a part of many signaling pathways. However, if overproduced, they also play a significant role in the development of cardiovascular diseases, such as arrhythmia, cardiomyopathy, ischemia/reperfusion injury (e.g., myocardial infarction and heart transplantation), and heart failure. As a result of oxidative stress action, apoptosis, hypertrophy, and fibrosis may occur. MicroRNAs (miRNAs) represent important endogenous nucleotides that regulate many biological processes, including those involved in heart damage caused by oxidative stress. Oxidative stress can alter the expression level of many miRNAs. These changes in miRNA expression occur mainly via modulation of nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, calcineurin/nuclear factor of activated T cell (NFAT), or nuclear factor kappa B (NF-κB) pathways. Up until now, several circulating miRNAs have been reported to be potential biomarkers of ROS-related cardiac diseases, including myocardial infarction, hypertrophy, ischemia/reperfusion, and heart failure, such as miRNA-499, miRNA-199, miRNA-21, miRNA-144, miRNA-208a, miRNA-34a, etc. On the other hand, a lot of studies are aimed at using miRNAs for therapeutic purposes. This review points to the need for studying the role of redox-sensitive miRNAs, to identify more effective biomarkers and develop better therapeutic targets for oxidative-stress-related heart diseases.

Huang-Lian-Jie-Du Decoction Ameliorates Acute Ulcerative Colitis in Mice via Regulating NF-κB and Nrf2 Signaling Pathways and Enhancing Intestinal Barrier Function

Evidence shows that intestinal inflammation, oxidative stress, and injury of mucosal barrier are closely related to the pathogenesis of ulcerative colitis (UC). Huang-lian-Jie-du Decoction (HLJDD) is a well-known prescription of traditional Chinese medicine with anti-inflammatory and antioxidative activities, which may be used to treat UC. However, its therapeutic effect and mechanism are still unclear. In this study, the UC model of BABL/c mice were established by DSS [3.5% (w/v)], and HLJDD was given orally for treatment at the same time. During the experiment, the clinical symptoms of mice were scored by disease activity index (DAI). Besides, the effects of HLJDD on immune function, oxidative stress, colon NF-κB and Nrf2 signaling pathway, and intestinal mucosal barrier function in UC mice were also investigated. The results showed that HLJDD could alleviate body weight loss and DAI score of UC mice, inhibit colonic shortening and relieve colonic pathological damage, and reduce plasma and colon MPO levels. In addition, HLJDD treatment significantly up-regulated plasma IL-10, down-regulated TNF-α and IL-1β levels, and inhibited the expression of NF-κB p65, p-IκKα/β, and p-IκBα proteins in the colon. Moreover, NO and MDA levels in colon tissues were significantly reduced after HLJDD treatment, while GSH, SOD levels and Nrf2, Keap1 protein expression levels were remarkably elevated. Additionally, HLJDD also protected intestinal mucosa by increasing the secretion of mucin and the expression of ZO-1 and occludin in colonic mucosa. These results indicate that HLJDD could effectively alleviate DSS-induced mice UC by suppressing NF-κB signaling pathway, activating Nrf2 signaling pathway, and enhancing intestinal barrier function.

Identification of an IKKβ inhibitor for inhibition of inflammation in vivo and in vitro

Targeting on the IKKβ to discover anti-inflammatory drugs has been launched for ten years, due to its predominant role in canonical NF-κB signaling. In the current study, we identified a novel IKKβ inhibitor, ellipticine (ELL), an alkaloid isolated from Ochrosia elliptica and Rauvolfia sandwicensis. We found that ELL reduced the secretion and mRNA expression of TNF-α and IL-6 and decreased the protein expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in bone marrow derived macrophages (BMDMs) stimulated with LPS. In coincided with the results, ELL suppressed PGE2 and NO production in BMDMs. Underlying mechanistic study showed that ELL inhibited IκBα phosphorylation and degradation as well as NF-κB nuclear translocation, which was attributed to suppression of IKKα/β activation. Furthermore, kinase assay and binding assay results indicated that ELL inhibited IKKβ activity via directly binding to IKKβ and in turn resulted in suppression of NF-κB signaling. To identify the binding sites of ELL on IKKβ, IKKβ^C46A plasmid was prepared and the kinase assay was performed. The results demonstrated that the inhibitory effect of ELL on IKKβ activity was impaired in the mutation, implying that anti-inflammatory effect of ELL was partially attributed to binding on cysteine 46. Furthermore, ELL up-regulated LC3 II expression and reduced p62 expression, suggesting that autophagy induction contributed to the anti-inflammatory effect of ELL as well. In coincided with the in vitro results, ELL increased the survival and antagonized the hypothermia in the mice with LPS-induced septic shock. Consistently, ELL reduced TNF-α and IL-6 production in the serum of the mice treated with LPS. Collectively, our study provides evidence that ELL is an IKKβ inhibitor and has potential to be developed as a lead compound for treatment inflammatory diseases in the future.

Discovery of Novel Anti-cryptosporidial Activities From Natural Products by in vitro High-Throughput Phenotypic Screening

Cryptosporidium parvum is a globally distributed zoonotic protozoan parasite of both medical and veterinary importance. Nitazoxanide is the only FDA-approved drug to treat cryptosporidiosis in immunocompetent people, but it is not fully effective. There is no drug approved by FDA for use in immunocompromised patients or in animals. In the present study, we conducted phenotypic screening of 800 nature products with defined chemical structures for potential novel activity against the growth of C. parvum in vitro. We identified a large number of compounds showing low to sub-micromolar anti-cryptosporidial activity, and fully characterized 16 top hits for anti-parasitic efficacies in vitro [EC₅₀ values from 0.122 to 3.940 μM, cytotoxicity (TC₅₀) values from 6.31 to >100 μm] and their safety margins. Among them, 11 compounds were derived from plants with EC₅₀ values from 0.267 to 3.940 μM [i.e., cedrelone, deoxysappanone B 7,4'-dimethyl ether (Deox B 7,4), tanshinone IIA, baicalein, deoxysappanone B 7,3'-dimethyl ether acetate, daunorubicin, dihydrogambogic acid, deacetylgedunin, deacetoxy-7-oxogedunin, dihydrotanshinone I, 2,3,4'-trihydroxy-4-methoxybenzophenone, and 3-deoxo-3beta-hydroxy-mexicanolide 16-enol ether]. Three compounds with sub-micromolar EC₅₀ values (i.e., cedrelone, Deox B 7,4, and baicalein) were further investigated for their effectiveness on various parasite developmental stages in vitro. Cedrelone and baicalein were more effective than Dexo B 7,4 when treating parasite for shorter periods of time, but all three compounds could kill the parasite irreversibly. These findings provide us a large selection of new structures derived from natural products to be explored for developing anti-cryptosporidial therapeutics.

Nrf2 in cancers: A double-edged sword

The Nrf2/Keap1 pathway is an important signaling cascade responsible for the resistance of oxidative damage induced by exogenous chemicals. It maintains the redox homeostasis, exerts anti-inflammation and anticancer activity by regulating its multiple downstream cytoprotective genes, thereby plays a vital role in cell survival. Interestingly, in recent years, accumulating evidence suggests that Nrf2 has a contradictory role in cancers. Aberrant activation of Nrf2 is associated with poor prognosis. The constitutive activation of Nrf2 in various cancers induces pro-survival genes and promotes cancer cell proliferation by metabolic reprogramming, repression of cancer cell apoptosis, and enhancement of self-renewal capacity of cancer stem cells. More importantly, Nrf2 is proved to contribute to the chemoresistance and radioresistance of cancer cells as well as inflammation-induced carcinogenesis. A number of Nrf2 inhibitors discovered for cancer treatment were reviewed in this report. These provide a new strategy that targeting Nrf2 could be a promising therapeutic approach against cancer. This review aims to summarize the dual effects of Nrf2 in cancer, revealing its function both in cancer prevention and inhibition, to further discover novel anticancer treatment.

Toona sinensis: a comprehensive review on its traditional usages, phytochemisty, pharmacology and toxicology

Toona sinensis (Juss.) M.Roem, Meliaceae, a deciduous plant native to eastern and southeastern Asia, is widely used in Traditional Chinese Medicine. This paper was aimed to summarize the current advances in traditional usage, phytochemistry, pharmacology and toxicology of T. sinensis. In this review, various types of data of T. sinensis are discussed in the corresponding parts of this paper, and perspectives for possible future studies of this plant are discussed. The main constituents of T. sinensis are terpenoids, phenylpropanoids and flavonoids, etc., and its pharmacological activities include anti-tumor effects, antioxidant activities, anti-diabetic effects and anti-inflammatory effects. Although a series of phytochemical and pharmacological researches of this plant have been conducted, the active constituents and action mechanism of these activities should be also further explored. Furthermore, the present review also indicates that T. sinensis has potentials to develop into drugs for treating various diseases with high efficacy and low toxicity, particularly in cancer, diabetes and inflammatory disorders. In conclusion, the paper provides a full-scale profile of the traditional usage, phytochemistry, pharmacology and toxicology of T. sinensis, and also provides potential therapeutic uses and drug development prospects of this plant.

Crosstalk of toll-like receptors signaling and Nrf2 pathway for regulation of inflammation

Inflammation as a second line of defense of innate immunity plays a crucial role in eliminating invading pathogens (bacteria, viruses, fungi as well as other parasites). The inflammatory response may also activate adaptive immune system involving lymphocytes to mount either antibody dependent or cell-mediated immune responses to clear pathogenic insult. However, if continued, the inflammatory processes may become uncontrolled culminating in cellular injury and tissue destruction, thereby manifesting itself in chronic form. The chronic inflammation has been associated with numerous human pathological conditions like allergies and autoimmune diseases, atherosclerosis, arthritis, Alzheimer's disease, cancer, obesity, type 2 diabetes, schizophrenia, neuro-degenerative diseases and numerous others. The dysregulated inflammatory process is associated with overproduction of free radicals leading to oxidative stress and activation of different cell signaling pathways. The regulation of inflammation by TLR signaling as well as Nrf2 pathways separately is widely documented. Since both these major signaling pathways modulate inflammation, they may crosstalk to bring about coordinated inflammatory responses. The linkage between TLR signaling and Nrf2-Keap1 pathway may serve as a bridge between immune regulation and oxidative stress responses through regulation of inflammation. Also, inflammation is reportedly responsible for the plethora of diseased conditions; a study of its regulation by targeting the TLR-Nrf2 cross-talks may also be beneficial for the development of therapeutic therapies or prophylactic treatments. Hence, present review focuses on the crosstalk between TLR signaling and Nrf2 pathway with respect to their role in modulation of inflammation in normal as well as pathologic conditions.

Extraction, identification, and antioxidant property evaluation of limonin from pummelo seeds

Limonin, the main bioactive phytochemical constituent of limonoids with multi-functions, is enriched in citrus fruits and often found at a high concentration in citrus seeds. The present study was attempted to introduce a new and efficient extraction method to isolate limonoids from pummelo seeds, and to evaluate the antioxidant property of the main constituent limonin in HepG2 cells. Three key single factors were identified for the extraction of limonoids from pummelo seeds using the Box-Behnken experiment design of response surface methodology (RSM), and the optimized extraction parameters were treatment with 89.68 mL of anhydrous acetone for 4.62 h at 78.94 °C, while the yield of limonoids was 11.52 mg/g. The structure of isolated main constituent of the limonoids was further identified as limonin by Fourier transform infrared (FT-IR) spectrometer and nuclear magnetic resonance (NMR) spectrum. Moreover, the molecular data in HepG2 cells revealed that limonin exerted its anti-oxidant property mainly by the activation of nuclear factor (erythroid-2)-like 2 (Nrf2)/kelch-like ECH-associated protein 1 (Keap1)- antioxidant response element (ARE) pathway in the form of transcriptional regulation of Nrf2 mRNA and posttranscriptional regulation of Nrf2/Keap1 system. These results demonstrate that pummelo seeds are an ideal source of limonoids, and limonin is proved to exert its anti-oxidant property by the activation of Nrf2/Keap1 pathway.

The role of Keap1-Nrf2-ARE signal pathway in diabetic retinopathy oxidative stress and related mechanisms

OBJECTIVE

Diabetic retinopathy (DR) is one severe complication of diabetes, and involves reactive oxygen species (ROS) produced under oxidative stress (OS) conditions. Keap1-Nrf2-ARE is one important endogenous anti-OS signal pathway. This study generated a type 2 DR rat model, on which expression of Nrf2/ARE pathway related proteins were measured to investigate functional role and mechanism of Keap1-Nrf2-ARE signal pathway in DR.

PATIENTS AND METHODS

Using DR model rats, blood samples were collected for measuring FBG, TC, TG, HDL-C, and LDL-C for evaluating blood glucose and lipid. Retinas were collected for measuring ROS content using DCFH-DA staining, and caspase-3 activity was measured by colorimetry. Cell apoptosis was measured by flow cytometry. Keap1 and Nrf2 proteins were quantified by Western blot. Aqueous humor was collected for measuring MDA, SOD, GSH-Px, and T-AOC.

RESULTS

Model rats had significantly elevated blood FBG, TG, TC, and LDL-C, plus decreased HDL-C. Model rats also had higher retinal ROS content, enhanced caspase-3 activity, and potentiated apoptosis. Compared to the control group, model rats had elevated MDA and lower activity of SOD, GSH-Px, and T-AOC in aqueous humor, plus lower Keap1 and higher Nrf2 expression in retina.

CONCLUSION

DR rats showed significantly elevated retinal apoptosis, with prominent OS. Under diabetic conditions, activation of Keap1-Nrf2-ARE pathway may play a role in alleviating OS damage and protecting retina.

MicroRNA-140-5p aggravates doxorubicin-induced cardiotoxicity by promoting myocardial oxidative stress via targeting Nrf2 and Sirt2

Clinical application of doxorubicin (DOX), an anthracycline antibiotic with potent anti- tumor effects, is limited because of its cardiotoxicity. However, its pathogenesis is still not entirely understood. The aim of this paper was to explore the mechanisms and new drug targets to treat DOX-induced cardiotoxicity. The in vitro model on H9C2 cells and the in vivo models on rats and mice were developed. The results showed that DOX markedly decreased H9C2 cell viability, increased the levels of CK, LDH, caused histopathological and ECG changes in rats and mice, and triggered myocardial oxidative damage via adjusting the levels of intracellular ROS, MDA, SOD, GSH and GSH-Px. Total of 18 differentially expressed microRNAs in rat heart tissue caused by DOX were screened out using microRNA microarray assay, especially showing that miR-140-5p was significantly increased by DOX which was selected as the target miRNA. Double-luciferase reporter assay showed that miR-140-5p directly targeted Nrf2 and Sirt2, as a result of affecting the expression levels of HO-1, NQO1, Gst, GCLM, Keap1 and FOXO3a, and thereby increasing DOX-caused myocardial oxidative damage. In addition, the levels of intracellular ROS were significantly increased or decreased in H9C2 cells treated with DOX after miR-140-5p mimic or miR-140-5p inhibitor transfection, respectively, as well as the changed expression levels of Nrf2 and Sirt2. Furthermore, DOX- induced myocardial oxidative damage was worsened in mice treated with miR-140-5p agomir, and however the injury was alleviated in the mice administrated with miR-140-5p antagomir. Therefore, miR-140-5p plays an important role in DOX-induced cardiotoxicity by promoting myocardial oxidative stress via targeting Nrf2 and Sirt2. Our data provide novel insights for investigating DOX-induced heart injury. In addition, miR-140-5p/ Nrf2 and miR-140-5p/Sirt2 may be the new targets to treat DOX-induced cardiotoxicity.

Klotho Improves Cardiac Function by Suppressing Reactive Oxygen Species (ROS) Mediated Apoptosis by Modulating Mapks/Nrf2 Signaling in Doxorubicin-Induced Cardiotoxicity

Background

Anthracyclines-induced cardiotoxicity has become one of the major restrictions of their clinical applications. Klotho showed cardioprotective effects. This study aimed to investigate the effects and possible mechanisms of klotho on doxorubicin (DOX)-induced cardiotoxicity.

Material/Methods

Rats and isolated myocytes were exposed to DOX and treated with exogenous klotho. Specific inhibitors and siRNAs silencing MAPKs were also used to treat the animals and/or myocytes. An invasive hemodynamic method was used to determine cardiac functions. Intracellular ROS generation was evaluated by DHE staining. Western blotting was used to determine the phosphorylation levels of JNK, ERK, and p38 MAPKs in plasma extracts and Nrf2 in nuclear extracts. Nuclear translocation of Nrf2 in myocytes was evaluated by immunohistochemistry. Cell apoptosis was evaluated by TUNEL assay and flow cytometry.

Results

Klotho treatment improved DOX-induced cardiac dysfunction in rats. The DOX-induced ROS accumulation and cardiac apoptosis were attenuated by klotho. Impaired phosphorylations of MAPKs, Nrf2 translocation and expression levels of HO1 and Prx1 were also attenuated by klotho treatment. However, the anti-oxidant and anti-apoptotic effects of klotho on DOX-exposed myocardium and myocytes were impaired by both specific inhibitors and siRNAs against MAPKs. Moreover, the recovery effects of klotho on phosphorylations of MAPKs, Nrf2 translocation and expression levels of HO1 and Prx1 were also impaired by specific inhibitors and siRNAs against MAPKs.

Conclusions

By recovering the activation of MAPKs signaling, klotho improved cardiac function loss which was triggered by DOX-induced ROS mediated cardiac apoptosis.