Protective effects of melatonin and N-acetyl cysteine against oxidative stress induced by microcystin-LR on cardiac muscle tissue

Rescuing Nucleus Pulposus Cells From Senescence via Dual-Functional Greigite Nanozyme to Alleviate Intervertebral Disc Degeneration

High levels of reactive oxygen species (ROS) lead to progressive deterioration of mitochondrial function, resulting in tissue degeneration. In this study, ROS accumulation induced nucleus pulposus cells (NPCs) senescence is observed in degenerative human and rat intervertebral disc, suggesting senescence as a new therapeutic target to reverse intervertebral disc degeneration (IVDD). By targeting this, dual-functional greigite nanozyme is successfully constructed, which shows the ability to release abundant polysulfides and presents strong superoxide dismutase and catalase activities, both of which function to scavenge ROS and maintain the tissue at physical redox level. By significantly lowering the ROS level, greigite nanozyme rescues damaged mitochondrial function in IVDD models both in vitro and in vivo, rescues NPCs from senescence and alleviated the inflammatory response. Furthermore, RNA-sequencing reveals ROS-p53-p21 axis is responsible for cellular senescence-induced IVDD. Activation of the axis abolishes greigite nanozyme rescued NPCs senescence phenotype, as well as the alleviated inflammatory response to greigite nanozyme, which confirms the role of ROS-p53-p21 axis in greigite nanozyme's function to reverse IVDD. In conclusion, this study demonstrates that ROS-induced NPCs senescence leads to IVDD and the dual-functional greigite nanozyme holds strong potential to reverse this process, providing a novel strategy for IVDD management.

Microcystin-LR-induced autophagy regulates oxidative stress, inflammation, and apoptosis in grass carp ovary cells in vitro

MC-LR is one of the cyanotoxins produced by fresh water cyanobacteria. Previous studies showed that autophagy played an important role in MC-LR-induced reproduction toxicity. However, information on the toxicological mechanism is limited. In this study, MC-LR could induce autophagy and apoptosis in GCO cells in vitro. In GCO cells that had been exposed to MC-LR, the inhibitor of 3-MA effectively decreased cell viability and damaged cell ultrastructure. Oxidative stress was significantly increased in the 3-MA + MC-LR group, accompanied by significantly increased MDA content and decreased CAT activity and GST, SOD1, GPx, and GR expression levels (P < 0.05). Inflammation was more serious in the 3-MA + MC-LR group than that of MC-LR group, which was evidenced by increasing expression levels of TNFα, IL11, MyD88, TNFR1, TRAF2, JNK, CCL4, and CCL20 (P < 0.05). Interestingly, the significant decrease of Caspase-9, Caspase-7, and Bax expression and significant increase of Bcl-2 and Bcl-2/Bax ratio in 3-MA + MC-LR group compared to MC-LR group, suggesting that extent of apoptosis were reduced. Taken together, these results indicated that MC-LR induced autophagy and apoptosis in GCO cells, however, the inhibition of autophagy decreased the extent of apoptosis, induced more serious oxidative stress and inflammation, which eventually induced cell death. Our findings provided some information for exploring the toxicity of MC-LR, however, the role of autophagy require further study in vivo.

Algicidal effect of tryptoline against Microcystis aeruginosa: Excess reactive oxygen species production mediated by photosynthesis

Cyanobacterial blooms significantly decrease water quality and can damage ecosystems and, as such, require efficient control methods. Algicidal bacteria and their associated substances are promising tools for controlling cyanobacterial blooms; however, their specific algicidal mechanisms remain unclear. Therefore, the current study sought to investigate the algicidal mechanism of tryptoline (1,2,3,4-tetrahydro-9 h-pyrido[3,4-b]indole) against Microcystis aeruginosa, with a specific focus on the contribution made by reactive oxygen species (ROS), the underlying mechanisms of ROS increase, as well as the photosystem response. Results show that the algicidal ratio of tryptoline significantly and positively correlates with algal ROS. Moreover, 93.79% of the algicidal ratio variation is attributed to ROS in the tryptoline group, while only 47.75% can be attributed to ROS in the tryptoline + N-acetyl-L-cysteine (NAC) group, where ROS are partially scavenged by NAC. In the presence of tryptoline, algicidal effect and ROS levels were significantly enhanced in the presence of light as compared to those in the dark (P < 0.001). Hence, the increase in ROS production attributed to tryptoline is primarily affected by the presence of light and photosynthesis. Additionally, tryptoline significantly reduces F_v/F_m, PI_ABS, ET_o/RC, and the expression of psaB and psbA genes related to photosynthesis, while increasing V_j and DI_o/RC (P < 0.05). These results suggest that tryptoline hinders algal photosynthesis by significantly decreasing photosynthetic efficiency and carbon assimilation, inhibiting photochemical electron transfer, and increasing closed reaction centers and energy loss. Moreover, following partial blockade of the photosynthetic electron transfer from Q_A to Q_B by diuron (3-(3-4-dichlorophenyl)-1,1-dimethylurea), the ROS of algae exposed to tryptoline is significantly decreased. Thus, tryptoline inhibits electron transfer downstream of Q_A, which increase the number of escaping electron and thereby increase ROS generation. Collectively, this study describes the algicidal mechanism of tryptoline against M. aeruginosa and highlights the critical factors associated with induction of algicidal activity.

Protective effects of Schisandrin B against D-GalN-induced cell apoptosis in human hepatocyte (L02) cells via modulating Bcl-2 and Bax

Schisandrin B is a dibenzocyclooctadiene derivative extracted fromSchisandra chinensis (Turcz.) Baill., that exhibits anti-oxidation, anti-inflammation, anti-tumor and hepatoprotective activities. To understand the hepatoprotective mechanism of schisandrin B, this study investigated the efficacy of schisandrin B on L02 cells after treatment with D-GalN. Following pretreatment with 40 μM schisandrin B, L02 cells were stimulated with 40 mM D-GalN. Cell viability, apoptosis, the expression levels of genes associated with apoptosis, and the intracellular oxidative stress indexes were measured. The viability of L02 cells was determined using MTT assay, and the Annexin V-FITC/PI assay kit was utilized for the assessment of apoptosis. The activities of GSH-Px and SOD, the level of MDA were assessed, separately, using relative detection kits. Moreover, RT-PCR as well as Western blot was applied to measure the mRNA and protein expression of Bax and Bcl-2. The results indicated that schisandrin B significantly prevented D-GalN‑induced oxidative damage in L02 cells (P<0.05), decreased GSH-Px and SOD activities (P<0.05), increased MDA content (P<0.05). Furthermore, schisandrin B inhibited D-GalN-induced apoptosis in L02 cells (P<0.05), regulated the expression of Bax and Bcl-2 (P<0.05). The results indicated that schisandrin B decreased the D-GalN-induced intracellular oxidative stress indexes generation, and inhibited the down-regulation of Bcl-2 and up-regulation of Bax induced by D-GalN. In conclusion, schisandrin B was shown to exert protective effect against oxidative damage of L02 cells, which, in part, was achieved by regulating the mRNA and protein levels of Bax and Bcl-2.

Allium sativum mitigates oxidative damages induced by Microcystin-LR in heart and liver tissues of mice

Microcystins (MCs) are hepatotoxic cyanotoxins implicated in several incidents of human and animal toxicity. Microcystin-(Lysine, Arginine) or MC-LR is the most toxic and encountered variant of MCs where oxidative stress plays a key role in its toxicity. This study investigated the oxidative damages induced in the liver and heart of Balb/C mice by an intraperitoneal injected acute dose of MC-LR. Thereafter, the potential protective effect of garlic (Allium sativum) extract supplementation against such damages was assessed through the evaluation of oxidative stress and cytotoxicity markers. Lipid peroxidation (LPO), carbonyl content (CC), glutathione content (GSH), alkaline phosphatase activity (ALP), lactate dehydrogenase (LDH) and sorbitol dehydrogenase (SDH) activities were measured. Results showed important oxidative damages in hepatic and cardiac cells of mice injected with the toxin. However, these damages have been significantly reduced in mice supplemented with garlic extract. Thus, this study demonstrated for the first time the effective use of garlic as an antioxidant agent against oxidative damages induced by MC-LR. As well, this study supports the use of garlic as a potential remedy against pathologies related to toxic agents.

Ethnopharmacological study of herbal remedies used for the management of thyroid disorders in Algeria

Traditional medicine is gaining an increasing importance in diseases management. Besides, thyroid disease is one of the common endocrine disorders spreading at high frequency worldwide. The present work is an ethnopharmacological study aiming to identify, document and analyze aromatic and medicinal plants used in Algerian traditional medicines for thyroid disorders management. Semi-structured interviews with 120 herbalists and traditional practitioners and rural dwellers were realized in eleven locations in Algeria throughout field studies achieved from June 2017 to July 2019. Results reveal the use of 63 medicinal plants belonging to 59 genera and 34 families. The most represented botanical families were Lamiaceae, Fabaceae, Apiaceae, Amaranthaceae and Asteraceae. However, the most cited plant species were Atriplex halimus L., Bunium incrassatum (Boiss.) Amo, Nigella sativa L., Aquilaria malaccensis Lam. and Saussurea costus (Falc.) Lipsch. These species are taken alone or in mixtures of two or more ingredients from different origins such as honey, olive oil, and goat milk. Our findings revealed new therapeutic uses of 60 medicinal plants that have not been previously reported for the treatment of thyroid in Algeria. This is the first study documenting the traditional uses based on herbal medicine for thyroid management in Algeria. Our findings are relevant in the search for novel drug discovery. Obviously, it is the time to increase effective scientific studies on mechanisms of action of these medicinal plants in order to validate their popular usages.

Antioxidant responses of triangle sail mussel Hyriopsis cumingii exposed to toxic Microcystis aeruginosa and thermal stress

Harmful algal blooms (HABs) and thermal stress as climate changes become more common in global water ecosystem, especially under eutrophic habitats. Here our study examined the combined impacts of bloom forming cyanobacteria Microcystis aeruginosa and thermal stress on the antioxidant responses of the ecologically important species triangle sail mussel Hyriopsis cumingii. The differential responses of a series of enzymes, e.g. superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), as well as signal metabolites including reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione (GSH) involved in antioxidant defense mechanisms were analyzed during 14 d exposure to toxic cyanobacterium M. aeruginosa and 7 d depuration period. The activities of SOD and GPx as well as the content of ROS and MDA in H. cumingii increased, while CAT activity reduced due to M. aeruginosa exposure. Thermal stress resulted in decrease of CAT, the accumulation of GSH and the enhance of GST and SOD. Meanwhile, the interactive effects among M. aeruginosa, thermal stress and time were also observed on most parameters except for GST activity. The total amount of microcystins (MC) in sail mussels increased with concentrations of exposed M. aeruginosa, independently of the presence or absence of thermal stress. Although around 50% of MC in mussels dropped in the depuration period, most parameters showed alterations because of cyanobacteria exposure and thermal stress. Overall, these findings suggested that toxic cyanobacteria or thermal stress induces oxidative stress and severely affects the enzymes activities and intermediates level associated with antioxidant defense mechanisms in sail mussels respectively. More importantly, the toxic impacts on sail mussels could be intensified by their combination.

Vitamin C Protects Porcine Oocytes From Microcystin-LR Toxicity During Maturation

Microcystin-leucine arginine (MC-LR) is the most toxic cyanotoxin found in water bodies. Microcystins are produced as secondary products of cyanobacteria metabolism. They have a stable structure, and can bioaccumulate in living organisms. Humans and livestock who drink fresh water containing MC-LR can be poisoned. However, few studies have reported the effects of MC-LR exposure on livestock or human reproduction. In this study, we used porcine oocytes as a model to explore the effects of MC-LR on oocyte maturation, and studied the impact of vitamin C (VC) administration on MC-LR-induced meiosis defects. Exposure to MC-LR significantly restricted cumulus cell expansion and decreased first polar body extrusion. Further studies showed that MC-LR exposure led to meiosis arrest by disturbing cytoskeleton dynamics with MC-LR exposed oocytes displaying aberrant spindle organization, low levels of acetylate α-tubulin, and disturbed actin polymerization. Additionally, MC-LR exposure impaired cytoplasmic maturation by inducing mitochondria dysfunction. Moreover, MC-LR also produced abnormal epigenetic modifications, and induced high levels of oxidative stress, caused DNA damage and early apoptosis. The administration of VC provided partial protection from all of the defects observed in oocytes exposed to MC-LR. These results demonstrate that MC-LR has a toxic effect on oocyte meiosis through mitochondrial dysfunction-induced ROS, DNA damage and early apoptosis. Supplementation of VC is able to protect against MC-LR-induced oocyte damage and represents a potential therapeutic strategy to improve the quality of MC-LR-exposed oocytes.

Getting an Early Start in Understanding Perinatal Asphyxia Impact on the Cardiovascular System

Perinatal asphyxia (PA) is a burdening pathology with high short-term mortality and severe long-term consequences. Its incidence, reaching as high as 10 cases per 1000 live births in the less developed countries, prompts the need for better awareness and prevention of cases at risk, together with management by easily applicable protocols. PA acts first and foremost on the nervous tissue, but also on the heart, by hypoxia and subsequent ischemia-reperfusion injury. Myocardial development at birth is still incomplete and cannot adequately respond to this aggression. Cardiac dysfunction, including low ventricular output, bradycardia, and pulmonary hypertension, complicates the already compromised circulatory status of the newborn with PA. Multiorgan and especially cardiovascular failure seem to play a crucial role in the secondary phase of hypoxic-ischemic encephalopathy (HIE) and its high mortality rate. Hypothermia is an acceptable solution for HIE, but there is a fragile equilibrium between therapeutic gain and cardiovascular instability. A profound understanding of the underlying mechanisms of the nervous and cardiovascular systems and a close collaboration between the bench and bedside specialists in these domains is compulsory. More resources need to be directed toward the prevention of PA and the consecutive decrease of cardiovascular dysfunction. Not much can be done in case of an unexpected acute event that produces PA, where recognition and prompt delivery are the key factors for a positive clinical result. However, the situation is different for high-risk pregnancies or circumstances that make the fetus more vulnerable to asphyxia. Improving the outcome in these cases is possible through careful monitoring, identifying the high-risk pregnancies, and the implementation of novel prenatal strategies. Also, apart from adequately supporting the heart through the acute episode, there is a need for protocols for long-term cardiovascular follow-up. This will increase our recognition of any lasting myocardial damage and will enhance our perspective on the real impact of PA. The goal of this article is to review data on the cardiovascular consequences of PA, in the context of an immature cardiovascular system, discuss the potential contribution of cardiovascular impairment on short and long-term outcomes, and propose further directions of research in this field.

Characterization of microcystin-induced apoptosis in HepG2 hepatoma cells

Microcystins (MCs) are a class of hepatotoxins that are commonly produced by freshwater cyanobacteria. MCs harm liver cells through inhibiting protein phosphatases 1 and 2A (PP1 and PP2A) and can produce dualistic effects, i.e., cell death and uncontrolled cellular proliferation. The induction of programmed cell death, i.e., apoptosis, in MC treated hepatic cells has been described previously; however, its exact pathway remains unclear. To address this, HepG2 human hepatoma cells were exposed to MC-LR, the most prevalent isomer of MCs, and morphological and physiological responses were examined. Microscopy and Alamar Blue assay showed that HepG2 cells responded to MC-LR treatment with apoptosis characteristics, such as clumping and shrinking of cells and detachment from the monolayer culture surface. A fluorescent caspase activation assay further revealed activation of all tested apoptosis-dependent caspases (i.e., caspase-3/7, 8 and 9) after 24 h of MC-LR treatment. Furthermore, caspase-8 was found being activated 4 h after MC-LR treatment, earlier than observed activation of caspase-9 (8 h after MC-LR treatment). These data demonstrated that MC-LR can induce apoptosis of HepG2 cells through both extrinsic and intrinsic pathways and that the extrinsic pathway may be activated before the intrinsic pathway. This indicates that extrinsic pathway is more sensitive than intrinsic pathway in MC induced apoptosis. This knowledge contributes to a better understanding of MC hepatotoxicity and can be further used for developing treatments for MC exposed hepatic cells.