Maresin 1, a Proresolving Lipid Mediator, Mitigates Carbon Tetrachloride-Induced Liver Injury in Mice

Host Response Modulation Therapy in the Diabetes Mellitus—Periodontitis Conjuncture: A Narrative Review

The inflammatory response of the host in periodontitis is the phenomenon that underlies the onset and evolution of periodontal destructive phenomena. A number of systemic factors, such as diabetes mellitus (DM), can negatively affect the patient with periodontitis, just as the periodontal disease can aggravate the status of the DM patient. Host response modulation therapy involves the use of anti-inflammatory and anti-oxidant products aimed at resolving inflammation, stopping destructive processes, and promoting periodontal healing, all important aspects in patients with high tissue loss rates, such as diabetic patients. This paper reviews the data available in the literature on the relationship between DM and periodontitis, the main substances modulating the inflammatory response (nonsteroidal anti-inflammatory drugs, sub-antimicrobial doses of doxycycline, or omega-3 fatty acids and their products, specialized pro-resolving mediators), as well as their application in diabetic patients.

Maresin-1 and Inflammatory Disease

Inflammation is an essential action to protect the host human body from external, harmful antigens and microorganisms. However, an excessive inflammation reaction sometimes exceeds tissue damage and can disrupt organ functions. Therefore, anti-inflammatory action and resolution mechanisms need to be clarified. Dietary foods are an essential daily lifestyle that influences various human physiological processes and pathological conditions. Especially, omega-3 fatty acids in the diet ameliorate chronic inflammatory skin diseases. Recent studies have identified that omega-3 fatty acid derivatives, such as the resolvin series, showed strong anti-inflammatory actions in various inflammatory diseases. Maresin-1 is a derivative of one of the representative omega-3 fatty acids, i.e., docosahexaenoic acid (DHA), and has shown beneficial action in inflammatory disease models. In this review, we summarize the detailed actions of maresin-1 in immune cells and inflammatory diseases.

Maresins: The Mainstay in Periodontal Resolution

Not much was known about the resolution of inflammation until the recent past when significant breakthroughs led to the unveiling of the exact mechanism of this. It is now known that the resolution of inflammation involves specific mediators of resolution such as lipoxins, protectins, resolvins, and maresins, making it an active process. Of these mediators, maresins are the latest discovery. Maresins are macrophage-derived mediators that are involved in the resolution of inflammation. Various studies on what maresins do to resolve periodontitis are ongoing. Reportedly, maresins help in periodontal regeneration and wound healing. Having known the numerous roles of these mediators, our current focus is shifting from anti-inflammatory pharmacotherapy to resolution pharmacotherapy.

In Vitro and In Vivo Protective Effects of Lentil (Lens culinaris) Extract against Oxidative Stress-Induced Hepatotoxicity

Excessive oxidative stress plays a role in hepatotoxicity and the pathogenesis of hepatic diseases. In our previous study, the phenolic extract of beluga lentil (BLE) showed the most potent in vitro antioxidant activity among extracts of four common varieties of lentils; thus, we hypothesized that BLE might protect liver cells against oxidative stress-induced cytotoxicity. BLE was evaluated for its protective effects against oxidative stress-induced hepatotoxicity in AML12 mouse hepatocytes and BALB/c mice. H₂O₂ treatment caused a marked decrease in cell viability; however, pretreatment with BLE (25-100 μg/mL) for 24 h significantly preserved the viability of H₂O₂-treated cells up to about 50% at 100 μg/mL. As expected, BLE dramatically reduced intracellular reactive oxygen species (ROS) levels in a dose-dependent manner in H₂O₂-treated cells. Further mechanistic studies demonstrated that BLE reduced cellular ROS levels, partly by increasing expression of antioxidant genes. Furthermore, pretreatment with BLE (400 mg/kg) for 2 weeks significantly reduced serum levels of alanine transaminase and triglyceride by about 49% and 40%, respectively, and increased the expression and activity of glutathione peroxidase in CCl₄-treated BALB/c mice. These results suggest that BLE protects liver cells against oxidative stress, partly by inducing cellular antioxidant system; thus, it represents a potential source of nutraceuticals with hepatoprotective effects.

Antioxidant activity and protective effect of propolis against carbon tetrachloride-induced liver and kidney injury by modulation of oxidative parameters

Background and Aim:

Propolis has a protective effect against cellular damage caused by toxic agents such as drugs, metals, xenobiotics, and chemicals. The aim of this study was to investigate the antioxidant activity and the effect of ethanolic extract of propolis on carbon tetrachloride (CCl4)-induced oxidative stress on kidney and liver injury in rat.

Materials and Methods:

The study quantified phenol, flavone, and flavonol in propolis and assessed antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and molybdate. The investigators used four groups of rats to study the effect of propolis on CCl₄-induced toxicity. Propolis extract was given orally (500 mg/kg) for 12 days, and CCl_{4 (}1 mL/kg) was administered intraperitoneally on day 5 of the experiment. Blood and tissue samples of the liver and kidney were collected on day 13 to measure biochemical and oxidative parameters. The parameters included malondialdehyde (MDA), protein carbonyl formation (PCO), advanced oxidation protein products (AOPP), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and ascorbic acid (AA). Biochemical parameters included liver enzymes, blood urea (BU), creatinine, and uric acid (UA).

Results:

CCl₄ decreased antioxidant agents, including CAT, GPx, GSH, and AA in the liver and kidney tissues. The oxidative agents’ levels, including MDA, PCO, and AOPP, increased by CCl₄ compared to the control group. CCl₄ increased liver enzymes, UA, BU, and creatinine in the blood samples. Propolis significantly alleviated liver and kidney function, improved antioxidant parameters, and decreased levels of oxidative agents.

Conclusion:

The data showed for the 1^st time that Moroccan propolis has a protective effect against CCl₄-induced kidney and liver toxicity by maintaining the activity of the antioxidant defense system, which was most likely due to its antioxidant activity.

Maresin-1 Prevents Liver Fibrosis by Targeting Nrf2 and NF-κB, Reducing Oxidative Stress and Inflammation

Liver fibrosis is a complex process characterized by the excessive accumulation of extracellular matrix (ECM) and an alteration in liver architecture, as a result of most types of chronic liver diseases such as cirrhosis, hepatocellular carcinoma (HCC) and liver failure. Maresin-1 (MaR1) is derivative of ω-3 docosahexaenoic acid (DHA), which has been shown to have pro-resolutive and anti-inflammatory effects. We tested the hypothesis that the application of MaR1 could prevent the development of fibrosis in an animal model of chronic hepatic damage. Sprague-Dawley rats were induced with liver fibrosis by injections of diethylnitrosamine (DEN) and treated with or without MaR1 for four weeks. In the MaR1-treated animals, levels of AST and ALT were normalized in comparison with DEN alone, the hepatic architecture was improved, and inflammation and necrotic areas were reduced. Cell proliferation, assessed by the mitotic activity index and the expression of Ki-67, was increased in the MaR1-treated group. MaR1 attenuated liver fibrosis and oxidative stress was induced by DEN. Plasma levels of the pro-inflammatory mediators TNF-α and IL-1β were reduced in MaR1-treated animals, whereas the levels of IL-10, an anti-inflammatory cytokine, increased. Interestingly, MaR1 inhibited the translocation of the p65 subunit of NF-κB, while increasing the activation of Nrf2, a key regulator of the antioxidant response. Finally, MaR1 treatment reduced the levels of the pro-fibrotic mediator TGF-β and its receptor, while normalizing the hepatic levels of IGF-1, a proliferative agent. Taken together, these results suggest that MaR1 improves the parameters of DEN-induced liver fibrosis, activating hepatocyte proliferation and decreasing oxidative stress and inflammation. These results open the possibility of MaR1 as a potential therapeutic agent in fibrosis and other liver pathologies.

Path4Drug: Data Science Workflow for Identification of Tissue-Specific Biological Pathways Modulated by Toxic Drugs

The early prediction of drug adverse effects is of great interest to pharmaceutical research, as toxicity is one of the leading reasons for drug attrition. Understanding the cell signaling and regulatory pathways affected by a drug candidate is crucial to the study of drug toxicity. In this study, we present a computational technique that employs the propagation of drug-protein interactions to connect compounds to biological pathways. Target profiles for drugs were built by retrieving drug target proteins from public repositories such as ChEMBL, DrugBank, IUPHAR, PharmGKB, and TTD. Subsequent enrichment test of the protein pool using Reactome revealed potential pathways affected by the drugs. Furthermore, an optional tissue filter utilizing the Human Protein Atlas was applied to identify tissue-specific pathways. The analysis pipeline was implemented in an open-source KNIME workflow called Path4Drug to allow automated data retrieval and reconstruction for any given drug present in ChEMBL. The pipeline was applied to withdrawn drugs and cardio- and hepatotoxic drugs with black box warnings to identify biochemical pathways they affect and to find pathways that can be potentially connected to the toxic events. To complement this approach, drugs used in cardiac therapy without any record of toxicity were also analyzed. The results provide already known associations as well as a large amount of additional potential connections. Consequently, our approach can link drugs to biological pathways by leveraging big data available in public resources. The developed tool is openly available and modifiable to support other systems biology analyses.

N-3 Polyunsaturated Fatty Acids and Their Lipid Mediators as A Potential Immune-Nutritional Intervention: A Molecular and Clinical View in Hepatic Disease and Other Non-Communicable Illnesses

In recent years, the beneficial effect of n-3 polyunsaturated fatty acids (n-3 PUFAs) intake on human health has been widely accepted in the field of immunonutrition. Today, we find a diversity of supplements based on n-3 PUFAs and/or minerals, vitamins and other substances. The main objective of this review is to discuss the importance of n-3 PUFAs and their derivatives on immunity and inflammatory status related to liver disease and other non-communicable illnesses. Based on the burden of liver diseases in 2019, more than two million people die from liver pathologies per year worldwide, because it is the organ most exposed to agents such as viruses, toxins and medications. Consequently, research conducted on n-3 PUFAs for liver disease has been gaining prominence with encouraging results, given that these fatty acids have anti-inflammatory and cytoprotective effects. In addition, it has been described that n-3 PUFAs are converted into a novel species of lipid intermediaries, specialized pro-resolving mediators (SPMs). At specific levels, SPMs improve the termination of inflammation as well as the repairing and regeneration of tissues, but they are deregulated in liver disease. Since evidence is still insufficient to carry out pharmacological trials to benefit the resolution of acute inflammation in non-communicable diseases, there remains a call for continuing preclinical and clinical research to better understand SPM actions and outcomes.

Protective Role of 4-Octyl Itaconate in Murine LPS/D-GalN-Induced Acute Liver Failure via Inhibiting Inflammation, Oxidative Stress, and Apoptosis

Oxidative stress, inflammation, and apoptosis are crucial in the pathogenesis of acute liver failure (ALF). 4-Octyl itaconate (OI) showed antioxidative and anti-inflammatory properties in many disease models. However, its role in lipopolysaccharide- (LPS-)/D-galactosamine- (D-GalN-) induced ALF is still not investigated. Here, we established an ALF murine model induced by LPS/D-GalN administration. And we found that OI improved survival rate in the murine ALF model. Our results also showed that OI alleviated LPS/D-GalN-induced hepatic histopathological injury and reduced the serum activities of alanine transaminase and aspartate transaminase. Moreover, OI reduced serum levels of proinflammatory cytokines such as monocyte chemotactic protein-1, tumor necrosis factors-α, and interlukin-6. Additionally, OI mitigated oxidative stress and alleviated lipid peroxidation in a murine model of ALF. This was evaluated by a reduction of thiobarbituric acid reactive substances (TBARS) in liver tissues. In addition, OI increased the ratio of reduced glutathione/oxidized glutathione and the activities of antioxidant enzymes including catalase and superoxide dismutase. Moreover, the apoptosis of hepatocytes in the liver was inhibited by OI. Furthermore, we found that OI inhibited LPS-induced nuclear translocation and activation of factor-kappa B (NF-κB) p65 in macrophages which could be inhibited by OI-induced activation of nuclear factor erythroid-2-related factor (Nrf2) signaling. Additionally, D-GalN-induced reactive oxygen species (ROS) generation and apoptosis in hepatocytes were inhibited by OI-induced activation of Nrf2 signaling. Therefore, the underlying mechanism for OI's protective effect in LPS/D-GalN-induced ALF may be associated with deactivation of NF-κB signaling in macrophages to reduce inflammation and inhibition of ROS-related hepatocyte apoptosis by activating Nrf2. In conclusion, OI showed a protective role in LPS/D-GalN-induced ALF by reducing inflammation, enhancing antioxidant capacity, and inhibiting cell apoptosis.

4-OI Attenuates Carbon Tetrachloride-Induced Hepatic Injury via Regulating Oxidative Stress and the Inflammatory Response

The liver is an important metabolic organ, and acute liver injury (ALI) is potentially lethal. Itaconate, a metabolic intermediate from the tricarboxylic acid cycle, showed emerging anti-oxidative and anti-inflammation properties, and an accumulating protective effect in multiple diseases, but its role in ALI still needs to be further explored. Here we established an ALI model induced by carbon tetrachloride in mice. Our results showed that 4-Octyl itaconate (OI), a derivate of itaconate, mitigated hepatic damage by improving liver function, reducing histopathological damage, and decreasing the death of hepatocytes. Additionally, OI decreased myeloperoxidase and thiobarbituric acid reactive substances (TBARS) levels in the ALI model. OI also inhibited the inflammatory response by reducing pro-inflammatory cytokine secretion (IL-6, TNF-α, IL-1β, and MCP-1) and infiltration of macrophages and neutrophils in the ALI model. However, administration of ML385, a specified Nrf2 inhibitor, eliminated the protective properties of OI in the CCl4-induced liver injury model by increasing hepatic damage and oxidative stress. Furthermore, OI increased the expression and nuclear translocation of Nrf2 and elevated the expression of heme oxygenase-1 and NAD(P)H quinone oxidoreductase 1, while knockdown of Nrf2 eliminated these effects in murine hepatocyte NCTC 1469 under CCl4 treatment. Moreover, we found that OI reduced serum High-mobility group box 1 (HMGB1) levels in CCl4-treated mice. Finally, OI inhibited nuclear translocation of factor-kappa B (NF-𝜅B) and inflammatory cytokine production in murine macrophages. In conclusion, these results indicated that OI ameliorated CCl4-induced ALI by mitigating oxidative stress and the inflammatory response. The possible mechanism was associated with the elevation of Nrf2 nuclear translocation and inhibition of HMGB1 mediated the nuclear translocation of NF-𝜅B.

Review on Auricularia auricula-judae as a Functional Food: Growth, Chemical Composition, and Biological Activities

Although the application of Auricularia auricula-judae (AAJ) for health purposes has a long tradition in Asia, there is a lack of research on the functional nutrition of AAJ; the current research focused on polysaccharides has been too unitary compared to other mushrooms in recent years. Identification, extraction, and large-scale production of biologically active substances have emerged as critical determinants that determine AAJ becoming a functional food. AAJ is being treated in a restrained manner, despite having significant potential as a drug or a source of pure bioactive substances. Functional ingredients of mushrooms and AAJ have emerged as a new impetus for researchers interested in developing functional foods. This review presents an overview of current studies relevant to nutrition and the application of AAJ. The physiological conditions of AAJ and the corresponding functional ingredients beneficial to human health are reviewed to better understand the function and mechanisms of different nutrient contents. Relevant methods for evaluating the efficiency of extraction are also summarized. Finally, current limitations and the future scope for functional ingredients of AAJ are identified and discussed.

Novel Antioxidant, Deethylated Ethoxyquin, Protects against Carbon Tetrachloride Induced Hepatotoxicity in Rats by Inhibiting NLRP3 Inflammasome Activation and Apoptosis

Inflammation and an increase in antioxidant responses mediated by oxidative stress play an important role in the pathogenesis of acute liver injury (ALI). We utilized in silico prediction of biological activity spectra for substances (PASS) analysis to estimate the potential biological activity profile of deethylated ethoxyquin (DEQ) and hypothesized that DEQ exhibits antioxidant and anti-inflammatory effects in a rat model of carbon tetrachloride (CCl₄)-induced ALI. Our results demonstrate that DEQ improved liver function which was indicated by the reduction of histopathological liver changes. Treatment with DEQ reduced CCl₄-induced elevation of gene expression, and the activity of antioxidant enzymes (AEs), as well as the expression of transcription factors Nfe2l2 and Nfkb2. Furthermore, DEQ treatment inhibited apoptosis, downregulated gene expression of pro-inflammatory cytokines (Tnf and Il6), cyclooxygenase 2 (Ptgs2), decreased glutathione (GSH) level and myeloperoxidase (MPO) activity in rats with ALI. Notably, DEQ treatment led to an inhibition of CCl₄-induced NLRP3-inflammasome activation which was indicated by the reduced protein expression of IL-1β, caspase-1, and NLRP3 in the liver. Our data suggest that DEQ has a hepatoprotective effect mediated by redox-homeostasis regulation, NLRP3 inflammasome, and apoptosis inhibition, which makes that compound a promising candidate for future clinical studies.

Maresin 1 attenuates pro-inflammatory activation induced by β-amyloid and stimulates its uptake

Alzheimer's disease (AD) is the most common dementia, characterized by pathological accumulation of β‐amyloid (Aβ) and hyperphosphorylation of tau protein, together with a damaging chronic inflammation. The lack of effective treatments urgently warrants new therapeutic strategies. Resolution of inflammation, associated with beneficial and regenerative activities, is mediated by specialized pro‐resolving lipid mediators (SPMs) including maresin 1 (MaR1). Decreased levels of MaR1 have been observed in AD brains. However, the pro‐resolving role of MaR1 in AD has not been fully investigated. In the present study, human monocyte‐derived microglia (MdM) and a differentiated human monocyte cell line (THP‐1 cells) exposed to Aβ were used as models of AD neuroinflammation. We have studied the potential of MaR1 to inhibit pro‐inflammatory activation of Aβ and assessed its ability to stimulate phagocytosis of Aβ₄₂. MaR1 inhibited the Aβ₄₂‐induced increase in cytokine secretion and stimulated the uptake of Aβ₄₂ in both MdM and differentiated THP‐1 cells. MaR1 was also found to decrease chemokine secretion and reduce the associated increase in the activation marker CD40. Activation of kinases involved in transduction of inflammation was not affected by MaR1, but the activity of nuclear factor (NF)‐κB was decreased. Our data show that MaR1 exerts effects that indicate a pro‐resolving role in the context of AD and thus presents itself as a potential therapeutic target for AD.

Tert-butylhydroquinone mitigates Carbon Tetrachloride induced Hepatic Injury in mice

Tert-butylhydroquinone (tBHQ) is an antioxidant compound that exhibits cytoprotective effect in many tissues under pathological condition. However, its role in carbon tetrachloride (CCL4) induced liver injury is still unclear. Here we established a carbon tetrachloride induced hepatic injury model in mice to determine whether tBHQ can mitigate CCL4 induced liver damage. In our study, we found tBHQ exhibited protective effects in CCL4 treated mice model. TBHQ markedly improved hepatic function and decreased hepatic histopathological damage in vivo. In addition, tBHQ reduced levels of pro-inflammatory cytokines in mice model. Moreover, tBHQ mitigated apoptosis of hepatocytes, oxidative stress and lipid peroxidation in vivo and in vitro. We also found the possible mechanism of protective effects of tBHQ was associated with activation of Nrf2/ heme oxygenase-1 (HO-1) pathway. In conclusion, our study revealed tBHQ can be a potential therapeutic drug in treatment of acute hepatic injury.

Itaconate: A Metabolite Regulates Inflammation Response and Oxidative Stress

Metabolic products can lead to crucial biological function alterations. Itaconate is probably the best example of how a metabolic process can be diverted to generate an immunomodulator effect in macrophages. Through inflammatory stimuli, such as lipopolysaccharide, the immune response gene 1 is activated and promotes the production of itaconate from the tricarboxylic acid cycle by decarboxylating cis-aconitate. Itaconate has been reported to have multiple immunoregulatory and antioxidative effects. In addition, reports have described its antibacterial and protumor effects. The involved mechanism in these effects includes the activation of nuclear factor E2-related factor 2 by alkylation of Kelch-like ECH-associated protein 1, inhibition of aerobic glycolysis by targeting glyceraldehyde-3-phosphate dehydrogenase and fructose-bisphosphate aldolase A, inhibition of succinate dehydrogenase, and blockade of IκBζ translation. All of these discoveries elucidated the transformation of the pro- into anti-inflammatory status in macrophages, which is crucial in innate immunity and set the ground for the emerging therapeutic implications of itaconate. In this review, we point out that itaconate is a novel and pivotal metabolic determinant of the immunoregulatory response in macrophages and highlight studies that have improved our understanding of the connection between the immune response and metabolism. In addition, we shed light on the therapeutic potential of itaconate and its derivatives to treat inflammatory diseases.

Maresin 1, a Proresolving Lipid Mediator, Ameliorates Liver Ischemia-Reperfusion Injury and Stimulates Hepatocyte Proliferation in Sprague-Dawley Rats

Maresin-1 (MaR1) is a specialized pro-resolving mediator, derived from omega-3 fatty acids, whose functions are to decrease the pro-inflammatory and oxidative mediators, and also to stimulate cell division. We investigated the hepatoprotective actions of MaR1 in a rat model of liver ischemia-reperfusion (IR) injury. MaR1 (4 ng/gr body weight) was administered prior to ischemia (1 h) and reperfusion (3 h), and controls received isovolumetric vehicle solution. To analyze liver function, transaminases levels and tissue architecture were assayed, and serum cytokines TNF-α, IL-6, and IL-10, mitotic activity index, and differential levels of NF-κB and Nrf-2 transcription factors, were analyzed. Transaminase, TNF-α levels, and cytoarchitecture were normalized with the administration of MaR1 and associated with changes in NF-κB. IL-6, mitotic activity index, and nuclear translocation of Nrf-2 increased in the MaR1-IR group, which would be associated with hepatoprotection and cell proliferation. Taken together, these results suggest that MaR1 alleviated IR liver injury, facilitated by the activation of hepatocyte cell division, increased IL-6 cytokine levels, and the nuclear localization of Nrf-2, with a decrease of NF-κB activity. All of them were related to an improvement of liver injury parameters. These results open the possibility of MaR1 as a potential therapeutic tool in IR and other hepatic pathologies.

Protective effects of maresin 1 against inflammation in experimentally induced acute pancreatitis and related lung injury

Severe acute pancreatitis (SAP) is an inflammatory disorder that progresses with local and systemic difficulties accompanied by a relatively high mortality rate. In recent years, maresin 1 (MaR1) has been shown to be a macrophage mediator with effective proresolving and anti-inflammatory properties that prevents the occurrence of various inflammatory conditions. The purpose of this study was to investigate the role of MaR1 in SAP and related lung injury. Experimental SAP was induced in mice with a combination of cerulean and lipopolysaccharide. MaR1 was administered 30 min before the primary injection of cerulean. Biochemical markers and histological injury scores were used to evaluate the severity of acute pancreatitis. To determine the degree of inflammation, serum cytokines and myeloperoxidase activity in pancreas and lung tissues were measured. Western blot analysis detected the activation of NF-κB. After MaR1 pretreatment, the activities of amylase, lipase, TNF-α, IL-1β, and IL-6 were decreased in serum, and the myeloperoxidase activity both in pancreas and in lung tissues significantly decreased, whereas the activity of anti-inflammatory cytokine IL-10 in serum was increased. MaR1-pretreated mice reduced the activation of pancreatic NF-κB and decreased the severity of pancreatic and lung-related injuries. These results confirm that MaR1 alleviated inflammation of the pancreas and lung by inhibiting the activity of NF-κB in experimentally induced acute pancreatitis and exerted anti-inflammatory effects. These findings suggest that MaR1 could be a new and useful drug in the treatment of SAP.NEW & NOTEWORTHY These results provided us evidence to confirm that maresin 1 (MaR1) can alleviate inflammation of the pancreas and lung by inhibiting the activity of NF-κB in experimental induced acute pancreatitis and exerts certain anti-inflammatory effects. These findings suggest that MaR1 could be a new and useful drug in the treatment of severe acute pancreatitis.

Proresolving Lipid Mediators: Endogenous Modulators of Oxidative Stress

Specialized proresolving mediators (SPMs) are a novel class of endogenous lipids, derived by ω-6 and ω-3 essential polyunsaturated fatty acids such as arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) that trigger and orchestrate the resolution of inflammation, which is the series of cellular and molecular events that leads to spontaneous regression of inflammatory processes and restoring of tissue homeostasis. These lipids are emerging as highly effective therapeutic agents that exert their immunoregulatory activity by activating the proresolving pathway, as reported by a consistent bulk of evidences gathered in the last two decades since their discovery. The production of reactive oxygen (ROS) and nitrogen (RNS) species by immune cells plays indeed an important role in the inflammatory mechanisms of host defence, and it is now clear that oxidative stress, viewed as an imbalance between such species and their elimination, can lead to many chronic inflammatory diseases. This review, the first of its kind, is aimed at exploring the manifold effects of SPMs on modulation of reactive species production, along with the mechanisms through which they either inhibit molecular signalling pathways that are activated by oxidative stress or induce the expression of endogenous antioxidant systems. Furthermore, the possible role of SPMs in oxidative stress-mediated chronic disorders is also summarized, suggesting not only that their anti-inflammatory and proresolving properties are strictly associated with their antioxidant role but also that these endogenous lipids might be exploited in the treatment of several pathologies in which uncontrolled production of ROS and RNS or impairment of the antioxidant machinery represents a main pathogenetic mechanism.

Maresin 1 mitigates renal ischemia/reperfusion injury in mice via inhibition of the TLR4/MAPK/NF-κB pathways and activation of the Nrf2 pathway

BACKGROUND

Inflammation and oxidative stress play a crucial role in the pathogenesis of renal ischemia/reperfusion injury (IRI). Maresin 1 (MaR1), which has shown strong anti-inflammatory and antioxidant effects, was recently reported to have protective properties in several different animal models.

AIM

The objectives of our study were to determine whether MaR1 alleviates renal IRI and to identify the underlying mechanisms.

MATERIALS AND METHODS

The mouse model in this study was induced by ischemia of the left kidney for 45 minutes and by nephrectomy of the right kidney. All mice were intravenously injected with a vehicle or MaR1. Renal histopathologic changes, function, proinflammatory cytokines, and oxidative stress were assessed. The expression of proteins was measured by Western blot.

RESULTS

The results indicated that MaR1 markedly protected against renal IRI. The protective effects were accompanied by the reduction of histologic changes and reduction of renal dysfunction. Meanwhile, MaR1 remarkably mitigated renal IRI-induced inflammation and oxidative stress. In addition, our results showed that MaR1 significantly inhibited the expression of TLR4 and the expression of phosphorylated Erk, JNK, and P38. Furthermore, MaR1 decreased the nuclear translocation of NF-κB and increased the nuclear translocation of Nrf2.

CONCLUSION

MaR1 protects against renal IRI by inhibiting the TLR4/MAPK/NF-κB pathways, which mediate anti-inflammation, and by activating the Nrf2 pathway, which mediates antioxidation.

Maresin1 Alleviates Metabolic Dysfunction in Septic Mice: A 1H NMR-Based Metabolomics Analysis

Maresin1 (MaR1), a new anti-inflammatory and proresolving lipid mediator, has been proven to exert organ-protective effects in septic animal models. However, the potential mechanisms are still not fully elucidated. In this study, we sought to explore the impact of MaR1 on metabolic dysfunction in cecal ligation and puncture- (CLP-) induced septic mice. We found that MaR1 significantly increased the overall survival rate and attenuated lung and liver injuries in septic mice. In addition, MaR1 markedly reduced the levels of proinflammatory cytokines (TNF-α and IL-6) and alleviated mitochondrial damage. Based on a ¹H NMR-based metabolomics analysis, CLP-induced septic mice had increased levels of acetate, pyruvate, and lactate in serum and decreased levels of alanine, aspartate, glutamate, and fumarate in lungs. However, these metabolic disorders, mainly involving energy and amino acid metabolism, can be recovered by MaR1 treatment. Therefore, our results suggest that the protective effects of MaR1 on sepsis could be related to the recovery of metabolic dysfunction and the alleviation of inflammation and mitochondrial damage.

Downregulation of Glt25d1 aggravates carbon tetrachloride‑induced acute hepatic injury through activation of the TGF‑β1/Smad2 signaling pathway

Collagen β (1-O) galactosyltransferase 1 (GLT25D1) has been reported to transfer galactose to hydroxylysine residues via β (1-O) linkages in collagen. The present study investigated the function of the collagen galactosyltransferase activity of GLT25D1 against carbon tetrachloride (CCl₄)-induced acute liver injury in vitro. Glt25d1^+/− mice and wild-type (WT) mice were injected intraperitoneally with the same dose of CCl₄. The grade of hepatic injury and the extent of hepatocyte necrosis in the acute phase were assessed 48 h following CCl₄ injection. Hepatocyte necrosis was evaluated by histological examination and by serum alanine aminotransferase and aspartate aminotransferase levels, which were higher in the Glt25d1^+/− mice compared with those in the WT mice. Reverse transcription-quantitative polymerase chain reaction was performed, and the results demonstrated that the mRNA expression levels of inflammatory cytokines, including tumor necrosis factor-α and interleukin-6 were significantly increased in the Glt25d1^+/− mice. Furthermore, western blot analyses were performed, and the results demonstrated that the protein levels of cleaved caspase-3 and −9 were also markedly increased in the Glt25d1^+/− liver, indicating that hepatocyte apoptosis was induced. Additionally, the expression levels of transforming growth factor (TGF)-β1 and phosphorylated small mothers against decapentaplegic (Smad)2 were markedly upregulated, indicating activation of the TGF-β1/Smad2 signaling pathway during CCl₄-induced acute liver injury in Glt25d1^+/− mice. CCl₄ administration also resulted in severe damage to Glt25d1^+/− primary hepatocytes in vitro. Taken together, the downregulation of Glt25d1 deteriorated CCl₄-induced liver injury in mice, which may involve triggering inflammatory responses, apoptosis and TGF-β1/Smad2 signaling pathway activation.

[Advances in macrophage function and its anti-inflammatory and proresolving activity and role in periodontitis development]

Macrophage plays an important role in human innate immune system. It has powerful functions, such as recognition, phagocytosis, and bacteria and foreign body removal. Periodontitis, which is a chronic infectious disease characterized by gum inflammation and bone loss, is a major cause of tooth loss in adults. Several studies demonstrated that periodontal tissue destruction is caused by the host immune response defending against infections. As an important part of host immune response, macrophage is also involved in periodontitis pathogenesis. Recently, anti-inflammatory and proresolving activities of macrophage was discovered. Thus, the complex function of macrophage in the occurrence, development, and resolution of inflammation and its potential role in periodontitis were reviewed.

Maresin 1 Ameliorates Lung Ischemia/Reperfusion Injury by Suppressing Oxidative Stress via Activation of the Nrf-2-Mediated HO-1 Signaling Pathway

Lung ischemia/reperfusion (I/R) injury occurs in various clinical conditions and heavily damaged lung function. Oxidative stress reaction and antioxidant enzymes play a pivotal role in the etiopathogenesis of lung I/R injury. In the current study, we investigated the impact of Maresin 1 on lung I/R injury and explored the possible mechanism involved in this process. MaR 1 ameliorated I/R-induced lung injury score, wet/dry weight ratio, myeloperoxidase, tumor necrosis factor, bronchoalveolar lavage fluid (BALF) leukocyte count, BALF neutrophil ratio, and pulmonary permeability index levels in lung tissue. MaR 1 significantly reduced ROS, methane dicarboxylic aldehyde, and 15-F2t-isoprostane generation and restored antioxidative enzyme (superoxide dismutase, glutathione peroxidase, and catalase) activities. Administration of MaR 1 improved the expression of nuclear Nrf-2 and cytosolic HO-1 in I/R-treated lung tissue. Furthermore, we also found that the protective effects of MaR 1 on lung tissue injury and oxidative stress were reversed by HO-1 activity inhibitor, Znpp-IX. Nrf-2 transcription factor inhibitor, brusatol, significantly decreased MaR 1-induced nuclear Nrf-2 and cytosolic HO-1 expression. In conclusion, these results indicate that MaR 1 protects against lung I/R injury through suppressing oxidative stress. The mechanism is partially explained by activation of the Nrf-2-mediated HO-1 signaling pathway.

Maresin 1 inhibits transforming growth factor-β1-induced proliferation, migration and differentiation in human lung fibroblasts

The myofibroblast has been implicated to be an important pathogenic cell in all fibrotic diseases, through synthesis of excess extracellular matrix. Lung fibroblast migration, proliferation and differentiation into a myofibroblast-like cell type are regarded as important steps in the formation of lung fibrosis. In the present study, the effect of maresin 1 (MaR 1), a pro-resolving lipid mediator, on transforming growth factor (TGF)-β1-stimulated lung fibroblasts was investigated, and the underlying molecular mechanisms were examined. The results of the present study demonstrated that MaR 1 inhibited TGF-β1-induced proliferative and migratory ability, assessed using MTT and scratch wound healing assays. The TGF-β1-induced expression of α-smooth muscle actin (α-SMA) and collagen type I, the hallmarks of myofibroblast differentiation, was decreased by MaR 1 at the mRNA and protein levels, determined using the reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Immunofluorescence demonstrated that MaR 1 downregulated the TGF-β1-induced expression of α-SMA. In addition, phosphorylated mothers against decapentaplegic homolog 2/3 (Smad2/3) and extracellular signal-related kinases (ERK) 1/2 were upregulated in TGF-β1-induced lung fibroblasts, and these effects were attenuated by MaR 1 administration. In conclusion, the results of the present study demonstrated that MaR 1 inhibited the TGF-β1-induced proliferation, migration and differentiation of human lung fibroblasts. These observed effects may be mediated in part by decreased phosphorylation of Smad2/3 and ERK1/2 signaling pathways. Therefore, MaR 1 may be a potential therapeutic approach to lung fibrotic diseases.

2-Hydroxy-4-methoxy benzoic acid attenuates the carbon tetra chloride-induced hepatotoxicity and its lipid abnormalities in rats via anti-inflammatory and antioxidant mechanism

BACKGROUND AND AIM

Liver inflammation stimulates various inflammatory cytokines and initiates injury through oxidative stress. The aim of this study was to curtaile the liver injury through natural principles such as 2-hydroxy-4-methoxy benzoic acid (HMBA).

METHODS

The current study examines the hepatoprotective and lipid lowering effect of HMBA against carbon tetra chloride (CCl₄)-mediated liver toxicity in male Wistar rats.

RESULTS

The hepatoprotective effects of HMBA against CCl₄-induced liver damage, were evident from low serum transaminases activities, reduced hepatic lipid peroxidation and collagen content, restoration of total glutathione, and recouping of the inflammatory cytokines, such as TNF-α, IL-1β, IL-10, and IL-6 levels. Further it was found that the treatment of HMBA, significantly lowered (P<0.01) the levels of total cholesterol, triglycerides, free fatty acids and phospholipids in serum and liver. To investigate the mechanism behind the hepatoprotective and lipid lowering effect, the activities of heme oxygenase (HO1), and myeloperoxidase (MPO) were measured and expression levels were quantified through western blot following HMBA administration. The results showed that HMBA administration significantly decreased the activity of HO1 (P<0.001), and increased the activity of MPO (P<0.001); further similar finding was observed in western analysis. The hepatoprotective, lipid lowering and shifting key defensive enzyme activities are similar to that of standard drug such as N-acetylcysteine.

CONCLUSION

HMBA is competent of shielding liver from CCl₄-induced hepatotoxicity, and this is associated with the lipid lowering, inflammatory cytokine restoration and induction of defensive enzyme activities.

Maresin 1 Mitigates High Glucose-Induced Mouse Glomerular Mesangial Cell Injury by Inhibiting Inflammation and Fibrosis

Background. Inflammation and fibrosis are the important pathophysiologic processes in diabetic nephropathy (DN). Maresin 1 is a potential anti-inflammatory lipid mediator, which has displayed powerful proresolving activities. Aim. We determine whether maresin 1 has protective effect on mouse glomerular mesangial cells (GMCs) induced by high glucose. Methods. We cultured GMCs stimulated by high glucose and categorized as follows: normal glucose group (5.6 mmol/L), high glucose group (30 mmol/L), mannitol group, maresin 1 intervention group (1, 10, and 100 nmol/L), maresin 1 and normal glucose group, and the N-acetylcysteine (NAC) intervention group (10 μmol/L NAC). After 24 h, the expression of ROS, NLRP3, caspase-1, procaspase-1, IL-1β, and pro-IL-1β was detected by western-blot, RT-PCR, and immunofluorescence. After 48 h, the expression of TGF-β1 and FN was detected by RT-PCR and ELISA. Results. Compared with normal glucose group, the expression of ROS, NLRP3, caspase-1, IL-1β, TGF-β1, and FN increased in high glucose group (P < 0.05), but it decreased after the treatment of maresin 1 in different concentrations. On the contrary, the expression of procaspase-1 and pro-IL-1β protein was restrained by high glucose and enhanced by maresin 1 in a dose-dependent manner (P < 0.05). Conclusion. Maresin 1 can inhibit NLRP3 inflammasome, TGF-β1, and FN in GMCs; it may have protective effect on DN by mitigating the inflammation and early fibrosis.

Ciliary neurotrophic factor analogue aggravates CCl4-induced acute hepatic injury in rats

Ciliary neurotrophic factor (CNTF) and CNTF analogs were reported to have hepatoprotective effect and ameliorate hepatic steatosis in db/db or high-fat-diet-fed mice. Because hepatic steatosis and injury are also commonly induced by hepatotoxin, the aim of the present study is to clarify whether CNTF could alleviate hepatic steatosis and injury induced by carbon tetrachloride (CCl₄). Unexpectedly, when combined with CCl₄, CNTF aggravated hepatic steatosis and liver injury. The mechanism is associated with effects of CNTF that inhibited lipoprotein secretion and drastically impaired the ability of lipoproteins to act as transport vehicles for lipids from the liver to the circulation. While injected after CCl₄ cessation, CNTF could improve liver function. These data suggest that CNTF could be a potential hepatoprotective agent against CCl₄-induced hepatic injury after the cessation of CCl₄ exposure. However, it is forbidden to combine recombinant mutant of human CNTF treatment with CCl₄.

Maresin 1 Mitigates Inflammatory Response and Protects Mice from Sepsis

Sepsis, frequently caused by infection of bacteria, is considered as an uncontrollable systematic inflammation response syndrome (SIRS). Maresin 1 (Mar1) is a new proresolving mediator with potent anti-inflammatory effect in several animal models. However, its effect in sepsis is still not investigated. To address this question, we developed sepsis model in BALB/c mice by cecal ligation and puncture (CLP) with or without Mar1 treatment. Our data showed that Mar1 markedly improved survival rate and decreased the levels of proinflammatory cytokines in CLP mice such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β). Furthermore, Mar1 reduced serum level of lipopolysaccharide (LPS) and enhanced the bacteria clearance in mice sepsis model. Moreover, Mar1 attenuated lung injury and decreased level of alanine transaminase (ALT), aspartate transaminase (AST), creatinine (Cre), and blood urea nitrogen (BUN) in serum in mice after CLP surgery. Treatment with Mar1 inhibited activation of nuclear factor kappa B (NF-κb) pathway. In conclusion, Mar1 exhibited protective effect in sepsis by reducing LPS, bacteria burden in serum, inhibiting inflammation response, and improving vital organ function. The possible mechanism is partly involved in inhibition of NF-κb activation.