Ameliorative impacts of astaxanthin against atrazine-induced renal toxicity through the modulation of ionic homeostasis and Nrf2 signaling pathways in mice

Astaxanthin (ASX), a red pigment belonging to carotenoids, has antioxidant activity and anti-oxidative stress effect. Atrazine (ATZ), a frequently used herbicide, whose degradation products are the cause for nephrosis and other oxidative stress associated diseases. This study was aimed to reveal the potential protective mechanism of astaxanthin against atrazine-induced nephrosis. Atrazine was orally given (250 mg/kg bw) to the mice along with astaxanthin (100 mg/kg bw) for 28 days. Serum biochemical indicators, oxidative stress biomarkers, ATPase activities, ion concentration, histomorphology, and various renal genes expression linked with apoptosis, Nrf2 signaling pathway, and aquaporins (AQPs) were assessed. It was found that serum creatinine (SCr), blood urea nitrogen (BUN), and MDA levels were significantly increased after the treatment of atrazine, whereas serum renal oxidative stress indicators like CAT, GSH, T-AOC, SOD decreased. Renal histopathology showed that atrazine significantly damaged renal tissues. The activities of Ca 2+-Mg 2+-ATPase were increased whereas Na +-K +-ATPase decreased significantly (P < 0.05). Moreover, results confirmed that the expression of AQPs, Nrf2, and apoptosis genes were also altered after atrazine administration. Interestingly, astaxanthin supplementation significantly (P < 0.05) improved atrazine-induced nephrotoxicity via decreasing SCr, BUN, oxidative stress, ionic homeostasis and reversing the changes in AQPs, Nrf2, and apoptosis gene expression. These findings collectively suggested that astaxanthin has strong potential ameliorative impact against atrazine induced nephrotoxicity.

Astaxanthin from microalgae: A review on structure, biosynthesis, production strategies and application

Astaxanthin is a red-colored secondary metabolite with excellent antioxidant properties, typically finds application as foods, feed, cosmetics, nutraceuticals, and medications. Astaxanthin is usually produced synthetically using chemicals and costs less as compared to the natural astaxanthin obtained from fish, shrimps, and microorganisms. Over the decades, astaxanthin has been naturally synthesized from Haematococcus pluvialis in commercial scales and remains exceptional, attributed to its higher bioactive properties as compared to synthetic astaxanthin. However, the production cost of algal astaxanthin is still high due to several bottlenecks prevailing in the upstream and downstream processes. To that end, the present study intends to review the recent trends and advancements in astaxanthin production from microalgae. The structure of astaxanthin, sources, production strategies of microalgal astaxanthin, and factors influencing the synthesis of microalgal astaxanthin were discussed while detailing the pathway involved in astaxanthin biosynthesis. The study also discusses the relevant downstream process used in commercial scales and details the applications of astaxanthin in various health related issues.

Curcumin ameliorates focal segmental glomerulosclerosis by inhibiting apoptosis and oxidative stress in podocytes

Focal segmental glomerulosclerosis (FSGS), a podocyte disease, is the leading cause of end-stage renal disease (ESRD). Nevertheless, the current effective treatment for FSGS is deficient. Curcumin (CUR) is a principal curcuminoid of turmeric, which is a member of the ginger family. Previous studies have shown that CUR has renoprotective effects. However, the mechanism of CUR in anti-FSGS is not clear. This study aimed to explore the mechanism of CUR against FSGS through a combination of network pharmacological methods and verification of experiments. The analysis identified 98 shared targets of CUR against FSGS, and these 98 targets formed a network of protein-protein interactions (PPI). Of these 98 targets, AKT1, TNF, IL-6, VEGFA, STAT3, MAPK3, HIF1A, CASP3, IL1B, and JUN were identified as the hub targets. Molecular docking suggested that the best binding to CUR is MAPK3 and AKT1. Apoptotic process and cell proliferation were identified as the main biological processes of CUR against FSGS by gene ontology (GO) analysis. The most enriched signaling pathway in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was the PI3K-AKT signaling pathway. Western blots and flow cytometry showed that CUR could inhibit adriamycin (ADR) induced apoptosis, oxidative stress damage, and attenuate podocyte epithelial-mesenchymal transition (EMT) by repressing the AKT signaling pathway. Collectively, our study demonstrates that CUR can attenuate apoptosis, oxidative stress damage, and EMT in FSGS in vitro. These results supply a compelling basis for future studies of CUR for the clinical treatment of FSGS.

Activation of Nrf2 pathway as a protective mechanism against oxidative stress-induced diseases: Potential of astaxanthin

Astaxanthin, a red-orange liposoluble carotenoid, has been the centre of considerable attention in recent years for its numerous biological activities, notably its potent antioxidant activity. It is reported that astaxanthin elicits these biological activities via a number of cellular pathways. The Nrf2/Keap1 pathway is a major regulator of the antioxidant defence system of cells; it modulates the expression of a plethora of genes related to redox homeostasis as well as cellular detoxification. The pathway has received lots of attention as a prospective therapeutic target for diseases related to oxidative stress and aging. Several reports have shown that the pathway is inducible by many natural compounds. This present work reviews the Nrf2/Keap1 pathway, its regulation and involvement in diseases, provides a brief overview of naturally occurring compounds as activators of the pathway as well as discusses the effect of astaxanthin on the pathway.

Astaxanthin as a King of Ketocarotenoids: Structure, Synthesis, Accumulation, Bioavailability and Antioxidant Properties

Astaxanthin (3,3-dihydroxy-β, β-carotene-4,4-dione) is a ketocarotenoid synthesized by Haematococcus pluvialis/lacustris, Chromochloris zofingiensis, Chlorococcum, Bracteacoccus aggregatus, Coelastrella rubescence, Phaffia rhodozyma, some bacteria (Paracoccus carotinifaciens), yeasts, and lobsters, among others However, it is majorly synthesized by Haematococcus lacustris alone (about 4%). The richness of natural astaxanthin over synthetic astaxanthin has drawn the attention of industrialists to cultivate and extract it via two stage cultivation process. However, the cultivation in photobioreactors is expensive, and converting it in soluble form so that it can be easily assimilated by our digestive system requires downstream processing techniques which are not cost-effective. This has made the cost of astaxanthin expensive, prompting pharmaceutical and nutraceutical companies to switch over to synthetic astaxanthin. This review discusses the chemical character of astaxanthin, more inexpensive cultivating techniques, and its bioavailability. Additionally, the antioxidant character of this microalgal product against many diseases is discussed, which can make this natural compound an excellent drug to minimize inflammation and its consequences.

Astaxanthin: A promising therapeutic agent for organ fibrosis

Fibrosis is the end-stage pathological manifestation of many chronic diseases. Infiltration of inflammatory cells and activation of myofibroblasts are the most prominent features of fibrosis, with excessive deposition of extracellular matrix (ECM) in tissues leading to organ tissue damage, which eventually progresses to organ failure and leads to high mortality rates. At present, a large number of studies have been conducted on tissue fibrosis, and the pathological mechanism of fibrosis development has generally been recognized. However, the prevention and treatment of fibrosis is still an unsolved problem, and a shortage of drugs that can be used in the clinic persists. Astaxanthin (ASTX), a carotenoid, is widely known for its strong antioxidant capacity. ASTX also has other biological properties, such as anti-inflammatory, antiaging and anticancer properties. Recently, many papers have reported that ASTX inhibits the occurrence and development of fibrosis by regulating signaling molecular pathways, such as transforming growth factor-β/small mother against decapentaplegic protein (TGF-β1/Smad), sirtuin 1 (SIRT1), nuclear factor kappa-B (NF-κB), microRNA, nuclear factor-E2-related factor 2/antioxidant response element (Nrf 2/ARE) and reactive oxygen species (ROS) pathways. By targeting these molecular signaling pathways, ASTX may become a potential drug for the treatment of fibrotic diseases. In this review, we summarize the therapeutic effects of ASTX on organ fibrosis and its underlying mechanisms of action. By reviewing the results from in vitro and in vivo studies, we analyzed the therapeutic prospects of ASTX for various fibrotic diseases and provided insights into and strategies for exploring new drugs for the treatment of fibrosis.

Anti-Oxidant and Anti-Inflammatory Effects of Astaxanthin on Gastrointestinal Diseases

A moderate amount of reactive oxygen species (ROS) is produced under normal conditions, where they play an important role in cell signaling and are involved in many aspects of the immune response to pathogens. On the other hand, the excessive production of ROS destructs macromolecules, cell membranes, and DNA, and activates pro-inflammatory signaling pathways, which may lead to various pathologic conditions. Gastrointestinal (GI) mucosa is constantly exposed to ROS due to the presence of bacteria and other infectious pathogens in food, as well as alcohol consumption, smoking, and the use of non-steroidal anti-inflammatory drugs (NSAID). Prolonged excessive oxidative stress and inflammation are two major risk factors for GI disorders such as ulcers and cancers. Bioactive food compounds with potent anti-oxidant and anti-inflammatory activity have been tested in experimental GI disease models to evaluate their therapeutic potential. Astaxanthin (AST) is a fat-soluble xanthophyll carotenoid that is naturally present in algae, yeast, salmon, shrimp, and krill. It has been shown that AST exhibits protective effects against GI diseases via multiple mechanisms. Residing at the surface and inside of cell membranes, AST directly neutralizes ROS and lipid peroxyl radicals, enhances the activity of anti-oxidant enzymes, and suppresses pro-inflammatory transcription factors and cytokines. In addition, AST has been shown to inhibit cancer cell growth and metastasis via modulating cell proliferation-related pathways, apoptosis, and autophagy. Considering the potential benefits of AST in GI diseases, this review paper aims to summarize recent advances in AST research, focusing on its anti-oxidant and anti-inflammatory effects against gastric and intestinal ulcers and cancers.

Health benefits of astaxanthin against age-related diseases of multiple organs: A comprehensive review

Age-related diseases are associated with increased morbidity in the past few decades and the cost associated with the treatment of these age-related diseases exerts a substantial impact on social and health care expenditure. Anti-aging strategies aim to mitigate, delay and reverse aging-associated diseases, thereby improving quality of life and reducing the burden of age-related pathologies. The natural dietary antioxidant supplementation offers substantial pharmacological and therapeutic effects against various disease conditions. Astaxanthin is one such natural carotenoid with superior antioxidant activity than other carotenoids, as well as well as vitamins C and E, and additionally, it is known to exhibit a plethora of pharmacological effects. The present review summarizes the protective molecular mechanisms of actions of astaxanthin on age-related diseases of multiple organs such as Neurodegenerative diseases [Alzheimer's disease (AD), Parkinson's disease (PD), Stroke, Multiple Sclerosis (MS), Amyotrophic lateral sclerosis (ALS), and Status Epilepticus (SE)], Bone Related Diseases [Osteoarthritis (OA) and Osteoporosis], Cancers [Colon cancer, Prostate cancer, Breast cancer, and Lung Cancer], Cardiovascular disorders [Hypertension, Atherosclerosis and Myocardial infarction (MI)], Diabetes associated complications [Diabetic nephropathy (DN), Diabetic neuropathy, and Diabetic retinopathy (DR)], Eye disorders [Age related macular degeneration (AMD), Dry eye disease (DED), Cataract and Uveitis], Gastric Disorders [Gastritis, Colitis, and Functional dyspepsia], Kidney Disorders [Nephrolithiasis, Renal fibrosis, Renal Ischemia reperfusion (RIR), Acute kidney injury (AKI), and hyperuricemia], Liver Diseases [Nonalcoholic fatty liver disease (NAFLD), Alcoholic Liver Disease (AFLD), Liver fibrosis, and Hepatic Ischemia-Reperfusion (IR) Injury], Pulmonary Disorders [Pulmonary Fibrosis, Acute Lung injury (ALI), and Chronic obstructive pulmonary disease (COPD)], Muscle disorders (skeletal muscle atrophy), Skin diseases [Atopic dermatitis (ATD), Skin Photoaging, and Wound healing]. We have also briefly discussed astaxanthin's protective effects on reproductive health.

Astaxanthin from Crustaceans and Their Byproducts: A Bioactive Metabolite Candidate for Therapeutic Application

In recent years, the food, pharma, and cosmetic industries have shown considerable interest in bioactive molecules of marine origin that show high potential for application as nutraceuticals and therapeutic agents. Astaxanthin, a lipid-soluble and orange-reddish-colored carotenoid pigment, is one of the most investigated pigments. Natural astaxanthin is mainly produced from microalgae, and it shows much stronger antioxidant properties than its synthetic counterpart. This paper aims to summarize and discuss the important aspects and recent findings associated with the possible use of crustacean byproducts as a source of astaxanthin. In the last five years of research on the crustaceans and their byproducts as a source of natural astaxanthin, there are many new findings regarding the astaxanthin content in different species and new green extraction protocols for its extraction. However, there is a lack of information on the amounts of astaxanthin currently obtained from the byproducts as well as on the cost-effectiveness of the astaxanthin production from the byproducts. Improvement in these areas would most certainly contribute to the reduction of waste and reuse in the crustacean processing industry. Successful exploitation of byproducts for recovery of this valuable compound would have both environmental and social benefits. Finally, astaxanthin’s strong biological activity and prominent health benefits have been discussed in the paper.

Anti-inflammatory action of astaxanthin and its use in the treatment of various diseases

Astaxanthin (AST) is a red pigmented carotenoid with significant antioxidant, anti-inflammatory, anti-proliferative, and anti-apoptotic properties. In this study, we summarize the available literature on the anti-inflammatory efficacy of AST in various chronic and acute disorders, such as neurodegenerative, renal-, hepato-, skin- and eye-related diseases, as well as gastrointestinal disorders. In addition, we elaborated on therapeutic efficacy of AST and the role of several pathways, including PI3K/AKT, Nrf2, NF-κB, ERK1/2, JNK, p38 MAPK, and JAK-2/STAT-3 in mediating its effects. However, additional experimental and clinical studies should be performed to corroborate the anti-inflammatory effects and protective effects of AST against inflammatory diseases in humans. Nevertheless, this review suggests that AST with its demonstrated anti-inflammatory property may be a suitable candidate for drug design with novel technology.

Exploring the Use of Medicinal Plants and Their Bioactive Derivatives as Alveolar NLRP3 Inflammasome Regulators during Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a successful intracellular pathogen that is responsible for the highest mortality rate among diseases caused by bacterial infections. During early interaction with the host innate cells, M. tuberculosis cell surface antigens interact with Toll like receptor 4 (TLR4) to activate the nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain-containing 3 (NLRP3) canonical, and non-canonical inflammasome pathways. NLRP3 inflammasome activation in the alveoli has been reported to contribute to the early inflammatory response that is needed for an effective anti-TB response through production of pro-inflammatory cytokines, including those of the Interleukin 1 (IL1) family. However, overstimulation of the alveolar NLRP3 inflammasomes can induce excessive inflammation that is pathological to the host. Several studies have explored the use of medicinal plants and/or their active derivatives to inhibit excessive stimulation of the inflammasomes and its associated factors, thus reducing immunopathological response in the host. This review describes the molecular mechanism of the NLRP3 inflammasome activation in the alveoli during M. tuberculosis infection. Furthermore, the mechanisms of inflammasome inhibition using medicinal plant and their derivatives will also be explored, thus offering a novel perspective on the alternative control strategies of M. tuberculosis-induced immunopathology.

Astaxanthin promotes M2 macrophages and attenuates cardiac remodeling after myocardial infarction by suppression inflammation in rats

Background

Cardiac remodeling after acute myocardial infarction (AMI) is an important process. The present study aimed to assess the protective effects of astaxanthin (ASX) on cardiac remodeling after AMI.

Methods

The study was conducted between April and September 2018. To create a rat AMI model, rats were anesthetized, and the left anterior descending coronary artery was ligated. The rats in the ASX group received 10 mg·kg⁻¹·day⁻¹ ASX by gavage for 28 days. On the 1st day after AMI, but before ASX administration, six rats from each group were sacrificed to evaluate changes in the heart function and peripheral blood (PB) levels of inflammatory factors. On the 7th day after AMI, eight rats from each group were sacrificed to evaluate the PB levels of inflammatory factors and the M2 macrophage count using both immunofluorescence (IF) and flow cytometry (FC). The remaining rats were observed for 28 days. Cardiac function was examined using echocardiography. The inflammatory factors, namely, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-10, were assessed using enzyme-linked immunosorbent assay. The heart weight/body weight (BW), and lung weight (LW)/BW ratios were calculated, and myocardial fibrosis in the form of collagen volume fraction was measured using Masson trichrome staining. Hematoxylin and eosin (H&E) staining was used to determine the myocardial infarct size (MIS), and TdT-mediated dUTP nick-end labeling staining was used to analyze the myocardial apoptosis index. The levels of apoptosis-related protein, type I/III collagen, transforming growth factor β1 (TGF-β1), metalloproteinase 9 (MMP9), and caspase 3 were assessed by Western blotting. Unpaired t-test, one-way analysis of variance, and non-parametric Mann-Whitney test were used to analyze the data.

Results

On day 1, cardiac function was worse in the ASX group than in the sham group (left ventricular end-systolic diameter [LVID_s]: 0.72 ± 0.08 vs. 0.22 ± 0.06 cm, t = −11.38; left ventricular end-diastolic diameter [LVID_d]: 0.89 ± 0.09 vs. 0.48 ± 0.05 cm, t = −9.42; end-systolic volume [ESV]: 0.80 [0.62, 0.94] vs. 0.04 [0.03, 0.05] mL, Z = −2.89; end-diastolic volume [EDV]: 1.39 [1.03, 1.49] vs. 0.28 [0.22, 0.32] mL, Z = −2.88; ejection fraction [EF]: 0.40 ± 0.04 vs. 0.86 ± 0.05, t = 10.00; left ventricular fractional shortening [FS] rate: 0.19 [0.18, 0.20] %FS vs. 0.51 [0.44, 0.58] %FS, Z = −2.88, all P < 0.01; n = 6). The levels of inflammatory factors significantly increased (TNF-α: 197.60 [133.89, 237.94] vs. 50.48 [47.21 57.10] pg/mL, Z = −2.88; IL-1β: 175.23 [160.74, 215.09] vs. 17.78 [16.83, 19.56] pg/mL, Z = −2.88; IL-10: 67.64 [58.90, 71.46] vs. 12.33 [11.64, 13.98] pg/mL, Z = −2.88, all P < 0.01; n = 6). On day 7, the levels of TNF-α and IL-1β were markedly lower in the ASX group than in the AMI group (TNF-α: 71.70 [68.60, 76.00] vs. 118.07 [106.92, 169.08] pg/mL, F = 42.64; IL-1β: 59.90 [50.83, 73.78] vs. 151.60 [108.4, 198.36] pg/mL, F = 44.35, all P < 0.01, n = 8). Conversely, IL-10 levels significantly increased (141.84 [118.98, 158.36] vs. 52.96 [42.68, 74.52] pg/mL, F = 126.67, P < 0.01, n = 8). The M2 macrophage count significantly increased (2891.42 ± 211.29 vs. 1583.38 ± 162.22, F = 274.35, P < 0.01 by immunofluorescence test; 0.96 ± 0.18 vs. 0.36 ± 0.05, F = 46.24, P < 0.05 by flowcytometry test). On day 28, cardiac function was better in the ASX group than in the AMI group (LVID_s: 0.50 [0.41, 0.56] vs. 0.64 [0.56, 0.74] cm, Z = −3.60; LVID_d: 0.70 [0.60, 0.76] vs. 0.80 [0.74 0.88] cm, Z = −2.96; ESV: 0.24 [0.18, 0.45] vs. 0.58 [0.44, 0.89] mL, Z = −3.62; EDV: 0.76 [0.44, 1.04] vs. 1.25 [0.82, 1.46] mL, Z = −2.54; EF: 0.60 ± 0.08 vs. 0.50 ± 0.12, F = 160.48; %FS: 0.29 [0.24, 0.31] vs. 0.20 [0.17, 0.21], Z = −4.43, all P < 0.01; n = 16). The MIS and LW/BW ratio were markedly lower in the ASX group than in the AMI group (myocardial infarct size: 32.50 ± 1.37 vs. 50.90 ± 1.73, t = 23.63, P < 0.01, n = 8; LW/BW: 1.81 ± 0.15 vs. 2.17 ± 0.37, t = 3.66, P = 0.01, n = 16). The CVF was significantly lower in the ASX group than in the AMI group: 12.88 ± 2.53 vs. 28.92 ± 3.31, t = 10.89, P < 0.01, n = 8. The expression of caspase 3, TGF-β1, MMP9, and type I/III collagen was lower in the ASX group than in the AMI group (caspase 3: 0.38 ± 0.06 vs. 0.66 ± 0.04, t = 8.28; TGF-β1: 0.37 ± 0.04 vs. 0.62 ± 0.07, t = 6.39; MMP9: 0.20 ± 0.06 vs. 0.40 ± 0.06, t = 4.62; type I collagen: 0.42 ± 0.09 vs. 0.74 ± 0.07, t = 5.73; type III collagen: 0.13 ± 0.02 vs. 0.74 ± 0.07, t = 4.32, all P < 0.01; n = 4).

Conclusions

ASX treatment after AMI may promote M2 macrophages and effectively attenuate cardiac remodeling by inhibiting inflammation and reducing myocardial fibrosis.

Astaxanthin and Nrf2 signaling pathway: a novel target for new therapeutic approaches

Astaxanthin (AST) is a naturally occurring compound isolated from various sources such as fungi, plants, salmon, and crab. However, Haematococcus Pluvialis, a green alga, is the primary source of this beta carotenoid compound. AST has several favourable biological and pharmacological activities such as antioxidant, anti-inflammatory, anti-tumor, anti-diabetes, hepatoprotective and neuroprotective. Nevertheless, the exact molecular mechanisms of these protective effects of AST are unclear yet. The Nrf2 signaling pathway is one of the critical candidate signaling pathways that may be involved in these beneficial effects of AST. This signaling pathway is responsible for maintaining the redox balance in the physiologic state. Upon nuclear translocation, Nrf2 signaling activates antioxidant enzymes to reduce oxidative stress and protect cells against damage. In the current study, we have reviewed the effects of AST on the Nrf2 signaling pathway, which could potentially be developed as a novel therapeutic approach for the management of various diseases.

Pharmacotherapy against Oxidative Stress in Chronic Kidney Disease: Promising Small Molecule Natural Products Targeting Nrf2-HO-1 Signaling

The global burden of chronic kidney disease (CKD) intertwined with cardiovascular disease has become a major health problem. Oxidative stress (OS) plays an important role in the pathophysiology of CKD. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant responsive element (ARE) antioxidant system plays a critical role in kidney protection by regulating antioxidants during OS. Heme oxygenase-1 (HO-1), one of the targets of Nrf2-ARE, plays an important role in regulating OS and is protective in a variety of human and animal models of kidney disease. Thus, activation of Nrf2-HO-1 signaling may offer a potential approach to the design of novel therapeutic agents for kidney diseases. In this review, we have discussed the association between OS and the pathogenesis of CKD. We propose Nrf2-HO-1 signaling-mediated cell survival systems be explored as pharmacological targets for the treatment of CKD and have reviewed the literature on the beneficial effects of small molecule natural products that may provide protection against CKD.

Protective Role of Nrf2 in Renal Disease

Chronic kidney disease (CKD) is one of the fastest-growing causes of death and is predicted to become by 2040 the fifth global cause of death. CKD is characterized by increased oxidative stress and chronic inflammation. However, therapies to slow or prevent CKD progression remain an unmet need. Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor that plays a key role in protection against oxidative stress and regulation of the inflammatory response. Consequently, the use of compounds targeting Nrf2 has generated growing interest for nephrologists. Pre-clinical and clinical studies have demonstrated that Nrf2-inducing strategies prevent CKD progression and protect from acute kidney injury (AKI). In this article, we review current knowledge on the protective mechanisms mediated by Nrf2 against kidney injury, novel therapeutic strategies to induce Nrf2 activation, and the status of ongoing clinical trials targeting Nrf2 in renal diseases.

Natural Products that Target the NLRP3 Inflammasome to Treat Fibrosis

Fibrosis is a common pathway followed by different organs after injury, and it can lead to parenchymal scarring, cellular dysfunction, and even organ failure. The NLRP3 inflammasome is a multiprotein complex composed of the sensor molecule NLRP3, the adaptor apoptosis-associated speck-like protein containing a CARD (ASC), and the effector protease caspase-1. Overactivation of the NLRP3 inflammasome triggers the abundant secretion of IL-1β and IL-18, induces pyroptosis, and promotes the release of a swathe of proinflammatory proteins, all of which contribute to fibrogenic processes in multiple organs. In recent years, screening bioactive natural compounds for NLRP3 inhibitors to alleviate fibrosis has gained broad interest from the scientific community because of the associated cost-effectiveness and easy access. In this review, we systematically and comprehensively summarize the natural products, including terpenoids, phenols, and alkaloids, among others, and the plant-derived crude extracts, that have been reported to ameliorate fibrosis via inhibiting NLRP3 inflammasome activation and highlight the underlying mechanisms. Among all the compounds, diterpenoids is the most promising candidates for inhibiting NLRP3 inflammasome activation and improving fibrosis, as they possess combined inhibitory effect on NLRP3 inflammasome assembly and NF-κB signaling pathway. All the information may aid in the development of therapeutic strategies for the treatment of fibrotic diseases.

Astaxanthin and its Effects in Inflammatory Responses and Inflammation-Associated Diseases: Recent Advances and Future Directions

Astaxanthin is a natural lipid-soluble and red-orange carotenoid. Due to its strong antioxidant property, anti-inflammatory, anti-apoptotic, and immune modulation, astaxanthin has gained growing interest as a multi-target pharmacological agent against various diseases. In the current review, the anti-inflammation mechanisms of astaxanthin involved in targeting for inflammatory biomarkers and multiple signaling pathways, including PI3K/AKT, Nrf2, NF-κB, ERK1/2, JNK, p38 MAPK, and JAK-2/STAT-3, have been described. Furthermore, the applications of anti-inflammatory effects of astaxanthin in neurological diseases, diabetes, gastrointestinal diseases, hepatic and renal diseases, eye and skin disorders, are highlighted. In addition to the protective effects of astaxanthin in various chronic and acute diseases, we also summarize recent advances for the inconsistent roles of astaxanthin in infectious diseases, and give our view that the exact function of astaxanthin in response to different pathogen infection and the potential protective effects of astaxanthin in viral infectious diseases should be important research directions in the future.

Astaxanthin from Haematococcus pluvialis ameliorates the chemotherapeutic drug (doxorubicin) induced liver injury through the Keap1/Nrf2/HO-1 pathway in mice

The aim of this study is to probe a new function of astaxanthin (AST) from Haematococcus pluvialis on chemotherapeutic drug (doxorubicin) induced liver injury in mice.

Oxidative Stress and Renal Fibrosis: Mechanisms and Therapies

Oxidative stress results from the disruption of the redox system marked by a notable overproduction of reactive oxygen species. There are four major sources of reactive oxygen species, including NADPH oxidases, mitochondria, nitric oxide synthases, and xanthine oxidases. It is well known that renal abnormalities trigger the production of reactive oxygen species by diverse mechanisms under various pathologic stimuli, such as acute kidney injury, chronic kidney disease, nephrotic syndrome, and metabolic disturbances. Mutually, accumulating evidences have identified that oxidative stress plays an essential role in tubulointerstitial fibrosis by myofibroblast activation as well as in glomerulosclerosis by mesangial sclerosis, podocyte abnormality, and parietal epithelial cell injury. Given the involvement of oxidative stress in renal fibrosis, therapies targeting oxidative stress seem promising in renal fibrosis management. In this review, we sketch the updated knowledge of the mechanisms of oxidative stress generation during renal diseases, the pathogenic processes of oxidative stress elicited renal fibrosis and treatments targeting oxidative stress during tubulointerstitial fibrosis and glomerulosclerosis.

Hypoxia causes important changes of extracellular matrix biomarkers and ADAMTS proteinases in the adriamycin-induced renal fibrosis model

AIM

Renal fibrosis is a common cause of renal dysfunction with chronic kidney diseases. This process is characterized by excessive production of extracellular matrix (ECM) or inhibition of ECM degradation. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) proteinases, which are widely presented in mammals, have very critical roles in ECM remodelling. We aimed to study the role of ADAMTS proteinases and some of the ECM markers in the pathogenesis of renal fibrosis and to investigate the effects of hypoxia on these biomarkers.

METHODS

In addition to the control group, Adriamycin (ADR) treated rats were divided into four groups as ADR, sham and two hypoxia groups. Renal nephropathy was assessed biochemical assays, pathological and immunohistochemical staining methods. The expression of ADAMTSs and mRNA were determined using Western blotting and real-time PCR, respectively.

RESULTS

Renal dysfuntion and tissue damage in favour of ECM accumulation and renal fibrosis were observed in the ADR group. This was approved by remarkable changes in the expression of ADAMTS such as increased ADAMTS-1, -12 and -15. In addition, it was found that hypoxia and duration of hypoxia enhanced markers of tubulointerstitial fibrosis in the rat kidney tissues. Also, expression differences especially in ADAMTS-1, -6 and -15 were observed in the hypoxia groups. The variable and different expression patterns of ADAMTS proteinases in the ADR-induced renal fibrosis suggest that ADAMTS family members are involved in the development and progression of fibrosis.

CONCLUSION

The expression changes of ADAMTS proteinases in kidney and association with hypoxia have potential clues to contribute to the early diagnosis and treatment options of renal fibrosis.

STC-1 ameliorates renal injury in diabetic nephropathy by inhibiting the expression of BNIP3 through the AMPK/SIRT3 pathway

Diabetic kidney disease (DKD) is the leading cause of morbidity and mortality in individuals with diabetes, and it is the leading cause of end-stage renal disease (ESRD) worldwide. Stanniocalcin-1 (STC-1) is present in various tissues, and it has antioxidant and anti-apoptotic activities, which play a role in kidney protection, including diabetic nephropathy (DN). However, the mechanism that underlies these effects remains unknown. This study suggests that STC-1 ameliorates oxidative stress and cell apoptosis in the kidneys of db/db mice and high glucose (HG)-treated BUMPT cells by inhibiting Bnip3 expression through AMPK/Sirt3 pathway activation. In the clinic, DKD patients with high levels of STC-1 have a better prognosis than patients with low STC-1 levels. Thus, we concluded that STC-1 ameliorates renal injury in DN by inhibiting the expression of Bnip3 through the AMPK/SIRT3 pathway and that serum STC-1 is independently associated with DKD progression in patients with type 2 diabetes. As high STC-1 levels indicate a better prognosis, synthetic STC-1 may become a potential drug for the treatment of DKD patients.

Astaxanthin ameliorates renal interstitial fibrosis and peritubular capillary rarefaction in unilateral ureteral obstruction

Loss of peritubular capillaries is a notable feature of progressive renal interstitial fibrosis. Astaxanthin (ASX) is a natural carotenoid with various biological activities. The present study aimed to evaluate the effect of ASX on unilateral ureteral obstruction (UUO)‑induced renal fibrosis in mice. For that purpose, mice were randomly divided into five treatment groups: Sham, ASX 100 mg/kg, UUO, UUO + ASX 50 mg/kg and UUO + ASX 100 mg/kg. ASX was administered to the mice for 7 or 14 days following UUO. The results demonstrated that UUO‑induced histopathological changes in the kidney tissue were prevented by ASX. Renal function was improved by ASX treatment, as evidenced by decreased blood urea nitrogen and serum creatinine levels. Furthermore, the extent of renal fibrosis and collagen deposition induced by UUO was suppressed by ASX. The levels of collagen I, fibronectin and α‑smooth muscle actin were increased by UUO in mice or by transforming growth factor (TGF)‑β1 treatment in NRK‑52E cells, and were reduced by ASX administration. In addition, ASX inhibited the UUO‑induced decrease in peritubular capillary density by upregulating vascular endothelial growth factor and downregulating thrombospondin 1 levels. Inactivation of the TGF‑β1/Smad signaling pathway was involved in the anti‑fibrotic mechanism of ASX in UUO mice and TGF‑β1‑treated NRK‑52E cells. In conclusion, ASX attenuated renal interstitial fibrosis and peritubular capillary rarefaction via inactivation of the TGF‑β1/Smad signaling pathway.

Periplaneta Americana Extract May Attenuate Renal Fibrosis through Inhibiting Janus Tyrosine Kinase 2/Signal Transducer and Activator of Transcription 3 Pathway

BACKGROUND

Periplaneta americana is one of the ancient insect groups with the strongest vitality. Periplaneta americana extract (PAE) has been explored as an alternative remedy for many diseases. Although much progress has been made in the study about PAE, the role of the drug in renal disease is rarely reported, especially in renal fibrosis. This study was designed to evaluate the renoprotective effect of PAE treatment to renal fibrosis.

METHOD

An in vivo, unilateral ureteral obstruction (UUO) mouse model was built. Then the mice were treated with PAE (100 mg/kg body weight) once daily by oral gavage, again starting on the day of UUO and continued for 1 week. At the end of 1 week, the mice were sacrificed; kidney samples were collected for further analysis. In vitro, Boston University mouse proximal tubular cells were plated in 35-mm dishes at a density of 0.3 * 106 cells/dish. Then the cells were treated with 5-ng/mL TGF-β1 in serum-free DMEM medium for an indicated length of time. The experimental groups were pretreated with the indicated concentrations of PAE (0.3125 mg/mL). The cells were further cultured for 24 h, and then cells were monitored morphologically or collected for biochemical analyses.

RESULTS

Both in vivo and vitro PAE inhibits the expression of FN and alpha-smooth muscle actin and suppresses renal fibrosis. Importantly, PAE protects against renal fibrosis by inhibiting Janus tyrosine kinase 2 (JAK)/signal transducer and activator of transcription 3 (STAT) tyrosine phosphorylation.

CONCLUSION

PAE attenuates renal fibrosis through the suppression of the JAK2/STAT3 pathway.

Lack of serum- and glucocorticoid-inducible kinase 3 leads to podocyte dysfunction

Serum- and glucocorticoid-inducible kinase 3 (SGK3) is a downstream mediator of PI3K, which is essential for maintaining the functional integrity of podocytes. However, little is known about the role of SGK3 in podocyte function. Herein, we demonstrated that SGK3 contributes to the maintenance of podocyte integrity. Conditionally immortalized mouse podocyte cells (MPCs) were treated with puromycin aminonucleoside (PAN). PAN treatment inhibited the activity of SGK3 and the expression of podocin. Short hairpin RNA (shRNA)-mediated knockdown of SGK3 also reduced podocin expression in the absence of PAN. Adriamycin (ADR)-treated mice developed proteinuria and had decreased renal glomerular SGK3 expression in comparison to control mice. Consistent with a role for SGK3 in the ADR effect, SGK3 knockout (KO) mice had markedly reduced kidney podocin expression and significantly elevated proteinuria compared with wild-type mice. Electron microscopy revealed that SGK3 KO mice displayed partial effacement of podocyte foot processes. Further, a SGK3 target protein, glycogen synthase kinase-3 (GSK3), was discovered to be dramatically activated in PAN and SGK3 shRNA-treated MPCs and in SGK3 KO mice. Taken together, these data strongly suggest that SGK3 plays a significant role in regulating podocyte function, likely by controlling the expression and activity of GSK3.-Peng, L.-Q., Zhao, H., Liu, S., Yuan, Y.-P., Yuan, C.-Y., Mwamunyi, M.-J., Pearce, D., Yao, L.-J. Lack of serum- and glucocorticoid-inducible kinase 3 leads to podocyte dysfunction.

Inflammasomes in the Kidney

Inflammasomes influence a diverse range of kidney disease, including acute and chronic kidney diseases, and those mediated by innate and adaptive immunity. Both IL-18 and in particular IL-1β are validated therapeutic targets in several kidney diseases. In addition to leukocyte-derived inflammasomes, renal tissue cells express functional inflammasome components. Furthermore, a range of endogenous substances that directly activate inflammasomes also mediate kidney injury. Many of the functional studies have focussed on the NLRP3 inflammasome, and there is also evidence for the involvement of other inflammasomes in some conditions. While, at least in some disease, the mechanistic details of the involvement of the inflammasome remain to be elucidated, therapies focussed on inflammasomes and their products have potential in treating kidney disease in the future.

Resveratrol Attenuates Adriamycin-Induced Focal Segmental Glomerulosclerosis through C3aR/C5aR- Sphingosine Kinase 1 Pathway

Background/Aim: Focal segmental glomerulosclerosis (FSGS) typically presents with nephrotic range proteinuria, which could eventually develop into end-stage renal disease. Resveratrol (RSV) is a natural polyphenol compound, which has been reported to suppress inflammatory response and renal interstitial fibrosis. This study is aimed at evaluating the renoprotective effect of RSV treatment on adriamycin-induced FSGS. Methods: In Balb/c mice, adriamycin nephropathy was induced by adriamycin (10 mg/kg body weight, diluted in normal saline) via a tail vein on day 0. Then the mice were treated with RSV (40 mg/kg body weight) once daily by oral gavage, again starting on the day of adriamycin injection and continued for 6 weeks. At 6 weeks, the mice were sacrificed; kidneys and blood samples were collected for further analysis. Results: When treated with adriamycin, the expressions of C3aR, C5aR, sphingosine kinase 1 (Sphk1), and soluble urokinase-type plasminogen activator receptor (suPAR) were upregulated, while RSV treatment could inhibit the expressions of C3aR, C5aR, Sphk1, and suPAR, eventually leading to anti-inflammatory and anti-fibrosis conditions. Conclusion: RSV attenuates adriamycin-induced FSGS through C3aR/C5aR-Sphk1 pathway.

Astaxanthin in cardiovascular health and disease: mechanisms of action, therapeutic merits, and knowledge gaps

Cardiovascular disease is the main contributor to morbidity and mortality worldwide.