Cathelicidin-WA attenuates LPS-induced inflammation and redox imbalance through activation of AMPK signaling

New insight into the biological activity of Salmo salar NK-lysin antimicrobial peptides

NK-lysin is a potent antimicrobial peptide (AMP) with antimicrobial activity against bacteria, fungi, viruses, and parasites. NK-lysin is a type of granulysin, a member of the saposin-like proteins family first isolated from a pig's small intestine. In previous work, for the first time, we identified four variants of nk-lysin from Atlantic salmon (Salmo salar) using EST sequences. In the present study, we reported and characterized two additional transcripts of NK-lysin from S. salar. Besides, we evaluated the tissue distribution of three NK-lysins from S. salar and assessed the antimicrobial, hemolytic, and immunomodulatory activities and signaling pathways of three NK-lysin-derived peptides. The synthetic peptides displayed antimicrobial activity against Piscirickettsia salmonis (LF-89) and Flavobacterium psychrophilum. These peptides induced the expression of immune genes related to innate and adaptive immune responses in vitro and in vivo. The immunomodulatory activity of the peptides involves the mitogen-activated protein kinases-mediated signaling pathway, including p38, extracellular signal-regulated kinase 1/2, and/or c-Jun N-terminal kinases. Besides, the peptides modulated the immune response induced by pathogen-associated molecular patterns (PAMPs). Our findings show that NK-lysin could be a highly effective immunostimulant or vaccine adjuvant for use in fish aquaculture.

Akebia saponin D attenuates allergic airway inflammation through AMPK activation

Akebia saponin D (ASD) is a bioactive triterpenoid saponin extracted from Dipsacus asper Wall. ex DC.. This study aimed to investigate the effects of ASD on allergic airway inflammation. Human lung epithelial BEAS-2B cells and bone marrow-derived mast cells (BMMCs) were pretreated with ASD (50, 100 and 200 μΜ) and AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) (1 mM), and then stimulated with lipopolysaccharide (LPS) or IL-33. Pretreatment with ASD and AICAR significantly inhibited TNF-α and IL-6 production from BEAS-2B cells, and IL-13 production from BMMCs. Moreover, pretreatment with ASD and AICAR significantly increased p-AMPK expression in BEAS-2B cells. Inhibition of AMPK by siRNA and compound C partly abrogated the suppression effect of ASD on TNF-α, IL-6, and IL-13 production. Asthma murine model was induced by ovalbumin (OVA) challenge and treated with ASD (150 and 300 mg/kg) or AICAR (100 mg/kg). Infiltration of eosinophils, neutrophils, monocytes, and lymphocytes, and production of TNF-α, IL-6, IL-4, and IL-13 were attenuated in ASD and AICAR treated mice. Lung histopathological changes were also ameliorated after ASD and AICAR treatment. Additionally, it showed that treatment with ASD and AICAR increased p-AMPK expression in the lung tissues. In conclusion, ASD exhibited protective effects on allergic airway inflammation through the induction of AMPK activation.

A reactive oxygen species-responsive hydrogel encapsulated with bone marrow derived stem cells promotes repair and regeneration of spinal cord injury

Spinal cord injury (SCI) is an overwhelming and incurable disabling event accompanied by complicated inflammation-related pathological processes, such as excessive reactive oxygen species (ROS) produced by the infiltrated inflammatory immune cells and released to the extracellular microenvironment, leading to the widespread apoptosis of the neuron cells, glial and oligodendroctyes. In this study, a thioketal-containing and ROS-scavenging hydrogel was prepared for encapsulation of the bone marrow derived mesenchymal stem cells (BMSCs), which promoted the neurogenesis and axon regeneration by scavenging the overproduced ROS and re-building a regenerative microenvironment. The hydrogel could effectively encapsulate BMSCs, and played a remarkable neuroprotective role in vivo by reducing the production of endogenous ROS, attenuating ROS-mediated oxidative damage and downregulating the inflammatory cytokines such as interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), resulting in a reduced cell apoptosis in the spinal cord tissue. The BMSCs-encapsulated ROS-scavenging hydrogel also reduced the scar formation, and improved the neurogenesis of the spinal cord tissue, and thus distinctly enhanced the motor functional recovery of SCI rats. Our work provides a combinational strategy against ROS-mediated oxidative stress, with potential applications not only in SCI, but also in other central nervous system diseases with similar pathological conditions.

Honokiol Ameliorates DSS-Induced Mouse Colitis by Inhibiting Inflammation and Oxidative Stress and Improving the Intestinal Barrier

Ulcerative colitis (UC) is a multifactor intestinal disease with increased morbidity. Recently, pleiotropic drugs with exact biosafety have been urgently needed. Honokiol (HKL) is the major bioactive component of traditional Chinese medicine "Houpu," with almost no toxic effects and approved anti-inflammation, antioxidant, antispasmodic, etc. effects. This study examined the therapeutic effect of HKL in dextran sulfate sodium- (DSS-) induced experimental colitis. In vivo, C57BL/6 mice received 3% DSS for seven days to generate UC, and HKL was pretreated for five days and given during the whole DSS-induced period. In vitro, RAW264.7 macrophages were stimulated with lipopolysaccharide (LPS) to induce inflammation, and mouse colon epithelial cells (MCEC) were treated with HKL or pretreated with HKL and then stimulated with LPS-induced macrophage supernate to investigate the barrier enhancement roles. HKL significantly ameliorated disease activity index (DAI), colon length, and histopathological scores in DSS-induced colitis. The inflammatory mediators of interleukin 1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX2) were decreased, and the tight conjunction proteins were increased in the HKL-treated group both in vivo and in vitro. Above all, HKL can relieve experimental UC through anti-inflammation, antioxidant, and epithelial barrier enhancement roles. These effects were associated with peroxisome proliferator-activated receptor γ (PPARγ)/nuclear factor-κB (NF-κB) p65, sirtuin3 (SIRT3)/adenosine 5'-monophosphate- (AMP-) activated protein kinase (AMPK), and nuclear factor erythroid 2-related factor 2 (NRF2)/heme oxygenase 1 (HO1) signaling pathways. In conclusion, after further clinical studies, HKL may be a promising drug for UC.

Purification Process and In Vitro and In Vivo Bioactivity Evaluation of Pectolinarin and Linarin from Cirsium japonicum

Pectolinarin and linarin are two major flavone O-glycosides of Cirsium japonicum, which has been used for thousands of years in traditional Chinese medicine. Pharmacological research on pectolinarin and linarin is meaningful and necessary. Here, a process for the purification of pectolinarin and linarin from C. japonicum was established using macroporous resin enrichment followed by prep-HPLC separation. The results show the purity of pectolinarin and linarin reached 97.39% and 96.65%, respectively. The in vitro bioactivities result shows the ORAC values of pectolinarin and linarin are 4543 and 1441 µmol TE/g, respectively, meanwhile their inhibition rate of BSA-MGO-derived AGEs is 63.58% and 19.31% at 2 mg/mL, which is 56.03% and 30.73% in the BSA-fructose system, respectively. The COX-2 inhibition rate at 50 µg/mL of linarin and pectolinarin reached 55.35% and 40.40%, respectively. Furthermore, the in vivo bioassay combining of histopathologic evaluation and biochemical analysis of liver glutamic oxaloacetic transaminase, serum creatinine and TNF-α show pectolinarin can alleviate lipopolysaccharide (LPS)-induced acute liver and kidney injury in mice. Metabolomics analysis shows that pectolinarin attenuates LPS-challenged liver and kidney stress through regulating the arachidonic acid metabolism and glutathione synthesis pathways. Collectively, our work presents a solid process for pectolinarin and linarin purification and has discovered a promising natural therapeutic agent-pectolinarin.

Development of Intestinal Injury and Restoration of Weaned Piglets under Chronic Immune Stress

This study aimed to investigate the effects of lipopolysaccharide (LPS)-induced chronic immune stress on intestinal morphology and function, immune system, oxidative status, and mitochondrial function in piglets. Fifty healthy Duroc × Landrace × Yorkshire piglets (21 ± 2 days old, barrow, 6.98 ± 0.14 kg body weight) were selected and randomly allotted to five groups, which were slaughtered at 0 (0 group), 1, 5, 9, and 15 d of LPS injection. The results showed that compared with the piglets without LPS injection, LPS injection significantly impaired the intestinal morphology and permeability at 1, 5, and 9 d, as manifested by the increased serum lactic acid and decreased ratio of villus height to crypt depth (p < 0.05). Moreover, intestinal inflammation and oxidative and mitochondrial injury were caused at 1 d, as manifested by upregulated IL-6 mRNA expression, increased malondialdehyde content, and impaired mitochondrial morphology (p < 0.05). However, these parameters were restored to levels identical to 0 group at 9~15 d, accompanied by significantly increased antioxidant capacity, enhanced protein expression of CD3+ and CD68+, and upregulated mRNA abundance of genes related to mitochondrial biogenesis and functions (p < 0.05). Collectively, these results suggest that the intestinal injury of piglets caused by chronic immune stress could be self-repaired.

A critical role of AMP-activated protein kinase in regulating intestinal nutrient absorption, barrier function, and intestinal diseases

As one of the most important organs in animals, the intestine is responsible for nutrient absorption and acts as a barrier between the body and the environment. Intestinal physiology and function require the participation of energy. 5'-adenosine monophosphate-activated protein kinase (AMPK), a classical and highly expressed energy regulator in intestinal cells, regulates the process of nutrient absorption and barrier function and is also involved in the therapy of intestinal diseases. Studies have yielded findings that AMPK regulates the absorption of glucose, amino acids, and fatty acids in the intestine primarily by regulating transportation systems, as we detailed here. Moreover, AMPK is involved in the regulation of the intestinal mechanical barrier and immune barrier through manipulating the expression of tight junctions, antimicrobial peptides, and secretory immunoglobulins. In addition, AMPK also participates in the regulation of intestinal diseases, which indicates that AMPK is a promising therapeutic target for intestinal diseases and cancer. In this review, we summarized the current understanding regarding how AMPK regulates intestinal nutrient absorption, barrier function, and intestinal diseases.

(-)-Epicatechin Reduces Neuroinflammation, Protects Mitochondria Function, and Prevents Cognitive Impairment in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy is a common neurological complication of sepsis. Despite advances in pathological and diagnostic investigations, its treatment remains a major challenge. In sepsis-associated encephalopathy, neuroinflammatory overactivation and mitochondrial damage are thought to contribute to cognitive and behavioral impairments. In this study, we found that administration of (−)-Epicatechin, a dietary flavonoid of the flavan-3-ol subgroup, improves memory deficits and behavior performance by ameliorating neuroinflammation, regulating mitochondria function, enhancing synaptic plasticity, and reducing neuronal loss in a mouse model of lipopolysaccharide-induced sepsis. We further show that the AMPK signaling pathway might be among the mechanisms involved in the beneficial memory effects. Our data demonstrated the potential of (−)-Epicatechin as a new drug candidate for the treatment of sepsis-associated cognitive impairment by targeting AMPK.

Upregulating Human Cathelicidin Antimicrobial Peptide LL-37 Expression May Prevent Severe COVID-19 Inflammatory Responses and Reduce Microthrombosis

COVID-19 is characterized by hyperactivation by inflammatory cytokines and recruitment of macrophages, neutrophils, and other immune cells, all hallmarks of a strong inflammatory response that can lead to severe complications and multi-organ damage. Mortality in COVID-19 patients is associated with a high prevalence of neutrophil extracellular trap (NET) formation and microthrombosis that are exacerbated by hyperglycemia, diabetes, and old age. SARS-CoV-2 infection in humans and non-human primates have revealed long-term neurological consequences of COVID-19, possibly concomitant with the formation of Lewy bodies in the brain and invasion of the nervous system via the olfactory bulb. In this paper, we review the relevance of the human cathelicidin LL-37 in SARS-CoV-2 infections. LL-37 is an immunomodulatory, host defense peptide with direct anti-SARS-CoV-2 activity, and pleiotropic effects on the inflammatory response, neovascularization, Lewy body formation, and pancreatic islet cell function. The bioactive form of vitamin D and a number of other compounds induce LL-37 expression and one might predict its upregulation, could reduce the prevalence of severe COVID-19. We hypothesize upregulation of LL-37 will act therapeutically, facilitating efficient NET clearance by macrophages, speeding endothelial repair after inflammatory tissue damage, preventing α-synuclein aggregation, and supporting blood-glucose level stabilization by facilitating insulin release and islet β-cell neogenesis. In addition, it has been postulated that LL-37 can directly bind the S1 domain of SARS-CoV-2, mask angiotensin converting enzyme 2 (ACE2) receptors, and limit SARS-CoV-2 infection. Purposeful upregulation of LL-37 could also serve as a preventative and therapeutic strategy for SARS-CoV-2 infections.

Neuroprotective Effects of Rhodiola Sacra on Transient Global Cerebral Ischemia Through Activating AMPK/Nrf2 Pathway in Rats

Aims: Rhodiola sacra is a widely used pharmaceutical component with multiple functions, including anti-oxidation and anti-inflammation. However, the exact mechanisms involved in neuroprotection against transient global cerebral ischemia (tGCI) remain to be elucidated. Herein, we aim at closing the gap in understanding on whether rhodiola sacra reduces neuronal death in hippocampal CA1 and at demonstrating how rhodiola sacra offers neuroprotection after tGCI. Results: The results show that rhodiola sacra (2.4 g/kg/d by feeding) pretreatment or/and postreatment significantly alleviated neuronal injury, inhibited glial activation, and improved cognitive function in male rats subjected to tGCI. The neuroprotection of prophylaxis with rhodiola sacra is equivalent to that of therapeutics. The binding mode of adenosine monophosphate-activated protein kinase (AMPK) α2-subunit with rhodiola sacra was predicted by molecular docking. Further, rhodiola sacra upregulates phosphorylated AMPK and promotes nuclear translocation of nuclear factor erythroid 2 related factor 2 (Nrf2). In addition, rhodiola sacra increases heme oxygenase-1 (HO-1) expression and activity and reduces malondialdehyde (MDA) content in CA1 after tGCI. However, the neuroprotection of rhodiola sacra is abolished by Nrf2 knockdown with small interfering RNA (siRNA) after tGCI. Similarly, the inhibition of AMPK with Compound C or siRNA against AMPK α2 aggravates neuronal death after tGCI through decreasing nuclear Nrf2 and the expression and activity of HO-1, and by increasing the release of MDA. Innovation and Conclusion: For the first time, this study demonstrates that as a prophylactic or therapeutic agent rhodiola sacra prevents oxidant stress, protects neurons, and improves cognitive function through activating the AMPK/Nrf2 pathway in tGCI rats. Antioxid. Redox Signal. 36, 567-591.

Dioscin promotes autophagy by regulating the AMPK-mTOR pathway in ulcerative colitis

BACKGROUND

Dioscin is reported to alleviate the dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) in mice. Autophagy plays an anti-inflammatory role in UC. We herein aimed to explore the biological functions of dioscin in autophagy in UC.

METHODS

To explore the effects of dioscin on UC progression, a DSS-induced mouse model of UC was established. Body weight, disease activity index and macroscopic damage index scores were recorded for seven days. Hematoxylin & Eosin (HE) staining was used to stain colon sections and an BX53 microscope was prepared to observe pathological changes. The activities of glutathione, superoxidative dismutase, and malondialdehyde were determined by commercially available kits. Western blotting was performed to measure the protein levels of p-AMPK/AMPK, p-mTOR/mTOR and autophagy-related genes.

RESULTS

The DSS-induced colitis and oxidative stress in mice were ameliorated after dioscin treatment. Dioscin promoted the phosphorylation of AMPK to inhibit mTOR activation and facilitated autophagy in DSS-induced mice model of UC.

CONCLUSION

Dioscin promotes autophagy by promoting the phosphorylation of AMPK to inhibit mTOR activation in ulcerative colitis.

Luteolin Protects Chondrocytes from H2O2-Induced Oxidative Injury and Attenuates Osteoarthritis Progression by Activating AMPK-Nrf2 Signaling

Osteoarthritis (OA) is a chronic degenerative disease featured by cartilage erosion and inflammation. Luteolin, a member of the flavonoid family, has been shown to exert anti-inflammatory and antioxidative activities. However, the potential biological effects and underlying mechanism of luteolin on chondrocytes and OA progression remain largely elusive. In this study, the potential effect and mechanism of luteolin on OA were investigated in vitro and in vivo. Our data revealed that luteolin inhibited H₂O₂-induced cell death, apoptosis, oxidative stress, programmed necrosis, and inflammatory mediator production in primary murine chondrocytes. In addition, luteolin could activate the AMPK and Nrf2 pathways, and AMPK serves as a positive upstream regulator of Nrf2. In vivo results demonstrated the therapeutic effects of luteolin on OA in the DMM mouse model. Collectively, our findings showed that luteolin might serve as a novel and effective treatment for OA and provided a new research direction for clinical OA therapies.

LKB1 Regulates Vascular Macrophage Functions in Atherosclerosis

Liver kinase B1 (LKB1) is known to shape the regulation of macrophage function by participating in multiple processes including cell metabolism, growth, and polarization. However, whether LKB1 also affects the functional plasticity of macrophages in atherosclerosis has not attracted much attention. Abnormal macrophage function is a pathophysiological hallmark of atherosclerosis, characterized by the formation of foam cells and the maintenance of vascular inflammation. Mounting evidence supports that LKB1 plays a vital role in the regulation of macrophage function in atherosclerosis, including affecting lipid metabolism reprogramming, inflammation, endoplasmic reticulum stress, and autophagy in macrophages. Thus, decreased expression of LKB1 in atherosclerosis aggravates vascular injury by inducing excessive lipid deposition in macrophages and the formation of foam cells. To systematically understand the role and potential mechanism of LKB1 in regulating macrophage functions in atherosclerosis, this review summarizes the relevant data in this regard, hoping to provide new ideas for the prevention and treatment of atherosclerosis.

The Potential Protective Effect of Iridoid Glycosides Isolated From Osmanthus fragrans Seeds Against the Development of Immune Liver Injury in Mice

Objective: The iridoid glycosides were extracted and separated from Osmanthus fragrans seeds, and the potential protective effect of Osmanthus fragrans seed extract on concanavalin A-induced immune liver injury in mice was studied.

Methods:Osmanthus fragrans seeds were extracted by 95% ethanol reflux. Then, the iridoid glycosides were enriched by extraction refined through petroleum ether (60°C–90°C), ethyl acetate, and water-saturated n-butanol in sequence, so as to purify the n-butanol part (Osmanthus fragrans seed’s n-butanol extraction, OFSN) by macroporous resin. Specnuezhenide and Nuezhenoside G13 were used as the reference substances to determine the concentration of iridoid glycosides by HPLC. On this basis, a mouse immune liver injury model was established by tail intravenous concanavalin A (20 mg/kg); the contents of serum ALT, AST, IFN-γ, and TNF-α and the contents of liver tissue MDA and SOD were determined; the pathological changes of the liver by HE staining were observed; and the expression levels of p38MAPK and p-p38mapk in liver tissue were detected by WB.

Results: The linearity, precision, repeatability, recovery, and stability of HPLC all met the requirements by validating with the methodology. The contents of Specnuezhenide and Nuezhenoside G13 in the n-butanol extracts were 39.20% and 39.88%, respectively. Actually, their contents can reach up to 82.56% and 87.9% after being purified by macroporous resin. The results of animal experiments show that OFSN could significantly reduce the liver and spleen index, reduce the ALT and AST contents in plasma and the MDA content in liver tissue, and then increase the SOD content. Besides, OFSN could also reduce the plasma IFN-γ and TNF-α levels. The HE staining result indicates that the pathological changes in the liver tissues of mice treated with OFSN are alleviated to different degrees while the WB result suggests that OFSN could significantly inhibit the expression of p-p38mapk.

Conclusion:Osmanthus fragrans seeds are rich in iridoid glycosides, which has a good protective effect on mouse immune liver injury caused by concanavalin A. The mechanism may be related to inhibiting the phosphorylation of p38MAPK, inhibiting the release of inflammatory mediators, improving the antioxidant capacity of liver cells, and weakening the occurrence of lipid peroxidation.

Cathelicidin-WA ameliorates diabetic cardiomyopathy by inhibiting the NLRP3 inflammasome

Cathelicidin-WA (CWA) is a novel cathelicidin peptide isolated from snakes that has been suggested to exert anti-inflammatory effects. The aim of our study was to investigate whether cathelicidin-WA (CWA) could protect the heart from diabetic cardiomyopathy (DCM). Streptozotocin (STZ) injection was used to establish a mouse model of DCM. CWA peptide (2 mg/kg or 8 mg/kg) was continuously administered to the mice from 10 weeks to 16 weeks after STZ injection. The mice in the DCM group exhibited cardiac dysfunction, while 8 mg/kg CWA ameliorated this cardiac dysfunction. Cardiac fibrosis, inflammation, and oxidative stress as well as cardiomyocyte apoptosis in the DCM mice were decreased by treatment with 8 mg/kg CWA. We isolated neonatal rat cardiomyocytes and stimulated the cells with high glucose to establish an in vitro model of myocyte cell injury. Consistently, CWA inhibited high glucose-induced cell death, inflammation and oxidative stress in the myocytes. Moreover, CWA reduced the formation of the NLR family pyrin domain-containing 3 (NRLP3) inflammasome by regulating thioredoxin-interacting protein expression and p65 activation. NLRP3 overexpression inhibited the beneficial effects of CWA on the heart during DCM and on high glucose-induced myocyte injury. In summary, CWA attenuates cardiac injury and preserves cardiac function during DCM by targeting the NLRP3 pathway.Abbreviations: AAV9: Adeno associated virus; AGE: Advanced Glycation End products; CWA: Cathelicidin-WA; DCM: diabetic cardiomyopathy; Gpx: glutathione peroxidase; HG: high glucose; IL: Interleukin; NLR: Family Pyrin Domain Containing 3 (NRLP3); TXNIP: Thioredoxin interacting protein; LVEF: left ventricular ejection fraction; MDA: Malondialdehyde; MnSOD: manganese superoxide dismutase; NADPH: Nicotinamide adenine dinucleotide phosphate; NAC: N-acetyl-cysteine; NRCMs: Neonatal rat cardiomyocytes; ROS: reactive oxygen species; STZ: Streptozotocin; TNFa: tumor necrosis factor a.

Cathelicidin-WA Protects Against LPS-Induced Gut Damage Through Enhancing Survival and Function of Intestinal Stem Cells

Preservation of intestinal stem cells (ISCs) plays a critical role in initiating epithelial regeneration after intestinal injury. Cathelicidin peptides have been shown to participate in regulating intestinal damage repair. However, it is not known how exactly Cathelicidin-WA (CWA) exert its function after tissue damage. Using a gut injury model in mice involving Lipopolysaccharide (LPS), we observed that CWA administration significantly improved intestinal barrier function, preserved ISCs survival, and augmented ISCs viability within the small intestine (SI) under LPS treatment. In addition, CWA administration effectively prevented proliferation stops and promoted the growth of isolated crypts. Mechanistically, our results show that the appearance of γH2AX was accompanied by weakened expression of SETDB1, a gene that has been reported to safeguard genome stability. Notably, we found that CWA significantly rescued the decreased expression of SETDB1 and reduced DNA damage after LPS treatment. Taken together, CWA could protect against LPS-induced gut damage through enhancing ISCs survival and function. Our results suggest that CWA may become an effective therapeutic regulator to treat intestinal diseases and infections.

Caveolin-1 Alleviates Acetaminophen-Induced Fat Accumulation in Non-Alcoholic Fatty Liver Disease by Enhancing Hepatic Antioxidant Ability via Activating AMPK Pathway

Non-alcoholic fatty liver disease (NAFLD) is an independent risk factor for acute liver injury caused by overuse of acetaminophen (APAP). Caveolin-1 (CAV1), a regulator of hepatic energy metabolism and oxidative stress, was found to have a protective effect against NAFLD in our previous study. However, it remains unclear whether CAV1 has a protective effect against APAP-induced hepatotoxicity in NAFLD. The aim of this study was to determine whether CAV1 inhibits oxidative stress through the AMPK/Nrf2/HO-1 pathway to protect the liver from fat accumulation exacerbated by APAP in NAFLD. In this study, seven-week-old C57BL/6 male mice (18–20 g) were raised under similar conditions for in vivo experiment. In vitro, L02 cells were treated with A/O (alcohol and oleic acid mixture) for 48 h, and APAP was added at 24 h for further incubation. The results showed that the protein expression of the AMPK/Nrf2 pathway was enhanced after CAV1 upregulation. The effects of CAV1 on fat accumulation, ROS, and the AMPK/Nrf2 anti-oxidative pathway were reduced after the application of CAV1-siRNA. Finally, treatment with compound C (an AMPK inhibitor) prevented CAV1 plasmid-mediated alleviation of oxidative stress and fat accumulation and reduced the protein level of Nrf2 in the nucleus, demonstrating that the AMPK/Nrf2/HO-1 pathway was involved in the protective effect of CAV1. These results indicate that CAV1 exerted a protective effect against APAP-aggravated lipid deposition and hepatic injury in NAFLD by inhibiting oxidative stress. Therefore, the upregulation of CAV1 might have clinical benefits in reducing APAP-aggravated hepatotoxicity in NAFLD.

Metformin Inhibits Lipoteichoic Acid-Induced Oxidative Stress and Inflammation Through AMPK/NRF2/NF-κB Signaling Pathway in Bovine Mammary Epithelial Cells

The objective of this research was to explore the effect of metformin on the lipoteichoic acid (LTA)–induced mastitis model using isolated primary bovine mammary epithelial cells (PBMECs). The PBMECs were exposed to either 3 mM metformin for 12 h as a metformin group (MET) or 100 μg/mL LTA for 6 h as LTA group (LTA). Cells pretreated with 3 mM metformin for 12 h followed by washing and 100 μg/mL LTA exposure for 6 h served as the MET + LTA group. Phosphate-buffered saline was added to cells as the control group. PBMECs pretreated with different metformin doses were analyzed by a flow cytometry (annexin V–fluorescein isothiocyanate assay) to detect the cell apoptotic rate. We performed quantitative reverse transcriptase–polymerase chain reaction and Western blot analysis to evaluate the inflammatory and oxidative responses to metformin and LTA by measuring cellular cytotoxicity, mRNA expression, and protein expression. Immunofluorescence was used to evaluate nuclear localization. The results showed that the gene expression of COX2, IL-1β, and IL-6 significantly increased in the cells challenged with LTA doses compared to control cells. In inflammatory PBMECs, metformin attenuated LTA-induced expression of inflammatory genes nuclear factor κB (NF-κB) p65, tumor necrosis factor α, cyclooxygenase 2, and interleukin 1β, as well as the nuclear localization and phosphorylation of NF-κBp65 protein, but increased the transcription of nuclear factor erythroid 2–related factor 2 (Nrf2) and Nrf2-targeted antioxidative genes heme oxygenase-1 (HO-1) and Gpx1, as well as the nuclear localization of HO-1 protein. Importantly, metformin-induced activation of Nrf2 is AMP-activated protein kinase (AMPK)–dependent; as metformin-pretreated PBMECs activated AMPK signaling via the upregulation of phosphorylated AMPK levels, cell pretreatment with metformin also reversed the translocation of Nrf2 that was LTA inhibited. This convergence between AMPK and Nrf2 pathways is essential for the anti-inflammatory effect of metformin in LTA-stimulated PBMECs. Altogether, our results indicate that metformin exerts anti-inflammation and oxidative stress through regulation of AMPK/Nrf2/NF-κB signaling pathway, which highlights the role of AMPK as a potential therapeutic strategy for treatment of bovine mastitis.

MicroRNA-30d-5p ameliorates lipopolysaccharide-induced acute lung injury via activating AMPKα

OBJECTIVES

Acute lung injury (ALI) is a devastating lung disease characterized by uncontrolled pulmonary inflammation and oxidative stress. Currently, no effective therapeutic strategies are available for ALI and its prognosis remains poor. The present study aims to investigate the role and potential mechanism of microRNA-30d-5p (miR-30d-5p) in the progression of ALI.

METHODS

Mice were intravenously treated with miR-30d-5p agomir, antagomir or their respective controls for 3 consecutive days and then were exposed to a single intratracheal injection of lipopolysaccharide (LPS) for 12 h at a dosage of 5 mg/kg to induce ALI. To inhibit adenosine monophosphate-activated protein kinase α (AMPKα) or phosphodiesterase 4 D (PDE4D), compound C (CpC) and rolipram were used.

RESULTS

miR-30d-5p expression in the lungs was significantly inhibited by LPS treatment. miR-30d-5p agomir significantly alleviated, while miR-30d-5p antagomir aggravated pulmonary inflammation, oxidative damage, and dysfunction in ALI mice. Besides, we found that miR-30d-5p agomir ameliorated LPS-induced ALI via activating AMPKα and that the inhibition of AMPKα by CpC completely abolished these beneficial effects of miR-30d-5p agomir. Further findings validated that PDE4D downregulation was required for the activation of AMPKα by miR-30d-5p agomir.

CONCLUSION

miR-30d-5p ameliorates LPS-induced ALI via activating AMPKα and it is a valuable therapeutic candidate in the treatment of ALI.

Asperuloside suppressing oxidative stress and inflammation in DSS-induced chronic colitis and RAW 264.7 macrophages via Nrf2/HO-1 and NF-κB pathways

BACKGROUND

Inflammatory bowel diseases (IBDs), which mainly include Crohn's disease (CD) and ulcerative colitis (UC), are chronic idiopathic inflammatory disease of the gastrointestinal tract for which effective pharmacological treatments are lacking or options are very limited.

PURPOSE

Here, we aim to investigate the therapeutic effects of an iridoid glycoside, asperuloside (ASP) on mice experimental chronic colitis induced by dextran sulfate sodium (DSS) and further explore underlying mechanisms in vitro and in vivo.

METHODS

LPS-treated RAW 264.7 cells showed inflammation and were assessed for various physiological, morphological and biochemical parameters in the absence or presence of ASP. Chronic colitis was induced by 2% DSS in mice, which were used as an animal model to explore the pharmacodynamics of ASP. We detected p65 and Nrf2 pathway proteins via Western blot and RT-PCR analysis, assessed the cytokines TNF-α and IL-6 via ELISA, tested p65 and Nrf2 nuclear translocation via fluorescence. In addition, the docking affinity of ASP and p65 or Nrf2 proteins in the MOE 2015 software.

RESULTS

We found that ASP attenuated weight loss, disease activity index (DAI) and colonic pathological damage in colitis mice and restored the expressions of inflammatory cytokines in the colon. In addition, ASP restored antioxidant capacity in DSS-induced chronic colitis mice and lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Furthermore, ASP suppressed oxidative stress through increasing Nrf2, HO-1 and NQO-1 proteins expressions, and down-regulated nuclear levels of p65 to inhibit DSS-induced colonic oxidative stress and inflammation. Validation of the molecular docking results also indicated that ASP interacts with Nrf2 or p65 proteins. In summary, ASP improved DSS-induced chronic colitis by alleviating inflammation and oxidative stress, activating Nrf2/HO-1 signaling and limiting NF-κB signaling pathway, which may be an effective candidate for the treatment of IBD.

l-Arginine Alleviates Hydrogen Peroxide-Induced Oxidative Damage in Ovine Intestinal Epithelial Cells by Regulating Apoptosis, Mitochondrial Function, and Autophagy

BACKGROUND

Previous studies demonstrated that dietary l-arginine (Arg) alters the equilibrium between reactive oxygen species (ROS) generation and biological defenses to resist oxidant-induced toxicity. Whether supplying Arg can protect ovine intestinal epithelial cells (OIECs) from hydrogen peroxide (H2O2)-induced oxidative damage is unclear.

OBJECTIVES

The current study aimed to examine the effect of Arg on mitophagy, mitochondrial dysfunction, and apoptosis induced by H2O2 in OIECs.

METHODS

The OIECs were incubated in Arg-free DMEM supplemented with 100 μM Arg (CON) or 350 μM Arg (ARG) alone or with 150 μM H2O2 (CON + H2O2, ARG + H2O2) for 24 h. Cellular apoptosis, mitochondrial function, autophagy, and the related categories of genes and proteins were determined. All data were analyzed by ANOVA using the general linear model procedures of SAS (SAS Institute) for a 2 × 2 factorial design.

RESULTS

Relative to the CON and ARG groups, H2O2 administration resulted in 44.9% and 26.5% lower (P < 0.05) cell viability but 34.7% and 61.8% greater (P < 0.05) ROS concentration in OIECs, respectively. Compared with the CON and CON + H2O2 groups, Arg supplementation led to 40.7% and 28.8% lower (P < 0.05) ROS concentration but 14.9%-49.0% and 29.3%-64.1% greater (P < 0.05) mitochondrial membrane potential, relative mitochondrial DNA content, and complex (I-IV) activity in OIECs, respectively. Compared with the CON and CON + H2O2 groups, Arg supplementation led to 33.9%-53.1% and 22.4%-49.1% lower (P < 0.05) mRNA abundance of proapoptotic genes, respectively. Relative to the CON and CON + H2O2 groups, Arg supplementation resulted in 33.0%-59.2% and 14.6%-37.7% lower (P < 0.05) abundance of proapoptotic, mitophagy, and cytoplasmic cytochrome c protein, respectively.

CONCLUSIONS

Supply of Arg protects OIECs against H2O2-induced damage partly by improving mitochondrial function and alleviating cellular apoptosis and autophagy.

Therapeutic effect of an anti-tuberculosis agent, isoniazid, and its nano-isoform in ulcerative colitis

BACKGROUND

Isoniazid (INH) is well known as a first-line anti-tuberculosis, while some studies demonstrate that it has anti-inflammatory activity via a different mechanism such as inhibitionthe production of IL-1, ROS, activation of PPARγ expression, inhibition of the transcriptional regulatory activity of NF-κB and AP-1. The aim of this study, investigate the anti-inflammatory effect of INH and INH combined with Sulfasalazine-loaded nanoparticles (NPs) in the ulcerative colitis mouse model.

METHODS

To investigate the anti-inflammatory effect of INH and NPs in the ulcerative colitis mice model, we evaluated the effect of INH clinical symptoms and colonic mucosal histology in colitis.

RESULT

The present study demonstrates that combination therapy of INH with sulfasalazine as well as NPs reduces the symptom of ulcerative colitis and improved disease activity index include body lose weight, diarrhea, rectal bleeding, colonic length, spleen weight, and colon histopathological score in DSS-induced colitis mice model.

CONCLUSION

Our results suggest that the nanoforms of INH with sulfasalazine enhances the therapeutic effect of the drugs in the treatment of ulcerative colitis.

Anti-inflammatory effects of Platycodin D on dextran sulfate sodium (DSS) induced colitis and E. coli Lipopolysaccharide (LPS) induced inflammation

Platycodin D (PLD) is a saponin found in Platycodon grandiflorum, which has been reported to have anti-inflammatory effects. However, the effects of PLD on ulcerative colitis (UC) remain unknown. In this study, PLD showed the potential to reduce inflammation, ameliorate intestinal damage, and maintain intestinal integrity in DSS-induced colitis. However, the beneficial effect of PLD was reduced when macrophages were depleted, indicating the key role of macrophages in the beneficial effect of PLD in DSS-induced colitis. Meanwhile, we found that PLD inhibited the expression of M1 markers and promoted the expression of M2 markers in colon. Similarly, we found PLD significantly attenuated the levels of pro-inflammatory cytokines, increased the level of anti-inflammatory cytokine and altered macrophage proportions in LPS-stimulated RAW 264.7 cells in vitro. Moreover, treating LPS-stimulated RAW 264.7 cells with PLD increased the activation of the PI3K/Akt signaling pathway and decreased activation of NF-κB pathway. Furthermore, we found that the anti-inflammatory and macrophage polarization regulatory effects of PLD was Adenosine 5'-monophosphate-activated protein kinase (AMPK)-dependent. These results indicate that PLD attenuates DSS-induced colitis and LPS-induced inflammation, and the mechanism behind the phenomenon may be regulating macrophage polarization via activation of AMPK. Our study provides a theoretical basis for PLD to be used as a potential treatment of colitis.

Roflupram, a novel phosphodiesterase 4 inhibitor, inhibits lipopolysaccharide-induced neuroinflammatory responses through activation of the AMPK/Sirt1 pathway

Roflupram (ROF) is a novel phosphodiesterase 4 inhibitor. We previously found that ROF suppressed the production of pro-inflammatory factors in microglial cells; however, the underlying mechanisms are largely unknown. The present study aimed to elucidate the underlying molecular mechanisms of the anti-neuroinflammatory effects of ROF in lipopolysaccharide (LPS)-activated microglial cells and LPS-challenged mice. Treatment with ROF suppressed LPS-induced expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in BV-2 microglia cell line. Immunofluorescence and Western blotting analysis showed that ROF significantly inhibited the activation of microglia, as evidenced by decreased expression of ionized calcium binding adaptor molecule-1 (Iba1). Similar results were obtained in primary cultured microglial cells. ROF induced the phosphorylation of AMP-activated protein kinase (AMPK) and the expression of Sirtuin 1 (Sirt1). Interestingly, the AMPK inhibitor, compound C, blocked the role of ROF in both the phosphorylation of AMPK and the expression of Sirt1 in BV-2 cells stimulated with LPS. More importantly, the Sirt1 inhibitor, EX527, abolished the inhibitory role of ROF on the production of pro-inflammatory factors, and reactivated BV-2 cells. In mice challenged with LPS, ROF improved cognition and decreased the levels of IL-6 and TNF-α in both the cortex and hippocampus. In contrast, EX527 weakened the effects of ROF on cognitive enhancement and reduction of pro-inflammatory factors in the cortex and hippocampus. Furthermore, EX527 blocked the inhibitory role of ROF in the activation of microglial cells in both the hippocampus and cortex. Taken together, our results indicated that ROF attenuated LPS-induced neuroinflammatory responses in microglia, and the AMPK/Sirt1 pathway is essential for the anti-inflammatory effects of ROF.

Protection against acute renal injury by naturally occurring medicines which act through Nrf2 signaling pathway

The cellular defense pathway plays a key role in maintaining the homeostasis, tissues and organisms. Nuclear factor E2-related factor 2 (Nrf2), as a key cell signaling pathway, plays an important role in encoding detoxification enzymes and other stress response mediators. Recent studies have shown that it is closely related to the prevention and treatment of acute kidney injury (AKI). Therefore, this article reviews the protective effects of Nrf2-related signaling pathways on acute kidney injury, and summarizes the strategies of natural pharmaceutical ingredients such as flavonoids, alkaloids, terpenes, phenylpropionic acid, polyphenols, and polysaccharides to prevent and treat acute kidney injury. It is of great significance to further study the relationship between Nrf2 regulated signal pathway and kidney disease and the development of new medicines for acute kidney injury treatment. It can also provide new ideas and treatment strategies for clinical treatment of acute kidney injury. PRACTICAL APPLICATIONS: This article reviewed the mechanisms by which the active ingredients of natural medicines slow down acute kidney injury through the Nrf2 pathway. It will help us to understand the regulatory role of the Nrf2 pathway in AKI more comprehensively, and provide a theoretical basis for further exploring the mechanism of more natural drugs to reduce acute kidney injury.

Andrographolide Exerts Antihyperglycemic Effect through Strengthening Intestinal Barrier Function and Increasing Microbial Composition of Akkermansia muciniphila

Accumulating evidence indicates that type 2 diabetes (T2D) is associated with intestinal barrier dysfunction and dysbiosis, implying the potential targets for T2D therapeutics. Andrographolide was reported to have several beneficial effects on diabetes and its associated complications. However, the protective role of andrographolide, as well as its underlying mechanism against T2D, remains elusive. Herein, we reported that andrographolide enhanced intestinal barrier integrity in LPS-induced Caco-2 cells as indicated by the improvement of cell monolayer barrier permeability and upregulation of tight junction protein expression. In addition, andrographolide alleviated LPS-induced oxidative stress by preventing ROS and superoxide anion radical overproduction and reversing glutathione depletion. In line with the in vitro results, andrographolide reduced metabolic endotoxemia and strengthened gut barrier integrity in db/db diabetic mice. We also found that andrographolide appeared to ameliorate glucose intolerance and insulin resistance and attenuated diabetes-associated redox disturbance and inflammation. Furthermore, our results indicated that andrographolide modified gut microbiota composition as indicated by elevated Bacteroidetes/Firmicutes ratio, enriched microbial species of Akkermansia muciniphila, and increased SCFAs level. Taken together, this study demonstrated that andrographolide exerted a glucose-lowering effect through strengthening intestinal barrier function and increasing the microbial species of A. muciniphila, which illuminates a plausible approach to prevent T2D by regulating gut barrier integrity and shaping intestinal microbiota composition.

Metformin alleviates lead-induced mitochondrial fragmentation via AMPK/Nrf2 activation in SH-SY5Y cells

As a widely acknowledged environmental pollutant, lead (Pb) exhibits neurological toxicity primarily due to the vulnerability of neural system. It is suggested that Pb could perturb mitochondrial function, triggering the following disturbance of cellular homeostasis. Here, we focused on the role of mitochondrial dynamics in Pb-induced cell damage. Pb exposure enhanced mitochondrial fragmentation and elevated p-Drp1 (s616) level in a reactive oxygen species (ROS) dependent manner, leading to cell death and energy shortage. By applying metformin, an AMP-activated protein kinase (AMPK) activator, these impairments could be alleviated via activation of AMPK, validated by experiments of pharmacological inhibition of AMPK. Further investigation confirmed that nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor managing antioxidative function, and its downstream antioxidant detoxifying enzyme were activated by metformin, resulting in the inhibition of the Pb-caused oxidative stress. Moreover, Nrf2 mediated the protection of metformin against mitochondrial fragmentation induced by Pb exposure, while knockdown of Nrf2 abrogated the protective effect. Finally, the treatment of Mdivi-1, a mitochondrial fission inhibitor, reversed Pb-triggered cell death, revealing that excessive mitochondrial fission is detrimental. To conclude, metformin could ameliorate Pb-induced mitochondrial fragmentation via antioxidative effects originated from AMPK/Nrf2 pathway activation, promoting energy supply and cell survival.

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Pb caused mitochondrial fragmentation in a ROS dependent manner.

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Metformin alleviated Pb-induced mitochondrial fission via Nrf2 activation.

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AMPK mediated metformin-induced Nrf2 activation.

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Inhibition of mitochondrial fragmentation rescued Pb-induced cell death.

Cathelicidin Modulates Vascular Smooth Muscle Cell Phenotypic Switching through ROS/IL-6 Pathway

Vascular smooth muscle cells (VSMC) are stromal cells of the blood vessels and their differentiation is thought to be essential during atherosclerosis. Cathelicidin-related antimicrobial peptides (CRAMP) are suggested to play a role in the development of atherosclerosis. Even so, the relationship of CRAMP and VSMC remains unclear. The present study was to determine whether CRAMP regulates VSMC phenotypic transformation and underlying mechanisms. We demonstrated that CRAMP could reverse platelet-derived growth factor-BB (PDGF-BB)-induced VSMC phenotypic transformation, evidencing by increasing α-smooth muscle actin (α-SMA), smooth muscle 22α (SM22α) and decreasing of proliferation and migration. Further studies showed that CRAMP inhibited nuclear factor κB (NF-κB)-induced autocrine of interleukin-6 (IL-6), which further activated of janus kinase 2 (JAK2)/signal transducer and activator 3 (STAT3). Meanwhile, our data showed that CRAMP can significantly inhibit PDGF-BB enhanced intracellular reactive oxygen species (ROS) level which further affected the NF-κB signaling pathway, indicating that CRAMP can regulate the phenotypic transformation of VSMC by regulating oxidative stress. These results indicated that CRAMP regulated the differentiation of VSMC by inhibiting ROS-mediated IL-6 autocrine, suggesting that targeting CRAMP is a potential avenue for regulating the differentiation of VSMC and treatment of atherosclerosis.

AMPK/p38/Nrf2 activation as a protective feedback to restrain oxidative stress and inflammation in microglia stimulated with sodium fluoride

Dysregulated activation of inflammation plays an important role in the development and progression of neuronal damage, and limiting the production of reactive oxygen species (ROS) can suppress the inflammatory signals. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox-sensing transcription factor that drives an adaptive cellular defense in response to oxidative stress. However, the implications of Nrf2 in sodium fluoride (NaF)-stimulated microglia and the underlying mechanisms remain obscure. In this study, we demonstrated that NaF activated the Nrf2 signaling and enhanced the downstream antioxidant protein levels, including heme oxygenase-1 and quinine oxidoreductase 1. NaF induced oxidative stress, as indicated by increased ROS level and malondialdehyde content, and reduced superoxide dismutase activity. Moreover, NaF promoted the nuclear translocation of NF-κB, thus increased the production of the pro-inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-6, and IL-1β. However, these effects were relieved by overexpression of Nrf2. Meanwhile, knockdown of Nrf2 by shRNA exacerbated NaF-induced oxidative stress and inflammation in BV-2 cells and primary cultured microglia. Mechanistically, NaF-induced Nrf2 activation is AMPK/p38 dependent, as deletion of AMPK using siRNA blocked the activating effect of NaF on p38 and Nrf2. Notably, treatment of N-Acety-l-Cysteine attenuated AMPK/p38-dependent Nrf2 activation in microglia exposed to NaF. In conclusion, these data demonstrated for the first time that Nrf2 activation exerts a neuroprotective effect on NaF-stimulated redox imbalance and inflammation that is dependent on the AMPK/p38 pathway.

Defatted Rice Bran Supplementation in Diets of Finishing Pigs: Effects on Physiological, Intestinal Barrier, and Oxidative Stress Parameters

Simple Summary

Most studies on dietary fiber mainly focus on the digestibility of feed nutrients and microbial flora, etc. However, insufficient attention has been paid to the regulation of immune and oxidative stress of the intestinal tract by dietary fiber. This study investigated the effects of varying levels of defatted rice bran replacing corn on physiological, intestinal barrier, and oxidative stress parameters in finishing pigs. Based on the current findings, a high diet of rice bran will not only reduce the level of inflammatory factors in the peripheral blood of finishing pigs, but also enhance the healthy level of the colon through mucin2 and keap1-Nrf2 pathways. Our results can be used as reference for dietary rice bran to improve intestinal health in finishing pigs.

Abstract

Rice bran is a waste product with low cost and high fiber content, giving it an added advantage over corn and soybean meal, which have to be purchased and always at a relatively higher cost. Under the background of increased attention to sustainable agriculture, it is significant to find alternative uses for this byproduct. A total of 35 finishing pigs were allotted to five dietary treatments: a control group with basal diet and four experimental diets where corn was equivalently substituted by 7%, 14%, 21%, and 28% defatted rice bran (DFRB), respectively. With increasing levels of DFRB, the neutrophil to lymphocyte ratio (NLR) linearly decreased (p < 0.05). In the jejunum, the mRNA level of nuclear factor erythroid-2 related factor-2 (Nrf2) exhibited a quadratic response (p < 0.01) with incremental levels of DFRB. In the colon, the mRNA levels of mucin 2 (MUC2), Nrf2, and NAD(P)H: quinone oxidoreductase 1 (NQO1) were upregulated (linear, p < 0.05) and heme oxygenase-1 (HO-1) was upregulated (linear, p < 0.01). Overall, using DFRB to replace corn decreased the inflammatory biomarkers of serum and showed potential function in modulating the intestinal barrier by upregulating the mRNA expression levels of MUC2 and downregulating that of Nrf2, NQO1, and HO-1 in the colon.

A cathelicidin-related antimicrobial peptide suppresses cardiac hypertrophy induced by pressure overload by regulating IGFR1/PI3K/AKT and TLR9/AMPKα

Cathelicidin-related antimicrobial peptide (CRAMP), an antimicrobial peptide, was reported to protect against myocardial ischemia/reperfusion injury. However, the effect of CRAMP on pressure overload-induced cardiac hypertrophy was unknown. This study explored the role of CRAMP on cardiac hypertrophy. A cardiac hypertrophy mouse model was induced by aortic banding surgery. Seven days after surgery, mice were given mCRAMP by intraperitoneal injection (8 mg/kg/d) for 7 weeks. Cardiac hypertrophy was evaluated by the hypertrophic response and fibrosis level as well as cardiac function. Mice were also injected with AAV9-shCRAMP to knockdown CRAMP in the mouse heart. CRAMP levels first increased and then reduced in the remodeling heart, as well as in angiotensin II-stimulated endothelial cells but not in cardiomyocytes and fibroblasts. mCRAMP protected against the pressure overload-induced cardiac remodeling process, while CRAMP knockdown accelerated this process. mCRAMP reduced the inflammatory response and oxidative stress in the hypertrophic heart, while mCRAMP deficiency deteriorated the pressure overload-induced inflammatory response and oxidative stress. mCRAMP inhibited the angiotensin II-stimulated hypertrophic response and oxidative stress in neonatal rat cardiomyocytes, but mCRAMP did not help the angiotensin II-induced inflammatory response and oxidative stress in endothelial cells. Mechanistically, we found that mCRAMP suppressed the cardiac hypertrophic response by activating the IGFR1/PI3K/AKT pathway via directly binding to IGFR1. AKT knockout mice completely reversed the anti-hypertrophic effect of mCRAMP but not its anti-oxidative effect. We also found that mCRAMP ameliorated cardiac oxidative stress by activating the TLR9/AMPKa pathway. This was confirmed by a TLR9 knockout mouse experiment, in which a TLR9 knockout partly reversed the anti-hypertrophic effect of mCRAMP and completely counteracted the anti-oxidative effect of mCRAMP. In summary, mCRAMP protected against pressure overload-induced cardiac hypertrophy by activating both the IGFR1/PI3K/AKT and TLR9/AMPKa pathways in cardiomyocytes.

Effects of dietary tributyrin on intestinal mucosa development, mitochondrial function and AMPK-mTOR pathway in weaned pigs

Background

The objective of this experiment was to investigate the influence of dietary tributyrin on intestinal mucosa development, oxidative stress, mitochondrial function and AMPK-mTOR signaling pathway.

Methods

Seventy-two pigs were divided into two treatments and received either a basal diet or the same diet supplemented with 750 mg/kg tributyrin. Each treatment has six replicates of six pigs. After 14 days, 6 pigs from each treatment were selected and the jejunal samples were collected.

Results

Results showed that supplemental tributyrin increased (P < 0.05) villus height and villus height: crypt depth of weaned pigs. Pigs fed tributyrin had greater (P < 0.05) RNA/DNA and protein/DNA ratios than pigs on the control group. The mRNA levels of sodium glucose transport protein-1 and glucose transporter-2 in the jejunum were upregulated (P < 0.05) in pigs fed the tributyrin diet. Dietary tributyrin supplementation lowered (P < 0.05) the malondialdehyde and hydrogen peroxide (H₂O₂₎ content in jejunum, enhanced (P < 0.05) the mitochondrial function, as demonstrated by decreased (P < 0.05) reactive oxygen species level and increased (P < 0.05) mitochondrial membrane potential. Furthermore, tributyrin increased (P < 0.05) mitochondrial DNA content and the mRNA abundance of genes related to mitochondrial functions, including peroxisomal proliferator-activated receptor-γ coactivator-1α, mitochondrial transcription factor A, nuclear respiratory factor-1 in the jejunum. Supplementation with tributyrin elevated (P < 0.05) the phosphorylation level of AMPK and inhibited (P < 0.05) the phosphorylation level of mTOR in jejunum compared with the control group.

Conclusions

These findings suggest that dietary supplementation with tributyrin promotes intestinal mucosa growth, extenuates oxidative stress, improves mitochondrial function and modulates the AMPK-mTOR signal pathway of weaned pigs.

LKB1/p53/TIGAR/autophagy-dependent VEGF expression contributes to PM2.5-induced pulmonary inflammatory responses

One of the health hazards of PM2.5 exposure is to induce pulmonary inflammatory responses. In our previous study, we demonstrated that exposing both the immortalized and primary human bronchial epithelial cells to PM2.5 results in a significant upregulation of VEGF production, a typical signaling event to trigger chronic airway inflammation. Further investigations showed that PM2.5 exposure strongly induces ATR/CHK1/p53 cascade activation, leading to the induction of DRAM1-dependent autophagy to mediate VEGF expression by activating Src/STAT3 pathway. In the current study, we further revealed that TIGAR was another transcriptional target of p53 to trigger autophagy and VEGF upregulation in Beas-2B cells after PM2.5 exposure. Furthermore, LKB1, but not ATR and CHK1, played a critical role in mediating p53/TIGAR/autophagy/VEGF pathway activation also by linking to Src/STAT3 signaling cascade. Therefore, on combination of the previous report, we have identified both ATR/CHK1/p53/DRAM1- and LKB1/p53/TIGAR- dependent autophagy in mediating VEGF production in the bronchial epithelial cells under PM2.5 exposure. Moreover, the in vivo study further confirmed VEGF induction in the airway potentially contributed to the inflammatory responses in the pulmonary vascular endothelium of PM2.5-treated rats. Therefore, blocking VEGF expression or autophagy induction might be the valuable strategies to alleviating PM2.5-induced respiratory injuries.

Ethyl pyruvate inhibits LPS induced IPEC-J2 inflammation and apoptosis through p38 and ERK1/2 pathways

The endotoxin of Gram-negative bacteria threatens the intestinal health of livestock. Ethyl pyruvate (EP) has been shown to regulate intestinal immunity and protect against cell and tissue damage. In this study, it was first verified that EP could reduce the secretion of IL-8, TNF-α, IL-6 and IL-1β in LPS-induced IPEC-J2 cells. Then, we used RNA sequencing (RNA-seq) to analyze the differentially expressed genes (DEGs) of inflammatory factors induced by LPS in IPEC-J2 cells. It was found that LPS induced the upregulation of 377 genes and the downregulation of 477 genes compared to Vehicle; LPS+EP induced the upregulation of 258 genes and the downregulation of 240 genes compared to Vehicle; and LPS+EP induced the upregulation of 373 genes and the downregulation of 188 genes compared to LPS (fold change > 1.5 and FDR < 0.01). Their enrichment pathways included the MAPK signaling pathway, PI3K-Akt signaling pathway, Toll-like receptor signaling pathway, and other pathways. Furthermore, the mRNA level of cytokines associated with inflammation and apoptosis enriched in the MAPK pathway was verified by qRT-PCR. Western blots and immunofluorescence revealed that EP significantly inhibited phosphorylated p38 and phosphorylated-ERK1/2 protein expression levels (P < 0.05). The apoptosis due to LPS reduced by EP was significantly inhibited, as shown by Annexin V-FITC/PI staining. According to the results, EP inhibited the expression of IL-8, TNF-α, IL-6 and IL-1β as well as apoptosis by inhibiting the phosphorylation of p38 and ERK1/2 in LPS-induced IPEC-J2 cells.

Cytotoxicity and Anti-inflammatory Properties of Apigenin-Derived Isolaxifolin

The rare flavonoid isolaxifolin, a potent insecticide, has been touted as a potential grain-protecting agent. In order to assess any impact of this natural product on human health and to explore its various other biological properties, we have established a semisynthesis from the simpler but structurally related and more abundant natural product apigenin. The five-step reaction sequence has provided, for the first time, sufficient material for an in-depth evaluation of the cytotoxic properties of the title natural product. The impact of isolaxifolin on certain pro-inflammatory cytokines in murine macrophage RAW 264.7 cells has also been examined. Such studies have revealed that isolaxifolin displays no toxic effects toward normal cells while displaying greater cytotoxicities against certain cancer cell lines than its synthetic precursor apigenin. Furthermore, unlike apigenin, isolaxifolin only reduced NO, TNF-α, and IL-6 secretions in LPS-induced RAW 264.7 cells in a rather modest and dose-independent manner.

Corilagin alleviates acetaminophen-induced hepatotoxicity via enhancing the AMPK/GSK3β-Nrf2 signaling pathway

Background

Acetaminophen (APAP) overdose-induced acute liver failure (ALF) is mainly resulted from uncontrolled oxidative stress. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a key antioxidant transcription factor, is essential for alleviating APAP-induced hepatotoxicity. Corilagin (Cori) is a natural polyphenol compound that possesses effective antioxidant activity; however, the protective effect of Cori on APAP-induced hepatotoxicity is still unknown. The current study aimed to explore whether Cori could mitigate hepatotoxicity caused by APAP and the underlying molecular mechanisms of action.

Methods

Cell counting kit-8 (CCK-8) assays, Western blotting analysis, dual-luciferase reporter assays, a mouse model, CRISPR/Cas9 knockout technology, and hematoxylin-eosin (H & E) staining were employed to explore the mechanisms by which Cori exerts a protective effect on hepatotoxicity in HepG2 cells and in a mouse model.

Results

Our findings suggested that Cori efficiently decreased APAP-triggered the generation of reactive oxygen species (ROS) and cell death in HepG2 cells. Additionally, Cori significantly induced the expression of several antioxidant enzymes, and this induced expression was closely linked to the upregulation of Nrf2, inhibition of Keap1 protein expression, and promotion of antioxidant response element (ARE) activity in HepG2 cells. Moreover, Cori clearly induced the phosphorylation of AMP-activated protein kinase (AMPK), glycogen synthase kinase-3β (GSK3β), liver kinase B1 (LKB1) and acetyl-CoA carboxylase (ACC). Furthermore, Cori-mediated GSK3β inactivation, Nrf2 upregulation and cytoprotection were abolished by an AMPK inhibitor (Compound C) in HepG2 cells. Lastly, we found that Cori inhibited APAP-induced hepatotoxicity and mediated the expression of many antioxidant enzymes; these results were reversed in Nrf2 ^−/− HepG2 cells. In vivo, Cori significantly protected against APAP-induced ALF by reducing mortality and alanine transaminase (ALT) and aspartate aminotransferase (AST) levels, attenuating histopathological liver changes, inhibiting myeloperoxidase (MPO) and malondialdehyde (MDA) levels, and increasing the superoxide dismutase (SOD) content and GSH-to-GSSG ratio as well as suppressing c-jun N-terminal kinase (JNK) phosphorylation. However, Cori-induced reductions in mortality, AST and ALT levels, and histopathological liver changes induced by APAP were clearly abrogated in Nrf2-deficienct mice.

Conclusions

These findings principally indicated that Cori effectively protects against APAP-induced ALF via the upregulation of the AMPK/GSK3β-Nrf2 signaling pathway.