Progress on the study of Popeye domain-containing 3 (POPDC3) in malignancies and striated muscle function and homeostasis.

The Popeye domain-containing protein 3 (POPDC3), a transmembrane protein with a unique cyclic adenosine monophosphate (cAMP) binding site, is widely expressed in mammalian tissues, with the highest levels of expression in skeletal muscle. POPDC3 plays a key role in many physiological and pathological processes and is considered a candidate biomarker and potential therapeutic target of cancer. In addition, POPDC3 gene variants have been associated with limb-girdle muscular dystrophy (LGMD) type 26. However, there are only a few studies on the biological role of POPDC3, interacting proteins, potential downstream targets, and regulated signaling pathways. Therefore, this review focuses on the structure of POPDC3 protein, interacting molecules, and the role and mechanism in cancer, and in cardiac and skeletal muscle, and to review the current research progress of POPDC3 and propose possible future study directions.

[Effect of Dendrobium officinale superfine powder on stomach Yin deficiency model mice induced by "spicy overeating"].

Dendrobium officinale is a traditional Chinese medicine for nourishing Yin and benefiting stomach. Its superfine powder has many advantages, such as good dissolution, high utilization rate, strong integrity and easy to use. However, the researches on effect of D. officinale superfine powder on stomach Yin deficiency model are still not sufficient. In this experiment, we explored the effect of D. officinale superfine powder in mice model with stomach Yin deficiency caused by "spicy overeating", and provided certain reference value for its application in gastrointestinal diseases. Male ICR mice were randomly divided into normal group, model group, Yiweitang group, omeprazole group, and D. officinale superfine powder high, medium and low dose groups. The mixture of wine and pepper liquid was given by gavage administration for 30 d, and the corresponding drug was given for 60 d while the model was conti-nued. The body weight, food intake, water intake, fecal moisture content and particle number, foot temperature of mice were measured. The levels of serum gastrin(Gas), motilin(MTL) and somatostatin(SS) were measured by ELISA. Gastric histomorpho-logy was observed by HE staining. The expression levels of nuclear factor kappa B(NF-κB) and cyclooxygenase-2(COX-2) were determined by immunohistochemistry. The expression levels of B-cell lymphoma-2(Bcl-2) and Bcl-2 associated X protein(Bax) in gastric tissues were detected by Western blot. The results showed that D. officinale superfine powder could increase the food intake, water intake, fecal moisture content and particle number, reduce the foot temperature, improve the pathological changes of gastric mucosa, reduce the expression of NF-κB, COX-2 protein in gastric tissues, and increase the ratio of Bax/Bcl-2. D. officinale superfine powder can "nourish Yin and benefit the stomach", improve the syndrome of stomach Yin deficiency, such as "hunger but not want to eat, dry mouth but not want to drink, hand and feet hot, constipation", and reduce the damage of gastric mucosa. The mechanism may be related to regulating the secretion of gastrointestinal hormones, inhibiting the inflammation of gastric tissues and promoting the apoptosis of abnormal cells in gastric tissues.

[Effect of Dendrobium officinale on Yin deficiency constipation induced by warm-drying medicine in mice].

Dendrobium officinale is a sacred product for nourishing Yin and has a clear "thick gastrointestinal" effect. Modern pharmacological studies had found that it could improve gastrointestinal function. This study observed the improvement effect of D. officinale on constipation model mice with Yin deficiency caused by warm-drying medicine. It provided experimental basis for the treatment of Yin deficiency constipation. The male and female ICR mice were randomly divided into normal group, model group, D. officinale high, medium and low dose groups(0.6, 0.4, 0.2 g·kg~(-1)), and phenolphthalein tablets group. The model mice of Yin deficiency constipation were established by gavage with warm-drying medicine. The overall state and body temperature of the mice were observed and recorded. The number of feces, feces weight, fecal moisture content and intestinal propulsion were measured. The morphological damage of colon tissue was observed by hematoxylin-eosin(HE) staining. The expression of inducible nitric oxide synthase(iNOS) in the colon was detected by Western blot and immunohistochemical method. The expression of iNOS mRNA in the colon was detected by Real-time fluorescence quantitative PCR, and the serum cyclic guanosine phosphate(cGMP) level was detected the enzyme-linked immunosorbent assay(ELISA). The results showed that D. candidum could reduce the body temperature of mice with Yin deficiency constipation, increase the number of feces, wet feces, dry feces and intestinal propulsion ability, reduce the expression of iNOS protein and mRNA in the colon, and reduce the content of cGMP in the serum. It showed that D. candidum could improve the symptoms of Yin deficiency constipation mice caused by warm-drying medicine, and the mechanism may be related to reducing the expression of iNOS in the colon and increasing intestinal motility.

Epoxyeicosatrienoic acids inhibit the activation of NLRP3 inflammasome in murine macrophages.

Epoxyeicosatrienoic acids (EETs) derived from arachidonic acid exert anti-inflammation effects. We have reported that blocking the degradation of EETs with a soluble epoxide hydrolase (sEH) inhibitor protects mice from lipopolysaccharide (LPS)-induced acute lung injury (ALI). The underlying mechanisms remain essential questions. In this study, we investigated the effects of EETs on the activation of nucleotide-binding domain leucine-rich repeat-containing receptor, pyrin domain-containing-3 (NLRP3) inflammasome in murine macrophages. In an LPS-induced ALI murine model, we found that sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl), TPPU, profoundly attenuated the pathological injury and inhibited the activation of the NLRP3 inflammasome, characterized by the reduction of the protein expression of NLRP3, ASC, pro-caspase-1, interleukin precursor (pro-IL-1ß), and IL-1ß p17 in the lungs of LPS-treated mice. In vitro, primary peritoneal macrophages from C57BL/6 were primed with LPS and activated with exogenous adenosine triphosphate (ATP). TPPU treatment remarkably reduced the expression of NLRP3 inflammasome-related molecules and blocked the activation of NLRP3 inflammasome. Importantly, four EETs (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) inhibited the activation of NLRP3 inflammasome induced by LPS + ATP or LPS + nigericin in macrophages in various degree. While the inhibitory effect of 5,6-EET was the weakest. Mechanismly, EETs profoundly decreased the content of reactive oxygen species (ROS) and restored the calcium overload in macrophages receiving LPS + ATP stimulation. In conclusion, this study suggests that EETs inhibit the activation of the NLRP3 inflammasome by suppressing calcium overload and ROS production in macrophages, contributing to the therapeutic potency to ALI.

PTUPB ameliorates high-fat diet-induced non-alcoholic fatty liver disease via inhibiting NLRP3 inflammasome activation in mice.

Non-alcoholic fatty liver disease (NAFLD) affects 25% of the global adult population, and no effective pharmacological treatment has been found. Products of arachidonic acid metabolism have been developed into a novel therapy for metabolic syndrome and diabetes. It has been demonstrated that protective actions of a novel dual cyclooxygenase-2 (COX-2) and soluble epoxide hydrolase (sEH) inhibitor, PTUPB, on the metabolic abnormalities. Here, we investigated the effects of PTUPB on hepatic steatosis in high-fat diet (HFD)-induced obese mice, as well as in hepatocytes in vitro. We found that PTUPB treatment reduced body weight, liver weight, liver triglyceride and cholesterol content, and the expression of lipolytic/lipogenic and lipid uptake related genes (Acc, Cd36, and Cidec) in HFD mice. In addition, PTUPB treatment arrested fibrotic progression with a decrease of collagen deposition and expression of Col1a1, Col1a3, and α-SMA. In vitro, PTUPB decreased palmitic acid-induced lipid deposition and downregulation of lipolytic/lipogenic genes (Acc and Cd36) in hepatocytes. Additionally, we found that PTUPB reduced the production of pro-inflammatory cytokines and suppressed the NLRP3 inflammasome activation in HFD mice and hepatocytes. In conclusion, dual inhibition of COX-2/sEH attenuates hepatic steatosis by inhibiting the NLRP3 inflammasome activation. PTUPB might be a promising potential therapy for liver steatosis associated with obesity.

[Effect of Wubi Shanyao Pills on sexual dysfunction in rats with adenine-induced kidney-Yang deficiency].

The aim of this paper was to study the effect of Wubi Shanyao Pills on sexual dysfunction in rats with kidney-Yang deficiency and to investigate its possible mechanism. Adenine(100 mg·kg~(-1)) was administered to male SD rats for 8 weeks to establish kidney-Yang deficiency model, and at the same time, Wubi Shanyao Pills(2, 1, 0.5 g·kg~(-1)) were administered to rats for 8 weeks. The syndrome manifestation of kidney-Yang deficiency was observed in rats and the scores of symptoms were evaluated. Sexual behavior indexes(incubation period and times of capture, straddle and ejaculation) were measured by mating experiment. The levels of serum testosterone(T), estradiol(E_2), follicle stimulating hormone(FSH), luteinizing hormone(LH), and gonadotropin releasing hormone(GnRH) were measured by radioimmunoassay. The wet weights of testis and seminal vesicle were measured. The content of fructose in seminal plasma was detected by UV spectrophotometry. The pathological changes of testis and epididymis were observed by HE staining. The expression levels of transforming growth factor(TGF-ß1) and cytochrome P450 aromatase(CYP19) in testis were detected by immunohistochemistry and Western blot. The results showed that Wubi Shanyao Pills could significantly reduce the score of kidney-Yang deficiency syndrome, improve the symptoms of kidney-Yang deficiency syndrome, shorten capture, straddle and ejaculation latency, increase capture and straddle times, increase serum T, LH, FSH, E_2 and GnRH levels, increase the wet weight of testis and seminal vesicle and fructose content in seminal plasma, improve the pathological structure of testis and epididymis, and inhibit the expression of TGF-ß1 and increase CYP19 in testis of the model rats. Therefore, Wubi Shanyao Pills can significantly improve sexual dysfunction in rats with kidney-Yang deficiency, and its mechanism may be related to regulating the low function of hypothalamus pituitary gonad(HPG) axis and improving the disorder of sex hormone secretion. In addition, it may be also related to inhibiting the expression of testicular TGF-ß1, increasing the expression of CYP19 protein, and then regulating the amount of T converted to E_2.

Inhibition of glycolysis alleviates lipopolysaccharide-induced acute lung injury in a mouse model.

Gluconic metabolic reprogramming, immune response, and inflammation are intimately linked. Glycolysis involves in the pathologic progress in acute and chronic inflammatory diseases. However, the involvement of glycolysis in the acute lung injury (ALI) is still unclear. This study investigated the role of glycolysis in an animal model of ALI. First, we found that lactate content in serum was remarkably increased in ALI patients and a murine model induced by intratracheal administration of lipopolysaccharide (LPS). The key proteins involving in glycolysis were robustly elevated, including HK2, PKM2, and HIF-1α. Intriguingly, inhibition of glycolysis by 2-deoxyglucose (2-DG) pronouncedly attenuated the lung tissue pathological injury, accumulation of neutrophil, oxidative stress, expression of proinflammatory factors in the lung of ALI mice induced by LPS. The 2-DG treatment also strongly suppressed the activation of the NOD-like receptor (NLR) family and pyrin domain-containing protein 3 (NLRP3) inflammasome. Furthermore, we investigated the role of glycolysis in the inflammatory response of primary murine macrophages activated by LPS in vitro. We found that the 2-DG treatment remarkably reduced the expression of proinflammatory factors induced by LPS, including tumor necrosis factor-α messenger RNA (mRNA), pro-interleukin (IL)-1ß mRNA, pro-IL-18 mRNA, NLRP3 mRNA, caspase-1 mRNA, and IL-1ß protein. Altogether, these data provide a novel link between gluconic metabolism reprogramming and uncontrolled inflammatory response in ALI. This study suggests glycolytic inhibition as an effective anti-inflammatory strategy in treating ALI.

Vasoactive intestinal peptide inhibits the activation of murine fibroblasts and expression of interleukin 17 receptor C.

Acute respiratory distress syndrome (ARDS) is an acute, severe, and refractory pulmonary inflammation with high morbidity and mortality. Excessive activation of fibroblast during the fibroproliferative phase plays a pivotal role in the prognosis of ARDS. Our previous study demonstrated that the vasoactive intestinal peptide (VIP) is mediated by lentivirus attenuates lipopolysaccharide (LPS)-induced ARDS in a murine model, and VIP inhibits the release of interleukin-17A (IL-17A) from activation macrophages. However, the effects of VIP on the activation of murine fibroblast and expression of IL-17 receptor (IL-17R) in ARDS remain unclear. Here, a mouse model of ARDS was established by an intratracheal injection of LPS. We found that the gene expression of col3a1 and hydroxyproline contents in the lungs were significantly increased 24 h after LPS injection. IL-17RC rather than IL-17RA was increased in the lungs of mice with ARDS. In vitro, LPS activated NIH3T3 cells, which was suppressed by VIP in a dose-dependent manner. In detail, VIP reduced the hydroxyproline content and col3a1 messenger RNA induced by LPS in NIH3T3 cells, as well as the expression of α-smooth muscle actin. Furthermore, we found that VIP inhibited the expression of IL-17R in the lungs of mice with ARDS and NIH3T3 cells stimulated with LPS, which was partly inhibited by antagonists of protein kinase A and protein kinase C. Taken together, our results demonstrated that VIP inhibited the activation of fibroblast via downregulation of IL-17RC, which may contribute to the protective effects of VIP against ARDS in mice.

Heme oxygenase-1: A potential therapeutic target for improving skeletal muscle atrophy.

Skeletal muscle atrophy is a common muscle disease that is directly caused by an imbalance in protein synthesis and degradation. At the histological level, it is mainly characterized by a reduction in muscle mass and fiber cross-sectional area (CSA). Patients with skeletal muscle atrophy present with reduced motor ability, easy fatigue, and poor life quality. Heme oxygenase-1 (HO-1) is an inducible enzyme that catalyzes the degradation of heme and has attracted much attention for its anti-oxidation effects. In addition, there is growing evidence that HO-1 plays an important role in anti-inflammatory, anti-apoptosis, pro-angiogenesis, and maintaining skeletal muscle homeostasis, making it a potential therapeutic target for improving skeletal muscle atrophy. Here, we review the pathogenesis of skeletal muscle atrophy, the biology of HO-1 and its regulation, and the biological function of HO-1 in skeletal muscle homeostasis, with a specific focus on the role of HO-1 in skeletal muscle atrophy, aiming to observe the therapeutic potential of HO-1 for skeletal muscle atrophy.

Exercise intervention mitigates zebrafish age-related sarcopenia via alleviating mitochondrial dysfunction.

Sarcopenia is a common disorder that leads to a progressive decrease in skeletal muscle function in elderly people. Exercise effectively prevents or delays the onset and progression of sarcopenia. However, the molecular mechanisms underlying how exercise intervention improves skeletal muscle atrophy remain unclear. In this study, we found that 21-month-old zebrafish had a decreased swimming ability, reduced muscle fibre cross-sectional area, unbalanced protein synthesis, and degradation, increased oxidative stress, and mitochondrial dysfunction, which suggests zebrafish are a valuable model for sarcopenia. Eight weeks of exercise intervention attenuated these pathological changes in sarcopenia zebrafish. Moreover, the effects of exercise on mitochondrial dysfunction were associated with the activation of the AMPK/SIRT1/PGC-1α axis and 15-PGDH downregulation. Our results reveal potential therapeutic targets and indicators to treat age-related sarcopenia using exercise intervention.

Aerobic exercise enhances mitochondrial homeostasis to counteract D-galactose-induced sarcopenia in zebrafish.

Sarcopenia is a common skeletal muscle degenerative disease characterized by decreased skeletal muscle mass and mitochondrial dysfunction that involves microRNAs (miR) as regulatory factors in various pathways. Exercise reduces age-related oxidative damage and chronic inflammation and increases autophagy, among others. Moreover, whether aerobic exercise can regulate mitochondrial homeostasis by modulating the miR-128/insulin-like growth factor-1 (IGF-1) signaling pathway and can improve sarcopenia requires further investigation. Interestingly, zebrafish have been used as a model for aging research for over a decade due to their many outstanding advantages. Therefore, we established a model of zebrafish sarcopenia using d-galactose immersion and observed substantial changes, including reduced skeletal muscle cross-sectional area, increased tissue fibrosis, decreased motility, increased skeletal muscle reactive oxygen species, and notable alterations in mitochondrial morphology and function. We found that miR-128 expression was considerably upregulated, where as Igf1 and peroxisome proliferator-activated receptor gamma coactivator 1-alpha were significantly downregulated; moreover, mitochondrial homeostasis was reduced. Four weeks of aerobic exercise delayed sarcopenia progression and prevented the disruption of mitochondrial function and homeostasis. The genes related to atrophy and miR-128 were downregulated, Igf1 expression was considerably upregulated, and the phosphorylation levels of Pi3k, Akt, and Foxo3a were upregulated. Furthermore, mitochondrial respiration and homeostasis were enhanced. In conclusion, aerobic exercise improved skeletal muscle quality and function via the miR-128/IGF-1 signaling pathway, consequently ameliorating mitochondrial homeostasis in aging skeletal muscle.

A High-Fat Diet Induces Muscle Mitochondrial Dysfunction and Impairs Swimming Capacity in Zebrafish: A New Model of Sarcopenic Obesity.

Obesity is a highly prevalent disease that can induce metabolic syndrome and is associated with a greater risk of muscular atrophy. Mitochondria play central roles in regulating the physiological metabolism of skeletal muscle; however, whether a decreased mitochondrial function is associated with impaired muscle function is unclear. In this study, we evaluated the effects of a high-fat diet on muscle mitochondrial function in a zebrafish model of sarcopenic obesity (SOB). In SOB zebrafish, a significant decrease in exercise capacity and skeletal muscle fiber cross-sectional area was detected, accompanied by high expression of the atrophy-related markers Atrogin-1 and muscle RING-finger protein-1. Zebrafish with SOB exhibited inhibition of mitochondrial biogenesis and fatty acid oxidation as well as disruption of mitochondrial fusion and fission in atrophic muscle. Thus, our findings showed that muscle atrophy was associated with SOB-induced mitochondrial dysfunction. Overall, these results showed that the SOB zebrafish model established in this study may provide new insights into the development of therapeutic strategies to manage mitochondria-related muscular atrophy.

Identification of Potentially Related Genes and Mechanisms Involved in Skeletal Muscle Atrophy Induced by Excessive Exercise in Zebrafish.

Long-term imbalance between fatigue and recovery may eventually lead to muscle weakness or even atrophy. We previously reported that excessive exercise induces pathological cardiac hypertrophy. However, the effect of excessive exercise on the skeletal muscles remains unclear. In the present study, we successfully established an excessive-exercise-induced skeletal muscle atrophy zebrafish model, with decreased muscle fiber size, critical swimming speed, and maximal oxygen consumption. High-throughput RNA-seq analysis identified differentially expressed genes in the model system compared with control zebrafish. Gene ontology and KEGG enrichment analysis revealed that the upregulated genes were enriched in autophagy, homeostasis, circadian rhythm, response to oxidative stress, apoptosis, the p53 signaling pathway, and the FoxO signaling pathway. Protein-protein interaction network analysis identified several hub genes, including keap1b, per3, ulk1b, socs2, esrp1, bcl2l1, hsp70, igf2r, mdm2, rab18a, col1a1a, fn1a, ppih, tpx2, uba5, nhlrc2, mcm4, tac1, b3gat3, and ddost, that correlate with the pathogenesis of skeletal muscle atrophy induced by excessive exercise. The underlying regulatory pathways and muscle-pressure-response-related genes identified in the present study will provide valuable insights for prescribing safe and accurate exercise programs for athletes and the supervision and clinical treatment of muscle atrophy induced by excessive exercise.

Recent advances in studies of 15-PGDH as a key enzyme for the degradation of prostaglandins.

15-hydroxyprostaglandin dehydrogenase (15-PGDH; encoded by HPGD) is ubiquitously expressed in mammalian tissues and catalyzes the degradation of prostaglandins (PGs; mainly PGE2, PGD2, and PGF2α) in a process mediated by solute carrier organic anion transport protein family member 2A1 (SLCO2A1; also known as PGT, OATP2A1, PHOAR2, or SLC21A2). As a key enzyme, 15-PGDH catalyzes the rapid oxidation of 15-hydroxy-PGs into 15-keto-PGs with lower biological activity. Increasing evidence suggests that 15-PGDH plays a key role in many physiological and pathological processes in mammals and is considered a potential pharmacological target for preventing organ damage, promoting bone marrow graft recovery, and enhancing tissue regeneration. Additionally, results of whole-exome analyses suggest that recessive inheritance of an HPGD mutation is associated with idiopathic hypertrophic osteoarthropathy. Interestingly, as a tumor suppressor, 15-PGDH inhibits proliferation and induces the differentiation of cancer cells (including those associated with colorectal, lung, and breast cancers). Furthermore, a recent study identified 15-PGDH as a marker of aging tissue and a potential novel therapeutic target for resisting the complex pathology of aging-associated diseases. Here, we review and summarise recent information on the molecular functions of 15-PGDH and discuss its pathophysiological implications.

Vasoactive intestinal peptide suppresses the NLRP3 inflammasome activation in lipopolysaccharide-induced acute lung injury mice and macrophages.

Vasoactive intestinal peptide (VIP) is a neuropeptide that exerts anti-inflammatory functions. We have reported that VIP mediated by lentivirus attenuates acute lung injury (ALI) in lipopolysaccharide (LPS)-induced murine model. However, the exact role of VIP in uncontrolled inflammation during ALI is largely unknown. Accumulating evidence indicates that the NLRP3 inflammasome has a critical role during ALI. In this study, we investigated the effects of VIP on the activation of NLRP3 inflammasome during the development of ALI in mice. Seven days after the intratracheal injection of VIP-lentivirus, a murine ALI model was induced by intratracheal injection of LPS. VIP-lentivirus significantly reduced the expression of NLRP3 inflammasome components in lung tissue, including NLRP3, pro-caspase-1, pro-IL-1ß, and pro-IL-18. VIP-lentivirus also inhibited the formation of caspase-1 p10 and the maturation of IL-1ß and IL-18. In vitro, exogenous VIP pre-treatment inhibited the priming of NLRP3 inflammasome in murine primary peritoneal macrophages, indicated by down-regulation of expression of NLRP3 inflammasome components. VIP pre-treatment effectively prevented the LPS-induced degradation of I-κB and the synthesis of the downstream of NF-κB, including TNF-α and IL-17A. Furthermore, VIP pre-treatment pronouncedly suppressed the autoproteolysis of caspase-1 and the secretion of IL-1ß and IL-18 induced by LPS plus ATP in macrophages. In addition, VIP inhibited the generation of reactive oxygen species in macrophages by decreasing NOX1 and NOX2 expression. These findings illustrate one mechanism that VIP attenuates ALI induced by LPS through inhibiting the activation of the NLRP3 inflammasome and encourage further studies assessing the therapeutic potential of VIP to ALI.

A COX-2/sEH dual inhibitor PTUPB ameliorates cecal ligation and puncture-induced sepsis in mice via anti-inflammation and anti-oxidative stress.

Arachidonic acid can be metabolized to prostaglandins and epoxyeicosatrienoic acids (EETs) by cyclooxygenase-2 (COX-2) and cytochrome P450 (CYP), respectively. While protective EETs are degraded by soluble epoxide hydrolase (sEH) very fast. We have reported that dual inhibition of COX-2 and sEH with specific inhibitor PTUPB shows anti-pulmonary fibrosis and renal protection. However, the effect of PTUPB on cecal ligation and puncture (CLP)-induced sepsis remains unclear. The current study aimed to investigate the protective effects of PTUPB against CLP-induced sepsis in mice and the underlying mechanisms. We found that COX-2 expressions were increased, while CYPs expressions were decreased in the liver, lung, and kidney of mice undergone CLP. PTUPB treatment significantly improved the survival rate, reduced the clinical scores and systemic inflammatory response, alleviated liver and kidney dysfunction, and ameliorated the multiple-organ injury of the mice with sepsis. Besides, PTUPB treatment reduced the expression of hypoxia-inducible factor-1α in the liver, lung, and kidney of septic mice. Importantly, we found that PTUPB treatment suppressed the activation of NLRP3 inflammasome in the liver and lung of septic mice. Meanwhile, we found that PTUPB attenuated the oxidative stress, which contributed to the activation of NLRP3 inflammasome. Altogether, our data, for the first time, demonstrate that dual inhibition of COX-2 and sEH with PTUPB ameliorates the multiple organ dysfunction in septic mice.

COX-2/sEH dual inhibitor PTUPB alleviates bleomycin-induced pulmonary fibrosis in mice via inhibiting senescence.

Pulmonary fibrosis (PF) is a senescence-associated disease with poor prognosis. Currently, there is no effective therapeutic strategy for preventing and treating the disease process. Mounting evidence suggests that arachidonic acid (ARA) metabolites are involved in the pathogenesis of various fibrosis. However, the relationship between the metabolism of ARA and PF is still elusive. In this study, we observed a disorder in the cyclooxygenase-2/cytochrome P450 (COX-2/CYP) metabolism of ARA in the lungs of PF mice induced by bleomycin (BLM). Therefore, we aimed to explore the role of COX-2/CYP-derived ARA metabolic disorders in PF. PTUPB, a dual COX-2 and soluble epoxide hydrolase (sEH) inhibitor, was used to restore the balance of COX-2/CYP metabolism. sEH is an enzyme hydrolyzing epoxyeicosatrienoic acids derived from ARA by CYP. We found that PTUPB alleviated the pathological changes in lung tissue and collagen deposition, as well as reduced senescence marker molecules (p16Ink4a and p53-p21Waf1/Cip1 ) in the lungs of mice treated by BLM. In vitro, we found that PTUPB pretreatment remarkably reduced the expression of senescence-related molecules in the alveolar epithelial cells (AECs) induced by BLM. In conclusion, our study supports the notion that the COX-2/CYP-derived ARA metabolic disorders may be a potential therapeutic target for PF via inhibiting the cellular senescence in AECs.

A COX-2/sEH dual inhibitor PTUPB alleviates lipopolysaccharide-induced acute lung injury in mice by inhibiting NLRP3 inflammasome activation.

Rationale: Dysregulation of arachidonic acid (ARA) metabolism results in inflammation; however, its role in acute lung injury (ALI) remains elusive. In this study, we addressed the role of dysregulated ARA metabolism in cytochromes P450 (CYPs) /cyclooxygenase-2 (COX-2) pathways in the pathogenesis of lipopolysaccharide (LPS)-induced ALI in mice. Methods: The metabolism of CYPs/COX-2-derived ARA in the lungs of LPS-induced ALI was investigated in C57BL/6 mice. The COX-2/sEH dual inhibitor PTUPB was used to establish the function of CYPs/COX-2 dysregulation in ALI. Primary murine macrophages were used to evaluate the underlying mechanism of PTUPB involved in the activation of NLRP3 inflammasome in vitro. Results: Dysregulation of CYPs/COX-2 metabolism of ARA occurred in the lungs and in primary macrophages under the LPS challenge. Decrease mRNA expression of Cyp2j9, Cyp2j6, and Cyp2j5 was observed, which metabolize ARA into epoxyeicosatrienoic acids (EETs). The expressions of COX-2 and soluble epoxide hydrolase (sEH), on the other hand, was significantly upregulated. Pre-treatment with the dual COX-2 and sEH inhibitor, PTUPB, attenuated the pathological injury of lung tissues and reduced the infiltration of inflammatory cells. Furthermore, PTUPB decreased the pro-inflammatory factors, oxidative stress, and activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in LPS-induced ALI mice. PTUPB pre-treatment remarkably reduced the activation of macrophages and NLRP3 inflammasome in vitro. Significantly, both preventive and therapeutic treatment with PTUPB improved the survival rate of mice receiving a lethal dose of LPS. Conclusion: The dysregulation of CYPs/COX-2 metabolized ARA contributes to the uncontrolled inflammatory response in ALI. The dual COX-2 and sEH inhibitor PTUPB exerts anti-inflammatory effects in treating ALI by inhibiting the NLRP3 inflammasome activation.

Endoplasmic reticulum stress contributes to NMDA-induced pancreatic ß-cell dysfunction in a CHOP-dependent manner.

AIMS: Accumulating evidence suggest that endoplasmic reticulum (ER) stress is an important mechanism underlying the development of diabetes. We have reported that sustained treatment with N-methyl-d-aspartate (NMDA) results in apoptotic ß-cell death and impairs insulin secretion. However, the molecular mechanism responsible for NMDA-induced ß-cell dysfunction remains largely obscure. Thus, this study aimed to determine whether sustained activation of NMDA receptors (NMDARs) causes ß-cell dysfunction through ER stress. MAIN METHODS: Primary mouse islets and MIN6 mouse pancreatic ß-cells were treated with NMDA for 24 h or high-glucose for 72 h. After the treatment, glucose-stimulated insulin secretion (GSIS) and the expression of ER stress markers were measured, respectively. In vivo, the expression of ER stress markers was measured in the pancreas of diabetic mice treated with or without NMDARs inhibitor Memantine. KEY FINDINGS: NMDA treatment caused an increase in the expression of ER stress markers (ATF4, CHOP, GRP78, and Xbp1s) in primary islets. While, tauroursodeoxycholic acid (TUDCA), an inhibitor of ER stress, significantly attenuated NMDA-induced ß-cell dysfunction, including the loss of glucose-stimulated insulin secretion and reduction of pancreas duodenum homeobox factor-1 (Pdx-1) mRNA expression, a transcription factor regulating insulin synthesis. Besides, NMDA-induced ER stress strongly promoted pro-inflammatory cytokines synthesis (IL-1ß and TNF-α) in ß cells. Interestingly, knockdown of CHOP attenuated ß-cell dysfunction evoked by NMDA. Furthermore, we demonstrated that blockade of NMDARs ameliorated high-glucose-induced ER stress in vitro and in vivo. SIGNIFICANCE: This study confirms that ER stress is actively involved in the activation of NMDARs-related ß-cell dysfunction.

Dihydroartemisinin attenuates lipopolysaccharide­induced acute lung injury in mice by suppressing NF­κB signaling in an Nrf2­dependent manner.

Acute lung injury (ALI) is a severe health issue with significant morbidity and mortality. Artemisinin is used for the treatment of fever and malaria in clinical practice. Dihydroartemisinin (DHA), the major active metabolite of artemisinin, plays a role in anti­organizational fibrosis and anti­neuronal cell death. However, whether DHA can attenuate ALI remains unclear. The current study thus examined the effects of DHA on ALI and primary macrophages. The results revealed that DHA attenuated lipopolysaccharide (LPS)­induced pulmonary pathological damage. DHA suppressed the LPS­induced infiltration of inflammatory cells, the elevation of myeloperoxidase activity, oxidative stress and the production of pro­inflammatory cytokines, including interleukin (IL)­1ß, tumor necrosis factor­α, and IL­6. Furthermore, DHA reduced the LPS­induced inflammatory response by suppressing the degradation of I­κB and the nuclear translocation of nuclear factor κ­light­chain­enhancer of activated B cells (NF­κB)/p65 in vivo and in vitro. DHA activated the nuclear factor­erythroid 2 related factor 2 (Nrf2) pathway, which was suppressed by LPS treatment. The Nrf2 inhibitor, ML385, diminished the protective effects of DHA against LPS­induced inflammation in macrophages. On the whole, the findings of this study demonstrate that DHA exerts therapeutic effects against LPS­induced ALI by inhibiting the Nrf2­mediated NF­κB activation in macrophages. The present study also confirmed the therapeutic effects of DHA in mice with LPS­induced ALI. Thus, these findings demonstrate that DHA exhibits anti­inflammatory activities and may be a therapeutic candidate for the treatment of ALI.