Evidence from an Avian Embryo Model that Zinc-Inducible MT4 Expression Protects Mitochondrial Function Against Oxidative Stress

BACKGROUND

Metallothioneins (MTs) have a strong affinity for zinc (Zn) and remain at a sufficiently high level in mitochondria. As the avian embryo is highly susceptible to oxidative damage and relatively easy to manipulate in a naturally closed chamber, it is an ideal model of the effects of oxidative stress on mitochondrial function. However, the protective roles and molecular mechanisms of Zn-inducible protein expression on mitochondrial function in response to various stressors are poorly understood.

OBJECTIVES

The study aimed to investigate the mechanisms by which Zn-induced MT4 expression protects mitochondrial function and energy metabolism subjected to oxidative stress using the avian embryo and embryonic primary hepatocyte models.

METHODS

First, we investigated whether MT4 expression alters mitochondrial function. Then, we examined the effects of Zn-induced MT4 overexpression and MT4 silencing on embryonic primary hepatocytes from breeder hens fed a normal Zn diet subjected to a tert-butyl hydroperoxide (BHP) oxidative stress challenge during incubation. In vivo, the avian embryos from hens fed the Zn-deficient and Zn-adequate diets were used to determine the protective roles of Zn-induced MT4 expression on the function of mitochondria exposed to oxidative stress induced by in ovo BHP injection.

RESULTS

An in vitro study revealed that Zn-induced MT4 expression reduced reactive oxygen species accumulation in primary hepatocytes. MT4 silencing exacerbated BHP-mediated mitochondrial dysfunction whereas Zn-inducible MT4 overexpression mitigated it. Another in vivo study disclosed that maternal Zn-induced MT4 expression protected mitochondrial function in chick embryo hepatocytes against oxidative stress by inhibiting the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)/peroxisome proliferators-activated receptor-γ (PPAR-γ) pathway.

CONCLUSION

This study underscores the potential protective roles of Zn-induced MT4 expression via the downregulation of the PGC-1α/PPAR-γ pathway on mitochondrial function stimulated by the stress challenge in the primary hepatocytes in an avian embryo model. Our findings suggested that Zn-induced MT4 expression could provide a new therapeutic target and preventive strategy for repairing mitochondrial dysfunction in disease.

Icariin promotes bone marrow mesenchymal stem cells osteogenic differentiation via the mTOR/autophagy pathway to improve ketogenic diet-associated osteoporosis

BACKGROUND

Icariin, a traditional Chinese medicine, has demonstrated anti-osteoporotic properties in ovariectomized mice. However, its effectiveness in preventing bone loss induced by ketogenic diet (KD), which mimics osteoporosis in human, remains unexplored. This study aims to investigate icariin's impact on KD-induced bone loss in mice.

METHODS

Thirty mice were divided into: sham, KD, and KD + icariin groups. Post a 12-week intervention, evaluation including bone microstructures, serum concentrations of tartrate-resistant acid phosphatase (TRAP) and bone-specific alkaline phosphatase (ALP), and femoral tissue expression levels of osteocalcin (OCN) and TRAP. The expression levels of mammalian target of rapamycin (mTOR), ALP, peroxisome proliferator-activated receptor gamma (PPAR-γ), phosphorylated mTOR (p-mTOR), and the autophagy adaptor protein (p62) were also analyzed. Alizarin granule deposition and cellular ALP levels were measured following the induction of bone marrow mesenchymal stem cells (BMSCs) into osteogenesis.

RESULTS

The study found that KD significantly impaired BMSCs' osteogenic differentiation, leading to bone loss. Icariin notably increased bone mass, stimulated osteogenesis, and reduced cancellous bone loss. In the KD + icariin group, measures such as bone tissue density (TMD), bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were significantly higher than in the KD group. Additionally, bone trabecular separation (Tb.Sp) was markedly lower in the KD + icariin group. Moreover, icariin increased OCN and ALP levels while suppressing PPAR-γ, TRAP, p62, and p-mTOR. In cellular studies, icariin encouraged osteogenic development in BMSCs under KD conditions.

CONCLUSIONS

Icariin effectively counteracts bone thinning and improves bone microstructure. Its mechanism likely involves stimulating BMSCs osteogenic differentiation and inhibiting bone resorption, potentially through mTOR downregulation. These findings suggest icariin's potential as an alternative treatment for KD-induced bone loss.

PDK4 inhibits osteoarthritis progression by activating the PPAR pathway

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease caused by the deterioration of cartilage. However, the underlying mechanisms of OA pathogenesis remain elusive.

METHODS

Hub genes were screened by bioinformatics analysis based on the GSE114007 and GSE169077 datasets. The Sprague-Dawley (SD) rat model of OA was constructed by intra-articular injection of a mixture of papain and L-cysteine. Hematoxylin-eosin (HE) staining was used to detect pathological changes in OA rat models. Inflammatory cytokine levels in serum were measured employing the enzyme-linked immunosorbent assay (ELISA). The reverse transcription quantitative PCR (RT-qPCR) was implemented to assess the hub gene expressions in OA rat models. The roles of PDK4 and the mechanism regulating the PPAR pathway were evaluated through western blot, cell counting kit-8 (CCK-8), ELISA, and flow cytometry assays in C28/I2 chondrocytes induced by IL-1β.

RESULTS

Six hub genes were identified, of which COL1A1, POSTN, FAP, and CDH11 expressions were elevated, while PDK4 and ANGPTL4 were reduced in OA. Overexpression of PDK4 inhibited apoptosis, inflammatory cytokine levels (TNF-α, IL-8, and IL-6), and extracellular matrix (ECM) degradation protein expressions (MMP-3, MMP-13, and ADAMTS-4) in IL-1β-induced chondrocytes. Further investigation revealed that PDK4 promoted the expression of PPAR signaling pathway-related proteins: PPARA, PPARD, and ACSL1. Additionally, GW9662, an inhibitor of the PPAR pathway, significantly counteracted the inhibitory effect of PDK4 overexpression on IL-1β-induced chondrocytes.

CONCLUSION

PDK4 inhibits OA development by activating the PPAR pathway, which provides new insights into the OA management.

Resveratrol ameliorates intestinal lipid metabolism through the PPAR signaling pathway in high-fat diet-fed red tilapia (Oreochromis niloticus)

Feeding high-fat (HF) diets has been shown to cause hepatic and intestinal impairment in fish species, but the mode of action, especially the pathways involved in the intestine, has not been determined yet. In this study, the effects of resveratrol (RES) supplementation on the intestinal structure, microbial flora, and fat metabolism in red tilapia (Oreochromis niloticus) were determined. The results showed RES maintained the structural integrity of the intestine and significantly increased the number of goblet cells in the midgut. RES significantly induced interferon (IL)-1β, IL-6, IL-10, and tumor necrosis factor (TNF)-α, serumal and fecal trimetlylamine oxide (TMAO) and lipopolysaccharides (LPS), intestinal acetic acid levels. However, the concentrations of bound bile acids increased in HF-fed red tilapia. Atp5fa1 and Pafah1b3 significantly increased, Pmt and Acss2 significantly decreased, respectively, with RES supplementation, which was alleviated and retained at the same level in the selisistat (EX527) group. While for transcriptome and proteomics results, RES was found to promote fatty acid β-oxidation and arachidonic acid metabolism associated with the peroxisome proliferator-activated receptor (PPAR) signaling pathway. The next validation experiment showed some genes related to apoptosis and fatty acid metabolism pathways were altered by RES supplementation. Namely, sn6, loc100702698, new_14481, and prkaa1 were upregulated, while ffrs1, ap3s1, and loc100705861 were downregulated. RES significantly increased Planctomycetes and Verrucomicrobia while decreased Moonvirus, Citrobacter, and Pseudomonas. Akkermansia and Fusobacterium significantly increased and Aeromonas significantly decreased. Thus, unsaturated fatty acid biosynthesis significantly increased and carbohydrate/energy metabolism decreased. To conclude, RES enabled the body to complete fatty acid β-oxidation and arachidonic acid metabolism, whereas the addition of inhibitors increased the expression of the phagosome transcriptome and reduced fatty acid β-oxidative metabolism.

Effect of nitro-conjugated linoleic acid on the inflammatory response of murine macrophages activated with lipopolysaccharide derived from Prevotella intermedia

Nitro-conjugated linoleic acid (NO2-CLA) has been observed to manifest salutary signaling responses, including anti-inflammatory and antioxidant properties. Here, the authors have explored the influence and underlying mechanisms of NO2-CLA on the proinflammatory reaction of murine macrophages that were challenged with lipopolysaccharide (LPS) derived from Prevotella intermedia, a putative periodontopathic bacterium. Treatment of LPS-activated RAW264.7 cells with NO2-CLA notably dampened the secretion of iNOS-derived NO, IL-1β and IL-6 as well as their gene expressions and significantly enhanced the markers for M2 macrophage polarization. NO2-CLA promoted the HO-1 expression in cells challenged with LPS, and tin protoporphyrin IX, an HO-1 inhibitor, significantly reversed the NO2-CLA-mediated attenuation of NO secretion, but not IL-1β or IL-6. We found that cells treated with NO2-CLA significantly increased mRNA expression of PPAR-γ compared to control cells, and NO2-CLA significantly reverted the decrease in PPAR-γ mRNA caused by LPS. Nonetheless, antagonists to PPAR-γ were unable to reverse the NO2-CLA-mediated suppression of inflammatory mediators. In addition, NO2-CLA did not alter the p38 and JNK activation elicited by LPS. Both NF-κB reporter activity and IκB-α degradation caused by LPS were notably diminished by NO2-CLA. NO2-CLA was observed to interrupt the nuclear translocation and DNA binding of p50 subunits caused by LPS with no obvious alterations in p65 subunits. Further, NO2-CLA attenuated the phosphorylation of STAT1/3 elicited in response to LPS. We propose that NO2-CLA could be considered as a possible strategy for the therapy of periodontal disease, although additional researches are certainly required to confirm this.

Chlorogenic acid improves the cognitive deficits of sleep-deprived mice via regulation of immunity function and intestinal flora

BACKGROUND

Sleep deprivation (SD) has become a global health concern with serious consequences containing memory deficits and gastrointestinal dysfunctions. The gut-brain axis serves as a crucial link between the brain and gut, and the utilization of chlorogenic acid (CGA) presents a compelling strategy for mitigating or potentially resolving various neuroinflammation-associated disorders. However, it is still unknown how CGA may interact with the gut, microbiota and the brain during SD.

PURPOSE

This study aims to explore the therapeutic effect and underlying mechanism of microbiota-gut-brain axis by which CGA prevents SD-induced cognitive deficits.

STUDY DESIGN AND METHODS

CGA (30, 60 mg/kg.bw.) was gavaged to C57BL/6 mice, and then they were submitted to 48-h SD. The cognitive and spatial learning abilities were investigated through behavioral tests. Furthermore, we explored the action mechanism of this compound with haematological analysis, histopathological examination, Western blot, ELISA and 16S rRNA gene pyrosequencing from colonic contents.

RESULTS

The cognitive deficits induced by SD were significantly relieved by administration of CGA in a dose-dependent manner. The hematoxylin and eosin staining of hippocampus and colon tissues indicated that pretreatment of CGA not only protected brain tissue from SD, but also maintained intestinal integrity. In the hippocampus, the increased pro-inflammatory neurometabolites were significantly prevented by CGA, and an immune profile capable of hippocampal-dependent spatial memory was improved via Nrf2/PPAR signaling pathways. The observed immunomodulatory effect was concomitant with augmentation of the intestinal barrier, as evidenced by the heightened expressions of tight junction proteins. 16S rRNA analysis of colonic contents revealed that levels of Clostridia_UCG-014 and lipopolysaccharide were significantly inhibited, and those of Lactobacillus and intestinal tight junction proteins were upregulated in the CGA group. Pathways of ko05322 (immune disease) and ko04610 (immune system) were significantly regulated by CGA. Based on PICRUSt2 algorithm, CGA probably influenced gut microbial functions via several metabolism pathways, such as arginine biosynthesis, pyrimidine metabolism and purine metabolism.

CONCLUSION

The present study first proved the efficacy and mechanism of CGA in alleviating SD-induced cognitive impairment and neuroinflammation via creating a systemic protection, a bidirectional communication system connecting the gut with the brain. The intestinal barrier improvement and the reshaped "SD microbiota" profiles restored immunity functions, which were probably the main contributors to Nrf2/PPAR activation and the neuroprotective effect of CGA. Overall, this work provided novel insights of CGA, which might guide the more reasonable clinical use of CGA in the pathogenesis of sleep-related disorders.

Mechanistic aspects of ameliorative effects of Eicosapentanoic acid ethyl ester on methotrexate-evoked testiculopathy in rats

Disrupted spermatogenesis and testicular injury are among the devastating outcomes of methotrexate. A major contributor to methotrexate-induced testiculopathy is oxidative damage which triggers apoptosis and altered autophagy responses. Eicosapentaenoic acid ethyl ester (EPA-E) is an antihyperlipidemic derivative of omega-3 fatty acids that exhibited affinity to peroxisome proliferator-activated receptor-γ (PPAR-γ) that possesses both antioxidant and autophagy modulating properties. This is an exploratory study aiming at assessing the effectiveness of EPA-E to alleviate testicular damage induced by methotrexate. The specific exploratory hypothesis of this experiment is: EPA-E administration for 1 week to methotrexate-treated rats reduces testicular damage compared to control rats. As a secondary outcome, we were interested in identifying the implicated mechanism that mediates the action of EPA-E. In adult male Wistar rats, testiculopathy was achieved by a single methotrexate injection (20 mg/kg, ip). Rats received vehicle, EPA-E (0.3 g/kg/day, po) alone or with selective PPAR-γ antagonist (bisphenol A diglycidyl ether, BADGE) at 30 mg/kg/day, ip for 1 week. EPA-E recuperated methotrexate-attenuated serum total testosterone while reduced testicular inflammation and oxidative stress, restoring superoxide dismutase (SOD) while reducing malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Methotrexate-induced testicular apoptosis (caspase-3 and p53) was suppressed upon EPA-E treatment. Besides, EPA-E curbed methotrexate-induced abnormal autophagy by downregulating LC3A/B and beclin-1. Interestingly, BADGE-coadministration reversed EPA-E beneficial actions. Collectively, our findings suggest PPAR-γ role in EPA-E-mediated mitigation of methotrexate-evoked testiculopathy via suppression of oxidative stress, apoptosis, as well as abnormal autophagy. Furthermore, EPA-E could be used as a preventive therapy for some testiculopathies mediated by oxidative stress.

Mitochondrial-mediated nuclear remodeling and macrophage polarizations: A key switch from liver fibrosis to HCC progression

Liver fibrosis is a significant health burden worldwide and has emerged as the leading cause of Hepatocellular carcinoma (HCC) incidence. Mitochondria are the dynamic organelles that regulate the differentiation, survival, and polarization of macrophages. Nuclear-DNA-associated proteins, micro-RNAs, as well as macrophage polarization are essential for maintaining intracellular and extra-cellular homeostasis in the liver parenchyma. Dysregulated mitochondrial coding genes (ETS complexes I, II, III, IV, and V), non-coding RNAs (mitomiRs), and nuclear alteration lead to the production of reactive oxygen species (ROS) and inflammation which are implicated in the transition of liver fibrosis into HCC. Recent findings indicated the protecting effect of E74-like factor 3/peroxisome proliferator-activated receptor-γ (Elf-3/PPAR-γ). HDAR-y inhibits the deacetylation of PPAR-y and maintains the PPAR-y pathway. Elf-3 plays a tumor suppressive role through epithelial-mesenchymal transition-related gene and zinc finger E-box binding homeobox 2 (ZEB-2) domain. Additionally, the development of HCC includes the PI3K/Akt/mTOR and transforming Growth Factor β (TGF-β) pathway that promotes the Epithelial-mesenchymal transition (EMT) through Smad/Snail/Slug signaling cascade. In contrast, the TLR2/NOX2/autophagy axis promotes M2 polarization in HCC. Thus, a thorough understanding of the mitochondrial and nuclear reciprocal relationship related to macrophage polarization could provide new research opportunities concerning diseases with a significant impact on liver parenchyma towards developing liver fibrosis or liver cancer. Moreover, this knowledge can be used to develop new therapeutic strategies to treat liver diseases.

Inhibitory effect and mechanism of Rosiglitazone on M1 type polarization of central microglia in intracerebral hemorrhage mice based on JNK/STAT3 signaling pathway

BACKGROUND

Intracerebral hemorrhage (ICH) seriously threatens the health of people. In addition, microglia M1 polarization was confirmed to be involved in the progression of ICH. Rosiglitazone was able to be used as an antidiabetic agent, which could activate PPAR-γ, and PPAR-γ was reported to inhibit inflammation in microglia. However, the detailed function of Rosiglitazone in ICH remains unclear.

METHODS

In vivo and in vitro experiments were used to test the function of Rosiglitazone in ICH. In addition, RT-qPCR and western blot were performed to evaluate the mRNA and protein level of PPAR-γ, respectively. Immunofluorescence staining was performed to detect the levels of CD206 and CD86, and ELISA was used to measure the levels of pro-inflammatory cytokines.

RESULTS

PPAR-γ was downregulated in ICH mice, whereas p-JNK and p-STAT3 were upregulated. Thrombin notably downregulated the level of PPAR-γ in BV2 cells, whereas Rosiglitazone partially reversed this phenomenon. In addition, Rosiglitazone markedly reversed thrombin-induced microglia M1 polarization. Consistently, thrombin-induced inflammatory response in BV2 cells was abolished in the presence of Rosiglitazone. SP600125 (JNK/STAT3 inhibitor) greatly reversed thrombin-induced M1 polarization in microglia, and GW9662 abolished the effect of SP600125. Meanwhile, Rosiglitazone could inactivate JNK/STAT3 pathway through the upregulation of PPAR-γ. Furthermore, Rosiglitazone notably alleviated the symptom of ICH in vivo through inhibiting the apoptosis and mediating PPAR-γ/JNK/STAT3 axis.

CONCLUSION

Rosiglitazone could attenuate the inflammation in ICH through inhibiting microglia M1 polarization. Thus, our research would shed now lights on exploring new therapeutic strategies against ICH.

Linalool attenuates lipid accumulation and oxidative stress in metabolic dysfunction-associated steatotic liver disease via Sirt1/Akt/PPRA-α/AMPK and Nrf-2/HO-1 signaling pathways

INTRODUCTION

Linalool is a monoterpene that occurs naturally in various aromatic plants and is identified in our previous study as a potential candidate for protection against high-fat diet (HFD)-induced metabolic dysfunction-associated steatotic liver disease (MASLD). However, little is known about its direct effects on hepatic lipid metabolism and oxidative stress. Therefore, this study aims to investigate the therapeutic effect of linalool against MASLD and the underlying mechanism.

METHODS

To establish a rat model of MASLD, male Wistar rats were fed HFD for 16 weeks and orally administered linalool (100 mg/kg body weight) for 45 days starting from week 14.

RESULTS

Linalool significantly reduced HFD-induced liver lipid accumulation and restored altered adipokine levels. Mechanistically, linalool downregulated the mRNA expression of sterol regulatory element binding protein 1 and its lipogenesis target genes fatty acid synthase and acetyl-CoA carboxylase, and upregulated the mRNA expression of genes involved in fatty acid oxidation (peroxisome proliferator-activated receptor (PPAR)-alpha [PPAR-α], lipoprotein lipase and protein kinase B [Akt]) as well as the upstream mediators sirtuin 1 (Sirt1) and AMP-activated protein kinase (AMPK) in the liver of MASLD rats. In addition, linalool also curbed oxidative stress by increasing antioxidant enzymes and activating nuclear erythroid-2-related factor 2 (Nrf-2) and its downstream target genes involved in antioxidant properties.

CONCLUSION

Therefore, this study concludes that linalool attenuates lipid accumulation in the liver by inhibiting de novo lipogenesis, promoting fatty acid oxidation, and attenuating oxidative stress by regulating Sirt1/Akt/PPRA-α/AMPK and Nrf-2/ HO-1 signaling pathways.

Influence of chrysin on D-galactose induced-aging in mice: Up regulation of AMP kinase/liver kinase B1/peroxisome proliferator-activated receptor-γ coactivator 1-α signaling pathway

Adenosine monophosphate kinase/liver kinase B1/peroxisome proliferator-activated receptor-γ coactivator 1-α (AMPK/LKB1/PGC1α) pathway has a vital role in regulating age-related diseases. It controls neurogenesis, cell proliferation, axon outgrowth, and cellular energy homeostasis. AMPK pathway also regulates mitochondrial synthesis. The current study evaluated the effect of chrysin on D-galactose (D-gal) induced-aging, neuron degeneration, mitochondrial dysfunction, oxidative stress, and neuroinflammation in mice. The mice were allocated randomly into four groups (10 each group): Group 1: normal control group, Group 2: D-gal group, Groups 3 and 4: chrysin (125 and 250 mg/kg, respectively). Groups 2-4 were injected with D-gal (200 mg/kg/day; s.c) for 8 weeks to induce aging. Groups 3 and 4 were orally gavaged every day concurrent with D-gal. At the end of experiment, behavioral, brain biochemical and histopathological changes were monitored. Chrysin administration elevated discrimination ratio in object recognition, Y Maze percentage alternation, locomotor activity and brain contents of AMPK, LKB1, PGC1α, NAD (P)H quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1), nerve growth factor (NGF) (neurotrophin-3; NT-3), and seretonin as well as reduced brain contents of tumor necrosis factor-alpha (TNF-α), nuclear factor kappa B (NF-κB), advanced glycation end products (AGEs) and glial fibrillary acidic protein (GFAP) compared to D-gal-treated mice. Chrysin also alleviated cerebral cortex and white matter neurons degeneration. Chrysin protects against neurodegeneration, improves mitochondrial autophagy and biogenesis as well as activates antioxidant genes expression. In addition, chrysin ameliorates neuroinflammation and stimulates the release of NGF and serotonin neurotransmitter. So, chrysin has a neuroprotective effect in D-gal induced-aging in mice.

Isolation, cloning, and tissue distribution and functional analysis of ShP-glycoprotein in the freshwater crab Sinopotamon henanense exposed to Cd and Cd-QDs

P-glycoprotein (Pgp), a member of ATP binding cassette (ABC) transporter family, can extrude toxic substances out of cells by mediating multi-xenobiotic resistance (MXR) in aquatic organisms, however, its regulation and association with MXR are still unclear. In this work, the genetic information of Pgp in freshwater crab Sinopotamon henanense (ShPgp) was revealed for the first time. ShPgp with a total of 4488 bp was cloned and analyzed, which includes 4044 bp open reading frame, 353 bp 3' untranslated region, and 91 bp 5' untranslated region. The recombinant ShPGP were expressed in Saccharomyces cerevisiae and taken for SDS-PAGE and western blot analysis. ShPGP was widely expressed in the midgut, hepatopancreas, testis, ovary, gill, hemocytes, accessory gonad and myocardium of the crabs studied. The images of immunohistochemistry indicated that ShPgp was mainly distributed in the cytoplasm and cell membrane. When the crabs were exposed to cadmium or cadmium containing quantum dots (Cd-QDs), not only the relative expression of ShPgp mRNA and the protein produced were enhanced, but also the MXR activity and ATP contents. The relative expression of target genes related to energy metabolism, detoxification and apoptosis was also determined in the carbs exposed to Cd or Cd-QDs. The results showed that bcl-2 was significantly down-regulated, while other genes were up-regulated except PPAR (not affected). However, when the Shpgp in treated crabs was interfering by knockdown technique, their apoptosis and the expression of proteolytic enzyme genes and transcription factors MTF1 and HSF1 were also elevated, while the expression of apoptosis inhibiting and fat metabolism genes were compromised. Based on the observation, we concluded that MTF1 and HSF1 were involved in gene transcription regulation of mt and MXR, respectively, while PPAR had limited regulatory effect on those genes in S. henanense. NF-κB may play a negligible role in the process of apoptosis in testes induced by cadmium or Cd-QDs. However, the detail information regarding Pgp involvement in SOD or MT, and its association with apoptosis during xenobiotics insults remain to be explored.

Protective effects of diclofenac on liver graft preservation

This study aims to evaluate the effect of diclofenac addition to the preservation solution Celsior on liver graft preservation. Liver from Wistar rats were cold flushed in situ, harvested, and then stored in Celsior solution (24 h, 4 °C) supplemented or not with 50 mg/L of diclofenac sodium salt. Reperfusion was performed (120 min, 37 °C) using the isolated perfusion rat liver model. Perfusate samples were collected to evaluate transaminases' activities after cold storage and by the end of reperfusion. To evaluate liver function, bile flow, hepatic clearance of bromosulfophthalein, and vascular resistance were assessed. Diclofenac scavenging property (DPPH assay) as well as oxidative stress parameters (SOD and MPO activities and the concentration of glutathione, conjugated dienes, MDA, and carbonylated proteins) were measured. Transcription factors (PPAR-γ and NF-κB), inflammation (COX-2, IL-6, HMGB-1, and TLR-4), as well as apoptosis markers (Bcl-2 and Bax) were determined by quantitative RT-PCR. Enriching the preservation solution Celsior with diclofenac sodium salt attenuated liver injuries and improved graft function. Oxidative stress, inflammation, and apoptosis were significantly reduced in Celsior + Diclo solution. Also, diclofenac activated PPAR-γ and inhibited NF-κB transcription factors. To decrease graft damage and improve transplant recovery, diclofenac sodium salt may be a promising additive to preservation solution.

Lacticaseibacillus paracasei K56 Attenuates High-Fat Diet-Induced Obesity by Modulating the Gut Microbiota in Mice

This study investigated the effects of Lacticaseibacillus paracasei K56 (L. paracasei K56) on body weight, body composition, and glycolipid metabolism in mice with high-fat diet-induced obesity and explored the underlying mechanisms. Male C57BL/6J mice were fed a high-fat diet for 8 weeks to induce obesity; then, the obese mice were gavaged with or without L. paracasei K56 for 10 weeks. The body weight, body composition, fat mass, blood lipid, blood glucose, and hormones of the mice were evaluated. Moreover, the fatty acid synthesis (FAS) and peroxisome proliferator-activated receptor γ (PPAR-γ) expressions in the liver were detected via Western blotting. 16S rRNA gene sequencing was adopted to determine the gut microbiota alterations. The high-fat diet successfully induced obesity, as indicated by the abnormal increase in body weight, visceral fat, fat mass, blood lipids, fasting blood glucose, and insulin-resistance. Moreover, the FAS expression in the liver was significantly increased, whereas the PPAR-γ expression was significantly decreased. The relative abundance of Proteobacteria, Actinobacteria and Patescibacteria was also significantly increased, and that of Verrucomicrobia was significantly decreased. However, these indicators of mice supplemented with L. paracasei K56 were significantly opposite to those of obese mice. The Ruminococcuaceae_UCG-013, Akkermansia, Prevotellaceae_UCG-001, Muribaculum, and Lachnospiraceae_NK4A136 groups were significantly negatively correlated with body weight, blood lipids, and blood glucose-related indicators, whereas Coriobacteriaceae_UCG-002, Enterorhabdus, Raoultibacter, Acinetobacter, Romboutsia, Leuconostoc, and Erysipelatoclostridium were significantly positively correlated with these indicators. L. paracasei K56 might be a promising probiotic strain that could effectively slow down the body weight gain, reduce fat accumulation, alleviate insulin-resistance, and restore pancreatic β-cell function in obese mice by regulating the gut microbiota.

Resveratrol attenuated fatty acid synthesis through MAPK-PPAR pathway in red tilapia

High-fat (HF) diets have been shown to cause hepatic impairment in fish species, but the mode of action, especially the pathways involved, has not yet been determined. In this study, the effects of resveratrol (RES) supplementation on the hepatic structure and fat metabolism of red tilapia (Oreochromis niloticus) were determined. Based on transcriptome and proteomics results, RES was found to promote fatty acid β-oxidation in the blood, liver, and liver cells associated with apoptosis and the MAPK/PPAR signaling pathway. RES supplementation was found to alter the expression of genes related to apoptosis and fatty acid pathways like blood itga6a and armc5 which were upregulated and downregulated respectively by high-fat feeding while ggh and ensonig00000008711 increased and decreased, respectively, with RES addition. Relative to the PPAR signaling pathway, fabp10a and acbd7 showed a reverse U-shaped tendency, both in different treatments and at different times. Proteomics results demonstrated that MAPK/PPAR, carbon/glyoxylate, dicarboxylate/glycine serine, and threonine/drug-other enzymes/beta-alanine metabolism pathways in the RES group were significantly affected, and Fasn and Acox1 decreased and increased, respectively, with RES addition. Seven subgroups were obtained using scRNA-seq, and enrichment analysis showed that the PPAR signaling pathway was upregulated with RES supplementation. RES significantly increased the expression of the marked genes (pck1) ensonig00000037711, fbp10a, granulin, hbe1, and zgc:136461, which are liver cell-specific genes. In conclusion, RES resulted in significantly enriched DGEs associated with fat metabolism and synthesis via the MAPK-PPAR signaling pathway.

AQP4 Aggravates Cognitive Impairment in Sepsis-Associated Encephalopathy through Inhibiting Nav 1.6-Mediated Astrocyte Autophagy

The pathology of sepsis-associated encephalopathy (SAE) is related to astrocyte-inflammation associated with aquaporin-4 (AQP4). The aim here is to investigate the effects of AQP4 associated with SAE and reveal its underlying mechanism causing cognitive impairment. The in vivo experimental results reveal that AQP4 in peripheral blood of patients with SAE is up-regulated, also the cortical and hippocampal tissue of cecal ligation and perforation (CLP) mouse brain has significant rise in AQP4. Furthermore, the data suggest that AQP4 deletion could attenuate learning and memory impairment, attributing to activation of astrocytic autophagy, inactivation of astrocyte and downregulate the expression of proinflammatory cytokines induced by CLP or lipopolysaccharide (LPS). Furthermore, the activation effect of AQP4 knockout on CLP or LPS-induced PPAR-γ inhibiting in astrocyte is related to intracellular Ca2+ level and sodium channel activity. Learning and memory impairment in SAE mouse model are attenuated by AQP4 knockout through activating autophagy, inhibiting neuroinflammation leading to neuroprotection via down-regulation of Nav 1.6 channels in the astrocytes. This results in the reduction of Ca2+ accumulation in the cell cytosol furthermore activating the inhibition of PPAR-γ signal transduction pathway in astrocytes.

PFO5DoDA disrupts hepatic homeostasis primarily through glucocorticoid signaling inhibition

Legacy per- and polyfluoroalkyl substances (PFASs) are a worldwide health concern due to their potential bioaccumulation and toxicity in humans. A variety of perfluoroether carboxylic acids (PFECAs) have been developed as next-generation replacements of legacy PFASs. However, information regarding their possible environmental and human health risks is limited. In the present study, we explored the effects of PFECAs on mice based on long-term exposure to environmentally relevant doses of perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoDA). Results showed that PFECAs exposure suppressed many cellular stress signals and resulted in hepatomegaly. PFO5DoDA acted as an agonist of the peroxisome proliferator-activated receptor (PPAR) in vitro and modulated PPAR-dependent gene expression in the liver. Importantly, PFECAs had an inhibitory effect on the glucocorticoid receptor (GR), which may contribute to the extensive suppression of stress signals. Of note, the GR suppression induced by PFECAs was not reported by legacy perfluorooctanoic acid (PFOA). PFO5DoDA-induced changes in both GR and PPAR signals remodeled hepatic metabolic profiles, including decreased fatty acids and amino acids and increased β-oxidation. Mechanistically, PFO5DoDA inhibited GR transactivation by degradation of GR proteins. Our results emphasize the potential risk of PFECAs to human health, which were introduced to ease concerns regarding legacy PFASs.

Fenofibrate promotes neuroprotection in a model of rotenone-induced Parkinson's disease

Parkinson's disease is a neurodegenerative disease, the etiology of which remains unknown, but some likely causes include oxidative stress, mitochondrial dysfunction and neuroinflammation. Peroxisome-proliferator-activated receptor (PPAR) agonists have been studied in animal models of Parkinson's disease and have shown neuroprotective effects. In this study, we aimed to (1) confirm the neuroprotective effects of PPAR-alpha agonist fenofibrate. To this end, male rats received fenofibrate (100 mg/kg) orally for 15 days, 5 days before the intraperitoneal injections of rotenone (2.5 mg/kg for 10 days). After finishing the treatment with rotenone and fenofibrate, animals were subjected to the open field, the forced swim test and the two-way active avoidance task. Subsequently, rats were euthanized for measurement of dopamine and metabolites levels in the striatum and quantification of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra pars compacta (SNpc). In addition, we aimed to (2) evaluate the neuroprotective effects of fenofibrate on the accumulation of α-synuclein aggregates. Here, rats were treated for 5 days with fenofibrate continuing for over 28 days with rotenone. Then, animals were perfused for immunohistochemistry analysis of α-synuclein. The results showed that fenofibrate reduced depressive-like behavior and memory impairment induced by rotenone. Moreover, fenofibrate diminished the depletion of striatal dopamine and protected against dopaminergic neuronal death in the SNpc. Likewise, the administration of fenofibrate attenuated the aggregation of α-synuclein in the SNpc and striatum in the rotenone-lesioned rats. Our study confirmed that fenofibrate exerted neuroprotective effects because parkinsonian rats exhibited reduced behavioral, neurochemical and immunohistochemical changes, and importantly, a lower number of α-synuclein aggregates.

Evaluation of L-Selenomethionine on Ameliorating Cardiac Injury Induced by Environmental Ammonia

L-Selenomethionine is one of the important organic selenium sources. The supplementation of L-selenomethionine in diets is significant to improve the health of pigs. Ammonia is a major pollutant in the atmosphere and piggery, posing a threat to human and animal health. Although ammonia exposure can damage the heart, the mechanism of cardiac toxicity by ammonia is still unknown. In this study, we investigated the mechanism of cardiac injury induced by ammonia exposure in pigs and the protective effect of L-selenomethionine on its cardiotoxicity. The results showed that the blood ammonia content of pig increased significantly in ammonia group, the expressions of energy metabolism-related genes (LDHA, PDK4, HK2, and CPTIB) and the oxidative stress indexes were significantly changed (P < 0.05), the AMPK/PPAR-γ/NF-κB signaling pathways were activated, the chromatin edge aggregation and nuclear pyknosis were observed in ultrastructure, the apoptotic cells were significantly increased (P < 0.05), and the mRNA and protein expressions of apoptosis-related genes (Bcl-2, Bax, Cyt-c, caspase-3, and caspase-9) were significantly affected (P < 0.05). The above changes were significantly alleviated in ammonia + L-selenomethionine group, but there were still significant differences compared with the C group (P < 0.05). Our results indicated that ammonia exposure could cause energy metabolism disorder and oxidative stress and induce apoptosis of cardiomyocytes through AMPK/PPAR-γ/NF-κB pathways, which could lead to cardiac injury and affect cardiac function. L-Selenomethionine could effectively alleviate the cardiac damage caused by ammonia and antagonize the cardiotoxicity of ammonia.

PGC1α overexpression preserves muscle mass and function in cisplatin-induced cachexia

BACKGROUND

Chemotherapy induces a cachectic-like phenotype, accompanied by skeletal muscle wasting, weakness and mitochondrial dysfunction. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC1α), a regulator of mitochondrial biogenesis, is often reduced in cachectic skeletal muscle. Overexpression of PGC1α has yielded mixed beneficial results in cancer cachexia, yet investigations using such approach in a chemotherapy setting are limited. Utilizing transgenic mice, we assessed whether overexpression of PGC1α could combat the skeletal muscle consequences of cisplatin.

METHODS

Young (2 month) and old (18 month) wild-type (WT) and PGC1α transgenic male and female mice (Tg) were injected with cisplatin (C; 2.5 mg/kg) for 2 weeks, while control animals received saline (n = 5-9/group). Animals were assessed for muscle mass and force, motor unit connectivity, and expression of mitochondrial proteins.

RESULTS

Young WT + C mice displayed reduced gastrocnemius mass (male: -16%, P < 0.0001; female: -11%, P < 0.001), muscle force (-6%, P < 0.05, both sexes), and motor unit number estimation (MUNE; male: -53%, P < 0.01; female: -51%, P < 0.01). Old WT + C male and female mice exhibited gastrocnemius wasting (male: -22%, P < 0.05; female: -27%, P < 0.05), muscle weakness (male: -20%, P < 0.0001; female: -17%, P < 0.01), and loss of MUNE (male: -82%, P < 0.01; female: -62%, P < 0.05), suggesting exacerbated cachexia compared with younger animals. Overexpression of PGC1α had mild protective effects on muscle mass in young Tg + C male only (gastrocnemius: +10%, P < 0.05); however, force and MUNE were unchanged in both young Tg + C male and female, suggesting preservation of neuromuscular function. In older male, protective effects associated with PGC1α overexpression were heighted with Tg + C demonstrating preserved muscle mass (gastrocnemius: +34%, P < 0.001), muscle force (+13%, P < 0.01), and MUNE (+3-fold, P < 0.05). Similarly, old female Tg + C did not exhibit muscle wasting or reductions in MUNE, and had preserved muscle force (+11%, P < 0.05) compared with female WT + C. Follow-up molecular analysis demonstrated that aged WT animals were more susceptible to cisplatin-induced loss of mitochondrial proteins, including PGC1α, OPA1, cytochrome-C, and Cox IV.

CONCLUSIONS

In our study, the negative effects of cisplatin were heighted in aged animals, whereas overexpression of PGC1α was sufficient to combat the neuromuscular dysfunction caused by cisplatin, especially in older animals. Hence, our observations indicate that aged animals may be more susceptible to develop chemotherapy side toxicities and that mitochondria-targeted strategies may serve as a tool to prevent chemotherapy-induced muscle wasting and weakness.

Modulation of endoplasmic reticulum stress via sulforaphane-mediated AMPK upregulation against nonalcoholic fatty liver disease in rats

Nonalcoholic fatty liver disease (NAFLD) is a major health concern. Endoplasmic reticulum (ER) stress, inflammation, and metabolic dysfunctions may be targeted to prevent the progress of nonalcoholic fatty liver disease. Sulforaphane (SFN), a sulfur-containing compound that is abundant in broccoli florets, seeds, and sprouts, has been reported to have beneficial effects on attenuating metabolic diseases. In light of this, the present study was designed to elucidate the mechanisms by which SFN ameliorated ER stress, inflammation, lipid metabolism, and insulin resistance - induced by a high-fat diet and ionizing radiation (IR) in rats. In our study, the rats were randomly divided into five groups: control, HFD, HFD + SFN, HFD + IR, and HFD + IR + SFN groups. After the last administration of SFN, liver and blood samples were taken. As a result, the lipid profile, liver enzymes, glucose, insulin, IL-1β, adipokines (leptin and resistin), and PI3K/AKT protein levels, as well as the mRNA gene expression of ER stress markers (IRE-1, sXBP-1, PERK, ATF4, and CHOP), fatty acid synthase (FAS), peroxisome proliferator-activated receptor-α (PPAR-α). Interestingly, SFN treatment modulated the levels of proinflammatory cytokine including IL-1β, metabolic indices (lipid profile, glucose, insulin, and adipokines), and ER stress markers in HFD and HFD + IR groups. SFN also increases the expression of PPAR-α and AMPK genes in the livers of HFD and HFD + IR groups. Meanwhile, the gene expression of FAS and CHOP was significantly attenuated in the SFN-treated groups. Our results clearly show that SFN inhibits liver toxicity induced by HFD and IR by ameliorating the ER stress events in the liver tissue through the upregulation of AMPK and PPAR-α accompanied by downregulation of FAS and CHOP gene expression.

Synthetic PPAR Agonist DTMB Alleviates Alzheimer's Disease Pathology by Inhibition of Chronic Microglial Inflammation in 5xFAD Mice

Abnormal productions of amyloid beta (Aβ) plaque and chronic neuroinflammation are commonly observed in the brain of patients with Alzheimer's disease, and both of which induce neuronal cell death, loss of memory, and cognitive dysfunction. However, many of the drugs targeting the production of Aβ peptides have been unsuccessful in treating Alzheimer's disease. In this study, we identified synthetic novel peroxisome proliferator-activating receptor (PPAR) agonist, DTMB, which can ameliorate the chronic inflammation and Aβ pathological progression of Alzheimer's disease. We discovered that DTMB attenuated the proinflammatory cytokine production of microglia by reducing the protein level of NF-κB. DTMB also improved the learning and memory defects and reduced the amount of Aβ plaque in the brain of 5xFAD mice. This reduction in Aβ pathology was attributed to the changes in gliosis and chronic inflammation level. Additionally, bulk RNA-sequencing showed that genes related to inflammation and cognitive function were changed in the hippocampus and cortex of DTMB-treated mice. Our findings demonstrate that DTMB has the potential to be a novel therapeutic agent for Alzheimer's disease.

Modulatory effects of pioglitazone as a ligand for the peroxisome proliferator-activated receptor on semen quality and fertility potential of broiler breeder roosters

Fertility potential in roosters is a crucial topic in broiler breeder reproduction which is thought to be associated with age. This study aims to investigate effects of 2 levels of pioglitazone (PIO) supplementation on peroxisome proliferator-activated receptor gamma (PPAR-γ) expression, semen quality, and fertility parameters of aged broiler breeder roosters. The efficacy of PIO was divided into 2 sections: receptor-dependent and receptor-independent. Expression of PPAR-γ mRNA and protein was assessed in sperm to monitor receptor-dependent actions. Sperm motility, velocity parameters, viability, mitochondrial activity, and apoptosis were assessed for the receptor-independent actions. Broiler breeder roosters were randomly assigned to 3 groups: 1) control received a basal diet (CTRL); 2) PIO-5 received a basal diet supplemented with 5 mg PIO/bird/day, and 3) PIO-10 received a basal diet supplemented with 10 mg PIO/bird/day. In addition, semen samples were collected from 24 Ross broiler breeder roosters at 30, 43, and 53 wk of age. Effects of PIO were significant in terms of total motility, straight-line velocity, mitochondrial activity, and apoptosis (P ≤ 0.05). Total motility, straight-line velocity and mitochondrial activity improved in both PIO groups (P ≤ 0.05) along with a significant reduction in early and late apoptosis in the PIO groups (P ≤ 0.05). Pioglitazone addition affected total motility, mitochondrial activity, early apoptosis and late apoptosis in a linearly and quadratically manner (P < 0.05). PPAR-γ mRNA and protein expression were not significantly upregulated by the different doses of PIO (P > 0.05). Similarly, fertility performance was not significantly changed in the PIO groups (P > 0.05). Moreover, PIO improved mitochondrial activity and decreased the apoptosis rate in the sperm of aged broiler breeder roosters. These improvements were associated with the receptor-independent actions of PIO and the mechanism of action of PIO did not appear to be affected by the PPAR-γ receptor in broiler breeder roosters.

PPAR-Mediated Toxicology and Applied Pharmacology

Peroxisome proliferator-activated receptors (PPARs), members of the nuclear hormone receptor family, attract wide attention as promising therapeutic targets for the treatment of multiple diseases, and their target selective ligands were also intensively developed for pharmacological agents such as the approved drugs fibrates and thiazolidinediones (TZDs). Despite their potent pharmacological activities, PPARs are reported to be involved in agent- and pollutant-induced multiple organ toxicity or protective effects against toxicity. A better understanding of the protective and the detrimental role of PPARs will help to preserve efficacy of the PPAR modulators but diminish adverse effects. The present review summarizes and critiques current findings related to PPAR-mediated types of toxicity and protective effects against toxicity for a systematic understanding of PPARs in toxicology and applied pharmacology.

[PPARs: physiological functions and pharmacological roles of agonists in human diseases. Note II]

Increasing attention paid to the main family of peroxisome proliferator activated receptors--PPARs is generated, on one hand by the multiple functions of its members in numerous metabolically active tissues, and on the other hand by the therapeutic benefits expresed by some specific ligands that are used in certain metabolic diseases treatment plan. PPARalpha stimulates the beta-oxidative degradation of fatty acids and controls plasma lipid transport through the mediated action upon the triglycerides and fatty acids metabolism and by modulation of biosynthesis and catabolism of bile acids in the liver. PPARgamma promotes adipocytes differentiation and fat storage. PPARbeta/delta is involved in control and management of adipogenesis. While PPARalpha mediates the hypolipemiant actions of fibrates, PPARgamma is the receptor for thiazolidinediones (glitazones) reccomended in type 2 diabetes treatment; by binding to PPARgamma, glitazones modulates transcription of genes involved in lipid and carbohydrate metabolism.

Agonists of peroxisome proliferators-activated receptors (PPAR) alpha, beta/delta or gamma reduce transforming growth factor (TGF)-beta-induced proteoglycans' production in chondrocytes

OBJECTIVE

To investigate the potency of selective agonists of peroxisome proliferators-activated receptors' (PPAR) isotypes (alpha, beta/delta or gamma) to modulate the stimulating effect of transforming growth factor-beta1 (TGF-beta1) on proteoglycans' (PGs) synthesis in chondrocytes.

METHOD

Rat chondrocytes embedded in alginate beads and cultured under low serum conditions were exposed to TGF-beta1 (10 ng/ml), alone or in combination with the following agonists: Wy14643 for PPARalpha, GW501516 for PPARbeta/delta, rosiglitazone (ROSI) for PPARgamma, in the presence or absence of PPAR antagonists (GW6471 for PPARalpha, GW9662 for PPARgamma). PGs' synthesis was evaluated by radiolabelled sulphate incorporation and glycosaminoglycans' (GAGs) content by Alcian blue staining of beads and colorimetric 1.9 dimethyl-methylene blue assay after beads' solubilization. Phosphorylation of Extracellular Signal-related Kinase1/2 (ERK1/2), Smad2/3 and p38-MAPK was assessed by Western Blot and production of prostaglandin E2 (PGE2) by Enzyme immuno-assay (EIA). Levels of mRNA for PPAR target genes [acyl-CoA oxidase (ACO) for PPARalpha; mitochondrial carnitin palmitoyl transferase-1 (CPT-1) for PPARbeta/delta and adiponectin for PPARgamma], aggrecan, TGF-beta1 and genes controlling GAGs' side chains' synthesis were quantified by real time polymerase chain reaction and normalized over RP29 housekeeping gene.

RESULTS

ACO was selectively up-regulated by 100 microM of Wy14643, CPT-1 by 100 nM of GW501516 and adiponectin by 10 microM of ROSI without cell toxicity. TGF-beta1 increased PGs' synthesis by four-fold, GAGs' content and deposition by 3.5-fold and six-fold, respectively, while inducing aggrecan expression around 10-fold without modifying mRNA levels of GAGs' controlling enzymes. PPAR agonists inhibited the stimulating effect of TGF-beta1 by 24-44% on PGs' synthesis and over 75% on aggrecan, GAGs' content and deposition with the following rank order of potency: ROSI>GW501516> or =Wy14643. TGF-beta1-induced phosphorylation of Smad2/3 and ERK1/2 was reduced by ROSI over GW501516 but not by Wy14643 whereas stimulated PGE2 production was inhibited by Wy14643 over GW501516 but not by ROSI. The effect of PPAR agonists on PPAR target genes and TGF-beta1-induced aggrecan expression was reversed selectively by PPAR antagonists.

CONCLUSION

In chondrocytes' beads, PPAR agonists reduced the stimulating effect of TGF-beta1 on PGs by inhibiting TGF-beta1-induced aggrecan expression in an isotype-selective manner. Thus, PPAR agonists could be deleterious in situation of cartilage repair although being protective in situation of cartilage degradation.

Tetradecylselenoacetic acid, a PPAR ligand with antioxidant, antiinflammatory, and hypolipidemic properties

OBJECTIVE

Antioxidants protect against oxidative stress and inflammation, which, in combination with hyperlipidemia, are important mediators of atherogenesis. Here we present a selenium-substituted fatty acid, tetradecylselenoacetic acid (TSA), which is hypothesized to have antioxidant, antiinflammatory, and hypolipidemic properties.

METHODS AND RESULTS

We show that TSA exerts antioxidant properties by delaying the onset of oxidation of human low density lipoprotein (LDL), by reducing the uptake of oxidized LDL in murine macrophages, and by increasing the mRNA level of superoxide dismutase in rat liver. TSA also showed antiinflammatory effects by suppressing the release of interleukin (IL)-2 and -4, and by increasing the release of IL-10 in human blood leukocytes. In addition, TSA decreased the plasma triacylglycerol level and increased the mitochondrial fatty acid beta-oxidation in rat liver. In pigs, TSA seemed to reduce coronary artery intimal thickening after percutaneous coronary intervention. In HepG2 cells TSA activated all peroxisome proliferator-activated receptors (PPARs) in a dose-dependent manner.

CONCLUSIONS

Our data suggest that TSA exert potent antioxidant, antiinflammatory, and hypolipidemic properties, potentially involving PPAR-related mechanisms. Based on these effects, it is tempting to hypothesize that TSA could be an interesting antiatherogenic approach to atherosclerotic disorders.

O endotélio na síndrome metabólica

O endotélio é responsável pela manutenção da homeostase vascular. Em condições fisiológicas, mantém o tônus vascular, o fluxo sangüíneo laminar, a fluidez da membrana plasmática, o equilíbrio entre coagulação e fibrinólise, a inibição da proliferação e da migração celulares e o controle da resposta inflamatória. A disfunção endotelial é definida como uma alteração do relaxamento vascular por diminuição da biodisponibilidade de fatores de relaxamento derivados do endotélio, principalmente o óxido nítrico (NO). Estas respostas vasomotoras anormais ocorrem na presença de inúmeros fatores de risco para a aterosclerose. A síndrome metabólica é considerada um estado de inflamação crônica que se acompanha de disfunção endotelial e ocasiona aumento na incidência de eventos isquêmicos cardiovasculares e elevada mortalidade. Essa revisão abordará o processo fisiológico de regulação da função vascular pelo endotélio, os métodos disponíveis para avaliação in vivo da disfunção endotelial e as terapias capazes de melhorar a função vascular e conseqüentemente minimizar o risco cardiovascular dessa síndrome tão prevalente no nosso meio.

Novel Indole-Based Peroxisome Proliferator-Activated Receptor Agonists: Design, SAR, Structural Biology, and Biological Activities

The synthesis and structure-activity relationship studies of novel indole derivatives as peroxisome proliferator-activated receptor (PPAR) agonists are reported. Indole, a drug-like scaffold, was studied as a core skeleton for the acidic head part of PPAR agonists. The structural features (acidic head, substitution on indole, and linker) were optimized first, by keeping benzisoxazole as the tail part, based on binding and functional activity at PPARgamma protein. The variations in the tail part, by introducing various heteroaromatic ring systems, were then studied. In vitro evaluation led to identification of a novel series of indole compounds with a benzisoxazole tail as potent PPAR agonists with the lead compound 14 (BPR1H036) displaying an excellent pharmacokinetic profile in BALB/c mice and an efficacious glucose lowering activity in KKA(y) mice. Structural biology studies of 14 showed that the indole ring contributes strong hydrophobic interactions with PPARgamma and could be an important moiety for the binding to the protein.

[Effects of peroxisome proliferator-activated receptor gamma ligands on monocrotaline-induced pulmonary hypertension in rats]

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor superfamily, which regulates transcription of target genes in a ligand-dependent manner. Ligands for PPARgamma have been shown to attenuate proliferation of vascular smooth muscle cells, and to induce apoptosis in several cell lines in vitro. Since monocrotaline (MCT)-induced pulmonary hypertension in rats is characterized by proliferation of pulmonary vascular smooth muscle cells, we hypothesized that PPARgamma ligands may reduce MCT-induced pulmonary hypertension. To test this hypothesis, we treated MCT-injected rats with pioglitazone and troglitazone, synthetic ligands for PPARgamma, for three weeks and measured pulmonary artery pressure and pulmonary vessel wall thickness. TdT-mediated dUTP-biotin nick end labeling (TUNEL) and immunostaining for proliferating cell nuclear antigen (PCNA) were utilized to assess apoptosis and cell proliferation in the pulmonary arterial walls of pioglitazone-treated rats. MCT with pioglitazone or troglitazone treatment significantly reduced pulmonary hypertension and wall thickening of the pulmonary arteries. TUNEL-positive apoptotic cells were not seen in the pulmonary arterial walls of either MCT-injected or control rats with or without pioglitazone. PCNA-positive cells were only seen in the thickened pulmonary arterial walls of MCT rats, but not in the pulmonary arterial walls of controls and of pioglitazone-treated MCT rats. We conclude that PPARgamma ligands reduce MCT-induced pulmonary hypertension and pulmonary vascular wall thickening in rats. Inhibition of MCT-induced cell proliferation in the pulmonary arterial walls may account for this effect

Selenoproteins, Cholesterol-Lowering Drugs, and the Consequences Revisiting of the Mevalonate Pathway

3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and peroxisome proliferator-activated receptor alpha activators (fibrates) are the backbone of pharmacologic hypercholesterolemia and dyslipidemia treatment. Many of their clinical effects, however, are still enigmatic. This article describes how a side road of the mevalonate pathway, characterized in recent years, can rationalize a major fraction of these unexplained observations. This side road is the enzymatic isopentenylation of selenocysteine-tRNA([Ser]Sec) (Sec-tRNA), the singular tRNA to decode the unusual amino acid selenocysteine. The functionally indispensable isopentenylation of Sec-tRNA requires a unique intermediate from the mevalonate pathway, isopentenyl pyrophosphate, which concomitantly constitutes the central building block for cholesterol biosynthesis, and whose formation is suppressed by statins and fibrates. The resultant inhibition of Sec-tRNA isopentenylation profoundly decreases selenoprotein expression. This effect might seamlessly explain the immunosuppressive, redox, endothelial, sympatholytic, and thyroidal effects of statins and fibrates as well as their common side effects and drug interactions.

PPARs: molecular targets in the pharmacogenomics era

The recent global increase in prevalence of diseases like obesity, type 2 diabetes and hypertension in westernized societies is unfortunately not paralleled by our full understanding of the causative mechanisms. It is now firmly established that the interacting genetic and environmental (diet, smoking) components together determine the development and severity of the particular condition, which makes detailed dissection of such complex traits even more complicated. In effect, there is an unmet urgent need for molecular targets so we can directly modulate the causative factors and devise effective preventive and therapeutic algorithms. Among the most promising molecular targets for treatment of metabolic syndrome-related conditions identified so far, the group of three lipid-sensors, the peroxisome proliferator-activated receptors (PPARs) clearly stands out. The review focuses on pharmacogenetic aspects of recent developments in PPAR biology.