Resolvin D1/N-formyl peptide receptor 2 ameliorates paclitaxel-induced neuropathic pain through the activation of IL-10/Nrf2/HO-1 pathway in mice.

Introduction: Paclitaxel is a chemotherapy drug that is commonly used to treat cancer, but it can cause paclitaxel-induced neuropathic pain (PINP) as a side effect. Resolvin D1 (RvD1) has been shown to be effective in promoting the resolution of inflammation and chronic pain. In this study, we evaluated the effects of RvD1 on PINP and its underlying mechanisms in mice. Methods: Behavioral analysis was used to assess the establishment of the PINP mouse model and to test the effects of RvD1 or other formulations on mouse pain behavior. Quantitative real-time polymerase chain reaction analysis was employed to detect the impact of RvD1 on 12/15 Lox, FPR2, and neuroinflammation in PTX-induced DRG neurons. Western blot analysis was used to examine the effects of RvD1 on FPR2, Nrf2, and HO-1 expression in DRG induced by PTX. TUNEL staining was used to detect the apoptosis of DRG neurons induced by BMDM conditioned medium. H2DCF-DA staining was used to detect the reactive oxygen species level of DRG neurons in the presence of PTX or RvD1+PTX treated BMDMs CM. Results: Expression of 12/15-Lox was decreased in the sciatic nerve and DRG of mice with PINP, suggesting a potential involvement of RvD1 in the resolution of PINP. Intraperitoneal injection of RvD1 promoted pain resolution of PINP in mice. Intrathecal injection of PTX-treated BMDMs induced mechanical pain hypersensitivity in naïve mice, while pretreatment of RvD1 in BMDMs prevented it. Macrophage infiltration increased in the DRGs of PINP mice, but it was not affected by RvD1 treatment. RvD1 increased IL-10 expression in the DRGs and macrophages, while IL-10 neutralizing antibody abolished the analgesic effect of RvD1 on PINP. The effects of RvD1 in promoting IL-10 production were also inhibited by N-formyl peptide receptor 2 (FPR2) antagonist. The primary cultured DRG neurons apoptosis increased after stimulation with condition medium of PTX-treated BMDMs, but decreased after pretreatment with RvD1 in BMDMs. Finally, Nrf2-HO1 signaling was additionally activated in DRG neurons after stimulation with condition medium of RvD1+PTX-treated BMDMs, but these effects were abolished by FPR2 blocker or IL-10 neutralizing antibody. Discussion: In conclusion, this study provides evidence that RvD1 may be a potential therapeutic strategy for the clinical treatment of PINP. RvD1/FPR2 upregulates IL-10 in macrophages under PINP condition, and then IL-10 activates the Nrf2- HO1 pathway in DRG neurons, relieve neuronal damage and PINP.

Anti-proliferation and apoptosis-inducing effects of dihydroartemisinin on SH-SY5Y cells and metabolomic analysis.

Background: In childhood, metastatic neuroblastoma (NB) is the most common extracranial solid tumor, but there are no appropriate drugs for its treatment. Dihydroartemisinin (DHA), a drug for malaria treatment, has therapeutic potential in several cancers; however, its mechanisms remain unclear. This study aimed to investigate the anti-proliferation effect of DHA on SH-SY5Y cells and to explore its mechanism in vitro. Methods: We used 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to measure the half-maximal inhibitory concentration (IC50) of DHA; western blot was used to determine protein levels; propidium iodide (PI) staining was used to determine apoptotic cells; JC-1 staining to measure mitochondrial membrane potential; and dichloro-dihydro-fluorescein diacetate (DCFH-DA) staining was used to determine reactive oxygen species (ROS). Metabonomic analysis was performed by using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)-based untargeted metabolomics. Multivariate statistical analysis was performed to screen potential metabolites associated with DHA treatment in SH-SY5Y cells. Results: It was shown that DHA inhibited SH-SY5Y cell proliferation and increased poly (ADP-ribose) polymerase (PARP-1) and caspase 3 in a dose-dependent manner. In Further, DHA promoted ROS generation and γH2AX expression. In addition, a total of 125 proposed metabolites in SH-SY5Y cells and 45 vital metabolic pathways were identified through UHPLC-MS/MS-based untargeted metabolomic analysis. Conclusions: These data suggest that DHA could regulate taurine, linoleic acid, phenylalanine metabolism, and tryptophan metabolism, which are involved in the anti-proliferation effect of DHA in SH-SY5Y cells.

Development and validation of an UHPLC-Orbitrap-HRMS method for rapid determination of endogenous L-carnitine in patients on hemodialysis/peritoneal dialysis and its application to promote rational drug use.

Background: L-carnitine is an endogenous vitamin-like amino acid derivate which plays an essential role in energy metabolism and can be easily lost via dialysis. Deficiency of L-carnitine has great effects on many aspects of bodily functions. To determine the deficiency degree and adjust the supplementation dose, a rapid, sensitive, and specific method for the detection of endogenous L-carnitine in the plasma of dialysis patients using ultra-high performance liquid chromatography-Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-HRMS) was developed and validated. Methods: The plasma samples were processed by protein precipitation and centrifugation before analysis using UHPLC-Orbitrap-HRMS. Sample separation was achieved with a hydrophilic interaction liquid chromatography (HILIC) column, using an isocratic elution with a runtime of 5 min. The separated analytes were detected by positive ionization mode in full scan mode and targeted-single ion monitoring (t-SIM) mode. Mildronate was used as the internal standard (IS). Results: All the plasma could be detected in the range of 6.169 to 197.394 µM, with adequate accuracy, precision, and recovery. The method was validated in fortified validation with relative standard deviations (RSD) 5.15-8.74%. This method was applied to the analysis of 105 dialysis patients and 39 healthy participants, the results revealed that peritoneal dialysis patients without L-carnitine supplementation should pay more attention to L-carnitine monitoring, meanwhile, all the hemodialysis patients were advised to be routinely given a full dose of L-carnitine, no matter whether they had taken L-carnitine or not. Conclusions: This study developed a simple and rapid UHPLC-Orbitrap-HRMS method for detection of endogenous L-carnitine in dialysis patients, which could be useful to promote rational drug use.

Comparative effect of ciprofloxacin and moxifloxacin on the modulation of bile acid profiles and gut microbiota in rats

Abstract Fluoroquinolones are an important class of antimicrobial agents to manage infectious diseases. However, knowledge about how host bile acids are modified by fluoroquinolones is limited. We investigated and compared the impact of fluoroquinolones on circulating bile acid profiles and gut microbiota from in vivo studies. We administered ciprofloxacin (100 mg/kg/day) or moxifloxacin (40 mg/kg/day) orally to male Wistar rats for seven days. Fifteen bile acids (BAs) from the serum and large intestine were quantified by HPLC-MS/MS. The diversity of gut microbiota after ciprofloxacin and moxifloxacin treatment was analyzed using high-throughput, next-generation sequencing technology. The two fluoroquinolone-treated groups had different BA profiles. Ciprofloxacin significantly reduced the hydrophobicity index of the BA pool, reduced secondary BAs, and increased taurine-conjugated primary BAs in both the serum and large intestine as compared with moxifloxacin. Besides, ciprofloxacin treatment altered intestinal microbiota with a remarkable increase in Firmicutes to Bacteroidetes ratio, while moxifloxacin exerted no effect. What we found suggests that different fluoroquinolones have a distinct effect on the host BAs metabolism and intestinal bacteria, and therefore provide guidance on the selection of fluoroquinolones to treat infectious diseases.

Thioredoxin-Interacting Protein (TXNIP) Regulates Parkin/PINK1-mediated Mitophagy in Dopaminergic Neurons Under High-glucose Conditions: Implications for Molecular Links Between Parkinson's Disease and Diabetes.

Patients with diabetes mellitus have a higher risk of developing Parkinson's disease (PD). However, the molecular links between PD and diabetes remain unclear. In this study, we investigated the roles of thioredoxin-interacting protein (TXNIP) in Parkin/PINK1-mediated mitophagy in dopaminergic (DA) cells under high-glucose (HG) conditions. In streptozotocin-induced diabetic mice, TXNIP was upregulated and autophagy was inhibited in the midbrain, while the loss of DA neurons was accelerated by hyperglycemia. In cultured PC12 cells under HG, TXNIP expression was upregulated and the intracellular reactive oxygen species (ROS) levels increased, leading to cell death. Autophagic flux was further blocked and PINK1 expression was decreased under HG conditions. Parkin expression in the mitochondrial fraction and carbonyl cyanide 3-chlorophenylhydrazone (CCCP)-induced co-localization of COX IV (marker for mitochondria) and LAMP1 (marker for lysosomes) were also significantly decreased by HG. Overexpression of TXNIP was sufficient to decrease the expression of both PINK1 and Parkin in PC12 cells, while knockdown of the expression of TXNIP by siRNA decreased intracellular ROS and attenuated cellular injury under HG. Moreover, inhibition of TXNIP improved the CCCP-induced co-localization of COX IV and LAMP1 in PC12 cells under HG. Together, these results suggest that TXNIP regulates Parkin/PINK1-mediated mitophagy under HG conditions, and targeting TXNIP may be a promising therapeutic strategy for reducing the risk of PD under hyperglycemic conditions.

The role of Nav1.7 and methylglyoxal-mediated activation of TRPA1 in itch and hypoalgesia in a murine model of type 1 diabetes.

Methylglyoxal (MGO), an endogenous reactive carbonyl compound, plays a key role in the pathogenesis of diabetic neuropathy. The aim of this study is to investigate the role of MGO in diabetic itch and hypoalgesia, two common symptoms associated with diabetic neuropathy. Methods: Scratching behavior, mechanical itch (alloknesis), and thermal hypoalgesia were quantified after intradermal (i.d.) injection of MGO in naïve mice or in diabetic mice induced by intraperitoneal (i.p.) injection of streptozotocin (STZ). Behavioral testing, patch-clamp recording, transgenic mice, and gene expression analysis were used to investigate the mechanisms underlying diabetic itch and hypoalgesia in mice. Results: I.d. injection of MGO evoked dose-dependent scratching in normal mice. Addition of MGO directly activated transient receptor potential ankyrin 1 (TRPA1) to induce inward currents and calcium influx in dorsal root ganglia (DRG) neurons or in TRPA1-expressing HEK293 cells. Mechanical itch, but not spontaneous itch was developed in STZ-induced diabetic mice. Genetic ablation of Trpa1 (Trpa1-/- ), pharmacological blockade of TRPA1 and Nav1.7, antioxidants, and mitogen-activated protein kinase kinase enzyme (MEK) inhibitor U0126 abrogated itch induced by MGO or in STZ-induced diabetic mice. Thermal hypoalgesia was induced by intrathecal (i.t.) injection of MGO or in STZ-induced diabetic mice, which was abolished by MGO scavengers, intrathecal injection of TRPA1 blockers, and in Trpa1-/- mice. Conclusion: This study revealed that Nav1.7 and MGO-mediated activation of TRPA1 play key roles in itch and hypoalgesia in a murine model of type 1 diabetes. Thereby, we provide a novel potential therapeutic strategy for the treatment of itch and hypoalgesia induced by diabetic neuropathy.

Correction to: Antidepressant-Like Action of Single Facial Injection of Botulinum Neurotoxin A is Associated with Augmented 5-HT Levels and BDNF/ERK/CREB Pathways in Mouse Brain.

In the original publication, Figure 4G was incorrectly published. The correct version of Figure 4G is presented in this correction. This correction does not affect the conclusions of the paper.

Antidepressant-Like Action of Single Facial Injection of Botulinum Neurotoxin A is Associated with Augmented 5-HT Levels and BDNF/ERK/CREB Pathways in Mouse Brain.

The present study was designed to examine the therapeutic effects of Botulinum neurotoxin A (BoNT/A) on depression-like behaviors in mice and to explore the potential mechanisms. These results revealed that a single facial injection of BoNT/A induced a rapid and prolonged improvement of depression-like behaviors in naïve and space-restriction-stressed (SRS) mice, reflected by a decreased duration of immobility in behavioral despair tests. BoNT/A significantly increased the 5-hydroxytryptamine (5-HT) levels in several brain regions, including the hippocampus and hypothalamus, in SRS mice. BoNT/A increased the expression of the N-methyl-D-aspartate receptor subunits NR1 and NR2B in the hippocampus, which were significantly decreased in SRS mice. Furthermore, BoNT/A significantly increased the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus, hypothalamus, prefrontal cortex, and amygdala, which were decreased in SRS mice. Finally, BoNT/A transiently increased the levels of phosphorylated extracellular signal-regulated kinase (p-ERK) and cAMP-response element binding protein (p-CREB), which were suppressed in the hippocampus of SRS mice. Collectively, these results demonstrated that BoNT/A treatment has anti-depressant-like activity in mice, and this is associated with increased 5-HT levels and the activation of BDNF/ERK/CREB pathways in the hippocampus, supporting further investigation of BoNT/A therapy in depression.

The Neuroprotection of Low-Dose Morphine in Cellular and Animal Models of Parkinson's Disease Through Ameliorating Endoplasmic Reticulum (ER) Stress and Activating Autophagy.

Parkinson's disease (PD) is a common neurodegenerative disease characterized the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). Brain endogenous morphine biosynthesis was reported to be impaired in PD patients and exogenous morphine attenuated 6-hydroxydopamine (6-OHDA)-induced cell death in vitro. However, the mechanisms underlying neuroprotection of morphine in PD are still unclear. In the present study, we investigated the neuroprotective effects of low-dose morphine in cellular and animal models of PD and the possible underlying mechanisms. Herein, we found 6-OHDA and rotenone decreased the mRNA expression of key enzymes involved in endogenous morphine biosynthesis in SH-SY5Y cells. Incubation of morphine prevented 6-OHDA-induced apoptosis, restored mitochondrial membrane potential, and inhibited the accumulation of intracellular reactive oxygen species (ROS) in SH-SY5Y cells. Furthermore, morphine attenuated the 6-OHDA-induced endoplasmic reticulum (ER) stress possible by activating autophagy in SH-SY5Y cells. Finally, oral application of low-dose morphine significantly improved midbrain tyrosine hydroxylase (TH) expression, decreased apomorphine-evoked rotation and attenuated pain hypersensitivity in a 6-OHDA-induced PD rat model, without the risks associated with morphine addiction. Feeding of low-dose morphine prolonged the lifespan and improved the motor function in several transgenic Drosophila PD models in gender, genotype, and dose-dependent manners. Overall, our results suggest that neuroprotection of low-dose morphine may be mediated by attenuating ER stress and oxidative stress, activating autophagy, and ameliorating mitochondrial function.

Epigallocatechin-3-gallate attenuates acute and chronic psoriatic itch in mice: Involvement of antioxidant, anti-inflammatory effects and suppression of ERK and Akt signaling pathways.

Chronic itch is a distressing symptom of many skin diseases and negatively impacts quality of life. However, there is no medication for most forms of chronic itch, although antihistamines are often used for anti-itch treatment. Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, exhibits anti-oxidative and anti-inflammatory properties. Our previous studies highlighted a key role of oxidative stress and proinflammatory cytokines in acute and chronic itch. Here, we evaluated the effects of green tea polyphenon 60 and EGCG on acute and chronic itch in mouse models and explored its potential mechanisms. The effects of EGCG were determined by behavioral tests in mouse models of acute and chronic itch, which were induced by compound 48/80, chloroquine (CQ), and 5% imiquimod cream treatment, respectively. We found that systemic or local administration of green tea polyphenon 60 or EGCG significantly alleviated compound 48/80- and chloroquine-induced acute itch in a dose-dependent manner in mice. Incubation of EGCG significantly decreased the accumulation of intracellular reactive oxygen species (ROS) directly induced by compound 48/80 and CQ in cultured ND7-23 cells, a dorsal root ganglia derived cell line. EGCG also attenuated imiquimod-induced chronic psoriatic itch behaviors and skin epidermal hyperplasia in mice. In addition, EGCG inhibited the expression of IL-23 mRNA in skin and TRPV1 mRNA in dorsal root ganglia (DRG). Finally, EGCG remarkably inhibited compound 48/80-induced phosphorylation of extracellular signal-regulated kinase (ERK) and imiquimod-induced p-AKT in the spinal cord of mice, respectively. Collectively, these results indicated EGCG could be a promising strategy for anti-itch therapy.

Thioredoxin-interacting protein induced α-synuclein accumulation via inhibition of autophagic flux: Implications for Parkinson's disease.

AIMS: Thioredoxin-interacting protein (TXNIP) is associated with activation of oxidative stress through inhibition of thioredoxin (Trx). However, some evidences point out that TXNIP acts as a scaffolding protein in signaling complex independent of cellular redox regulation. The autophagy-lysosomal pathway plays important roles in the clearance of misfolded proteins and dysfunctional organelles. Lysosomal dysfunction has been involved in several neurodegenerative disorders including Parkinson's disease (PD). Although researchers have reported that TXNIP inhibited autophagic flux, the specific mechanism is rarely studied. METHODS: In this study, we investigated the effects of TXNIP on autophagic flux and α-synuclein accumulation by Western blot in HEK293 cells transfected with TXNIP plasmid. Further, we explored the influence of TXNIP on DA neuron survival in substantia nigra by IHC. RESULTS: We found that TXNIP induced LC3-II expression, but failed to degrade p62, a substrate of autophagy. Also, TXNIP aggravated α-synuclein accumulation. We also found that TXNIP inhibited the expression of ATP13A2, a lysosomal membrane protein. Moreover, we found that overexpression of ATP13A2 attenuated the impairment of autophagic flux and α-synuclein accumulation induced by TXNIP. Furthermore, overexpression of TXNIP in substantia nigra resulted in loss of DA neuron. CONCLUSION: Our data suggested that TXNIP blocked autophagic flux and induced α-synuclein accumulation through inhibition of ATP13A2, indicating TXNIP was a disease-causing protein in PD.

The neuroprotection of hydrogen sulfide against MPTP-induced dopaminergic neuron degeneration involves uncoupling protein 2 rather than ATP-sensitive potassium channels.

AIMS: Hydrogen sulfide (H(2)S), a novel gaseous mediator, has been recognized to protect neurons from overexcitation by enhancing the activity of the adenosine triphosphate-sensitive potassium (K-ATP) channel. However, no direct evidence supports that the K-ATP channel contributes to the neuroprotective effect of H(2)S in neurodegeneration. Herein, wild-type and Kir6.2 knockout (Kir6.2(-/-)) mice were used to establish the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD) so as to investigate the involvement of K-ATP channels in the neuroprotection of H(2)S. RESULTS: Systemic administration of sodium hydrosulfide (NaHS) (an H(2)S donor, 5.6 mg/kg/day) for 7 days rescued MPTP-induced loss of dopaminergic (DA) neurons in substantia nigra compacta of both Kir6.2(+/+) and Kir6.2(-/-) mice. Consistently, NaHS (100 µM) protected primary mesencephalic neurons against 1-methyl-4-phenylpyridinium (MPP(+))-induced cytotoxicity in both genotypes. We further found that deficiency of mitochondrial uncoupling protein 2 (UCP2), which reduces reactive oxygen species (ROS) production and functions as upstream to the K-ATP channel in determining vulnerability of DA neurons, abolished the protective effects of H(2)S against either DA neuron degeneration in the PD mouse model or MPP(+)-induced injury in primary mesencephalic neurons. Rationally, UCP2 evokes mild uncoupling, which in turn diminishes ROS accumulation in DA neurons. Furthermore, H(2)S exerted neuroprotective effect via enhancing UCP2-mediated antioxidation and subsequently suppressing ROS-triggered endoplasmic reticulum stress as well as ultimately inhibiting caspase 12-induced neuronal apoptosis. INNOVATION AND CONCLUSION: H(2)S protects DA neurons against degeneration in a UCP2 rather than Kir6.2/K-ATP channel-dependent mechanism, which will give us an insight into the potential of H(2)S in terms of opening up new therapeutic avenues for PD.