Unleashing Axonal Regeneration Capacities: Neuronal and Non-neuronal Changes After Injuries to Dorsal Root Ganglion Neuron Central and Peripheral Axonal Branches.

Peripheral nerves obtain remarkable regenerative capacity while central nerves can hardly regenerate following nerve injury. Sensory neurons in the dorsal root ganglion (DRG) are widely used to decipher the dissimilarity between central and peripheral axonal regeneration as axons of DRG neurons bifurcate into the regeneration-incompetent central projections and the regeneration-competent peripheral projections. A conditioning peripheral branch injury facilitates central axonal regeneration and enables the growth and elongation of central axons. Peripheral axonal injury stimulates neuronal calcium influx, alters the start-point chromatin states, increases chromatin accessibility, upregulates the expressions of regeneration-promoting genes and the synthesis of proteins, and supports axonal regeneration. Following central axonal injury, the responses of DRG neurons are modest, resulting in poor intrinsic growth ability. Some non-neuronal cells in DRGs, for instance satellite glial cells, also exhibit diminished injury responses to central axon injury as compared with peripheral axon injury. Moreover, DRG central and peripheral axonal branches are respectively surrounded by inhibitory glial scars generated by central glial cells and a permissive microenvironment generated by Schwann cells and macrophages. The aim of this review is to look at changes of DRG neurons and non-neuronal cells after peripheral and central axon injuries and summarize the contributing roles of both neuronal intrinsic regenerative capacities and surrounding microenvironments in axonal regeneration.

Promoting AMPK/SR-A1-mediated clearance of HMGB1 attenuates chemotherapy-induced peripheral neuropathy.

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is a serious side effect of chemotherapy with poorly understood mechanisms and few treatments. High-mobility group box 1 (HMGB1)-induced neuroinflammation is the main cause of CIPN. Here, we aimed to illustrate the role of the macrophage scavenger receptor A1 (SR-A1) in HMGB1 clearance and CIPN resolution. METHODS: Oxaliplatin (L-OHP) was used to establish a CIPN model. Recombinant HMGB1 (rHMGB1) (his tag) was used to evaluate the phagocytosis of HMGB1 by macrophages. RESULTS: In the clinic, HMGB1 expression and MMP-9 activity were increased in the plasma of patients with CIPN. Plasma HMGB1 expression was positively correlated with the cumulative dose of L-OHP and the visual analog scale. In vitro, engulfment and degradation of rHMGB1 increased and inflammatory factor expression decreased after AMP-activated protein kinase (AMPK) activation. Neutralizing antibodies, inhibitors, or knockout of SR-A1 abolished the effects of AMPK activation on rHMGB1 engulfment. In vivo, AMPK activation increased SR-A1 expression in the dorsal root ganglion, decreased plasma HMGB1 expression and MMP-9 activity, and attenuated CIPN, which was abolished by AMPK inhibition or SR-A1 knockout in the CIPN mice model. CONCLUSION: Activation of the AMPK/SR-A1 axis alleviated CIPN by increasing macrophage-mediated HMGB1 engulfment and degradation. Therefore, promoting HMGB1 clearance may be a potential treatment strategy for CIPN. Video abstract.

Suppressing high mobility group box-1 release alleviates morphine tolerance via the adenosine 5'-monophosphate-activated protein kinase/heme oxygenase-1 pathway.

Opioids, such as morphine, are the most potent drugs used to treat pain. Long-term use results in high tolerance to morphine. High mobility group box-1 (HMGB1) has been shown to participate in neuropathic or inflammatory pain, but its role in morphine tolerance is unclear. In this study, we established rat and mouse models of morphine tolerance by intrathecal injection of morphine for 7 consecutive days. We found that morphine induced rat spinal cord neurons to release a large amount of HMGB1. HMGB1 regulated nuclear factor κB p65 phosphorylation and interleukin-1ß production by increasing Toll-like receptor 4 receptor expression in microglia, thereby inducing morphine tolerance. Glycyrrhizin, an HMGB1 inhibitor, markedly attenuated chronic morphine tolerance in the mouse model. Finally, compound C (adenosine 5'-monophosphate-activated protein kinase inhibitor) and zinc protoporphyrin (heme oxygenase-1 inhibitor) alleviated the morphine-induced release of HMGB1 and reduced nuclear factor κB p65 phosphorylation and interleukin-1ß production in a mouse model of morphine tolerance and an SH-SY5Y cell model of morphine tolerance, and alleviated morphine tolerance in the mouse model. These findings suggest that morphine induces HMGB1 release via the adenosine 5'-monophosphate-activated protein kinase/heme oxygenase-1 signaling pathway, and that inhibiting this signaling pathway can effectively reduce morphine tolerance.

Pyruvate dehydrogenase beta subunit (Pdhb) promotes peripheral axon regeneration by regulating energy supply and gene expression.

Key metabolic enzymes not only regulate Glucose, lipid, amino acid metabolism to serve the cellular energy needs, but also modulate noncanonical or nonmetabolic signaling pathway such as gene expression, cell-cycle progression, DNA repair, apoptosis and cell proliferation in regulating the pathologic progression of disease. However, the role of glycometabolism in peripheral nerve axon regeneration is little known. In this study, we investigated the expression of Pyruvate dehydrogenase E1(PDH), a key enzyme linking glycolysis and the tricarboxylic acid (TCA) cycle, with qRT-PCR and found that pyruvate dehydrogenase beta subunit (Pdhb) is up-regulated at the early stage during peripheral nerve injury. The knockdown of Pdhb inhibits neurite outgrowth of primary DRG neurons in vitro and restrains axon regeneration of sciatic nerve after crush injury. Pdhb overexpression promoting axonal regeneration is reversed by knockdown of Monocarboxylate transporter 2(Mct2), a transporter involved in the transport and metabolism of lactate, indicating Pdhb promoting axon regeneration depends on lactate for energy supply. Given the nucleus-localization of Pdhb, further analysis revealed that Pdhb enhances the acetylation of H3K9 and affecting the expression of genes involved in arachidonic acid metabolism and Ras signaling pathway, such as Rsa-14-44 and Pla2g4a, thereby promoting axon regeneration. Collectively, our data indicates that Pdhb is a positive dual modulator of energy generation and gene expression in regulating peripheral axon regeneration.

Neutrophil extracellular traps as a unique target in the treatment of chemotherapy-induced peripheral neuropathy.

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is a severe dose-limiting side effect of chemotherapy and remains a huge clinical challenge. Here, we explore the role of microcirculation hypoxia induced by neutrophil extracellular traps (NETs) in the development of CIPN and look for potential treatment. METHODS: The expression of NETs in plasma and dorsal root ganglion (DRG) are examined by ELISA, IHC, IF and Western blotting. IVIS Spectrum imaging and Laser Doppler Flow Metry are applied to explore the microcirculation hypoxia induced by NETs in the development of CIPN. Stroke Homing peptide (SHp)-guided deoxyribonuclease 1 (DNase1) is used to degrade NETs. FINDINGS: The level of NETs in patients received chemotherapy increases significantly. And NETs accumulate in the DRG and limbs in CIPN mice. It leads to disturbed microcirculation and ischemic status in limbs and sciatic nerves treated with oxaliplatin (L-OHP). Furthermore, targeting NETs with DNase1 significantly reduces the chemotherapy-induced mechanical hyperalgesia. The pharmacological or genetic inhibition on myeloperoxidase (MPO) or peptidyl arginine deiminase-4 (PAD4) dramatically improves microcirculation disturbance caused by L-OHP and prevents the development of CIPN in mice. INTERPRETATION: In addition to uncovering the role of NETs as a key element in the development of CIPN, our finding provides a potential therapeutic strategy that targeted degradation of NETs by SHp-guided DNase1 could be an effective treatment for CIPN. FUNDING: This study was funded by the National Natural Science Foundation of China81870870, 81971047, 81773798, 82271252; Natural Science Foundation of Jiangsu ProvinceBK20191253; Major Project of "Science and Technology Innovation Fund" of Nanjing Medical University2017NJMUCX004; Key R&D Program (Social Development) Project of Jiangsu ProvinceBE2019732; Nanjing Special Fund for Health Science and Technology DevelopmentYKK19170.

NET-Triggered NLRP3 Activation and IL18 Release Drive Oxaliplatin-Induced Peripheral Neuropathy.

Oxaliplatin is an antineoplastic agent frequently used in the treatment of gastrointestinal tumors. However, it causes dose-limiting sensorimotor neuropathy, referred to as oxaliplatin-induced peripheral neuropathy (OIPN), for which there is no effective treatment. Here, we report that the elevation of neutrophil extracellular traps (NET) is a pathologic change common to both cancer patients treated with oxaliplatin and a murine model of OIPN. Mechanistically, we found that NETs trigger NLR family pyrin domain containing 3 (NLRP3) inflammasome activation and the subsequent release of IL18 by macrophages, resulting in mechanical hyperalgesia. In NLRP3-deficient mice, the mechanical hyperalgesia characteristic of OIPN in our model was reduced. In addition, in the murine model, treatment with the IL18 decoy receptor IL18BP prevented the development of OIPN. We further showed that eicosapentaenoic acid (EPA) reduced NET formation by suppressing the LPS-TLR4-JNK pathway and thereby abolished NLRP3 inflammasome activation and the subsequent secretion of IL18, which markedly prevented oxaliplatin-induced mechanical hyperalgesia in mice. These results identify a role for NET-triggered NLRP3 activation and IL18 release in the development of OIPN and suggest that utilizing IL18BP and EPA could be effective treatments for OIPN.

RSK1 promotes mammalian axon regeneration by inducing the synthesis of regeneration-related proteins.

In contrast to the adult mammalian central nervous system (CNS), the neurons in the peripheral nervous system (PNS) can regenerate their axons. However, the underlying mechanism dictating the regeneration program after PNS injuries remains poorly understood. Combining chemical inhibitor screening with gain- and loss-of-function analyses, we identified p90 ribosomal S6 kinase 1 (RSK1) as a crucial regulator of axon regeneration in dorsal root ganglion (DRG) neurons after sciatic nerve injury (SNI). Mechanistically, RSK1 was found to preferentially regulate the synthesis of regeneration-related proteins using ribosomal profiling. Interestingly, RSK1 expression was up-regulated in injured DRG neurons, but not retinal ganglion cells (RGCs). Additionally, RSK1 overexpression enhanced phosphatase and tensin homolog (PTEN) deletion-induced axon regeneration in RGCs in the adult CNS. Our findings reveal a critical mechanism in inducing protein synthesis that promotes axon regeneration and further suggest RSK1 as a possible therapeutic target for neuronal injury repair.

The metabolomic profiling identifies N, N-dimethylglycine as a facilitator of dorsal root ganglia neuron axon regeneration after injury.

Identifying novel molecules involved in axon regeneration of neurons in the peripheral nervous system (PNS) will be of benefit in obtaining a therapeutic strategy for repairing axon damage both in the PNS and the central nervous system (CNS). Metabolism and axon regeneration are tightly connected. However, the overall metabolic processes and the landscape of the metabolites in axon regeneration of PNS neurons are uncovered. Here, we used an ultra high performance liquid tandem chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOFMS)-based untargeted metabolomics to analyze dorsal root ganglia (DRG) metabolic characteristics at different time points post sciatic nerve injury and acquired hundreds of differentially changed metabolites. In addition, the results reveal that several metabolic pathways were significantly altered, such as 'Histidine metabolism', 'Glycine serine and threonine metabolism', 'Arginine and proline metabolism', 'taurine and hypotaurine metabolism' and so on. Given metabolite could alter a cell's or an organism's phenotype, further investigation demonstrated that N, N-dimethylglycine (DMG) has a promoting effect on the regenerative ability post injury. Overall, our data may serve as a resource useful for further understanding how metabolites contribute to axon regeneration in DRG during sciatic nerve regeneration and suggest DMG may be a candidate drug to repair nerve injury.

AMPK-autophagy-mediated inhibition of microRNA-30a-5p alleviates morphine tolerance via SOCS3-dependent neuroinflammation suppression.

BACKGROUND: The development of morphine tolerance is a clinical challenge for managing severe pain. Studies have shown that neuroinflammation is a critical aspect for the development of analgesic tolerance. We found that AMPK-autophagy activation could suppress neuroinflammation and improve morphine tolerance via the upregulation of suppressor of cytokine signaling 3 (SOCS3) by inhibiting the processing and maturation of microRNA-30a-5p. METHODS: CD-1 mice were utilized for the tail-flick test to evaluate morphine tolerance. The microglial cell line BV-2 was utilized to investigate the mechanism of AMPK-autophagy-mediated posttranscriptional regulation of SOCS3. Proinflammatory cytokines were measured by western blotting and real-time PCR. The levels of SOCS3 and miRNA-processing enzymes were evaluated by western blotting, real-time PCR and immunofluorescence staining. RESULTS: Based on experimental verification, miRNA-30a-5p could negatively regulate SOCS3. The AMPK activators AICAR, resveratrol and metformin downregulated miRNA-30a-5p. We found that AMPK activators specifically inhibited the processing and maturation of miRNA-30a-5p in microglia by degrading DICER and AGO2 via autophagy. Furthermore, a miRNA-30a-5p inhibitor significantly improved morphine tolerance via upregulation of SCOS3 in mice. It markedly increased the level of SOCS3 in the spinal cord of mice and subsequently inhibited morphine-induced phosphorylation of NF-κB p65. In addition, a miRNA-30a-5p inhibitor decreased the levels of IL-1ß and TNF-α caused by morphine in microglia. CONCLUSION: AMPK-autophagy activation suppresses neuroinflammation and improves morphine tolerance via the upregulation of SOCS3 by inhibiting miRNA-30a-5p.

Kinase DYRK2 acts as a regulator of autophagy and an indicator of favorable prognosis in gastric carcinoma.

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide; therefore, new and more specific molecules for GC are needed. Here, we found that dual specificity tyrosine phosphorylation regulated kinase 2 (DYRK2) may be a specific marker for GC. Immunohistochemistry (IHC) and statistical and bioinformatics analyses were conducted to detect DYRK2 expression in stomach tissues. The role of DYRK2 in GC was analyzed with a nude mouse model and CCK-8, wound healing and Transwell assays. Western blotting and immunofluorescence experiments were also performed to elucidate the relationship between DYRK2 expression and both epithelial-mesenchymal transition (EMT) and autophagy progression. We found that DYRK2 expression in GC tissues was lower than that in benign or normal tissues, and patients with high DYRK2 expression had a good prognosis. The in vitro results showed that DYRK2 expression inhibited the tumorigenic activities of GC, including proliferation, migration, and invasion. By analyzing the expression of EMT markers after altering DYRK2 expression, we observed that DYRK2 inhibits the occurrence of EMT. The nude mouse model revealed that DYRK2 inhibits tumor growth. Finally, we used Western blotting and immunofluorescence assays and found that DYRK2 promotes autophagy. Based on these data, DYRK2 may be a good reference indicator for the clinical diagnosis of GC.

Rescue of HSP70 in Spinal Neurons Alleviates Opioids-Induced Hyperalgesia via the Suppression of Endoplasmic Reticulum Stress in Rodents.

A major unresolved issue in treating pain is the paradoxical hyperalgesia produced by the gold-standard analgesic morphine and other opioids. Endoplasmic reticulum (ER) stress has been shown to contribute to neuropathic or inflammatory pain, but its roles in opioids-induced hyperalgesia (OIH) are elusive. Here, we provide the first direct evidence that ER stress is a significant driver of OIH. GRP78, the ER stress marker, is markedly upregulated in neurons in the spinal cord after chronic morphine treatment. At the same time, morphine induces the activation of three arms of unfolded protein response (UPR): inositol-requiring enzyme 1α/X-box binding protein 1 (IRE1α/XBP1), protein kinase RNA-like ER kinase/eukaryotic initiation factor 2 subunit alpha (PERK/eIF2α), and activating transcription factor 6 (ATF6). Notably, we found that inhibition on either IRE1α/XBP1 or ATF6, but not on PERK/eIF2α could attenuate the development of OIH. Consequently, ER stress induced by morphine enhances PKA-mediated phosphorylation of NMDA receptor subunit 1(NR1) and leads to OIH. We further showed that heat shock protein 70 (HSP70), a molecular chaperone involved in protein folding in ER, is heavily released from spinal neurons after morphine treatment upon the control of KATP channel. Glibenclamide, a classic KATP channel blocker that inhibits the efflux of HSP70 from cytoplasm to extracellular environment, or HSP70 overexpression in neurons, could markedly suppress morphine-induced ER stress and hyperalgesia. Taken together, our findings uncover the induction process and the central role of ER stress in the development of OIH and support a novel strategy for anti-OIH treatment.

FIBCD1 overexpression predicts poor prognosis in patients with hepatocellular carcinoma.

Fibrinogen C domain-containing 1 (FIBCD1) is an acetyl-recognition receptor that affects the occurrence and development of certain tumors. However, the prognostic significance of FIBCD1 in hepatocellular carcinoma (HCC) remains unclear. This study aimed to explore FIBCD1 expression in HCC and to determine the prognostic value of FIBCD1 in patients with HCC. A total of 1,058 liver tissue samples with detailed and complete clinical information were collected, including 495 HCC samples. Tissue microarray immunohistochemistry analysis was used to evaluate FIBCD1 protein expression in the collected tissues. The Kaplan-Meier plotter online tool was used to investigate the association between FIBCD1 expression and prognosis of patients with HCC. Oncomine and the Gene Expression Profiling Interactive Analysis database were used for bioinformatics analysis of FIBCD1. Results showed that FIBCD1 expression was higher in HCC and was associated with tumor diameter (P=0.002), tumor number (P=0.001), tumor node metastasis stage (P<0.001), primary tumor (T; P<0.001), lymph node metastases (N; P=0.002), distant metastases (M; P=0.023), differentiation degree (P=0.003), vascular invasion (P<0.001) and liver cirrhosis (P=0.011). Patients with HCC and high FIBCD1 expression had worse overall survival than those with low FIBCD1 expression. High FIBCD1 expression (P<0.001), TNM stage (P=0.003), T (P<0.001), N (P=0.014), and vascular invasion (P<0.001) were independent prognostic factors in HCC. Hence, FIBCD1 may be a novel biomarker for prognosis evaluation of HCC.

High mobility group box-1-toll-like receptor 4-phosphatidylinositol 3-kinase/protein kinase B-mediated generation of matrix metalloproteinase-9 in the dorsal root ganglion promotes chemotherapy-induced peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a significant side effect of chemotherapeutics. The mechanisms of CIPN remain substantially unidentified, although inflammation-induced peripheral sensitization has been indicated as an important factor. Here, we aimed to illustrate the role of the matrix metalloproteinase (MMP)-9-related signaling pathway in the process of CIPN. Oxaliplatin (L-OHP) was administered to mice to establish the CIPN model. Gelatin zymography was used to measure MMP-9/2 activities. Western blotting and immunohistochemistry were used to measure the expression of high-mobility group box-1 (HMGB-1), calcitonin gene-related peptide and ionized calcium-binding adapter molecule 1. Mechanical withdrawal was measured by von Frey hairs testing. Raw 264.7 cells and SH-SY5Y cells were cultured to investigate cell signaling in vitro. Here, we report that L-OHP-induced mechanical pain in mice with significant MMP-9/2 activation in dorsal root ganglion (DRG) neurons. MMP-9 inhibition or knockout alleviated the occurrence of CIPN directly. MMP-9/2 were released from macrophages and neurons in the DRG via the HMGB-1-toll-like receptor 4 (TLR4)-phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) axis, because MMP-9/2 activities could be reduced by macrophage scavengers or PI3Kγ knockout in CIPN mice. The in vitro data revealed that induced MMP-9 activity by recombinant HMGB-1 could be abolished by TLR4, PI3K or Akt inhibitors. Finally, it was shown that N-acetyl-cysteine (NAC) could reduce MMP-9/2 activities and attenuate CIPN effectively and safely. The HMGB-1-TLR4-PI3K/Akt-MMP-9 axis is involved in the crosstalk between macrophages and neurons in the pathological process of CIPN in mice. Direct inhibition of MMP-9 by NAC may be a potential therapeutic regimen for CIPN treatment.

p38/TF/HIF-α Signaling Pathway Participates in the Progression of CIPN in Mice.

Chemotherapy induced peripheral neuropathy (CIPN) is a serious adverse effect of chemotherapeutics with limited pathogenetic mechanism been known. Whether microcirculatory disturbance is involved in CIPN has not been reported. Considering that tissue factor (TF) is an endogenous coagulation factor, we hypothesize CIPN may be induced by the high expression of TF in macrophages and sciatic nerve, which induces the molecular signal related to ischemia and hypoxia. Oxaliplatin (L-OHP) was used to establish CIPN model. Von Frey Hairs was used to measure nociception. The murine macrophage cell line Raw 264.7 was used for cell experiments. Gelatin zymography and western blotting were used to measure the activity or expression of protein. TF expression and MMP-9/2 activity in sciatic nerve and blood are significantly increased by L-OHP. L-OHP increased the release of HSP70 from macrophage and enhanced the expression of p-p38 and HIF-1α in vivo and in vitro. Hirudin significantly suppressed the overexpression of p38, HIF-1α and activation of MMP-9/2 induced by L-OHP and attenuated CIPN in mice. This study suggests that a novel HSP70-TLR-4-p38-TF-HIF-1a axis may play a pivotal role in the pathological process of CIPN. It is also shown that the use of anticoagulant Hirudin can inhibit the above mechanisms and improve CIPN.

High-Expression HBO1 Predicts Poor Prognosis in Gastric Cancer.

OBJECTIVES: Our goal was to assess the expression of histone acetyltransferase binding to origin recognition complex 1 (HBO1) in gastric cancer and the effect on prognosis for the patients. METHODS: We used quantitative reverse transcription polymerase chain reaction, Western blot, and tissue microarray immunohistochemistry to investigate the expressions of HBO1 messenger RNA (mRNA) and protein in gastric cancer tissues. Online resources, including Oncomine and Kaplan-Meier Plotter, were used to further assess the correlation between HBO1 expression and the prognosis of the patients with gastric cancer. RESULTS: HBO1 mRNA and protein expressions in gastric cancer tissues were both significantly higher than those in normal tissues. The correlations between high HBO1 expression and differentiation, invasive depth (T), lymph node metastasis (N), distant metastasis (M), TNM staging, and serum carcinoembryonic antigen levels were positive. High HBO1 expression was negatively correlated with survival time in patients with gastric cancer. CONCLUSIONS: HBO1 might be a valuable biomarker to evaluate the prognosis of patients with gastric cancer.

High Expression of RARß Is a Favorable Factor in Colorectal Cancer.

RARß plays a critical role in cancer progression and is associated with several types of human cancer. It remains unclear, however, whether it is linked to the clinicopathological parameters of colorectal cancer (CRC). We therefore determined the expression of RARß protein in patients with primary CRC and examined its relationship with clinical outcomes. RARß expression in 234 samples of CRC patients and matched benign noncancerous tumors was detected by immunohistochemistry. RARß mRNA expression was confirmed using the TCGA and Oncomine databases. COX regression analysis and Kaplan-Meier survival analysis were performed to determine the relationship between RARß expression and CRC prognosis. Our results show that high expression of RARß correlated with better prognosis in CRC patients. RARß expression in CRC specimens was clearly lower than in peritumoral specimens (30.8% vs 58.8%, p < 0.001) and significantly correlated with gender (χ 2 = 3.926, p = 0.048), tumor differentiation (χ 2 = 5.978, p = 0.014), and tumor stage (χ 2 = 6.642, p = 0.036). Multivariate analyses further revealed that low RARß expression (p = 0.001), distant metastasis (p = 0.001), tissue differentiation (p = 0.006), and tumor stage (p = 0.002) were associated with overall survival in CRC patients. In addition, Kaplan-Meier analysis indicated that increased RARß expression in cytoplasm (p = 0.001) and early tumor TNM stage (p = 0.030) was associated with a more favorable outcome in patients with CRC. In conclusion, RARß expression was strongly correlated with several clinicopathological factors of CRC and may represent a favorable prognostic marker in patients with CRC.

Inhibition of apoptosis signal-regulating kinase by paeoniflorin attenuates neuroinflammation and ameliorates neuropathic pain.

BACKGROUND: Neuropathic pain is a serious clinical problem that needs to be solved urgently. ASK1 is an upstream protein of p38 and JNK which plays important roles in neuroinflammation during the induction and maintenance of chronic pain. Therefore, inhibition of ASK1 may be a novel therapeutic approach for neuropathic pain. Here, we aim to investigate the effects of paeoniflorin on ASK1 and neuropathic pain. METHODS: The mechanical and thermal thresholds of rats were measured using the Von Frey test. Cell signaling was assayed using western blotting and immunohistochemistry. RESULTS: Chronic constrictive injury (CCI) surgery successfully decreased the mechanical and thermal thresholds of rats and decreased the phosphorylation of ASK1 in the rat spinal cord. ASK1 inhibitor NQDI1 attenuated neuropathic pain and decreased the expression of p-p38 and p-JNK. Paeoniflorin mimicked ASK1 inhibitor NQDI1 and inhibited ASK1 phosphorylation. Paeoniflorin decreased the expression of p-p38 and p-JNK, delayed the progress of neuropathic pain, and attenuated neuropathic pain. Paeoniflorin reduced the response of astrocytes and microglia to injury, decreased the expression of IL-1ß and TNF-α, and downregulated the expression of CGRP induced by CCI. CONCLUSIONS: Paeoniflorin is an effective drug for the treatment of neuropathic pain in rats via inhibiting the phosphorylation of ASK1, suggesting it may be effective in patients with neuropathic pain.

Morphine induces dysfunction of PINK1/Parkin-mediated mitophagy in spinal cord neurons implying involvement in antinociceptive tolerance.

The development of opioid-induced analgesic tolerance is a clinical challenge in long-term use for managing chronic pain. The mechanisms of morphine tolerance are poorly understood. Mitochondria-derived reactive oxygen species (ROS) is a crucial signal inducing analgesic tolerance and pain. Chronic administration of morphine leads to robust ROS production and accumulation of damaged mitochondria, which are immediately removed by mitophagy. Here, we show that morphine inhibits mitochondria damage-induced accumulation of PTEN-induced putative kinase 1 (PINK1) in neurons. It interrupts the recruitment of Parkin to the impaired mitochondria and inhibits the ubiquitination of mitochondrial proteins catalyzed by Parkin. Consequently, morphine suppresses the recognition of autophagosomes to the damaged mitochondria mediated by LC3 and sequestosome-1 (SQSTM1/p62). Thus, morphine inhibits autophagy flux and leads to the accumulation of SQSTM1/p62. Finally, the impaired mitochondria cannot be delivered to lysosomes for degradation and ultimately induces robust ROS production and morphine tolerance. Our findings suggest that the dysfunction of mitophagy is involved in morphine tolerance. The deficiency of PINK1/Parkin-mediated clearance of damaged mitochondria is crucial for the generation of excessive ROS and important to the development of analgesic tolerance. These findings suggest that the compounds capable of stabilizing PINK1 or restoring mitophagy may be utilized to prevent or reduce opioid tolerance during chronic pain management.

Overexpression of ADAMTS-2 in tumor cells and stroma is predictive of poor clinical prognosis in gastric cancer.

ADAMTS-2 is a member of the ADAMTS family and is a procollagen N-proteinase. The objective of our research is to explore the prognostic significance of ADAMTS-2 in gastric carcinoma. A total of 655 samples with full clinicopathological data were investigated in this study. Tissue microarray immunohistochemistry analysis was used to analyze the relationship between clinicopathological characteristics and ADAMTS-2 expression. Oncomine and Kaplan-Meier plotters were performed for the relationship analysis between prognosis and ADAMTS-2 expression in patients with gastric cancer. Compared with that of normal tissues, the ADAMTS-2 protein expression was remarkably higher in gastric cancer cells and fibroblast cells. The results of univariate analysis indicated that the expression of ADAMTS-2 in tumor cells and fibroblast cells, Laurén classification, TNM grade, and carcinoembryonic antigen level in gastric cancer were all correlated with overall survival. The results of multivariate analysis indicated that the high expression of ADAMTS-2 in gastric cancer cells and fibroblast cells both were independent prognostic factors. Therefore, ADAMTS-2 may be a potential biomarker for assessing the prognosis of gastric carcinoma.

Overexpression of FIBCD1 Is Predictive of Poor Prognosis in Gastric Cancer.

OBJECTIVES: Fibrinogen C domain containing 1 (FIBCD1) is a newly identified acetyl group recognition receptor. The aim of this study was to evaluate the prognostic significance of FIBCD1 in gastric cancer. METHODS: This study included 706 samples, and the clinical data of all patients were recorded in detail. We studied messenger RNA (mRNA) and protein expression of FIBCD1 in cancerous and normal tissues by quantitative real-time polymerase chain reaction (n = 54) and tissue microarray immunohistochemistry analysis (n = 706), respectively. RESULTS: mRNA and protein expression levels of FIBCD1 were significantly higher in gastric cancer than in normal tissues. High FIBCD1 protein level showed significant correlations with age (P = .011), TNM stage (P < .001), serum carcinoembryonic antigen (CEA) level (P = .002), and the expression of human epidermal growth factor receptor 2 (P < .001). Kaplan-Meier survival analysis revealed that patients with gastric cancer with high levels of FIBCD1 had a significantly shorter survival time than those with low expression levels. In univariate analysis, high FIBCD1 expression, older age, histologic type, differentiation, TNM stage, serum CEA, and serum CA19-9 level correlated with overall survival. Multivariate analysis suggested that FIBCD1 expression was an independent prognostic factor. CONCLUSIONS: FIBCD1 may be a novel biomarker to evaluate the prognosis of gastric cancer.