Mechanism of opioid addiction and its intervention therapy: Focusing on the reward circuitry and mu-opioid receptor.

Opioid abuse and addiction have become a global pandemic, posing tremendous health and social burdens. The rewarding effects and the occurrence of withdrawal symptoms are the two mainstays of opioid addiction. Mu-opioid receptors (MORs), a member of opioid receptors, play important roles in opioid addiction, mediating both the rewarding effects of opioids and opioid withdrawal syndrome (OWS). The underlying mechanism of MOR-mediated opioid rewarding effects and withdrawal syndrome is of vital importance to understand the nature of opioid addiction and also provides theoretical basis for targeting MORs to treat drug addiction. In this review, we first briefly introduce the basic concepts of MORs, including their structure, distribution in the nervous system, endogenous ligands, and functional characteristics. We focused on the brain circuitry and molecular mechanism of MORs-mediated opioid reward and withdrawal. The neuroanatomical and functional elements of the neural circuitry of the reward system underlying opioid addiction were thoroughly discussed, and the roles of MOR within the reward circuitry were also elaborated. Furthermore, we interrogated the roles of MORs in OWS, along with the structural basis and molecular adaptions of MORs-mediated withdrawal syndrome. Finally, current treatment strategies for opioid addiction targeting MORs were also presented.

Blockade of mIL-6R alleviated lipopolysaccharide-induced systemic inflammatory response syndrome by suppressing NF-κB-mediated Ccl2 expression and inflammasome activation.

Systemic inflammatory response syndrome (SIRS) is characterized by dysregulated cytokine release, immune responses and is associated with organ dysfunction. IL-6R blockade indicates promising therapeutic effects in cytokine release storm but still remains unknown in SIRS. To address the issue, we generated the human il-6r knock-in mice and a defined epitope murine anti-human membrane-bound IL-6R (mIL-6R) mAb named h-mIL-6R mAb. We found that the h-mIL-6R and the commercial IL-6R mAb Tocilizumab significantly improved the survival rate, reduced the levels of TNF-α, IL-6, IL-1ß, IFN-γ, transaminases and blood urea nitrogen of LPS-induced SIRS mice. Besides, the h-mIL-6R mAb could also dramatically reduce the levels of inflammatory cytokines in LPS-treated THP-1 cells in vitro. RNA-seq analysis indicated that the h-mIL-6R mAb could regulate LPS-induced activation of NF-κB/Ccl2 and NOD-like receptor signaling pathways. Furthermore, we found that the h-mIL-6R mAb could forwardly inhibit Ccl2 expression and NLRP3-mediated pyroptosis by suppressing NF-κB in combination with the NF-κB inhibitor. Collectively, mIL-6R mAbs suppressed NF-κB/Ccl2 signaling and inflammasome activation. IL-6R mAbs are potential alternative therapeutics for suppressing excessive cytokine release, over-activated inflammatory responses and alleviating organ injuries in SIRS.

Inhibition of mu-opioid receptor suppresses proliferation of hepatocellular carcinoma cells via CD147-p53-MAPK cascade signaling pathway.

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths. Previous studies have suggested that mu-opioid receptor (MOR), a member of the opioid receptor family, is involved in the pathogenesis of HCC. However, the mechanism by which MOR regulates the biological behavior of HCC is still poorly understood. To address this problem, in this study, we investigated the role of MOR in the proliferation of HCC cell lines and the underlying mechanism. First, RT-PCR, western-blot and immunohistochemistry revealed higher expression of MOR in HCC cells and tissue than in non-tumor cells or adjacent tissue, and elevated expression of MOR was associated with jeopardized survival of HCC patients, as demonstrated by bioinformatic databases. Knockdown of MOR by specific siRNA attenuated the proliferation and migration of HCC cells and this effect could be reversed by rescue experiments, confirming the essential role of MOR in the proliferation of HCC. Moreover, results of colony formation assay, CCK8 test, flow cytometry and western blot suggested that a monoclonal antibody (mAb) specifically against MOR could inhibit proliferation of HepG2 and Huh7 cells via the MOR-CD147-p53-MAPK pathway, and the interaction between MOR and CD147 was verified by immunofluorescence colocalization and co-IP analysis. The mAb against MOR also enhanced the cisplatin-induced apoptosis of HCC cells by downregulating p-ERK, Bcl-2 and upregulating Bax. Taken together, these results suggest that MOR could regulate the proliferation of HCC cells in a CD147-p53-MAPK dependent manner. MOR possesses the potential to be a therapeutic target to treat HCC.

Wogonin alleviates liver injury in sepsis through Nrf2-mediated NF-κB signalling suppression.

Sepsis is a life-threatening organ dysfunction syndrome, and liver is a susceptible target organ in sepsis, because the activation of inflammatory pathways contributes to septic liver injury. Oxidative stress has been documented to participate in septic liver injury, because it not only directly induces oxidative genotoxicity, but also exacerbates inflammatory pathways to potentiate damage of liver. Therefore, to ameliorate oxidative stress is promising for protecting liver in sepsis. Wogonin is the compound extracted from the medicinal plant Scutellaria baicalensis Geogi and was found to exert therapeutic effects in multiple inflammatory diseases via alleviation of oxidative stress. However, whether wogonin is able to mitigate septic liver injury remains unknown. Herein, we firstly proved that wogonin treatment could improve survival of mice with lipopolysaccharide (LPS)- or caecal ligation and puncture (CLP)-induced sepsis, together with restoration of reduced body temperature and respiratory rate, and suppression of several pro-inflammatory cytokines in circulation. Then, we found that wogonin effectively alleviated liver injury via potentiation of the anti-oxidative capacity. To be specific, wogonin activated Nrf2 thereby promoting expressions of anti-oxidative enzymes including NQO-1, GST, HO-1, SOD1 and SOD2 in hepatocytes. Moreover, wogonin-induced Nrf2 activation could suppress NF-κB-regulated up-regulation of pro-inflammatory cytokines. Ultimately, we provided in vivo evidence that wogonin activated Nrf2 signalling, potentiated anti-oxidative enzymes and inhibited NF-κB-regulated pro-inflammatory signalling. Taken together, this study demonstrates that wogonin can be the potential therapeutic agent for alleviating liver injury in sepsis by simultaneously ameliorating oxidative stress and inflammatory response through the activation of Nrf2.

Melatonin induces the rejuvenation of long-term ex vivo expanded periodontal ligament stem cells by modulating the autophagic process.

BACKGROUND: Stem cells that have undergone long-term ex vivo expansion are most likely functionally compromised (namely cellular senescence) in terms of their stem cell properties and therapeutic potential. Due to its ability to attenuate cellular senescence, melatonin (MLT) has been proposed as an adjuvant in long-term cell expansion protocols, but the mechanism underlying MLT-induced cell rejuvenation remains largely unknown. METHODS: Human periodontal ligament stem cells (PDLSCs) were isolated and cultured ex vivo for up to 15 passages, and cells from passages 2, 7, and 15 (P2, P7, and P15) were used to investigate cellular senescence and autophagy change in response to long-term expansion and indeed the following MLT treatment. Next, we examined whether MLT could induce cell rejuvenation by restoring the autophagic processes of damaged cells and explored the underlying signaling pathways. In this context, cellular senescence was indicated by senescence-associated ß-galactosidase (SA-ß-gal) activity and by the expression of senescence-related proteins, including p53, p21, p16, and γ-H2AX. In parallel, cell autophagic processes were evaluated by examining autophagic vesicles (by transmission electronic microscopy), autophagic flux (by assessing mRFP-GFP-LC3-transfected cells), and autophagy-associated proteins (by Western blot assay of Atg7, Beclin-1, LC3-II, and p62). RESULTS: We found that long-term in vitro passaging led to cell senescence along with impaired autophagy. As expected, MLT supplementation not only restored cells to a younger state but also restored autophagy in senescent cells. Additionally, we demonstrated that autophagy inhibitors could block MLT-induced cell rejuvenation. When the underlying signaling pathways involved were investigated, we found that the MLT receptor (MT) mediated MLT-related autophagy restoration by regulating the PI3K/AKT/mTOR signaling pathway. CONCLUSIONS: The present study suggests that MLT may attenuate long-term expansion-caused cellular senescence by restoring autophagy, most likely via the PI3K/AKT/mTOR signaling pathway in an MT-dependent manner. This is the first report identifying the involvement of MT-dependent PI3K/AKT/mTOR signaling in MLT-induced autophagy alteration, indicating a potential of autophagy-restoring agents such as MLT to be used in the development of optimized clinical-scale cell production protocols.

L-type voltage-gated calcium channels in stem cells and tissue engineering.

L-type voltage-gated calcium ion channels (L-VGCCs) have been demonstrated to be the mediator of several significant intracellular activities in excitable cells, such as neurons, chromaffin cells and myocytes. Recently, an increasing number of studies have investigated the function of L-VGCCs in non-excitable cells, particularly stem cells. However, there appear to be no systematic reviews of the relationship between L-VGCCs and stem cells, and filling this gap is prescient considering the contribution of L-VGCCs to the proliferation and differentiation of several types of stem cells. This review will discuss the possible involvement of L-VGCCs in stem cells, mainly focusing on osteogenesis mediated by mesenchymal stem cells (MSCs) from different tissues and neurogenesis mediated by neural stem/progenitor cells (NSCs). Additionally, advanced applications that use these channels as the target for tissue engineering, which may offer the hope of tissue regeneration in the future, will also be explored.

N,N'-Dibenzyl-2,2'-(3,6-dioxaoctane-1,8-diyldi-oxy)dibenzamide.

The title compound, C(34)H(36)N(2)O(6), located on a center of inversion, crystallizes with one half-mol-ecule in the asymmetric unit. The dihedral angle between the benzene rings is 86.19 (2)°. An intra-molecular N-H⋯O hydrogen bond forms a six-membered ring; it affects the conformation of the mol-ecule which adopts a folded rather than open conformation. The crystal packing is stabilized by inter-molecular C-H⋯O inter-actions.