Novel effect of methionine enkephalin against influenza A virus infection through inhibiting TLR7-MyD88-TRAF6-NF-κB p65 signaling pathway

Methionine enkephalin (MENK) protected macrophages from ferroptosis by downregulating HMOX1 and ferritin

OBJECTIVE

The aim of this work was to investigate the immunological effect of MENK by analyzing the protein spectrum and bioinformatics of macrophage RAW264.7, and to explore the relationship between macrophage and ferroptosis.

RESULT

We employed proteomic analysis to identify differentially expressed proteins (DEPs) between macrophages and macrophages intervened by MENK. A total of 208 DEPs were identified. Among these, 96 proteins had upregulated expression and 112 proteins had downregulated expression. Proteomic analysis revealed a significant enrichment of DEPs associated with iron metabolism. The identification of hub genes was conducted using KEGG pathway diagrams and protein-protein interaction (PPI) analysis. The hub genes identified in this study include HMOX1 and Ferritin (FTH and FTL). A correlation was established between HMOX1, FTH, and FTL in the GO and KEGG databases. The results of PCR, WB and immunofluorescence showed that MENK downregulated the level of HMOX1 and FTH.

CONCLUSION

MENK had the potential to become an adjuvant chemotherapy drug by regulating iron metabolism in macrophages, reducing levels of HMOX1 and ferritin. We proposed an innovative research direction on the therapeutic potential of MENK, focusing on the relationship between ferroptosis and macrophage activity.

Polydatin alleviates sepsis‑induced acute lung injury via downregulation of Spi‑B

Sepsis-induced acute lung injury (ALI) is related to the dysregulation of inflammatory responses. Polydatin supplement was reported to exhibit anti-inflammatory effects in several diseases. The present study aimed to investigate the role of polydatin in sepsis-induced ALI. A cecum ligation and puncture (CLP)-induced mouse ALI model was established first and the pathological changes of lung tissues were assessed using hematoxylin and eosin staining. Meanwhile, to mimic sepsis-induced ALI in vitro, pulmonary microvascular endothelial cells (PMVECs) were treated with lipopolysaccharide (LPS). Pro-inflammatory cytokines levels were measured in lung tissues and PMVECs using ELISA. Reverse transcription-quantitative PCR was used to measure the mRNA levels of Spi-B in lung tissues and PMVECs. Moreover, the expression levels of Spi-B, p-PI3K, p-Akt, and p-NF-κB in lung tissues and PMVECs were determined using western blotting. The data revealed that polydatin attenuated CLP-induced lung injury and inhibited sepsis-induced inflammatory responses in mice. Furthermore, polydatin significantly inhibited the expression of Spi-B, p-PI3K, p-Akt, and p-NF-κB in lung tissues of mice subjected to CLP-induced ALI, while this phenomenon was reversed through Spi-B overexpression. Consistently, the anti-inflammatory effect of polydatin was abolished by Spi-B overexpression. Taken together, the current findings revealed that polydatin alleviated sepsis-induced ALI via the downregulation of Spi-B.

Methionine enkephalin(MENK) upregulated memory T cells in anti-influenza response

Novel prophylactic drugs and vaccination strategies for protection against influenza virus should induce specific effector T-cell immune responses in pulmonary airways and peripheral lymphoid organs. Designing approaches that promote T-cell-mediated responses and memory T-cell differentiation would strengthen host resistance to respiratory infectious diseases. The results of this study showed that pulmonary delivery of MENK via intranasal administration reduced viral titres, upregulated opioid receptor MOR and DOR, increased the proportions of T-cell subsets including CD8+ T cells, CD8+ TEM cells, NP/PA-effector CD8+ TEM cells in bronchoalveolar lavage fluid and lungs, and CD4+/CD8+ TCM cells in lymph nodes to protect mice against influenza viral challenge. Furthermore, we demonstrated that, on the 10th day of infection, the proportions of CD4+ TM and CD8+ TM cells were significantly increased, which meant that a stable TCM and TEM lineage was established in the early stage of influenza infection. Collectively, our data suggested that MENK administered intranasally, similar to the route of natural infection by influenza A virus, could exert antiviral activity through upregulating T-cell-mediated adaptive immune responses against influenza virus.

Proteomics analysis of methionine enkephalin upregulated macrophages against infection by the influenza-A virus

Macrophages have a vital role in phagocytosis and antiviral effect against invading influenza viruses. Previously, we found that methionine enkephalin (MENK) inhibited influenza virus infection by upregulating the "antiviral state" of macrophages. To investigate the immunoregulatory mechanism of action of MENK on macrophages, we employed proteomic analysis to identify differentially expressed proteins (DEPs) between macrophages infected with the influenza-A virus and cells infected with the influenza-A virus after pretreatment with MENK. A total of 215 DEPs were identified: 164 proteins had upregulated expression and 51 proteins had downregulated expression. Proteomics analysis showed that DEPs were highly enriched in "cytokine-cytokine receptor interaction", "phagosome", and "complement and coagulation cascades pathway". Proteomics analysis revealed that MENK could be an immune modulator or prophylactic for the prevention and treatment of influenza. MENK promoted the polarization of M1 macrophages, activated inflammatory responses, and enhanced phagocytosis and killing function by upregulating opsonizing receptors.

Anti-cancer effect of COVID-19 vaccines in 4T1 mice models

AIMS

Without any doubt, vaccination was the best choice for Coronavirus disease 2019 (COVID-19) pandemic control. According to the American Society of Clinical Oncology (ASCO) and European Society for Medical Oncology (ESMO), people with cancer or a history of cancer have a higher risk of dying from Covid-19 than ordinary people; hence, they should be considered a high-priority group for vaccination. On the other hand, the effect of the Covid-19 vaccination on cancer is not transparent enough. This study is one of the first in vivo studies that try to show the impact of Sinopharm (S) and AstraZeneca (A) vaccines on breast cancer, the most common cancer among women worldwide.

MATERIALS AND METHODS

Vaccination was performed with one and two doses of Sinopharm (S1/S2) or AstraZeneca (A1/A2) on the 4T1 triple-negative breast cancer (TNBC) mice model. The tumor size and body weight of mice were monitored every two days. After one month, mice were euthanized, and the existence of Tumor-infiltrating lymphocytes (TILs) and expression of the important markers in the tumor site was assessed. Metastasis in the vital organs was also investigated.

KEY FINDINGS

Strikingly, all of the vaccinated mice showed a decrease in tumor size and this decrease was highest after two vaccinations. Moreover, we observed more TILs in the tumor after vaccination. Vaccinated mice demonstrated a decrease in the expression of tumor markers (VEGF, Ki-67, MMP-2/9), CD4/CD8 ratio, and metastasis to the vital organs.

SIGNIFICANCE

Our results strongly suggest that COVID-19 vaccinations decrease tumor growth and metastasis.

Methionine enkephalin inhibits colorectal cancer by remodeling the immune status of the tumor microenvironment

There is evidence that methionine enkephalin (MENK), an opioid peptide, promotes anti-tumor immune responses. In this study, the effect of MENK on colorectal cancer (CRC) and its mechanisms of action were examined in vivo. The intraperitoneal administration of 20 mg/kg MENK effectively inhibited MC38 subcutaneous colorectal tumor growth in mice. MENK inhibited tumor progression by increasing the immunogenicity and recognition of MC38 cells. MENK down-regulated the oncogene Kras and anti-apoptotic Bclxl and Bcl2, suppressed Il1b, Il6, iNOS, and Arg1 (encoding inflammatory cytokines), and increased Il17a and Il10 levels. MENK promoted a tumor suppressive state by decreasing the immune checkpoints Pd-1, Pd-l1, Lag3, Flgl1, and 2b4 in CRC. MENK also altered the immune status of the tumor immune microenvironment (TIME). It increased the infiltration of M1-type macrophages, CD8⁺T cells, and CD4⁺T cells and decreased the proportions of G-MDSCs, M-MDSCs, and M2-type macrophages. MENK accelerated CD4⁺T_EM and CD8⁺T_EM cell activation in the TIME and up-regulated IFN-γ, TNF-α, and IL-17A in CD4⁺T cells and Granzyme B in CD8⁺T cells. In addition, analyses of PD-1 and PD-L1 expression indicated that MENK promoted the anti-tumor immune response mediated by effector T cells. Finally, OGFr was up-regulated at the protein and mRNA levels by MENK, and the inhibitory effects of MENK on tumor growth were blocked by NTX, a specific blocker of OGFr. These finding indicate that MENK remodels the TIME in CRC to inhibit tumor progression by binding to OGFr. MENK is a potential therapeutic agent for CRC, especially for improving the efficacy of immunotherapy.

Methionine enkephalin inhibited cervical carcinoma via apoptosis promotion and reduction of myeloid derived suppressor cell infiltrated in tumor

Immunotherapy for cervical carcinoma is becoming increasingly important recently. In these studies methionine enkephalin (menk) is shown to inhibit cervical tumor cell proliferation in vitro in association with an increase in the expression of apoptosis markers and mediators, including an increase in fas, caspase 8, and caspase 3 expression and intrinsic expression of the signaling pathway mediator bax. In vivo, tumor growth was restrained in mice xenotransplant model with typical pathological features of apoptosis. Furthermore, myeloid derived suppressor cells (MDSCs) had a significant decrease in circulation and in tumor site. In brief, these findings showed menk could inhibit tumor growth in vitro and in vivo, providing direction of further research and clinical application prospect.

Regulatory role of methionine enkephalin in myeloid-derived suppressor cells and macrophages in human cutaneous squamous cell carcinoma

The antitumor effects of methionine enkephalin (MENK), also known as opioid growth factor (OGF), including its inhibitory effects on cutaneous squamous cell carcinoma (CSCC), have been established. In this study, we determined the precise mechanism by which MENK suppresses CSCC cell growth. In particular, MENK induced G0/G1 cell cycle arrest and promoted apoptosis in CSCC cells via the Bcl-2/Bax/Caspase-3 signaling pathway. Moreover, MENK reduced immunosuppression by downregulating the number of myeloid-derived suppressor cells (MDSCs) and regulating the polarization of tumor-associated macrophages from M2 to M1 in vivo. Furthermore, JAK2/STAT3, an important tumor-promotion and immunosuppression signaling pathway that is involved in MDSC expansion in tumors and macrophage polarization, was inhibited. These findings highlight the potential of the JAK2/STAT3 signaling pathway as a therapeutic target and suggest the clinical application of MENK for CSCC.

Research progress of opioid growth factor in immune-related diseases and cancer diseases

Methionine enkephalin (MENK) has an important role in both neuroendocrine and immune systems. MENK was known as an opioid growth factor (OGF) for its growth regulatory characteristics. OGF interacts with the OGF receptor (OGFr) to inhibit DNA synthesis by upregulating p16 and/or p21, which delays the cell cycle transition from G0/G1 to S phase, and inhibits cell proliferation. In addition, OGF combines with OGFr in immune cells to exert its immunomodulatory activity and regulate immune function. OGF has been studied as an immunomodulator in a variety of autoimmune diseases, including multiple sclerosis, inflammatory bowel disease, diabetes and viral infections, and has been proven to relieve symptoms of certain diseases in animal and in vitro experiments. Also, OGF and OGFr have various anti-tumor molecular mechanisms. OGF can be used as the primary therapy alone or combined with other drugs to treat tumors. This article summarizes the research progress of OGF in immune-related diseases and cancer diseases.

Uncovering the pharmacological mechanisms of Xijiao Dihuang decoction combined with Yinqiao powder in treating influenza viral pneumonia by an integrative pharmacology strategy

Xijiao Dihuang decoction combined with Yinqiao powder (XDD-YQP) is a classical combination formula; however, its therapeutic effects in treating influenza viral pneumonia and the pharmacological mechanisms remain unclear. The therapeutic effect of XDD-YQP in influenza viral pneumonia was evaluated in mice. Subsequently, an everted gut sac model coupled with UPLC/Q-TOF MS were used to screen and identify the active compounds of XDD-YQP. Furthermore, network pharmacological analysis was adopted to probe the mechanisms of the active compounds. Lastly, we verified the targets predicted from network pharmacological analysis by differential bioinformatics analysis. Animal experiments showed that XDD-YQP has a therapeutic effect on influenza viral pneumonia. Moreover, 113 active compounds were identified from intestinal absorbed solutions of XDD-YQP. Using network pharmacological analysis, 90 major targets were selected as critical in the treatment of influenza viral pneumonia through 12 relevant pathways. Importantly, the MAPK signaling pathway was found to be closely associated with the other 11 pathways. Moreover, seven key targets, EGFR, FOS, MAPK1, MAP2K1, HRAS, NRAS, and RELA, which are common targets in the MAPK signaling pathway, were investigated. These seven key targets were identified as differentially expressed genes (DEGs) between influenza virus-infected and uninfected individuals. Hence, the seven key targets in the MAPK signaling pathway may play a vital role in the treatment of influenza viral pneumonia with XDD-YQP. This research may offer an integrative pharmacology strategy to clarify the pharmacological mechanisms of traditional Chinese medicines. The results provide a theoretical basis for a broader clinical application of XDD-YQP.

Necroptosis triggered by ROS accumulation and Ca2+ overload, partly explains the inflammatory responses and anti-cancer effects associated with 1Hz, 100 mT ELF-MF in vivo

Whereas the anti-neoplastic activity of extremely low frequency magnetic fields (ELF-EMF) is well-documented in literature, little is known about its underlying anti-cancer mechanisms and induced types of cell death. Here, for the first time, we reported induction of necroptosis, a specific type of programed necrotic cell death, in MC4-L2 breast cancer cell lines following a 2 h/day exposure to a 100 Hz, 1 mT ELF-EMF for five days. For in vivo assessment, inbred BALB/c mice bearing established MC-4L2 tumors were exposed to 100 mT, 1 Hz ELF-EMF 2 h daily for a period of 28-day, following which tumors were dissected and fixed for evaluation of tumor biomarkers expression and types of cell death induced using TUNEL assay, Immunohistochemistry and H&E staining. Peripheral blood samples were also collected for assessing pro-inflammatory cytokine profile following exposure. An exaggerated proinflammatory response evident form enhancement of IFN-γ (4.8 ± 0.24 folds) and TNF-α (3.1 ± 0.19 folds) and number of tumors infiltrating lymphocytes (TILs), specially CD8⁺ T_h cells (~20 folds), proposed occurrence of necroptosis in vivo. Meanwhile, exposure could effectively suppress tumor growth and expression of Ki-67, CD31, VEGFR2 and MMP-9. In vitro studies on ELF-EMF exposed MC-4L2 cells demonstrated a meaningful increase in phosphorylation of RIPK1/RIPK3/MLKL proteins and cleavage of caspase-9/caspase-3, confirming occurrence of both necroptosis and apoptosis. Complementary in vitro studies by treating ELF-EMF exposed MC-4L2 cells with verapamil (a calcium channel inhibitor), N-acetyl cysteine (a ROS scavenger) or calcium chloride confirmed the role of elevated intracellular calcium and ROS levels in ELF-EMF induced necroptosis.

Methionine enkephalin activates autophagy and stimulates tumour cell immunogenicity in human cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (CSCC) is a common skin tumour. Due to weak immunogenicity, recurrence is frequent after treatment. In this study, we explored the effects and mechanisms of methionine enkephalin (MENK), an endogenous opioid peptide and negative growth regulator, in CSCC. MENK inhibited A431 cell proliferation and promoted apoptosis through the opioid growth factor receptor (OGFr). Importantly, MENK also induced autophagy in CSCC and stimulated the emission of DAMPs in A431 cells, which resulted in enhanced activation of dendritic cells (DC).In conclusion, MENK provides an effective method with therapeutic potential to modulate the CSCC microenvironment by utilizing autophagy in the cancer cells.

Toll-like receptor-mediated innate immunity against herpesviridae infection: a current perspective on viral infection signaling pathways

Background

In the past decades, researchers have demonstrated the critical role of Toll-like receptors (TLRs) in the innate immune system. They recognize viral components and trigger immune signal cascades to subsequently promote the activation of the immune system.

Main body

Herpesviridae family members trigger TLRs to elicit cytokines in the process of infection to activate antiviral innate immune responses in host cells. This review aims to clarify the role of TLRs in the innate immunity defense against herpesviridae, and systematically describes the processes of TLR actions and herpesviridae recognition as well as the signal transduction pathways involved.

Conclusions

Future studies of the interactions between TLRs and herpesviridae infections, especially the subsequent signaling pathways, will not only contribute to the planning of effective antiviral therapies but also provide new molecular targets for the development of antiviral drugs.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Identification of potential mRNA panels for severe acute respiratory syndrome coronavirus 2 (COVID-19) diagnosis and treatment using microarray dataset and bioinformatics methods

The goal of the present investigation is to identify the differentially expressed genes (DEGs) between SARS-CoV-2 infected and normal control samples to investigate the molecular mechanisms of infection with SARS-CoV-2. The microarray data of the dataset E-MTAB-8871 were retrieved from the ArrayExpress database. Pathway and Gene Ontology (GO) enrichment study, protein–protein interaction (PPI) network, modules, target gene–miRNA regulatory network, and target gene–TF regulatory network have been performed. Subsequently, the key genes were validated using an analysis of the receiver operating characteristic (ROC) curve. In SARS-CoV-2 infection, a total of 324 DEGs (76 up- and 248 down-regulated genes) were identified and enriched in a number of associated SARS-CoV-2 infection pathways and GO terms. Hub and target genes such as TP53, HRAS, MAPK11, RELA, IKZF3, IFNAR2, SKI, TNFRSF13C, JAK1, TRAF6, KLRF2, CD1A were identified from PPI network, target gene–miRNA regulatory network, and target gene–TF regulatory network. Study of the ROC showed that ten genes (CCL5, IFNAR2, JAK2, MX1, STAT1, BID, CD55, CD80, HAL-B, and HLA-DMA) were substantially involved in SARS-CoV-2 patients. The present investigation identified key genes and pathways that deepen our understanding of the molecular mechanisms of SARS-CoV-2 infection, and could be used for SARS-CoV-2 infection as diagnostic and therapeutic biomarkers.

Toll-like receptor 7 deficiency mitigates hyperoxia-induced acute lung injury in mice

INTRODUCTION

Toll-like receptor (TLR) 7 is an important mediator in inflammation. However, its role in hyperoxia-induced acute lung injury (HALI) remains to be elucidated.

METHODS

C57BL/6 wild-type and C57BL/6 background TLR 7 deficiency mice were exposed to hyperoxia to stimulate HALI in airtight cages. Animals were sacrificed at 72 h post hyperoxia or room air exposure. Lung injury indicators were measured. Moreover, soluble epoxide hydrolase (sEH) activity was detected by a 14, 15-EET/DHET ELISA kit. Activation of activator protein (AP)-1 and nuclear factor kappa-B (NF-κB) was detected with enzyme linked immunosorbent assay kits.

RESULTS

Our data revealed that pulmonary histological assay and wet to dry weight ratio, myeloperoxidase and malondialdehyde activity were reduced in TLR 7 deficiency mice compared with wild-type mice. Moreover, hyperoxia-caused elevation of sEH activity was reduced in TLR 7 deficiency mice. Transcription factors AP-1 activation was significantly inhibited in TLR 7 deficiency mice compared with wild-type mice. Similarly, the activation of NF-κB was reduced in TLR 7 deficiency mice. Tumor necrosis factor-α and interleukin-1β, potent proinflammatory cytokines, were reduced in TLR 7 deficiency mice.

CONCLUSION

TLR 7 deficiency is associated with inhibition of inflammation in HALI in mice.

Methionine enkephalin inhibits influenza A virus infection through upregulating antiviral state in RAW264.7 cells

MENK, as an immune adjuvant, has potential immune-regulatory activity on innate and adaptive immune cells. The aim of this work was to investigate the antiviral effect of MENK on influenza virus-infected murine macrophage cells (RAW264.7) and its underlying mechanisms. The results showed that MENK markedly inhibited influenza A virus (H1N1) replication in pre- and post-MENK treatment, especially in pre-MENK treatment. The mechanisms exploration revealed that MENK (10 mg/mL) significantly inhibited the nucleoprotein (NP) of influenza virus and up-regulated levels of IL-6, TNF-α and IFN-β compared with those in H1N1 control group. Further experiments confirmed that antiviral effects of MENK was associated with promotion of opioid receptor (MOR) as well as activation of NF-κB p65 inducing cellular antiviral status. The data suggest that MENK should be potential candidate for prophylactic or therapeutic treatment against H1N1 influenza virus.

BAFF is involved in the pathogenesis of IgA nephropathy by activating the TRAF6/NF‑κB signaling pathway in glomerular mesangial cells

The aim of the present study was to investigate the involvement of B cell-activating factor (BAFF) in the pathogenesis of IgA nephropathy by activating the tumor necrosis factor receptor-associated factor 6 (TRAF6)/NF-κB signaling pathway in glomerular mesangial cells. For the clinical analysis, blood, urine and kidney tissue samples were collected from 58 patients diagnosed with primary IgA nephropathy by renal biopsy. For the in vitro study, glomerular mesangial cells were divided into five groups: Control (con)-short hairpin RNA (shRNA) (control group); con-shRNA + BAFF (20 ng/ml); con-shRNA + BAFF + BAFF-RFc chimera protein (500 µg/ml); TRAF6-shRNA; and TRAF6-shRNA + BAFF (20 ng/ml). For the in vivo experiments, 60 Sprague-Dawley rats were randomly divided into four groups: Con-small interfering RNA (siRNA) (control group); con-siRNA + IgA (IgA nephropathy group), BAFF-RFc chimera protein (2 µg/ml) + IgA, and TRAF6-siRNA (0.2 µM) + IgA. Reverse transcription-quantitative PCR was performed to evaluate the mRNA expression levels of TRAF6, connective tissue growth factor (CTGF), fibronectin (FN) and NF-κBP65. Western blot analysis was used to detect the protein expression levels of TRAF6, FN, CTGF and phosphorylated-NF-κBP65 in glomerular mesangial cells and kidney tissues. The results revealed that plasma BAFF levels were positively correlated with the severity of pathological damage in patients with IgA nephropathy. In vitro, BAFF induced the mRNA and protein expression of TRAF6, CTGF, FN and NF-κBP65 in glomerular mesangial cells. After the BAFF-RFc chimera protein was added to inhibit the binding of BAFF and BAFF-receptor (-R), this effect was reduced. In vivo, inhibition of the effects of BAFF via injection with the BAFF-R Fc chimera protein reduced kidney damage in rats suffering from IgA nephropathy. The effect on the expression of signaling pathway-associated proteins was also alleviated. In conclusion, BAFF enhanced the expression of fibroblast factors in the kidneys by activating the TRAF6/NF-κB signaling pathway.

Prospective oncotarget for gynecological cancer: Opioid growth factor (OGF) - opioid growth factor receptor (OGFr) axis

The standard treatments for neoplasia include surgery, chemotherapy, hormone antagonists and radiotherapy, which can prolong survival, but rarely cure the tumors of gynecological cancer patients. OGF - OGFr expression, in various gynecologic cells and tissues, is an intersection point between cell development, neuroendocrine function and immune modulation. It has been identified that OGF and OGFr expression differs between gynecological tumor and normal cells. Further, exogenous or endogenous OGF and OGFr antagonists have been known to have a role in regulating cell viability and apoptosis. Moreover, the expression of proteins in the OGF - OGFr axis modulate differentiation and membrane expression of immune cells, which can enhance the immune response. In vivo and in vitro assays have shown that OGF and OGFr antagonists inhibit mitosis as well as induce apoptosis in gynecologic cancer cells. Although immune augmentation combination therapies can intensify cytotoxic activity, OGF or OGFr antagonists do not increase toxicities associated with dual-immune regulation. In conclusion, the OGF - OGFr axis provides significant strategies for antitumor efficiency in gynecological cancer.

Enkephalins and ACTH in the mammalian nervous system

The pentapeptides methionine-enkephalin and leucine-enkephalin belong to the opioid family of peptides, and the non-opiate peptide adrenocorticotropin hormone (ACTH) to the melanocortin peptide family. Enkephalins/ACTH are derived from pro-enkephalin, pro-dynorphin or pro-opiomelanocortin precursors and, via opioid and melanocortin receptors, are responsible for many biological activities. Enkephalins exhibit the highest affinity for the δ receptor, followed by the μ and κ receptors, whereas ACTH binds to the five subtypes of melanocortin receptor, and is the only member of the melanocortin family of peptides that binds to the melanocortin-receptor 2 (ACTH receptor). Enkephalins/ACTH and their receptors exhibit a widespread anatomical distribution. Enkephalins are involved in analgesia, angiogenesis, blood pressure, embryonic development, emotional behavior, feeding, hypoxia, limbic system modulation, neuroprotection, peristalsis, and wound repair; as well as in hepatoprotective, motor, neuroendocrine and respiratory mechanisms. ACTH plays a role in acetylcholine release, aggressive behavior, blood pressure, bone maintenance, hyperalgesia, feeding, fever, grooming, learning, lipolysis, memory, nerve injury repair, neuroprotection, sexual behavior, sleep, social behavior, tissue growth and stimulates the synthesis and secretion of glucocorticoids. Enkephalins/ACTH are also involved in many pathologies. Enkephalins are implicated in alcoholism, cancer, colitis, depression, heart failure, Huntington's disease, influenza A virus infection, ischemia, multiple sclerosis, and stress. ACTH plays a role in Addison's disease, alcoholism, cancer, Cushing's disease, dermatitis, encephalitis, epilepsy, Graves' disease, Guillain-Barré syndrome, multiple sclerosis, podocytopathies, and stress. In this review, we provide an updated description of the enkephalinergic and ACTH systems.

Methionine enkephalin (MENK) regulates the immune pathogenesis of type 2 diabetes mellitus via the IL-33/ST2 pathway

The incidence and mortality of type 2 diabetes mellitus (T2DM) rank among the top ten worldwide. Emerging studies indicate pathological roles for the immune system in inflammation, insulin resistance and islet β-cell damage in subjects with T2DM. Methionine enkephalin (MENK) is present in endocrine cells of the pancreas and has been suggested to be an important mediator between the immune and neuroendocrine systems. Therefore, it may play a role in modulating insulin secretion from islet cells. Since little is known about the effect of MENK on T2DM, therefore it was the aim of this study to characterize the role and possible mechanism of action of MENK on plasma glucose and serum insulin levels in T2DM rats and INS-1 cells in vivo and in vitro. MENK significantly decreased the plasma glucose level and increased the serum insulin concentration in T2DM rats. It also increased the serum levels of the cytokines IL-5 and IL-10, while decreased TNF-α and IL-2 levels. We further confirmed that MENK regulated glucose metabolism by upregulating opioid receptor expression and modulating the IL-33/ST2 and MyD88-TRAF6-NF-κB p65 signaling pathways. Based on these results, an intraperitoneal injection of MENK represents a potentially new approach for T2DM.

Methionine enkephalin (MENK) inhibits human gastric cancer through regulating tumor associated macrophages (TAMs) and PI3K/AKT/mTOR signaling pathway inside cancer cells

This study was to explore the effect and mechanisms of anti- human gastric cancer by MENK in vitro and in vivo. The results showed in MENK-treated xenograft tissue, the percentage of M2-type macrophages decreased while M1-type macrophages increased. MENK increased the expression of M1-related cytokine TNF-α and attenuated the expression of M2-related cytokine IL-10 expression. MENK upregulated the expression of opioid receptor (OGFr), while it inhibited HGC27 and SGC7901 cells through blocking PI3K/AKT/mTOR signal pathway in vitro and in vivo. These effects of MENK could be cancelled when OGFr was knockdown. This indicates that binding to OGFr by MENK appears to be essential for the anti- GC cells. Therefore, it is concluded that MENK might skew macrophage toward M2 phenotype from M1 phenotype within tumor and induce cells apoptosis though blocking OGFr/PI3K/AKT/mTOR signaling pathway.

The novel mechanism of anticancer effect on gastric cancer through inducing G0/G1 cell cycle arrest and caspase-dependent apoptosis in vitro and in vivo by methionine enkephalin

Background

Gastric cancer (GC) is the second cause of cancer-related deaths. Methionine enkephalin (MENK), an endogenous opioid peptide, has immunological and antitumor activity.

Purpose

The aim of this work was to investigate whether MENK could exhibit activity against human GC in vitro and in vivo.

Materials and methods

Human GC cells were treated with MENK. Cell viability, colony formation, cell morphology, cell cycle, and apoptosis were assessed. The effects of MENK on gene expression of OGFr, Bax, BCL-2, caspase-3, PARP, Ki67, cyclin D1, c-myc, survivin were quantifed by qRT-PCR. Western blot was used to analyze the effects of MENK on protein expression of OGFr, Bax, BCL-2, caspase-3, PARP. The anti-tumor activity of MENK in gastic carcinoma was also investigated with animal experiments.

Results

The results indicate that MENK could significantly inhibit the growth of human GC cells SGC7901 and HGC27 in a concentration- and time-dependent manner, decrease the number of cell colonies, and arrest cell cycle in the G0/G1 phase by causing a decrease in Ki67, cyclin D1, and c-myc mRNA. Furthermore, MENK could induce tumor cell apoptosis associated with the upregulation of Bax, a corresponding downregulation of BCL-2 and survivin, and activation of caspase-3 and PARP. Moreover, MENK upregulated the expression of opioid receptors (OGFr) in SGC7901 and HGC27 cells. The interaction between MENK and OGFr in SGC7901 and HGC27 cells appears to be essential for the antitumor activity of MENK.

Conclusion

We conclude that MENK may be a potential drug for the treatment of GC.

Molecular cloning and functional characterisation of NLRX1 in grass carp (Ctenopharyngodon idella)

The nucleotide-binding domain and leucine-rich-repeat-containing (NLR) proteins regulate innate immunity. Although the positive regulatory impact of NLRs is clear, their inhibitory roles are not well defined. In the present study, the NLR family gene NLRX1 from grass carp (Ctenopharyngodon idella) was cloned and characterised. NLRX1 was widely expressed in all tissues examined, albeit at varying levels. After exposure to the grass carp reovirus (GCRV), NLRX1 mRNA expression levels were altered in immune organs, and dramatically altered in liver. Subcellular localisation indicated that NLRX1 protein co-localised with the mitochondria in the transfected cells. Additionally, the bimolecular fluorescence complementation (BiFC) system was introduced to detect the interaction between tumour necrosis factor (TNF) receptor associated factor 6 (TRAF6) and NLRX1. Moreover, deficient of NLRX1 in CIK cells with small interference RNA (siRNA) promoted polyinosinic:polycytidylic acid (poly (I:C))-induced IFN-related genes production, including IRF3, IRF7, and IFN-I, which reveals that NLRX1 is a negative regulator of IFN. Taken together, our results demonstrate that NLRX1 gene plays an important role in innate immune regulation and provide new insights into understanding the functional characteristics of the NLRX1 in teleosts.

Advancements in Host-Based Interventions for Influenza Treatment

Influenza is a major acute respiratory infection that causes mortality and morbidity worldwide. Two classes of conventional antivirals, M2 ion channel blockers and neuraminidase inhibitors, are mainstays in managing influenza disease to lessen symptoms while minimizing hospitalization and death in patients with severe influenza. However, the development of viral resistance to both drug classes has become a major public health concern. Vaccines are prophylaxis mainstays but are limited in efficacy due to the difficulty in matching predicted dominant viral strains to circulating strains. As such, other potential interventions are being explored. Since viruses rely on host cellular functions to replicate, recent therapeutic developments focus on targeting host factors involved in virus replication. Besides controlling virus replication, potential targets for drug development include controlling virus-induced host immune responses such as the recently suggested involvement of innate lymphoid cells and NADPH oxidases in influenza virus pathogenesis and immune cell metabolism. In this review, we will discuss the advancements in novel host-based interventions for treating influenza disease.