Effect of systemic injection of heterogenous and homogenous opioids on peripheral cellular immune response in rats with bone cancer pain: A comparative study

Involvement of the Opioid Peptide Family in Cancer Progression

Peptides mediate cancer progression favoring the mitogenesis, migration, and invasion of tumor cells, promoting metastasis and anti-apoptotic mechanisms, and facilitating angiogenesis/lymphangiogenesis. Tumor cells overexpress peptide receptors, crucial targets for developing specific treatments against cancer cells using peptide receptor antagonists and promoting apoptosis in tumor cells. Opioids exert an antitumoral effect, whereas others promote tumor growth and metastasis. This review updates the findings regarding the involvement of opioid peptides (enkephalins, endorphins, and dynorphins) in cancer development. Anticancer therapeutic strategies targeting the opioid peptidergic system and the main research lines to be developed regarding the topic reviewed are suggested. There is much to investigate about opioid peptides and cancer: basic information is scarce, incomplete, or absent in many tumors. This knowledge is crucial since promising anticancer strategies could be developed alone or in combination therapies with chemotherapy/radiotherapy.

Knowledge Mapping of Opioids and Immunomodulation: A Bibliometric Analysis (2000-2022)

Background

Increasing evidence indicates that opioids markedly affect the immune system. However, there are few studies on opioids and immunomodulation using bibliometric analysis.

Purpose

We aimed to provide a comprehensive overview of the research status and trends of the influence of opioids on immunomodulation using a bibliometric approach.

Methods

Articles related to opioids and immunomodulation published from 2000 to 2022 were obtained from the Science Citation Index Expanded of the Web of Science Core Collection by searching keywords related to opioids and immunomodulation. Bibliometric analyses and visualizations were conducted using the CiteSpace and VOSviewer software programs.

Results

From 2000 to 2022, a total of 3242 research articles on opioids and immunomodulation were published in 1126 academic journals by 16,555 authors in 3368 institutions from 102 countries/regions. A majority of publications were from the US and China, and the University of Minnesota System and Chinese Academy of Sciences were the most active institutions. Tsong-long Hwang had published the most papers, while Sabita Roy had the most cocitations. The Journal of Ethnopharmacology published the most papers on opioids and immunomodulation, the Journal of Immunology was the top cocited journal, and the major area of these publications were molecular, biological, and genetic. The top three keywords were "expression", "activation", and "inflammation."

Conclusion

The number of studies on opioids and immunomodulation has increased sharply all over the world in the last two decades. This is the first bibliometric study to comprehensively summarize the collaboration network in this field. It will help scholars to understand not only the basic knowledge structure but also potential collaborations, research trend topics, and hot directions.

Morphine suppresses the immune function of lung cancer by up-regulating MAEL expression

BACKGROUND

Patients with cancer rely on morphine for analgesia, while studies have indicated morphine can induce immunosuppression in cancer. Therefore, investigating the immunosuppressive roles and molecular mechanism of morphine on lung cancer progression is imperative.

METHODS

Lactate dehydrogenase (LDH) release assay was used to determine the cytotoxicity of morphine to lung cancer cells. The percentage of CD4⁺ and CD8⁺ T cells was detected by flow cytometry. In addition, Maelstrom (MAEL), Nrf2, and PTEN were determined by western blot and RT-qPCR. Immune factors programmed death-ligand 1 (PD-L1), transforming growth factor (TGF-β), interleukin (IL)-10, and IL-2 were determined by western blot and ELISA assay.

RESULTS

Morphine increased the levels of PD-L1, TGF-β, and IL-10, while decreased IL-2 level. Morphine enhanced MAEL expression in A549 cells and H460 cells. Morphine up-regulated Nrf2 and down-regulated PTEN, and morphine-induced MAEL up-regulation was reversed by PTEN. However, MAEL silencing inhibited the enhanced effects of morphine on cell viability and proliferation of A549 cells. Furthermore, morphine treatment reduced the LDH release and the percentage of CD8⁺ T cells, and increased the ratio of CD4⁺/CD8⁺ T cells and tumor weight. Meanwhile, MAEL silencing reversed the effects of morphine on immune factors (PD-L1, TGF-β, IL-10, and IL-2), the percentage of CD8⁺ T cells, and the ratio of CD4⁺/CD8⁺ T cells.

CONCLUSION

Morphine activated MAEL in lung cancer cells by Nrf2/PTEN pathway and regulated the immune factors, thereby promoting tumor immune escape.

The other side of the coin: Positive view on the role of opioids in cancer

Opioids have been used for medicinal purposes as an analgesic and recreational purposes as a euphorigenic throughout human history. Cancer patients are often treated with different doses of opioids concurrently with anti-cancer drugs for pain relief without exhibiting excessive adverse effects. The intersection of the biology of pain, opioid therapy, and disease progression represents the crux of the matters and is of potentially great importance in cancer care. For more than 20 years, multiple investigations have focused on the stimulatory effects of opioids on cancer cell growth, while in-depth studies on the inhibitory effects on cancer cell growth development have usually been neglected. This paper reviews the evidence regarding opioid therapies and their anti-cancer effects on various malignancies. Likewise, we have a glimpse into the molecular mechanisms necessary for pinpointing their positive or negative impacts on malignancies to raise awareness and stimulate more excellent dialogue regarding their carcinogenic/anticarcinogenic roles.

Phosphoproteomic Profiling of Rat's Dorsal Root Ganglia Reveals mTOR as a Potential Target in Bone Cancer Pain and Electro-Acupuncture's Analgesia

Bone cancer pain (BCP) is a clinical refractory mixed pain involving neuropathic and inflammatory pain, with the underlying mechanisms remaining largely unknown. Electro-acupuncture (EA) can partly alleviate BCP according to previous research. We aim to explore the proteins and major pathways involved in BCP and EA treatment through phosphoproteomic profiling. BCP rat model was built by tibial inoculation of MRMT-1 mammary gland carcinoma cells. Mechanical hyperalgesia determined by paw withdrawal thresholds (PWTs) and bone destruction manifested on the radiographs confirmed the success of modeling, which were attenuated by EA treatment. The differentially expressed phosphorylated proteins (DEPs) co-regulated by BCP modeling and EA treatment in rat dorsal root ganglions (DRGs) were analyzed through PEX100 Protein microarray. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that DEPs were significantly enriched in mammalian target of rapamycin (mTOR) signaling pathway. The phosphorylations of mTOR at Ser2448 and Thr2446 were increased in BCP and downregulated by EA. In addition, the phosphorylation of S6K and Akt, markers of the mTOR complex, were also increased in BCP and downregulated by EA. Inhibition of mTOR signaling alleviated the PWTs of BCP rats, while the mTOR agonist impaired the analgesic effect of EA. Thus, our study provided a landscape of protein phosphorylation changes in DRGs of EA-treated BCP rats and revealed that mTOR signaling can be potentially targeted to alleviate BCP by EA treatment.

Electroacupuncture Attenuates Surgical Stress-Induced Reduction of T Lymphocytes through Modulation of Peripheral Opioid System

OBJECTIVE

To investigate the action mechanisms of electroacupuncture (EA) on postoperative immunosuppression.

METHODS

Male C57BL/6 mice (5`-7 weeks old) were randomly divided into: the sham injury group, the surgical trauma stressed group, the EA group [surgery + 2/100 Hz EA at Neiguan (PC 6)], and the EA+ Nal (surgery + EA + intraperitoneal injection of naloxone). Abdominal surgical trauma stress mice model was established. EA was performed on bilateral PC 6 acupoints by an EA apparatus (2/100 Hz) for 20 min once a day for 3 days. The mRNA expressions of MOR, DOR, and KOR in thymus and L3`-L5 dorsal root ganglions (DRG) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and the protein expressions of MOR, DOR, and KOR in thymus were measured by Western blot. Flow cytometry assay was used to detect the levels of T lymphocyte subtypes in the peripheral blood.

RESULTS

Surgical trauma induced decreased the mRNA expression level of MOR in both thymus (P<0.01) and L3`-L5 DRGs (P<0.05). Moreover, EA treatment not only significantly attenuated the MOR protein and mRNA expression in the thymus (both P<0.05), but also markedly increased expression of DOR and KOR opioid receptor in thymus (P<0.01). However, the mRNA expressions of opioid receptors were not regulated by EA in the DRG (all P>0.05). Furthermore, T lymphocyte population of CD3⁺ and CD4⁺ was decreased in the peripheral blood after surgical trauma (both P<0.01). EA treatment can significantly elevate the population of CD₃⁺ (P<0.01), CD₄⁺ (P<0.05) and CD₈⁺ T cells (P<0.01). Intraperitoneal injection of the non-selective opioid receptor antagonist naloxone blocked the up-regulation of T lymphocytes by EA.

CONCLUSION

EA may improve postoperative immunosuppression through the peripheral opioid system.

Different Processed Products of Curcumae Radix Regulate Pain-Related Substances in a Rat Model of Qi Stagnation and Blood Stasis

Background

Curcumae blood Radix (Yujin) has been widely used to treat Qi stagnation and stasis in TCM. According to the Chinese Pharmacopoeia, the tuberous roots of Curcuma longed L. (i.e., Huangsiyujin, HSYJ) is one of the major species of Yujin. According to the processing theory of TCM, stir-frying HSYJ with vinegar might strengthen the effect of dispersing stagnated hepatoqi to relieve pain, and stir-frying HSYJ with wine might strengthen the effect of promoting blood circulation in order to remove blood stasis. However, the mechanism for the enhancement of clinical efficacy by processing is unclear.

Aim/Hypothesis

This study was aimed at evaluating the effect of different processed products of HSYJ on chemical constituents and pain-related substances to explore underlying mechanisms of HSYJ in treating pain caused by Qi stagnation and blood stasis.

Methods

The effects of different processing methods on the paste yield of water decoction were analyzed, and the content of the main constituents were detected by HPLC. A rat model of Qi stagnation and blood stasis was established by tail clamp stimulation combined with subcutaneous adrenaline injection. After treatment and intervention with HSYJ and its processed products, β-endorphin (β-EP) and 5-hydroxytryptamine (5-HT) were measured by ELISA, and the expression of c-fos was evaluated by immunohistochemistry.

Results

After stir-frying with vinegar or wine, the extract yield and curcumin content increased. Compared with model group, raw HSYJ could significantly improve the abnormality of 5-HT in plasma (P < 0.05) and β-EP in brain (P < 0.01). Stir-frying HSYJ with vinegar or wine could significantly improve the abnormality of 5-HT in plasma, β-EP in brain, and the expression of c-fos (P < 0.01). Stir-frying HSYJ with vinegar could also significantly increase the level of β-EP in plasma (P < 0.05).

Conclusion

These results showed that different processing methods have certain effects on the chemical constituents of HSYJ, mainly in increasing the decoction rate and curcumin content. HSYJ and its processed products can reduce 5-HT levels, increase β-EP levels, and inhibit the expression of c-fos in model rats. The effects of stir-frying HSYJ with vinegar on β-EP levels in plasma was superior to others.

Opioids in Cancer Development, Progression and Metastasis: Focus on Colorectal Cancer

OPINION STATEMENT

So far, opioids have been successfully used to reduce cancer pain in patients in order to improve their quality of life. However, the use of opioids leads to numerous side effects such as constipation, drowsiness, nausea, itching, increased sweating and hormonal changes. In this review, we described the action of opioids in several molecular pathways significant for maintenance of the intestinal homeostasis including the impact on the intestinal epithelium integrity, changes in microbiome composition, modulation of the immune system or induction of apoptosis and inhibition of angiogenesis. We summed up the role of individual opioids in the processes involved in the growth and development of cancer and elucidated if targeting opioid receptors may constitute novel therapeutic option in colon cancer.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Postoperative opioids, endocrine changes, and immunosuppression

Opioids are among most effective drugs for managing acute postoperative pain. This article discusses the potential effects of perioperative opioids on endocrine and immune function.

Alleviating Mechanical Allodynia and Modulating Cellular Immunity Contribute to Electroacupuncture's Dual Effect on Bone Cancer Pain

Hypothesis: Electroacupuncture (EA) has been used as an alternative analgesic therapy for hundreds of years, yet its analgesic potency and therapeutic advantage against bone cancer pain (BCP) in comparison with morphine remains unclear. This study aimed to investigate the effects of EA on mechanical allodynia and cellular immunity of BCP rats, and to further explore the potential mechanism. Methods: The BCP model was established by implanting Walker 256 mammary gland carcinoma cells into the left tibia of adult female Sprague-Dawley rats. EA (dilatational wave, 2/100 Hz, 0.5 mA–1mA–1.5 mA for 10 minutes each intensity) was applied bilaterally to Zusanli (ST 36) and Kunlun (BL 60) for 30 minutes. Both EA stimulation and morphine (10 mg/kg, intraperitoneally) was given once every other day. Naloxone (0.3 mg/kg, intraperitoneally) was injected at 30 minutes prior to EA. Mechanical allodynia were demonstrated by paw withdrawal thresholds (PWTs) which measured by dynamic plantar aesthesiometer. T cell proliferation, percentage of CD3⁺, CD4⁺ and CD8⁺ T lymphocytes in spleen as well as expression of interleukin-2 (IL-2) in plasma were detected by WST-8, flow cytometry, and enzyme-linked immunosorbent assay technique, respectively. Results: An intratibial inoculation of Walker 256 mammary gland carcinoma cells significantly decreased PWTs to mechanical stimuli. EA stimulation alleviated mechanical allodynia in BCP rats, and the analgesic potency of EA was weaker than that of morphine. In contrast to morphine, EA stimulation of BCP rats increased splenic concanavalin A (Con A)-induced T cell proliferation and plasma IL-2 content, as well as increased the percentages of splenic CD₃⁺CD₄⁺ and CD₃⁺CD₈⁺ T cell subsets. Moreover, both the analgesic effect and the partial immunomodulation of EA were suppressed by an intraperitoneal injection of naloxone. Conclusion: EA could significantly alleviate BCP-induced mechanical allodynia. Although the analgesic effect of EA was weaker than that of morphine, EA had an immunomodulation effect on cellular immunity. Both analgesic and immunomodulatory effect of EA might share the same mechanism via the opioid-mediated pathway, which needs further investigation.