Association Between Activation of the Programmed Cell Death-1 (PD-1)/Programmed Death-Ligand 1 (PD-L1) Pathway and Pain in Patients with Cancer

PD-L1/PD-1 pathway: a potential neuroimmune target for pain relief

Pain is a common symptom of many diseases with a high incidence rate. Clinically, drug treatment, as the main method to relieve pain at present, is often accompanied by different degrees of adverse reactions. Therefore, it is urgent to gain a profound understanding of the pain mechanisms in order to develop advantageous analgesic targets. The PD-L1/PD-1 pathway, an important inhibitory molecule in the immune system, has taken part in regulating neuroinflammation and immune response. Accumulating evidence indicates that the PD-L1/PD-1 pathway is aberrantly activated in various pain models. And blocking PD-L1/PD-1 pathway will aggravate pain behaviors. This review aims to summarize the emerging evidence on the role of the PD-L1/PD-1 pathway in alleviating pain and provide an overview of the mechanisms involved in pain resolution, including the regulation of macrophages, microglia, T cells, as well as nociceptor neurons. However, its underlying mechanism still needs to be further elucidated in the future. In conclusion, despite more deep researches are needed, these pioneering studies indicate that PD-L1/PD-1 may be a potential neuroimmune target for pain relief.

Lung cancer patients with positive programmed death-ligand 1 expression endure graver postoperative pain

BACKGROUND

Postoperative pain after video-assisted thoracoscopic surgery (VATS) is common in lung cancer patients, and it is unclear whether cancer itself participates in pain regulation. Programmed cell death ligand-1 (PD-L1) expressed by tumours may be analgesic. Our study aimed to detect the association between PD-L1 and acute postoperative pain.

METHODS

We reviewed patients who underwent VATS for lung cancer with tumour PD-L1 expression analysed in our centre from Jan 2017 to Jul 2020. They were divided into PD-L1 (-) group and PD-L1 (+) group and were further divided into four subgroups according to opioids for postoperative analgesia: sufentanil PD-L1 (-), sufentanil PD-L1 (+), oxycodone PD-L1 (-), and oxycodone PD-L1 (+). We compared the numeric rating scale (NRS) for the first three postoperative days at rest or cough between groups.

RESULTS

A total of 369 patients (167 in PD-L1 (-) vs. 202 in PD-L1 (+)) were included. On the first postoperative day, NRS at cough in the PD-L1 (+) patients were higher than those in the PD-L1 (-) patients (2.91 ± 1.07 vs. 2.66 ± 1.01, p = 0.018). On the third day, NRS at cough in PD-L1 (+) patients was higher (2.50 ± 1.02 vs. 2.26 ± 1.09, p = 0.043). For patients with oxycodone, NRS was higher in PD-L1 (+) than in PD-L1 (-) (p = 0.041) at cough after surgery. In contrast, those with sufentanil did not significantly differ in NRS between groups.

CONCLUSIONS

Patients with PD-L1 (+) suffered graver pain in the early postoperative period after VATS for lung cancer compared with PD-L1 (-) on tumours. Analgesia with sufentanil seemed to overcome this effect better than oxycodone.

SIGNIFICANCE

We demonstrated that patients with positive programmed cell death ligand-1 (PD-L1) on tumours suffered graver pain in the early postoperative period after video-assisted thoracoscopic surgery for lung cancer and reacted differently with opioids. It might be beneficial to adjust analgesic protocols according to tumour PD-L1 expression for individualized postoperative pain management.

Emerging Role of PD-1 in the Central Nervous System and Brain Diseases

Programmed cell death protein 1 (PD-1) is an immune checkpoint modulator and a major target of immunotherapy as anti-PD-1 monoclonal antibodies have demonstrated remarkable efficacy in cancer treatment. Accumulating evidence suggests an important role of PD-1 in the central nervous system (CNS). PD-1 has been implicated in CNS disorders such as brain tumors, Alzheimer's disease, ischemic stroke, spinal cord injury, multiple sclerosis, cognitive function, and pain. PD-1 signaling suppresses the CNS immune response via resident microglia and infiltrating peripheral immune cells. Notably, PD-1 is also widely expressed in neurons and suppresses neuronal activity via downstream Src homology 2 domain-containing protein tyrosine phosphatase 1 and modulation of ion channel function. An improved understanding of PD-1 signaling in the cross-talk between glial cells, neurons, and peripheral immune cells in the CNS will shed light on immunomodulation, neuromodulation, and novel strategies for treating brain diseases.

The relationship between the expression of soluble programmed cell death-1 and cancer pain: A protocol for systematic review and meta analysis

BACKGROUND

The immune checkpoint programmed cell death-1 (PD-1) plays a critical role in immune regulation. Recent studies have demonstrated functional PD-1 expression in peripheral sensory neurons, which contributes to neuronal excitability, pain, and opioid analgesia. However, the relationship between the expression of soluble programmed cell death-1(sPD-1) and cancer pain is controversial. The purpose of this study was to evaluate the relationship between sPD-1 expression level and cancer pain through meta-analysis.

METHODS

Studies were selected from Pubmed, Web of science, Embase, Google Scholar, and Chinese National Knowledge Infrastructure, and the Chinese Biomedical Literature Database based on inclusion and exclusion criteria. The standard mean difference (SMD) and 95% confidence interval (CI) were calculated using the random-effect model or fixed-effect model to assess the association between sPD-1 expression level and cancer pain. All analyses were performed with the Stata 14 software.

RESULTS

This review will be disseminated in print by peer-review.

CONCLUSION

The results of this study will help us to determine whether the expression level of sPD-1 is related to cancer pain.

ETHICS AND DISSEMINATION

The private information from individuals will not be published. This systematic review also should not endanger participant rights. Ethical approval is not available. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/WDPUY.

Pain Biomarkers in Cancer: An Overview

BACKGROUND

Pain is a common symptom in oncologic patients and its management is generally guided with reference to pain individually perceived by patients and expressed through self-reported scales. However, the utility of these tools is limited as it strongly depends on patients' opinions. For this reason, more objective instruments are desirable.

OBJECTIVE

In this overview, scientific articles indicating potential markers to be used for pain management in cancer were collected and discussed.

METHODS

Research was performed on principal electronic scientific databases by using the words "pain", "cancer", "markers" and "biomarkers" as the main keywords, and findings describing potential biomarkers for the management of cancer pain were reported.

RESULTS

Studies on pain markers not specific for cancer typology (inflammatory, genetic markers predicting response to analgesic drugs, neuroimaging markers) and pain markers for specific types of cancer (bone cancer, breast cancer, lung cancer, head and neck cancer, prostate cancer, cancer in pediatrics) have been presented and commented on.

CONCLUSION

This overview supports the view of the involvement of inflammatory mediators in the mechanisms underlying cancer pain. Only a small amount of data from research up till today is available on markers that can help in the management of pain, except for pro-inflammatory cytokines and other inflammatory indexes such as C-reactive protein (CRP). However, biomarkers are a promising strategy useful to predict pain intensity and to objectively quantify analgesic response in guiding decisions regarding individual-tailored treatments for cancer patients.

Acupuncture for chronic cancer-related pain: a systematic review and network meta-analysis protocol

INTRODUCTION

Chronic cancer-related pain is one of the most common excruciating symptom that can be caused by the cancer (by the primary tumour or by metastases) or by its treatment (surgery, chemotherapy and radiotherapy). Although multiple clinical trials and systematic reviews have suggested that acupuncture could be effective in treating chronic cancer-related pain, the comparative efficacy and safety of these acupuncture methods remains unclear. We, therefore, performed this study to evaluate and rank the efficacy and safety of different acupuncture methods for chronic cancer-related pain.

METHODS AND ANALYSIS

Seven databases will be searched, including Cochrane Library, MEDLINE, Embase, Chinese National Knowledge Infrastructure (CNKI), Wanfang Database, the Chongqing VIP Chinese Science and Technology Periodical Database and Chinese Biomedical Literature Database (CBM) from their inception to March 2020. The primary outcome is the change of pain intensity. Bayesian network meta-analysis will be conducted using software R3.5.1. Finally, we will use the Grading of Recommendations Assessment, Development and Evaluation System (GRADE) to assess the quality of evidence.

ETHICS AND DISSEMINATION

Ethical approval is not required for literature-based studies. The results will be disseminated through peer-reviewed publication.

PROSPERO REGISTRATION NUMBER

CRD42020165747.

Novel Analgesics with Peripheral Targets

A limited number of peripheral targets generate pain. Inflammatory mediators can sensitize these. The review addresses targets acting exclusively or predominantly on sensory neurons, mediators involved in inflammation targeting sensory neurons, and mediators involved in a more general inflammatory process, of which an analgesic effect secondary to an anti-inflammatory effect can be expected. Different approaches to address these systems are discussed, including scavenging proinflammatory mediators, applying anti-inflammatory mediators, and inhibiting proinflammatory or facilitating anti-inflammatory receptors. New approaches are contrasted to established ones; the current stage of progress is mentioned, in particular considering whether there is data from a molecular and cellular level, from animals, or from human trials, including an early stage after a market release. An overview of publication activity is presented, considering a IuPhar/BPS-curated list of targets with restriction to pain-related publications, which was also used to identify topics.

Probiotic-Treated Super-Charged NK Cells Efficiently Clear Poorly Differentiated Pancreatic Tumors in Hu-BLT Mice

Abstract: Background and Aims: We have previously demonstrated that the stage of differentiation of tumors has profound effect on the function of NK cells, and that stem-like/poorly differentiated tumors were preferentially targeted by the NK cells. Therefore, in this study we determined the role of super-charged NK cells in immune mobilization, lysis, and differentiation of stem-like/undifferentiated tumors implanted in the pancreas of humanized-BLT (hu-BLT) mice fed with or without AJ2 probiotics. The phenotype, growth rate and metastatic potential of pancreatic tumors differentiated by the NK cells (NK-differentiated) or patient derived differentiated or stem-like/undifferentiated pancreatic tumors were investigated. Methods: Pancreatic tumor implantation was performed in NSG and hu-BLT mice. Stage of differentiation of tumors was determined using our published criteria for well-differentiated tumors exhibiting higher surface expression of MHC- class I, CD54, and PD-L1 (B7H1) and lower expression of CD44 receptors. The inverse was seen for poorly-differentiated tumors. Results: Stem-like/undifferentiated pancreatic tumors grew rapidly and formed large tumors and exhibited lower expression of above-mentioned differentiation antigens in the pancreas of NSG and hu-BLT mice. Unlike stem-like/undifferentiated tumors, NK-differentiated MP2 (MiaPaCa-2) tumors or patient-derived differentiated tumors were not able to grow or grew smaller tumors, and were unable to metastasize in NSG or hu-BLT mice, and they were susceptible to chemotherapeutic drugs. Stem-like/undifferentiated pancreatic tumors implanted in the pancreas of hu-BLT mice and injected with super-charged NK cells formed much smaller tumors, proliferated less, and exhibited differentiated phenotype. When differentiation of stem-like tumors by the NK cells was prevented by the addition of antibodies to IFN-γ and TNF-α, tumors grew rapidly and metastasized, and they remained resistant to chemotherapeutic drugs. Greater numbers of immune cells infiltrated the tumors of NK-injected and AJ2-probiotic bacteria-fed mice. Moreover, increased IFN-γ secretion in the presence of decreased IL-6 was seen in tumors resected and cultured from NK-injected and AJ2 fed mice. Tumor-induced decreases in NK cytotoxicity and IFN-γ secretion were restored/increased within PBMCs, spleen, and bone marrow when mice received NK cells and were fed with AJ2. Conclusion: NK cells prevent growth of pancreatic tumors through lysis and differentiation, thereby curtailing the growth and metastatic potential of stem-like/undifferentiated-tumors.