Immunosuppression by opioids: Mechanisms of action on innate and adaptive immunity

Opioids are excellent analgesics for the clinical treatment of various types of acute and chronic pain, particularly cancer-related pain. Nevertheless, it is well known that opioids have some nasty side effects, including immunosuppression, which is commonly overlooked. As a result, the incidence of opportunistic bacterial and viral infections increases in patients with long-term opioid use. Nowadays, there are no effective medications to alleviate opioid-induced immunosuppression. Understanding the underlying molecular mechanism of opioids in immunosuppression can enable researchers to devise effective therapeutic interventions. This review comprehensively summarized the exogenous opioids-induced immunosuppressive effects and their underlying mechanisms, the regulatory roles of endogenous opioids on the immune system, the potential link between opioid immunosuppressive effect and the function of the central nervous system (CNS), and the future perspectives in this field.

The combined analgesic effect of pregabalin and morphine in the treatment of pancreatic cancer pain, a retrospective study

BACKGROUND

Pregabalin is commonly used to relieve neuropathic pain. However, data are lacking on its efficacy for the treatment of chronic cancer pain. The purpose of this study was to determine the analgesic efficacy of pregabalin combined with morphine in the management of pancreatic cancer pain.

METHODS

This study reviewed patients who were prescribed morphine and 150 mg/d pregabalin between 1 January 2017 and 10 November 2018 in our institute. The primary outcomes of this study were the average pain score and dose of morphine. Secondary outcomes included characters of breakthrough cancer pain, functional interference related to pain, anxiety/depression status, and incidence of treatment-related adverse events during the study.

RESULTS

A total of 240 patients with pain related to pancreatic cancer were included in the study. The results showed that patients of both combination therapy group (pregabalin+morphine) and monotherapy group (morphine) achieved similar analgesic efficacy, demonstrated by NRS (2.4 ± 0.9 vs. 2.6 ± 0.9; combination vs. monotherapy) at the end of the study. Mean daily dose of morphine used in the combination group was significant lower compared to monotherapy group (39.5 ± 16.0 mg vs. 61.5 ± 19.3 mg, net difference 23.5, 95% CI: 18.4-28.6, p <  0.001). The change of functional interference score related to pain was significantly different between combination and monotherapy group (12.0 ± 0.4 vs. 9.8 ± 4.9; net difference, 2.3; 95% CI: 1.1-3.3; p < 0.001). Patients in combination therapy group had experienced shorter duration of breakthrough cancer pain than those in monotherapy group (X² p < 0.001, Cramer's V:0.36). The incidence of somnolence, dizziness, and cognitive dysfunction were significantly higher in the combination group compared to monotherapy group. No serious treatment-related side effects were observed.

CONCLUSIONS

The findings of this study supported the use of pregabalin with morphine to relieve pain in patients of pancreatic cancer.

Evaluation of Murine Macrophage Cytokine Production After In Vivo Morphine Treatment

The discovery of opioid receptor expression on immune cells has originated a large research activity on the possible modulation by opioid drugs of immune system responses. In this chapter we describe an easy methodology useful to obtain information about the potential immunomodulatory activity of opioid drugs. An in vivo treatment schedule is used, and macrophages are studied for their ability to release different cytokines.