The Interplay between Chronic Pain, Opioids, and the Immune System

Abstract

Chronic pain represents one of the most serious worldwide medical problems, in terms of both social and economic costs, often causing severe and intractable physical and psychological suffering. The lack of biological markers for pain, which could assist in forming clearer diagnoses and prognoses, makes chronic pain therapy particularly arduous and sometimes harmful. Opioids are used worldwide to treat chronic pain conditions, but there is still an ambiguous and inadequate understanding about their therapeutic use, mostly because of their dual effect in acutely reducing pain and inducing, at the same time, tolerance, dependence, and a risk for opioid use disorder. In addition, clinical studies suggest that opioid treatment can be associated with a high risk of immune suppression and the development of inflammatory events, worsening the chronic pain status itself. While opioid peptides and receptors are expressed in both central and peripheral nervous cells, immune cells, and tissues, the role of opioids and their receptors, when and why they are activated endogenously and what their exact role is in chronic pain pathways is still poorly understood. Thus, in this review we aim to highlight the interplay between pain and immune system, focusing on opioids and their receptors.

Opioid usage and COVID-19 prognosis: A systematic review and meta-analysis

“…The pandemic has exacerbated the opioid crisis by disrupting this care, further increasing numbers of overdose events as well as opioid-related hospitalizations and deaths [ [11] , [12] , [13] ]. Opioids are also known to have immunosuppressive effects; thus, long-term use of opioids is associated with increased risk of infections and mortality [ 14 , 15 ]. The use of prescribed opioids in active-phase cancer treatment, palliative care, and end-of-life care may therefore disproportionately affect the already immunocompromised patient.…”

The Protective Effect of Bergamot Polyphenolic Fraction (BPF) on Chemotherapy-Induced Neuropathic Pain

“…This mechanism, accompanied by an increase in oxidative stress is also responsible for the alteration of the glial transpostrator and glutamate functionality [25,59]. Obviously, it should be remembered that these mechanisms have been found not only in CIPN but also in inflammatory, neuropathic pain and morphine-induced tolerance, and hyperalgesia [15,28,38,55,59,60].…”

Neutrophil-to-Lymphocyte Ratio as an Indicator of Opioid-Induced Immunosuppression After Thoracoscopic Surgery: A Randomized Controlled Trial

“…Opioids have been a major focus of medical research because of their critical role in pain management, especially in anesthesia during perioperation. 14 , 15 Opioids can produce powerful analgesia, which is effective in treating severe pain. However, it has some common adverse effects, one of which is related to immune function.…”