TY - JOUR
T1 - Morphine decreases the function of primary human natural killer cells by both TLR4 and opioid receptor signaling
AU - Maher, Dermot P.
AU - Walia, Deepa
AU - Heller, Nicola M.
N1 - Funding Information:
None of the contributing authors has any declared conflicts of interest within 12 months of submission. DPM received funding from a Blaustein Pain Research Fund Grant and NIH Grant 5T32GM075774. NMH receives funding from NIH Grant R01 HL124477 and DoD CDMRP W81XWH-16-1-0509. No copyrighted material from outside sources was used in preparation of this manuscript. This study has not been previously presented. All authors contributed equally to this manuscript and meet criteria based on the International Committee of Medical Journal Editors.
Publisher Copyright:
© 2019
PY - 2020/1
Y1 - 2020/1
N2 - Background: Opioids are commonly used to provide analgesia for cancer pain, and functional opioid receptors have been identified on natural killer (NK) cells, the lymphocytes responsible for surveillance and elimination of cancer cells. Opioids also bind to other lymphocyte receptors, such as Toll-like receptor (TLR)-4. Here, we characterized the effects of morphine on primary human NK cell cytotoxicity and mediator release, which occur through classical opioid receptor or TLR4 signaling. Methods: Purified primary human NK cells were pretreated with inhibitors of opioid receptors or TLR4 before being cultured with target tumor cell line K562 in the presence or absence of morphine. Apoptosis of K562 cells in each treatment condition was measured with an Annexin V flow cytometry-based assay and compared to that of K562 cells cultured with NK cells alone. Supernatant concentrations of 13 cytokines and cytotoxic mediators were measured with a multiplex bead-based flow cytometry assay. Results: Exposure of NK cells to morphine decreased their ability to induce apoptosis in K562 cells. Pretreating the NK cells with either naloxone, a mu- and kappa-opioid receptor antagonist, or TAK-242, a selective inhibitor of TLR4 signaling, prevented this effect. Paradoxically, morphine increased the concentration of interleukin-6, granzyme A, and granzyme B in cell supernatants. Pretreatment of NK cells with TAK-242 prevented the morphine-induced increase in interleukin-6, whereas pretreatment with naloxone inhibited the morphine-induced increase in granzymes A and B. Conclusions: Both classical opioid receptors and TLR4 participate in morphine-induced suppression of NK cell cytotoxic activity. These studies have important implications for maintenance of immune function during management of cancer pain.
AB - Background: Opioids are commonly used to provide analgesia for cancer pain, and functional opioid receptors have been identified on natural killer (NK) cells, the lymphocytes responsible for surveillance and elimination of cancer cells. Opioids also bind to other lymphocyte receptors, such as Toll-like receptor (TLR)-4. Here, we characterized the effects of morphine on primary human NK cell cytotoxicity and mediator release, which occur through classical opioid receptor or TLR4 signaling. Methods: Purified primary human NK cells were pretreated with inhibitors of opioid receptors or TLR4 before being cultured with target tumor cell line K562 in the presence or absence of morphine. Apoptosis of K562 cells in each treatment condition was measured with an Annexin V flow cytometry-based assay and compared to that of K562 cells cultured with NK cells alone. Supernatant concentrations of 13 cytokines and cytotoxic mediators were measured with a multiplex bead-based flow cytometry assay. Results: Exposure of NK cells to morphine decreased their ability to induce apoptosis in K562 cells. Pretreating the NK cells with either naloxone, a mu- and kappa-opioid receptor antagonist, or TAK-242, a selective inhibitor of TLR4 signaling, prevented this effect. Paradoxically, morphine increased the concentration of interleukin-6, granzyme A, and granzyme B in cell supernatants. Pretreatment of NK cells with TAK-242 prevented the morphine-induced increase in interleukin-6, whereas pretreatment with naloxone inhibited the morphine-induced increase in granzymes A and B. Conclusions: Both classical opioid receptors and TLR4 participate in morphine-induced suppression of NK cell cytotoxic activity. These studies have important implications for maintenance of immune function during management of cancer pain.
KW - Analgesia, opioid
KW - Killer cells, natural
KW - Receptors, natural killer cell
KW - Receptors, opioid
UR - http://www.scopus.com/inward/record.url?scp=85073750899&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85073750899&partnerID=8YFLogxK
U2 - 10.1016/j.bbi.2019.10.011
DO - 10.1016/j.bbi.2019.10.011
M3 - Article
C2 - 31626971
AN - SCOPUS:85073750899
VL - 83
SP - 298
EP - 302
JO - Brain, Behavior, and Immunity
JF - Brain, Behavior, and Immunity
SN - 0889-1591
ER -