22 - Methadone and Buprenorphine Increase Circulating Pro-Inflammatory Cytokines and Induce Inflammatory Microglial Genes after Perinatal Exposure

Monday, May 1, 2023

9:30 AM – 11:30 AM ET

Poster Number: 22
Publication Number: 22.434

Balaji G. Vijayakumar, Johns Hopkins University, Baltimore, MD, United States; Yuma Kitase, Johns Hopkins school of Medicine, Baltimore, MD, United States; Nethra Madurai, Johns Hopkins Hospital, Lutherville-Timonium, MD, United States; Shenandoah Robinson, Johns Hopkins Children's Center, Baltimore, MD, United States; Lauren Jantzie, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Presenting Author(s)

Balaji G. Vijayakumar (he/him/his)

Graduate Student
Johns Hopkins University
Baltimore, Maryland, United States

Background:

The impact of opioid exposure on childhood development compels a better understanding of the causes of neural injury and highlight the neurodevelopmental consequences of immune activation following perinatal opioid exposure (POE). Advances in molecular neuroscience reveal the importance of the multifaceted interplay of the central and peripheral immune systems in regulating brain development. Studies to identify the mechanisms of injury caused by POE with buprenorphine and methadone are essential.

Objective:

To test the hypothesis that methadone and buprenorphine elicit a peripheral inflammatory response and molecular microglial inflammatory changes in an established preclinical model of POE.

Design/Methods:

Over 28 days, pregnant Sprague Dawley dams received continuous infusion of 12 mg/kg methadone, 1 mg/kg buprenorphine, or saline by osmotic mini pump infusion (0.25μL/h flow rate). On postnatal day 10 (P10, term equivalent) serum was collected and assayed for inflammatory biomarkers using a clinically translatable biomarker platform. Inflammatory genes were assessed by qPCR in cortex and isolated microglia. Statistically significant differences were found by comparing saline to methadone or buprenorphine groups with p< 0.05 considered significant (t-test, n=8-15/group).

Results:

Pups exposed to methadone or buprenorphine had significantly elevated levels of IL-1β (p< 0.05), TNFα (p< 0.01), IL-6 (p< 0.001) and CXCL1 (p< 0.01) in serum at P10 compared to controls, consistent with a POE-induced systemic inflammatory response syndrome. Analysis of cortical gene expression revealed increases in inflammatory cytokine, chemokine, and cognate receptor levels in methadone and buprenorphine exposed pups, including CD86 (p< 0.01), CD206 (p< 0.05), CXCR2 (p< 0.01) and CXCL1(p< 0.05). Methadone increased microglial TLR4 (p< 0.05) and iNOS (p< 0.01) gene expression compared to controls, consistent with a pro-inflammatory microenvironment.

Conclusion(s): Methadone and buprenorphine cause systemic inflammation and yield a cerebral inflammatory signature defined by increases in multiple pro-inflammatory proteins and alterations in microglial genes at critical periods of CNS development. TLR4-mediated microglial changes and immune activation have implications for maladaptive opioid-induced neuroplasticity. More research is urgently needed to understand the functional consequences of POE and the impact of inflammatory changes on dynamic neural circuitry.