Presenter:Hayden Isaacs(Class of 2019)

PI:Dr. S. Mohan

Assistant ProfessorDPSR

Bench to Bedside: Role of IL-1beta in Morphine Tolerance Using a Mouse Model for Postoperative

Pain

INTRODUCTION & RELEVANCE -Postoperative Pain

Pain● Most feared problem among patients

● Inadequately treated in 50% of all surgical procedures

● More than 80% of patients experience postoperative pain● 71% experience moderate to severe pain

● 75% believe it is “necessary to feel pain following surgery”● 8% postpone surgery because of concerns associated regarding pain 

Apfebaum JL et alk., Anesth Analg 2003:97, 534-540Gottschal A, Smith DS, Am Fam Physician 2001,63: 1979-1984

INTRODUCTION & RELEVANCE -Morphine and Tolerance

● Morphine - an opioid pain medication that is used to treat moderate to severe pain.

●Can lead to a multimodal (use of more than one drug) practice which is being used more frequently for pain relief.

●Tolerance can be quick to develop.

● Tolerance - is a person's diminished response to a drug, which occurs when the drug is used repeatedly and the body adapts to the continued presence of the drug. 

INTRODUCTION & RELEVANCE -Mechanism behind opioid tolerance

● Mu-opioid receptor is G-protein coupled receptor (GPCR) and when activated ●leads to decreased excitation of pain pathway

● Agonist stimulation inhibits cAMP formation which leads to suppression of Na+ and Ca+ channels resulting in analgesia

● Over time G-Proteins in the G-protein mediated mechanism can lead to decreased excitability through opioid receptor desensitization

●IL-1 beta is a pro-inflammatory cytokine that is produced by activated macrophages and glial cells during inflammatory conditions

●IL-1 beta affects opiate-dependent pathways by upregulating the expression of the mu-opioid receptor

●IL-1 beta activates IL-1R and can result in the NF-kappa beta mediated increase in cytokines, chemokines and adhesion factors involved in tissue injury and inflammation

INTRODUCTION & RELEVANCE –Interleukin-1beta (IL-1beta)

To determine whether blockade of the IL-R1 limits morphine tolerance and dependence in a post-operative pain model using WT and IL-R1-/- mice

RESEARCH AIM

RESEARCH HYPOTHESIS

Our hypothesis is that deletion of the IL-R1 receptor will alleviate pain and decrease the incidence of opioid-induced hyperalgesia

STUDY DESIGN AND METHODSThree-day study

● B57/BL6 (B6) mice:● Wild-type (n=10; 5 each for morphine and saline)

● IL-1R KO (n=10; 5 each for morphine and saline)

● Pain (acute) model:● 5 mm plantar incision on the right hindpaw

● P0: day of surgery

● P1-3: postoperative days ● Morphine (10mg/kg, s.c.) injected once-daily

MECHANICAL SENSITIVITY

Brennan et al., 2009

METHODS (Cont.)

● Three devices used to conduct behavioral studies:

● Dynamic Plantar Anesthesiometer (Von Frey)

●Mechanical

● Plantar Test (Hargreaves method) Analgesia Meter

●Heat

● Rotarod●Motor Coordination

MECHANICAL SENSITIVITY

HEAT SENSITIVITY

MOTOR COORDINATION

Site of testing

Results – mechanical sensitivityThree-day study

Post incision injury (day)

Tim

e (s

ec)

Tim

e (s

ec)

N = 5 N = 5 Post incision injury (day)

Ipsilateral (right) hindpaw

Results – heat sensitivityThree-day study

Tim

e (s

ec)

Tim

e (s

ec)

N = 5 N = 5Post incision injury (day) Post incision injury (day)

Ipsilateral (right) hindpaw

Results – motor coordinationThree-day study

Tim

e (s

ec)

Tim

e (s

ec)

N = 5 N = 5Post incision injury (day) Post incision injury (day)

Conclusion and Future Studies

In the morphine treated groups:●differences were found in mechanical, heat and motor coordination between

WT and IL-1R KO mice at post-op., day 2 and 3

Future studies:●Conducted a longer six-day study (morphine injected (10mg/kg S.c.) daily●Measure changes in genes – IL-1b and NMDAR in skin, spinal cord and brain

tissues

Acknowledgements

Thank you:●Dr. Mohan Ph.D. (PI)●Hannah Claar (Class of 2019)

●Sarah Stevens (MU-BMS Ph.D. graduate student)

ReferencesByrne, Linda Staikos et al. “Interleukin-1 Beta-Induced up-Regulation of Opioid Receptors in the

Untreated and Morphine-Desensitized U87 MG Human Astrocytoma Cells.” J of Neuroinflammation 9 (2012): 252

Viviani, B., et al. "Interleukin-1β Enhances Nmda Receptor-Mediated Intracellular Calcium Increase through Activation of the Src Family of Kinases." J of Neuroscience 23.25 (2003): 8692-700

Mohan, Shekher et al. “Dual Regulation of mu Opioid Receptors in SK-N-SH Neuroblastoma Cells by Morphine and Interleukin-1β: Evidence for Opioid-Immune Crosstalk.” J of neuroimmunology 227.1-2 (2010): 26–34