Biologic Mechanisms for Pain Variation After Physical Activity in Osteoarthritis

Bioenergetics, Inflammation, and Protein Expression as Mechanisms for Variation in Pain Sensitivity After Physical Activity in Adults With Knee Osteoarthritis

Osteoarthritis (OA) in the knee is characterized by chronic inflammatory pain that is not necessarily related to the amount of joint damage. Clinical practice guidelines recommend physical activity (PA) for osteoarthritis pain, but most adults with OA do not engage in PA. One reason for this is that while PA can reduce OA related joint pain, it does not work for everyone. PA decreases pain sensitivity for about half of adults with OA but increases pain sensitivity for the other half. The investigators are hypothesizing that individual differences in how well cells work to make energy, inflammation, and different proteins available in blood cells explains who PA will work to reduce pain and who it won't among adults with OA. The purpose of this pilot study is to determine if blood cells' ability to make cellular energy, inflammation and proteins help explain the difference about who PA reduces activity for and who it doesn't. The investigators will compare these biologic factors and pain sensitivity before walking, immediately after 30 minutes of walking (i.e. "acute") and after six weeks of walking three times a week for 30 minutes (i.e. "long-term") in adults with hip or knee osteoarthritis. The investigators will also compare these results to adults without OA. The investigators will recruit a sample of 40 adults with radiologic (e.g x-ray or CT scan) evidence of hip or knee OA and 20 age/gender matched healthy adults without OA to address the following study aims: Aim 1: To examine the effects of a six week (three days/week) walking program on pain in adults with OA as compared to healthy controls. Aim 2: To test the cells' ability to make energy as a mechanism for variation in pain after "acute" and "long-term" PA in older adults with lower extremity osteoarthritis. Aim3: To test the role of inflammation as a mechanism for variation in pain after "acute" and "long-term" physical activity in adults with lower extremity osteoarthritis. Aim 4: To generate hypotheses regarding the role of proteomics in variation in pain after "acute" and "long-term" physical activity.

Study Overview

• Status: Completed
• Conditions: Pain; Physical Activity; Osteoarthritis, Knee; Mitochondrial Pathology
• Intervention / Treatment: Behavioral: Walking

Detailed Description

Osteoarthritis (OA) in the knee is characterized by chronic inflammatory pain that is not necessarily associated with the amount of joint damage.1 Clinical practice guidelines recommend physical activity (PA) for osteoarthritis pain,2 but uptake of PA among adults with OA is very low.3 One reason for this is that while PA can reduce pain among adults with lower extremity OA,4,5 it does so differentially, decreasing pain sensitivity for about half of adults with OA but actually increasing pain sensitivity for the other half.6 Further, a recent meta-analysis revealed that engaging in a single type of PA (e.g. aerobic exercise or resistance training) reduces OA knee pain, but there was large heterogeneity in the results which could not be explained by age, sex, BMI, alignment in the knee, disease severity, or baseline pain.5 One of the goals of developing individualized PA interventions for adults with OA is to elucidate the mechanisms by which PA reduces OA pain and for whom PA most effectively diminishes the pain.

Aerobic physical activity, such as walking, increases cellular capacity for energy generation (ATP production) via oxidative phosphorylation up to 2-fold by stimulating mitochondrial biogenesis.7,8 This phenomenon occurs not only in skeletal muscle,7 but also in brain cells,9,10 liver cells,9,11,12 adipose tissue,13 kidney cells,12 and leukocytes14 indicating that PA likely increases metabolic demand systemically. Moreover, PA is thought to create adaptive changes in the activity and/or abundance of proteins involved in processes related to mitochondrial function.8 Mitochondrial function, including energy generation through oxidative phosphorylation; inflammation; and mitochondrial related protein expression are key features in osteoarthritis15,16 and chronic inflammatory pain.17,18 Animal models of inflammatory pain demonstrate a cellular metabolic shift from oxidative phosphorylation to glycolysis in chronic inflammatory states via the pyruvate dehydrogenase kinase 2/4 (PKD2/4)-pyruvate dehydrogenase (PDH)-lactic acid axis.19 This results in an increase in lactic acid production in the affected area. The ensuing acidic microenvironment amplifies the nociceptive response via recruitment of additional pro-algesic proinflammatory cytokines which "activate nociceptors and spinal glia to cause peripheral and central sensitizations, respectively".19 Thus, improvement in the capacity to generate ATP through oxidative phosphorylation, and associated reduction of glycolysis, may reduce pain sensitivity. However, while a large body of animal and correlational data supports a strong link between oxidative potential and pain outcomes, experimental evidence of cause and effect remains sparse, especially in humans.8

The investigators are hypothesizing that individual differences in systemic cellular bioenergetic function, inflammation, and protein expression influence the effect of PA to reduce pain sensitivity in adults with knee OA. The purpose of this quasi-experimental pilot study is to test mitochondrial bioenergetics (oxidative phosphorylation, mitochondrial content) in platelets, inflammation (cytokines) and protein expression as mechanisms for variation in pain sensitivity immediately after 30 minutes of walking (i.e. "acute") and after six weeks of walking three times a week for 30 minutes (i.e. "long-term") in adults with knee osteoarthritis. The investigators will address the following specific aims and hypotheses in a sample of 40 adults with radiologic evidence of hip or knee OA and 20 age/gender matched healthy controls:

Aim 1: To examine the effects of a six week (three days/week) walking program on pain thresholds in adults with knee OA as compared to healthy controls H1.1: Pain sensitivity (Quantitative Sensory Testing) will increase in approximately 50% of adults with OA and decrease in approximately 50% of adults with OA after acute and long-term PA.

H1.2: Pain sensitivity will decrease in healthy controls after acute and long-term PA.

Aim2: To test the role of mitochondrial bioenergetics (oxidative phosphorylation, mitochondrial content) as a mechanism for variation in pain sensitivity after PA in older adults with knee OA.

H2.1: Pain sensitivity is negatively associated with mitochondrial function (oxidative phosphorylation, mitochondrial content) in platelets at baseline, after acute PA and long-term PA H2.2: Healthy controls will have higher capacity for oxidative phosphorylation in platelets than OA participants.

Aim3: To test the role of inflammation as a mechanism for variation in pain sensitivity after physical activity in older adults with knee OA.

H3.1: Pain sensitivity is positively associated with increased circulating proinflammatory cytokines (c-reactive protein, interleukin (IL)-1, IL-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, PGES) at baseline, after acute and long-term PA.

Aim 4: To generate hypotheses regarding the role of proteomics in variation in pain sensitivity after physical activity (immediacy following and after six weeks of walking program) Changes in protein expression will depend on the half-life of the protein being expressed which can range from minutes to days.8 Thus, it is important to examine adaptive changes in protein expression in both the short (minutes/day post PA) and long term (days/weeks between bouts of physical activity).

• Study Type: Interventional
• Enrollment (Actual): 13
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Maryland
    • Baltimore, Maryland, United States, 21201
      • University of Maryland, Baltimore

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

Adults with Osteoarthritis:

• Age 50-80
• radiographic evidence of knee osteoarthritis (OA participants)
• self-report current non-smoker
• willing and able to walk for 30 minutes a day three days a week for six weeks at a location that is within 30 minutes from University of Maryland Baltimore
• speaks English

Healthy Controls:

• Age 50-80
• self-reports no osteoarthritis
• self-report current non-smoker
• willing and able to walk for 30 minutes a day three days a week for six weeks at a location that is within 30 minutes from University of Maryland Baltimore
• speaks English

Exclusion Criteria:

• unable to pass the evaluation to sign consent
• diagnosis of rheumatoid arthritis
• diagnosis of gout
• diagnosis of heart failure
• diagnosis of chronic obstructive pulmonary disease
• diagnosis of diabetes
• diagnosis of Parkinson's disease
• diagnosis of Alzheimer's disease
• diagnosis of autoimmune disease
• currently taking long-term steroid medications such as methotrexate
• weight less than 110 lbs.
• direct employee of the PI

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Adults with knee Osteoarthritis; walking 30 minutes per day, three days/week for 6 weeks.	Behavioral: Walking; walking 30 minutes per day, three days/week for 6 weeks with a member of study team.
Active Comparator: Healthy controls; walking 30 minutes per day, three days/week for 6 weeks.	Behavioral: Walking; walking 30 minutes per day, three days/week for 6 weeks with a member of study team.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain sensitivity	Change from baseline pain threshold/tolerance after 30 minutes of walking	Baseline and immediately after 30 minutes of walking
Pain sensitivity	Change from baseline pain threshold/tolerance after six weeks of walking for 30 minutes three days/week	Baseline and within 4 weeks after completing six weeks of walking for 30 minutes three days/week

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
platelet mitochondrial function	platelet oxygen consumption as indicator of cellular energy production via oxidative phosphorylation or glycolysis; mitochondrial copy number; mitochondrial proteins	immediately after 30 minutes of walking
platelet mitochondrial function	platelet oxygen consumption as indicator of cellular energy production via oxidative phosphorylation or glycolysis; mitochondrial copy number; mitochondrial proteins	after six weeks of walking for 30 minutes
Inflammatory markers in plasma	c-reactive protein (CRP), Interleukin (IL)-1, IL-1β, IL-6, IL-10, Tumor Necrosis factor-alpha (TNF-α), prostaglandin-e (PGES)	immediately after 30 minutes of walking
Inflammatory markers in plasma	c-reactive protein (CRP), Interleukin (IL)-1, IL-1β, IL-6, IL-10, Tumor Necrosis factor-alpha (TNF-α), prostaglandin-e (PGES)	after six weeks of walking for 30 minutes
Platelet protein signatures	Platelet protein signatures will be explored using nanocapillary liquid chromatography-mass spectrometry (LC-MS/MS) coupled to an Orbitrap MS that combines two mass analyzers to allow simultaneous precursor ion scans from which relative quantitative data is derived between two groups (hi and low pain groups) and fragmentation data from which peptide sequence matches are made.	immediately after 30 minutes of walking
Platelet protein signatures	Platelet protein signatures will be explored using nanocapillary liquid chromatography-mass spectrometry (LC-MS/MS) coupled to an Orbitrap MS that combines two mass analyzers to allow simultaneous precursor ion scans from which relative quantitative data is derived between two groups (hi and low pain groups) and fragmentation data from which peptide sequence matches are made.	after six weeks of walking for 30 minutes

Collaborators and Investigators

• Sponsor: University of Maryland, Baltimore
• Collaborators: National Institute of Nursing Research (NINR)
• Investigators: Principal Investigator: Jennifer Klinedinst, PhD, University of Maryland, Baltimore

Publications and helpful links

General Publications

• Klinedinst NJ, Huang W, Nelson AK, Resnick B, Renn C, Kane MA, Dorsey SG. Inflammatory and Immune Protein Pathways Possible Mechanisms for Pain Following Walking in Knee Osteoarthritis. Nurs Res. 2022 Jul-Aug 01;71(4):328-335. doi: 10.1097/NNR.0000000000000593. Epub 2022 Mar 18.

Study record dates

Study Major Dates

• Study Start (Actual): May 7, 2018
• Primary Completion (Actual): August 24, 2022
• Study Completion (Actual): August 24, 2022

Study Registration Dates

• First Submitted: November 8, 2017
• First Submitted That Met QC Criteria: November 13, 2017
• First Posted (Actual): November 17, 2017

Study Record Updates

• Last Update Posted (Actual): September 7, 2022
• Last Update Submitted That Met QC Criteria: September 6, 2022
• Last Verified: September 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Joint Diseases; Musculoskeletal Diseases; Rheumatic Diseases; Arthritis; Osteoarthritis; Osteoarthritis, Knee
• Other Study ID Numbers: HP-00076861; 1P30NR016579-01 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: This is a pilot study with a very small sample size.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No