Cytokine and neuropeptide levels are associated with pain relief in patients with chronically painful total knee arthroplasty: A pilot study

Jasvinder A. Singh, Siamak Noorbaloochi, Keith L. Knutson

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Background: There are few studies with an assessment of the levels of cytokines or neuropeptides as correlates of pain and pain relief in patients with painful joint diseases. Our objective was to assess whether improvements from baseline to 2-months in serum cytokine, chemokine and substance P levels were associated with clinically meaningful pain relief at 2-months post-injection in patients with painful total knee arthroplasty (TKA). Methods: Using data from randomized trial of 60 TKAs, we assessed the association of change in cytokine/chemokine/Substance P levels with primary study outcome, clinically important improvement in Western Ontario McMaster Osteoarthritis Index (WOMAC) pain subscale at 2-months post-injection using Student's t-tests and Spearman's correlation coefficient (non-parametric). Patients were categorized as pain responders (20-point reduction or more on 0-100 WOMAC pain) vs. pain non-responders. Sensitivity analysis used 0-10 daytime pain numeric rating scale (NRS) instead of WOMAC pain subscale. Results: In a pilot study, compared to non-responders (n = 23) on WOMAC pain scale at 2-months, pain responders (n = 12) had significantly greater increase in serum levels of IL-7, IL-10, IL-12, eotaxin, interferon gamma and TNF-α from baseline to 2-months post-injection (p < 0.05 for all). Change in several cytokine/chemokine and substance P levels from pre-injection to 2-month follow-up correlated significantly with change in WOMAC pain with correlation coefficients ranging -0.37 to -0.51: IL-2, IL-7, IL-8, IL-9, IL-16, IL-12p, GCSF, IFN gamma, IP-10, MCP, MIP1b, TNF-α and VEGF (n = 35). Sensitivity analysis showed that substance P decreased significantly more from baseline to 2-months in the pain responders (0.54 ± 0.53; n = 10) than in the pain non-responders (0.48 ± 1.18; n = 9; p = 0.023) and that this change in serum substance P correlated significantly with change in daytime NRS pain, correlation coefficient was 0.53 (p = 0.021; n = 19). Findings should be interpreted with caution, since cytokine analyses were performed for a sub-group of the entire trial population. Conclusion: Serum cytokine, chemokine and Substance P levels correlated with pain response in patients with painful TKA after an intra-articular injection in a randomized trial.

Original languageEnglish (US)
Article number17
JournalBMC Musculoskeletal Disorders
Issue number1
StatePublished - Jan 14 2017

Bibliographical note

Funding Information:
This study was supported by the resources and use of facilities at Birmingham and Minneapolis Veterans Affairs medical centers and the NIH CTSA award 1 KL2 RR024151-01 (Mayo Clinic Center for Clinical and Translational Research). JAS is supported by the resources and the use of facilities at the VA Medical Center at Birmingham, Alabama, USA.

Funding Information:
JAS has received research grants from Takeda and Savient and consultant fees from Savient, Takeda, Regeneron, Merz, Bioiberica, Crealta and Allergan pharmaceuticals, WebMD, UBM LLC and the American College of Rheumatology. JAS serves as the principal investigator for an investigator-initiated study funded by Horizon pharmaceuticals through a grant to DINORA, Inc., a 501 (c)(3) entity. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies; a member of the American College of Rheumatology’s (ACR) Annual Meeting Planning Committee (AMPC); Chair of the ACR Meet-the-Professor, Workshop and Study Group Subcommittee; and a member of the Veterans Affairs Rheumatology Field Advisory Committee. Other authors have no relevant disclosures. None of the authors have any non-financial disclosures.

Publisher Copyright:
© 2017 The Author(s).


  • Cytokine
  • Pain
  • Primary total knee arthroplasty
  • Substance P
  • TKA


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