Spinal Manipulative Therapy Reduces Inflammatory Cytokines but Not Substance P Production in Normal Subjects
Received 12 July 2005; received in revised form 20 September 2005
Objective
To examine the effect of a single spinal manipulation therapy (SMT) on the in vitro production of inflammatory cytokines, tumor necrosis factor α, and interleukin (IL) 1β, in relation to the systemic (in vivo) levels of neurotransmitter substance P (SP).
Methods
Sixty-four asymptomatic subjects were assigned to SMT, sham manipulation, or venipuncture control group. SMT subjects received a single adjustment in the thoracic spine. Blood and serum samples were obtained from subjects before and then at 20 minutes and 2 hours after intervention. Whole-blood cultures were activated with lipopolysaccharide (LPS) for 24 hours. Cytokine production in culture supernatants and serum SP levels were assessed by specific immunoassays.
Results
Over the study period, a significant proportion (P ≤ .05) of sham and control subjects demonstrated progressive increases in the synthesis of tumor necrosis factor α and IL-1β. Conversely, in a comparable proportion of cultures from SMT-derived subjects, the production of both cytokines decreased gradually. Normalization of the observed alterations to reflect the changes relative to self-baselines demonstrated that, within 2 hours after intervention, the production of both cytokines increased significantly (P < .001 to .05) in both controls. In contrast, a significant (P < .001 to .05) reduction of proinflammatory cytokine secretion was observed in cultures from SMT-receiving subjects. In all study groups, serum levels of SP remained unaltered within 2 hours after intervention.
Conclusions
SMT-treated subjects show a time-dependent attenuation of LPS-induced production of the inflammatory cytokines unrelated to systemic levels of SP. This suggests SMT-related down-regulation of inflammatory-type responses via a central yet unknown mechanism.
aAssociate Professor, Division of Research, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada
bProfessor and Chair, Department of Pathology and Microbiology, Canadian Chiropractic College, Toronto, Ontario, Canada
cAssistant Professor and Associate Dean of Clinics, Canadian Chiropractic College, Toronto, Ontario, Canada
Submit requests for reprints to: H. Stephen Injeyan, PhD, DC, Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, Ontario, Canada M2H 3J1.
Sources of support: This study was supported by the Canadian Memorial Chiropractic College and a Public Health Service grant no. U24 AR45166 through the Consortial Center for Chiropractic Research. The contents of this article are solely the responsibility of the authors.
ABSTRACT