Decrease of IL-1β and TNF in the Spinal Cord Mediates Analgesia Produced by Ankle Joint Mobilization in Complete Freund Adjuvant-Induced Inflammation Mice Model

Abstract

ObjectiveThis study aims to investigate the effects of ankle joint mobilization (AJM) on mechanical hyperalgesia and peripheral and central inflammatory biomarkers after intraplantar (i.pl.) Complete Freund’s Adjuvant (CFA)-induced inflammation.MethodsMale Swiss mice were randomly assigned to 3 groups (n = 7): Saline/Sham, CFA/Sham, and CFA/AJM. Five AJM sessions were carried out at 6, 24, 48, 72, and 96 h after CFA injection. von Frey test was used to assess mechanical hyperalgesia. Tissues from paw skin, paw muscle and spinal cord were collected to measure pro-inflammatory (TNF, IL-1β) and anti-inflammatory cytokines (IL-4, IL-10, and TGF-β1) by ELISA. The macrophage phenotype at the inflammation site was evaluated by Western blotting assay using the Nitric Oxide Synthase 2 (NOS 2) and Arginase-1 immunocontent to identify M1 and M2 macrophages, respectively.ResultsOur results confirm a consistent analgesic effect of AJM following the second treatment session. AJM did not change cytokines levels at the inflammatory site, although it promoted a reduction in M2 macrophages. Also, there was a reduction in the levels of pro-inflammatory cytokines IL-1β and TNF in the spinal cord.ConclusionTaken together, the results confirm the anti-hyperalgesic effect of AJM and suggest a central neuroimmunomodulatory effect in a model of persistent inflammation targeting the pro-inflammatory cytokines IL-1β and TNF.

Myeloid Vamp3 deletion attenuates CFA-induced inflammation and pain in mice via ameliorating macrophage infiltration and inflammatory cytokine production

“…A recent study by Omura et al. demonstrated an escalation in M1 macrophage density after intraplantar injection of CFA, while M2 density remained unchanged at the site of inflammation ( 23 ). Our immunohistochemical staining experiments provided clear evidence that the knockout of Vamp3 in myeloid cells resulted in a substantial reduction in local macrophage accumulation in the plantar skin following CFA injection.…”

“…The levels of proinflammatory cytokines TNF-α and IL-6 in the CFA-injected paws were measured following previously described protocols ( 23 ), with minor modifications. Briefly, the injected paws (including skin and underlying muscle) at day 1 and day 14 post CFA administration were dissected and homogenized on ice in radioimmunoprecipitation assay (RIPA) lysis and extraction buffer (Thermo Fisher Scientific, Shanghai, China, catalog number 89900) containing a protease inhibitor cocktail set III (1:100 v/v; Merck, catalog number 539134) and 1 mM phenylmethylsulfonyl fluoride (Merck, catalog number P7626) before centrifugation at 13,000 rpm for 10 min at 4°C.…”

“…However, the impact of Vamp3 deficiency on inflammation and pain remains elusive. Complete Freund’s adjuvant (CFA) has been employed in various animal models to elicit inflammation and investigate inflammatory pain ( 23 , 24 ). Given the prominent role of monocyte/macrophage lineage cells, we hypothesized that Vamp3 deficiency in myeloid cells would attenuate the severity of CFA-induced inflammation.…”

Macrophages and glial cells: Innate immune drivers of inflammatory arthritic pain perception from peripheral joints to the central nervous system

“…Additionally, analgesic effects with articular joint movement (AJM) treatment have been reported in a model of persistent inflammation. AJM did not altered cytokine levels at the inflammatory site, but centrally, AJM reduced the levels of pro-inflammatory cytokines IL-1β and TNF in the spinal cord, which suggests a central neuro-immunomodulatory effect ( 254 ). This data corroborates other pre-clinical studies showing that non-pharmacological interventions such as environmental enrichment (EE) can modulate the nociceptive and inflammatory responses in arthritis models.…”

Effects of Orthopedic Manual Therapy on Pain Sensitization in Patients With Chronic Musculoskeletal Pain

“…Among the approaches to desensitize central nervous system, healthcare professionals may use orthopedic manual therapy (OMT) techniques on patients with CMSKP, with the recommendation of its use in the clinical guidelines. 19 Although OMT mechanisms are not fully understood, a mechanical stimulus initiates a cascade of peripheral and central neurophysiological effects, 20 decreasing proinflammatory mediators, 21 decreasing mechanical hyperalgesia, 22,23 and activating supraspinal inhibitory pathways to produce a hypoalgesic and antinociceptive response. 24,25 Published systematic reviews (SRs) have demonstrated that OMT improves pain sensitivity and reduces central sensitization in patients with CMSKP, 5,26,27 although its effects are only limited to the immediate (after intervention) or short-term (from hours to days).…”