Inflammation: Friend or Foe? Benjamin Reich, DPT Marshfield Clinic Outline 1. Why this topic? 2. Muscle regeneration 3. Inflammatory Process 4. Impact of NSAIDs 5. Impact of Ice, heat, ultrasound 2 Why? 1
4 Why?? 5 Why? High number of PT s directly recommend NSAIDs 1 Studies suggest knowledge is inadequate <1/2 of PT s believed that NSAIDs should be withheld during first few days after injury Inflammation has BENEFICIAL effects Lack of knowledge regarding the effect of inflammation on tissue healing Regenerative Medicine is growing Regenerative Rehabilitation??? 6 2
Muscle Regeneration Myofibers are Postmitotic Muscle cells themselves can not divide Satellite cells (adult muscle stem cells) are responsible for regeneration No satellite cells, no regeneration Can get increase in muscle fiber size (hypertrophy) without satellite cells 7 Muscle Regeneration After injury, satellite cells are activated and become myoblasts Extensive proliferation during first few days of injury At 3 to 7 days, proliferation stops and myoblasts differentiate and fuse to the myofibers then form myotubes After day 7, myotubes grow to form new mature myofibers 8 9 3
Muscle Regeneration The inflammatory process plays a KEY role in satellite cell function 10 11 Damage to blood vessels and tissue starts the inflammatory process Mast cells are released STIMULATE proliferation of SATELLITE cells Inflammatory cells coordinate muscle healing Inflammatory Process Early inflammatory mediators stimulate vasodilation and increase vascular permeability Allows for infiltration of inflammatory cells in to the tissue 12 4
Inflammatory Process Neutrophils show up first (first 72 hours) Break down cell debris to clean the injured zone Can induce secondary damage to the in tact living tissue Depends on severity of injury Release cytokines Stimulates inflammatory cell recruitment Stimulates myoblasts M1 Macrophages also appear during the first 72 hours Break down muscle cell debris Release pro-inflammatory factors Stimulates inflammatory cell recruitment Stimulates myoblasts 13 Inflammatory Process ~48 hours after muscle injury, macrophages change from M1 phenotype to M2 phenotype Release anti-inflammatory molecules and growth factors Stops myoblast proliferation Stimulates myoblast differentiation, fusion, and myofiber growth This change is essential in muscle regeneration as well as resolving inflammation Depleting macrophages during acute injury phase leads to defective muscle healing, persistent necrotic tissue, and increased fat accumulation (mice) 14 Inflammatory Process Pro-inflammatory lipid mediators start to become replaced by anti-inflammatory mediators Also essential to muscle regeneration and resolution of inflammation COX-2 essential to this process It promotes inflammation in the early stages and helps with the resolution in later stages COX-2 is blocked by NSAIDs 15 5
Impact of NSAIDs Acute Inhibition of COX-2 in mice has shown: Diminished proliferation, differentiation, and fusion of satellite cells Impaired skeletal muscle growth, delayed skeletal muscle repair, and increased fibrosis 16 Impact of NSAIDS Acute inhibition of COX-2 in humans has shown: No significant improvement in outcomes when NSAIDs added to physical therapy treatment following acute hamstring injury at days 1, 3, and 7 (meclofenamate and diclofenac) VAS rating, thigh circumference (swelling), isokinetic muscle performance testing Placebo group had significantly less pain at day 7 in more severe injuries 17 Impact of NSAIDS Acute inhibition of COX-2 in humans has shown: Suppression of satellite cells in the vastus lateralis following eccentric exercise after 8 days (Indomethacin) 200 maximal eccentric contractions in to an isokinetic dynamometer No significant difference in MVC No difference in muscle soreness Pressure with a probe Increase in inflammatory cells at day 8 in the indomethacin leg Not statistically significant (p = 0.9) 18 6
Impact of NSAIDS Acute inhibition of COX-2 in humans has shown: Suppression of satellite cells in the vastus lateralis following a 36 km run induced injury at day 8 (Indomethacin) Increase in satellite cells in placebo group No increase in NSAID group 19 Impact of NSAIDS Immobilization of a limb for 2 weeks in elderly patients followed by 6 weeks of retraining showed: NSAID consumption did not affect muscle mass and strength (Ibuprofen 1200 mg) Did not significantly affect circulating levels of inflammatory markers 20 What about ice??? Exercise stimulates intramuscular inflammation and increases satellite cell activity 2 Increased amount of neutrophils, macrophages, and increased gene expression of cytokines and neurotrophins Response was no different between cold water immersion or active recovery groups Cryotherapy does not substantially alter local or systemic inflammatory responses to exercise induced muscle damage Many studies that demonstrate decrease in inflammation were performed in mice (muscles are more superficial) 21 7
What about ice??? Muscle mass increases significantly following training in both active recovery and cold water immersion 3 Significantly less of an increase in cold water vs. active recovery Leg press strength, knee extension strength, and maximal isometric torque gains were significantly higher in active recovery group Significant gain in satellite cell count after exercise in active recovery group only 22 What about Heat??? One time application of 42⁰C hot pack 5 minutes after crush injury to extensor digitorum in mice for 20 minutes: Facilitated migration of macrophages 4 Facilitated proliferation and differentiation of satellite cells Muscle cross sectional area larger at 14 and 28 days in the heat group vs. non heat group 23 What about Heat??? Heating of myoblasts in vitro showed 6 : Significant upregulation of myofibrillogenesis genes Increased differentiation of myoblasts Heating the lower extremities in humans has shown 7 : Promotion of key angiogenic mediators in skeletal muscle 24 8
What about Ultrasound? Low intensity pulsed ultrasound following muscle injury in mice was found to (daily 3 minute sessions, 1 Mhz, 0.4 W/cm 2, 1:5 pulsed mode, for 7 days): 5 Decrease number of neutrophils and macrophages within first day Decrease total macrophages and M1 macrophages after 2 days Increase number of M2 macrophages after 2 days Helps to resolve inflammatory process? Decrease total number of macrophages after days 3-7 Don t know how this affected muscle regeneration 25 What should we do???? 27 9
Questions????? References 1) Duchesne E, Dufresne SS, Dumont NA. Impact of inflammation and Anti-inflammatory Modalities on Skeletal Muscle Healing: From Fundamental Research to the Clinic. Phys Ther. 2017;97:807-817. 2) Peake JM, Roberts LA, Figueiredo VC, Egner I, Krog S, Aas SN, Suzuki K, Markworth JF, Coombes JS, Cameron-Smith D, Raastad T. The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise. J Physiol. 2017 Feb 1;595(3):695-711. 3) Roberts LA, Raastad T, Markworth JF, Figueiredo VC, Egner IM, Shield A, Cameron-Smith D, Coombes JS, Peake JM. Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. J Physiol. 2015 Sep 15;593(18):4285-301. 4) Gao CQ, Zhao YL, Li HC, Sui WG, Yan HC, Wang XQ. Heat Stress promotes skeletal muscle regeneration after crush injury in rats. Acta Histochemica. 2014:327-334. 5) da Silva Junior EM, Mesquita-Ferrari RA, França CM, Andreo L, Bussadori SK, Fernandes KPS. Modulating effect of low intensity pulsed ultrasound on the phenotype of inflammatory cells. Biomed Pharmacother. 2017 Dec;96:1147-1153 6) Guo Q, Miller D, An H, Wang H, Lopez J, Lough D, et al. (2016) Controlled Heat Stress Promotes Myofibrillogenesis during Myogenesis. PLoS ONE 11(11): e0166294. doi:10.1371/journal.pone.0166294 7) Alisha M. Kuhlenhoelter, Kyoungrae Kim, Dustin Neff, Yaohui Nie, A. Nicole Blaize, Brett J. Wong, Shihuan Kuang, Julianne Stout, Qifan Song, Timothy P. Gavin, Bruno T. Roseguini. Am J Physiol Regul Integr Comp Physiol. 2016 Aug 1; 311(2): R377 R391 29 10