The Mechanisms Of Skeletal Muscle Inflammation In Mitochondrial Homeostasis Delay In Movement

Objective: Inflammation is closely related to many diseases, the aging process occursalong with the phenomenon of elevated inflammatory cytokines, accompanied bymuscular atrophy and reduced mitochondrial biogenesis. Inflammation has beenconfirmed as a factor that can lead to skeletal muscle function deterioration, andanti-inflammatory factor treatment can slow down the process of skeletal muscledeterioration. Over-expression of IL-6can speed up the process of sarcopenia, theevidence that skeletal muscle cell incubation directly with IL-6, suggests thatmitochondria fusion protein expression of Mfn2is reduced. However, the effect ofIL-6in the process of skeletal muscle function and the regulating mechanism ofmitochondrial homeostasis and biosynthesis are not clear. Exercise can be used asprevention and treatment of diseases associated with skeletal muscle function. Thestudy found that moderate intensity exercise can reverse muscle mass reducing causedby IL-6over-expression. The study built the model of C57mice caused byinflammation, explore the process that skeletal muscular atrophy caused byinflammation, the effect of IL-6and mitochondrial homeostasis in skeletal muscularatrophy in mice and then intervention with moderate endurance exercise, to explorethe effect of exercise on skeletal muscle function deterioration and possible regulatorymechanism.Method:1, the establishment of animal models: after feeding adaptation and adaptivetraining,8-month-old male C57mice were randomly divided into a quiet group andthe exercise group. Exercise group for4weeks of moderate intensity12m/min (76%VO2max) treadmill training for30minutes a day. After four weeks the quiet groupand the exercise group were randomly divided into two groups and injected with IL-6or normal saline. Eventually divided into four experimental groups:①quiet salinecontrol group (R, N=10);②movement saline control group (E,N=10);③quiet IL-6injection group (RI,N=10):0.3pg/kgIL-6continuous injection four weeks;④ movement IL-6injection group (EI,N=10):0.3pg/kgIL-6continuous injection fourweeks.2,removal of the eye by way of blood serum IL-6and TNF-α levels by ELISA.3, after the extraction of quantitative skeletal muscle mitochondria, mitochondrialstate with Oxygraph-2k cellular respiration meter (Oroboros, Austria)3respiration(State3), state4respiration (State4) and calculate the respiratory control ratio(RCR);fluorescence spectroscopic photometer JC-1labeled mitochondrial membranepotential and DCFH-DA method for the determination of mitochondrial H2O2production rate;Western-blotting assay COXIV, PGC-1α, IL-6, NFκB, TNF-α andmitochondrial biogenesis associated protein content.Results:(1) model: ELISA measurement of serum levels of inflammatory cytokinesTNF-α:quiet IL-6TNF-α levels in serum by ELISA injected mice was significantlyhigher than the quiet control group (p<0.05).Sports and exercise control groupinjected IL-6group quieter injection group TNF-α were significantly lower(p<0.01).(2)movement and IL-6injection in animal models,IL-6injection group quietquadriceps wet weight/body weight (mg/g) ratio was significantly lower than the quietcontrol group (p<0.05);movement of saline non-significant (p>0.05) between thecontrol group and the movement of IL-6injection group.(3) mouse skeletal musclemitochondrial respiratory function: moderate-intensity exercise training can improvemitochondrial respiratory function, exercise IL-6injected mice with IL-6quietmitochondrial respiratory control mice injected ratio (RCR) showed significantdifferences (p<0.05).It can significantly affect the movement state3respiration,movement IL-6group of animals injected state3respiration was significantly higherthan IL-6injection quiet animals (p<0.05).Sports saline control group than in thesaline control configuration quiet3respiration was significantly higher (p<0.01), butthe state4and no significant changes.(4)ROS generation rate in each group: ROSgeneration rate control group of mice was significantly lower than the saline controlgroup of mice quiet (p<0.05), and sports and IL-6injected mice could significantlyaffect the mitochondria ROS generation rate. Compared with IL-6injection groupquiet motion ROS IL-6injection group was significantly lower than that of IL-6injection group quiet (p<0.01).(5)The results of each group of mitochondrial membrane potential: Sports saline control group of mice mitochondrial membranepotential was significantly higher than the saline control group of mice quiet (p<0.05),IL-6Quiet injection group was significantly lower than the quiet membrane potentialphysiological saline control group (p<0.05).(6)Analysis of Protein Expression:PGC-1α:receiving IL-6in mice injected,PGC-1α protein was significantly lower thanthe other groups, skeletal muscle mitochondria of IL-6protein injected micesignificantly PGC-1α quiet higher IL-6injection group (p<0.05); while mice receivingsaline injections, exercise control group was significantly higher than the controlgroup quiet (p<0.05). COXIV: Motion control group of mice was significantly higherthan the mitochondrial protein COXIV quiet saline control group (p<0.05); movementIL-6injected mice mitochondrial COXIV protein was significantly higher than thequiet IL-6injection group (p<0.05); IL-6: tranquil control group mouse mitochondrialprotein IL-6were significantly higher than control group exercise (p<0.05), IL-6quietmitochondrial mice injected IL-6protein was significantly higher than the controlgroup and quiet movement IL-6injection group (p<0.05, p<0.01); NFκB: quiet IL-6protein injected mice were significantly higher than the mitochondrial NFκB quietsaline control group (p<0.05) sports injected mice IL-6protein in skeletal musclemitochondria NFκB significantly lower IL-6quiet injected mice (p<0.05); TNF-α:quiet IL-6in skeletal muscle of mice injected TNF-α protein ratio under the sameconditions a quiet saline control group were significantly increased (p<0.01), IL-6under the sports group of mice injected with the same conditions as quiet IL-6injection group was significantly decreased compared (p<0.05), exercise physiologyunder the saline control group of mice with the same condition quiet compared to thesaline control group was significantly lower (p<0.05).Conclusions:1.Exogenous inflammatory cytokines IL-6can cause elevated levels of ROS inskeletal muscle, while reducing skeletal muscle mitochondrial respiratory functionand mitochondrial biogenesis related protein expression of PGC-1α and COXIV,impact the skeletal muscle mitochondrial energy metabolism and mitochondrialbiogenesis. 2.Exogenous IL-6inflammatory cytokines can cause elevated levels of TNF-α inskeletal muscle, skeletal muscle inflammation induced skeletal muscle deterioration,that may be associated with muscular atrophy.3.Endurance exercise training increases PGC-1α expression, regulate mitochondrialbiogenesis and mitochondrial function.At the same time,it can also inhibit theexpression of inflammatory transcription factor NFκB, regulate anti-inflammatory andpro-inflammatory cytokines homeostasis and delay the occurrence of skeletal muscleinflammation.