Effects of a hydroxyl radical scavenger, EPC-K1, and neutrophil depletion on reperfusion injury in rat skeletal muscle

Efficacy of non-surgical interventions for promoting improved functional outcomes following acute compartment syndrome: A systematic review

BACKGROUND

Acute compartment syndrome (ACS) is a devastating complication which develops following a traumatic extremity injury that results in increased pressure within osteofascial compartments, thereby leading to ischemia, muscle and nerve necrosis, and creates a life-threatening condition if left untreated. Fasciotomy is the only available standard surgical intervention for ACS. Following fasciotomy the affected extremity is plagued by prolonged impairments in function. As such, an unmet clinical need exists for adjunct, non-surgical therapies which can facilitate accelerated functional recovery following ACS. Thus, the purpose of this systematic review was to examine the state of the literature for non-surgical interventions that aim to improve muscle contractile functional recovery of the affected limb following ACS.

METHODS

English language manuscripts which evaluated non-surgical interventions for ACS, namely those which evaluated the function of the affected extremity, were identified as per PRISMA protocols via searches within three databases from inception to February 2022. Qualitative narrative data synthesis was performed including: study characteristics, type of interventions, quality, and outcomes. Risk of bias (RoB) was assessed using the Systematic Review Centre for Laboratory Animal Experimentation's (SYRCLE) RoB tool and reported level of evidence for each article.

RESULTS

Upon review of all initially identified reports, 29 studies were found to be eligible and included. 23 distinct non-surgical interventions were found to facilitate improved muscle contractile function following ACS. Out of 29 studies, 15 studies which evaluated chemical and biological interventions, showed large effect sizes for muscle function improvement.

CONCLUSIONS

This systematic review demonstrated that the majority of identified non-surgical interventions facilitated an improvement in muscle contractile function following pathological conditions of ACS.

Dexamethasone promotes long-term functional recovery of neuromuscular junction in a murine model of tourniquet-induced ischaemia-reperfusion

AIM

Tourniquet-induced ischaemia and subsequent reperfusion cause serious ischaemia-reperfusion (IR) injury in the neuromuscular junction (NMJ) and skeletal muscle. Here, we investigated whether dexamethasone (Dex) promotes long-term functional recovery of the NMJ and skeletal muscle in tourniquet-induced hindlimb IR.

METHODS

Unilateral hindlimb of C57/BL6 mice was subjected to 3 h of ischaemia following 6 weeks of reperfusion (6-wk IR). Dex treatment began on the day of IR induction and lasted for different periods. Sciatic nerve-stimulated gastrocnemius muscle contraction was detected in situ. Function of the NMJ was measured in situ using electrophysiological recording of the miniature endplate potential (mEPP) and endplate potential (EPP). Western blot was used to detect protein expression of nicotinic acetylcholine receptors (nAChRs) in gastrocnemius muscles.

RESULTS

Gastrocnemius muscle contraction in mice with 6-wk IR was about 60% of normal skeletal muscle contraction recorded in age-matched sham mice. The amplitude of the mEPP and EPP was lower in mice with 6-wk IR, compared to sham mice. Dex treatment for 1 or 3 days did not restore the function of the NMJ and improve gastrocnemius muscle contraction in mice with 6-wk IR. Dex treatment for 1 week exerted a maximum effect on improving the function of the NMJ and skeletal muscle, with the effect of Dex gradually lessening with prolonged Dex treatment. There are no significant differences in protein expression of nAChR-α1 and nAChR-β1 subunits in the gastrocnemius muscle among all groups.

CONCLUSION

Dex promotes repair of the NMJ and subsequently restores skeletal muscle contractile function in tourniquet-induced 6-wk IR.

Antioxidants attenuate oxidative damage in rat skeletal muscle during mild ischaemia

We have previously shown oxidative stress and oedema, caused by both xanthine oxidase-derived oxidants and infiltrating neutrophils, within skeletal muscle after contractile-induced claudication. The purpose of this study was to determine whether supplementation with antioxidant vitamins attenuates the oxidative stress, neutrophil infiltration and oedema associated with an acute bout of contractile-induced claudication. Rats received vehicle, vitamin C, vitamin E or vitamin C + E for 5 days prior to contractile-induced claudication. Force production was significantly reduced in the claudicant limbs of all groups compared with the control (sham) limb of control animals. Contractile-induced claudication caused a significant increase in protein oxidation, lipid peroxidation, neutrophil infiltration and oedema compared with sham muscles. Supplementation with vitamin C, E or C + E prevented the increases in each of these, and there were no differences between groups. These findings suggest that, in an animal model of exercise-induced claudication, neutrophil chemotaxis is caused by oxidizing species and that antioxidant supplementation can prevent oxidative damage, neutrophil infiltration and oedema following an acute bout of contractile-induced claudication.

Ascorbic acid (vitamin C) and iloprost attenuate the lung injury caused by ischemia/reperfusion of the lower extremities of rats

The objectives of this study were to compare the protective effects of ascorbic acid and iloprost on lung injury caused by ischemia reperfusion (I/R) of the lower extremities of rats. Wistar albino rats (n = 34) were divided into five groups. In the I/R group (n = 6), the aorta was cross-clamped for 3 hr, followed by 1 hr of reperfusion. In the vitamin C group (n = 8), animals were pretreated with 100 mg/kg ascorbic acid via the left jugular vein before aortic cross-clamping. In the iloprost group (n = 8), animals were pretreated with 20 ng/(kg x min) iloprost by constant intravenous infusion via the left jugular venous cannula. In the sham group (n = 6), the abdomen was left open at the same period and a juguler venous line was established. In the control group (n = 6), lungs were removed and blood samples taken immediately after sternotomy. No treatment was given in this group. After both lungs were removed, biochemical parameters were measured and histopathological evaluation was made. Although the arterial blood pO2 and HCO3 levels were statistically significantly high in both the vitamin C and iloprost groups compared to the I/R group, plasma malondialdehyde (MDA) levels were significantly low. Meanwhile, the MDA levels in the lung tissue were significantly low in the vitamin C group compared to the I/R group. The MDA level in the lung tissue in the iloprost group was also low compared to the I/R group, but it was not statistically significant. The lungs of the I/R group displayed intense interstitial leukocytic infiltration in histopathological examination compared to the other groups. Pretreatment of animals with iloprost and vitamin C significantly decreased the pulmonary injury characterized by decreased plasma leukocyte sequestration. The results suggest that both vitamin C and iloprost are useful agents for attenuating the lung injury caused by increased oxidative stress and neutrophil accumulation after a period of I/R of the lower extremities.

Effect of anti-inflammatory and antioxidant drugs on the long-term repair of severely injured mouse skeletal muscle

Non-steroidal anti-inflammatory drugs are frequently prescribed after skeletal muscle injury. It is not known whether this type of medication can interfere with muscle repair, although inflammatory response is thought to play an important role in this process. Tibialis anterior muscles of mice were injured by myotoxic agent (snake venom) or crushed. Then, animals were treated daily for 10-14 days with different types of non-steroidal anti-inflammatory and antioxidant drugs. The long-term repair was studied 10-42 days after injury by analysing the recovery of in situ muscle force production, size of regenerating muscle cells and expression of myosin heavy chain. Our results show that diclofenac, diferuloylmethane (curcumin), dimethylthiourea or pyrrolidine dithiocarbamate treatment did not significantly affect muscle recovery after myotoxic injury (P > 0.05). Similarly, diferuloylmethane, dimethyl sulphoxide or indomethacin administration did not markedly change muscle repair after crush injury. However, we noted that high doses (> 2 mg kg(-1)) of diferuloylmethane or indomethacin increased lethality and reduced muscle repair after crush injury. In conclusion, non-steroidal anti-inflammatory and antioxidant drugs did not exhibit long-term detrimental effects on muscle recovery after injury, except at lethal doses.

Aprotinin ameliorates ischemia/reperfusion injury in a rat hind limb model

The aim of the study was to investigate the protective effect of aprotinin in a rat hind limb ischemia/reperfusion (I/R) model. A well-known antioxidant, alpha-tocopherol, was also tested for comparison. Ischemia was induced for 4 h by vascular clamping of the iliac arteries of 24 Sprague-Dawley rats, followed by 1 h of reperfusion. Muscle injury was evaluated in three groups: a saline group, an alpha-tocopherol group and an aprotinin group. Blood pH, pO2, pCO2, HCO3, creatine kinase (CPK), lactate dehyrogenase (LDH) and thiobarbituric acid reactive substances (TBARS) as well as muscle TBARS were measured at the end of the reperfusion. Muscle tissue samples were taken for histological examination. alpha-Tocopherol and aprotinin groups showed a significant amelioration of plasma CPK (p=0.002, p=0.002), LDH (p=0.004, p=0.004) and muscle tissue TBARS (p=0.001, p=0.001) compared with the control. Plasma TBARS were significantly lower in the aprotinin group compared with the control (p=0.017). Also, tissue TBARS was significantly lower in the aprotinin group than the alpha-tocopherol group (p<0.001). Neutrophil infiltration was less prominent in the alpha-tocopherol and aprotinin groups compared to the control (p=0.006, p=0.001). These results suggest that aprotinin, a potent anti-inflammatory drug, is more useful than alpha-tocopherol, a powerful antioxidant, for attenuating muscle injury after I/R.

Reperfusion injury in skeletal muscle is reduced in inducible nitric oxide synthase knockout mice

Inducible nitric oxide synthase (iNOS) participates in many pathological events, and selective inhibition of iNOS has been shown to reduce ischemia-reperfusion (I/R) injury in different tissues. To further confirm its role in this injury process, I/R injury was observed in denervated cremaster muscles of iNOS-deficient (iNOS−/−) and wild-type mice. After 3-h ischemia and 90-min reperfusion, blood flow in reperfused muscle was 80 ± 8.5% (mean ± SE) of baseline at 10-min reperfusion and completely returned to the preischemia baseline after 20 min in iNOS−/− mice. In contrast, blood flow was 32 ± 7.4% at 10 min and increased to 60 ± 20% of the baseline level at 90 min in wild-type mice ( P < 0.001 vs. iNOS−/− mice at all time points). The increased muscle blood flow in iNOS−/− mice was associated with significantly less vasospasm in all three sizes of arterial vessel size categories. The weight ratio to the contralateral muscle not subjected to I/R was greater in wild-type mice (173 ± 11%) than in iNOS−/− mice (117 ± 3%; P < 0.01). Inflammation and neutrophil extravasation were also more severe in wild-type mice. Western blot analysis demonstrated an absence of iNOS protein band in iNOS−/− mice and upregulation of iNOS protein expression in wild-type mice. Our results confirm the importance of iNOS in I/R injury. Upregulated iNOS exacerbates I/R injury and appears to be a therapeutic target in protection of tissues against this type of injury.

Antioxidant effect of MCI-186, a new Free-Radical scavenger, on ischemia-reperfusion injury in a rat hindlimb amputation model

BACKGROUND

A newly synthesized free-radical scavenger, MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-1), was recently approved in Japan for treating acute brain infarction. The purpose of this study was to investigate whether or not MCI-186 is effective in reducing ischemia-reperfusion injury in the extremities.

MATERIALS AND METHODS

Warm ischemia was sustained for 4 hours. The animals were divided into 4 groups: (1) sham group, (2) control group (saline injection), (3) MCI group (MCI-186 injection), and (4) EPC group (EPC-K1 [(l-ascorbic acid 2-[3,4-dihydro-2, 5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl hydrogen phosphate] potassium salt], a hydroxyl-radical scavenger, injection). Wet and dry (W/D) weights of the gastrocnemius and tibialis anterior muscles, muscle contractile function, and serum levels of creatine phosphokinase (CPK), lactate dehydrogenase (LDH), glutamic oxaloacetic transminase (GOT), and mitochondrial glutamic oxaloacetic transminase (GOT-m) were measured after 24 h of reperfusion. The cytotoxic aldehydes malondialdehyde and 4-hydroxy-2-nonenal as indices of lipid peroxidation (LPO), and neutrophil-specific enzyme myeloperoxidase (MPO) as an index of neutrophil infiltration, were measured in the gastrocnemius muscle.

RESULTS

Contractile functions in the MCI and EPC groups were significantly better than in the control group. In the tibialis anterior muscle, the contractile function was better in the MCI group than in the EPC group. W/D ratios and serum levels of CPK, LDH, GOT, and GOT-m were lower in the sham and MCI groups than in the control group. Levels of LPO and MPO activity were significantly lower in the MCI and EPC groups than in the control group. Histological findings demonstrated that inflammatory tissue reactions rarely occurred in the MCI group.

CONCLUSION

MCI-186 is effective in preventing ischemia-reperfusion injury in extremities. MCI-186 seems to have promise as a therapeutic agent, because it prevents ischemia-reperfusion injury even in the tibialis anterior muscle, which contains fast-twitch glycolytic fibers, known to be very susceptible to ischemic insult.

p66 ShcA Modulates Tissue Response to Hindlimb Ischemia

Background— Oxidative stress plays a pivotal role in ischemia and ischemia/reperfusion injury. Because p66 ShcA -null (p66 ShcA −/−) mice exhibit both lower levels of intracellular reactive oxygen species and increased resistance to cell death induced by oxidative stress, we investigated whether tissue damage that follows acute ischemia or ischemia/reperfusion was altered in p66 ShcA −/− mice.

Methods and Results— Unilateral hindlimb ischemia was induced by femoral artery dissection, and ischemia/reperfusion was induced with an elastic tourniquet. Both procedures caused similar changes in blood perfusion in p66 ShcA wild-type (p66 ShcA wt) and p66 ShcA −/− mice. However, significant differences in tissue damage were found: p66 ShcA wt mice displayed marked capillary density decrease and muscle fiber necrosis. In contrast, in p66 ShcA −/− mice, minimal capillary density decrease and myofiber death were present. When apoptosis after ischemia was assayed, significantly lower levels of apoptotic endothelial cells and myofibers were found in p66 ShcA −/− mice. In agreement with these data, both satellite muscle cells and endothelial cells isolated from p66 ShcA −/− mice were resistant to apoptosis induced by simulated ischemia in vitro. Lower apoptosis levels after ischemia in p66 ShcA −/− cells correlated with decreased levels of oxidative stress both in vivo and in vitro.

Conclusions— p66 ShcA plays a crucial role in the cell death pathways activated by acute ischemia and ischemia/reperfusion, indicating p66 ShcA as a potential therapeutic target for prevention and treatment of ischemic tissue damage.

Xanthine oxidase and activated neutrophils cause oxidative damage to skeletal muscle after contractile claudication

We previously showed oxidative damage and edema within skeletal muscle after contractile claudication. To investigate the sources of this oxidative damage in the gastrocnemius muscle, we administered allopurinol (Allo, to inhibit xanthine oxidase) and cyclophosphamide (Cyclo, to deplete neutrophils) before inducing contractile claudication in male Sprague Dawley rats. Contractile claudication (ligated stimulated, LS) caused a significant increase in xanthine oxidase activity [sham ligated stimulated (SS) = 2.57 +/- 0.07; LS = 3.22 +/- 0.07] and neutrophil infiltration (SS = 0.47 +/- 0.03; LS = 0.91 +/- 0.10) compared with controls (SS), and this was associated with increased lipid peroxidation, protein oxidation, muscle damage, and edema. Pretreatment with Allo attenuated the increase in xanthine oxidase activity and attenuated lipid hydroperoxides (control LS = 12.85 +/- 0.50; Allo LS = 9.96 +/- 0.71), muscle damage, and neutrophil infiltration (control LS = 0.91 +/- 0.10; Allo LS = 0.61 +/- 0.07). This latter finding suggests that xanthine oxidase-derived oxidants are chemotactic to neutrophils. Pretreatment with Cyclo reduced neutrophil infiltration (control LS = 0.91 +/- 0.10; Cyclo LS = 0.55 +/- 0.02) and attenuated lipid peroxidation (control LS = 12.85 +/- 0.50; Cyclo LS = 6.462 +/- 0.62), protein oxidation (control LS = 2.59 +/- 0.47; Cyclo LS = 1.77 +/- 0.60), muscle damage, and edema. Together, these data indicate that contractile claudication causes an increase in xanthine oxidase activity and neutrophils in muscle and that inhibition of these oxidant sources protects against oxidative stress, muscle damage, and edema.

Neutropenia impairs venous thrombosis resolution in the rat

OBJECTIVES

Neutrophil influx is one of the first events in a formed deep venous thrombosis (DVT), but whether these cells are active participants in the resolution process is not clear. This study tests the hypothesis that neutrophils (PMN) are active participants in DVT resolution.

METHODS

Thrombosis was induced by inferior vena caval (IVC) ligation in male Sprague-Dawley rats, and rats were sacrificed at 2, 4, or 7 days for evaluation of the thrombus. Neutropenia was induced by rabbit anti-rat PMN serum, and controls received rabbit serum. Venography was performed at the 7-day time point. Immunohistochemical staining was performed to quantify intrathrombus PMNs and monocytes, and the myeloperoxidase (MPO) assay was performed to assess intrathrombus neutrophil activity. Intrathrombus concentrations of kerotinocyte cytokine (KC), macrophage inflammatory protein-2 (MIP-2), gamma interferon inducible protein-10 (IP-10), macrophage inflammatory protein-1 alpha (MIP-1 alpha), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor (TNF)-alpha were quantified by enzyme immunoassay at each time point and normalized to total protein. Total collagen was determined at day 7.

RESULTS

Peripheral blood smears showed a 94% PMN reduction at 2 days (P <.05), recovering to 44% of control at 7 days. Intrathrombus PMNs were significantly lower in neutropenic rats at 2 and 4 days, but there were no differences in intrathrombus monocytes. The MPO assay confirmed reduced neutrophil activity at 4 days. Thrombi from neutropenic rats were larger at 2 and 7 days compared with controls. In vivo thrombus area at 7 days as assessed by venography was also greater in neutropenic rats as compared with controls. The intrathrombus KC concentration was increased more than 20-fold in the neutropenic rats at 2 days, but there were no significant differences in other intrathrombus chemokines. Finally, intrathrombus collagen was increased over threefold in neutropenic rats as compared with controls.

CONCLUSION

Neutropenia impairs DVT resolution by several measures, most likely by altering normal fibrinolytic activity and thrombus collagen turnover.