Role of NO and PAF in the impairment of skeletal muscle contractility induced by TNF-α

2000 ◽  
Vol 279 (6) ◽  
pp. R2156-R2163 ◽  
Author(s):  
Giuseppe Alloatti ◽  
Claudia Penna ◽  
Filippo Mariano ◽  
Giovanni Camussi
Keyword(s):  
Skeletal Muscle ◽  
Methyl Ester ◽  
Platelet Activating Factor ◽  
Inhibitory Effect ◽  
No Production ◽  
Force Frequency ◽  
Muscle Contractility ◽  
Tnf Α ◽  
Frequency Relationship

The role of platelet-activating factor (PAF) and nitric oxide (NO) as mediators of the effects of tumor necrosis factor-α (TNF-α) on skeletal muscle contractility was studied in guinea pig extensor digitorum longus (EDL) muscle. TNF-α (5–10 ng/ml) reduced contractility at every stimulation frequency (1–200 Hz) and shifted the force-frequency relationship to the right. The role of NO and PAF as mediators of TNF-α was suggested by the protective effect of N G-nitro-l-arginine methyl ester (l-NAME; 1 mM), but not of N G-nitro-d-arginine methyl ester (d-NAME; 1 mM), and by the inhibitory effect of the PAF-receptor antagonist WEB-2170 (3 μM). TNF-α increased the production of PAF and NO. Similar to TNF-α, both S-nitroso- N-acetylpenicillamine (0.5–1 μM), an NO-generating compound, and PAF (10–20 nM) reduced EDL contractility. l-NAME, but not d-NAME, blocked the negative effect of PAF. Blockade of phospholipase A2, which is required for PAF synthesis, significantly reduced the effects of TNF-α. WEB-2170 inhibited NO synthesis induced by TNF-α and PAF-stimulated NO production. These results suggest that both PAF and NO contribute to the development of the mechanical alterations induced by TNF-α and that NO production is downstream to the synthesis of PAF.

Lipopolysaccharide and proinflammatory cytokines stimulate interleukin-6 expression in C2C12 myoblasts: role of the Jun NH2-terminal kinase

2003 ◽  
Vol 285 (5) ◽  
pp. R1153-R1164 ◽  
Author(s):  
Robert A. Frost ◽  
Gerald J. Nystrom ◽  
Charles H. Lang
Keyword(s):  
Skeletal Muscle ◽  
Map Kinases ◽  
Kinase Inhibitors ◽  
Inhibitory Effect ◽  
C2c12 Myoblasts ◽  
Downstream Target ◽  
Tnf Α ◽  
Inflammatory Stimuli

IL-6 is a major inflammatory cytokine that plays a central role in coordinating the acute-phase response to trauma, injury, and infection in vivo. Although IL-6 is synthesized predominantly by macrophages and lymphocytes, skeletal muscle is a newly recognized source of this cytokine. IL-6 from muscle spills into the circulation, and blood-borne IL-6 can be elevated >100-fold due to exercise and injury. The purpose of the present study was to determine whether inflammatory stimuli, such as LPS, TNF-α, and IL-1β, could increase IL-6 expression in skeletal muscle and C2C12 myoblasts. Second, we investigated the role of mitogen-activated protein (MAP) kinases, and the Jun NH2-terminal kinase (JNK) in particular, as a mediator of this response. Intraperitoneal injection of LPS in mice increased the circulating concentration of IL-6 from undetectable levels to 4 ng/ml. LPS also increased IL-6 mRNA 100-fold in mouse fast-twitch skeletal muscle. Addition of LPS, IL-1β, or TNF-α directly to C2C12 myoblasts increased IL-6 protein (6- to 8-fold) and IL-6 mRNA (5- to 10-fold). The response to all three stimuli was completely blocked by the JNK inhibitor SP-600125 but not as effectively by other MAP kinase inhibitors. SP-600125 blocked LPS-stimulated IL-6 synthesis dose dependently at both the RNA and protein level. SP-600125 was as effective as the synthetic glucocorticoid dexamethasone at inhibiting IL-6 expression. SP-600125 inhibited IL-6 synthesis when added to cells up to 60 min after LPS stimulation, but its inhibitory effect waned with time. LPS stimulated IL-6 mRNA in both myoblasts and myotubes, but myoblasts showed a proportionally greater LPS-induced increase in IL-6 protein expression compared with myotubes. SP-600125 and the proteasomal inhibitor MG-132 blocked LPS-induced degradation of IκB-α/ϵ and LPS-stimulated expression of IκB-α mRNA. Yet, only SP-600125 and not MG-132 blocked LPS-induced IL-6 mRNA expression. This suggests that IL-6 gene expression is a downstream target of JNK in C2C12 myoblasts.

scholarly journals Platelet-Activating Factor Induces Nitric Oxide Synthesis in Trypanosoma cruzi-Infected Macrophages and Mediates Resistance to Parasite Infection in Mice

1999 ◽  
Vol 67 (6) ◽  
pp. 2810-2814 ◽  
Author(s):  
Júlio C. S. Aliberti ◽  
Fabiana S. Machado ◽  
Ricardo T. Gazzinelli ◽  
Mauro M. Teixeira ◽  
João S. Silva
Keyword(s):  
Trypanosoma Cruzi ◽  
Platelet Activating Factor ◽  
No Production ◽  
Activated Macrophages ◽  
Mechanisms Of Resistance ◽  
Trypanocidal Activity ◽  
Intracellular Parasites ◽  
Tnf Α

ABSTRACT Trypanosoma cruzi replicates in nucleated cells and is susceptible to being killed by gamma interferon-activated macrophages through a mechanism dependent upon NO biosynthesis. In the present study, the role of platelet-activating factor (PAF) in the induction of NO synthesis and in the activation of the trypanocidal activity of macrophages was investigated. In vitro, PAF induced NO secretion byT. cruzi-infected macrophages and the secreted NO inhibited intracellular parasite growth. The addition of a PAF antagonist, WEB 2170, inhibited both NO biosynthesis and trypanocidal activity. The inducible NO synthase/l-arginine pathway mediated trypanocidal activity, since it was inhibited by treatment withl-N-monomethyl arginine (l-NMMA), an l-arginine analog. PAF-mediated NO production in infected macrophages appears to be dependent on tumor necrosis alpha (TNF-α) production, since the addition of a neutralizing anti-TNF-α monoclonal antibody mAb inhibited NO synthesis. To test the role of PAF in mediating resistance or susceptibility to T. cruziinfection, infected mice were treated with WEB 2170, a PAF antagonist. These animals had higher parasitemia and earlier mortality than did vehicle-treated mice. Taken together, our results suggest that PAF belongs to a group of mediators that coordinate the mechanisms of resistance to infections with intracellular parasites.

scholarly journals Let-7a-5p regulates the inflammatory response in chronic rhinosinusitis with nasal polyps

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Jianwei Zhang ◽  
Lei Han ◽  
Feng Chen
Keyword(s):  
Inflammatory Response ◽  
Chronic Rhinosinusitis ◽  
Nasal Polyps ◽  
Mapk Pathway ◽  
Inhibitory Effect ◽  
Luciferase Reporter ◽  
Western Blot Assay ◽  
Protein Levels ◽  
Tnf Α

Abstract Background Let-7a-5p is demonstrated to be a tumor inhibitor in nasopharyngeal carcinoma. However, the role of let-7a-5p in chronic rhinosinusitis with nasal polyps (CRSwNP) has not been reported. This study is designed to determine the pattern of expression and role of let-7a-5p in CRSwNP. Methods The expression level of let-7a-5p, TNF-α, IL-1β, and IL-6 in CRSwNP tissues and cells were detected by RT-qPCR. Western blot assay was carried out to measure the protein expression of the Ras-MAPK pathway. Dual luciferase reporter assay and RNA pull-down assay were used to explore the relationship between let-7a-5p and IL-6. Results Let-7a-5p was significantly downregulated in CRSwNP tissues and cells. Moreover, the mRNA expression of TNF-α, IL-1β and IL-6 was increased in CRSwNP tissues, while let-7a-5p mimic inhibited the expression of TNF-α, IL-1β and IL-6. Besides that, let-7a-5p was negatively correlated with TNF-α, IL-1β and IL-6 in CRSwNP tissues. In our study, IL-6 was found to be a target gene of let-7a-5p. Additionally, let-7-5p mimic obviously reduced the protein levels of Ras, p-Raf1, p-MEK1 and p-ERK1/2, while IL-6 overexpression destroyed the inhibitory effect of let-7a-5p on the Ras-MAPK pathway in CRSwNP. Conclusion We demonstrated that let-7a-5p/IL-6 interaction regulated the inflammatory response through the Ras-MAPK pathway in CRSwNP.

scholarly journals Grain dust-induced lung inflammation is reduced byRhodobacter sphaeroidesdiphosphoryl lipid A

1998 ◽  
Vol 274 (1) ◽  
pp. L26-L31 ◽  
Author(s):  
Paul J. Jagielo ◽  
Timothy J. Quinn ◽  
Nilofer Qureshi ◽  
David A. Schwartz
Keyword(s):  
Inflammatory Response ◽  
Airway Inflammation ◽  
Lipid A ◽  
Partial Agonist ◽  
Inhibitory Effect ◽  
Sterile Saline ◽  
Endotoxin Activity ◽  
Tnf Α ◽  
Grain Dust

To further determine the importance of endotoxin in grain dust-induced inflammation of the lower respiratory tract, we evaluated the efficacy of pentaacylated diphosphoryl lipid A derived from the lipopolysaccharide of Rhodobacter sphaeroides (RsDPLA) as a partial agonist of grain dust-induced airway inflammation. RsDPLA is a relatively inactive compound compared with lipid A derived from Escherichia coli (LPS) and has been demonstrated to act as a partial agonist of LPS-induced inflammation. To assess the potential stimulatory effect of RsDPLA in relation to LPS, we incubated THP-1 cells with RsDPLA (0.001–100 μg/ml), LPS (0.02 μg endotoxin activity/ml), or corn dust extract (CDE; 0.02 μg endotoxin activity/ml). Incubation with RsDPLA revealed a tumor necrosis factor (TNF)-α stimulatory effect at 100 μg/ml. In contrast, incubation with LPS or CDE resulted in TNF-α release at 0.02 μg/ml. Pretreatment of THP-1 cells with varying concentrations of RsDPLA before incubation with LPS or CDE (0.02 μg endotoxin activity/ml) resulted in a dose-dependent reduction in the LPS- or CDE-induced release of TNF-α with concentrations of RsDPLA of up to 10 μg/ml but not at 100 μg/ml. To further understand the role of endotoxin in grain dust-induced airway inflammation, we utilized the unique LPS inhibitory property of RsDPLA to determine the inflammatory response to inhaled CDE in mice in the presence of RsDPLA. Ten micrograms of RsDPLA intratracheally did not cause a significant inflammatory response compared with intratracheal saline. However, pretreatment of mice with 10 μg of RsDPLA intratracheally before exposure to CDE (5.4 and 0.2 μg/m3) or LPS (7.2 and 0.28 μg/m3) resulted in significant reductions in the lung lavage concentrations of total cells, neutrophils, and specific proinflammatory cytokines compared with mice pretreated with sterile saline. These results confirm the LPS-inhibitory effect of RsDPLA and support the role of endotoxin as the principal agent in grain dust causing airway inflammation.

Does autonomic blockade reveal a potent contribution of nitric oxide to locomotion-induced vasodilation?

2000 ◽  
Vol 279 (2) ◽  
pp. H726-H732 ◽  
Author(s):  
Don D. Sheriff ◽  
Christopher D. Nelson ◽  
Ryan K. Sundermann
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
No Production ◽  
Vascular Conductance ◽  
Absolute Level ◽  
Autonomic Blockade ◽  
The Absolute ◽  
Ganglionic Transmission ◽  
Treadmill Locomotion

We sought to test the role of nitric oxide (NO) in governing skeletal muscle (iliac) vascular conductance during treadmill locomotion in dogs ( n = 6; 3.2 and 6.4 km/h at 0% grade, and 6.4 km/h at 10% grade). As seen previously, the increase in muscle vascular conductance accompanying treadmill locomotion was little influenced by NO synthase inhibition alone with N ω-nitro-l-arginine methyl ester (l-NAME, 10 mg/kg iv), but the absolute value of conductance achieved during locomotion was reduced. Such ambiguous results provide an unclear picture regarding the importance of NO during locomotion. However, muscle vasodilation is normally restrained by the sympathetic system during locomotion. Thus a significant contribution by NO to the increase in vascular conductance that accompanies locomotion could be masked by partial withdrawal of the competing influence of sympathetic vasoconstrictor nerve activity secondary to the rise in arterial pressure following systemicl-NAME administration. To test this possibility, we compared the rise in muscle vascular conductance before and afterl-NAME treatment while ganglionic transmission was blocked by hexamethonium. Under these conditions, l-NAME significantly reduced both the rise in vascular conductance (by 32%, P < 0.001) and the absolute level of vascular conductance (by 30%, P < 0.001) achieved during locomotion with no effect on blood flow. Thus augmented NO production normally provides a significant drive to relax vascular smooth muscle in active skeletal muscle during locomotion. Potential deficits stemming from the absence of NO following l-NAME treatment are masked by less intense sympathetic restraint when autonomic function is intact.

Sources and implications of basal nitric oxide in spontaneous contractions of guinea pig taenia caeci

2003 ◽  
Vol 285 (4) ◽  
pp. G747-G753 ◽  
Author(s):  
Catalina Caballero-Alomar ◽  
Carmen Santos ◽  
Diego Lopez ◽  
M. Teresa Mitjavila ◽  
Pere Puig-Parellada
Keyword(s):  
Nitric Oxide ◽  
Guinea Pig ◽  
Inhibitory Effect ◽  
No Production ◽  
Paramagnetic Resonance ◽  
Synthase Inhibitor ◽  
Spontaneous Contractions ◽  
Electron Paramagnetic

We examined in vitro the source and role of basal nitric oxide (NO) in proximal segments of guinea pig taenia caeci in nonadrenergic, noncholinergic (NANC) conditions. Using electron paramagnetic resonance (EPR), we measured the effect of the NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME, 10–4 M), the neuronal blocker tetrodotoxin (TTX, 10–6 M), or both on spontaneous contractions and on the production of basal NO. Both l-NAME and TTX, when tested alone, increased the amplitude and frequency of contractions. NO production was abolished by l-NAME and was inhibited by 38% by TTX. When tested together, l-NAME in the presence of TTX or TTX in the presence of l-NAME had no further effect on the amplitude or frequency of spontaneous contractions, and the NO production was inhibited. These findings suggest that basal NO consists of TTX-sensitive and TTX-resistant components. The TTX-sensitive NO has an inhibitory effect on spontaneous contractions; the role of TTX-resistant NO is unknown.

scholarly journals Diphlorethohydroxycarmalol (DPHC) Isolated from the Brown Alga Ishige okamurae Acts on Inflammatory Myopathy as an Inhibitory Agent of TNF-α

Marine Drugs ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. 529
Author(s):  
Seo-Young Kim ◽  
Ginnae Ahn ◽  
Hyun-Soo Kim ◽  
Jun-Geon Je ◽  
Kil-Nam Kim ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Muscle Atrophy ◽  
Inflammatory Myopathy ◽  
Biologically Active ◽  
C2c12 Myotubes ◽  
No Production ◽  
Ishige Okamurae ◽  
Tnf Α ◽  
Anti Inflammatory

Inflammation affects various organs of the human body, including skeletal muscle. Phlorotannins are natural biologically active substances found in marine brown algae and exhibit anti-inflammatory activities. In this study, we focused on the effects of phlorotannins on anti-inflammatory activity and skeletal muscle cell proliferation activity to identify the protective effects on the inflammatory myopathy. First, the five species of marine brown algal extracts dramatically inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells without toxicity at all the concentrations tested. Moreover, the extracts collected from Ishige okamurae (I. okamurae) significantly increased cell proliferation of C2C12 myoblasts compared to the non-treated cells with non-toxicity. In addition, as a result of finding a potential tumor necrosis factor (TNF)-α inhibitor that regulates the signaling pathway of muscle degradation in I. okamurae-derived natural bioactive compounds, Diphlorethohydroxycarmalol (DPHC) is favorably docked to the TNF-α with the lowest binding energy and docking interaction energy value. Moreover, DPHC down-regulated the mRNA expression level of pro-inflammatory cytokines and suppressed the muscle RING-finger protein (MuRF)-1 and Muscle Atrophy F-box (MAFbx)/Atrgoin-1, which are the key protein muscle atrophy via nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPKs) signaling pathways in TNF-α-stimulated C2C12 myotubes. Therefore, it is expected that DPHC isolated from IO would be developed as a TNF-α inhibitor against inflammatory myopathy.

scholarly journals Endogenous vascular remodeling in ischemic skeletal muscle: a role for nitric oxide

2003 ◽  
Vol 94 (3) ◽  
pp. 935-940 ◽  
Author(s):  
John B. Buckwalter ◽  
Valerie C. Curtis ◽  
Zoran Valic ◽  
Stephen B. Ruble ◽  
Philip S. Clifford
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Methyl Ester ◽  
Vascular Remodeling ◽  
Treated Group ◽  
No Synthase ◽  
No Production ◽  
Ischemic Limb ◽  
Time Flow

To test the hypothesis that nitric oxide (NO) production is essential for endogenous vascular remodeling in ischemic skeletal muscle, 22 New Zealand White rabbits were chronically instrumented with transit-time flow probes on the common iliac arteries and underwent femoral ligation to produce unilateral hindlimb ischemia. Iliac blood flow and arterial pressure were recorded at rest and during a graded exercise test. An osmotic pump connected to a femoral arterial catheter continuously delivered N-nitro-l-arginine methyl ester (a NO synthase inhibitor) or a control solution ( N-nitro-d-arginine methyl ester or phenylephrine) to the ischemic limb over a 2-wk period. At 1, 3, and 6 wk after femoral ligation, maximal treadmill exercise blood flow in the ischemic limb was reduced compared with baseline in each group. However, maximal exercise blood flow was significantly ( P < 0.05) lower in the l-NAME-treated group than in controls for the duration of the study: 48 ± 4 vs. 60 ± 5 ml/min at 6 wk. Consistent with the reduction in maximal blood flow response, the duration of voluntary exercise was also substantially ( P < 0.05) shorter in thel-NAME-treated group: 539 ± 67 vs. 889 ± 87 s. Resting blood flow was unaffected by femoral ligation in either group. The results of this study show that endogenous vascular remodeling, which partially alleviated the initial deficit in blood flow, was interrupted by NO synthase inhibition. Therefore, we conclude that NO is essential for endogenous collateral development and angiogenesis in ischemic skeletal muscle in the rabbit.

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