Neutrophil Chemotaxis, Phagocytosis, and Generation of Reactive Oxygen Species Show a Hierarchy of Responsiveness to Increasing Concentrations of N-Formyl-Met-Leu-Phe

Iizawa, Osamu; Akamatsu, Hirohiko; Niwa, Yukie

doi:10.1159/000109415

Cited by 22 publications

(17 citation statements)

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“…A possible hierarchical response for neutrophils in the presence of pathogenic microbes is also best exemplified by another subset of bacterial peptides. At a low concentration of fMLP, chemotaxis and phagocytosis of neutrophils are more prevalent, while a high concentration of fMLP generates free radials and possible tissue damage (27). In summary, the present study is the first to clearly show that neutrophils invading in whole skeletal muscle are not fully activated following the unloading and reloading protocol and that another stimulus such as LPS is necessary to induce maximal neutrophil activation and muscle fiber damage.…”

Section: Discussionmentioning

confidence: 62%

Neutrophil-induced skeletal muscle damage: a calculated and controlled response following hindlimb unloading and reloading

Dumont¹,

Bouchard²,

Frenette³

2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Neutrophils phagocyte necrotic debris and release cytokines, enzymes, and oxidative factors. In the present study, we investigated the contribution of neutrophils to muscle injury, dysfunction, and recovery using an unloading and reloading model. Mice were submitted to 10 days of hindlimb unloading and were transiently depleted in neutrophils with anti-Ly6G/Ly6C antibody prior to reloading. Leukocyte accumulation and muscle function were assessed immunohistologically and functionally in vitro. In addition, soleus muscles submitted to unloading and reloading were incubated in vitro with LPS (100 microg/ml) to determine whether exogenous stimulus would activate neutrophil response and produce extensive muscle damage. Contractile properties were recorded every hour for 6 h, and muscles were subsequently incubated in procion orange to assess muscle damage. Neutrophil depletion affected neither the loss in muscle force nor the time of recovery in atrophied and reloaded soleus muscles. However, atrophied and reloaded soleus muscles that contained high concentration of neutrophils experienced a 20% greater loss in force than atrophied and reloaded soleus muscles depleted in neutrophils following in vitro incubation with LPS. Procion orange dye also confirmed that neutrophils induced a 2.5-fold increase in muscle membrane damage in the presence of LPS. These results show that neutrophil infiltration during modified mechanical loading is highly regulated and efficiently eliminated, with no significant muscle fiber injury unless the activation state of neutrophils is modified by the presence of LPS.

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Section: Discussionmentioning

confidence: 62%

Neutrophil-induced skeletal muscle damage: a calculated and controlled response following hindlimb unloading and reloading

Dumont¹,

Bouchard²,

Frenette³

2008

American Journal of Physiology-Regulatory, Integrative and Comp

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“…1). Analogs 1 and 3 showed a low but statistically significant (p<0.05) activity at 10 -11 and 10 -10 M, respectively, which are physiological concentrations for chemoattractants [9] , whereas peptide 2 exhibits a lower efficacy. Analog 1 was more potent than fMLP-OMe in inducing O 2 -production at the physiological concentration of 10 -5 M (Fig.…”

Section: Resultsmentioning

confidence: 93%

fMLP-OMe Analogs Substituted at the Methionine Residue: An Insight into the Receptor Properties

Cavicchioni

Monesi

Ferretti

et al. 1998

Arch. Pharm. Pharm. Med. Chem.

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“…Furthermore, the optimal dose of fMLP that induced maximal migration of murine neutrophils under agarose (30 pmol) is ϳ30 times higher than that previously observed, by ourselves and others, for human neutrophils. 40 Other workers have also reported data supporting differential migratory behavior between human and murine cells, 19,40,52 suggesting that this phenomenon is because of species difference. Nevertheless, isolated murine neutrophils are clearly responsive and migrate under agarose toward a chemotactic stimulus.…”

Section: Discussionmentioning

confidence: 96%

A Novel Method for Isolation of Neutrophils from Murine Blood Using Negative Immunomagnetic Separation

Cotter

Norman

Hellewell

et al. 2001

The American Journal of Pathology

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Inappropriate neutrophil activation has been implicated in the pathology of several clinically important inflammatory conditions. Although murine models are extensively used in the investigation of such pathological processes, a reliable method by which viable, quiescent neutrophils can be isolated from murine blood has not been developed. Here we describe a novel method based on negative immunomagnetic separation, which yields highly pure populations of murine neutrophils. Blood is incubated with a cocktail of antibodies against specific cell markers on unwanted cells, and then with secondary antibody-coated magnetic beads. After running the preparation through a column within a magnetic field, labeled cells are retained, and a neutrophil-rich effluent is collected. This method yields a >95% pure suspension of >97% viable neutrophils, recovering ϳ70% of neutrophils from whole blood. Flow cytometric analysis shows little difference in surface Lselectin and CD18 expression on isolated neutrophils compared with neutrophils in whole blood, indicating that neutrophils are minimally activated by the isolation process. Stimulation with phorbol 12-myristate 13-acetate (PMA) reduced L-selectin and increased CD18 expression. Isolated neutrophils migrate under agarose in response to fMLP, and fluorescently labeled neutrophils transfused into recipient mice interact with postcapillary venules in a manner comparable to endogenous leukocytes. These findings show that neutrophils isolated using this method can be used for inflammatory studies in vitro and in vivo.

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Neutrophil Chemotaxis, Phagocytosis, and Generation of Reactive Oxygen Species Show a Hierarchy of Responsiveness to Increasing Concentrations of N-Formyl-Met-Leu-Phe

Cited by 22 publications

References 0 publications

Neutrophil-induced skeletal muscle damage: a calculated and controlled response following hindlimb unloading and reloading

Neutrophil-induced skeletal muscle damage: a calculated and controlled response following hindlimb unloading and reloading

fMLP-OMe Analogs Substituted at the Methionine Residue: An Insight into the Receptor Properties

A Novel Method for Isolation of Neutrophils from Murine Blood Using Negative Immunomagnetic Separation

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