Macrophage-stimulating protein differently affects human alveolar macrophages from smoker and non-smoker patients: evaluation of respiratory burst, cytokine release and NF-kappaB pathway

1 Macrophage activation is a key feature of inflammatory reactions occurring during bacterial infections, immune responses and tissue injury. We previously demonstrated that human macrophages of different origin express the tyrosine kinase receptor recepteur d'origine nantaise, the human receptor for MSP ( RON) and produce superoxide anion ( O-2(-)) when challenged with macrophage-stimulating protein ( MSP), the endogenous ligand for RON. 2 This study was aimed to evaluate the role of MSP in alveolar macrophages ( AM) isolated from healthy volunteers and patients with interstitial lung diseases ( sarcoidosis, idiopathic pulmonary fibrosis), either smokers or non- smokers, by evaluating the respiratory burst, cytokine release and nuclear factor- kappa B ( NF-kappa B) activation. MSP effects were compared with those induced by known AM stimuli, for example, phorbol myristate acetate, N- formyl- methionyl- leucyl- phenylalanine, lipopolysaccharide. 3 MSP evokes O-2(-) production, cytokine release and NF- kappa B activation in a concentration- dependent manner. By evaluating the respiratory burst, we demonstrate a significantly increased O-2(-) production in AM from healthy smokers or smokers with pulmonary fibrosis, as compared to non- smokers, thus suggesting MSP as an enhancer of cigarette smoke toxicity. 4 Besides inducing interleukin- 1 beta ( IL- 1 beta) and interleukin- 10 ( IL- 10) production, MSP triggers an enhanced tumor necrosis factor- alpha release, especially in healthy and pulmonary fibrosis smokers. On the contrary, MSP- induced IL- 10 release is higher in AM from healthy non- smokers. 5 MSP activates the transcription factor NF- kB; this effect is more potent in healthy and fibrosis smokers ( 2.5- fold increase in p50 subunit translocation). This effect is receptor- mediated, as it is prevented by a monoclonal anti- human MSP antibody. 6 The higher effectiveness of MSP in AM from healthy smokers and patients with pulmonary fibrosis is suggestive of its role in these clinical conditions

Anti-inflammatory drugs and tumor necrosis factor-alpha production from monocytes: role of transcription factor NF-kappaB and implication for rheumatoid arthritis therapy

Inhibition of tumor necrosis factor-alpha (TNF-alpha) represents a relevant target in rheumatoid arthritis therapy. Besides inhibiting cyclooxygenase, anti-inflammatory drugs can affect the activation of transcription factors. We investigated the ability of dexamethasone, indomethacin, and rofecoxib to modulate nuclear factor-kappaB (NF-kappaB) activation and TNF-alpha release from human monocytes challenged with lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA). Both stimuli induced NF-kappaB nuclear translocation and TNF-a secretion. Dexamethasone potently inhibited TNF-alpha release, indomethacin inhibited only PMA-evoked release, while rofecoxib had no effect. In the electrophoretic mobility shift assay, dexamethasone and rofecoxib dose-dependently inhibited the DNA binding activity of NF-kappaB in stimulated monocytes, whereas indomethacin failed to inhibit the LPS-evoked one. These results were further confirmed by evaluating the drugs' ability to reduce nuclear NF-kappaB subunits, as well as the amount of phosphorylated IkappaBalpha in cytosolic fractions. In conclusion, these results indicate that anti-inflammatory drugs differ largely in their ability to inhibit NF-kappaB activity and/or TNF-alpha release from human monocytes. These effects can be relevant to rheumatoid arthritis therapy