Low-level laser therapy associated to N-acetylcysteine lowers macrophage inflammatory protein-2 (MIP-2) mRNA expression and generation of intracellular reactive oxygen species in alveolar macrophages.

OBJECTIVE: The aim of this work was to investigate the low-level laser therapy (LLLT) effect on alveolar macrophages (AM) activated by oxidative stress and lipopolysaccharide (LPS). BACKGROUND DATA: LLLT has been reported to actuate positively relieving the late and early symptoms of airway and lung inflammation. It is not known if the increased MIP-2 mRNA expression and intracellular reactive oxygen species (ROS) generation observed in acute lung inflammation (ALI) can be influenced by LLLT. MATERIALS AND METHODS: Rat AM cell line (AMJ2-C11) was cultured with LPS or H(2)O(2) and laser irradiated. MIP-2 mRNA and ROS production in the AM were evaluated by Real Time-PCR and the 2',7'-dichlorofluorescin diacetate (DCFH-DA) respectively. The NF-κB protein in the AM was measured by the enzyme linked immunoassay method. To investigate the antioxidant effect of laser, the AM were prebathed with N-acetylcysteine (NAC) and then irradiated with laser. LLLT was also studied in the presence of an inhibitor of NF-κB (BMS 205820). In addition, the effect of LLLT on NF-κB protein was investigated. RESULTS: LLLT attenuated the MIP-2 mRNA expression and intracellular ROS generation after LPS or H(2)O(2). When the AM were pretreated with NAC, the laser effect was potentiated. BMS 205820 suppresses the effect of LLLT on MIP-2 mRNA expression and ROS generation, stimulated by LPS or H(2)O(2). On NF-κB transcription factor, both the LLLT and NAC reduced this protein in the AM exposed to LPS or H(2)O(2). The synergistic effect between LLLT and NAC on the reduction the NF-κB was also evidenced. CONCLUSION: Results indicate that there is a synergistic action of LLLT with NAC on MIP-2 mRNA expression from LPS- or H(2)O(2)-stimulated AM, and that both ROS intracellular generation and NF-kB signaling seem to be involved.

Endotoxin induces eosinophil accumalation in the rat pleural cavity

Changes in eosinophil counts after intrathoracic (it) injection of endotoxin (LPS) were investigated in Wistar rats (150 - 180 g). Increasing doses of endotoxin (62.5 - 500 ng/cavity) induced a dose-dependent increase in the number of eosinophils recovered from the rat pleural cavity 24 h later. The eosinophilia was apparent within 24 h, peaked within 48 h (from 0.76 ñ 0.12 to 3.68 ñ 0.51 eosinophils x 10**6/cavity, P < 0.001) and returned to basal levels 120h after the it inection of endotoxin (250 ng/cavity). Endotoxin (3 ng - 4 µg/ml) failed to attract eosinophilis in vitro under conditions in which PAF-acether induced a dose-related response. These findings indicate that endotoxin-induced eosinophil migration in vivo is mediated by a secondary mechanism

Pleural eosinophil infiltration induced by PAF-acether is not a desensitizable phenomenon

This study investigated the effect of successive daily intrathoracic (it) injections of PAF-acether upon its demonstrated ability to generate eosinochemotaxin(s). Repeated administration of PAF-acether led to a selective state of desensitization, characterized by a gradual reduction of its ability to induce exudation. Concomitantly, however, there was a progressive pleural accumulation of eosinophilis leading to a 7-fold increase in the eosinophil counts after the 4th restimulation. The generation of eosinochemotaxin(s) elicited by PAF-acether was not modified by desensitization, as detected by transferring the cell-free pleural fluid from donor to recipient animals. We conclude that, in contrast to exudation, eosinophil tissue infiltration induced by PAF-acether is not a desensitizable phenomenon

Adrenalectomy exacerbates paw edema without interfering with desensitization induced by PAF-acether in rats

Subcutaneous injection of PAF-acether into rat's paw to a local inflammatory response (edema) followed by desensitization after repeated injections of the substance. The desensitizing effect was not modified by previous adrenalectomy, whereas the inflammatory response observed after the first injection of PAF-acether was exacerbated. This finding suggests that adrenal hormones may act as modulators of PAF-induced inflammatory reactions. Because LY 171883, an LTD4 blocker, inhibited the edema which follows the first injection of PAF-acether, we suggest that leukotrienes may play an important role in the phenomenon