Lipopolysaccharide-induced lung injury: role of P2X7 receptor.

RATIONALE: P2X7 receptors have been involved in inflammatory and immunological responses, and their activation modulates pro-inflammatory cytokines production by LPS-challenged macrophages. OBJECTIVES: To determine the role of P2X7R in LPS-induced acute lung injury in mice. METHODS: Wild-type (C57BL/6) and P2X7 knockout mice received intratracheal injection of saline or Escherichia coli LPS (60 µg). After 24h, changes in lung mechanics were determined by the end-inflation occlusion method. Bronchoalveolar lavage was performed, and lungs were harvested for measurement of morphometry, fibers content, inflammatory cells and cytokine expression by histochemistry and immunohistochemistry. RESULTS: Compared with saline, LPS increased lung mechanical parameters, mast cell, collagen and fibronectin deposition in lung parenchyma, as well as nitric oxide and lactate dehydrogenase release into bronchoalveolar fluid in wild-type, but not in P2X7R knockout mice. Alveolar collapse, lung influx of polymorphonuclear and CD14(+) cells, as well as TGF-ß, MMP-2, and IL-1ß release were higher in wild-type than knockout LPS-challenged mice, while MMP-9 release where similar between the two genotypes. LPS increased macrophage immunoreactivity in lung tissue in both genotypes, but macrophages were not activated in the P2X7R knockout mice. Furthermore, LPS administration increased P2X7R immunoexpression in lung parenchyma in wild-type mice, and TLR4 in both wild-type and P2X7R knockout mice. CONCLUSION: P2X7 receptors are implicated in the pathophysiology of LPS-induced lung injury, modulating lung inflammatory and functional changes.

Mate tea reduced acute lung inflammation in mice exposed to cigarette smoke.

OBJECTIVE: Short-term cigarette smoke exposure has been associated with acute lung inflammation (ALI) and oxidative damage. We studied mate tea (Ilex paraguariensis infusion) as a possible nutritional resource for ALI. METHODS: C57BL/6 mice (n = 30) were administered with mate tea orally (150 mg/kg, CSMO), mate tea intraperitonially (150 mg/kg, CSMIP), or the vehicle (CS) and then exposed to cigarette smoke for 5 d (six cigarettes per day). The control group was sham-smoked (n = 30). One day after the final exposure, mice were sacrificed. Bronchoalveolar lavages were performed and lungs removed for biochemical (lung homogenates) and histologic analyses. RESULTS: Mate tea reduced the increase of alveolar macrophages and neutrophils in bronchoalveolar lavages (cells x 10(3)/mL) of the CSMO (214.3 +/- 21.4 and 12.2 +/- 4.9) and CSMIP (248.3 +/- 11.1 and 12.1 +/- 2.3) groups compared with the CS group (425.9 +/- 28.1 and 140.5 +/- 20.1). Mate tea reduced lipid peroxidation (the control group was considered 100%) and tumor necrosis factor-alpha (picograms per milliliter) in the CSMO group (61.3 +/- 11.3 and 185.3 +/- 21.8) compared with the CS group (150.0 +/- 18.1 and 242.3 +/- 13.2). Matrix metalloprotease-9 activity was higher in the CS group and lower in the CSMO group. Oxidative and inflammatory markers in the CSMO group were not different from those in the control group. CONCLUSION: These data imply a potential antioxidant role for mate tea on ALI. Further studies are needed to determine such mechanisms and to explore its potential as an anti-inflammatory and nutritional resource in lung damaged by cigarette smoke exposure.