Secretory leucoprotease inhibitor (SLPI) is a nonglycosylated protein produced by epithelial cells. In addition to its antiprotease activity, SLPI has been shown to exhibit antiinflammatory properties, including down-regulation of tumor necrosis factor α expression by lipopolysaccharide (LPS) in macrophages and inhibition of nuclear factor (NF)-κB activation in a rat model of acute lung injury. We have previously shown that SLPI can inhibit LPS-induced NF-κB activation in monocytic cells by inhibiting degradation of IκBα without affecting the LPS-induced phosphorylation and ubiquitination of IκBα. Here, we present evidence to show that upon incubation with peripheral blood monocytes (PBMs) and the U937 monocytic cell line, SLPI enters the cells, becoming rapidly localized to the cytoplasm and nucleus, and affects NF-κB activation by binding directly to NF-κB binding sites in a site-specific manner. SLPI can also prevent p65 interaction with the NF-κB consensus region at concentrations commensurate with the physiological nuclear levels of SLPI and p65. We also demonstrate the presence of SLPI in nuclear fractions of PBMs and alveolar macrophages from individuals with cystic fibrosis and community-acquired pneumonia. Therefore, SLPI inhibition of NF-κB activation is mediated, in part, by competitive binding to the NF-κB consensus-binding site.

Cystic fibrosis (CF) is a genetic disease characterized by severe neutrophil-dominated airway inflammation. An important cause of inflammation in CF is Pseudomonas aeruginosa infection. We have evaluated the importance of a number of P. aeruginosa components, namely lipopeptides, LPS, and unmethylated CpG DNA, as proinflammatory stimuli in CF by characterizing the expression and functional activity of their cognate receptors, TLR2/6 or TLR2/1, TLR4, and TLR9, respectively, in a human tracheal epithelial line, CFTE29o−, which is homozygous for the ΔF508 CF transmembrane conductance regulator mutation. We also characterized TLR expression and function in a non-CF airway epithelial cell line 16HBE14o−. Using RT-PCR, we demonstrated TLR mRNA expression. TLR cell surface expression was assessed by fluorescence microscopy. Lipopeptides, LPS, and unmethylated CpG DNA induced IL-8 and IL-6 protein production in a time- and dose-dependent manner. The CF and non-CF cell lines were largely similar in their TLR expression and relative TLR responses. ICAM-1 expression was also up-regulated in CFTE29o− cells following stimulation with each agonist. CF bronchoalveolar lavage fluid, which contains LPS, bacterial DNA, and neutrophil elastase (a neutrophil-derived protease that can activate TLR4), up-regulated an NF-κB-linked reporter gene and increased IL-8 protein production in CFTE29o− cells. This effect was abrogated by expression of dominant-negative versions of MyD88 or Mal, key signal transducers for TLRs, thereby implicating them as potential anti-inflammatory agents for CF.

Rationale: Simvastatin inhibits inflammatory responses in vitro and in murine models of lung inflammation in vivo. As simvastatin modulates a number of the underlying processes described in acute lung injury (ALI), it may be a potential therapeutic option. Objectives: To investigate in vivo if simvastatin modulates mechanisms important in the development of ALI in a model of acute lung inflammation induced by inhalation of lipopolysaccharide (LPS) in healthy human volunteers. Methods: Thirty healthy subjects were enrolled in a double-blind, placebo-controlled study. Subjects were randomized to receive 40 mg or 80 mg of simvastatin or placebo (n 5 10/group) for 4 days before inhalation of 50 mg LPS. Measurements were performed in bronchoalveolar lavage fluid (BALF) obtained at 6 hours and plasma obtained at 24 hours after LPS challenge. Nuclear translocation of nuclear factor-kB (NF-kB) was measured in monocyte-derived macrophages. Measurements and Main Results: Pretreatment with simvastatin reduced LPS-induced BALF neutrophilia, myeloperoxidase, tumor necrosis factor-a, matrix metalloproteinases 7, 8, and 9, and C-reactive protein (CRP) as well as plasma CRP (all P , 0.05 vs. placebo). There was no significant difference between simvastatin 40 mg and 80 mg. BALF from subjects post-LPS inhalation induced a threefold up-regulation in nuclear NF-kB in monocyte-derived macrophages (P , 0.001); pretreatment with simvastatin reduced this by 35% (P , 0.001). Conclusions: Simvastatin has antiinflammatory effects in the pulmonary and systemic compartment in humans exposed to inhaled LPS. Clinical trial registered with www.controlled-trials.com (ISRCTN21056528).

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Conformational diseases are a class of disorders associated with aberrant protein accumulation in tissues and cellular compartments. Z α1-antitrypsin (A1AT) deficiency is a genetic disease associated with accumulation of misfolded A1AT in the endoplasmic reticulum (ER) of hepatocytes. We sought to identify intracellular events involved in the molecular pathogenesis of Z A1AT-induced liver disease using an in vitro model system of Z A1AT ER accumulation. We investigated ER stress signals induced by Z A1AT and demonstrated that both the ER overload response and the unfolded protein response were activated by mutant Z A1AT, but not wild-type M A1AT. Interestingly, activation of the unfolded protein response pathway required an additional insult, whereas NF-κB activation, a hallmark of the ER overload response, was constitutive. These findings have important implications for the design of future therapeutics for Z A1AT liver disease and may also impact on drug design for other conformational diseases.

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Cystic fibrosis is characterised in the lungs by high levels of neutrophil elastase (NE). NE induces interleukin-8 (IL-8) expression via an IL-1 receptor-associated kinase signalling pathway. Here, we show that these events involve the cell surface membrane bound toll-like receptor 4 (TLR4). We demonstrate that human embryonic kidney (HEK)293 cells transfected with a TLR4 cDNA (HEK-TLR4) express TLR4 mRNA and protein and induce IL-8 promoter activity in response to NE. Treatment of both HEK-TLR4 and human bronchial epithelial cells with NE decreases TLR4 protein expression. Furthermore, a TLR4 neutralising antibody abrogates NE-induced IL-8 production, and induces tolerance to a secondary lipopolysaccharide stimulus. These data implicate TLR4 in NE induced IL-8 expression in bronchial epithelium.

Secretory leucoprotease inhibitor (SLPI) is a non-glycosylated protein produced by epithelial cells, macrophages, and neutrophils and was initially identified as a serine protease inhibitor of the neutrophil proteases elastase and cathepsin G. In addition to its antiprotease activity, SLPI has been shown to exhibit anti-inflammatory properties including down-regulation of tumor necrosis factor-␣ expression by lipopolysaccharide (LPS) in monocytes, inhibition of NF-B activation by IgG immune complexes in a rat model of acute lung injury, and prevention of human immunodeficiency virus infectivity in monocytic cells via as yet unidentified mechanisms. In this report we have shown that SLPI prevents LPS-induced NF-B activation by inhibiting degradation of IB␣ without affecting the LPS-induced phosphorylation and ubiquitination of IB␣. We have also demonstrated that SLPI prevents LPS-induced interleukin-1 receptor-associated kinase and IB␤ degradation. In addition, we have demonstrated that oxidized SLPI, a variant of SLPI that has diminished antiprotease activity, cannot prevent LPS-induced NF-B activation or Inhibitor B ␣/␤ degradation indicating that the antiinflammatory effect of SLPI on the LPS-signaling pathway is dependent on its antiprotease activity. These results suggest that SLPI may be inhibiting proteasomal degradation of NF-B regulatory proteins, an effect that is dependent on the antiprotease activity of SLPI. Secretory leucoprotease inhibitor (SLPI)1 is an 11.7-kDa non-glycosylated protein, which is expressed by epithelial cells, macrophages, and neutrophils (1-3). It is found in various secretory fluids but primarily bronchial and nasal secretions (4, 5). SLPI forms inhibitory complexes with a variety of proteolytic enzymes including neutrophil elastase and cathepsin G and therefore appears to be an important component of the antiprotease defense of the lung (6). The amino acid sequence of SLPI and the resulting NMR solution structure have revealed a protein composed of two highly homologous domains of 53 and 54 amino acids, 8 disulfide bridges in total, and a large number of positively charged residues (7). The small size of SLPI and the large number of disulfide bridges were thought to confer resistance of SLPI to proteolysis. However, we have demonstrated recently (8) that SLPI is susceptible to proteolytic cleavage by members of the elastolytic cathepsin family and that cathepsin L present in the emphysematous lung results in SLPI cleavage and inactivation of its antiprotease activity.Recently, it has been demonstrated that SLPI also possesses anti-inflammatory, anti-viral, and anti-bacterial activity. LPShyporesponsive cells have been shown to transcribe SLPI, and transfection of macrophages with SLPI was shown to suppress LPS-induced activation of NF-B and production of nitric oxide and TNF␣ by an unknown mechanism (9). In addition, IFN␥ suppressed expression of SLPI and restored LPS responsiveness to SLPI-producing cells (9). SLPI has also been shown to inhibit HIV infectivity of monocytes by ...