Activation of the NLRP3 inflammasome and subsequent maturation of IL-1β have been implicated in acute lung injury (ALI), resulting in inflammation and fibrosis. We investigated the role of vimentin, a type III intermediate filament, in this process using three well-characterized murine models of ALI known to require NLRP3 inflammasome activation. We demonstrate that central pathophysiologic events in ALI (inflammation, IL-1β levels, endothelial and alveolar epithelial barrier permeability, remodeling, and fibrosis) are attenuated in the lungs of Vim-/- mice challenged with LPS, bleomycin, and asbestos. Bone marrow chimeric mice lacking vimentin have reduced IL-1β levels and attenuated lung injury and fibrosis following bleomycin exposure. Furthermore, decreased active caspase-1 and IL-1β levels are observed in vitro in Vim-/- and vimentin-knockdown macrophages. Importantly, we show direct protein-protein interaction between NLRP3 and vimentin. This study provides insights into lung inflammation and fibrosis and suggests vimentin may be a key regulator of the NLRP3 inflammasome.

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Rationale: Wnt/b-catenin signaling has been implicated in lung fibrosis, but how this occurs and whether expression changes in Wnt pathway components predict disease progression is unknown.Objectives: To determine whether the Wnt coreceptor Lrp5 drives pulmonary fibrosis in mice and is predictive of disease severity in humans.Methods: We examined mice with impaired Wnt signaling caused by loss of the Wnt coreceptor Lrp5 in models of lung fibrosis induced by bleomycin or an adenovirus encoding an active form of transforming growth factor (TGF)-b. We also analyzed gene expression in peripheral blood mononuclear cells (PBMC) from patients with idiopathic pulmonary fibrosis (IPF). Measurements and Main Results:In patients with IPF, analysis of peripheral blood mononuclear cells revealed that elevation of positive regulators, Lrp5 and 6, was independently associated with disease progression. LRP5 was also associated with disease severity at presentation in an additional cohort of patients with IPF. Lrp5 null mice were protected against bleomycin-induced pulmonary fibrosis, an effect that was phenocopied by direct inhibition of b-catenin signaling by the small molecular inhibitor of b-catenin responsive transcription. Transplantation of Lrp5 null bone marrow cells into wild-type mice did not limit fibrosis. Instead, Lrp5 loss was associated with reduced TGF-b production by alveolar type 2 cells and leukocytes. Consistent with a role of Lrp5 in the activation of TGF-b, Lrp5 null mice were not protected against lung fibrosis induced by TGF-b.Conclusions: We show that the Wnt coreceptor, Lrp5, is a genetic driver of lung fibrosis in mice and a marker of disease progression and severity in humans with IPF. Evidence that TGF-b signaling can override a loss in Lrp5 has implications for patient selection and timing of Wnt pathway inhibitors in lung fibrosis.

It is feasible to apply aptamer ligands for use in diagnostic imaging, where they may offer significant advantages over monoclonal antibodies and other reagents.

Background: Leptin regulates appetite through the long isoform of its receptor in the hypothalamus. Although leptin regulates immune responses, it is still unknown whether a direct effect of leptin on lymphocytes is required. Aims: To clarify whether expression of leptin receptors on T lymphocytes modulates intestinal inflammation in mice. Methods: The model of colitis induced by transfer of CD4

Obesity is associated with increased severity of acute pancreatitis (AP). The cytokines IL-18 and IL-12 are elevated in patients with AP, and IL-18 levels are high in obesity. We aimed to develop a pathologically relevant model to study obesity-associated severe AP. Lean WT and obese leptin-deficient ob/ob mice received two injections of IL-12 plus IL-18. Survival, pancreatic inflammation, and biochemical markers of AP were measured. Dosing with IL-12 plus IL-18 induced 100% lethality in ob/ob mice; no lethality was observed in WT mice. Disruption of pancreatic exocrine tissue and acinar cell death as well as serum amylase and lipase levels were significantly higher in ob/ob than in WT mice. Edematous AP developed in WT mice, whereas obese ob/ob mice developed necrotizing AP. Adipose tissue necrosis and saponification were present in cytokine-injected ob/ob but not in WT mice. Severe hypocalcemia and elevated acute-phase response developed in ob/ob mice. The cytokine combination induced high levels of regenerating protein 1 and pancreatitis-associated protein expression in the pancreas of WT but not of ob/ob mice. To differentiate the contribution of obesity to that of leptin deficiency, mice received short-and long-term leptin replacement therapy. Shortterm leptin reconstitution in the absence of major weight loss did not protect ob/ob mice, whereas leptin deficiency in the absence of obesity resulted in a significant reduction in the severity of the pancreatitis. In conclusion, we developed a pathologically relevant model of AP in which obesity per se is associated with increased severity.cytokines ͉ inflammation ͉ obesity ͉ pancreas A cute pancreatitis (AP) is an inflammatory disorder that ranges from interstitial edema to confluent necrosis and hemorrhage. In severe cases, progress to circulatory shock, acute lung injury, renal failure, and eventual death may occur (1). Despite some controversy, numerous studies have demonstrated that obesity is associated with increased risk of the severe form of AP and with development of life-threatening complications (2-8). However, the mechanism by which increased adiposity worsens AP remains unknown.Leptin, a protein mainly produced by adipocytes, is a critical regulator of appetite (9). Leptin exerts important regulatory effects on inflammation (10). In the context of AP, the role of leptin remains controversial. In patients with AP, a correlation between serum leptin and disease severity has been reported by some investigators but not by others (11,12). Although in animal models administration of leptin decreases AP severity (13-16), more severe disease is present in leptin-deficient ob/ob and leptin receptordeficient db/db mice as well as leptin-receptor mutant fa/fa rats (17, 18). However, the differential effect of obesity versus leptin deficiency has not been fully investigated.IL-12 and IL-18 are two proinflammatory cytokines that drive the Th1 cell response, characterized by high levels of IFN-␥ (19). Both cytokines are mainly produced by monocytes/macrophages....

Concanavalin A-induced hepatotoxicity was compared in lipodystrophic aP2-nSREBP-1c transgenic mice (LD mice) lacking adipose tissue, obese leptin-deficient ob/ob mice, and lean wild-type (WT) mice. Serum leptin and adiponectin were low in LD mice, whereas ob/ob mice had undetectable leptin, but high adiponectin. Protection from hepatotoxicity was observed in ob/ob, but not in LD mice, despite low cytokine levels and reduced T cell activation and hepatic natural killer T cells in both groups. Administration of adiponectin protected LD mice from hepatotoxicity without altering cytokine levels. In contrast, administration of leptin heightened disease susceptibility by restoring cytokine production. Neutralization of TNF alpha protected LD mice from liver damage. Increased in vivo susceptibility to the hepatotoxic effect of TNF alpha was observed in LD mice. In vitro, adiponectin protected primary hepatocytes from TNF alpha-induced death, whereas leptin had no protective effect. In conclusion, although leptin increases susceptibility to hepatotoxicity by regulating cytokine production and T cell activation, adiponectin protects hepatocytes from TNF alpha-induced death.

Interleukin (IL)-18 binding protein (IL-18BP) is a natural inhibitor of the pleiotropic cytokine IL-18. To study the role of IL-18BP in modulating inflammatory responses in vivo, mice transgenic for human IL-18BP isoform a (IL-18BP-Tg) were generated. The transgene was expressed at high levels in each organ examined. High levels of bioactive human IL-18BPa were detectable in the circulation of IL-18BP-Tg mice, which were viable, fertile, and had no tissue or organ abnormality. The high levels of IL-18BP in the transgenic mice were able to completely neutralize the interferon-gamma (IFN-gamma)-inducing activity of exogenously administered IL-18. Following administration of endotoxin, with or without prior sensitization with heat-inactivated Propionibacterium acnes, IL-18BP-Tg mice produced significantly lower serum levels of IFN-gamma and macrophage-inflammatory protein-2 compared with nontransgenic littermates. Significantly reduced production of IFN-gamma in response to endotoxin was also observed in cultures of IL-18BP-Tg splenocytes. Finally, IL-18BP-Tg mice were completely protected in a model of hepatotoxicity induced by administration of concanavalin A. These results indicate that high endogenous levels of IL-18BP in trangenic mice effectively neutralize IL-18 and are protective in response to different inflammatory stimuli.