In mammals, several well-defined metabolic changes occur during infection, many of which are attributable to products of the reticuloendothelial system. Among these changes, a hypertriglyceridaemic state is frequently evident, resulting from defective triglyceride clearance, caused by systemic suppression of the enzyme lipoprotein lipase (LPL). We have found previously that macrophages secrete the hormone cachectin, which specifically suppresses LPL activity in cultured adipocytes (3T3-L1 cells). When originally purified from RAW 264.7 (mouse macrophage) cells, cachectin was shown to have a pI of 4.7, a subunit size of relative molecular mass (Mr) 17,000 and to form non-covalent multimers. A receptor for cachectin was identified on non-tumorigenic cultured cells and on normal mouse liver membranes. A new high-yield purification technique has enabled us to determine further details of the structure of mouse cachectin. We now report that a high degree of homology exists between the N-terminal sequence of mouse cachectin and the N-terminal sequence recently determined for human tumour necrosis factor (TNF). Purified cachectin also possesses potent TNF activity in vitro. These findings suggest that the 'cachectin' and 'TNF' activities of murine macrophage conditioned medium are attributable to a single protein, which modulates the metabolic activities of normal as well as neoplastic cells through interaction with specific high-affinity receptors.

Frontiers in Immunology | www.frontiersin.org absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Background/Aims Drug-induced and indeterminate Acute Liver Failure (ALF) might be due to an autoimmune-like hepatitis that is responsive to corticosteroid therapy. The aim of this study was to evaluate whether corticosteroids improve survival in fulminant autoimmune hepatitis, drug-induced or indeterminate ALF, and whether this benefit varies according to the severity of illness. Methods We conducted a retrospective analysis of autoimmune, indeterminate and drug-induced ALF patients in the Acute Liver Failure Study Group from 1998-2007. The primary endpoints were overall and spontaneous survival (SS, survival without transplant). Results 361 ALF patients were studied, 66 with autoimmune (25 steroids, 41 no steroids), 164 with indeterminate (21 steroids, 143 no steroids), and 131 with drug-induced (16 steroids, 115 no steroids) ALF. Steroid use was not associated with improved overall survival (61% vs. 66%, p=0.41), nor with improved survival in any diagnosis category. Steroid use was associated with diminished survival in certain subgroups of patients, including those with the highest quartile of MELD (MELD > 40, survival 30% vs. 57%, p=0.03). In multivariable analysis controlling for steroid use and diagnosis, age (OR 1.37 per decade), coma grade (OR 2.02 grade 2, 2.65 grade 3, 5.29 grade 4), MELD (OR 1.07) and pH<7.4 (OR 3.09) were significantly associated with mortality. Though steroid use was associated with a marginal benefit in SS overall (35% v. 23%, p=0.047), this benefit did not persistent in multivariable analysis; mechanical ventilation (OR 0.24), MELD (OR 0.93), and ALT (1.02) were the only significant predictors of SS. Conclusions Corticosteroids did not improve overall survival or SS in drug-induced, indeterminate or autoimmune ALF and were associated with lower survival in patients with the highest MELD scores.

Background 30-day readmissions for hospitalized patients with cirrhosis are common, particularly for patients with hepatic encephalopathy (HE). Methods We performed a prospective pre-post study from 2010–2013 to assess the impact of a quality improvement (QI) protocol on 30-day readmissions to a transplant center’s liver unit. The intervention included a yearlong control period, a handheld checklist and an “electronic” phase incorporating checklist items into the electronic provider order entry system. The intervention included goal-directed lactulose therapy and universal rifaximin for overt HE as well as prompts for antibiotic prophylaxis of spontaneous bacterial peritonitis (SBP). 30-day readmission trends were compared to non-cirrhotic patients admitted to hospitalists and patients with decompensated cirrhosis at another center. Results 824 patients were admitted 1720 times. The average model for end-stage liver disease score on admission was 17.7 ± 7.4. The electronic phase was associated with 40% lower adjusted odds of 30-day readmission compared to control, both overall and for patients with HE. The proportion of admissions for ≥ grade 2 HE that resulted in a readmission fell from 48.9% (66/135) in the control period to 26.0% (27/104) in the electronic phase (p = 0.0003). Rifaximin use for HE and antibiotic secondary prophylaxis of SBP (on discharge) were associated with lower adjusted odds of readmission (respective OR 0.39 and 0.40). The electronic phase was associated with a lower length of stay (beta coefficient −1.34 95% CI: −2.38 – −0.32, p = 0.01). Conclusion A QI initiative using electronic decision support reduced 30-day readmissions for patients with cirrhosis.

The goals of this study were to characterize the changes to chondroitin sulfate proteoglycans and hyaluronan in lungs in the acute response to gram-negative bacterial infection, and to identify cellular components responsible for these changes. Mice were treated with intratracheal (IT) live Escherichia coli, E. coli lipopolysaccharide (LPS), or PBS. Both E. coli and LPS caused rapid selective increases in mRNA expression of versican and hyaluronan synthase (Has) isoforms 1 and 2 associated with increased immunohistochemical and histochemical staining for versican and hyaluronan in the lungs. Versican was associated with a subset of alveolar macrophages. To examine whether macrophages contribute to versican and hyaluronan accumulation, in vitro studies with primary cultures of bone marrow-derived and alveolar macrophages were performed. Unstimulated macrophages expressed very low levels of versican and hyaluronan synthase mRNA, with no detectible versican protein or hyaluronan product. Stimulation with LPS caused rapid increases in versican mRNA and protein, a rapid increase in Has1 mRNA, and concomitant inhibition of hyaluronidases 1 and 2, the major hyaluronan degrading enzymes. Hyaluronan could be detected following chloroquine pre-treatment, indicating rapid turnover and degradation of hyaluronan by macrophages. In addition, the effects of LPS, the M1 macrophage classical activation agonist, were compared to those of IL-4/IL-13 or IL-10, the M2a and M2c alternative activation agonists, respectively. Versican and Has1 increased only in response to M1 activation. Finally, the up-regulation of versican and Has1 in the whole lungs of wild-type mice following IT LPS was completely abrogated in TLR-4−/− mice. These findings suggest that versican and hyaluronan synthesis may play an important role in the innate immune response to gram-negative lung infection.

Growing evidence suggests that versican is important in the innate immune response to lung infection. Our goal was to understand the regulation of macrophage-derived versican and the role it plays in innate immunity. We first defined the signaling events that regulate versican expression, using bone marrow-derived macrophages (BMDMs) from mice lacking specific Toll-like receptors (TLRs), TLR adaptor molecules, or the type I interferon receptor (IFNAR1). We show that LPS and polyinosinic-polycytidylic acid [poly(I:C)] trigger a signaling cascade involving TLR3 or TLR4, the Trif adaptor, type I interferons, and IFNAR1, leading to increased expression of versican by macrophages and implicating versican as an interferon-stimulated gene. The signaling events regulating versican are distinct from those for hyaluronan synthase 1 (HAS1) and syndecan-4 in macrophages. HAS1 expression requires TLR2 and MyD88. Syndecan-4 requires TLR2, TLR3, or TLR4 and both MyD88 and Trif. Neither HAS1 nor syndecan-4 is dependent on type I interferons. The importance of macrophage-derived versican in lungs was determined with LysM/ mice. These studies show increased recovery of inflammatory cells in the bronchoalveolar lavage fluid of poly(I:C)-treated LysM/ mice compared with control mice. IFN-β and IL-10, two important anti-inflammatory molecules, are significantly decreased in both poly(I:C)-treated BMDMs from LysM/ mice and bronchoalveolar lavage fluid from poly(I:C)-treated LysM/ mice compared with control mice. In short, type I interferon signaling regulates versican expression, and versican is necessary for type I interferon production. These findings suggest that macrophage-derived versican is an immunomodulatory molecule with anti-inflammatory properties in acute pulmonary inflammation.

Edited by Gerald W. HartViral infection is an exacerbating factor contributing to chronic airway diseases, such as asthma, via mechanisms that are still unclear. Polyinosine-polycytidylic acid (poly(I:C)), a Toll-like receptor 3 (TLR3) agonist used as a mimetic to study viral infection, has been shown to elicit inflammatory responses in lungs and to exacerbate pulmonary allergic reactions in animal models. Previously, we have shown that poly(I:C) stimulates lung fibroblasts to accumulate an extracellular matrix (ECM), enriched in hyaluronan (HA) and its binding partner versican, which promotes monocyte adhesion. In the current study, we aimed to determine the in vivo role of versican in mediating inflammatory responses in poly(I:C)-induced lung inflammation using a tamoxifen-inducible versican-deficient mouse model (Vcan ؊/؊ mice). In C57Bl/6 mice, poly(I:C) instillation significantly increased accumulation of versican and HA, especially in the perivascular and peribronchial regions, which were enriched in infiltrating leukocytes. In contrast, versican-deficient (Vcan ؊/؊ ) lungs did not exhibit increases in versican or HA in these regions and had strikingly reduced numbers of leukocytes in the bronchoalveolar lavage fluid and lower expression of inflammatory chemokines and cytokines. Poly(I:C) stimulation of lung fibroblasts isolated from control mice generated HA-enriched cable structures in the ECM, providing a substrate for monocytic cells in vitro, whereas lung fibroblasts from Vcan ؊/؊ mice did not. Moreover, increases in proinflammatory cytokine expression were also greatly attenuated in the Vcan ؊/؊ lung fibroblasts. These findings provide strong evidence that versican is a critical inflammatory mediator during poly(I:C)-induced acute lung injury and, in association with HA, generates an ECM that promotes leukocyte infiltration and adhesion.

No abstract