Geri Brown

Second infections independently increase mortality in hospitalized patients With cirrhosis: the north american consortium for the study of end‐stage liver disease (NACSELD) experience

Bacterial infections are an important cause of mortality in cirrhosis, but there is a paucity of multicenter studies. The aim was to define factors predisposing to infection‐related mortality in hospitalized patients with cirrhosis. A prospective, cohort study of patients with cirrhosis with infections was performed at eight North American tertiary‐care hepatology centers. Data were collected on admission vitals, disease severity (model for endstage liver disease [MELD] and sequential organ failure [SOFA] scores), first infection site, type (community‐acquired, healthcare‐associated [HCA] or nosocomial), and second infection occurrence during hospitalization. The outcome was mortality within 30 days. A multivariate logistic regression model predicting mortality was created. 207 patients (55 years, 60% men, MELD 20) were included. Most first infections were HCA (71%), then nosocomial (15%) and community‐acquired (14%). Urinary tract infections (52%), spontaneous bacterial peritonitis (SBP, 23%) and spontaneous bacteremia (21%) formed the majority of the first infections. Second infections were seen in 50 (24%) patients and were largely preventable: respiratory, including aspiration (28%), urinary, including catheter‐related (26%), fungal (14%), and Clostridium difficile (12%) infections. Forty‐nine patients (23.6%) who died within 30 days had higher admission MELD (25 versus 18, P < 0.0001), lower serum albumin (2.4 g/dL versus 2.8 g/dL, P = 0.002), and second infections (49% versus 16%, P < 0.0001) but equivalent SOFA scores (9.2 versus 9.9, P = 0.86). The case fatality rate was highest for C. difficile (40%), respiratory (37.5%), and spontaneous bacteremia (37%), and lowest for SBP (17%) and urinary infections (15%). The model for mortality included admission MELD (odds ratio [OR]: 1.12), heart rate (OR: 1.03) albumin (OR: 0.5), and second infection (OR: 4.42) as significant variables. Conclusion: Potentially preventable second infections are predictors of mortality independent of liver disease severity in this multicenter cirrhosis cohort. (HEPATOLOGY 2012;56:2328–2335)

Bone marrow progenitor cells contribute to esophageal regeneration and metaplasia in a rat model of Barrett's esophagus

Barretts esophagus develops when refluxed gastric juice injures the esophageal squamous lining and the injury heals through a metaplastic process in which intestinal-type columnar cells replace squamous ones. The progenitor cell that gives rise to Barretts metaplasia is not known, nor is it known why the condition is predisposed to malignancy. We studied the contribution of bone marrow stem cells to the development of Barretts esophagus in an animal model. Twenty female rats were given a lethal dose of irradiation followed by tail vein injection of bone marrow cells from male rats. Ten days later, the female rats were randomly assigned to undergo either esophagojejunostomy, a procedure that causes reflux esophagitis with intestinal metaplasia, or a sham operation. The rats were killed at 8 weeks and serial sections of the snap-frozen esophagi were cut and mounted on slides. The first and last sections were used for histological evaluation and the intervening sections were immunostained for cytokeratin to identify epithelial cells and analyzed for Y chromosome by fluorescence in situ hybridization (FISH). Histological evaluation of the esophagi from rats that had esophagojejunostomy revealed ulcerative esophagitis and multiple areas of intestinal metaplasia. FISH analyses showed that some of the squamous epithelial cells and some of the columnar epithelial cells lining the glands of the intestinal metaplasia were positive for Y chromosome. These observations suggest that multi-potential progenitor cells of bone marrow origin contribute to esophageal regeneration and metaplasia in this rat model of Barretts esophagus.

Tumor necrosis factor inhibitor ameliorates murine intestinal graft-versus-host disease☆☆☆

BACKGROUND & AIMS Transfer of T helper cells from DBA/2 mice to irradiated allogeneic B6D2F1 mice leads to development of colonic graft-versus-host disease with pathological features of inflammatory bowel disease. To examine the role of tumor necrosis factor (TNF) in graft-versus-host disease enteropathy, an adenoviral vector encoding a TNF inhibitor protein was administered. METHODS Irradiated B6D2F1 mice were infused with DBA/2 bone marrow and spleen cells. Mice then received either a control beta-galactosidase-encoding adenovirus or an adenovirus encoding a TNF inhibitor, composed of the extracellular domain of the human 55-kilodalton TNF receptor linked to the murine immunoglobulin G1 heavy chain. Mucosal permeability to sucralose and colonic histology were assessed 14 and 25 days after transplantation. RESULTS Less diarrhea was observed in DBA/2 --> B6D2F1 mice expressing the TNF inhibitor, and colonic sections from these mice had significantly less inflammation and epithelial cell abnormalities. In TNF inhibitor recipients, mucosal permeability to sucralose was similar to that in nonirradiated control mice and significantly less than in recipients of the control adenovirus. CONCLUSIONS TNF inhibition decreases the severity of enteropathy in the DBA/2 --> B6D2F1 murine model of colonic graft-versus-host disease.

Infection caused by Francisella philomiragia (formerly Yersinia philomiragia). A newly recognized human pathogen

We evaluated the clinical characteristics of patients with Francisella philomiragia (formerly Yersinia philomiragia) isolated from normally sterile sites. Isolates from 14 patients were received by the Centers for Disease Control between 1975 and 1987: 9 were from blood; 2 from lung biopsies; and 1 each from pleural, peritoneal, and cerebrospinal fluid. Underlying problems included chronic granulomatous disease in 5 patients, near-drowning in 5, and a myeloproliferative disease in 2. All 13 patients for whom records were available had a febrile syndrome compatible with bacterial infection. Pneumonia and fever-bacteremia were the commonest clinical syndromes reported. In 7 cases, F. philomiragia was the only sterile-site isolate, and the clinical syndrome did not resolve without appropriate antibiotics. Familiarity with this organism is important because of its ability to cause serious disease in chronic granulomatous disease and near-drowning patients. Further study may yield new insights into pathogenic and host defense mechanisms.

Virally Infected Hepatocytes Are Resistant to Perforin-Dependent CTL Effector Mechanisms

Cell-mediated cytotoxicity plays an important role in the clearance of noncytopathic viruses from infected tissues. Perforin-dependent cytotoxic mechanisms have been noted to play an important role in the clearance of infections from multiple extrahepatic organs. In contrast, mice with defects in the Fas/Fas ligand (FasL)-mediated cytotoxicity pathway exhibit delayed clearance of adenovirus from the liver without apparent delay in the clearance of viral infections from extrahepatic organs. The present studies examined the role of cytotoxic effector mechanisms in intrahepatic immune responses to a replication-defective, recombinant β-galactosidase-encoding adenovirus (AdCMV-lacZ). Delayed clearance of AdCMV-lacZ from the livers of FasL-defective B6.gld mice, but not perforin-deficient B6.pfp−/− mice, was noted despite no significant differences in initial hepatic CD8+ T cell IFN-γ or TNF responses or in activation of intrahepatic cytotoxic lymphocytes cells capable of killing AdCMV-lacZ-infected fibroblast targets. In contrast, AdCMV-lacZ-infected hepatocyte targets were far more sensitive to killing by intrahepatic cytotoxic lymphocytes from B6.pfp−/− than from B6.gld mice, and residual levels of virus-specific killing of hepatocyte targets by FasL-defective B6.gld CTL were blocked by TNF inhibition. These results suggest that inherent resistance of hepatocytes to cytotoxicity mediated by perforin-dependent mechanisms leaves Fas/FasL-dependent, cell-mediated cytotoxicity as the major pathway for CTL-mediated killing of virally infected hepatocytes and accounts for the more prominent role of perforin-independent anti-viral mechanisms in immune responses in the liver.

TNF-TNFR2 Interactions Are Critical for the Development of Intestinal Graft-Versus-Host Disease in MHC Class II-Disparate (C57BL/6J→C57BL/6J × bm12)F1 Mice

TNF-TNFR2 interactions promote MHC class II-stimulated alloresponses while TNF-TNFR1 interactions promote MHC class I-stimulated alloresponses. The present studies were designed to evaluate whether TNF-TNFR2 interactions were involved in the in vivo generation of CD4+ T cell-mediated intestinal graft-versus-host disease (GVHD) in the (C57BL/6J (hereafter called B6)→B6 × B6.C-H-2bm12 (bm12))F1 GVHD model. Briefly, 5 × 106 splenic CD4+ T lymphocytes from B6.TNFR2−/− or control B6 mice were transferred with 1–2 × 106 T cell-depleted B6 bone marrow cells (BMC) to irradiated MHC class II-disparate (bm12 × B6)F1 mice. Weight loss, intestinal inflammation, and the surface expression of CD45RB (memory marker) on intestinal and splenic lymphocytes were assessed. IL-2 and IFN-α mRNA levels in intestinal lymphocytes were assessed by nuclease protection assays. A significant reduction in weight loss and intestinal inflammation was observed in recipients of the TNFR2−/−CD4+ SpC. Similarly, a significant decrease was noted in T cell numbers and in CD45RBlow (activated/memory) expression on intestinal but not CD4+ T cells in recipients of TNFR2−/−CD4+ spleen cells. IL-2 and IFN-α mRNA levels were reduced in the intestine in the recipients of TNFR2−/− splenic CD4+ T cells. These results indicate that TNF-TNFR2 interactions are important for the development of intestinal inflammation and activation/differentiation of Th1 cytokine responses by intestinal lymphocytes in MHC class II-disparate GVHD while playing an insignificant role in donor T cell activation in the spleen.

The role of TNF-TNFR2 interactions in generation of CTL responses and clearance of hepatic adenovirus infection

Deficiency or inhibition of tumor necrosis factor (TNF) significantly prolongs hepatic expression of recombinant adenoviral vectors. To explore mechanisms responsible for this observation, the present studies examined the effects of TNF versus TNF receptor 1 (TNFR1) or TNFR2 deficiency on the course of antiviral‐immune responses to a replication‐deficient, β‐galactosidase‐encoding recombinant adenovirus (AdCMV‐lacZ). Clearance of AdCMV‐lacZ was significantly delayed in TNF‐deficient mice. Less pronounced but significant delays in AdCMV‐lacZ clearance were observed in TNFR2‐deficient but not TNFR1‐deficient mice. Numbers of interferon‐γ expressing intrahepatic lymphocytes (IHL) were similar in AdCMV‐lacZ‐infected, TNF‐deficient, TNFR1‐deficient, TNFR2‐deficient, and control mice. However, IHL isolated from AdCMV‐lacZ‐infected, TNF‐deficient or AdCMV‐lacZ‐infected, TNFR2‐deficient mice exhibited decreased levels of FasL expression and adenovirus‐specific cytolytic T lymphocyte (CTL) activity. Similar defects in allo‐specific killing of Fas‐sensitive hepatocyte targets by TNF‐deficient or TNFR2‐deficient but not TNFR1‐deficient CTL were also noted. No defects in generation of allo‐specific cytotoxicity directed against perforin‐sensitive target cells were noted in TNF‐, TNFR1‐, or TNFR2‐deficient lymphocytes. These findings indicate that TNF/TNFR2 interactions facilitate generation of FasL‐dependent CTL effector pathways that play an important role in in vivo antiviral‐immune responses in the liver.

Adenoviral Vectors Given Intravenously to Immunocompromised Mice Yield Stable Transduction of the Colonic Epithelium

BACKGROUND & AIMS Adenoviral vectors have been used for gene transfer in the liver but not for gene transfer in intestinal tissue. The aim of this study was to show that in selectively immunocompromised mice injected intravenously with a recombinant adenovirus, higher levels of a reporter gene are expressed in the colon than in the liver. METHODS Adenovirus encoding beta-galactosidase was injected intravenously in lethally irradiated B6D2F1 mice that had received syngeneic B6D2F1 bone marrow and spleen cell transplants, in athymic mice, in mice treated with 2-chlorodeoxyadenosine, or in normal mice. Enzymatic assays and polymerase chain reaction analysis were performed on colonic tissue obtained months after transduction. Colonic tissues were also stained for beta-galactosidase. RESULTS Intravenous adenoviral administration yielded long-term expression of a foreign gene in liver and colonic epithelium in transiently immunocompromised recipients. Histological analysis suggested that stem cell transfection and integration of the foreign gene may have occurred insofar as crypts and colonic epithelial cells in immunocompromised animals stained positive for beta-galactosidase months after virus administration. In polymerase chain reaction analysis, the transverse and distal colon of syngeneic bone marrow transplant recipients showed long-term retention of beta-galactosidase gene. CONCLUSIONS Long-term transduction of colonic epithelial cells is observed after administration of adenoviral vectors by an intravenous route in selectively immunocompromised mice.

Lipid abnormalities in HIV/hepatitis C virus-coinfected patients

Among HIV‐infected patients, hepatitis C virus (HCV) coinfection is associated with increased rates of lipodystrophy and insulin resistance. Its impact on HIV‐associated dyslipidaemia is less clear.

IL-12-Independent LIGHT Signaling Enhances MHC Class II Disparate CD4+ T Cell Alloproliferation, IFN-γ Responses, and Intestinal Graft-versus-Host Disease

Inhibition of LIGHT (a cellular ligand for herpes virus entry mediator and lymphotoxin receptor)/herpes simplex virus entry mediator (HVEM) and LIGHT/lymphotoxin β receptor (LTβR) interactions decreases mortality in MHC class I and II disparate graft-vs-host disease (GVHD). The present studies assessed the effects of these interactions on the generation of CD4+ T cell alloresponses in MHC class II-disparate MLC and GVHD. An inhibitor protein of LIGHT and LTαβ2 (LTβR-Ig) and an inhibitor protein of LIGHT (HVEM-Ig) caused similar decreases in alloresponses of control B6 or B6.129S1-IL12rb2tm1Jm (B6.IL12R−/−) spleen cells (SpC) in a MHC class II-disparate MLC. GVHD-induced wasting disease in MHC class II-disparate recipients of B6 CD4+ SpC who received either the LTβR-Ig-encoding adenovirus (LTβR-Ig Adv; 13.1 ± 10.9%; n = 10; p = 0.0004) or the HVEM-Ig-encoding adenovirus (HVEM-Ig Adv; 16.4 ± 9.9%; n = 13; p = 0.0008) was significantly reduced compared with that in recipients of a control adenovirus (30.4 ± 8.8%; n = 13). Furthermore, gut GVHD histologic scores of recipients of B6 CD4+ SpC who received the LTβR-Ig Adv (0.8 ± 0.8; n = 5; p = 0.0007) or the HVEM-Ig Adv (1.4 ± 0.5; n = 5; p = 0.008) were reduced compared with scores of recipients of a control adenovirus (2.5 ± 0.75; n = 11). In the intestine, both LTβR-Ig Adv and HVEM-Ig Adv decreased CD4+ T cells (0.35 ± 0.4 × 106 (n = 6) vs 0.36 ± 0.02 × 106 (n = 9); p = 0.03 and p = 0.007) compared with control adenovirus (0.86 ± 0.42 × 106; n = 9). LIGHT is critical for optimal CD4+ T cell alloresponses in MHC class II-disparate MLC and GVHD.