Resident enteric bacteria are necessary for development of spontaneous colitis and immune system activation in interleukin-10-deficient mice

Mice with targeted deletion of the gene for interleukin-10 (IL-10) spontaneously develop enterocolitis when maintained in conventional conditions but develop only colitis when kept in specific-pathogen-free (SPF) environments. This study tested the hypothesis that enteric bacteria are necessary for the development of spontaneous colitis and immune system activation in IL-10-deficient mice. IL-10-deficient mice were maintained in either SPF conditions or germfree conditions or were populated with bacteria known to cause colitis in other rodent models. IL-10-deficient mice kept in SPF conditions developed colitis in all segments of the colon (cecum and proximal and distal colon). These mice exhibited immune system activation as evidenced by increased expression of CD44 on CD4(+) T cells; increased mesenteric lymph node cell numbers; and increased production of immunoglobulin A (IgA), IgG1, and IL-12 p40 from colon fragment cultures. Mice populated with bacterial strains, including Bacteroides vulgatus, known to induce colitis in other rodent models had minimal colitis. Germfree IL-10-deficient mice had no evidence of colitis or immune system activation. We conclude therefore that resident enteric bacteria are necessary for the development of spontaneous colitis and immune system activation in IL-10-deficient mice.

Partial Oral versus Intravenous Antibiotic Treatment of Endocarditis

BACKGROUND

Patients with infective endocarditis on the left side of the heart are typically treated with intravenous antibiotic agents for up to 6 weeks. Whether a shift from intravenous to oral antibiotics once the patient is in stable condition would result in efficacy and safety similar to those with continued intravenous treatment is unknown.

METHODS

In a randomized, noninferiority, multicenter trial, we assigned 400 adults in stable condition who had endocarditis on the left side of the heart caused by streptococcus, Enterococcus faecalis, Staphylococcus aureus, or coagulase-negative staphylococci and who were being treated with intravenous antibiotics to continue intravenous treatment (199 patients) or to switch to oral antibiotic treatment (201 patients). In all patients, antibiotic treatment was administered intravenously for at least 10 days. If feasible, patients in the orally treated group were discharged to outpatient treatment. The primary outcome was a composite of all-cause mortality, unplanned cardiac surgery, embolic events, or relapse of bacteremia with the primary pathogen, from the time of randomization until 6 months after antibiotic treatment was completed.

RESULTS

After randomization, antibiotic treatment was completed after a median of 19 days (interquartile range, 14 to 25) in the intravenously treated group and 17 days (interquartile range, 14 to 25) in the orally treated group (P=0.48). The primary composite outcome occurred in 24 patients (12.1%) in the intravenously treated group and in 18 (9.0%) in the orally treated group (between-group difference, 3.1 percentage points; 95% confidence interval, -3.4 to 9.6; P=0.40), which met noninferiority criteria.

CONCLUSIONS

In patients with endocarditis on the left side of the heart who were in stable condition, changing to oral antibiotic treatment was noninferior to continued intravenous antibiotic treatment. (Funded by the Danish Heart Foundation and others; POET ClinicalTrials.gov number, NCT01375257 .).

Spontaneous regression of lymphoproliferative disorders in patients treated with methotrexate for rheumatoid arthritis and other rheumatic diseases

PURPOSE

To determine the clinicopathologic features of lymphoproliferative disorders (LPD) that occur in the setting of methotrexate (MTX) therapy for rheumatic diseases (RD) and to define the relationship between the presence of Epstein-Barr virus (EBV) in tumor cells and the response of LPD to MTX withdrawal.

PATIENTS AND METHODS

In addition to nine new cases, we analyzed 28 cases previously reported in the literature of LPD in patients receiving MTX for RD. In addition to MTX, immunosuppressive therapy included corticosteroids in 19 patients, azathioprine in three, and cyclosporine in one. Extranodal disease was identified in 16 patients, but none had CNS involvement. Pathologic findings included five cases of Hodgkin's disease and seven low-grade lymphomas. The remaining patients had intermediate or aggressive lymphomas. In situ hybridization studies (ISHS) for EBV-RNA transcripts were positive in 12 of 27 patients (44%).

RESULTS

Among 37 patients, 16 were initially observed after MTX withdrawal without additional antitumor therapy. Six achieved a spontaneous complete remission (CR), three had a partial response (PR), one had a minimal response, and six had no response to MTX withdrawal. Of 10 responding patients, EBV was detected by ISHS (n = 6) or polymerase chain reaction (PCR) (n = 2); one patient had a CR despite the absence of EBV by PCR and one had a CR but did not have viral assays performed. Only one of six patients with negative EBV by ISHS or PCR responded to MTX withdrawal.

CONCLUSION

MTX withdrawal and observation for a short period should be considered in the initial management of patients who develop LPD while on MTX therapy. Responses were consistently observed, but not limited to patients in whom EBV was detected by ISHS or PCR. Further studies are required to confirm these findings and to evaluate the role for EBV in LPD that occur in patients receiving MTX.

Different subsets of enteric bacteria induce and perpetuate experimental colitis in rats and mice

Resident bacteria are incriminated in the pathogenesis of experimental colitis and inflammatory bowel diseases. We investigated the relative roles of various enteric bacteria populations in the induction and perpetuation of experimental colitis. HLA-B27 transgenic rats received antibiotics (ciprofloxacin, metronidazole, or vancomycin-imipenem) in drinking water or water alone in either prevention or treatment protocols. Mice were treated similarly with metronidazole or vancomycin-imipenem before or after receiving 5% dextran sodium sulfate (DSS). Germfree transgenic rats were colonized with specific-pathogen-free enteric bacteria grown overnight either in anaerobic or aerobic atmospheres. Nontransgenic rats colonized with anaerobic bacteria served as negative controls. Although preventive metronidazole significantly attenuated colitis in transgenic rats and DSS-treated mice, it had no therapeutic benefit once colitis was established. Ciprofloxacin also partially prevented but did not treat colitis in B27 transgenic rats. In both animal models vancomycin-imipenem most effectively prevented and treated colitis. Germfree transgenic rats reconstituted with enteric bacteria grown under anaerobic conditions had more aggressive colitis than those associated with aerobic bacteria. These results suggest that a subset of resident luminal bacteria induces colitis, but that a complex interaction of commensal aerobic and anaerobic bacteria provides the constant antigenic drive for chronic immune-mediated colonic inflammation.

Exercise-induced hypertension, cardiovascular events, and mortality in patients undergoing exercise stress testing: a systematic review and meta-analysis

BACKGROUND

The prognostic relevance of a hypertensive response to exercise (HRE) is ill-defined in individuals undergoing exercise stress testing. The study described here was intended to provide a systematic review and meta-analysis of published literature to determine the value of exercise-related blood pressure (BP) (independent of office BP) for predicting cardiovascular (CV) events and mortality.

METHODS

Online databases were searched for published longitudinal studies reporting exercise-related BP and CV events and mortality rates.

RESULTS

We identified for review 12 longitudinal studies with a total of 46,314 individuals without significant coronary artery disease, with total CV event and mortality rates recorded over a mean follow-up of 15.2±4.0 years. After adjustment for age, office BP, and CV risk factors, an HRE at moderate exercise intensity carried a 36% greater rate of CV events and mortality (95% CI, 1.02-1.83, P = 0.039) than that of subjects without an HRE. Additionally, each 10mm Hg increase in systolic BP during exercise at moderate intensity was accompanied by a 4% increase in CV events and mortality, independent of office BP, age, or CV risk factors (95% CI, 1.01-1.07, P = 0.02). Systolic BP at maximal workload was not significantly associated with the outcome of an increased rate of CV, whether analyzed as a categorical (HR=1.49, 95% CI, 0.90-2.46, P = 0.12) or a continuous (HR=1.01, 95% CI, 0.98-1.04, P = 0.53) variable.

CONCLUSIONS

An HRE at moderate exercise intensity during exercise stress testing is an independent risk factor for CV events and mortality. This highlights the need to determine underlying pathophysiological mechanisms of exercise-induced hypertension.

Novel urinary metabolite of alpha-tocopherol, 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman, as an indicator of an adequate vitamin E supply?

Previously, the metabolism of alpha-tocopherol was considered to involve the opening of the chroman structure because of its oxidation to tocopherylquinone. In contrast, we describe here 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC) as the major urinary metabolite of alpha-tocopherol that appears in human urine after vitamin E supplementation. It is formed directly from alpha-tocopherol without previous oxidative splitting of the chroman ring. The correlation of alpha-tocopherol intake, plasma alpha-tocopherol concentrations, and urinary excretion of alpha-CEHC in human volunteers supplemented with RRR-alpha-tocopherol dosages ranging from 0 to 800 mg/d was examined. HPLC and gas chromatography-mass spectroscopy analysis revealed that alpha-CEHC was only excreted when a plasma threshold of 7-9 mumol alpha-tocopherol/g total lipid was exceeded. This concentration was obtained by a daily intake of approximately 50-150 mg alpha-tocopherol. We suggest that alpha-CEHC excretion indicates a saturated binding capacity of vitamin E in the plasma and thus may be considered to be a marker of optimum vitamin E intake.

Global air pollution crossroads over the Mediterranean

The Mediterranean Intensive Oxidant Study, performed in the summer of 2001, uncovered air pollution layers from the surface to an altitude of 15 kilometers. In the boundary layer, air pollution standards are exceeded throughout the region, caused by West and East European pollution from the north. Aerosol particles also reduce solar radiation penetration to the surface, which can suppress precipitation. In the middle troposphere, Asian and to a lesser extent North American pollution is transported from the west. Additional Asian pollution from the east, transported from the monsoon in the upper troposphere, crosses the Mediterranean tropopause, which pollutes the lower stratosphere at middle latitudes.

Experts' opinion on management of hemodynamics in ARDS patients: focus on the effects of mechanical ventilation

RATIONALE

Acute respiratory distress syndrome (ARDS) is frequently associated with hemodynamic instability which appears as the main factor associated with mortality. Shock is driven by pulmonary hypertension, deleterious effects of mechanical ventilation (MV) on right ventricular (RV) function, and associated-sepsis. Hemodynamic effects of ventilation are due to changes in pleural pressure (Ppl) and changes in transpulmonary pressure (TP). TP affects RV afterload, whereas changes in Ppl affect venous return. Tidal forces and positive end-expiratory pressure (PEEP) increase pulmonary vascular resistance (PVR) in direct proportion to their effects on mean airway pressure (mPaw). The acutely injured lung has a reduced capacity to accommodate flowing blood and increases of blood flow accentuate fluid filtration. The dynamics of vascular pressure may contribute to ventilator-induced injury (VILI). In order to optimize perfusion, improve gas exchange, and minimize VILI risk, monitoring hemodynamics is important.

RESULTS

During passive ventilation pulse pressure variations are a predictor of fluid responsiveness when conditions to ensure its validity are observed, but may also reflect afterload effects of MV. Central venous pressure can be helpful to monitor the response of RV function to treatment. Echocardiography is suitable to visualize the RV and to detect acute cor pulmonale (ACP), which occurs in 20-25 % of cases. Inserting a pulmonary artery catheter may be useful to measure/calculate pulmonary artery pressure, pulmonary and systemic vascular resistance, and cardiac output. These last two indexes may be misleading, however, in cases of West zones 2 or 1 and tricuspid regurgitation associated with RV dilatation. Transpulmonary thermodilution may be useful to evaluate extravascular lung water and the pulmonary vascular permeability index. To ensure adequate intravascular volume is the first goal of hemodynamic support in patients with shock. The benefit and risk balance of fluid expansion has to be carefully evaluated since it may improve systemic perfusion but also may decrease ventilator-free days, increase pulmonary edema, and promote RV failure. ACP can be prevented or treated by applying RV protective MV (low driving pressure, limited hypercapnia, PEEP adapted to lung recruitability) and by prone positioning. In cases of shock that do not respond to intravascular fluid administration, norepinephrine infusion and vasodilators inhalation may improve RV function. Extracorporeal membrane oxygenation (ECMO) has the potential to be the cause of, as well as a remedy for, hemodynamic problems. Continuous thermodilution-based and pulse contour analysis-based cardiac output monitoring are not recommended in patients treated with ECMO, since the results are frequently inaccurate. Extracorporeal CO2 removal, which could have the capability to reduce hypercapnia/acidosis-induced ACP, cannot currently be recommended because of the lack of sufficient data.

Targeted mutation of the murine goosecoid gene results in craniofacial defects and neonatal death

The goosecoid gene encodes a homeodomain-containing protein that has been identified in a number of species and has been implicated in a variety of key developmental processes. Initially suggested to be involved in organizing the embryo during early development, goosecoid has since been demonstrated to be expressed during organogenesis-most notably in the head, the limbs and the ventrolateral body wall. To investigate the role of goosecoid in embryonic development, we have inactivated the gene by gene targeting to generate mice mutant for the goosecoid gene. Mice that are homozygous for the goosecoid mutation do not display a gastrulation phenotype and are born; however, they do not survive more than 24 hours. Analysis of the homozygotes revealed numerous developmental defects affecting those structures in which goosecoid is expressed during its second (late) phase of embryonic expression. Predominantly, these defects involve the lower mandible and its associated musculature including the tongue, the nasal cavity and the nasal pits, as well as the components of the inner ear (malleus, tympanic ring) and the external auditory meatus. Although the observed phenotype is in accordance with the late expression domains of goosecoid in wild-type embryos, we suggest that the lack of an earlier phenotype is the result of functional compensation by other genes.

Evidence from opiate binding studies that heroin acts through its metabolites

The relative affinity to opiate receptors of heroin, 6-acetylmorphine and morphine was estimated by determining their ability to displace specifically bound 3H-naltrexone from rat brain opiate binding sites. In vitro hydrolysis of heroin to 6-acetylmorphine was monitored in the binding assay filtrate by use of a quantitative HPLC procedure. The rate of heroin hydrolysis was significantly slower at 0 degrees C than at 37 degrees C. The displacement of 1 nM 3H-naltrexone by unlabeled ligand at concentrations ranging from 7 to 500 nM was measured at 0 degrees C for 120 minutes, yielding IC50 values of heroin = 483 nM, 6-acetylmorphine = 73 nM and morphine = 53 nM. When the binding data for heroin were recalculated to include the displacement that could be attributed to the 6-acetylmorphine derived from heroin degradation during the incubation, all of the apparent heroin binding was accounted for by the 6-acetylmorphine. These results are consistent with previous reports of the low binding affinity of morphine congeners (e.g., codeine) that lack a free phenolic 3-hydroxyl group and support the view that heroin is a prodrug which serves to determine the distribution of its intrinsically active metabolites, 6-acetylmorphine and morphine.

A prospective, randomized, pragmatic, health outcomes trial evaluating the incorporation of hylan G-F 20 into the treatment paradigm for patients with knee osteoarthritis (Part 1 of 2): clinical results

OBJECTIVE

First, to assess the clinical effectiveness of hylan G-F 20 in an appropriate care treatment regimen (as defined by the American College of Rheumatology (ACR) 1995 guidelines) as measured by validated disease-specific outcomes and health-related quality of life endpoints for patients with osteoarthritis (OA) of the knee. Second, to utilize the measures of effectiveness and costs in an economic evaluation (see accompanying manuscript).

DESIGN

A total of 255 patients with OA of the knee were enrolled by rheumatologists or orthopedic surgeons into a prospective, randomized, open-label, 1-year, multi-centred trial, conducted in Canada. Patients were randomized to 'Appropriate care with hylan G-F 20' (AC+H) or 'Appropriate care without hylan G-F 20' (AC). Data were collected at clinic visits (baseline, 12 months) and by telephone (1, 2, 4, 6, 8, 10, and 12 months).

RESULTS

The AC+H group was superior to the AC group for all primary (% reduction in mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale: 38% vs 13%,P =0.0001) and secondary effectiveness outcome measures. These differences were all statistically significant and exceeded the 20% difference between groups set a priori by the investigators as the minimum clinically important difference. Health-related quality of life improvements in the AC+H group were statistically superior for the WOMAC pain, stiffness and physical function (all P< 0.0001), the SF-36 aggregate physical component (P< 0.0001) and the Health Utilities Index Mark 3 (HUI3) overall health utility score (P< 0.0001). Safety (adverse events and patient global assessments of side effects) differences favoured the AC+H group.

CONCLUSION

The data presented here indicate that the provision to patients with knee OA of viscosupplementation with hylan G-F 20 within an appropriate care treatment regimen provides benefits in the knee, overall health and health related quality of life at reduced levels of co-therapy and systemic adverse reactions.

The pharmacokinetics of heroin in patients with chronic pain

We measured blood concentrations of heroin and its active metabolites, 6-acetylmorphine and morphine, serially in 11 patients with chronic pain (9 of whom had cancer) after intravenous injection, intravenous infusion, intramuscular injection, and an oral dose of heroin hydrochloride. Parenteral heroin provided measureable blood levels of heroin, 6-acetylmorphine, and morphine. Blood levels of heroin and 6-acetylmorphine reached their maximal concentrations within minutes and were cleared rapidly. The mean half-life of heroin (+/- S.D.) after intravenous injection or infusion was only 3.0 +/- 1.3 minutes, and the mean clearance of heroin from the blood at apparent steady state was 30.8 +/- 2.1 ml per kilogram of body weight per minute. Morphine levels rose more gradually, and morphine was cleared much more slowly. Oral administration of heroin resulted in measurable blood levels of morphine but not of heroin or 6-acetylmorphine. The amount of circulating morphine provided by an oral dose of heroin was only 79 per cent of that available from an equal amount of morphine. We conclude that heroin is a pro-drug that serves to determine the distribution of its active metabolites. Parenteral heroin is rapidly converted to 6-acetylmorphine, which contributes to rapid pain relief. Oral heroin is converted to morphine and appears to be an inefficient means of providing morphine to the systemic circulation.

Interleukin-1-induced nuclear factor kappa B activation is inhibited by overexpression of phospholipid hydroperoxide glutathione peroxidase in a human endothelial cell line

Oxygen radicals are commonly accepted mediators in the tumour necrosis factor-mediated nuclear factor kappa B (NF kappa B) signalling cascade, but evidence for their role during interleukin-1 (IL-1) signalling is lacking. To test the involvement of hydroperoxides we investigated whether IL-1-induced NF kappa B activation could be influenced by glutathione peroxidases (GPx). These enzymes remove hydroperoxides with various specificities for the hydroperoxide substrate. By overexpressing phospholipid hydroperoxide glutathione peroxidase (PHGPx), which characteristically reacts with lipophilic hydroperoxides, the roles of H2O2 and lipid hydroperoxides were assessed. A human umbilical endothelial cell line, ECV 304, was stably transfected with the genes for both PHGPx and selenophosphate synthetase (selD), which provides selenophosphate for selenoprotein biosynthesis. When grown in selenium-deficient culture medium, the double-transfected clone (ECVPHGPx+SelD+) expressed 5-fold higher (P<0.005) PHGPx activity (measured by phosphatidylcholine hydroperoxide removal) than controls. The rate of H2O2 removal was also significantly (P<0.01) higher in this clone. When grown with high levels of extracellular selenium (up to 100 nM selenite), PHGPx activity and H2O2 removal were enhanced substantially in control cells and transfected cells. Under these conditions, PHGPx activity was 1.7-fold (P<0.005) higher in ECVPHGPx+SelD+, but H2O2 removal was the same as in controls. IL-1-induced NF kappa B activation was inhibited by selenium supplementation in control cells. In ECVPHGPx+SelD+ under conditions of selenium restriction, IL-1 induced NF kappa B activation only to a similar extent as under conditions of selenium supplementation in controls, and activation was abolished with 50 nM sodium selenite. These results show that overexpressed PHGPx is sufficient to inhibit NF kappa B activation, and suggests that NF kappa B activation by IL-1 is mediated by a preferential substrate of PHGPx, such as a fatty acid hydroperoxide, rather than by H2O2, the preferred substrate of the more abundant cytosolic GPx.

Air Pollution and Climate-Forcing Impacts of a Global Hydrogen Economy

If today's surface traffic fleet were powered entirely by hydrogen fuel cell technology, anthropogenic emissions of the ozone precursors nitrogen oxide (NOx) and carbon monoxide could be reduced by up to 50%, leading to significant improvements in air quality throughout the Northern Hemisphere. Model simulations of such a scenario predict a decrease in global OH and an increased lifetime of methane, caused primarily by the reduction of the NOx emissions. The sign of the change in climate forcing caused by carbon dioxide and methane depends on the technology used to generate the molecular hydrogen. A possible rise in atmospheric hydrogen concentrations is unlikely to cause significant perturbations of the climate system.

Influence of intestinal bacteria on induction of regulatory T cells: lessons from a transfer model of colitis

BACKGROUND

The resident flora plays a critical role in initiation and perpetuation of intestinal inflammation, as demonstrated in experimental models of colitis where animals fail to develop disease under germ free conditions. However, the importance of exposure to commensal bacteria before the onset of colitis is unclear. Our aim was to investigate the influence of previous exposure of donor animals to bacterial antigens on colitis development using a transfer model.

METHODS

Clinical course and histology were evaluated after transfer of CD4(+)CD62L(+) lymphocytes from germ free and conventionally housed donor mice into SCID recipients. Cotransfer of CD4(+)CD62L(+) cells with CD4(+)CD62L(- )lymphocytes from both groups of mice was initiated. Lymphocytes were analysed by FACS, polarisation potential of cells determined, and cytokines measured within the supernatant by enzyme linked immunosorbent assay.

RESULTS

Animals that received cells from germ free donors developed an earlier onset of colitis compared with mice reconstituted with lymphocytes from conventionally housed animals. Additionally, CD4(+)CD62L(- )cells from germ free mice were not able to abrogate colitis induced by cotransfer with CD4(+)CD62L(+) lymphocytes whereas CD4(+)CD62L(- )T cells from normal mice ameliorated disease. The higher percentage of CD4(+)GITR(+) expressing lymphocytes and the production of interleukin 10 after priming by dendritic cells suggests the presence of T(reg) cells within the CD4(+)CD62L(+) lymphocyte subset derived from conventional housed mice and assumes a lack of T(reg) cells within germ free mice.

CONCLUSION

The results indicate that bacterial antigens are crucial for the generation and/or expansion of T(reg) cells in a healthy individual. Therefore, bacterial colonisation is of great importance in maintaining the immunological balance.