On human macrophages IL-10 acts as a more potent anti-inflammatory cytokine than IL-6, although both cytokines signal mainly via activation of the transcription factor STAT3. In this study we compare IL-10 and IL-6 signaling in primary human macrophages derived from blood monocytes. Pretreatment of macrophages with PMA or the proinflammatory mediators LPS and TNF-␣ blocks IL-6-induced STAT3 activation, whereas IL-10-induced activation of STAT3 remains largely unaffected. Although LPS induces the feedback inhibitor suppressor of cytokine signaling 3 (SOCS3) in macrophages, inhibition of IL-6 signal transduction by LPS occurs rapidly and does not depend on gene transcription. We also found that pretreatment of macrophages with IL-10 inhibits subsequent STAT3 activation by IL-6, whereas IL-10-induced STAT3 activation is not affected by preincubation with IL-6. This cross-inhibition is dependent on active transcription and might therefore be explained by different sensitivities of IL-10 and IL-6 signaling toward the feedback inhibitor SOCS3, which is induced by both cytokines. In contrast to the IL-6 signal transducer gp130, which has been previously shown to recruit SOCS3 to one of its phosphotyrosine residues (Y759), peptide precipitation experiments suggest that SOCS3 does not interact with phosphorylated tyrosine motifs of the IL-10R. Taken together, different sensitivities of IL-10 and IL-6 signaling toward mechanisms that inhibit the Janus kinase/STAT pathway define an important mechanism that contributes to the different anti-inflammatory potencies of these two cytokines.

Recent findings indicate that cytokine signaling can be modulated by other mediators of simultaneously activated signal transduction pathways. In this study we show that LPS and TNFK K are potent inhibitors of IL-6-mediated STAT3 activation in human monocyte derived macrophages, rat liver macrophages and RAW 264.7 mouse macrophages but not in human hepatoma cells (HepG2) or in rat hepatocytes. Accordingly, LPS and TNFK K were found to induce the expression of SOCS3 mRNA in each of the investigated type of macrophages but not in HepG2 cells. Using a specific inhibitor, evidence is presented that the p38 MAP kinase might be involved, especially for the inhibitory effect of TNFK K.z 1999 Federation of European Biochemical Societies.

OBJECTIVES To identify the signaling pathways involved in the anti-inflammatory shift of the cytokine balance due to hypothermia during cardiopulmonary bypass. DESIGN Experimental animal study. SETTING Department of experimental surgery of a university hospital. SUBJECTS Young pigs. INTERVENTIONS Animals underwent normothermic (37 degrees C) or hypothermic (28 degrees C) cardiopulmonary bypass (n = 6 each). Samples of liver tissue were taken before and 6 hrs after cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS Intrahepatic expression of tumor necrosis factor-alpha, interleukin-10, inducible nitric oxide synthase, and suppressor of cytokine signaling-3 was detected by reverse transcriptase polymerase chain reaction and/or Western blotting. Concentrations of the inhibitory protein of nuclear factor-kappaB, IkappaB, and of the signal transducer and activator of transcription (STAT)-3 were measured by Western blotting. The DNA-binding activity of nuclear factor-kappaB and STAT-3 was assessed by electrophoretic mobility shift and supershift assays. Liver cell necrosis and apoptosis were assessed by histology and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, respectively. Pigs operated on in hypothermia showed significantly higher intrahepatic concentrations of interleukin-10 and lower concentrations of tumor necrosis factor-alpha than the others. They also showed a lower percentage of hepatic cell necrosis but not of apoptosis. This anti-inflammatory reaction observed in the hypothermic group was associated with a higher expression of suppressor of cytokine signaling-3 and with increased activation of STAT-3. Activation of nuclear factor-kappaB and expression of inducible nitric oxide synthase, however, were not significantly different between both groups. CONCLUSION Our results show that hypothermia during cardiopulmonary bypass up-regulates interleukin-10 via STAT-3 activation, which in turn leads to the attenuation of tumor necrosis factor-alpha expression and to hepatic protection.

Purpose:To describe the epidemiology of the acute respiratory distress syndrome (ARDS) in a Brazilian ICU.Methods: This prospective observational, non-interventional study, included all consecutive patients with ARDS criteria [1] admitted in the ICU of a Brazilian tertiary hospital, between January 1997 and September 2001. Were collected in a prospective fashion the following variables: age, gender, APACHE II score at ICU admission and at ARDS diagnosis, cause of ARDS, presence of AIDS, cancer and immunosuppression, occurrence of barotrauma, performance of traqueostomy, mortality, duration of mechanical ventilation (MV), length of stay (LOS) in ICU and in hospital. The lung injury score (LIS) [2] was used to quantify the degree of pulmonary injury in the first week of ARDS.Results: There was 2182 patients (P) admitted in ICU during the study period, of whom 141 (6.46%) had ARDS criteria. Seventy-six (54%) were men, the mean age was 46 ± 18 years, APACHE II 18 ± 7 and 19 ± 7 at admission and at ARDS diagnosis, respectively. Septic shock accounted for 42% (60 P) of the ARDS causes, sepsis 22% (31 P), diffuse pulmonary infection 16% (23 P), aspiration pneumonia 11% (15 P), non-septic shock 5% (7 P) and others 4% (5 P). Ten percent (14 P) had AIDS, 30% (43 P) cancer and 25% (36 P) immunosuppression. All patients were mechanically ventilated with Tidal Volume between 4 and 8 ml/kg. Only 3.5% (5 P) had barotrauma and 10% (14 P) performed traqueostomy. Mortality rate was 79% in the ICU. The patients required 12 ± 10 days on MV, ranging from 1 to 55 days. The LOS in ICU and hospital was 14 ± 13 (1-69) days and 28 ± 32 (1-325) days, respectively. There was a time delay of 3.7 ± 4.5 days between admission in ICU and the onset of ARDS. The Murray score (mean ± SD) was 3.2 ± 0.4, 3 ± 0.5, 3 ± 0.5, 2.9 ± 0.6, 2.8 ± 0.7, 2.7 ± 0.7 and 2.6 ± 0.8 in the first 7 days, respectively.Conclusions: ARDS in our hospital has a similar incidence of reports in the USA and Europe. There was a higher mortality, which could be explained by a high incidence of infection causes of ARDS, mainly septic shock, and elevated combined occurrence of AIDS, cancer and immunosuppression, along the degree of LIS. The incidence of barotrauma was low, as a consequence of the current mechanical ventilation strategies.Purpose: To correlate the occurrence and level of organ dysfunction in ARDS with mortality. Methods:This cohort study includes all consecutive patients with ARDS criteria [1] admitted in the ICU between January 1997 and September 2001. Were collected in a prospective fashion the following variables: age, gender, APACHE II score at the ARDS diagnosis, the occurrence of organ dysfunction determined by the multiple organ dysfunction syndrome (MODS) [2] in the first week, and mortality in the ICU. The occurrence of organ/system dysfunction was considered with a MODS equal to or greater than 1 in any day. The levels 3 or 4 of MODS were considered severe organ/system dysfunction. Statistical analyses were done by Mann-Whitney and chi-square as indi...

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