Cardiopulmonary bypass decreases cytokine production in lipopolysaccharide-stimulated whole blood cells: roles of interleukin-10 and the extracorporeal circuit.

OBJECTIVE: To determine whether cardiopulmonary bypass (CPB) alters the ex vivo cytokine production of whole blood cells stimulated by lipopolysaccharide (LPS) and to assess the roles of interleukin (IL)-10 and an extracorporeal circuit (ECC) in the alteration. DESIGN: Prospective, controlled study. SETTING: Biochemistry laboratory and surgical intensive care unit in a university hospital. PATIENTS: Seventeen consecutive adult patients undergoing coronary artery bypass grafting or valve surgery with normothermic CPB and eight healthy volunteers. INTERVENTIONS: Blood samples for cytokine measurement were drawn from patients before and during (at 60, 90, 120, 180 and 360 mins) CPB and were cultured with and without LPS and with and without anti-IL-10 antibodies. Blood was also drawn from healthy subjects and sampled for cytokine analysis before and during circulation in an isolated ECC. MEASUREMENTS AND MAIN RESULTS: The concentrations of ex vivo tumor necrosis factor (TNF)-alpha, IL-6, IL-8, and IL-10, measured by enzyme-linked immunosorbent assay, were reduced in both experimental settings. In patients on CPB, LPS hyporesponsiveness was detected at 60 mins after the onset of CPB and was maximal at 120 mins (78% to 86% decreases from pre-CPB levels) but was transient, except for TNF-alpha. The plasma concentration of IL-10 peaked at 90 mins after the start of CPB, but the role of IL-10 in LPS hyporesponsiveness appears limited because anti-IL-10 antibodies significantly increased ex vivo production of IL-6 but not TNF-alpha or IL-8. In the isolated ECC study, no IL-10 was detected in plasma, yet the ex vivo production of the cytokines (except IL-8) was decreased (by 66% to 95%). CONCLUSION: Our results demonstrate the following: a) CPB induces an early and transient LPS hyporesponsiveness of whole blood as measured by cytokine production; b) IL-10 seems only partly involved in this process, and its role is restricted to an in vivo situation; and c) contact of blood with an ECC is sufficient to induce LPS hyporesponsiveness.

Oncostatin M is a potent stimulator of alpha1-antitrypsin secretion in lung epithelial cells: modulation by transforming growth factor-beta and interferon-gamma.

alpha1-Antitrypsin (alpha1-AT) plays a key role in lung homeostasis. Although the hepatocyte is considered as the primary source of alpha1-AT, we have previously demonstrated that rat alveolar epithelial type II cells as well as the human A549 cell line synthesize alpha1-AT, suggesting its local production within the lung. In the present study, we showed that oncostatin M, as opposed to interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), or IL-6, is a potent stimulator of alpha1-AT synthesis in the human A549 cell line. The oncostatin M-induced alpha1-AT secretion is modulated by interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) at both the protein and mRNA levels. IFN-gamma decreases oncostatin M-induced alpha1-AT secretion. By contrast, TGF-beta in combination with oncostatin M induces a dramatic and synergistic upregulation that is not observed in the HepG2 hepatocyte cell line. Our results suggest that during an inflammatory process, alveolar epithelial cells may contribute to the antiprotease defense within the lung.

Compartmentalized IL-8 and elastase release within the human lung in unilateral pneumonia.

Because interleukin 8 (IL-8) is a potent neutrophil chemotactic and activating cytokine, we investigated IL-8 production in relation to neutrophil migration and elastase release in the human lung during unilateral community-acquired pneumonia (CAP). In 17 patients, the local response in the involved lung was compared with that in the contralateral, noninvolved lung, and with the systemic response. Eight healthy volunteers served as controls. IL-8, total neutrophil elastase (NE), free elastase activity, alpha 1-antitrypsin (alpha 1-AT), and total leukocyte and neutrophil counts were evaluated in bronchoalveolar lavage fluids (BALF). Mean IL-8 concentrations in BALF from the involved lungs of the patients were significantly greater than those in BALF from the noninvolved lung or from controls (p < or = 0.001). By contrast, the serum IL-8 concentration was not different in patients and in controls. Total NE and alpha 1-AT concentrations were increased in BALF from the involved lung as compared with the noninvolved lung or controls (p < or = 0.001). The elastase-inhibitory capacity of alpha 1-AT in BALF was impaired in the involved lung of seven of the 14 patients as compared with the controls, leading to free elastase activity in the involved lung of all patients with CAP. Plasma total NE concentrations were significantly greater in the CAP patients than in the controls. IL-8 concentrations in BALF correlated positively with total leukocyte counts, absolute numbers and percentages of neutrophils, total NE concentrations, and free elastase activity. Our results suggest that during unilateral CAP, locally produced IL-8 may trigger neutrophil accumulation and activation, thus contributing to a local elastase/antielastase imbalance within the site of infection.

Compartmentalized cytokine production within the human lung in unilateral pneumonia.

The in situ inflammatory response developing in the human lung during a localized bacterial infection was studied in 15 patients with unilateral community-acquired pneumonia (CAP). The local response in the involved lung was compared with that in the contralateral, noninvolved lung as well as with the systemic blood response. Eight healthy volunteers served as control subjects. Concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) were measured by ELISA in bronchoalveolar lavage (BAL) fluids (n = 15), serum (n = 15), and alveolar macrophage and monocyte culture supernatants (n = 8). The concentrations of TNF-alpha, IL-beta and IL-6 in BAL fluid were significantly higher in the involved lung than in the paired noninvolved lung (p < or = 0.01) or in healthy subjects (p < or = 0.02, p < or = 0.01, and p < or = 0.001, respectively). Serum IL-6 concentrations were higher in patients than in control subjects, whereas IL-1 beta and TNF-alpha concentrations did not differ in the two groups. Alveolar macrophages from the involved lung spontaneously released higher concentrations of IL-1 beta, IL-6, and TNF-alpha (p < or = 0.05) than did macrophages from the noninvolved lung, which served as controls. However, macrophages were hyporesponsive in terms of cytokine production to further stimulation by lipopolysaccharide (LPS) in the noninvolved and involved lung compared with controls, whereas peripheral blood monocytes were not.(ABSTRACT TRUNCATED AT 250 WORDS)

Secretion of alpha 1-antitrypsin by alveolar epithelial cells.

We have investigated the ability of alveolar epithelial cells (human A549 cell line and rat type-II pneumocytes) to produce alpha 1-antitrypsin (AAT). Northern blot analysis demonstrated the presence of an AAT-specific mRNA transcript in A549 cells. Unstimulated A549 cells secreted immunoreactive AAT at a rate of 0.51 +/- 0.04 ng/10(6) cells/h, with a modified glycosylation compared to serum AAT. AAT formed a complex with neutrophil elastase. Rat type-II pneumocytes secreted immunoreactive AAT. Our results suggest that alveolar epithelial cells could participate in antiprotease defense within the lung through local AAT production.