In hospital-acquired pneumonia, extracellular matrix destruction is common and may be caused by excessive activity of matrix metalloproteinases (MMPs). Thirty patients with hospital-acquired pneumonia and 16 control subjects were studied. We evaluated the concentrations of MMP-8, MMP-9, and tissue inhibitor of metalloproteinase-1 in mini-bronchoalveolar lavage fluid (mini-BALF) and blood using zymography and specific immunoassays. In patients with hospital-acquired pneumonia concentrations of MMP-8 and MMP-9 in mini-BALF were increased 10-fold, whereas their specific inhibitor tissue inhibitor of metalloproteinase-1 was not concomitantly increased. In 80% of patients with pneumonia, but in none of the control subjects, the active form of MMP-9 was detected by zymography. Zymography furthermore showed the banding pattern of neutrophil-derived MMP-9, indicating that neutrophils were the main source of MMP-9. Comparison of neutrophils from blood and mini-BALF showed higher basal release of MMPs by pulmonary neutrophils. Stimulation analysis indicated that pulmonary neutrophils were already maximally activated. In patients with detection of potentially pathogenic microorganisms, concentrations of MMPs were fivefold increased compared with patients with negative cultures. Furthermore, MMP-levels were related to clinical severity. These are the first data suggesting that neutrophil-derived MMPs are increased in hospital-acquired pneumonia in association to the detection of causative microorganisms and clinical severity.

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Background-In the host defence of the lung neutrophils (PMN) play a central role. Apart from antimicrobial properties, recent data indicate that PMN also exert anti-inflammatory eVects by stimulation and release of cytokine antagonists such as interleukin-1 receptor antagonist (IL-1ra). Methods-Cytokine release from lipopolysaccharide stimulated whole blood was studied in 18 patients with community acquired pneumonia (CAP) and severe co-morbidities at admission and after 24 hours. Release of IL-1ra, interleukin-1 (IL-1 ), tumour necrosis factor (TNF ), soluble TNF receptor type I (sTNF-RI), and IL-8 was determined by ELISA. Results-The mean (SD) leucocyte level at admission was 12.5 (4.1)/nl. There was a significant correlation between the release of anti-inflammatory cytokines such as IL-1ra and sTNF-RI and the leucocyte count at admission and after 24 hours. Additional in vitro experiments showed that co-incubation of peripheral blood mononuclear cells with autologous PMN led to a marked dose dependent increase in IL-1ra and sTNF-RI release. Conclusion-These results indicate that PMN may be responsible for the increase in anti-inflammatory cytokines in CAP. Strategies to increase neutrophil counts may exert beneficial eVects, not only by augmenting the antimicrobial activity but also by modulating the inflammatory cytokine response. (Thorax 2001;56:121-125)

Granulocyte colony-stimulating factor (G-CSF) has immunomodulating properties that could be beneficial for adjunctive treatment of severe infections. Cytokine release from stimulated whole blood and expression of neutrophil surface and apoptosis markers in response to G-CSF were studied in human volunteers under physiologic conditions and after ethanol pretreatment. Levels of interleukin (IL)-1 receptor antagonist and soluble tumor necrosis factor (TNF) receptor-1 were significantly increased after G-CSF, whereas TNF-alpha and IL-10 concentrations were reduced, and IL-1beta and IL-8 remained unchanged. There was a significant inhibition of neutrophil apoptosis and increased expression of complement regulatory protein CD55 without changes in CD11b, CD14, and CD59 expression. These effects were well preserved after ethanol pretreatment, which per se led to an increase in apoptosis and decreased CD55 expression. Thus, G-CSF treatment was associated with a reduction of the proinflammatory cytokine response and enhanced neutrophil survival in vivo, suggesting a therapeutic potential of G-CSF for severe infections in the nonneutropenic host.

In 29 patients with community-acquired pneumonia, 24 patients with hospital-acquired pneumonia and 35 patients with pneumonia in the immunocompromised host the diagnostic value of bronchoalveolar lavage (BAL) with quantitative bacterial and fungal cultures was studied; 32 patients with noninfectious pulmonary diseases and 14 healthy volunteers served as controls. An infectious etiology could be established in 81% of the pneumonia patients without differences between the three groups; significant infection was associated with colony counts of > or = 10(4) cfu/ml. Prior antibiotic therapy lowered the yield of BAL culture only in community-acquired pneumonia (94% vs 55% positive cultures in untreated vs pretreated patients, p < 0.02). Furthermore the culture results were related to the radiographic extension of pulmonary infiltrates (92% positive cultures in multilobar vs 54% in lobar or segmental infiltrates, p < 0.001). Therapeutic consequences of BAL were shown by resistance of the isolated organisms to predefined empiric treatment regimens in 41% community-acquired pneumonia, 43% pneumonia in the immunocompromised host and 67% hospital-acquired pneumonia patients.