[Research in pneumology since 100 years]

Pulmonology during the last century has early on benefited from outstanding morphologic, anatomic and physiologic descriptions which have allowed the comprehension of pulmonary mechanic and gas exchanges. On these bases invasive and non-invasive ventilations have been initiated. With the discovery of antibiotics and antituberculosis treatments, the mortality related to infections diseases has markedly decreased in the young ages in countries having access to them. Biotechnology should soon improve the treatment not only of vascular but also interstitial diseases. Surgery remains the cornerstone for the treatment of limited cancer. Lung transplantation and lately thromboendarterectomy are becoming of more widespread usage.

Evaluation of phagocytic activity in human monocyte-derived dendritic cells

Dendritic cells play a central role in initiation of primary T lymphocyte responses to foreign antigens. Their potency in antigen presentation vis-à-vis reported low or lack of ability to phagocytize particulate matter has limited our understanding of the role that they play in inducing immunity to particulate antigens. One hypothesis is that dendritic cells may possess a high phagocytic capacity when immature and located in peripheral tissues, which they lose on maturation. Our goal was to characterize the phagocytic capacity in human immature dendritic cells. The phagocytic capacity of human monocyte-derived immature dendritic cells was studied by morphological and morphometric means, and compared to that of professional phagocytes, human alveolar macrophages, their progenitors, the peripheral blood monocytes, and mature dendritic cells. Phagocytic index (proportion of phagocytic cells) was decreased by 42.8% (immature dendritic cells) and 74.2% (mature dendritic cells) with respect to monocytes. Similarly, the phagocytic index was decreased by 46.5% (immature dendritic cells) and 75.9% (mature dendritic cells) with respect to macrophages. Volume density of phagocytized particles was decreased by 76.1% (immature dendritic cells) and 96.7% (mature dendritic cells) with respect to the monocytes. However, volume density was decreased by 34.3% (immature dendritic cells) and 91% (mature dendritic cells) with respect to alveolar macrophages. These results show that human monocyte-derived immature dendritic cells possess a phagocytic capacity that is lower than that of peripheral blood monocytes and alveolar macrophages but higher than that of mature dendritic cells.

Early chimerism of macrophages and lymphocytes in lung transplant recipients is predictive of graft tolerance

BACKGROUND

The persistence of donor cells derived from the graft (chimerism) has been documented in various tissues after organ transplantation. It was suggested that stable chimerism might reflect a state of donor-specific tolerance. Chimerism of macrophages and lymphocytes were studied over time after lung transplantation as well as its impact on graft tolerance.

MATERIAL AND METHODS

Macrophages and lymphocytes were purified from bronchoalveolar lavage sequentially obtained from 24 patients between 1 and 41 months posttransplantation (20, 22, 24, and 17 patients at, respectively, 1, 3, 6, and 12 months). DNA was extracted from these cells and their recipient-donor origin was evaluated by PCR amplification of highly polymorphic DNA regions (minisatellites).

RESULTS

We show that the remaining donor cells over the first month vary from 10 up to 50% and 5 up to 55% for lymphocytes and macrophages respectively (+/-2 SD). All patients presented some chimerism up to the 6th postoperative month. Good correlation was observed between the residual amount of donor lymphocytes and macrophages during the first 3 months (P<0.001). Patients with at least 30% donor lymphocytes at 1 month after transplantation had less rejections (> or =stage II) in the follow up (P=0.0007). The same observation is true for donor macrophages although to lower extend (P=0.02). The chimerism lost its predictive value beyond 3 months.

CONCLUSIONS

These data demonstrate that a level of chimerism above 30% of either donor lymphocytes or macrophages at 1 month is related to a better state of graft tolerance. However, chimerism decreases markedly beyond 3 months and has then no predictive value.

Genetic background of attenuated Salmonella typhimurium has profound influence on infection and cytokine patterns in human dendritic cells

Salmonella typhimurium (ST) can cause infection in man, and attenuated strains are under consideration as live vaccine vectors. However, little is known about the interaction of ST with human dendritic cells (DC). Here, we compared the consequences of exposure of human, monocyte-derived DC with different attenuated strains of ST. Infection was observed with all four strains tested (wild type, PhoP-, PhoPc, and AroA), but the PhoPc strain was by far the most efficient. Intracellular persistence of wild type and PhoP- was longer than that of PhoPc and AroA, both of which were largely eliminated within 24 h. Most DC survived infection by the attenuated strains, although apoptosis was observed in a fraction of the exposed cells. All strains induced DC maturation, independent from the extent of infection. Although all strains stimulated secretion of TNF-alpha and IL-12 strongly, PhoPc induced significantly less IL-10 than the other three strains and as much as 10 times less IL-10 than heat-killed PhoPc, suggesting that this mutant suppressed the secretion of IL-10 by the DC. These data indicate that infectivity, bacterial elimination, and cytokine secretion in human DC are controlled by the genetic background of ST.

Human lung tissue macrophages, but not alveolar macrophages, express matrix metalloproteinases after direct contact with activated T lymphocytes

Human alveolar macrophages (AM) and lung tissue macrophages (LTM) have a distinct localization in the cellular environment. We studied their response to direct contact with activated T lymphocytes in terms of the production of interstitial collagenase (MMP-1), 92-kD gelatinase (MMP-9), and of TIMP-1, one of the counter-regulatory tissue inhibitors of metalloproteinases. Either AM obtained by bronchoalveolar lavage or LTM obtained by mincing and digestion of lung tissue were exposed for 48 h to plasma membranes of T lymphocytes previously activated with phorbol myristate acetate and phytohemagglutinin for 24 h. Membranes of activated T cells strongly induced the production of MMP-1, MMP-9, and TIMP-1 exclusively in LTM but not in AM, whereas membranes from unstimulated T cells failed to induce the release of MMPs. Both populations of mononuclear phagocytes spontaneously released only small amounts of MMPs and TIMP-1. Similar results were obtained when MMP and TIMP-1 expression was analyzed at pretranslational and biosynthetic levels, respectively. Blockade experiments with cytokine antagonists revealed the involvement of T-cell membrane-associated interleukin-1 and tumor necrosis factor-alpha in MMP production by LTM upon contact with T cells. These data suggest that the ability of lung macrophages to produce MMPs after direct contact with activated T cells is related to the difference in phenotype of mononuclear phagocytes and cell localization. In addition, these observations indicate that cell-cell contact represents an important biological mechanism in potentiating the inflammatory response of mononuclear phagocytes in the lungs.

Fungal infections in transplant recipients

Fungi are ubiquitous and the respiratory tract is exposed to aerosolized spores of both fungi that are "pathogenic" even in the normal host, such as Cryptococus neoformans, and those that are "opportunistic", such as Candida and Aspergillus species, among others. Although these latter species may occasionally form fungal balls or induce allergic phenomena in the normal host, they produce more invasive diseases in immunosuppressed patients. Among these diseases, pseudomembranous aspergillosis has recently been described. The diagnostic approach to these entities, and, in particular, the thin dividing line between colonization and infection are addressed, along with the diagnostic value of the various procedures. New prophylactic regimens are reviewed such as the possibility of using amphotericin aerosols in combination with systemic azole administration. The authors would emphasize the importance of restoring lung defences by not only decreasing immunosuppressive regimens but also considering the use of newly available recombinant cytokines such as growth factors, to reduce neutropenia, for instance, in addition to antifungal drugs when infection is diagnosed. However, immunomodulation procedures are far from being well established.

New strategies against an old plague: genetically engineered tuberculosis vaccines

The failure of BCG vaccination to control the global tuberculosis epidemic and the spread of multidrug resistance underline the need for a better vaccine. Recent advances in molecular microbiology, gene therapy, and, last but not least, immunobiology, provide a rational basis for the development of more efficient vaccines against tuberculosis. The complete sequencing of the M. tuberculosis genome marked a turning point in tuberculosis vaccine research. The advent of genetic vaccination with either naked DNA, live recombinant, or artificial vaccine vectors holds out great promise of more efficient immunisation, in particular against intracellular pathogens such as M. tuberculosis. Our new understanding of how the immune response is orchestrated by dendritic cells makes it possible to design vaccines which specifically exploit the functions of these antigen presenting cells. Yet M. tuberculosis has kept many of its secrets, and although functional genomics, molecular medicine and immunotherapy are evolving rapidly, much empiric search and discovery are needed until the "captain of all these men of death" gives up his ghost to biotechnology.

Matrix metalloproteinases correlate with alveolar-capillary permeability alteration in lung ischemia-reperfusion injury

BACKGROUND

Matrix metalloproteinases (MMPs) are able to degrade the endothelial basal lamina and increase vascular permeability.

METHODS

In a porcine model of isolated-reperfused lung, we studied the alveolar-capillary permeability and the zymographic expression of MMP-9 and MMP-2 in the bronchoalveolar lavage fluid of lungs submitted ex vivo to ischemia in three preservation solutions [modified Euro-Collins (EC), low-potassium-dextran, modified-blood]. Twenty-two pigs were randomly divided into three groups according to the preservation solution used. One lung of each pig was rapidly reperfused and analyzed (control lung) although the other lung was reperfused and analyzed after 8 hr of ischemia (ischemic lung).

RESULTS

Alveolar-capillary permeability, evaluated by the transferrin leak index, was increased after 8 hr of ischemia compared with controls in the three groups, but was significantly higher in the modified EC group. In the EC group, after 8 hr of ischemia, both proMMP-9 and MMP-9 increased significantly (8.8- and 22-fold, respectively) compared with controls and this increase correlated with the transferrin leak index. Neither proMMP-9 nor MMP-9 increased with the other two preservation solutions. The MMP-2 increase after ischemia was smaller and was also restricted to the EC group.

CONCLUSION

MMP expression is enhanced during lung ischemia-reperfusion, especially in the presence of EC and this phenomenon correlates with the alteration of alveolar-capillary permeability.

Antigen presentation in the lung: dendritic cells and macrophages

Antigen presentation is a required prime event before T-cell activation can occur. Cells which constitutively express major histocompatibility antigen class I or II are responsible for presenting antigens. These are essentially alveolar macrophages (AM) residing mostly in the air spaces, and dendritic cells (DC), which create a tight surveillance network just below the epithelial cells of the airways and in the loose connective tissue around the vessels or in the pleura. AM are poor antigen presenting cells compared to DC. AM when encountering foreign particles or organisms may, however, influence the degree of activity or maturation of neighbouring DC, by releasing cytokines. Thus, we will describe how the innate immune processes may influence specific immunity and perhaps Th1 and Th2 differentiation. Following the description of the differences in phenotype and functions of AM and DC, we will provide data showing that in some pathological conditions, such as sarcoidosis, AM can acquire some specificities of DC.

[Indications for lung transplantation in advanced cystic fibrosis]

Lung transplantation has become a valid therapeutic option for cystic fibrosis patients with end-stage lung disease. The indication for transplantation does not rely on strict criteria only but must be evaluated case by case. In particular, the dynamics of the clinical course need to be considered with regard to impaired physical performance, recurrent infections, decline in pulmonary function and weight loss. Important risk factors are a poor nutritional status, osteoporosis, liver involvement, previous pleurodesis and the occurrence of multiresistant bacteria. Management and assessment of cystic fibrosis patients for lung transplantation is complex. Therefore patients should be referred to specialised centres at an early stage.

Pulmonary defence mechanisms

Lung defence involves a wide array of mechanisms needed to remove inhaled particles and organisms. The various innate immune processes which take place either in the central or in the more distant airways are reviewed. The recruitment and the development of an adaptive immunity following the innate response are described. This entails the production of secretory immunoglobulins in the airways and either the influx of polymorphonuclear neutrophils in the alveoli to phagocytose more or less opsonized organisms or the activation of the T lymphocyte response to improve the removal of intracellular pathogens.

Bone mineral density in lung-transplant recipients before and after graft: prevention of lumbar spine post-transplantation-accelerated bone loss by pamidronate

BACKGROUND

Lung-transplant recipients are at risk of osteoporosis. They may have low bone mass even before posttransplantation immunosuppressive therapy. We studied bone mineral density (BMD) before and after lung transplantation and compared the efficacy of antiresorptive therapies to calcium and vitamin D supplementation.

METHODS

Areal BMD was assessed in 42 patients awaiting lung transplantation and measured again after surgery at 6 (n = 29), and at 12 months (n = 20). Nineteen patients received antiresorptive therapy (30 mg pamidronate IV every 3 months (n = 14), or hormonal replacement therapy (n = 5)), and 10 patients received only calcium and vitamin D supplements.

RESULTS

Mean age- and gender-adjusted lumbar spine (LS) and femoral neck (FN) BMD was significantly decreased prior to transplantation (- 0.6 +/- 0.2, p< 0.01, and - 1.5 +/- 0.2 standard deviation, p < 0.001, respectively). At that time, 29% were osteoporotic (T-score < - 2.5 below the peak bone mass), while 55% were below - 1.0 T-score. Antiresorptive therapy decreased the rate of LS bone loss during the first 6 months and led to a significant increase of BMD at 1 year, with LS changes of + 0.2 +/- 0.1 vs - 0.4 +/- 0.1 Z-score in the calcium-vitamin D group (p< 0.002), and + 0.2 +/- 0.1 vs - 0.04 +/- 0.1 for FN (NS). One out of 20 patients experienced clinically evident fractures during antiresorptive therapy, and 3 out of 12 in the calcium-vitamin D group.

CONCLUSION

A significant proportion of patients awaiting lung transplantation was osteoporotic or osteopenic. Antiresorptive therapy (pamidronate or hormone-replacement therapy (HRT)) prevented accelerated LS bone loss after graft.

Human lung dendritic cells have an immature phenotype with efficient mannose receptors

Dendritic cells (DC) can be present at distinct stages of differentiation within the immune system. Sallusto and colleagues have recently described an in vitro culture system suitable for analyzing the maturation processes of DC (Sallusto and colleagues, J. Exp. Med. 1994;179:1109-1118). Monocytes cultured for 6 d in the presence of granulocyte macrophage colony-stimulating factor and interleukin-4 develop into immature DC with a high endocytic capacity but a low capacity to stimulate T cells. When challenged by lipopolysaccharide, these cells upregulate costimulatory molecules, express CD83, and become mature DC. CCR1 and CCR5 chemokine receptors are highly expressed on immature DC and downregulated on mature DC. This in vitro system was used to characterize human lung DC. Lung DC were shown to express some characteristics of in vitro immature DC. These are: (1) low expression of the costimulatory molecules CD40, CD80, and CD86; (2) poor expression of the differentiation marker CD83 and no CD1a; and (3) good capacity to incorporate dextran. Lung DC express moderate levels of CCR1 and CCR5. However, lung DC, like in vitro mature DC, express high levels of major histocompatibility complex Class II molecules, show low expression of CD14 and CD64, and are characterized by their high capacity to stimulate allogeneic T cells to proliferate during mixed leukocyte reactions (MLRs). Although lung DC express low levels of CD80 and CD86, the important role of these costimulatory molecules in inducing high MLR was demonstrated by using blocking antibodies. Therefore, while lung DC have overall a phenotype and an endocytic capacity close to in vitro immature DC, they share, like in vitro mature DC, a powerful capacity to stimulate T cells.

Costs and outcomes of prolonged cytomegalovirus prophylaxis to cover the enhanced immunosuppression phase following lung transplantation

BACKGROUND

Cytomegalovirus (CMV) disease is one of the major challenges of lung transplantation that may determine outcome. The benefits of ganciclovir prophylaxis seem indisputable, but no consensus has been reached on the optimal duration of therapy. Results with different protocols suggest that efficacy is related to the duration of treatment.

MATERIALS AND METHODS

To evaluate the additional effect of a prolonged regimen throughout the maximal immunosuppression phase, we conceived a protocol administering ganciclovir, 5 mg/kg/d for 20 weeks from the first postoperative day, to all CMV-seropositive patients undergoing lung transplantation or receiving the lung from a seropositive donor. Virus shedding was routinely measured in body fluids including through BAL. Costs and outcomes are compared with those in shorter prophylaxis protocols from previous reported studies.

RESULTS

Of 30 lung transplant recipients, 22 patients at risk for CMV reactivations were observed for (mean SD) 22.9 +/- 13.2 months. CMV infections were detected in eight patients 8.6 +/- 5.1 months after transplantation. CMV pneumonitis developed in one patient 9 months following the transplant event. Prolonged IV ganciclovir prophylaxis was, in general, well tolerated. However, five patients had bacteremia and one had a local thrombosis, with no long-term consequences. A prescription for 8 additional weeks of prophylaxis to cover the whole period of enhanced immunosuppression decreased the cumulative incidence of first CMV infections by 29% 1 year after transplantation compared to 12-week regimens reported in other studies that indicated a 50% reduction in the incidence of first CMV infection. The total cost of 20 weeks of IV ganciclovir prophylaxis was $6,010 (US dollars) per patient more expensive than 12 weeks of IV ganciclovir therapy. This was not offset by the reduced requirement for treatment of infections. Indeed, extrapolating to our cohort of patients, the additional cost per patient was seven times greater than the treatment for the infections that were reported after the 12-week prophylaxis protocol.

CONCLUSION

Prolonging ganciclovir prophylaxis to 20 weeks decreased by half the rates of CMV infection when compared to reports from centers using a shorter protocol of 12 weeks for ganciclovir prophylaxis. Additionally, a delay in the onset of the first infection was observed. Nevertheless, the increase in costs and the discomfort of long-term use of venous catheters are important factors that may favor a shorter regimen of 12 weeks followed by preemptive therapies each time CMV infections occur.

Beneficial effects of leukocyte-depleted blood and low-potassium dextran solutions on microvascular permeability in preserved porcine lung

Modified Euro-Collins (EC) solution, a crystalloid intracellular-type solution, has been commonly used for pulmonary preservation. Several experimental studies have shown the advantages of using extracellular colloid-based solutions. The aim of this study was to compare the quality of preservation of two extracellular colloid solutions, leukocyte-depleted blood (BL) and low-potassium dextran (LPD) solutions, with that of EC solution. Lungs of 22 domestic pigs were flushed and preserved with EC (n = 8), BL (n = 7), or LPD (n = 7) solution. After harvesting, one of the lungs was reperfused immediately in an ex vivo circuit (control lungs), whereas the contralateral lung was reperfused after 8 h of cold (4 degrees C) storage (preserved lungs). Besides the lung function parameters (gas exchange, pulmonary hemodynamics and mechanics), the permeability of the endothelial-epithelial barrier was assessed by determining the transferrin leak index (TLI) using a double radioisotopic method, by measuring the alveolar/arterial protein concentration ratio, and by analyzing histopathologic changes. The functional quality (oxygenation, airway resistance, dynamic compliance [CL, dyn]) of both BL and LPD lungs was slightly but significantly superior to that of EC lungs. However, pulmonary vascular resistance was lower in BL-preserved than in EC- or LPD-preserved lungs. The TLI was increased in EC control and preserved lungs, whereas it was low in BL and LPD control lungs and did not increase after preservation. The alveolar/arterial protein concentration ratio was not different between control groups, but was increased fourfold in EC-preserved compared with BL- or LPD-preserved lungs. Finally, EC-preserved lungs presented a weight gain about twice that of BL- and LPD-preserved lungs. Morphologic analysis confirmed these results, because in the EC-preserved lungs, rupture of alveolar septa and severe alveolar edema and hemorrhage were observed, whereas BL- and LPD-preserved lungs showed a relatively well-preserved structure. The results demonstrate that both BL and LPD flush solutions preserve the endothelial-epithelial barrier better than does EC solution. Although the quality of preservation is similar, pulmonary vascular resistance is higher in LPD-preserved than in BL-preserved lungs.

Improvement of drug-induced chronic renal failure in lung transplantation

BACKGROUND

Nephrotoxicity is a frequently encountered adverse effect of calcineurin inhibitors (cyclosporine and tacrolimus)-combined immunosuppressive regimens.

METHODS

We have compared the glomerular filtration rate in 14 patients who underwent lung transplantation, before and after replacement of azathioprine by mycophenolate mofetil and reduction of associated calcineurin inhibitors doses.

RESULTS

After a mean follow-up of 16+/-4 months with the modified immunosuppressive regimen, the mean glomerular filtration rate increased by 20% with no change in lung function.

CONCLUSION

By its strong immunosuppressive effect, mycophenolate mofetil allows the decrease of associated calcineurin inhibitor doses, with subsequent improvement of renal function without jeopardizing the transplanted lung.

Differential regulation of tumor necrosing factor-alpha (TNF-alpha) and interleukin-10 (IL-10) secretion by protein kinase and phosphatase inhibitors in human alveolar macrophages

IL-10, a cytokine first identified as a product of cloned Th2 lymphocytes, is also produced by monocytes/macrophages. By its ability to inhibit cytokine synthesis and the expression of surface antigens, IL-10 is able to temper inflammation. In contrast, TNF-alpha plays a key role in acute and chronic inflammation and has been implicated in several forms of lung injury. The objective of this study was to investigate whether activators or inhibitors of LPS-activated signalling pathways might be able to dissociate TNF-alpha from IL-10 secretion in alveolar macrophages (AM). The results show that PMA activates expression of TNF-alpha without inducing IL-10 expression. We further demonstrate that LPS-induced TNF-alpha secretion is independent of PKC activation and can be increased by inhibitors of the serine/threonine phosphatases PP1 and PP2A. In contrast, LPS-mediated IL-10 secretion is down-regulated by PMA and inhibitors of PP1 and PP2A. Addition of PKC inhibitors reverses the PMA-mediated down-regulation of LPS-induced IL-10 secretion, indicating that PKC, once activated in vivo, might play a prominent role in controlling the secretion of IL-10 by AM. This study provides evidence that the PKC activator PMA and the phosphatase inhibitor calyculin A are able to dissociate TNF-alpha from IL-10 secretion by AM. Our data further indicate that LPS-mediated activation of certain signalling molecules has different consequences on the secretion of TNF-alpha or IL-10 by AM, an observation which may be important for the modulation of immune and inflammatory processes.

Interleukin-12 production by human alveolar macrophages is controlled by the autocrine production of interleukin-10

By releasing interleukin (IL)-12 in the lung, alveolar macrophages (AM) may profoundly modify an immune response. The autocrine regulation of the heterodimeric, biologically active form of IL-12 (IL-12 p70) by IL-10 was studied, as well as the expression of its subunits of 35 kD (p35) and 40 kD (p40). AM cultured in medium alone expressed only p35 mRNA. Both p35 and p40 mRNA levels were induced by lipopolysaccharide (LPS) and were further increased by interferon-gamma (IFN-gamma). LPS alone induced IL-12 p40 but not IL-12 p70 production in monocytes and in AM. However, IL-12 p70 was released when the autocrine production of IL-10 was neutralized by IL-10 blocking antibody, and IL-12 p40 production increased. Although IFN-gamma markedly decreased LPS-induced IL-10 production in AM, neutralizing IL-10 further enhanced the level of LPS and IFN-gamma-induced IL-12 p70 in AM. In contrast, neutralizing the trace amount of IL-10 released by AM stimulated by CD40 crosslinking and IFN-gamma did not increase IL-12 p70. Thus, IL-12 p70 production by AM appears to be tightly controlled by the autocrine release of IL-10 when stimulated by LPS, or by LPS and IFN-gamma, whereas CD40 crosslinking triggered IL-12 p70 production in the absence of autocrine regulation by IL-10.

Physiological changes in respiratory function associated with ageing

Physiological ageing of the lung is associated with dilatation of alveoli, enlargement of airspaces, decrease in exchange surface area and loss of supporting tissue for peripheral airways ("senile emphysema"), changes resulting in decreased static elastic recoil of the lung and increased residual volume and functional residual capacity. Compliance of the chest wall diminishes, thereby increasing work of breathing when compared with younger subjects. Respiratory muscle strength also decreases with ageing, and is strongly correlated with nutritional status and cardiac index. Expiratory flow rates decrease with a characteristic alteration in the flow-volume curve suggesting small airway disease. The ventilation-perfusion ratio (V'A/Q') heterogeneity increases, with low V'A/Q' zones appearing as a result of premature closing of dependent airways. Carbon monoxide transfer decreases with age, reflecting mainly a loss of surface area. In spite of these changes, the respiratory system remains capable of maintaining adequate gas exchange at rest and during exertion during the entire lifespan, with only a slight decrease in arterial oxygen tension, and no significant change in arterial carbon dioxide tension. Ageing tends to diminish the reserve of the respiratory system in cases of acute disease. Decreased sensitivity of respiratory centres to hypoxia or hypercapnia results in a diminished ventilatory response in cases of heart failure, infection or aggravated airway obstruction. Furthermore, decreased perception bronchoconstriction and diminished physical activity may result in lesser awareness of the disease and delayed diagnosis.

Pre-emptive therapy with azoles in lung transplant patients. Geneva Lung Transplantation Group

Pulmonary fungal infection is diagnosed in up to 15-25% of lung transplant recipients and frequently bears a fatal outcome. This prospective uncontrolled study addresses the efficacy and safety of pre-emptive azole therapy against fungal infection in these patients. Fluconazole or itraconazole have been systematically used according to reported fungus sensitivity after the discovery of fungi in lower respiratory tract samples. Patients were treated until the bronchial suture was normal and the cultures of the following bronchoscopy remained negative. Fungi were found post-transplantation in the lower respiratory tract specimens of 26 out of 31 (84%) patients, predominantly Candida albicans (20 patients) and Aspergillus fumigatus (16 patients). Mycelia characteristic of Candida spp. or Aspergillus spp. were found in necrotic tissue at the bronchial suture of nine patients. The mean duration of the 38 treatments was 3.6+/-2.6 months (range, 0.5-12 months). After a median follow-up of 16 (range, 0-48) months, two cases of extended ulcerative and pseudo membranous Aspergillus fumigatus bronchitis were observed and healed under itraconazole treatment. In conclusion, pre-emptive azole therapy may be effective and well-tolerated in lung transplant patients where fungi are found in the airways or pleura.

Activation of human macrophages by mechanical ventilation in vitro

Positive-pressure mechanical ventilation supports gas exchange in patients with respiratory failure but is also responsible for significant lung injury. In this study, we have developed an in vitro model in which isolated lung cells can be submitted to a prolonged cyclic pressure-stretching strain resembling that of conventional mechanical ventilation. In this model, cells cultured on a Silastic membrane were elongated up to 7% of their initial diameter, corresponding to a 12% increase in cell surface. The lung macrophage was identified as the main cellular source for critical inflammatory mediators such as tumor necrosis factor-alpha, the chemokines interleukin (IL)-8 and -6, and matrix metalloproteinase-9 in this model system of mechanical ventilation. These mediators were measured in supernatants from ventilated alveolar macrophages, monocyte-derived macrophages, and promonocytic THP-1 cells. Nuclear factor-kappaB was found to be activated in ventilated macrophages. Synergistic proinflammatory effects of mechanical stress and molecules such as bacterial endotoxin were observed, suggesting that mechanical ventilation might be particularly deleterious in preinjured or infected lungs. Dexamethasone prevented IL-8 and tumor necrosis factor-alpha secretion in ventilated macrophages. Mechanical ventilation induced low levels of IL-8 secretion by alveolar type II-like cells. Other lung cell types such as endothelial cells, bronchial cells, and fibroblasts failed to produce IL-8 in response to a prolonged cyclic pressure-stretching load. This model is of particular value for exploring physical stress-induced signaling pathways, as well as for testing the effects of novel ventilatory strategies or adjunctive substances aimed at modulating cell activation induced by mechanical ventilation.