David R. Park

Fas (CD95) Induces Proinflammatory Cytokine Responses by Human Monocytes and Monocyte-Derived Macrophages

Fas (CD95, APO-1) is regarded as the prototypical cell death receptor of the TNFR superfamily. Fas-induced apoptosis is generally considered to be a noninflammatory process, contributing to the silent resolution of immune and inflammatory responses. However, accumulating evidence indicates that Fas may also induce cellular activation signals. We hypothesized that Fas could activate proinflammatory cytokine responses by normal human monocytes and macrophages. Monocytes were isolated by negative immunoselection from the PBMC fraction of venous blood from healthy volunteers, and monocyte-derived macrophages were cultivated in vitro. Both monocytes and monocyte-derived macrophages released TNF-α and IL-8 following Fas ligation, and conditioned medium from Fas-activated monocytes and macrophages induced the directed migration of neutrophils in a chemotaxis assay. Fas-induced monocyte cytokine responses were associated with monocyte apoptosis, nuclear translocation of NF-κB, and cytokine gene expression and were blocked by caspase inhibition but not by inhibition of IL-1β signaling. In contrast, Fas-induced macrophage cytokine responses occurred in the absence of apoptosis and were caspase independent, indicating maturation-dependent differences in the Fas signaling pathways that lead to proinflammatory cytokine induction. Rather than contributing to the resolution of inflammation, Fas ligation on circulating monocytes and tissue macrophages may induce proinflammatory cytokine responses that can initiate acute inflammatory responses and tissue injury.

The Etiology of Community‐Acquired Pneumonia at an Urban Public Hospital: Influence of Human Immunodeficiency Virus Infection and Initial Severity of Illness

In a prospective study, the etiology of community-acquired pneumonia (CAP) was investigated among consecutive patients admitted to an academic, urban public hospital in Seattle. The study population was uniquely young, was predominantly male, and had high rates of homelessness, cigarette smoking, alcoholism, injection drug use, and human immunodeficiency virus (HIV) infection. Leading causes of CAP among HIV-negative patients were aspiration, followed by Streptococcus pneumoniae, Legionella species, and Mycoplasma pneumoniae. Among HIV-positive patients, Pneumocystis carinii, Mycobacterium tuberculosis, S. pneumoniae, and M. pneumoniae were the most common etiologic agents. Severe CAP was associated with typical bacterial infections and aspiration pneumonia but not Legionella infection among HIV-negative patients and with Pseudomonas aeruginosa infections among HIV-positive patients. These findings emphasize the need to tailor empirical antibiotic therapy according to local patient populations and individual risk factors and highlight the importance of recognizing underlying HIV infection in patients who are hospitalized with CAP.

Environment or host?: A case-control study of risk factors for Mycobacterium avium complex lung disease.

RATIONALE Mycobacterium avium complex lung disease is an increasingly common and chronically debilitating problem. Several host traits have been suggested or confirmed as risk factors. Potential environmental and behavioral risk factors have also been proposed. Few have been evaluated in comparative studies. OBJECTIVES To determine if aerosol-generating activities in the home and garden, features of the home water supply, or several pulmonary and immune-compromising conditions are associated with Mycobacterium avium complex lung disease. METHODS Cases were recruited from academic medical centers and by informal referrals from nonuniversity practices in Washington and Oregon. Control subjects were recruited by random-digit dialing and matched to cases by age, sex, and partial telephone number. Associations were measured as odds ratios (OR) estimated using conditional logistic regression. MEASUREMENTS AND MAIN RESULTS Known and potential risk factors were measured by in-home interview. Fifty-two matched pairs were studied. Six of 12 examined host traits were associated with disease, including history of chronic obstructive pulmonary disease (OR, 10; 95% confidence interval [CI], 1.2-80), pneumonia hospitalization (OR, 3.4; 95% CI, 1.1-11), and steroid use (OR, 8; 95% CI, 1.6-41). In contrast, 11 of the 14 aerosol-generating activities and all five features of home water supply studied bore little or no association with disease. CONCLUSIONS Aerosol-generating activities seem not to be risk factors for Mycobacterium avium complex lung disease in HIV-negative adults, but prior lung disease and immune-suppressing drugs seem to be associated with susceptibility.

Proteomic and Computational Analysis of Bronchoalveolar Proteins during the Course of the Acute Respiratory Distress Syndrome

RATIONALE Acute lung injury causes complex changes in protein expression in the lungs. Whereas most prior studies focused on single proteins, newer methods allowing the simultaneous study of many proteins could lead to a better understanding of pathogenesis and new targets for treatment. OBJECTIVES The purpose of this study was to examine the changes in protein expression in the bronchoalveolar lavage fluid (BALF) of patients during the course of the acute respiratory distress syndrome (ARDS). METHODS Using two-dimensional difference gel electrophoresis (DIGE), the expression of proteins in the BALF from patients on Days 1 (n = 7), 3 (n = 8), and 7 (n = 5) of ARDS were compared with findings in normal volunteers (n = 9). The patterns of protein expression were analyzed using principal component analysis (PCA). Biological processes that were enriched in the BALF proteins of patients with ARDS were identified using Gene Ontology (GO) analysis. Protein networks that model the protein interactions in the BALF were generated using Ingenuity Pathway Analysis. MEASUREMENTS AND MAIN RESULTS An average of 991 protein spots were detected using DIGE. Of these, 80 protein spots, representing 37 unique proteins in all of the fluids, were identified using mass spectrometry. PCA confirmed important differences between the proteins in the ARDS and normal samples. GO analysis showed that these differences are due to the enrichment of proteins involved in inflammation, infection, and injury. The protein network analysis showed that the protein interactions in ARDS are complex and redundant, and revealed unexpected central components in the protein networks. CONCLUSIONS Proteomics and protein network analysis reveals the complex nature of lung protein interactions in ARDS. The results provide new insights about protein networks in injured lungs, and identify novel mediators that are likely to be involved in the pathogenesis and progression of acute lung injury.

The biological activity of FasL in human and mouse lungs is determined by the structure of its stalk region

Acute lung injury (ALI) is a life-threatening condition in critically ill patients. Injury to the alveolar epithelium is a critical event in ALI, and accumulating evidence suggests that it is linked to proapoptotic Fas/FasL signals. Active soluble FasL (sFasL) is detectable in the bronchoalveolar lavage (BAL) fluid of patients with ALI, but the mechanisms controlling its bioactivity are unclear. We therefore investigated how the structure of sFasL influences cellular activation in human and mouse lungs and the role of oxidants and proteases in modifying sFasL activity. The sFasL in BAL fluid from patients with ALI was bioactive and present in high molecular weight multimers and aggregates. Oxidants generated from neutrophil myeloperoxidase in BAL fluid promoted aggregation of sFasL in vitro and in vivo. Oxidation increased the biological activity of sFasL at low concentrations but degraded sFasL at high concentrations. The amino-terminal extracellular stalk region of human sFasL was required to induce lung injury in mice, and proteolytic cleavage of the stalk region by MMP-7 reduced the bioactivity of sFasL in human cells in vitro. The sFasL recovered from the lungs of patients with ALI contained both oxidized methionine residues and the stalk region. These data provide what we believe to be new insights into the structural determinants of sFasL bioactivity in the lungs of patients with ALI.

Factors associated with mortality in patients with tuberculosis

BackgroundKnown risk factors for death following a diagnosis of tuberculosis may not be applicable to current U.S. cases. We evaluated the factors associated with all-cause mortality in patients with tuberculosis in Washington State.MethodsUsing data from the Tuberculosis Information Management System of Washington State, we conducted a cohort study of all residents diagnosed with tuberculosis from 1993 through 2005. Death from any cause was ascertained through the Washington State Death Certificate Data Files. Proportional hazards models were used to estimate the independent effect on all-cause mortality of demographic, clinical, and behavioral characteristics.ResultsDuring a median follow-up of 6 years in 3451 patients treated for tuberculosis, there were 417 deaths. Mortality was independently associated with increasing age, male gender, HIV-coinfection, and U.S. birth. Within 1 year of tuberculosis diagnosis, treatment by a private provider and the use of directly observed therapy were also independently associated with increased mortality. In addition, an interaction term of private provider times directly observed therapy was also significantly associated with mortality.ConclusionsWe identified factors independently associated with increased all-cause mortality following a diagnosis of tuberculosis. The associations between mortality and provider type should be evaluated with more thorough adjustment for severity of illness, but suggest important directions for future research.

cDNA microarray analysis reveals fundamental differences in the expression profiles of primary human monocytes, monocyte-derived macrophages, and alveolar macrophages

We report the systematic use of large‐scale cDNA microarrays to study the gene expression profiles of primary human peripheral blood monocytes (MONO) in comparison with in vitro‐differentiated, M‐CSF‐induced MONO‐derived macrophages (MAC) and primary human alveolar MAC (AM), obtained by bronchoalveolar lavage from the lungs of normal volunteers. These studies revealed large‐scale differences in the gene expression profile between both MAC types (MAC and AM) and MONO. In addition, large differences were observed in the gene expression profiles of the two MAC types. Specifically, 21% of genes on the array (2904 out of 13,582) were differentially expressed between AM and MONO, and 2229 out of 13,583 probes were differentially expressed between MAC and AM. Our expression data show remarkable differences in gene expression between different MAC subpopulations and emphasize the heterogeneity of different MAC populations. This study underscores the need to scrutinize models of MAC biology for relevance to specific disease processes.

Mapping the lung proteome in cystic fibrosis.

The pathophysiology of cystic fibrosis (CF) lung disease remains incompletely understood. Novel mechanisms in the pathogenesis of CF lung disease may be discovered by studying the patterns of protein expression in bronchoalveolar lavage fluid (BALF). We used shotgun proteomics to analyze BALF samples from 8 CF and 4 control subjects. Differential protein expression between CF and control subjects was determined using spectral counting and statistical analysis. Using Gene Ontology analysis, we identified enriched biological modules and then applied network analysis to construct a protein interaction map in CF lung disease. Shotgun proteomics analysis of BALF identified hundreds of proteins whose differential enrichment or depletion robustly distinguished the CF phenotype from normal controls. Functional categorization and network analysis identified key processes, including the immune response and proteolytic activity that are known contributors to CF lung disease. Importantly, this approach also implicated abnormalities in previously unsuspected pathways, such as dysregulation of the complement system that may have critical roles in the pathogenesis of CF lung disease. By integrating shotgun proteomics with statistical and computational analyses, we have developed a promising approach to understand the pathophysiology of CF lung disease. Our approach should be applicable to a wide range of proteomics-based clinical research.

Long-Term Survival after Hospitalization for Community-Acquired and Healthcare-Associated Pneumonia

Background: Elderly patients surviving community-acquired pneumonia (CAP) have subsequent increased mortality. However, little is known regarding long-term survival in younger adults or those with healthcare-associated pneumonia (HCAP). Objectives: To identify factors associated with mortality and compare long-term survival in patients hospitalized with HCAP to that of patients with CAP. Methods: We determined survival after discharge as of December 2002 in a patient cohort admitted with pneumonia between June 1994 and May 1996. We used the Cox proportional hazard model to estimate differences in survival after controlling for confounders. Results: Of the 522 patients hospitalized with pneumonia, 457 survived to discharge. One hundred sixty-four patients (36%, 95% confidence interval, CI, 31–40%) were admitted with HCAP, while 293 (64%, 95% CI 60–69%) were admitted with CAP. Of the 181 deaths in the follow-up period, 70 occurred in patients under age 65 years admitted with HCAP (53% death rate, 95% CI 44–62%). Nineteen of these deaths (27%, 95% CI 17–39%) occurred in the absence of HIV infection. In patients under the age of 65 whose only risk factor for HCAP was treatment for pneumonia or hospitalization in the previous 90 days, 4 of 13 patients (31%, 95% CI 9–61%) died. Twenty percent (95% CI 15–26%) of patients under age 65 years admitted with CAP died during the follow-up. Conclusions: Admission for HCAP, and to a lesser degree CAP, is associated with increased long-term mortality even in young patients. Future studies are warranted to identify interventions to improve survival in this population.

Fentanyl-Induced Chest Wall Rigidity

Fentanyl and other opiates used in procedural sedation and analgesia are associated with several well-known complications. We report the case of a man who developed the uncommon complication of chest wall rigidity and ineffective spontaneous ventilation following the administration of fentanyl during an elective bronchoscopy. His ventilation was assisted and the condition was reversed with naloxone. Although this complication is better described in pediatric patients and with anesthetic doses, chest wall rigidity can occur with analgesic doses of fentanyl and related compounds. Management includes ventilatory support and reversal with either naloxone or a short-acting neuromuscular blocking agent. This reaction does not appear to be a contraindication to future use of fentanyl or related compounds. Chest wall rigidity causing respiratory compromise should be readily recognized and treated by bronchoscopists.