Faculty Bibliography

STUDY OBJECTIVE: To test the hypothesis that individuals chronically noncompliant with antituberculous chemotherapy are vectors for ongoing transmission of the disease in the community. DESIGN: Cohort study. SETTING: A large public hospital with a tuberculosis detention unit for patients with repeated and prolonged nonadherence to therapy. PATIENTS: Mycobacterium tuberculosis isolates from patients confined on the detention unit were obtained from the hospital's mycobacteriology laboratory. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: A standardized IS6110-based Southern blot hybridization protocol was used to genotype M tuberculosis isolates recovered from patients confined on the detention unit at the hospital. Each DNA fingerprint pattern was compared with the IS6110-fingerprint database at the Public Health Research Institute Tuberculosis Center, which has archived fingerprint patterns from over 2,500 M tuberculosis isolates collected from New York City patients in the past 5 years. Eighty percent of available isolates from detained patients belonged to an identifiable DNA fingerprint cluster, suggesting an epidemiologic link between the detainees and other New York City tuberculosis patients. CONCLUSIONS: Chronic noncompliance with therapy is associated with ongoing spread of tuberculosis in the community. Aggressive measures, including detention, for the small number of recalcitrant, noncompliant patients may interrupt a chain of transmission and contribute to a decline in the spread of tuberculosis in urban areas

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) is associated with substantial morbidity, despite drug therapy. Interferon-gamma, a cytokine produced mainly by CD4 T lymphocytes, can activate alveolar macrophages, important effector cells in host immunity against Mycobacterium tuberculosis. We investigated safety and tolerability of aerosolised interferon-gamma in patients with MDR-TB, and assessed its efficacy in terms of sputum-smear grades. METHODS: We did an open-label trial of aerosol interferon-gamma given to five patients with smears and cultures positive for pulmonary MDR-TB, despite documented adherence to therapy. The patients received aerosol interferon-gamma 500 micrograms three times a week for 1 month. Safety and tolerability were assessed, and, as well as routine clinical assessments, sputum samples for smear and culture were collected at entry and weekly. Computed tomography scans of the chest were done at baseline and after therapy ended. FINDINGS: Interferon-gamma was well tolerated by all patients. In all five, bodyweight stabilised or increased. Sputum acid-fast-bacillus smears became negative in all patients, and the time to positive culture increased (from 17 to 24 days, not significant), which suggested that the mycobacterial burden had decreased. The size of cavitary lesions was reduced in all patients, 2 months after treatment had ended. INTERPRETATION: Preliminary data suggest that aerosol interferon-gamma is a well-tolerated treatment that may be useful as adjunctive therapy in patients with MDR-TB who are otherwise not responding well to therapy

Since apoptosis is observed in tuberculous granulomata, we investigated the molecular mechanisms underlying the apoptotic pathway in an in vitro model of mycobacterial infection of mononuclear phagocytes. We postulated that Mycobacterium tuberculosis could trigger the apoptotic pathway in macrophages, resulting in death of the microorganism by modulating the expression of bcl-2, bax, bcl-xL, and bcl-xS. We found that the mRNA of bcl-2, an inhibitor of apoptosis, was downregulated in peripheral blood monocytes (PBM) between 2 and 6 h following infection with M. bovis BCG or induction with heat-killed M. tuberculosis H37Ra. Western analysis showed a downregulation of the Bcl-2 protein, with a half-life of 24 h. At the same time points, there was no change in the expression of Bax or Bcl-xS, inducers of apoptosis, but Bcl-xL, another inhibitor of apoptosis, was minimally upregulated by BCG. To determine if apoptosis could be a mechanism for growth inhibition in vivo, we obtained alveolar macrophages by bronchoalveolar lavage from involved sites in patients with active pulmonary tuberculosis. Using the TUNEL (terminal deoxynucleotidyltransferase mediated nick end labeling) technique, we observed significantly more apoptosis in involved segments of five tuberculosis patients (14.8 +/- 1.9%) than in those of normal controls (<1%, P = 0.02) or in uninvolved segments (4.3 +/- 0.9%, P < 0.05). We conclude that apoptosis of mononuclear phagocytes induced by M. tuberculosis occurs in vivo and that in an in vitro model of mycobacterial infection, apoptosis may be mediated by downregulation of Bcl-2

SETTING: A large public hospital in New York City. OBJECTIVE: To determine the prevalence of tuberculosis infection and disease in a cohort of indigent persons in New York. DESIGN: Persons seeking social services at any of five community-based organizations in New York City were screened for tuberculosis infection using tuberculin skin testing and a symptom questionnaire. Skin test or symptom positive persons were referred to the Bellevue Hospital Chest Clinic for a chest radiograph and medical evaluation. After this evaluation, patients were classified into a diagnostic category (e.g. tuberculosis infection, tuberculosis disease, no evidence of tuberculosis infection or disease). RESULTS: Of 651 persons screened, 591 (91%) completed the initial evaluation. The tuberculosis infection prevalence for the entire cohort was 41% (95% Confidence Interval [CI], 37% to 45%). Risk factors for infection included residence in a congregate setting, drug use, and birth outside the United States. Human immunodeficiency virus (HIV) infection was not a risk factor for infection. Eleven cases of active tuberculosis were also detected (disease prevalence of 1.7%, 95% CI, 0.85% to 3%). Most of the patients with active tuberculosis had documented HIV infection or clear risk factors for HIV. CONCLUSION: We conclude that tuberculosis infection and disease remain common in populations characterized by poor housing conditions, drug use, and HIV infection. Linking a major medical provider with community-based organizations is an effective means to provide highly targeted screening services to a population at serious risk for disease acquisition and transmission

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by an excessive accumulation of surfactant lipids and proteins in the alveolar space. In mice with a homozygous deletion of granulocyte macrophage-colony stimulating factor (GM-CSF), their phenotype mimics PAP. To evaluate whether the knockout mouse model mimics human disease, we evaluated GM-CSF expression in alveolar macrophages from a patient with PAP. We performed multiple whole lung lavages on a patient with PAP, and cultured BAL cells in the presence or absence of LPS. In contrast to the GM-CSF knockout mouse, human BAL cells from a patient with PAP expressed mRNA for GM-CSF following LPS stimulation. However, similar to the knockout mouse, GM-CSF protein release from BAL cells was undetectable with or without LPS. BAL cells from normal human controls released GM-CSF in abundance after LPS stimulation. In BAL cells from the patient with PAP, neutralization of interleukin-10 (IL-10) by anti-IL-10 antibody, resulted in enhanced GM-CSF production. Thus, alveolar macrophages from a PAP lung have deficient GM-CSF production analogous to the GM-CSF knockout mice; in contrast, human cells from a PAP lung have an intact GM-CSF gene. This case report illustrates an important difference between the knockout mouse model of PAP and the human disease

The increase in multidrug-resistant tuberculosis and high mortality among those co-infected with HIV-1 necessitates new therapeutic approaches directed at Mycobacterium tuberculosis. We hypothesized that a dominant-negative mutation in the DNA-dependent RNA polymerase gene would inhibit transcription of all genes by blocking access of the wild-type enzyme to promoters. An evolutionarily invariant lysine was substituted with arginine by site-directed mutagenesis in the rpoB gene. The dominant-negative rpoB gene product inhibited a transposon-derived kanamycin-resistance gene in both M. smegmatis and M. tuberculosis H37Rv, leading to growth inhibition of the mycobacteria on solid media containing kanamycin. The dominant-negative mutant rpoB gene is a potential suicide gene especially for the treatment of multidrug-resistant tuberculosis once a delivery strategy is also developed

Transforming growth factor beta (TGF-beta), a multifunctional cytokine and growth factor, plays a key role in scarring and fibrotic processes because of its ability to induce extracellular matrix proteins and modulate the growth and immune function of many cell types. These effects are important in inflammatory disorders with fibrosis and cancer. The asbestos-related diseases are characterized by fibrosis in the lower respiratory tract and pleura and increased occurrence of lung cancer and mesothelioma. We performed immunohistochemistry with isoform-specific antibodies to the three TGF-beta isoforms on 16 autopsy lungs from Quebec, Canada, asbestos miners and millers. There was increased immunolocalization of all three TGF-beta isoforms in the fibrotic lesions of asbestosis and pleural fibrosis. The hyperplastic type II pneumocytes contained all three isoforms. By contrast, there was differential spatial immunostaining for the TGF-beta isoforms in malignant mesothelioma, with TGF-beta 1 in the stroma but TGF-beta 2 in the tumor cells. These data are consistent with an important role for TGF-beta in accumulation of extracellular matrix and cell proliferation in asbestos-related diseases

Chemokines are a superfamily of small related protein molecules that are secreted by a variety of cells and that have, among their diverse biological properties, the ability to recruit a wide range of immune cells to the sites of infection and disease. Chemokines are secreted in response to bacterial, viral, parasitic, and mycobacterial pathogens. Our recent progress in understanding the patterns of chemokine secretion in response to various pathogens and their impact on disease manifestations is likely to lead to the development of novel therapeutic approaches for a variety of serious infections