Richard M. Rose

Reduced binding and phagocytosis of Pneumocystis carinii by alveolar macrophages from persons infected with HIV-1 correlates with mannose receptor downregulation.

The macrophage mannose receptor, a pattern recognition molecule and component of innate immunity, mediates binding and phagocytosis of Pneumocystis carinii and likely represents an important clearance mechanism in the lungs of immunocompetent hosts. The purpose of this study was to examine the ability of alveolar macrophages from HIV-infected individuals to bind and phagocytose P. carinii, and to investigate the role of the macrophage mannose receptor in mediating this interaction. Compared with healthy individuals, alveolar macrophage phagocytosis of P. carinii from HIV+ persons was reduced up to 74% (P = 0.02), primarily reflecting a reduction in the number of organisms associated with each macrophage (P = 0.019). Furthermore, macrophages from HIV+ individuals demonstrated up to an 80% (P < 0.05) reduction in mannose receptor surface expression and endocytosis. Mannose receptor affinity was unaltered, and mRNA levels were modestly reduced (P < 0.05). Cells from HIV+ individuals with CD4(+) counts < 200 cells/mm3 (representing individuals at high clinical risk for P. carinii pneumonia) demonstrated the lowest levels of P. carinii phagocytosis and mannose receptor endocytosis. In vitro HIV infection of alveolar macrophages from healthy individuals reduced mannose receptor endocytosis to 53.2% (P < 0.05) and P. carinii binding and phagocytosis to 67.4% (P < 0.05) of control. Our studies suggest that HIV infection may alter innate immunity in the lungs, and that impaired alveolar macrophage mannose receptor-mediated binding and phagocytosis of P. carinii may contribute to the susceptibility of HIV-infected individuals to this opportunistic pulmonary pathogen.

Endobronchial involvement with non‐Hodgkin's lymphoma. A clinical–radiologic analysis

Based on experience with three cases of endobronchial non‐Hodgkins lymphoma and a review of cases previously reported, two patterns of lymphomatous involvement of airways are described. The Type 1 pattern is characterized by diffuse submucosal infiltrates occurring in the presence of intra‐ and extrathoracic lymphoma. In Type 2 cases, central airways are involved by a solitary mass in the absence of clinically apparent systemic lymphoma. The clinical–radiologic picture is characterized by signs of pneumonitis in Type 1 cases, while in Type 2 cases, signs of airway obstruction uniformly occur.

Pulmonary complications of orthotopic liver transplantation.

Pulmonary complications following orthotopic liver transplantation (OLT) were prospectively evaluated in 18 individuals transplanted at the New England Deaconess Hospital. Of sixteen patients who survived the immediate postoperative period, 12 (75%) sustained a pulmonary complication. Of these complications, 64% were noninfectious--whereas 22% were infectious, and 14% probably infectious. Six of eight documented infections were caused by viruses of the herpes group. In four cases of viral pneumonitis other pulmonary pathogens were isolated (fungi-3, protozoan-1, bacteria-1). Unlike noninfectious complications, pulmonary infections were associated with a fatal outcome in five of six patients who died after OLT. Pulmonary complications are frequent and serious occurrences after OLT, and contribute to both the morbidity and mortality of this procedure. Compared with pulmonary complications seen after transplantation of other organs, OLT was associated with a higher proportion of noninfectious complications but a similar spectrum of pulmonary infections.

Phytosterols are present in Pneumocystis carinii.

Although originally classified as a protozoan, Pneumocystis carinii is now considered to have fungal characteristics. Drugs typically used for the treatment of fungal infections target ergosterol. Because P. carinii is an important pathogen in AIDS and other immunocompromised patients, knowledge of the sterol content of this organism may be useful as a basis for developing new treatment strategies or for improving diagnosis. P. carinii organisms were harvested from infected rat lungs and were purified by filtration. Control preparations from uninfected animals were identically prepared. Lipids were extracted from the organisms and control preparations and were separated into neutral lipid, glycolipid, and phospholipid fractions by silicic acid chromatography. The neutral lipid fraction was further treated by alkaline hydrolysis and was analyzed by reversed-phase high-pressure liquid chromatography (HPLC), gas chromatography (GC), and GC-mass spectrometry (GC-MS). As shown by HPLC, the neutral lipid fraction from infected rats contained a minimum of six peaks, while in control preparations a single peak with a retention time identical to that of cholesterol was observed. The predominant sterol in these preparations was positively identified by GC-MS as cholesterol and constituted 80 to 90% of the total. The remaining peaks had relative retention times similar to those of phytosterols by both HPLC and GC, and the similarity of these sterols to those derived from plants and fungi was confirmed by MS. Ergosterol, however, was not present. These results provide further evidence for a close phylogenetic relationship between P. carinii and fungi and suggest that these sterols could be used as targets for drug development and for improving diagnosis.

Surfactant protein-A levels increase during Pneumocystis carinii pneumonia in the rat

In bronchoalveolar lavage (BAL) of human immunodeficiency virus (HIV)-infected patients with Pneumocystis carinii pneumonia and in lungs of glucocorticoid-immunosuppressed rats infected with P. carinii, surfactant phospholipid levels are reduced. However, levels of the surfactant-associated protein-A (SP-A) in BAL are 4-5 times higher than normal in patients with P. carinii pneumonia. In this study, we examined the effects of glucocorticoid immunosuppression and P. carinii infection on SP-A messenger ribonucleic acid (mRNA) and protein levels in rat lungs. Rats were immunosuppressed by adding dexamethasone to their drinking water and were infected with P. carinii by intratracheal instillation of the organism. SP-A was measured by enzyme-linked immunosorbent assay (ELISA) and SP-A mRNA by hybridization of Northern blots with an SP-A complementary deoxyribonucleic acid (cDNA) probe. There was a severalfold increase in SP-A protein and mRNA levels in uninfected glucocorticoid-treated rats. However, contrary to what has been reported with the surfactant-associated lipids, SP-A mRNA and protein levels in P. carinii-infected animals were significantly higher than those found in the uninfected, immunosuppressed animals. Our results demonstrate that SP-A increases, probably as a result of elevated mRNA levels, in immunosuppressed rats with P. carinii infection and are consistent with our findings in HIV-positive patients with P. carinii pneumonia.

Cytokine activation of antibacterial activity in human pulmonary macrophages: Comparison of recombinant interferon-γ and granulocyte-macrophage colony-stimulating factor

We examined the ability of two recombinant human cytokines, granulocyte-macrophage colony-stimulating factor (rHu-GM-CSF) and interferon-gamma (rHu-IFN-gamma) to activate antibacterial mechanisms in human pulmonary macrophages (PM) and peripheral blood monocytes (PBM). Growth of Legionella pneumophila (LP) was assessed in PM or PBM which had been exposed to either rHu-IFN-gamma (500-1000 u/ml) or rHu-GM-CSF (1 to 10,000 u/ml). In both PM and PBM exposed to 500 u/ml rHu-IFN-gamma, growth of LP was reduced compared to cells exposed to media alone. By comparison, exposure of these cell types to rHu-GM-CSF had no detectable effect on bacterial replication. In order to investigate potential mechanisms accounting for this observation, the effect of these cytokines on the hydrogen peroxide (H2O2)-releasing capacity of cells was studied. Exposure of PM and PBM to rHu-IFN-gamma (500 to 1000 u/ml) resulted in increased production of H2O2 triggered by phorbol myristate acetate; when subjected to the same experimental conditions, rHu-GM-CSF-exposed cells exhibited no increase in H2O2 production. To further clarify the role of rHu-IFN-gamma-induced augmentation of oxidative metabolism on cellular inhibition of bacterial growth, an amount of catalase capable of completely neutralizing extracellular H2O2 was added to cells before and during infection. This did not abrogate the antibacterial activity of rHu-IFN-gamma. These studies demonstrate that rHu-IFN-gamma but not rHu-GM-CSF is capable of augmenting the capacity of PM and PBM to restrict LP growth. These data suggest that the antibacterial activity of rHu-IFN-gamma in this system may involve oxidative as well as nonoxidative mechanisms.

Solitary nodular sarcoidosis

Three patients, each with a solitary lung nodule consisting of sarcoid tissue, are described. With the exception of one case where a submandibular lymph node was palpable, clinical and pathological involvement was limited to the thorax and the prognosis was highly favourable. In spite of atypical features, the absence of other causes of granulomatous inflammation suggests that these patients had sarcoidosis. What factors account for limited granulomatous reaction in this form of sarcoidosis are unknown. Previous use of corticosteroids and an age of over 40 years are two possible causes suggested by these cases.

Diminished Perception of Inspiratory-Resistive Loads in Insulin-Dependent Diabetics

Diabetes mellitus is known to be associated with impaired perception of sensory input from organs such as the heart. To determine whether diabetics have a diminished ability to perceive respiratory sensations, we compared the abilities of patients with insulin-dependent diabetes (n = 17) and nondiabetic controls (n = 13) to detect inspiratory-resistive loads. The subjects were evaluated as they breathed through a tube-manifold apparatus with resistance that was varied randomly. They indicated whenever they perceived increased resistance to inspiration. The threshold for detecting added inspiratory resistance was expressed as a fraction of the background resistance of the subject plus that of the apparatus. This fraction, known as the Weber fraction, was 0.53 +/- 0.19 (mean +/- SD) in diabetics with neuropathy, 0.38 +/- 0.24 in diabetics without neuropathy, and 0.29 +/- 0.15 in nondiabetic controls. The differences in the mean value of the Weber fraction among the three groups were significantly different from zero (F = 4.57, P less than 0.025). There was not a significant correlation between the Weber fraction and age, degree of autonomic dysfunction, pulmonary function, cigarette smoking, or degree of diabetic control. The Weber fraction correlated with the duration of diabetes (r = 0.57, P less than 0.02). We conclude that patients with insulin-dependent diabetes may have an impaired ability to perceive inspiratory-resistive loads. This increased threshold for the perception of respiratory sensations may lead to delayed recognition of pulmonary disease in diabetics.

An acidic lymphokine distinct from interferon-γ inhibits the replication of herpes simplex virus in human pulmonary macrophages

Supernatants from concanavalin A-stimulated human peripheral blood mononuclear cells were fractionated by gel filtration and isoelectric focusing. A fraction with an isoelectric point of 2.2-3.3 containing macrophage migration inhibition factor activity inhibited the replication of herpes simplex virus type 1 in human pulmonary macrophages and U937 cells. This fraction did not inhibit the replication of herpes simplex virus in human fibroblasts. Moreover, the ability of this lymphokine fraction to inhibit viral growth in macrophages was not neutralized by antibody against interferon-gamma. These findings identify a macrophage specific antiviral lymphokine which is distinct biochemically and immunologically from interferon-gamma.

The HIV core protein p24 inhibits interferon-γ-induced increase of HLA-DR and cytochrome b heavy chain mRNA levels in the human monocyte-like cell line THP1

Cells from the human monocytic cell-line THP1 were incubated prior to activation with IFN-gamma or LPS with varying amounts of p24, the main product of the HIV gag gene and the major component of the virus core. The IFN-gamma-dependent increase of mRNA for HLA-DR and for the heavy chain of cytochrome b was markedly decreased by p24 but not by gp120. This effect was abrogated by anti-p24 antibodies. On the other hand, preincubation of THP1 cells with p24 did not affect the accumulation of the LPS-dependent mRNA for TNF alpha and IL1-beta. These results indicate that p24 at concentrations similar to those found in the serum of HIV-infected individuals specifically affects IFN-gamma-induced activation markers.