Pulmonary disease in patients with human immunodeficiency virus infection

Pulmonary disease is the most important cause of morbidity and mortality in patients infected with human immunodeficiency virus (HIV). All parts of the hospital system are expected to be involved in the diagnosis and treatment of HIV infected patients in the coming years. Many different processes cause pulmonary disease alone or in combination. Bilateral interstitial infiltrates are the most frequent chest x-ray abnormality and are most frequently caused by infection with Pneumocystis carinii. Cytomegalovirus, Mycobacterium tuberculosis, nonspecific interstitial pneumonitis and pulmonary Kaposi's sarcoma are the most important parts of the differential diagnosis. An aggressive approach to the diagnosis of pulmonary disease in this patient population is indicated in order to provide optimal care and assess new therapies.

Substance P receptor-mediated secretion of respiratory glycoconjugate from feline airways in vitro

The effect of substance P (SP) and other tachykinins on respiratory glycoconjugate (RGC) release was studied in a feline tracheal organ culture system. SP in concentrations of 10(-5) and 10(-6) M stimulated an increase in RGC release of 35 +/- 8% and 18.5 +/- 5%, respectively. The addition of the protease inhibitor aprotinin or the enkephalinase inhibitor thiorphan to the cultures had no effect on the baseline secretion of RGC but markedly potentiated the activity of SP. SP in the presence of aprotinin or thiorphan was active at 10(-8) -10(-9) M concentrations and was more potent at each concentration studied (in the presence of peptidase inhibitors). Among other tachykinins studied, only physalaemin in the presence of aprotinin had a clear stimulatory effect on RGC release at 10(-6) M concentration (26% +/- 5% increase above control, n = 4, p less than 0.02); kassinin, neurokinin A, and neurokinin B had little or no effect on RGC secretion in concentrations of 10(-6) M or less. Autoradiographic studies of [125I]SP binding revealed SP receptor expression in the submucosal glands of the feline trachea. [125I]SP binding was inhibited in the presence of excess unlabeled SP. We conclude that SP receptors are present in the feline tracheal submucosal glands and that binding to SP receptors results in RGC secretion.

Bronchoscopy of symptom free patients infected with human immunodeficiency virus for detection of pneumocystosis

No evidence of Pneumocystis carinii infection was found in eight symptom free patients who were positive for the human immunodeficiency virus and who underwent bronchoscopy, bronchoalveolar lavage, and brush biopsy. This suggests that the presence of Pneumocystis carinii in bronchoscopy material is likely to indicate pneumocystis infection.

The outcome of Pneumocystis carinii pneumonia in Danish patients with AIDS

A total of 100 consecutive patients with AIDS were evaluated for efficacy and safety of treatment and secondary prophylaxis directed against Pneumocystis carinii pneumonia (PCP). 89 episodes of PCP were recorded in 75 patients. 63 of the 75 patients (84%) with a first episode of PCP were discharged. Of 72 patients with a first episode of PCP who were initially treated with trimethoprim-sulfamethoxazole. 76% completed therapy successfully. Side effects were common, but generally mild and tolerated during continued treatment. 7/11 patients (64%) with a first episode of PCP who required mechanical ventilation were discharged. Long term prognosis for these patients was not worse than for patients who did not require mechanical ventilation. Relapse of PCP occurred in 3/50 patients (6%) during secondary prophylaxis, 160 mg trimethoprim and 800 mg sulfamethoxazole (TMP-SMZ) every 24 h, compared to 11/16 (69%) patients who were not receiving prophylaxis (p less than 0.00001). No patients discontinued prophylaxis because of side effects. It is concluded that for most patients with AIDS and PCP, treatment and secondary prophylaxis with TMP-SMZ is safe and effective.

Dexamethasone inhibits respiratory glycoconjugate secretion from feline airways in vitro by the induction of lipocortin (lipomodulin) synthesis

The effect of glucocorticoids on respiratory glycoconjugate (RGC) secretion was studied in a cat tracheal organ culture system. Dexamethasone (10(-5) to 10(-9) M) added to culture medium for 24 h caused a dose-related reversible inhibition of RCG of as much as 40% with a peak effect at 24 to 60 h after initiation of dexamethasone treatment. A monoclonal antilipocortin antibody added to the cultures blocked the inhibitory effect of dexamethasone on RGC secretion and accelerated the reversal of the dexamethasone effect after discontinuation of dexamethasone treatment. A control antibody without antilipocortin activity had no effect on RGC secretion or dexamethasone-induced inhibition of RGC secretion. Measurement of the concentration of lipocortin in airways revealed a 220% increase after treatment with dexamethasone for 24 h. We conclude that dexamethasone inhibits RGC secretion through the induction of lipocortin synthesis.

Dexamethasone reduces rat tracheal goblet cell hyperplasia produced by human neutrophil products

An experimental model leading to goblet cell hyperplasia was developed in order to examine the possible preventive effects of glucocorticosteroids. Human peripheral blood neutrophils were isolated and either freeze-thaw lysed or activated with serum opsonized zymosan. Supernatants from these neutrophil preparations were then instilled transorally into the tracheas of male Sprague-Dawley rats. After 7-35 days, the rats were sacrificed; the lower tracheas were excised, fixed in formalin, and stained with periodic acid-Schiff and alcian blue; and the goblet cells and total epithelial cells were counted. Supernatants from both lysed neutrophils and zymosan-activated neutrophils stimulated a 50% and 42% (respectively) increase in goblet cells after 3 weeks as compared to controls. Purified human neutrophil or porcine pancreatic elastase also caused goblet cell hyperplasia, while sham challenge, challenge with buffer, or challenge with lysates of human mononuclear cells failed to affect goblet cell number. The increase in goblet-cell number was maximal by three weeks and persisted through 35 days. Treatment of animals with glucocorticosteroids administered by the addition of dexamethasone to the drinking water (2 mg/l for 1 week followed by 0.2 mg/l for 2 weeks) ablated the goblet cell hyperplasia produced by neutrophil lysates or elastase alone. We conclude that goblet cell hyperplasia may be induced with insufflated neutrophil products and that this action can be inhibited by treatment with corticosteroids.

The role of eicosanoids in respiratory mucus hypersecretion

The role of eicosanoids in the excessive secretion of respiratory mucous glycoproteins (MGP) accompanying immediate hypersensitivity and inflammatory pulmonary states has only been addressed in the last few years. Three lines of evidence suggest that eicosanoids may participate in the physiologic regulation of MGP secretion as well as being capable of stimulating increased MGP production. First, inhibition of eicosanoid generation with corticosteroids or eicosatetraynoic acid (ETYA) reduces ongoing baseline MGP secretion while selective inhibition of prostaglandin production with nonsteroidal anti-inflammatory agents increases MGP release. Second, arachidonic acid and a variety of eicosanoids stimulate MGP secretion in vitro. In fact, several lipoxygenase pathway metabolites including hydroxyeicosatetraenoic acids (HETEs) and leukotrienes (LTC4 and LTD4) significantly increase MGP secretion in nanogram quantities. Third, a variety of pulmonary cells including airway epithelium, endothelial cells, mast cells, alveolar macrophages and neutrophilic leukocytes generate eicosanoids under conditions that would be encountered in clinical states in which mucus secretion occurs. Thus, mucus secretion during both normal and stimulated states would be influenced by eicosanoids. It seems likely that this eicosanoid-mucus secretion relationship is very important in all forms of asthma, but most particularly in aspirin-related asthma.