Recent Publications by CFE Educators

Mast cells (MCs) are abundant in fibrotic tissue, although their role in fibrogenesis remains obscure. Recent studies suggest MCs may produce basic fibroblast growth factor (bFGF). To evaluate the hypothesis that MC bFGF contributes to the fibrotic response in human interstitial lung disease, we studied lung tissue, bronchoalveolar lavage fluid and serum in 1) idiopathic pulmonary fibrosis, 2) chronic beryllium disease and sarcoidosis, 3) control subjects with no disease or who were beryllium sensitized with normal lung histology. Diseased subjects underwent clinical assessments to stage disease severity. We determined that most bFGF+ cells in lung interstitium are MCs and are most abundant in idiopathic pulmonary fibrosis. Distribution of bFGF+ MCs matched that of extracellular matrix deposition and correlated with the extent of fibrosis morphometrically. Only one bFGF isoform (17.8 kd) was found in idiopathic pulmonary fibrosis and chronic beryllium disease lung tissues and interacted with heparin-like molecules in the lung. Using a human MC line, we verified that MCs express bFGF mRNA and protein that localizes to cytoplasmic granules. Clinically, bFGF concentrations in bronchoalveolar lavage fluid and serum were highest in disease states and correlated with bronchoalveolar lavage cellularity and severity of gas exchange abnormalities, supporting a role for MC bFGF in the pulmonary fibrotic response and its clinical consequence.

The 39-kDa receptor-associated protein (RAP) is a receptor antagonist that inhibits ligand interactions with the receptors that belong to the low density lipoprotein receptor gene family. Our previous studies have demonstrated that RAP interacts with the low density lipoprotein receptor-related protein (LRP) within the endoplasmic reticulum and prevents premature interaction of ligands with the receptor. To analyze whether RAP is also involved in the folding of LRP during receptor biosynthesis, we generated anchor-free, soluble minireceptors that represent each of the four putative ligand-binding domains of LRP (SLRP1, -2, -3, and -4, corresponding to the clusters with 2, 8, 10, and 11 cysteine-rich complement-type repeats, respectively). When these SLRPs were overexpressed by cell transfection, only SLRP1 was secreted. Little or no secretion was observed for SLRP2, -3, and -4. However, when RAP cDNA was cotransfected with SLRP2, -3, and -4 cDNAs, each of these SLRPs was secreted. The cellular retention of SLRPs in the absence of RAP coexpression appeared to be a result of the formation of SDS-resistant, oligomeric aggregates observed under nonreducing conditions. Such oligomers of the SLRPs likely resulted from formation of intermolecular disulfide bonds since they were reduced to monomers when analyzed under reducing conditions. The oligomers were formed not only among molecules of a given SLRP, but also between different SLRPs. The role of RAP in the process of LRP folding was shown by the reduction in aggregated SLRP oligomers upon RAP coexpression. A similar role of RAP in preventing the aggregation of newly synthesized receptor was also observed using membrane-containing minireceptor of LRP. Coimmunoprecipitation and ligand binding studies demonstrated that RAP binds avidly to SLRP2, -3, and -4, but not to SLRP1. These results suggest that these interactions may be important for proper folding of LRP by ensuring the formation of proper intradomain, but not intermolecular or interdomain, disulfide bonds. Thus, our results strongly suggest that, in addition to the prevention of premature binding of ligands to LRP, RAP also plays an important role in receptor folding.

Diffuse panbronchiolitis (DPB), an important cause of progressive obstructive lung disease in the Far East, represents a distinctive sinobronchial syndrome with typical radiologic and histologic features. We have identified DPB in five citizens of the United States, three with histologic confirmation, who have never traveled to the Far East. There were four men and one woman, whose ages ranged from 46 to 75 yr at the time of diagnosis. All had a prior history of chronic sinusitis and presented with cough, dyspnea, and sputum production. Three were never smokers and two were current smokers. Pulmonary function testing revealed severe airflow limitation (the FEV1 ranging from 22% to 56% of predicted), and overdistention. All patients had high-resolution computed tomographic (HRCT) scans indicating centrilobular nodules with adjoining thickened and dilated bronchioles. In the three patients in whom open lung biopsy was performed, there was bronchiolocentric infiltration of lymphocytes, plasma cells, and foamy macrophages. Three patients remain alive and are being treated with chronic macrolide therapy. The clinical, radiographic, and histologic features of these patients closely resemble those described in Japanese patients. DPB must be considered in the differential diagnosis of sinopulmonary syndromes, bronchiolitis, and cryptic cases of obstructive lung disease among United States citizens, since therapy now offers an improved prognosis.

UNLABELLED

STUDY OBJECTIVES AND DESIGN: Arterial vasoconstriction is thought to play a role in the etiology of cocaine-induced cardiovascular complications, but little is known about the immediate effects of cocaine on the thoracic aorta and coronary arteries. To examine these effects, we used transesophageal echocardiography to examine the thoracic aorta and coronary arteries before and immediately after intravenous (i.v.) cocaine (1.2 mg/kg) in 15 subjects.

MEASUREMENTS AND RESULTS

Immediately after cocaine infusion, average heart rate, systolic BP, and double product were increased compared with baseline (22%, 15%, 35%, respectively). There was no significant change in the diameters of the ascending aorta (27.5 vs 27.1 mm; p = 0.85), the descending aorta (19.8 vs 20.4 mm; p = 0.62), or the left main coronary artery (4.3 vs 4.7 mm; p = 0.15). However, there was a trend for an increase in coronary blood flow immediately after cocaine (226 vs 309 mL/min; p = 0.10).

CONCLUSIONS

We conclude that in the 15 subjects studied, there was no evidence of thoracic aorta of coronary artery vasoconstriction immediately after i.v. cocaine. Instead, we found that the diameters of the thoracic aorta and the left main coronary artery were unchanged, and that there was a trend for augmentation of coronary artery blood flow.

Tolerance to the analgesic effects of morphine results in part from the development of a compensatory response in neurons that express the opioid receptor or of neural circuits in which those neurons participate. According to this formulation, withdrawal of morphine results in an overshoot of several neuronal properties because of the unopposed action of the compensatory response system. To identify the population of spinal cord neurons that underlies this state, we monitored expression of Fos-like immunoreactivity, after naltrexone-precipitated abstinence in normal and morphine-tolerant rats. After daily (five days) implantation of morphine or placebo pellets, the rats received an injection of saline or naltrexone and behavior was monitored for 1 h. The rats were then killed, their spinal cords removed and 50-microns transverse sections of the lumbar cord were immunostained with a rabbit polyclonal antiserum directed against Fos. Naltrexone injection in the placebo group did not increase spinal cord Fos expression. Naltrexone-precipitated abstinence resulted in an increase in Fos expression at all levels of the spinal cord; the greatest increase and densest staining was in laminae I through VI. Importantly, when withdrawal was precipitated in anesthetized rats, we recorded a significant reduction in Fos expression, particularly in laminae III through VI, but there was persistent expression in the superficial dorsal horn, particularly in lamina I. These results suggest that spinal cord nociresponsive neurons are sensitized during the development of tolerance. This sensitization is unmasked by the administration of naltrexone and is manifested by fos induction in laminae I/II in awake or anesthetized withdrawing animals. The underlying mechanisms of tolerance development may be similar to those that underlie injury-induced central sensitization and hyperalgesia.

In previous studies, we reported that supraspinally administered DAMGO, a mu-opioid agonist, produces a dose-related, naloxone-reversible inhibition of formalin-evoked pain behaviors and spinal cord Fos-like immunoreactivity (FLI) in the rat spinal cord. Although these results support the hypothesis that activation of supraspinal mu-opioid receptors produces antinociception by increasing the activity of bulbospinal inhibitory pathways, other studies suggest that supraspinal morphine decreases rather than increases descending inhibitory control. In the present study, we specifically examined the effect of intracerebroventricular (i.c.v.) injection of morphine in the rat. Supraspinal morphine produced a dose-related, naloxone-reversible inhibition of both formalin-evoked behaviors nd spinal cord FLI. Although the magnitude of the antinociception produced by i.c.v. morphine in the formalin test was significantly correlated with the numbers of FLI neurons in the spinal cord, the lowest dose of i.c.v. morphine tested (0.70 nmol) produced a significant reduction of FLI in the superficial laminae without producing behavioral antinociception, which is consistent with our hypothesis that noxious stimulus-evoked Fos expression in the superficial laminae is a poor predictor of the magnitude of pain behavior. These data support the hypothesis that the antinociceptive effects of supraspinally administered morphine result from an increase in descending inhibitory control.

Dyspnea with exertion is nearly always present in patients with pulmonary lymphangioleiomyomatosis, but the mechanisms underlying exercise impairment have not been well defined. Spirometry, lung volumes, lung mechanics, and exercise physiology were performed on a cohort of 16 patients. We determined the relative contribution of airflow limitation, gas exchange abnormalities, and pulmonary vascular abnormalities to the exercise performance achieved. The patients had normal TLC and Vtg, but RV was elevated in 88% of the subjects. A moderate to severe obstructive pattern was present in 69% of the subjects, and the DLCO was reduced, often markedly, in 81% of the subjects. Exercise performance was limited (work load, 68% +/- 6) with abnormalities of ventilatory function and gas exchange present. Strong correlations between overall exercise performance (percent predicted VO2max and maximal work load achieved) and indices of airflow and vascular involvement were present. Poor exercise performance was due primarily to ventilatory limitation. The etiology of this ventilatory limitation appears twofold. First, subjects had a reduced ventilatory ceiling because of airflow limitation. Second, subjects demonstrated an excessive ventilatory response as a result of increased dead-space ventilation thought to be due to disease-associated cystic changes and associated pulmonary vascular dysfunction or destruction.