Minor salivary gland biopsy to detect primary Sjogren syndrome in patients with interstitial lung disease

PURPOSES

To describe a cohort of patients who presented with interstitial lung disease (ILD) of unknown cause, features of primary Sjögren syndrome (pSS), and a positive minor salivary gland biopsy (MSGB).

METHODS

Thirty-eight patients with ILD evaluated at our center underwent an MSGB to confirm a diagnosis of pSS. All of the samples were reviewed by pathologists experienced in the evaluation of salivary gland histology. We defined a positive MSGB finding as a lymphocyte focus score of >1.

RESULTS

At presentation, all patients had ILD, and symptoms of cough and dyspnea. None had a definable connective tissue disease (CTD) or known cause for their ILD. Thirteen patients (34%) had positive MSGB findings. Of these, the median age was 61 years (age range, 33 to 75 years); 7 patients (54%) were women; 8 patients (62%) had a smoking history; and 10 patients (77%) had sicca symptoms. In all patients, a thoracic high-resolution CT scan evaluation demonstrated bibasilar, peripheral-predominant, ground-glass, and reticular opacities. Four patients (31%) were negative for both antinuclear autoantibody (ANA) and rheumatoid factor (RF) autoantibody, and three patients (23%) were negative for ANA, RF, Sjögren syndrome (SS)-A, and SS-B autoantibodies. No patients experienced any complications from the MSGB. The identification of underlying pSS did not affect the management of ILD in these patients.

CONCLUSIONS

Confirming a diagnosis of pSS-related ILD by performing MSGB allows for a more precise CTD classification. This study provides evidence that CTD may exist subclinically, and longitudinal studies are needed to determine whether identifying occult CTD impacts on management, longitudinal changes in lung function, or survival.

Compartmentalized expression of c-FLIP in lung tissues of patients with idiopathic pulmonary fibrosis

Increased apoptosis of alveolar epithelial cells and impaired apoptosis of myofibroblasts have been linked to the pathogenesis of idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP). Fas, a death receptor of the TNF-receptor superfamily, has been implicated in apoptosis of both cell types, though the mechanisms are poorly understood. The goals of this study were: (1) to examine the localization of Fas-associated death-domain-like IL-1beta-converting enzyme inhibitory protein (c-FLIP), an NF-kappaB-dependent regulator of Fas-signaling, in lung tissues from IPF/UIP patients and control subjects; and (2) to compare c-FLIP expression with epithelial cell and myofibroblast apoptosis, proliferation, and NF-kappaB activation. c-FLIP expression was restricted to airway epithelial cells in control lung tissues. In contrast, in patients with IPF/UIP, c-FLIP was also expressed by alveolar epithelial cells in areas of injury and fibrosis, but was absent from myofibroblasts in fibroblastic foci and from alveolar epithelial cells in uninvolved areas of lung tissue. Quantification of apoptosis and proliferation revealed an absence of apoptotic or proliferating cells in fibroblastic foci and low levels of apoptosis and proliferation by alveolar epithelial cells. Quantification of NF-kappaB expression and nuclear translocation revealed strong staining and translocation in alveolar epithelial cells and weak staining and minimal nuclear translocation in myofibroblasts. These findings suggest that: (1) c-FLIP expression is induced in the abnormal alveolar epithelium of patients with IPF/UIP, (2) the resistance of myofibroblasts to apoptosis in patients with IPF/UIP occurs independently of c-FLIP expression, and (3) increased NF-kappaB activation and c-FLIP expression by the alveolar epithelium may be linked.

Neprilysin null mice develop exaggerated pulmonary vascular remodeling in response to chronic hypoxia

Neprilysin is a transmembrane metalloendopeptidase that degrades neuropeptides that are important for both growth and contraction. In addition to promoting carcinogenesis, decreased levels of neprilysin increases inflammation and neuroendocrine cell hyperplasia, which may predispose to vascular remodeling. Early pharmacological studies showed a decrease in chronic hypoxic pulmonary hypertension with neprilysin inhibition. We used a genetic approach to test the alternate hypothesis that neprilysin depletion increases chronic hypoxic pulmonary hypertension. Loss of neprilysin had no effect on baseline airway or alveolar wall architecture, vessel density, cardiac function, hematocrit, or other relevant peptidases. Only lung neuroendocrine cell hyperplasia and a subtle neuropeptide imbalance were found. After chronic hypoxia, neprilysin-null mice exhibited exaggerated pulmonary hypertension and striking increases in muscularization of distal vessels. Subtle thickening of proximal media/adventitia not typically seen in mice was also detected. In contrast, adaptive right ventricular hypertrophy was less than anticipated. Hypoxic wild-type pulmonary vessels displayed close temporal and spatial relationships between decreased neprilysin and increased cell growth. Smooth muscle cells from neprilysin-null pulmonary arteries had increased proliferation compared with controls, which was decreased by neprilysin replacement. These data suggest that neprilysin may be protective against chronic hypoxic pulmonary hypertension in the lung, at least in part by attenuating the growth of smooth muscle cells. Lung-targeted strategies to increase neprilysin levels could have therapeutic benefits in the treatment of this disorder.

The cancer paradigm of severe pulmonary arterial hypertension

The plexiform lesions of severe pulmonary arterial hypertension (PAH) are similar in histologic appearance, whether the disease is idiopathic or secondary. Both forms of the disease show actively proliferating endothelial cells without evidence of apoptosis. Here, we discuss the pathobiology of the atypical, angioproliferative endothelial cells in severe PAH. The concept of the endothelial cell as a "quasi-malignant" cell provides a new framework for antiproliferative, antiangiogenic therapy in severe PAH.

Pulmonary arterial hypertension from a pediatric perspective

This review of pediatric pulmonary arterial hypertension provides a framework within which to view pulmonary hypertension in children. Classification schemes, including the latest recommendations from the World Health Organization, are discussed, and the histopathology of severe pulmonary hypertension is reviewed. New information is provided regarding idiopathic and familial forms of the disease. Specific childhood etiologies, including persistent pulmonary hypertension of the newborn and congenital heart disease, are reviewed. Additionally, we examine the role of collagen vascular diseases, portal hypertension, and viruses in the pathogenesis of severe pulmonary arterial hypertension.

Clinically significant interstitial lung disease in limited scleroderma: histopathology, clinical features, and survival

PURPOSES

To evaluate the pathologic patterns, clinical features, and survival among subjects with scleroderma (ie, systemic sclerosis [SSc]) and clinically significant interstitial lung disease (ILD) evaluated at an ILD center.

METHODS

Retrospective cohort study of all SSc patients who had been referred for further evaluation of ILD and had undergone surgical lung biopsy. Clinical data were abstracted by review of the medical record, and lung biopsy specimens were reviewed and classified according to current pathologic criteria.

RESULTS

All patients presented with significant respiratory symptoms. Twenty-two of 27 subjects had surgical lung biopsy-proven ILD, and 5 subjects had miscellaneous non-ILD patterns. Of those subjects with ILD, 64% (14 of 22 subjects) had a nonspecific interstitial pneumonia (NSIP) pathologic pattern (fibrotic NSIP, 13 subjects; cellular NSIP, 1 subject), and 36% (8 of 22 subjects) had the usual interstitial pneumonia (UIP) pattern. Subjects with NSIP were younger (median age, 42 vs 58 years, respectively; p = 0.003), but no differences were noted in pulmonary physiology (FVC: NSIP group, 52% predicted; UIP group, 65% predicted; p = 0.22; diffusing capacity of the lung for carbon monoxide: NSIP group, 40% predicted; UIP group, 42% predicted; p = 1.0). All patients had limited skin involvement. The Scl-70 antibody was absent among those assessed (NSIP group, 0 of 10 subjects; UIP group, 0 of 7 subjects). All patients were treated with cytotoxic therapy. The median survival time for those with NSIP was 15.3 years (5,596 days) compared with 3 years (1,084 days) for those with UIP (p = 0.07 [log-rank test]).

CONCLUSIONS

In SSc patients with limited cutaneous disease and clinically significant ILD, fibrotic NSIP and UIP are the predominant pathologic patterns. Those with the UIP pattern of disease had a trend toward shorter survival time.

Abrogation of anti-inflammatory transcription factor LKLF in neutrophil-dominated airways

This is the first report to describe a role for Lung Kruppel-like Factor (LKLF or KLF2) in inflammatory airways diseases. In the present study, we identify that LKLF is constitutively expressed in the small airways of normal lungs; however, its expression disappears in severe airway diseases, such as cystic fibrosis (CF) and chronic obstructive pulmonary disease. LKLF from primary airway epithelial cells inhibits NF-kappaB-driven transcription induced by Pseudomonas aeruginosa 7-fold, but is down-regulated in the presence of TNF-alpha and activated human neutrophils. As a constitutively expressed protein, LKLF inhibits release of a key pro-inflammatory chemokine, IL-8, from airway epithelia. Its expression by lung epithelial cells is enhanced in the presence of TNF blockade. Thus, cytokine-mediated inhibition of LKLF by neutrophils may contribute to ongoing recruitment by promoting IL-8 release from airway epithelia. We conclude that, in neutrophil-dominated airway environments, such as that seen in CF, reduced LKLF activity releases a brake on pro-inflammatory cytokine production and thereby may contribute to the persistent inflammatory responses seen in CF airway disease.

Chronic hypersensitivity pneumonitis: CT features comparison with pathologic evidence of fibrosis and survival

PURPOSE

To retrospectively compare in patients with chronic hypersensitivity pneumonitis (HP) the computed tomographic (CT) imaging features suggestive of fibrosis with pathologic evidence of fibrosis at surgical lung biopsy and to compare a usual interstitial pneumonia (UIP) pattern at CT with survival.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained for this study, which was HIPAA compliant. Twenty-six patients (15 women, 11 men; age range, 37-76 years) with chronic HP had their surgical lung biopsy results reviewed by two pathologists for the presence of fibrosis. Two radiologists systematically reviewed the CT scans. The two radiologists were blinded to all clinical information, including pathologic diagnosis, patient information, and outcomes. The combination of a subpleural reticular pattern and lower zone predominance was considered a UIP pattern. CT findings were compared with the histopathologic presence of fibrosis, physiologic parameters, symptoms, and survival. The chi(2) or Fisher exact test (each two-tailed) was used to compare nominal and ordinal variables. A t test (with unequal variances) was used to compare continuous variables. The log-rank procedure was used to compare Kaplan-Meier survival curves.

RESULTS

Fifteen patients had fibrotic HP at biopsy, and 11 had nonfibrotic HP. Patients with fibrotic HP had more extensive reticular pattern and were more likely to have traction bronchiectasis, honeycombing, and a UIP pattern than those with nonfibrotic HP (P = .015, P = .007, P = .007, respectively). Although the presence of histologic fibrosis was associated with decreased survival (P = .003), the CT features were not associated with decreased survival.

CONCLUSION

CT findings of extensive reticular pattern, traction bronchiectasis, and honeycombing are closely related to the presence of histologic fibrosis in chronic HP.

Pulmonary stromal-derived factor-1 expression and effect on neutrophil recruitment during acute lung injury

The severe and protracted inflammation that characterizes acute lung injury (ALI) is driven by the ongoing recruitment of neutrophils to the lung. Although much of the cytokine signaling responsible for the initial phase of ALI has been elaborated, relatively little is known about the mechanisms governing the recruitment of neutrophils from the bone marrow to the lung in the later period of this disease. Given its previously described chemoattractant effects on marrow neutrophils, we investigated whether stromal-derived factor-1 (SDF-1) (CXCL12) might participate in this later phase of recruitment. Using immunohistochemistry to examine both banked human lung specimens from patients with ALI and lungs from mice with LPS-induced pneumonitis, we found that pulmonary SDF-1 expression increases during ALI. We further determined that both lung SDF-1 protein expression and mRNA expression rise in a delayed but sustained pattern in this mouse model and that the major source of the increase in expression appears to be the lung epithelium. Lastly, we found that expression of the SDF-1 receptor CXCR4 rises in a similar temporal pattern on neutrophils in both the blood and airspace of LPS-injured mice and that Ab-mediated SDF-1 blockade significantly attenuates late but not early pulmonary neutrophilia in this model. These results implicate SDF-1 in neutrophil recruitment to the lung in the later period of acute lung injury and suggest a novel role for this cytokine in coordinating the transition from the inflammatory response to the initiation of tissue repair.

Plexiform-like lesions and increased tissue factor expression in a rat model of severe pulmonary arterial hypertension

Severe pulmonary arterial hypertension (PAH) occurs in idiopathic form and in association with diverse diseases. The pathological hallmarks are distal smooth muscle hypertrophy, obliteration of small pulmonary arteriole lumens, and disorganized cellular proliferation in plexiform lesions. In situ thrombosis is also observed. A detailed understanding of the disease progression has been hampered by the absence of an animal model bearing all the pathological features of human disease. To create a model with these characteristics, we gave young (200-g) rats monocrotaline 1 wk following left pneumonectomy; controls with vehicle treatment or sham operation were also studied. In experimental rats, pulmonary arteries had distal smooth muscle hypertrophy and proliferative perivascular lesions. The lesions had a plexiform appearance, occurred early in disease development, and were composed of cells expressing endothelial antigens. Three-dimensional microangiography revealed severe vascular pruning and disorganized vascular networks. We found that expression of tissue factor (TF), the membrane glycoprotein that initiates coagulation, facilitates angiogenesis, and mediates arterial injury in the systemic circulation, was increased in the pulmonary arterioles and plexiform-like lesions of the rats. TF was also heavily expressed in the vessels and plexiform lesions of humans with pulmonary arterial hypertension. We conclude that plexiform-like lesions can be reproduced in rats, and this model will facilitate experiments to address controversies about the role of these lesions in PAH. Increased TF expression may contribute to the prothrombotic diathesis and vascular cell proliferation typical of human disease.

VEGF-R blockade causes endothelial cell apoptosis, expansion of surviving CD34+ precursor cells and transdifferentiation to smooth muscle-like and neuronal-like cells

Severe pulmonary hypertension (PH) is characterized by complex precapillary arteriolar lesions, which contain phenotypically altered smooth muscle (SM) and endothelial cells (EC). We have demonstrated that VEGF receptor blockade by SU5416 {3-[(2,4-dimethylpyrrol-5-yl)methylidenyl]-indolin 2-one} in combination with chronic hypoxia causes severe angioproliferative PH associated with arterial occlusion in rats. We postulate that endothelial-mesenchymal transdifferentiation can take place in the occlusive lesions and that endothelium-derived mesenchymal cells can further differentiate toward a SM phenotype. To examine this hypothesis, we incubated human pulmonary microvascular endothelial cells (HPMVEC) with SU5416 and analyzed these cells utilizing quantitative-PCR, immunofluorescent staining and flow cytometry analysis. In vitro studies in HPMVEC demonstrated that SU5416 suppressed PGI2S gene expression while potently inducing COX-2, VEGF, and TGF-beta1 expression; and caused transdifferentiation of mature vascular endothelial cells (defined by Dil-ac-LDL, Lectin and Factor VIII) to SM-like (as defined by expression of alpha-SM actin) "transitional" cells, coexpressing both endothelial and SM markers. SU5416 expanded the number of CD34 and/or c-kit positive cells and caused transdifferentiation of CD34 positive cells but not negative cells. In conclusion, our data show that SU5416 generated a selection pressure that killed some EC and expanded progenitor-like cells to transdifferentiate to SM-like and neuronal-like cells.

Lung disease and PKCs

The lung offers a rich opportunity for development of therapeutic strategies focused on isozymes of protein kinase C (PKCs). PKCs are important in many cellular responses in the lung, and existing therapies for pulmonary disorders are inadequate. The lung poses unique challenges as it interfaces with air and blood, contains a pulmonary and systemic circulation, and consists of many cell types. Key structures are bronchial and pulmonary vessels, branching airways, and distal air sacs defined by alveolar walls containing capillaries and interstitial space. The cellular composition of each vessel, airway, and alveolar wall is heterogeneous. Injurious environmental stimuli signal through PKCs and cause a variety of disorders. Edema formation and pulmonary hypertension (PHTN) result from derangements in endothelial, smooth muscle (SM), and/or adventitial fibroblast cell phenotype. Asthma, chronic obstructive pulmonary disease (COPD), and lung cancer are characterized by distinctive pathological changes in airway epithelial, SM, and mucous-generating cells. Acute and chronic pneumonitis and fibrosis occur in the alveolar space and interstitium with type 2 pneumocytes and interstitial fibroblasts/myofibroblasts playing a prominent role. At each site, inflammatory, immune, and vascular progenitor cells contribute to the injury and repair process. Many strategies have been used to investigate PKCs in lung injury. Isolated organ preparations and whole animal studies are powerful approaches especially when genetically engineered mice are used. More analysis of PKC isozymes in normal and diseased human lung tissue and cells is needed to complement this work. Since opposing or counter-regulatory effects of selected PKCs in the same cell or tissue have been found, it may be desirable to target more than one PKC isozyme and potentially in different directions. Because multiple signaling pathways contribute to the key cellular responses important in lung biology, therapeutic strategies targeting PKCs may be more effective if combined with inhibitors of other pathways for additive or synergistic effect. Mechanisms that regulate PKC activity, including phosphorylation and interaction with isozyme-specific binding proteins, are also potential therapeutic targets. Key isotypes of PKC involved in lung pathophysiology are summarized and current and evolving therapeutic approaches to target them are identified.

Respiratory Bronchiolitis-Interstitial Lung Disease

BACKGROUND

The clinical and physiologic features of respiratory bronchiolitis (RB)-interstitial lung disease (ILD) have been previously described; however, the natural history and outcome have not been systematically evaluated. The majority of published reports consider RB-ILD to be a nonprogressive ILD that clinically improves with smoking cessation and antiinflammatory treatment. In this study, we sought to determine the outcome of RB-ILD patients with and without smoking cessation and with and without corticosteroid therapy.

METHODS

Thirty-two RB-ILD cases confirmed by surgical lung biopsy were identified from a prospectively enrolled cohort of subjects with ILD. Initial and follow-up data on symptoms, physiology, treatment, and outcome were collected and analyzed.

RESULTS

Kaplan-Meier analysis revealed that at least 75% of RB-ILD patients survived > 7 years after diagnosis. Clinical improvement occurred in only 28% of cases, and physiologic improvement occurred in 10.5% of cases. One patient died of progressive ILD, and two patients died of non-small cell lung cancer. While physiologic improvement was limited to those who had ceased smoking, corticosteroids and/or other immunosuppressive therapy had little effect on symptoms or physiology.

CONCLUSIONS

This study shows that prolonged survival is common in RB-ILD. However, symptomatic and physiologic improvement occurs in only a minority of patients, and neither smoking cessation nor immunosuppressive therapy is regularly associated with clinically significant benefit.

Organizing pneumonia and lymphoplasmacytic inflammation predict treatment response in idiopathic pulmonary fibrosis

AIMS

To identify individual histopathological features within usual interstitial pneumonia pattern that predict responsiveness to immunosuppressive therapy.

METHODS AND RESULTS

Fifty-six retrospectively confirmed usual interstitial pneumonia pattern surgical lung biopsy specimens from subjects with idiopathic pulmonary fibrosis treated with corticosteroid and cytotoxic therapy were included. Eleven prospectively defined histopathological features were evaluated by two expert pulmonary pathologists. Regression analysis identified predictors of response to therapy, as defined by the change in percent predicted forced vital capacity over 6 months. Additional end-points were change in dyspnoea score over 6 months, and survival time. Improvement in percent predicted forced vital capacity was associated with lymphoplasmacytic inflammation, while worsening of percent predicted forced vital capacity was associated with the presence of organizing pneumonia and fibroblast foci. Worsening dyspnoea was associated with fibroblast foci. Survival time was associated with age and baseline percent predicted forced vital capacity, but not with any individual histopathological feature.

CONCLUSIONS

In pathological usual interstitial pneumonia pattern, the presence of lymphoplasmacytic inflammation predicts responsiveness to immunomodulatory therapy, while airspace organization predicts lack of response.

Lung diseases in patients with common variable immunodeficiency: chest radiographic, and computed tomographic findings

OBJECTIVE

To evaluate chest radiographic and computed tomographic (CT) findings of lung disease related to common variable immunodeficiency.

METHODS

Thirty-five chest radiographs and 30 CT scans of 46 patients were assessed. Lung parenchymal abnormalities that were evaluated included airspace consolidation, ground-glass attenuation, nodules, bronchiectasis, and air trapping.

RESULTS

On CT, ground-glass attenuation and nodules were the most frequent findings, observed in 60% (n = 18/30) and 83% (n = 25/30), respectively. Three major CT patterns were identified: airway disease (n = 13), nodules (n = 8), and parenchymal opacification (n = 6). All 13 patients with airway disease showed centrilobular opacities. One patient with peribronchial nodules showed lymphoid interstitial pneumonia, and 1 with randomly distributed nodules showed noncaseating granulomas. Patients with a CT pattern of parenchymal opacification showed lower lung predominance; surgical biopsies showed organizing pneumonia in 1 patient and lymphoid interstitial pneumonia with nonnecrotizing granulomas in another.

CONCLUSIONS

Common variable immunodeficiency is associated with 3 major CT patterns: airway disease, nodules, and parenchymal opacification.

Fibroblast foci are not discrete sites of lung injury or repair: the fibroblast reticulum

BACKGROUND

Usual interstitial pneumonia (UIP), the pathologic correlate of idiopathic pulmonary fibrosis, contains characteristic discrete areas of fibroblasts, myofibroblasts, and newly formed collagen, termed "fibroblast foci." These lesions are argued to represent isolated sites of recurrent acute lung injury and suggested to be the mechanism of disease progression. We hypothesized that, rather than isolated, these lesions are part of an organized neoplasm.

METHODS

Morphometric analysis of pentachrome-stained histologic sections of UIP was performed. Using point-counting technique on serial sections, fibroblast foci, arteries, and macrophage clusters were identified and we determined their individual "connectiveness" by estimating the Euler number. Two-dimensional micrographs were collated into a three-dimensional array from which a visual three-dimensional reconstruction could be constructed. Clonality analysis was performed using human androgen receptor gene methylation assay.

RESULTS

Blood vessels show significant connectivity with a Euler number of 2, whereas macrophage clusters exhibited no connectivity. The fibroblast foci showed a high level of interconnection with Euler numbers ranging from 19 to 39. The computer generated three-dimensional models provide a visual confirmation of this connectiveness. Human androgen receptor gene methylation assay analysis of the foci showed balanced methylation consistent with polyclonality.

CONCLUSIONS

The fibroblast foci of UIP are the leading edge of a complex reticulum that is highly interconnected and extends from the pleura into the underlying parenchyma. It is a reactive, rather than a malignant, process.

HIV-1 Nef is associated with complex pulmonary vascular lesions in SHIV-nef-infected macaques

RATIONALE

HIV-infected patients with pulmonary arterial hypertension have histologic manifestations that are indistinguishable from those found in patients with idiopathic pulmonary arterial hypertension. In addition, the role of pleiotropic viral proteins in the development of plexiform lesions in HIV-related pulmonary hypertension (HRPH) has not been explored. Simian immunodeficiency virus (SIV) infection of macaques has been found to closely recapitulate many of the characteristic features of HIV infection, and thus hallmarks of pulmonary arterial hypertension should also be found in this nonhuman primate model of HIV.

OBJECTIVES

To determine whether pulmonary arterial lesions were present in archived SIV-infected macaque lung tissues from Johns Hopkins University and two National Primate Research Centers.

METHODS

Archived macaque and human lung sections were examined via immunohistochemistry for evidence of complex vascular lesions.

RESULTS

Complex plexiform-like lesions characterized by lumenal obliteration, intimal disruption, medial hypertrophy, thrombosis, and recanalized lumena were found exclusively in animals infected with SHIV-nef (a chimeric viral construct containing the HIV nef gene in an SIV backbone), but not in animals infected with SIV. The mass of cells in the lesions were factor VIII positive, and contained cells positive for muscle-specific and smooth muscle actins. Lung mononuclear cells were positive for HIV Nef, suggesting viral replication. Endothelial cells in both the SHIV-nef macaques and patients with HRPH, but not in patients with idiopathic pulmonary arterial hypertension, were also Nef positive.

CONCLUSIONS

The discovery of complex vascular lesions in SHIV-nef- but not SIV-infected animals, and the presence of Nef in the vascular cells of patients with HRPH, suggest that Nef plays a key role in the development of severe pulmonary arterial disease.

Pulmonary capillary hemangiomatosis: an immunohistochemical analysis of vascular remodeling

QUESTION OF STUDY: Pulmonary capillary hemangiomatosis (PCH) is an extremely rare cause of severe pulmonary hypertension. It is characterized histologically by exuberant proliferation of capillaries that often invade alveolar septae, bronchial walls, and pleura. Expression of vascular remodeling markers in PCH is not known.

MATERIALS/PATIENTS AND METHODS

Using antibodies directed against vascular remodeling markers known to be abnormally expressed in plexiform lesions of idiopathic pulmonary hypertension, we performed the first detailed immunohistochemical analysis of the lungs in a patient with PCH. -

RESULTS

As in plexiform lesions, the PCH lesions have increased expression of markers associated with cellular proliferation and angiogenesis such as vascular endothelial growth factor and MiB-1. In contrast to plexiform lesions, the PCH lesions retain markers of cell growth suppression such as peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and caveolin-1.

ANSWER TO QUESTION

This study suggests that the aberrant endothelial cells that lead to the characteristic lesions of PCH and idiopathic pulmonary hypertension are distinct.

Sarcoidois and pulmonary hypertension--a case report

We report a case of severe pulmonary hypertension associated with sarcoidosis with a unique histopathological presentation. This 43-year old obese patient first presented eight years ago with complaint of dyspnea on exertion for four years and was diagnosed as primary pulmonary hypertension. Six years later, a skin biopsy performed on her left cheek to rule out squamous cell carcinoma revealed sarcoidosis. The patient was then put on steroid therapy and subsequently, the oxygen saturation improved transiently, although the mean pulmonary arterial pressure did not show improvement. The patient was then started on prostacyclin infusion and was hemodynamically stable, but the pulmonary artery pressures worsened. The patient died from complications subsequent to a diagnostic procedure. An autopsy limited to the lungs was performed and routinely prepared hematoxylin and eosin stained sections were examined. Immunohistochemical stains for CD31, factor VIII-related antigen and muscle-specific actin were performed on selected sections. The diagnosis of sarcoidosis was confirmed. However, pulmonary fibrosis was not seen. The granulomas surrounded medium- and small-sized pulmonary arteries, but did not destroy the vessel wall. Plexiform lesions indicating severe pulmonary hypertension were identified in pulmonary arteries, which were not involved by granulomas.

Morphologic changes in explanted lungs after prostacyclin therapy for pulmonary hypertension

Prostacyclin (PGI2) causes vasodilation and inhibition of platelet aggregation in vivo. PGI2 is also postulated to affect pulmonary vascular remodeling, at least partly through anti-proliferative effect via PGI2 receptor (PGIR). However, the mechanism(s) of action by which (PGI2) exerts its therapeutic effect is still not clear despite clear clinical benefit seen in severe pulmonary hypertension (PH) patients. We performed a histopathologic and morphometric study on the explanted lung tissues from PGI2-treated patients prior to lung transplantation (n = 9), in an attempt to elucidate morphologic changes associated with PGI2 treatment. Explanted lungs from PH patients without PGI2 treatment were examined as the control (n = 11). We also studied the possible differences in PGIR expression between the treated and untreated groups by immunohistochemical method. Seven out of 9 treated patients showed moderate to severe bronchial and perivascular inflammation, as opposed to only 1 such case in the control group. Five out of 9 treated cases showed moderate to severe alveolar edema with or without evidence of old hemorrhage, in contrast to only 1 case showing moderate alveolar edema in control patients. Morphometry did not reveal any significant difference between the two groups either in the % thickness of intima, media, or adventitia or in the density of plexiform lesions. Immunostain also failed to demonstrate any notable difference in PGIR expression. In conclusion, PGI2-treated cases revealed more pronounced pulmonary alveolar edema and inflammation, but no morphological evidence of altered vascular remodeling or PGIR expression after PGI2 therapy.

Loss of caveolin and heme oxygenase expression in severe pulmonary hypertension

Caveolae are cell plasma membrane microdomains implicated in organizing and concentrating many signaling molecules. In the lung, caveolae are in endothelium, smooth muscle, fibroblasts, and pneumocytes. Caveolin is the main structural protein of caveolae. Caveolin 1 is down-regulated in transformed cells and may be a tumor suppressor protein. Caveolin 2 is coexpressed and hetero-oligomerizes with caveolin 1. Because the cells of the plexiform lesions in severe pulmonary hypertension (PH) are phenotypically altered, we wondered whether these cells lack caveolin. We now demonstrate by immunolocalization that while caveolin is expressed in lung endothelial, smooth-muscle, and alveolar septal cells, its expression is absent or decreased in plexiform lesions and in some muscularized precapillary arterioles. In contrast, Western blot analysis of total lung extracts from patients with severe PH shows no significant reduction in caveolin. Similar to the human lung tissue, a rat model of severe PH demonstrates absent-to-decreased caveolin expression in the complex vascular lesions. Additionally, it appears that caveolin and heme oxygenase 1 (HO-1) [a heat shock protein] are co-expressed since HO-1 expression parallels caveolin expression in vascular lesions. We propose that loss of caveolin expression in the cells of the complex vascular lesions in severe PH reflects the proliferating and apoptosis-resistant nature of these cells.

Apoptosis of pulmonary microvascular endothelial cells stimulates vascular smooth muscle cell growth

We have previously hypothesized that the development of severe angioproliferative pulmonary hypertension is associated with not only initial endothelial cell (EC) apoptosis followed by the emergence of apoptosis-resistant proliferating EC but also with proliferation of vascular smooth muscle cells (VSMC). We have demonstrated that EC death results in the selection of an apoptosis-resistant, proliferating, and phenotypically altered EC phenotype. We postulate here that the initial apoptosis of EC induces the release of mediators that cause VSMC proliferation. We cultured EC in an artificial capillary CellMax system designed to simulate the highly efficient functions of the human capillary system. We induced apoptosis of microvascular EC using shear stress and the combined VEGF receptor (VEGFR-1 and -2) inhibitor SU-5416. Flow cytometry for the proliferation marker bromodeoxyuridine showed that serum-free medium conditioned by apoptosed EC induced proliferation of VSMC, whereas serum-free medium conditioned by nonapoptosed EC did not. We also show that medium conditioned by apoptosed EC is characterized by increased concentrations of transforming growth factor (TGF)-beta1 and VEGF compared with medium conditioned by nonapoptosed EC and that TGF-beta1 blockade prevented the proliferation of cultured VSMC. In conclusion, EC death induced by high shear stress and VEGFR blockade leads to the production of factors, in particular TGF-beta1, that activate VSMC proliferation.

Lymphoid interstitial pneumonia: clinical features, associations and prognosis

Lymphoid interstitial pneumonia (LIP) is rare and its clinical course incompletely described. The aim of this study was to examine the clinical features, associations and prognosis of surgical lung biopsy-proven LIP. The study group consisted of 15 subjects encountered over a 14-yr period. The majority of subjects were females (n = 11) and the mean age was 47 yrs (range 17-78 yrs). Underlying systemic immune disorders were frequent, including Sjögren's syndrome (n = 8), rheumatoid arthritis, systemic lupus erythematosus, polymyositis, common variable immunodeficiency and dysproteinaemia. Only three patients were classified as "idiopathic". Presenting symptoms were dominated by dyspnoea and cough. Restrictive physiology, reduced diffusion capacity (62.5+/-18.4% predicted) and bronchoalveolar lavage lymphocytosis (30.5+/-29.1% pred) were noted. Thirteen patients received corticosteroid therapy. Of the nine whose response could be assessed, four showed clinical improvement and four were stable. Overall, median survival was 11.5 yrs. Of the seven patients who died, respiratory problems were the primary cause of death in three. Conversion to lymphoma was not identified. In conclusion, histopathological lymphoid interstitial pneumonia is commonly associated with immune system dysregulation, with idiopathic lymphoid interstitial pneumonia being extremely rare. Clinical stability or improvement with corticosteroids can be expected; however, survival remains impaired.

Human lung project: evaluating variance of gene expression in the human lung

Nondiseased tissue is an important reference for microarray studies of pulmonary disease. We obtained 23 single lungs from multiorgan donors at time of procurement. Donors varied in age, sex, smoking history, and ethnicity. Lungs were dissected into upper and lower lobe peripheral sections for RNA extraction. Microarray analysis was performed using Affymetrix Hu-133 Plus 2.0 arrays. We observed that the relative variability of gene expression increased rapidly from technical (lowest), to regional, to population (highest). In addition, age and sex have measurable effects on gene expression. Gene expression variability is heterogeneously distributed among biologic categories. We conclude that gene expression variability is greater between individuals than within individuals and that population variability is the most important factor in the study design of microarray experiments of the human lung. Classes of genes with high population variability are biologically important and provide a novel perspective into lung physiology and pathobiology. Our study represents the first comprehensive analysis of nondiseased lung tissue. The generation of this robust dataset has important implications for the design and implementation of future comparative expression analysis with pulmonary disease states.