Robert Vassallo

Incidence and mortality of interstitial lung disease in rheumatoid arthritis: a population-based study.

OBJECTIVE Interstitial lung disease (ILD) has been recognized as an important comorbidity in rheumatoid arthritis (RA). We undertook the current study to assess incidence, predictors, and mortality of RA-associated ILD. METHODS We examined a population-based incidence cohort of patients with RA and a matched cohort of individuals without RA. All subjects were followed up longitudinally. The lifetime risk of ILD was estimated. Cox proportional hazards models were used to compare the incidence of ILD between cohorts, to investigate predictors, and to explore the impact of ILD on survival. RESULTS Patients with RA (n = 582) and subjects without RA (n = 603) were followed up for a mean of 16.4 and 19.3 years, respectively. The lifetime risk of developing ILD was 7.7% for RA patients and 0.9% for non-RA subjects. This difference translated into a hazard ratio (HR) of 8.96 (95% confidence interval [95% CI] 4.02-19.94). The risk of developing ILD was higher in RA patients who were older at the time of disease onset, in male patients, and in individuals with more severe RA. The risk of death for RA patients with ILD was 3 times higher than in RA patients without ILD (HR 2.86 [95% CI 1.98-4.12]). Median survival after ILD diagnosis was only 2.6 years. ILD contributed approximately 13% to the excess mortality of RA patients when compared with the general population. CONCLUSION Our results emphasize the increased risk of ILD in patients with RA. The devastating impact of ILD on survival provides evidence that development of better strategies for the treatment of ILD could significantly lower the excess mortality among individuals with RA.

Cigarette smoke extract suppresses human dendritic cell function leading to preferential induction of Th-2 priming

Dendritic cells (DC) are key regulators of immune responses. In the current study, we hypothesized that cigarette smoke-induced aberrance in DC function is an important mechanism by which smokers develop cancer, infection, and allergy—diseases common in smokers. We demonstrate that cigarette smoke extract (CSE) inhibits DC-mediated priming of T cells, specifically inhibiting the secretion of IFN-γ whereas enhancing the production of IL-4 in the MLR. Conditioning with CSE did not effect cytokine (IL-10, IL-6, or IL-12) production from immature DCs, but significantly inhibited IL-12p70 release by LPS-matured DCs. In contrast, IL-10 secretion by LPS-activated CSE-conditioned DCs was enhanced when compared with control DCs. CSE also induced cyclooxygenase-2 protein levels in maturing DCs and significantly augmented endogenous PGE2 release. Conditioning of DCs with CSE also suppressed LPS-mediated induction of CD40, CD80, and CD86, and suppressed maturation-associated CCR7 expression. Although CSE has been reported to induce apoptosis of fibroblasts and epithelial cells, the immunomodulatory effects observed with CSE were not due to diminished DC viability. The effects of CSE on DC function were not exclusively mediated by nicotine, because equivalent, or even higher concentrations of nicotine than those found in CSE, failed to suppress DC-induced T cell priming. These data provide evidence that soluble components extracted from cigarette smoke suppress key DC functions and favor the development of Th-2 immunity.

Revised classification of histiocytoses and neoplasms of the macrophage-dendritic cell lineages

The histiocytoses are rare disorders characterized by the accumulation of macrophage, dendritic cell, or monocyte-derived cells in various tissues and organs of children and adults. More than 100 different subtypes have been described, with a wide range of clinical manifestations, presentations, and histologies. Since the first classification in 1987, a number of new findings regarding the cellular origins, molecular pathology, and clinical features of histiocytic disorders have been identified. We propose herein a revision of the classification of histiocytoses based on histology, phenotype, molecular alterations, and clinical and imaging characteristics. This revised classification system consists of 5 groups of diseases: (1) Langerhans-related, (2) cutaneous and mucocutaneous, and (3) malignant histiocytoses as well as (4) Rosai-Dorfman disease and (5) hemophagocytic lymphohistiocytosis and macrophage activation syndrome. Herein, we provide guidelines and recommendations for diagnoses of these disorders.

Isolated Pneumocystis carinii Cell Wall Glucan Provokes Lower Respiratory Tract Inflammatory Responses

Macrophage-induced lung inflammation contributes substantially to respiratory failure during Pneumocystis carinii pneumonia. We isolated a P. carinii cell wall fraction rich in glucan carbohydrate, which potently induces TNF-α and macrophage-inflammatory protein-2 generation from alveolar macrophages. Instillation of this purified P. carinii carbohydrate cell wall fraction into healthy rodents is accompanied by substantial increases in whole lung TNF-α generation and is associated with neutrophilic infiltration of the lungs. Digestion of the P. carinii cell wall isolate with zymolyase, a preparation containing predominantly β-1,3 glucanase, substantially reduces the ability of this P. carinii cell wall fraction to activate alveolar macrophages, thus suggesting that β-glucan components of the P. carinii cell wall largely mediate TNF-α release. Furthermore, the soluble carbohydrate β-glucan receptor antagonists laminariheptaose and laminarin also substantially reduce the ability of the P. carinii cell wall isolate to stimulate macrophage-inflammatory activation. In contrast, soluble α-mannan, a preparation that antagonizes macrophage mannose receptors, had minimal effect on TNF-α release induced by the P. carinii cell wall fraction. P. carinii β-glucan-induced TNF-α release from alveolar macrophages was also inhibited by both dexamethasone and pentoxifylline, two pharmacological agents with potential activity in controlling P. carinii-induced lung inflammation. These data demonstrate that P. carinii β-glucan cell wall components can directly stimulate alveolar macrophages to release proinflammatory cytokines mainly through interaction with cognate β-glucan receptors on the phagocyte.

Asthma-related environmental fungus, Alternaria, activates dendritic cells and produces potent Th2 adjuvant activity.

Asthma is thought to result from dysregulated Th2-like airway inflammatory responses to the environment. Although the etiology of asthma is not fully understood in humans, clinical and epidemiological evidence suggest a potential link between exposure to environmental fungi, such as Alternaria, and development and/or exacerbation of asthma. The goal of this project was to investigate the mechanisms of airway Th2 responses by using Alternaria as a clinically relevant model for environmental exposure. Airway exposure of naive animals to an experimental Ag, OVA, or a common allergen, short ragweed pollen, induced no or minimal immune responses to these Ags. In contrast, mice developed strong Th2-like immune responses when they were exposed to these Ags in the presence of Alternaria extract. Extracts of other fungi, such as Aspergillus and Candida, showed similar Th2 adjuvant effects, albeit not as potently. Alternaria stimulated bone marrow-derived dendritic cells (DCs) to express MHC class II and costimulatory molecules, including OX40 ligand, in vitro. Importantly, Alternaria inhibited IL-12 production by activated DCs, and DCs exposed to Alternaria enhanced Th2 polarization of CD4+ T cells. Furthermore, adoptive airway transfer of DCs, which had been pulsed with OVA in the presence of Alternaria, showed that the recipient mice had enhanced IgE Ab production and Th2-like airway responses to OVA. Thus, the asthma-related environmental fungus Alternaria produces potent Th2-like adjuvant effects in the airways. Such immunogenic properties of certain environmental fungi may explain their strong relationships with human asthma and allergic diseases.

Nicotine and oxidative cigarette smoke constituents induce immune-modulatory and pro-inflammatory dendritic cell responses

Chronic airway inflammation is a cardinal feature of chronic obstructive pulmonary disease (COPD), a destructive cigarette smoke-induced lung disease. Although it is apparent that dendritic cells (DCs) are an important constituent of the chronic inflammatory cell influx found in airways of COPD patients, the functional roles of DCs in the pathogenesis of smoking-induced emphysema are unknown. We postulated that DCs activated by cigarette smoke constituents directly participate in the chronic inflammation that characterizes COPD airways. Concordant with this hypothesis, we observed that incubation of DCs with cigarette smoke extract (CSE), and chronic exposure of mice to cigarette smoke, both augmented the generation of neutrophilic chemokines by immature and lipopolysaccharide (LPS) or CD40L-matured DCs. The generation of interleukin-8 (CXCL8/IL-8) by human DCs conditioned with CSE was suppressed by the anti-oxidant n-acetyl cysteine (NAC), implying the involvement of oxidant sensitive pathways as a primary mechanism involved in the enhanced CXCL8/IL-8 generation. Cigarette smoke extract and nicotine also augment the production of secreted prostaglandin-E2 and intra-cellular cyclo-oxygenase-2 (COX-2) in maturing DCs. Whereas NAC suppressed production of CXCL8 by CSE-conditioned DCs, it augmented production of PGE2 and cellular COX-2 levels in maturing DCs. These studies indicate that the stimulation of DCs by cigarette smoke-induced oxidative stress and nicotine promote the generation of pro-inflammatory responses that promote chronic inflammation in smokers. Certain pharmacologic strategies such as anti-oxidant therapy may be only partially effective in mitigating cigarette smoke-induced pro-inflammatory DC-mediated responses in smokers.

Cigarette smoke-induced oxidative stress suppresses generation of dendritic cell IL-12 and IL-23 through ERK-dependent pathways.

IL-12p70, a heterodimer composed of p35 and p40 subunits, is a key polarizing cytokine produced by maturing dendritic cells (DCs). We report that cigarette smoke extract (CSE), an extract of soluble cigarette smoke components, suppresses both p35 and p40 production by LPS or CD40L-matured DCs. Suppression of IL-12p70 production from maturing DCs was not observed in the presence of nicotine concentrations achievable in CSE or in the circulation of smokers. The suppressed IL-12p70 protein production by CSE-conditioned DCs was restored by pretreatment of DCs or CSE with the antioxidants N-acetylcysteine and catalase. Inhibition of DC IL-12p70 by CSE required activation of ERK-dependent pathways, since inhibition of ERK abrogated the suppressive effect of CSE on IL-12 secretion. Oxidative stress and sustained ERK phosphorylation by CSE enhanced nuclear levels of the p40 transcriptional repressor c-fos in both immature and maturing DCs. Suppression of the p40 subunit by CSE also resulted in diminished production of IL-23 protein by maturing DCs. Using a murine model of chronic cigarette smoke exposure, we observed that systemic and lung DCs from mice “smokers” produced significantly less IL-12p70 and p40 protein upon maturation. This inhibitory effect was selective, since production of TNF-α during DC maturation was enhanced in the smokers. These data imply that oxidative stress generated by cigarette smoke exposure suppresses the generation of key cytokines by maturing DCs through the activation of ERK-dependent pathways. Some of the cigarette smoke-induced inhibitory effects on DC function may be mitigated by antioxidants.

Theophylline: Recent Advances in the Understanding of Its Mode of Action and Uses in Clinical Practice

Theophylline, a drug that has been used for several decades, has several different actions at a cellular level, including inhibition of phosphodiesterase isoenzymes, antagonism of adenosine, enhancement of catecholamine secretion, and modulation of calcium fluxes. Recently, theophylline was found to have several immunomodulatory and anti-inflammatory properties, and thus interest in its use in patients with asthma has been renewed. The use of theophylline in the treatment of asthma and chronic obstructive pulmonary disease has diminished with the advent of new medications, but theophylline remains beneficial, especially in the patient with difficult refractory symptoms. In the future, theophylline may be used as treatment for bradyarrhythmias after cardiac transplantation, prophylactic medication to reduce the severity of nephropathy associated with intravenous administration of contrast material, therapy for breathing problems during sleep, and treatment for leukemias.

Echocardiographic and clinical characteristics of pulmonary hypertension complicating pulmonary Langerhans cell histiocytosis.

OBJECTIVE To determine the echocardiographic characteristics and impact on survival of pulmonary hypertension (PH) and correlations between echocardiographic and clinical variables in patients with pulmonary Langerhans cell histiocytosis (PLCH). PATIENTS AND METHODS Of 123 adults seen at our institution between January 1976 and December 2002 with histologically proven PLCH, 17 underwent echocardiographic evaluation. Correlations were performed between echocardiographic measures of PH and clinical variables. Cumulative survival probabilities for patients with PH were estimated using the Kaplan-Meier method and were compared to a historical cohort of patients with PLCH using time-dependent proportional hazard regression. RESULTS Of the 17 patients, PH (estimated pulmonary artery systolic pressure [PASP] at rest, > 35 mm Hg) was present in 15. Thirteen patients (6 men; median PASP, 67 mm Hg; range, 41.2-90.6 mm Hg) had no other known causes of PH. All patients were smokers. Nine patients had a PASP of more than 50 mm Hg. An inverse correlation was found between the forced vital capacity and PASP (r = -0.61; P = .03); no correlation was found between PASP and other pulmonary function parameters. Seven patients with a PASP greater than 65 mm Hg had an enlarged right ventricle with impaired systolic function. The development of PH in patients with PLCH was associated with increased mortality (hazard ratio, 22.8; 95% confidence interval, 7.6 to > 68.9; P < .001). CONCLUSION Severe PH occurs in PLCH, correlates with the forced vital capacity, and has a significant impact on survival. Clinicians should consider echocardiographic screening for PH in all dyspneic patients with PLCH.

Cigarette smoke-induced mitochondrial fragmentation and dysfunction in human airway smooth muscle

The balance between mitochondrial fission and fusion is crucial for mitochondria to perform its normal cellular functions. We hypothesized that cigarette smoke (CS) disrupts this balance and enhances mitochondrial dysfunction in the airway. In nonasthmatic human airway smooth muscle (ASM) cells, CS extract (CSE) induced mitochondrial fragmentation and damages their networked morphology in a concentration-dependent fashion, via increased expression of mitochondrial fission protein dynamin-related protein 1 (Drp1) and decreased fusion protein mitofusin (Mfn) 2. CSE effects on Drp1 vs. Mfn2 and mitochondrial network morphology involved reactive oxygen species (ROS), activation of extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt), protein kinase C (PKC) and proteasome pathways, as well as transcriptional regulation via factors such as NF-κB and nuclear erythroid 2-related factor 2. Inhibiting Drp1 prevented CSE effects on mitochondrial networks and ROS generation, whereas blocking Mfn2 had the opposite, detrimental effect. In ASM from asmatic patients, mitochondria exhibited substantial morphological defects at baseline and showed increased Drp1 but decreased Mfn2 expression, with exacerbating effects of CSE. Overall, these results highlight the importance of mitochondrial networks and their regulation in the context of cellular changes induced by insults such as inflammation (as in asthma) or CS. Altered mitochondrial fission/fusion proteins have a further potential to influence parameters such as ROS and cell proliferation and apoptosis relevant to airway diseases.