Six cases of silicosis: implications for health surveillance of stonemasons.

BACKGROUND: Silicosis is one of the oldest occupational lung diseases, but it continues to cause significant morbidity and mortality worldwide. AIMS: To report cases of silicosis presenting to two specialist respiratory clinics. METHODS: A retrospective analysis of prospectively collected data of cases of silicosis in workers referred to specialist respiratory clinics. RESULTS: Over the course of 6 years, six cases were identified. The patients were all male with an age range between 24 and 39 years. The duration of silica exposure ranged between 7 and 20 years (mean 13 years). Four cases were entirely asymptomatic at presentation, and two cases described minimal shortness of breath on exertion. Pulmonary function tests were normal in three cases, and a mild restrictive ventilatory defect was documented in the other cases. All had a low apparent predicted probability of pneumoconiosis based on health questionnaires, spirometry and duration of silica exposure. The initial chest X-ray was abnormal in all six cases with radiological evidence of silicosis (International Labour Office profusion category ≥1/1) on imaging, and all had evidence of silicosis on high-resolution computed tomography (HRCT). Three patients had already progressed to progressive massive fibrosis on HRCT scanning at the time of referral to specialist respiratory services. CONCLUSIONS: The appearances of these six cases of silicosis in young, asymptomatic construction workers emphasizes the importance of enforcing effective exposure control and comprehensive surveillance programmes. Our observations highlight the importance of having a low threshold for early radiological screening to promote early and effective detection of this disease.

Systemic lupus erythematosus complicating simple silicosis.

Inhalation of crystalline silica is known to result in silicosis: an irreversible, disabling and potentially fatal occupational lung disease, which is associated with a variety of pulmonary and non-pulmonary complications including autoimmunity. A potential link between silicosis and systemic lupus erythematosus (SLE) is currently recognized only in cases of acute or accelerated silicosis. We report a case of SLE, a disease which usually affects young females, arising in a male former stonemason with simple silicosis. Epidemiological and clinical literature on the association of silica exposure and development of SLE are briefly reviewed. This case report and literature review highlight the link between occupational silica exposure and autoimmune disease including SLE, establishes that even simple silicosis appears linked to development of autoimmunity and emphasizes the importance of an occupational history, especially in male patients who develop SLE.

Occupational lung disease.

Occupational medicine represents the interface between work and health. As such, its breadth encompasses issues of clinical medicine, epidemiology, occupational hygiene, toxicology, ethics, and the law. The diagnosis of an occupational lung disease has implications not only for the health of the worker, but also in some circumstances for the health of colleagues and the employer. It is not surprising that many clinicians find this challenging. The aim of this paper is to provide a summary of common work-related lung disorders, and stress the importance of considering a patients' occupation when presented with a range of respiratory symptoms.

Cannabis and the lung.

The use of cannabis is embedded within many societies, mostly used by the young and widely perceived to be safe. Increasing concern regarding the potential for cannabis to cause mental health effects has dominated cannabis research and the potential adverse respiratory effects have received relatively little attention. Studies on cannabis are challenging and subject to confounding by concomitant use of tobacco and other social factors, and while many of the studies referred to in this review are beset by the difficulties inherent in undertaking epidemiological research of the effects of cannabis, there is an emerging concern among many chest physicians who would suggest that habitual smoking of cannabis may contribute to the development of chronic obstructive pulmonary disease, pneumothorax and respiratory infections, including tuberculosis. Special attention should be given to the risk of lung cancer, particularly as biological plausibility may precede epidemiology.

Cytokines in the pathogenesis of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a common cause of morbidity and mortality. The term is heterogenous and encompasses a number of distinct but often overlapping phenotypes including chronic bronchitis, small airways obstruction, emphysema and in some individuals, a systemic component. Although there have been significant advances in understanding the pathophysiology of COPD, understanding of the role of the inflammation in the pathogenesis of the condition remains in its infancy. Indeed, cytokines that are known to orchestrate the inflammatory response in asthma and other inflammatory diseases are only beginning to be reported in COPD. In this review, we highlight the potential role of cytokines in the development of mucus hypersecretion observed in chronic bronchitis and the morphological changes observed in the small airways and airspaces contributing to the development of airflow limitation and respiratory failure respectively. We report evidence that exacerbations are linked to increased expression of pro-inflammatory cytokines and that the wasting and skeletal muscle dysfunction observed in some patients is most probably related to the presence of a systemic inflammatory response. In addition transgenic and gene therapy technology has been used to explore the temporal and co-ordinated role of cytokines in the development of COPD animal models. Enhanced understanding of the events involved in the pathogenesis of COPD will lead to the development of therapy with potential to modify the observed progressive decline in lung function and impact on the development of the illness.

Neutrophil-derived elastases and their inhibitors: potential role in the pathogenesis of lung disease.

The proteinase-antiproteinase hypothesis still receives support from clinical and experimental observations in a range of inflammatory lung diseases. The function of these molecules appears to be broader than originally believed and further research is likely to lead to an improved understanding of their role in the regulation of both the beneficial and detrimental effects in inflammatory response and the maintenance of the homeostasis in the normal lung. Thus the potential for the development as therapeutic tools is likely to become more attractive as improved drug development and delivery mechanisms appear.

Pulmonary endothelial permeability and circulating neutrophil-endothelial markers in patients undergoing esophagogastrectomy.

OBJECTIVE: Esophagogastrectomy is an established surgical treatment for esophageal malignancy. The postoperative period may be complicated by the development of acute lung injury syndromes and thus, may provide a useful model in which to study the early pathogenic mechanisms of inflammatory lung injury. DESIGN: Open, prospective study. SETTING: High dependency and intensive therapy units. PATIENTS: Eight healthy male volunteers and 20 patients in the early postoperative period INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The lung protein accumulation index (PAI) of radiolabeled transferrin was determined by using a portable, double-isotope system. The following circulating inflammatory markers-thought to reflect neutrophil-endothelial activation and injury including circulating neutrophil elastase-soluble L-, E-, and P-selectins and thrombomodulin and von Willebrand factor antigen were assayed from venous blood samples The PAI for healthy volunteers was median -0.5 (range, -1.73 to 0.27) x 10(-3)/min and for patients undergoing esophagogastrectomy -0.005 (range, -1.53 to 2.28) x 10(-3)/min. There was no statistical difference between the two groups. In the postesophagogastrectomy group, a significant elevation in circulating levels of neutrophil elastase, soluble P- and E-selectin, thrombomodulin, and von Willebrand factor antigen were observed relative to the control group but only circulating plasma elastase demonstrated a significant correlation with the PAI (r2 = .23, p =.03). CONCLUSIONS: The data suggest patients undergoing esophagogastrectomy develop a inflammatory response but this is not a surrogate of permeability and other factors are likely to determine persistent injury to the alveolar-capillary barrier function in this patient group.

Human neutrophil elastase regulates the expression and secretion of elafin (elastase-specific inhibitor) in type II alveolar epithelial cells.

Elafin is a low molecular weight antiproteinase believed to be important in the regulation of elastase mediated tissue damage. The expression of elafin is known to be regulated by proinflammatory cytokines such as interleukin-1 beta and tumour necrosis factor but little was known regarding the effect of human neutrophil elastase (HNE). Employing a chloramphenicol acetyltransferase reporter construct of the human elafin gene, reverse transcription PCR from total cellular RNA and ELISA techniques, we have examined the effect of human neutrophil elastase on the transcription and secretion of human elafin in the pulmonary epithelial A549 cell line. Stimulation with HNE at concentrations of 10(-10) and 10(-11) M resulted in a significant upregulation of elafin promoter activity. Similarly, transcription of the endogenous human elafin gene was upregulated with HNE concentrations ranging from 10(-10) to 10(-12) M. In addition, we demonstrate that stimulation with HNE at concentrations ranging from 10(-9) and 10(-12) M resulted in a significant reduction in the secreted elafin protein as measured in the cell supernatant. These results provide further evidence for a role of elafin in the regulation of HNE driven proteolysis of the extracellular matrix.

Regulatory role for macrophage migration inhibitory factor in acute respiratory distress syndrome.

Migration inhibitory factor (MIF) is known to exert significant pro-inflammatory effects and has the potential to override the anti-inflammatory action of glucocorticoids. In this study we have identified significant quantities of MIF in the alveolar airspaces of patients with acute respiratory distress syndrome (ARDS). We show in alveolar cells from patients with ARDS that MIF augments pro-inflammatory cytokine secretion (TNF alpha and IL-8), anti-MIF significantly attenuates TNF alpha and IL-8 secretion and MIF overrides, in a concentration-related fashion, the anti-inflammatory effects of glucocorticoids. These findings suggest that MIF may act as a mediator sustaining the pulmonary inflammatory response in ARDS and that an anti-MIF strategy may represent a novel therapeutic approach in inflammatory diseases such as ARDS.

The association between mortality rates and decreased concentrations of interleukin-10 and interleukin-1 receptor antagonist in the lung fluids of patients with the adult respiratory distress syndrome.

OBJECTIVES: To determine the relation between 1) intra-alveolar concentrations of the proinflammatory cytokines (tumor necrosis factor, interleukin-1 beta, and interleukin-8) and the anti-inflammatory cytokines (interleukin-10 and interleukin-1 receptor antagonist) in patients with early adult respiratory distress syndrome (ARDS) and 2) subsequent patient mortality rates. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: 28 consecutive patients in whom ARDS was prospectively identified during hospitalization and 9 ventilated controls. MEASUREMENTS: Concentrations of proinflammatory cytokines and anti-inflammatory cytokines in bronchoalveolar lavage fluid. RESULTS: The concentrations of proinflammatory and anti-inflammatory cytokines within the alveolar air spaces were significantly elevated in patients with ARDS compared with controls (P = 0.01 for tumor necrosis factor [median, 90 pg/mL (range, 0 to 2500 pg/mL) for patients with ARDS; median, 0 pg/mL (range, 0 to 118 pg/mL) for controls]; P = 0.001 for interleukin-1 beta [median, 179 pg/mL (range, 0 to 2200 pg/mL) for patients with ARDS; median, 0 pg/mL (range, 0 to 80 pg/mL) for controls]; P = 0.0001 for interleukin-8 [median, 628 pg/mL (range, 0 to 4700 pg/mL) for patients with ARDS; median, 0 pg/mL (range, 0 to 278 pg/mL) for controls]; P = 0.0005 for interleukin-10 [median, 100 pg/mL (range, 0 to 1600 pg/mL) for patients with ARDS; median, 0 pg/mL (range, 0 to 50 pg/mL) for controls], and P = 0.002 for interleukin-1 receptor antagonist [median, 820 pg/mL (range, 0 to 18,900 pg/mL) for patients with ARDS; median, 50 pg/mL (range, 0 to 240 pg/mL) for controls]). A highly significant correlation was found between low concentrations of anti-inflammatory cytokines and subsequent patient mortality rates (P = 0.003 for interleukin-10 [median, 120 pg/mL (range, 30 to 1600 pg/mL) for survivors; median, 40 pg/mL (range, 0 to 110 pg/mL) for nonsurvivors]; P = 0.008 for interleukin-1 receptor antagonist [median, 1600 pg/mL (range, 80 to 18,900 pg/mL) for survivors; median, 90 pg/mL (range, 0 to 3400 pg/mL) for nonsurvivors. No significant correlation was found between the concentrations of the proinflammatory cytokines and mortality rates. CONCLUSION: Low concentrations of the anti-inflammatory cytokines interleukin-10 and interleukin-1 receptor antagonist in bronchoalveolar lavage fluid obtained from patients with early ARDS are closely associated with poor prognosis. These findings support the hypothesis that failure to mount a localized intrapulmonary anti-inflammatory response early in the pathogenesis of ARDS contributes to more severe organ injury and worse prognosis. Our findings suggest that augmenting anti-inflammatory cytokine defenses would be a beneficial therapeutic approach to patients with ARDS and other inflammatory diseases.

Transplantation for chronic pulmonary disease: referral and outcome in Northern Ireland, 1986-1990.

Eighteen patients have been referred for lung transplantations from Northern Ireland in 1986-1990. Fourteen were accepted but only four achieved transplantation. These rates are lower than for comparable regions in the North of England. The lung donation rate from Northern Ireland during the same period was similar to that for the United Kingdom as a whole. The low referral and transplant rates for Northern Ireland require reassessment of the procedures involved.