Glucocorticoid receptors in bronchoalveolar lavage fluid in sarcoidosis. A preliminary report

Sarcoidosis: A Clinical Overview from Symptoms to Diagnosis

Sarcoidosis is a multi-system disease of unknown etiology characterized by the formation of granulomas in various organs. It affects people of all ethnic backgrounds and occurs at any time of life but is more frequent in African Americans and Scandinavians and in adults between 30 and 50 years of age. Sarcoidosis can affect any organ with a frequency varying according to ethnicity, sex and age. Intrathoracic involvement occurs in 90% of patients with symmetrical bilateral hilar adenopathy and/or diffuse lung micronodules, mainly along the lymphatic structures which are the most affected system. Among extrapulmonary manifestations, skin lesions, uveitis, liver or splenic involvement, peripheral and abdominal lymphadenopathy and peripheral arthritis are the most frequent with a prevalence of 25-50%. Finally, cardiac and neurological manifestations which can be the initial manifestation of sarcoidosis, as can be bilateral parotitis, nasosinusal or laryngeal signs, hypercalcemia and renal dysfunction, affect less than 10% of patients. The diagnosis is not standardized but is based on three major criteria: a compatible clinical and/or radiological presentation, the histological evidence of non-necrotizing granulomatous inflammation in one or more tissues and the exclusion of alternative causes of granulomatous disease. Certain clinical features are considered to be highly specific of the disease (e.g., Löfgren's syndrome, lupus pernio, Heerfordt's syndrome) and do not require histological confirmation. New diagnostic guidelines were recently published. Specific clinical criteria have been developed for the diagnosis of cardiac, neurological and ocular sarcoidosis. This article focuses on the clinical presentation and the common differentials that need to be considered when appropriate.

Expression of glucocorticoid receptors alpha and beta in steroid sensitive and steroid insensitive interstitial lung diseases

BACKGROUND

Sensitivity to glucocorticoids may be related to the concentration of glucocorticoid receptors alpha (GRalpha) and beta (GRbeta). A study was undertaken to assess GRalpha and GRbeta expression in steroid insensitive interstitial lung disease (idiopathic pulmonary fibrosis (IPF)) and steroid sensitive interstitial lung diseases (sarcoidosis and cryptogenic organising pneumonia (COP)).

METHODS

Lung tissue was obtained from control subjects and from patients with IPF, sarcoidosis, and COP. Pulmonary function tests were carried out at the time of lung biopsy and every 3 months. GRalpha and GRbeta expression was evaluated by both competitive RT-PCR and immunohistochemistry. Data are presented as median and 25-75th percentile.

RESULTS

GRalpha mRNA expression (10(5) cDNA copies/ micro g total RNA) was higher in patients with steroid sensitive interstitial lung diseases (10.0; 7.8-14.9; n = 11) than in patients with IPF (4.4; 3.2-6.6; n = 19; p<0.001). GRbeta expression was at least 1000 times lower than that of GRalpha and did not differ between the three groups. A negative correlation was found between GRalpha mRNA levels and the fibrotic pathology score of the tissue (r = -0.484, p<0.01) and a positive correlation was found between GRalpha mRNA levels and improvement in forced vital capacity (r = 0.633; p<0.01) after treatment of patients with glucocorticoids. Immunoreactivity for GR protein was also higher in patients with sarcoidosis and COP than in those with IPF.

CONCLUSION

The variable response of some interstitial lung diseases to steroid treatment may be the result of differences in the expression of GRalpha.

Glucocorticoid receptor mRNA expression in pulmonary alveolar macrophages in sarcoidosis

The presence of the glucocorticoid receptor was demonstrated by immunocytochemistry in pulmonary alveolar macrophages obtained by bronchoalveolar lavage. Also, GR mRNA content was determined by solution hybridization in PAM from 12 healthy volunteers and in 6 patients with sarcoidosis. No significant differences with regard to GR mRNA expression was detected between the two groups examined. For comparison, lung tissue from three patients undergoing thoracic surgery was examined and found to contain GR mRNA levels in the same range. As an indication of GR function, we also determined the mRNA levels of a glucocorticoid-regulated gene, metallothionein IIA, during basal conditions and after in vitro incubation of PAM with dexamethasone. Neither the control sample nor the dexamethasone-stimulated MTII mRNA values in PAMs differed significantly between the two groups. Solution hybridization is a rapid, sensitive and convenient assay which enables accurate and specific quantitation of GR mRNA in PAM. The GR mRNA content and basal as well as dexamethasone-induced MTII mRNA levels in PAM from patients with sarcoidosis is not significantly different from those in healthy volunteers.

Effect of prednisolone treatment in chronic silicosis

We evaluated the effects of daily oral prednisolone therapy on alveolitis parameters and pulmonary function tests over a 6-month period in patients with chronic silicosis. Pulmonary function tests were done in 34 patients, and bronchoalveolar lavage (BAL) was done in 21 of them. Pulmonary function tests showed a significant improvement in lung volumes, FEV1, PEFR, SGaw, DLCO, and PaO2. Analysis of BAL fluid revealed a significant decrease in total cell count. Mean fibronectin and immunoglobulin values in BAL fluid also were lower after treatment, but the change was not statistically significant. No serious side effects were encountered with prednisolone therapy. These results indicate that daily oral prednisolone therapy may suppress the alveolitis in certain patients with chronic silicosis and bring about a significant improvement in lung functions and gas exchange.