The cytokine network in sarcoidosis and its clinical relevance.

In recent years, analysis of the cytokine network has substantially improved our knowledge of the immunopathogenesis of sarcoidosis. There is increasing evidence from clinical immunology that analysis of the cytokine network may be helpful for clinicians to assess the extent and activity of sarcoid inflammation. Genetic polymorphisms may contribute to interindividual differences in the regulation of cytokine release. Thus, disease phenotype-associated haplotypes should exist and their analysis might disclose risk profiles of individual patients. Furthermore, serological assessment of cytokines or soluble cytokine receptors may become suitable parameters in clinical practice to detect an ongoing inflammation in chronic sarcoidosis.

Effect of proinflammatory cytokines on interleukin-8 mRNA expression and protein production by isolated human alveolar epithelial cells type II in primary culture.

Alveolar epithelial cells type II (AEC-II) are ideally situated to regulate the recruitment and activation of different types of cells through the production of chemokines in response to inflammatory stimulation from the alveolar space. We hypothesized that these cells are important producers of interleukin-8 (IL-8) in the lung. This lead us to investigate the capacity of isolated human AEC-II cells to release IL-8 and whether this IL-8 release is regulated by proinflammatory cytokines, i.e. IL-1 beta, TNF-alpha and IFN-gamma. We isolated AEC-II from tumor-free sections of human lungs obtained by pneumectomy and purified the cells by magnetic activated cell sorting. For control experiments the AEC-II-like cell line A549 was used. IL-8 concentration was measured by ELISA in supernatants of unstimulated and LPS-, IL-1 beta-, TNF-alpha- and IFN-gamma- stimulated cells. IL-8 mRNA expression was evaluated by RT-PCR. Spontaneous IL-8 mRNA expression and protein secretion by AEC-II were significantly higher in comparison with A549 cells. TNF-alpha increased both IL-8 mRNA expression and protein production, whereas IL-1 beta slightly increased IL-8 release but did not change mRNA expression in AEC-II. LPS and IFN-gamma did not influence IL-8 expression in AEC-II and A549 cells. These results show considerable differences between A549 cell and AEC-II. The latter are capable of producing IL-8 under the control of proinflammatory cytokines. Our findings demonstrate that the modulation of IL-8 release in AEC-II may have an important impact on the immunoreactivity of these cells during pulmonary inflammation in vivo.

Serum level of soluble tumour necrosis factor receptor II (75 kDa) indicates inflammatory activity of sarcoidosis.

OBJECTIVES: Tumour necrosis factor alpha (TNFalpha) is a key cytokine involved in granuloma formation of sarcoidosis. Since soluble TNF receptors (sTNF-R) are known to inhibit TNF effects, we were interested in whether they are elevated in the serum of sarcoidosis patients. METHODS: We determined serum levels of sTNF-R I (55 kDa) and sTNF-R II (75 kDa) in 49 patients with sarcoidosis and 22 controls. The clinical course of the disease was re-evaluated in a follow-up after (mean +/- SE) 6.8 +/- 6.6 months. RESULTS: sTNF-R I (3.1 +/- 1.1 ng mL-1, P < 0.05) and sTNF-R II (5.5 +/- 2.7 ng mL-1, P < 0.0005) were significantly elevated in sarcoidosis compared with controls (2.4 +/- 0.7 and 3.0 +/- 1.3 ng mL-1, respectively). Interestingly, both sTNF receptors were significantly higher in the serum of patients with active compared with inactive sarcoidosis (P < 0.005 and P < 0.0005, respectively). Furthermore, serum sTNF-R II levels were significantly higher in sarcoidosis patients with advanced radiological types II and III. In 10 patients, serum sTNF-R levels were obtained before and after systemic corticosteroid therapy and we observed a significant decrease of sTNF-R II (P < 0.02), whereas sTNF-R I levels were not reduced significantly. CONCLUSIONS: Both types of sTNF receptors are elevated in the serum of sarcoidosis patients with active disease, but only the sTNF-R II seems to be useful for monitoring the inflammatory activity of the disease.

Different cytokine patterns correlate with the extension of disease in pulmonary tuberculosis.

The relative amounts of different pro- and anti-inflammatory cytokines released at the site of infection by bronchoalveolar lavage (BAL) cells may influence the presentation of tuberculosis. To investigate this hypothesis the in situ release by BAL cells of the following cytokines was measured and correlated with the chest X-ray findings of 43 patients with pulmonary tuberculosis: interleukin (IL)-8, macrophage inflammatory protein-1alpha (MIP-1alpha), IL-6, tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interferon-gamma (IFN-gamma), IL-2, IL-4 and IL-5. The release of IL-8 and IL-6 decreased with the progression of the disease, while the release of MIP-1alpha was increased in patients with advanced tuberculosis. The release of TNF-alpha and TGF-beta did not differ between patients with or without cavitary lesions. The Th1 (IFN-gamma and IL-2) and Th2 (IL-4 and IL-5) cytokine release exhibited a gradual increment with the advance of tuberculosis. Thus, our data provide evidence that a Th0 cytokine pattern is predominant at the site of pulmonary tuberculosis. In conclusion, immunoparalysis status could not be observed in our patients with severe tuberculosis.

Increased expression of proinflammatory chemokines in bronchoalveolar lavage cells of patients with progressing idiopathic pulmonary fibrosis and sarcoidosis.

BACKGROUND: There is increasing evidence that the proinflammatory chemokines interleukin-8 (IL-8) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) are involved in the pathogenesis of interstitial lung diseases. METHODS: We investigated the release of TNF-alpha, IL-8, MIP-1 alpha by cultured bronchoalveolar lavage (BAL) immune cells of patients with idiopathic pulmonary fibrosis (IPF, n = 24), sarcoidosis (SAR, n = 24), and controls (n = 20) by ELISA. Furthermore, mRNA expression of these cytokines in BAL cells immediately frozen after bronchoscopy was determined. The clinical course of the disease was evaluated and the patients were subdivided into groups with progressing or stable disease. RESULTS: TNF-alpha, IL-8, and MIP-1 alpha were significantly elevated in the supernatants of BAL immune cells of IPF and SAR patients with progressing disease compared to controls (p < 0.005 in both diseases) and also when compared to patients with stable disease (IPF p < 0.005, SAR p < 0.05). Interestingly, the release of TNF-alpha, IL-8, and MIP-1 alpha did not differ significantly between IPF patients with stable disease and controls, whereas in SAR patients with stable disease a difference at a low significance level (p < 0.05) was obtained. In IPF and SAR patients with progressing disease, a clear mRNA signal of TNF-alpha, IL-8, and MIP-1 alpha was detected in BAL immune cells not having been stimulated by adherence to plastic, whereas in patients with stable disease or controls only a weak signal was observed. MIP-1 alpha release correlated positively with percentage of BAL eosinophils in IPF and SAR. Furthermore, the percentage of eosinophils in BAL was significantly elevated in the IPF subgroup with progressing disease. CONCLUSIONS: Our data demonstrate that an exaggerated expression of TNF-alpha, IL-8, and MIP-1 alpha in BAL immune cells is characteristic for IPF and SAR patients who show progressing disease.

Sarcoidosis: TNF-alpha release from alveolar macrophages and serum level of sIL-2R are prognostic markers.

At the time of diagnosis, many sarcoidosis patients have no clinical indication for corticosteroid therapy, and prognostic parameters predicting deterioration are missing. In the present study, we investigated parameters derived from bronchoalveolar lavage (BAL) and serum in 77 patients with recently diagnosed sarcoidosis to test their predictive value. Patients were divided into a group with (Group A, n = 37) and a group without (Group B, n = 40) indications for therapy, and the course of the disease was evaluated after 5.7 +/- 0.4 mo. The CD4+/CD8+ lymphocyte ratio and percentage of BAL lymphocytes were of no predictive value. Release of tumor necrosis factor-alpha (TNF-alpha) from cultured alveolar macrophages (AM) was significantly increased in both groups (Group A = 1,872 +/- 428 pg/ml; Group B = 1,561 +/- 449 pg/ml) as compared with controls (220 +/- 37 pg/ml). In Group B, however, patients with a high level of TNF-alpha release had a significantly greater risk of disease progression than did those with normal TNF-alpha release (43.8% versus 8.3%, respectively). From the serologic parameters investigated, consisting of neopterin, angiotensin converting enzyme (ACE), and soluble interleukin-2 receptor (sIL-2R), only the last was of significant predictive value; 42.1% of sarcoidosis patients in Group B with a high level of sIL-2R experienced disease progression, whereas none of those with a normal level did. We conclude that TNF-alpha release and sIL-2R are suitable parameters for predicting disease progression in sarcoid patients who have no indication for therapy at the time of disease diagnosis.