Evaluation of inflammatory cytokine secretion by human alveolar macrophages.

The alveolar macrophage (AM) secretes interleukin 1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8), all of them inflammatory cytokines involved in the pathogenesis of many lung diseases. The aim of the present work was to evaluate the basal and stimulated secretion of these cytokines by human AMs. Human AMs were collected by bronchoalveolar lavage (BAL) from four healthy controls and 13 patients with diffuse interstitial lung disease (five cases of sarcoidosis, three of hypersensitivity pneumonitis and five of idiopathic pulmonary fibrosis). AMs were cultured in the presence or absence of different concentrations of lipopolysaccharide (LPS), phorbolmyristate and gamma-interferon. IL-1beta, TNF-alpha, IL-6 and IL-8 levels were measured in BAL fluid and culture supernatant using specific enzyme-linked immunosorbent assays. The substance found to stimulate the secretion of inflammatory cytokines to the greatest extent was LPS at a concentration of 10 microg/ml. Regarding the secretion of IL-1beta, four observations were of interest: basal secretion was very low; LPS exerted a potent stimulatory effect; considerable within-group variability was observed; and there were no significant differences in the comparisons among groups. With respect to TNF-alpha secretion, the results were similar. The only striking finding was the higher basal secretion of this cytokine with respect to that of IL-1beta. Regarding the secretion of IL-6, the same pattern followed by TNF-alpha was found. However, it should be stressed that the increase induced by LPS was smaller than in the two previous cytokines. Regarding the secretion of IL-8, three findings were patent: the strong basal secretion of this cytokine; the moderate increase induced by LPS; and the existence of significant differences among the different groups with respect to the stimulated secretion of this cytokine, which reached maximum values in patients with idiopathic pulmonary fibrosis. Finally, it should be noted that the pattern of cytokines observed in the BAL fluid was similar to that found in cultured AM supernatants. The pattern of inflammatory cytokine secretion by AMs differs from that of other cells of the mononuclear phagocyte system (MPS). In this sense. AMs secrete low amounts of IL-1, moderate amounts of TNF-alpha and IL-6, and high quantities of IL-8. Adherence is an important stimulus in the secretion of these molecules and LPS elicits an increased secretion inverse to the basal secretion. There is considerable individual variability in the secretion of inflammatory cytokines by the AMs of patients with interstitial lung disease and the AMs of these patients are primed in vivo for the secretion of these cytokines. The results of our study, carried out in vitro, can be extrapolated to the in vivo setting.

Effect of cyclosporin A on inflammatory cytokine production by human alveolar macrophages.

Cyclosporin A (CsA) is an immunomodulator drug that has been used in the treatment of several types of advanced pulmonary interstitial disease. This beneficial effect occurs mainly in circumstances in which alveolitis due to CD4 lymphocytes is absent, suggesting that CsA acts on other types of cells. The present study was undertaken to determine the effect of CsA on inflammatory cytokine secretion by human alveolar macrophages (AMs). Human AMs were collected by bronchoalveolar lavage from four control subjects and 13 patients with interstitial lung disease. Purified human AMs were incubated with different concentrations of CsA (200, 20 and 2 ng ml-1) in the presence or absence of lipopolysaccharide (LPS). Interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), IL-6 and IL-8 levels were measured in supernatants using specific enzyme-linked immunosorbent assays. It was found that CsA inhibits basal secretion of TNF-alpha and IL-8 at 20 and 200 ng ml-1. However, none of the different concentrations of CsA modified basal secretion of IL-1 beta nor IL-6. By contrast, a lower concentration of CsA (2 ng ml-1) inhibits LPS-stimulated secretion of all inflammatory cytokines. It is concluded that CsA exerts a modest effect on inflammatory cytokine production by human AMs.

Differential patterns of filaggrin expression in lamellar ichthyosis.

Lamellar ichthyosis (LI) is a rare genetic and congenital disturbance of keratinization that is phenotypically and genotypically heterogeneous. Filaggrin is one of the major components of the stratum corneum situated in the protein matrix and the cornified envelope. In view of the heterogeneity of LI, this study aimed at exploring filaggrin expression in the skin of patients suffering from the disease. Epidermal filaggrin expression was determined using immunohistochemical techniques and Western blot in 12 patients with LI and the findings were compared with those observed in four normal controls and eight patients with ichthyosis vulgaris. With Western blot, six different patterns of filaggrin expression were detected. The patients with similar clinical manifestations showed a similar pattern, as did members of the same family. Overall, higher filaggrin expression in scales correlated with a better prognosis. In patients receiving retinoids no variations in filaggrin expression during treatment were detected. Our results suggest that LI is heterogeneous as regards filaggrin expression. Filaggrin could therefore be used as a prognostic marker as well as being a marker of the basic defect involved in LI.

[Nitric oxide in the lower respiratory tract]. / Oxido nítrico en el tracto respiratorio inferior.

The aim of this work is to review of the role of nitric oxide (NO) in the lower respiratory tract. This review mainly focuses on the generation of nitric oxide by alveolar macrophages. In the first part of the paper, we summarize the literature on nitric oxide synthesis by different cell types and the effects of this mediator on target cells. Methods for measuring nitric oxide are also analyzed. The core of the paper is a review of the role of nitric oxide in diffuse interstitial lung diseases (both human and experimental models). We include data about the concentration of this mediator in bronchoalveolar lavage fluid and then summarize the knowledge about the regulation of nitric oxide synthesis by animal or human alveolar macrophages. Finally, we review the biological effects of nitric oxide in the lower respiratory tract.

The role of platelet-activating factor (PAF) in interstitial pulmonary disease.

Platelet-activating factor (PAF) is a biolipid of crucial importance in the inflammatory response. In the first part of this work we review the basic biochemical characteristics of PAF. Also, the production and degradation of PAF by inflammatory cells is detailed in depth, with a description of enzymes linked to these processes. Subsequently, we examine the main characteristics of the generation of PAF by pulmonary cells, with emphasis on its production by alveolar macrophages. We then discuss in depth the effects of this biolipid on the inflammatory cells present in interstitial disease. In this part of the review we describe the direct effect of PAF on polymorphonuclear leukocytes (neutrophils and eosinophils), mononuclear phagocyte system cells, lymphocytes and endothelial cells. We then examine the indirect effect of PAF on inflammatory cells (mainly due to an interaction with neuropeptides). Finally, we discuss the data on the role of PAF in diffuse interstitial pulmonary disease (both human and experimental).