Effect of cyclosporin A on inflammatory cytokine production by U937 monocyte-like cells.

Cyclosporin A (CsA) is an immunosuppresor drug that has been used in the treatment of several types of inflammatory diseases. In some of them the inhibition of T-lymphocyte activation does not suitably account for the observed beneficial effect, suggesting that CsA could act on other types of cells. The present study was undertaken to determine the effect of CsA on inflammatory cytokine secretion by U937 monocyte cells. Undifferentiated and dimethylsulfoxide (DMSO) differentiated U937 cells were incubated with different concentrations of CsA (200, 20 and 2 ng/mL) in the presence or absence of phorbol-myristate-acetate (PMA). Interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6 and IL-8 levels were measured in supernatants using specific enzyme-linked immunosorbent assays. At the highest concentration used (200 ng/mL) CsA decreased the basal and stimulated secretion of all the inflammatory cytokines studied in both undifferentiated and differentiated cells, with the only exception of PMA-stimulated IL-1 secretion by undifferentiated cells. However, only basal secretion of interleukin-8 in both undifferentiated and DMSO-differentiated U937 cells was significantly reduced by CsA at the highest concentration (200 ng/ mL). At therapeutic concentrations in vivo, CsA exerts a predominant effect on IL-8 secretion by human mononuclear phagocytes.

Cyclosporin A decreases human macrophage interleukin-6 synthesis at post-transcriptional level.

In addition to its well-established effect on T cells, cyclosporin A (CsA) also inhibits inflammatory cytokine production by macrophages. However, little is known about the mechanism of action of CsA on macrophage cytokine production. We measured the effect of CsA on basal and phorbol-myristate-acetate (PMA)-stimulated production of interleukin-6 using the human monocyte cell line U937 differentiated with dimethylsulfoxide (DMSO). Interleukin-6 levels were measured in supernatant and cell lysates using specific enzyme-linked immunosorbent assays. We found that CsA decreases not only IL-6 release but also cytokine synthesis. The concentration of CsA used did not affect either cell viability or proliferation. Three possibilities may be advanced to explain the CsA-due decrease in IL-6 production by macrophages: (a) inhibition of the synthesis of an early common regulatory protein, (b) inhibition of cytokine gene transcription, or (c) modulation of post-transcriptional events. The first possibility was tested by measuring the effect of cycloheximide on the experimental system during the first 3 hours of culture. Although cycloheximide decreased total cytokine synthesis, the pattern of cytokine modulation by CsA persisted. These data suggest that CsA-mediated macrophage cytokine inhibition is not mediated by an early common regulatory protein. To further explore the inhibition mechanism, we measured IL-6 mRNA levels by Northern blot. IL-6 mRNA levels were unaffected by CsA both in resting and PMA-stimulated cells. We conclude that in human macrophages CsA diminishes IL-6 production at post-transcriptional level.

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.

Teratoma of the placenta, a case report.

A mature solid teratoma of the placenta is presented. Like the other six, previously reported, cases it was located on the placental surface, between amnion and chorion. The nature of the tumor as well as its differential feature with fetus acardius amorphus are discussed.