No abstract

ALN-RSV01 was safe and may have beneficial effects on long-term allograft function in LTX patients infected with RSV. Clinical trial registered with www.clinicaltrials.gov (NCT 00658086).

Idiopathic pulmonary fibrosis is an immunologically mediated pulmonary disorder in which activated alveolar macrophages (AM) and neutrophils play cardinal roles in the pathogenesis of the inflammatory lung lesion. The factors responsible for the induction and perpetuation of the neutrophilic alveolitis are not known. Recently, a novel cytokine (Interleukin-8) was described that is released by activated mononuclear phagocytes and a variety of other cell types, and it exhibits potent chemotactic activity for polymorphonuclear leukocytes (PMN). Increased expression of IL-8 has been described in other inflammatory disorders characterized by neutrophilic infiltration, including psoriasis, rheumatoid arthritis, and the sepsis syndrome, but no studies have assessed this cytokine in the context of interstitial pulmonary disorders. We have previously shown that normal human AM release IL-8 upon appropriate stimulation, but data assessing the expression of IL-8 by human AM in specific pulmonary disease states are lacking. In this study, we examined the expression of steady-state mRNA for IL-8 by human alveolar macrophages obtained by bronchoalveolar lavage (BAL) from patients with idiopathic pulmonary fibrosis (IPF) or sarcoidosis and from healthy volunteers. Because it is known that adherence to plastic culture plates may up-regulate gene expression for IL-8 in the absence of additional stimulation, we extracted mRNA immediately from the cell pellet obtained by BAL rather than using cultured alveolar macrophage monolayers. Northern blot analysis was performed to determine IL-8 mRNA expression. We found that BAL cells from patients with IPF constitutively expressed mRNA for IL-8, and the amount of IL-8 mRNA (as assessed by laser densitometry) correlated with the percent of neutrophils on BAL.(ABSTRACT TRUNCATED AT 250 WORDS)

Mononuclear phagocytes are important immune effector cells that play a fundamental role in cellular immunity. In addition to their antigen-presenting and phagocytic activities, monocytes/macrophages produce a vast array of regulatory and chemotactic cytokines. Interleukin-8 (IL-8), a potent neutrophil-activating and chemotactic peptide, is produced in large quantities by mononuclear phagocytes and may be an important mediator of local and systemic inflammatory events. In this investigation, we describe the effects of prostaglandin E2 (PGE2) and dexamethasone (Dex) on IL-8 mRNA and protein expression from lipopolysaccharide (LPS)-treated human peripheral blood monocytes (PBM) and alveolar macrophages (AM). We demonstrate the dose-dependent suppression of IL-8 from LPS-stimulated PBM by PGE2. Treatment of stimulated PBM with 10(-6) M PGE2 resulted in maximal inhibition, causing 60% suppression of both IL-8 mRNA and extracellular protein levels. In contrast, PGE2 (10(-6) to 10(-8) M) did not significantly alter IL-8 mRNA or protein expression from LPS-treated AM. Treatment of LPS-stimulated PBM and AM with Dex (10(-6) to 10(-8) M) resulted in 75% decline in IL-8 mRNA and extracellular protein from either cell population. Pretreatment of PBM with PGE2 or Dex 1 or 2 h before LPS stimulation caused a significant suppression of steady-state IL-8 mRNA levels; however, administration of either of these modulators 1 or 2 h after LPS stimulation failed to have an inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS)

The pulmonary fibroblast's (PF) unique location allows it to communicate in a bidirectional fashion between the vascular compartment and alveolar airspace, placing it in a strategic position for the elicitation of inflammatory leukocytes into the lung. In this study, we demonstrate that PF may contribute to pulmonary inflammation through the production of a potent neutrophil chemotactic factor, interleukin (IL)-8. PF-derived IL-8 expression was dependent upon stimulation by either tumor necrosis factor (TNF) or IL-1 but not lipopolysaccharide (LPS). Both TNF and IL-1 stimulation of PF resulted in a time- and dose-dependent expression of steady-state levels of mRNA, antigen, and specific chemotactic activity consistent with IL-8. Because it was apparent that cytokine networking may exist in the lung between alveolar macrophage (AM)-derived cytokines and the production of PF-derived IL-8, we next examined an in vitro model of cellular communication within the lung. We determined that LPS-stimulated AM-conditioned media induced significant levels of PF-derived IL-8 mRNA, which was inhibited by preincubation with specific neutralizing TNF and IL-1 beta antibodies. Furthermore, when AM were directly co-cultured with PF and stimulated with LPS, the kinetic analysis of PF-derived antigenic expression of IL-8 was shifted toward the right. This suggested that PF-derived IL-8 expression in co-culture was first dependent upon activation of the AM by LPS and subsequent elaboration of macrophage inflammatory mediators. These data provide evidence that cytokine networking between AM and PF may be operative in the lung, culminating in the generation of IL-8 and elicitation of inflammatory leukocytes.