Inflammation, regardless of whether it is provoked by infection or by tissue damage, starts with the activation of macrophages which initiate a cascade of inflammatory responses by producing the cytokines interleukin-1 (IL-1) and tumour necrosis factor-alpha (ref. 1). Three naturally occurring ligands for the IL-1 receptor (IL1R) exist: the agonists IL-1alpha and IL-1beta and the IL-1-receptor antagonist IL1RA (ref. 2). IL-1 is the only cytokine for which a naturally occurring antagonist is known. Here we describe the crystal structure at 2.7 A resolution of the soluble extracellular part of type-I IL1R complexed with IL1RA. The receptor consists of three immunoglobulin-like domains. Domains 1 and 2 are tightly linked, but domain three is completely separate and connected by a flexible linker. Residues of all three domains contact the antagonist and include the five critical IL1RA residues which were identified by site-directed mutagenesis. A region that is important for biological function in IL-1beta, the 'receptor trigger site' is not in direct contact with the receptor in the IL1RA complex. Modelling studies suggest that this IL-1beta trigger site might induce a movement of domain 3.

Vascular endothelial growth factor-A (VEGF-A) is required for vascular development throughout the embryo and has been proposed to play an important role in pulmonary vascular patterning. Expressed by the embryonic respiratory epithelium, VEGF-A signals endothelial cells within the splanchnic mesenchyme. To refine understanding of the spatial and temporal role of VEGF-A in lung morphogenesis, isoform VEGF164 was expressed under conditional control in distal and proximal airway epithelial cells. Unexpectedly, increased expression of VEGF164 in distal lung disrupted peripheral vascular net assembly and arrested branching of airways tubules without altering endothelial cell proliferation or apoptosis. Peripheral airway branching and vascular smooth muscle patterning were also altered. In contrast, expression of VEGF164 by epithelial cells of the conducting airways caused atypical evaginations of small capillary-like vessels into large airways but did not alter peripheral vascular net assembly or branching morphogenesis. These data demonstrate that the differential response of endothelial cells in distal vascular beds and large central blood vessels is established early in lung development. Precise temporal and spatial expression of VEGF-A is required for vascular patterning during lung morphogenesis. Disruption of pulmonary vascular assembly perturbs reciprocal interactions with epithelium leading to altered airway branching morphogenesis.

. VEGF causes pulmonary hemorrhage, hemosiderosis, and air space enlargement in neonatal mice.

The nucleotide sequence of the human adenosine deaminase gene was determined. The gene was isolated in a series of overlapping lambda phage clones containing human germ line DNA. A total of 36,741 base pairs were sequenced, including 32,040 base pairs from the transcription initiation site to the polyadenylation site, 3935 base pairs of 5'-flanking DNA, and 766 base pairs of 3'-flanking DNA. The gene contains 12 exons separated by 11 introns. The exons range in size from 62 to 325 base pairs while the introns are 76-15 166 base pairs in size. The area sequenced contains 23 copies of Alu repetitive DNA and a single copy of an "O" family repeat. All but one of these repeat sequences are located in the first three introns or the 5'-flanking region. The apparent promoter region of the gene lacks the "TATA" and "CAAT" sequences often found in eucaryotic promoters and is extremely G/C rich. Contained within this region are areas homologous to other G/C-rich promoters, including six decanucleotide sequences that are highly homologous to sequences identified as functional binding sites for transcription factor Sp1.

The role of vascular endothelial growth factor (VEGF) in renal fibrosis, tubular cyst formation, and glomerular diseases is incompletely understood. We studied a new conditional transgenic mouse system [Pax8-rtTA/(tetO) 7 VEGF], which allows increased tubular VEGF production in adult mice. The following pathology was observed. The interstitial changes consisted of a ubiquitous proliferation of peritubular capillaries and fibroblasts, followed by deposition of matrix leading to a unique kind of fibrosis, ie, healthy tubules amid a capillary-rich dense fibrotic tissue. In tubular segments with high expression of VEGF, cysts developed that were surrounded by a dense network of peritubular capillaries. The glomerular effects consisted of a proliferative enlargement of glomerular capillaries, followed by mesangial proliferation. This resulted in enlarged glomeruli with loss of the characteristic lobular structure. Capillaries became randomly embedded into mesangial nodules, losing their filtration surface. Serum VEGF levels were increased, whereas endogenous VEGF production by podocytes was down-regulated. Taken together, this study shows that systemic VEGF interferes with the intraglomerular cross-talk between podocytes and the endocapillary compartment. It suppresses VEGF secretion by podocytes but cannot compensate for the deficit. VEGF from podocytes induces a directional effect, attracting the capillaries to the lobular surface, a relevant mechanism to optimize filtration surface. Systemic VEGF lacks this effect, leading to severe deterioration in glomerular architecture, similar to that seen in diabetic nephropathy.

Abstract-Herein, we show that the paired-related homeobox gene, Prx1, is required for lung vascularization. Initial studies revealed that Prx1 localizes to differentiating endothelial cells (ECs) within the fetal lung mesenchyme, and later within ECs forming vascular networks. To begin to determine whether Prx1 promotes EC differentiation, fetal lung mesodermal cells were transfected with full-length Prx1 cDNA, resulting in their morphological transformation to an endothelial-like phenotype. In addition, Prx1-transformed cells acquired the ability to form vascular networks on Matrigel. Thus, Prx1 might function by promoting pulmonary EC differentiation within the fetal lung mesoderm, as well as their subsequent incorporation into vascular networks. To understand how Prx1 participates in network formation, we focused on tenascin-C (TN-C), an extracellular matrix (ECM) protein induced by Prx1. Immunocytochemistry/ histochemistry showed that a TN-C-rich ECM surrounds Prx1-positive pulmonary vascular networks both in vivo and in tissue culture. Furthermore, antibody-blocking studies showed that TN-C is required for Prx1-dependent vascular network formation on Matrigel. Finally, to determine whether these results were relevant in vivo, we examined newborn Prx1-wild-type (ϩ/ϩ) and Prx1-null (Ϫ/Ϫ) mice and showed that Prx1 is critical for expression of TN-C and lung vascularization. These studies provide a framework to understand how Prx1 controls EC differentiation and their subsequent incorporation into functional pulmonary vascular networks. T o ensure efficient gas exchange in the postnatal lung, fetal pulmonary vessels form in parallel to the developing airways and as capillary networks surrounding the alveoli. Pulmonary endothelial cells (ECs) can be detected as early as embryonic day (E) 9.5 to 10 in the developing mouse lung. [1][2][3][4][5][6] Although multiple mechanisms lead to colonization of the lung by ECs, it is generally accepted that vasculogenesis (ie, differentiation of ECs from the uncommitted distal mesoderm and organization of endothelial progenitors into a primitive vascular plexus) and angiogenesis (ie, sprouting of pulmonary vessels from pre-existing central trunk vessels) represent principal processes that give rise to the lung vasculature. [2][3][4] By E14, differentiating proximal and distal pulmonary ECs form a 3-dimensional array of arteries, veins, and capillaries, which become invested by surrounding mesenchymal cells that have the potential to give rise to pericyte, smooth muscle, and adventitial cell layers. 5 Concurrently, a complex extracellular matrix (ECM) forms around the vessel wall, providing structural and functional cues to adjacent cells. 1 Adding to the complexity of generating a vascular network, the lung epithelium controls the development of the adjacent pulmonary vasculature and vice versa. 6 -8 Thus, gene expression within the lung needs to be precisely coordinated in time and space. Because homeobox genes encode transcription factors that dictate tissue patterning and...

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Interleukin-I (IL-1) molecules are cytokines involved in the acute-phase response against infection and injury. Three naturally occurring IL-1 molecules are known, two agonists: IL-la and IL-1P, and one antagonist, the 1L-1 receptor antagonist (IL-lra). Although IL-1 action protects the organism by enhancing the response to pathogens, its overproduction can lead to pathology and has been implicated in disease states that include septic shock, rheumatoid arthritis, graft versus host disease and certain leukemias. The crystal structure of IL-lra has been solved at 0.21-nm resolution by molecular replacement using the ILlp structure as a search model. The crystals contain two independent IL-lra molecules which are very similar, IL-lra has the same fold as IL-la and IL-ID. The fold consists of twelve P-strands which form a six-stranded P-barrel, closed on one side by three P-hairpin loops. Cys69 and Cysll6 are linked via a disulfide bond and Pro53 has been built in the cis-conformation. Comparison of the IL-lra structure with the IL-la and IL-1P structures present in the Protein Data Bank shows that a putative receptor interaction region, involving the N-terminus up to the beginning of strand pl and the loops D and G, is very different in the three IL-1 molecules. Other putative interaction regions, as identified with mutagenesis studies, are structurally conserved and rigid, allowing precise and specific interactions with the IL-1 receptor.