Thrombospondin-1 is required for normal murine pulmonary homeostasis and its absence causes pneumonia.

Abstract

The thrombospondins are a family of extracellular calcium-binding proteins that modulate cellular phenotype. Thrombospondin-1 (TSP-1) reportedly regulates cellular attachment, proliferation, migration, and differentiation in vitro. To explore its function in vivo, we have disrupted the TSP-1 gene by homologous recombination in the mouse genome. Platelets from these mice are completely deficient in TSP-1 protein; however, thrombin-induced platelet aggregation is not diminished. TSP-1-deficient mice display a mild and variable lordotic curvature of the spine that is apparent from birth. These mice also display an increase in the number of circulating white blood cells, with monocytes and eosinophils having the largest percent increases. The brain, heart, kidney, spleen, stomach, intestines, aorta, and liver of TSP-1-deficient mice showed no major abnormalities. However, consistent with high levels of expression of TSP-1 in lung, we observe abnormalities in the lungs of mice that lack the protein. Although normal at birth, histopathological analysis of lungs from 4-wk-old TSP-1-deficient mice reveals extensive acute and organizing pneumonia, with neutrophils and macrophages. The macrophages stain for hemosiderin, indicating that diffuse alveolar hemorrhage is occurring. At later times, the number of neutrophils decreases and a striking increase in the number of hemosiderin-containing macrophages is observed associated with multiple-lineage epithelial hyperplasia and the deposition of collagen and elastin. A thickening and ruffling of the epithelium of the airways results from increasing cell proliferation in TSP-1-deficient mice. These results indicate that TSP-1 is involved in normal lung homeostasis.

Thrombospondin‐1–deficient mice exhibit increased vascular density during retinal vascular development and are less sensitive to hyperoxia‐mediated vessel obliteration

“…However, the role TSP1 plays during vascular development and neovascularization requires further delineation. The TSP1-/-mice appear to develop and reproduce normally with some subtle differences when compared with normal mice (Lawler et al, 1998). Here, we demonstrate that (1) the TSP1-/-mice exhibit an increased retinal vascular density, which is most apparent at the later stages of retinal vascular development; (2) the retinas of TSP1-/-mice were less sensitive to hyperoxia-mediated vessel obliteration compared with wildtype mice, but exhibited a similar neovascularization response during oxygen-induced ischemic retinopathy; (3) the retinal vasculature of TSP1-/-mice exhibited reduced number of apoptotic nuclei during remodeling and maturation; (4) the TSP1 expression increased during normal development of retinal vasculature, but its expression was not affected during oxygen-induced ischemic retinopathy; (5) the VEGF expression was also up-regulated during development of retinal vasculature, but its expression was further induced during oxygen-induced ischemic retinopathy independent of TSP1 expression; and (6) the regression of hyaloid vessels, and the newly formed retinal vessels in oxygen-induced ischemic retinopathy, was delayed in TSP1-/-mice.…”

“…Generation of TSP1-/-mice on a C57BL6 background was described previously (Lawler et al, 1998). TSP1-/-mice and wild-type C57BL/6 mice (Jackson Labs) were maintained at the University of Wisconsin animal facilities and studies were performed according to approved protocols.…”

“…TSP1-/-mice develop normally, although they exhibit delayed wound healing and develop pneumonia later in life (Lawler et al, 1998;Lawler, 2000). To gain a better understanding of the role TSP1 plays in retinal vascular development and retinal neovascularization during oxygen-induced ischemic retinopathy, we have used the TSP1-/-mice.…”

The effect of thrombospondin-1 on breast cancer metastasis

“…Generation of the TSP-1-null mouse on the 129Sv background was carried out previously in the lab [34]. These mice were backcrossed to wild type FVB mice (Taconic Farms) eight times and then intercrossed to produce TSP-1-null mice on the FVB background.…”

“…In both cell lines that were used in this manuscript, the tumor cell preparations contained approximately 30% fibroblasts. To verify the genotype of the cell lines, DNA was isolated from cells not used in the assay using the Qiamp DNA Mini Kit (Valencia, CA), and PCR amplification was carried out using oligos that have been previously described [34]. In all cases, the cells were the correct genotype.…”