Non-vascular Cell Types Research Articles

Cyclooxygenase-2 regulates granulocyte-macrophage colony-stimulating factor, but not interleukin-8, production by human vascular cells: role of cAMP.

Vascular smooth muscle is now recognized as an important site of mediator generation under inflammatory conditions. Indeed, the release of leukocyte activators, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-8, by human arterial smooth muscle cells has recently been demonstrated. However, the potential for venous cells to release GM-CSF has not been addressed. We have shown that human vascular smooth muscle cells express the "inflammatory" form of cyclooxygenase (COX), cyclooxygenase-2 (COX-2), when stimulated with cytokines. In some nonvascular cell types, the COX activity has been shown to regulate the release of GM-CSF and IL-8, although the nature of the isoform responsible was not addressed. We show that human venous smooth muscle cells, like their arterial counterparts, release GM-CSF after stimulation with IL-1beta. Similarly, both cell types released IL-8. Under the same conditions, we found that COX-2 activity suppressed GM-CSF, but not IL-8, release by both types of human vascular cells. Moreover, the prostacyclin mimetic, cicaprost, and the cAMP analogue, dibutyryl cAMP, inhibited GM-CSF release from these cells. These observations suggest that COX-2 activity suppresses GM-CSF release via a cAMP-dependent pathway in human vascular cells and illustrates a novel mechanism by which this enzyme can modulate immune and inflammatory events.

The interstitial cells of the trout testis ( Oncorhynchus mykiss): ultrastructural characterization and changes throughout the reproductive cycle

The major non-vascular cell types present in the interstitial compartment in trout testes have been ultrastructurally characterized and cell changes in the course of the two first reproductive cycles have been studied. Three major cell types are always present fibroblasts, myoid cells and Leydig cells. Their structure varies with the maturational stage of the gonad. Fibroblasts are centrally located in the interstitial areas. Numerous typical myoid cells are always present near the basal lamina. However, at the end of a cycle some of them display degenerative changes, then disappear. At the beginning of the next cycle, fibroblasts appear to differentiate to new myoid cells. Leydig cells present before the start of the first spermatogenesis are replaced by new ones which probably also arise from fibroblasts. These cells progressively differentiate during spermatogenesis, so that most of the Leydig cells present during the spermiation phase are fully-differentiated steroidogenic cells. At the end of a cycle, a certain number of the Leydig cells disappear and are replaced at the beginning of the next cycle by new ones most likely derived from fibroblasts. The remaining Leydig cells dedifferentiate to cells which may redifferentiate during gonadal activity. Macrophages are present mostly at the end of a cycle and participate at this time in the removal of dead interstitial cells. In conclusion, at least some fibroblast-like cells are precursor cells, able to replace myoid cells and Leydig cells which disappear between two consecutive reproductive cycles.

Vascular-specific expression of the bean GRP 1.8 gene is negatively regulated.

In French bean, the glycine-rich cell wall protein GRP 1.8 is specifically synthesized in the vascular tissue. To identify cis-acting sequences required for cell type-specific synthesis of GRP 1.8, expression patterns of fusion gene constructs were analyzed in transgenic tobacco. In these constructs, the uidA (beta-glucuronidase) gene was placed under control of 5' upstream deletions as well as internal deletions of the GRP 1.8 promoter. Four different cis-acting regulatory regions, SE1 and SE2 (stem elements), a negative regulatory element, and a root-specific element, were found to control the tissue-specific expression. Deletion of the negative regulatory element resulted in expression of the uidA gene in cell types other than vascular cells. The SE1 region was essential for expression in several cell types in the absence of further upstream regulatory sequences. Full-length promoters having insertions between the negative regulatory element and SE1 strongly expressed the gene in nonvascular cell types in stems and leaves. Thus, vascular-specific expression of the GRP 1.8 promoter is controlled by a complex set of positive and negative interactions between cis-acting regulatory regions. The disturbance of these interactions results in expression in additional cell types.