Matrix metalloproteinase 9‐mediated shedding of syndecan 4 in response to tumor necrosis factor α: a contributor to endothelial cell glycocalyx dysfunction

Abstract

The endothelial surface glycocalyx is a hydrated mesh in which proteoglycans are prominent. It is damaged in diseases associated with elevated levels of tumor necrosis factor α (TNF-α). We investigated the mechanism of TNF-α-induced disruption of the glomerular endothelial glycocalyx. We used conditionally immortalized human glomerular endothelial cells (GEnCs), quantitative PCR arrays, Western blotting, immunoprecipitation, immunofluorescence, and dot blots to examine the effects of TNF-α. TNF-α induced syndecan 4 (SDC4) mRNA up-regulation by 2.5-fold, whereas cell surface SDC4 and heparan sulfate (HS) were reduced by 36 and 30%, respectively, and SDC4 and sulfated glycosaminoglycan in the culture medium were increased by 52 and 65%, respectively, indicating TNF-α-induced shedding. Small interfering (siRNA) knockdown of SDC4 (by 52%) caused a corresponding loss of cell surface HS of similar magnitude (38%), and immunoprecipitation demonstrated that SDC4 and HS are shed as intact proteoglycan ectodomains. All of the effects of TNF-α on SDC4 and HS were abrogated by the metalloproteinase (MMP) inhibitor batimastat. Also abrogated was the associated 37% increase in albumin passage across GEnC monolayers. Specific MMP9 knockdown by siRNA similarly blocked TNF-α effects. SDC4 is the predominant HS proteoglycan in the GEnC glycocalyx. TNF-α-induced MMP9-mediated shedding of SDC4 is likely to contribute to the endothelial glycocalyx disruption observed in diabetes and inflammatory states.

Innate immune signaling induces expression and shedding of the heparan sulfate proteoglycan syndecan‐4 in cardiac fibroblasts and myocytes, affecting inflammation in the pressure‐overloaded heart

“…In Paper II, we observed a parallel upregulation of syndecan-4 and three sheddases proposed to regulate its shedding, 193,195 i.e. ADAMTS1, ADAMTS4 and MMP9.…”

“…This is evident from studies where inhibition of one or a small number of sheddases is found to profoundly affect shedding levels of a particular syndecan. 195,198,199 For instance, specific knockdown of MMP9 by siRNA completely blocked TNFα-induced syndecan-4 shedding from human glomerular endothelial cells. 195 In WT mice, shedding of syndecan-1 is increased in bleomysin-treated lungs, however the pattern of syndecan-1 staining remained unchanged and no syndecan-1 was detected in BAL fluid in MMP7 KO mice.…”

“…195,198,199 For instance, specific knockdown of MMP9 by siRNA completely blocked TNFα-induced syndecan-4 shedding from human glomerular endothelial cells. 195 In WT mice, shedding of syndecan-1 is increased in bleomysin-treated lungs, however the pattern of syndecan-1 staining remained unchanged and no syndecan-1 was detected in BAL fluid in MMP7 KO mice. 199 However, Pasqualon et al showed that in cultured lung epithelial tumor cells, constitutive shedding of overexpressed syndecan-1 was significantly reduced in ADAM17 KO mice.…”

Syndecan-4 ectodomain evokes mobilization of podocyte TRPC6 channels and their associated pathways: An essential role for integrin signaling

“…Sdc4 can be detected in many cell types, including glomerular endothelial cells [16] and podocytes [17]. Sdc4 is inserted into the plasma membrane as a type-1 single-pass core protein [18,19].…”

Glycocalyx Degradation after Pulmonary Transplantation Surgery

“…It has been previously observed that one of the enzymes that can damage the glycocalyx is HPSE, which may induce syndecan-1 shedding and represents an important determinant in the pathogenesis of several inflammatory disorders including pulmonary diseases such as inflammatory lung injury [31]. MMP-9 has also been studied in relation to glycocalyx degradation, and it can induce syndecan shedding in an inflammatory context [32]. In our study, increased activity of both HPSE and MMP-9 was observed after reperfusion, suggesting that, in the context of the pulmonary IRI, these could play a role in glycocalyx degradation.…”