Connective tissue growth factor is correlated with peritoneal lymphangiogenesis.

Lymphatic absorption in the peritoneal cavity may contribute to ultrafiltration failure in peritoneal dialysis (PD). Lymphatic vessels develop during PD-related peritoneal fibrosis. Connective tissue growth factor (CTGF, also called CCN2) is an important determinant of fibrotic tissue remodeling, but little is known about its possible involvement in lymphangiogenesis. In this study, we investigated the relationship between CTGF and peritoneal lymphangiogenesis. A positive correlation was observed between vascular endothelial growth factor-C (VEGF-C), a major lymphangiogenic growth factor, and the CTGF concentration in human PD effluents. CTGF expression was positively correlated with expression of lymphatic markers and VEGF-C in human peritoneal biopsies. We found a positive correlation between the increase in CTGF and the increase in VEGF-C in cultured human peritoneal mesothelial cells (HPMCs) treated with transforming growth factor-β1 (TGF-β1). The diaphragm is a central player in peritoneal lymphatic absorption. CTGF expression was also correlated with expression of VEGF-C and lymphatics in a rat diaphragmatic fibrosis model induced by chlorhexidine gluconate (CG). Furthermore, CTGF gene deletion reduced VEGF-C expression and peritoneal lymphangiogenesis in the mouse CG model. Inhibition of CTGF also reduced VEGF-C upregulation in HPMCs treated with TGF-β1. Our results suggest a close relationship between CTGF and PD-associated lymphangiogenesis

CTGF and lymphangiogenesis in renal and peritoneal fibrosis

Long term peritoneal dialysis (PD) treatment results in submesothelial fibrosis, neoangiogenesis, and ultrafiltration failure (UFF). Peritoneal lymphangiogenesis with increased lymphatic absorption is very likely to contribute to UFF in peritoneal fibrosis. We generated two non-bacterial rat models, a scraping model and a zymosan injection model, which are useful for investigating the pathophysiology of fibrosis, neoangiogenesis, and lymphangiogenesis triggered by peritonitis-induced inflammation. We found that transforming growth factor-b (TGF-b) increased expression of an important lymphangiogenic growth factor, vascular endothelial growth factor (VEGF)-C in peritoneal mesothelial cells. Inhibition of TGF-b signaling reduced VEGF-C expression and lymphangiogenesis in parallel with reduction of fibrosis and inflammation, and that treatment with soluble VEGF receptor (VEGFR)-3 specifically suppressed lymphangiogenesis and improved impaired ultrafiltration in a peritoneal fibrosis model. Blocking of VEGFR-3 signaling might be a useful strategy to improve lymphangiogenesis-dependent UFF. Connective tissue growth factor (CTGF/CCN2), an important determinant of fibrotic tissue remodeling, was also associated with VEGF-C expression and lymphangiogenesis in human PD effluents, human peritoneal biopsies, and in a rat peritoneal fibrosis model, and a positive correlation between CTGF and VEGF-C enhancement was observed in peritoneal mesothelial cells treated with TGF-b1, implying a possible novel role for CTGF in PD-related peritoneal lymphangiogenesis. Lymphangiogenesis is also associated with tubulointerstitial fibrosis in kidney diseases. We observed that TGF-b, VEGF-C, and lymphatic vessels were time-dependently increased in a rat unilateral ureteral obstruction (UUO) model, and that TGF-b increased VEGF-C production in cultured renal tubular cells and macrophages, while inhibition of TGF-b signaling reduced VEGF-C expression and lymphatic vessel formation in the UUO model, similar to our findings in the peritoneal fibrosis model. Furthermore, CTGF knockdown reduced VEGF-C expression and decreased lymphangiogenesis in parallel with reduction of fibrosis in the mouse UUO model, while CTGF increased VEGF-C production in renal tubular cells. On the other hand, CTGF could directly bind to VEGF-C, and thereby suppress VEGF-C-induced lymphatic endothelial cells growth, but this direct inhibitory effect of CTGF on VEGF-C was abrogated by cleavage of CTGF. Thus, we identified a role for CTGF in renal lymphangiogenesis both through the regulation of VEGF-C production and activity. We also evaluated the effect of aging on tissue response to kidney injury, and found that UUO kidneys of old mice showed less interstitial fibrosis compared to young mice. This was associated with increased bone morphogenetic protein (BMP) 6 and decreased CTGF expression. Our further observations that CTGF directly bound to BMP6 and suppressed BMP6 downstream signaling, suggested that the renoprotective effects of preserved BMP6 expression might be further upregulated by the lower CTGF expression in old UUO kidneys might be responsible for the less fibrotic response in older kidneys. Finally, CTGF is also an important mediator of renal allograft fibrosis and we identified tubulointerstitial CTGF [removed]CTGFti) at 3 months as an independent predictor of interstitial fibrosis (IF) and tubular atrophy (TA) at 5 years after transplantation in stable renal transplant recipients, and that CTGFti and urinary CTGF levels at 3 months when added to donor age improved prediction of later IF/TA development

CTGF and lymphangiogenesis in renal and peritoneal fibrosis

Long term peritoneal dialysis (PD) treatment results in submesothelial fibrosis, neoangiogenesis, and ultrafiltration failure (UFF). Peritoneal lymphangiogenesis with increased lymphatic absorption is very likely to contribute to UFF in peritoneal fibrosis. We generated two non-bacterial rat models, a scraping model and a zymosan injection model, which are useful for investigating the pathophysiology of fibrosis, neoangiogenesis, and lymphangiogenesis triggered by peritonitis-induced inflammation. We found that transforming growth factor-b (TGF-b) increased expression of an important lymphangiogenic growth factor, vascular endothelial growth factor (VEGF)-C in peritoneal mesothelial cells. Inhibition of TGF-b signaling reduced VEGF-C expression and lymphangiogenesis in parallel with reduction of fibrosis and inflammation, and that treatment with soluble VEGF receptor (VEGFR)-3 specifically suppressed lymphangiogenesis and improved impaired ultrafiltration in a peritoneal fibrosis model. Blocking of VEGFR-3 signaling might be a useful strategy to improve lymphangiogenesis-dependent UFF. Connective tissue growth factor (CTGF/CCN2), an important determinant of fibrotic tissue remodeling, was also associated with VEGF-C expression and lymphangiogenesis in human PD effluents, human peritoneal biopsies, and in a rat peritoneal fibrosis model, and a positive correlation between CTGF and VEGF-C enhancement was observed in peritoneal mesothelial cells treated with TGF-b1, implying a possible novel role for CTGF in PD-related peritoneal lymphangiogenesis. Lymphangiogenesis is also associated with tubulointerstitial fibrosis in kidney diseases. We observed that TGF-b, VEGF-C, and lymphatic vessels were time-dependently increased in a rat unilateral ureteral obstruction (UUO) model, and that TGF-b increased VEGF-C production in cultured renal tubular cells and macrophages, while inhibition of TGF-b signaling reduced VEGF-C expression and lymphatic vessel formation in the UUO model, similar to our findings in the peritoneal fibrosis model. Furthermore, CTGF knockdown reduced VEGF-C expression and decreased lymphangiogenesis in parallel with reduction of fibrosis in the mouse UUO model, while CTGF increased VEGF-C production in renal tubular cells. On the other hand, CTGF could directly bind to VEGF-C, and thereby suppress VEGF-C-induced lymphatic endothelial cells growth, but this direct inhibitory effect of CTGF on VEGF-C was abrogated by cleavage of CTGF. Thus, we identified a role for CTGF in renal lymphangiogenesis both through the regulation of VEGF-C production and activity. We also evaluated the effect of aging on tissue response to kidney injury, and found that UUO kidneys of old mice showed less interstitial fibrosis compared to young mice. This was associated with increased bone morphogenetic protein (BMP) 6 and decreased CTGF expression. Our further observations that CTGF directly bound to BMP6 and suppressed BMP6 downstream signaling, suggested that the renoprotective effects of preserved BMP6 expression might be further upregulated by the lower CTGF expression in old UUO kidneys might be responsible for the less fibrotic response in older kidneys. Finally, CTGF is also an important mediator of renal allograft fibrosis and we identified tubulointerstitial CTGF [removed]CTGFti) at 3 months as an independent predictor of interstitial fibrosis (IF) and tubular atrophy (TA) at 5 years after transplantation in stable renal transplant recipients, and that CTGFti and urinary CTGF levels at 3 months when added to donor age improved prediction of later IF/TA development

Roles of the TGF-β–VEGF-C Pathway in Fibrosis-Related Lymphangiogenesis

Lymphatic vessels drain excess tissue fluids to maintain the interstitial environment. Lymphatic capillaries develop during the progression of tissue fibrosis in various clinical and pathological situations, such as chronic kidney disease, peritoneal injury during peritoneal dialysis, tissue inflammation, and tumor progression. The role of fibrosis-related lymphangiogenesis appears to vary based on organ specificity and etiology. Signaling via vascular endothelial growth factor (VEGF)-C, VEGF-D, and VEGF receptor (VEGFR)-3 is a central molecular mechanism for lymphangiogenesis. Transforming growth factor-β (TGF-β) is a key player in tissue fibrosis. TGF-β induces peritoneal fibrosis in association with peritoneal dialysis, and also induces peritoneal neoangiogenesis through interaction with VEGF-A. On the other hand, TGF-β has a direct inhibitory effect on lymphatic endothelial cell growth. We proposed a possible mechanism of the TGF-β–VEGF-C pathway in which TGF-β promotes VEGF-C production in tubular epithelial cells, macrophages, and mesothelial cells, leading to lymphangiogenesis in renal and peritoneal fibrosis. Connective tissue growth factor (CTGF) is also involved in fibrosis-associated renal lymphangiogenesis through interaction with VEGF-C, in part by mediating TGF-β signaling. Further clarification of the mechanism might lead to the development of new therapeutic strategies to treat fibrotic diseases

Peritonitis-induced peritoneal injury models for research in peritoneal dialysis review of infectious and non-infectious models

Abstract Peritonitis is an important complication of peritoneal dialysis. Several animal peritonitis models have been described, including bacterial and fungal models that are useful for studying inflammation in peritonitis. However, these models have limitations for investigating peritoneal fibrosis induced by acute inflammation and present difficulties in handling the infected animals. Animal models of peritonitis which induced peritoneal fibrosis are important for establishing new therapies to improve peritoneal damage induced by peritonitis. Here, we present an overview of representative animal models of peritoneal dialysis-associated infectious and non-infectious peritonitis, including our novel animal models (scraping and zymosan models) that mimic peritoneal injury associated with fibrosis and neoangiogenesis caused by bacterial or fungal peritonitis

Connective tissue growth factor regulates fibrosis-associated renal lymphangiogenesis

Lymphangiogenesis is correlated with the degree of renal interstitial fibrosis. Pro-fibrotic transforming growth factor β induces VEGF-C production, the main driver of lymphangiogenesis. Connective tissue growth factor (CTGF) is an important determinant of fibrotic tissue remodeling, but its possible involvement in lymphangiogenesis has not been explored. We found prominent lymphangiogenesis during tubulointerstitial fibrosis to be associated with increased expression of CTGF and VEGF-C in human obstructed nephropathy as well as in diabetic kidney disease. Using CTGF knockout mice, we investigated the involvement of CTGF in development of fibrosis and associated lymphangiogenesis in obstructive nephropathy. The increase of lymphatic vessels and VEGF-C in obstructed kidneys was significantly reduced in CTGF knockout compared to wild-type mice. Also in mouse kidneys subjected to ischemia-reperfusion injury, CTGF knockdown was associated with reduced lymphangiogenesis. In vitro, CTGF induced VEGF-C production in HK-2 cells, while CTGF siRNA suppressed transforming growth factor β1-induced VEGF-C upregulation. Furthermore, surface plasmon resonance analysis showed that CTGF and VEGF-C directly interact. Interestingly, VEGF-C-induced capillary-like tube formation by human lymphatic endothelial cells was suppressed by full-length CTGF but not by naturally occurring proteolytic CTGF fragments. Thus, CTGF is significantly involved in fibrosis-associated renal lymphangiogenesis through regulation of, and direct interaction with, VEGF-C

Connective tissue growth factor regulates fibrosis-associated renal lymphangiogenesis

Lymphangiogenesis is correlated with the degree of renal interstitial fibrosis. Pro-fibrotic transforming growth factor β induces VEGF-C production, the main driver of lymphangiogenesis. Connective tissue growth factor (CTGF) is an important determinant of fibrotic tissue remodeling, but its possible involvement in lymphangiogenesis has not been explored. We found prominent lymphangiogenesis during tubulointerstitial fibrosis to be associated with increased expression of CTGF and VEGF-C in human obstructed nephropathy as well as in diabetic kidney disease. Using CTGF knockout mice, we investigated the involvement of CTGF in development of fibrosis and associated lymphangiogenesis in obstructive nephropathy. The increase of lymphatic vessels and VEGF-C in obstructed kidneys was significantly reduced in CTGF knockout compared to wild-type mice. Also in mouse kidneys subjected to ischemia-reperfusion injury, CTGF knockdown was associated with reduced lymphangiogenesis. In vitro, CTGF induced VEGF-C production in HK-2 cells, while CTGF siRNA suppressed transforming growth factor β1-induced VEGF-C upregulation. Furthermore, surface plasmon resonance analysis showed that CTGF and VEGF-C directly interact. Interestingly, VEGF-C-induced capillary-like tube formation by human lymphatic endothelial cells was suppressed by full-length CTGF but not by naturally occurring proteolytic CTGF fragments. Thus, CTGF is significantly involved in fibrosis-associated renal lymphangiogenesis through regulation of, and direct interaction with, VEGF-C

Tubulointerstitial expression and urinary excretion of connective tissue growth factor 3 months after renal transplantation predict interstitial fibrosis and tubular atrophy at 5 years in a retrospective cohort analysis

Connective tissue growth factor (CTGF) is an important mediator of renal allograft fibrosis, and urinary CTGF (CTGFu) levels correlate with the development of human allograft interstitial fibrosis. We evaluated the predictive value of CTGF protein expression in 160 kidney transplant recipients with paired protocol biopsies at 3 months and 5 years after transplantation. At month 3 and year 1, CTGFu was measured using ELISA, and biopsies were immunohistochemically stained for CTGF, with semiquantitative scoring of tubulointerstitial CTGF-positive area (CTGFti). Predictors of interstitial fibrosis and tubular atrophy (IF/TA) severity at 5 years were donor age [OR 1.05 (1.02-1.08), P = 0.001], female donor [OR 0.40 (0.18-0.90), P = 0.026], induction therapy [OR 2.76 (1.10-6.89), P = 0.030], and CTGFti >10% at month 3 [OR 2.72 (1.20-6.15), P = 0.016]. In subgroups of patients with little histologic damage at 3 months [either ci score 0 (n = 119), IF/TA score ≤1 (n = 123), or absence of IF/TA, interstitial inflammation, and tubulitis (n = 45)], consistent predictors of progression of chronic histologic damage by 5 years were donor age, induction therapy, CTGFti >10%, and CTGFu. These results suggest that, even in patients with favorable histology at 3 months, significant CTGF expression is often present which may predict accelerated accumulation of histologic damage.status: publishe

Age-dependent shifts in renal response to injury relate to altered BMP6/CTGF expression and signaling

Age is associated with an increased prevalence of chronic kidney disease (CKD), which, through progressive tissue damage and fibrosis, ultimately leads to loss of kidney function. Although much effort is put into studying CKD development experimentally, age has rarely been taken into account. Therefore, we investigated the effect of age on the development of renal tissue damage and fibrosis in a mouse model of obstructive nephropathy (i.e., unilateral ureter obstruction; UUO). We observed that after 14 days, obstructed kidneys of old mice had more tubulointerstitial atrophic damage but less fibrosis than those of young mice. This was associated with reduced connective tissue growth factor (CTGF), and higher bone morphogenetic protein 6 (BMP6) expression and pSMAD1/5/8 signaling, while transforming growth factor-β expression and transcriptional activity were no different in obstructed kidneys of old and young mice. In vitro, CTGF bound to and inhibited BMP6 activity. In summary, our data suggest that in obstructive nephropathy atrophy increases and fibrosis decreases with age and that this relates to increased BMP signaling, most likely due to higher BMP6 and lower CTGF expression