Acta Ophthalmologica 2015
Levels of angiogenesis-related vascular endothelial growth factor family in neovascular glaucoma eyes Shida Chen,1 Minwen Zhou,1,2,3 Wei Wang,1 Huimin Wu,1 Xiling Yu,1 Wenbin Huang,1 Xinbo Gao,1 Jiawei Wang,1 Xingyi Li,1 Shaolin Du,1 Xiaoyan Ding1 and Xiulan Zhang1 1
Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, China Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, China 3 Shanghai Key Laboratory of Fundus Disease, Shanghai, China 2
ABSTRACT. Purpose: This study aimed to evaluate the angiogenesis-related factors of the vascular endothelial growth factor (VEGF) family in the aqueous humour of patients with neovascular glaucoma (NVG). Methods: This study involved 22 eyes of 22 patients with advanced NVG requiring antiglaucomatous surgery and 20 control subjects with cataracts. The NVG eyes received an intravitreal injection of ranibizumab (IVR) treatment before antiglaucomatous surgery. Aqueous humour and blood were collected at the time of IVR and cataract surgery. Protein concentration of VEGF-A, VEGF-B and placenta growth factor (PlGF) in aqueous humour and plasma was determined by ELISA tests. Results: The mean concentration (standard deviation) of VEGF-A and PlGF in the aqueous humour of patients with NVG were 3037 (2387) pg/ml and 1078 (712) pg/ ml, respectively; both were significantly higher than the control group (both p < 0.001). However, levels of VEGF-A and PlGF in the serum of NVG and control subjects remained low. High concentrations of VEGF-A were closely correlated with high levels of PlGF in patients with NVG (r = 0.593, p = 0.004). Concentrations of VEGF-B in aqueous humour and serum remained unchanged (p > 0.05). Conclusion: There were high concentrations of angiogenesis factors of the VEGF family, with the exception of VEGF-B, in the aqueous humour of patients with NVG, and there was a positive correlation between VEGF-A and PlGF. High PlGF levels in patients with NVG may provide another potential target for treatment of NVG. Key words: neovascular glaucoma – PlGF – VEGF-A – VEGF-B
Acta Ophthalmol. 2015: 93: e556–e560 ª 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd
doi: 10.1111/aos.12624
Introduction Neovascular glaucoma (NVG) is a disease characterized as intractable, difficult to manage and often resulting in disastrous vision loss. The most common diseases responsible for development of NVG are ischaemic central retinal vein
e556
occlusion (CRVO), diabetic retinopathy and ocular ischaemic syndrome (Hayreh 2007). It is believed that a high concentration of vascular endothelial growth factor A (VEGF-A) in the aqueous humour is the one of the major cause of NVG (Tripathi et al. 1998; Horsley &
Kahook 2010). Anti-VEGF agents, which is a recombinant, humanized, monoclonal antibody Fab that neutralizes all active forms of VEGF-A, have been shown to be beneficial in treating NVG (Grisanti et al. 2006; Horsley & Kahook 2010). However, the precise pathophysiologic mechanisms of NVG are speculative, and anti-VEGF treatment alone does not completely inhibit NVG (Wakabayashi et al. 2008). Furthermore, current anti-VEGF therapy focuses on a single pathogenic mechanism, but other growth factors or cytokines may influence disease progression and recurrence (Hayreh 2007). The VEGF family, which comprises VEGFA, VEGF-B, VEGF-C, placenta growth factor (PlGF) and VEGF-D, plays an essential role in the angiogenesis process. Among the factors, VEGF-C and VEGF-D are mainly involved in lymphangiogenesis, and VEGF-A and PlGF are prominently involved in angiogenesis (Witmer et al. 2003; Takahashi 2011). The role of VEGF-B in the angiogenesis is controversial (Li et al. 2012). The role of other angiogenic factors of the VEGF family in the development of NVG remains unknown, and this study aimed to study the angiogenesis-related factors of the VEGF family in the aqueous humour of eyes with NVG.
Patients and Methods Subjects and enrolment criteria
This prospective, comparative study was approved by the Ethical Review
Acta Ophthalmologica 2015
Table 1. Characteristics of the subjects. Characteristic
NVG
Control
p-value
No. of eyes Age, y (SD) Sex, Male/Female IOP, mmHg (SD) DM HR
22 55.5 (19.6) 16/6 46.0 (7.2) 7 3
20 60.9 (5.9) 8/12 13.6 (2.5) 0 0
N/A 0.05). In addition, there were no significant correlations between aqueous humour levels and plasma levels of VEGF family factors in either group (all p > 0.05).
Discussion Our study showed that concentrations of VEGF-A and PlGF in aqueous humour were significantly greater in
patients with NVG; however, the level of VEGF-B remained unchanged compared to the control group. The study also found that an increased level of VEGF-A was closely correlated with an increased level of PlGF in the aqueous humour of patients with NVG. The finding of increased levels of VEGF-A in aqueous humour of patients with NVG was consistent with our previous study (Zhou et al. 2013). VEGF-A has been explored fully as a crucial angiogenic factor and potent vascular-permeable factor with great selectivity for endothelial cells (Otani et al. 2002), and anti-VEGF treatment has been efficient in patients with NVG. It was found that IVR could decrease iris fluorescein angiography leakage as early as 1 day after injection and could last for a month (Grisanti et al. 2006). In addition, our previous study found that bevacizumab significantly decreased the level of VEGF in the aqueous humour of patients with NVG, which, in turn, significantly decreased the neovascularization of the iris (Zhou et al. 2013). However, we found that neovascularization of the iris does not disappear completely, even after anti-VEGF therapy in a clinical setting. We hypothesize that other angiogenesis factors may contribute to neovascularization of the iris. PlGF is expressed in the placenta predominantly, and it has been found that PlGF not only can induce angiogenesis by itself but also by enhancing VEGF-A activity by heterodimeriza-
tion (DiSalvo et al. 1995). PlGF can bind to VEGFR-1 to promote recruitment of bone marrow-derived cells and stimulate retinal neovascularization (Carmeliet et al. 2001). In addition, PlGF could also increase vessel permeability and inflammation (Odorisio et al. 2002; Oura et al. 2003). PlGF/ VEGF heterodimers have been found in the synovial fluid of patients with inflammatory arthropathies, and PlGF upregulates production of VEGF in peripheral blood mononuclear cells (Bottomley et al. 2000). Yoshinori et al. found that levels of PlGF and VEGF in the vitreous fluid of patients with diabetic retinopathy were increased significantly compared to the control group, and both closely correlated with each other (Mitamura et al. 2002). In our study, both VEGF-A and PlGF were increased in the aqueous humour of patients with NVG, and they closely correlated with each other. This is consistent with another study, which found that concentrations of PlGF correlated closely with concentrations of VEGF in the aqueous humours of patients with diffuse diabetic macular oedema (Jonas et al. 2012). All the results, including those of our study, suggesting that PlGF may have a synergistic effect with VEGF-A in the development of NVG, which may enhance the angiogenesis effect of VEGF-A in the pathogenesis of NVG. Furthermore, current anti-VEGF methods is insufficient to inhibit NVG, regardless of the effect of PlGF. Combination therapy, such as adjunctive PlGF with VEGF blockade, is likely to be beneficial in treating NVG. Although VEGF-B binds to the same receptor including VEGFR-1 and NRP-1 as PlGF, it is a multifaceted factor that could act as an angiogenesis factor and that also has antiangiogenesis properties under different conditions (Li et al. 2012). In mice, adeno-associated viral delivery of VEGF-B to the skeletal or heart muscle induced very little angiogenesis, vascular permeability or inflammation (Bry et al. 2010). However, overexpression of VEGF-B in the mouse retina promoted pathological retinal and choroidal neovascularization and breakdown of the blood-retinal barrier (Zhong et al. 2011). More recently, Singh et al. found that hypoxia-induced VEGF-B expression in mouse retina and deletion of VEGF-B attenuated hypoxia-
e559
Acta Ophthalmologica 2015
induced retinal neovascularization (Singh et al. 2013). These controversial findings may suggest VEGF-B is more tissue specific and had different role in different tissues under vary conditions. In our study, the level of VEGF-B did not change in the NVG group compared to the control group, which may suggest VEGF-B may not involve in the pathogenesis of NVG; however, the exact role of VEGF-B in NVG needs more research. This study also explored factors that will potentially influence the level of angiogenesis VEGF factors. First, we measured plasma levels of the three VEGF family factors in both study groups. Results showed that their concentrations remained low, and there was no significant difference between the two groups. In addition, correlation analysis revealed no correlation between aqueous levels and plasma levels of VEGF factors in either group. These findings indicate that increased aqueous levels of VEGF-A and PlGF are not due to systemic disease. Instead, levels likely are the result of increased local production in the retina, followed by leakage into the anterior chamber. Various underlying diseases contribute to development of NVG, including CRVO, diabetic retinopathy and ocular ischaemic syndrome (Hayreh 2007). Although in our study, the underlying diseases mechanisms were not found to contribute significantly to increased levels of VEGF family factors, this may because of the small sample for each different underlying disease. It is not surprising that this study did not find any relationship between levels of VEGF family factors and IOP, because IOP mainly is determined by the extent of anterior synechiae and angle closure by the fibrovascular membrane. Furthermore, another reason is that all the patients with NVG have already being treated for increased IOP, so it will have some effect when exploring the relation between the IOP and the levels of factors. This study has several limitations. First, only 22 eyes included in our study, which is considered a small sample size, especially when considering the influence of underlying diseases. Second, antiglaucomatous drugs used in NVG might have affected VEGF family factors concentrations in the aqueous humour. Finally, we tested the level of
e560
VEGF family factors only before treatment with ranibizumab. In future, we should test for these factors before and after IVR treatment and follow-up to see the therapeutic effect.
References Bottomley MJ, Webb NJ, Watson CJ, Holt L, Bukhari M, Denton J, Freemont AJ & Brenchley PE (2000): Placenta growth factor (PlGF) induces vascular endothelial growth factor (VEGF) secretion from mononuclear cells and is co-expressed with VEGF in synovial fluid. Clin Exp Immunol 119: 182–188. Bry M, Kivela R, Holopainen T et al. (2010): Vascular endothelial growth factor-B acts as a coronary growth factor in transgenic rats without inducing angiogenesis, vascular leak, or inflammation. Circulation 122: 1725–1733. Carmeliet P, Moons L, Luttun A et al. (2001): Synergism between vascular endothelial growth factor and placental growth factor contributes to angiogenesis and plasma extravasation in pathological conditions. Nat Med 7: 575–583. DiSalvo J, Bayne ML, Conn G et al. (1995): Purification and characterization of a naturally occurring vascular endothelial growth factor. Placenta growth factor heterodimer. J Biol Chem 270: 7717–7723. Grisanti S, Biester S, Peters S, Tatar O, Ziemssen F & Bartz-Schmidt KU (2006): Intracameral bevacizumab for iris rubeosis. Am J Ophthalmol 142: 158–160. Hayreh SS (2007): Neovascular glaucoma. Prog Retin Eye Res 26: 470–485. Horsley MB & Kahook MY (2010): Anti-VEGF therapy for glaucoma. Curr Opin Ophthalmol 21: 112–117. Jonas JB, Jonas RA, Neumaier M & Findeisen P (2012): Cytokine concentration in aqueous humor of eyes with diabetic macular edema. Retina 32: 2150–2157. Li X, Kumar A, Zhang F, Lee C & Tang Z (2012): Complicated life, complicated VEGF-B. Trends Mol Med 18: 119–127. Mitamura Y, Tashimo A, Nakamura Y, Tagawa H, Ohtsuka K, Mizue Y & Nishihira J (2002): Vitreous levels of placenta growth factor and vascular endothelial growth factor in patients with proliferative diabetic retinopathy. Diabetes Care 25: 2352. Odorisio T, Schietroma C, Zaccaria ML, Cianfarani F, Tiveron C, Tatangelo L, Failla CM & Zambruno G (2002): Mice overexpressing placenta growth factor exhibit increased vascularization and vessel permeability. J Cell Sci 115: 2559–2567. Otani A, Takagi H, Oh H, Koyama S, Ogura Y, Matumura M & Honda Y (2002): Vascular endothelial growth factor family and receptor expression in human choroidal neovascular membranes. Microvasc Res 64: 162–169. Oura H, Bertoncini J, Velasco P, Brown LF, Carmeliet P & Detmar M (2003): A critical role of placental growth factor in the induction of inflammation and edema formation. Blood 101: 560–567. Singh NK, Hansen DE 3rd, Kundumani-Sridharan V & Rao GN (2013): Both Kdr and Flt1 play a vital role in hypoxia-induced Src-PLD1-
PKCgamma-cPLA(2) activation and retinal neovascularization. Blood 121: 1911–1923. Takahashi S (2011): Vascular endothelial growth factor (VEGF), VEGF receptors and their inhibitors for antiangiogenic tumor therapy. Biol Pharm Bull 34: 1785–1788. Tripathi RC, Li J, Tripathi BJ, Chalam KV & Adamis AP (1998): Increased level of vascular endothelial growth factor in aqueous humor of patients with neovascular glaucoma. Ophthalmology 105: 232–237. Wakabayashi T, Oshima Y, Sakaguchi H et al. (2008): Intravitreal bevacizumab to treat iris neovascularization and neovascular glaucoma secondary to ischemic retinal diseases in 41 consecutive cases. Ophthalmology 115: 1571– 1580, 1580. e1-3. Witmer AN, Vrensen GF, Van Noorden CJ & Schlingemann RO (2003): Vascular endothelial growth factors and angiogenesis in eye disease. Prog Retin Eye Res 22: 1–29. Zhong X, Huang H, Shen J, Zacchigna S, Zentilin L, Giacca M & Vinores SA (2011): Vascular endothelial growth factor-B gene transfer exacerbates retinal and choroidal neovascularization and vasopermeability without promoting inflammation. Mol Vis 17: 492–507. Zhou M, Chen S, Wang W, Huang W, Cheng B, Ding X & Zhang X (2013): Levels of erythropoietin and vascular endothelial growth factor in surgery-required advanced neovascular glaucoma eyes before and after intravitreal injection of bevacizumab. Invest Ophthalmol Vis Sci 54: 3874–3879.
Received on May 27th, 2014. Accepted on October 31st, 2014. Correspondence: Xiulan Zhang, MD, PhD Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology Sun Yat-sen University 54S. Xianlie Road Guangzhou, China 510060 Tel: +86 20 87330484 Fax: +86 20 87333271 Email: [email protected] and Xiaoyan Ding, MD, PhD Department of Vitreo-retinopathy, Zhongshan Ophthalmic Center State Key Laboratory of Ophthalmology Sun Yat-sen University 54S. Xianlie Road Guangzhou, China 510060 Tel: +86-20-87330373 Fax: +86-20-87333271 Email: [email protected] This research was supported by the National Natural Science Foundation of China (81170849, 81371008) and the Science and Technology Planning Project of Guangdong Province, China (No. 2012B031800353). Shida Chen and Minwen Zhou contributed equally to the research and should be considered as equivalent authors. Dr. Xiulan Zhang and Dr. Xiaoyan Ding should be considered equivalent corresponding authors.
Levels of angiogenesis-related vascular endothelial growth factor family in neovascular glaucoma eyes Shida Chen,1 Minwen Zhou,1,2,3 Wei Wang,1 Huimin Wu,1 Xiling Yu,1 Wenbin Huang,1 Xinbo Gao,1 Jiawei Wang,1 Xingyi Li,1 Shaolin Du,1 Xiaoyan Ding1 and Xiulan Zhang1 1
Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, China Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, China 3 Shanghai Key Laboratory of Fundus Disease, Shanghai, China 2
ABSTRACT. Purpose: This study aimed to evaluate the angiogenesis-related factors of the vascular endothelial growth factor (VEGF) family in the aqueous humour of patients with neovascular glaucoma (NVG). Methods: This study involved 22 eyes of 22 patients with advanced NVG requiring antiglaucomatous surgery and 20 control subjects with cataracts. The NVG eyes received an intravitreal injection of ranibizumab (IVR) treatment before antiglaucomatous surgery. Aqueous humour and blood were collected at the time of IVR and cataract surgery. Protein concentration of VEGF-A, VEGF-B and placenta growth factor (PlGF) in aqueous humour and plasma was determined by ELISA tests. Results: The mean concentration (standard deviation) of VEGF-A and PlGF in the aqueous humour of patients with NVG were 3037 (2387) pg/ml and 1078 (712) pg/ ml, respectively; both were significantly higher than the control group (both p < 0.001). However, levels of VEGF-A and PlGF in the serum of NVG and control subjects remained low. High concentrations of VEGF-A were closely correlated with high levels of PlGF in patients with NVG (r = 0.593, p = 0.004). Concentrations of VEGF-B in aqueous humour and serum remained unchanged (p > 0.05). Conclusion: There were high concentrations of angiogenesis factors of the VEGF family, with the exception of VEGF-B, in the aqueous humour of patients with NVG, and there was a positive correlation between VEGF-A and PlGF. High PlGF levels in patients with NVG may provide another potential target for treatment of NVG. Key words: neovascular glaucoma – PlGF – VEGF-A – VEGF-B
Acta Ophthalmol. 2015: 93: e556–e560 ª 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd
doi: 10.1111/aos.12624
Introduction Neovascular glaucoma (NVG) is a disease characterized as intractable, difficult to manage and often resulting in disastrous vision loss. The most common diseases responsible for development of NVG are ischaemic central retinal vein
e556
occlusion (CRVO), diabetic retinopathy and ocular ischaemic syndrome (Hayreh 2007). It is believed that a high concentration of vascular endothelial growth factor A (VEGF-A) in the aqueous humour is the one of the major cause of NVG (Tripathi et al. 1998; Horsley &
Kahook 2010). Anti-VEGF agents, which is a recombinant, humanized, monoclonal antibody Fab that neutralizes all active forms of VEGF-A, have been shown to be beneficial in treating NVG (Grisanti et al. 2006; Horsley & Kahook 2010). However, the precise pathophysiologic mechanisms of NVG are speculative, and anti-VEGF treatment alone does not completely inhibit NVG (Wakabayashi et al. 2008). Furthermore, current anti-VEGF therapy focuses on a single pathogenic mechanism, but other growth factors or cytokines may influence disease progression and recurrence (Hayreh 2007). The VEGF family, which comprises VEGFA, VEGF-B, VEGF-C, placenta growth factor (PlGF) and VEGF-D, plays an essential role in the angiogenesis process. Among the factors, VEGF-C and VEGF-D are mainly involved in lymphangiogenesis, and VEGF-A and PlGF are prominently involved in angiogenesis (Witmer et al. 2003; Takahashi 2011). The role of VEGF-B in the angiogenesis is controversial (Li et al. 2012). The role of other angiogenic factors of the VEGF family in the development of NVG remains unknown, and this study aimed to study the angiogenesis-related factors of the VEGF family in the aqueous humour of eyes with NVG.
Patients and Methods Subjects and enrolment criteria
This prospective, comparative study was approved by the Ethical Review
Acta Ophthalmologica 2015
Table 1. Characteristics of the subjects. Characteristic
NVG
Control
p-value
No. of eyes Age, y (SD) Sex, Male/Female IOP, mmHg (SD) DM HR
22 55.5 (19.6) 16/6 46.0 (7.2) 7 3
20 60.9 (5.9) 8/12 13.6 (2.5) 0 0
N/A 0.05). In addition, there were no significant correlations between aqueous humour levels and plasma levels of VEGF family factors in either group (all p > 0.05).
Discussion Our study showed that concentrations of VEGF-A and PlGF in aqueous humour were significantly greater in
patients with NVG; however, the level of VEGF-B remained unchanged compared to the control group. The study also found that an increased level of VEGF-A was closely correlated with an increased level of PlGF in the aqueous humour of patients with NVG. The finding of increased levels of VEGF-A in aqueous humour of patients with NVG was consistent with our previous study (Zhou et al. 2013). VEGF-A has been explored fully as a crucial angiogenic factor and potent vascular-permeable factor with great selectivity for endothelial cells (Otani et al. 2002), and anti-VEGF treatment has been efficient in patients with NVG. It was found that IVR could decrease iris fluorescein angiography leakage as early as 1 day after injection and could last for a month (Grisanti et al. 2006). In addition, our previous study found that bevacizumab significantly decreased the level of VEGF in the aqueous humour of patients with NVG, which, in turn, significantly decreased the neovascularization of the iris (Zhou et al. 2013). However, we found that neovascularization of the iris does not disappear completely, even after anti-VEGF therapy in a clinical setting. We hypothesize that other angiogenesis factors may contribute to neovascularization of the iris. PlGF is expressed in the placenta predominantly, and it has been found that PlGF not only can induce angiogenesis by itself but also by enhancing VEGF-A activity by heterodimeriza-
tion (DiSalvo et al. 1995). PlGF can bind to VEGFR-1 to promote recruitment of bone marrow-derived cells and stimulate retinal neovascularization (Carmeliet et al. 2001). In addition, PlGF could also increase vessel permeability and inflammation (Odorisio et al. 2002; Oura et al. 2003). PlGF/ VEGF heterodimers have been found in the synovial fluid of patients with inflammatory arthropathies, and PlGF upregulates production of VEGF in peripheral blood mononuclear cells (Bottomley et al. 2000). Yoshinori et al. found that levels of PlGF and VEGF in the vitreous fluid of patients with diabetic retinopathy were increased significantly compared to the control group, and both closely correlated with each other (Mitamura et al. 2002). In our study, both VEGF-A and PlGF were increased in the aqueous humour of patients with NVG, and they closely correlated with each other. This is consistent with another study, which found that concentrations of PlGF correlated closely with concentrations of VEGF in the aqueous humours of patients with diffuse diabetic macular oedema (Jonas et al. 2012). All the results, including those of our study, suggesting that PlGF may have a synergistic effect with VEGF-A in the development of NVG, which may enhance the angiogenesis effect of VEGF-A in the pathogenesis of NVG. Furthermore, current anti-VEGF methods is insufficient to inhibit NVG, regardless of the effect of PlGF. Combination therapy, such as adjunctive PlGF with VEGF blockade, is likely to be beneficial in treating NVG. Although VEGF-B binds to the same receptor including VEGFR-1 and NRP-1 as PlGF, it is a multifaceted factor that could act as an angiogenesis factor and that also has antiangiogenesis properties under different conditions (Li et al. 2012). In mice, adeno-associated viral delivery of VEGF-B to the skeletal or heart muscle induced very little angiogenesis, vascular permeability or inflammation (Bry et al. 2010). However, overexpression of VEGF-B in the mouse retina promoted pathological retinal and choroidal neovascularization and breakdown of the blood-retinal barrier (Zhong et al. 2011). More recently, Singh et al. found that hypoxia-induced VEGF-B expression in mouse retina and deletion of VEGF-B attenuated hypoxia-
e559
Acta Ophthalmologica 2015
induced retinal neovascularization (Singh et al. 2013). These controversial findings may suggest VEGF-B is more tissue specific and had different role in different tissues under vary conditions. In our study, the level of VEGF-B did not change in the NVG group compared to the control group, which may suggest VEGF-B may not involve in the pathogenesis of NVG; however, the exact role of VEGF-B in NVG needs more research. This study also explored factors that will potentially influence the level of angiogenesis VEGF factors. First, we measured plasma levels of the three VEGF family factors in both study groups. Results showed that their concentrations remained low, and there was no significant difference between the two groups. In addition, correlation analysis revealed no correlation between aqueous levels and plasma levels of VEGF factors in either group. These findings indicate that increased aqueous levels of VEGF-A and PlGF are not due to systemic disease. Instead, levels likely are the result of increased local production in the retina, followed by leakage into the anterior chamber. Various underlying diseases contribute to development of NVG, including CRVO, diabetic retinopathy and ocular ischaemic syndrome (Hayreh 2007). Although in our study, the underlying diseases mechanisms were not found to contribute significantly to increased levels of VEGF family factors, this may because of the small sample for each different underlying disease. It is not surprising that this study did not find any relationship between levels of VEGF family factors and IOP, because IOP mainly is determined by the extent of anterior synechiae and angle closure by the fibrovascular membrane. Furthermore, another reason is that all the patients with NVG have already being treated for increased IOP, so it will have some effect when exploring the relation between the IOP and the levels of factors. This study has several limitations. First, only 22 eyes included in our study, which is considered a small sample size, especially when considering the influence of underlying diseases. Second, antiglaucomatous drugs used in NVG might have affected VEGF family factors concentrations in the aqueous humour. Finally, we tested the level of
e560
VEGF family factors only before treatment with ranibizumab. In future, we should test for these factors before and after IVR treatment and follow-up to see the therapeutic effect.
References Bottomley MJ, Webb NJ, Watson CJ, Holt L, Bukhari M, Denton J, Freemont AJ & Brenchley PE (2000): Placenta growth factor (PlGF) induces vascular endothelial growth factor (VEGF) secretion from mononuclear cells and is co-expressed with VEGF in synovial fluid. Clin Exp Immunol 119: 182–188. Bry M, Kivela R, Holopainen T et al. (2010): Vascular endothelial growth factor-B acts as a coronary growth factor in transgenic rats without inducing angiogenesis, vascular leak, or inflammation. Circulation 122: 1725–1733. Carmeliet P, Moons L, Luttun A et al. (2001): Synergism between vascular endothelial growth factor and placental growth factor contributes to angiogenesis and plasma extravasation in pathological conditions. Nat Med 7: 575–583. DiSalvo J, Bayne ML, Conn G et al. (1995): Purification and characterization of a naturally occurring vascular endothelial growth factor. Placenta growth factor heterodimer. J Biol Chem 270: 7717–7723. Grisanti S, Biester S, Peters S, Tatar O, Ziemssen F & Bartz-Schmidt KU (2006): Intracameral bevacizumab for iris rubeosis. Am J Ophthalmol 142: 158–160. Hayreh SS (2007): Neovascular glaucoma. Prog Retin Eye Res 26: 470–485. Horsley MB & Kahook MY (2010): Anti-VEGF therapy for glaucoma. Curr Opin Ophthalmol 21: 112–117. Jonas JB, Jonas RA, Neumaier M & Findeisen P (2012): Cytokine concentration in aqueous humor of eyes with diabetic macular edema. Retina 32: 2150–2157. Li X, Kumar A, Zhang F, Lee C & Tang Z (2012): Complicated life, complicated VEGF-B. Trends Mol Med 18: 119–127. Mitamura Y, Tashimo A, Nakamura Y, Tagawa H, Ohtsuka K, Mizue Y & Nishihira J (2002): Vitreous levels of placenta growth factor and vascular endothelial growth factor in patients with proliferative diabetic retinopathy. Diabetes Care 25: 2352. Odorisio T, Schietroma C, Zaccaria ML, Cianfarani F, Tiveron C, Tatangelo L, Failla CM & Zambruno G (2002): Mice overexpressing placenta growth factor exhibit increased vascularization and vessel permeability. J Cell Sci 115: 2559–2567. Otani A, Takagi H, Oh H, Koyama S, Ogura Y, Matumura M & Honda Y (2002): Vascular endothelial growth factor family and receptor expression in human choroidal neovascular membranes. Microvasc Res 64: 162–169. Oura H, Bertoncini J, Velasco P, Brown LF, Carmeliet P & Detmar M (2003): A critical role of placental growth factor in the induction of inflammation and edema formation. Blood 101: 560–567. Singh NK, Hansen DE 3rd, Kundumani-Sridharan V & Rao GN (2013): Both Kdr and Flt1 play a vital role in hypoxia-induced Src-PLD1-
PKCgamma-cPLA(2) activation and retinal neovascularization. Blood 121: 1911–1923. Takahashi S (2011): Vascular endothelial growth factor (VEGF), VEGF receptors and their inhibitors for antiangiogenic tumor therapy. Biol Pharm Bull 34: 1785–1788. Tripathi RC, Li J, Tripathi BJ, Chalam KV & Adamis AP (1998): Increased level of vascular endothelial growth factor in aqueous humor of patients with neovascular glaucoma. Ophthalmology 105: 232–237. Wakabayashi T, Oshima Y, Sakaguchi H et al. (2008): Intravitreal bevacizumab to treat iris neovascularization and neovascular glaucoma secondary to ischemic retinal diseases in 41 consecutive cases. Ophthalmology 115: 1571– 1580, 1580. e1-3. Witmer AN, Vrensen GF, Van Noorden CJ & Schlingemann RO (2003): Vascular endothelial growth factors and angiogenesis in eye disease. Prog Retin Eye Res 22: 1–29. Zhong X, Huang H, Shen J, Zacchigna S, Zentilin L, Giacca M & Vinores SA (2011): Vascular endothelial growth factor-B gene transfer exacerbates retinal and choroidal neovascularization and vasopermeability without promoting inflammation. Mol Vis 17: 492–507. Zhou M, Chen S, Wang W, Huang W, Cheng B, Ding X & Zhang X (2013): Levels of erythropoietin and vascular endothelial growth factor in surgery-required advanced neovascular glaucoma eyes before and after intravitreal injection of bevacizumab. Invest Ophthalmol Vis Sci 54: 3874–3879.
Received on May 27th, 2014. Accepted on October 31st, 2014. Correspondence: Xiulan Zhang, MD, PhD Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology Sun Yat-sen University 54S. Xianlie Road Guangzhou, China 510060 Tel: +86 20 87330484 Fax: +86 20 87333271 Email: [email protected] and Xiaoyan Ding, MD, PhD Department of Vitreo-retinopathy, Zhongshan Ophthalmic Center State Key Laboratory of Ophthalmology Sun Yat-sen University 54S. Xianlie Road Guangzhou, China 510060 Tel: +86-20-87330373 Fax: +86-20-87333271 Email: [email protected] This research was supported by the National Natural Science Foundation of China (81170849, 81371008) and the Science and Technology Planning Project of Guangdong Province, China (No. 2012B031800353). Shida Chen and Minwen Zhou contributed equally to the research and should be considered as equivalent authors. Dr. Xiulan Zhang and Dr. Xiaoyan Ding should be considered equivalent corresponding authors.
