University of Groningen
Identification of biomarkers for diabetic retinopathy
Fickweiler, Ward
DOI:
10.33612/diss.95666609
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2019
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Fickweiler, W. (2019). Identification of biomarkers for diabetic retinopathy. University of Groningen.
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C h ap te r C h ap te r 5 C h ap te r 5 C h ap te r 5 C h ap te r 5
chapter 5
summary, discussion and future
perspectives
C h ap te r 5 summary
Diabetic retinopathy (DR) is a leading cause of vision loss in diabetic patients, in particu-lar through diabetic macuparticu-lar edema (DME)1. DME may develop when the leakage of fluid
may exceed clearance in the retina. The pathogenesis of DME is unclear. It is thought that breakdown of the inner endothelial blood-retinal barrier (BRB) and retinal vascular hyper-permeability may lead to retinal thickening2,3, but less is known about the contribution of
cytotoxic processes, neuronal damage and alterations in the vitreous gel in the etiology of DME. Retinal hyperpermeability often demonstrates a low correlation with the extent of retinal thickening4. Aiello, King and colleagues have discovered VEGF as a major mediator
in DME by altering endothelial tight junctions and transcellular flow5. Although anti-VEGF
therapies are effective for DME, about 50% of DME patients do not fully respond or are refractive to anti-VEGF therapy6,7. Therefore, improving the therapeutic efficacy and the
development of new treatments for DME are needed. In addition, advancing knowledge in predicting treatment response in patients with DME that could help to individualize therapies and choose alternative treatments for patients with DME is required. Therefore, in this thesis, we focus on potential novel biomarkers for DR that could contribute to the definition of targets for new therapies and provide more effective management strategies for DR.
Chapter 1 reviews the role of the kallikrein kinin system (KKS) in diabetes and the mecha-nisms that contribute to KKS activation. The KKS has been implicated as a VEGF indepen-dent pathway of DME. Pharmacological inhibition of components of the KKS, which may be a potential new treatment option for DME, are also discussed. The effects of the KKS are primarily mediated by bradykinin (BK). Chapter 1b characterizes the effects of BK on the retinal structure and proteome of the rat retina. Intravitreal injection of BK and/or VEGF was associated with a similar increase in retinal thickening. Proteomic analysis identified pro-inflammatory molecules and plasma proteins that were elevated in BK-injected eyes, including 8 proteins that were previously reported to be increased in the human vitreous DME proteome. This study provided insight into the proteomic changes in the retina that are associated with retinal edema. The findings in chapter 1c suggested a pattern of a decreased prevalence of cardiovascular disease among people with type 1 diabetes with chronic kidney disease and without proliferative DR, suggesting that common protective factors for prolifera-tive DR and cardiovascular disease may exist.
In Chapter 2a we aimed to explore the predictive value of specific OCT patterns and retinal features on visual outcomes and retinal thickness in patients with DME receiving anti-VEGF treatment. We analyzed the prognostic value and accuracy of specific OCT patterns and retinal features in predicting the response of 117 patients with DME to anti-VEGF therapy. Patients with DME with serous pattern at baseline were associated with a potential good response to anti-VEGF therapy. In contrast, DME patients with disorganization of retinal
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inner layers (DRIL) were correlated with poorer visual outcome of anti-VEGF therapy. The prognostic value of external limiting membrane (ELM) and inner/outer segment (IS/OS) line integrities was not established. In chapter 2b, we assessed retinal layer thickness on OCT on 1413 eyes of 776 patients across a wide range of age, duration of diabetes, and DR sever-ity. Male gender was strongly associated with increased retinal thickness, with a consistent effect across multiple retinal layers. Longer duration of diabetes was related to thinning of neuroretinal structures. When we compared eyes with no-mild DR to eyes with proliferative DR, the presence of proliferative DR had opposite effects of increased inner versus decreased outer retinal layers. In models adjusting for gender and scatter laser as possible confound-ers, proliferative DR remained related to increases in inner versus decreases in outer retinal layers. This study provided further insight into the neuroretinal abnormalities in advanced diabetic eye disease.
In Chapter 3a, we studied the prognostic value of selected candidate circulating retina-specific mRNAs, including messenger RNA (mRNA) of retinoschisin, RPE65, rhodopsin, and endo-thelial progenitor cell (EPC) markers CD34 and CD133 for patients with DME that receive anti-VEGF therapy. Blood samples were collected from 89 patients with DME according to the study protocol of the multicenter, prospective Bevacizumab and Ranibizumab in Diabetic Macular Edema (BRDME) study. Plasma mRNA levels of retinoschisin were negatively corre-lated with visual acuity and plasma mRNA levels of rhodopsin were positively correcorre-lated with visual acuity in patients with DME. Change in retinal thickness between baseline and months 1, 2, and 3 during anti VEGF treatment was associated with mRNA levels of retinoschisin and rhodopsin. However, we found no significant association between mRNA levels of retinoschi-sin and rhodopretinoschi-sin and outcomes between baseline and month 6. We did not find detectable amounts of plasma EPC CD133 and RPE 65 mRNA in the circulation of DME patients. The studies in chapter 3b discovered that elevated photoreceptor-secreted Retinol Binding Protein 3 (RBP3) in the retina and vitreous of individuals with extreme duration of type 1 diabetes is associated with long-term protection from advanced DR, independent of glycemic control. This represents the first neuroretinal protein identified with potential protective activ-ity against the toxic effects of hyperglycemia on the retinal vasculature, a major cause of DR onset and worsening. Intravitreal injection of RBP3 and its specific overexpression in rodents inhibited actions of VEGF and normalized diabetes-induced capillary permeability, abnormal neural retinal function, retinal thinning and acellular capillaries. These findings identify the first neuroretinal protein to act on retinal vasculature, suggesting numerous therapeutic and diagnostic possibilities.
C h ap te r 5
dIscussIon and future perspectIves
Optimizing current imaging in DR
In this thesis, we evaluated specific retinal patterns and features in predicting the response of patients with DME that received anti-VEGF therapy using OCT imaging. OCT imaging is widely used in the diagnosis of DME. We have shown that several OCT patterns are associ-ated with different treatment responses of DME patients to anti-VEGF therapy. We found that the presence of subretinal fluid and disorganization of retinal inner layers are predictive OCT parameters of treatment response of DME patients to anti-VEGF therapy. In contrast, we found no statistically significant associations between treatment response external limit-ing membrane (ELM) and inner/outer segments (IS/OS) integrities. The identification of the integrities of these structures may be influenced by the resolution of the OCT systems. Therefore, identifying these retinal features using next-generation OCT systems for prognos-tic purposes may be more accurate.
Other imaging modalities in the management of DR include fundus photography and fluorescein angiography (FA). FA has been useful for decades in ophthalmologic practice for evaluating, diagnosing and treating retinal diseases. FA has also been used to classify eyes with DME by proportion of fluorescein leakage as focal or diffuse14,15. However, the use of
these classifications in predicting treatment response is limited since the terms are often used without clear definitions and the reproducibility of grading FA has been only moderate16. In
addition, there are important side-effects and complications of fluorescein injection, includ-ing nausea, vomitinclud-ing and vasovagal reaction. There seems to be a trend toward decreasinclud-ing use of FA in the management of DME17,18. In contrast to FA, OCT is a noninvasive imaging
modality without significant side effects or complications. Next-generation OCT devices will be developed with higher resolution and sensitivity. While OCT is superior in imaging retinal structures, FA provides essential information about retinal vasculature status and leakage. Optical coherence tomography angiography (OCTA) is a new imaging modality, which has the potential to show retinal structures and retinal vascular plexus. This promising imaging technique visualizes retinal structures at the retinal capillary layer level19. Future studies using
OCTA will need to be conducted to better understand pathogenic mechanisms of DME and to identify specific OCTA patterns and retinal features that may help in predicting treatment response in DME.
New biomarkers for DR
Besides characteristics on imaging techniques regularly used in the management of DME, such as OCT, other predictors of treatment response may be found in the peripheral blood of patients with DME. As discussed previously, about half of patients with DME do not fully re-spond to anti-VEGF therapy7,20. Identifying a biomarker for DME could lead to a better
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the optimization of the best treatment strategy for patients with DME. Therefore, we explored the most strongly associated DR biomarkers in DME with a focus on predicting treatment response. We have demonstrated that circulating retinoschisin and rhodopsin mRNA levels may have value as biomarkers in patients with DME. Retinoschisin is primarily expressed in rod and cone photoreceptors and bipolar cells, and maintains the integrity of the inner nuclear layer and outer plexiform layer21. Loss of retinoschisin function may lead to splitting of the
retina and cystic cavitities radiating from the central retina22. Rhodopsin is found in rod
photo-receptor cells and is involved in visual phototransduction23. Prognostic studies are needed to
further elucidate the value of these biomarkers in predicting treatment response in DME. In addition, it is unknown whether circulating levels of retinoschisin and rhodopsin mRNAs are general markers of visual acuity or specific for patients with DME. Further research is required to explore the association between the plasma mRNA levels, corresponding protein levels and pathogenic mechanisms in DME. The Kallikrein Kinin System (KKS) has been discovered by Feener and colleagues as a potential VEGF-independent mechanism of DME24-29. Therefore,
the KKS may be an interesting candidate pathway for the identification of non-responders of anti-VEGF therapy in DME. Previous reports also have suggested that several components of the KKS may be potential biomarkers in DME27,28,30. Further studies are needed to study
the potential of the KKS as a potential biomarker for DR and DME. Advancing knowledge in genetics is another field to find new biomarkers for DR. In addition to genetic variation, epigenetics may mediate the relationship between genotype and environmental factors. The most important mechanisms of epigenetic changes are DNA methylation, modifications of histone tails and micro-RNAs32-34. Exploring epigenetics in diabetes has just begun. DME
may develop and progress even after improved glycemic control35,36. Further studies need
to explore the role of epigenetic modifications in DR and DME. Epigenetic modifications are reversible, thereby enabling the development of new therapeutic targets for DR and DME37.
Need for new treatments for DME
The effects of the KKS pathway are primarily mediated by bradykinin (BK). We showed that intravitreal injection of BK and VEGF increase retinal thickness, vasodilation and tortuosity in a similar magnitude and time manner. To date, there is no representative animal model available for DME. For example, rats lack a macula. Thus, the mechanisms that contribute to BK-and VEGF-induced retinal thickening and translation to human studies will require additional studies. Another finding of our study regarding the efficacy of anti-VEGF therapies in DME was that the improvement in mean visual-acuity letter score of all patients with DME improved to a lower extent than reported in previous studies. Our study excluded patients that may confound the interpretation of these study results, such as hypertension or ocular treatment within 3 months of initiation of the study. The difference in improvement of anti-VEGF therapy between studies may be related to differences in population, study design, treatment protocol, and anti-VEGF therapy among other factors. However, these findings suggest the need for new treatments in patients with DME.
C h ap te r 5
1. Antonetti DA, Klein R, Gardner TW. Diabetic retinopathy. N Engl J Med. 2012;366(13):1227-1239. 2. Ehrlich R, Harris A, Ciulla TA, Kheradiya N, Winston DM, Wirostko B. Diabetic macular oedema:
Physical, physiological and molecular factors contribute to this pathological process. Acta
Oph-thalmol. 2010;88(3):279-291.
3. Antcliff RJ, Marshall J. The pathogenesis of edema in diabetic maculopathy. Semin Ophthalmol. 1999;14(4):223-232.
4. Danis RP, Scott IU, Qin H, et al. Association of fluorescein angiographic features with visual acu-ity and with optical coherence tomographic and stereoscopic color fundus photographic features of diabetic macular edema in a randomized clinical trial. Retina. 2010;30(10):1627-1637. 5. Aiello LP, Avery RL, Arrigg PG, et al. Vascular endothelial growth factor in ocular fluid of patients
with diabetic retinopathy and other retinal disorders. N Engl J Med. 1994;331(22):1480-1487. 6. Mitchell P, Bandello F, Schmidt-Erfurth U, et al. The RESTORE study: Ranibizumab monotherapy
or combined with laser versus laser monotherapy for diabetic macular edema. Ophthalmology. 2011;118(4):615-625.
7. Nguyen QD, Brown DM, Marcus DM, et al. Ranibizumab for diabetic macular edema: Results from 2 phase III randomized trials: RISE and RIDE. Ophthalmology. 2012;119(4):789-801. 8. Sophie R, Lu N, Campochiaro PA. Predictors of functional and anatomic outcomes in patients
with diabetic macular edema treated with ranibizumab. Ophthalmology. 2015;122(7):1395-1401. 9. Montero JA, Ruiz-Moreno JM, De La Vega C. Incomplete posterior hyaloid detachment after
intravitreal pegaptanib injection in diabetic macular edema. Eur J Ophthalmol. 2008;18(3):469-472.
10. Wilkins JR, Puliafito CA, Hee MR, et al. Characterization of epiretinal membranes using optical coherence tomography. Ophthalmology. 1996;103(12):2142-2151.
11. Kim NR, Kim YJ, Chin HS, Moon YS. Optical coherence tomographic patterns in diabetic macu-lar oedema: Prediction of visual outcome after focal laser photocoagulation. Br J Ophthalmol. 2009;93(7):901-905.
12. Gandorfer A, Messmer EM, Ulbig MW, Kampik A. Resolution of diabetic macular edema after surgical removal of the posterior hyaloid and the inner limiting membrane. Retina. 2000;20(2):126-133.
13. Harbour JW, Smiddy WE, Flynn HW,Jr, Rubsamen PE. Vitrectomy for diabetic macular edema associated with a thickened and taut posterior hyaloid membrane. Am J Ophthalmol. 1996;121(4):405-413.
14. Kang SW, Park CY, Ham DI. The correlation between fluorescein angiographic and optical coher-ence tomographic features in clinically significant diabetic macular edema. Am J Ophthalmol. 2004;137(2):313-322.
15. Ozdek SC, Erdinc MA, Gurelik G, Aydin B, Bahceci U, Hasanreisoglu B. Optical coherence tomo-graphic assessment of diabetic macular edema: Comparison with fluorescein angiotomo-graphic and clinical findings. Ophthalmologica. 2005;219(2):86-92.
16. Browning DJ, Altaweel MM, Bressler NM, Bressler SB, Scott IU, Diabetic Retinopathy Clinical Research Network. Diabetic macular edema: What is focal and what is diffuse? Am J Ophthalmol. 2008;146(5):649-55, 655.e1-6.
17. Bailey CC, Sparrow JM, Grey RH, Cheng H. The national diabetic retinopathy laser treatment audit. I. maculopathy. Eye (Lond). 1998;12 ( Pt 1)(Pt 1):69-76.
18. Diabetic Retinopathy Clinical Research Network, Scott IU, Edwards AR, et al. A phase II ran-domized clinical trial of intravitreal bevacizumab for diabetic macular edema. Ophthalmology. 2007;114(10):1860-1867.
Chapter 5
192
19. Chalam KV, Sambhav K. Optical coherence tomography angiography in retinal diseases. J
Oph-thalmic Vis Res. 2016;11(1):84-92.
20. Diabetic Retinopathy Clinical Research Network, Wells JA, Glassman AR, et al. Aflibercept, bevacizumab, or ranibizumab for diabetic macular edema. N Engl J Med. 2015;372(13):1193-1203. 21. Weber BH, Schrewe H, Molday LL, et al. Inactivation of the murine X-linked juvenile retinoschisis
gene, Rs1h, suggests a role of retinoschisin in retinal cell layer organization and synaptic struc-ture. Proc Natl Acad Sci U S A. 2002;99(9):6222-6227.
22. Molday RS, Kellner U, Weber BH. X-linked juvenile retinoschisis: Clinical diagnosis, genetic analysis, and molecular mechanisms. Prog Retin Eye Res. 2012;31(3):195-212.
23. Park PS. Constitutively active rhodopsin and retinal disease. Adv Pharmacol. 2014;70:1-36. 24. Kita T, Clermont AC, Murugesan N, et al. Plasma kallikrein-kinin system as a VEGF-independent
mediator of diabetic macular edema. Diabetes. 2015;64(10):3588-3599.
25. Gao BB, Chen X, Timothy N, Aiello LP, Feener EP. Characterization of the vitreous proteome in diabetes without diabetic retinopathy and diabetes with proliferative diabetic retinopathy. J
Proteome Res. 2008;7(6):2516-2525.
26. Gao B, Clermont A, Rook S, et al. Extracellular carbonic anhydrase mediates hemorrhagic retinal and cerebral vascular permeability through prekallikrein activation. Nat Med. 2007;13(2):181-188. 27. Liu J, Clermont AC, Gao B, Feener EP. Intraocular hemorrhage causes retinal vascular
dysfunc-tion via plasma kallikrein. Invest Ophthalmol Vis Sci. 2013;54(2):1086-1094.
28. Clermont A, Chilcote TJ, Kita T, et al. Plasma kallikrein mediates retinal vascular dysfunction and induces retinal thickening in diabetic rats. Diabetes. 2011;60(5):1590-1598.
29. Feener EP, Zhou Q, Fickweiler W. Role of plasma kallikrein in diabetes and metabolism. Thromb
Haemost. 2013;110(9):434-441.
30. Walia S, Clermont AC, Gao BB, Aiello LP, Feener EP. Vitreous proteomics and diabetic retinopathy.
Semin Ophthalmol. 2010;25(5-6):289-294.
32. Cooper ME, El-Osta A. Epigenetics: Mechanisms and implications for diabetic complications. Circ
Res. 2010;107(12):1403-1413.
33. Villeneuve LM, Natarajan R. The role of epigenetics in the pathology of diabetic complications.
Am J Physiol Renal Physiol. 2010;299(1):F14-25.
34. El-Osta A, Brasacchio D, Yao D, et al. Transient high glucose causes persistent epigenetic changes and altered gene expression during subsequent normoglycemia. J Exp Med. 2008;205(10):2409-2417.
35. Progression of retinopathy with intensive versus conventional treatment in the diabetes control and complications trial. diabetes control and complications trial research group. Ophthalmology. 1995;102(4):647-661.
36. Holman RR, Paul SK, Bethel MA, Matthews DR, Neil HA. 10-year follow-up of intensive glucose control in type 2 diabetes. N Engl J Med. 2008;359(15):1577-1589.
37. Advani A, Huang Q, Thai K, et al. Long-term administration of the histone deacetylase inhibitor vorinostat attenuates renal injury in experimental diabetes through an endothelial nitric oxide synthase-dependent mechanism. Am J Pathol. 2011;178(5):2205-2214.
43. Jarajapu YP, Cai J, Yan Y, et al. Protection of blood retinal barrier and systemic vasculature by insulin-like growth factor binding protein-3. PLoS One. 2012;7(7):e39398.
C h ap te r 5 acknoWledgements/dankWoord
Dit proefschrift was er niet geweest zonder de steun en inpanningen van mijn promotores en begeleiders, prof. dr. J.M.M. Hooymans, prof. dr. B.H.R. Wolffenbuttel en dr. L.I. Los.
Bij aanvang van mijn opleiding waren slechts de globale contouren van dit onderzoek zicht-baar. Mijn eerste promotor, Anneke Hooymans, heeft het mogelijk gemaakt dat ik tijd kreeg om aan dit onderzoek te werken gedurende mijn opleiding tot oogarts en vertrouwde erop dat het in een proefschrift zou resulteren. Daarnaast heeft zij het mogelijk gemaakt om mijn opleiding een jaar te onderbreken om onderzoek te doen in Amerika. Anneke, heel veel dank hiervoor.
Mijn tweede promotor, Bruce Wolffenbuttel, heeft mij door zijn positieve instelling en advie-zen vaak gesteund in dit onderzoek. Naast zijn vele werkzaamheden als arts, onderzoeker en hoofd van de Endocrinologie in het UMCG heeft hij ook de tijd gevonden om mij te bege-leiden. Bruce, heel veel dank en ik hoop dat we in de toekomst nog eens samen de Boston Bruins bezoeken.
Gedurende het gehele traject van dit proefschrift heeft Leonie Los mij op een geduldige wijze begeleid. Vanaf het begin is zij samen met mij opgetrokken om dit onderzoek mogelijk te ma-ken en in de loop van het traject was zij de stuwende kracht om dit proefschrift af te ronden. Leonie, bedankt voor de begeleiding en het vertrouwen. Zonder jou was dit proefschrift er niet geweest.
Ook alle collega’s van de afdeling Oogheelkunde in het UMCG wil ik graag bedanken voor de steun gedurende mijn assistenten-en promotietijd. Prof. dr. Nomdo Jansonius en dr. Jan Wil-lem Pott wil ik graag bedanken voor het creëren van tijd en mogelijkheden om gedurende het laatste deel van mijn opleiding mijn promotie-onderzoek af te ronden. De retina-groep (drs. Victor Renardel de Lavalette, drs. Gina Postma en drs. Angela Huiskamp) wil ik bedanken voor de medewerking in het verzamelen van glasvochtsamples en epiretinale membranen van patienten. Ook wil ik alle collega arts-assistenten bedanken voor het overnemen van klinische werkzaamheden gedurende mijn onderzoekswerk, zowel tijdens mijn verblijf in Amerika als tijdens mijn opleiding in Nederland. Daarnaast wil ik graag het stafsecretariaat Oogheelkunde (Ella Oosterveld, Stella de Rooy en Fenna Fonck-Pott) bedanken voor de ondersteuning, hulp bij aanstellingen en het opgraven van moeilijk te verkrijgen literatuur. Luuk Mooibroek ben ik dankbaar voor zijn hulp bij het opzetten van digitale onderzoekdatabases en ondersteuning bij video-conferenties. Wim Berghuis en Wim Nieuwold wil ik bedanken voor het financieel beheer van de fondsen tijdens mijn promotieonderzoek. Marijke Meinen ben ik dankbaar voor haar hulp in het verkrijgen van data en materiaal van alle Groningse BRDME patienten.
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Corine van der Worp wil ik graag bedanken voor haar hulp in weekenden en avonden voor het verwerken van patientenmateriaal in het laboratorium.
Inge Pop van het Parelsnoer Initiatief wil ik graag bedanken voor haar assistentie bij het opzetten van de Parelsnoer database voor DME patienten in Groningen.
Dr. Ilja Nolte wil ik bedanken voor de statistische hulp bij de OCT en marker studies. Verder wil ik alle medewerkers van de BRDME studiegroep bedanken voor hun bijdrage en samenwerking voor de OCT en marker studies.
Prof. dr. R.O. Schlingemann, beste Reinier, bedankt voor de plezierige samenwerking en voor de mogelijkheid om deel uit te maken van de BRDME studie.
Dr. Frank Verbraak wil ik graag bedanken voor zijn hulp bij het OCT artikel en het clas-sificeren en analyseren van de OCT afbeeldingen.
Dr. Ingeborg Klaassen en haar team wil ik bedanken voor de metingen en analyse van de markers in de bloedsamples van de BRDME patiënten.
Daarnaast ben ik de Stichting Blindenhulp, de Landelijke Stichting voor Slechtzienden en Blinden en onderzoekschool GUIDE dankbaar voor de financiële mogelijkheden om dit onderzoek uit te voeren.
Graag wil ik de leden van de beoordelingscommissie, prof.dr. Annette Moll, prof. dr. Ingrid Molema en Prof.dr. Eric J.G. Sijbrands, bedanken voor het beoordelen van mijn proefschrift. I would like to thank the team at Joslin for their help and mentorship: Dr. Feener, Dr. Sun, Dr. Aiello, and Dr. King and also members of the Beetham Eye Institute, Section on Vascular Cell Biology, and the Joslin 50-Year Medalist Study. I’m looking forward to continue working with you.
Naast mijn werkkring wil ik graag nog een aantal familieleden en vrienden bedanken. Mijn ouders wil ik bedanken voor hun vertrouwen in mijn mogelijkheden. Freek, Thamara en Suze, dank voor alle steun. Ewout, Bregje, Erwin, Elise, Jelle, Arjen en Kasper, bedankt voor alle ont-spanning en gezelligheid, het langskomen in Boston, gezamenlijke weekenden en vakanties. Ook de familie en vrienden van Suzanne wil ik bedanken voor hun interesse in mijn onderzoek. En tot slot, Suzanne, bedankt voor het ontwerpen van illustraties voor de manuscripten en het verbeteren en samenstellen van het proefschrift. Ik kijk uit naar onze toekomst samen met Wout
C h ap te r 5 currIculum vItae
Ward Fickweiler was born in 1985 in Apeldoorn, the Netherlands. After completing his pre-university education in Schiermonnikoog and Leeuwarden (1997-2003), he moved to the University of Groningen in 2003 to study Medicine. He received his Bachelor’s degree in 2006 and graduated with a Doctor of Medicine (M.D.) in 2009, distinguished with a nomination for Best Scientific Thesis from the University of Groningen, where he subsequently specialized in Ophthalmology. During his clinical years, he developed specific interest in the area of diabetic eye disease and started working on research which resulted in this thesis under supervision of Dr. Anneke Hooymans, Dr. Bruce Wolffenbuttel, and Dr. Leonie Los. In 2013, he spent a year performing basic science research in the laboratory of Dr. Edward Feener at Joslin Diabetes Center, Harvard Medical School, Boston, USA. After finishing the ophthalmology residency training program in the Netherlands in 2016, he returned to Joslin Diabetes Center to further develop his research in diabetic eye disease in the laboratories of Dr. Jennifer Sun, Dr. Lloyd P Aiello and Dr. George King. He received the Mary K. Iacocca Junior Fellowship Award, which is designed to recognize Joslin fellows with an important project and with high potential for future impact in a career in diabetes. The author is married to Suzanne Bergenhenegouwen. Together they have one child (Wout, born in 2018).
