A prematuridade está associada com uma alta incidência de complicações no período neonatal sendo uma das mais importantes a retinopatia da prematuridade (ROP) e suas seqüelas: ambliopia, estrabismo, cegueira. Estudos indicam que alterações no fluxo sanguíneo retiniano estão envolvidas na patogênese da ROP causando um crescimento vascular anormal dos vasos da retina. A análise por ultrassonografia Doppler (USD) dos vasos da órbita permite uma estimativa do fluxo sanguíneo local. Objetivo: estabelecer valores de velocidade do fluxo sanguíneo e de seus índices na artéria oftálmica em recém-nascidos pré-termos de muito baixo peso (RNPTMBP) "saudáveis" do nascimento até a alta. Metodologia: Coorte de recémnascidos pré-termos de muito baixo peso, nascidos na UTI Neonatal do Hospital de Clínicas de Porto Alegre (HCPA) no período de agosto de 2006 a abril de 2008. Foram obtidas as medidas de velocidade sistólica (VS), velocidade diastólica (VD), índice de pulsatilidade (IP) e índice de resistência (IR) da artéria oftálmica por USD nas primeiras 24 horas de vida, com sete dias, com 28 dias e no momento da alta hospitalar. Incluímos RN com peso de nascimento abaixo de 1500 gramas e idade gestacional <= 32 semanas, sem ROP graus 2 e 3, e sem hemorragia peri-intraventricular (HPIV) graus 3 e 4. A análise estatística foi realizada utilizando teste t pareado e análise de variância (ANOVA). Resultados: Foram estudados 46 RNPTMBP (92 olhos examinados). No primeiro exame os valores em média do fluxo sanguíneo e índices da artéria oftálmica foram: VS 18,42 cm/s; VD 6,22 cm/s; IP 1,40; IR 0,70 e com 28 dias de vida: VS 22,38 cm/s; VD 6,97 cm/s; IP 1,51; IR 0,75 (p<0.001). Não houve diferença significativa entre as medidas obtidas no olho direito e no esquerdo, e entre primeiro e segundo exames. Da mesma forma, as medidas obtidas com 28 dias de vida foram similares aquelas no momento da alta hospitalar. Conclusão: Ocorre uma elevação nas velocidades de fluxo sanguíneo da artéria oftálmica do período pós-natal até a alta em recémnascidos pré-termo de muito baixo peso de nascimento "saudáveis". Os índices calculados não mostraram diferença estatisticamente significativa. O conhecimento deste padrão normal poderá auxiliar na prevenção e no screening para detecção de doença ocular. / Retinopathy of prematurity (ROP) is a multifactorial disease of very low birth weight infants (VLBWI), and the vascular component has an important role. Evaluation of retinal blood flow is essential to understand its physiopathology. Objective: To establish normal blood flow velocity and Doppler indices of the ophthalmic arteries from birth to discharge of "healthy" VLBWI.Methods: Cohort study of newborns with birth weight < 1500 grams and gestational age <= 32 weeks born at our Hospital from August 2006 to April 2008. Doppler ultrasound exam was done in both eyes in the first 24 hours after birth, at 7 and 28 days old, and at hospital discharge for systolic velocity (SV), diastolic velocity (DV), pulsatility index (PI) and resistance index (RI). We excluded those with ROP stage 2 and higher, periintraventricular hemorrhage grades 3 and 4, and death. Statistical analysis was performed using paired t test and repeated measures ANOVA. The study was approved by our Ethic Committee.Results: 46 VLBWI (92 eyes) were studied. First exam: SV 18.40 cm/s; DV 6.23 cm/s; PI 1.41; RI 0.70 and 28 days after birth: SV 22.30 cm/s; DV 6.77 cm/s; PI 1,50; RI 0.75 ( p<0.001). Both eyes had similar Doppler findings at all examined moments. SV and DV increased significantly from the first 24 hours to hospital discharge. There were no significant changes during the study period in PI and RI. Conclusions: There was a increase of SV and DV retinal blood flow from birth to hospital discharge in "healthy" VLBWI; other Doppler measurements were stable. Knowing this normal pattern will provide prevention and screening for ROP.

INTRODUÇÃO: Baixos níveis séricos de fator de crescimento insulin-like I (IGF- 1) ao nascimento têm sido considerados um fator de risco para o desenvolvimento da retinopatia da prematuridade em recém-nascidos prematuros de extremo baixo peso. Isto se deve ao seu papel como fator permissivo para o fator de crescimento endotelial vascular (VEGF) exercer sua função no desenvolvimento normal e patológico dos vasos da retina. OBJETIVO: Testar a hipótese de que a administração do JB-1 (um análogo do IGF-1 que inibe de forma potente a auto-fosforilação do receptor do IGF-1 pelo IGF-1) durante a hiperóxia previne a retinopatia induzida por oxigênio em nosso modelo experimental em ratos. MATERIAL E METODOS: Ratos recém-nascidos foram expostos a 50% de oxigênio com três episódios consecutivos de hipóxia (12% de oxigênio) do nascimento ao 14º dia de vida. Os ratos foram tratados com injeções subcutâneas de 1) JB-1 (1g/d) nos três primeiros dias de vida (JB-1 x3); 2) JB- 1(1g/d) por dias alternados do 1º ao 13º dias de vida (JB-1x7) 3) ou volume equivalente de solução salina. Grupos controles foram criados em ar ambiente nas mesmas condições, exceto pelo ciclo de hiperóxia/ hipóxia. Os grupos foram analisados após a exposição ao oxigênio no 14º dia de vida ou deixados em ar ambiente por mais sete dias até o sacrifício, no 21º dia de vida. Determinou-se as dosagens sistêmicas e oculares de fator de crescimento endotelial vascular (VEGF), receptor tipo1 solúvel do fator de crescimento endotelial vascular (sVEGFR-1) e fator de crescimento insulin-like I (IGF-1), associados a análise da vascularização retiniana e do perfil dos genes relacionados à angiogênese retiniana. RESULTADOS: O tratamento com JB-1x3 resultou em supressão efetiva da retinopatia induzida por oxigênio, sem efeitos adversos no crescimento somático e foi associado a um aumento do sVEGFR-1 quando comparado com o JB-1x7. Ao contrário, o tratamento com JB-1x7 durante a exposição ao oxigênio levou à diminuição do peso corpóreo e níveis mais altos de IGF-1 e VEGF relacionados à presença de tortuosidades vasculares e neovascularização retiniana, quando comparado com as retinas que receberam apenas solução salina. CONCLUSÃO: O tratamento curto e sistêmico com JB-1 durante a hiperóxia resultou em prevenção da retinopatia induzida por oxigênio sem restrição do crescimento somático. Novos estudos devem ser realizados para determinar se o JB-1 pode ser usado em recém-nascidos de extremo baixo peso na prevenção da retinopatia da prematuridade / INTRODUCTION: Low serum insulin growth factor (IGF-1) levels at birth is a risk factor for the development of retinopathy of prematurity in extremely low birth weight infants. This may be due to its role as a permissive factor for vascular endothelial growth factor (VEGF) function in normal and pathologic vascular development. OBJECTIVE: To test the hypothesis that JB-1 (an IGF-1 analog that potently inhibits the autophosphorylation of the IGF-1 receptor by IGF-1) administration during hyperoxia prevents oxygen induced retinopathy in our rat model. MATERIAL AND METHODS: Neonatal rats were exposed to 50% oxygen with brief, clustered, hypoxic (12% oxygen) episodes from birth to day 14. The pups were treated with subcutaneus injections of 1) JB-1 (1g/d) on the first, second, and third day (JB-1x3) 2) JB1 (1g/d) on alternate days from first to day 13 (JB- 1x7); or equivalent volume of saline. Control littermates were raised in room air with all conditions identical except for inspired oxygen. Groups were analyzed after hyperoxia/hypoxia cycling on day 14 or allowed to recover in room air until the 21st day. Systemic and ocular VEGF, soluble VEGFR-1, and IGF-1; retinal vasculature and gene profile of retinal angiogenesis were assessed. RESULTS: JB-1x3 treatment resulted in successful suppression of oxygeninduced retinopathy with no adverse effect on anthropometric growth, which was associated with increased sVEGFR-1 compared to JB-1x7. In contrast, intermittent and long exposure to JB-1 (JB-1x7) during the hyperoxia/hypoxia cycling period resulted in decreased body weight and higher ocular IGF-1 and VEGF levels as well as vascular tortuosity and retinal neovascularization compared with saline treated retinas. CONCLUSION: Systemic treatment with JB-1 during hyperoxia results in successful prevention of oxygen-induced retinopathy with little adverse effects on anthropometric growth. Further confirmatory studies are needed to determine whether systemic JB-1 should be used in extremely low birth weight infants to prevent retinopathy of prematurity

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2018-07-10T19:46:34Z No. of bitstreams: 2 Joziana_Pastro2018.pdf: 1649555 bytes, checksum: 769cd69a9e879a09907152dd2e64987c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-07-10T19:46:34Z (GMT). No. of bitstreams: 2 Joziana_Pastro2018.pdf: 1649555 bytes, checksum: 769cd69a9e879a09907152dd2e64987c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Retinopathy of prematurity (ROP) is a vasoproliferative disease, related to blindness, in Premature Newborns (PN) who, within other factors, used oxygen during hospitalization. Early visual follow-up of preterm newborns by ophthalmologists makes it possible to identify the stage and grade of the disease and the indication of treatment or attendance of its evolution. Nursing orientation is essential to the PN relatives, since ROP is not an easily seen disease, so, parents being aware that the ophthalmologic follow-up is of vital importance for the visual recovery of the baby will make a difference in the child future visual health. Therefore, this study aims to evaluate the prevalence and evolution of ROP in PN, hospitalized in a Neonatal Intensive Care Unit (NICU) and attended at a referral ophthalmologic follow-up service. This is a quantitative, descriptive and exploratory study, carried out in the city of Cascavel. Data collection was done in medical records of PN, born between January 2014 and June 2016, hospitalized in the NICU of the West Paraná University hospital, and followed by the outpatient clinic of Cascavel Eyes Hospital, totaling 181 charts. A quantitative analysis was performed through descriptive and inferential statistic. The prevalence of ROP was 11.31% (n = 50). Relating its characteristics to evolution, the diagnoses prevalent in the PN of the study were respiratory diseases (41.99%) and among comorbidities, sepsis prevailed (63.54%). 80 PN required blood transfusion (44,20%) and 152 (83.98%) used oxygen therapy, with a predominance of mask device (n = 141; 77,90%) and orotracheal tube - TOT (n = 100; 55.25%), on average for 15 days. The highest concentration recorded was hood (45.0%). The time of use and the O2 concentration of TOT, time of mask use and time and concentration of O2 of Continuous Positive Airway Pressure (CPAP), were significant to trigger ROP. Among ROP cases, ten (5.5%) children had severe ROP and required laser treatment. All the PN diagnosed with ROP used oxygen. ROP prevailed in moderate preterm newborns (44%), with ROP grade 3 being the most severe, affecting both extreme and moderate PN. Respiratory diseases, sepsis and procedures such as blood transfusion and oxygen therapy influenced the presence of ROP, with prevalence in moderate preterm newborns. The adoption of ophthalmologic screening for ROP detection, with background examinations of the eyes in the NICU contributed to the early treatment and prevention of severe visual impairment and blindness caused by ROP. Thus, nurses are fundamentally important, from the prevention, the diagnosis until the course of the treatment and for discharge counselling. / A Retinopatia da Prematuridade (ROP) é uma enfermidade vasoproliferativa, relacionada à cegueira, em recém-nascidos prematuros (RNPT) que, dentre outros fatores, utilizaram oxigênio durante a hospitalização. O acompanhamento visual precoce de prematuros por oftalmologistas possibilita a identificação do estágio e do grau da doença, assim como a indicação de tratamento ou de acompanhamento da sua evolução. A orientação da enfermagem é primordial aos familiares dos RNPT, visto que a ROP não é uma doença de fácil visualização; portanto, os pais estarem cientes de que o acompanhamento oftalmológico é de vital importância para a recuperação visual do bebê fará diferença na vida futura da criança. Assim, este estudo objetiva avaliar a prevalência e a evolução da ROP em RNPT internados em uma Unidade de Terapia Intensiva Neonatal (UTIN) e acompanhados em serviço de seguimento oftalmológico de referência. Trata-se de uma pesquisa quantitativa, descritiva e exploratória, realizada no município de Cascavel. A coleta de dados ocorreu em prontuários de RNPT, nascidos entre janeiro de 2014 e junho de 2016, hospitalizados na UTIN do Hospital Universitário do Oeste do Paraná – HUOP, e em seguimento pelo ambulatório do Hospital de Olhos de Cascavel, totalizando 181 prontuários. Realizou-se análise quantitativa, por meio de estatística descritiva e inferencial. A prevalência de ROP foi de 11,31% (n=50). Relacionados às suas características e evolução, os diagnósticos prevalentes nos RNPT do estudo foram as doenças respiratórias (41,99%) e, entre as comorbidades, a sepse prevaleceu (63,54%). Necessitaram de transfusão de sangue 80 RNPT (44,20%), e 152 (83,98%) fizeram uso de oxigenioterapia, com predomínio do dispositivo máscara (n=141; 77,90%) e tubo orotraqueal - TOT (n=100; 55,25%), em média por 15 dias. A maior concentração registrada foi por halo (45%). O tempo de uso e a concentração de O2 de TOT, tempo de uso de máscara e tempo e concentração de O2 do Continuous Positive Airway Pressure (CPAP) foram significativos para desencadear a ROP. Dentre os casos de ROP, dez (5,5%) crianças tiveram ROP grave e necessitaram de tratamento com laser. Todos os RNPT diagnosticados com ROP fizeram uso de oxigênio. A ROP prevaleceu nos prematuros moderados (44%), sendo o grau 3 de ROP o mais grave encontrado, acometendo tanto RNPT extremos quanto moderados. Doenças respiratórias, sepse e procedimentos como a transfusão de sangue e a oxigenioterapia influenciaram na presença da ROP, com prevalência em prematuros moderados. A adoção da triagem oftalmológica para a detecção da ROP, com exames de fundo de olho sistematicamente realizados na UTIN, contribuíram para o tratamento precoce e a prevenção de deficiências visuais graves e cegueira causados pela ROP. Nesse sentido, o enfermeiro é de fundamental importância, desde a prevenção, o diagnóstico até o decorrer do tratamento e a alta.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-02-26T11:57:05Z No. of bitstreams: 1 jomaraoliveiradossantosyogui.pdf: 569717 bytes, checksum: be9f77d66f6c940acf5caed0b7a11a98 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-03-03T13:37:39Z (GMT) No. of bitstreams: 1 jomaraoliveiradossantosyogui.pdf: 569717 bytes, checksum: be9f77d66f6c940acf5caed0b7a11a98 (MD5) / Made available in DSpace on 2016-03-03T13:37:39Z (GMT). No. of bitstreams: 1 jomaraoliveiradossantosyogui.pdf: 569717 bytes, checksum: be9f77d66f6c940acf5caed0b7a11a98 (MD5) Previous issue date: 2015-03-11 / A Retinopatia da Prematuridade(ROP) é uma das principais causas de cegueira na infância. A ROP pode ser evitável ou minimizada, desde que diagnosticada em tempo hábil. Objetivos: Determinar a ocorrência de retinopatia da prematuridade e avaliar os principais fatores associados e implicados no seu desenvolvimento. Métodos: Trata-se de um estudo transversal de base hospitalar, realizado no período de 2002 a 2012, no Hospital Universitário, HU/CAES/UFJF, de Juiz de Fora/MG-Brasil. A população de estudo é composta por 392 recém-nascidos, com idade gestacional < 37 semanas e qualquer peso ao nascimento. Resultados:A ocorrência da ROP no HU/CAS/UFJF foi de 29,9%. Os fatores associados à ROP, após a regressão logística, foram: baixo peso ao nascer, oxigenoterapia (cateter nasal e CPAP) e sepse neonatal. Conclusão: O presente estudo demonstrou significantes fatores associados à ROP após realizar a análise multivariada: peso ao nascer (foi demonstrado que quanto mais baixo o peso ao nascer maior é a ocorrência da ROP), oxigenioterapia (cateter nasal e CPAP) e sepse neonatal. / The retinopathy of prematurity(ROP) is one of the main causes of childhood blindness. The ROP can be avoided or minimized as long as it is diagnosed in time. Purposes: To determine the occurrence of retinopathy of prematurity and assess the main associated factors involved in its development. Methods: Seccional study carried out from 2002 at 2012, at the University Hospital HU/CAES/UFJF, Juiz de Fora (MG) – Brazil. The sample was composed of 392 newborns, with less than 37 weeks of gestational age and any birth weight. Results: The occurrence of ROP in HU/CAS/UFJF was of 29, 9%. The associated factors of ROP after the logistic regression were birth weight, oxygen Therapy (nasal catheter, CPAP), neonatal sepsis. Conclusion: The present study showed significant associated factors to ROP: birth weight (It was noticed that the lower the birth weight, the higher is the occurrence of ROP), oxygen Therapy (nasal catheter, CPAP) and neonatal sepsis.

<p>Stopa prematuriteta konstantno raste, a sve vi&scaron;e prevremeno rođenih beba koje prežive neonatalni i perinatalni period zahteva adekvatno sistemsko i oftalmolo&scaron;ko praćenje i tretman. Prematuritet sam po sebi, predstavlja rizik za razvoj vida. Taj rizik dodatno povećava prisustvo prematurne retinopatije i refraktivnih mana. Skrining i tretman promena na retini u sklopu prematuriteta, kao i optička korekcija refraktivnih mana obezbeđuju uslove za razvoj vida. Cilj ovog istraživanja je bio utvrditi promene biometrijskih karakteristika oka prematurusa, sa i bez prematurne retinopatije, tokom &scaron;estogodi&scaron;njeg praćenja, utvrditi refraktivni status ove dve grupe dece sa &scaron;est godina, te povezati promene biometrijskih karakteristika oka sa refrakcijom. U ispitivanje je uključeno 192 prevremeno rođena deteta (384 oka). Vr&scaron;ena su tri pregleda, u uzrastu od 3 meseca, 12 meseci i 6 godina starosti. Nakon prvog pregleda ispitivani uzorak je, u zavisnosti od nalaza na očnom dnu, podeljen na bebe sa prematurnom retinopatijom i bebe bez ovog oboljenja, a kako bi se uporedile proučavane karakteristike. U sva tri navedena uzrasta je pregledano očno dno i merene su tri glavne biometrijske karakteristike koje utiču na refraktivni status: aksijalna dužina oka, dubina prednje očne komore i debljina očnog sočiva. Sa &scaron;est godina je određena refrakcija, uključujući zakrivljenost rožnjače odnosno kornealni astigmatizam, vidna o&scaron;trina bez korekcije refraktivne mane, a zatim i nakon korekcije. Ostali neophodni podaci su dobijeni iz medicinske dokumentacije. Pokazano je da prematurna retinopatija utiče na refraktivni status i vidni ishod sa &scaron;est godina, pre svega uticajem na zakrivljenost rožnjače, aksijalnu dužinu oka i dubinu prednje očne komore, dok su promene debljine očnog sočiva bez posebnog značaja. Vidne o&scaron;trine oba oka u pred&scaron;kolskom uzrastu prevremeno rođene dece sa prematurnom retinopatijom su statistički značajno manje kada se uporede sa vidnim o&scaron;trinama prevremeno rođene dece bez retinopatije, ali razlika u ovim dvema vrednostima gubi statističku značajnost nakon optičke korekcije. Učestalost astigmatizma u prematurnoj populaciji sa 6 godina je visoka, a od onih koji imaju astigmatizam u tom uzrastu, vi&scaron;e od dve trećine je imalo prematurnu retinopatiju. Ukupna učestalost miopije, hipermetropije i emetropije u prematurnoj populaciji sa 6 godina je 18,9%, 54,7% i 13,2%, a preostalih 13,2% su anizometropi. U vi&scaron;e od trećine dece, sa prematurnom retinopatijom u najranijem uzrastu, sa &scaron;est godina postoji gubitak vidne sposobnosti, koji je najče&scaron;će blag, no može biti i potpun.</p> / <p>The number of babies born prematurely is constantly growing, so more and more of them need appropriate systemic and ophthalmologic monitoring and treatament. Prematurity itself, represents a risk for the development of vision. This risk further reinforces the presence of retinopathy of prematurity and refractive errors. Screening and treatment of retinopathy, as well as optical correction of refractive errors provide adequate conditions for the development of vision. The aim of this study was to determine changes of biometric features of eyes of the prematurely born infants, with and without retinopathy of prematurity, during the six-year follow-up. We also want to determine the refractive status of these two groups of children in the six year, and to link changes of biometric features with their eye refraction. The study included 192 prematurely born children (384 eyes). The examinations were performed at 3 months, 12 months and 6 years and they included fundus examination and measurements of the ocular axial length, anterior chamber depth and lens thickness. After dividing the subjects into two groups, based on the results of the fundus examination at 3 months, the results of the children with and without retinopathy were compared. At the age of six we also determine the refraction of eyes, including the curvature of the cornea and corneal astigmatism, visual acuity without correction of refractive error, and then after it. Other necessary data were obtained from medical documentation. It is shown that retinopathy of prematurity affects the refractive status and visual outcome at sixth year, primarily by the changes of curvature of the cornea, the axial length of the eye and the depth of the anterior chamber, while the change in the lens thickness has no significance. Visual acuity in both eyes in the preschool age preterm born children with retinopathy of prematurity are significantly less, when compared to visual acuity in preterm infants without retinopathy, but the difference in these two values lost statistical significance after optical correction. The rate of astigmatism in preterm population of six years is high, and of those who have astigmatism in this age group, more than two-thirds had retinopathy of prematurity. The overall incidence of myopia, hypermetropia and emetropia in the prematurely born, six years old children is 18.9%, 54.7% and 13.2%, and the remaining 13.2% have anisometropia. In more than a third of children with retinopathy of prematurity at an early age, with six years, there has been loss of visual acuity, which is usually mild, but it can be complete.</p>

Les yeux forment des avant-postes visuels importants du cerveau. Comme les autres organes, la rétine sensorielle des yeux est vulnérable aux effets nocifs des facteurs environnementaux, tels que la lumière et l'oxygène. Dans ce travail, nous nous sommes concentrés sur l’impact de l’exposition à une lumière constante et l’hyperoxie prolongée sur l'architecture et la fonction rétinienne. Dans la première partie de notre étude, nous avons montré qu’ une exposition de sept jours à une lumière constante perturbe la phagocytose des bâtonnets et cônes et régule négativement leur renouvellement dans la « rétine riche en cônes " d’Arvicanthis ansorgei. Notre étude donne un aperçu sur la physiopathologie des cônes, ce qui représente la principale source de handicap visuel dans une variété de pathologies rétiniennes, y compris la rétinite pigmentaire (RP) et la dégénérescence maculaire liée à l'âge (DMLA). Dans la deuxième partie de notre étude, nous avons montré qu’ une exposition de cinq jours à l’hyperoxie entraîne chez les souris néonatales une perte significative de cellules ganglionnaires dans les régions périphériques de la rétine, et de cellules à mélanopsine (ipRGC). L’exposition prolongée à l’hyperoxie perturbe également la capacité de photoentrainment des animaux probablement due à la perte des ipRGC et la perte de la rhodopsine dans les segments externes des bâtonnets chez les animaux traités. / Eyes form important visual outposts of the brain. Just like other organs, sensory retina in the eyes is also vulnerable to the injurious effects of environmental factors; such as light and oxygen. In this work, we have focused on the impacts of constant prolonged light and hyperoxia on the retinal architecture and function. In the first part of our study, we show that seven days of constant light disrupts rod and cone phagocytosis and downregulates their turnover in the “cone rich retina” of Arvicanthis ansorgei. The study gives an insight on the cone pathophysiology, which represents the major source of visual handicap in a variety of retinal pathologies, including retinitis pigmentosa (RP) and age-related macular degeneration (AMD). In the second part of our study, we show that five days of hyperoxia treatment in the neonatal mice results in the significant loss of retinal ganglion cells in the peripheral regions; the loss of melanopsin expressing retinal ganglion cells (ipRGC) was found to be significant. Hyperoxia also affects the photoentrainment capability of the animals probably because of the loss of ipRGC and the loss of rhodopsin in the outer segments of the photoreceptors in the treated animals.

La rétinopathie du prématuré, modélisée par les modèles de rétinopathie induite par l’oxygène (OIR), est l’une des principales causes de cécité dans l’enfance. Elle est constituée d’une première phase de vaso-oblitération rétinienne et choroïdienne suivie d’une phase de néovascularisation post-ischmémique rétinienne. La phase de dégénérescence vasculaire est entre autres liée d’une part à une baisse de l’expression des facteurs pro-angiogéniques et d’autre part à une inflammation rétinienne excessive. Toutefois, les mécanismes post-transcriptionnels à l’origine de ces phénomènes demeurent peu connus. La dérégulation des microARNs (miRs), des ARNs non codants régulant négativement l'expression des gènes, est impliquée dans la modulation de multiples processus physiologiques et pathologiques dont l’angiogenèse et l'inflammation. Cependant, le rôle des miRs dans l’angiogenèse et l’inflammation au cours de l’OIR reste à explorer. Basé sur l’établissement préalable d’un profil de modulation de l’expression des miRs au cours de l’OIR, nous avons sélectionné et caractérisé dans cette thèse le rôle d’un miR sur la fonction angiogénique puis d’un miR sur la fonction inflammatoire dans l’OIR. Nous avons caractérisé dans un premier temps, le miR-96. L’expression du miR-96 était significativement diminuée in vivo dans la rétine et la choroïde lors de la phase de vaso-oblitération du modèle murin de l’OIR. In vitro, le miR-96 était régulé négativement par l’hyperoxie dans les cellules endothéliales rétiniennes. La supplémentation en miR-96 avait un effet pro-angiogénique sur les cellules endothéliales rétiniennes soumises à l’hyperoxie par la préservation de la signalisation de facteurs angiogéniques, tels que VEGF et Ang2, leur permettant de maintenir leur capacité de migration et de tubulogenèse. In vivo, la supplémentation intravitréenne en miR-96 exerçait également ces fonctions vaso-protectives et permettait de préserver la microvascularisation rétinienne et choroïdienne par le maintien du niveau d’expression physiologique de VEGF et Ang2. Dans un second temps, nous avons caractérisé le miR-125a. L’expression du miR-125a était significativement diminuée in vivo dans la rétine lors de la phase de vaso-oblitération du modèle murin de l’OIR, mais également in vitro dans les cellules microgliales soumises à l’inflammation par hyperoxie ou LPS, ce qui était inversement corrélé à une augmentation de cytokines pro-inflammatoires telles que TNF-a, IL-6 et IL-16. Le miR-125a a été caractérisé comme anti-inflammatoire et sa supplémentation dans les cellules microgliales activées diminuait significativement l’expression de ces marqueurs pro-inflammatoires. La modification du sécrétome des cellules microgliales permettait une récupération des capacités angiogéniques des cellules endothéliales rétiniennes avec amélioration de leur prolifération et de leur tubulogenèse. In vivo, la supplémentation intravitréenne en mir-125a permettait de maintenir une expression physiologique de TNF-a, IL-6 et IL-16, ce qui était associé à une diminution de la vaso-oblitération rétinienne. Collectivement, ces travaux ont permis d’identifier et de caractériser le rôle du miR-96 dans la dysfonction angiogénique et du miR-125a dans la dysfonction inflammatoire lors de l’OIR. Cette thèse démontre pour la première fois qu’une thérapie basée sur la modulation de miRs spécifiques permettait de prévenir la dégénérescence vasculaire de l’OIR. Ces résultats pourraient constituer la base de nouvelles stratégies thérapeutiques dans le traitement précoce des rétinopathies ischémiques comme la rétinopathie du prématuré. / Retinopathy of prematurity is one of the leading causes of blindness in childhood and is represented by oxygen-induced retinopathy (OIR) models. It’s characterized by a first phase of retinal and choroidal vasoobliteration followed by a retinal neovascularization. The vascular degeneration is partly linked to a decrease in the expression of pro-angiogenic factors and to an excessive retinal inflammation. However, the post-transcriptional mechanisms implicated remain poorly understood. microRNAs (miRs) are non-coding RNAs that negatively regulate gene expression. Dysregulation of miRs is involved in the modulation of multiple physiological and pathological processes including angiogenesis and inflammation. However, the role of miRs in angiogenesis and inflammation during OIR remains to be explored. Based on the prior establishment of the modulation profile of miRs expression during OIR, we selected and characterized in this thesis the role of a miR on the angiogenic function then another miR on the inflammatory function in OIR. We first characterized the miR-96. In vivo, miR-96 expression was significantly downregulated in the retina and choroid during the vaso-obliteration phase of OIR rat. In vitro, miR-96 was downregulated by hyperoxia in retinal endothelial cells. miR-96 overexpression had a pro-angiogenic effect on retinal endothelial cells subjected to hyperoxia by preserving the signaling of angiogenic factors including VEGF and Ang2. This allowed to maintain their capacity for migration and tubulogenesis. In vivo, intravitreal supplementation with miR-96 also exerted these vasoprotective functions and preserved retinal and choroidal microvasculature by maintaining the physiological expression level of VEGF and Ang2. Secondly, we characterized the miR-125a. In vivo, the expression of miR-125a was significantly reduced in the retina during the vaso-obliteration phase of the OIR rat. In vitro, miR-125a was downregulated in microglial cells subjected to inflammation by hyperoxia or LPS, which was inversely correlated with an increase in pro-inflammatory cytokines such as TNF-a, IL-6 and IL-16. miR-125a was characterized as anti-inflammatory and its overexpression in activated microglial cells significantly decreased the expression of these pro-inflammatory markers. The modification of the secretome of the microglial cells allowed a recovery of the angiogenic capacities of the retinal endothelial cells with improvement of their proliferation and their tubulogenesis. In vivo, intravitreal supplementation with mir-125a maintained a physiological expression of TNF-a, IL-6 and IL-16, which was associated with a decrease in retinal vaso-obliteration. Collectively, these tasks identified and characterized the role of miR-96 in angiogenic dysfunction and miR-125a in inflammatory dysfunction during OIR. This thesis demonstrates for the first time that a therapy based on the modulation of specific miRs can prevent the OIR vascular degeneration. These results could form the basis of new therapeutic strategies in the early treatment of ischemic retinopathies such as retinopathy of prematurity.

La rétinopathie induite par l’oxygène (RIO) est un modèle animal semblable aux rétinopathies vue chez l’homme. Dans ce modèle, une destruction des microvaisseaux rétiniens est suivie d’une néovascularisation pathologique qui chez l’homme peut mener à un détachement de la rétine et subséquemment une perte de vision. Afin de remédier à cette revascularisation anarchique, un traitement de cellules souches (hématopoïétiques et mésenchymateuses) a été effectué chez des souris soumises à ce modèle. Les cellules injectées ont pu migrer à la rétine et induire une revascularisation saine (surtout les cellules souches mésenchymateuses). L’injection du milieu de culture de ces cellules induit aussi une revascularisation semblable à celle vue chez les souris traitées avec les cellules indiquant que l’effet thérapeutique des cellules semble être accompli par l’entremise de facteurs paracrines. Ces résultats suggèrent que ces cellules peuvent jouer un rôle au niveau de l’angiogénèse et indiquent un potentiel thérapeutique pour les rétinopathies. / Oxygen induced retinopathy (OIR) is an animal model that mimics the developing phases of retinopathies seen in humans such as diabetic retinopathy and retinopathy of prematurity. An initial destruction of retinal microvasculature is followed by pathological neovascularization that can lead to retinal detachment in humans and therefore blindness. Utilizing bone marrow derived stem cells (mesenchymal and hematopoietic), we aimed to repopulate the retina with normal vessels which are affected in the OIR model. Cells injected into the vitreous migrated to the retina and reduced both the area of vasoobliteration and neovascularization. Injection of conditioned cell medium also induced proper vascular repair similar to that seen in mice injected with cells indicating that the cells therapeutic effect is achieved through paracrine action. These results suggest that bone marrow stem cells play a role in angiogenesis and could be a potential therapeutic aid in treating retinopathies.

Dans les pays industrialisés, les rétinopathies ischémiques proliférantes telles que la rétinopathie diabétique et la rétinopathie du prématuré sont les principales causes de cécité chez les individus en âge de travailler et la population pédiatrique. Ces pathologies sont caractérisées par une dégénérescence microvasculaire initiale suivie d’une hyper-vascularisaton compensatoire disproportionnée et pathologique. Les sirtuines constituent une importante famille de protéines impliquées dans le métabolisme et la réponse au stress. Plus particulièrement, sirtuine 3 (SIRT3) est une déacétylase mitochondriale primordiale qui agit au cœur du métabolisme énergétique et de l’activation de nombreuses voies métaboliques oxydatives. Nos résultats démontrent pour la première fois qu’une déficience en SIRT3 diminue la sévérité des lésions vasculaires dans le modèle murin de rétinopathie induite par l’oxygène (OIR). En plus de stimuler l’angiogénèse, l’absence de SIRT3 est aussi associée à une augmentation de la glycolyse, possiblement en activant la famille de gènes 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB). Nous suggérons que le manque de SIRT3 est impliqué dans l’effet Warburg et procure ainsi un avantage prolifératif et protecteur dans l’OIR. La présente étude propose SIRT3 comme nouvelle cible thérapeutique potentielle dans la rétinopathie du prématuré, une maladie dont les complications désastreuses persistent tout au long de la vie. / Proliferative ischemic retinopathies such as proliferative diabetic retinopathy and retinopathy of prematurity (ROP) are the leading causes of blindness in working age and pediatric populations in industrialized countries. These pathologies are characterized by an initial microvascular degeneration followed by a disproportionate compensatory but pathological hyper-vascularization mounted by the hypoxic and energy deficient retina in an attempt to reinstate metabolic equilibrium. Sirtuins are an important family of protein involved in metabolism and stress response. Sirtuin 3 (SIRT3) in particular is a major mitochondrial deacetylase central to energy metabolism and the regulation of many oxidative pathways. For the first time, our results show that a lack of SIRT3 decreases the severity of vascular lesions in the oxygen-induced retinopathy (OIR) mouse model. Deficiency in SIRT3 not only stimulates angiogenesis, but also increases glycolysis, possibly through indirect activation of the gene family 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB). We suggest that a lack of SIRT3 is involved in the Warburg effect and therefore confers a proliferative advantage that is protective in OIR. The present study puts forward SIRT3 as a new potential therapeutic target for ROP, a disease leading to life-long vision complications.

La rétinopathie induite par l’oxygène (RIO) est un modèle animal semblable aux rétinopathies vue chez l’homme. Dans ce modèle, une destruction des microvaisseaux rétiniens est suivie d’une néovascularisation pathologique qui chez l’homme peut mener à un détachement de la rétine et subséquemment une perte de vision. Afin de remédier à cette revascularisation anarchique, un traitement de cellules souches (hématopoïétiques et mésenchymateuses) a été effectué chez des souris soumises à ce modèle. Les cellules injectées ont pu migrer à la rétine et induire une revascularisation saine (surtout les cellules souches mésenchymateuses). L’injection du milieu de culture de ces cellules induit aussi une revascularisation semblable à celle vue chez les souris traitées avec les cellules indiquant que l’effet thérapeutique des cellules semble être accompli par l’entremise de facteurs paracrines. Ces résultats suggèrent que ces cellules peuvent jouer un rôle au niveau de l’angiogénèse et indiquent un potentiel thérapeutique pour les rétinopathies. / Oxygen induced retinopathy (OIR) is an animal model that mimics the developing phases of retinopathies seen in humans such as diabetic retinopathy and retinopathy of prematurity. An initial destruction of retinal microvasculature is followed by pathological neovascularization that can lead to retinal detachment in humans and therefore blindness. Utilizing bone marrow derived stem cells (mesenchymal and hematopoietic), we aimed to repopulate the retina with normal vessels which are affected in the OIR model. Cells injected into the vitreous migrated to the retina and reduced both the area of vasoobliteration and neovascularization. Injection of conditioned cell medium also induced proper vascular repair similar to that seen in mice injected with cells indicating that the cells therapeutic effect is achieved through paracrine action. These results suggest that bone marrow stem cells play a role in angiogenesis and could be a potential therapeutic aid in treating retinopathies.