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Leung, Winnie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 155-164). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.v / Table of Contents --- p.vi / List of Figures --- p.x / Abbreviations --- p.xii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Clinical management of Cancer --- p.2 / Chapter 1.2 --- Multidrug resistance --- p.8 / Chapter 1.3 --- Aim of study --- p.14 / Chapter Chapter 2 --- Identification of gene contributing to multidrug resistance in human uterine sarcoma cells --- p.16 / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- Material and Methods / Chapter 2.2.1 --- Materials / Chapter 2.2.1.1 --- Cell lines --- p.20 / Chapter 2.2.1.2 --- "Cell culture medium, supplements and buffers" --- p.20 / Chapter 2.2.1.3 --- Gene expression assay reagents --- p.22 / Chapter 2.2.1.4 --- Western blotting reagents --- p.24 / Chapter 2.2.1.5 --- MTT assay reagents --- p.29 / Chapter 2.2.1.6 --- Apoptosis analysis by flow cytometry reagents --- p.29 / Chapter 2.2.2 --- Metho --- p.ds / Chapter 2.2.2.1 --- Cell Culture --- p.31 / Chapter 2.2.2.2 --- MTT assay --- p.32 / Chapter 2.2.2.3 --- Gene expression essay (RT-PCR) --- p.33 / Chapter 2.2.2.4 --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of protein lysate and Western blotting --- p.37 / Chapter 2.2.2.5 --- Quantification of doxorubicin uptake by flow cytometry --- p.40 / Chapter 2.2.2.6 --- Apoptosis analysis by flow cytometry --- p.41 / Chapter 2.3 --- Results --- p.4 / Chapter 2.3.1 --- Cytotoxicity of doxorubicin on SA and DX5 cells --- p.43 / Chapter 2.3.2 --- mRNA expression of multidrug resistance related genes in SA and DX5 cells --- p.46 / Chapter 2.3.3 --- P-glycoprotein expression in SA and DX5 cells --- p.49 / Chapter 2.3.4 --- Doxorubicin (Dox) uptake by SA and DX5 cells --- p.51 / Chapter 2.3.5 --- Doxorubicin induced Apoptosis in SA and DX5 cells --- p.54 / Chapter 2.4 --- Discussion --- p.61 / Chapter 2.5 --- Conclusion --- p.65 / Chapter Chapter 3 --- Alternation in P-glycoprotein expression in DX5_Ninjl cells --- p.66 / Chapter 3.1 --- Introduction --- p.67 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Materials / Chapter 3.2.1.1 --- Cell lines --- p.70 / Chapter 3.2.1.2 --- "Cell culture medium, supplements and buffers" --- p.70 / Chapter 3.2.1.3 --- Gene expression assay reagents --- p.70 / Chapter 3.2.1.4 --- Western blotting reagents --- p.72 / Chapter 3.2.1.5 --- Plasmid DNA extraction --- p.75 / Chapter 3.2.1.6 --- Transient transfection --- p.76 / Chapter 3.2.1.7 --- MTT reagents --- p.76 / Chapter 3.2.2 --- Methods / Chapter 3.2.2.1 --- Cell culture --- p.78 / Chapter 3.2.2.2 --- Gene expression essay (RT-PCR) --- p.79 / Chapter 3.2.2.3 --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of protein lysate and Western blotting --- p.81 / Chapter 3.2.2.4 --- DNA plasmid extraction --- p.83 / Chapter 3.2.2.5 --- Transient transfection --- p.84 / Chapter 3.2.2.6 --- MTT assay --- p.85 / Chapter 3.2.2.7 --- Quantification of doxorubicin (Dox) uptake by flow cytometry --- p.86 / Chapter 3.3 --- Results / Chapter 3.3.1 --- mRNA expression of Ninjurinl (Ninj1) in SA and DX5 cells --- p.87 / Chapter 3.3.2 --- The protein expression of Ninjurinl (Ninj1) in SA and DX5 cells --- p.89 / Chapter 3.3.3 --- Ninjurin1 (Ninj1) cDNA transfection in DX5 cells --- p.91 / Chapter 3.3.4 --- mRNA expression of MDR1 in Ninjurin1-transfected DX5 cells (DX5_Ninjl) --- p.93 / Chapter 3.3.5 --- P-glycoprotein expression in Ninjurin1-transfected DX5 cells --- p.95 / Chapter 3.3.6 --- "Cytotoxicity of doxorubicin (Dox) on DX5 control, DX5 vector control and DX5_Ninjl cells" --- p.97 / Chapter 3.3.7 --- "Doxorubicin (Dox) uptake by SA control, DX5 control and DX5_Ninjl cells" --- p.99 / Chapter 3.4 --- Discussion --- p.102 / Chapter 3.5 --- Conclusion --- p.105 / Chapter Chapter 4 --- Alternation in MDR1 expression in DX5一THBS1 cells --- p.106 / Chapter 4.1 --- Introduction --- p.107 / Chapter 4.2 --- Materials and Methods / Chapter 4.2.1 --- Materials / Chapter 4.2.1.1 --- Cell lines --- p.109 / Chapter 4.2.1.2 --- Cell culture medium； supplements and buffers --- p.109 / Chapter 4.2.1.3 --- Gene expression assay reagents --- p.109 / Chapter 4.2.1.4 --- Western blotting reagents --- p.111 / Chapter 4.2.1.5 --- Plasmid DNA extraction --- p.114 / Chapter 4.2.1.6 --- Transient transfection --- p.115 / Chapter 4.2.1.7 --- MTT reagents --- p.115 / Chapter 4.2.2 --- Methods / Chapter 4.2.2.1 --- Cell culture --- p.117 / Chapter 4.2.2.2 --- Gene expression essay (RT-PCR) --- p.118 / Chapter 4.2.2.3 --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of protein lysate and Western blotting --- p.120 / Chapter 4.2.2.4 --- DNA plasmid extraction --- p.123 / Chapter 4.2.2.5 --- Transient transfection --- p.123 / Chapter 4.2.2.6 --- MTT assay --- p.124 / Chapter 4.2.2.7 --- Quantification of doxorubicin (Dox) uptake by flow cytometry --- p.125 / Chapter 4.3 --- Results / Chapter 4.3.1 --- mRNA expression of Thrombospondinl (THBS1) in SA and DX5 cells --- p.126 / Chapter 4.3.2 --- The protein expression of Thrombospondinl (THBS1) in SA and DX5 cells --- p.128 / Chapter 4.3.3 --- Thrombospondinl (THBS1) cDNA transfection in DX5 cells --- p.130 / Chapter 4.3.4 --- mRNA expression of MDR1 in Thrombospondinl-transfected DX5 cells (DX5_THBS1) --- p.132 / Chapter 4.3.5 --- P-glycoprotein expression in Thrombospondinl-transfected DX5 cells --- p.134 / Chapter 4.3.6 --- "Cytotoxicity of doxorubicin (Dox) on DX5 control, DX5 vector control and DX5一THBS1 cells" --- p.136 / Chapter 4.3.7 --- "Doxorubicin (Dox) uptake by SA control, DX5 control and DX5_THBS1 cells" --- p.138 / Chapter 4.4 --- Discussion --- p.141 / Chapter 4.5 --- Conclusion --- p.145 / Chapter Chapter 5 --- General discussion --- p.146 / Chapter 5.1 --- Doxorubicin induced multidrug resistance in human uterin sarcoma cells via upregulation of P-glycoprotein --- p.147 / Chapter 5.2 --- The down-regulation of Ninjurin1 in human uterine sarcoma cells contributed to multidrug resistance --- p.148 / Chapter 5.3 --- The down-regulation of Thrombospondin1 in human uterine sarcoma cells contributed to multidrug resistance --- p.150 / Chapter 5.4 --- Conclusion and Future Perspective --- p.153 / Reference --- p.155

Thrombospondin-1 (TSP-1) binding to its membrane receptor CD47 results in an inhibtion of the nitric oxide (NO) receptor soluble guanylate cyclase (sGC) and a decrease in intracellular cGMP levels. This causes physiologic effects such as vasoconstriction and a rise in blood pressure. The mechanism by which TSP-1 binds to CD47 at the membrane to decrease sGC activity is largely unknown. CD47 can physically associate with a number of binding partners, including α(v)β₃ and vascular endothelial growth factor receptor 2 (VEGFR2). Binding of a C-terminal fragment of TSP-1 called E3CaG1 to CD47 leads to a rise in intracellular calcium ([Ca²⁺](i)), which decreases sGC activity via a phosphorylation event. Binding of E3CaG1 is also known to disrupt the interaction between CD47 and VEGFR2, leading to a decrease in endothelial nitric-oxide synthase (eNOS) activity and cGMP levels through an Akt signaling pathway. However, it is not known whether other membrane proteins associated with CD47 are required for E3CaG1 binding and a subsequent [Ca²⁺](i) increase. Plasmon-waveguide resonance (PWR) spectroscopy was employed to elucidate the mechanism of TSP-1 inhibition of sGC activity through membrane complexes involving CD47. Using PWR, I found E3CaG1 can bind specifically to CD47 within native Jurkat membranes with picomolar and nanomolar dissociation constants (K(d)), suggesting multiple CD47 complexes are present. Among these complexes, CD47/VEGFR2 was found to bind E3CaG1 with a picomolar K(d)and CD47/α(v)β₃ was found to bind E3CaG1 with a nanomolar K(d). In addition, the presence of an anti-VEGFR2 antibody inhibited the E3CaG1-induced calcium response, which suggested CD47 in complex with VEGFR2 was responsible for TSP-1 reduction of sGC activity. I show that when both CD47 and VEGFR2 are returned to a HEK 293T cell line that does not contain these receptors, an increase in [Ca²⁺](i) upon E3CaG1 binding is restored. Interestingly, E3CaG1 was also found to bind to VEGFR2 in complex with the integrin α(v)β₃ on CD47-null cell lines and their derivations, causing a decrease in [Ca²⁺](i) levels. Therefore, the third type 2 repeat and C-terminal domains of TSP-1 can cause both increases and decreases in calcium based upon the availability of protein complexes to which it binds.

Les métastases sont à l'origine dans 90% des cas du décès des patients et sont donc un enjeu thérapeutique majeur. Les traitements anti-angiogéniques qui inhibent la vascularisation tumorale et augmentent l'hypoxie ont une efficacité limitée en clinique. Des liens ont été établis entre l'hypoxie et le changement métabolique des cellules tumorales, l'augmentation des cellules souches cancéreuses, la transition épithélio-mésenchymateuse et la résistance aux traitements mais également la dissémination métastatique. Ces observations nous ont poussés à réévaluer le rôle de l'hypoxie dans la dissémination métastatique du cancer du sein, en nous focalisant sur l'étude du premier inhibiteur endogène de l'angiogenèse identifié, la Thrombospondine 1 (TSP1). En clinique, nous avons observé que l'expression de la TSP1 est corrélée aux marqueurs d'agressivité et qu'elle augmente avec le grade tumoral. Dans un modèle orthotopique de tumeurs mammaires métastatiques, nous avons montré que l'inhibition de la TSP1 réduit fortement l'EMT, l'invasion et les métastases pulmonaires alors même que la vascularisation de la tumeur primaire est densifiée et plus fonctionnelle, réduisant l'hypoxie. Pour déterminer le rôle de la TSP1 dans la survenue des métastases, nous avons effectué des mutations ponctuelles de ce gène dans le domaine d'activation du TGFbéta ou dans celui de la liaison au CD36 qui médie majoritairement les propriétés anti-angiogéniques de la TSP1. La mutation de l'une ou l'autre de ces séquences entraîne une diminution drastique des métastases pulmonaires. Ce travail nous conduit à proposer un nouveau concept thérapeutique, visant à normaliser la vascularisation tumorale et à réduire l'hypoxie par une stratégie "anti-antiangiogénique" basée sur l'inhibition de la TSP1. Cette stratégie devrait inhiber la dissémination métastatique et favoriser la pénétration des traitements chimiothérapeutiques et augmenter l'efficacité de la radiothérapie, dépendante de la présence d'oxygène. / Metastasis are responsible for 90% of cases of patients death and so represent a major therapeutic challenge in oncology. Anti-angiogenic treatments, which inhibit tumor vascularization and increase hypoxia, have limited clinical efficiency. This inefficiency could be a consequence of hypoxia. Indeed, links have been established between hypoxia and: metabolic changes in tumor cells, increase in cancer stem cells, epithelial-mesenchymal transition and resistance to treatment. Experimental and clinical evidence also suggest that hypoxia may directly induce metastatic dissemination. These observations led us to reassess the role of hypoxia in metastatic dissemination by focusing on the study of the first identified endogenous angiogenic inhibitor, the Thrombospondin 1 (TSP1). TSP1 is also an activator of latent TGFbéta. The aim of this work was to study the role of TSP1 in tumor progression and dissemination of metastatic breast cancer. In clinic, we observed that the expression of TSP1 is correlated with markers of aggressiveness and that it increases with tumor grade. In an orthotopic model of metastatic breast tumors, we have shown that inhibition of TSP1 strongly reduce EMT, invasion and lung metastasis meanwhile the vascularization of the primary tumor is densified and more functional, thus reducing hypoxia. To determine the role of TSP1 in the occurrence of metastasis, we generate point mutations of this gene in TGFbéta activation domain or in the binding domain to CD36 that predominantly mediates the anti-angiogenic properties of TSP1. Mutations of either of these sequences result in a drastic decrease in lung metastasis, which confirms the importance of TGFbéta in metastatic dissemination. Our results also demonstrate a direct link between hypoxia and metastasis: the inactivation of anti-angiogenic properties of TSP1, which increases tumor perfusion and decreases hypoxia without affecting primary tumor growth, blocks metastatic dissemination even though the cells have the ability to migrate. This work led us to propose a new therapeutic concept aiming to normalize tumor vascularization and reduce hypoxia by an "anti-antiangiogenic" strategy based on TSP1 inhibition. This strategy should inhibit metastatic spreading, promote the diffusion of chemotherapeutic treatments and increase the efficiency of radiotherapy, dependent on oxygen presence.

Thrombospondin-1 (TSP-1) is synthesized, secreted, and incorporated into the extracellular matrix by a variety of cells, including the endothelial cells. Addition of angiotensin II (AII) significantly induced TSP-1 mRNA in rat heart-derived endothelial cells. TSP-1 mRNA levels reached a plateau within 2 h after the addition of AII and decreased after 5 h. The induction was superinduced by cycloheximide and blocked by actinomycin D. Losartan, an AT1 receptor antagonist, could abolish the induction of TSP-1 mRNA by AII. Phorbol 12-myristate 13-acetate (TPA) was found to enhance TSP-1 mRNA level whereas a protein kinase C inhibitor, H7, was shown to block the induction. Immunoblot analysis revealed that TSP-1 was detectable in the medium 4 h after AII stimulation. Our results suggest that the upregulation of TSP-1 by All represents an important mechanism leading to perivascular fibrosis in the heart.

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Diabetic kidney disease (DKD) is the leading cause of end stage renal disease worldwide and occurs in up to 40% of patients with diabetes. The standard of care for DKD treatment has not kept up with the current health epidemic, which has led to a heavy economic toll and substantial health burden. Targeting either cell surface (cs)GRP78, activated α2-macroglobulin (α2M*) or preventing their interaction may provide a novel anti-fibrotic therapeutic target for the treatment of DKD and potentially non-diabetic chronic kidney disease (CKD) as well. Previously our lab has shown that HG-induced csGRP78 is a mediator of PI3k/Akt signaling and downstream extracellular matrix (ECM) protein production in glomerular mesangial cells (MC). However, the ligand responsible for activating high glucose (HG)-induced csGRP78 had not yet been determined. We have shown thus far that α2M is endogenously produced, secreted, and activated (denoted α2M*) in HG by MC, which leads to its binding to and activation thereof csGRP78. Further, α2M knockdown or α2M* neutralization attenuated Akt activation, the production of the profibrotic cytokine connective growth tissue factor (CTGF) and ECM proteins fibronectin and collagen IV. We have also shown that integrin β1 (Intβ1), a transmembrane receptor, associated with csGRP78 under HG conditions and likely acts as a tether to present csGRP78 completely extracellularly on MC. Interestingly, Intβ1 activation, even in the absence of HG, was sufficient to induce csGRP78 translocation. Further, inhibition of either csGRP78 or Intβ1 prevented synthesis, secretion and signaling of TGFβ1. This data implicates a role for Intβ1 as a required signaling partner for csGRP78-mediated profibrotic signaling. To further our understanding of csGRP78/ α2M*’s role in DKD, we investigated their ability to mediate TGFβ1 signaling through its non-proteolytic activator thrombospondin-1 (TSP1). Here, HG-induced TSP1 expression, ECM deposition, and activation of TGFβ1 was regulated by the PI3k/Akt pathway via csGRP78/α2M* in MC. Furthermore, we assessed whether this csGRP78/ α2M* axis is relevant to promoting profibrotic signaling in other renal cell types, including proximal tubule epithelial cells (PTEC) and renal fibroblasts (RF), that contribute to the pathogenesis of both later stage DKD and non-diabetic CKD. We show evidence here that HG and direct treatment with TGFβ1, a key pathologic regulator of kidney fibrosis, induce GRP78 surface translocation as well as the endogenous production and activation of α2M in both PTEC and RF. Inhibition of either csGRP78 or α2M* prevented TGFβ1 signaling measured as Smad3 activation as well as downstream ECM production. Interestingly, inhibition of this pathway under direct TGFβ1 treatment did not prevent Smad3 activation, implicating a role for Smad-independent TGFβ1 signaling through this axis. We identified the known noncanonical TGFβ1 signaling partners, yes associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ), are mediated by csGRP78 and α2M*. Lastly, we evaluated the potential therapeutic benefit of inhibiting csGRP78/α2M* interaction in the kidney fibrosis model, unilateral ureteral obstruction (UUO). Here, we show evidence that inhibition of this signaling axis using an inhibitory peptide can prevent renal fibrosis. Whether this peptide also prevents fibrosis in DKD is currently being assessed. Together, these studies strongly implicate targeting csGRP78/α2M* interaction as a novel anti-fibrotic therapeutic intervention for early and late stage DKD, as well as a potential role in non-diabetic CKD. / Thesis / Doctor of Philosophy (Medical Science) / Diabetic kidney disease is the leading cause of kidney failure in developed nations. This progressive disease leads to the loss of kidney function due to an accumulation of scar proteins in the kidney over time. High glucose is a major factor that causes this to occur. Our lab studies specific kidney cells called mesangial cells, proximal tubule epithelial cells, and fibroblasts that produce scar proteins in the presence of high glucose. We have shown that when these cells are treated with high glucose, this causes the movement of a protein called GRP78 that normally resides inside the cell to move to the cell’s surface where it can interact with other proteins. My research has established that the proteins alpha 2-macroglobulin (ɑ2M), integrin β1 (Intβ1), and thrombospondin-1 (TSP1) can bind to GRP78 on the cell surface and cause cells to make scar proteins. Preventing ɑ2M or Intβ1 from binding to GRP78 or preventing TSP1 production prevents mesangial cells from making scar proteins when exposed to high glucose. In a mouse model that overproduces these scar proteins, we showed that preventing cell surface GRP78 and α2M interaction prevents scar protein production and is thus a novel potential treatment option for kidney disease.

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Activée par la chimiothérapie, la sénescence est un mécanisme suppresseur de tumeur qui bloque la progression tumorale. Cependant, des cellules cancéreuses sont capables d’échapper à cette pression ce qui provoque une rechute clinique. Nous avons récemment décrit que les cellules émergentes acquièrent la capacité de résister à l’anoïkis et dépendent de Mcl-1. Cette voie de survie est activée par la kinase Akt qui inhibe la protéine Noxa et l’apoptose. L’une des caractéristiques de la sénescence est l’apparition d’un phénotype sécrétoire appelé SASP qui peut induire des effets délétères aux cellules voisines. Dans cette étude nous avons observé que le sécrétome des cellules persistantes induit la résistance à l’anoïkis, la migration et l’invasion des cellules parentales. Des études de protéomique réalisées au laboratoire ont montré que laTSP-1 est surexprimée dans les stades avancés de tumeurs de patients du sein et du colon. Lors de la persistance, la TSP-1 et son récepteur CD47 sont exprimés plus fortement par les cellules sénescentes. Le blocage de la TSP-1 ou de sa liaison à CD47 augmente l’émergence et induit la formation de sphéroïdes traduisant une augmentation de la proportion de cellules souches. Les facteurs d’auto-renouvellement Nanog etKlf4 sont induits précocement en réponse au traitement. Suite à l’inactivation de CD47 ou à une stimulation avec laTSP-1, l’expression de Nanog est bloquée. L’inhibition de Nanog ou de Klf4 diminue l’émergence. Ainsi, dans les cellules sénescentes, CD47 activerait le mécanisme d’auto-renouvellement et favoriserait l’émergence. En seliant, la TSP-1 bloquerait ces mécanismes et agirait comme un suppresseur de tumeur. / Activated by chemotherapy, senescence is a suppressive mechanism that prevents tumor progression. However some cancer cells can emerge and induce clinical relapse. We have recently described that emergent cells resist toanoikis and depend on Mcl-1. This survival pathway is activated by Akt kinase that inhibits Noxa and apoptosis. One of the caracteristics of senescence is the appearance of the secretory phenotype called SASP that can induce deleterious effects to neighboring cells. In this study, we observed that the secretome of persistant cells induces anoïkis resistance, migration and invasion of parental cells. Proteomics analysis performed at laboratory showed that TSP-1 is over expressed in advanced stages of colon and breast tumors. During persistance, TSP-1 and its receptor CD47 are more expressed by senescent cells. Blockade of TSP-1 or its binding on CD47 increases persistence and induces spheroïds generation showing an increase in the proportion of stem cells. Self-renewal factors Nanog and Klf4 are early expressed following treatment. Following CD47 inactivation or stimulation withTSP-1, the expression of Nanog is blocked. The inhibition of Nanog or Klf4 reduces emergence. So, in senescent cells, CD47 could activate self-renewal and could promote emergence. By linking to its receptor, TSP-1 could block these processes et coud act as a tumor suppressor.

A aterosclerose é uma doença crônica onde duas características marcantes são observadas: retenção de lipídios e inflamação. Compreender as interações entre as células do sistema imunológico e as lipoproteínas envolvidas na aterogênese são desafios urgentes, uma vez que as doenças cardiovasculares são a principal causa de morte no mundo. Os macrófagos são cruciais para o desenvolvimento de placas ateroscleróticas e para a perpetuação da inflamação em tais lesões; estas células também estão diretamente envolvidas na ruptura de placa instável. Recentemente diferentes populações de macrófagos estão sendo identificadas nas lesões ateroscleróticas. Embora macrófagos M2 tenham sido identificados, a função destas células na aterosclerose ainda não está definida. Neste projeto, avaliamos se a adição de LDLox altera a função de macrófagos M2. Resultados: 1- Foi possível observar que os M2 se mantem viáveis após o estímulo com as lipoproteínas. 2- Quando avaliamos a expressão de moléculas co-estimulatórias, receptores Scavenger, lectinas e integrinas na superfície das células, observamos que a adição de LDLn ou LDLox em 2 concentrações diferentes (5 e 50ug/ml), por diferentes períodos de tempo não alterou a expressão de nenhum dos marcadores avaliados. A presença de LDL também não alterou outra função primordial dos M2, a capacidade de fagocitose. 3- Quando investigamos a presença de citocinas no sobrenadante das culturas estimuladas ou não com as lipoproteínas, identificamos um aumento na secreção de IL-8, uma citocina pró-inflamatória, na presença de LDLox, semelhante ao observado com a população de macrófagos M1. 4- Avaliamos se os macrófagos M2 estimulados ou não com LDL mantem sua capacidade de favorecer a angiogênese. Observamos que nas culturas estimuladas com o sobrenadante das culturas dos M2 mantidos na presença de LDLox houve uma inibição significativa da formação de túbulos pelas HUVECs. 5- Observamos que na presença do meio condicionado dos M2 estimulados com LDLox ocorreu uma intensa degradação dos filamentos de matriz extracelular produzida por MEFs. 6- Avaliamos a expressão gênica de componentes de matriz, membrana basal, moléculas de adesão, proteases e também inibidores de protease nestas células. Dos 96 genes avaliados, observamos que a adição de LDLox reduziu a expressão de 10 genes de maneira significativa, entre eles: beta-Actina (ACTB), Colágeno 6A2 (Col6A2), Integrina alfa 6 (ITGA6), Metaloproteinase 15 (MMP15), molécula de adesão celular endotelial plaquetária (PECAM) e Inibidor de metalopeptidase 2 (TIMP2). A adição de LDLox aumentou significativamente somente a expressão de trombospondina (TSP1). A adição de LDLn não alterou a expressão de nenhum gene de forma significativa. 7- A adição de LDLox induziu aumento da expressão da TSP1 e redução da expressão de colágeno 6, quando comparadas aos macrófagos M2 sem estímulo. Nossos resultados indicam que a adição de LDLox altera diversas funções dos macrófagos M2 in vitro. Em especial detectamos uma inibição significativa na angiogênese e também a secreção de mediadores que induzem a degradação da matriz extracelular. A adição de LDLox também inibiu a expressão de genes envolvidos com a estabilização da matriz extracelular. Nossos resultados sugerem que esta população de células pode contribuir para a perpetuação do processo inflamatório e degradação tecidual observados na lesão dos pacientes. Assim, acreditamos que este projeto contribuiu para o esclarecimento da participação dos M2 na patologia da aterosclerose / Atherosclerosis is a chronic disease where two key characteristics are observed: lipid retention and inflammation. Understanding the interactions between the cells of the immune system and the lipoproteins involved in atherogenesis are urgent challenges, since cardiovascular diseases are the leading cause of death in the world. Macrophages are crucial for the development of atherosclerotic plaques and for the inflammation in such lesions; These cells are also directly involved in unstable plaque rupture. Recently different populations of macrophages are being identified in atherosclerotic lesions. Although M2 macrophages has been identified, the function of these cells in atherosclerosis has not yet been defined. This project, we evaluated whether the addition of OxLDL alters the function of M2 macrophages. Results: 1- M2 macrophages remain viable after stimulation with the lipoproteins. 2- When evaluated the expression of co-stimulatory molecules, Scavenger receptors, lectins and integrins on the surface of the cells. We observed that the addition of LDLn or OxLDL at 2 different concentrations (5 and 50 ?g / ml) for different time periods did not alter the expression of any of the evaluated markers. 3- The presence of LDL also did not alter other primordial function of M2 cells, phagocytosis. 4- Was observed that cultures stimulated with conditioned medium of OxLDL-stimulated M2 there was a significant inhibition of tubule formation by HUVECs. 5- We observed that in the presence of OxLDL-stimulated M2 cells conditioned médium an intense degradation of the matrix filaments occurred. 6- We evaluated the gene expression of matrix components, basement membrane, adhesion molecules, proteases and also protease inhibitors in these cells. Of the 96 evaluated genes, we observed that the addition of OxLDL significantly reduced the expression of 10 genes, among them: Actin-beta (ACTB), Collagen 6A2 (Col6A2), Integrin alfa 6 (ITGA6), Metaloproteinase 15 (MMP15), Platelet endothelial cell adhesion molecule (PECAM) and metallopeptidase 2 inhibitor (TIMP2). The addition of OxLDL significantly increased only the expression, thrombospondin-1 (TSP1). Addition of LDLn did not significantly alter the expression of any gene. 7- That OxLDL addition induced increased TSP1 expression and reduced collagen 6 expression, when compared to M2 macrophages without stimulation. Our results indicate that the addition of OxLDL alters several M2 macrophages functions in vitro. In particular we detected a significant inhibition in angiogenesis and also the secretion of mediators that induce the degradation of the extracellular matrix. The addition of OxLDL also inhibited the expression of genes involved in extracellular matrix stabilization. Our results suggest that this cell population may contribute to the perpetuation of the inflammatory process and tissue degradation observed in the lesion of the patients. Thus, we believe that this project contributed to better understand the participation of M2 in the pathology of atherosclerosis