Indiana University-Purdue University Indianapolis (IUPUI) / Sepsis is a clinical syndrome due to a systemic inflammatory response to severe microbial infection. Little is known about the changes in the bone marrow (BM) and how they affect the hematopoietic response to bacterial infection. Using an animal model of severe sepsis induced by Pseudomonas aeruginosa, we have previously reported that hematopoietic stem cells (HSC) undergo a significant expansion in the BM accompanied with myeloid suppression. This bone marrow response was Toll-like Receptor 4 (TLR4)-dependent. TLR4 is activated by bacterial lipopolysaccharide (LPS) and signals through two major independent downstream molecules: TRIF and MyD88. In the present study, I found that the TLR4/TRIF and the TLR4/MyD88 pathways contribute in a distinct manner to the BM response to P. aeruginosa's LPS. TRIF plays a major role in the expansion of the HSC pool, whereas MyD88 is required for myeloid suppression. Following LPS stimulation, HSCs enter in the cell cycle, expand and exhaust when transplanted in healthy mice. Loss of TRIF rescued completely the long-term engraftment and multilineage reconstitution potential of septic HSCs, but did not affect myeloid differentiation. Conversely, MyD88 deficiency prevented completely the myeloid suppression in the myeloid progenitors, but conferred limited protective effects on the HSC function. It is of great therapeutic value to identify the downstream molecules involved in TLR4/MyD88 dependent myeloid suppression. I found miR-21, a microRNA that is involved in inflammation, was up-regulated upon LPS challenge in a MyD88-dependent manner. However, deletion of miR-21 in the BM did not rescue LPS-induced bone marrow dysfunction, demonstrating that miR-21 is not a critical regulator in these processes. Further studies are warranted to determine the precise molecular mechanisms involved in the complex pathogenesis of BM response to sepsis. Taken together, my results show for the first time that the TLR4/TRIF signaling as a key mediator of HSC damage during acute LPS exposure and that activation of the TLR4/MyD88 signaling pathway play a dominant role in myeloid suppression. These results provide novel insights into our understanding of the molecular mechanisms underlying bone marrow injury during severe sepsis and may lead to the development of new therapeutic approaches in this disease.

Thesis (PhD (Physiology (Human and animal))-- University of Stellenbosch, 2007. / Definition: Stem cells are unspecialised cells with the capacity for long-term self-renewal and the ability to differentiate into multiple cell-lineages. The potential for the application of stem cells in clinical settings has had a profound effect on the future of regenerative medicine. However, to be of greater therapeutic use, selection of the most appropriate cell type, as well as optimisation of stem cell incorporation into the damaged tissue is required. In adult skeletal muscle, satellite cells are the primary stem cell population which mediate postnatal muscle growth. Following injury or in diseased conditions, these cells are activated and recruited for new muscle formation. In contrast, the potential of resident adult stem cell incorporation into the myocardium has been challenged and the response of cardiac tissue, especially to ischaemic injury, is scar formation. Following muscle damage, various growth factors and cytokines are released in the afflicted area which influences the recruitment and incorporation of stem cells into the injured tissue. Transforming Growth Factor-β (TGF-β) is a member of the TGF-β-superfamily of cytokines and has at least three isoforms, TGF-β1, -β2, and -β3, which play essential roles in the regulation of cell growth and regeneration following activation and stimulation of receptor-signalling pathways. By improving the understanding of how TGF-β affects these processes, it is possible to gain insight into how the intercellular environment can be manipulated to improve stem cell-mediated repair following muscle injury. Therefore, the main aims of this thesis were to determine the effect of the three TGF-β isoforms on proliferation, differentiation, migration and fusion of muscle progenitor cells (skeletal and cardiac) and relate this to possible improved mechanisms for muscle repair. The effect of short- and long-term treatment with all three TGF-β isoforms were investigated on muscle progenitor cell proliferation and differentiation using the C2C12 skeletal muscle satellite and P19 multipotent embryonal carcinoma cell-lineages as in vitro model systems. Cells were treated with 5 ng/mℓ TGF-β isoforms unless where stated otherwise. In C2C12 cells, proliferating cell nuclear antigen (PCNA) expression and localisation were analysed, and together with total nuclear counts, used to assess the effect of TGF-β on myoblast proliferation (Chapter 5). The myogenic regulatory factors MyoD and myogenin, and structural protein myosin heavy chain (MHC) were used as protein markers to assess early and terminal differentiation, respectively. To establish possible mechanisms by which TGF-β isoforms regulate differentiation, further analysis included determination of MyoD localisation and the rate of MyoD degradation in C2C12 cells. To assess the effect of TGF-β isoforms on P19 cell differentiation, protein expression levels of connexin-43 and MHC were analysed, together with the determination of embryoid body numbers in differentiating P19 cells (Chapter 6). Furthermore, assays were developed to analyse the effect of TGF-β isoforms on both C2C12 and P19 cell migration (Chapter 7), as well as fusion of C2C12 cells (Chapter 8). Whereas all three isoforms of TGF-β significantly increased proliferation of C2C12 cells, differentiation results, however, indicated that especially following long-term incubation, TGF-β isoforms delayed both early and terminal differentiation of C2C12 cells into myotubes. Similarly, myocyte migration and fusion were also negatively regulated following TGF-β treatment. In the P19 cell-lineage, results demonstrated that isoform-specific treatment with TGF-β1 could potentially enhance differentiation. Further research is however required in this area, especially since migration was greatly reduced in these cells. Taken together, results demonstrated variable effects following TGF-β treatment depending on the cell type and the duration of TGF-β application. Circulating and/or treatment concentrations of this growth factor could therefore be manipulated depending on the area of injury to improve regenerative processes. Alternatively, when selecting appropriate stem or progenitor cells for therapeutic application, the effect of the immediate environment and subsequent interaction between the two should be taken into consideration for optimal beneficial results.

O diabetes mellitus do tipo 1 (T1D) é uma doença autoimune mediada por células T e caracterizada pela destruição seletiva das células ? pancreáticas produtoras de insulina. Células estromais mesenquimais (MSCs) e células tronco hematopoéticas (HSCs) são os principais componentes do nicho hematopoético na medula óssea. Estas células vêm sendo utilizadas nos últimos anos em transplantes autólogos para tratamento do T1D. O objetivo geral do presente trabalho foi avaliar o perfil de expressão gênica global de MSCs e HSCs de pacientes com T1D e compará-lo com células isoladas de indivíduos saudáveis através da técnica de microarray e programas específicos de bioinformática. As MSCs e HSCs foram isoladas da medula óssea de pacientes com T1D antes e após o tratamento com imunossupressão em altas doses seguida pelo transplante autólogo de células tronco hematopoéticas (AHSCT). As MSCs apresentaram valor elevado de expressão absoluta de diversas moléculas potencialmente relacionadas com suas funções de suporte à hematopoese. MSCs de pacientes diabéticos apresentaram perfil de expressão gênica global distinto das isoladas de indivíduos saudáveis, com hiper-regulação da sinalização via proteína G e hiporregulação da atividade transcricional. O receptor ?3 adrenérgico, assim como a sinalização simpática, foram hiper-expressos nas células dos pacientes. Genes que codificam moléculas que suportam a hematopoese e regulados pelo sistema nervoso simpático, VCAM1 e CXCL12, foram hiporregulados em nossa análise. Após o AHSCT, houve atenuação do perfil de expressão diferencial das MSCs dos pacientes, entretanto elas permaneceram com hiperatividade da sinalização via proteína G e déficit da atividade transcricional. As HSCs apresentaram altos níveis de expressão absoluta de diversas integrinas e receptores de citocinas e fatores de crescimento, potencialmente relacionados com funções na hematopoese. HSCs de pacientes com T1D apresentaram perfil de expressão gênica global distinto das de indivíduos saudáveis, com hiper-regulação de genes associados com a atividade transcricional. Os fatores de transcrição TCFL2 e p53, que têm papel fundamental na regulação do ciclo celular das HSCs, foram diferencialmente expressos entre as HSCs de pacientes diabéticos e controles. Assim, nossos resultados de expressão gênica global apontaram alterações intrínsecas nas HSCs e MSCs de pacientes diabéticos que podem estar relacionadas com a falha terapêutica dos transplantes autólogos. A implicação dessas alterações no desenvolvimento e patogênese do T1D permanece desconhecida e a realização de ensaios funcionais poderá esclarecer o significado biológico das mesmas. / Type 1 diabetes mellitus (T1D) is a T cell-mediated autoimmune disease, characterized by selective destruction of insulin-producing pancreatic ? cells. Mesenchymal stromal cells (MSCs) and hematopoietic stem cells (HSCs) are the main components of hematopoietic niches. In the last years, these cells are being used in autologous transplantation settings for T1D treatment. The main goal of this study was to evaluate the global gene expression profile of MSCs and HSCs from T1D patients, by using microarrays and bioinformatics specific programs. MSCs and HSCs were isolated from bone marrow of T1D patients before and after treatment with high dose immunossupression followed by hematopoietic stem cell transplantation. MSCs showed high absolute expression values of several molecules potentially related to their function of hematopoiesis support. MSCs from T1D patients exhibited distinct gene expression profile from control MSCs and presented up-regulation of the G protein-coupled receptor signaling pathway and down-regulation of transcriptional activity. The ?3 adrenergic receptor, as well the sympathetic nervous system signaling were up-regulated on patient´s cells. Genes that codify molecules which support hematopoeisis and are regulated by the symphatic nervous system, VCAM1 and CXCL12, were downregulated on our analysis. After AHSCT, there was an attenuation of the differential expression profile of MSCs from T1D patients, however they remained with G proteincoupled receptor signaling pathway hyperactivity and transcriptional activity deficit. HSCs exhibited high absolute expression values of integrins, cytokine receptors and growth factors, molecules potencially related to hematopoietic functions. HSCs from T1D patients showed distinct expression profile from control HSCs and demonstrated up-regulation of genes related to transcriptional activity. The transcription factors TCFL2 and p53, which have important role in regulating HSC cycle, were differentially expressed between HSCs from T1D patients and controls. Thus, our global gene expression analysis has revealed intrinsic alterations on MSCs and HSCs from T1D patients that could be related to the autologous transplant therapeutic failures. The implications of these alterations on the development and pathogenesis of T1D remain unknown and functional assays could unravel their biological meaning.

A sepse causa uma alta taxa de mortalidade no mundo. A fisiopatologia da doença envolve uma rede complexa de mediadores inflamatórios que promovem a lesão de diversos tecidos, além de diversas alterações hemodinâmicas e disfunção do sistema nervoso autonômico (SNA). Assim sabe-se que o sistema nervoso cumpre um papel importante no controle da inflamação sistêmica mediante a via colinérgica anti-inflamatória (VCA) através do receptor nicotínico de acetilcolina alfa7 (alfa7nAChR). O uso das células-tronco mesenquimais (CTM) tem mostrado efeitos benéficos em diversos ensaios clínicos de doenças inflamatórias. Neste contexto, as células-tronco mesenquimais derivadas da geleia de Wharton do cordão umbilical (CTM-GW) tornam-se promissórias, uma vez que essas células são reconhecidas pela regulação da resposta imunológica, reparação neural, efeito anti-apoptose, assim como a melhora da sobrevida na sepse, em modelos experimentais. Nossa hipótese foi de que as CTM-GW poderiam cumprir um papel neuroimunomodulador através da VCA e atenuar a disfunção de múltiplos órgãos em um modelo animal de sepse de ligadura e punção do ceco (LPC). Inicialmente células da matriz do cordão umbilical foram isoladas e caracterizadas de acordo com o consenso internacional vigente. Ratos Wistar machos adultos foram subdivididos em grupos: 1) sham (operação simulada); 2) LPC; 3) LPC+CTM-GW (injetado 106 CTM-GW via intraperitoneal, i.p. 6 h após LPC) e 4) LPC+MLA+CTM-GW (MLA: Metillicaconitine, antagonista do alfa7nAChR, i.p., 5:30 h após LPC e 106 CTM-GW 6h após). Às 24 horas após LPC, foram avaliadas a função cardiovascular, hemodinâmica assim como os outros parâmetros. Interessantemente, o tratamento com CTM-GW na sepse atenuou a disfunção diastólica e protegeu a sensibilidade baroreflexa. Além disso, as CTM-GW estimularam a atividade autonômica, simpática e parassimpática no coração. Observamos que o tratamento celular induziu uma regulação da expressão do receptor alfa7nAChR e TLR4 no baço e no coração, assim como a redução da relação p-STAT3TYR705 e STAT3 total no baço. Outros efeitos importantes e adicionais foram a diminuição da infiltração de leucócitos e a regulação das citocinas pró-inflamatórias pelas células. O bloqueio da VCA usando MLA confirmou que o receptor alfa7nAChR pode ser um provável alvo, chave da ação das CTM entre vários outros mecanismos envolvidos na resposta imune. Finalmente, as CTM-GW conseguiram reduzir a apoptose no pulmão e no baço independentemente da VAC reforçando o conceito de que as células-tronco tem efeitos diversos além da imuno-regulação. Em conclusão, as CTM-GW na sepse foram capazes de atenuar a lesão cardiopulmonar assim como modular a atividade autonômica, reduzindo a inflamação sistêmica, pelo menos em parte, através da via colinérgica anti-inflamatória. Indubitavelmente todos estes efeitos anteriormente descritos e em associação se demonstraram fundamentais no mecanismo de reparo e proteção tecidual em resposta a sepse. Mais estudos pré-clínicos e futuros testes clínicos precisam ser realizados para maior compreensão destes mecanismos bem como uma possível validação terapêutica / Sepsis induces organ dysfunction due to overexpression of the inflammatory host response, involving cardiorespiratory and autonomic dysregulation, thus increasing the associated morbidity and mortality. The cholinergic anti-inflammatory pathway (CAP) is mediated by nervous system through alpha7 nicotinic acetylcholine receptor (alpha7nAChR). This receptor has an important role in systemic inflammation control. Wharton\'s jelly-derived mesenchymal stem cells (WJ-MSCs) are known to express genes and secreted factors related to neurological and immunological protection, as well as to improve survival in experimental sepsis. We hypothesized that WJ-MSCs play a modulatory role through the CAP and attenuate sepsis-induced organ injury in a cecal ligation and puncture (CLP) model. Rats were randomly divided into 4 groups: 1) Control (sham-operated); 2) submitted to CLP without treatment; 3) submitted to CLP and treated with 106 WJ-MSCs 6 h later and 4) CLP+MLA+WJ-MSC group (MLA: Methyllycaconitine, alpha7nAChR antagonist). All experiments were performed 24 h post-surgery. Echocardiographic parameters and heart rate variability were assessed. Importantly, treatment with WJ-MSCs attenuated diastolic heart failure and recovered barorreflex sensitivity. Moreover, WJ-MSCs injection increased cardiac sympathetic and cardiovagal activity. In cardiac and splenic tissue, WJ-MSC treatment downregulated TLR4 and alpha7nAChR expression, as well as it reduced p-STAT3/Total STAT3 ratio in the spleen. In addition, WJ-MSC reduced leukocyte infiltration and pro-inflammatory cytokines, which only were abolished by MLA treatment. Finally, WJ-MSC treatment diminished apoptosis in lung and spleen tissue. Together these findings suggest that treatment with WJ-MSCs appears to protect against sepsis-induced organ injury reducing systemic inflammation, at least in part, through cholinergic anti-inflammatory pathway

O diabetes mellitus do tipo 1 (T1D) é uma doença autoimune mediada por células T e caracterizada pela destruição seletiva das células ? pancreáticas produtoras de insulina. Células estromais mesenquimais (MSCs) e células tronco hematopoéticas (HSCs) são os principais componentes do nicho hematopoético na medula óssea. Estas células vêm sendo utilizadas nos últimos anos em transplantes autólogos para tratamento do T1D. O objetivo geral do presente trabalho foi avaliar o perfil de expressão gênica global de MSCs e HSCs de pacientes com T1D e compará-lo com células isoladas de indivíduos saudáveis através da técnica de microarray e programas específicos de bioinformática. As MSCs e HSCs foram isoladas da medula óssea de pacientes com T1D antes e após o tratamento com imunossupressão em altas doses seguida pelo transplante autólogo de células tronco hematopoéticas (AHSCT). As MSCs apresentaram valor elevado de expressão absoluta de diversas moléculas potencialmente relacionadas com suas funções de suporte à hematopoese. MSCs de pacientes diabéticos apresentaram perfil de expressão gênica global distinto das isoladas de indivíduos saudáveis, com hiper-regulação da sinalização via proteína G e hiporregulação da atividade transcricional. O receptor ?3 adrenérgico, assim como a sinalização simpática, foram hiper-expressos nas células dos pacientes. Genes que codificam moléculas que suportam a hematopoese e regulados pelo sistema nervoso simpático, VCAM1 e CXCL12, foram hiporregulados em nossa análise. Após o AHSCT, houve atenuação do perfil de expressão diferencial das MSCs dos pacientes, entretanto elas permaneceram com hiperatividade da sinalização via proteína G e déficit da atividade transcricional. As HSCs apresentaram altos níveis de expressão absoluta de diversas integrinas e receptores de citocinas e fatores de crescimento, potencialmente relacionados com funções na hematopoese. HSCs de pacientes com T1D apresentaram perfil de expressão gênica global distinto das de indivíduos saudáveis, com hiper-regulação de genes associados com a atividade transcricional. Os fatores de transcrição TCFL2 e p53, que têm papel fundamental na regulação do ciclo celular das HSCs, foram diferencialmente expressos entre as HSCs de pacientes diabéticos e controles. Assim, nossos resultados de expressão gênica global apontaram alterações intrínsecas nas HSCs e MSCs de pacientes diabéticos que podem estar relacionadas com a falha terapêutica dos transplantes autólogos. A implicação dessas alterações no desenvolvimento e patogênese do T1D permanece desconhecida e a realização de ensaios funcionais poderá esclarecer o significado biológico das mesmas. / Type 1 diabetes mellitus (T1D) is a T cell-mediated autoimmune disease, characterized by selective destruction of insulin-producing pancreatic ? cells. Mesenchymal stromal cells (MSCs) and hematopoietic stem cells (HSCs) are the main components of hematopoietic niches. In the last years, these cells are being used in autologous transplantation settings for T1D treatment. The main goal of this study was to evaluate the global gene expression profile of MSCs and HSCs from T1D patients, by using microarrays and bioinformatics specific programs. MSCs and HSCs were isolated from bone marrow of T1D patients before and after treatment with high dose immunossupression followed by hematopoietic stem cell transplantation. MSCs showed high absolute expression values of several molecules potentially related to their function of hematopoiesis support. MSCs from T1D patients exhibited distinct gene expression profile from control MSCs and presented up-regulation of the G protein-coupled receptor signaling pathway and down-regulation of transcriptional activity. The ?3 adrenergic receptor, as well the sympathetic nervous system signaling were up-regulated on patient´s cells. Genes that codify molecules which support hematopoeisis and are regulated by the symphatic nervous system, VCAM1 and CXCL12, were downregulated on our analysis. After AHSCT, there was an attenuation of the differential expression profile of MSCs from T1D patients, however they remained with G proteincoupled receptor signaling pathway hyperactivity and transcriptional activity deficit. HSCs exhibited high absolute expression values of integrins, cytokine receptors and growth factors, molecules potencially related to hematopoietic functions. HSCs from T1D patients showed distinct expression profile from control HSCs and demonstrated up-regulation of genes related to transcriptional activity. The transcription factors TCFL2 and p53, which have important role in regulating HSC cycle, were differentially expressed between HSCs from T1D patients and controls. Thus, our global gene expression analysis has revealed intrinsic alterations on MSCs and HSCs from T1D patients that could be related to the autologous transplant therapeutic failures. The implications of these alterations on the development and pathogenesis of T1D remain unknown and functional assays could unravel their biological meaning.

A sepse causa uma alta taxa de mortalidade no mundo. A fisiopatologia da doença envolve uma rede complexa de mediadores inflamatórios que promovem a lesão de diversos tecidos, além de diversas alterações hemodinâmicas e disfunção do sistema nervoso autonômico (SNA). Assim sabe-se que o sistema nervoso cumpre um papel importante no controle da inflamação sistêmica mediante a via colinérgica anti-inflamatória (VCA) através do receptor nicotínico de acetilcolina alfa7 (alfa7nAChR). O uso das células-tronco mesenquimais (CTM) tem mostrado efeitos benéficos em diversos ensaios clínicos de doenças inflamatórias. Neste contexto, as células-tronco mesenquimais derivadas da geleia de Wharton do cordão umbilical (CTM-GW) tornam-se promissórias, uma vez que essas células são reconhecidas pela regulação da resposta imunológica, reparação neural, efeito anti-apoptose, assim como a melhora da sobrevida na sepse, em modelos experimentais. Nossa hipótese foi de que as CTM-GW poderiam cumprir um papel neuroimunomodulador através da VCA e atenuar a disfunção de múltiplos órgãos em um modelo animal de sepse de ligadura e punção do ceco (LPC). Inicialmente células da matriz do cordão umbilical foram isoladas e caracterizadas de acordo com o consenso internacional vigente. Ratos Wistar machos adultos foram subdivididos em grupos: 1) sham (operação simulada); 2) LPC; 3) LPC+CTM-GW (injetado 106 CTM-GW via intraperitoneal, i.p. 6 h após LPC) e 4) LPC+MLA+CTM-GW (MLA: Metillicaconitine, antagonista do alfa7nAChR, i.p., 5:30 h após LPC e 106 CTM-GW 6h após). Às 24 horas após LPC, foram avaliadas a função cardiovascular, hemodinâmica assim como os outros parâmetros. Interessantemente, o tratamento com CTM-GW na sepse atenuou a disfunção diastólica e protegeu a sensibilidade baroreflexa. Além disso, as CTM-GW estimularam a atividade autonômica, simpática e parassimpática no coração. Observamos que o tratamento celular induziu uma regulação da expressão do receptor alfa7nAChR e TLR4 no baço e no coração, assim como a redução da relação p-STAT3TYR705 e STAT3 total no baço. Outros efeitos importantes e adicionais foram a diminuição da infiltração de leucócitos e a regulação das citocinas pró-inflamatórias pelas células. O bloqueio da VCA usando MLA confirmou que o receptor alfa7nAChR pode ser um provável alvo, chave da ação das CTM entre vários outros mecanismos envolvidos na resposta imune. Finalmente, as CTM-GW conseguiram reduzir a apoptose no pulmão e no baço independentemente da VAC reforçando o conceito de que as células-tronco tem efeitos diversos além da imuno-regulação. Em conclusão, as CTM-GW na sepse foram capazes de atenuar a lesão cardiopulmonar assim como modular a atividade autonômica, reduzindo a inflamação sistêmica, pelo menos em parte, através da via colinérgica anti-inflamatória. Indubitavelmente todos estes efeitos anteriormente descritos e em associação se demonstraram fundamentais no mecanismo de reparo e proteção tecidual em resposta a sepse. Mais estudos pré-clínicos e futuros testes clínicos precisam ser realizados para maior compreensão destes mecanismos bem como uma possível validação terapêutica / Sepsis induces organ dysfunction due to overexpression of the inflammatory host response, involving cardiorespiratory and autonomic dysregulation, thus increasing the associated morbidity and mortality. The cholinergic anti-inflammatory pathway (CAP) is mediated by nervous system through alpha7 nicotinic acetylcholine receptor (alpha7nAChR). This receptor has an important role in systemic inflammation control. Wharton\'s jelly-derived mesenchymal stem cells (WJ-MSCs) are known to express genes and secreted factors related to neurological and immunological protection, as well as to improve survival in experimental sepsis. We hypothesized that WJ-MSCs play a modulatory role through the CAP and attenuate sepsis-induced organ injury in a cecal ligation and puncture (CLP) model. Rats were randomly divided into 4 groups: 1) Control (sham-operated); 2) submitted to CLP without treatment; 3) submitted to CLP and treated with 106 WJ-MSCs 6 h later and 4) CLP+MLA+WJ-MSC group (MLA: Methyllycaconitine, alpha7nAChR antagonist). All experiments were performed 24 h post-surgery. Echocardiographic parameters and heart rate variability were assessed. Importantly, treatment with WJ-MSCs attenuated diastolic heart failure and recovered barorreflex sensitivity. Moreover, WJ-MSCs injection increased cardiac sympathetic and cardiovagal activity. In cardiac and splenic tissue, WJ-MSC treatment downregulated TLR4 and alpha7nAChR expression, as well as it reduced p-STAT3/Total STAT3 ratio in the spleen. In addition, WJ-MSC reduced leukocyte infiltration and pro-inflammatory cytokines, which only were abolished by MLA treatment. Finally, WJ-MSC treatment diminished apoptosis in lung and spleen tissue. Together these findings suggest that treatment with WJ-MSCs appears to protect against sepsis-induced organ injury reducing systemic inflammation, at least in part, through cholinergic anti-inflammatory pathway

Currently, in most situations, the autologous immune system is unable to eradicate the residual leukemic burden persisting after chemo-radiotherapy, but a balance can be established between leukemic and immune cells leading to a clinical remission for several months or years. If this balance is broken, a clinical relapse can occur. The high incidence of relapses in human cancers demonstrates the frequent inefficacy of the immune system to control these residual cells. In this context, allogeneic hematopoietic stem cell transplantation (HSCT) has been proven to be the most effective way to reinforce the immune reaction against leukemia, graft-versus-leukemia (GVL) effect and, so, achieve a definitive eradication of the residual disease in a significant proportion of patients. Indeed, the whole concept of HSCT evolved from an organ transplant concept (to replace a defective ill organ with a new healthy one) to the concept of creating an extraordinary immunotherapeutic platform in which the donor immune system contributes to the eradication of the residual leukemic cells. Thus, the past and present issues remain those of finding the best immunomodulatory modalities to achieve a full engraftment, a powerful GVL effect and no or moderate graft-versus-host disease (GVHD). Different ways to reach this goal, such as post transplant cytokine modulation, specific or global cellular depletion of the graft and post transplant global or specific donor immune cell add-backs, are still extensively studied. Nevertheless, the persistent high relapse rate (RR) observed in leukemia patients after HSCT remains the most important cause of death before transplant-related toxicities. Moreover, since only about 40 to 70% (depending on the ethnic context) of patients with high-risk hematological malignancies, eligible for allogeneic HSCT, have a fully HLA-matched sibling or matched unrelated donor (MUD), a great deal of effort has been invested to make the use of an alternative haploidentical sibling donor feasible. The advantage of this procedure is the immediate availability of a donor for almost all patients. <p>The aim of the work described in this thesis has been to implement a strategy to transplant a patient using a HLA haploidentical donor. The strategy is to try to improve DFS that could be applied both in the autologous or allogeneic context: first, by using nonspecific immune manipulation post transplant and then, by developing specific strategies directed against leukemia antigens. Particularly in the allogeneic situation, the aim was to increase the GVL effect without inducing or aggravating the deleterious GVHD. The first part of this thesis described our own clinical results, consisting of three consecutive phase I/II studies, in which we tried to determine the feasibility of giving prophylactic donor lymphocyte infusions (DLI) post transplant and the effect of replacing granulocyte colony-stimulating factor (G-CSF), typically used to speed up neutrophil recovery, with granulocyte macrophage colony-stimulating factor (GM-CSF), which is known for its immunomodulatory properties. The slow immune reconstitution in haploidentical transplant is chiefly responsible for the high incidence of early lethal viral and fungal infections, and most probably for early relapses; therefore, we sought to accelerate and strengthen the post transplant immune reconstitution without increasing the GVHD rate. Thus, we have studied the impact of post transplant growth factor administration and of unselected DLI in haploidentical transplant. We have also implemented, in our center, anti-cytomegalovirus (CMV) specific T cell generation and infusion to improve anti-CMV immune reconstitution. Since then, our results have been pooled in a multi-center analysis performed by the European Bone Marrow Transplantation group (EBMT) allowing us to compare our results with those of the entire group. We have also participated in the design of an ongoing study aimed at selectively depleting the graft from alloreactive T cells, and improving post transplant T cell add-backs. In our attempts to generate and expand ex vivo lymphocytes (directed against pathogens (CMV) and leukemia-associated antigens, Wilms' tumor gene 1 (WT1) and to use them in vivo, we found inconsistent results (in the case of WT1) using classical clinical grade dendritic cells (DC) generated and matured in bags, as was the case for the majority of the teams worldwide. This led us to question the full functionality of these DC and we undertook a thorough comparative analysis of DC generated and differentiated in bags and in plates (typical for most pre-clinical studies). This analysis showed us that one cannot transpose pre-clinical studies (using culture plates) directly to clinical protocols (generally using clinical grade culture bags) and that DC generated in bags are functionally deficient. We learned that, if we want to use a DC vaccine to improve the GVL effect in haploidentical transplant, we will have to be careful about the technique by which they are generated. To improve immunotherapeutic approaches, the understanding of the mechanisms underlying tumor tolerance and how to manipulate them is critical in the development of new effective immunotherapeutic clinical trials. This is why we currently focus on how to obtain effective in vivo anti-leukemia immune reactions using an ex-vivo manipulated product to trigger the immunotherapeutic response. More specifically, we are analyzing the impact of regulatory T cell (Tregs) depletion and function for an adequate anti-leukemic immune response. This pre-clinical work aims at improving the outcome of leukemia patients who have relapsed and been put back into second remission and at decreasing the RR after HSCT, especially in the field of haploidentical transplantation. <p>In conclusion, haploidentical transplantation has become a valuable tool. The results are at least similar to those obtained using MUD when performed in the same group of patients. Specific immunomodulation post transplant can affect events such as GVHD and GVL, but clinically we are still at the level of nonspecific manipulations. It is our hope that ongoing pre-clinical work will enable us to perform specific anti-pathogen and anti-leukemia immune manipulation that will favorably influence the patient outcome.<p>/<p><p>Dans la majorité des situations, le système immunitaire autologue est incapable d’éradiquer les cellules leucémiques résiduelles qui échappent à la radiothérapie et à la chimiothérapie, cependant un équilibre peut s’établir entre les cellules leucémiques et immunitaires aboutissant à une rémission pouvant durer plusieurs mois ou années. Si cet équilibre se rompt, une rechute clinique peut se déclarer. Dans ce contexte, il est prouvé que la greffe allogénique de cellules souches hématopoïétiques est le moyen le plus efficace de renforcer les réactions immunitaires contre la leucémie par la réaction du greffon contre la leucémie et ainsi d’obtenir une éradication définitive de la maladie résiduelle chez un nombre significatif de patients. En effet, le concept global de l’allogreffe de cellules souches hématopoïétiques a évolué du concept de transplantation d’organe (remplacement d’un organe malade par un nouvel organe sain) vers celui de créer une extraordinaire plateforme d’immunothérapie à travers laquelle le système immunitaire du donneur contribue à l’éradication des cellules leucémiques persistantes. Donc, la problématique reste celle de trouver les meilleures modalités d’immunomodulation pour achever une prise du greffon, un effet anti-leucémique puissant du greffon, et l’absence ou un minimum d’effet du greffon contre l’hôte. Différentes stratégies existent pour atteindre cet objectif, comme l’utilisation de cytokines pour moduler la reconstitution immunitaire, des déplétions cellulaires globales ou spécifiques du greffon et l’infusion de cellules immunes «globales» ou spécifiques du donneur après greffe. Ces stratégies sont encore largement à l’étude. Néanmoins, la persistance d’un taux de rechute élevé observé chez les patients leucémiques, après allogreffe reste la cause principale de décès, avant celle liée à la toxicité de la greffe. De plus, étant donné que seulement environ 40 à 70% (dépendant de l’origine ethnique) des patients avec une hémopathie à haut risque, éligibles pour une greffe allogénique, ont un donneur familial ou non familial complètement HLA compatible, des efforts importants ont été développés pour rendre faisable l’utilisation de donneurs familiaux alternatifs, haploidentiques. L’avantage de cette approche est l’accès immédiat à un donneur pour quasiment tous les patients.<p>Le but du travail décrit dans cette thèse a été l’implémentation d’une stratégie d’allogreffe utilisant un donneur haploidentique. Le travail vise également à développer de façon plus large des stratégies qui peuvent améliorer le taux de survie sans rechute, non seulement dans le contexte des greffes haploidentiques, mais également dans le cadre des greffes allogéniques en général, ainsi que dans les situations autologues :premièrement, par la manipulation immunitaire non spécifique après greffe et ensuite par le développement de stratégies spécifiques dirigées contre des antigènes leucémiques. En particulier dans la situation allogénique, le but a été d’augmenter l’effet du greffon contre la leucémie sans induire ou aggraver l’effet délétère du greffon contre l’hôte. La première partie de la thèse décrit les résultats cliniques de notre propre protocole de greffe haploidentique, qui a consisté en trois études consécutives de phase I/II. Dans ces études, nous avons voulu déterminer la faisabilité de réaliser des infusions prophylactiques de lymphocytes du donneur après transplantation, et l’impact du remplacement du « granulocyte colony-stimulating factor » (G-CSF), largement utilisé pour permettre une récupération en polynucléaires neutrophiles plus rapide, par du « granulocyte-macrophage colony-stimulating factor » (GM-CSF), lequel est connu pour ses propriétés immunomodulatrices différentes. La reconstitution immunitaire très lente après greffe haploidentique est majoritairement responsable de l’incidence élevée de décès par infections virales et fungiques précoces, et très probablement des rechutes précoces. C’est pourquoi nous avons cherché à accélérer et à renforcer la reconstitution immunitaire post-greffe sans augmenter la fréquence de réaction du greffon contre l’hôte. Nous avons donc étudié l’impact de l’administration de facteurs de croissance et l’infusion de lymphocytes non sélectionnés du donneur en post greffe haploidentique. Nous avons également implémenté dans notre centre, la génération et l’infusion de lymphocytes T spécifiques anti-cytomégalovirus (CMV) afin d’améliorer la reconstitution immunitaire anti-CMV. D’autre part, nos résultats ont été regroupés dans une étude multicentrique menée par le groupe européen de transplantation de moelle osseuse (EBMT), ce qui nous a permis de comparer nos résultats avec ceux de l’entièreté du groupe. Nous avons parallèlement participé à la conception d’une étude actuellement en cours ayant pour but d’améliorer la reconstitution immunitaire après greffe par la déplétion sélective du greffon en lymphocytes T alloréactifs et par l’infusion après greffe de lymphocytes T du donneur également sélectivement déplétés en lymphocytes T alloréactifs. Afin d’optimaliser l’effet anti-leucémique du système immunitaire, nous avons débuté un protocole de vaccination par cellules dendritiques (DCs). Ces cellules dendritiques étaient chargées en lysat de blastes leucémiques dans le cas de patients présentant au diagnostic une leucémie aigue surexprimant l’oncogène 1 de la tumeur de Wilms (WT1). Néanmoins dans nos travaux de génération et d’expansion ex-vivo de lymphocytes T spécifiques de l’antigène WT1, utilisant les DCs de grade clinique, générées et maturées en poches, nous avons rencontré des résultats inconsistants, comme c’était le cas dans la majorité des protocoles cliniques internationaux de vaccination. Nous nous sommes alors posé la question de la fonctionnalité globale de ces cellules et nous avons entrepris une analyse comparative poussée des DCs générées et différenciées en poches ou en plaques. Les DCs générées en plaques sont celles utilisées dans la plupart des travaux précliniques. Cette analyse nous a montré que l’on ne pouvait pas directement transposer les résultats précliniques basés sur des DCs générées en plaques dans des protocoles cliniques basés sur des DCs générées en poches, car ces dernières présentent des déficits fonctionnels importants. Nous avons appris que si l’on voulait utiliser un vaccin à base de cellules dendritiques pour améliorer l’effet du greffon contre la leucémie dans les greffes allogéniques, nous devions être très attentifs quant au protocole utilisé pour la génération de ces vaccins cellulaires. Pour améliorer les approches immunothérapeutiques, la connaissance des mécanismes qui établissent la tolérance tumorale et des façons de manipuler ceux-ci, est critique dans le développement de nouveaux protocoles efficaces. C’est pourquoi nous nous concentrons actuellement sur les conditions nécessaires à l’obtention in vivo d’une réaction immune anti-leucémique efficace lors de l’utilisation d’un produit cellulaire manipulé ex vivo. Plus spécifiquement, nous analysons l’impact de la déplétion en lymphocytes T régulateurs (Tregs) sur la réponse anti-leucémique. Ce travail préclinique a pour but d’améliorer le devenir de patients leucémiques qui ont rechutés et ont été mis en seconde rémission, ainsi que de diminuer le taux de rechute après allogreffe, spécifiquement après greffe haploidentique. <p>En conclusion, la transplantation haploidentique est actuellement un outil précieux pour de nombreux patients. Les résultats sont au minimum similaires à ceux qui sont obtenus par les greffes non-familiales HLA identiques lorsqu’elles sont pratiquées dans les mêmes groupes de patients. L’immunomodulation spécifique après greffe peut affecter des événements comme la réaction du greffon contre l’hôte et la réaction du greffon contre la leucémie, mais en pratique clinique nous en sommes encore au niveau de la manipulation aspécifique. Nous espérons que les travaux précliniques actuels vont nous permettre d’appliquer des stratégies spécifiques et d’obtenir une manipulation immune anti-leucémique qui aura une influence favorable significative sur le devenir des patients. / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Indiana University-Purdue University Indianapolis (IUPUI) / Graft-versus-host disease (GVHD) remains the major complication after allogeneic hematopoietic stem cell transplantation (HSCT), resulting from immunological attack on target organs such as gastrointestinal (GI) tract, liver and skin from donor allogeneic T cells. The most common treatment for GVHD is immunosuppressive drugs such as corticosteroids, which may result in many side effects including the loss of the beneficial graft-versus-leukemia (GVL) effect and increased infection rates. However, GVHD-specific drugs have yet to be implemented. Here we show that by targeting on a novel pathogenic CD4+ T cell subpopulation that our lab previously found in patients with GI GVHD, we can develop new avenues to treat GVHD. This novel population is characterized as CD146+CCR5+ T cells, co-expressing IL-17A and IFN-γ. We found that the inducible T-cell costimulator (ICOS), which has been reported to be important for human Th17 differentiation in vitro, is critical for the development of this nonconventional T Helper 1 (Th1*)-polarized CD146+CCR5+ conventional T cells (Tconvs) population. Furthermore, we found that ICOS can induce the generation of Th1*-polarized CD146+CCR5+ regulatory T cells (Tregs) population, lowering the frequencies of phenotypic markers of functional Tregs. Our data also showed that inhibiting the major transcriptional factor of Th17, RAR-related orphan receptor gamma t (RORγt), could prevent the development of CD146+CCR5+ Tconvs in vitro. Our results demonstrate how pathogenic CD146+CCR5+ T cells are induced through ICOS or RORγt, suggesting new targets for GVHD treatment. We anticipate our assay to be a starting point for the development of novel GVHD-specific drugs. For example, the treatments that focus on inhibiting RORγ would have fewer side effects than general immunosuppressive drugs that GVHD patients use today and inhibit GVHD while sparing the GVL effect. Furthermore, we expect the CD146+CCR5+ Tconvs and/or Tregs can be used as GVHD biomarkers. These biomarkers may guide preemptive treatments such as RORγt inhibitor.

Indiana University-Purdue University Indianapolis (IUPUI) / More than 300 million people world-wide suffer from breathlessness, wheezing, chest tightness, and coughing characteristic of chronic bronchial asthma, the global incidence of which is on the rise. Allergen-sensitization and challenge elicits pulmonary expression of chemoattractants that promote a chronic eosinophil-rich infiltrate. Eosinophils are increasingly recognized as important myeloid effectors in chronic inflammation characteristic of asthma, although few eosinophil molecular signaling pathways have successfully been targeted in asthma therapy. p21 activated kinases (PAKs), members of the Ste-20 family of serine/threonine kinases, act as molecular switches in cytoskeletal-dependent processes involved in cellular motility. We hypothesized that PAK1 modulated eosinophil infiltration in an allergic airway disease (AAD) murine model. In this model, Pak1 deficient mice developed reduced inflammatory AAD responses in vivo with notable decreases in eosinophil infiltration in the lungs and broncho-alveolar lavage fluids (BALF). To test the importance of PAK1 in hematopoietic cells in AAD we used complementary bone marrow transplant experiments that demonstrated decreased eosinophil inflammation in hosts transplanted with Pak1 deficient bone marrow. In in vitro studies, we show that eotaxin-signaling through PAK1 facilitated eotaxin-mediated eosinophil migration. Ablating PAK1 expression by genetic deletion in hematopoietic progenitors or siRNA treatment in derived human eosinophils impaired eotaxin-mediated eosinophil migration, while ectopic PAK1 expression promoted this migration. Together these data suggest a key role for PAK1 in the development of atopic eosinophil inflammation and eotaxin-mediated eosinophil migration.

Indiana University-Purdue University Indianapolis (IUPUI) / In the US, more than 1 million burn injuries are reported annually. About 45,000 injuries due to fires and burns result in hospitalization and ten percent of these result in death every year. Advances in burn treatment have led to a reduction in mortality rate over the last decades. Since more patients are surviving the initial resuscitation phase even with very large areas of skin being burned away, wound care has become increasingly important to ensure continued patient survival and improvement. While currently a common treatment for third degree burn wounds, skin grafts have several drawbacks. The availability of donor sites for autografts may be limited, especially in incidences of extensive skin loss. The rejection associated with the use of allografts and xenografts may render them inadequate or undesirable. Even if a suitable graft is found, poor retention due to infection, hematoma, and low vascularity at the recipient site are other drawbacks associated with the use of skin grafts as a primary treatment for severe burn wounds. As such, research has been done into alternative treatments, which include but are not limited to artificial skin, cell therapy, and growth factor application. We propose the delivery of adipose derived stem cells (ASC) in combination with endothelial progenitor cells (EC) via Integra Dermal Regenerative Template (DRT) to promote faster graft vascularization and thus faster healing of wounds. Integra DRT is an acellular skin substitute that consists of a dermal layer composed of bovine collagen and chondroitin-6-sulfate glycosaminoglycan, and an "epidermal" layer, which consists of silicone polymer. This silicone layer is removed after the collagen matrix is adequately vascularized (usually takes 2-3 weeks), and then a thin layer autograft is applied to the top of the neo-dermis. ASC are derived from the stromal-vascular fraction (SVF) of adipose tissue and are a readily available, pluripotent, mesenchymal cell known to promote angiogenesis. They are being explored as a treatment for a myriad of diseases and conditions, including wound healing. In combination with ECs, they form stable microvessel networks in vitro and in vivo. In our work, we found that ASC+EC form stable microvessel networks when cultured on Integra DRT. Also, ASC and ASC+EC conditioned media promoted both survival and migration of human epidermal keratinocytes compared to control medium. In a full thickness wound healing model, using healthy NSG mice, the ASC+EC case showed a significantly higher rate of wound closure compared to control. Based on best linear unbiased estimates (BLUE), the difference between the healing rates of ASC alone treatment and the Control treatment group is -0.45 +/- 0.22 mm²/day (p=0.041), which is not less than 0.025 and thus not statistically significant (Bonferroni Adjusted). However, the BLUE for the difference between the ASC+EC group and the Control group healing rates is -0.55 +/- 0.28 mm²/day (p = 0.017<0.025, Bonferroni Adjusted), which is statistically significant. Histology revealed a significantly higher number of vessels compared to control in both ASC alone and ASC+EC case. CD31 staining revealed the presence of human vessels in ASC+EC treatment scaffolds. We conclude that the combination of ASC and EC can be used to accelerate healing of full-thickness wounds when delivered to site of the wound via Integra. This result is especially compelling due to the fact that the mice used were all healthy. Thus our treatment shows an improvement in healing rate even compared to normal wound healing.