Thesis advisor: Kenneth C. Williams / Thesis advisor: Welkin Johnson / Neuropathogenesis of HIV-associated neurocognitive disorders (HAND) is likely instigated by chronic immune activation in response to residual infection in the central nervous system (CNS), where combined antiretroviral therapy (cART) has limited access. Monocyte/macrophages (Mo/Mϕ) constitute the predominant population of infected cells in the CNS and play a major role in HIV-induced neuropathogenesis. Emergence of compartmentalized HIV subpopulations in the brain corresponds with accumulation of HIV-infected Mo/Mϕ and is consistent with acquired immune deficiency syndrome (AIDS)-related neuropathology. We used a rhesus macaque model of neuroAIDS to elucidate the role of Mo/Mϕ in establishing CNS infection and the emergence of compartmentalized virus in the brain. To do this, we: 1) performed phylogenetic analysis of viral sequences from peripheral and CNS compartments and determined the incidence of Mo/Mϕ infection in CNS tissues to identify sources of CNS viral subpopulations that emerge with AIDS-related neuropathology; 2) optimized a method for obtaining single genome viral sequences from Mo/Mϕ populations extracted from tissues and 3) performed phylogenetic analysis of viral sequences from bone marrow (BM) and CNS Mo/Mϕ and determined the incidence of Mo/Mϕ infection in the BM to assess whether BM Mo/Mϕ are sources of infected Mo/Mϕ that accumulate in the CNS with AIDS-related neuropathology. We found that animals with AIDS-related neuropathology had a higher incidence of Mo/Mϕ infection and compartmentalized SIV subpopulations in CNS tissues compared to animals without neuropathology. Additionally, CSF virus, which is used to assess the presence of CNS virus compartmentalization in living patients, was not compartmentalized even with significant compartmentalization in the brain and severe AIDS-related neuropathology (Chapter 2). Relative to animals without CNS pathology, animals with AIDS-related neuropathology had a higher incidence of Mo/Mϕ infection in the BM and viral sequences from BM and CNS perivascular Mo/Mϕ clustered with sequences from trafficking monocytes and CNS tissues (Chapter 4). The results suggest that infected Mo/MΦ in CNS tissues are sources of compartmentalized virus and that infected Mo/Mϕ in the BM are sources of infected Mo/Mϕ that accumulate in the CNS with AIDS-related neuropathology. In summary, the data in this dissertation suggest that targeting Mo/Mϕ may prevent CNS infection and inflammation associated with HIV-induced neuropathogenesis. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.

Trichophyton rubrum, importante agente de dermatofitoses, é um fungo queratinofílico, capaz de parasitar tecidos como pele e unha. É o principal responsável pelas dermatofitoses crônicas e refratárias ao tratamento e como é uma espécie antropofílica encontra-se muito bem adaptado ao parasitismo humano. Por tratar-se de uma micose cutânea, torna-se necessário o estudo dos fenômenos que ocorrem durante o encontro deste fungo com uma das principais células do sistema imunológico que primeiramente reconhecem o antígeno. Assim sendo, o objetivo deste trabalho é estudar a interação de T.rubrum com macrófagos, para aumentar o conhecimento dos mecanismos envolvidos na resposta imunológica nesta importante patologia. Para isso, foram realizados ensaios de fagocitose de conídios de T.rubrum, seguidos da análise da expressão de moléculas de superfície celular, dosagem de citocinas e viabilidade de macrófagos. Verificamos que o exoantígeno de T.rubrum provocou diminuição da fagocitose de conídios e partículas de zymosan pelos macrófagos. Entretanto, o exoantígeno não interferiu na expressão de moléculas de superfície celular e não foi capaz de estimular os macrófagos a secretar TNF-α, IL-12, IL-10 e óxido nítrico. Já os conídios fagocitados por macrófagos, provocaram diminuição significativa na expressão de suas moléculas de superfície, tais como MHC classe II, CD80 e CD54. Após fagocitose de conídios, os macrófagos foram capazes de secretar uma grande quantidade de TNF-α e IL-10 e após 8 horas de cultivo, os conídios internalizados iniciaram processo de formação de hifa, provocando lise e a conseqüente morte destas células. Por estes achados e pelos estudos prévios já realizados com o T.rubrum, pensamos que a persistência desta infecção fúngica possa estar relacionada com a ação inibitória do fungo sobre os macrófagos, levando à cronicidade observada nestas lesões. / Trichophyton rubrum is the most common pathogen causing dermatophytosis, accounting for approximately 80% of the reported cases of onychomycosis. Since 90% of the chronic dermatophyte infections are caused by T. rubrum, it is likely that this pathogen must have evolved mechanisms that evade or suppress cell-mediated immunity. Several reports have highlighted the participation of phagocytes in the immune defense against fungi; however, few studies have addressed the role of these cells in dermatophytosis. In this study, we investigated the interactions of resident and peritoneal macrophages with T. rubrum. We show here that the interaction of T. rubrum conidia with resident macrophages results in the production of TNF-α and IL-10 but not IL-12 and nitric oxide. Infected macrophages down-regulated the expression of co-stimulatory molecules (CD80 and CD54). We also show that phagocytosis of T. rubrum conidia is inhibited by the addition of fungal exoantigens or mannan. Cytotoxicity assays indicated that after 8 h of conidia ingestion macrophage viability decreased drastically. Electron microscopy revealed that the ingested conidia grow and differentiate into hyphae inside macrophages leading to rupture of the macrophage membrane.

University of Macau / Institute of Chinese Medical Sciences

A síntese de melatonina por fagócitos mononucleares do colostro humano é iniciada após a indução com a partícula zimosan, com ou sem opsonização por IgA. Esta produção é dependente da ativação da via NFKB, o que foi observado após o bloqueio farmacológico da via com PDTC ou ALLN levando a diminuição da concentração de melatonina nas culturas. A localização do NFKB varia temporalmente após o estímulo inicial e as subunidades do NFKB são diferentes no núcleo de células ativadas. A subunidade p50 está presente em todas as condições experimentais (controle, zimosan e zimosan opsonizado), mas as subunidades Rel A e c-Rel apenas nas células tratadas. A melatonina apresenta atividade sobre células imunocompetentes em diversos modelos experimentais, mas o modelo de fagocitose ainda não havia sido relatado na literatura. Observamos que a melatonina é capaz de potenciar a fagocitose de zimosan não opsonizado. A capacidade de síntese de melatonina apresentada por células imunocompetentes é um fenômeno conhecido e agora pudemos demonstrar que a via NFKB é responsável também pela síntese de melatonina em fagócitos mononucleares do colostro. Ao contrário do que ocorre na glândula pineal onde a ativação da via do NFKB bloqueia a síntese de melatonina, nos leucócitos, a ativação desta via se faz necessária para o inicio da síntese. Uma possível justificativa para esta diferença é a presença da subunidade c-Rel apenas nos fagócitos, permitindo supor que esta subunidade seja responsável pela síntese de melatonina nestas células. Hipoteticamente, a síntese de melatonina dependente da ativação de um fator envolvido com a resposta inflamatória, abre a perspectiva de que a melatonina estaria participando deste processo. O aumento na taxa de fagocitose induzida pela melatonina mostra uma participação importante dessa indolamina durante uma infecção, diminuindo o tempo em que um possível patógeno se encontraria no meio extracelular auxiliando na sua rápida eliminação. Os dados apresentados no presente trabalho demonstram que as células imunocompetentes não apenas produzem esta indolamina, como também se utilizam dela para modular processos nos quais estas células participam. / The melatonin synthesis by human mononuclear phagocytes starts after the induction by IgA opsonized or not zymosan. This production is dependent on the activation of NFKB pathway since the pharmacological block of the pathway by PDTC or ALLN reduces the melatonin concentration in culture supernatants. The NFKB localization temporally varies after initial stimulus and the presence of specific subunits in the cell nucleus is different in activated cells when compared with control cells. We observed the presence of p50 subunit in all experimental conditions (control, zymosan, opsonized zymosan), but the Rel A and c-Rel subunits were only detected in treated cells. Melatonin shows activity over immune cells in many experimental models, but the phagocytosis model was not yet reported in literature. We observed that melatonin (1 nM) is able to potentiate the non opsonized zymosan phagocytosis. The capacity to synthesize melatonin presented by immune cells is a well known phenomenon and now we demonstrate that the NFKB pathway is also responsible for the melatonin synthesis in colostral mononuclear phagocytes. The activation of NFKB pathway inhibits the melatonin synthesis in pineal gland but, in leukocytes, the activation of this pathway is necessary to achieved melatonin synthesis. A possible explanation for this difference is the presence of c-Rel in the phagocytes, which presents transactivation domains, allowing the supposition that this subunit is the responsible for melatonin synthesis in these cells. Since, melatonin synthesis is dependent on the activation of a factor involved with an inflammatory response, this study opens the perspective that the melatonin could participate as a modulator of this process. The phagocytosis induced by melatonin discloses a significant role of this indolamine during an infection, promoting the fast elimination of pathogen in the extracellular medium. The data shows that immune cells not only produces this indolamine, but also use the melatonin to modulate the immune responses.

by Chan Yee Man Elaine. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 130-143). / Abstract --- p.I / Acknowledgements --- p.III / Abbreviations --- p.IV / Objectives of the study --- p.VII / Table of Contents --- p.VIII / Chapter Section 1 --- Introduction --- p.1 / Chapter 1.1 --- Necrosis vs Apoptosis --- p.2 / Chapter 1.2 --- Cell Death by Apoptosis --- p.4 / Chapter 1.3 --- The Biochemistry of Nitric Oxide --- p.9 / Chapter 1.4 --- Mechanisms of NO Action --- p.14 / Chapter 1.5 --- Signal Transduction Pathways to Apoptosis --- p.17 / Chapter 1.5.1 --- Regulation by Ca2+ --- p.17 / Chapter 1.5.2 --- Protein Kinase C --- p.20 / Chapter 1.5.3 --- cAMP --- p.21 / Chapter 1.5.4 --- Protein tyrosine kinase --- p.21 / Chapter 1.5.5 --- Ceramide --- p.22 / Chapter 1.5.6 --- pH --- p.23 / Chapter 1.5.7 --- Oxygen Radicals --- p.23 / Chapter 1.5.8 --- Anchorage Dependence and Extracellular Matrix --- p.24 / Chapter Section 2 --- Materials and Methods --- p.27 / Chapter 2.1 --- Materials --- p.28 / Chapter 2.1.1 --- Animal --- p.28 / Chapter 2.1.2 --- Cell line --- p.28 / Chapter 2.1.3 --- "Culture media, buffers and chemicals" --- p.28 / Chapter 2.1.4 --- Dye solutions --- p.30 / Chapter 2.1.5 --- Reagents and buffers for polyacrylamide gel electrophoresis (PAGE) --- p.31 / Chapter 2.1.6 --- Reagents and buffers for Western blotting --- p.32 / Chapter 2.1.7 --- Reagents and buffers for agarose gel electrophoresis --- p.33 / Chapter 2.2 --- Methods --- p.35 / Chapter 2.2.1 --- Cell culture --- p.35 / Chapter 2.2.2 --- [3H]-Thymidine incorporation --- p.35 / Chapter 2.2.3 --- MTT assay --- p.36 / Chapter 2.2.4 --- Determination of NO by Griess assay --- p.36 / Chapter 2.2.5 --- Observation of apoptotic morphology of cells by confocal laser scanning microscopy (CLSM) --- p.37 / Chapter 2.2.6 --- Determination of cell death induced by NO producing drugs --- p.38 / Chapter 2.2.7 --- Determination of cell death induced by Concanavalin A --- p.38 / Chapter 2.2.8 --- Determination of effect of nitric oxide synthase (NOS) inhibitor on cell death induced by Con A --- p.39 / Chapter 2.2.9 --- Determination of the requirement of Ca2+ in cell death induced by NO producing drugs --- p.39 / Chapter 2.2.10 --- Determination of the requirement of cGMP in cell death induced by NO producing drugs --- p.40 / Chapter 2.2.11 --- Determination of cell death induced by PKC activation and depletion --- p.40 / Chapter 2.2.12 --- Determination of effect of PKC depletion on cell death induced by NO producing drugs and Con A --- p.41 / Chapter 2.2.13 --- Observation of immunofluorescence by confocal laser scanning microscopy --- p.41 / Chapter 2.2.14 --- Preparation of protein samples for PAGE --- p.42 / Chapter 2.2.15 --- Polyacrylamide gel electrophoresis --- p.43 / Chapter 2.2.16 --- Western blotting of PKC --- p.44 / Chapter 2.2.17 --- Preparation of DNA samples from cells --- p.46 / Chapter 2.2.18 --- Agarose gel electrophoresis of DNA --- p.47 / Chapter 2.2.19 --- Statistical analysis --- p.48 / Chapter Section 3 --- Results --- p.49 / Chapter 3.1 --- Induction of apoptosis in macrophages by NO producing drugs --- p.50 / Chapter 3.2 --- Apoptosis induced by NO producing drugs was caused by NO --- p.54 / Chapter 3.3 --- Signal transduction pathways to the NO-induced cell death in macrophages --- p.66 / Chapter 3.3.1 --- Calcium ion --- p.66 / Chapter 3.3.2 --- cGMP --- p.68 / Chapter 3.3.3 --- Protein kinase C --- p.71 / Chapter 3.4 --- Induction of apoptosis by Con A --- p.89 / Chapter 3.5 --- Tubulin structure in Con A-treated cells --- p.94 / Chapter 3.6 --- Nitric oxide and Con A-induced cell death in macrophages --- p.96 / Chapter 3.7 --- Effect ofNOS inhibitor on cell death induced by Con A --- p.102 / Chapter 3.8 --- Involvement of PKC in the Con A-induced cell death in macrophages --- p.106 / Chapter Section 4 --- Discussion --- p.114 / Chapter 4.1 --- Induction of apoptosis in macrophages by NO producing drugs --- p.118 / Chapter 4.2 --- Signal transduction pathways to the NO-induced cell death in macrophages --- p.120 / Chapter 4.2.1 --- Ca2+ ion --- p.120 / Chapter 4.2.2 --- cGMP --- p.120 / Chapter 4.2.3 --- Protein kinase C --- p.121 / Chapter 4.3 --- Induction of apoptosis by Con A --- p.124 / Chapter 4.4 --- Tubulin structure in Con A-treated cells --- p.124 / Chapter 4.5 --- Nitric oxide and Con A-induced cell death --- p.125 / Chapter 4.6 --- Effect ofNOS inhibitor on cell death induced by Con A --- p.125 / Chapter 4.7 --- Involvement of PKC in the Con A-induced cell death in macrophages --- p.127 / Chapter Section 5 --- Bibliography --- p.129 / References --- p.130

By serial subcultivation on media containing egg-white lysozyme a highly resistant variant of M. lysodeikticus bacteriophage was selected. The parent strain was sensitive to 0.1 pg per ml. lysozyme while the variant was resistant to 4000 pg per ml. The two strains were examined in detail and it was found that the resistant strain differed genotypicelly from the sensitive strain in its ability to acetylate certain cell wall hydroxyl groups. This was the sole reason for lysozyme resistance. It was found that deacetylation of the resistant strain by ample chemical treatment restored its sensitivity to lysozyme while acetylation of the sensitive strain rendered it resistant.

Convincing evidence that activated macrophages play a critical role in control of mycobacterial diseases has been clearly established from animal and in-vitro studies. Macrophages produce a variety of molecules upon appropriate stimulation, which act in concert towards eventual killing of bacteria. People with SUb-optimal macrophage activation are more susceptible to infection with intracellular pathogens. My project aims to answer two questions relating to genetic regulation of macrophage activation in tuberculosis: do macrophage genes regulate microbial-induced responses and do macrophage genes influence susceptibility to tuberculosis? A whole blood assay was used to investigate IFN-y responsiveness in healthy individuals and those who develop tuberculosis in The Gambia. Cytokine responses to lipopolysaccaride (LPS), Lipoarabinomanan (LAM) and the enhancing effect of IFN-y on these stimulants were measured. LPS induced IL-l 0 levels was higher in recovered TB cases than in controls (p=0.02). LPS and LAM induced cytokines were highly correlated (p<0.0001) similarly, levels of IL-IB and TNF were highly correlated (P<O.OOOl). Ten new polymorphisms were detected by sequencing specific regions within the promoter of IFNG and IFNGRI genes. One, a double deletion of TT in the promoter of IFNGR1, abolishes a GAS binding site at position -470 and another, a CIT transition, is close to a putative NF-kappa B binding site at position -56 in the IFNGRI gene (positions are relative to the transcription start site). These along with published polymorphisms at some macrophage candidate gene loci were genotyped. Comparisons were made to determine whether different alleles at candidate gene loci influence macrophage cytokine responses. TNFA-863 , LTA NeaL lL1RN and NRAMPl (469+14) polymorphisms were shown to influence macrophage cytokine levels significantly. TNFA-863 was associated with LPS induced TNF (P < 0.05), LTA was associated with LAM and LPS induced TNF and 1L-~ levels (p < 0.01). NRAMPI (469+14) was associated with LAM induced 1L-I0 (P<O.OI) and fL1RN was associated with LAM and LPS induced 1L-l 0 (P<0.05). Alleles 1 (G) of TNFA-308, 2 (A) of TNFA-238, 1 (T) of fL1B-511 and 2 (ddeVT) of fFNGR1 were significantly associated with TB in the panel of samples studied. For the microsatellite markers, allele 5 of fL9 (TG)n repeat in intron 4 and allele 3 of the Z DNA promoter polymorphism NRAMP 1, were significantly associated with TB. NRAMP 1 !NT 4 variant was significantly associated with both TB and LAM induced 1L-I0 secretion.

Red blood cell (RBC) transfusions are associated with adverse effects, such as an increased risk of bacterial infection. In preparing RBCs for transfusion, donor RBCs are refrigerator stored for extended periods of time, during which they undergo oxidative damage, ultimately leading to their rapid post-transfusion clearance from the circulation. Macrophages play important roles in recycling iron derived from the clearance of RBCs. They are also a critically important component of host defense, protecting against invading pathogens. However, the effects on macrophage biology of acutely ingesting large numbers of RBCs are not completely understood. To investigate this issue, we used a mouse model of RBC transfusion and clearance, which mimics the clinical setting. In this model, transfusions of refrigerator storage-damaged (i.e., “old”) RBCs led to increased erythrophagocytosis by splenic red pulp macrophages (RPMs). This robust erythrophagocytosis induced ferroptosis, an iron-dependent form of cell death, in RPMs. This was accompanied by increases in reactive oxygen species and lipid peroxidation in vivo, which were reduced by treatment in vitro with ferrostatin-1, a ferroptosis inhibitor. Old RBC transfusions also induced RPM-dependent chemokine expression by splenic Ly6Chi monocytes, which signaled Ly6Chi monocyte migration from bone marrow to spleen, where these cells subsequently differentiated into RPMs. The combination of cell division among remaining splenic RPMs, along with the influx of bone marrow-derived Ly6Chi monocytes, suggests that, following RPM depletion induced by robust erythrophagocytosis, there is a coordinated effort to restore homeostasis of the RPM population by local self-maintenance and contributions from circulating monocytes. However, the effects on the overall functioning of the splenic Ly6Chi monocytes and remaining RPMs are unclear, especially their responses to subsequent immune challenges. In a mouse model of RBC storage and transfusion, we found that, following a transfusion of old RBCs, macrophages were less capable of phagocytosing a subsequent particle stimulus, such as bacteria (i.e., Escherichia coli and Staphylococcus aureus) or additional old RBCs. However, splenic Ly6Chi monocytes became activated in a specific timeframe following the initial old RBC transfusion, thereby increasing their phagocytic capacity. Nonetheless, despite contributions from activated splenic Ly6Chi monocytes, RPM function was indispensable for clearing S. aureus; this functional impairment may make the transfusion recipient susceptible to S. aureus sepsis. In conclusion, these findings may be clinically relevant to pathological conditions that can arise as a result of increased erythrophagocytosis, such as transfusion-related immunomodulation and impaired host immunity.

Phagosome maturation is a dynamic process involving the engulfment and degradation of pathogens by phagocytic cells. However, several pathogens have employed mechanisms that facilitate their survival and escape from the phagosome. The fungal pathogen, Candida albicans, is capable of switching from yeast to hyphal form to facilitate its pathogenicity and escape from the phagosome. Rab GTPases are key regulators in phagosome maturation by mediating interactions with the endocytic pathway and leading to biogenesis of the phagolysosome. The temporal localisation dynamics of Rab2 on maturing phagosomes containing live C. albicans was investigated. Live-cell imaging revealed green fluorescent protein (GFP)-tagged Rab2 was recruited to C. albicans-containing phagosomes. Rab2 appeared on phagosomes within 2 min following complete engulfment of C. albicans. Rab2 persisted transiently on macrophage phagosomes and this correlated with the length of C. albicans hyphae at the time of uptake, suggesting C. albicans morphology modulates Rab2 localisation dynamics. Expression of dominant negative or dominant active Rab2 did not affect macrophage migration, the rate of engulfment or phagosome acidification during the early stages of phagosome maturation. Furthermore, altered expression of Rab2 did not interfere with C. albicans ability to escape from and kill macrophages, suggesting Rab2 is not involved in the outcome of the host-pathogen interaction. However, altered expression of Rab2 reduced the acquisition of the late-stage phagosome maturation markers, cathepsin B and LAMP1, suggesting Rab2 impacts upon phagosome-lysosome fusion. Finally, the uptake of other particles by macrophages revealed Rab2 recruitment, as well as localisation dynamics on phagosomes, may be cargo-dependent. Through the use of live-cell imaging, real-time dynamics of phagosome biogenesis in live cells was examined, offering unique insight at the host-pathogen interface.

Les espèces de la famille des Mycobacteriaceae sont caractérisées par une enveloppe bactérienne épaisse, riche en lipides, de structures uniques, connus pour être d'importants immunomodulateurs. Les mycobactéries sont majoritairement non pathogènes et sont rapidement éliminées par le système immunitaire de l'hôte. Cependant, certaines espèces causent des pathologies graves pour l'homme. Parmi ces espèces, M. tuberculosis, agent étiologique de la tuberculose ou M. abscessus, pathogène opportuniste responsable de mycobactérioses chez les patients immunodéprimés, sont capables d'échapper aux mécanismes fondamentaux du système immunitaire afin de se maintenir au sein des macrophages. Parmi ces mécanismes, l'autophagie, processus cellulaire de dégradation de composants cytoplasmiques par les lysosomes, est impliquée dans l'immunité anti-mycobactérienne en limitant la multiplication intracellulaire des mycobactéries. Les mécanismes moléculaires de l'activation de l'autophagie dans un contexte d'infection à mycobactérie et les mécanismes d'inhibition du processus mis en place par les mycobactéries pathogènes ou opportunistes sont partiellement caractérisés. Ainsi les objectifs principaux de ma thèse furent de (i) caractériser la réponse autophagique des macrophages suite à l'infection par trois espèces de mycobactéries, M. smegmatis (non pathogène), M. abscessus (opportuniste) et M. tuberculosis (pathogène) ; et (ii) de déterminer le rôle de deux facteurs de virulence lipidiques, les dimycocérosates de phthiocérols (DIM) et les sulfolipides (SL) dans la modulation du processus autophagique. Les résultats de ce travail de thèse ont permis (i) de caractériser un nouvel mécanisme d'induction de l'autophagie, ne reposant pas sur l'ubiquitination préalable de la mycobactérie et impliquant l'activation de la voie de signalisation des TLRs et, (ii) grâce à l'utilisation de différents mutants, de montrer que les lipides DIM, SL de M. tuberculosis et les glycopeptidolipides (GPL) de M. abscessus sont impliqués dans la limitation du processus autophagique au sein des macrophages. Ce travail de thèse met en évidence de nouveaux facteurs cellulaires et mycobactériens impliqués dans la régulation du processus autophagique, facteurs qui pourraient être des cibles potentielles dans le développement de vaccin ou de thérapies basées sur les défenses de l'hôte. / Mycobacteria are a large family of bacteria characterized by an atypical cell envelope rich in exotic lipids and glycoconjugates. Although most members of the mycobacteria family are non-pathogenic, a few members such as M. tuberculosis or M. abscessus are pathogenic or opportunistic for humankind. These mycobacteria cause diseases such as Tuberculosis or a wide array of infections in immunocompromised patients, and are able to escape fundamental mechanisms of macrophage innate immune responses. Amongst these mechanisms, autophagy, which is the selective engulfment of cytoplasmic components and degradation by lysosomes, contributes to anti-mycobacterial immunity by limiting the intracellular growth of mycobacteria. The molecular mechanism behind anti-mycobacterial autophagy and the strategies employed by pathogenic or opportunistic mycobacteria to limit this process have yet to be fully uncovered. My thesis project aimed to (i) decipher the autophagic response in macrophages induced by three species of mycobacteria: a non-pathogenic M.smegmatis, an opportunistic M.abcessus and a pathogenic M.tuberculosis and (ii) to determine the role of two lipidic virulence factors, phthiocerols of dimycocerosates (DIM) and sulfolipids (SL) in the modulation of the autophagy process to advantage the mycobacteria. This work has (i) characterized a novel induction mechanism of autophagy, which does not rely on the ubiquitination of the mycobacteria and implicates the activation of TLR signaling, and (ii) has shown that M. tuberculosis lipids DIM and SL and M abscessus glycopeptidolipid (GPL) are involved in the limitation of the autophagy process inside macrophages. Overall, this work provides novel regulation mechanisms of autophagy pathway during macrophage encounter with mycobacteria species, mechanisms that could be potential targets in the development of host-based therapy or vaccine against mycobacterial infections.