Browsing by Author "Mandal, Manoj"
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- A 3d cell culture model of the tuberculosis granuloma that can be applied for host genetic studies in the context of a multicellular immunologic response to infectionPublication . David, Susana; Mandal, Manoj; Anes, Elsa; Pires, DavidIntroduction: The granuloma is an inflammatory infiltrate of mononuclear cells. Some bacterial infections are characterized by the formation of granulomas as part of the immune response to contain the infection. Granuloma models have contributed valuable insights into the genetic basis of granuloma formation during infection. For example, IFNGR1 and IFNGR2 variants have been found to disrupt the immune response, resulting in impaired granuloma formation and increased susceptibility to diseases by Mycobacterium sp. More easily implemented comprehensive models would facilitate the study of the different immune mechanisms and help identify new diseaseassociated genes. Our objective is to generate an in vitro 3D cell culture model using human primary cells and microspheres to generate a stratified granuloma model for future use in genetic, immunological and drug discovery studies. Methods: A commercial system was used to encapsulate human peripheral blood mononuclear cells (PBMC) infected with GFP-expressing M. tuberculosis and maintained in culture for several weeks. The cellular constituents of these granulomas and their organization were characterized by fluorescence microscopy and flow cytometry as well as the viability of the cells and the extent of bacterial replication in factor of time. Results: The results demonstrate a ready recruitment of cells towards infected macrophages, leading to the formation of densely populated aggregates. These aggregates maintained cell viability for several weeks and displayed an enhanced control of bacterial replication compared to the more common monolayer infection models. Moreover, the capsules can be easily disrupted when required to isolate genetic material for further analysis. Conclusion: The proposed 3D model resembles some structural and cellular characteristics of the tuberculosis granuloma and maintains its stability beyond more common 2D models of infection. These preliminary results demonstrate that this model can be used to further explore the determinants of granuloma formation and host response to infection.
- A 3D cell culture model of the Tuberculosis granuloma that can be applied for host genetic studies in the context of a multicellular immunologic response to infectionPublication . David, Susana; Mandal, Manoj; Anes, Elsa; Pires, David
- Cystatin F depletion in Mycobacterium tuberculosis-infected macrophages improves cathepsin C/granzyme B-driven cytotoxic effects on HIV-infected cells during coinfectionPublication . Mandal, Manoj; Pires, David; Calado, Marta; Azevedo-Pereira, Jose Miguel; Anes, ElsaCystatin F (CstF) is a protease inhibitor of cysteine cathepsins, including those involved in activating the perforin/granzyme cytotoxic pathways. It is targeted at the endolysosomal pathway but can also be secreted to the extracellular milieu or endocytosed by bystander cells. CstF was shown to be significantly increased in tuberculous pleurisy, and during HIV coinfection, pleural fluids display high viral loads. In human macrophages, our previous results revealed a strong upregulation of CstF in phagocytes activated by interferon γ or after infection with Mycobacterium tuberculosis (Mtb). CstF manipulation using RNA silencing led to increased proteolytic activity of lysosomal cathepsins, improving Mtb intracellular killing. In the present work, we investigate the impact of CstF depletion in macrophages during the coinfection of Mtb-infected phagocytes with lymphocytes infected with HIV. The results indicate that decreasing the CstF released by phagocytes increases the major pro-granzyme convertase cathepsin C of cytotoxic immune cells from peripheral blood-derived lymphocytes. Consequently, an observed augmentation of the granzyme B cytolytic activity leads to a significant reduction in viral replication in HIV-infected CD4+ T-lymphocytes. Ultimately, this knowledge can be crucial for developing new therapeutic approaches to control both pathogens based on manipulating CstF.
- Development and characterisation of a 3D cell culture model of the tuberculosis granulomaPublication . Pires, David; David, Susana; Mandal, Manoj; Soderberg, Julia; Anes, ElsaTuberculosis (TB) is a disease caused by Mycobacterium tuberculosis (Mtb) that results in 1.6 million deaths yearly. The TB granuloma is the hallmark cellular structure of latent TB that contains the spread of infection1 . More comprehensive in vitro models of TB that better resemble the cellular and immunoregulatory complexity of the granuloma would facilitate the study of the interplay between the bacteria and the different immune system cells2 . We aim to generate an in vitro, 3D cell culture model of the TB granuloma that can be easily implemented using readily available commercial reagents and materials. A commercial encapsulation system based on sodium cellulose sulphate (NaCS) and Poly (diallyldimethylammonium chloride) (PDADMAC)3 was used to generate small capsules containing human peripheral blood mononuclear cells (PBMC) in the presence of GFPexpressing Mtb H37Rv and maintained in culture for several weeks. The 3D structure formed by the cells inside and outside the capsules was evaluated by fluorescence microscopy and flow cytometry to distinguish the different cell types, and how they are organised inside the sphere and to measure cell survival and bacteria replication. The results show that human PBMCs readily form 3D cellular aggregates around infected cells and that cells cultivated outside the capsules are attracted and surround the capsules in response to infection. The model could be maintained for several weeks before bacteria-induced cell necrosis. PBMC’s viability remained stable, with more than 80 % live cells following two weeks of culture. Moreover, adding an exterior layer of cells helped control bacterial replication, suggesting relevant communication between cells inside and outside the capsules to control the infection.
- Development of chitosan particles loaded with siRNA for cystatin C to control intracellular drug-resistant mycobacterium tuberculosisPublication . Pires, David; Mandal, Manoj; Matos, Ana I.; Peres, Carina; Catalão, Maria João; Azevedo-Pereira, José Miguel; Satchi-Fainaro, Ronit; Florindo, Helena F.; Anes, ElsaThe golden age of antibiotics for tuberculosis (TB) is marked by its success in the 1950s of the last century. However, TB is not under control, and the rise in antibiotic resistance worldwide is a major threat to global health care. Understanding the complex interactions between TB bacilli and their host can inform the rational design of better TB therapeutics, including vaccines, new antibiotics, and host-directed therapies. We recently demonstrated that the modulation of cystatin C in human macrophages via RNA silencing improved the anti-mycobacterial immune responses to Mycobacterium tuberculosis infection. Available in vitro transfection methods are not suitable for the clinical translation of host-cell RNA silencing. To overcome this limitation, we developed different RNA delivery systems (DSs) that target human macrophages. Human peripheral blood-derived macrophages and THP1 cells are difficult to transfect using available methods. In this work, a new potential nanomedicine based on chitosan (CS-DS) was efficiently developed to carry a siRNA-targeting cystatin C to the infected macrophage models. Consequently, an effective impact on the intracellular survival/replication of TB bacilli, including drug-resistant clinical strains, was observed. Altogether, these results suggest the potential use of CS-DS in adjunctive therapy for TB in combination or not with antibiotics.
- ESAT-6 a major virulence factor of mycobacterium tuberculosisPublication . Anes, Elsa; Pires, David; Mandal, Manoj; Azevedo-Pereira, José MiguelMycobacterium tuberculosis (Mtb), the causative agent of human tuberculosis (TB), is one of the most successfully adapted human pathogens. Human-to-human transmission occurs at high rates through aerosols containing bacteria, but the pathogen evolved prior to the establishment of crowded populations. Mtb has developed a particular strategy to ensure persistence in the host until an opportunity for transmission arises. It has refined its lifestyle to obviate the need for virulence factors such as capsules, flagella, pili, or toxins to circumvent mucosal barriers. Instead, the pathogen uses host macrophages, where it establishes intracellular niches for its migration into the lung parenchyma and other tissues and for the induction of long-lived latency in granulomas. Finally, at the end of the infection cycle, Mtb induces necrotic cell death in macrophages to escape to the extracellular milieu and instructs a strong inflammatory response that is required for the progression from latency to disease and transmission. Common to all these events is ESAT-6, one of the major virulence factors secreted by the pathogen. This narrative review highlights the recent advances in understanding the role of ESAT-6 in hijacking macrophage function to establish successful infection and transmission and its use as a target for the development of diagnostic tools and vaccines.
- HIV/Mtb co-infection: from the amplification of disease pathogenesis to an "emerging syndemic"Publication . Azevedo-Pereira, José Miguel; Pires, David; Calado, Marta; Mandal, Manoj; Santos-Costa, Quirina; Anes, ElsaHuman immunodeficiency virus (HIV) and Mycobacterium tuberculosis (Mtb) are pathogens responsible for millions of new infections each year; together, they cause high morbidity and mortality worldwide. In addition, late-stage HIV infection increases the risk of developing tuberculosis (TB) by a factor of 20 in latently infected people, and even patients with controlled HIV infection on antiretroviral therapy (ART) have a fourfold increased risk of developing TB. Conversely, Mtb infection exacerbates HIV pathogenesis and increases the rate of AIDS progression. In this review, we discuss this reciprocal amplification of HIV/Mtb coinfection and how they influence each other's pathogenesis. Elucidating the infectious cofactors that impact on pathogenesis may open doors for the design of new potential therapeutic strategies to control disease progression, especially in contexts where vaccines or the sterile clearance of pathogens are not effectively available.
- Host-directed therapies based on protease inhibitors to control Mycobacterium tuberculosis and HIV coinfectionPublication . Mandal, Manoj; Pires, David; Azevedo-Pereira, Jose Miguel; Anes, ElsaDespite continuous and extensive global efforts in the fight against tuberculosis (TB), this infectious disease continues to exert a tremendous burden on public health concerns and deaths worldwide. TB, caused by the bacterial species Mycobacterium tuberculosis, is highly frequent in people living with HIV. The continuing epidemics of both chronic infections and the emergence of antimicrobial resistance, as well as the lack of effective diagnostic tools and drug–drug interactions, pose major challenges in the fight against these pathogens. Developing a wide range of host-directed therapies may improve treatment outcomes, helping alleviate the morbidity and mortality associated with both infections. In this review, we discuss the identification and development of new host-directed strategies based on protease inhibitors and their clinical relevance as adjunctive treatment. In the context of therapeutic agents with novel mechanisms, selective protease inhibitors, including saquinavir (SQV) and cystatins (CstC and CstF), are valuable targets that may provide effective therapeutic solutions for controlling Mtb and HIV coinfection.
- Liposomal delivery of repurposed antiviral drug saquinavir to macrophages as a host-directed therapy for tuberculosisPublication . Mandal, Manoj; Pires, David; Pinho, Jacinta; Catalão, Maria João; Almeida, António José; Azevedo-Pereira, José Miguel; Gaspar, Maria Manuela; Anes, ElsaMycobacterium tuberculosis (Mtb) latently infects approximately a quarter of the world’s population and 10 % of these will develop the disease tuberculosis. Mtb infects macrophages, manipulating the proteolytic mechanisms, particularly, by decreasing the expression and activity of lysosomal cathepsins. Consequently, Mtb survives and even replicates inside macrophages concomitant with poor priming of the adaptive immune response. Our group found that the protease inhibitor used in antiretroviral therapy for HIV infection, saquinavir (SQV), restores and further improves the overall activity of cathepsins in Mtb-infected macrophages and more specifcally, that of cathepsin S [1]. In this study, we tested the incorporation of SQV in liposomes to establish an improved delivery method for SQV to human monocyte-derived macrophages. Using fuorophore-tagged liposomes we demonstrated the effciency of SQV-loaded liposome internalization by human macrophages. Additionally, using a general fuorescent substrate of human cathepsins we could observe improved proteolytic activity in treated macrophages. When applying this treatment to Mtb-infected macrophages these effects resulted in better control of the infection. Furthermore, liposomal delivery of SQV reduced the cytotoxicity of the treatment and allowed the usage of higher concentrations without impacting cell viability. By using this strategy, we overcame the cathepsin activity blockade that is induced by the pathogen [2]. The results further demonstrate the effcacy of SQV-loaded liposomes to help control infections by Mtb clinical strains susceptible or resistant to the current antibiotic therapy. Our results suggest the use of liposomal delivery of SQV as a potential complementary therapy against Mtb infection. Human monocytes were isolated from buffy-coats of healthy human donors provided by the National Blood Institute (Instituto Português do Sangue e da Transplantação, IP, Lisbon, Portugal).
- Liposomal delivery of saquinavir to macrophages overcomes cathepsin blockade by Mycobacterium tuberculosis and helps control the phagosomal replicative nichesPublication . Pires, David; Mandal, Manoj; Pinho, Jacinta; Catalão, Maria João; Almeida, António José; Azevedo-Pereira, José Miguel; Gaspar, Maria Manuela; Anes, ElsaMycobacterium tuberculosis is able to establish a chronic colonization of lung macrophages in a controlled replication manner, giving rise to a so-called latent infection. Conversely, when intracellular bacteria undergo actively uncontrolled replication rates, they provide the switch for the active infection called tuberculosis to occur. Our group found that the pathogen is able to manipulate the activity of endolysosomal enzymes, cathepsins, directly at the level of gene expression or indirectly by regulating their natural inhibitors, cystatins. To provide evidence for the crucial role of cathepsin manipulation for the success of tuberculosis bacilli in their intracellular survival, we used liposomal delivery of saquinavir. This protease inhibitor was previously found to be able to increase cathepsin proteolytic activity, overcoming the pathogen induced blockade. In this study, we demonstrate that incorporation in liposomes was able to increase the efficiency of saquinavir internalization in macrophages, reducing cytotoxicity at higher concentrations. Consequently, our results show a significant impact on the intracellular killing not only to reference and clinical strains susceptible to current antibiotic therapy but also to multidrug- and extensively drug-resistant (XDR) Mtb strains. Altogether, this indicates the manipulation of cathepsins as a fine-tuning strategy used by the pathogen to survive and replicate in host cells.