Biology subjects

Renshaw, S. A.

Publications and source records attributed to Renshaw, S. A..

18 recordsLinked to original sources

bioRxiv2023

Macrophage transplantation rescues RNASET2-deficient leukodystrophy by replacing deficient microglia in a zebrafish model

RNaseT2-deficient leukodystrophy is a rare infantile white matter disorder mimicking a viral infection and resulting in severe psychomotor impairments. Despite its severity, there remain no treatments for this disorder, with little understanding of cellular mechanisms of pathogenesis. Recent research using the rnaset2 mutant zebrafish model has suggested that microglia - brain-resident phagocytes - may be the drivers of neuroinflammation in this disorder, due to their failure to digest apoptotic debris during early development. As such, the current study aimed to develop a strategy for microglial replacement and test the effects of this intervention on rnaset2 mutant zebrafish pathology. We developed a strategy for microglial replacement through transplantation of adult whole kidney marrow-derived macrophages into embryonic hosts. Using live imaging, we revealed that transplant-derived macrophages can engraft within host brains and express microglia-specific markers, suggesting adoption of a microglial phenotype. Tissue clearing strategies revealed the persistence of transplanted cells in host brains beyond embryonic stages We demonstrated that transplanted cells clear apoptotic cells within the brain, as well as rescuing overactivation of the antiviral response otherwise seen in mutant larvae. RNA sequencing at the point of peak transplant-derived cell engraftment confirms that transplantation can reduce the brain-wide immune response, and particularly the antiviral response, in rnaset2-deficient brains. Crucially, this reduction in neuroinflammation resulted in behavioural rescue - restoring rnaset2 mutant motor activity to wild type levels in embryonic and juvenile stages. Together, these findings demonstrate the role of microglia as the cellular drivers of neuropathology in rnaset2 mutants, and that macrophage transplantation is a viable strategy for microglial replacement in the zebrafish. Therefore, microglia-targeted interventions may have therapeutic benefits in RNaseT2-deficient leukodystrophy.

neuroscience↗

bioRxiv2022

The EGFR/ErbB inhibitor neratinib modifies the neutrophil phosphoproteome and promotes apoptosis and clearance by airway macrophages

Dysregulated neutrophilic inflammation can be highly destructive in chronic inflammatory diseases due to prolonged neutrophil lifespan and continual release of histotoxic mediators in inflamed tissues. Therapeutic induction of neutrophil apoptosis, an immunologically silent form of cell death, may be beneficial in these diseases, provided that the apoptotic neutrophils are efficiently cleared from the tissue. Our previous research identified ErbB inhibitors as able to induce neutrophil apoptosis and reduce neutrophilic inflammation both in vitro and in vivo (Rahman et al., 2019). Here we extend that work using a clinical ErbB inhibitor, neratinib, which has the potential to be repurposed in inflammatory diseases. We show that neratinib reduces neutrophilic migration to an inflammatory site in zebrafish larvae. Neratinib upregulates efferocytosis and reduces the number of persisting neutrophil corpses in mouse models of acute, but not chronic, lung injury, suggesting the drug may have therapeutic benefits in acute inflammatory settings. Phosphoproteomics analysis of human neutrophils shows that neratinib modifies the phosphorylation of proteins regulating apoptosis, migration and efferocytosis. This work identifies a potential mechanism for neratinib in treating acute lung inflammation by upregulating the clearance of dead neutrophils and, through examination of the neutrophil phosphoproteome, provides important insights into the mechanisms by which this may be occurring.

immunology↗

bioRxiv2022

A subset of gut leukocytes have telomerase-dependent 'hyper-long' telomeres and require telomerase for function in zebrafish

Telomerase, the enzyme capable of elongating telomeres, is usually restricted in human somatic cells, which contributes to progressive telomere shortening with cell-division and ageing. Using the zebrafish model, we show that subsets gut immune cells have telomerase-dependent "hyper-long" telomeres, which we identified as being predominantly macrophages and dendritics (mpeg1.1+ and cd45+mhcII+). Notably, mpeg+ macrophages have much longer telomeres in the gut than in their haematopoietic tissue of origin, suggesting that there is a gut-specific modulation of telomerase in these cells. Moreover, we show that a subset of gut mpeg+ cells express telomerase (tert) in young WT zebrafish, but that the relative proportion of these cells decreases with ageing. Importantly, this is accompanied by telomere shortening and DNA damage responses with ageing and a telomerase-dependent decrease in expression of autophagy and immune activation markers. Finally, these telomerase-dependent molecular alterations are accompanied by impaired phagocytosis of E.coli and increased gut permeability in vivo. Together, our data show that limiting levels of telomerase lead to changes in gut immunity and gut permeability, which, together, are likely contributors to local and systemic tissue degeneration and increased susceptibility to infection with ageing. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/478480v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@141a6caorg.highwire.dtl.DTLVardef@12d24baorg.highwire.dtl.DTLVardef@c64267org.highwire.dtl.DTLVardef@319449_HPS_FORMAT_FIGEXP M_FIG C_FIG Our data show that limiting levels of telomerase contribute to alterations in gut immunity, namely increased apoptosis, decreased autophagy and immune activation of mpeg+ macrophages in the gut. This is accompanied by a decreased ability to clear pathogens and increased gut permeability. Together, these are likely contributors to local and systemic tissue degeneration and susceptibility to infection with ageing.

cell biology↗

bioRxiv2021

Roscovitine exacerbates Mycobacterium abscessus infection by reducing NADPH oxidase-dependent neutrophil trafficking

Persistent neutrophilic inflammation associated with chronic pulmonary infection causes progressive lung injury and eventually death in individuals with cystic fibrosis (CF), a genetic disease caused by bi-allelic mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. We therefore examined whether Roscovitine, a cyclin-dependent kinase inhibitor that (in other conditions) reduces inflammation while promoting host defence, might provide a beneficial effect in the context of CF. Herein, using CFTR-depleted zebrafish larvae as an innovative vertebrate model of CF immuno-pathophysiology, combined with murine and human approaches, we sought to determine the effects of Roscovitine on innate immune responses to tissue injury and pathogens in CF condition. We show that Roscovitine exerts anti-inflammatory and pro-resolution effects in neutrophilic inflammation induced by infection or tail amputation in zebrafish. Roscovitine reduces overactive epithelial ROS-mediated neutrophil trafficking, by reducing DUOX2/NADPH-oxidase activity, and accelerates inflammation resolution by inducing neutrophil apoptosis and reverse migration. Importantly, while Roscovitine efficiently enhances intracellular bacterial killing of Mycobacterium abscessus in human CF macrophages ex vivo, we found that treatment with Roscovitine results in worse infection in mouse and zebrafish models. By interfering with DUOX2/NADPH oxidase-dependent ROS production, Roscovitine reduces the number of neutrophils at infection sites, and consequently compromises granuloma formation and maintenance, favouring extracellular multiplication of M. abscessus and more severe infection. Our findings bring important new understanding of the immune-targeted action of Roscovitine and have significant therapeutic implications for safety targeting inflammation in CF.

microbiology↗

bioRxiv2021

A zebrafish reporter line reveals immune and neuronal expression of endogenous retrovirus.

Endogenous retroviruses (ERVs) are fossils left in our genome from retrovirus infections of the past. Their sequences are part of every vertebrate genome and their random integrations are thought to have contributed to evolution. Although ERVs are mainly kept silenced by the host genome, they are found activated in multiple disease states such as auto-inflammatory disorders and neurological diseases. What makes defining their role in health and diseases challenging is the numerous copies in mammalian genomes and the lack of tools to study them. In this study, we identified 8 copies of the zebrafish endogenous retrovirus (zferv). We created and characterised the first in vivo ERV reporter line in any species. Using a combination of live imaging, flow cytometry and single cell RNA sequencing, we mapped zferv expression to early T cells and neurons. Thus, this new tool identified tissues expressing ERV in zebrafish, highlighting a potential role of ERV during brain development and strengthening the hypothesis that ERV play a role in immunity and neurological diseases. This transgenic line is therefore a suitable tool to study the function of ERV in health and diseases.

cell biology↗

bioRxiv2020

Humanisation of the zebrafish C5a receptor confers targeting by human-specific staphylococcal virulence factors.

Staphylococcus aureus infects approximately 30% of the human population and causes a spectrum of pathologies ranging from mild skin infections to life-threatening invasive diseases. The strict host specificity of its virulence factors has severely limited the accuracy of in vivo models for the development of vaccines and therapeutics. To resolve this, we generated a humanised zebrafish model and determined that neutrophil-specific expression of the human C5a receptor conferred susceptibility to the S. aureus toxins PVL and HlgCB, leading to reduced neutrophil numbers at the site of infection and increased infection-associated mortality as a direct result of the interaction between S. aureus and the receptor. These results show that humanised zebrafish provide a valuable platform to study the contribution of human-specific S. aureus virulence factors to infection in vivo that could facilitate the development of novel therapeutic approaches and essential vaccines.

immunology↗

bioRxiv2019

Deletion of cftr leads to an excessive neutrophilic response and defective tissue repair in a zebrafish model of sterile inflammation

Inflammation-related progressive lung destruction is the leading causes of premature death in cystic fibrosis (CF), a genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. However, therapeutic targeting of inflammation has been hampered by a lack of understanding of the links between a dysfunctional CFTR and the deleterious innate immune response in CF. Herein, we used CFTR-depleted zebrafish larvae as an innovative in vivo vertebrate model, mimicking aspects of the inflammatory pathology of CF-related lung, to understand how CFTR dysfunction leads to abnormal inflammatory status in CF. We show that impaired CFTR-mediated inflammation correlates with an exuberant neutrophilic response after injury: CF zebrafish exhibit enhanced and sustained accumulation of neutrophils at wounds. Excessive epithelial oxidative responses drive enhanced neutrophil recruitment towards wounds. Persistence of neutrophils at inflamed sites is associated with impaired reverse migration of neutrophils and reduction in neutrophil apoptosis. As a consequence, the increased number of neutrophils at wound sites causes tissue damage and abnormal tissue repair. Importantly, the pro-resolution molecule Tanshinone IIA successfully re-balances inflammation both by accelerating inflammation resolution and by improving tissue repair in CFTR-deficient animal. Larval zebrafish giving a unique insight into innate immune cell function in CFTR deficiency, our findings bring important new understanding of the mechanisms underlying the inflammatory pathology in CF, which could be addressed therapeutically to prevent inflammatory lung damage in CF patients with potential improvements in disease outcomes.

immunology↗

bioRxiv2019

Evaluation of the anti-inflammatory effects of synthesised tanshinone I and isotanshinone I analogues in zebrafish

During inflammation, dysregulated neutrophil behaviour can play a major role in chronic inflammatory diseases such as chronic obstructive pulmonary disease, for which current treatments are generally ineffective. Recently, tanshinones have shown promising antiinflammatory effects by targeting neutrophils in vivo, yet are still an underexplored general group of compounds. Here, an existing six step synthetic route was optimised and used to prepare a small family of substituted tanshinone and isomeric isotanshinone analogues, together with the synthesis of other structurally similar molecules. Evaluation of these using a transgenic zebrafish model of inflammation revealed that many of these compounds exhibit promising anti-inflammatory effects in vivo. Several compounds affect neutrophil recruitment and/or resolution of neutrophilic inflammation, and broad structure-activity relationships were constructed. In particular, the methoxy-substituted tanshinone 39 specifically accelerates resolution of inflammation without affecting organism host defence, making this a particularly attractive candidate for potential pro-resolution therapeutics. On the other hand, {beta}-lapachones exhibit effects on neutrophil recruitment yet not on resolution. Notable differences in toxicity profiles between compound classes were also observed.

immunology↗

bioRxiv2019

Failure to clear developmental apoptosis contributes to the pathology of RNASET2-deficient leukoencephalopathy.

The contribution of microglia in neurological disorders is emerging as a leading driver rather than a consequence of pathology. RNAseT2-deficient leukoencephalopathy is a severe childhood white matter disorder affecting patients in their first year of life and mimics a cytomegalovirus brain infection. The early onset and resemblance of the symptoms to an immune response suggest an inflammatory and embryonic origin of the pathology. In this study, we identify deficient microglia as an early marker of pathology. Using the ex utero development and the optical transparency of an rnaset2-deficient zebrafish model, we found that dysfunctional microglia fail to clear apoptotic neurons during brain development. This was associated with increased number of apoptotic cells and behavioural defects lasting into adulthood. This zebrafish model recapitulates all aspect of the human disease to be used as a robust preclinical model. Using microglia-specific depletion and rescue experiments, we identified microglia as potential drivers of the pathology and highlight tissue-specific approaches as future therapeutic avenues.

neuroscience↗

bioRxiv2019

The CXCL12/CXCR4 signalling axis retains neutrophils at inflammatory sites in zebrafish

The inappropriate retention of neutrophils in the lung is a major driver of the excessive tissue damage characteristic of respiratory inflammatory diseases including COPD, ARDS and cystic fibrosis. The molecular programmes which orchestrate neutrophil recruitment to inflammatory sites through chemotactic guidance have been well studied. However, how neutrophil sensitivity to these cues is modulated during inflammation resolution is not understood. The identification of neutrophil reverse migration as a mechanism of inflammation resolution and the ability to modulate this therapeutically has identified a new target to treat inflammatory disease. Here we investigate the role of the CXCL12/CXCR4 signalling axis in modulating neutrophil retention at inflammatory sites. We used an in vivo tissue injury model to study inflammation using transgenic zebrafish larvae. Expression of cxcl12a and cxcr4b during the tissue damage response was assessed using in situ hybridisation and analysis of RNA sequencing data. CRISPR/Cas9 was used to knockdown cxcl12a and cxcr4b in zebrafish larvae. The CXCR4 antagonist AMD3100 was used to block the Cxcl12/Cxcr4 signalling axis pharmacologically. We identified that cxcr4b and cxcl12a are expressed at the wound site in zebrafish larvae during the inflammatory response. Following tail-fin transection, removal of neutrophils from inflammatory sites is significantly increased in cxcr4b and cxcl12a CRISPR knockdown larvae. Pharmacological inhibition of the Cxcl12/Cxcr4 signalling axis accelerates inflammation resolution, an effect caused by an increase in neutrophil reverse migration. The findings of this study suggest that CXCR4/CXCL12 signalling may play an important role in neutrophil retention at inflammatory sites, identifying a potential new target for the therapeutic removal of neutrophils from the lung in chronic inflammatory disease.

immunology↗

bioRxiv2019

Neutrophils use selective autophagy receptor p62 to target Staphylococcus aureus for degradation in the zebrafish model

Autophagy leads to degradation of cellular components and has an important role in restricting intracellular pathogens. Autophagy receptors, including p62, target invading intracellular pathogens to the autophagy pathway for degradation. Staphylococcus aureus is a significant pathogen of humans and often life-threatening in the immunocompromised. Increasing evidence demonstrates that S. aureus is an intracellular pathogen of immune cells and may use neutrophils as proliferative niche but the intracellular fate of S. aureus following phagocytosis by neutrophils has not previously been analysed in vivo. In vitro, p62 is able to co-localise with intracellular Staphylococcus aureus, but whether p62 is beneficial or detrimental in host defence against S. aureus in vivo had not been determined. Here we use zebrafish to determine the fate and location of S. aureus within neutrophils throughout infection. We show that Lc3 and p62 recruitment to phagocytosed S. aureus is altered depending on the bacterial location within the neutrophil. We also show rapid Lc3 marking of bacterial phagosomes within neutrophils which may be associated with subsequent bacterial degradation. Finally, we find that p62 is important for controlling cytosolic bacteria demonstrating for the first time a key role of p62 in autophagic control of S. aureus in neutrophils.

immunology↗

bioRxiv2019

The autophagic response to Staphylococcus aureus provides an intracellular niche in neutrophils

Staphylococcus aureus is a major human pathogen causing multiple pathologies, from cutaneous lesions to life-threatening sepsis. Although neutrophils contribute to immunity against S. aureus, multiple lines of evidence suggest that these phagocytes can provide an intracellular niche for staphylococcal dissemination. However, the mechanism of neutrophil subversion by intracellular S. aureus remains unknown. Targeting of intracellular pathogens by autophagy is recognised as an important component of host innate immunity, but whether autophagy is beneficial or detrimental to S. aureus-infected hosts remains controversial. Here, using larval zebrafish we show that S. aureus is rapidly decorated by the autophagy marker Lc3 following engulfment by macrophages and neutrophils. Upon phagocytosis by neutrophils, Lc3-positive, non-acidified spacious phagosomes are formed. This response is dependent on phagocyte NADPH oxidase as both cyba knockdown and diphenyleneiodonium (DPI) treatment inhibited Lc3 decoration of phagosomes. Importantly, NADPH oxidase inhibition diverted neutrophil S. aureus processing into tight acidified vesicles, which resulted in increased host resistance to the infection. Some intracellular bacteria within neutrophils were also tagged by p62-GFP fusion protein and loss of p62 impaired host defence. Taken together, we have shown that intracellular handling of S. aureus by neutrophils is best explained by Lc3-associated phagocytosis (LAP), which appears to provide an intracellular niche for bacterial pathogenesis, while the selective autophagy receptor p62 is host-protective. The antagonistic roles of LAP and p62-mediated pathways in S. aureus-infected neutrophils may explain the conflicting reports relating to anti-staphylococcal autophagy and provide new insights for therapeutic strategies against antimicrobial resistant staphylococci.

immunology↗

bioRxiv2019

Non-apoptotic pioneer neutrophils initiate an endogenous swarming response in a zebrafish tissue injury model

Neutrophils are rapidly recruited to inflammatory sites where they coordinate their migration to form clusters, a process termed neutrophil swarming. The factors which modulate neutrophil swarming during its early stages are not fully understood, requiring the development of new in vivo models. Using transgenic zebrafish larvae to study endogenous neutrophil migration in a tissue damage model, we demonstrate that neutrophil swarming is a conserved process in zebrafish immunity, sharing essential features with mammalian systems. We show that neutrophil swarms initially develop around a pioneer neutrophil, in a three-phase sequence of events. By adopting a high-resolution confocal microscopy approach, we observed the release of cell fragments by early swarming neutrophils. We developed a neutrophil specific histone H2A transgenic reporter line TgBAC(mpx:GFP)i114;Tg(lyz:H2A-mCherry)sh530 to study neutrophil extracellular traps (NETs), and found that endogenous neutrophils recruited to sites of tissue damage released NETs at the start of the swarming process. The optical transparency achieved using the zebrafish model has provided some of the highest resolution imaging of NET release in vivo to date. Using a combination of transgenic reporter lines and DNA intercalating agents, we demonstrate that pioneer neutrophils release extracellular traps during the swarming response, suggesting that cell death signalling via NETosis might be important in driving the swarming response.

immunology↗

bioRxiv2018

A transgenic zebrafish line for in vivo visualisation of neutrophil myeloperoxidase

The neutrophil enzyme myeloperoxidase (MPO) is a major enzyme made by neutrophils to generate antimicrobial and immunomodulatory compounds, notably hypochlorous acid (HOCl), amplifying their capacity for destroying pathogens and regulating inflammation. Despite its roles in innate immunity, the importance of MPO in preventing infection is unclear, as individuals with MPO deficiency are asymptomatic with the exception of an increased risk of candidiasis. Dysregulation of MPO activity is also linked with inflammatory conditions such as atherosclerosis, emphasising a need to understand the roles of the enzyme in greater detail. Consequently, new tools for investigating granular dynamics in vivo can provide useful insights into how MPO localises within neutrophils, aiding understanding of its role in preventing and exacerbating disease. The zebrafish is a powerful model for investigating the immune system in vivo, as it is genetically tractable, and optically transparent. To visualise MPO activity within zebrafish neutrophils, we created a genetic construct that expresses human MPO as a fusion protein with a C-terminal fluorescent tag, driven by the neutrophil-specific promoter lyz. After introducing the construct into the zebrafish genome by Tol2 transgenesis, we established the Tg(lyz:Hsa.MPO-mEmerald,cmlc2:EGFP)sh496 line, and confirmed transgene expression in zebrafish neutrophils. We observed localisation of MPO-mEmerald within a subcellular location resembling neutrophil granules, mirroring MPO in human neutrophils. In Spotless (mpxNL144) larvae - which express a non-functional zebrafish myeloperoxidase - the MPO-mEmerald transgene does not disrupt neutrophil migration to sites of infection or inflammation, suggesting that it is a suitable line for the study of neutrophil granule function. We present a new transgenic line that can be used to investigate neutrophil granule dynamics in vivo without disrupting neutrophil behaviour, with potential applications in studying processing and maturation of MPO during development.

immunology↗

bioRxiv2018

Macrophage Il-1beta protects against mycobacterial infection downstream of Hif-1alpha in zebrafish

Drug resistant mycobacteria are a rising problem worldwide. There is an urgent need to understand the immune response to TB to identify host targets that, if targeted therapeutically, could be used to tackle these currently untreatable infections. Here, we use an Il-1{beta} fluorescent transgenic line to show that there is an early innate immune pro-inflammatory response to well-established zebrafish models of inflammation and Mycobacterium marinum (Mm) infection. We demonstrate that host-derived hypoxia signalling, mediated by the Hif-1 transcription factor, can prime macrophages with increased levels of Il-1{beta} in the absence of infection, upregulating neutrophil antimicrobial nitric oxide production, leading to greater protection against infection. Our data link Hif-1 to proinflammatory macrophage Il-1{beta} transcription in vivo during early mycobacterial infection and importantly highlight a host protective mechanism, via antimicrobial nitric oxide, that decreases disease outcomes and that could be targeted therapeutically to stimulate the innate immune response to better deal with infections.

immunology↗

bioRxiv2017

Lipid mediator class-switching downstream of PGE2 determines the outcome of inflammation resolution in vivo.

Neutrophils are the first immune cells recruited to a site of injury or infection, where they perform many functions. Having completed their role, neutrophils must be removed from the inflammatory site - either by apoptosis and efferocytosis or by reverse migration away from the wound - for restoration of normal tissue homeostasis. Disruption of these tightly controlled physiological processes of neutrophil removal can lead to a range of inflammatory diseases. We used an in vivo zebrafish model to understand the role of lipid mediator production in neutrophil removal. Following tailfin amputation in the absence of macrophages, neutrophillic inflammation does not resolve. This is due to loss of macrophage-dependent production of eicosanoid prostaglandin E2, which drives neutrophil removal via promotion of reverse migration. Knockdown of endogenous prostaglandin E synthase gene reveals PGE2 as essential for neutrophil inflammation resolution. Furthermore, PGE2 is able to signal through EP4 receptors to enhance Alox15 production, causing a switch towards anti-inflammatory eicosanoid signalling, specifically Lipoxin A4. Our data confirm regulation of neutrophil migration by PGE2 and LXA4 in an in vivo model of inflammation resolution. This pathway may contain therapeutic targets for driving inflammation resolution in chronic inflammatory disease.

immunology↗

bioRxiv2017

Mycophenolate mofetil increases susceptibility toopportunistic fungal infection independent of lymphocytes

Anti-proliferative agents that target lymphoid cells are common immunosuppressive agents used in the treatment of diverse autoimmune, graft versus host and inflammatory diseases. Mycophenolate mofetil (MMF) is an anti-proliferative agent that targets lymphoid dependence on inosine monophosphate dehydrogenase for the de novo purine synthesis of deoxyguanosine triphosphate (dGTP) for DNA replication. Here we show that MMF has a distinct and specific in vivo effect on macrophages, in the absence of lymphoid cells. This results in increased macrophage cell death that is dependent on the depletion of cellular GTP, independent of DNA synthesis. Furthermore, the macrophage specific effect of MMF treatment causes an increase in susceptibility to the opportunistic fungal infection Cryptococcus neoformans by reducing phagocytosis and increasing the release of intracellular pathogens via macrophage lysis. Our study demonstrates the need for a better mechanistic understanding of immunosuppressive treatments used in clinical practice and of the specific infection risks associated with certain treatment regimens.

immunology↗

bioRxiv2017

Polymersomes Targeting Mononuclear Phagocytes

Mononuclear phagocytes such as monocytes, tissue-specific macrophages and dendritic cells are primary actors in both innate and adaptive immunity, as well as tissue homoeostasis. They have key roles in a range of physiological and pathological processes, so any strategy targeting these cells will have wide-ranging impact. These phagocytes can be parasitized by intracellular bacteria, turning them from housekeepers to hiding places and favouring chronic and/or disseminated infection. One of the most infamous is the bacteria that cause tuberculosis, which is the most pandemic and one of the deadliest disease with one third of the worlds population infected, and 1.8 million deaths worldwide in 2015. Here we demonstrate the effective targeting and intracellular delivery of antibiotics to both circulating monocytes and resident macrophages, using pH sensitive nanoscopic polymersomes made of poly(2-(methacryloyloxy)ethyl phosphorylcholine)-co-poly(2-(di-isopropylamino)ethyl methacrylate) (PMPC-PDPA). Polymersome selectivity to mononuclear phagocytes is demonstrated and ascribed to the polymerised phosphorylcholine motifs affinity toward scavenger receptors. Finally, we demonstrate the successful exploitation of this targeting for the effective eradication of intracellular bacteria that cause tuberculosis Mycobacterium tuberculosis as well as other intracellular parasites including the Mycobacterium bovis, Mycobacterium marinum and the most common bacteria associated with antibiotic resistance, the Staphylococcus aureus.

immunology↗