Host-directed therapy with amiodarone in preclinical models restricts mycobacterial infection and enhances autophagy.

Unlabelled: () as well as nontuberculous mycobacteria are intracellular pathogens whose treatment is extensive and increasingly impaired due to the rise of mycobacterial drug resistance. The loss of antibiotic efficacy has raised interest in the identification of host-directed therapeutics (HDT) to develop novel treatment strategies for mycobacterial infections. In this study, we identified amiodarone as a potential HDT candidate that inhibited both intracellular and in primary human macrophages without directly impairing bacterial growth, thereby confirming that amiodarone acts in a host-mediated manner.

Using Zebrafish to Dissect the Interaction of Mycobacteria with the Autophagic Machinery in Macrophages.

Existing drug treatment against tuberculosis is no match against the increasing number of multi-drug resistant strains of its causative agent, (). A better understanding of how mycobacteria subvert the host immune defenses is crucial for developing novel therapeutic strategies. A potential approach is enhancing the activity of the autophagy machinery, which can direct bacteria to autophagolysosomal degradation.

DRAM1 Promotes Lysosomal Delivery of in Macrophages.

Damage-Regulated Autophagy Modulator 1 (DRAM1) is an infection-inducible membrane protein, whose function in the immune response is incompletely understood. Based on previous results in a zebrafish infection model, we have proposed that DRAM1 is a host resistance factor against intracellular mycobacterial infection. To gain insight into the cellular processes underlying DRAM1-mediated host defence, here we studied the interaction of DRAM1 with in murine RAW264.

Repurposing Tamoxifen as Potential Host-Directed Therapeutic for Tuberculosis.

The global burden of tuberculosis (TB) is aggravated by the continuously increasing emergence of drug resistance, highlighting the need for innovative therapeutic options. The concept of host-directed therapy (HDT) as adjunctive to classical antibacterial therapy with antibiotics represents a novel and promising approach for treating TB. Here, we have focused on repurposing the clinically used anticancer drug tamoxifen, which was identified as a molecule with strong host-directed activity against intracellular Mycobacterium tuberculosis ().

HI-NESS: a family of genetically encoded DNA labels based on a bacterial nucleoid-associated protein.

The interplay between three-dimensional chromosome organisation and genomic processes such as replication and transcription necessitates in vivo studies of chromosome dynamics. Fluorescent organic dyes are often used for chromosome labelling in vivo. The mode of binding of these dyes to DNA cause its distortion, elongation, and partial unwinding.

Autophagy and Lc3-Associated Phagocytosis in Zebrafish Models of Bacterial Infections.

Modeling human infectious diseases using the early life stages of zebrafish provides unprecedented opportunities for visualizing and studying the interaction between pathogens and phagocytic cells of the innate immune system. Intracellular pathogens use phagocytes or other host cells, like gut epithelial cells, as a replication niche. The intracellular growth of these pathogens can be counteracted by host defense mechanisms that rely on the autophagy machinery.

Mathematical Mirroring for Identification of Local Symmetry Centers in Microscopic Images Local Symmetry Detection in FIJI.

Symmetry is omnipresent in nature and we encounter symmetry routinely in our everyday life. It is also common on the microscopic level, where symmetry is often key to the proper function of core biological processes. The human brain is exquisitely well suited to recognize such symmetrical features with ease.

Deficiency in the autophagy modulator Dram1 exacerbates pyroptotic cell death of Mycobacteria-infected macrophages.

DNA damage regulated autophagy modulator 1 (DRAM1) is a stress-inducible regulator of autophagy and cell death. DRAM1 has been implicated in cancer, myocardial infarction, and infectious diseases, but the molecular and cellular functions of this transmembrane protein remain poorly understood. Previously, we have proposed DRAM1 as a host resistance factor for tuberculosis (TB) and a potential target for host-directed anti-infective therapies.

Aryl Hydrocarbon Receptor Modulation by Tuberculosis Drugs Impairs Host Defense and Treatment Outcomes.

Antimicrobial resistance in tuberculosis (TB) is a public health threat of global dimension, worsened by increasing drug resistance. Host-directed therapy (HDT) is an emerging concept currently explored as an adjunct therapeutic strategy for TB. One potential host target is the ligand-activated transcription factor aryl hydrocarbon receptor (AhR), which binds TB virulence factors and controls antibacterial responses.

The selective autophagy receptors Optineurin and p62 are both required for zebrafish host resistance to mycobacterial infection.

Mycobacterial pathogens are the causative agents of chronic infectious diseases like tuberculosis and leprosy. Autophagy has recently emerged as an innate mechanism for defense against these intracellular pathogens. In vitro studies have shown that mycobacteria escaping from phagosomes into the cytosol are ubiquitinated and targeted by selective autophagy receptors.

Macrophages target Salmonella by Lc3-associated phagocytosis in a systemic infection model.

Innate immune defense against intracellular pathogens, like Salmonella, relies heavily on the autophagy machinery of the host. This response is studied intensively in epithelial cells, the target of Salmonella during gastrointestinal infections. However, little is known of the role that autophagy plays in macrophages, the predominant carriers of this pathogen during systemic disease.

Microbiota promote secretory cell determination in the intestinal epithelium by modulating host Notch signaling.

Resident microbes promote many aspects of host development, although the mechanisms by which microbiota influence host tissues remain unclear. We showed previously that the microbiota is required for allocation of appropriate numbers of secretory cells in the zebrafish intestinal epithelium. Because Notch signaling is crucial for secretory fate determination, we conducted epistasis experiments to establish whether the microbiota modulates host Notch signaling.

Correction: Macrophages, but not neutrophils, are critical for proliferation of Burkholderia cenocepacia and ensuing host-damaging inflammation.

[This corrects the article DOI: 10.1371/journal.ppat.

Macrophages, but not neutrophils, are critical for proliferation of Burkholderia cenocepacia and ensuing host-damaging inflammation.

Bacteria of the Burkholderia cepacia complex (Bcc) can cause devastating pulmonary infections in cystic fibrosis (CF) patients, yet the precise mechanisms underlying inflammation, recurrent exacerbations and transition from chronic stages to acute infection and septicemia are not known. Bcc bacteria are generally believed to have a predominant extracellular biofilm life style in infected CF lungs, similar to Pseudomonas aeruginosa, but this has been challenged by clinical observations which show Bcc bacteria predominantly in macrophages. More recently, Bcc bacteria have emerged in nosocomial infections of patients hospitalized for reasons unrelated to CF.

DRAM1 promotes the targeting of mycobacteria to selective autophagy.

Autophagy provides an important defense mechanism against intracellular bacteria, such as Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis disease (TB). We recently reported that pathogen recognition and antibacterial autophagy are connected by the induction of the DNA damage-regulated autophagy modulator DRAM1 via the toll-like receptor (TLR)-MYD88-NFKB innate immunity signaling pathway. Having shown that DRAM1 colocalizes with Mtb in human macrophages, we took advantage of a zebrafish model for TB to investigate the function of DRAM1 in autophagic host defense in vivo.

GLUT2-mediated glucose uptake and availability are required for embryonic brain development in zebrafish.

Glucose transporter 2 (GLUT2; gene name SLC2A2) has a key role in the regulation of glucose dynamics in organs central to metabolism. Although GLUT2 has been studied in the context of its participation in peripheral and central glucose sensing, its role in the brain is not well understood. To decipher the role of GLUT2 in brain development, we knocked down slc2a2 (glut2), the functional ortholog of human GLUT2, in zebrafish.

Cellular visualization of macrophage pyroptosis and interleukin-1β release in a viral hemorrhagic infection in zebrafish larvae.

Hemorrhagic viral diseases are distributed worldwide with important pathogens, such as dengue virus or hantaviruses. The lack of adequate in vivo infection models has limited the research on viral pathogenesis and the current understanding of the underlying infection mechanisms. Although hemorrhages have been associated with the infection of endothelial cells, other cellular types could be the main targets for hemorrhagic viruses.

Mycobacteria counteract a TLR-mediated nitrosative defense mechanism in a zebrafish infection model.

Pulmonary tuberculosis (TB), caused by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb), is a major world health problem. The production of reactive nitrogen species (RNS) is a potent cytostatic and cytotoxic defense mechanism against intracellular pathogens. Nevertheless, the protective role of RNS during Mtb infection remains controversial.

Nanoparticles as drug delivery system against tuberculosis in zebrafish embryos: direct visualization and treatment.

Nanoparticles (NPs) enclosing antibiotics have provided promising therapy against Mycobacterium tuberculosis (Mtb) in different mammalian models. However, the NPs were not visualized in any of these animal studies. Here, we introduce the transparent zebrafish embryo as a system for noninvasive, simultaneous imaging of fluorescent NPs and the fish tuberculosis (TB) agent Mycobacterium marinum (Mm).

The DNA damage-regulated autophagy modulator DRAM1 links mycobacterial recognition via TLR-MYD88 to autophagic defense [corrected].

Autophagy is an important defense mechanism against mycobacteria, the causative agents of tuberculosis. The molecular mechanisms that link mycobacterial recognition to autophagy remain unclear. Our analysis in zebrafish and human macrophage models of mycobacterial infection reveals that the DNA damage-regulated autophagy modulator DRAM1 functions downstream of pathogen recognition by the Toll-like receptor (TLR)/interleukin-1 receptor (IL1R)-MYD88-NF-κB innate immune sensing pathway to activate selective autophagy.

Hypoxia inducible factor signaling modulates susceptibility to mycobacterial infection via a nitric oxide dependent mechanism.

Tuberculosis is a current major world-health problem, exacerbated by the causative pathogen, Mycobacterium tuberculosis (Mtb), becoming increasingly resistant to conventional antibiotic treatment. Mtb is able to counteract the bactericidal mechanisms of leukocytes to survive intracellularly and develop a niche permissive for proliferation and dissemination. Understanding of the pathogenesis of mycobacterial infections such as tuberculosis (TB) remains limited, especially for early infection and for reactivation of latent infection.

Real-time imaging and genetic dissection of host-microbe interactions in zebrafish.

Many aspects of host interactions with microbes can only be studied in the context of a whole organism. The zebrafish as a model organism has shown to be highly successful for studies of infection biology and the interactions of commensal microbiota with their hosts. Zebrafish are transparent during embryo and larval development and these early life stages are optimally suited for high-resolution imaging of host-microbe interactions in a vertebrate organism.

Functional analysis of a zebrafish myd88 mutant identifies key transcriptional components of the innate immune system.

Toll-like receptors (TLRs) are an important class of pattern recognition receptors (PRRs) that recognize microbial and danger signals. Their downstream signaling upon ligand binding is vital for initiation of the innate immune response. In human and mammalian models, myeloid differentiation factor 88 (MYD88) is known for its central role as an adaptor molecule in interleukin 1 receptor (IL-1R) and TLR signaling.

Pathogen recognition and activation of the innate immune response in zebrafish.

The zebrafish has proven itself as an excellent model to study vertebrate innate immunity. It presents us with possibilities for in vivo imaging of host-pathogen interactions which are unparalleled in mammalian model systems. In addition, its suitability for genetic approaches is providing new insights on the mechanisms underlying the innate immune response.