Laser interstitial thermal therapy (LITT) is a minimally invasive treatment for brain tumors that are recurrent or surgically inaccessible. We developed a murine model of LITT to investigate its effects on tumor burden, immune activation, and delivery of heat-activated therapeutics. We engineered a preclinical LITT system using a 1064-nm laser coupled to a 400-μm fiber-optic probe. Orthotopic gliomas were established in the right frontal cortex of BL6 mice using luciferase-transduced glioma cells. Ten days post-implantation, mice were treated with LITT (0.45 or 0.75 W). Tumor response and blood–brain barrier (BBB) disruption were assessed using bioluminescence imaging (BLI), Evans Blue dye, and histology at 3, 7, and 14 days post-treatment. Immunofluorescence (IF) staining characterized immune cell activation. The distribution of doxorubicin released from intravenously administered Thermodox® was also evaluated. LITT disrupted the BBB, enabling Evans Blue dye and doxorubicin penetration up to 4 mm from the probe. Tumor burden was reduced by LITT, as shown by decreased hypercellularity on H E and reduced BLI signal, while sham-treated mice showed tumor progression. A reproducible ablation zone formed at the probe site. IF revealed increased IBA1 + macrophages and T cell infiltration in LITT-treated brains. Thermodox®-derived doxorubicin distribution correlated with thermal diffusion and matched a Fickian perfusion model. We present a reproducible preclinical model of LITT that enables investigation of tumor ablation, immune modulation, and thermally triggered drug delivery. These findings support the use of LITT as a platform for combinatorial strategies in glioma treatment.

Objective:To manufacture and characterize a modified niclosamide stearate (NS) prodrug therapeutic (mNSPT) for use in a small clinical trial in a metastatic canine osteosarcoma (OS) model. Animals:10 dogs that presented for treatment of nondetectable metastatic OS underwent resection of primary tumors prior to systemic therapy. Four cycles of IV carboplatin (300 mg/m2, IV, q 3 wk) followed by 4 cycles of the experimental mNSPT (10 mg/kg, IV, weekly). Posttreatment surveillance included physical examination and thoracic radiographs every 3 months for 2 years. Samples for pharmacokinetic analysis were taken at the end of the 0.5- to 1-hour IV infusion of the mNSPTs and followed for 2 hours. Clinical Presentation:The NS average concentration at the end of infusion was 134.88 ± 13.32 μg/mL; the average area under the curve was 211.62 ± 27.89 h·µg/mL. The niclosamide concentration at the end of infusion was 23.11 μg/mL ± 3.77 μg/mL, and the area under the curve was 27.52 ± 5.92 h·µg/mL, well above the NSPT 0.75 μg/mL (1.27 μM) cell-effective concentrations for OS cells in culture. The average terminal half-life was 4.57 hours for NS and 3.23 hours for niclosamide. Three dogs developed metastatic disease on carboplatin and did not receive mNSPT. The median time to tumor progression and OS of the 7 treated dogs was 510 and 632 days, respectively, with 3 dogs living > 4 years. Results:The results support further translational investigation of this novel therapeutic approach to OS treatment in a randomized, prospective phase III study in dogs and, if successful, ultimately in OS patients. Clinical Relevance:These results suggest that niclosamide-when transformed into the highly bioavailable NSPT-may have potential as a novel therapeutic agent for treating OS.

Tumor Ablation and Immune Microenvironment Modulation Following Laser Interstitial Thermal Therapy in a Murine Glioblastoma Model Ashley Puentes, Prazwal Athukuri, MD, Karina V. Moreno, Yuhui Yang, MS, Malcolm F. MacDonald, Anantha Marisetty, PhD, Sungho Lee, MD, Khatri Latha, PhD, David Needham, PhD, DSc, Ganesh Rao, MD Glioblastoma (GBM) is an aggressive brain tumor with limited treatment options, particularly when surgical resection is not feasible. Laser interstitial thermal therapy (LITT) is a minimally invasive technique that delivers focused thermal ablation to tumor tissue. We evaluated the efficacy and immunological effects of LITT using a murine GBM model. C57BL/6 mice were orthotopically implanted with GL261-luciferase cells in the right frontal cortex. Five days post-implantation, mice underwent LITT or Sham treatment (laser fiber placement without activation). LITT was administered using a 1064-nm laser probe with thermal regulation maintained at 46°C. Tumor progression was monitored via bioluminescent imaging (BLI), revealing significant signal reductions at days 3, 7, and 14 in LITT-treated mice, whereas Sham controls exhibited progressive tumor growth. H&E staining confirmed well-demarcated ablation zones with central necrosis. Immunofluorescence analyses showed increased activation of Iba1+ microglia/macrophages and infiltration of CD3+, CD4+, and CD8+ T cells following LITT, especially at early time points. LITT also disrupted the blood-brain barrier, as evidenced by Evans blue dye extravasation. Survival analysis demonstrated a significant benefit for LITT-treated mice compared to Sham controls (p = 0.0287). These findings establish LITT as an effective approach for reducing tumor burden and promoting immune cell infiltration in a preclinical GBM model. The observed microglial activation and T cell recruitment suggest that LITT may enhance responsiveness to immunotherapy, particularly checkpoint inhibitors. This combinatorial strategy may offer new therapeutic opportunities for GBM, especially in cases where surgical resection is not feasible.

MOTIVATION:Many cancers overexpress low-density lipoprotein receptors (LDLR), facilitating cholesterol metabolism for tumour growth. Targeting LDLR offers a promising strategy for selective drug delivery. Orlistat, a fatty acid synthase (FAS) inhibitor, has shown anti-cancer potential, particularly in tumours with high FAS expression. This study introduces an LDLR-Orlistat Targeted Nanoparticles (LDLR-OTNs) to enhance cancer cell uptake via LDLR-mediated endocytosis. The objectives include synthesizing lipid-based orlistat nanoparticles, functionalizing them with an 11-mer LDLR-binding peptide, assessing uptake and cytotoxicity in three LDLR- and FAS-expressing breast cancer cell lines (BT-474, MDA MB 453, MCF-7), and comparing uptake kinetics with non-targeted nanoparticles. METHODS:Orlistat nanoparticles (ONs) were synthesised via rapid solvent exchange, producing uncoated ONs, POPC-coated ONs (POPC-ONs), and LDLR-targeted ONs (LDLR-OTNs). Targeting was achieved by conjugating an 11-mer binding peptide (RLTRKRGLKLA) to DSPE-PEG5000 maleimide via click chemistry, confirmed by Ellman's test. Nanoparticles were characterised using DLS and TEM. Cellular uptake over 24 hours was assessed using fluorescence-labelled POPC-ONs and LDLR-OTNs, and uptake kinetics were analysed. Suramin-blocking studies were used to confirm LDLR-mediated uptake. A 48-hour cytotoxicity assay quantified IC50 values in the aforementioned cell lines. RESULTS:TEM data showed that LDLR-OTNs (33 nm) were smaller than untargeted POPC-ONs (58 nm) and uncoated ONs (67 nm). Ellman's test confirmed > 99.2% peptide conjugation. Cellular uptake of LDLR-OTNs was rapid, with significant fluorescence by 1 hour and a kinetic plateau at 24-48 hours, with data fitting to a modified exponential model, while that of untargeted POPC-ONs had lower initial uptake, following a logistic model. Suramin blocking reduced LDLR-OTN uptake, confirming receptor-mediated entry. Cytotoxicity assays yielded IC50 values of 23.8 µM (BT-474), 25.8 µM (MDA MB 453), and 8.2 µM (MCF-7), with maximal inhibition at 48 h. CONCLUSIONS:LDLR-OTNs demonstrated receptor-mediated uptake and potent cytotoxicity in LDLR- and FAS- overexpressing breast cancer cells. These findings support LDLR-targeted nanoparticles as a promising approach for delivering FAS inhibitors to LDLR-rich tumours, meriting further investigation in targeted cancer therapy development.

My contribution to honoring Professor Kinam Park celebrates and resonates with his scholarly career in drug delivery, his commitment to encouraging the next generation(s), and his efforts to keep us focused on clinically effective formulations. To do this I take as my example, niclosamide, a small molecule protonophore that, uniquely, can “target” all cell membranes, both plasma and organelle. As such, it acts upstream of many cell pathways and so has the potential to affect many of the essential events that a cell, and particularly a diseased cell or other entities like a virus, use to stay alive and prosper. Literature shows that it has so far been discovered to positively influence (at least): cancer, bacterial and viral infection, metabolic diseases such as Type II diabetes, NASH and NAFLD, artery constriction, endometriosis, neuropathic pain, rheumatoid arthritis, sclerodermatous graft-versus-host disease, systemic sclerosis, Parkinson's, and COPD. With such a fundamental action and broad-spectrum activity, I believe that studying niclosamide in all its manifestations, discovering if and to what extent it can contribute positively to disease control (and also where it can't), formulating it as effective therapeutics, and testing them in preclinical and clinical trials is a career builder for our next generation(s).The article is divided into two parts: Part I introduces niclosamide and other proton shunts mainly in cancer and viral infections and reviews an exponentially growing literature with some concepts and physicochemical properties that lead to its proton shunt mechanism. Part II focuses on repurposing by reformulation of niclosamide. I give two examples of “carrier-free formulations”, — one for cancer (as a prodrug therapeutic of niclosamide stearate for i.v. and other administration routes, exemplified by our recent work on Osteosarcoma in mice and canine patients), and the other as a niclosamide solution formulation (that could provide the basis for a preventative nasal spray and early treatment option for COVID19 and other respiratory virus infections).My goal is to excite and enthuse, encourage, and motivate all involved in the drug development and testing process in academia, institutes, and industry, to learn more about this interesting molecule and others like it. To enable such endeavors, I give many proposed ideas throughout the document, that have been stimulated and inspired by gaps in the literature, urgent needs in disease, and new studies arising from our own work. The hope is that, by reading through this document and studying the suggested topics and references, the drug delivery and development community will continue our lineage and benefit from our legacy to achieve niclosamide's potential as an effective contributor to the treatment and control of many diseases and conditions.

My contribution to honoring Professor Kinam Park celebrates and resonates with his scholarly career in drug delivery, his commitment to encouraging the next generation(s), and his efforts to keep us focused on clinically effective formulations. To do this I take as my example, niclosamide, a small molecule protonophore that, uniquely, can "target" all cell membranes, both plasma and organelle. As such, it acts upstream of many cell pathways and so has the potential to affect many of the essential events that a cell, and particularly a diseased cell or other entities like a virus, use to stay alive and prosper. Literature shows that it has so far been discovered to positively influence (at least): cancer, bacterial and viral infection, metabolic diseases such as Type II diabetes, NASH and versus-host disease, systemic sclerosis, Parkinson's, and COPD. With such a fundamental action and broadspectrum activity, I believe that studying niclosamide in all its manifestations, discovering if and to what extent it can contribute positively to disease control (and also where it can't), formulating it as effective therapeutics, and testing them in preclinical and clinical trials is a career builder for our next generation(s). The article is divided into two parts: Part I introduces niclosamide and other proton shunts mainly in cancer and viral infections and reviews an exponentially growing literature with some concepts and physicochemical properties that lead to its proton shunt mechanism. Part II focuses on repurposing by reformulation of niclosamide. I give two examples of "carrier-free formulations", - one for cancer (as a prodrug therapeutic of niclosamide stearate for i.v. and other administration routes, exemplified by our recent work on Osteosarcoma in mice and canine patients), and the other as a niclosamide solution formulation (that could provide the basis for a preventative nasal spray and early treatment option for COVID19 and other respiratory virus infections). My goal is to excite and enthuse, encourage, and motivate all involved in the drug development and testing process in academia, institutes, and industry, to learn more about this interesting molecule and others like it. To enable such endeavors, I give many proposed ideas throughout the document, that have been stimulated and inspired by gaps in the literature, urgent needs in disease, and new studies arising from our own work. The hope is that, by reading through this document and studying the suggested topics and references, the drug delivery and development community will continue our lineage and benefit from our legacy to achieve niclosamide's potential as an effective contributor to the treatment and control of many diseases and conditions. (c) 2023 Elsevier B.V. All rights reserved.

My contribution to honoring Professor Kinam Park celebrates and resonates with his scholarly career in drug delivery, his commitment to encouraging the next generation(s), and his efforts to keep us focused on clinically effective formulations. To do this I take as my example, niclosamide, a small molecule protonophore that, uniquely, can "target" all cell membranes, both plasma and organelle. As such, it acts upstream of many cell pathways and so has the potential to affect many of the essential events that a cell, and particularly a diseased cell or other entities like a virus, use to stay alive and prosper. Literature shows that it has so far been discovered to positively influence (at least): cancer, bacterial and viral infection, metabolic diseases such as Type II diabetes, NASH and NAFLD, artery constriction, endometriosis, neuropathic pain, rheumatoid arthritis, sclerodermatous graft-versus-host disease, systemic sclerosis, Parkinson's, and COPD. With such a fundamental action and broad-spectrum activity, I believe that studying niclosamide in all its manifestations, discovering if and to what extent it can contribute positively to disease control (and also where it can't), formulating it as effective therapeutics, and testing them in preclinical and clinical trials is a career builder for our next generation(s). The article is divided into two parts: Part I introduces niclosamide and other proton shunts mainly in cancer and viral infections and reviews an exponentially growing literature with some concepts and physicochemical properties that lead to its proton shunt mechanism. Part II focuses on repurposing by reformulation of niclosamide. I give two examples of "carrier-free formulations", - one for cancer (as a prodrug therapeutic of niclosamide stearate for i.v. and other administration routes, exemplified by our recent work on Osteosarcoma in mice and canine patients), and the other as a niclosamide solution formulation (that could provide the basis for a preventative nasal spray and early treatment option for COVID19 and other respiratory virus infections). My goal is to excite and enthuse, encourage, and motivate all involved in the drug development and testing process in academia, institutes, and industry, to learn more about this interesting molecule and others like it. To enable such endeavors, I give many proposed ideas throughout the document, that have been stimulated and inspired by gaps in the literature, urgent needs in disease, and new studies arising from our own work. The hope is that, by reading through this document and studying the suggested topics and references, the drug delivery and development community will continue our lineage and benefit from our legacy to achieve niclosamide's potential as an effective contributor to the treatment and control of many diseases and conditions.

AVI file - 34.5MB, Real-time intravascular release of doxorubicin from Dox-TSL and subsequent redistribution of drug in B16 melanoma tumor tissue. The video shows drug (red) delivered over the first 20min, at 20x magnification. The eNOS-GFPtg mouse model was used in this experiment, so the blood vessels are green. (Download before playing in IE8)

The gamma-interferon (IFNγ)-inducible guanylate-binding proteins (GBPs) promote host defense against gram-negative cytosolic bacteria in part through the induction of an inflammatory cell death pathway called pyroptosis. To activate pyroptosis, GBPs facilitate sensing of the gram-negative bacterial outer membrane component lipopolysaccharide (LPS) by the noncanonical caspase-4 inflammasome. There are seven human GBP paralogs, and it is unclear how each GBP contributes to LPS sensing and pyroptosis induction. GBP1 forms a multimeric microcapsule on the surface of cytosolic bacteria through direct interactions with LPS. The GBP1 microcapsule recruits caspase-4 to bacteria, a process deemed essential for caspase-4 activation. In contrast to GBP1, closely related paralog GBP2 is unable to bind bacteria on its own but requires GBP1 for direct bacterial binding. Unexpectedly, we find that GBP2 overexpression can restore gram-negative-induced pyroptosis in GBP1 KO cells, without GBP2 binding to the bacterial surface. A mutant of GBP1 that lacks the triple arginine motif required for microcapsule formation also rescues pyroptosis in GBP1 KO cells, showing that binding to bacteria is dispensable for GBPs to promote pyroptosis. Instead, we find that GBP2, like GBP1, directly binds and aggregates “free” LPS through protein polymerization. We demonstrate that supplementation of either recombinant polymerized GBP1 or GBP2 to an in vitro reaction is sufficient to enhance LPS-induced caspase-4 activation. This provides a revised mechanistic framework for noncanonical inflammasome activation where GBP1 or GBP2 assembles cytosol-contaminating LPS into a protein-LPS interface for caspase-4 activation as part of a coordinated host response to gram-negative bacterial infections.

Abstract Motivation The low solubility, weak acid drug, niclosamide is a host cell modulator with broad-spectrum anti-viral cell-activity against many viruses, including stopping the SARS-CoV-2 virus from infecting cells in cell culture. As a result, a simple universal nasal spray preventative was proposed and investigated in earlier work regarding the dissolution of niclosamide into simple buffers. However, starting with pharmaceutical grade, niclosamide represents a new 505(b)(2) application. The motivation for this second paper in the series was therefore to explore if and to what extent niclosamide could be extracted from commercially available and regulatory-approved niclosamide oral tablets that could serve as a preventative nasal spray and an early treatment oral/throat spray, with possibly more expeditious testing and regulatory approval. Experimental Measurements of supernatant niclosamide concentrations were made by calibrated UV-Vis for the dissolution of niclosamide from commercially available Yomesan crushed into a powder for dissolution into Tris Buffer (TB) solutions. Parameters tested were as follows: time (0–2 days), concentration (300 µM to -1 mM), pH (7.41 to 9.35), and anhydrous/hydrated state. Optical microscopy was used to view the morphologies of the initial crushed powder, and the dissolving and equilibrating undissolved excess particles to detect morphologic changes that might occur. Results Concentration dependence: Niclosamide was readily extracted from powdered Yomesan at pH 9.34 TB at starting Yomesan niclosamide equivalents concentrations of 300 µM, 600 µM, and 1 mM. Peak dissolved niclosamide supernatant concentrations of 264 µM, 216 µM, and 172 µM were achieved in 1 h, 1 h, and 3 h respectively. These peaks though were followed by a reduction in supernatant concentration to an average of 112.3 µM ± 28.4 µM after overnight stir on day 2. pH dependence: For nominal pHs of 7.41, 8.35, 8.85, and 9.35, peak niclosamide concentrations were 4 µM, 22.4 µM, 96.2 µM, and 215.8 µM, respectively. Similarly, the day 2 values all reduced to 3 µM, 12.9 µM, 35.1 µM, and 112.3 µM. A heat-treatment to 200 °C dehydrated the niclosamide and showed a high 3 h concentration (262 µM) and the least day-2 reduction (to 229 µM). This indicated that the presence, or formation during exposure to buffer, of lower solubility polymorphs was responsible for the reductions in total solubilities. These morphologic changes were confirmed by optical microscopy that showed initially featureless particulate-aggregates of niclosamide could grow multiple needle-shaped crystals and form needle masses, especially in the presence of Tris-buffered sodium chloride, where new red needles were rapidly made. Scale up: A scaled-up 1 L solution of niclosamide was made achieving 165 µM supernatant niclosamide in 3 h by dissolution of just one fifth (100 mg niclosamide) of a Yomesan tablet. Conclusion These comprehensive results provide a guide as to how to utilize commercially available and approved tablets of niclosamide to generate aqueous niclosamide solutions from a simple dissolution protocol. As shown here, just one 4-tablet pack of Yomesan could readily make 165 L of a 20 µM niclosamide solution giving 16,500 10 mL bottles. One million bottles, from just 60 packs of Yomesan, would provide 100 million single spray doses for distribution to mitigate a host of respiratory infections as a universal preventative-nasal and early treatment oral/throat sprays throughout the world. Graphical Abstract pH dependence of niclosamide extraction from crushed Yomesan tablet material into Tris buffer (yellow-green in vial) and Tris-buffered saline solution (orange-red in vial). Initial anhydrous dissolution concentration is reduced by overnight stirring to likely monohydrate niclosamide; and is even lower if in TBSS forming new niclosamide sodium needle crystals grown from the original particles.

Supplementary Materials including Text and Data

The story starts in Basel at CLINAM in 2013, when I asked Pieter about making nanoparticles and he advised me to “try this solvent-exchange method we have developed for making limit sized particles”. We are particularly interested in what are “limit size materials” because we want to test the feasibility of an idea: could we design, make, develop, and test the concept for treating metastatic cancer by, “Putting the Drug in the Cancer’s Food? “Limit size” is the size of the cancer‘s food, ? the common Low Density Lipoprotein, (LDL) ~20 nm diameter. In this contribution to Pieter’s LTAA we focus on the “bottom” (nucleation) and the “up” (growth) of “bottom-up design” as it applies to homogeneous nucleation of especially, hydrophobic drugs and the 8 physico-chemical stages and associated parameters that determine the initial size, and any subsequent coarsening, of a nanoparticle suspension. We show that, when made by the rapid solvent-exchange method, the same sized particles can be obtained without phospholipid. Furthermore, the obtained size follows the predictions of classic nucleation theory when the appropriate values for the parameters (surface tension and supersaturation) at nucleation are included. Calculations on dissolution time for nanoparticles reveal that a typical fewmicromolar-solubility, hydrophobic, anti-cancer drug (like Lapatinib, Niclosamide, Abiraterone, and Fulvestrant) of 500 nm diameter would take between 3?7 s to dissolve in an infinite sink like the blood stream; and a 50 nm particle would dissolve in less than a second! And so the nanoparticle design requires a highly water-insoluble drug, and a tight, encapsulating, impermeable lipid:cholesterol monolayer. While the “Y” junction can be used to mix an ethanolic solution with anti-solvent, we find that a “no-junction” can give equally good results. A series of nanoparticles (DiI-fluorescently labeled Triolein-cored and drug-cored nanoparticles of Orlistat) were then tested in well-characterized cell lines for uptake and efficacy as well as a PET-imageable nanoparticle in initial PET-imaging studies in animals for EPR uptake and tumor detection. We show that, while free-drug cannot be optimally administered in vivo, a nanoparticle formulation of orlistat could in principle represent a stable parenteral delivery system. The article ends with a brief discussion of what we see as the way forward in Individualized Medicine from the Diagnostic-Therapeutic (“Diapeutic”) side, requiring 18FDG detection of metastatic lesions, functional imaging of a protein target (e.g. Fatty Acid Synthase) using 11C acetate, then a PET (or other)-imageable nanoparticle to demonstrate EPR accumulation, and then the administration of the pure-drug nanoparticle taken in by the most aggressive cancer cells in the perivascular space, as they would their “food”.

AVI file - 41.7MB, Real-time drug delivery of free doxorubicin and Dox-TSL in heated FaDu tumor tissue. The blood vessels are highlighted in green and drug is red. The video shows drug delivered over the first 20min, at 20x magnification. Free drug quickly disperses throughout the tissue and then is reabsorbed into the vasculature, leaving a low drug concentration behind in the tumor cells. In the Dox-TSL treated tissue, drug is delivered uniformly across the tumor tissue, with visible uptake in tumor and endothelial cell nuclei. Drug in the Dox-TSL treated mouse continues to accumulate in the tumor tissue over the 20min period. (Download before playing in IE8)

In the second part of this series of papers, we address the same Cauchy problem that was considered in part 1, namely the nonlocal Fisher-KPP equation in one spatial dimension, \[ u_t = D u_{xx} + u(1-\phi*u), \] where $\phi*u$ is a spatial convolution with the top hat kernel, $\phi(y) \equiv H\left(\frac{1}{4}-y^2\right)$, except that now the spatial domain is the finite interval $[0,a]$ rather than the whole real line. Consequently boundary conditions are required at the interval end-points, and we address the situations when these boundary conditions are of either Dirichlet or Neumann type. This model forms a natural extension to the classical Fisher-KPP model, with the introduction of the simplest possible nonlocal effect into the saturation term. Nonlocal reaction-diffusion models arise naturally in a variety of (frequently biological or ecological) contexts, and as such it is of fundamental interest to examine its properties in detail, and to compare and contrast these with the well known properties of the classical Fisher-KPP model.

Metabolic reprogramming, through increased uptake of cholesterol in the form of low-density lipoproteins (LDL), is one way by which cancer cells, including high grade gliomas (HGG), maintain their rapid growth. In this study, we determined LDL receptor (LDLR) expression in HGGs using immunohistochemistry on tissue microarrays from intra- and inter tumour regions of 36 adult and 133 paediatric patients to confirm LDLR as a therapeutic target. Additionally, we analysed expression levels in three representative cell line models to confirm their future utility to test LDLR-targeted nanoparticle uptake, retention, and cytotoxicity. Our data show widespread LDLR expression in adult and paediatric cohorts, but with significant intra-tumour variation observed between the core and either rim or invasive regions of adult HGG. Expression was independent of paediatric tumour grade or identified clinicopathological factors. LDLR-expressing tumour cells localized preferentially within perivascular niches, also with significant adult intra-tumour variation. We demonstrated variable levels of LDLR expression in all cell lines, confirming their suitability as models to test LDLR-targeted nanotherapy delivery. Overall, our study reveals the LDLR pathway as a ubiquitous metabolic vulnerability in high grade gliomas across all ages, amenable to future consideration of LDL-mediated nanoparticle/drug delivery to potentially circumvent tumour heterogeneity.

Sensing and killing of intracellular bacterial pathogens are important features of cell-autonomous immunity. The cytokine gamma-interferon (IFNγ) enhances cell-autonomous immunity through upregulation of interferon stimulated genes such as guanylate binding proteins (GBPs). GBPs promote defense against Gram-negative cytosolic bacteria in part through the induction of an inflammatory cell death pathway called pyroptosis. To activate pyroptosis, GBPs facilitate caspase-4 sensing of the Gram-negative bacterial outer membrane component lipopolysaccharide (LPS). There are seven human GBP paralogs and it is unclear how each GBP contributes to LPS sensing and pyroptosis induction. GBP1 forms a multimeric microcapsule on the surface of cytosolic bacteria through direct interactions with LPS and recruits caspase-4 to bacteria, a process deemed essential for caspase-4 activation. In contrast to GBP1, closely related paralog GBP2 is unable to bind bacteria on its own but requires GBP1 for direct bacterial binding. Unexpectedly, we find that GBP2 overexpression can restore Gram-negative-induced pyroptosis in GBP1 KO cells, without GBP2 binding to the bacterial surface. A mutant of GBP1 that lacks the triple arginine motif required for microcapsule formation also rescues pyroptosis in GBP1 KO cells, showing that binding to bacteria is dispensable for GBPs to promote pyroptosis. Instead, we find that GBP2, like GBP1, directly binds and aggregates ‘free’ LPS through protein polymerization. This provides a novel mechanistic framework for non-canonical inflammasome activation where GBP1 or GBP2 assemble cytosol-contaminating LPS into a protein-LPS interface for caspase-4 activation as part of a coordinated host response to Gram-negative bacterial infections. Significance Statement Sensing Gram-negative bacterial lipopolysaccharide by human caspase-4 is critical for host defense to intracellular Gram-negative bacterial pathogens. Human guanylate binding proteins (GBPs) facilitate caspase-4 activation in response to Gram-negative infections by a poorly understood mechanism. The prevailing model suggests GBP1 binding to bacteria and consequential recruitment of caspase-4 to the bacterial surface are essential for triggering this host response. Here, we show GBP1 binding to bacteria is dispensable for caspase-4 activation and identify GBP2 as an additional lipopolysaccharide-binding protein that can functionally replace GBP1. We demonstrate that GBP1 and GBP2 share the ability to form lipopolysaccharide-protein complexes, which, we propose, allow caspase-4 activation. Our study provides a new mechanistic framework for cytosolic LPS sensing.

In Part II of this series of papers, we consider an initial-boundary value problem for the Kolmogorov-Petrovskii-Piscounov (KPP)-type equation with a discontinuous cut-off in the reaction function at concentration u=uc. For fixed cut-off value uc is an element of(0,1), we apply the method of matched asymptotic coordinate expansions to obtain the complete large-time asymptotic form of the solution, which exhibits the formation of a permanent form traveling wave (PTW) structure. In particular, this approach allows the correction to the wave speed and the rate of convergence of the solution onto the PTW to be determined via a detailed analysis of the asymptotic structures in small time and, subsequently, in large space. The asymptotic results are confirmed against numerical results obtained for the particular case of a cut-off Fisher reaction function.

Chlamydia trachomatis, an obligate intracellular bacterium with limited metabolic capabilities, possesses the futalosine pathway for menaquinone biosynthesis. Futalosine pathway enzymes have promise as narrow-spectrum antibiotic targets, but the activity and essentiality of chlamydial menaquinone biosynthesis have yet to be established. In this work, menaquinone-7 (MK-7) was identified as a C. trachomatis-produced quinone through liquid chromatography-tandem mass spectrometry. An immunofluorescence-based assay revealed that treatment of C. trachomatis-infected HeLa cells with the futalosine pathway inhibitor docosahexaenoic acid (DHA) reduced inclusion number, inclusion size, and infectious progeny. Supplementation with MK-7 nanoparticles rescued the effect of DHA on inclusion number, indicating that the futalosine pathway is a target of DHA in this system. These results open the door for menaquinone biosynthesis inhibitors to be pursued in antichlamydial development.

ABSTRACT Chlamydia trachomatis, an obligate intracellular bacterium with limited metabolic capabilities, possesses the futalosine pathway for menaquinone biosynthesis. Futalosine pathway enzymes have promise as narrow spectrum targets, but the activity and essentiality of chlamydial menaquinone biosynthesis have yet to be established. In this work, menaquinone-7 (MK-7) was identified as a C. trachomatis -produced quinone through LC-MS/MS. An immunofluorescence-based assay revealed that treatment of C. trachomatis -infected HeLa cells with futalosine pathway inhibitor docosahexaenoic acid (DHA) reduced inclusion number, inclusion size, and infectious progeny. Supplementation with MK-7 nanoparticles rescued the effect of DHA on inclusion number, indicating that the futalosine pathway is a target of DHA in this system. These results open the door for menaquinone biosynthesis inhibitors to be pursued in antichlamydial development.

Mesenchymal stem cells are the focus of intense research in bone development and regeneration. The potential of microparticles as modulating moieties of osteogenic response by utilizing their architectural features is demonstrated herein. Topographically textured microparticles of varying microscale features are produced by exploiting phase-separation of a readily soluble sacrificial component from polylactic acid. The influence of varying topographical features on primary human mesenchymal stem cell attachment, proliferation and markers of osteogenesis is investigated. In the absence of osteoinductive supplements, cells cultured on textured microparticles exhibit notably increased expression of osteogenic markers relative to conventional smooth microparticles. They also exhibit varying morphological, attachment and proliferation responses. Significantly altered gene expression and metabolic profiles are observed, with varying histological characteristics in vivo. This study highlights how tailoring topographical design offers cell-instructive 3D microenvironments which allow manipulation of stem cell fate by eliciting the desired downstream response without use of exogenous osteoinductive factors.