Jennifer Lin

All Publications

• The activity of antimicrobial peptoids against multidrug-resistant ocular pathogens. Contact lens & anterior eye : the journal of the British Contact Lens Association Sara, M., Yasir, M., Kalaiselvan, P., Hui, A., Kuppusamy, R., Kumar, N., Chakraborty, S., Yu, T. T., Wong, E. H., Molchanova, N., Jenssen, H., Lin, J. S., Barron, A. E., Willcox, M. 2024: 102124

  Abstract

  BACKGROUND: Ocular infections caused by antibiotic-resistant pathogens can result in partial or complete vision loss. The development of pan-resistant microbial strains poses a significant challenge for clinicians as there are limited antimicrobial options available. Synthetic peptoids, which are sequence-specific oligo-N-substituted glycines, offer potential as alternative antimicrobial agents to target multidrug-resistant bacteria.METHODS: The antimicrobial activity of synthesised peptoids against multidrug-resistant (MDR) ocular pathogens was evaluated using the microbroth dilution method. Hemolytic propensity was assessed using mammalian erythrocytes. Peptoids were also incubated with proteolytic enzymes, after which their minimum inhibitory activity against bacteria was re-evaluated.RESULTS: Several alkylated and brominated peptoids showed good inhibitory activity against multidrug-resistant Pseudomonas aeruginosa strains at concentrations of ≤15mugmL-1 (≤12M). Similarly, most brominated compounds inhibited the growth of methicillin-resistant Staphylococcus aureus at 1.9 to 15mugmL-1 (12M). The N-terminally alkylated peptoids caused less toxicity to erythrocytes. The peptoid denoted as TM5 had a high therapeutic index, being non-toxic to either erythrocytes or corneal epithelial cells, even at 15 to 22 times its MIC. Additionally, the peptoids were resistant to protease activity.CONCLUSIONS: Peptoids studied here demonstrated potent activity against various multidrug-resistant ocular pathogens. Their properties make them promising candidates for controlling vision-related morbidity associated with eye infections by antibiotic-resistant strains.

  View details for DOI 10.1016/j.clae.2024.102124

  View details for PubMedID 38341309

• Antiviral effect of peptoids on hepatitis B virus infection in cell culture. Antiviral research Murayama, A., Hitomi, I., Yamada, N., Aly, H. H., Molchanova, N., Lin, J. S., Nishitsuji, H., Shimotohno, K., Muramatsu, M., Barron, A. E., Kato, T. 2024: 105821

  Abstract

  Although antimicrobial peptides have been shown to inactivate viruses through disruption of their viral envelopes, clinical use of such peptides has been hampered by a number of factors, especially their enzymatically unstable structures. To overcome the shortcomings of antimicrobial peptides, peptoids (sequence-specific N-substituted glycine oligomers) mimicking antimicrobial peptides have been developed. We aimed to demonstrate the antiviral effects of antimicrobial peptoids against hepatitis B virus (HBV) in cell culture. The anti-HBV activity of antimicrobial peptoids was screened and evaluated in an infection system involving the HBV reporter virus and HepG2.2.15-derived HBV. By screening with the HBV reporter virus infection system, three (TM1, TM4, and TM19) of 12 peptoids were identified as reducing the infectivity of HBV, though they did not alter the production levels of HBs antigen in cell culture. These peptoids were not cytotoxic at the evaluated concentrations. Among these peptoids, TM19 was confirmed to reduce HBV infection most potently in a HepG2.2.15-derived HBV infection system that closely demonstrates authentic HBV infection. In cell culture, the most effective administration of TM19 was virus treatment at the infection step, but the reduction in HBV infectivity by pre-treatment or post-treatment of cells with TM19 was minimal. The disrupting effect of TM19 targeting infectious viral particles was clarified in iodixanol density gradient analysis. In conclusion, the peptoid TM19 was identified as a potent inhibitor of HBV. This peptoid prevents HBV infection by disrupting viral particles and is a candidate for a new class of anti-HBV reagents.

  View details for DOI 10.1016/j.antiviral.2024.105821

  View details for PubMedID 38272318

• Supramolecular Peptoid Structure Strengthens Complexation with Polyacrylic Acid Microgels. Biomacromolecules Zhao, W., Lin, J. S., Nielsen, J. E., Sørensen, K., Wadurkar, A. S., Ji, J., Barron, A. E., Nangia, S., Libera, M. R. 2024

  Abstract

  We have studied the complexation between cationic antimicrobials and polyanionic microgels to create self-defensive surfaces that responsively resist bacterial colonization. An essential property is the stable sequestration of the loaded (complexed) antimicrobial within the microgel under a physiological ionic strength. Here, we assess the complexation strength between poly(acrylic acid) [PAA] microgels and a series of cationic peptoids that display supramolecular structures ranging from an oligomeric monomer to a tetramer. We follow changes in loaded microgel diameter with increasing [Na+] as a measure of the counterion doping level. Consistent with prior findings on colistin/PAA complexation, we find that a monomeric peptoid is fully released at ionic strengths well below physiological conditions, despite its +5 charge. In contrast, progressively higher degrees of peptoid supramolecular structure display progressively greater resistance to salting out, which we attribute to the greater entropic stability associated with the complexation of multimeric peptoid bundles.

  View details for DOI 10.1021/acs.biomac.3c01242

  View details for PubMedID 38240722

• Between Good and Evil: Complexation of the Human Cathelicidin LL-37 and Nucleic Acids. Biophysical journal Zielke, C., Nielsen, J. E., Lin, J. S., Barron, A. E. 2023

  Abstract

  The innate immune system provides a crucial first line of defense against invading pathogens attacking the body. As the only member of the human cathelicidin family, the antimicrobial peptide LL-37 has been shown to have antiviral, antifungal, and antibacterial properties. In complexation with nucleic acids, LL-37 is suggested to maintain its beneficial health effects while also acting as a condensation agent for the nucleic acid. Complexes formed by LL-37 and nucleic acids have been shown to be immunostimulatory with a positive impact on the human innate immune system. However, some studies also suggest that in some circumstances, LL-37/nucleic acid complexes may be a contributing factor to autoimmune disorders such as psoriasis and systemic lupus erythematosus. This review provides a comprehensive discussion of research highlighting the beneficial health effects of LL-37/nucleic acid complexes, as well as discussing observed detrimental effects. We will emphasize why it is important to investigate and elucidate structural characteristics, such as condensation patterns of nucleic acids within complexation, and their mechanisms of action, to shed light on the intricate physiological effects of LL-37 and the seemingly contradictory role of LL-37/nucleic acid complexes in the innate immune response.

  View details for DOI 10.1016/j.bpj.2023.10.035

  View details for PubMedID 37919905

• The anti-inflammatory effects of photobiomodulation are mediated by cytokines: Evidence from a mouse model of inflammation. Frontiers in neuroscience Shamloo, S., Defensor, E., Ciari, P., Ogawa, G., Vidano, L., Lin, J. S., Fortkort, J. A., Shamloo, M., Barron, A. E. 2023; 17: 1150156

  Abstract

  There is an urgent need for therapeutic approaches that can prevent or limit neuroinflammatory processes and prevent neuronal degeneration. Photobiomodulation (PBM), the therapeutic use of specific wavelengths of light, is a safe approach shown to have anti-inflammatory effects. The current study was aimed at evaluating the effects of PBM on LPS-induced peripheral and central inflammation in mice to assess its potential as an anti-inflammatory treatment. Daily, 30-min treatment of mice with red/NIR light (RL) or RL with a 40 Hz gamma frequency flicker for 10 days prior to LPS challenge showed anti-inflammatory effects in the brain and systemically. PBM downregulated LPS induction of key proinflammatory cytokines associated with inflammasome activation, IL-1β and IL-18, and upregulated the anti-inflammatory cytokine, IL-10. RL provided robust anti-inflammatory effects, and the addition of gamma flicker potentiated these effects. Overall, these results demonstrate the potential of PBM as an anti-inflammatory treatment that acts through cytokine expression modulation.

  View details for DOI 10.3389/fnins.2023.1150156

  View details for PubMedID 37090796

  View details for PubMedCentralID PMC10115964

• Membrane-acting biomimetic peptoids against visceral leishmaniasis. FEBS open bio Kumar, V., Lin, J. S., Molchanova, N., Fortkort, J. A., Reckmann, C., Brase, S., Jenssen, H., Barron, A. E., Chugh, A. 2023

  Abstract

  Visceral leishmaniasis (VL) is among the most neglected tropical diseases in the world. Drug cell permeability is essential for killing the intracellular residing parasites responsible for VL, making cell-permeating peptides a logical choice to address VL. Unfortunately, the limited biological stability of peptides restricts their usage. Sequence-specific oligo-N-substituted glycines ("peptoids") are a class of peptide mimics that offers an excellent alternative to peptides in terms of ease of synthesis and good biostability. We tested peptoids against the parasite Leishmania donovani in both forms, i.e., intracellular amastigotes and promastigotes. N-alkyl hydrophobic chain addition (lipidation) and bromination of oligopeptoids yielded compounds with good anti-leishmanial activity against both forms, showing the promise of these antiparasitic peptoids as potential drug candidates to treat VL.

  View details for DOI 10.1002/2211-5463.13562

  View details for PubMedID 36683396

• Peptoid-Loaded Microgels Self-Defensively Inhibit Staphylococcal Colonization of Titanium in a Model of Operating-Room Contamination ADVANCED MATERIALS INTERFACES Zhao, W., Wang, H., Xiao, X., De Stefano, L., Katz, J., Lin, J. S., Barron, A. E., Schaer, T. P., Wang, H., Libera, M. 2022

  View details for DOI 10.1002/admi.202201662

  View details for Web of Science ID 000853143800001

• Anti-persister and Anti-biofilm Activity of Self-Assembled Antimicrobial Peptoid Ellipsoidal Micelles. ACS infectious diseases Lin, J. S., Bekale, L. A., Molchanova, N., Nielsen, J. E., Wright, M., Bacacao, B., Diamond, G., Jenssen, H., Santa Maria, P. L., Barron, A. E. 2022

  Abstract

  Although persister cells are the root cause of resistance development and relapse of chronic infections, more attention has been focused on developing antimicrobial agents against resistant bacterial strains than on developing anti-persister agents. Frustratingly, the global preclinical antibacterial pipeline does not include any anti-persister drug. Therefore, the central point of this work is to explore antimicrobial peptidomimetics called peptoids (sequence-specific oligo-N-substituted glycines) as a new class of anti-persister drugs. In this study, we demonstrate that one particular antimicrobial peptoid, the sequence-specific pentamer TM5, is active against planktonic persister cells and sterilizes biofilms formed by both Gram-negative and Gram-positive bacteria. Moreover, we demonstrate the potential of TM5 to inhibit cytokine production induced by lipopolysaccharides from Gram-negative bacteria. We anticipate that this work can pave the way to the development of new anti-persister agents based on antimicrobial peptoids of this class to simultaneously help address the crisis of bacterial resistance and reduce the occurrence of the relapse of chronic infections.

  View details for DOI 10.1021/acsinfecdis.2c00288

  View details for PubMedID 36018039

• Efficacy of Cathelicidin-Mimetic Antimicrobial Peptoids against Staphylococcus aureus. Microbiology spectrum Benjamin, A. B., Moule, M. G., Didwania, M. K., Hardy, J., Saenkham-Huntsinger, P., Sule, P., Nielsen, J. E., Lin, J. S., Contag, C. H., Barron, A. E., Cirillo, J. D. 2022: e0053422

  Abstract

  Staphylococcus aureus is one of the most common pathogens associated with infection in wounds. The current standard of care uses a combination of disinfection and drainage followed by conventional antibiotics such as methicillin. Methicillin and vancomycin resistance has rendered these treatments ineffective, often causing the reemergence of infection. This study examines the use of antimicrobial peptoids (sequence-specific poly-N-substituted glycines) designed to mimic naturally occurring cationic, amphipathic host defense peptides, as an alternative to conventional antibiotics. These peptoids also show efficient and fast (<30min) killing of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) at low micromolar concentrations without having apparent cytotoxic side effects in vivo. Additionally, these novel peptoids show excellent efficacy against biofilm formation and detachment for both MSSA and MRSA. In comparison, conventional antibiotics were unable to detach or prevent formation of biofilms. One cationic 12mer, Peptoid 1, shows great promise, as it could prevent formation of and detach biofilms at concentrations as low as 1.6muM. The use of a bioluminescent S. aureus murine incision wound model demonstrated clearance of infection in peptoid-treated mice within 8days, conveying another advantage these peptoids have over conventional antibiotics. These results provide clear evidence of the potential for antimicrobial peptoids for the treatment of S. aureus wound infections. IMPORTANCE Staphylococcus aureus resistance is a consistent problem with a large impact on the health care system. Infections with resistant S. aureus can cause serious adverse effects and can result in death. These antimicrobial peptoids show efficient killing of bacteria both as a biofilm and as free bacteria, often doing so in less than 30 min. As such, these antimicrobials have the potential to alleviate the burden that Staphylococcus infections have on the health care system and cause better outcomes for infected patients.

  View details for DOI 10.1128/spectrum.00534-22

  View details for PubMedID 35467395

• Self-Assembly of Antimicrobial Peptoids Impacts Their Biological Effects on ESKAPE Bacterial Pathogens. ACS infectious diseases Nielsen, J. E., Alford, M. A., Yung, D. B., Molchanova, N., Fortkort, J. A., Lin, J. S., Diamond, G., Hancock, R. E., Jenssen, H., Pletzer, D., Lund, R., Barron, A. E. 2022

  Abstract

  Antimicrobial peptides (AMPs) are promising pharmaceutical candidates for the prevention and treatment of infections caused by multidrug-resistant ESKAPE pathogens, which are responsible for the majority of hospital-acquired infections. Clinical translation of AMPs has been limited, in part by apparent toxicity on systemic dosing and by instability arising from susceptibility to proteolysis. Peptoids (sequence-specific oligo-N-substituted glycines) resist proteolytic digestion and thus are of value as AMP mimics. Only a few natural AMPs such as LL-37 and polymyxin self-assemble in solution; whether antimicrobial peptoids mimic these properties has been unknown. Here, we examine the antibacterial efficacy and dynamic self-assembly in aqueous media of eight peptoid mimics of cationic AMPs designed to self-assemble and two nonassembling controls. These amphipathic peptoids self-assembled in different ways, as determined by small-angle X-ray scattering; some adopt helical bundles, while others form core-shell ellipsoidal or worm-like micelles. Interestingly, many of these peptoid assemblies show promising antibacterial, antibiofilm activity in vitro in media, under host-mimicking conditions and antiabscess activity in vivo. While self-assembly correlated overall with antibacterial efficacy, this correlation was imperfect. Certain self-assembled morphologies seem better-suited for antibacterial activity. In particular, a peptoid exhibiting a high fraction of long, worm-like micelles showed reduced antibacterial, antibiofilm, and antiabscess activity against ESKAPE pathogens compared with peptoids that form ellipsoidal or bundled assemblies. This is the first report of self-assembling peptoid antibacterials with activity against in vivo biofilm-like infections relevant to clinical medicine.

  View details for DOI 10.1021/acsinfecdis.1c00536

  View details for PubMedID 35175731

• Upregulating Human Cathelicidin Antimicrobial Peptide LL-37 Expression May Prevent Severe COVID-19 Inflammatory Responses and Reduce Microthrombosis Frontiers in Immunology Aloul, K. M., Nielsen, J. E., Defensor, E. B., Lin, J. S., Fortkort, J. A., Shamloo, M., Cirillo, J. D., Gombart, A. F., Barron, A. E. 2022; 13: 1-16

  View details for DOI 10.3389/fimmu.2022.880961

• Potent Antiviral Activity against HSV-1 and SARS-CoV-2 by Antimicrobial Peptoids Pharmaceuticals Diamond, G., Molchanova, N., Herlan, C., Fortkort, J. A., Lin, J. S., Figgins, E., Bopp, N., Ryan, L. K., Chung, D., Adcock, R. S., Sherman, M., Barron, A. E. 2021; 14 (4): 304

  View details for DOI 10.3390/ph14040304

• The human cathelicidin LL-37 is a nanomolar inhibitor of amyloid self-assembly of islet amyloid polypeptide (IAPP). Angewandte Chemie (International ed. in English) Armiento, V., Hille, K., Naltsas, D., Lin, J. S., Barron, A. E., Kapurniotu, A. 2020

  Abstract

  Amyloid self-assembly of islet amyloid polypeptide (IAPP) is linked to pancreatic inflammation, β-cell degeneration, and the pathogenesis of type 2 diabetes (T2D). The multifunctional host defence peptides (HDPs) cathelicidins play crucial roles in inflammation. Here we show that the antimicrobial and immunomodu-latory polypeptide human cathelicidin LL-37 binds IAPP with nano-molar affinity and effectively suppresses its amyloid self-assembly and related pancreatic β-cell damage in vitro. In addition, we identify key LL-37 segments mediating its interaction with IAPP. Our results suggest a possible protective role for LL-37 in T2D pathogenesis and offer a molecular basis for the design of LL-37-derived peptides combining antimicrobial, immunomodulatory, and T2D-related anti-amyloid functions as promising candidates for multifunc-tional drugs.

  View details for DOI 10.1002/anie.202000148

  View details for PubMedID 31999880

• The human cathelicidin LL-37 is a nanomolar inhibitor of amyloid self-assembly of islet amyloid polypeptide (IAPP) Angewandte Chemie International Edition, https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202000148 Armiento, V., Hille, K., Naltsas, D., Lin, J. S., Barron, A. E., Kapurniotu, A. 2020; In Press: 6

  View details for DOI 10.1002/anie.202000148

• Optimizing Exogenous Surfactant as a Pulmonary Delivery Vehicle for Chicken Cathelicidin-2. Scientific reports Baer, B. n., Veldhuizen, E. J., Molchanova, N. n., Jekhmane, S. n., Weingarth, M. n., Jenssen, H. n., Lin, J. S., Barron, A. E., Yamashita, C. n., Veldhuizen, R. n. 2020; 10 (1): 9392

  Abstract

  The rising incidence of antibiotic-resistant lung infections has instigated a much-needed search for new therapeutic strategies. One proposed strategy is the use of exogenous surfactants to deliver antimicrobial peptides (AMPs), like CATH-2, to infected regions of the lung. CATH-2 can kill bacteria through a diverse range of antibacterial pathways and exogenous surfactant can improve pulmonary drug distribution. Unfortunately, mixing AMPs with commercially available exogenous surfactants has been shown to negatively impact their antimicrobial function. It was hypothesized that the phosphatidylglycerol component of surfactant was inhibiting AMP function and that an exogenous surfactant, with a reduced phosphatidylglycerol composition would increase peptide mediated killing at a distal site. To better understand how surfactant lipids interacted with CATH-2 and affected its function, isothermal titration calorimetry and solid-state nuclear magnetic resonance spectroscopy as well as bacterial killing curves against Pseudomonas aeruginosa were utilized. Additionally, the wet bridge transfer system was used to evaluate surfactant spreading and peptide transport. Phosphatidylglycerol was the only surfactant lipid to significantly inhibit CATH-2 function, showing a stronger electrostatic interaction with the peptide than other lipids. Although diluting the phosphatidylglycerol content in an existing surfactant, through the addition of other lipids, significantly improved peptide function and distal killing, it also reduced surfactant spreading. A synthetic phosphatidylglycerol-free surfactant however, was shown to further improve CATH-2 delivery and function at a remote site. Based on these in vitro experiments synthetic phosphatidylglycerol-free surfactants seem optimal for delivering AMPs to the lung.

  View details for DOI 10.1038/s41598-020-66448-1

  View details for PubMedID 32523049

• Helical side chain chemistry of a peptoid-based SP-C analogue: Balancing structural rigidity and biomimicry BIOPOLYMERS Brown, N. J., Lin, J. S., Barron, A. E. 2019; 110 (6)

  View details for DOI 10.1002/bip.23277

  View details for Web of Science ID 000477676800006

• Helical side chain chemistry of a peptoid-based SP-C analogue: Balancing structural rigidity and biomimicry. Biopolymers Brown, N. J., Lin, J. S., Barron, A. E. 2019: e23277

  Abstract

  Surfactant protein C (SP-C) is an important constituent of lung surfactant (LS) and, along with SP-B, is included in exogenous surfactant replacement therapies for treating respiratory distress syndrome (RDS). SP-C's biophysical activity depends upon the presence of a rigid C-terminal helix, of which the secondary structure is more crucial to functionality than precise side-chain chemistry. SP-C is highly sequence-conserved, suggesting that the beta-branched, aliphatic side chains of the helix are also important. Nonnatural mimics of SP-C were created using a poly-N-substituted glycine, or "peptoid," backbone. The mimics included varying amounts of alpha-chiral, aliphatic side chains and alpha-chiral, aromatic side chains in the helical region, imparting either biomimicry or structural rigidity. Biophysical studies confirmed that the peptoids mimicked SP-C's secondary structure and replicated many of its surface-active characteristics. Surface activity was optimized by incorporating both structurally rigid and biomimetic side chain chemistries in the helical region indicating that both characteristics are important for activity. By balancing these features in one mimic, a novel analogue was created that emulates SP-C's in vitro surface activity while overcoming many of the challenges related to natural SP-C. Peptoid-based analogues hold great potential for use in a synthetic, biomimetic LS formulation for treating RDS.

  View details for PubMedID 30972750

• Effective in vivo treatment of acute lung injury with helical, amphipathic peptoid mimics of pulmonary surfactant proteins SCIENTIFIC REPORTS Czyzewski, A. M., McCaig, L. M., Dohm, M. T., Broering, L. A., Yao, L., Brown, N. J., Didwania, M. K., Lin, J. S., Lewis, J. F., Veldhuizen, R., Barron, A. E. 2018; 8: 6795

  Abstract

  Acute lung injury (ALI) leads to progressive loss of breathing capacity and hypoxemia, as well as pulmonary surfactant dysfunction. ALI's pathogenesis and management are complex, and it is a significant cause of morbidity and mortality worldwide. Exogenous surfactant therapy, even for research purposes, is impractical for adults because of the high cost of current surfactant preparations. Prior in vitro work has shown that poly-N-substituted glycines (peptoids), in a biomimetic lipid mixture, emulate key biophysical activities of lung surfactant proteins B and C at the air-water interface. Here we report good in vivo efficacy of a peptoid-based surfactant, compared with extracted animal surfactant and a synthetic lipid formulation, in a rat model of lavage-induced ALI. Adult rats were subjected to whole-lung lavage followed by administration of surfactant formulations and monitoring of outcomes. Treatment with a surfactant protein C mimic formulation improved blood oxygenation, blood pH, shunt fraction, and peak inspiratory pressure to a greater degree than surfactant protein B mimic or combined formulations. All peptoid-enhanced treatment groups showed improved outcomes compared to synthetic lipids alone, and some formulations improved outcomes to a similar extent as animal-derived surfactant. Robust biophysical mimics of natural surfactant proteins may enable new medical research in ALI treatment.

  View details for PubMedID 29717157

• Evidence that the Human Innate Immune Peptide LL-37 May Be a Binding Partner of Abeta and Inhibitor of Fibril Assembly De Lorenzi, E., Chiari, M., Colombo, R., Cretich, M., Sola, L., Vanna, R., Gagni, P., Bisceglia, F., Morasso, C., Lin, J. S., Lee, M., McGeer, P. L., Barron, A. E. CELL PRESS. 2018: 393A

  View details for Web of Science ID 000430450000449

• Evidence that the Human Innate Immune Peptide LL-37 may be a Binding Partner of Amyloid-β and Inhibitor of Fibril Assembly. Journal of Alzheimer's disease : JAD De Lorenzi, E., Chiari, M., Colombo, R., Cretich, M., Sola, L., Vanna, R., Gagni, P., Bisceglia, F., Morasso, C., Lin, J. S., Lee, M., McGeer, P. L., Barron, A. E. 2017; 59 (4): 1213-1226

  Abstract

  Identifying physiologically relevant binding partners of amyloid-β (Aβ) that modulate in vivo fibril formation may yield new insights into Alzheimer's disease (AD) etiology. Human cathelicidin peptide, LL-37, is an innate immune effector and modulator, ubiquitous in human tissues and expressed in myriad cell types.We present in vitro experimental evidence and discuss findings supporting a novel hypothesis that LL-37 binds to Aβ42 and can modulate Aβ fibril formation.Specific interactions between LL-37 and Aβ (with Aβ in different aggregation states, assessed by capillary electrophoresis) were demonstrated by surface plasmon resonance imaging (SPRi). Morphological and structural changes were investigated by transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy. Neuroinflammatory and cytotoxic effects of LL-37 alone, Aβ42 alone, and LL-37/Aβ complexes were evaluated in human microglia and neuroblastoma cell lines (SH-SY5Y).SPRi shows binding specificity between LL-37 and Aβ, while TEM shows that LL-37 inhibits Aβ42 fibril formation, particularly Aβ's ability to form long, straight fibrils characteristic of AD. CD reveals that LL-37 prevents Aβ42 from adopting its typical β-type secondary structure. Microglia-mediated toxicities of LL-37 and Aβ42 to neurons are greatly attenuated when the two peptides are co-incubated prior to addition. We discuss the complementary biophysical characteristics and AD-related biological activities of these two peptides.Based on this body of evidence, we propose that LL-37 and Aβ42 may be natural binding partners, which implies that balanced (or unbalanced) spatiotemporal expression of the two peptides could impact AD initiation and progression.

  View details for DOI 10.3233/JAD-170223

  View details for PubMedID 28731438

  View details for PubMedCentralID PMC5611894

• Intracellular biomass flocculation as a key mechanism of rapid bacterial killing by cationic, amphipathic antimicrobial peptides and peptoids. Scientific reports Chongsiriwatana, N. P., Lin, J. S., Kapoor, R. n., Wetzler, M. n., Rea, J. A., Didwania, M. K., Contag, C. H., Barron, A. E. 2017; 7 (1): 16718

  Abstract

  Many organisms rely on antimicrobial peptides (AMPs) as a first line of defense against pathogens. In general, most AMPs are thought to kill bacteria by binding to and disrupting cell membranes. However, certain AMPs instead appear to inhibit biomacromolecule synthesis, while causing less membrane damage. Despite an unclear understanding of mechanism(s), there is considerable interest in mimicking AMPs with stable, synthetic molecules. Antimicrobial N-substituted glycine (peptoid) oligomers ("ampetoids") are structural, functional and mechanistic analogs of helical, cationic AMPs, which offer broad-spectrum antibacterial activity and better therapeutic potential than peptides. Here, we show through quantitative studies of membrane permeabilization, electron microscopy, and soft X-ray tomography that both AMPs and ampetoids trigger extensive and rapid non-specific aggregation of intracellular biomacromolecules that correlates with microbial death. We present data demonstrating that ampetoids are "fast killers", which rapidly aggregate bacterial ribosomes in vitro and in vivo. We suggest intracellular biomass flocculation is a key mechanism of killing for cationic, amphipathic AMPs, which may explain why most AMPs require micromolar concentrations for activity, show significant selectivity for killing bacteria over mammalian cells, and finally, why development of resistance to AMPs is less prevalent than developed resistance to conventional antibiotics.

  View details for PubMedID 29196622

  View details for PubMedCentralID PMC5711933

• Evidence that the Human Innate Immune Peptide LL-37 may be a Binding Partner of Amyloid-β and Inhibitor of Fibril Assembly Journal of Alzheimer's Disease De Lorenzi, E., Chiari, M., Colombo, R., Cretich, M., Sola, L., Vanna, R., Gagni, P., Bisceglia, F., Morasso, C., Lin, J. S., Lee, M., McGeer, P. L., Barron, A. E. 2017; 59 (4): 1213-1226

  Abstract

  Identifying physiologically relevant binding partners of amyloid-β (Aβ) that modulate in vivo fibril formation may yield new insights into Alzheimer's disease (AD) etiology. Human cathelicidin peptide, LL-37, is an innate immune effector and modulator, ubiquitous in human tissues and expressed in myriad cell types.We present in vitro experimental evidence and discuss findings supporting a novel hypothesis that LL-37 binds to Aβ42 and can modulate Aβ fibril formation.Specific interactions between LL-37 and Aβ (with Aβ in different aggregation states, assessed by capillary electrophoresis) were demonstrated by surface plasmon resonance imaging (SPRi). Morphological and structural changes were investigated by transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy. Neuroinflammatory and cytotoxic effects of LL-37 alone, Aβ42 alone, and LL-37/Aβ complexes were evaluated in human microglia and neuroblastoma cell lines (SH-SY5Y).SPRi shows binding specificity between LL-37 and Aβ, while TEM shows that LL-37 inhibits Aβ42 fibril formation, particularly Aβ's ability to form long, straight fibrils characteristic of AD. CD reveals that LL-37 prevents Aβ42 from adopting its typical β-type secondary structure. Microglia-mediated toxicities of LL-37 and Aβ42 to neurons are greatly attenuated when the two peptides are co-incubated prior to addition. We discuss the complementary biophysical characteristics and AD-related biological activities of these two peptides.Based on this body of evidence, we propose that LL-37 and Aβ42 may be natural binding partners, which implies that balanced (or unbalanced) spatiotemporal expression of the two peptides could impact AD initiation and progression.

  View details for DOI 10.3233/JAD-170223

  View details for PubMedCentralID PMC5611894

• Simultaneous detection of 19 K-ras mutations by free-solution conjugate electrophoresis of ligase detection reaction products on glass microchips ELECTROPHORESIS Albrecht, J. C., Kotani, A., Lin, J. S., Soper, S. A., Barron, A. E. 2013; 34 (4): 590-597

  Abstract

  We demonstrate here the power and flexibility of free-solution conjugate electrophoresis (FSCE) as a method of separating DNA fragments by electrophoresis with no sieving polymer network. Previous work introduced the coupling of FSCE with ligase detection reaction (LDR) to detect point mutations, even at low abundance compared to the wild-type DNA. Here, four large drag-tags are used to achieve free-solution electrophoretic separation of 19 LDR products ranging in size from 42 to 66 nt that correspond to mutations in the K-ras oncogene. LDR-FSCE enabled electrophoretic resolution of these 19 LDR-FSCE products by CE in 13.5 min (E = 310 V/cm) and by microchip electrophoresis in 140 s (E = 350 V/cm). The power of FSCE is demonstrated in the unique characteristic of free-solution separations where the separation resolution is constant no matter the electric field strength. By microchip electrophoresis, the electric field was increased to the maximum of the power supply (E = 700 V/cm), and the 19 LDR-FSCE products were separated in less than 70 s with almost identical resolution to the separation at E = 350 V/cm. These results will aid the goal of screening K-ras mutations on integrated "sample-in/answer-out" devices with amplification, LDR, and detection all on one platform.

  View details for DOI 10.1002/elps.201200462

  View details for Web of Science ID 000315169800016

  View details for PubMedID 23192597

• Divergent dispersion behavior of ssDNA fragments during microchip electrophoresis in pDMA and LPA entangled polymer networks ELECTROPHORESIS Fredlake, C. P., Hert, D. G., Niedringhaus, T. P., Lin, J. S., Barron, A. E. 2012; 33 (9-10): 1411-1420

  Abstract

  Resolution of DNA fragments separated by electrophoresis in polymer solutions ("matrices") is determined by both the spacing between peaks and the width of the peaks. Prior research on the development of high-performance separation matrices has been focused primarily on optimizing DNA mobility and matrix selectivity, and gave less attention to peak broadening. Quantitative data are rare for peak broadening in systems in which high electric field strengths are used (>150 V/cm), which is surprising since capillary and microchip-based systems commonly run at these field strengths. Here, we report results for a study of band broadening behavior for ssDNA fragments on a glass microfluidic chip, for electric field strengths up to 320 V/cm. We compare dispersion coefficients obtained in a poly(N,N-dimethylacrylamide) (pDMA) separation matrix that was developed for chip-based DNA sequencing with a commercially available linear polyacrylamide (LPA) matrix commonly used in capillaries. Much larger DNA dispersion coefficients were measured in the LPA matrix as compared to the pDMA matrix, and the dependence of dispersion coefficient on DNA size and electric field strength were found to differ quite starkly in the two matrices. These observations lead us to propose that DNA migration mechanisms differ substantially in our custom pDMA matrix compared to the commercially available LPA matrix. We discuss the implications of these results in terms of developing optimal matrices for specific separation (microchip or capillary) platforms.

  View details for DOI 10.1002/elps.201100686

  View details for Web of Science ID 000304600500010

  View details for PubMedID 22648809

• Peptoid transporters: effects of cationic, amphipathic structure on their cellular uptake MOLECULAR BIOSYSTEMS Huang, W., Seo, J., Lin, J. S., Barron, A. E. 2012; 8 (10): 2626-2628

  Abstract

  Two cationic, amphipathic peptoids (poly-N-substituted glycines) were developed as new molecular transporters, which have extensive cellullar uptake and utilize different internalization mechanisms from purely cationic polyguanidine comparators.

  View details for DOI 10.1039/c2mb25197c

  View details for Web of Science ID 000308098600019

  View details for PubMedID 22828784

  View details for PubMedCentralID PMC3431920

• Monodisperse, "Highly" Positively Charged Protein Polymer Drag-Tags Generated in an Intein-Mediated Purification System Used in Free-Solution Electrophoretic Separations of DNA BIOMACROMOLECULES Wang, X., Albrecht, J. C., Lin, J. S., Barron, A. E. 2012; 13 (1): 117-123

  Abstract

  Free-solution conjugate electrophoresis (FSCE) is a method of DNA sequencing that eliminates the need for viscous polymer solutions by tethering a carefully designed, mobility modifying "drag-tag" to each DNA molecule to achieve size-based separations of DNA. The most successful drag-tags to date are genetically engineered, highly repetitive polypeptides ("protein polymers") that are designed to be large, water-soluble, and completely monodisperse. Positively charged arginines were deliberately introduced at regular intervals into the amino acid sequence to increase the hydrodynamic drag without increasing drag-tag length. Additionally, a one-step purification method that combines affinity chromatography and on-column tag cleavage was devised to achieve the required drag-tag monodispersity. Sequencing with a read length of approximately 180 bases was successfully achieved with a known sequence in free-solution electrophoresis using one of these positively charged drag-tags. This preliminary result is expected to lead to further progress in FSCE sequencing with ~400 bases read length possible when more "highly" positively charged protein polymers of larger size are generated with the intein system.

  View details for DOI 10.1021/bm2013313

  View details for Web of Science ID 000298897300013

  View details for PubMedID 22168388

  View details for PubMedCentralID PMC3270947

• Ultrafast, efficient separations of large-sized dsDNA in a blended polymer matrix by microfluidic chip electrophoresis: A design of experiments approach ELECTROPHORESIS Sun, M., Lin, J. S., Barron, A. E. 2011; 32 (22): 3233-3240

  Abstract

  Double-stranded (ds) DNA fragments over a wide size range were successfully separated in blended polymer matrices by microfluidic chip electrophoresis. Novel blended polymer matrices composed of two types of polymers with three different molar masses were developed to provide improved separations of large dsDNA without negatively impacting the separation of small dsDNA. Hydroxyethyl celluloses with average molar masses of ∼27  kDa and ∼1  MDa were blended with a second class of polymer, high-molar mass (∼7  MDa) linear polyacrylamide. Fast and highly efficient separations of commercially available DNA ladders were achieved on a borosilicate glass microchip. A distinct separation of a 1-kb DNA extension ladder (200-40,000  bp) was completed in 2  min. An orthogonal design of experiments was used to optimize experimental parameters for DNA separations over a wide size range. We find that the two dominant factors are the applied electric field strength and the inclusion of a high concentration of low-molar mass polymer in the matrix solution. These two factors exerted different effects on the separations of small dsDNA fragments below 1  kbp, medium dsDNA fragments between 1 and 10  kbp, and large dsDNA fragments above 10  kbp.

  View details for DOI 10.1002/elps.201100260

  View details for Web of Science ID 000298098700020

  View details for PubMedID 22009451

• Blinded study determination of high sensitivity and specificity microchip electrophoresis-SSCP/HA to detect mutations in the p53 gene ELECTROPHORESIS Hestekin, C. N., Lin, J. S., Senderowicz, L., Jakupciak, J. P., O'Connell, C., Rademaker, A., Barron, A. E. 2011; 32 (21): 2921-2929

  Abstract

  Knowledge of the genetic changes that lead to disease has grown and continues to grow at a rapid pace. However, there is a need for clinical devices that can be used routinely to translate this knowledge into the treatment of patients. Use in a clinical setting requires high sensitivity and specificity (>97%) in order to prevent misdiagnoses. Single-strand conformational polymorphism (SSCP) and heteroduplex analysis (HA) are two DNA-based, complementary methods for mutation detection that are inexpensive and relatively easy to implement. However, both methods are most commonly detected by slab gel electrophoresis, which can be labor-intensive, time-consuming, and often the methods are unable to produce high sensitivity and specificity without the use of multiple analysis conditions. Here, we demonstrate the first blinded study using microchip electrophoresis (ME)-SSCP/HA. We demonstrate the ability of ME-SSCP/HA to detect with 98% sensitivity and specificity >100 samples from the p53 gene exons 5-9 in a blinded study in an analysis time of <10 min.

  View details for DOI 10.1002/elps.201100396

  View details for Web of Science ID 000298101000001

  View details for PubMedID 22002021

  View details for PubMedCentralID PMC3416029

• Completely Monodisperse, Highly Repetitive Proteins for Bioconjugate Capillary Electrophoresis: Development and Characterization BIOMACROMOLECULES Lin, J. S., Albrecht, J. C., Meagher, R. J., Wang, X., Barron, A. E. 2011; 12 (6): 2275-2284

  Abstract

  Protein-based polymers are increasingly being used in biomaterial applications because of their ease of customization and potential monodispersity. These advantages make protein polymers excellent candidates for bioanalytical applications. Here we describe improved methods for producing drag-tags for free-solution conjugate electrophoresis (FSCE). FSCE utilizes a pure, monodisperse recombinant protein, tethered end-on to a ssDNA molecule, to enable DNA size separation in aqueous buffer. FSCE also provides a highly sensitive method to evaluate the polydispersity of a protein drag-tag and thus its suitability for bioanalytical uses. This method is able to detect slight differences in drag-tag charge or mass. We have devised an improved cloning, expression, and purification strategy that enables us to generate, for the first time, a truly monodisperse 20 kDa protein polymer and a nearly monodisperse 38 kDa protein. These newly produced proteins can be used as drag-tags to enable longer read DNA sequencing by free-solution microchannel electrophoresis.

  View details for DOI 10.1021/bm200358r

  View details for Web of Science ID 000291499900038

  View details for PubMedID 21553840

  View details for PubMedCentralID PMC3129339

• Free-solution electrophoretic separations of DNA-drag-tag conjugates on glass microchips with no polymer network and no loss of resolution at increased electric field strength ELECTROPHORESIS Albrecht, J. C., Kerby, M. B., Niedringhaus, T. P., Lin, J. S., Wang, X., Barron, A. E. 2011; 32 (10): 1201-1208

  Abstract

  Here, we demonstrate the potential for high-resolution electrophoretic separations of ssDNA-protein conjugates in borosilicate glass microfluidic chips, with no sieving media and excellent repeatability. Using polynucleotides of two different lengths conjugated to moderately cationic protein polymer drag-tags, we measured separation efficiency as a function of applied electric field. In excellent agreement with prior theoretical predictions of Slater et al., resolution is found to remain constant as applied field is increased up to 700 V/cm, the highest field we were able to apply. This remarkable result illustrates the fundamentally different physical limitations of free-solution conjugate electrophoresis (FSCE)-based DNA separations relative to matrix-based DNA electrophoresis. ssDNA separations in "gels" have always shown rapidly declining resolution as the field strength is increased; this is especially true for ssDNA > 400 bases in length. FSCE's ability to decouple DNA peak resolution from applied electric field suggests the future possibility of ultra-rapid FSCE sequencing on chips. We investigated sources of peak broadening for FSCE separations on borosilicate glass microchips, using six different protein polymer drag-tags. For drag-tags with four or more positive charges, electrostatic and adsorptive interactions with poly(N-hydroxyethylacrylamide)-coated microchannel walls led to appreciable band-broadening, while much sharper peaks were seen for bioconjugates with nearly charge-neutral protein drag-tags.

  View details for DOI 10.1002/elps.201000574

  View details for Web of Science ID 000290586200014

  View details for PubMedID 21500207

  View details for PubMedCentralID PMC3416026

• A 265-Base DNA Sequencing Read by Capillary Electrophoresis with No Separation Matrix ANALYTICAL CHEMISTRY Albrecht, J. C., Lin, J. S., Barron, A. E. 2011; 83 (2): 509-515

  Abstract

  Electrophoretic DNA sequencing without a polymer matrix is currently possible only with the use of some kind of "drag-tag" as a mobility modifier. In free-solution conjugate electrophoresis (FSCE), a drag-tag attached to each DNA fragment breaks linear charge-to-friction scaling, enabling size-based separation in aqueous buffer alone. Here we report a 265-base read for free-solution DNA sequencing by capillary electrophoresis using a random-coil protein drag-tag of unprecedented length and purity. We identified certain methods of protein expression and purification that allow the production of highly monodisperse drag-tags as long as 516 amino acids, which are almost charge neutral (+1 to +6) and yet highly water-soluble. Using a four-color LIF detector, 265 bases could be read in 30 min with a 267-amino acid drag-tag, on par with the average read of current next-gen sequencing systems. New types of multichannel systems that allow much higher throughput electrophoretic sequencing should be much more accessible in the absence of a requirement for viscous separation matrix.

  View details for DOI 10.1021/ac102188p

  View details for Web of Science ID 000286129800007

  View details for PubMedID 21182303

  View details for PubMedCentralID PMC3271724

• Sequencing of DNA by free-solution capillary electrophoresis using a genetically engineered protein polymer drag-tag ANALYTICAL CHEMISTRY Meagher, R. J., Won, J., Coyne, J. A., Lin, J., Barron, A. E. 2008; 80 (8): 2842-2848

  Abstract

  We demonstrate the first use of a non-natural, genetically engineered protein polymer drag-tag to sequence DNA fragments by end-labeled free-solution electrophoresis (ELFSE). Fluorescently labeled DNA fragments resulting from the Sanger cycle sequencing reaction were separated by free-solution capillary electrophoresis, with much higher resolution and cleaner results than previously reported for this technique. With ELFSE, size-based separation of DNA in the absence of a sieving matrix is enabled by the end-on attachment of a polymeric "drag-tag" that modifies the charge-to-friction ratio of DNA in a size-dependent fashion. Progress in ELFSE separations has previously been limited by the lack of suitable large, monodisperse drag-tags. To address this problem, we designed, constructed, cloned, expressed, and purified a non-natural, genetically engineered 127mer protein polymer for use as an ELFSE drag-tag. The Sanger cycle sequencing reaction is performed with the drag-tag covalently attached to the sequencing primer, a major advance over previous strategies for ELFSE sequencing. The electrophoretic separation is diffusion-limited, without significant adsorption of the drag-tag to capillary walls. Although the read length (at about 180 bases) is still short, our results provide evidence that larger protein polymer drag-tags, currently under development, could extend the read length of ELFSE to more competitive levels. ELFSE offers the possibility of very rapid DNA sequencing separations without any of the difficulties associated with viscous polymeric sieving networks and hence will be amenable to implementation in microchannel and chip-based electrophoresis systems.

  View details for DOI 10.1021/ac702591t

  View details for Web of Science ID 000254969100026

  View details for PubMedID 18318549