Lab Affiliations

All Publications

  • Bacterial outer membrane vesicles bound to bacteriophages modulate neutrophil responses to bacterial infection. Frontiers in cellular and infection microbiology Pennetzdorfer, N., Popescu, M. C., Haddock, N. L., Dupuy, F., Kaber, G., Hargil, A., Johansson, P. K., Enejder, A., Bollyky, P. L. 2023; 13: 1250339


    Pseudomonas aeruginosa is a major human pathogen, particularly effective at colonizing the airways of patients with cystic fibrosis. Bacteriophages are highly abundant at infection sites, but their impact on mammalian immunity remains unclear. We previously showed that Pf4, a temperate filamentous bacteriophage produced by P. aeruginosa, modifies the innate immune response to P. aeruginosa infections via TLR3 signaling, but the underlying mechanisms remained unclear. Notably, Pf4 is a single-stranded DNA and lysogenic phage, and its production does not typically result in lysis of its bacterial host. We identified previously that internalization of Pf4 by human or murine immune cells triggers maladaptive viral pattern recognition receptors and resulted in bacterial persistence based on the presence of phage RNA. We report now that Pf4 phage dampens inflammatory responses to bacterial endotoxin and that this is mediated in part via bacterial vesicles attached to phage particles. Outer membrane vesicles (OMVs) are produced by Gram-negative bacteria and play a key role in host pathogen interaction. Recently, evidence has emerged that OMVs differentially package small RNAs. In this study, we show that Pf4 are decorated with OMVs that remain affixed to Pf4 despite of purification steps. These phages are endocytosed by human cells and delivered to endosomal vesicles. We demonstrate that short RNAs within the OMVs form hairpin structures that trigger TLR3-dependent type I interferon production and antagonize production of antibacterial cytokines and chemokines. In particular, Pf4 phages inhibit CXCL5, preventing efficient neutrophil chemotaxis in response to endotoxin. Moreover, blocking IFNAR or TLR3 signaling abrogates the effect of Pf4 bound to OMVs on macrophage activation. In a murine acute pneumonia model, mice treated with Pf4 associated with OMVs show significantly less neutrophil infiltration in BAL fluid than mice treated with purified Pf4. These changes in macrophage phenotype are functionally relevant: conditioned media from cells exposed to Pf4 decorated with OMVs are significantly less effective at inducing neutrophil migration in vitro and in vivo. These results suggest that Pf4 phages alter innate immunity to bacterial endotoxin and OMVs, potentially dampening inflammation at sites of bacterial colonization or infection.

    View details for DOI 10.3389/fcimb.2023.1250339

    View details for PubMedID 37965262

    View details for PubMedCentralID PMC10641230

  • APOE4/4 is linked to damaging lipid droplets in Alzheimer's microglia. bioRxiv : the preprint server for biology Haney, M. S., Pálovics, R., Munson, C. N., Long, C., Johansson, P., Yip, O., Dong, W., Rawat, E., West, E., Schlachetzki, J. C., Tsai, A., Guldner, I. H., Lamichhane, B. S., Smith, A., Schaum, N., Calcuttawala, K., Shin, A., Wang, Y. H., Wang, C., Koutsodendris, N., Serrano, G. E., Beach, T. G., Reiman, E. M., Glass, C. K., Abu-Remaileh, M., Enejder, A., Huang, Y., Wyss-Coray, T. 2023


    Several genetic risk factors for Alzheimer's Disease (AD) implicate genes involved in lipid metabolism and many of these lipid genes are highly expressed in glial cells. However, the relationship between lipid metabolism in glia and AD pathology remains poorly understood. Through single-nucleus RNA-sequencing of AD brain tissue, we have identified a microglial state defined by the expression of the lipid droplet (LD) associated enzyme ACSL1 with ACSL1-positive microglia most abundant in AD patients with the APOE4/4 genotype. In human iPSC-derived microglia (iMG) fibrillar Aβ (fAβ) induces ACSL1 expression, triglyceride synthesis, and LD accumulation in an APOE-dependent manner. Additionally, conditioned media from LD-containing microglia leads to Tau phosphorylation and neurotoxicity in an APOE-dependent manner. Our findings suggest a link between genetic risk factors for AD with microglial LD accumulation and neurotoxic microglial-derived factors, potentially providing novel therapeutic strategies for AD.

    View details for DOI 10.1101/2023.07.21.549930

    View details for PubMedID 37546938

    View details for PubMedCentralID PMC10401952

  • Elastin-like protein hydrogels with controllable stress relaxation rate and stiffness modulate endothelial cell function. Journal of biomedical materials research. Part A Shayan, M., Huang, M. S., Navarro, R., Chiang, G., Hu, C., Oropeza, B. P., Johansson, P. K., Suhar, R. A., Foster, A. A., LeSavage, B. L., Zamani, M., Enejder, A., Roth, J. G., Heilshorn, S. C., Huang, N. F. 2023


    Mechanical cues from the extracellular matrix (ECM) regulate vascular endothelial cell (EC) morphology and function. Since naturally derived ECMs are viscoelastic, cells respond to viscoelastic matrices that exhibit stress relaxation, in which a cell-applied force results in matrix remodeling. To decouple the effects of stress relaxation rate from substrate stiffness on EC behavior, we engineered elastin-like protein (ELP) hydrogels in which dynamic covalent chemistry (DCC) was used to crosslink hydrazine-modified ELP (ELP-HYD) and aldehyde/benzaldehyde-modified polyethylene glycol (PEG-ALD/PEG-BZA). The reversible DCC crosslinks in ELP-PEG hydrogels create a matrix with independently tunable stiffness and stress relaxation rate. By formulating fast-relaxing or slow-relaxing hydrogels with a range of stiffness (500-3300Pa), we examined the effect of these mechanical properties on EC spreading, proliferation, vascular sprouting, and vascularization. The results show that both stress relaxation rate and stiffness modulate endothelial spreading on two-dimensional substrates, on which ECs exhibited greater cell spreading on fast-relaxing hydrogels up through 3days, compared with slow-relaxing hydrogels at the same stiffness. In three-dimensional hydrogels encapsulating ECs and fibroblasts in coculture, the fast-relaxing, low-stiffness hydrogels produced the widest vascular sprouts, a measure of vessel maturity. This finding was validated in a murine subcutaneous implantation model, in which the fast-relaxing, low-stiffness hydrogel produced significantly more vascularization compared with the slow-relaxing, low-stiffness hydrogel. Together, these results suggest that both stress relaxation rate and stiffness modulate endothelial behavior, and that the fast-relaxing, low-stiffness hydrogels supported the highest capillary density in vivo.

    View details for DOI 10.1002/jbm.a.37520

    View details for PubMedID 36861665

  • Collagen hydrogels covalently crosslinked by bioorthogonal click chemistry resist cell-induced contraction while preserving encapsulated corneal stromal cell phenotype Brunel, L. G., Hull, S. M., Johansson, P. K., Myung, D., Heilshorn, S. C. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • A human multi-lineage hepatic organoid model for liver fibrosis. Nature communications Guan, Y., Enejder, A., Wang, M., Fang, Z., Cui, L., Chen, S., Wang, J., Tan, Y., Wu, M., Chen, X., Johansson, P. K., Osman, I., Kunimoto, K., Russo, P., Heilshorn, S. C., Peltz, G. 2021; 12 (1): 6138


    To investigate the pathogenesis of a congenital form of hepatic fibrosis, human hepatic organoids were engineered to express the most common causative mutation for Autosomal Recessive Polycystic Kidney Disease (ARPKD). Here we show that these hepatic organoids develop the key features of ARPKD liver pathology (abnormal bile ducts and fibrosis) in only 21 days. The ARPKD mutation increases collagen abundance and thick collagen fiber production in hepatic organoids, which mirrors ARPKD liver tissue pathology. Transcriptomic and other analyses indicate that the ARPKD mutation generates cholangiocytes with increased TGFbeta pathway activation, which are actively involved stimulating myofibroblasts to form collagen fibers. There is also an expansion of collagen-producing myofibroblasts with markedly increased PDGFRB protein expression and an activated STAT3 signaling pathway. Moreover, the transcriptome of ARPKD organoid myofibroblasts resemble those present in commonly occurring forms of liver fibrosis. PDGFRB pathway involvement was confirmed by the anti-fibrotic effect observed when ARPKD organoids were treated with PDGFRB inhibitors. Besides providing insight into the pathogenesis of congenital (and possibly acquired) forms of liver fibrosis, ARPKD organoids could also be used to test the anti-fibrotic efficacy of potential anti-fibrotic therapies.

    View details for DOI 10.1038/s41467-021-26410-9

    View details for PubMedID 34686668

  • Elastin-like Proteins to Support Peripheral Nerve Regeneration in Guidance Conduits. ACS biomaterials science & engineering Suhar, R. A., Marquardt, L. M., Song, S., Buabbas, H., Doulames, V. M., Johansson, P. K., Klett, K. C., Dewi, R. E., Enejder, A. M., Plant, G. W., George, P. M., Heilshorn, S. C. 2021; 7 (9): 4209-4220


    Synthetic nerve guidance conduits (NGCs) offer an alternative to harvested nerve grafts for treating peripheral nerve injury (PNI). NGCs have been made from both naturally derived and synthesized materials. While naturally derived materials typically have an increased capacity for bioactivity, synthesized materials have better material control, including tunability and reproducibility. Protein engineering is an alternative strategy that can bridge the benefits of these two classes of materials by designing cell-responsive materials that are also systematically tunable and consistent. Here, we tested a recombinantly derived elastin-like protein (ELP) hydrogel as an intraluminal filler in a rat sciatic nerve injury model. We demonstrated that ELPs enhance the probability of forming a tissue bridge between the proximal and distal nerve stumps compared to an empty silicone conduit across the length of a 10 mm nerve gap. These tissue bridges have evidence of myelinated axons, and electrophysiology demonstrated that regenerated axons innervated distal muscle groups. Animals implanted with an ELP-filled conduit had statistically higher functional control at 6 weeks than those that had received an empty silicone conduit, as evaluated by the sciatic functional index. Taken together, our data support the conclusion that ELPs support peripheral nerve regeneration in acute complete transection injuries when used as an intraluminal filler. These results support the further study of protein engineered recombinant ELP hydrogels as a reproducible, off-the-shelf alternative for regeneration of peripheral nerves.

    View details for DOI 10.1021/acsbiomaterials.0c01053

    View details for PubMedID 34510904

  • Vibrational Sum-Frequency Scattering as a Sensitive Approach to Detect Structural Changes in Collagen Fibers Treated with Surfactants LANGMUIR Johansson, P. K., Castner, D. G. 2019; 35 (24): 7848-7857


    Optimizing protocols so that the structure of the collagen fibers in the extracellular matrix remains intact during the decellularization process requires techniques with high structural sensitivity, especially for the surface region of the collagen fibers. Here, we demonstrate that vibrational sum-frequency scattering (SFS) spectroscopy in the protein-specific amide I region provides vibrational spectra and scattering patterns characteristic of protein fiber networks self-assembled in vitro from collagen type I, which are kept in aqueous environments during the analysis. At scattering angles away from the phase-matched direction, the relative strengths of various polarization combinations are highly reproducible, and changes in their ratios can be followed in real time during exposure to sodium dodecyl sulfate surfactant solutions. For the fibers in this work, a scattering angle of about 22° provided specificity for the surface region of the fibers, as it allowed monitoring of immediate structural changes during the surfactant exposure. With further development, we hypothesize that the information from the SFS characterization of collagen fibers may complement information from other techniques with sensitivity to the overall structure, such as second-harmonic generation imaging and infrared spectroscopy, and provide a more complete understanding of fiber molecular structures and interactions during exposure to various environments and conditions.

    View details for DOI 10.1021/acs.langmuir.9b00412

    View details for Web of Science ID 000472682600028

    View details for PubMedID 31117724

    View details for PubMedCentralID PMC6648693

  • Stark Tuning Rates of Organic Carbonates Used in Electrochemical Energy Storage Devices JOURNAL OF PHYSICAL CHEMISTRY C Olson, J. Z., Schneider, S. H., Johansson, P. K., Luk, T. S., Schlenker, C. W. 2019; 123 (18): 11484–92
  • Operando Sum-Frequency Generation Detection of Electrolyte Redox Products at Active Si Nanoparticle Li-Ion Battery Interfaces CHEMISTRY OF MATERIALS Olson, J. Z., Johansson, P. K., Castner, D. G., Schlenker, C. W. 2018; 30 (4): 1239-1248
  • Nonlinear Optical Methods for Characterization of Molecular Structure and Surface Chemistry Topics in Catalysis Johansson, P. K., Schmüser, L., Castner, D. G. 2018; 61 (9-11): 1101-1124
  • Label-free imaging of amyloids using their intrinsic linear and nonlinear optical properties BIOMEDICAL OPTICS EXPRESS Johansson, P. K., Koelsch, P. 2017; 8 (2): 743-756


    The optical properties of amyloid fibers are often distinct from those of the source protein in its non-fibrillar form. These differences can be utilized for label-free imaging or characterization of such structures, which is particularly important for understanding amyloid fiber related diseases such as Alzheimer's and Parkinson's disease. We demonstrate that two amyloid forming proteins, insulin and β-lactoglobulin (β-LG), show intrinsic fluorescence with emission spectra that are dependent on the excitation wavelength. Additionally, a new fluorescence peak at about 430 nm emerges for β-LG in its amyloid state. The shift in emission wavelength is related to the red edge excitation shift (REES), whereas the additional fluorescence peak is likely associated with charge delocalization along the fiber backbone. Furthermore, the spherulitic amyloid plaque-like superstructures formed from the respective proteins were imaged label-free with confocal fluorescence, multiphoton excitation fluorescence (MPEF), and second-harmonic generation (SHG) microscopy. The latter two techniques in particular yield images with a high contrast between the amyloid fiber regions and the core of amorphously structured protein. Strong multiphoton absorption (MPA) for the amyloid fibers is a likely contributor to the observed contrast in the MPEF images. The crystalline fibrillar region provides even higher contrast in the SHG images, due to the inherently ordered non-centrosymmetric structure of the fibers together with their non-isotropic arrangement. Finally, we show that MPEF from the insulin spherulites exhibits a spectral dependence on the excitation wavelength. This behavior is consistent with the REES phenomenon, which we hypothesize is the origin of this observation. The presented results suggest that amyloid deposits can be identified and structurally characterized based on their intrinsic optical properties, which is important for probe-less and label-free identification and characterization of amyloid fibers in vitro and in complex biological samples.

    View details for DOI 10.1364/BOE.8.000743

    View details for Web of Science ID 000394182100021

    View details for PubMedID 28270981

    View details for PubMedCentralID PMC5330564

  • Experimental design and analysis of activators regenerated by electron transfer-atom transfer radical polymerization experimental conditions for grafting sodium styrene sulfonate from titanium substrates JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A Foster, R. N., Johansson, P. K., Tom, N. R., Koelsch, P., Castner, D. G. 2015; 33 (5): 05E131


    A 24 factorial design was used to optimize the activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) grafting of sodium styrene sulfonate (NaSS) films from trichlorosilane/10-undecen-1-yl 2-bromo-2-methylpropionate (ester ClSi) functionalized titanium substrates. The process variables explored were: (1) ATRP initiator surface functionalization reaction time; (2) grafting reaction time; (3) CuBr2 concentration; and (4) reducing agent (vitamin C) concentration. All samples were characterized using x-ray photoelectron spectroscopy (XPS). Two statistical methods were used to analyze the results: (1) analysis of variance with [Formula: see text], using average [Formula: see text] XPS atomic percent as the response; and (2) principal component analysis using a peak list compiled from all the XPS composition results. Through this analysis combined with follow-up studies, the following conclusions are reached: (1) ATRP-initiator surface functionalization reaction times have no discernable effect on NaSS film quality; (2) minimum (≤24 h for this system) grafting reaction times should be used on titanium substrates since NaSS film quality decreased and variability increased with increasing reaction times; (3) minimum (≤0.5 mg cm-2 for this system) CuBr2 concentrations should be used to graft thicker NaSS films; and (4) no deleterious effects were detected with increasing vitamin C concentration.

    View details for DOI 10.1116/1.4929506

    View details for Web of Science ID 000361229000031

    View details for PubMedID 26396463

    View details for PubMedCentralID PMC4570287

  • Electronic polymers in lipid membranes SCIENTIFIC REPORTS Johansson, P. K., Jullesson, D., Elfwing, A., Liin, S. I., Musumeci, C., Zeglio, E., Elinder, F., Solin, N., Inganas, O. 2015; 5: 11242


    Electrical interfaces between biological cells and man-made electrical devices exist in many forms, but it remains a challenge to bridge the different mechanical and chemical environments of electronic conductors (metals, semiconductors) and biosystems. Here we demonstrate soft electrical interfaces, by integrating the metallic polymer PEDOT-S into lipid membranes. By preparing complexes between alkyl-ammonium salts and PEDOT-S we were able to integrate PEDOT-S into both liposomes and in lipid bilayers on solid surfaces. This is a step towards efficient electronic conduction within lipid membranes. We also demonstrate that the PEDOT-S@alkyl-ammonium:lipid hybrid structures created in this work affect ion channels in the membrane of Xenopus oocytes, which shows the possibility to access and control cell membrane structures with conductive polyelectrolytes.

    View details for DOI 10.1038/srep11242

    View details for Web of Science ID 000356090400002

    View details for PubMedID 26059023

    View details for PubMedCentralID PMC4462020

  • Vibrational Sum-Frequency Scattering for Detailed Studies of Collagen Fibers in Aqueous Environments JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Johansson, P. K., Koelsch, P. 2014; 136 (39): 13598-13601


    Protein fibers play a crucial role in many disease related phenomena and biological systems. A structural analysis of fibrous proteins often requires labeling approaches or disruptive sample preparation while it lacks chemical specificity. Here we demonstrate that the technique of vibrational sum-frequency scattering (SFS) provides a label-free pathway for the chemical and structural analysis of protein fibers in solution. By examining collagen, the most abundant protein in mammals, we demonstrate that the SFS signal of fibers can be detected in the NH, CH stretching and bending, and amide I regions. SFS spectra were found to depend on the scattering angle, which implies the possibility to selectively probe various features of the fibers. The fitting of the data and maximum entropy method analysis revealed a different phase for side-chains and carbonyl contributions, which helps to identify these otherwise overlapping spectral peaks and provides the possibility to perform orientational analysis. Our findings suggest that SFS allows for the greater understanding of protein fibers in solution, which is important when, for example, designing scaffolds in tissue engineering or developing cures for diseases associated with protein fibers.

    View details for DOI 10.1021/ja508190d

    View details for Web of Science ID 000342608800033

    View details for PubMedID 25225785

    View details for PubMedCentralID PMC4183644