Interleukin-13 Activates Distinct Cellular Pathways Leading to Ductular Reaction, Steatosis, and Fibrosis

Fibroproliferative diseases are driven by dysregulated tissue repair responses and are major cause of morbidity and mortality as they affect nearly every organ system. Type-2 cytokine responses are critically involved in tissue repair; however, the mechanisms that regulate beneficial regeneration versus pathological fibrosis are not well understood. Here, we have shown that the type-2 effector cytokine interleukin-13 simultaneously, yet independently, directed hepatic fibrosis and the compensatory proliferation of hepatocytes and biliary cells in progressive models of liver disease induced by interleukin-13 over-expression or following infection with Schistosoma mansoni. Using transgenic mice with interleukin-13 signaling genetically disrupted in hepatocytes, cholangiocytes, or resident tissue fibroblasts, we have revealed direct and distinct roles for interleukin-13 in fibrosis, steatosis, cholestasis, and ductular reaction. Together, these studies show that these mechanisms are simultaneously controlled but distinctly regulated by interleukin-13 signaling. Thus, it may be possible to promote interleukin-13-dependent hepatobiliary expansion without generating pathological fibrosis

Counting the Number of Magnesium Ions Bound to the Surface-Immobilized Thymine Oligonucleotides That Comprise Spherical Nucleic Acids

Label-free studies carried out under aqueous phase conditions quantify the number of Mg²⁺ ions binding to surface-immobilized T₄₀ sequences, the subsequent reordering of DNA on the surface, and the consequences of Mg²⁺ binding for DNA–DNA interactions. Second harmonic generation measurements indicate that, within error, 18–20 Mg²⁺ ions are bound to the T₄₀ strand at saturation and that the metal–DNA interaction is associated with a near 30% length contraction of the strand. Structural reordering, evaluated using vibrational sum frequency generation, atomic force microscopy, and dynamic light scattering, is attributed to increased charge screening as the Mg²⁺ ions bind to the negatively charged DNA, reducing repulsive Coulomb forces between nucleotides and allowing the DNA single strands to collapse or coil upon themselves. The impact of Mg²⁺ binding on DNA hybridization and duplex stability is assessed with spherical nucleic acid (SNA) gold nanoparticle conjugates in order to determine an optimal working range of Mg²⁺ concentrations for DNA–DNA interactions in the absence of NaCl. The findings are consistent with a charge titration effect in which, in the absence of NaCl, (1) hybridization does not occur at room temperature if an average of 17.5 or less Mg²⁺ ions are bound per T₄₀ strand, which is not reached until the bulk Mg²⁺ concentration approaches 0.5 mM; (2) hybridization proceeds, albeit with low duplex stability having an average <i>T</i>_m of 31(3)°C, if an average of 17.5–18.0 Mg²⁺ ions are bound; and (3) highly stable duplexes having a <i>T</i>_m of 64(2)°C form if 18.5–19.0 Mg²⁺ ions are bound, corresponding to saturation of the T₄₀ strand

Functional and transcriptional comparison of IPSC-Hep 3D cultures plated as single cells or clumps.

<p>(<b>A</b>) Secreted albumin, alpha-fetoprotein, and alpha-1-antitrypsin levels as evaluated by immunoassays (mean ± s.d.; n = 3 biological replicates). (<b>B</b>) qPCR heatmap of 39 hepatic genes comparing the two 3D culture conditions to adult and fetal hepatocytes (range of expression shown as sample extrema for each gene; quantitative values shown in <b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086372#pone.0086372.s002" target="_blank">Figures S2</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086372#pone.0086372.s004" target="_blank">S4</a></b>). (<b>C</b>) Confocal micrograph highlighting the loss of detectable albumin in 3D single cell cultures and the spontaneous polarization of IPSC-Heps within 3D clump cultures (scalebar = 100 microns).</p

Functional comparison of IPSC-Hep 3D clump culture versus traditional 2D culture.

<p>(<b>A</b>) Oil red O and periodic acid staining demonstrating lipid storage and glycogen synthesis in both 2D and 3D clump cultures. (<b>B</b>) qPCR analysis of select phase I and phase II enzymes, hepatic transporters, and other hepatic markers demonstrating a shift towards a more mature phenotype in the 3D clump cultures (fold expression to undifferentiated IPSCs; mean ± s.d.; n = 3 biological replicates). (<b>C</b>) Confocal micrographs comparing the presence and localization of hepatic markers within the two culture systems (scale bar = 100 microns). (<b>D</b>) CYP3A4 activity of the two culture conditions measured over a period of 75 days (mean ± s.d.; n = 3 biological replicates).</p

Th2 and Th17 inflammatory pathways are reciprocally regulated in asthma

Increasing evidence suggests that asthma is a heterogeneous disorder regulated by distinct molecular mechanisms. Here, in a cross-sectional study of asthmatics of varying severity (n=51), endobronchial tissue gene expression analysis revealed three major patient clusters: Th2-high, Th17-high, and Th2/Th17-low. Th2-high and Th17-high patterns were mutually exclusive in individual patient samples, and their gene signatures were inversely correlated and differentially regulated by IL-13 and IL-17A. To understand this dichotomous pattern of Th2 and Th17 signatures, we investigated the potential of type 2 cytokine suppression in promoting Th17 responses in a preclinical model of allergen induced asthma. Neutralization of IL-4 and/or IL-13 resulted in increased Th17 cells and neutrophilic inflammation in the lung. However, neutralization of IL-1 and IL-17 protected subjects from eosinophilia, mucus hyperplasia, airway hyperreactivity and abolished the neutrophilic inflammation, suggesting that combination therapies targeting both pathways may maximize therapeutic efficacy across a patient population comprising both Th2 and Th17 endotypes

TH2 and TH17 inflammatory pathways are reciprocally regulated in asthma

Concurrent blockade of IL-13 and IL-17A may improve control of asthma.</jats:p