36 research outputs found
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 Mg<sup>2+</sup> ions binding to surface-immobilized
T<sub>40</sub> sequences, the subsequent reordering of DNA on the
surface, and the consequences of Mg<sup>2+</sup> binding for DNAâDNA
interactions. Second harmonic generation measurements indicate that,
within error, 18â20 Mg<sup>2+</sup> ions are bound to the T<sub>40</sub> strand at saturation and that the metalâDNA 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 Mg<sup>2+</sup> 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 Mg<sup>2+</sup> 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 Mg<sup>2+</sup> concentrations for DNAâDNA 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 Mg<sup>2+</sup> ions are bound per T<sub>40</sub> strand, which is not reached
until the bulk Mg<sup>2+</sup> concentration approaches 0.5 mM; (2)
hybridization proceeds, albeit with low duplex stability having an
average <i>T</i><sub>m</sub> of 31(3)°C, if an average
of 17.5â18.0 Mg<sup>2+</sup> ions are bound; and (3) highly
stable duplexes having a <i>T</i><sub>m</sub> of 64(2)°C
form if 18.5â19.0 Mg<sup>2+</sup> ions are bound, corresponding
to saturation of the T<sub>40</sub> 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.; nâ=â3 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>â<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 (scalebarâ=â100 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.; nâ=â3 biological replicates). (<b>C</b>) Confocal micrographs comparing the presence and localization of hepatic markers within the two culture systems (scale barâ=â100 microns). (<b>D</b>) CYP3A4 activity of the two culture conditions measured over a period of 75 days (mean ± s.d.; nâ=â3 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