Abstract
Thymic stromal lymphopoietin (TSLP) is a cytokine mainly released by epithelial cells that plays important roles in inflammation, autoimmune disease, and cancer. While TSLP is expressed in the liver at high levels, the role of TSLP in liver ischemia/reperfusion (I/R) injury remains unknown. Experiments were carried out to determine the role of TSLP in liver I/R injury. Wild-type (WT) and TSLP receptor–knockout (TSLPR–/–) mice were subjected to liver partial warm I/R injury. Liver injury was assessed by measuring serum alanine aminotransferase (ALT) level, necrotic areas by liver histology, hepatocyte death, and local hepatic inflammatory responses. Signal pathways were explored in vivo and in vitro to identify possible mechanisms for TSLP in I/R injury. TSLP and TSLPR protein expression increased during liver I/R in vivo and following hepatocyte hypoxia/reoxygenation in vitro. Deletion of TSLPR or neutralization of TSLP with anti-TSLP antibody exacerbated liver injury in terms of serum ALT levels as well as necrotic areas in liver histology. Administration of exogenous recombinant mouse TSLP to WT mice significantly reduced liver damage compared with controls, but failed to prevent I/R injury in TSLPR–/– mice. TSLP induced autophagy in hepatocytes during liver I/R injury. Mechanistically, Akt was activated in WT mice during liver I/R injury. The opposite results were observed in TSLPR–/– mice. In addition, TSLP could directly induce Akt activation in hepatocytes independent of nonparenchymal cells in vitro. Furthermore, the Akt agonist, insulin-like growth factor-1 (IGF-1), prevented I/R injury in TSLPR–/– mice and an Akt inhibitor, LY294002, blocked the protective effects of TSLP in WT mice subjected to I/R. Our data indicate that TSLP protects against liver I/R injury via activation of the PI3K/Akt pathway. Through this pathway, TSLP induces autophagy in hepatocytes. Thus, TSLP is a potent inhibitor of stress-induced hepatocyte necrosis.
Authors
Shilai Li, Zhongjie Yi, Meihong Deng, Melanie J. Scott, Chenxuan Yang, Wenbo Li, Zhao Lei, Nicole M. Santerre, Patricia Loughran, Timothy R. Billiar
Abstract
The adult mammalian heart regenerates poorly after injury and, as a result, ischemic heart diseases are among the leading causes of death worldwide. The recovery of the injured heart is dependent on orchestrated repair processes including inflammation, fibrosis, cardiomyocyte survival, proliferation, and contraction properties that could be modulated in patients. In this work we designed an automated high-throughput screening system for small molecules that induce cardiomyocyte proliferation in vitro and identified the small molecule Chicago Sky Blue 6B (CSB). Following induced myocardial infarction, CSB treatment reduced scar size and improved heart function of adult mice. Mechanistically, we show that although initially identified using in vitro screening for cardiomyocyte proliferation, in the adult mouse CSB promotes heart repair through (i) inhibition of CaMKII signaling, which improves cardiomyocyte contractility; and (ii) inhibition of neutrophil and macrophage activation, which attenuates the acute inflammatory response, thereby contributing to reduced scarring. In summary, we identified CSB as a potential therapeutic agent that enhances cardiac repair and function by suppressing postinjury detrimental processes, with no evidence for cardiomyocyte renewal.
Authors
Oren Yifa, Karen Weisinger, Elad Bassat, Hanjun Li, David Kain, Haim Barr, Noga Kozer, Alexander Genzelinakh, Dana Rajchman, Tamar Eigler, Kfir Baruch Umansky, Daria Lendengolts, Ori Brener, Nenad Bursac, Eldad Tzahor
Abstract
Mammalian focal adhesion proteins Pinch1 and Pinch2 regulate integrin activation and cell–extracellular matrix adhesion and migration. Here, we show that deleting Pinch1 in osteocytes and mature osteoblasts using the 10-kb mouse Dmp1-Cre and Pinch2 globally (double KO; dKO) results in severe osteopenia throughout life, while ablating either gene does not cause bone loss, suggesting a functional redundancy of both factors in bone. Pinch deletion in osteocytes and mature osteoblasts generates signals that inhibit osteoblast and bone formation. Pinch-deficient osteocytes and conditioned media from dKO bone slice cultures contain abundant sclerostin protein and potently suppress osteoblast differentiation in primary BM stromal cells (BMSC) and calvarial cultures. Pinch deletion increases adiposity in the BM cavity. Primary dKO BMSC cultures display decreased osteoblastic but enhanced adipogenic, differentiation capacity. Pinch loss decreases expression of integrin β3, integrin-linked kinase (ILK), and α-parvin and increases that of active caspase-3 and -8 in osteocytes. Pinch loss increases osteocyte apoptosis in vitro and in bone. Pinch loss upregulates expression of both Rankl and Opg in the cortical bone and does not increase osteoclast formation and bone resorption. Finally, Pinch ablation exacerbates hindlimb unloading–induced bone loss and impairs active ulna loading–stimulated bone formation. Thus, we establish a critical role of Pinch in control of bone homeostasis.
Authors
Yishu Wang, Qinnan Yan, Yiran Zhao, Xin Liu, Simin Lin, Peijun Zhang, Liting Ma, Yumei Lai, Xiaochun Bai, Chuanju Liu, Chuanyue Wu, Jian Q. Feng, Di Chen, Huiling Cao, Guozhi Xiao
Abstract
Broadly neutralizing Abs targeting the HA stem can provide broad protection against different influenza subtypes, raising the question of how best to elicit such Abs. We have previously demonstrated that vaccination with pandemic live-attenuated influenza vaccine (pLAIV) establishes immune memory for HA head-specific Abs. Here, we determine the extent to which matched versus mismatched LAIV-inactivated subunit vaccine (IIV) prime-boost vaccination elicits stem-specific memory B cells and Abs. We vaccinated African green monkeys with H5N1 pLAIV-pIIV or H5N1 pLAIV followed by seasonal IIV (sIIV) or with H5N1 pLAIV alone and measured Abs and HA-specific B cell responses. While we observed an increase in stem-specific memory B cells, head-specific memory B cell responses were substantially higher than stem-specific responses and were dominant even following boost with mismatched IIV. Neutralizing Abs against heterologous influenza viruses were undetectable. Head-specific B cells from draining lymph nodes exhibited germinal center markers, while stem-specific B cells found in the spleen and peripheral blood did not. Thus, although mismatched prime-boost generated a pool of stem-specific memory B cells, head-specific B cells and serum Abs substantially dominated the immune response. These findings have implications for including full-length native HA in prime-boost strategies intended to induce stem-specific Abs for universal influenza vaccination.
Authors
Sinthujan Jegaskanda, Sarah F. Andrews, Adam K. Wheatley, Jonathan W. Yewdell, Adrian B. McDermott, Kanta Subbarao
Abstract
In addition to its well-known beneficial effects for the treatment of several types of cancer, PD-1 blockade has shown encouraging results in preclinical models of sepsis and in a recent clinical trial in sepsis. Because cancer is the most common comorbidity in septic patients, here we aimed to determine the efficacy of PD-1 checkpoint blockade in the setting of sepsis complicated with preexisting malignancy. In a model of established lung cancer followed by cecal ligation and puncture–induced (CLP-induced) sepsis, PD-1 blockade exhibited no therapeutic effect on sepsis survival. This diminished efficacy of PD-1 blockade in cancer septic animals (septic animals with cancer) was characterized by a reduction in both the quality and quantity of PD-1+ responder cells. Specifically, CD8+ T cells isolated from cancer septic animals exhibited decreased CD28 expression and a reduction in the CXCR5+PD-1+ subset. In addition, flow cytometric analysis of T cells isolated from cancer septic animals revealed 2B4 as another possible checkpoint under these conditions. Administration of anti-2B4 to cancer septic animals significantly improved sepsis survival and was associated with increased T cell costimulatory receptor expression and decreased coinhibitory receptor expression. These results illustrate functions of coinhibitory receptors in the setting of sepsis complicated with cancer.
Authors
Ching-wen Chen, Ming Xue, Wenxiao Zhang, Jianfeng Xie, Craig M. Coopersmith, Mandy L. Ford
Abstract
Dysregulated citrullination, a unique form of posttranslational modification catalyzed by the peptidylarginine deiminases (PADs), has been observed in several human diseases, including rheumatoid arthritis. However, the physiological roles of PADs in the immune system are still poorly understood. Here, we report that global inhibition of citrullination enhances the differentiation of type 2 helper T (Th2) cells but attenuates the differentiation of Th17 cells, thereby increasing the susceptibility to allergic airway inflammation. This effect on Th cells is due to inhibition of PAD2 but not PAD4. Mechanistically, PAD2 directly citrullinates GATA3 and RORγt, 2 key transcription factors determining the fate of differentiating Th cells. Citrullination of R330 of GATA3 weakens its DNA binding ability, whereas citrullination of 4 arginine residues of RORγt strengthens its DNA binding. Finally, PAD2-deficient mice also display altered Th2/Th17 immune response and heightened sensitivity to allergic airway inflammation. Thus, our data highlight the potential and caveat of PAD2 as a therapeutic target of Th cell–mediated diseases.
Authors
Bo Sun, Hui-Hsin Chang, Ari Salinger, Beverly Tomita, Mandar Bawadekar, Caitlyn L. Holmes, Miriam A. Shelef, Eranthie Weerapana, Paul R. Thompson, I-Cheng Ho
Abstract
The ciliopathies are a group of phenotypically overlapping disorders caused by structural or functional defects in the primary cilium. Although disruption of numerous signaling pathways and cellular trafficking events have been implicated in ciliary pathology, treatment options for affected individuals remain limited. Here, we performed a genome-wide RNAi (RNA interference) screen to identify genetic suppressors of BBS4, one of the genes mutated in Bardet-Biedl syndrome (BBS). We discovered 10 genes that, when silenced, ameliorate BBS4-dependent pathology. One of these encodes USP35, a negative regulator of the ubiquitin proteasome system, suggesting that inhibition of a deubiquitinase, and subsequent facilitation of the clearance of signaling components, might ameliorate BBS-relevant phenotypes. Testing of this hypothesis in transient and stable zebrafish genetic models showed this posit to be true; suppression or ablation of usp35 ameliorated hallmark ciliopathy defects including impaired convergent extension (CE), renal tubule convolution, and retinal degeneration with concomitant clearance of effectors such as β-catenin and rhodopsin. Together, our findings reinforce a direct link between proteasome-dependent degradation and ciliopathies and suggest that augmentation of this system might offer a rational path to novel therapeutic modalities.
Authors
I-Chun Tsai, Kevin A. Adams, Joyce A. Tzeng, Omar Shennib, Perciliz L. Tan, Nicholas Katsanis
Abstract
Aging is a major risk factor for cardiovascular disease. Although the impact of aging has been extensively studied, little is known regarding the aging processes in cells of the heart. Here we analyzed the transcriptomes of hearts of 12-week-old and 18-month-old mice by single-nucleus RNA-sequencing. Among all cell types, aged fibroblasts showed most significant differential gene expression, increased RNA dynamics, and network entropy. Aged fibroblasts exhibited significantly changed expression patterns of inflammatory, extracellular matrix organization angiogenesis, and osteogenic genes. Functional analyses indicated deterioration of paracrine signatures between fibroblasts and endothelial cells in old hearts. Aged heart-derived fibroblasts had impaired endothelial cell angiogenesis and autophagy and augmented proinflammatory response. In particular, expression of Serpine1 and Serpine2 were significantly increased and secreted by old fibroblasts to exert antiangiogenic effects on endothelial cells, an effect that could be significantly prevented by using neutralizing antibodies. Moreover, we found an enlarged subpopulation of aged fibroblasts expressing osteoblast genes in the epicardial layer associated with increased calcification. Taken together this study provides system-wide insights and identifies molecular changes of aging cardiac fibroblasts, which may contribute to declined heart function.
Authors
Ramon Vidal, Julian Uwe Gabriel Wagner, Caroline Braeuning, Cornelius Fischer, Ralph Patrick, Lukas Tombor, Marion Muhly-Reinholz, David John, Magdalena Kliem, Thomas Conrad, Nuno Guimarães-Camboa, Richard Harvey, Stefanie Dimmeler, Sascha Sauer
Abstract
Mutations in B cell lymphoma 2–associated athanogene 3 (BAG3) are recurrently associated with dilated cardiomyopathy (DCM) and muscular dystrophy. Using isogenic genome-edited human induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs), we examined how a DCM-causing BAG3 mutation (R477H), as well as complete loss of BAG3 (KO), impacts myofibrillar organization and chaperone networks. Although unchanged at baseline, fiber length and alignment declined markedly in R477H and KO iPSC-CMs following proteasome inhibition. RNA sequencing revealed extensive baseline changes in chaperone- and stress response protein–encoding genes, and protein levels of key BAG3 binding partners were perturbed. Molecular dynamics simulations of the BAG3-HSC70 complex predicted a partial disengagement by the R477H mutation. In line with this, BAG3-R477H bound less HSC70 than BAG3-WT in coimmunoprecipitation assays. Finally, myofibrillar disarray triggered by proteasome inhibition in R477H cells was mitigated by overexpression of the stress response protein heat shock factor 1 (HSF1). These studies reveal the importance of BAG3 in coordinating protein quality control subsystem usage within the cardiomyocyte and suggest that augmenting HSF1 activity might be beneficial as a means to mitigate proteostatic stress in the context of BAG3-associated DCM.
Authors
Chris McDermott-Roe, Wenjian Lv, Tania Maximova, Shogo Wada, John Bukowy, Maribel Marquez, Shuping Lai, Amarda Shehu, Ivor Benjamin, Aron Geurts, Kiran Musunuru
Abstract
Filoviruses of the genus Ebolavirus include 6 species with marked differences in their ability to cause disease in humans. From the highly virulent Ebola virus to the seemingly nonpathogenic Reston virus, case fatality rates can range between 0% and 90%. In order to understand the molecular basis of these differences, it is imperative to establish disease models that recapitulate human disease as faithfully as possible. Nonhuman primates (NHPs) are the gold-standard models for filovirus pathogenesis, but comparative studies are skewed by the fact that Reston virus infection can be lethal for NHPs. Here we used HLA-A2–transgenic, NOD–scid–IL-2γ receptor–knockout (NSG-A2) mice reconstituted with human hematopoiesis to compare Ebola virus and Reston virus pathogenesis in a human-like environment. While markedly less pathogenic than Ebola virus, Reston virus killed 20% of infected mice, a finding that was linked to exacerbated inflammation and viral replication in the liver. In addition, the case fatality ratios of different Ebolavirus species in humans were recapitulated in the humanized mice. Our findings point to humanized mice as a putative model to test the pathogenicity of newly discovered filoviruses, and suggest that further investigations on Reston virus pathogenesis in humans are warranted.
Authors
Beatriz Escudero-Pérez, Paula Ruibal, Monika Rottstegge, Anja Lüdtke, Julia R. Port, Kristin Hartmann, Sergio Gómez-Medina, Jürgen Müller-Guhl, Emily V. Nelson, Susanne Krasemann, Estefanía Rodríguez, César Muñoz-Fontela
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