Latest issue: September 7, 2017

In the issue

Abstract

Advanced breast cancer is frequently associated with skeletal metastases and accelerated bone loss. Recombinant parathyroid hormone [teriparatide, PTH(1-34)] is the first anabolic agent approved in the US for treatment of osteoporosis. While signaling through the PTH receptor in the osteoblast lineage regulates bone marrow hematopoietic niches, the effects of anabolic PTH on the skeletal metastatic niche are unknown. Here, we demonstrate, using orthotopic and intratibial models of 4T1 murine and MDA-MB-231 human breast cancer tumors, that anabolic PTH decreases both tumor engraftment and the incidence of spontaneous skeletal metastasis in mice. Microcomputed tomography and histomorphometric analyses revealed that PTH increases bone volume and reduces tumor engraftment and volume. Transwell migration assays with murine and human breast cancer cells revealed that PTH alters the gene expression profile of the metastatic niche, in particular VCAM-1, to inhibit recruitment of cancer cells. While PTH did not affect growth or migration of the primary tumor, it elicited several changes in the tumor gene expression profile resulting in a less metastatic phenotype. In conclusion, PTH treatment in mice alters the bone microenvironment, resulting in decreased cancer cell engraftment, reduced incidence of metastases, preservation of bone microarchitecture and prolonged survival.

Authors

Srilatha Swami, Joshua Johnson, Lance A. Bettinson, Takaharu Kimura, Hui Zhu, Megan A. Albertelli, Rachelle W. Johnson, Joy Y. Wu

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Abstract

Cardiac hypertrophy, as a response to hemodynamic stress, is associated with cardiac dysfunction and death, but whether hypertrophy itself represents a pathological process remains unclear. Hypertrophy is driven by changes in myocardial gene expression that require the MEF2 family of DNA-binding transcription factors, as well as the nuclear lysine acetyltransferase p300. Here we used genetic and small-molecule probes to determine the effects of preventing MEF2 acetylation on cardiac adaptation to stress. Both nonacetylatable MEF2 mutants and 8MI, a molecule designed to interfere with MEF2-coregulator binding, prevented hypertrophy in cultured cardiac myocytes. 8MI prevented cardiac hypertrophy in 3 distinct stress models, and reversed established hypertrophy in vivo, associated with normalization of myocardial structure and function. The effects of 8MI were reversible, and did not prevent training effects of swimming. Mechanistically, 8MI blocked stress-induced MEF2 acetylation, nuclear export of class II histone deacetylases HDAC4 and -5, and p300 induction, without impeding HDAC4 phosphorylation. Correspondingly, 8MI transformed the transcriptional response to pressure overload, normalizing almost all 232 genes dysregulated by hemodynamic stress. We conclude that MEF2 acetylation is required for development and maintenance of pathological cardiac hypertrophy, and that blocking MEF2 acetylation can permit recovery from hypertrophy without impairing physiologic adaptation.

Authors

Jianqin Wei, Shaurya Joshi, Svetlana Speransky, Christopher Crowley, Nimanthi Jayathilaka, Xiao Lei, Yongqing Wu, David Gai, Sumit Jain, Michael Hoosien, Yan Gao, Lin Chen, Nanette H. Bishopric

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Abstract

The factors that promote the differentiation of pathogenic T cells in autoimmune diseases are poorly defined. Use of genetically modified mice has provided insight into molecules necessary for the development of autoimmunity, but the sum of the data has led to contradictory observations based on what is currently known about specific molecules in specific signaling pathways. To define the minimum signals required for development of encephalitogenic T cells that cause CNS autoimmunity, myelin-specific T cells were differentiated with various cytokine cocktails, and pathogenicity was determined by transfer into mice. IL-6+IL-23 or IL-12+IL-23 generated encephalitogenic T cells and recapitulated the essential cytokine signals provided by antigen-presenting cells, and both IL-6 and IL-12 induced IL-23 receptor expression on both mouse and human naive T cells. IL-23 signaled through both STAT3 and STAT4, and disruption in STAT4 signaling impaired CNS autoimmunity independent of IL-12. These data explain why IL-12–deficient mice develop CNS autoimmunity, while STAT4-deficient mice are resistant. CD4+ memory T cells from multiple sclerosis patients had significantly higher levels of p-STAT3/p-STAT4, and p-STAT3/p-STAT4 heterodimers were observed upon IL-23 signaling, suggesting that p-STAT3/p-STAT4 induced by IL-23 signaling orchestrate the generation of pathogenic T cells in CNS autoimmunity, regardless of Th1 or Th17 phenotype.

Authors

Priscilla W. Lee, Alan J. Smith, Yuhong Yang, Amanda J. Selhorst, Yue Liu, Michael K. Racke, Amy E. Lovett-Racke

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Abstract

Recent data indicate that there are different subpopulations of Th17 cells that can express a regulatory as opposed to an inflammatory gene signature. The transmembrane glycoprotein PDPN is critical in the development of multiple organs including the lymphatic system and has been described on T cells in mouse models of autoimmune Th17 inflammation. Here, we demonstrate that unlike in mice, PDPN+ T cells induced under classic Th17-polarizing conditions express transcription factors associated with Th17 cells but do not produce IL-17. Moreover, these cells express a transcriptional profile enriched for immunosuppressive and regulatory pathways and express a distinct cytokine profile compared with potentially pathogenic PDPN– Th17 cells. Ligation of PDPN by its ligand CLEC-2 ameliorates the Th17 inflammatory response. IL-17 secretion is restored with shRNA gene silencing of PDPN. Furthermore, PDPN expression is reduced via an Sgk1-mediated pathway under proinflammatory, high sodium chloride conditions. Finally, CD3+PDPN+ T cells are devoid of IL-17 in skin biopsies from patients with candidiasis, a prototypical Th17-driven skin disease. Thus, our data support the hypothesis that PDPN may serve as a marker of a nonpathogenic Th17 cell subset and may also functionally regulate pathogenic Th17 inflammation.

Authors

Alyssa N. Nylander, Gerald D. Ponath, Pierre-Paul Axisa, Mayyan Mubarak, Mary Tomayko, Vijay K. Kuchroo, David Pitt, David A. Hafler

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Abstract

Heart disease remains the leading cause of death worldwide, highlighting a pressing need to identify novel regulators of cardiomyocyte (CM) function that could be therapeutically targeted. The mammalian Hippo/Tead pathway is critical in embryonic cardiac development and perinatal CM proliferation. However, the requirement of Tead1, the transcriptional effector of this pathway, in the adult heart is unknown. Here, we show that tamoxifen-inducible adult CM–specific Tead1 ablation led to lethal acute-onset dilated cardiomyopathy, associated with impairment in excitation-contraction coupling. Mechanistically, we demonstrate Tead1 is a cell-autonomous, direct transcriptional activator of SERCA2a and SR-associated protein phosphatase 1 regulatory subunit, Inhibitor-1 (I-1). Thus, Tead1 deletion led to a decrease in SERCA2a and I-1 transcripts and protein, with a consequent increase in PP1-activity, resulting in accumulation of dephosphorylated phospholamban (Pln) and decreased SERCA2a activity. Global transcriptomal analysis in Tead1-deleted hearts revealed significant changes in mitochondrial and sarcomere-related pathways. Additional studies demonstrated there was a trend for correlation between protein levels of TEAD1 and I-1, and phosphorylation of PLN, in human nonfailing and failing hearts. Furthermore, TEAD1 activity was required to maintain PLN phosphorylation and expression of SERCA2a and I-1 in human induced pluripotent stem cell–derived (iPS-derived) CMs. To our knowledge, taken together, this demonstrates a nonredundant, novel role of Tead1 in maintaining normal adult heart function.

Authors

Ruya Liu, Jeongkyung Lee, Byung S. Kim, Qiongling Wang, Samuel K. Buxton, Nikhil Balasubramanyam, Jean J. Kim, Jianrong Dong, Aijun Zhang, Shumin Li, Anisha A. Gupte, Dale J. Hamilton, James F. Martin, George G. Rodney, Cristian Coarfa, Xander H.T. Wehrens, Vijay K. Yechoor, Mousumi Moulik

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Abstract

Transcriptionally activated monocytes are recruited to the heart after acute myocardial infarction (AMI). After AMI in mice and humans, the number of extracellular vesicles (EVs) increased acutely. In humans, EV number correlated closely with the extent of myocardial injury. We hypothesized that EVs mediate splenic monocyte mobilization and program transcription following AMI. Some plasma EVs bear endothelial cell (EC) integrins, and both proinflammatory stimulation of ECs and AMI significantly increased VCAM-1–positive EV release. Injected EC-EVs localized to the spleen and interacted with, and mobilized, splenic monocytes in otherwise naive, healthy animals. Analysis of human plasma EV-associated miRNA showed 12 markedly enriched miRNAs after AMI; functional enrichment analyses identified 1,869 putative mRNA targets, which regulate relevant cellular functions (e.g., proliferation and cell movement). Furthermore, gene ontology termed positive chemotaxis as the most enriched pathway for the miRNA-mRNA targets. Among the identified EV miRNAs, EC-associated miRNA-126-3p and -5p were highly regulated after AMI. miRNA-126-3p and -5p regulate cell adhesion– and chemotaxis-associated genes, including the negative regulator of cell motility, plexin-B2. EC-EV exposure significantly downregulated plexin-B2 mRNA in monocytes and upregulated motility integrin ITGB2. These findings identify EVs as a possible novel signaling pathway by linking ischemic myocardium with monocyte mobilization and transcriptional activation following AMI.

Authors

Naveed Akbar, Janet E. Digby, Thomas J. Cahill, Abhijeet N. Tavare, Alastair L. Corbin, Sushant Saluja, Sam Dawkins, Laurienne Edgar, Nadiia Rawlings, Klemen Ziberna, Eileen McNeill, Oxford Acute Myocardial Infarction (OxAMI) Study, Errin Johnson, Alaa A. Aljabali, Rebecca A. Dragovic, Mala Rohling, T. Grant Belgard, Irina A. Udalova, David R. Greaves, Keith M. Channon, Paul R. Riley, Daniel C. Anthony, Robin P. Choudhury

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Abstract

Eradication of the HIV-1 latent reservoir represents the current paradigm to developing a cure for AIDS. HIV-1 has evolved multiple mechanisms to evade CD8 T cell responses, including HIV-1 Nef–mediated downregulation of MHC-I from the surface of infected cells. Nef transcripts and protein are detectable in samples from aviremic donors, suggesting that Nef expression in latently HIV-1–infected CD4 T cells protects them from immune-mediated clearance. Here, we tested 4 small molecule inhibitors of HIV-1 Nef in an in vitro primary CD4 T cell latency model and measured the ability of autologous ex vivo or HIV-1 peptide–expanded CD8 T cells to recognize and kill latently infected cells as a function of inhibitor treatment. Nef inhibition enhanced cytokine secretion by autologous CD8 T cells against latently HIV-1–infected targets in an IFN-γ release assay. Additionally, CD8 T cell–mediated elimination of latently HIV-1–infected cells was significantly enhanced following Nef blockade, measured as a reduction in the frequency of infected cells and Gag protein in cultures following viral outgrowth assays. We demonstrate for the first time to our knowledge that Nef blockade, in combination with HIV-specific CD8 T cell expansion, might be a feasible strategy to target the HIV-1 latent reservoir that should be tested further in vivo.

Authors

Shariq Mujib, Aamir Saiyed, Saleh Fadel, Ardalan Bozorgzad, Nasra Aidarus, Feng Yun Yue, Erika Benko, Colin Kovacs, Lori A. Emert-Sedlak, Thomas E. Smithgall, Mario A. Ostrowski

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Abstract

Decreased cortical thickness and increased cortical porosity are the key anatomic changes responsible for osteoporotic fractures in elderly women and men. The cellular basis of these changes is unbalanced endosteal and intracortical osteonal remodeling by the osteoclasts and osteoblasts that comprise the basic multicellular units (BMUs). Like humans, mice lose cortical bone with age, but unlike humans, this loss occurs in the face of sex steroid sufficiency. Mice are therefore an ideal model to dissect age-specific osteoporotic mechanisms. Nevertheless, lack of evidence for endosteal or intracortical remodeling in mice has raised questions about their translational relevance. We show herein that administration of the antiosteoclastogenic cytokine osteoprotegerin to Swiss Webster mice ablated not only osteoclasts, but also endosteal bone formation, demonstrating the occurrence of BMU-based endosteal remodeling. Femoral cortical thickness decreased in aged male and female C57BL/6J mice, as well as F1 hybrids of C57BL/6J and BALB/cBy mice. This decrease was greater in C57BL/6J mice, indicating a genetic influence. Moreover, endosteal remodeling became unbalanced because of increased osteoclast and decreased osteoblast numbers. The porosity of the femoral cortex increased with age but was much higher in females of both strains. Notably, the increased cortical porosity resulted from de novo intracortical remodeling by osteon-like structures. Age-dependent cortical bone loss was associated with increased osteocyte DNA damage, cellular senescence, the senescence-associated secretory phenotype, and increased levels of RANKL. The demonstration of unbalanced endosteal and intracortical remodeling in old mice validates the relevance of this animal model to involutional osteoporosis in humans.

Authors

Marilina Piemontese, Maria Almeida, Alexander G. Robling, Ha-Neui Kim, Jinhu Xiong, Jeff D. Thostenson, Robert S. Weinstein, Stavros C. Manolagas, Charles A. O’Brien, Robert L. Jilka

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Abstract

The role of B cells and posttranslational modifications in pathogenesis of organ-specific immune diseases is increasingly envisioned but remains poorly understood, particularly in human disorders. In celiac disease, transglutaminase 2–modified (TG2-modified; deamidated) gluten peptides drive disease-specific T cell and B cell responses, and antibodies to deamidated gluten peptides are excellent diagnostic markers. Here, we substantiate by high-throughput sequencing of IGHV genes that antibodies to a disease-specific, deamidated, and immunodominant B cell epitope of gluten (PLQPEQPFP) have biased and stereotyped usage of IGHV3-23 and IGHV3-15 gene segments with modest somatic mutations. X-ray crystal structures of 2 prototype IGHV3-15/IGKV4-1 and IGHV3-23/IGLV4-69 antibodies reveal peptide interaction mainly via germline-encoded residues. In-depth mutational analysis showed restricted selection and substitution patterns at positions involved in antigen binding. While the IGHV3-15/IGKV4-1 antibody interacts with Glu5 and Gln6, the IGHV3-23/IGLV4-69 antibody interacts with Gln3, Pro4, Pro7, and Phe8 — residues involved in substrate recognition by TG2. Hence, both antibodies, despite different interaction with the epitope, recognize signatures of TG2 processing that facilitates B cell presentation of deamidated gluten peptides to T cells, thereby providing a molecular framework for the generation of these clinically important antibodies. The study provides essential insight into the pathogenic mechanism of celiac disease.

Authors

Omri Snir, Xi Chen, Moriah Gidoni, M. Fleur du Pré, Yuguang Zhao, Øyvind Steinsbø, Knut E.A. Lundin, Gur Yaari, Ludvig M. Sollid

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Abstract

Cardiomyopathy frequently complicates sepsis and is associated with increased mortality. Increased cardiac oxidative stress and mitochondrial dysfunction have been observed during sepsis, but the mechanisms responsible for these abnormalities have not been determined. We hypothesized that NADPH oxidase 2 (NOX2) activation could be responsible for sepsis-induced oxidative stress and cardiomyopathy. Treatment of isolated adult mouse cardiomyocytes with low concentrations of the endotoxin lipopolysaccharide (LPS) increased total cellular reactive oxygen species (ROS) and mitochondrial superoxide. Elevated mitochondrial superoxide was accompanied by depolarization of the mitochondrial inner membrane potential, an indication of mitochondrial dysfunction, and mitochondrial calcium overload. NOX2 inhibition decreased LPS-induced superoxide and prevented mitochondrial dysfunction. Further, cardiomyocytes from mice with genetic ablation of NOX2 did not have LPS-induced superoxide or mitochondrial dysfunction. LPS decreased contractility and calcium transient amplitude in isolated cardiomyocytes, and these abnormalities were prevented by inhibition of NOX2. LPS decreased systolic function in mice, measured by echocardiography. NOX2 inhibition was cardioprotective in 2 mouse models of sepsis, preserving systolic function after LPS injection or cecal ligation and puncture (CLP). These data show that inhibition of NOX2 decreases oxidative stress, preserves intracellular calcium handling and mitochondrial function, and alleviates sepsis-induced systolic dysfunction in vivo. Thus, NOX2 is a potential target for pharmacotherapy of sepsis-induced cardiomyopathy.

Authors

Leroy C. Joseph, Dimitra Kokkinaki, Mesele-Christina Valenti, Grace J. Kim, Emanuele Barca, Dhanendra Tomar, Nicholas E. Hoffman, Prakash Subramanyam, Henry M. Colecraft, Michio Hirano, Adam J. Ratner, Muniswamy Madesh, Konstantinos Drosatos, John P. Morrow

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Abstract

Myasthenia gravis (MG) is a B cell–mediated autoimmune disorder of neuromuscular transmission. Pathogenic autoantibodies to muscle-specific tyrosine kinase (MuSK) can be found in patients with MG who do not have detectable antibodies to the acetylcholine receptor (AChR). MuSK MG includes immunological and clinical features that are generally distinct from AChR MG, particularly regarding responsiveness to therapy. B cell depletion has been shown to affect a decline in serum autoantibodies and to induce sustained clinical improvement in the majority of MuSK MG patients. However, the duration of this benefit may be limited, as we observed disease relapse in MuSK MG patients who had achieved rituximab-induced remission. We investigated the mechanisms of such relapses by exploring autoantibody production in the reemerging B cell compartment. Autoantibody-expressing CD27+ B cells were observed within the reconstituted repertoire during relapse but not during remission or in controls. Using two complementary approaches, which included production of 108 unique human monoclonal recombinant immunoglobulins, we demonstrated that antibody-secreting CD27hiCD38hi B cells (plasmablasts) contribute to the production of MuSK autoantibodies during relapse. The autoantibodies displayed hallmarks of antigen-driven affinity maturation. These collective findings introduce potential mechanisms for understanding both MuSK autoantibody production and disease relapse following B cell depletion.

Authors

Panos Stathopoulos, Aditya Kumar, Richard J. Nowak, Kevin C. O’Connor

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Abstract

BACKGROUND. In obese subjects with obstructive sleep apnea (OSA), chronic intermittent hypoxia (CIH) may be linked to systemic and adipose tissue inflammation. METHODS. We obtained abdominal subcutaneous adipose tissue biopsies from OSA and non-OSA obese (BMI > 35) subjects at baseline and after 24 weeks (T1) of weight-loss intervention plus continuous positive airway pressure (c-PAP) or weight-loss intervention alone, respectively. OSA subjects were grouped according to good (therapeutic) or poor (subtherapeutic) adherence to c-PAP. RESULTS. At baseline, anthropometric and metabolic parameters, serum cytokines, and adipose tissue mRNA levels of obesity-associated chemokines and inflammatory markers were not different in OSA and non-OSA subjects. At T1, body weight was significantly reduced in all groups. Serum concentrations of IL-2, IL-4, IL-6, MCP-1, PDGFβ, and VEGFα were reduced by therapeutic c-PAP in OSA subjects and remained unaltered in non-OSA and subtherapeutic c-PAP groups. Similarly, adipose tissue mRNA levels of macrophage-specific (CD68, CD36) and ER stress (ATF4, CHOP, ERO-1) gene markers, as well as of IL-6, PDGFβ, and VEGFα, were decreased only in the therapeutic c-PAP group. CONCLUSION. CIH does not represent an additional factor increasing systemic and adipose tissue inflammation in morbid obesity. However, in subjects with OSA, an effective c-PAP therapy improves systemic and obesity-associated inflammatory markers. FUNDING. Ministero dell’Università e della Ricerca and Progetti di Rilevante Interesse Nazionale.

Authors

Sebastio Perrini, Angelo Cignarelli, Vitaliano Nicola Quaranta, Vito Antonio Falcone, Stella Kounaki, Stefania Porro, Alessandro Ciavarella, Romina Ficarella, Maria Barbaro, Valentina Annamaria Genchi, Pasquale Nigro, Pierluigi Carratù, Annalisa Natalicchio, Luigi Laviola, Onofrio Resta, Francesco Giorgino

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Abstract

Human endogenous retroviruses (HERVs), remnants of ancestral viral genomic insertions, are known to represent 8% of the human genome and are associated with several pathologies. In particular, the envelope protein of HERV-W family (HERV-W-Env) has been involved in multiple sclerosis pathogenesis. Investigations to detect HERV-W-Env in a few other autoimmune diseases were negative, except in type-1 diabetes (T1D). In patients suffering from T1D, HERV-W-Env protein was detected in 70% of sera, and its corresponding RNA was detected in 57% of peripheral blood mononuclear cells. While studies on human Langerhans islets evidenced the inhibition of insulin secretion by HERV-W-Env, this endogenous protein was found to be expressed by acinar cells in 75% of human T1D pancreata. An extensive immunohistological analysis further revealed a significant correlation between HERV-W-Env expression and macrophage infiltrates in the exocrine part of human pancreata. Such findings were corroborated by in vivo studies on transgenic mice expressing HERV-W-env gene, which displayed hyperglycemia and decreased levels of insulin, along with immune cell infiltrates in their pancreas. Altogether, these results strongly suggest an involvement of HERV-W-Env in T1D pathogenesis. They also provide potentially novel therapeutic perspectives, since unveiling a pathogenic target in T1D.

Authors

Sandrine Levet, Julie Medina, Julie Joanou, Amandine Demolder, Nelly Queruel, Kevin Réant, Matthieu Normand, Marine Seffals, Julie Dimier, Raphaële Germi, Thomas Piofczyk, Jacques Portoukalian, Jean-Louis Touraine, Hervé Perron

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Abstract

Respiratory syncytial virus (RSV) infects almost all infants by 2 years of age, and severe bronchiolitis resulting from RSV infection is the primary cause of hospitalization in the first year of life. Among infants hospitalized due to RSV-induced bronchiolitis, those with a specific mutation in the chemokine receptor CX3CR1, which severely compromises binding of its ligand CX3CL1, were at a higher risk for more severe viral bronchiolitis than those without the mutation. Here, we show that RSV infection of newborn mice deficient in CX3CR1 leads to significantly greater neutrophilic inflammation in the lungs, accompanied by an increase in mucus production compared with that induced in WT mice. Analysis of innate and adaptive immune responses revealed an early increase in the number of IL-17+ γδ T cells in CX3CR1-deficient mice that outnumbered IFN-γ+ γδ T cells as well as IFN-γ+ NK cells, IFN-γ being host protective in the context of RSV infection. This bias toward IL-17+ γδ T cells persisted at a later time. The lungs of CX3CR1-deficient mice expressed higher levels of IL-1β mRNA and protein, and blockade of IL-1β signaling using IL-1 receptor antagonist significantly reduced the number of IL-17+ γδ T cells in the lungs of infected mice. Blockade of IL-17RC abolished RSV-induced lung pathology in infected CX3CR1-deficient mice. We propose that, in infants harboring mutant CX3CR1, targeting the IL-17R may minimize disease severity and hospitalization in early life.

Authors

Sudipta Das, Mahesh Raundhal, Jie Chen, Timothy B. Oriss, Rachael Huff, John V. Williams, Anuradha Ray, Prabir Ray

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Abstract

Ventricular chamber growth and development during perinatal circulatory transition is critical for functional adaptation of the heart. However, the chamber-specific programs of neonatal heart growth are poorly understood. We used integrated systems genomic and functional biology analyses of the perinatal chamber specific transcriptome and we identified Wnt11 as a prominent regulator of chamber-specific proliferation. Importantly, downregulation of Wnt11 expression was associated with cyanotic congenital heart defect (CHD) phenotypes and correlated with O2 saturation levels in hypoxemic infants with Tetralogy of Fallot (TOF). Perinatal hypoxia treatment in mice suppressed Wnt11 expression and induced myocyte proliferation more robustly in the right ventricle, modulating Rb1 protein activity. Wnt11 inactivation was sufficient to induce myocyte proliferation in perinatal mouse hearts and reduced Rb1 protein and phosphorylation in neonatal cardiomyocytes. Finally, downregulated Wnt11 in hypoxemic TOF infantile hearts was associated with Rb1 suppression and induction of proliferation markers. This study revealed a previously uncharacterized function of Wnt11-mediated signaling as an important player in programming the chamber-specific growth of the neonatal heart. This function influences the chamber-specific development and pathogenesis in response to hypoxia and cyanotic CHDs. Defining the underlying regulatory mechanism may yield chamber-specific therapies for infants born with CHDs.

Authors

Marlin Touma, Xuedong Kang, Fuying Gao, Yan Zhao, Ashley A. Cass, Reshma Biniwale, Xinshu Xiao, Mansuoreh Eghbali, Giovanni Coppola, Brian Reemtsen, Yibin Wang

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Abstract

We developed an in vitro model system where induced pluripotent stem cells (iPSCs) differentiate into 3-dimensional human hepatic organoids (HOs) through stages that resemble human liver during its embryonic development. The HOs consist of hepatocytes, and cholangiocytes, which are organized into epithelia that surround the lumina of bile duct–like structures. The organoids provide a potentially new model for liver regenerative processes, and were used to characterize the effect of different JAG1 mutations that cause: (a) Alagille syndrome (ALGS), a genetic disorder where NOTCH signaling pathway mutations impair bile duct formation, which has substantial variability in its associated clinical features; and (b) Tetralogy of Fallot (TOF), which is the most common form of a complex congenital heart disease, and is associated with several different heritable disorders. Our results demonstrate how an iPSC-based organoid system can be used with genome editing technologies to characterize the pathogenetic effect of human genetic disease-causing mutations.

Authors

Yuan Guan, Dan Xu, Phillip M. Garfin, Ursula Ehmer, Melissa Hurwitz, Greg Enns, Sara Michie, Manhong Wu, Ming Zheng, Toshihiko Nishimura, Julien Sage, Gary Peltz

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Abstract

Oxidative stress is important in the pathogenesis of allergic asthma. Extracellular superoxide dismutase (EC-SOD; SOD3) is the major antioxidant in lungs, but its role in allergic asthma is unknown. Here we report that asthmatics have increased SOD3 transcript levels in sputum and that a single nucleotide polymorphism (SNP) in SOD3 (R213G; rs1799895) changes lung distribution of EC-SOD, and decreases likelihood of asthma-related symptoms. Knockin mice analogous to the human R213G SNP had lower airway hyperresponsiveness, inflammation, and mucus hypersecretion with decreased interleukin-33 (IL-33) in bronchoalveolar lavage fluid and reduced type II innate lymphoid cells (ILC2s) in lungs. SOD mimetic (Mn (III) tetrakis (N-ethylpyridinium-2-yl) porphyrin) attenuated Alternaria-induced expression of IL-33 and IL-8 release in BEAS-2B cells. These results suggest that R213G SNP potentially benefits its carriers by resulting in high EC-SOD in airway-lining fluid, which ameliorates allergic airway inflammation by dampening the innate immune response, including IL-33/ST2–mediated changes in ILC2s.

Authors

Rohit Gaurav, Jason T. Varasteh, Michael R. Weaver, Sean R. Jacobson, Laura Hernandez-Lagunas, Qing Liu, Eva Nozik-Grayck, Hong Wei Chu, Rafeul Alam, Børge G. Nordestgaard, Camilla J. Kobylecki, Shoaib Afzal, Geoffrey L. Chupp, Russell P. Bowler

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Abstract

A cure for heart failure remains a major unmet clinical need, and current therapies targeting neurohomonal and hemodynamic regulation have limited efficacy. The pathological remodeling of the myocardium has been associated with a stereotypical gene expression program, which had long been viewed as the consequence and not the driver of the disease until very recently. Despite the advance, there is no therapy available to reverse the already committed gene program. Here, we demonstrate that transcriptional repressor REV-ERB binds near driver transcription factors across the genome. Pharmacological activation of REV-ERB selectively suppresses aberrant pathologic gene expression and prevents cardiomyocyte hypertrophy. In vivo, REV-ERBα activation prevents development of cardiac hypertrophy, reduces fibrosis, and halts progression of advanced heart failure in mouse models. Thus, to our knowledge, modulation of gene networks by targeting REV-ERBα represents a novel approach to heart failure therapy.

Authors

Lilei Zhang, Rongli Zhang, Chih-Liang Tien, Ricky E. Chan, Keiki Sugi, Chen Fu, Austin C. Griffin, Yuyan Shen, Thomas P. Burris, Xudong Liao, Mukesh K. Jain

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Abstract

Selection of biased T cell receptor (TCR) repertoires across individuals is seen in both infectious diseases and autoimmunity, but the underlying molecular basis leading to these shared repertoires remains unclear. Celiac disease (CD) occurs primarily in HLA-DQ2.5+ individuals and is characterized by a CD4+ T cell response against gluten epitopes dominated by DQ2.5-glia-α1a and DQ2.5-glia-α2. The DQ2.5-glia-α2 response recruits a highly biased TCR repertoire composed of TRAV26-1 paired with TRBV7-2 harboring a semipublic CDR3β loop. We aimed to unravel the molecular basis for this signature. By variable gene segment exchange, directed mutagenesis, and cellular T cell activation studies, we found that TRBV7-3 can substitute for TRBV7-2, as both can contain the canonical CDR3β loop. Furthermore, we identified a pivotal germline-encoded MHC recognition motif centered on framework residue Y40 in TRAV26-1 engaging both DQB1*02 and the canonical CDR3β. This allowed prediction of expanded DQ2.5-glia-α2–reactive TCR repertoires, which were confirmed by single-cell sorting and TCR sequencing from CD patient samples. Our data refine our understanding of how HLA-dependent biased TCR repertoires are selected in the periphery due to germline-encoded residues.

Authors

Kristin Støen Gunnarsen, Lene Støkken Høydahl, Louise Fremgaard Risnes, Shiva Dahal-Koirala, Ralf Stefan Neumann, Elin Bergseng, Terje Frigstad, Rahel Frick, M. Fleur du Pré, Bjørn Dalhus, Knut E.A. Lundin, Shuo-Wang Qiao, Ludvig M. Sollid, Inger Sandlie, Geir Åge Løset

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Abstract

Abnormal airway smooth muscle function can contribute to cystic fibrosis (CF) airway disease. We previously found that airway smooth muscle from newborn CF pigs had increased basal tone, an increased bronchodilator response, and abnormal calcium handling. Since CF pigs lack airway infection and inflammation at birth, these findings suggest intrinsic airway smooth muscle dysfunction in CF. In this study, we tested the hypothesis that CFTR loss in airway smooth muscle would produce a distinct set of changes in the airway smooth muscle transcriptome that we could use to develop novel therapeutic targets. Total RNA sequencing of newborn wild-type and CF airway smooth muscle revealed changes in muscle contraction–related genes, ontologies, and pathways. Using connectivity mapping, we identified several small molecules that elicit transcriptional signatures opposite of CF airway smooth muscle, including NVP-TAE684, an inhibitor of proline-rich tyrosine kinase 2 (PYK2). In CF airway smooth muscle tissue, PYK2 phosphorylation was increased and PYK2 inhibition decreased smooth muscle contraction. In vivo NVP-TAE684 treatment of wild-type mice reduced methacholine-induced airway smooth muscle contraction. These findings suggest that studies in the newborn CF pig may provide an important approach to enhance our understanding of airway smooth muscle biology and for discovery of novel airway smooth muscle therapeutics for CF and other diseases of airway hyperreactivity.

Authors

Daniel P. Cook, Ryan J. Adam, Keyan Zarei, Benjamin Deonovic, Mallory R. Stroik, Nicholas D. Gansemer, David K. Meyerholz, Kin Fai Au, David A. Stoltz

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Abstract

BACKGROUND. The impact of resistance exercise training (RE-T) across the life span is poorly defined. METHODS. To resolve this, we recruited three distinct age cohorts of young (18–28 years; n = 11), middle-aged (45–55 years; n = 20), and older (nonsarcopenic; 65–75 years; n = 17) individuals to a cross-sectional intervention study. All subjects participated in 20 weeks of fully supervised whole-body progressive RE-T, undergoing assessment of body composition, muscle and vascular function, and metabolic health biomarkers before and after RE-T. Individuals also received stable isotope tracer infusions to ascertain muscle protein synthesis (MPS). RESULTS. There was an age-related increase in adiposity, but only young and middle-age groups demonstrated reductions following RE-T. Increases in blood pressure with age were attenuated by RE-T in middle-aged, but not older, individuals, while age-related increases in leg vascular conductance were unaffected by RE-T. The index of insulin sensitivity was reduced by RE-T in older age. Despite being matched at baseline, only younger individuals increased muscle mass in response to RE-T, and there existed a negative correlation between age and muscle growth; in contrast, increases in mechanical quality were preserved across ages. Acute increases in MPS (upon feeding plus acute RE-T) were enhanced only in younger individuals, perhaps explaining greater hypertrophy. CONCLUSION. Our data indicate that RE-T offsets some, but not all, negative characteristics of ageing — some of which are apparent in midlife. FUNDING. Biotechnology and Biological Sciences Research Council (BB/C516779/1).

Authors

Bethan E. Phillips, John P. Williams, Paul L. Greenhaff, Kenneth Smith, Philip J. Atherton

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Abstract

Bone metastases (BoM) are a significant cause of morbidity in patients with estrogen receptor–positive (ER-positive) breast cancer; yet, characterizations of human specimens are limited. In this study, exome-capture RNA sequencing (ecRNA-seq) on aged (8–12 years), formalin-fixed, paraffin-embedded (FFPE), and decalcified cancer specimens was evaluated. Gene expression values and ecRNA-seq quality metrics from FFPE or decalcified tumor RNA showed minimal differences when compared with matched flash-frozen or nondecalcified tumors. ecRNA-seq was then applied on a longitudinal collection of 11 primary breast cancers and patient-matched synchronous or recurrent BoMs. Overtime, BoMs exhibited gene expression shifts to more Her2 and LumB PAM50 subtype profiles, temporally influenced expression evolution, recurrently dysregulated prognostic gene sets, and longitudinal expression alterations of clinically actionable genes, particularly in the CDK/Rb/E2F and FGFR signaling pathways. Taken together, this study demonstrates the use of ecRNA-seq on decade-old and decalcified specimens and defines recurrent longitudinal transcriptional remodeling events in estrogen-deprived breast cancers.

Authors

Nolan Priedigkeit, Rebecca J. Watters, Peter C. Lucas, Ahmed Basudan, Rohit Bhargava, William Horne, Jay K. Kolls, Zhou Fang, Margaret Q. Rosenzweig, Adam M. Brufsky, Kurt R. Weiss, Steffi Oesterreich, Adrian V. Lee

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Abstract

The oncoprotein Mdm2 is a RING domain–containing E3 ubiquitin ligase that ubiquitinates G protein–coupled receptor kinase 2 (GRK2) and β-arrestin2, thereby regulating β-adrenergic receptor (βAR) signaling and endocytosis. Previous studies showed that cardiac Mdm2 expression is critical for controlling p53-dependent apoptosis during early embryonic development, but the role of Mdm2 in the developed adult heart is unknown. We aimed to identify if Mdm2 affects βAR signaling and cardiac function in adult mice. Using Mdm2/p53–KO mice, which survive for 9–12 months, we identified a critical and potentially novel role for Mdm2 in the adult mouse heart through its regulation of cardiac β1AR signaling. While baseline cardiac function was mostly similar in both Mdm2/p53–KO and wild-type (WT) mice, isoproterenol-induced cardiac contractility in Mdm2/p53–KO was significantly blunted compared with WT mice. Isoproterenol increased cAMP in left ventricles of WT but not of Mdm2/p53–KO mice. Additionally, while basal and forskolin-induced calcium handling in isolated Mdm2/p53–KO and WT cardiomyocytes were equivalent, isoproterenol-induced calcium handling in Mdm2/p53–KO was impaired. Mdm2/p53–KO hearts expressed 2-fold more GRK2 than WT. GRK2 polyubiquitination via lysine-48 linkages was significantly reduced in Mdm2/p53–KO hearts. Tamoxifen-inducible cardiomyocyte-specific deletion of Mdm2 in adult mice also led to a significant increase in GRK2, and resulted in severely impaired cardiac function, high mortality, and no detectable βAR responsiveness. Gene delivery of either Mdm2 or GRK2-CT in vivo using adeno-associated virus 9 (AAV9) effectively rescued β1AR-induced cardiac contractility in Mdm2/p53–KO. These findings reveal a critical p53-independent physiological role of Mdm2 in adult hearts, namely, regulation of GRK2-mediated desensitization of βAR signaling.

Authors

Pierre-Yves Jean-Charles, Samuel Mon-Wei Yu, Dennis Abraham, Reddy Peera Kommaddi, Lan Mao, Ryan T. Strachan, Zhu-Shan Zhang, Dawn E. Bowles, Leigh Brian, Jonathan A. Stiber, Stephen N. Jones, Walter J. Koch, Howard A. Rockman, Sudha K. Shenoy

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JCI Insight is a peer-reviewed journal published by the American Society for Clinical Investigation dedicated to well-executed preclinical and clinical research studies. The journal was founded in 2016 and is headed by Editor in Chief Howard Rockman.

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