In this issue, Sun et al. investigate lung epithelial regeneration in response to injury and demonstrate a critical role for TAZ, a component of the Hippo pathway, in alveolar epithelial cell differentiation. The cover image shows a murine alveolar spheroid derived from TdTomato+ lineage type 2 alvelolar cells (AEC2, red) that has been immunostained for an AEC2 marker (SPC, white) and an AEC1 marker (HOPX, green). Nuclei are shown in blue.
Mitochondrial dysfunction characterizes many rare and common age-associated diseases. The biochemical consequences, underlying clinical manifestations, and potential therapeutic targets, remain to be better understood. We tested the hypothesis that lipid dyshomeostasis in mitochondrial disorders goes beyond mitochondrial fatty acid β-oxidation, particularly in liver. This was achieved using comprehensive untargeted and targeted lipidomics in a case-control cohort of patients with Leigh syndrome French-Canadian variant (LSFC), a mitochondrial disease caused by mutations in LRPPRC, and in mice harboring liver-specific inactivation of Lrpprc (H-Lrpprc–/–). We discovered a plasma lipid signature discriminating LSFC patients from controls encompassing lower levels of plasmalogens and conjugated bile acids, which suggest perturbations in peroxisomal lipid metabolism. This premise was reinforced in H-Lrpprc–/– mice, which compared with littermates recapitulated a similar, albeit stronger peroxisomal metabolic signature in plasma and liver including elevated levels of very-long-chain acylcarnitines. These mice also presented higher transcript levels for hepatic markers of peroxisome proliferation in addition to lipid remodeling reminiscent of nonalcoholic fatty liver diseases. Our study underscores the value of lipidomics to unveil unexpected mechanisms underlying lipid dyshomeostasis ensuing from mitochondrial dysfunction herein implying peroxisomes and liver, which likely contribute to the pathophysiology of LSFC, but also other rare and common mitochondrial diseases.
Matthieu Ruiz, Alexanne Cuillerier, Caroline Daneault, Sonia Deschênes, Isabelle Robillard Frayne, Bertrand Bouchard, Anik Forest, Julie Thompson Legault, The LSFC Consortium, Frederic M. Vaz, John D. Rioux, Yan Burelle, Christine Des Rosiers
In the United States, poison ivy is the most common naturally occurring allergen that causes allergic contact dermatitis (ACD). The immune and pruritic mechanisms associated with poison ivy ACD remain largely unexplored. Here, we compared skin whole transcriptomes and itch mediator levels in mouse ACD models induced by the poison ivy allergen, urushiol, and the synthetic allergen, oxazolone. The urushiol model produced a Th2-biased immune response and scratching behavior, resembling findings in poison ivy ACD patients. Urushiol-challenged skin contained elevated levels of the cytokine thymic stromal lymphopoietin (TSLP), a T cell regulator and itch mediator, and pruritogenic serotonin (5-HT) and endothelin (ET-1) but not substance P (SP) or histamine. The oxazolone model generated a mixed Th1/Th2 response associated with increased levels of SP, 5-HT, and ET-1 but not TSLP or histamine. Injections of a TSLP monoclonal neutralizing antibody or serotonergic or endothelin inhibitors, but not SP inhibitors or antihistamines, reduced scratching behaviors in urushiol-challenged mice. Our findings suggest that the mouse urushiol model may serve as a translational model of human poison ivy ACD. Inhibiting signaling by TSLP and other cytokines may represent alternatives to the standard steroid/antihistamine regimen for steroid-resistant or -intolerant patients and in exaggerated systemic responses to poison ivy.
Boyi Liu, Yan Tai, Boyu Liu, Ana I. Caceres, Chengyu Yin, Sven-Eric Jordt
Cellular senescence is a tumor-suppressive mechanism that can paradoxically contribute to aging pathologies. Despite evidence of immune clearance in mouse models, it is not known how senescent cells (SnCs) persist and accumulate with age or in tumors in individuals. Here, we identify cooperative mechanisms that orchestrate the immunoevasion and persistence of normal and cancer human SnCs through extracellular targeting of natural killer receptor signaling. Damaged SnCs avoided immune recognition through MMP-dependent shedding of NKG2D ligands reinforced via paracrine suppression of NKG2D receptor–mediated immunosurveillance. These coordinated immunoediting processes were evident in residual, drug-resistant tumors from cohorts of more than 700 prostate and breast cancer patients treated with senescence-inducing genotoxic chemotherapies. Unlike in mice, these reversible senescence subversion mechanisms were independent of p53/p16 and exacerbated in oncogenic RAS-induced senescence. Critically, the p16INK4A tumor suppressor could disengage the senescence growth arrest from the damage-associated immune senescence program, which was manifest in benign nevus lesions, where indolent SnCs accumulated over time and preserved a non-proinflammatory tissue microenvironment maintaining NKG2D-mediated immunosurveillance. Our study shows how subpopulations of SnCs elude immunosurveillance and reveals potential secretome-targeted therapeutic strategies to selectively eliminate — and restore the clearance of — the detrimental SnCs that actively persist after chemotherapy and accumulate at sites of aging pathologies.
Denise P. Muñoz, Steven M. Yannone, Anneleen Daemen, Yu Sun, Funda Vakar-Lopez, Misako Kawahara, Adam M. Freund, Francis Rodier, Jennifer D. Wu, Pierre-Yves Desprez, David H. Raulet, Peter S. Nelson, Laura J. van ’t Veer, Judith Campisi, Jean-Philippe Coppé
Airway neutrophilia occurs in approximately 50% of patients with asthma and is associated with particularly severe disease. Unfortunately, this form of asthma is usually refractory to corticosteroid treatment, and there is an unmet need for new therapies. Pulmonary neutrophilic inflammation is associated with Th17 cells, whose differentiation is controlled by the nuclear receptor retinoic acid–related orphan receptor γt (RORγt). Here, we tested whether VTP-938, a selective inverse agonist of this receptor, can reduce disease parameters in animal models of neutrophilic asthma. When administered before allergic sensitization through the airway, the RORγt inverse agonist blunted allergen-specific Th17 cell development in lung-draining lymph nodes and attenuated allergen-induced production of IL-17. VTP-938 also reduced pulmonary production of IL-17 and airway neutrophilia when given during the allergen challenge of the model. Finally, in an environmentally relevant model of allergic responses to house dust extracts, VTP-938 suppressed production of IL-17 and neutrophilic inflammation and also markedly diminished airway hyperresponsiveness. Together, these findings suggest that orally available inverse agonists of RORγt might provide an effective therapy to treat glucocorticoid-resistant neutrophilic asthma.
Gregory S. Whitehead, Hong Soon Kang, Seddon Y. Thomas, Alexander Medvedev, Tadeusz P. Karcz, Gentaro Izumi, Keiko Nakano, Sergei S. Makarov, Hideki Nakano, Anton M. Jetten, Donald N. Cook
Immunotherapy holds promise for patients with multiple myeloma (MM), but little is known about how MM-induced immunosuppression influences response to therapy. Here, we investigated the impact of disease progression on immunotherapy efficacy in the Vk*MYC mouse model. Treatment with agonistic anti-CD137 (4-1BB) mAbs efficiently protected mice when administered early but failed to contain MM growth when delayed more than 3 weeks after Vk*MYC tumor cell challenge. The quality of the CD8+ T cell response to CD137 stimulation was not altered by the presence of MM, but CD8+ T cell numbers were profoundly reduced at the time of treatment. Our data suggest that an insufficient ratio of CD8+ T cells to MM cells (CD8/MM ratio) accounts for the loss of anti-CD137 mAb efficacy. We established serum M-protein levels prior to therapy as a predictive factor of response. Moreover, we developed an in silico model to capture the dynamic interactions between CD8+ T cells and MM cells. Finally, we explored two methods to improve the CD8/MM ratio: anti-CD137 mAb immunotherapy combined with Treg depletion or administered after chemotherapy treatment with cyclophosphamide or melphalan efficiently reduced MM burden and prolonged survival. Together, our data indicate that consolidation treatment with anti-CD137 mAbs might prevent MM relapse.
Camille Guillerey, Kyohei Nakamura, Andrea C. Pichler, Deborah Barkauskas, Sophie Krumeich, Kimberley Stannard, Kim Miles, Heidi Harjunpää, Yuan Yu, Mika Casey, Alina I. Doban, Mircea Lazar, Gunter Hartel, David Smith, Slavica Vuckovic, Michele W.L. Teng, P. Leif Bergsagel, Marta Chesi, Geoffrey R. Hill, Ludovic Martinet, Mark J. Smyth
Hormones produced by the anterior pituitary gland regulate an array of important physiological functions, but the causes of pituitary hormone disorders are not fully understood. Herein we report that genetically engineered mice with deletion of the hedgehog signaling receptor PATCHED1 (Ptch1) by S100a4 promoter–driven Cre recombinase (S100a4-Cre;Ptch1fl/fl mutants) exhibit adult-onset hypogonadotropic hypogonadism and multiple pituitary hormone disorders. During the transition from puberty to adulthood, S100a4-Cre;Ptch1fl/fl mice of both sexes develop hypogonadism coupled with reduced gonadotropin levels. Their pituitary glands also display severe structural and functional abnormalities, as revealed by transmission electron microscopy and expression of key genes regulating pituitary endocrine functions. S100a4-Cre activity in the anterior pituitary gland is restricted to CD45+ cells of hematopoietic origin, including folliculo-stellate cells and other immune cell types, causing sex-specific changes in the expression of genes regulating the local microenvironment of the anterior pituitary. These findings provide in vivo evidence for the importance of pituitary hematopoietic cells in regulating fertility and endocrine function, in particular during sexual maturation and likely through sexually dimorphic mechanisms. These findings support a previously unrecognized role of hematopoietic cells in causing hypogonadotropic hypogonadism and provide inroads into the molecular and cellular basis for pituitary hormone disorders in humans.
Yi Athena Ren, Teresa Monkkonen, Michael T. Lewis, Daniel J. Bernard, Helen C. Christian, Carolina J. Jorgez, Joshua A. Moore, John D. Landua, Haelee M. Chin, Weiqin Chen, Swarnima Singh, Ik Sun Kim, Xiang H.F. Zhang, Yan Xia, Kevin J. Phillips, Harry MacKay, Robert A. Waterland, M. Cecilia Ljungberg, Pradip K. Saha, Sean M. Hartig, Tatiana Fiordelisio Coll, JoAnne S. Richards
Bile acids play a major role in the regulation of lipid and energy metabolism. Here we propose the hepatic bile acid uptake transporter Na+ taurocholate cotransporting polypeptide (NTCP) as a target to prolong postprandial bile acid elevations in plasma. Reducing hepatic clearance of bile acids from plasma by genetic deletion of NTCP moderately increased plasma bile acid levels, reduced diet-induced obesity, attenuated hepatic steatosis, and lowered plasma cholesterol levels. NTCP and G protein–coupled bile acid receptor–double KO (TGR5–double KO) mice were equally protected against diet-induced obesity as NTCP–single KO mice. NTCP-KO mice displayed decreased intestinal fat absorption and a trend toward higher fecal energy output. Furthermore, NTCP deficiency was associated with an increased uncoupled respiration in brown adipose tissue, leading to increased energy expenditure. We conclude that targeting NTCP-mediated bile acid uptake can be a novel approach to treat obesity and obesity-related hepatosteatosis by simultaneously dampening intestinal fat absorption and increasing energy expenditure.
Joanne M. Donkers, Sander Kooijman, Davor Slijepcevic, Roni F. Kunst, Reinout L.P. Roscam Abbing, Lizette Haazen, Dirk R. de Waart, Johannes H.M. Levels, Kristina Schoonjans, Patrick C.N. Rensen, Ronald P.J. Oude Elferink, Stan F.J. van de Graaf
Despite their well-recognized success in the clinic, antibodies generally do not penetrate cellular membranes to target intracellular molecules, many of which underlie incurable diseases. Here we show that covalently conjugating phosphorothioated DNA oligonucleotides to antibodies enabled their efficient cellular internalization. Antibody cell penetration was partially mediated by membrane potential alteration. Moreover, without an antigen to bind, intracellular levels of the modified antibodies underwent cellular clearance, which involved efflux and lysosomal degradation, enabling detection of intended intracellular molecules as tested in fibroblasts, tumor cells, and T cells. This target-dependent cellular retention of modified antibodies extended to in vivo studies. Both local and systemic administrations of low doses of modified antibodies effectively inhibited intracellular targets, such as transcription factors Myc, interferon regulatory factor 4, and tyrosine-protein kinase SRC, and expression of their downstream genes in tumors, resulting in tumor cell apoptosis and tumor growth inhibition. This simple modification enables the use of antibodies to detect and modulate intracellular molecules in both cultured living cells and in whole animals, forming the foundation for a new paradigm for antibody-based research, diagnostics, and therapeutics.
Andreas Herrmann, Toshikage Nagao, Chunyan Zhang, Christoph Lahtz, Yi-Jia Li, Chanyu Yue, Ronja Mülfarth, Hua Yu
Advances in genomic medicine have elucidated an increasing number of genetic etiologies for patients with common variable immunodeficiency (CVID). However, there is heterogeneity in clinical and immunophenotypic presentations and a limited understanding of the underlying pathophysiology of many cases. The primary defects in CVID may extend beyond the adaptive immune system, and the combined defect in both the myeloid and lymphoid compartments suggests the mechanism may involve bone marrow output and earlier progenitors. Using the methylation profile of the human androgen receptor (AR) gene as a surrogate epigenetic marker for bone marrow clonality, we examined the hematopoietic compartments of patients with CVID. Our data show that clonal hematopoiesis is common among patients with adult-onset CVID who do not have associated noninfectious complications. Nonblood tissues did not show a skewed AR methylation status, supporting a model of an acquired clonal hematopoietic event. Attenuation of memory B cell differentiation into long-lived plasma cells (CD20–CD27+CD38+CD138+) was associated with marked changes in the postdifferentiation methylation profile, demonstrating the functional consequence of clonal hematopoiesis on humoral immunity in these patients. This study sheds light on a potential etiology of a subset of patients with CVID, and the findings suggest that it is a stage of an acquired lymphocyte maturation disorder.
Gabriel K. Wong, Sara Barmettler, James M. Heather, David Millar, Sarah A. Penny, Aarnoud Huissoon, Alex Richter, Mark Cobbold
NK cell exhaustion (NCE) due to sustained proliferation results in impaired NK cell function with loss of cytokine production and lytic activity. Using murine models of chronic NK cell stimulation, we have identified a phenotypic signature of NCE, characterized by upregulation of the terminal differentiation marker KLRG1 and by downregulation of eomesodermin and the activating receptor NKG2D. Chronic stimulation of mice lacking NKG2D resulted in minimal NCE compared with control mice, thus identifying NKG2D as a crucial mediator of NCE. NKG2D internalization and downregulation on NK cells have been previously observed in the presence of tumor cells with high expression of NKG2D ligands (NKG2DL) due to the activation of the DNA damage repair pathways. Interestingly, our study revealed that during NK cell activation, there is an increase of MULT1, an NKG2DL, that correlates with an induction of DNA damage. Treatment with the ATM DNA damage repair pathway inhibitor KU55933 (KU) during activation reduced NCE by improving expression of activation markers and genes involved in cell survival, through sustaining NKG2D expression and preserving cell functionality. Importantly, NK cells expanded ex vivo in the presence of KU displayed increased antitumor efficacy in both NKG2D-dependent and -independent mouse models. Collectively, these data demonstrate that NCE is caused by DNA damage and is regulated, at least in part, by NKG2D. Further, the prevention of NCE is a promising strategy to improve NK cell–based immunotherapy.
Maite Alvarez, Federico Simonetta, Jeanette Baker, Antonio Pierini, Arielle S. Wenokur, Alyssa R. Morrison, William J. Murphy, Robert S. Negrin
Idiopathic CD4 lymphocytopenia (ICL) is a clinically heterogeneous immunodeficiency disorder defined by low numbers of circulating CD4+ T cells and increased susceptibility to opportunistic infections. CD8+ T cells, NK, and/or B cells may also be deficient in some patients. To delineate possible pathogenic cellular mechanisms in ICL, we compared immune system development and function in NOD-RAGKO-γcKO (NRG) mice transplanted with hematopoietic stem cells from patients with ICL or healthy controls. CD34+ hematopoietic stem cells from healthy controls and patients with ICL reconstituted NRG mice equally well. In contrast, PBMC transfers into NRG mice identified 2 ICL engraftment phenotypes, reconstituting and nonreconstituting (NR), based on the absence or presence of donor lymphopenia. For patients in the NR group, the distribution of lymphocyte subsets was similar in the peripheral blood of both the patient and the corresponding humanized mice. The NR-ICL group could be further divided into individuals whose CD3+ T cells had defects in proliferation or survival. Thus, ICL cellular pathogenesis might be classified by humanized mouse models into 3 distinct subtypes: (a) T cell extrinsic, (b) T cell intrinsic affecting proliferation, and (c) T cell intrinsic affecting survival. Humanized mouse models of ICL help to delineate etiology and ultimately to guide development of individualized therapeutic strategies.
Ainhoa Perez-Diez, Xiangdong Liu, Virginia Sheikh, Gregg Roby, David F. Stroncek, Irini Sereti
Circulating tumor cells (CTCs) provide easy, repeatable, and representative access to information regarding solid tumors. However, their detection remains difficult because of their paucity, their short half-life, and the lack of reliable surface biomarkers. Flow cytometry (FC) is a fast, sensitive, and affordable technique, ideal for rare-cell detection. Adapted to CTC detection (i.e., extremely rare cells), most FC-based techniques require a time-consuming pre-enrichment step, followed by a 2-hour staining procedure, impeding the efficiency of CTC detection. We overcame these caveats and reduced the procedure to less than 1 hour, with minimal manipulation. First, cells were simultaneously fixed, permeabilized, and then stained. Second, using low-speed FC acquisition conditions and 2 discriminators (cell size and pan-cytokeratin expression), we suppressed the pre-enrichment step. Applied to blood from donors with or without known malignant diseases, this protocol ensures a high recovery of the cells of interest independently of their epithelial-mesenchymal plasticity and can predict which samples are derived from cancer donors. This proof-of-concept study lays the bases of a sensitive tool to detect CTCs from a small amount of blood upstream of in-depth analyses.
Alexia Lopresti, Fabrice Malergue, François Bertucci, Maria Lucia Liberatoscioli, Severine Garnier, Quentin DaCosta, Pascal Finetti, Marine Gilabert, Jean Luc Raoul, Daniel Birnbaum, Claire Acquaviva, Emilie Mamessier
Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder with variable genetic etiologies. Here, we focused on understanding the precise molecular pathology of a single clinical variant in DSP, the gene encoding desmoplakin. We initially identified a potentially novel missense desmoplakin variant (p.R451G) in a patient diagnosed with biventricular ACM. An extensive single-family ACM cohort was assembled, revealing a pattern of coinheritance for R451G desmoplakin and the ACM phenotype. An in vitro model system using patient-derived induced pluripotent stem cell lines showed depressed levels of desmoplakin in the absence of abnormal electrical propagation. Molecular dynamics simulations of desmoplakin R451G revealed no overt structural changes, but a significant loss of intramolecular interactions surrounding a putative calpain target site was observed. Protein degradation assays of recombinant desmoplakin R451G confirmed increased calpain vulnerability. In silico screening identified a subset of 3 additional ACM-linked desmoplakin missense mutations with apparent enhanced calpain susceptibility, predictions that were confirmed experimentally. Similar to R451G, these mutations are found in families with biventricular ACM. We conclude that augmented calpain-mediated degradation of desmoplakin represents a shared pathological mechanism for select ACM-linked missense variants. This approach for identifying variants with shared molecular pathologies may represent a powerful new strategy for understanding and treating inherited cardiomyopathies.
Ronald Ng, Heather Manring, Nikolaos Papoutsidakis, Taylor Albertelli, Nicole Tsai, Claudia J. See, Xia Li, Jinkyu Park, Tyler L. Stevens, Prameela J. Bobbili, Muhammad Riaz, Yongming Ren, Christopher E. Stoddard, Paul M.L. Janssen, T. Jared Bunch, Stephen P. Hall, Ying-Chun Lo, Daniel L. Jacoby, Yibing Qyang, Nathan Wright, Maegen A. Ackermann, Stuart G. Campbell
The lung is a relatively quiescent organ during homeostasis but has a remarkable capacity for repair after injury. Alveolar epithelial type I cells (AEC1s) line airspaces and mediate gas exchange. After injury, they are regenerated by differentiation from their progenitors — alveolar epithelial type II cells (AEC2s) — which also secrete surfactant to maintain surface tension and alveolar patency. While recent studies showed that the maintenance of AEC2 stemness is Wnt dependent, the molecular mechanisms underlying AEC2-AEC1 differentiation in adult lung repair are still incompletely understood. Here, we show that WWTR1 (TAZ) plays a crucial role in AEC differentiation. Using an in vitro organoid culture system, we found that tankyrase inhibition can efficiently block AEC2-AEC1 differentiation, and this effect was due to the inhibition of TAZ. In a bleomycin-induced lung injury model, conditional deletion of TAZ in AEC2s dramatically reduced AEC1 regeneration during recovery, leading to exacerbated alveolar lesions and fibrosis. In patients with idiopathic pulmonary fibrosis (IPF), decreased blood levels of the receptor for advanced glycation end products (RAGE), a biomarker of AEC1 health, were associated with more rapid disease progression. Our findings implicate TAZ as a critical factor involved in AEC2-to-AEC1 differentiation, and hence the maintenance of alveolar integrity after injury.
Tianhe Sun, Zhiyu Huang, Hua Zhang, Clara Posner, Guiquan Jia, Thirumalai R. Ramalingam, Min Xu, Hans Brightbill, Jackson G. Egen, Anwesha Dey, Joseph R. Arron
Adeno-associated virus (AAV) vector liver-directed gene therapy (GT) for hemophilia B (HB) is limited by a vector dose–dependent hepatotoxicity. Recently, this obstacle has been partially circumvented by the use of a hyperactive factor IX (FIX) variant, R338L (Padua), which has an 8-fold increased specific activity compared with FIX-WT. FIX-R338L has emerged as the standard for HB GT. However, the underlying mechanism of its hyperactivity is undefined; as such, safety concerns of unregulated coagulation and the potential for thrombotic complications have not been fully addressed. To this end, we evaluated the enzymatic and clotting activity as well as the activation, inactivation, and cofactor dependence of FIX-R338L relative to FIX-WT. We observed that the high specific activity of FIX-R338L requires factor VIIIa (FVIIIa) cofactor. In a potentially novel system using emicizumab, an FVIII-mimicking bispecific antibody, the hyperactivity of both recombinant FIX-R338L and AAV-mediated transgene-expressed FIX-R338L from HB GT subjects was ablated without FVIIIa activity. We conclude that the molecular regulation of activation, inactivation, and cofactor dependence of FIX-R338L is similar to FIX-WT but that the FVIIIa-dependent hyperactivity of FIX-R338L is the result of a faster rate of factor X activation. This mechanism helps mitigate safety concerns of unregulated coagulation and supports the expanded use of FIX-R338L in HB therapy.
Benjamin J. Samelson-Jones, Jonathan D. Finn, Lindsey A. George, Rodney M. Camire, Valder R. Arruda
Whereas prior studies have demonstrated an important immunomodulatory role for the neuronal cholinergic system in the heart, the role of the nonneuronal cholinergic system is not well understood. To address the immunomodulatory role of the nonneuronal cholinergic system in the heart, we used a previously validated diphtheria toxin–induced (DT-induced) cardiomyocyte ablation model (Rosa26-DTMlc2v-Cre mice). DT-injected Rosa26-DTMlc2v-Cre mice were treated with diluent or pyridostigmine bromide (PYR), a reversible cholinesterase inhibitor. PYR treatment resulted in increased survival and decreased numbers of MHC-IIloCCR2+ macrophages in DT-injected Rosa26-DTMlc2v-Cre mice compared with diluent-treated Rosa26-DTMlc2v-Cre mice. Importantly, the expression of CCL2/7 mRNA and protein was reduced in the hearts of PYR-treated mice. Backcrossing Rosa26-DTMlc2v-Cre mice with a transgenic mouse line (Chat-ChR2) that constitutively overexpresses the vesicular acetylcholine transporter (VAChT) resulted in decreased expression of Ccl2/7 mRNA and decreased numbers of CD68+ cells in DT-injured Rosa26-DTMlc2v-Cre/Chat-ChR2 mouse hearts, consistent with the pharmacologic studies with PYR. In vitro studies with cultures of LPS-stimulated peritoneal macrophages revealed a concentration-dependent reduction in CCL2 secretion following stimulation with acetylcholine, nicotine, and muscarine. To our knowledge, these findings reveal a previously unappreciated immunomodulatory role for the nonneuronal cholinergic system in regulating homeostatic responses in the heart following tissue injury.
Cibele Rocha-Resende, Carla Weinheimer, Geetika Bajpai, Luigi Adamo, Scot J. Matkovich, Joel Schilling, Philip M. Barger, Kory J. Lavine, Douglas L. Mann
We determined which metabolic pathways are activated by hypoxia-inducible factor 1–mediated (HIF-1–mediated) protection against oxygen-induced retinopathy (OIR) in newborn mice, the experimental correlate to retinopathy of prematurity, a leading cause of infant blindness. HIF-1 coordinates the change from oxidative to glycolytic metabolism and mediates flux through serine and 1-carbon metabolism (1CM) in hypoxic and cancer cells. We used untargeted metabolite profiling in vivo to demonstrate that hypoxia mimesis activates serine/1CM. Both [13C6] glucose labeling of metabolites in ex vivo retinal explants as well as in vivo [13C3] serine labeling of metabolites followed in liver lysates strongly suggest that retinal serine is primarily derived from hepatic glycolytic carbon and not from retinal glycolytic carbon in newborn pups. In HIF-1α2lox/2lox albumin-Cre–knockout mice, reduced or near-0 levels of serine/glycine further demonstrate the hepatic origin of retinal serine. Furthermore, inhibition of 1CM by methotrexate blocked HIF-mediated protection against OIR. This demonstrated that 1CM participates in protection induced by HIF-1 stabilization. The urea cycle also dominated pathway enrichment analyses of plasma samples. The dependence of retinal serine on hepatic HIF-1 and the upregulation of the urea cycle emphasize the importance of the liver to remote protection of the retina.
Charandeep Singh, George Hoppe, Vincent Tran, Leah McCollum, Youstina Bolok, Weilin Song, Amit Sharma, Henri Brunengraber, Jonathan E. Sears
Nipah virus (NiV) is an emerging zoonotic paramyxovirus that causes highly lethal henipavirus encephalitis in humans. Survivors develop various neurologic sequelae, including late-onset and relapsing encephalitis, several months up to several years following initial infection. However, the underlying pathology and disease mechanisms of persistent neurologic complications remain unknown. Here, we demonstrate persistent NiV infection in the brains of grivets that survived experimental exposure to NiV. Encephalitis affected the entire brains, with the majority of NiV detected in the neurons and microglia of the brainstems, cerebral cortices, and cerebella. We identified the vascular endothelium in the brain as an initial target of NiV infection during the acute phase of disease, indicating a primary path of entry for NiV into the brain. Notably, we were unable to detect NiV anywhere else except the brains in the examined survivors. Our findings indicate that late-onset and relapsing encephalitis of NiV in human survivors may be due to viral persistence in the brain and shed light on the pathogenesis of chronic henipavirus encephalitis.
Jun Liu, Kayla M. Coffin, Sara C. Johnston, April M. Babka, Todd M. Bell, Simon Y. Long, Anna N. Honko, Jens H. Kuhn, Xiankun Zeng
BACKGROUND There is growing evidence to suggest that the brain is an important target for insulin action and that states of insulin resistance may extend to the CNS, with detrimental effects on cognitive functioning. Although the effect of systemic insulin resistance on peripheral organs is well studied, the degree to which insulin affects brain function in vivo remains unclear.METHODS This randomized, single-blinded, 2-way–crossover, sham-controlled, pilot study determined the effects of hyperinsulinemia on functional MRI (fMRI) brain activation during a 2-back working memory task in 9 healthy older adults (aged 57–79 years). Each participant underwent 2 clamp procedures (an insulin infusion and a saline placebo infusion, with normoglycemia maintained during both conditions) to examine the effects of hyperinsulinemia on task performance and associated blood oxygen level–dependent (BOLD) signal using fMRI.RESULTS Hyperinsulinemia (compared with saline control) was associated with an increase in both the spatial extent and relative strength of task-related BOLD signal during the 2-back task. Further, the degree of increased task-related activation in select brain regions correlated with greater systemic insulin sensitivity as well as decreased reaction times and performance accuracy between experimental conditions.CONCLUSION Together, these findings provide evidence of insulin action in the CNS among older adults during periods of sustained cognitive demand, with the greatest effects noted for individuals with highest systemic insulin sensitivity.FUNDING This work was funded by the NIH (5R21AG051958, 2016).
Victoria J. Williams, Bianca A. Trombetta, Rabab Z. Jafri, Aaron M. Koenig, Chase D. Wennick, Becky C. Carlyle, Laya Ekhlaspour, Rexford S. Ahima, Steven J. Russell, David H. Salat, Steven E. Arnold
Genetic susceptibility to chronic pancreatitis in humans is frequently associated with mutations that increase activation of the digestive protease trypsin. Intrapancreatic trypsin activation is an early event in experimental acute pancreatitis in rodents, suggesting that trypsin is a key driver of pathology. In contrast with trypsin, the pancreatic protease chymotrypsin serves a protective function by mitigating trypsin activation through degradation. In humans, loss-of-function mutations in chymotrypsin C (CTRC) are common risk factors for chronic pancreatitis; however, the pathogenic effect of CTRC deficiency has not been corroborated in animal models yet. Here we report that C57BL/6 mice that are widely used for genetic manipulations do not express functional CTRC because of a single-nucleotide deletion in exon 2 of the Ctrc gene. We restored a functional Ctrc locus in C57BL/6N mice and demonstrated that in the Ctrc+ strain, the severity of cerulein-induced experimental acute and chronic pancreatitis was significantly ameliorated. Improved disease parameters were associated with reduced intrapancreatic trypsin activation, suggesting a causal link between CTRC-mediated trypsinogen degradation and protection against pancreatitis. Taken together with prior human genetic and biochemical studies, the observations provide conclusive evidence for the protective role of CTRC against pancreatitis.
Andrea Geisz, Zsanett Jancsó, Balázs Csaba Németh, Eszter Hegyi, Miklós Sahin-Tóth
Mutations in the BSCL2 gene underlie human type 2 Berardinelli-Seip congenital lipodystrophy (BSCL2) disease. Global Bscl2–/– mice recapitulate human BSCL2 lipodystrophy and results in the development of insulin resistance and hypertrophic cardiomyopathy. The pathological mechanisms underlying the development of lipodystrophy and cardiomyopathy in BSCL2 are controversial. Here we report that Bscl2–/– mice develop cardiac hypertrophy because of increased basal IGF1 receptor–mediated (IGF1R-mediated) PI3K/AKT signaling. Bscl2–/– hearts exhibited increased adipose triglyceride lipase (ATGL) protein stability and expression causing drastic reduction of glycerolipids. Excessive fatty acid oxidation was overt in Bscl2–/– hearts, partially attributing to the hyperacetylation of cardiac mitochondrial proteins. Intriguingly, pharmacological inhibition or genetic inactivation of ATGL could rescue adipocyte differentiation and lipodystrophy in Bscl2–/– cells and mice. Restoring a small portion of fat mass by ATGL partial deletion in Bscl2–/– mice not only reversed the systemic insulin resistance, but also ameliorated cardiac protein hyperacetylation, normalized cardiac substrate metabolism, and improved contractile function. Collectively, our study uncovers pathways underlying lipodystrophy-induced cardiac hypertrophy and metabolic remodeling and pinpoints ATGL as a downstream target of BSCL2 in regulating the development of lipodystrophy and its associated cardiomyopathy.
Hongyi Zhou, Xinnuo Lei, Yun Yan, Todd Lydic, Jie Li, Neal L. Weintraub, Huabo Su, Weiqin Chen
Patients with mutations in Cullin-3 (CUL3) exhibit severe early-onset hypertension, but the contribution of the smooth muscle remains unclear. Conditional genetic ablation of CUL3 in vascular smooth muscle (S-CUL3KO) causes progressive impairment in response to NO, rapid development of severe hypertension, and increased arterial stiffness. Loss of CUL3 in primary aortic smooth muscle cells or aorta resulted in decreased expression of the NO receptor soluble guanylate cyclase (sGC), a marked reduction in cGMP production, and impaired vasodilation to cGMP analogs. Vasodilation responses to a selective large-conductance Ca2+-activated K+ channel activator were normal, suggesting that downstream signals that promote smooth muscle–dependent relaxation remained intact. We conclude that smooth muscle–specific CUL3 ablation impairs both cGMP production and cGMP responses and that loss of CUL3 function selectively in smooth muscle is sufficient to cause severe hypertension by interfering with the NO/sGC/cGMP pathway. Our study provides evidence that vascular smooth muscle CUL3 is a major regulator of BP. CUL3 mutations cause severe vascular dysfunction, arterial stiffness, and hypertension due to defects in vascular smooth muscle.
Larry N. Agbor, Anand R. Nair, Jing Wu, Ko-Ting Lu, Deborah R. Davis, Henry L. Keen, Frederick W. Quelle, James A. McCormick, Jeffrey D. Singer, Curt D. Sigmund
Progression of fibrosis and the development of cirrhosis are responsible for the liver-related morbidity and mortality associated with chronic liver diseases. There is currently a great unmet need for effective antifibrotic strategies. Stem cells play a central role in wound-healing responses to restore liver homeostasis following injury. Here we tested the hypothesis that extracellular vesicles (EVs) isolated from induced pluripotent stem cells (iPSCs) modulate hepatic stellate cell (HSC) activation and may have antifibrotic effects. Human iPSCs were generated by reprogramming primary skin fibroblasts. EVs were isolated by differential centrifugation, quantified by flow cytometry (FACS), and characterized by dynamic light scattering and transmission electron microscopy (TEM). Primary human HSCs were activated with TGF-β (10 ng/mL) and exposed to iPSC-EVs. Efficacy of iPSC-EVs was tested on HSCs in vitro and in 2 murine models of liver injury (CCl4 and bile duct ligation). Characterization of iPSC-derived EVs by flow cytometry identified a large population of EVs released by iPSCs, primarily with a diameter of 300 nm, that could be visualized by TEM as round, cup-shaped objects. Fluorescent tracing assays detected iPSC-EVs in HSC cytosol after a short incubation, and EV uptake by HSCs resulted in both decrease of profibrogenic markers α–smooth muscle actin, CollagenIα1, fibronectin, and tissue inhibitor of metalloproteinases–1 and HSC profibrogenic responses, such as chemotaxis and proliferation. Genomics analyses of iPSC-EV miRNA cargo revealed 22 highly expressed miRNAs, among which miR-92a-3p was the most abundant. Transcriptome analysis identified 60 genes downmodulated and 235 upregulated in TGF-β–primed HSCs in the presence or absence of iPSC-EVs. Intravenous injection of iPSC-EVs in CCl4-induced and bile duct ligation–induced liver fibrosis resulted in antifibrotic effects at protein and gene levels. Results of this study identify iPSC-EVs as a potentially novel antifibrotic approach that may reduce or reverse liver fibrosis in patients with chronic liver disease.
Davide Povero, Eva M. Pinatel, Aleksandra Leszczynska, Nidhi P. Goyal, Takahiro Nishio, Jihoon Kim, David Kneiber, Lucas de Araujo Horcel, Akiko Eguchi, Paulina M. Ordonez, Tatiana Kisseleva, Ariel E. Feldstein
Postinfluenza bacterial superinfections cause increased morbidity and mortality compared with singular infection with influenza during both pandemics and seasonal epidemics. Vaccines and current treatments provide limited benefit, a rationale to conduct studies utilizing alternative therapies. FY1 and an optimized version, MEDI8852, anti-influenza HA mAbs, have been shown to neutralize influenza virus during singular influenza infection. MEDI4893*, an anti–Staphylococcus aureus α-toxin mAb, has been shown to improve survival when administered prophylactically prior to S. aureus pneumonia. Our objective was to determine if mAbs can improve survival during postinfluenza bacterial pneumonia. We administered FY1 in a murine model of postinfluenza methicillin-resistant S. aureus (MRSA) pneumonia and observed improved survival rates when given early during the course of influenza infection. Our findings indicate decreased lung injury and increased uptake and binding of bacteria by macrophages in the mice that received FY1 earlier in the course of influenza infection, corresponding to decreased bacterial burden. We also observed improved survival when mice were treated with a combination of FY1 and MEDI4893* late during the course of postinfluenza MRSA pneumonia. In conclusion, both FY1 and MEDI4893* prolong survival when used in a murine model of postinfluenza MRSA pneumonia, suggesting pathogen-specific mAbs as a possible therapeutic in the context of bacterial superinfection.
Keven M. Robinson, Krishnaveni Ramanan, Joshua M. Tobin, Kara L. Nickolich, Matthew J. Pilewski, Nicole L. Kallewaard, Bret R. Sellman, Taylor S. Cohen, John F. Alcorn
Neoepitopes are the only truly tumor-specific antigens. Although potential neoepitopes can be readily identified using genomics, the neoepitopes that mediate tumor rejection constitute a small minority, and there is little consensus on how to identify them. Here, for the first time to our knowledge, we use a combination of genomics, unbiased discovery mass spectrometry (MS) immunopeptidomics, and targeted MS to directly identify neoepitopes that elicit actual tumor rejection in mice. We report that MS-identified neoepitopes are an astonishingly rich source of tumor rejection-mediating neoepitopes (TRMNs). MS has also demonstrated unambiguously the presentation by MHC I, of confirmed tumor rejection neoepitopes that bind weakly to MHC I; this was done using DCs exogenously loaded with long peptides containing the weakly binding neoepitopes. Such weakly MHC I–binding neoepitopes are routinely excluded from analysis, and our demonstration of their presentation, and their activity in tumor rejection, reveals a broader universe of tumor-rejection neoepitopes than presently imagined. Modeling studies show that a mutation in the active neoepitope alters its conformation such that its T cell receptor–facing surface is substantially altered, increasing its exposed hydrophobicity. No such changes are observed in the inactive neoepitope. These results broaden our understanding of antigen presentation and help prioritize neoepitopes for personalized cancer immunotherapy.
Hakimeh Ebrahimi-Nik, Justine Michaux, William L. Corwin, Grant L.J. Keller, Tatiana Shcheglova, HuiSong Pak, George Coukos, Brian M. Baker, Ion I. Mandoiu, Michal Bassani-Sternberg, Pramod K. Srivastava