Latest issue: June 20, 2019
In the issue
Abstract
BACKGROUND Dietary changes have led to the growing prevalence of type 2 diabetes and nonalcoholic fatty liver disease. A hallmark of both disorders is hepatic lipid accumulation, derived in part from increased de novo lipogenesis. Despite the popularity of high-protein diets for weight loss, the effect of dietary protein on de novo lipogenesis is poorly studied. We aimed to characterize the effect of dietary protein on de novo lipid synthesis.METHODS We use a 3-way crossover interventional study in healthy males to determine the effect of high-protein feeding on de novo lipogenesis, combined with in vitro models to determine the lipogenic effects of specific amino acids. The primary outcome was a change in de novo lipogenesis–associated triglycerides in response to protein feeding.RESULTS We demonstrate that high-protein feeding, rich in glutamate, increases de novo lipogenesis–associated triglycerides in plasma (1.5-fold compared with control; P < 0.0001) and liver-derived very low-density lipoprotein particles (1.8-fold; P < 0.0001) in samples from human subjects (n = 9 per group). In hepatocytes, we show that glutamate-derived carbon is incorporated into triglycerides via palmitate. In addition, supplementation with glutamate, glutamine, and leucine, but not lysine, increased triglyceride synthesis and decreased glucose uptake. Glutamate, glutamine, and leucine increased activation of protein kinase B, suggesting that induction of de novo lipogenesis occurs via the insulin signaling cascade.CONCLUSION These findings provide mechanistic insight into how select amino acids induce de novo lipogenesis and insulin resistance, suggesting that high-protein feeding to tackle diabetes and obesity requires greater consideration.FUNDING The research was supported by UK Medical Research Council grants MR/P011705/1, MC_UP_A090_1006 and MR/P01836X/1. JLG is supported by the Imperial Biomedical Research Centre, National Institute for Health Research (NIHR).
Authors
Evelina Charidemou, Tom Ashmore, Xuefei Li, Ben D. McNally, James A. West, Sonia Liggi, Matthew Harvey, Elise Orford, Julian L. Griffin
Abstract
Susceptibility to chronic beryllium (Be) disease (CBD) is linked to HLA-DP molecules possessing a glutamic acid at the 69th position of the β-chain (βGlu69), with the most prevalent βGlu69-containing molecule being HLA-DP2. We have previously shown that HLA-DP2–transgenic (HLA-DP2–Tg) mice exposed to Be oxide (BeO) develop mononuclear infiltrates in a peribronchovascular distribution and a beryllium-specific, HLA-DP2–restricted CD4+ T cell response. In addition to T cells, B cells constituted a major portion of infiltrated leukocytes in the lung of BeO-exposed HLA-DP2–Tg mice and sequester BeO particles within ectopic lymphoid aggregates and granulomas. B cell depletion was associated with a loss of lymphoid aggregates and granulomas as well as a significant increase in lung injury in BeO-exposed mice. The protective role of B cells was innate in origin, and BeO-induced B cell recruitment to the lung was dependent on MyD88 signaling. Similar to BeO-exposed HLA-DP2–Tg mice, B cells also accumulate in the lungs of CBD subjects, located at the periphery and surrounding the granuloma. Overall, our data suggest what we believe is a novel modulatory role for B cells in the protection of the lung against sterile particulate exposure, with B cell recruitment to the inflamed lung occurring in an antigen-independent and MyD88-dependent manner.
Authors
Shaikh M. Atif, Douglas G. Mack, Amy S. McKee, Javier Rangel-Moreno, Allison K. Martin, Andrew Getahun, Lisa A. Maier, John C. Cambier, Rubin Tuder, Andrew P. Fontenot
Abstract
Monosomy 7 and deletion of 7q, known as del(7q), are common clonal cytogenetic abnormalities associated with high-grade myelodysplastic syndrome (MDS) arising in inherited and acquired bone marrow failure. Current nontransplant approaches to treat marrow failure may be complicated by stimulation of clonal outgrowth. To study the biological consequences of del(7q) within the context of a failing marrow, we generated induced pluripotent stem cells (iPSCs) derived from patients with Shwachman-Diamond syndrome (SDS), a bone marrow failure disorder with MDS predisposition, and genomically engineered a 7q deletion. The TGF-β pathway was the top differentially regulated pathway in transcriptomic analysis of SDS versus SDSdel(7q) iPSCs. SMAD2 phosphorylation was increased in SDS relative to wild-type cells, consistent with hyperactivation of the TGF-β pathway in SDS. Phospho-SMAD2 levels were reduced following 7q deletion in SDS cells and increased upon restoration of 7q diploidy. Inhibition of the TGF-β pathway rescued hematopoiesis in SDS iPSCs and in bone marrow hematopoietic cells from SDS patients while it had no impact on the SDSdel(7q) cells. These results identified a potential targetable vulnerability to improve hematopoiesis in an MDS predisposition syndrome and highlighted the importance of the germline context of somatic alterations to inform precision medicine approaches to therapy.
Authors
Melisa Ruiz-Gutierrez, Özge Vargel Bölükbaşı, Gabriela Alexe, Adriana G. Kotini, Kaitlyn Ballotti, Cailin E. Joyce, David W. Russell, Kimberly Stegmaier, Kasiani Myers, Carl D. Novina, Eirini P. Papapetrou, Akiko Shimamura
Abstract
Pulmonary fibrosis is a devastating disease characterized by accumulation of activated fibroblasts and scarring in the lung. While fibroblast activation in physiological wound repair reverses spontaneously, fibroblast activation in fibrosis is aberrantly sustained. Here we identified histone 3 lysine 9 methylation (H3K9me) as a critical epigenetic modification that sustains fibroblast activation by repressing the transcription of genes essential to returning lung fibroblasts to an inactive state. We show that the histone methyltransferase G9a (EHMT2) and chromobox homolog 5 (CBX5, also known as HP1α), which deposit H3K9me marks and assemble an associated repressor complex, respectively, are essential to initiation and maintenance of fibroblast activation specifically through epigenetic repression of peroxisome proliferator–activated receptor γ coactivator 1 α gene (PPARGC1A, encoding PGC1α). Both TGF-β and increased matrix stiffness potently inhibit PGC1α expression in lung fibroblasts through engagement of the CBX5/G9a pathway. Inhibition of the CBX5/G9a pathway in fibroblasts elevates PGC1α, attenuates TGF-β– and matrix stiffness–promoted H3K9 methylation, and reduces collagen accumulation in the lungs following bleomycin injury. Our results demonstrate that epigenetic silencing mediated by H3K9 methylation is essential for both biochemical and biomechanical fibroblast activation and that targeting this epigenetic pathway may provide therapeutic benefit by returning lung fibroblasts to quiescence.
Authors
Giovanni Ligresti, Nunzia Caporarello, Jeffrey A. Meridew, Dakota L. Jones, Qi Tan, Kyoung Moo Choi, Andrew J. Haak, Aja Aravamudhan, Anja C. Roden, Y.S. Prakash, Gwen Lomberk, Raul A. Urrutia, Daniel J. Tschumperlin
Abstract
Benign prostatic hyperplasia (BPH) is the most common cause of lower urinary tract symptoms in men. Current treatments target prostate physiology rather than BPH pathophysiology and are only partially effective. Here, we applied next-generation sequencing to gain insight into BPH. By RNA-Seq, we uncovered transcriptional heterogeneity among BPH cases, where a 65-gene BPH stromal signature correlated with symptom severity. Stromal signaling molecules bone morphogenetic protein 5 (BMP5) and CXC chemokine ligand 13 (CXCL13) were enriched in BPH while estrogen-regulated pathways were depleted. Notably, BMP5’s addition to cultured prostatic myofibroblasts altered their expression profile toward a BPH profile that included the BPH stromal signature. RNA-Seq also suggested an altered cellular milieu in BPH, which we verified by immunohistochemistry and single-cell RNA-Seq. In particular, BPH tissues exhibited enrichment of myofibroblast subsets but also depletion of neuroendocrine cells and an estrogen receptor–positive fibroblast cell type residing near the epithelium. By whole-exome sequencing, we uncovered somatic single-nucleotide variants in BPH, of uncertain pathogenic significance but indicative of clonal cell expansions. Thus, genomic characterization of BPH has identified a clinically relevant stromal signature and new candidate disease pathways (including a likely role for BMP5 signaling) and reveals BPH to be not merely a hyperplasia, but rather a fundamental relandscaping of cell types.
Authors
Lance W. Middleton, Zhewei Shen, Sushama Varma, Anna S. Pollack, Xue Gong, Shirley Zhu, Chunfang Zhu, Joseph W. Foley, Sujay Vennam, Robert T. Sweeney, Karen Tu, Jewison Biscocho, Okyaz Eminaga, Rosalie Nolley, Robert Tibshirani, James D. Brooks, Robert B. West, Jonathan R. Pollack
Abstract
Despite current immunosuppressive strategies, long-term lung transplant outcomes remain poor due to rapid allogenic responses. Using a stringent mouse model of allo-airway transplantation, we identified the CCR4-ligand axis as a central node driving secondary lymphoid tissue homing and activation of the allogeneic T cells that prevent long-term allograft survival. CCR4 deficiency on transplant recipient T cells diminished allograft injury and when combined with CTLA4-Ig led to lung allograft accommodation lasting longer than in any previous study to our knowledge. Thus, we identify CCR4-ligand interactions as a central mechanism driving allogeneic transplant rejection and suggest it as a potential target to enhance long-term lung transplant survival.
Authors
Vyacheslav Palchevskiy, Ying Ying Xue, Rita Kern, Stephen S. Weigt, Aric L. Gregson, Sophie X. Song, Michael C. Fishbein, Cory M. Hogaboam, David M. Sayah, Joseph P. Lynch III, Michael P. Keane, David G. Brooks, John A. Belperio
Abstract
BACKGROUND The lymphocyte-depleting antibody alemtuzumab is a highly effective treatment for relapsing-remitting multiple sclerosis (RRMS); however, 50% of patients develop novel autoimmunity after treatment. Most at risk are individuals who reconstitute their T cell pool by proliferating residual cells, rather than producing new T cells in the thymus, raising the possibility that autoimmunity might be prevented by increasing thymopoiesis. Keratinocyte growth factor (palifermin) promotes thymopoiesis in nonhuman primates.METHODS Following a dose tolerability substudy, individuals with RRMS (duration ≤10 years; expanded disability status scale ≤5.0, with ≥2 relapses in the previous 2 years) were randomized to placebo or 180 μg/kg/d palifermin, given for 3 days immediately before and after each cycle of alemtuzumab, with repeat doses at month 1 (M1) and M3. The interim primary endpoint was naive CD4+ T cell count at M6. Exploratory endpoints included number of recent thymic emigrants (RTEs) and signal joint T cell receptor excision circles/ml (sjTRECs/ml) of blood. The trial’s primary endpoint was incidence of autoimmunity at M30.RESULTS At M6, individuals receiving palifermin had fewer naive CD4+ T cells (2.229 × 107/l vs. 7.733 × 107/l; P = 0.007), RTEs (16% vs. 34%), and sjTRECs/ml (1100 vs. 3396), leading to protocol-defined termination of recruitment. No difference was observed in the rate of autoimmunity between the 2 groups.CONCLUSION In contrast with animal studies, palifermin reduced thymopoiesis in our patients. These results offer a note of caution to those using palifermin to promote thymopoiesis in other settings, particularly in the oncology/hematology setting, where alemtuzumab is often used as part of the conditioning regime.TRIAL REGISTRATION ClinicalTrials.gov NCT01712945.FUNDING MRC and Moulton Charitable Trust.
Authors
Alasdair J. Coles, Laura Azzopardi, Onajite Kousin-Ezewu, Harpreet Kaur Mullay, Sara A.J. Thompson, Lorna Jarvis, Jessica Davies, Sarah Howlett, Daniel Rainbow, Judith Babar, Timothy J. Sadler, J. William L. Brown, Edward Needham, Karen May, Zoya G. Georgieva, Adam E. Handel, Stefano Maio, Mary Deadman, Ioanna Rota, Georg Holländer, Sarah Dawson, David Jayne, Ruth Seggewiss-Bernhardt, Daniel C. Douek, John D. Isaacs, Joanne L. Jones
Abstract
Impaired insulin secretion in type 2 diabetes (T2D) is linked to reduced insulin granule docking, disorganization of the exocytotic site, and impaired glucose-dependent facilitation of insulin exocytosis. We show in β cells from 80 human donors that the glucose-dependent amplification of exocytosis is disrupted in T2D. Spatial analyses of granule fusion events, visualized by total internal reflection fluorescence microscopy in 24 of these donors, demonstrated that these events are nonrandom across the surface of β cells from donors with no diabetes. The compartmentalization of events occurs within regions defined by concurrent or recent membrane-resident secretory granules. This organization, and the number of membrane-associated granules, is glucose dependent and notably impaired in T2D β cells. Mechanistically, multichannel Kv2.1 clusters contribute to maintaining the density of membrane-resident granules and the number of fusion “hotspots,” while SUMOylation sites at the channel N- (K145) and C-terminus (K470) determine the relative proportion of fusion events occurring within these regions. Thus, a glucose-dependent compartmentalization of fusion, regulated in part by a structural role for Kv2.1, is disrupted in β cells from donors with T2D.
Authors
Jianyang Fu, John Maringa Githaka, Xiaoqing Dai, Gregory Plummer, Kunimasa Suzuki, Aliya F. Spigelman, Austin Bautista, Ryekjang Kim, Dafna Greitzer-Antes, Jocelyn E. Manning Fox, Herbert Y. Gaisano, Patrick E. MacDonald
Abstract
TRIOBP remodels the cytoskeleton by forming unusually dense F-actin bundles and is implicated in human cancer, schizophrenia, and deafness. Mutations ablating human and mouse TRIOBP-4 and TRIOBP-5 isoforms are associated with profound deafness, as inner ear mechanosensory hair cells degenerate after stereocilia rootlets fail to develop. However, the mechanisms regulating formation of stereocilia rootlets by each TRIOBP isoform remain unknown. Using 3 new Triobp mouse models, we report that TRIOBP-5 is essential for thickening bundles of F-actin in rootlets, establishing their mature dimensions and for stiffening supporting cells of the auditory sensory epithelium. The coiled-coil domains of this isoform are required for reinforcement and maintenance of stereocilia rootlets. A loss of TRIOBP-5 in mouse results in dysmorphic rootlets that are abnormally thin in the cuticular plate but have increased widths and lengths within stereocilia cores, and causes progressive deafness recapitulating the human phenotype. Our study extends the current understanding of TRIOBP isoform–specific functions necessary for life-long hearing, with implications for insight into other TRIOBPopathies.
Authors
Tatsuya Katsuno, Inna A. Belyantseva, Alexander X. Cartagena-Rivera, Keisuke Ohta, Shawn M. Crump, Ronald S. Petralia, Kazuya Ono, Risa Tona, Ayesha Imtiaz, Atteeq Rehman, Hiroshi Kiyonari, Mari Kaneko, Ya-Xian Wang, Takaya Abe, Makoto Ikeya, Cristina Fenollar-Ferrer, Gavin P. Riordan, Elisabeth A. Wilson, Tracy S. Fitzgerald, Kohei Segawa, Koichi Omori, Juichi Ito, Gregory I. Frolenkov, Thomas B. Friedman, Shin-ichiro Kitajiri
Abstract
BACKGROUND The hereditary transthyretin (TTR) amyloidoses are a group of diseases for which several disease-modifying treatments are now available. Long-term effectiveness of these therapies is not yet fully known. Moreover, the existence of alternative therapies has resulted in an urgent need to identify patient characteristics that predict response to each therapy.METHODS We carried out a retrospective cohort study of 210 patients with hereditary TTR amyloidosis treated with the kinetic stabilizer tafamidis (20 mg qd). These patients were followed for a period of 18–66 months, after which they were classified by an expert as responders, partial responders, or nonresponders. Correlations between baseline demographic and clinical characteristics, as well as plasma biomarkers and response to therapy, were investigated.RESULTS 34% of patients exhibited an almost complete arrest of disease progression (classified by an expert as responders); 36% had a partial to complete arrest in progression of some but not all disease components (partial responders); whereas the remaining 30% continued progressing despite therapy (nonresponders). We determined that disease severity, sex, and native TTR concentration at the outset of treatment were the most relevant predictors of response to tafamidis. Plasma tafamidis concentration after 12 months of therapy was also a predictor of response for male patients. Using these variables, we built a model to predict responsiveness to tafamidis.CONCLUSION Our study indicates long-term effectiveness for tafamidis, a kinetic stabilizer approved for the treatment of hereditary TTR amyloidosis. Moreover, we created a predictive model that can be potentially used in the clinical setting to inform patients and clinicians in their therapeutic decisions.
Authors
Cecília Monteiro, Jaleh S. Mesgazardeh, João Anselmo, Joana Fernandes, Marta Novais, Carla Rodrigues, Gabriel J. Brighty, David L. Powers, Evan T. Powers, Teresa Coelho, Jeffery W. Kelly
Abstract
BACKGROUND Cerebral cavernous angiomas (CAs) with a symptomatic hemorrhage (CASH) have a high risk of recurrent hemorrhage and serious morbidity.METHODS Eighteen plasma molecules with mechanistic roles in CA pathobiology were investigated in 114 patients and 12 healthy subjects. The diagnostic biomarker of a CASH in the prior year was derived as that minimizing the Akaike information criterion and validated using machine learning, and was compared with the prognostic CASH biomarker predicting bleeding in the subsequent year. Biomarkers were longitudinally followed in a subset of cases. The biomarkers were queried in the lesional neurovascular unit (NVU) transcriptome and in plasma miRNAs from CASH and non-CASH patients.RESULTS The diagnostic CASH biomarker included a weighted combination of soluble CD14 (sCD14), VEGF, C-reactive protein (CRP), and IL-10 distinguishing CASH patients with 76% sensitivity and 80% specificity (P = 0.0003). The prognostic CASH biomarker (sCD14, VEGF, IL-1β, and sROBO-4) was confirmed to predict a bleed in the subsequent year with 83% sensitivity and 93% specificity (P = 0.001). Genes associated with diagnostic and prognostic CASH biomarkers were differentially expressed in CASH lesional NVUs. Thirteen plasma miRNAs were differentially expressed between CASH and non-CASH patients.CONCLUSION Shared and unique biomarkers of recent symptomatic hemorrhage and of future bleeding in CA are mechanistically linked to lesional transcriptome and miRNA. The biomarkers may be applied for risk stratification in clinical trials and developed as a tool in clinical practice.FUNDING NIH, William and Judith Davis Fund in Neurovascular Surgery Research, Be Brave for Life Foundation, Safadi Translational Fellowship, Pritzker School of Medicine, and Sigrid Jusélius Foundation.
Authors
Seán B. Lyne, Romuald Girard, Janne Koskimäki, Hussein A. Zeineddine, Dongdong Zhang, Ying Cao, Yan Li, Agnieszka Stadnik, Thomas Moore, Rhonda Lightle, Changbin Shi, Robert Shenkar, Julián Carrión-Penagos, Sean P. Polster, Sharbel Romanos, Amy Akers, Miguel Lopez-Ramirez, Kevin J. Whitehead, Mark L. Kahn, Mark H. Ginsberg, Douglas A. Marchuk, Issam A. Awad
Abstract
Th1 and Th17 are important in the pathogenesis of autoimmune diseases and they depend on glycolysis as a source of energy. T cell antigen receptor signaling phosphorylates a serine/threonine kinase, calcium/calmodulin–dependent protein kinase IV (CaMK4), and promotes glycolysis. Based on these findings we hypothesized that CaMK4 promotes glycolysis. Camk4-deficient CD4+ T cells and cells treated with a CaMK4 inhibitor had less glycolysis compared with their counterparts. Pull-down of CaMK4 and mass spectrometry identified pyruvate kinase muscle isozyme (PKM), the final rate-limiting enzyme in glycolysis, as a binding partner. Coimmunoprecipitation and Western blotting showed that CaMK4 interacts directly with PKM2. Camk4-deficient CD4+ T cells displayed decreased pyruvate kinase activity. Silencing or pharmacological inhibition of PKM2 reduced glycolysis and in vitro differentiation to Th1 and Th17 cells, while PKM2 overexpression restored Th17 cell differentiation. Treatment with a PKM2 inhibitor ameliorated experimental autoimmune encephalomyelitis and CD4+ T cells treated with PKM2 inhibitor or Pkm2-shRNA caused limited disease activity in an adoptive cell transfer model of experimental autoimmune encephalomyelitis. Our data demonstrate that CaMK4 binds to PKM2 and promotes its activity, which is requisite for Th1 and Th17 differentiation in vitro and in vivo. PKM2 represents a therapeutic target for T cell–dependent autoimmune diseases.
Authors
Michihito Kono, Kayaho Maeda, Irina Stocton-Gavanescu, Wenliang Pan, Masataka Umeda, Eri Katsuyama, Catalina Burbano, Seo Yeon K. Orite, Milena Vukelic, Maria G. Tsokos, Nobuya Yoshida, George C. Tsokos
Abstract
African Americans develop end-stage renal disease at a higher rate compared with European Americans due to 2 polymorphisms (G1 and G2 risk variants) in the apolipoprotein L1 (APOL1) gene common in people of African ancestry. Although this compelling genetic evidence provides an exciting opportunity for personalized medicine in chronic kidney disease, drug discovery efforts have been greatly hindered by the fact that APOL1 expression is lacking in rodents. Here, we describe a potentially novel physiologically relevant genomic mouse model of APOL1-associated renal disease that expresses human APOL1 from the endogenous human promoter, resulting in expression in similar tissues and at similar relative levels as humans. While naive APOL1-transgenic mice did not exhibit a renal disease phenotype, administration of IFN-γ was sufficient to robustly induce proteinuria only in APOL1 G1 mice, despite inducing kidney APOL1 expression in both G0 and G1 mice, serving as a clinically relevant “second hit.” Treatment of APOL1 G1 mice with IONIS-APOL1Rx, an antisense oligonucleotide (ASO) targeting APOL1 mRNA, prior to IFN-γ challenge robustly and dose-dependently inhibited kidney and liver APOL1 expression and protected against IFN-γ–induced proteinuria, indicating that the disease-relevant cell types are sensitive to ASO treatment. Therefore, IONIS-APOL1Rx may be an effective therapeutic for APOL1 nephropathies and warrants further development.
Authors
Mariam Aghajan, Sheri L. Booten, Magnus Althage, Christopher E. Hart, Anette Ericsson, Ingela Maxvall, Joseph Ochaba, Angela Menschik-Lundin, Judith Hartleib, Steven Kuntz, Danielle Gattis, Christine Ahlström, Andrew T. Watt, Jeffery A. Engelhardt, Brett P. Monia, Maria Chiara Magnone, Shuling Guo
Abstract
The increased formation of methylglyoxal (MG) under hyperglycemia is associated with the development of microvascular complications in patients with diabetes mellitus; however, the effects of elevated MG levels in vivo are poorly understood. In zebrafish, a transient knockdown of glyoxalase 1, the main MG detoxifying system, led to the elevation of endogenous MG levels and blood vessel alterations. To evaluate effects of a permanent knockout of glyoxalase 1 in vivo, glo1–/– zebrafish mutants were generated using CRISPR/Cas9. In addition, a diet-induced–obesity zebrafish model was used to analyze glo1–/– zebrafish under high nutrient intake. Glo1–/– zebrafish survived until adulthood without growth deficit and showed increased tissue MG concentrations. Impaired glucose tolerance developed in adult glo1–/– zebrafish and was indicated by increased postprandial blood glucose levels and postprandial S6 kinase activation. Challenged by an overfeeding period, fasting blood glucose levels in glo1–/– zebrafish were increased which translated into retinal blood vessel alterations. Thus, the data have identified a defective MG detoxification as a metabolic prerequisite and glyoxalase 1 alterations as a genetic susceptibility to the development of type 2 diabetes mellitus under high nutrition intake.
Authors
Elisabeth Lodd, Lucas M. Wiggenhauser, Jakob Morgenstern, Thomas H. Fleming, Gernot Poschet, Michael Büttner, Christoph T. Tabler, David P. Wohlfart, Peter P. Nawroth, Jens Kroll
Abstract
During chronic HIV infection, immune cells become increasingly dysfunctional and exhausted. Little is known about how immune functions are restored after initiation of antiretroviral therapy (ART). In this study, we assessed cellular and metabolic activity and evaluated the effect of individual antiretrovirals on cellular subsets ex vivo in ART-treated and treatment-naive chronically HIV-infected individuals. We observed that cellular respiration was significantly decreased in most immune cells in chronic HIV infection. The respiration was correlated to immune activation and the inhibitory receptor programmed cell death 1 on CD8+ T cells. ART restored the metabolic phenotype, but the respiratory impairment persisted in CD4+ T cells. This was particularly the case for individuals receiving integrase strand transfer inhibitors. CD4+ T cells from these individuals showed a significant reduction in ex vivo proliferative capacity compared with individuals treated with protease inhibitors or nonnucleoside reverse transcriptase inhibitors. We noticed a significant decrease in respiration of cells treated with dolutegravir (DLG) or elvitegravir (EVG) and a switch from polyfunctional to TNF-α–dominated “stress” immune response. There was no effect on glycolysis, consistent with impaired mitochondrial function. We detected increased levels of mitochondrial ROS and mitochondrial mass. These findings indicate that EVG and DLG use is associated with slow proliferation and impaired respiration with underlying mitochondrial dysfunction, resulting in overall decreased cellular function in CD4+ T cells.
Authors
Marek Korencak, Morgan Byrne, Enrico Richter, Bruce T. Schultz, Patrick Juszczak, Julie A. Ake, Anuradha Ganesan, Jason F. Okulicz, Merlin L. Robb, Buena de los Reyes, Sandra Winning, Joachim Fandrey, Timothy H. Burgess, Stefan Esser, Nelson L. Michael, Brian K. Agan, Hendrik Streeck
Abstract
Inhibition of Bruton tyrosine kinase (BTK) is a breakthrough therapy for certain B cell lymphomas and B cell chronic lymphatic leukemia. Covalent BTK inhibitors (e.g., ibrutinib) bind to cysteine C481, and mutations of this residue confer clinical resistance. This has led to the development of noncovalent BTK inhibitors that do not require binding to cysteine C481. These new compounds are now entering clinical trials. In a systematic BTK mutagenesis screen, we identify residues that are critical for the activity of noncovalent inhibitors. These include a gatekeeper residue (T474) and mutations in the kinase domain. Strikingly, co-occurrence of gatekeeper and kinase domain lesions (L512M, E513G, F517L, L547P) in cis results in a 10- to 15-fold gain of BTK kinase activity and de novo transforming potential in vitro and in vivo. Computational BTK structure analyses reveal how these lesions disrupt an intramolecular mechanism that attenuates BTK activation. Our findings anticipate clinical resistance mechanisms to a new class of noncovalent BTK inhibitors and reveal intramolecular mechanisms that constrain BTK’s transforming potential.
Authors
Shenqiu Wang, Sayan Mondal, Chunying Zhao, Marjan Berishaj, Phani Ghanakota, Connie Lee Batlevi, Ahmet Dogan, Venkatraman E. Seshan, Robert Abel, Michael R. Green, Anas Younes, Hans-Guido Wendel
Abstract
BACKGROUND Metabolic syndrome (MetS) is highly correlated with obesity and cardiovascular risk, but the importance of dietary carbohydrate independent of weight loss in MetS treatment remains controversial. Here, we test the theory that dietary carbohydrate intolerance (i.e., the inability to process carbohydrate in a healthy manner) rather than obesity per se is a fundamental feature of MetS.METHODS Individuals who were obese with a diagnosis of MetS were fed three 4-week weight-maintenance diets that were low, moderate, and high in carbohydrate. Protein was constant and fat was exchanged isocalorically for carbohydrate across all diets.RESULTS Despite maintaining body mass, low-carbohydrate (LC) intake enhanced fat oxidation and was more effective in reversing MetS, especially high triglycerides, low HDL-C, and the small LDL subclass phenotype. Carbohydrate restriction also improved abnormal fatty acid composition, an emerging MetS feature. Despite containing 2.5 times more saturated fat than the high-carbohydrate diet, an LC diet decreased plasma total saturated fat and palmitoleate and increased arachidonate.CONCLUSION Consistent with the perspective that MetS is a pathologic state that manifests as dietary carbohydrate intolerance, these results show that compared with eucaloric high-carbohydrate intake, LC/high-fat diets benefit MetS independent of whole-body or fat mass.TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02918422.FUNDING Dairy Management Inc. and the Dutch Dairy Association.
Authors
Parker N. Hyde, Teryn N. Sapper, Christopher D. Crabtree, Richard A. LaFountain, Madison L. Bowling, Alex Buga, Brandon Fell, Fionn T. McSwiney, Ryan M. Dickerson, Vincent J. Miller, Debbie Scandling, Orlando P. Simonetti, Stephen D. Phinney, William J. Kraemer, Sarah A. King, Ronald M. Krauss, Jeff S. Volek
Abstract
The activation and recruitment of NK cells to the site of viral infection are crucial for virus control. However, it remains largely unknown what controls the recruitment of the activated NK cells to the infection site. In a model of intraperitoneal infection with vaccinia virus (VV), we showed that poly(ADP-ribose) polymerase-1 (PARP-1), a sensor of DNA damage, is critical for NK cell recruitment to the site of infection and viral control in vivo. We further demonstrated that PARP-1 promotes the production of CCL2 and that the CCL2-CCR2 axis is essential for NK cell recruitment to the infection site. In addition, we demonstrated that peritoneal macrophages are the main producer of PARP-1–dependent CCL2 secretion. Mechanistically, PARP-1 functions as a regulator of NF-κB by promoting its nuclear translocation and binding to its response sequences in macrophages upon VV infection. Taken together, our results reveal a potentially previously unknown role for PARP-1–dependent CCL2 production in NK cell migration and viral control and may provide important insights into the design of effective NK cell–based therapies for viral infections and cancer.
Authors
Qiyang Shou, Huiying Fu, Xiaopei Huang, Yiping Yang
Abstract
Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by muscle weakness and caused by pathogenic autoantibodies that bind to membrane proteins at the neuromuscular junction. Most patients have autoantibodies against the acetylcholine receptor (AChR), but a subset of patients have autoantibodies against muscle-specific tyrosine kinase (MuSK) instead. MuSK is an essential component of the pathway responsible for synaptic differentiation, which is activated by nerve-released agrin. Through binding MuSK, serum-derived autoantibodies inhibit agrin-induced MuSK autophosphorylation, impair clustering of AChRs, and block neuromuscular transmission. We sought to establish individual MuSK autoantibody clones so that the autoimmune mechanisms could be better understood. We isolated MuSK autoantibody-expressing B cells from 6 MuSK MG patients using a fluorescently tagged MuSK antigen multimer, then generated a panel of human monoclonal autoantibodies (mAbs) from these cells. Here we focused on 3 highly specific mAbs that bound quantitatively to MuSK in solution, to MuSK-expressing HEK cells, and at mouse neuromuscular junctions, where they colocalized with AChRs. These 3 IgG isotype mAbs (2 IgG4 and 1 IgG3 subclass) recognized the Ig-like domain 2 of MuSK. The mAbs inhibited AChR clustering, but intriguingly, they enhanced rather than inhibited MuSK phosphorylation, which suggests an alternative mechanism for inhibiting AChR clustering.
Authors
Kazushiro Takata, Panos Stathopoulos, Michelangelo Cao, Marina Mané-Damas, Miriam L. Fichtner, Erik S. Benotti, Leslie Jacobson, Patrick Waters, Sarosh R. Irani, Pilar Martinez-Martinez, David Beeson, Mario Losen, Angela Vincent, Richard J. Nowak, Kevin C. O’Connor
Abstract
An imbalance of nephroprotective factors and renal damaging molecules contributes to development and progression of chronic kidney disease (CKD). We investigated associations of renoprotective factor gene expression patterns with CKD severity and outcome. Gene expression profiles of 197 previously reported renoprotective factors were analyzed in a discovery cohort in renal biopsies of 63 CKD patients. Downregulation of dicarbonyl and L-xylulose reductase (DCXR) showed the strongest association with disease progression. This significant association was validated in an independent set of 225 patients with nephrotic syndrome from the multicenter NEPTUNE cohort. Reduced expression of DCXR was significantly associated with degree of histological damage as well as with lower estimated glomerular filtration rate and increased urinary protein levels. DCXR downregulation in CKD was confirmed in 3 publicly available transcriptomics data sets in the context of CKD. Expression of DCXR showed positive correlations to enzymes that are involved in dicarbonyl stress detoxification based on transcriptomics profiles. The sodium glucose cotransporter-2 (SGLT2) inhibitors canagliflozin and empagliflozin showed a beneficial effect on renal proximal tubular cells under diabetic stimuli–enhanced DCXR gene expression. In summary, lower expression of the renoprotective factor DCXR in renal tissue is associated with more severe disease and worse outcome in human CKD.
Authors
Paul Perco, Wenjun Ju, Julia Kerschbaum, Johannes Leierer, Rajasree Menon, Catherine Zhu, Matthias Kretzler, Gert Mayer, Michael Rudnicki, Nephrotic Syndrome Study Network (NEPTUNE)
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Abstract
Colorectal cancer (CRC) is the third most frequent neoplastic disorder and is a main cause of tumor-related mortality as many patients progress to stage IV metastatic CRC. Standard care consists of combination chemotherapy (FOLFIRI or FOLFOX). Patients with WT KRAS typing are eligible to receive anti-EGFR therapy combined with chemotherapy. Unfortunately, predicting efficacy of CRC anti-EGFR therapy has remained challenging. Here we uncover that the EGFR-pathway component RasGRP1 acts as CRC tumor suppressor in the context of aberrant Wnt signaling. We find that RasGRP1 suppresses EGF-driven proliferation of colonic epithelial organoids. Having established that RasGRP1 dosage levels impacts biology, we focused on CRC patients next. Mining five different data platforms, we establish that RasGRP1 expression levels decrease with CRC progression and predict poor clinical outcome of patients. Lastly, deletion of one or two Rasgrp1 alleles makes CRC spheroids more susceptible to EGFR inhibition. Retrospective analysis of the CALGB80203 clinical trial shows that addition of anti-EGFR therapy to chemotherapy significantly improves outcome for CRC patients when tumors express low RasGRP1 suppressor levels. In sum, RasGRP1 is a unique biomarker positioned in the EGFR pathway and of potential relevance to anti-EGFR therapy for CRC patients.
Authors
Oghenekevwe M. Gbenedio, Caroline Bonnans, Delphine Grun, Chih-Yang Wang, Ace J. Hatch, Michelle R. Mahoney, David Barras, Mary Matli, Yi Miao, K. Christopher Garcia, Sabine Tejpar, Mauro Delorenzi, Alan P. Venook, Andrew B. Nixon, Robert S. Warren, Jeroen P. Roose, Philippe Depeille
Abstract
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 co-transporting 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-G protein-coupled bile acid receptor (TGR5) double knockout mice were equally protected against diet-induced-obesity as NTCP single knockout mice. NTCP knockout mice displayed decreased intestinal fat absorption and a trend towards 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.
Authors
Joanne M. Donkers, Sander Kooijman, Davor Slijepcevic, Roni F. Kunst, Reinout L.P. Roscam Abbing, Lizette C.J.M 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
Abstract
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, we use a combination of genomics, unbiased discovery 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. MS has also demonstrated unambiguously the presentation by MHC I, of confirmed tumor rejection neoepitopes which 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 significantly 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.
Authors
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
Abstract
Adeno-associated-viral (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 eightfold increased specific activity compared to 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 novel system utilizing emicizumab, a FVIII-mimicking bispecific antibody, the hyperactivity of both recombinant FIX-R338L and AAV-mediated-transgene-expressed FIX-R338L from HB GT subjects is 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.
Authors
Benjamin J. Samelson-Jones, Jonathan D. Finn, Lindsey A. George, Rodney M. Camire, Valder R. Arruda
Abstract
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 impacts brain function in vivo remains unclear. Methods: This randomized, single-blinded, 2-way-crossover, sham-controlled, pilot study determined the effects of hyperinsulinemia on fMRI brain activation during a 2-back working memory task in 9 healthy older adults (aged 57-79 years). Each participant underwent two 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 to 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 National Institutes of Health (5R21AG051958, 2016).
Authors
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
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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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