Tregs require IL-2 signaling for signal transducer and activator of transcription 5 (STAT5)-mediated induction of Foxp3. While phosphatase 2A (PP2A) is a negative regulator of IL-2 production in effector T cells and Tregs do not produce IL-2, it is not known whether PP2A controls IL-2 signaling in Tregs. To address the role of PP2A in IL-2 signaling in Tregs we studied mice engineered to lack PP2A in all Foxp3-expressing cells. We report that PP2A is required to enable Foxp3 expression and to maintain sufficient numbers of Tregs in the thymus. We show for the first time that PP2A prevents the selective loss of surface IL-2Rβ and preserves IL-2R signaling potency in Tregs. The loss of IL-2Rβ in thymus- and spleen-derived Tregs that lack PP2A is due to increased sheddase activity. Pan-sheddase or selective A disintegrin and metalloproteinase 10 (ADAM10) inhibition, like forced expression of IL-2Rβ in PP2A-deficient Tregs restored IL-2Rβ expression and signaling. Thus, PP2A restrains the sheddase activity of ADAM10 in Treg cells to prevent the cleavage of IL-2Rβ from the cell surface to enable competent IL-2R signaling which is essential for Tregs development and homeostasis.
Amir Sharabi, Hao Li, Isaac R. Kasper, Wenliang Pan, Esra Meidan, Maria G. Tsokos, Vaishali R. Moulton, George C. Tsokos
Drug refractory epilepsy (RE) is a chronic neurological disease with varied etiology that represents a group of patients whose seizures do not respond to anti-epileptic drugs. The immune system may have a role in seizure and epilepsy development, but the specific mechanisms of inflammation that lead to epileptogenesis and contribute to RE are unknown. Here, we used mass cytometry to comprehensively study the immune system of pediatric patients with RE and compared their immune profile and function with patients with age-matched autoimmune encephalitis (AIE) and healthy controls. Patients with RE and AIE displayed similar immune profiles overall, with changes in CD4+ and CD8+ T-cell subsets and an unbalance toward pro-inflammatory IL-17 production. In addition, patients with RE uniquely showed an altered balance in natural killer cell subsets. A systems level intercellular network analysis identified rewiring of the immune system leading to loss of inhibitory/regulatory intercellular connections and emergence of pro-inflammatory pathogenic functions in neuro-inflammatory immune-cell networks in patients with AIE and RE. These data underscore the contribution of systemic inflammation to the pathogenesis of seizures and epileptogenesis and have direct translational implications in advancing diagnostics and therapeutics design.
Pavanish Kumar, Derrick Wei Shih Chan, Amanda Lim, Bhairav Paleja, Simon Ling, Lai Li Yun, Su Li Poh, Adeline Ngoh, Thaschawee Arkachaisri, Joo Guan Yeo, Salvatore Albani
Many lung diseases result from a failure of efficient regeneration of damaged alveolar epithelial cells (AECs) after lung injury. During regeneration, AEC2s proliferate to replace lost cells, after which proliferation halts and some AEC2s transdifferentiate into AEC1s to restore normal alveolar structure and function. Although the mechanisms underlying AEC2 proliferation have been studied, the mechanisms responsible for halting proliferation and inducing transdifferentiation are poorly understood. To identify candidate signaling pathways responsible for halting proliferation and inducing transdifferentiation, we performed single cell RNA sequencing on AEC2s during regeneration in a murine model of lung injury induced by intratracheal LPS. Unsupervised clustering revealed distinct subpopulations of regenerating AEC2s: proliferating, cell cycle arrest, and transdifferentiating. Gene expression analysis of these transitional subpopulations revealed that TGFβ signaling was highly upregulated in the cell cycle arrest subpopulation and relatively downregulated in transdifferentiating cells. In cultured AEC2s, TGFβ was necessary for cell cycle arrest but impeded transdifferentiation. We conclude that during regeneration after LPS-induced lung injury, TGFβ is a critical signal halting AEC2 proliferation but must be inactivated to allow transdifferentiation. This study provides insight into the molecular mechanisms regulating alveolar regeneration and the pathogenesis of diseases resulting from a failure of regeneration.
Kent A. Riemondy, Nicole L. Jansing, Peng Jiang, Elizabeth F. Redente, Austin E. Gillen, Rui Fu, Alyssa J. Miller, Jason R. Spence, Anthony N. Gerber, Jay R. Hesselberth, Rachel L. Zemans
We have previously reported that the carboxy-terminal proteolytic cleavage product of the COL6α3 chain that we refer to as “endotrophin” has potent effects on transformed mammary ductal epithelial cells in rodents. Endotrophin (ETP) is abundantly expressed in adipose tissue. It is a chemoattractant for macrophages, exerts effects on endothelial cells and through epithelial-mesenchymal transition (EMT) enhances progression of tumor cells. In a recombinant form, human endotrophin exerts similar effects on human macrophages and endothelial cells as its rodent counterpart. It enhances EMT in human breast cancer cells and upon overexpression in tumor cells, the cells become chemoresistant. Here, we report the identification of endotrophin from human plasma. It is circulating at higher levels in breast cancer patients. We have developed neutralizing monoclonal antibodies against human endotrophin and provide evidence for the effectiveness of these antibodies to curb tumor growth and enhance chemosensitivity in a nude mouse model carrying human tumor cell lesions. Combined, the data validate endotrophin as a viable target for anti-tumor therapy for human breast cancer and opens the possibility for further use of these new reagents for anti-fibrotic approaches in liver, kidney, bone marrow and adipose tissue.
Dawei Bu, Clair Crewe, Christine M. Kusminski, Ruth Gordillo, Alexandra L. Ghaben, Min Kim, Jiyoung Park, Hui Deng, Wei Xiong, Xiao-Zheng Liu, Per Eystein Lønning, Nils Halberg, Adan Rios, Yujun Chang, Anneliese Gonzalez, Ningyan Zhang, Zhiqiang An, Philipp E. Scherer
In demyelinating diseases such as Multiple Sclerosis (MS), demyelination of neuronal fibers impairs impulse conduction and causes axon degeneration. While neuronal activity stimulates oligodendrocyte production and myelination in normal conditions, it remains unclear whether the activity of demyelinated axons restores their loss-of-function in a harmful environment. To investigate this question, we established a model to induce a moderate optogenetic stimulation of demyelinated axons in the corpus callosum at the level of the motor cortex in which cortical circuit activation and locomotor effects were reduced in adult freely moving mice. We demonstrate that a moderate activation of demyelinated axons enhances the differentiation of oligodendrocyte precursor cells onto mature oligodendrocytes, but only under a repeated stimulation paradigm. This activity-dependent increase in the oligodendrocyte pool promotes an extensive remyelination and functional restoration of conduction, as revealed by ultrastructural analyses and compound action potential recordings. Our findings reveal the need of preserving an appropriate neuronal activity in the damaged tissue to promote oligodendrocyte differentiation and remyelination, likely by enhancing axon-oligodendroglia interactions. Our results provide new perspectives for translational research using neuromodulation in demyelinating diseases.
Fernando C. Ortiz, Chloé Habermacher, Mariana Graciarena, Pierre-Yves Houry, Akiko Nishiyama, Brahim Nait-Oumesmar, Maria Cecilia Angulo
Changes in neuronal activity alter blood flow to match energy demand with the supply of oxygen and nutrients. This functional hyperemia is maintained by interactions between neurons, vascular cells, and glia. However, how changing neuronal activity prevalent at the onset of neurodegenerative disease affects neurovascular elements is unclear. Here, in mice with photoreceptor degeneration, a model of neuron-specific dysfunction, we combined assessment of visual function, neurovascular unit structure, and the blood-retina barrier permeability. We found that the rod loss paralleled remodeling of the neurovascular unit, comprised of photoreceptors, retinal pigment epithelium, and Muller glia. When significant visual function was still present, blood flow became disrupted and blood-retina barrier began to fail, facilitating cone loss and vision decline. Thus, in contrast to the established view, vascular deficit in neuronal degeneration is not a late consequence of neuronal dysfunction, but is present early in the course of disease. These findings further establish the importance of vascular deficit and blood retina barrier function in neuron-specific loss, and highlight it as a target for early therapeutic intervention.
Elena Ivanova, Nazia M. Alam, Glen T. Prusky, Botir T. Sagdullaev
High autophagic activity in podocytes, terminally differentiated cells which serve as main components of the kidney filtration barrier, is essential for podocyte survival under various challenges. How podocytes maintain such a high level of autophagy, however, remains unclear. Here we report that signal regulatory protein α (SIRPα) plays a key role in promoting podocyte autophagy. Unlike other glomerular cells, podocytes strongly express SIRPα, which is, however, downregulated in patients with focal segmental glomerulosclerosis and mice with experimental nephropathy. Podocyte SIRPα levels are inversely correlated with the severity of podocyte injury and proteinuria but positively with autophagy. Compared to wild-type littermates, Sirpa-deficient mice display greater age-related podocyte injury and proteinuria and develop more rapid and severe renal injury in various models of experimental nephropathy. Mechanistically, podocyte SIRPα strongly reduces Akt/GSK-3β/β-catenin signaling, leading to an increase in autophagic activity. Our findings thus demonstrate a critical protective role of SIRPα in podocyte survival via maintaining autophagic activity.
Limin Li, Ying Liu, Shan Li, Yong Yang, Caihong Zeng, Weiwei Rong, Hongwei Liang, Mingchao Zhang, Xiaodong Zhu, Koby Kidder, Yuan Liu, Zhihong Liu, Ke Zen
Regulatory T cells (Tregs) are key modulators of inflammation and are important for the maintenance of peripheral tolerance. Adoptive immunotherapy with polyclonal Tregs holds promise in organ transplantation, graft-versus-host disease, and autoimmune diseases, but may be enhanced by antigen-specific, long-lived Treg cells. We modified primary human Tregs with chimeric antigen-receptors (CARs) bearing different costimulatory domains and performed in vitro analyses of their phenotype and function. While neither the presence of a CAR nor the type of costimulation domain influenced Foxp3 expression in Tregs, the costimulation domain of the CARs affected CAR Treg surface phenotype and functions such as cytokine production. Furthermore, signaling from the CD28 costimulation domain maintained CAR Treg suppressor function, whereas 4-1B costimulation did not. In vivo, CAR Tregs accumulated at sites expressing target antigen, and suppressed antigen specific effector T cell responses; however, only CAR Tregs with CD28 signaling domains were potent inhibitors of effector T cell mediated graft rejection in vivo. Our findings support the use of CD28 based CAR-Tregs for tissue specific immune suppression in the clinic.
Angela C. Boroughs, Rebecca C. Larson, Bryan D. Choi, Amanda A. Bouffard, Lauren S. Riley, Erik Schiferle, Anupriya S. Kulkarni, Curtis L. Cetrulo, David Ting, Bruce R. Blazar, Shadmehr Demehri, Marcela V. Maus
MHC I-restricted epitopes of chicken ovalbumin (OVA) were originally identified using CD8 T cells as probes. Here, using bioinformatics tools, we identify four additional epitopes in OVA in addition to a cryptic epitope. Each new epitope is presented in vivo, as deduced from the lack of CD8 response to it in OVA-transgenic mice. In addition, CD8 responses to the known and novel epitopes are examined in C57BL/6 mice exposed to the OVA-expressing tumor E.G7 in several ways. No responses to any epitope including SIINFEKL are detected in mice with growing E.G7 or mice immunized with the tumor. Only in E.G7-bearing mice treated with an anti-CTLA4 antibody which depletes tumor-infiltrating regulatory T cells, CD8 responses to SIINFEKL and the novel epitope EKYNLTSVL are detected. Finally, all epitopes fails to treat mice with pre-existing tumors. These observations force an important re-consideration of the common assumptions about the therapeutic value of neoepitopes detected by CD8 responses in tumor-bearing hosts.
Sukrut Hemant Karandikar, John Sidney, Alessandro Sette, Mark Joseph Selby, Alan Jerry Korman, Pramod Kumar Srivastava
Because injured mitochondria can accelerate cell death through the elaboration of oxidative free radicals and other mediators, it is striking that proliferator gamma coactivator 1-alpha (PGC1α), a stimulator of increased mitochondrial abundance, protects stressed renal cells instead of potentiating injury. Here we report that PGC1α’s induction of lysosomes via transcription factor EB (TFEB) may be pivotal for kidney protection. CRISPR and stable gene transfer showed that PGC1α knockout tubular cells were sensitized to the genotoxic stressor cisplatin whereas transgenic cells were protected. The biosensor mtKeima unexpectedly revealed that cisplatin blunts mitophagy both in cells and mice. PGC1α not only counteracted this effect but also raised basal mitophagy, as did the downstream mediator nicotinamide adenine dinucleotide (NAD+). PGC1α did not consistently affect known autophagy pathways modulated by cisplatin. Instead RNA sequencing identified coordinated regulation of lysosomal biogenesis via TFEB. This effector pathway was sufficiently important that inhibition of TFEB or lysosomes unveiled a striking harmful effect of excess PGC1α in cells and conditional mice. These results uncover an unexpected effect of cisplatin on mitophagy and PGC1α’s exquisite reliance on lysosomes for kidney protection. Finally, the data illuminate TFEB as a novel target for renal tubular stress resistance.
Matthew R. Lynch, Mei T. Tran, Kenneth M. Ralto, Zsuzsanna K. Zsengeller, Vinod Raman, Swati S. Bhasin, Nuo Sun, Xiuying Chen, Daniel Brown, Ilsa I. Rovira, Kensei Taguchi, Craig R. Brooks, Isaac E. Stillman, Manoj K. Bhasin, Toren Finkel, Samir M. Parikh
AXL overexpression is a common resistance mechanism to anti-cancer therapies, including the resistance to BYL719 (Alpelisib) – the p110α isoform specific inhibitor of phosphoinositide 3-kinase (PI3K) – in esophagus and head and neck squamous cell carcinoma (ESCC, HNSCC respectively). However, the mechanisms underlying AXL overexpression in resistance to BYL719 remain elusive. Here we demonstrated that the AP-1 transcription factors, c-JUN and c-FOS, regulate AXL overexpression in HNSCC and ESCC. The expression of AXL was correlated with that of c-JUN both in HNSCC patients and in HNSCC and ESCC cell lines. Silencing of c-JUN and c-FOS expression in tumor cells downregulated AXL expression and enhanced the sensitivity of human papilloma virus positive (HPVPos) and negative (HPVNeg) tumor cells to BYL719 in vitro. Blocking of the c-JUN N-terminal kinase (JNK) using SP600125 in combination with BYL719 showed a synergistic anti-proliferative effect in vitro, which was accompanied by AXL downregulation and potent inhibition of the mTOR pathway. In vivo, the BYL719–SP600125 drug combination led to the arrest of tumor growth in cell line-derived and patient-derived xenograft models, and in syngeneic head and neck murine cancer models. Collectively, our data suggests that JNK inhibition in combination with anti-PI3K therapy is a new therapeutic strategy that should be tested in HPVPos and HPVNeg HNSCC and ESCC patients.
Mai Badarni, Manu Prasad, Noa Balaban, Jonathan Zorea, Ksenia M. Yegodayev, Ben-Zion Joshua, Anat Bahat Dinur, Reidar Grénman, Barak Rotblat, Limor Cohen, Moshe Elkabets
The endoplasmic reticulum (ER) of cancer cells needs to adapt to the enhanced proteotoxic stress associated with the accumulation of unfolded, misfolded and transformation-associated proteins. One way by which tumors thrive in the context of ER stress is by promoting ER-Associated Degradation (ERAD), although the mechanisms are poorly understood. Here, we show that the Small p97/VCP Interacting Protein (SVIP), an endogenous inhibitor of ERAD, undergoes DNA hypermethylation-associated silencing in tumorigenesis to achieve this goal. SVIP exhibits tumor suppressor features and its recovery is associated with increased ER stress and growth inhibition. Proteomic and metabolomic analyses show that cancer cells with epigenetic loss of SVIP are depleted in mitochondrial enzymes and oxidative respiration activity. This phenotype is reverted upon SVIP restoration. The dependence of SVIP hypermethylated cancer cells on aerobic glycolysis and glucose was also associated with sensitivity to an inhibitor of the glucose transporter GLUT1. This could be relevant to the management of tumors carrying SVIP epigenetic loss, because these occur in high-risk patients who manifest poor clinical outcomes. Overall, our study provides insights into how epigenetics helps deal with ER stress and how SVIP epigenetic loss in cancer may be amenable to therapies that target glucose transporters.
Pere Llinàs-Arias, Margalida Rosselló-Tortella, Paula Lopez-Serra, Montserrat Pérez-Salvia, Fernando Setién, Silvia Marin, Juan P. Muñoz, Alexandra Junza, Jordi Capellades, Maria E. Calleja-Cervantes, Humberto J. Ferreira, Manuel Castro de Moura, Marina Srbic, Anna Martínez-Cardús, Carolina de la Torre, Alberto Villanueva, Marta Cascante, Oscar Yanes, Antonio Zorzano, Catia Moutinho, Manel Esteller
The mTOR pathway is central to most cells. How mTOR is activated in macrophages and modulates macrophage physiology remain poorly understood. The tumor suppressor Folliculin (FLCN) is a GAP for RagC/D, a regulator of mTOR. We show here that LPS potently suppresses FLCN in macrophages, allowing nuclear translocation of the transcription factor TFE3, leading to lysosome biogenesis, cytokine production, and hypersensitivity to inflammatory signals. Nuclear TFE3 additionally activates a transcriptional RagD positive feedback loop that stimulates FLCN-independent canonical mTOR signaling to S6K and increases cellular proliferation. LPS thus simultaneously suppresses the TFE3 arm and activates the S6K arm of mTOR. In vivo, mice lacking myeloid FLCN reveal chronic macrophage activation, leading to profound histiocytic infiltration and tissue disruption, with hallmarks of human histiocytic syndromes like Erdheim-Chester Disease. Our data thus identify a critical FLCN-mTOR-TFE3 axis in myeloid cells, modulated by LPS, that balances mTOR activation and curbs innate immune responses.
Jia Li, Shogo Wada, Lehn K. Weaver, Chhanda Biswas, Edward M. Behrens, Zoltan Arany
In clinical breast cancer intervention, selection of the optimal treatment protocol based on predictive biomarkers remains an elusive goal. Here, we present a modeling tool to predict the likelihood of breast cancer response to neoadjuvant chemotherapy using patient specific tumor vasculature biomarkers. A semi-automated analysis was implemented and performed on 3990 histological images from 48 patients, with 10–208 images analyzed for each patient. We applied a histology-based model to resected primary breast cancer tumors (n = 30), and then evaluated a cohort of patients (n = 18) undergoing neoadjuvant chemotherapy, collecting pre- and post-treatment pathology specimens and MRI data. We found that core biopsy samples can be used with acceptable accuracy (r = 0.76) to determine histological parameters representative of the whole tissue region. Analysis of model histology parameters obtained from tumor vasculature measurements, specifically diffusion distance divided by radius of drug source (L/rb) and blood volume fraction (BVF), provides a statistically significant separation of patients obtaining a pathologic complete response (pCR) from those that do not (Student’s t-test; P < 0.05). With this model, it is feasible to evaluate primary breast tumor vasculature biomarkers in a patient specific manner, thereby allowing a precision approach to breast cancer treatment.
Terisse A. Brocato, Ursa Brown-Glaberman, Zhihui Wang, Reed G. Selwyn, Colin M. Wilson, Edward F. Wyckoff, Lesley C. Lomo, Jennifer L. Saline, Anupama Hooda-Nehra, Renata Pasqualini, Wadih Arap, C. Jeffrey Brinker, Vittorio Cristini
Hypertrophic cardiomyopathy (HCM) is triggered mainly by mutations in genes encoding sarcomeric proteins, but a significant proportion of patients lack a genetic diagnosis. We identified a novel mutation in the ryanodine receptor 2, RyR2-P1124L, in a patient from a genotype-negative HCM cohort. The aim of this study was to determine whether RyR2-P1124L triggers functional and structural alterations in isolated RyR2 channels and whole hearts. We found that P1124L induces significant conformational changes in the SPRY2 domain of RyR2. Recombinant RyR2-P1124L channels displayed a cytosolic loss-of-function phenotype, which contrasted with a higher sensitivity to luminal [Ca2+], indicating a luminal gain-of-function. Homozygous mice for RyR2-P1124L showed mild cardiac hypertrophy, similar to the human patient. This phenotype, evident at 1 yr of age, was accompanied by an increase in the expression of calmodulin (CaM). P1124L mice also showed higher susceptibility to arrhythmia at 8 mo of age, before the onset of hypertrophy. RyR2-P1124L has a distinct cytosolic loss-of-function and a luminal gain-of-function phenotype. This bifunctionally-divergent behavior triggers arrhythmias and structural cardiac remodeling, and involves overexpression of calmodulin as a potential hypertrophic mediator. This study is relevant to continue elucidating the possible causes of genotype-negative HCM and the role of RyR2 in cardiac hypertrophy.
Francisco J. Alvarado, J. Martijn Bos, Zhiguang Yuchi, Carmen R. Valdivia, Jonathan J. Hernandez, Yan-Ting Zhao, Dawn S. Henderlong, Yan Chen, Talia R. Booher, Cherisse A. Marcou, Filip Van Petegem, Michael J. Ackerman, Hector H. Valdivia
Sarcomeric disarray is a hallmark of gene mutations in patients with Hypertrophic Cardiomyopathy (HCM). However, it is unknown when detrimental sarcomeric changes first occur and whether they originate in the developing embryonic heart. Furthermore, Rho Kinase (ROCK) is a serine threonine protein kinase that is critical for regulating the function of several sarcomeric proteins and therefore, our aim was to determine if disruption of ROCK signalling during the earliest stages of heart development would disrupt the integrity of sarcomeres altering heart development and function. Using a mouse model in which the function of ROCK is specifically disrupted in embryonic cardiomyocytes we demonstrate a progressive cardiomyopathy that first appeared as sarcomeric disarray during cardiogenesis. This led to abnormalities in the structure of embryonic ventricular wall and compensatory cardiomyocyte hypertrophy during foetal development. This sarcomeric disruption and hypertrophy persisted throughout adult life, triggering left ventricular concentric hypertrophy with systolic dysfunction, and re-activation of foetal gene expression and cardiac fibrosis, all typical features of HCM. Taken together, our findings establish a novel mechanism for the developmental origin of the sarcomeric phenotype of HCM and suggest that variants in the ROCK genes or disruption of ROCK signalling could, in part, contribute to its pathogenesis.
Kate E. Bailey, Guy A. MacGowan, Simon Tual-Chalot, Lauren Phillips, Tim J. Mohun, Deborah J. Henderson, Helen M. Arthur, Simon D. Bamforth, Helen M. Phillips
Anthracyclines are amongst the most effective chemotherapeutics ever developed, but they produce grueling side-effects, serious adverse events and resistance often develops over time. We found that these compounds can be sequestered by secreted cellular Prion protein (PrPC), blocking their cytotoxic activity. This effect was dose-dependent using either cell line-conditioned medium or human serum as a source of PrPC. Genetic depletion of PrPC or inhibition of binding via chelation of ionic copper prevented the interaction and restored cytotoxic activity. This was more pronounced for doxorubicin than its epimer, epirubicin. Investigating the relevance to breast cancer management, we found that the levels of PRNP transcript in pre-treatment tumor biopsies stratified relapse-free survival after neoadjuvant treatment with anthracyclines, particularly amongst doxorubicin-treated patients with residual disease at surgery (p=2.8E-08). These data suggest that local sequestration could mediate treatment resistance. Consistent with this, tumor cell expression of PrPC protein correlated with poorer response to doxorubicin but not epirubicin in an independent cohort analyzed by immunohistochemistry, particularly soluble isoforms released into the extracellular environment by shedding (p=0.015). These findings have important potential clinical implications for frontline regimen decision-making. We suggest there is warranted utility for prognostic PrPC/PRNP assays to guide chemo-sensitization strategies that exploit an understanding of PrPC-anthracycline-copper ion complexes.
Adrian P. Wiegmans, Jodi M. Saunus, Sunyoung Ham, Richard J. Lobb, Jamie R. Kutasovic, Andrew J. Dalley, Mariska Miranda, Caroline Atkinson, Simote T. Foliaki, Kaltin Ferguson, Colleen Niland, Cameron N. Johnstone, Victoria Lewis, Steven Collins, Sunil R. Lakhani, Fares Al-Ejeh, Andreas Möller
Peripheral hyperinsulinemia resulting from subcutaneous insulin injection is associated with metabolic defects which include abnormal glucose metabolism. The first aim of this study was to quantify the impairments in liver and muscle glucose metabolism that occur when insulin is delivered via a peripheral vein compared to when it is given through its endogenous secretory route (the hepatic portal vein) in overnight fasted conscious dogs. The second aim was to determine if peripheral delivery of a hepato-preferential insulin analog could restore the physiologic response to insulin that occurs under meal feeding conditions. This study is the first to show that hepatic glucose uptake correlates with insulin’s direct effects on the liver under hyperinsulinemic-hyperglycemic conditions. In addition, glucose uptake was equally divided between the liver and muscle when insulin was infused into the portal vein, but when it was delivered into a peripheral vein the percentage of glucose taken up by muscle was 4-times greater than that going to the liver, with liver glucose uptake being less than half of normal. These defects could not be corrected by adjusting the dose of peripheral insulin. On the other hand, hepatic and non-hepatic glucose metabolism could be fully normalized by a hepato-preferential insulin analog.
Dale S. Edgerton, Melanie Scott, Ben Farmer, Phillip E. Williams, Peter Madsen, Thomas Kjeldsen, Christian L. Brand, Christian Fledelius, Erica Nishimura, Alan D. Cherrington
Bariatric surgeries including vertical sleeve gastrectomy (VSG) ameliorate obesity and diabetes. Weight-loss and accompanying increases to insulin sensitivity contribute to improved glycemia after surgery, however, studies in humans also suggest weight-independent actions of bariatric procedures to lower blood glucose, possibly by improving insulin secretion. To evaluate this hypothesis, we compared VSG operated mice with pair-fed, sham-surgical controls (PF-Sham) 2 weeks after surgery. This paradigm yielded similar post-operative body weight and insulin sensitivity between VSG and calorically restricted PF-Sham animals. However, VSG improved glucose tolerance and markedly enhanced insulin secretion during oral nutrient and intraperitoneal glucose challenges compared to controls. Islets from VSG mice displayed a unique transcriptional signature enriched for genes involved in Ca2+ signaling and insulin secretion pathways. This finding suggests that bariatric surgery leads to intrinsic changes within the islet that alter function. Indeed, islets isolated from VSG mice had increased glucose-stimulated insulin secretion and a left-shifted glucose sensitivity curve compared to islets from PF-Sham mice. Isolated islets from VSG animals showed corresponding increases in the pulse duration of glucose-stimulated Ca2+ oscillations. Together these findings demonstrate a weight-independent improvement in glycemic control following VSG, which is, in part, driven by improved insulin secretion and associated with substantial changes in islet gene expression. These results support a model in which β-cells play a key role in the adaptation to bariatric surgery and the improved glucose tolerance that is typical of these procedures.
Jonathan D. Douros, Jingjing Niu, Sophia M. Sdao, Trillian Gregg, Kelsey H. Fisher-Wellman, Manish S. Bharadwaj, Anthony Molina, Ramamani Arumugam, Mackenzie D. Martin, Enrico Petretto, Matthew J. Merrins, Mark A. Herman, Jenny Tong, Jonathan E. Campbell, David D'Alessio
The auto antigen (Ag)-specific regulatory T cells (Tregs) from pluripotent stem cells (PSCs), i.e., PSC-Tregs, have the ability to suppress autoimmunity. PSC-Tregs can be programmed to be tissue-associated and to infiltrate into local inflamed tissues to suppress autoimmune responses after adoptive transfer. Nevertheless, the mechanisms by which the auto Ag-specific PSC-Tregs suppress the autoimmune response remain to be fully elucidated. In this study, we generated the functional auto Ag-specific Tregs from the induced PSC (iPSCs), i.e., iPSC-Tregs, and investigated the underlying mechanisms of autoimmunity suppression by these Tregs in a type 1 diabetes (T1D) murine model. A double transgenic (Tg) mouse model of T1D was established in F1 mice in which the first generation of RIP-mOVA Tg mice that were crossed with OT-I T cell receptor (TCR) Tg mice was challenged with vaccinia viruses expressing OVA (VACV-OVA). We show that adoptive transfer of OVA-specific iPSC-Tregs greatly suppressed autoimmunity in the animal model and prevented the insulin-secreting pancreatic β cells from destruction. Further, we demonstrate that the adoptive transfer significantly reduced the expression of ICAM-1 in the diabetic pancreas and inhibited the migration of pathogenic CD8+ T cells and the production of the pro-inflammatory IFN-γ in the pancreas. These results indicate that the stem cell-derived tissue-associated Tregs can robustly accumulate in the diabetic pancreas, and through down-regulating the expression of ICAM-1 in the local inflamed tissues and inhibiting the production of pro-inflammatory cytokine IFN-γ, suppress the migration and activity of the pathogenic immune cells that cause T1D.
Mohammad Haque, Fengyang Lei, Xiaofang Xiong, Jugal Kishore Das, Xingcong Ren, Deyu Fang, Shahram Salek-Ardakani, Jin-Ming Yang, Jianxun Song