Issue published June 22, 2023
- Volume 8, Issue 12
- Previous Issue | Next Issue
Loisay et al. report a mouse model of FGFR3-related hypochondroplasia that exhibits progressive dwarfism and osteoporotic features in adulthood. The cover shows a μCT image of the fifth lumbar vertebra of a 10-week-old mouse.
On the cover: Hypochondroplasia gain-of-function mutation in FGFR3 causes defective bone mineralization in mice
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Research Articles
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Abstract
T cells play an important role in acute kidney injury (AKI). Metabolic programming of T cells regulates their function, is a rapidly emerging field, and is unknown in AKI. We induced ischemic AKI in C57BL/6J mice and collected kidneys and spleens at multiple time points. T cells were isolated and analyzed by an immune-metabolic assay. Unbiased machine learning analyses identified a distinct T cell subset with reduced voltage-dependent anion channel 1 and mTOR expression in post-AKI kidneys. Ischemic kidneys showed higher expression of trimethylation of histone H3 lysine 27 and glutaminase. Splenic T cells from post-AKI mice had higher expression of glucose transporter 1, hexokinase II, and carnitine palmitoyltransferase 1a. Human nonischemic and ischemic kidney tissue displayed similar findings to mouse kidneys. Given a convergent role for glutamine in T cell metabolic pathways and the availability of a relatively safe glutamine antagonist, JHU083, effects on AKI were evaluated. JHU083 attenuated renal injury and reduced T cell activation and proliferation in ischemic and nephrotoxic AKI, whereas T cell–deficient mice were not protected by glutamine blockade. In vitro hypoxia demonstrated upregulation of glycolysis-related enzymes. T cells undergo metabolic reprogramming during AKI, and reconstitution of metabolism by targeting T cell glutamine pathway could be a promising novel therapeutic approach.
Authors
Kyungho Lee, Elizabeth A. Thompson, Sepideh Gharaie, Chirag H. Patel, Johanna T. Kurzhagen, Phillip M. Pierorazio, Lois J. Arend, Ajit G. Thomas, Sanjeev Noel, Barbara S. Slusher, Hamid Rabb
×Abstract
Radiographic contact of glioblastoma (GBM) tumors with the lateral ventricle and adjacent stem cell niche correlates with poor patient prognosis, but the cellular basis of this difference is unclear. Here, we reveal and functionally characterize distinct immune microenvironments that predominate in subtypes of GBM distinguished by proximity to the lateral ventricle. Mass cytometry analysis of isocitrate dehydrogenase wild-type human tumors identified elevated T cell checkpoint receptor expression and greater abundance of a specific CD32+CD44+HLA-DRhi macrophage population in ventricle-contacting GBM. Multiple computational analysis approaches, phospho-specific cytometry, and focal resection of GBMs validated and extended these findings. Phospho-flow quantified cytokine-induced immune cell signaling in ventricle-contacting GBM, revealing differential signaling between GBM subtypes. Subregion analysis within a given tumor supported initial findings and revealed intratumor compartmentalization of T cell memory and exhaustion phenotypes within GBM subtypes. Collectively, these results characterize immunotherapeutically targetable features of macrophages and suppressed lymphocytes in GBMs defined by MRI-detectable lateral ventricle contact.
Authors
Todd Bartkowiak, Sierra M. Lima, Madeline J. Hayes, Akshitkumar M. Mistry, Asa A. Brockman, Justine Sinnaeve, Nalin Leelatian, Caroline E. Roe, Bret C. Mobley, Silky Chotai, Kyle D. Weaver, Reid C. Thompson, Lola B. Chambless, Rebecca A. Ihrie, Jonathan M. Irish
×Abstract
Innate and adaptive immune cells modulate the severity of autosomal dominant polycystic kidney disease (ADPKD), a common kidney disease with inadequate treatment options. ADPKD has parallels with cancer, in which immune checkpoint inhibitors have been shown to reactivate CD8+ T cells and slow tumor growth. We have previously shown that in PKD, CD8+ T cell loss worsens disease. This study used orthologous early-onset and adult-onset ADPKD models (Pkd1 p.R3277C) to evaluate the role of immune checkpoints in PKD. Flow cytometry of kidney cells showed increased levels of programmed cell death protein 1 (PD-1)/cytotoxic T lymphocyte associated protein 4 (CTLA-4) on T cells and programmed cell death ligand 1 (PD-L1)/CD80 on macrophages and epithelial cells in Pkd1RC/RC mice versus WT, paralleling disease severity. PD-L1/CD80 was also upregulated in ADPKD human cells and patient kidney tissue versus controls. Genetic PD-L1 loss or treatment with an anti–PD-1 antibody did not impact PKD severity in early-onset or adult-onset ADPKD models. However, treatment with anti–PD-1 plus anti–CTLA-4, blocking 2 immune checkpoints, improved PKD outcomes in adult-onset ADPKD mice; neither monotherapy altered PKD severity. Combination therapy resulted in increased kidney CD8+ T cell numbers/activation and decreased kidney regulatory T cell numbers correlative with PKD severity. Together, our data suggest that immune checkpoint activation is an important feature of and potential novel therapeutic target in ADPKD.
Authors
Emily K. Kleczko, Dustin T. Nguyen, Kenneth H. Marsh, Colin D. Bauer, Amy S. Li, Marie-Louise T. Monaghan, Michael D. Berger, Seth B. Furgeson, Berenice Y. Gitomer, Michel B. Chonchol, Eric T. Clambey, Kurt A. Zimmerman, Raphael A. Nemenoff, Katharina Hopp
×Abstract
Tumor vascular normalization prevents tumor cells from breaking through the basement membrane and entering the vasculature, thereby inhibiting metastasis initiation. In this study, we report that the antitumor peptide JP1 regulated mitochondrial metabolic reprogramming through AMPK/FOXO3a/UQCRC2 signaling, which improved the tumor microenvironment hypoxia. The oxygen-rich tumor microenvironment inhibited the secretion of IL-8 by tumor cells, thereby promoting tumor vascular normalization. The normalized vasculature resulted in mature and regular blood vessels, which made the tumor microenvironment form a benign feedback loop consisting of vascular normalization, sufficient perfusion, and an oxygen-rich microenvironment, prevented tumor cells from entering the vasculature, and inhibited metastasis initiation. Moreover, the combined therapy of JP1 and paclitaxel maintained a certain vascular density in the tumor and promoted tumor vascular normalization, increasing the delivery of oxygen and drugs and enhancing the antitumor effect. Collectively, our work highlights the antitumor peptide JP1 as an inhibitor of metastasis initiation and its mechanism of action.
Authors
Jiahua Cui, Zhen Che, Lu Zou, Dongyin Chen, Zhan Xie, Kun Ding, Huning Jiang, Aiping Li, Jianwei Zhou, Yongqian Shu
×Abstract
Inflammatory bowel disease (IBD) is a relapsing-remitting disorder characterized by chronic inflammation of the gastrointestinal (GI) tract. Anxiety symptoms are commonly observed in patients with IBD, but the mechanistic link between IBD and anxiety remains elusive. Here, we sought to characterize gut-to-brain signaling and brain circuitry responsible for the pathological expression of anxiety-like behaviors in male dextran sulfate sodium–induced (DSS-induced) experimental colitis mice. We found that DSS-treated mice displayed increased anxiety-like behaviors, which were prevented by bilateral GI vagal afferent ablation. The locus coeruleus (LC) is a relay center connecting the nucleus tractus solitarius to the basolateral amygdala (BLA) in controlling anxiety-like behaviors. Chemogenetic silencing of noradrenergic LC projections to the BLA reduced anxiety-like behaviors in DSS-treated mice. This work expands our understanding of the neural mechanisms by which IBD leads to comorbid anxiety and emphasizes a critical role of gastric vagal afferent signaling in gut-to-brain regulation of emotional states.
Authors
Chin-Hao Chen, Tsung-Chih Tsai, Yi-Jen Wu, Kuei-Sen Hsu
×Abstract
ˆCCL24 is a pro-fibrotic, pro-inflammatory chemokine expressed in several chronic fibrotic diseases. In the liver, CCL24 plays a role in fibrosis and inflammation, and blocking CCL24 led to reduced liver injury in experimental models. We studied the role of CCL24 in primary sclerosing cholangitis (PSC) and evaluated the potential therapeutic effect of blocking CCL24 in this disease. Multidrug resistance gene 2–knockout (Mdr2–/–) mice demonstrated CCL24 expression in liver macrophages and were used as a relevant experimental PSC model. CCL24-neutralizing monoclonal antibody, CM-101, significantly improved inflammation, fibrosis, and cholestasis-related markers in the biliary area. Moreover, using spatial transcriptomics, we observed reduced proliferation and senescence of cholangiocytes following CCL24 neutralization. Next, we demonstrated that CCL24 expression was elevated under pro-fibrotic conditions in primary human cholangiocytes and macrophages, and it induced proliferation of primary human hepatic stellate cells and cholangiocytes, which was attenuated following CCL24 inhibition. Correspondingly, CCL24 was found to be highly expressed in liver biopsies of patients with PSC. CCL24 serum levels correlated with Enhanced Liver Fibrosis score, most notably in patients with high alkaline phosphatase levels. These results suggest that blocking CCL24 may have a therapeutic effect in patients with PSC by reducing liver inflammation, fibrosis, and cholestasis.
Authors
Raanan Greenman, Michal Segal-Salto, Neta Barashi, Ophir Hay, Avi Katav, Omer Levi, Ilan Vaknin, Revital Aricha, Sarit Aharoni, Tom Snir, Inbal Mishalian, Devorah Olam, Johnny Amer, Ahmad Salhab, Rifaat Safadi, Yaakov Maor, Palak Trivedi, Christopher J. Weston, Francesca Saffioti, Andrew Hall, Massimo Pinzani, Douglas Thorburn, Amnon Peled, Adi Mor
×Abstract
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is caused by mutations in SACS gene encoding sacsin, a huge protein highly expressed in cerebellar Purkinje cells (PCs). Patients with ARSACS, as well as mouse models, display early degeneration of PCs, but the underlying mechanisms remain unexplored, with no available treatments. In this work, we demonstrated aberrant calcium (Ca2+) homeostasis and its impact on PC degeneration in ARSACS. Mechanistically, we found pathological elevation in Ca2+-evoked responses in Sacs–/– PCs as the result of defective mitochondria and ER trafficking to distal dendrites and strong downregulation of key Ca2+ buffer proteins. Alteration of cytoskeletal linkers, which we identified as specific sacsin interactors, likely account for faulty organellar trafficking in Sacs–/– cerebellum. Based on this pathogenetic cascade, we treated Sacs–/– mice with Ceftriaxone, a repurposed drug that exerts neuroprotection by limiting neuronal glutamatergic stimulation and, thus, Ca2+ fluxes into PCs. Ceftriaxone treatment significantly improved motor performances of Sacs–/– mice, at both pre- and postsymptomatic stages. We correlated this effect to restored Ca2+ homeostasis, which arrests PC degeneration and attenuates secondary neuroinflammation. These findings disclose key steps in ARSACS pathogenesis and support further optimization of Ceftriaxone in preclinical and clinical settings for the treatment of patients with ARSACS.
Authors
Andrea Del Bondio, Fabiana Longo, Daniele De Ritis, Erica Spirito, Paola Podini, Bernard Brais, Angela Bachi, Angelo Quattrini, Francesca Maltecca
×Abstract
Epigenetic aberrations, including posttranslational modifications of core histones, are major contributors to cancer. Here, we define the status of histone H2B monoubiquitylation (H2Bub1) in clear cell ovarian carcinoma (CCOC), low-grade serous carcinoma, and endometrioid carcinomas. We report that clear cell carcinomas exhibited profound loss, with nearly all cases showing low or negative H2Bub1 expression. Moreover, we found that H2Bub1 loss occurred in endometriosis and atypical endometriosis, which are established precursors to CCOCs. To examine whether dysregulation of a specific E3 ligase contributes to the loss of H2Bub1, we explored expression of ring finger protein 40 (RNF40), ARID1A, and UBR7 in the same case cohort. Loss of RNF40 was significantly and profoundly correlated with loss of H2Bub1. Using genome-wide DNA methylation profiles of 230 patients with CCOC, we identified hypermethylation of RNF40 in CCOC as a likely mechanism underlying the loss of H2Bub1. Finally, we demonstrated that H2Bub1 depletion promoted cell proliferation and clonogenicity in an endometriosis cell line. Collectively, our results indicate that H2Bub1 plays a tumor-suppressive role in CCOCs and that its loss contributes to disease progression.
Authors
Adam J. Ferrari, Priyanka Rawat, Hannah S. Rendulich, Akshaya V. Annapragada, Yasuto Kinose, Xiaoming Zhang, Kyle Devins, Anna Budina, Robert B. Scharpf, Marilyn A. Mitchell, Janos L. Tanyi, Mark A. Morgan, Lauren E. Schwartz, T. Rinda Soong, Victor E. Velculescu, Ronny Drapkin
×Abstract
Immune responses in people with multiple sclerosis (pwMS) receiving disease-modifying therapies (DMTs) have been of significant interest throughout the COVID-19 pandemic. Lymphocyte-targeting immunotherapies, including anti-CD20 treatments and sphingosine-1-phosphate receptor (S1PR) modulators, attenuate Ab responses after vaccination. Evaluation of cellular responses after vaccination, therefore, is of particular importance in these populations. In this study, we used flow cytometry to analyze CD4 and CD8 T cell functional responses to SARS-CoV-2 spike peptides in healthy control study participants and pwMS receiving 5 different DMTs. Although pwMS receiving rituximab and fingolimod therapies had low Ab responses after both 2 and 3 vaccine doses, T cell responses in pwMS taking rituximab were preserved after a third vaccination, even when an additional dose of rituximab was administered between vaccine doses 2 and 3. PwMS taking fingolimod had low detectable T cell responses in peripheral blood. CD4 and CD8 T cell responses to SARS-CoV-2 variants of concern Delta and Omicron were lower than to the ancestral Wuhan-Hu-1 variant. Our results indicate the importance of assessing both cellular and humoral responses after vaccination and suggest that, even in the absence of robust Ab responses, vaccination can generate immune responses in pwMS.
Authors
Asia-Sophia Wolf, Anthony Ravussin, Marton König, Mathias H. Øverås, Guri Solum, Ingrid Fadum Kjønstad, Adity Chopra, Trygve Holmøy, Hanne F. Harbo, Silje Watterdal Syversen, Kristin Kaasen Jørgensen, Einar August Høgestøl, Jon Torgils Vaage, Elisabeth G. Celius, Fridtjof Lund-Johansen, Ludvig A. Munthe, Gro Owren Nygaard, Siri Mjaaland
×Abstract
Synaptic plasticity impairment plays a critical role in the pathogenesis of Alzheimer’s disease (AD), and emerging evidence has shown that microRNAs (miRs) are alternative biomarkers and therapeutic targets for synaptic dysfunctions in AD. In this study, we found that the level of miR-431 was downregulated in the plasma of patients with amnestic mild cognitive impairment and AD. In addition, it was decreased in the hippocampus and plasma of APPswe/PS1dE9 (APP/PS1) mice. Lentivirus-mediated miR-431 overexpression in the hippocampus CA1 ameliorated synaptic plasticity and memory deficits of APP/PS1 mice, while it did not affect amyloid-β levels. Smad4 was identified as a target of miR-431, and Smad4 knockdown modulated the expression of synaptic proteins, including SAP102, and protected against synaptic plasticity and memory dysfunctions in APP/PS1 mice. Furthermore, Smad4 overexpression reversed the protective effects of miR-431, indicating that miR-431 attenuated synaptic impairment at least partially by Smad4 inhibition. Thus, these results indicated that miR-431/Smad4 might be a potential therapeutic target for AD treatment.
Authors
Jianwei Ge, Zhiwei Xue, Shu Shu, Linjie Yu, Ruomeng Qin, Wenyuan Tao, Pinyi Liu, Xiaohong Dong, Zhen Lan, Xinyu Bao, Lei Ye, Yun Xu, Xiaolei Zhu
×Abstract
Cyclic GMP-AMP synthase (cGAS) is a DNA sensor and responsible for inducing an antitumor immune response. Recent studies reveal that cGAS is frequently inhibited in cancer, and therapeutic targets to promote antitumor cGAS function remain elusive. SRC is a proto-oncogene tyrosine kinase and is expressed at elevated levels in numerous cancers. Here, we demonstrate that SRC expression in primary and metastatic bladder cancer negatively correlates with innate immune gene expression and immune cell infiltration. We determine that SRC restricts cGAS signaling in human cell lines through SRC small molecule inhibitors, depletion, and overexpression. cGAS and SRC interact in cells and in vitro, while SRC directly inhibits cGAS enzymatic activity and DNA binding in a kinase-dependent manner. SRC phosphorylates cGAS, and inhibition of cGAS Y248 phosphorylation partially reduces SRC inhibition. Collectively, our study demonstrates that cGAS antitumor signaling is hindered by the proto-oncogene SRC and describes how cancer-associated proteins can regulate the innate immune system.
Authors
William Dunker, Shivam A. Zaver, Jose Mario Bello Pineda, Cameron J. Howard, Robert K. Bradley, Joshua J. Woodward
×Abstract
The omentum contains immune cell structures called milky spots that are niches for transcoelomic metastasis. It is difficult to remove the omentum completely, and there are no effective strategies to minimize the risk of colonization of preserved omental tissues by cancer cells that circulate in the peritoneal fluid. Normal saline is commonly administered into the peritoneal cavity for diagnostic and intraoperative lavage. Here we show that normal saline, when administered into the peritoneal cavity of mice, is prominently absorbed by the omentum, exfoliates its mesothelium, and induces expression of CX3CL1, the ligand for CX3CR1, within and surrounding the omental vasculature. Studies using CX3CR1-competent and CX3CR1-deficient mice showed that the predominant response in the omentum following saline administration is an accumulation of CX3CR1+ monocytes/macrophages that expand milky spots and promote neoangiogenesis within these niches. Moreover, saline administration promoted the implantation of cancer cells of ovarian and colorectal origin onto the omentum. By contrast, these deleterious effects were not observed following i.p. administration of lactated Ringer’s solution. Our findings suggest that normal saline stimulates the receptivity of the omentum for cancer cells and that the risk of colonization can be minimized by using a biocompatible crystalloid for lavage procedures.
Authors
Hironari Akasaka, WonJae Lee, Song Yi Ko, Ernst Lengyel, Honami Naora
×Abstract
The combination of radiation therapy (RT) and immunotherapy has emerged as a promising treatment option in oncology. Historically, x-ray radiation (XRT) has been the most commonly used form of RT. However, proton beam therapy (PBT) is gaining recognition as a viable alternative, as it has been shown to produce similar outcomes to XRT while minimizing off-target effects. The effects of PBT on the antitumor immune response have only just begun to be described, and to our knowledge no studies to date have examined the effect of PBT as part of a combinatorial immunoradiotherapeutic strategy. Here, using a 2-tumor model of lung cancer in mice, we show that PBT in tandem with an anti-PD1 antibody substantially reduced growth in both irradiated and unirradiated tumors. This was accompanied by robust activation of the immune response, as evidenced by whole-tumor and single-cell RNA sequencing showing upregulation of a multitude of immune-related transcripts. This response was further significantly enhanced by the injection of the tumor to be irradiated with NBTXR3 nanoparticles. Tumors of mice treated with the triple combination exhibited increased infiltration and activation of cytotoxic immune cells. This triple combination eradicated both tumors in 37.5% of the treated mice and showed robust long-term immunity to cancer.
Authors
Yun Hu, Sébastien Paris, Narayan Sahoo, Genevieve Bertolet, Qi Wang, Qianxia Wang, Hampartsoum B. Barsoumian, Jordan Da Silva, Ailing Huang, Denaha J. Doss, David P. Pollock, Ethan Hsu, Nanez Selene, Claudia S. Kettlun Leyton, Tiffany A. Voss, Fatemeh Masrorpour, Shonik Ganjoo, Carola Leuschner, Jordan T. Pietz, Nahum Puebla-Osorio, Saumil Gandhi, Quynh-Nhu Nguyen, Jing Wang, Maria Angelica Cortez, James W. Welsh
×Abstract
Hypochondroplasia (HCH) is a mild dwarfism caused by missense mutations in fibroblast growth factor receptor 3 (FGFR3), with the majority of cases resulting from a heterozygous p.Asn540Lys gain-of-function mutation. Here, we report the generation and characterization of the first mouse model (Fgfr3Asn534Lys/+) of HCH to our knowledge. Fgfr3Asn534Lys/+ mice exhibited progressive dwarfism and impairment of the synchondroses of the cranial base, resulting in defective formation of the foramen magnum. The appendicular and axial skeletons were both severely affected and we demonstrated an important role of FGFR3 in regulation of cortical and trabecular bone structure. Trabecular bone mineral density (BMD) of long bones and vertebral bodies was decreased, but cortical BMD increased with age in both tibiae and femurs. These results demonstrate that bones in Fgfr3Asn534Lys/+ mice, due to FGFR3 activation, exhibit some characteristics of osteoporosis. The present findings emphasize the detrimental effect of gain-of-function mutations in the Fgfr3 gene on long bone modeling during both developmental and aging processes, with potential implications for the management of elderly patients with hypochondroplasia and osteoporosis.
Authors
Léa Loisay, Davide Komla-Ebri, Anne Morice, Yann Heuzé, Camille Viaut, Amélie de La Seiglière, Nabil Kaci, Danny Chan, Audrey Lamouroux, Geneviève Baujat, J.H. Duncan Bassett, Graham R. Williams, Laurence Legeai-Mallet
×Abstract
Diabetic retinopathy (DR) is a leading cause of blindness in working-age adults and remains an important public health issue worldwide. Here we demonstrate that the expression of stimulator of interferon genes (STING) is increased in patients with DR and animal models of diabetic eye disease. STING has been previously shown to regulate cell senescence and inflammation, key contributors to the development and progression of DR. To investigate the mechanism whereby STING contributes to the pathogenesis of DR, diabetes was induced in STING-KO mice and STINGGT (loss-of-function mutation) mice, and molecular alterations and pathological changes in the retina were characterized. We report that retinal endothelial cell senescence, inflammation, and capillary degeneration were all inhibited in STING-KO diabetic mice; these observations were independently corroborated in STINGGT mice. These protective effects resulted from the reduction in TBK1, IRF3, and NF-κB phosphorylation in the absence of STING. Collectively, our results suggest that targeting STING may be an effective therapy for the early prevention and treatment of DR.
Authors
Haitao Liu, Sayan Ghosh, Tanuja Vaidya, Sridhar Bammidi, Chao Huang, Peng Shang, Archana Padmanabhan Nair, Olivia Chowdhury, Nadezda A. Stepicheva, Anastasia Strizhakova, Stacey Hose, Nikolaos Mitrousis, Santosh Gopikrishna Gadde, Thirumalesh MB, Pamela Strassburger, Gabriella Widmer, Eleonora M. Lad, Patrice E. Fort, José-Alain Sahel, J. Samuel Zigler Jr., Swaminathan Sethu, Peter D. Westenskow, Alan D. Proia, Akrit Sodhi, Arkasubhra Ghosh, Derrick Feenstra, Debasish Sinha
×Abstract
BACKGROUND There is considerable heterogeneity in the effect of weight loss on metabolic function in people with obesity.METHODS We evaluated muscle and liver insulin sensitivity, body composition, and circulating factors associated with insulin action before and after approximately 20% weight loss in women identified as “Responders” (n = 11) or “Non-responders” (n = 11), defined as the top (>75% increase) and bottom (<5% increase) quartiles of the weight loss–induced increase in glucose disposal rate (GDR) during a hyperinsulinemic-euglycemic clamp procedure, among 43 women with obesity (BMI: 44.1 ± 7.9 kg/m2).RESULTS At baseline, GDR, which provides an index of muscle insulin sensitivity, and the hepatic insulin sensitivity index were more than 50% lower in Responders than Non-responders, but both increased much more after weight loss in Responders than Non-responders, which eliminated the differences between groups. Weight loss also caused greater decreases in intrahepatic triglyceride content and plasma adiponectin and PAI-1 concentrations in Responders than Non-responders and greater insulin-mediated suppression of plasma free fatty acids, branched-chain amino acids, and C3/C5 acylcarnitines in Non-responders than Responders, so that differences between groups at baseline were no longer present after weight loss. The effect of weight loss on total body fat mass, intra-abdominal adipose tissue volume, adipocyte size, and circulating inflammatory markers were not different between groups.CONCLUSION The results from our study demonstrate that the heterogeneity in the effects of marked weight loss on muscle and hepatic insulin sensitivity in people with obesity is determined by baseline insulin action, and reaches a ceiling when “normal” insulin action is achieved.TRIAL REGISTRATION NCT00981500, NCT01299519, NCT02207777.FUNDING NIH grants P30 DK056341, P30 DK020579, P30 DK052574, UL1 TR002345, and T32 HL13035, the American Diabetes Association (1-18-ICTS-119), the Longer Life Foundation (2019-011), and the Atkins Philanthropic Trust.
Authors
Bettina Mittendorfer, Brandon D. Kayser, Mihoko Yoshino, Jun Yoshino, Jeramie D. Watrous, Mohit Jain, J. Christopher Eagon, Bruce W. Patterson, Samuel Klein
×Abstract
BACKGROUND Weight-loss diets often target dietary fat or carbohydrates, macronutrients that are sensed via distinct gut-brain pathways and differentially affect peripheral hormones and metabolism. However, the effects of such diet changes on the human brain are unclear. METHODS We investigated whether selective isocaloric reductions in dietary fat or carbohydrates altered dopamine D2/3 receptor binding potential (D2BP) and neural activity in brain-reward regions in response to visual food cues in 17 inpatient adults with obesity as compared with a eucaloric baseline diet using a randomized crossover design. RESULTS On the fifth day of dietary fat restriction, but not carbohydrate restriction, both D2BP and neural activity to food cues were decreased in brain-reward regions. After the reduced-fat diet, ad libitum intake shifted toward foods high in both fat and carbohydrates. CONCLUSION These results suggest that dietary fat restriction increases tonic dopamine in brain-reward regions and affects food choice in ways that may hamper diet adherence. TRIAL REGISTRATION ClinicalTrials.gov NCT00846040 FUNDING. NIDDK 1ZIADK013037.
Authors
Valerie L. Darcey, Juen Guo, Amber B. Courville, Isabelle Gallagher, Jason A. Avery, W. Kyle Simmons, John E. Ingeholm, Peter Herscovitch, Alex Martin, Kevin D. Hall
×Abstract
Fasting is associated with increased susceptibility to hypoglycemia in people with type 1 diabetes, thereby making it a significant health risk. To date, the relationship between fasting and insulin-induced hypoglycemia has not been well characterized, so our objective was to determine whether insulin-independent factors, such as counterregulatory hormone responses, are adversely impacted by fasting in healthy control individuals. Counterregulatory responses to insulin-induced hypoglycemia were measured in 12 healthy people during 2 metabolic studies. During one study, participants ate breakfast and lunch, after which they underwent a 2-hour bout of insulin-induced hypoglycemia (FED). During the other study, participants remained fasted prior to hypoglycemia (FAST). As expected, hepatic glycogen concentrations were lower in FAST, and associated with diminished peak glucagon levels and reduced endogenous glucose production (EGP) during hypoglycemia. Accompanying lower EGP in FAST was a reduction in peripheral glucose utilization, and a resultant reduction in the amount of exogenous glucose required to maintain glycemia. These data suggest that whereas a fasting-induced lowering of glucose utilization could potentially delay the onset of insulin-induced hypoglycemia, subsequent reductions in glucagon levels and EGP are likely to encumber recovery from it. As a result of this diminished metabolic flexibility in response to fasting, susceptibility to hypoglycemia could be enhanced in patients with type 1 diabetes under similar conditions.
Authors
Shana O. Warner, Yufei Dai, Nicole Sheanon, Michael V. Yao, Rebecca L. Cason, Shahriar Arbabi, Shailendra B. Patel, Diana Lindquist, Jason J. Winnick
×Abstract
Defects in endoplasmic reticulum (ER) proteostasis have been linked to diseases in multiple organ systems. Here we examined the impact of perturbation of ER proteostasis in mice bearing thyrocyte-specific knockout of either HRD1 (to disable ER-associated protein degradation [ERAD]) or ATG7 (to disable autophagy) in the absence or presence of heterozygous expression of misfolded mutant thyroglobulin (the most highly expressed thyroid gene product, synthesized in the ER). Misfolding-inducing thyroglobulin mutations are common in humans but are said to yield only autosomal-recessive disease — perhaps because misfolded thyroglobulin protein might undergo disposal by ERAD or ER macroautophagy. We find that as single defects, neither ERAD, nor autophagy, nor heterozygous thyroglobulin misfolding altered circulating thyroxine levels, and neither defective ERAD nor defective autophagy caused any gross morphological change in an otherwise WT thyroid gland. However, heterozygous expression of misfolded thyroglobulin itself triggered significant ER stress and individual thyrocyte death while maintaining integrity of the surrounding thyroid epithelium. In this context, deficiency of ERAD (but not autophagy) resulted in patchy whole-follicle death with follicular collapse and degeneration, accompanied by infiltration of bone marrow–derived macrophages. Perturbation of thyrocyte ER proteostasis is thus a risk factor for both cell death and follicular demise.
Authors
Xiaohan Zhang, Crystal Young, Xiao-Hui Liao, Samuel Refetoff, Mauricio Torres, Yaron Tomer, Mihaela Stefan-Lifshitz, Hao Zhang, Dennis Larkin, Deyu Fang, Ling Qi, Peter Arvan
×Abstract
Respiration can positively influence cerebrospinal fluid (CSF) flow in the brain, yet its effects on central nervous system (CNS) fluid homeostasis, including waste clearance function via glymphatic and meningeal lymphatic systems, remain unclear. Here, we investigated the effect of supporting respiratory function via continuous positive airway pressure (CPAP) on glymphatic-lymphatic function in spontaneously breathing anesthetized rodents. To do this, we used a systems approach combining engineering, MRI, computational fluid dynamics analysis, and physiological testing. We first designed a nasal CPAP device for use in the rat and demonstrated that it functioned similarly to clinical devices, as evidenced by its ability to open the upper airway, augment end-expiratory lung volume, and improve arterial oxygenation. We further showed that CPAP increased CSF flow speed at the skull base and augmented glymphatic transport regionally. The CPAP-induced augmented CSF flow speed was associated with an increase in intracranial pressure (ICP), including the ICP waveform pulse amplitude. We suggest that the augmented pulse amplitude with CPAP underlies the increase in CSF bulk flow and glymphatic transport. Our results provide insights into the functional crosstalk at the pulmonary-CSF interface and suggest that CPAP might have therapeutic benefit for sustaining glymphatic-lymphatic function.
Authors
Burhan Ozturk, Sunil Koundal, Ehab Al Bizri, Xinan Chen, Zachary Gursky, Feng Dai, Andrew Lim, Paul Heerdt, Jonathan Kipnis, Allen Tannenbaum, Hedok Lee, Helene Benveniste
×Abstract
Background The effects of diet-induced weight loss (WL) and WL after Roux-en-Y gastric bypass (RYGB) surgery on β cell function (BCF) are unclear because of conflicting results from different studies, presumably because of differences in the methods used to measure BCF, the amount of WL between treatment groups, and baseline BCF. We evaluated the effect of WL after RYGB surgery or reduced energy intake alone on BCF in people with obesity with and without type 2 diabetes.Methods BCF (insulin secretion in relationship to plasma glucose) was assessed before and after glucose or mixed-meal ingestion before and after (a) progressive amounts (6%, 11%, 16%) of WL induced by a low-calorie diet (LCD) in people with obesity without diabetes, (b) ~20% WL after RYGB surgery or laparoscopic adjustable gastric banding (LAGB) in people with obesity without diabetes, and (c) ~20% WL after RYGB surgery or LCD alone in people with obesity and diabetes.Results Diet-induced progressive WL in people without diabetes progressively decreased BCF. Marked WL after LAGB or RYGB in people without diabetes did not alter BCF. Marked WL after LCD or RYGB in people with diabetes markedly increased BCF, without a difference between groups.Conclusion Marked WL increases BCF in people with obesity and diabetes but not in people with obesity without diabetes. The effect of RYGB-induced WL on BCF is not different from the effect of matched WL after LAGB or LCD alone.trial registration NCT00981500, NCT02207777, NCT01299519.Funding NIH grants R01 DK037948, P30 DK056341, P30 DK020579, UL1 TR002345.
Authors
Bettina Mittendorfer, Bruce W. Patterson, Faidon Magkos, Mihoko Yoshino, David P. Bradley, J. Christopher Eagon, Samuel Klein
×Abstract
Growing evidence indicates that the glucagon-like peptide-1 (GLP-1) system is involved in the neurobiology of addictive behaviors, and GLP-1 analogues may be used for the treatment of alcohol use disorder (AUD). Here, we examined the effects of semaglutide, a long-acting GLP-1 analogue, on biobehavioral correlates of alcohol use in rodents. A drinking-in-the-dark procedure was used to test the effects of semaglutide on binge-like drinking in male and female mice. We also tested the effects of semaglutide on binge-like and dependence-induced alcohol drinking in male and female rats, as well as acute effects of semaglutide on spontaneous inhibitory postsynaptic currents (sIPSCs) from central amygdala (CeA) and infralimbic cortex (ILC) neurons. Semaglutide dose-dependently reduced binge-like alcohol drinking in mice; a similar effect was observed on the intake of other caloric/noncaloric solutions. Semaglutide also reduced binge-like and dependence-induced alcohol drinking in rats. Semaglutide increased sIPSC frequency in CeA and ILC neurons from alcohol-naive rats, suggesting enhanced GABA release, but had no overall effect on GABA transmission in alcohol-dependent rats. In conclusion, the GLP-1 analogue semaglutide decreased alcohol intake across different drinking models and species and modulated central GABA neurotransmission, providing support for clinical testing of semaglutide as a potentially novel pharmacotherapy for AUD.
Authors
Vicky Chuong, Mehdi Farokhnia, Sophia Khom, Claire L. Pince, Sophie K. Elvig, Roman Vlkolinsky, Renata C.N. Marchette, George F. Koob, Marisa Roberto, Leandro F. Vendruscolo, Lorenzo Leggio
