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Abstract
Vision loss in age-related macular degeneration (AMD) stems from disruption of photoreceptor cells in the macula, the central retinal area required for high-acuity vision. Mice and rats have no macula, but surgical insertion of a subretinal implant can induce localized photoreceptor degeneration due to chronic separation from retinal pigment epithelium, simulating a key aspect of AMD. We find that the implant-induced loss of photoreceptors in rat retina leads to local changes in the physiology of downstream retinal ganglion cells (RGCs), similar to changes in RGCs of rodent models of retinitis pigmentosa (RP), an inherited disease causing retina-wide photoreceptor degeneration. The local implant-induced changes in RGCs include enhanced intrinsic excitability leading to accelerated spontaneous firing, increased membrane permeability to fluorescent dyes, and enhanced photosensitization by azobenzene photoswitches. The local physiological changes are correlated with an increase in Retinoic Acid Receptor (RAR)-induced gene transcription, the key process underlying retinal remodeling in mouse models of RP. Hence the loss of photoreceptors, whether by local physical perturbation or by inherited mutation, leads to a stereotypical set of pathophysiological consequences in RGCs. These findings implicate RAR as a possible common therapeutic target for reversing the signal-corrupting effects of retinal remodeling in both RP and AMD.
Authors
Bristol Denlinger, Zachary Helft, Michael Telias, Henri Lorach, Daniel Palanker, Richard H. Kramer
Abstract
Duchenne muscular dystrophy (DMD) is a devastating genetic muscle disease resulting in progressive muscle degeneration and wasting. Glucocorticoids, specifically prednisone/prednisolone and deflazacort, are commonly used by DMD patients. Emerging DMD therapeutics include those targeting the muscle wasting factor, myostatin (Mstn). The aim of this study was to investigate how chronic glucocorticoid treatment impacts the efficacy of Mstn inhibition in the D2.mdx mouse model of DMD. We report that chronic treatment of dystrophic mice with prednisolone (Pred) causes significant muscle wasting, entailing both activation of the ubiquitin-proteasome degradation pathway and inhibition of muscle protein synthesis. Combining Pred with Mstn inhibition, using a modified Mstn propeptide (dnMstn), completely abrogates the muscle hypertrophic effects of Mstn inhibition independent of Mstn expression or SMAD3 activation. Transcriptomic analysis identified that combining Pred with dnMstn treatment affects gene expression profiles associated with inflammation, metabolism, and fibrosis. Additionally, we demonstrate that Pred-induced muscle atrophy is not prevented by Mstn ablation. Therefore, glucocorticoids interfere with potential muscle mass benefits associated with targeting Mstn, and the ramifications of glucocorticoid use should be a consideration during clinical trial design for DMD therapeutics. These results have significant implications for past and future Mstn inhibition trials in DMD.
Authors
David W. Hammers, Cora C. Hart, Andreas Patsalos, Michael K. Matheny, Lillian A. Wright, Laszlo Nagy, H. Lee Sweeney
LXRs regulate features of age-related macular degeneration and may be a potential therapeutic target
Abstract
Effective treatments and animal models for the most prevalent neurodegenerative form of blindness in the elderly, called age-related macular degeneration (AMD), are lacking. Genome-wide association studies have identified lipid metabolism and inflammation as AMD-associated pathogenic pathways. Given liver x receptors, encoded by NR1H3 and NR1H2, are master regulators of these pathways, herein we investigated the role of LXR in human and mouse eyes as a function of age and disease, and tested the therapeutic potential of targeting LXR. We identified immunopositive LXR fragments in human extracellular early dry AMD lesions and a decrease in LXR expression within the retinal pigment epithelium (RPE) as a function of age. Aged mice, lacking LXR presented with isoform dependent ocular pathologies. Specifically, loss of the Nr1h3 isoform results in pathobiologies aligned with AMD, supported by compromised visual function, accumulation of native and oxidized lipids in the outer retina, and upregulation of ocular inflammatory cytokines, while absence of Nr1h2 is associated with ocular lipoidal degeneration. Therapeutically, LXR activation, ameliorated lipid accumulation and oxidant-induced injury in RPE cells in vitro, and decreased ocular inflammatory markers and lipid deposition in a mouse model, in vivo, providing translational support for pursuing LXR-active pharmaceuticals as potential therapies for dry AMD.
Authors
Mayur Choudhary, Ebraheim N. Ismail, Pei-Li Yao, Faryan Tayyari, Roxana A. Radu, Steven Nusinowitz, Michael E. Boulton, Rajendra S. Apte, Jeffrey W. Ruberti, James T. Handa, Peter Tontonoz, Goldis Malek
Abstract
High-density lipoproteins (HDL) contain hundreds of lipid species and proteins and exert many potentially vasoprotective and anti-diabetogenic activities on cells. To resolve structure-function-disease relationships of HDL we characterized HDL of 51 healthy subjects and 98 patients with diabetes (T2DM), coronary heart disease (CHD), or both for protein and lipid composition as well as functionality in five cell types. The integration of 40 clinical characteristics, 34 NMR features, 182 proteins, 227 lipid species, and 12 functional read-outs by high-dimensional statistical modelling revealed first that CHD and T2DM are associated with different changes of HDL in size distribution, protein and lipid composition as well as function. Second, different cellular functions of HDL are weakly correlated with each other and determined by different structural components. Cholesterol efflux capacity was no proxy of other functions. Third, three novel determinants of HDL function were identified and validated by the use of artificially reconstituted HDL, namely the sphingadienine-based sphingomyelin SM 42:3 and glycosylphosphatidylinositol-phospholipase D1 for the ability of HDL to inhibit starvation induced apoptosis of human aortic endothelial cells and apolipoprotein F for the ability of HDL to promote maximal respiration of brown adipocytes.
Authors
Mathias Cardner, Mustafa Yalcinkaya, Sandra Goetze, Edlira Luca, Miroslav Balaz, Monika Hunjadi, Johannes Hartung, Andrej Shemet, Nicolle Kraenkel, Silvija Radosavljevic, Michaela Keel, Alaa Othman, Gergely Karsai, Thorsten Hornemann, Manfred Claassen, Gerhard Liebisch, Erick Carreira, Andreas Ritsch, Ulf Landmesser, Jan Krützfeldt, Christian Wolfrum, Bernd Wollscheid, Niko Beerenwinkel, Lucia Rohrer, Arnold von Eckardstein
Abstract
Pancreatic ductal adenocarcinoma (PDAC) has dismal five-year survival (<9%). We hypothesize that exposure of tumors to conventional therapies may preferentially modulate immune biomarkers in the tumor microenvironment in PDAC. PDAC patients who underwent upfront surgical resection or who received neoadjuvant FOLFIRINOX with or without neoadjuvant radiotherapy followed by surgical resection were selected for study. Total expression of immunologically relevant transcripts and spatially resolved expression of immunologically relevant proteins was quantitated using multiplexed methods (Nanostring nCounter and GeoMX platforms). This analysis identified numerous differentially expressed transcripts associated with the type of neoadjuvant therapy received. Moreover, we identified significant alterations in the expression and/or spatial distribution of immunologically relevant proteins in different regions (tumor cell rich, immune cell rich, stromal cell rich) of the TME. These data provide insight into the immunological effects of clinically relevant neoadjuvant therapy for resectable/borderline-resectable PDAC, by describing significant differences in the expression of key immunologic biomarkers within the PDAC microenvironment that were associated with the type of treatment patients received prior to surgical resection. This represents a comprehensive analysis of numerous biomarkers conducted on the PDAC microenvironment. This work may guide strategic new combination therapies for pancreatic cancer.
Authors
Matthew R. Farren, Layal Sayegh, Michael Brandon Ware, Hsiao-Rong Chen, Jingjing Gong, Yan Liang, Alyssa Krasinskas, Shishir K. Maithel, Mohammad Zaidi, Juan M. Sarmiento, David Kooby, Pretesh Patel, Bassel El-Rayes, Walid Shaib, Gregory B. Lesinski
Abstract
Background: Inflammation is implicated in many aging-related disorders. In animal models, menopause leads to increased gut permeability and inflammation. Our primary objective was to determine if gut permeability increases during the menopause transition (MT) in women. Our exploratory objectives were to examine whether greater gut permeability is associated with more inflammation and lower bone mineral density (BMD).Methods: We included 65 women from the Study of Women’s Health Across the Nation. Key measures were markers of gut permeability (gut barrier dysfunction [fatty acid binding protein 2 [FABP2]) and immune activation secondary to gut microbial translocation (lipopolysaccharide binding protein [LBP], soluble CD14 [sCD14]); inflammation (high-sensitivity CRP); and lumbar spine (LS) or total hip (TH) BMD. Results: In our primary analysis, FABP2, LBP, and sCD14 increased by 22.8% (P = 0.001), 3.7% (P = 0.05), and 8.9% (P = 0.0002), respectively from pre- to postmenopause. In exploratory, repeated measures, mixed-effects linear regression (adjusted for age at the premenopausal visit, body mass index, race/ethnicity, and study site), greater gut permeability was associated with greater inflammation, and lower LS and TH BMD. Conclusions: Gut permeability increases during the MT. Greater gut permeability is associated with more inflammation and lower BMD. Future studies should examine the longitudinal associations of gut permeability, inflammation, and BMD.Funding: NIH, Department of Health and Human Services, through the National Institute on Aging, National Institute of Nursing Research, and NIH Office of Research on Women’s Health (U01NR004061, U01AG012505, U01AG012535, U01AG012531, U01AG012539, U01AG012546, U01AG012553, U01AG012554, U01AG012495).
Authors
Albert Shieh, Marta Epeldegui, Arun S Karlamangla, Gail A. Greendale
Abstract
Small molecule inhibitors of Dual Specificity, Tyrosine Phosphorylation-Regulated Kinase 1A (DYRK1A), including harmine and others, are able to drive human beta cell regeneration. While DYRK1A is certainly a target of this class, whether it is the only, or the most important target, is uncertain. Here, we employ a combined pharmacologic and genetic approach to refine the potential mitogenic targets of the DYRK1A inhibitor family in human islets. A combination of human beta cell RNAseq, DYRK1A inhibitor kinome screens, pharmacologic inhibitors, and targeted silencing of candidate genes confirms that DYRK1A is a central target. Surprisingly, however, DYRK1B also proves to be an important target: silencing DYRK1A results in an increase in DYRK1B; simultaneous silencing of both DYRK1A and DYRK1B yields greater beta cell proliferation than silencing either individually. Importantly, other potential kinases, such as the CLK and the GSK3 families, are excluded as important harmine targets. Finally, we describe adenoviruses that are able to silence up to seven targets simultaneously. Collectively, we report that inhibition of both DYRK1A and DYRK1B is required for induction of maximal rates of human beta cell proliferation, and provide clarity for future efforts at structure-based drug design for human beta cell regenerative drugs.
Authors
Courtney Ackeifi, Ethan Swartz, Kunal Kumar, Hongtao Liu, Suebsuwong Chalada, Esra Karakose, Donald K. Scott, Adolfo Garcia-Ocaña, Roberto Sanchez, Robert J. DeVita, Andrew F. Stewart, Peng Wang
Abstract
Subpial demyelination is a specific hallmark of multiple sclerosis (MS) and a correlate of disease progression. Although the mechanism(s) that mediate pathogenesis in the subpial compartment remain unclear, it has been speculated that inflammation in the overlying meninges may be associated with subpial injury. Here we show that adoptive transfer of proteolipid protein-primed Th17 cells into SJL/J recipient mice induces subpial demyelination associated with microglial/macrophage activation, disruption of the glial limitans and evidence of an oxidative stress response. This pathology was topologically associated with foci of immune cells in the meninges and occurred in the absence of measurable anti-MOG IgM or IgG antibodies. To test the role of brain-infiltrating leukocytes on subpial injury, we modulated sphingosine 1-phosphate (S1P) receptor1,5 activity with BAF312 (siponimod) treatment. Administration of BAF312, even after adoptively transferred T cells had entered the brain, significantly ameliorated clinical EAE and diminished subpial pathology, concomitant with a selective reduction in the capacity of transferred T cells to make Th17 cytokines. We conclude that sustained subpial cortical injury is associated with the capacity for brain-resident T cells to produce Th17 cytokines, and this pathological process occurs in an S1P receptor1,5-dependent manner.
Authors
Lesley A. Ward, Dennis S.W. Lee, Anshu Sharma, Angela Wang, Ikbel Naouar, Xianjie I. Ma, Natalia Pikor, Barbara Nuesslein-Hildesheim, Valeria Ramaglia, Jennifer L. Gommerman
Abstract
BACKGROUND We hypothesized that obesity-associated hepato-steatosis served as a pathophysiologic chemical depot for fat-soluble vitamins and altered normal physiology. Using α-tocopherol (vitamin E) as a model vitamin, pharmacokinetics and kinetics principles were utilized to determine whether excess liver fat sequestered α-tocopherol in women with obesity-associated hepato-steatosis vs healthy controls. METHODS Custom-synthesized deuterated α-tocopherols (d3- and d6-α-tocopherols) were administered to hospitalized healthy women and women with hepato-steatosis under IND guidelines. Serial samples obtained over 72 hours were analyzed by LC/MS. Fluorescent-labelled α-tocopherol was custom-synthesized for cell studies. RESULTS In healthy subjects, 85% of intravenous d6-α-tocopherol disappeared from the circulation within 20 minutes but reappeared within minutes and peaked at 6-8 hours. d3- and d6-α-Tocopherols localized to lipoproteins. Lipoprotein redistribution occurred only in vivo within 1h, indicating a key role of liver in rapid uptake and re-release into the circulation. Compared to healthy subjects, subjects with hepato-steatosis had similar d6-α-tocopherol entry rates into liver, but reduced initial release rates (p<0.001). Similarly, pharmacokinetics parameters of AUC and Maximum Concentration (Cmax) were reduced (AUC0-8 ,p<0.01;Cmax p<0.02) in hepato-steatosis subjects, indicating reduced hepatic d6-α-tocopherol output. Reduced kinetics and pharmacokinetics parameters (AUC and Cmax) in hepato-steatosis subjects who received 2 mg were mirrored by similar reductions in healthy subjects when comparing 5 and 2 mg doses. In vitro, fluorescent-labelled α-tocopherol localized specifically to lipid in fat-loaded hepatocytes, indicating sequestration. CONCLUSIONS The unique role of the liver in vitamin E physiology is dysregulated by excess liver fat. Obesity-associated hepato-steatosis may produce unrecognized hepatic vitamin E sequestration, which might subsequently drive liver disease. Our findings raise the possibility that hepato-steatosis may similarly alter hepatic physiology of other fat-soluble vitamins.
Authors
Pierre-Christian Violet, Ifechukwude C. Ebenuwa, Yu Wang, Mahtab Niyyati, Sebastian J. Padayatty, Brian Head, Kenneth Wilkins, Stacey Chung, Varsha Thakur, Lynn Ulatowski, Jeffrey Atkinson, Mikel Ghelfi, Sheila Smith, Hongbin Tu, Gerd Bobe, Chia-Ying Liu, David W. Herion, Robert D. Shamburek, Danny Manor, Maret G. Traber, Mark Levine
Abstract
Overexpression and long terminal repeat (LTR) polymorphism of the HRES-1/Rab4 human endogenous retrovirus locus have been associated with T-cell activation and disease manifestations in systemic lupus erythematosus (SLE). Although genomic DNA methylation is overall diminished in SLE, its role in HRES-1/Rab4 expression is unknown. Therefore, we determined how lupus-associated polymorphic rs451401 alleles of the LTR regulate transcription from the HRES-1/Rab4 promoter and thus impact T-cell activation. The results show that cytosine-119 is hypermethylated while cytosine-51 of the promoter and the LTR-enhancer are hypomethylated in SLE. Pharmacological or genetic inactivation of DNA-methyltransferase-1 augmented the expression of HRES-1/Rab4. The minimal promoter was selectively recognized by metabolic stress sensor NRF1 when cytosine-119 but not cytosine-51 was methylated, and NRF1 stimulated HRES-1/Rab4 expression in human T cells. In turn, IRF2 and PSIP1 bound to the LTR-enhancer and exerted control over HRES-1/Rab4 expression in rs451401-genotype and methylation-dependent manners. The LTR-enhancer conferred markedly greater expression of HRES-1/Rab4 in subjects with rs451401CC over rs451401GG alleles that in turn promoted mechanistic target of rapamycin (mTOR) activation upon T-cell receptor stimulation. HRES-1/Rab4 alone robustly activated mTOR in human T cells. These findings identify HRES-1/Rab4 as a methylation and rs451401 allele-dependent transducer of environmental stress and controller of T-cell activation.
Authors
Aparna Godavarthy, Ryan Kelly, John Jimah, Miguel Beckford, Tiffany Caza, David Fernandez, Nick Huang, Manuel Duarte, Joshua Lewis, Hind J. Fadel, Eric M. Poeschla, Katalin Banki, Andras Perl
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