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Abstract
Friedreich ataxia is an autosomal recessive neurodegenerative disease associated with a high diabetes prevalence. No treatment is available to prevent or delay disease progression. Friedreich ataxia is caused by intronic GAA trinucleotide repeat expansions in the frataxin-encoding FXN gene that reduce frataxin expression, impair iron-sulfur cluster biogenesis, cause oxidative stress, and result in mitochondrial dysfunction and apoptosis. Here we examined the metabolic, neuroprotective and frataxin-inducing effects of glucagon-like-peptide 1 (GLP-1) analogs in in vivo and in vitro models and in Friedreich ataxia patients. The GLP-1 analog exenatide improved glucose homeostasis of frataxin-deficient mice through enhanced insulin content and secretion in pancreatic β-cells. Exenatide induced frataxin and iron-sulfur cluster-containing proteins in β-cells and brain, and was protective to sensory neurons in dorsal root ganglia. GLP-1 analogs also induced frataxin expression, reduced oxidative stress and improved mitochondrial function in Friedreich ataxia patients’ induced pluripotent stem cell-derived β-cells and sensory neurons. The frataxin-inducing effect of exenatide was confirmed in a pilot trial in Friedreich ataxia patients, showing modest frataxin induction in platelets over a 5-week treatment course. Taken together, GLP-1 analogs improve mitochondrial function in frataxin-deficient cells and induce frataxin expression. Our findings identify incretin receptors as a therapeutic target in Friedreich ataxia.
Authors
Mariana Igoillo-Esteve, Ana F. Oliveira, Cristina Cosentino, Federica Fantuzzi, Céline Demarez, Sanna Toivonen, Amélie Hu, Satyan Chintawar, Miguel Lopes, Nathalie Pachera, Ying Cai, Baroj Abdulkarim, Myriam Rai, Lorella Marselli, Piero Marchetti, Mohammad Tariq, Jean-Christophe Jonas, Marina Boscolo, Massimo Pandolfo, Décio L. Eizirik, Miriam Cnop
Abstract
Integrins, the extracellular matrix receptors that facilitate cell adhesion and migration, are necessary for organ morphogenesis; however, their role in maintaining adult tissue homeostasis is poorly understood. To define the functional importance of β1 integrin in adult mouse lung, we deleted it post-development in type 2 alveolar epithelial cells (AECs). Aged β1 integrin-deficient mice exhibited chronic obstructive pulmonary disease (COPD)-like pathology characterized by emphysema, lymphoid aggregates, and increased macrophage infiltration. These histopathological abnormalities were preceded by β1 integrin-deficient AEC dysfunction such as excessive reactive oxygen species production and up-regulation of NF-κB-dependent chemokines, including CCL2. Genetic deletion of the CCL2 receptor, Ccr2, in mice with β1 integrin-deficient type 2 AECs impaired recruitment of monocyte-derived macrophages and resulted in accelerated inflammation and severe premature emphysematous destruction. These lungs exhibited reduced AEC efferocytosis and excessive numbers of inflamed type 2 AECs, demonstrating the requirement for recruited monocyte-macrophages in limiting lung injury and remodeling in the setting of a chronically inflamed epithelium. These studies support a critical role for β1 integrin in alveolar homeostasis in the adult lung.
Authors
Erin J. Plosa, John T. Benjamin, Jennifer M. Sucre, Peter M. Gulleman, Linda A. Gleaves, Wei Han, Seunghyi Kook, Vasiliy V. Polosukhin, Scott M. Haake, Susan H. Guttentag, Lisa R. Young, Ambra Pozzi, Timothy S. Blackwell, Roy Zent
Abstract
Dystrophic muscle is characterised by chronic injury, and a steady recruitment of inflammatory Ly6Chi monocytes. Recent studies have identified the spleen as the dominant reservoir of these cells during chronic inflammation. Here we investigated the hitherto unexplored contribution of splenic Ly6Chi monocytes to dystrophic muscle pathology. Using the mdx mouse model of muscular dystrophy, we show that Ly6Chi monocytes accumulate in great numbers in the spleen over the course of the disease. The chemokine receptor CCR2 was upregulated on Ly6Chi monocytes in mdx spleen before disease onset, thereby enabling their recruitment to dystrophic muscle. Splenectomy performed before disease onset significantly reduced the number of Ly6Chi monocytes infiltrating dystrophic limb muscle. Moreover, in the absence of splenic Ly6Chi monocytes there was a significant reduction in dystrophic muscle inflammation and necrosis, along with improved regeneration during early disease. However, during late disease, lack of splenic Ly6Chi monocytes adversely affected muscle fiber repair, due to a delay in the phenotypic shift of pro-inflammatory F4/80+/Ly6Chi/CD206lo to anti-inflammatory F4/80+/Ly6Clo/CD206+ macrophages. Overall, we show that the spleen is an indispensable source of Ly6Chi monocytes in muscular dystrophy, and that splenic monocytes are critical players in both muscle fiber injury and repair.
Authors
Giuseppe Rizzo, Rosanna Di Maggio, Anna Benedetti, Jacopo Morroni, Marina Bouche, Biliana Lozanoska-Ochser
Abstract
Anti-PD1 therapy has become an immunotherapeutic backbone for treating many cancer types. While many studies have aimed to characterize the immune response to anti-PD1 therapy in the tumor and in the peripheral blood, relatively less is known about the changes in the tumor draining lymph nodes (TDLNs). TDLNs are primary sites of tumor antigen exposure that are critical to both regulation and cross-priming of the antitumor immune response. We employed multi-panel mass cytometry to obtain a high-parameter proteomic (39 total unique markers) immune profile of the TDLN in a well-studied PD1-responsive immunocompetent mouse model. Based on combined hierarchal gating and unsupervised clustering analyses, we found that anti-PD1 therapy enhances remodeling of both B and T cell compartments toward memory phenotypes. Functionally, expression of checkpoint markers was increased in conjunction with production of IFNγ, TNFα, or IL2 in key cell types, including B and T cell subtypes and rarer subsets such as Tregs and NKT cells. A deeper profiling of the immunologic changes that occur in the TDLN milieu during effective anti-PD1 therapy may lead to the discovery of novel biomarkers for monitoring response and provide key insights toward developing combination immunotherapeutic strategies.
Authors
Won Jin Ho, Mark Yarchoan, Soren Charmsaz, Rebecca M. Munday, Ludmila Danilova, Marcelo B. Sztein, Elana J. Fertig, Elizabeth M. Jaffee
Abstract
Background. We hypothesized that dynamic perfluorinated gas magnetic resonance imaging (19F MRI) would sensitively detect mild cystic fibrosis (CF) lung. Methods. This prospective study enrolled 20 healthy volunteers and 24 stable subjects with CF, including a subgroup of subjects with normal FEV1 (>80% predicted, n = 9). Dynamic 19F MRI images were acquired during sequential breath holds while breathing perfluoropropane (PFP) and during gas wash-out. Outcomes included the fraction of lung without significant ventilation (ventilation defect percent, VDP) and time constants that described PFP wash-in and wash-out kinetics. Results. VDP values (mean ± SD) of healthy controls (3.87% ± 2.7%) were statistically different from moderate CF subjects (19.5% ± 15.5%, P = 0.001) but not from mild CF subjects (10.4% ± 9.9%, P = 0.24) . The fractional lung volume with slow gas wash-out was elevated both in subjects with mild (9.61% ± 4.87%; P = 0.0066) and moderate CF (16.01% ± 5.01%; P = 0.0002) when compared to healthy controls (3.84% ± 2.16%). Conclusion. 19F MRI detected significant ventilation abnormalities in subjects with cystic fibrosis. Assessment of gas wash-out kinetics was more sensitive to mild CF lung disease than quantitation of steady state ventilation defects making 19F MRI a potentially valuable method for the characterization of early lung disease in CF.
Authors
Jennifer L. Goralski, Sang Hun Chung, Tyler M. Glass, Agathe S. Ceppe, Esther O. Akinnagbe-Zusterzeel, Aaron T. Trimble, Richard C. Boucher, Brian J. Soher, H. Cecil Charles, Scott H. Donaldson, Yueh Z. Lee
Abstract
Background. Current clinical biomarkers for the PD-1 blockade therapy are insufficient because they rely only on the tumor properties such as PD-L1 expression frequency and the amount of tumor mutation burden. Identifying reliable responsive biomarkers based on the host immunity is necessary to improve the predictive values. Methods. We investigated the levels of plasma metabolites and T cell properties including energy metabolism markers in the blood of patients with non-small cell lung cancer before and after treatment with nivolumab (n = 55). Predictive value of combination markers statistically selected were evaluated by cross validation and linear discriminant analysis on discovery and validation cohorts, respectively. Correlation between plasma metabolites and T cell markers were investigated. Results. The four metabolites derived from microbiome (hippuric acid), fatty acid oxidation (butyrylcarnitine) and redox (cystine and glutathione disulfide) provided high response probability (AUC = 0.91). Similarly, a combination of four T cell markers, those related to mitochondrial activation (PGC-1 expression and reactive oxygen species), and the frequencies of CD8+ PD-1high and CD4+ T cells demonstrated even higher prediction value (AUC = 0.96). Among the pool of all selected markers, the four T cell markers were exclusively selected as the highest predictive combination probably due to their linkage to the above mentioned metabolite markers. In a prospective validation set (n = 24) these four cellular markers showed a high accuracy rate for the clinical responses of the patients (AUC = 0.92). Conclusion. Combination of biomarkers reflecting host immune activity is quite valuable for the responder prediction.
Authors
Ryusuke Hatae, Kenji Chamoto, Young Hak Kim, Kazuhiro Sonomura, Kei Taneishi, Shuji Kawaguchi, Hironori Yoshida, Hiroaki Ozasa, Yuichi Sakamori, Maryam Akrami, Sidonia Fagarasan, Izuru Masuda, Yasushi Okuno, Fumihiko Matsuda, Toyohiro Hirai, Tasuku Honjo
Abstract
Chronic sympathoexcitation is implicated in ventricular arrhythmogenesis (VAs) following myocardial infarction (MI), but the critical neural pathways involved are not well understood. Cardiac adrenergic function is partly regulated by sympathetic afferent reflexes, transduced by spinal afferent fibers expressing the TRPV1 channel. The role of chronic TRPV1 afferent signaling in VAs is not known. We hypothesized that persistent TRPV1 afferent neurotransmission promotes VAs after MI. Using epicardial Resiniferatoxin (RTX) to deplete cardiac TRPV1-expressing fibers, we dissected the role of this neural circuit in VAs after chronic MI in a porcine model. We examined the underlying mechanisms using molecular approaches, immunohistochemistry, in vitro and in vivo cardiac electrophysiology, and simultaneous cardio-neural mapping. Epicardial RTX depleted cardiac TRPV1 afferent fibers and abolished functional responses to TRPV1 agonists. Ventricular tachycardia/fibrillation (VT/VF) was readily inducible in MI subjects by programmed electrical stimulation or cesium chloride administration, however, TRPV1 afferent depletion prevented VT/VF induced by either method. Mechanistically, TRPV1 afferent depletion neither altered cardiomyocyte action potentials and calcium transients; nor the expression of ion channels and calcium handling proteins. However, it attenuated fibrosis and mitigated electrical instability in the scar-border zone. In vivo recordings of cardiovascular-related stellate ganglion neurons (SGNs) revealed that MI enhances SGN function and disrupts integrated neural processing. Depleting TRPV1 afferents normalized these processes. Taken together, these data indicate that after MI, TRPV1 afferent-induced adrenergic dysfunction promotes fibrosis, adverse cardiac remodeling, and worsens border zone electrical heterogeneity, resulting in electrically unstable ventricular myocardium. We propose targeting TRPV1-expressing afferent to reduce VT/VF following MI.
Authors
Koji Yoshie, Pradeep S. Rajendran, Louis Massoud, Janki Mistry, M. Amer Swid, Xiaohui Wu, Tamer Sallam, Rui Zhang, Joshua I. Goldhaber, Siamak Salavatian, Olujimi A. Ajijola
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
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