Post-stroke cognitive impairment is considered one of the main complications during the chronic phase of ischemic stroke. In the adult brain, the hippocampus regulates both encoding and retrieval of new information through adult neurogenesis. Nevertheless, the lack of predictive models and studies based on the forgetting processes hinder the understanding of memory alterations after stroke. Our aim was to explore whether post-stroke neurogenesis participates in the development of long-term memory impairment. Here we show a hippocampal neurogenesis burst that persisted one month after stroke and that correlated with an impaired contextual and spatial memory performance. Furthermore, we demonstrate that the enhancement of hippocampal neurogenesis after stroke by physical activity or memantine treatment weakened existing memories. More importantly, stroke-induced newborn neurons promoted an aberrant hippocampal circuitry remodelling with differential features at ipsi- and contralesional levels. Strikingly, inhibition of stroke-induced hippocampal neurogenesis by temozolomide treatment or using a genetic approach (Nestin-CreERT2/NSE-DTA mice) impeded the forgetting of old memories. These results suggest that hippocampal neurogenesis modulation could be considered as a potential approach for post-stroke cognitive impairment.
María Isabel Cuartero, Juan de la Parra, Alberto Pérez-Ruiz, Isabel Bravo-Ferrer, Violeta Durán-Laforet, Alicia García-Culebras, Juan Manuel García-Segura, Jagroop Dhaliwal, Paul W. Frankland, Ignacio Lizasoain, María Àngeles Moro
The cytoplasmic aggregation of TDP-43 is a hallmark of degenerating neurons in amyotrophic lateral sclerosis (ALS) and subsets of frontotemporal dementia (FTD). In order to reduce TDP-43 pathology, we have generated single chain (scFv) antibodies against the RNA recognition motif 1 (RRM1) of TDP-43 which is involved in abnormal protein self-aggregation and interaction with p65 nuclear factor kappa B (NFKB). Viral-mediated delivery into the nervous system of a scFv antibody, named VH7Vk9, reduced microgliosis in a mouse model of acute neuroinflammation and it mitigated cognitive impairment, motor defects, TDP-43 proteinopathy and neuroinflammation in transgenic mice expressing ALS-linked TDP-43 mutations. These results suggest that antibodies targeting the RRM1 domain of TDP-43 might provide new therapeutic avenues for treatment of ALS and FTD.
Silvia Pozzi, Sai Sampath Thammisetty, Philippe Codron, Reza Rahimian, Karine V. Plourde, Geneviève Soucy, Christine Bareil, Daniel Phaneuf, Jasna Kriz, Claude Gravel, Jean-Pierre Julien
In the stomach, chronic inflammation causes metaplasia and creates a favorable environment for the evolution of gastric cancer. Glucocorticoids are steroid hormones that repress proinflammatory stimuli but their role in the stomach is unknown. In this study, we show that endogenous glucocorticoids are required to maintain gastric homeostasis. Removal of circulating glucocorticoids in mice by adrenalectomy resulted in the rapid onset of spontaneous gastric inflammation, oxyntic atrophy, and spasmolytic polypeptide-expressing metaplasia (SPEM), a precursor of gastric cancer. SPEM and oxyntic atrophy occurred independently of lymphocytes. However, depletion of monocytes and macrophages by clodronate treatment or inhibition of gastric monocyte infiltration using the Cx3cr1 knockout mouse model prevented SPEM development. Our results highlight the requirement for endogenous glucocorticoid signaling within the stomach to prevent spontaneous gastric inflammation and metaplasia and suggest that glucocorticoid deficiency may lead to gastric cancer development.
Jonathan T. Busada, Sivapriya Ramamoorthy, Derek W. Cain, Xiaojiang Xu, Donald N. Cook, John A. Cidlowski
We used the cancer intrinsic property of oncogene-induced DNA damage as the base for a conditional synthetic lethality approach. To target mechanisms important for cancer cell adaptation to genotoxic stress and thereby to achieve cancer cell-specific killing, we combined inhibition of the kinases ATR and Wee1. Wee1 regulates cell cycle progression, whereas ATR is an apical kinase in the DNA damage response. In an orthotopic breast cancer model, tumor-selective synthetic lethality between bioavailable ATR and Wee1 inhibitors led to tumor remission and inhibited metastasis with minimal side effects. ATR and Wee1 inhibition had a higher synergistic effect in cancer stem cells than in bulk cancer cells, compensating for the lower sensitivity of cancer stem cells to the individual drugs. Mechanistically, the combination treatment caused cells with unrepaired or under-replicated DNA to enter mitosis leading to mitotic catastrophe. As these inhibitors of ATR and Wee1 are already in phase I/II clinical trials, this knowledge could soon be translated into the clinic, especially as we showed that the combination treatment targets a wide range of tumor cells. Particularly the anti-metastatic effect of combined Wee1/ATR inhibition and the low toxicity of ATR inhibitors compared to Chk1 inhibitors has great clinical potential.
Amirali B. Bukhari, Cody W. Lewis, Joanna J. Pearce, Deandra Luong, Gordon K. Chan, Armin M. Gamper
Upon arterial injury, endothelial denudation leads to platelet activation, and delivery of multiple agents (e.g. TXA2, PDGF) promoting VSMC dedifferentiation, and proliferation, in injury repair (intimal hyperplasia). Resolution of vessel injury repair, and prevention of excessive repair (switching VSMC back to a differentiated quiescent state) is a poorly understood process. We now report that internalization of activated platelets by VSMCs promotes resolution of arterial injury by switching on VSMC quiescence. Ex vivo and in vivo studies using lineage tracing reporter mice (PF4-Cre x mTmG) demonstrated uptake of green platelets by red vascular smooth muscle cells upon arterial wire injury. Genome-wide miRNA sequencing of VSMCs co-cultured with activated platelets identified significant increases in platelet-derived miR-223. miR-223 appears to directly target PDGFRβ (in VSMCs) reversing the injury-induced dedifferentiation. Upon arterial injury platelet miR-223 knockout mice exhibit increased intimal hyperplasia, whereas miR-223 mimics reduced intimal hyperplasia. Diabetic mice with reduced expression of miR-223, exhibited enhanced VSMC dedifferentiation, proliferation, and increased intimal hyperplasia. Horizontal transfer of platelet-derived miRNAs into VSMCs provide a novel mechanism for regulating VSMC phenotypic switching. Platelets thus play a dual role in vascular injury repair, initiating an immediate repair process, and concurrently, a delayed process to prevent excessive repair.
Zhi Zeng, Luoxing Xia, Xuejiao Fan, Allison C. Ostriker, Timur Yarovinsky, Meiling Su, Yuan Zhang, Xiangwen Peng, Xie Yi, Lei Pi, Xiaoqiong Gu, Sookja Kim Chung, Kathleen A. Martin, Renjing Liu, John Hwa, Wai Ho Tang
Allergen immunotherapy for patients with allergies begins with weekly escalating doses of allergen under medial supervision to monitor and treat IgE-mast cell mediated anaphylaxis. There is currently no treatment to safely desensitize mast cells to enable robust allergen immunotherapy with therapeutic levels of allergen. Here we demonstrated that liposomal nanoparticles bearing an allergen and a high-affinity glycan ligand of the inhibitory receptor CD33 profoundly suppressed IgE-mediated activation of mast cells, prevented anaphylaxis in transgenic mice with mast cells expressing human CD33, and desensitized mice from subsequent allergen challenge for several days. We showed that high levels of CD33 were consistently expressed on human skin mast cells, and that the antigenic-liposomes with CD33 ligand prevented IgE-mediated bronchoconstriction in slices of human lung. The results demonstrated the potential of exploiting CD33 to desensitize mast cells to provide a therapeutic window for administering allergen immunotherapy without triggering anaphylaxis.
Shiteng Duan, Cynthia J. Koziol-White, William F. Jester Jr., Corwin M. Nycholat, Matthew S. Macauley, Reynold A. Panettieri Jr., James C. Paulson
Immune checkpoint inhibitors and adoptive transfer of gene-engineered T cells have emerged as novel therapeutic modalities for hard-to-treat solid tumors; however, many patients are refractory to these immunotherapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. By comparing the tumor microenvironment of checkpoint inhibition-sensitive and -resistant murine solid tumors, we observed that the resistant tumors had low immunogenicity and lacked infiltration of CD8+ T cells at the tumor site. We identified antigen presentation by CD11b+F4/80+ tumor-associated macrophages (TAMs) as a key factor correlated with immune resistance. In the resistant tumors, TAMs remained inactive and did not exert antigen-presenting activity. Targeted delivery of a long peptide antigen to TAMs by using a nano-sized hydrogel (nanogel) in the presence of a Toll-like receptor agonist activated TAMs, induced their antigen-presenting activity, and thereby transformed the resistant tumors into tumors sensitive to adaptive immune responses such as adoptive transfer of tumor-specific T cell receptor-engineered T cells. These results indicate that the status and function of TAMs have a significant impact on tumor immune sensitivity and also that manipulation of TAM functions would be an effective approach for improving the efficacy of immunotherapies.
Daisuke Muraoka, Naohiro Seo, Tae Hayashi, Yoshiro Tahara, Keisuke Fujii, Isao Tawara, Yoshihiro Miyahara, Kana Okamori, Hideo Yagita, Seiya Imoto, Rui Yamaguchi, Mitsuhiro Komura, Satoru Miyano, Masahiro Goto, Shin-ichi Sawada, Akira Asai, Hiroaki Ikeda, Kazunari Akiyoshi, Naozumi Harada, Hiroshi Shiku
Local flow patterns determine the uneven distribution of atherosclerotic lesions. This research aims to elucidate the mechanism of regulation of nuclear translocation of Yes-associated protein (YAP) under oscillatory shear stress (OSS) in the atheroprone phenotype of endothelial cells (ECs). We report here that OSS led to tyrosine phosphorylation and strong, continuous nuclear translocation of YAP in ECs that is dependent on integrin α5β1 activation. YAP overexpression in ECs blunted the anti-atheroprone effect of an integrin-α5β1 blocking peptide (ATN161) in Apoe-/- mice. Activation of integrin α5β1 induced tyrosine, but not serine, phosphorylation of YAP in ECs. Blockage of integrin α5β1 with ATN161 abolished the phosphorylation of YAP at Y357 induced by OSS. Mechanistic studies showed that c-Abl inhibitor attenuated the integrin α5β1-induced YAP tyrosine phosphorylation. Furthermore, the phosphorylation of c-Abl and YAPY357 was significantly increased in ECs in atherosclerotic vessels of mice and in human plaques vs. normal vessels. Finally, bosutinib, a tyrosine kinase inhibitor, markedly reduced the level of YAPY357 and the development of atherosclerosis in Apoe-/- mice. The c-Abl/YAPY357 pathway serves as a mechanism for the activation of integrin α5β1 and the atherogenic phenotype of ECs in response to OSS, and provides a potential therapeutic strategy for atherogenesis.
Bochuan Li, Jinlong He, Huizhen Lv, Yajin Liu, Xue Lv, Chenghu Zhang, Yi Zhu, Ding Ai
Sphingolipid imbalance is the culprit in a variety of neurological diseases, some affecting the myelin sheath. We have used whole exome sequencing in patients with undetermined leukoencephalopathies to uncover the endoplasmic reticulum lipid desaturase DEGS1 as the causative gene in nineteen patients from thirteen unrelated families. Shared features among the cases include severe motor arrest, early nystagmus, dystonia, spasticity and profound failure to thrive. MRI showed hypomyelination, thinning of corpus callosum and progressive thalami and cerebellar atrophy, suggesting a critical role of DEGS1 in myelin development and maintenance. This enzyme converts dihydroceramide (DhCer) into ceramide (Cer) in the final step of the de novo biosynthesis pathway. We detected a marked increase of the substrate DhCer and DhCer/Cer ratios in patient’s fibroblasts and muscle. Further, we used a knockdown approach for disease modelling in Danio rerio, followed by a preclinical test with the first-line treatment for multiple sclerosis, fingolimod (FTY720, Gilenya). The enzymatic inhibition of ceramide synthase, one step prior to DEGS1 in the pathway, by fingolimod, reduced the critical DhCer/Cer imbalance and the severe locomotor disability, increasing the number of myelinating oligodendrocytes in the zebrafish model. These proof-of-concept results pave the way to clinical translation.
Devesh C. Pant, Imen Dorboz, Agatha Schlüter, Stéphane Fourcade, Nathalie Launay, Javier Joya, Sergio Aguilera-Albesa, Maria Eugenia Yoldi, Carlos Casasnovas, Mary J. Willis, Montserrat Ruiz, Dorothée Ville, Gaetan Lesca, Karine Siquier-Pernet, Isabelle Desguerre, Huifang Yan, Jinming Wang, Margit Burmeister, Lauren Brady, Mark Tarnopolsky, Carles Cornet, Davide Rubbini, Javier Terriente, Kiely N. James, Damir Musaev, Maha S. Zaki, Marc C. Patterson, Brendan C. Lanpher, Eric W. Klee, Filippo Pinto e Vairo, Elizabeth Wohler, Nara Lygia de M. Sobreira, Julie S. Cohen, Reza Maroofian, Hamid Galehdari, Neda Mazaheri, Gholamreza Shariati, Laurence Colleaux, Diana Rodriguez, Joseph G. Gleeson, Cristina Pujades, Ali Fatemi, Odile Boespflug-Tanguy, Aurora Pujol
The development and function of stem and progenitor cells that produce blood cells are vital in physiology. GATA2 mutations cause GATA-2-deficiency syndrome involving immunodeficiency, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). GATA-2 physiological activities necessitate that it be strictly regulated, and cell type-specific enhancers fulfill this role. The +9.5 intronic enhancer harbors multiple conserved cis-elements, and germline mutations of these cis-elements are pathogenic in humans. Since mechanisms underlying how GATA2 enhancer disease mutations impact hematopoiesis and pathology are unclear, we generated mouse models of the enhancer mutations. While a multi-motif mutant was embryonic lethal, a single-nucleotide Ets motif mutant was viable, and steady-state hematopoiesis was normal. However, the Ets motif mutation abrogated stem/progenitor cell regeneration following stress. These results reveal a new mechanism in human genetics in which a disease predisposition mutation inactivates enhancer regenerative activity, while sparing developmental activity. Mutational sensitization to stress that instigates hematopoietic failure constitutes a paradigm for GATA-2-deficiency syndrome and other contexts of GATA-2-dependent pathogenesis.
Alexandra A. Soukup, Ye Zheng, Charu Mehta, Jun Wu, Peng Liu, Miao Cao, Inga Hofmann, Yun Zhou, Jing Zhang, Kirby D. Johnson, Kyunghee Choi, Sunduz Keles, Emery H. Bresnick
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