1
|
Mathavarajah S, Thompson AW, Stoyek MR, Quinn TA, Roy S, Braasch I, Dellaire G. Suppressors of cGAS-STING are downregulated during fin-limb regeneration and aging in aquatic vertebrates. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:241-251. [PMID: 37877156 PMCID: PMC11043210 DOI: 10.1002/jez.b.23227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 09/19/2023] [Accepted: 10/03/2023] [Indexed: 10/26/2023]
Abstract
During the early stages of limb and fin regeneration in aquatic vertebrates (i.e., fishes and amphibians), blastema undergo transcriptional rewiring of innate immune signaling pathways to promote immune cell recruitment. In mammals, a fundamental component of innate immune signaling is the cytosolic DNA sensing pathway, cGAS-STING. However, to what extent the cGAS-STING pathway influences regeneration in aquatic anamniotes is unknown. In jawed vertebrates, negative regulation of cGAS-STING activity is accomplished by suppressors of cytosolic DNA such as Trex1, Pml, and PML-like exon 9 (Plex9) exonucleases. Here, we examine the expression of these suppressors of cGAS-STING, as well as inflammatory genes and cGAS activity during caudal fin and limb regeneration using the spotted gar (Lepisosteus oculatus) and axolotl (Ambystoma mexicanum) model species, and during age-related senescence in zebrafish (Danio rerio). In the regenerative blastema of wounded gar and axolotl, we observe increased inflammatory gene expression, including interferon genes and interleukins 6 and 8. We also observed a decrease in axolotl Trex1 and gar pml expression during the early phases of wound healing which correlates with a dramatic increase in cGAS activity. In contrast, the plex9.1 gene does not change in expression during wound healing in gar. However, we observed decreased expression of plex9.1 in the senescing cardiac tissue of aged zebrafish, where 2'3'-cGAMP levels are elevated. Finally, we demonstrate a similar pattern of Trex1, pml, and plex9.1 gene regulation across species in response to exogenous 2'3'-cGAMP. Thus, during the early stages of limb-fin regeneration, Pml, Trex1, and Plex9.1 exonucleases are downregulated, presumably to allow an evolutionarily ancient cGAS-STING activity to promote inflammation and the recruitment of immune cells.
Collapse
Affiliation(s)
| | - Andrew W. Thompson
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA
| | - Matthew R. Stoyek
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Canada
| | - Stéphane Roy
- Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montréal, QC, Canada
| | - Ingo Braasch
- Department of Integrative Biology, Michigan State University, East Lansing, MI, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA
| | - Graham Dellaire
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| |
Collapse
|
2
|
Liu B, Alimi OA, Wang Y, Kong Y, Kuss M, Krishnan MA, Hu G, Xiao Y, Dong J, DiMaio DJ, Duan B. Differentiated mesenchymal stem cells-derived exosomes immobilized in decellularized sciatic nerve hydrogels for peripheral nerve repair. J Control Release 2024; 368:24-41. [PMID: 38367864 DOI: 10.1016/j.jconrel.2024.02.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/31/2024] [Accepted: 02/12/2024] [Indexed: 02/19/2024]
Abstract
Peripheral nerve injury (PNI) and the limitations of current treatments often result in incomplete sensory and motor function recovery, which significantly impact the patient's quality of life. While exosomes (Exo) derived from stem cells and Schwann cells have shown promise on promoting PNI repair following systemic administration or intraneural injection, achieving effective local and sustained Exo delivery holds promise to treat local PNI and remains challenging. In this study, we developed Exo-loaded decellularized porcine nerve hydrogels (DNH) for PNI repair. We successfully isolated Exo from differentiated human adipose-derived mesenchymal stem cells (hADMSC) with a Schwann cell-like phenotype (denoted as dExo). These dExo were further combined with polyethylenimine (PEI), and DNH to create polyplex hydrogels (dExo-loaded pDNH). At a PEI content of 0.1%, pDNH showed cytocompatibility for hADMSCs and supported neurite outgrowth of dorsal root ganglions. The sustained release of dExos from dExo-loaded pDNH persisted for at least 21 days both in vitro and in vivo. When applied around injured nerves in a mouse sciatic nerve crush injury model, the dExo-loaded pDNH group significantly improved sensory and motor function recovery and enhanced remyelination compared to dExo and pDNH only groups, highlighting the synergistic regenerative effects. Interestingly, we observed a negative correlation between the number of colony-stimulating factor-1 receptor (CSF-1R) positive cells and the extent of PNI regeneration at the 21-day post-surgery stage. Subsequent in vitro experiments demonstrated the potential involvement of the CSF-1/CSF-1R axis in Schwann cells and macrophage interaction, with dExo effectively downregulating CSF-1/CSF-1R signaling.
Collapse
Affiliation(s)
- Bo Liu
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Olawale A Alimi
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Yanfei Wang
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA; College of Osteopathic Medicine, Lake Erie College of Osteopathic Medicine, Erie, PA 16509, USA
| | - Yunfan Kong
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mitchell Kuss
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mena Asha Krishnan
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Guoku Hu
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Yi Xiao
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jixin Dong
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Dominick J DiMaio
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Bin Duan
- Mary & Dick Holland Regenerative Medicine Program and Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA; Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
| |
Collapse
|
3
|
Liu L, Li MZ, Yao MH, Yang TN, Tang YX, Li JL. Melatonin inhibits atrazine-induced mitochondrial impairment in cerebellum of mice: Modulation of cGAS-STING-NLRP3 axis-dependent cell pyroptosis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168924. [PMID: 38036146 DOI: 10.1016/j.scitotenv.2023.168924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/19/2023] [Accepted: 11/25/2023] [Indexed: 12/02/2023]
Abstract
The global prevalence of Neurological disorders has increased alarmingly in response to environmental and lifestyle changes. Atrazine (ATZ) is a difficult to degrade soil and water pollutant with well-known neurotoxicity. Melatonin (MT), an antioxidant with chemoprotective properties, has a potential therapeutic effect on cerebellar damage caused by ATZ exposure. The aim of this study was to explore the effects and underlying mechanisms of MT on the cerebellar inflammatory response and pyroptosis induced by ATZ exposure. In this study, C57BL/6J mice were treated with ATZ (170 mg/kg BW/day) and MT (5 mg/kg BW/day) for 28 days. Our results revealed that MT alleviated the histopathological changes, ultrastructural damage, oxidative stress and decrease of mitochondrial membrane potential (ΔΨm) in the cerebellum induced by ATZ exposure. ATZ exposure damaged the mitochondria leading to release of mitochondrial DNA (mtDNA) to the cytoplasm, MT activated the cyclic GMP-AMP synthetase interferon gene stimulator (cGAS-STING) axis to alleviate inflammation and pyroptosis caused by ATZ exposure. In general, our study provided new evidence that the cGAS-STING-NLRP3 axis plays an important role in the treatment of ATZ-induced cerebellar injury by MT.
Collapse
Affiliation(s)
- Lin Liu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Mu-Zi Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Ming-Hui Yao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Tian-Ning Yang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Yi-Xi Tang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Jin-Long Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, PR China.
| |
Collapse
|
4
|
Baruch EN, Nagarajan P, Gleber-Netto FO, Rao X, Xie T, Akhter S, Adewale A, Shajedul I, Mattson BJ, Ferrarotto R, Wong MK, Davies MA, Jindal S, Basu S, Harwood C, Leigh I, Ajami N, Futreal A, Castillo M, Gunaratne P, Goepfert RP, Khushalani N, Wang J, Watowich S, Calin GA, Migden MR, Vermeer P, D’Silva N, Yaniv D, Burks JK, Gomez J, Dougherty PM, Tsai KY, Allison JP, Sharma P, Wargo J, Myers JN, Gross ND, Amit M. Inflammation induced by tumor-associated nerves promotes resistance to anti-PD-1 therapy in cancer patients and is targetable by interleukin-6 blockade. RESEARCH SQUARE 2023:rs.3.rs-3161761. [PMID: 37503252 PMCID: PMC10371163 DOI: 10.21203/rs.3.rs-3161761/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
While the nervous system has reciprocal interactions with both cancer and the immune system, little is known about the potential role of tumor associated nerves (TANs) in modulating anti-tumoral immunity. Moreover, while peri-neural invasion is a well establish poor prognostic factor across cancer types, the mechanisms driving this clinical effect remain unknown. Here, we provide clinical and mechniastic association between TANs damage and resistance to anti-PD-1 therapy. Using electron microscopy, electrical conduction studies, and tumor samples of cutaneous squamous cell carcinoma (cSCC) patients, we showed that cancer cells can destroy myelin sheath and induce TANs degeneration. Multi-omics and spatial analyses of tumor samples from cSCC patients who underwent neoadjuvant anti-PD-1 therapy demonstrated that anti-PD-1 non-responders had higher rates of peri-neural invasion, TANs damage and degeneration compared to responders, both at baseline and following neoadjuvant treatment. Tumors from non-responders were also characterized by a sustained signaling of interferon type I (IFN-I) - known to both propagate nerve degeneration and to dampen anti-tumoral immunity. Peri-neural niches of non-responders were characterized by higher immune activity compared to responders, including immune-suppressive activity of M2 macrophages, and T regulatory cells. This tumor promoting inflammation expanded to the rest of the tumor microenvironment in non-responders. Anti-PD-1 efficacy was dampened by inducing nerve damage prior to treatment administration in a murine model. In contrast, anti-PD-1 efficacy was enhanced by denervation and by interleukin-6 blockade. These findings suggested a potential novel anti-PD-1 resistance drived by TANs damage and inflammation. This resistance mechanism is targetable and may have therapeutic implications in other neurotropic cancers with poor response to anti-PD-1 therapy such as pancreatic, prostate, and breast cancers.
Collapse
Affiliation(s)
- Erez N. Baruch
- Division of Cancer Medicine, Hematology and Oncology Fellowship program, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Frederico O. Gleber-Netto
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xiayu Rao
- Department of Bioinformatics and Computational Biology, Division of Basic Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Tongxin Xie
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Shamima Akhter
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Adebayo Adewale
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Islam Shajedul
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Brandi J Mattson
- The Neurodegeneration Consortium, Therapeutics Discovery Division, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Renata Ferrarotto
- Department of Head and Neck Thoracic Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Michael K. Wong
- Department of Melanoma Medical Oncology, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Michael A Davies
- Department of Melanoma Medical Oncology, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Sonali Jindal
- Department of Immunology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Sreyashi Basu
- Department of Immunology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Catherine Harwood
- Department of Dermatology, Royal London Hospital, Barts Health NHS Trust, Centre for Cell Biology and Cutaneous Research, Blizard Institute Barts and the London School of Medicine and Dentistry Queen Mary University of London, UK
| | - Irene Leigh
- Department of Dermatology, Royal London Hospital, Barts Health NHS Trust, Centre for Cell Biology and Cutaneous Research, Blizard Institute Barts and the London School of Medicine and Dentistry Queen Mary University of London, UK
| | - Nadim Ajami
- Department of Genomic Medicine, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Andrew Futreal
- Department of Genomic Medicine, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Micah Castillo
- Department of Biology and Biochemistry, University of Houston Sequencing and Gene Editing Core, University of Houston, Houston, TX, USA
| | - Preethi Gunaratne
- Department of Biology and Biochemistry, University of Houston Sequencing and Gene Editing Core, University of Houston, Houston, TX, USA
| | - Ryan P. Goepfert
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Jing Wang
- Department of Bioinformatics and Computational Biology, Division of Basic Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Stephanie Watowich
- Department of Immunology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - George A Calin
- Department of Translational Molecular Pathology, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Michael R. Migden
- Department of Dermatology, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Paola Vermeer
- Cancer Biology and Immunotherapies Group, Sanford Research, Sioux Falls, SD, USA
| | - Nisha D’Silva
- Department of Dentistry & Pathology, the University of Michigan, Ann Arbor, MI, USA
| | - Dan Yaniv
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jared K Burks
- Department of Leukemia, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Javier Gomez
- Department of Leukemia, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Patrick M Dougherty
- Department of Pain Medicine, Division of Anesthesiology, Critical Care, and Pain Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Kenneth Y. Tsai
- Department of Tumor Biology, Moffitt Cancer Center, Tampa, FL, USA
| | - James P Allison
- Department of Immunology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Padmanee Sharma
- Department of Immunology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jennifer Wargo
- Department of Genomic Medicine, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Surgical Oncology, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jeffrey N. Myers
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Neil D. Gross
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Moran Amit
- Department of Head and Neck Surgery, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Genomic Medicine, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX
| |
Collapse
|
5
|
Ghazisaeidi S, Muley MM, Salter MW. Neuropathic Pain: Mechanisms, Sex Differences, and Potential Therapies for a Global Problem. Annu Rev Pharmacol Toxicol 2023; 63:565-583. [PMID: 36662582 DOI: 10.1146/annurev-pharmtox-051421-112259] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The study of chronic pain continues to generate ever-increasing numbers of publications, but safe and efficacious treatments for chronic pain remain elusive. Recognition of sex-specific mechanisms underlying chronic pain has resulted in a surge of studies that include both sexes. A predominant focus has been on identifying sex differences, yet many newly identified cellular mechanisms and alterations in gene expression are conserved between the sexes. Here we review sex differences and similarities in cellular and molecular signals that drive the generation and resolution of neuropathic pain. The mix of differences and similarities reflects degeneracy in peripheral and central signaling processes by which neurons, immune cells, and glia codependently drive pain hypersensitivity. Recent findings identifying critical signaling nodes foreshadow the development of rationally designed, broadly applicable analgesic strategies. However, the paucity of effective, safe pain treatments compels targeted therapies as well to increase therapeutic options that help reduce the global burden of suffering.
Collapse
Affiliation(s)
- Shahrzad Ghazisaeidi
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada;
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- University of Toronto Centre for the Study of Pain, Toronto, Ontario, Canada
| | - Milind M Muley
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada;
- University of Toronto Centre for the Study of Pain, Toronto, Ontario, Canada
| | - Michael W Salter
- Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada;
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- University of Toronto Centre for the Study of Pain, Toronto, Ontario, Canada
| |
Collapse
|
6
|
Li Y, Lei Z, Ritzel RM, He J, Li H, Choi HMC, Lipinski MM, Wu J. Impairment of autophagy after spinal cord injury potentiates neuroinflammation and motor function deficit in mice. Theranostics 2022; 12:5364-5388. [PMID: 35910787 PMCID: PMC9330534 DOI: 10.7150/thno.72713] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 06/24/2022] [Indexed: 01/25/2023] Open
Abstract
Autophagy is a catabolic process that degrades cytoplasmic constituents and organelles in the lysosome, thus serving an important role in cellular homeostasis and protection against insults. We previously reported that defects in autophagy contribute to neuronal cell damage in traumatic spinal cord injury (SCI). Recent data from other inflammatory models implicate autophagy in regulation of immune and inflammatory responses, with low levels of autophagic flux associated with pro-inflammatory phenotypes. In the present study, we examined the effects of genetically or pharmacologically manipulating autophagy on posttraumatic neuroinflammation and motor function after SCI in mice. Methods: Young adult male C57BL/6, CX3CR1-GFP, autophagy hypomorph Becn1+/- mice, and their wildtype (WT) littermates were subjected to moderate thoracic spinal cord contusion. Neuroinflammation and autophagic flux in the injured spinal cord were assessed using flow cytometry, immunohistochemistry, and NanoString gene expression analysis. Motor function was evaluated with the Basso Mouse Scale and horizontal ladder test. Lesion volume and spared white matter were evaluated by unbiased stereology. To stimulate autophagy, disaccharide trehalose, or sucrose control, was administered in the drinking water immediately after injury and for up to 6 weeks after SCI. Results: Flow cytometry demonstrated dysregulation of autophagic function in both microglia and infiltrating myeloid cells from the injured spinal cord at 3 days post-injury. Transgenic CX3CR1-GFP mice revealed increased autophagosome formation and inhibition of autophagic flux specifically in activated microglia/macrophages. NanoString analysis using the neuroinflammation panel demonstrated increased expression of proinflammatory genes and decreased expression of genes related to neuroprotection in Becn1+/- mice as compared to WT controls at 3 days post-SCI. These findings were further validated by qPCR, wherein we observed significantly higher expression of proinflammatory cytokines. Western blot analysis confirmed higher protein expression of the microglia/macrophage marker IBA-1, inflammasome marker, NLRP3, and innate immune response markers cGAS and STING in Becn1+/- mice at 3 day after SCI. Flow cytometry demonstrated that autophagy deficit did not affect either microglial or myeloid counts at 3 days post-injury, instead resulting in increased microglial production of proinflammatory cytokines. Finally, locomotor function showed significantly worse impairments in Becn1+/- mice up to 6 weeks after SCI, which was accompanied by worsening tissue damage. Conversely, treatment with a naturally occurring autophagy inducer trehalose, reduced protein levels of p62, an adaptor protein targeting cargo to autophagosomes as well as the NLRP3, STING, and IBA-1 at 3 days post-injury. Six weeks of trehalose treatment after SCI led to improved motor function recovery as compared to control group, which was accompanied by reduced tissue damage. Conclusions: Our data indicate that inhibition of autophagy after SCI potentiates pro-inflammatory activation in microglia and is associated with worse functional outcomes. Conversely, increasing autophagy with trehalose, decreased inflammation and improved outcomes. These findings highlight the importance of autophagy in spinal cord microglia and its role in secondary injury after SCI.
Collapse
Affiliation(s)
- Yun Li
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Zhuofan Lei
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Rodney M Ritzel
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Junyun He
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Hui Li
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Harry M C Choi
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Marta M Lipinski
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| | - Junfang Wu
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD, 21201 USA
| |
Collapse
|