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1. Invasion of microglia/macrophages and granulocytes into the Mauthner axon myelin sheath following spinal cord injury of the adult goldfish, Carassius auratus

   https://doi.org/10.1002/jmor.21086  

   Koganti, Lahari ; Liu, Jun ; DeMajewski, Andrea ; Agostini, Mark A. ; Wong, Tina W. ; Faber, Donald S. ; Zottoli, Steven J. ( November 2019 , Journal of Morphology)

   Rapid activation of resident glia occurs after spinal cord injury. Somewhat later, innate and adaptive immune responses occur with the invasion of peripheral immune cells into the wound site. The activation of resident and peripheral immune cells has been postulated to play harmful as well as beneficial roles in the regenerative process. Mauthner cells, large identifiable neurons located in the hindbrain of most fish and amphibians, provided the opportunity to study the morphological relationship between reactive cells and Mauthner axons (M‐axons) severed by spinal cord crush or by selective axotomy. After crossing in the hindbrain, the M‐axons of adult goldfish,Carassius auratus, extend the length of the spinal cord. Following injury, the M‐axon undergoes retrograde degeneration within its myelin sheath creating an axon‐free zone (proximal dieback zone). Reactive cells invade the wound site, enter the axon‐free dieback zone and are observed in the vicinity of the retracted M‐axon tip as early as 3 hr postinjury. Transmission electron microscopy allowed the detection of microglia/macrophages and granulocytes, some of which appear to be neutrophil‐like, at each of these locations. We believe that this is the first report of the invasion of such cells within the myelin sheath of an identifiable axon in the vertebrate central nervous system (CNS). We speculate that microglia/macrophages and granulocytes that are attracted within a few hours to the damaged M‐axon are part of an inflammatory response that allows phagocytosis of debris and plays a role in the regenerative process. Our results provide the baseline from which to utilize immunohistochemical and genetic approaches to elucidate the role of non‐neuronal cells in the regenerative process of a single axon in the vertebrate CNS.

    

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2. A wireless spinal stimulation system for ventral activation of the rat cervical spinal cord

   https://doi.org/10.1038/s41598-021-94047-1  

   Hogan, Matthew K. ; Barber, Sean M. ; Rao, Zhoulyu ; Kondiles, Bethany R. ; Huang, Meng ; Steele, William J. ; Yu, Cunjiang ; Horner, Philip J. ( July 2021 , Scientific Reports)

   Electrical stimulation of the cervical spinal cord is gaining traction as a therapy following spinal cord injury; however, it is difficult to target the cervical motor region in a rodent using a non-penetrating stimulus compared with direct placement of intraspinal wire electrodes. Penetrating wire electrodes have been explored in rodent and pig models and, while they have proven beneficial in the injured spinal cord, the negative aspects of spinal parenchymal penetration (e.g., gliosis, neural tissue damage, and obdurate inflammation) are of concern when considering therapeutic potential. We therefore designed a novel approach for epidural stimulation of the rat spinal cord using a wireless stimulation system and ventral electrode array. Our approach allowed for preservation of mobility following surgery and was suitable for long term stimulation strategies in awake, freely functioning animals. Further, electrophysiology mapping of the ventral spinal cord revealed the ventral approach was suitable to target muscle groups of the rat forelimb and, at a single electrode lead position, different stimulation protocols could be applied to achieve unique activation patterns of the muscles of the forelimb.

    

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3. Quantitative Proteomic Profiling of Murine Ocular Tissue and the Extracellular Environment

   https://doi.org/10.1002/cpmo.83  

   Yeung, Jason ; Lamb, Jeffrey ; Krieger, Jonathan R. ; Gadjeva, Mihaela ; Geddes‐McAlister, Jennifer ( September 2020 , Current Protocols in Mouse Biology)

   Mass spectrometry‐based proteomics provides a robust and reliable method for detecting and quantifying changes in protein abundance among samples, including cells, tissues, organs, and supernatants. Physical damage or inflammation can compromise the ocular surface permitting colonization by bacterial pathogens, commonlyPseudomonas aeruginosa, and the formation of biofilms. The interplay betweenP. aeruginosaand the immune system at the site of infection defines the host's ability to defend against bacterial invasion and promote clearance of infection. Profiling of the ocular tissue following infection describes the nature of the host innate immune response and specifically the presence and abundance of neutrophil‐associated proteins to neutralize the bacterial biofilm. Moreover, detection of unique proteins produced byP. aeruginosaenable identification of the bacterial species and may serve as a diagnostic approach in a clinical setting. Given the emergence and prevalence of antimicrobial resistant bacterial strains, the ability to rapidly diagnose a bacterial infection promoting quick and accurate treatment will reduce selective pressure towards resistance. Furthermore, the ability to define differences in the host immune response towards bacterial invasion enhances our understanding of innate immune system regulation at the ocular surface. Here, we describe murine ocular infection and sample collection, as well as outline protocols for protein extraction and mass spectrometry profiling from corneal tissue and extracellular environment (eye wash) samples. © 2020 Wiley Periodicals LLC.

   Basic Protocol 1: Murine model of ocular infection

   Basic Protocol 2: Murine model sample collection

   Basic Protocol 3: Protein extraction from eye wash

   Basic Protocol 4: Protein extraction from corneal tissue

   Basic Protocol 5: Mass spectrometry‐based proteomics and bioinformatics from eye wash and corneal tissue samples

    

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4. Understanding Neutrophil Dynamics during COVID-19 Infection

   https://doi.org/10.3390/app13042409  

   Murphy, Quiyana M. ; Ciupe, Stanca M. ( February 2023 , Applied Sciences)

   Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results in varied clinical outcomes, with virus-induced chronic inflammation and tissue injury being associated with enhanced disease pathogenesis. To determine the role of tissue damage on immune populations recruitment and function, a mathematical model of innate immunity following SARS-CoV-2 infection has been proposed. The model was fitted to published longitudinal immune marker data from patients with mild and severe COVID-19 disease and key parameters were estimated for each clinical outcome. Analytical, bifurcation, and numerical investigations were conducted to determine the effect of parameters and initial conditions on long-term dynamics. The results were used to suggest changes needed to achieve immune resolution. 

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5. Stem‐Cell‐Driven Growth and Regrowth of the Adult Spinal Cord in Teleost Fish

   https://doi.org/10.1002/dneu.22672  

   Zupanc, Günther K. H. ( March 2019 , Developmental Neurobiology)

   The spinal cord of the teleost fishApteronotus leptorhynchuscontinues to grow during adulthood, in concert with the overall body growth. Immunohistological studies, combined with mathematical modeling, suggest that this growth is driven by proliferative activity of Sox2‐expressing stem/progenitor cells (SPCs) and by cell drift due to population pressure. The SPCs exhibit high volumetric density in the caudal filament and the ependymal layer. Nevertheless, the majority of these cells are found in the parenchyma throughout the rostro‐caudal axis of the spinal cord, albeit at much lower volumetric densities than in the ependymal layer. The SPCs give rise, via transit‐amplifying cells, to neurons and glia. The relative number of neurons and glia is primarily regulated through apoptosis of supernumerary neurons. Quantitative analysis has demonstrated that the continued cell proliferation results in additive neurogenesis. This addition includes adult‐born spinal electromotoneurons, thereby resulting in a continuous increase in the amplitude of the fish’s electric organ discharge during adult life. Amputation of the caudal part of the spinal cord induces initially a degenerative response, dominated by massive apoptotic cell death in spinal cord tissue immediately rostral to the injury site, and distinguished by a partial loss of the electric organ discharge amplitude. This phase is followed by a regenerative response, characterized by absence of gliosis and by rapid stem‐cell‐driven tissue regrowth. Although the quality of the regenerated tissue is variable among individuals, the structural repair has led in every fish examined thus far to full recovery of the electric organ discharge amplitude.

    

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