Faculty Bibliography

BACKGROUND INFORMATION/BACKGROUND:The current consensus on cilia development posits that the ciliary transition zone (TZ) is formed via extension of nine centrosomal microtubules. In this model, TZ structure remains unchanged in microtubule number throughout the cilium life cycle. This model does not however explain structural variations of TZ structure seen in nature and could also lend itself to the misinterpretation that deviations from nine-doublet microtubule ultrastructure represent an abnormal phenotype. Thus, a better understanding of events that occur at the TZ in vivo during metazoan development is required. RESULTS:To address this issue, we characterized ultrastructure of two types of sensory cilia in developing Caenorhabditis elegans. We discovered that, in cephalic male (CEM) and inner labial quadrant (IL2Q) sensory neurons, ciliary TZs are structurally plastic and remodel from one structure to another during animal development. The number of microtubule doublets forming the TZ can be increased or decreased over time, depending on cilia type. Both cases result in structural TZ intermediates different from TZ in cilia of adult animals. In CEM cilia, axonemal extension and maturation occurs concurrently with TZ structural maturation. CONCLUSIONS AND SIGNIFICANCE/CONCLUSIONS:Our work extends the current model to include the structural plasticity of metazoan transition zone, which can be structurally delayed, maintained or remodelled in cell type-specific manner.

Over the past two decades, considerable advances in our understanding of inflammatory and immune pathways have allowed for the growing use of targeted biologic therapy. Most notably, the introduction of tumor necrosis factor (TNF) inhibitors has dramatically changed the management of autoimmune inflammatory disorders, including ankylosing spondylitis (AS). Despite the efficacy of TNF inhibitors documented in multiple clinical trials, anti-TNF therapy in AS is far from foolproof; it is associated with serious adverse effects and limited response to therapy in some patients. Moreover, specific questions regarding the role of TNF as a mediator of AS remain unanswered. Therefore, additional efforts are needed in order to better understand the role of TNF in the pathogenesis of AS and to develop safer and more effective treatment strategies. The purpose of this review is to better the understanding of the physiologic and pathogenic roles of TNF signaling in the course of AS. Relevant TNF biology and novel approaches to TNF blockade in AS are discussed.

Corticotropin-releasing factor (CRF) that is released from the paraventricular nucleus (PVN) of the hypothalamus is essential for mediating stress response by activating the hypothalamic-pituitary-adrenal axis. CRF-releasing PVN neurons receive inputs from multiple brain regions that convey stressful events, but their neuronal dynamics on the timescale of behavior remain unknown. Here, our recordings of PVN CRF neuronal activity in freely behaving mice revealed that CRF neurons are activated immediately by a range of aversive stimuli. By contrast, CRF neuronal activity starts to drop within a second of exposure to appetitive stimuli. Optogenetic activation or inhibition of PVN CRF neurons was sufficient to induce a conditioned place aversion or preference, respectively. Furthermore, conditioned place aversion or preference induced by natural stimuli was significantly decreased by manipulating PVN CRF neuronal activity. Together, these findings suggest that the rapid, biphasic responses of PVN CRF neurons encode the positive and negative valences of stimuli.

The strategy of using existing drugs originally developed for one disease to treat other indications has found success across medical fields. Such drug repurposing promises faster access of drugs to patients while reducing costs in the long and difficult process of drug development. However, the number of existing drugs and diseases, together with the heterogeneity of patients and diseases, notably including cancers, can make repurposing time consuming and inefficient. The key question we address is how to efficiently repurpose an existing drug to treat a given indication. As drug efficacy remains the main bottleneck for overall success, we discuss the need for machine-learning computational methods in combination with specific phenotypic studies along with mechanistic studies, chemical genetics and omics assays to successfully predict disease-drug pairs. Such a pipeline could be particularly important to cancer patients who face heterogeneous, recurrent and metastatic disease and need fast and personalized treatments. Here we focus on drug repurposing for colorectal cancer and describe selected therapeutics already repositioned for its prevention and/or treatment as well as potential candidates. We consider this review as a selective compilation of approaches and methodologies, and argue how, taken together, they could bring drug repurposing to the next level.

Reactive oxygen species (ROS) impair wound healing through destructive oxidation of intracellular proteins, lipids and nucleic acids. Intracellular superoxide dismutase (SOD1) regulates ROS levels and plays a critical role in tissue homoeostasis. Recent evidence suggests that age-associated wound healing impairments may partially result from decreased SOD1 expression. We investigated the mechanistic basis by which increased oxidative stress links to age-associated impaired wound healing. Fibroblasts were isolated from unwounded skin of young and aged mice, and myofibroblast differentiation was assessed by measuring α-smooth muscle actin and collagen gel contraction. Excisional wounds were created on young and aged mice to study the healing rate, ROS levels and SOD1 expression. A mechanistic link between oxidative stress and fibroblast function was explored by assessing the TGF-β1 signalling pathway components in young and aged mice. Age-related wounds displayed reduced myofibroblast differentiation and delayed wound healing, consistent with a decrease in the in vitro capacity for fibroblast-myofibroblast transition following oxidative stress. Young fibroblasts with normal SOD1 expression exhibited increased phosphorylation of ERK in response to elevated ROS. In contrast, aged fibroblasts with reduced SOD1 expression displayed a reduced capacity to modulate intracellular ROS. Collectively, age-associated wound healing impairments are associated with fibroblast dysfunction that is likely the result of decreased SOD1 expression and subsequent dysregulation of intracellular ROS. Strategies targeting these mechanisms may suggest a new therapeutic approach in the treatment of chronic non-healing wounds in the aged population.

BACKGROUND:Inferior vena cava thrombosis (IVCT), although rare, has a potential for significant morbidity and mortality. IVCT is often a result of IVC filter thrombosis, but it can also occur de novo. Although anticoagulation remains the standard of care, endovascular techniques to restore IVC patency have become key adjunctive therapies in recent years. This study examines a single-center experience with diagnosis and management of IVCT. METHODS:A retrospective Institutional Review Board-approved review of a single-center institutional database was screened to identify IVCT thrombosis using International Classification of Diseases code 453.2 over a 3-year period. Etiology of IVCT was separated into 2 groups: those with IVC thrombosis in the setting of prior IVC filter place and those in whom IVCT occurred de novo. Patient demographics, presenting characteristics, and management of IVCT were examined. Treatment options included expectant management with anticoagulation versus catheter-directed thrombolysis (CDT), mechanical thrombectomy, stenting, or a combination. For those who underwent intervention, technical success, defined as restoration of IVC patency, was assessed. RESULTS:Forty-one unique patients were identified with radiographically confirmed diagnosis of ICVT (mean age 61, range 25-91; 21 female, 51.2%). Eighteen (43.9%) patients presented with thrombosed IVC filter. Risk factors for venous thromboembolism included tobacco usage, current or prior smoking (n = 17, 41.5%), history of prior deep vein thrombosis (n = 25, 61.0%), malignancy (n = 17, 41.5%), use of hormonal supplements (n = 3, 7.3%), known thrombophilia (n = 4, 9.8%), and obesity (body mass index: mean 29, range 18.8-58.53). Eleven patients (26.8%) presented with pulmonary embolism (PE), and of those 63.6% had IVC filter thrombosis (n = 7). Risk of PE was not significantly different between those patients presenting with a thrombosed IVC filter compared to those with de novo IVCT (38.9% vs. 17.4%, P = 0.12) Management of IVCT included anticoagulation alone (n = 27, 65.9%), CDT (n = 5, 12.2%), mechanical thrombolysis (n = 10, 24.4%), and adjunctive IVC stent (n = 3, 7.3%). Among the 14 (34.1%) patients who had intervention for IVCT, patency was restored in 12 patients (85.7%). CONCLUSIONS:IVCT is a rare event and is associated with known risk factors for venous thromboembolism. PE can occur in roughly 25% of patients presenting with IVCT. Presence of a filter does not appear to confer an advantage in preventing PE when IVCT occurs. Although majority of IVCT is managed with anticoagulation alone, endovascular interventions, including lysis and stenting, can safely restore patency in most properly selected patients.

PTSD is heterogeneous disorder that can be long lasting and often has delayed onset following exposure to a traumatic event. Therefore, it is important to take a staging approach to evaluate progression of biological mechanisms of the disease. Here, we begin to evaluate the temporal trajectory of changes following exposure to traumatic stressors in the SPS rat PTSD model. The percent of animals displaying severe anxiety on EPM increased from 17.5% at one week to 57.1% two weeks after SPS stressors, indicating delayed onset or progressive worsening of the symptoms. The LC displayed prolonged activation, and dysbalance of the CRH/NPY systems, with enhanced CRHR1 gene expression, coupled with reduced mRNAs for NPY and Y2R. In the mediobasal hypothalamus, increased CRH mRNA levels were sustained, but there was a flip in alterations of HPA regulatory molecules, GR and FKBP5 and Y5 receptor at two weeks compared to one week. Two weeks after SPS, intranasal NPY at 300 µg/rat, but not 150 µg which was effective after one week, reversed SPS triggered elevated anxiety. It also reversed SPS elicited depressive/despair symptoms and hyperarousal. Overall, the results reveal time-dependent progression in development of anxiety symptoms and molecular impairments in gene expression for CRH and NPY systems in LC and mediobasal hypothalamus by SPS. With longer time afterwards only a higher dose of NPY was effective in reversing behavioral impairments triggered by SPS, indicating that therapeutic approaches should be adjusted according to the degree of biological progression of the disorder.

BACKGROUND:Bringing antibodies from pre-clinical studies to human trials requires humanization, but this process may alter properties that are crucial for efficacy. Since pathological tau protein is primarily intraneuronal in Alzheimer's disease, the most efficacious antibodies should work both intra- and extracellularly. Thus, changes which impact uptake or antibody binding will affect antibody efficacy. METHODS:Initially, we examined four tau mouse monoclonal antibodies with naturally differing charges. We quantified their neuronal uptake, and efficacy in preventing toxicity and pathological seeding induced by human-derived pathological tau. Later, we generated a human chimeric 4E6 (h4E6), an antibody with well documented efficacy in multiple tauopathy models. We compared the uptake and efficacy of unmodified and chimeric antibodies in neuronal and differentiated neuroblastoma cultures. Further, we analyzed tau binding using ELISA assays. FINDINGS/RESULTS:Neuronal uptake of tau antibodies and their efficacy strongly depends on antibody charge. Additionally, their ability to prevent tau toxicity and seeding of tau pathology does not necessarily go together. Particularly, chimerization of 4E6 increased its charge from 6.5 to 9.6, which blocked its uptake into human and mouse cells. Furthermore, h4E6 had altered binding characteristics despite intact binding sites, compared to the mouse antibody. Importantly, these changes in uptake and binding substantially decreased its efficacy in preventing tau toxicity, although under certain conditions it did prevent pathological seeding of tau. CONCLUSIONS:These results indicate that efficacy of chimeric/humanized tau antibodies should be thoroughly characterized prior to clinical trials, which may require further engineering to maintain or improve their therapeutic potential. FUND: National Institutes of Health (NS077239, AG032611, R24OD18340, R24OD018339 and RR027990, Alzheimer's Association (2016-NIRG-397228) and Blas Frangione Foundation.

The drivers and the specification of CD4⁺ T cell differentiation in the tumor microenvironment and their contributions to tumor immunity or tolerance are incompletely understood. Using models of pancreatic ductal adenocarcinoma (PDA), we show that a distinct subset of tumor-infiltrating dendritic cells (DC) promotes PDA growth by directing a unique T_H-program. Specifically, CD11b⁺CD103^- DC predominate in PDA, express high IL-23 and TGF-β, and induce FoxP3^neg tumor-promoting IL-10⁺IL-17⁺IFNγ^+ regulatory CD4⁺ T cells. The balance between this distinctive T_H program and canonical FoxP3^+ T_REGS is unaffected by pattern recognition receptor ligation and is modulated by DC expression of retinoic acid. This T_H-signature is mimicked in human PDA where it is associated with immune-tolerance and diminished patient survival. Our data suggest that CD11b⁺CD103^- DC promote CD4⁺ T cell tolerance in PDA which may underscore its resistance to immunotherapy.

BACKGROUND:Little evidence regarding the extent of recovery of radial nerve lesions with associated humerus trauma exists. The aim of this study is to examine the incidence and resolution of types of radial nerve palsy (RNP) in operative and nonoperative humeral shaft fracture populations. MATERIALS AND METHODS/METHODS:Radial nerve lesions were identified as complete (RNPc), which included motor and sensory loss, and incomplete (RNPi), which included sensory-only lesions. Charts were reviewed for treatment type, radial nerve status, RNP resolution time, and follow-up time. Descriptive statistics were used to document incidence of RNP and time to resolution. Independent-samples t-test was used to determine significant differences between RNP resolution time in operative and nonoperative cohorts. RESULTS:A total of 175 patients (77 operative, 98 nonoperative) with diaphyseal humeral shaft injury between 2007 and 2016 were identified and treated. Seventeen out of 77 (22.1%) patients treated operatively were diagnosed preoperatively with a radial nerve lesion. Two (2.6%) patients developed secondary RNPc postoperatively. Eight out of 98 (8.2%) patients presented with RNP postinjury for nonoperatively treated humeral shaft fracture. All patients who presented with either RNPc, RNPi, or iatrogenic RNP had complete resolution of their RNP. No statistically significant difference was found in recovery time when comparing the operative versus nonoperative RNPc, operative versus nonoperative RNPi, or RNPc versus RNPi patient groups. CONCLUSIONS:All 27 (100%) patients presenting with or developing radial nerve palsy in our study recovered. No patient required further surgery for radial nerve palsy. Radial nerve exploration in conjunction with open reduction and internal fixation (ORIF) appears to facilitate speedier resolution of RNP when directly compared with observation in nonoperative cases, although not statistically significantly so. These findings provide surgeons valuable information they can share with patients who sustain radial nerve injury with associated humerus shaft fracture or nonunion. LEVEL OF EVIDENCE/METHODS:Level III treatment study.