CoNDA Pilot Projects

Daniel Kashima, MD

Innate immune system influences on neuronal physiology and behavior in epilepsy

Epilepsy is a common brain network disorder characterized by an enduring risk for unprovoked seizures. Many patients also exhibit developmental or cognitive deficits. Although there are numerous etiologies, all epilepsies share the characteristic of an imbalance in excitation and inhibition of neural circuits. As such, the bulk of epilepsy management focuses on reducing neuronal excitation or increasing inhibition via medications or neuromodulation devices. Despite advances in knowledge, many patients with epilepsy suffer from seizures refractory to available treatments signifying a need for other therapeutic targets. Certain epilepsies such infantile spasms and febrile infection related epilepsy syndrome (FIRES) are treated with medications modulating the innate immune system. Implied with this treatment is a central role for the immune system in disease pathophysiology. It is not known what role(s) the innate immune system plays in other epilepsies or if there is a converging mechanism. This proposal will test the hypothesis that toll-like receptor 4 (TLR4) and interleukin 1 (IL-1), components of the innate immune system, are necessary for pathologic synaptic changes resulting in over-excitation of neural circuits in epilepsy. This will be assessed through the Specific Aims: (1) To determine the role of TLR4 in modulating synaptic physiology and learning/memory in epilepsy, behavioral and patch-clamp electrophysiology experiments will be performed in both genetic (Dravet syndrome) and provoked (mesial temporal lobe epilepsy) mouse models of epilepsy in the setting of TLR4 deficiency, and (2) To determine the consequence of IL-1 upregulation on synaptic physiology and learning/memory, behavioral and patch-clamp electrophysiology experiments will be performed in mice with functional IL-1 upregulation modeling FIRES. Results from these studies have the potential to elucidate shared mechanisms of innate immune neuronal circuit changes in epilepsy, bridging the fields of neuroscience and immunology to provide novel therapeutic interventions to mitigate epilepsy and related comorbidities.

Dr. Kashima is an Assistant Professor in the Department of Pediatrics/Division of Neurology at UNMC. He completed his education at the Vanderbilt University School of Medicine in Nashville, TN, and completed his residency training at the University of Michigan Medical School in Ann Arbor. 

Matthew Van Hook, PhD

Impacts of amyloid and tau pathology in visual brain regions

Alzheimer’s disease (AD) is a neurodegenerative disease that is the leading cause of dementia and a major cause of death. AD is known to be associated with visual system manifestations such as amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs) comprised of hyperphosphorylated tau protein in the retina and visual regions of the brain as well as retinal thinning and optic nerve atrophy. Still, it is largely unknown how
AD pathology influences the structure or function of the visual centers in the brain. In preliminary studies using 5xFAD mice, which have amyloid plaque deposition but no NFTs, we found that the regions responsible for conscious vision – the dorsolateral geniculate nucleus (dLGN) and primary visual cortex (V1) - display pronounced amyloid pathology and activation of phagocytic microglia. In contrast, the more reflexive areas such as the suprachiasmatic nucleus (SCN) and superior colliculus (SC) had no Aβ plaques or microglia responses. Additionally, patch-clamp electrophysiology recording in the dLGN showed no detectable effects on synaptic function in the dLGN. Since 5xFAD mice lack NFT's/Tau pathology, a key question is whether and how AD-like pathology characterized by both Aβ plaques and NFTs/hyperphosphorylated tau impacts visual brain regions. The overall objective of this pilot project will therefore be to test the hypothesis that combined amyloid and tau trigger AD-like pathology in major visual brain regions in 3xTg-AD mice, which develop both amyloid and tau pathology. Specific Aim 1 will employ an array of histological and microscopy approaches to test for AD-like pathology, microglial and astroglial reactivity, and synapse loss in the SCN, dLGN, V1, and SC. Specific Aim 2 will take a functional approach and use virally-delivered optogenetic reporters to selectively activate retinal ganglion cell inputs to SCN, dLGN, and SC in living brain slices while monitoring post-synaptic and single-vesicle response properties while performing patch clamp recording in living brain slices. Synaptic function will be assessed in V1 using extracellular electrical stimulation. Overall, the aims of this pilot project will provide critical early insight into differential effects of AD on visual centers of the brain mediating diverse visual responses, drawing on our lab’s expertise in diseases of the visual system and synaptic physiology, and supporting future applications for NIH research funding.

Matthew J. Van Hook, PhD, is an associate professor and neuroscientist in the UNMC Department of Ophthalmology and Visual Sciences. He also holds a courtesy appointment in the UNMC Department of Cellular and Integrative Physiology. Dr. Van Hook's research explores mechanisms underlying the plasticity and development of the visual system in health and disease.

Lee Korshoj, PhD

Hormonal and epigenetic regulation of TREM2 drives the severity of craniotomy infection

*pending NIH approval 

Infection following craniotomy can occur at rates exceeding 10% despite prophylactic measures, affecting hundreds of thousands of patients worldwide each year. The Gram-positive pathogen Staphylococcus aureus (S. aureus) is specifically responsible for half of these infections, where it forms a biofilm on the fragment of skull (referred to as the bone flap) that was intraoperatively removed to access the brain. As biofilms are highly recalcitrant to antibiotics and clearance by the host immune system, the only viable treatment typically requires discarding the bone flap and prolonged periods of antibiotic treatment prior to bone flap replacement with a prosthesis. Extended periods without the bone flap often lead to extracranial herniation, hydrocephalus, seizures, and neurological deficits on top of preexisting co-morbidities. The high morbidity and mortality associated with these infections necessitates a better understanding of immune factors driving severity and how the pathophysiology of craniotomy infection affects microanatomical or cognitive processes within the brain, as a step towards improved prevention and treatment. Using a mouse model of S. aureus craniotomy infection which has been validated to recapitulate human pathology, we have uncovered a central role for the myeloid-cell surface receptor, TREM2, in controlling the infection severity. The promiscuous TREM2 receptor can be stimulated through both damage- and pathogen-associated molecular patterns (DAMPs and PAMPs) which arise from the surgery/cell death and bacterial infection, respectively. During craniotomy infection, microglia, monocytes, and macrophages are the predominant TREM2-expressing cells. Our preliminary findings indicate that DAMPs and PAMPs have opposing stimulatory effects on TREM2 surface expression, and that signaling through the receptor imparts anti-inflammatory polarization by attenuating production of proinflammatory mediators and reducing intracellular reactive oxygen species within phagocytes to promote survival of S. aureus. In the craniotomy infection model, TREM2 ultimately enhances infection severity as seen via increased bacterial burdens across all tissue compartments (brain, bone flap, and galea). This phenotype is interestingly specific to females, suggesting a link between TREM2 signaling and hormone production. The objective of this work is to uncover the underlying molecular and epigenetic interdependencies of TREM2 in the context of craniotomy infection while also exploring how infection contributes to microanatomical and neurocognitive deficits. On the molecular level, we will pursue a working hypothesis of apolipoprotein-mediated crosstalk between estrogen and/or progesterone hormones and TREM2. On the epigenetic level, we will pursue a working hypothesis that hormone fluctuations during S. aureus infection induce changes in chromatin accessibility with downstream effects on TREM2 signaling. MRI (and future advanced in-vivo imaging and comprehensive behavioral assessments) will be performed to link molecular- and epigenetic-level changes to novel microanatomical (and future cognitive) phenotypes associated with craniotomy infection.

Lee E. Korshoj, PhD, is an assistant professor in the UNMC Department of Pathology, Microbiology and Immunology. He completed undergraduate and graduate training in chemical engineering and applies his cross-field expertise toward the study of host-pathogen interactions. As a National Science Foundation Graduate Research Fellowship Program Award recipient, his graduate work coupled sequencing technologies with machine learning and bioinformatics tools for biomarker detection and profiling multidrug-resistant bacteria. As a postdoctoral fellow, he received a National Institutes of Health National Research Service Award to examine the immune responses during infection with the multidrug-resistant bacterium Staphylococcus aureus and how this pathogen uses biofilm formation as a means to subvert host immune defenses.