Our Research

While most hydrocephalus in the United States develops as a result of brain hemorrhage, infection is by far the greatest cause of hydrocephalus worldwide. Paenibacillus species have emerged as significant contributors to neonatal sepsis and post-infectious hydrocephalus (PIH), particularly in marginalized communities. Fatal neonatal infections caused by Paenibacillus have risen sharply in East Africa and, more recently, in the U.S., but limited diagnostic capacity in resource-constrained settings hampers early detection and effective treatment. This project strengthens the clinical microbiology laboratory at Jinja Regional Referral Hospital in Uganda to build sustainable diagnostic capacity for PIH management in East Africa. The team will advance understanding of Paenibacillus-related infections, evaluate an innovative in-house point-of-care diagnostic assay, and generate genomic data characterizing antimicrobial resistance mechanisms and virulence factors—contributing to global surveillance efforts and informing treatment guidelines. Because inflammation and scarring of the CSF pathways are shared features of hydrocephalus regardless of what triggers it, what this work reveals about how infection injures the developing brain may prove relevant across the full spectrum of the disease, including the post-hemorrhagic hydrocephalus most commonly seen in the U.S.

Neonatal hydrocephalus often requires multiple invasive surgeries due to shunt failures, highlighting the need for non-surgical alternatives. This project develops a novel biologic therapy targeting the choroid plexus (ChP) to reduce cerebrospinal fluid production using an adeno-associated virus (AAV)-mediated approach. Building on new findings demonstrating effective ChP cell ablation and reduced CSF volume with a prototype AAV-ChP, the study will develop an optimized AAV production system that can later scale to GMP manufacturing. The team aims to: (1) create an AAV production system using an shRNA approach to make producer cells resistant to the transgene product and ensure high virus yield, and (2) evaluate novel AAV5 capsid variants with improved ChP specificity and efficiency. Success would yield a high-efficiency, clinically scalable AAV therapy and a new path toward treating hydrocephalus without surgery.

Established treatments for hydrocephalus rely on shunt surgery, which relieves symptoms but leaves the underlying disease essentially untreated. Gene therapy—transferring genetic material to repair, regulate, or replace defective genes—offers a route to correcting the underlying disease mechanism, but delivering it non-invasively to the brain remains a major barrier. Recent advances in focused ultrasound (FUS) enable the delivery of systemically circulating gene therapies to the central nervous system and hold significant promise for overcoming these technical restrictions. This project examines the use of FUS as a method for gene delivery to achieve expression in the ependymal cells lining the periventricular space of the brain, an important step toward expanding gene therapies across the spectrum of neurological disorders including hydrocephalus.

The Robinson and Jantzie labs have identified an oral medication cocktail (including melatonin and roxadustat) that demonstrated improved stabilization of CSF dynamics and neural cell recovery in animal models of hydrocephalus. This study performs key experiments needed to bring this cocktail to clinical trials. The team aims to: (1) establish a minimally effective dose of the drug cocktail in existing post-hemorrhagic hydrocephalus models, (2) define lipid signatures of repair that correlate with dosing and efficacy, and (3) identify CSF biomarkers to guide treatment duration.

Premature infants are particularly susceptible to brain bleeds in the germinal matrix, a region of intense growth during brain development. These bleeds can cause lasting brain injury and post-hemorrhagic hydrocephalus (PHH). While promising therapies for PHH are emerging from rodent models, translation to the clinic often fails without large animal models for intermediate preclinical trials. These researchers will build upon prior mouse model work and, with the Costine-Bartell laboratory, create a realistic model of germinal matrix bleeds and PHH in neonatal piglets. They aim to: (1) develop a piglet model of germinal matrix hemorrhage leading to PHH using intraperitoneal glycerol injections, and (2) test choroid plexus Nkcc1-gene therapy on this new model for PHH treatment.

This proposal investigates the role of peripheral myeloid cells in PHH and novel therapeutic approaches targeting inflammation for improved patient outcomes. Preliminary data show PHH is associated with disruption of the choroid plexus (CP)-blood-CSF barrier and increased pro-inflammatory myeloid cells expressing inflammatory mTOR genes. Additionally, a decrease in PGRN, a crucial regulator of anti-inflammatory autophagy, is observed in PHH. The team hypothesizes that myeloid cells enter the CSF through the CP-CSF barrier, and manipulation of the mTOR and PGRN inflammatory pathways can prevent intraventricular hemorrhage from developing into PHH and related neurological injury. The objectives are to examine the fundamental role of myeloid cells in PHH and explore new pharmacological therapies using rapamycin (FDA-approved mTOR inhibitor) and PGRN to reduce inflammation and brain cell damage in the periventricular areas.

Brain hemorrhages in infants cause the most common form of pediatric hydrocephalus in North America. Of the brain tissues regulating post-hemorrhagic hydrocephalus (PHH) development, the choroid plexus represents a major treatment target based on animal models. Before pursuing clinical trials, research utilizing human tissue is needed to validate treatment targets and approaches. Given this need for ex vivo human preclinical testing, this team is developing a novel experimental platform utilizing discarded surgical specimens. This allows evaluation of known molecular targets in PHH and identification of new targets specific to human tissue. In parallel, they will test the ability of current gene therapy tools to target human tissue for clinical translation. Together, these applications of a novel ex vivo human assay will accelerate progress toward clinical trials.

Germinal matrix hemorrhage with intraventricular hemorrhage (GMH-IVH) is a devastating neurologic injury in neonates. GMH-IVH begins with arterial vessel rupture in premature neonates, followed by secondary injury with cell damage, cytotoxic edema, immune cell recruitment, and generalized neuroinflammation. This injury is believed to result in post-hemorrhagic hydrocephalus (PHH) and periventricular leukomalacia (PVL) with significant neurocognitive impairment and cerebral palsy. The complement system has recently been implicated in PHH development following GMH-IVH, with targeted inhibitors reducing PHH rates while improving neurocognitive outcomes in animal models. However, little is known about the underlying mechanism for complement activation and regulation during injury. Understanding the complement system's role will allow use of available targeted inhibitors to pharmacologically treat neonates with GMH-IVH, potentially preventing hydrocephalus development while reducing the number of children requiring surgical intervention.

Current management strategies for hydrocephalus rely on invasive surgeries including endoscopic third ventriculostomy (ETV), choroid plexus lesionectomy, and shunt replacement. Beyond inherent surgical risks, there's high risk of post-procedure shunt failure leading to additional surgeries and significant morbidity and mortality. There is urgent need for an incisionless, non-invasive approach for managing hydrocephalus. Histotripsy is a non-invasive, ultrasound-based ablation therapy that uses targeted cavitation to mechanically fractionate and liquefy tissues. Histotripsy offers an opportunity to perform ETV, choroid plexus lesionectomy, and shunt clearing without making an incision. In this proposal, researchers will conduct experiments to demonstrate the feasibility and accuracy of using histotripsy to perform these procedures in a cadaveric model. Histotripsy has the potential to meet the need for incisionless, non-invasive surgical treatment through ETV, choroid plexus lesionectomy, and as adjuvant therapy for maintaining shunt patency.

Bleeding into the cerebral ventricles is the leading cause of hydrocephalus in the United States, yet interventions to treat this condition remain suboptimal. The Lehtinen laboratory and others have recently identified the choroid plexus (ChP) as a first responder to intraventricular blood and therefore a key contributor to hydrocephalus development. Despite major research advances utilizing rodent models of hydrocephalus, translation to the human clinic has historically been limited. This is likely due to our lack of understanding of fundamental differences in hydrocephalus development between rodents and humans. The pig offers an intermediate species for preclinical testing of therapies. Here they propose to compare human and pig ChP in hydrocephalus development following bleeding. They can then compare these data to existing rodent data to elucidate the most promising mechanisms for developing novel therapies.

Why are surgical approaches still the mainstay of hydrocephalus treatment? Why isn't there a pharmaceutical, non-surgical strategy despite decades of research? The answer: mechanisms driving cerebrospinal fluid (CSF) secretion through the choroid plexus (CP) are not completely understood. There is critical need for a model that gives researchers unencumbered access to study how the CP functions. This research proposal will develop a tool to accelerate investigation of mechanisms underlying CP functions. The CP-on-a-chip developed in this project will then be used to test a hypothesis about how inflammation may trigger TRPV4 activation and lead to CSF hypersecretion at the CP. Understanding how the "secretion" and "barrier" functions of the CP are altered in response to inflammation will enable development of more effective pharmaceutical approaches to potentially mitigate hydrocephalus symptoms without the need for surgeries.

Very few risk factors have been determined that contribute to developing hydrocephalus following intracranial hemorrhage. Further, the functional mechanisms and downstream effects of hemorrhage leading to hydrocephalus have not been characterized. There is need for novel, unbiased approaches to identify and describe the pathways that lead to PHH. This project will fund molecular profiling of tissues relevant to PHH (cerebrospinal fluid) from clinically well-characterized hydrocephalus patients to: (1) identify novel genes implicated in disease, (2) understand the biology of the disease, (3) identify gene-specific pathways leading to disease, (4) identify new potential biomarkers, and (5) nominate potential drugs that could be repurposed for PHH. To accomplish this, researchers will generate genomics, transcriptomics, proteomics, metabolomic and lipidomic data from two large, well-characterized hydrocephalus cohorts.

Developing pharmacotherapy for hydrocephalus is hindered by its complex multifactorial nature and the prevailing dogma that surgery is the only option. Understanding the underlying mechanisms of hydrocephalus-related brain injury can overcome this narrow view, opening doors for medical therapeutics to improve outcomes and even prevent or cure the condition. These researchers have collaboratively identified a complement-induced component of post-hemorrhagic hydrocephalus (PHH). However, several physiological functions are associated with the complement system, and prolonged systemic inhibition is detrimental. They have therefore developed a novel peripherally injected, site-targeted complement inhibitor (PSel-Crry 2.3), which reduced PHH, decreased brain injury volume, and improved neurological function in a mouse model of germinal matrix hemorrhage (GMH). This project funds investigation of the most efficacious dose and initial treatment window using the same GMH model. Successful completion will enhance understanding of PHH and propel development of therapeutic medication for this currently surgical-only condition.

No studies have identified the complete expression profile of cells and exosomes in the cerebrospinal fluid (CSF) in post-hemorrhagic hydrocephalus (PHH). The McAllister Lab's preliminary results indicate that neural stem cells (NSC), oligodendrocyte-related progenitor cells, and immune cells are present in the CSF of PHH patients. They have also confirmed that exosomes carry pro-inflammatory cargo, such as S100A proteins, in the CSF in PHH. This project will test the central hypothesis that PHH pathogenesis and its associated developmental disabilities are mediated through the effect of CSF-based cellular and exosomal inflammatory signaling on the ventricular/subventricular zones (VZ/SVZ). The team will: (1) define the cell composition and gene-activated pathways in CSF from neonates with PHH, (2) examine the role of exosomes in inflammatory and neurodevelopmental mechanisms in hydrocephalus, and (3) analyze S100A9 in PHH as a potential therapeutic target. This work will provide new research directions into PHH pathophysiology and possible therapeutic targets.

Though hydrocephalus results from multiple causes, both genetic and acquired, there are convergent pathophysiological mechanisms that can be pursued in developing non-surgical intervention strategies. Previous pharmacotherapies have largely failed in clinical settings for hydrocephalus management due to: (1) inappropriate target distribution leading to off-target deleterious effects, (2) failure to converge on multiple pathogenic mechanisms, and (3) lack of robust and adequately powered preclinical proof-of-mechanism studies. This project pursues a promising new target, inhibition of serum- and glucocorticoid-induced kinase 1 (SGK1), for hydrocephalus treatment. SGK1 inhibitors block transepithelial ion transport and thus may reduce CSF production. This grant will support three experimental aims intentionally designed to provide a robust body of preclinical studies to advance the SGK1 inhibitor toward clinical trial. These studies represent a novel target for hydrocephalus treatment using a proprietary compound that is a specific inhibitor of SGK1.

Human hydrocephalus is characterized by abnormal circulation and accumulation of cerebrospinal fluid in the brain ventricles. Loss and dysfunction of ependymal cells has been linked to hydrocephalus formation in mice and humans. Current treatment of hydrocephalus only partially relieves symptoms, leaving the disease basically untreated. Recent findings identify GemC1/Lynkeas and McIdas as central regulators of ependymal cell fate commitment and differentiation, while mutations in GemC1/Lynkeas and McIdas have been associated with hydrocephalus in humans. The goal of this project is to provide evidence for novel directions on hydrocephalus treatment. Researchers will assess the ability of GemC1/Lynkeas and McIdas to induce direct cellular reprogramming toward the ependymal lineage in cells lining the wall of hydrocephalic mouse models. A genetic mouse model of hydrocephalus established in the laboratory and a mouse model of intracranial hemorrhage will be used toward this direction.

Previously, this group showed that iron plays a key role in the development of hydrocephalus and neuronal cell death after intraventricular hemorrhage. However, the mechanism by which iron enters ependymal and choroid plexus cells in the brain to cause this damage remains unknown. This project will determine the mechanism of iron entry into these critical cell types, which will allow for the development of directed treatments to inhibit cellular iron entry, preventing neuronal damage and hydrocephalus. (Note: This investment resulted in a $2.4 million follow-up grant from the NIH!)

Disruption of the ventricular zone (VZ)—the layer of cells lining the brain's ventricles—is a fundamental step in the development of post-hemorrhagic hydrocephalus (PHH) in preterm infants. This group has shown that the cell junctions holding the VZ together break down in PHH, specifically that N-cadherin-based adherens junctions are compromised. Linked to this are a characteristic neuroinflammatory response, reactive astrocytosis, and resulting periventricular white matter injury. Compelling preliminary data implicate the sheddase ADAM10 in cutting N-cadherin and triggering this breakdown. This project tests two central hypotheses: (1) that ADAM10-mediated cleavage of N-cadherin is a fundamental trigger for VZ disruption and the development of PHH, and (2) that pharmacologically inhibiting ADAM10 will prevent PHH from developing. This highly innovative work provides the first steps toward defining the primary molecular mechanisms that lead to PHH.

Preliminary data indicated that TRPV4 antagonists ameliorate hydrocephalus in a rat model of Meckel Gruber Syndrome. The goals of this proposal were to: (1) determine if the efficacy is a class action of TRPV4 antagonists, (2) determine if TRPV4 antagonists are effective in another model of hydrocephalus representing a different species and different genetic mutation, and (3) use a continuous choroid plexus cell line to examine the effect of TRPV4 agonists and antagonists on transepithelial ion flux. Drug treatment was followed with state-of-the-art rodent MRI for quantification of ventricular volumes. The cell line was studied using well-characterized electrophysiological techniques. These studies formed the framework for future pharmacokinetic and pharmacodynamic testing of TRPV4 antagonists, and structural/functional studies linking changes in brain metabolism with behavioral changes. The proposed studies made a substantial contribution toward developing the first drug treatment for hydrocephalus. (Note: This grant resulted in a $1.3 million follow-up grant from the DOD in 2017 and another $11.3M in 2023!)

This study hypothesized that the peptide hormone augurin is produced and secreted by the choroid plexus epithelium, acts as a ligand for an unknown receptor, and has a critical function in CSF fluid homeostasis. If proven, researchers predicted that augurin could be manipulated pharmacologically to treat hydrocephalus.