Shaffer Research Grants

Glaucoma and other optic nerve diseases cause vision loss when retinal ganglion cells (RGCs) are damaged and their long nerve fibers (axons) break down. Scientists have found ways to help these axons regrow but getting them to grow long enough to reconnect with the brain remains a major challenge. Our research aims to find new molecules that help axons regrow through different biological pathways than the ones already known. We believe that combining these new molecules with existing treatments could work better than using either alone. To test this idea, we will use a well-established mouse model of optic nerve injury. By combining drug-based treatments with gene therapy, we hope to protect RGCs, encourage axon regrowth, and move closer to developing new treatments for people with glaucoma and other optic nerve diseases—ultimately aiming to preserve and restore vision, and improve quality of life.

Glaucoma is a leading cause of blindness worldwide. It primarily affects retinal ganglion cells (RGCs), which transmit visual information from the eye to the brain via the optic nerve. In glaucoma, neuroinflammation plays a major role in vision loss and is driven by overactive astrocytes, a type of support cell in the retina. When these astrocytes become reactive, they contribute to the damage and death of RGCs. Our project explores the potential of a naturally occurring molecule called lipoxin B4 (LXB4) to counteract this harmful process. LXB4 is known for its anti-inflammatory properties, and we’ve found that it can protect RGCs by reducing inflammation and calming reactive astrocytes. LXB4 also lowers the production of harmful proteins like C3, which are linked to increased inflammation in the optic nerve. By reducing astrocyte overactivity and inflammation, LXB4 helps preserve RGCs, potentially preventing further vision loss. This research introduces a new approach to treating glaucoma by focusing on protecting retinal cells with anti-inflammatory strategies, rather than relying solely on reducing eye pressure. If successful, LXB4-based therapies could provide a new way to slow or stop glaucoma’s progression and help millions of people maintain their vision.

Glaucoma is a leading cause of blindness and lowering the pressure inside the eye is the main treatment. This pressure called intra-ocular pressure or IOP builds up when a part of the eye called the trabecular meshwork (TM) becomes diseased making it harder for fluid to drain. This research focuses on tiny molecules called microRNAs (miRNAs), which help control how genes are turned on and off in TM cells. These miRNAs affect how the TM works and how much fluid it lets through—both of which are key to keeping eye pressure at healthy levels. The research team will study cells from both healthy donors and people with glaucoma. They have already collected these cell samples and will compare how miRNAs and messenger RNAs (mRNAs) behave in both groups. This is important because miRNAs can control mRNAs, and together they may reveal the root causes of TM dysfunction in glaucoma. Using advanced analysis tools, the team will:

• Identify which miRNAs and mRNAs are different in glaucoma cells
• Discover how they interact
• Determine which biological pathways are affected
• Confirm key findings with further testing

This project brings together two experts: a cell biologist and a glaucoma specialist. Their goal is to uncover new biomarkers and potential treatment targets for glaucoma, which could eventually lead to new, more effective therapies based on miRNAs.

Glaucoma is a major cause of permanent vision loss. One key driver is high eye pressure, which is normally kept in a healthy range because a clear fluid (aqueous humor) drains through a tiny channel called Schlemm’s canal. With aging, this channel tends to become narrower—but it isn’t clear whether aging always raises eye pressure or how older eyes keep fluid moving. Our preliminary work shows that immune cells called macrophages gather around this drainage channel more in older eyes and make a signal called VEGFA. We don’t yet know if this response is helpful—supporting the channel and keeping pressure controlled—or harmful—contributing to blockage. In this project, we will (1) map where fluid flows and where macrophages are located in young and aged mouse eyes; (2) test whether macrophages in human and mouse tissue make more VEGFA with age; and (3) switch off VEGFA only in macrophages in mice to see how that affects the drainage channel and eye pressure. By revealing whether macrophage-derived VEGFA preserves or harms the drainage pathway, this work could point to new, targeted treatments—either boosting a protective response or blocking a harmful one. Our long-term goal is safer, more effective ways to control eye pressure and protect sight for people with glaucoma.

Glaucoma is a common and debilitating disease for which the major risk factors are aging and high eye pressure. Although more common in older people, children and young people can be severely affected by glaucoma related to genetic mutations. Despite recent great advances in identifying genetic associations with glaucoma, the precise roles that many of these gene variants play in eye structure and function remain poorly understood. This project will leverage cutting-edge technologies and newly developed mouse models to selectively “knock out” an understudied “glaucoma gene,” LTBP2 in the trabecular meshwork which is an eye tissue that is known to regulate fluid outflow from the eye. Our goal is to determine how LTBP2 impacts both eye development in babies and children and pressure regulation in the eyes of adults. Once validated, our mouse models will provide a valuable resource for many other investigators in the field. In turn, results of this study could lead to improved treatments for children with congenital and pediatric glaucoma as well as multiple forms of glaucoma in adults.

Glaucoma is a leading cause of irreversible blindness, characterized by progressive  loss of retinal ganglion cells (RGCs) and optic nerve degeneration. Mounting evidence implicates metabolic dysfunction and ischemia in disease progression. In contrast, mammalian hibernators such as the cone-dominant thirteen-lined ground squirrel  (TLGS) possess remarkable tolerance to ischemia and extreme metabolic suppression. These animals activate coordinated adaptive mechanisms that prevent irreversible retinal damage and permanent vision loss. This proposal seeks to harness these natural protective strategies to inform novel therapeutic approaches for glaucoma. Significance for people with glaucoma: If successful, this research could lead to a completely new class of treatments that go beyond lowering eye pressure. By mimicking the natural defenses of hibernating animals, we hope to develop therapies that directly protect the nerve cells of the eye and preserve vision. This approach has the potential to benefit people who continue to lose sight despite current treatments, offering new hope for preventing blindness from glaucoma.

Glaucoma is a leading cause of irreversible blindness characterized by the progressive death of retinal ganglion cells (RGCs). A growing body of evidence implicates a protein, Fas ligand (FasL), as a critical mediator of RGC death. However, FasL can be expressed as a membrane-bound protein (mFasL) or cleaved and released as a soluble protein (sFasL), with opposing biological effects. The mFasL protein induces cell death and inflammation, while the sFasL protein does not induce cell death or inflammation and can also block the effects of mFasL. In experimental glaucoma models, elevated pressure in the eye leads to increased expression of mFasL, resulting in increased activation of microglia, the resident immune cells of the retina, inflammation, and the death of RGCs. Conversely, overexpression of sFasL has been shown to protect RGCs and inhibit inflammation by reducing microglia activation. Therefore, a better understanding of the different signaling pathways induced by mFasL versus sFasL is crucial for elucidating the mechanisms underlying glaucomatous neurodegeneration. Using several mouse strains that differ in mFasL and sFasL expression, we will identify the sFasL-specific and mFasL-specific signaling pathways that regulate inflammation and cell death during the development of glaucoma. A better understanding of how changes in the natural balance of mFasL and sFasL contributes to the development of glaucoma will allow us to design new therapeutic strategies – such as enhancing sFasL or inhibiting mFasL – that may provide neuroprotection while minimizing inflammation. In addition, a clearer understanding of the dichotomy in FasL signaling could pave the way for more targeted interventions that preserve RGCs and prevent vision loss in glaucoma patients.

Glaucoma is a leading cause of irreversible blindness, and vision is lost when retinal ganglion cells (RGCs), the nerve cells that connect the eye to the brain, degenerate. Current treatments mainly lower eye pressure, but many patients continue to lose vision, suggesting other disease processes are at work. One promising area of research is how the supporting immune cells in the optic nerve, called microglia, respond to changes in the tissue environment. In glaucoma, the optic nerve head becomes stiffer with age and disease, but it is not known how this stiffness affects microglia and whether their response contributes to further damage of RGCs. In this project, we will use human induced pluripotent stem cells (iPSCs) to grow both microglia and RGCs in advanced 3D microfluidic culture systems that mimic the optic nerve environment. By adjusting the stiffness of these cultures, we will test whether microglia become more inflammatory under “glaucoma-like” conditions and whether this, in turn, harms RGCs. This work will provide new insight into how changes in the optic nerve environment drive inflammation and nerve damage in glaucoma. Understanding these processes is an important step toward identifying new treatment strategies that go beyond lowering eye pressure, with the goal of protecting vision and improving quality of life for people with glaucoma.

Over a third of patients with glaucoma have vision loss from degeneration of their optic nerves that does not result from high eye pressure. While our current therapies targeting high eye pressure can be beneficial in some of these cases, many patients continue to lose vision despite good eye pressure control. Developing therapies that target other pathways in optic nerve survival are thus critical. One of the best ways to do this is by identifying new genetic mechanisms for glaucoma and identifying how they lead to glaucoma. This allows us to both improve our ability to diagnose and monitor disease progress in glaucoma and to find new drug targets for cases not responding to therapy. We recently identified a new gene mutation that is present in a large family with early onset normal pressure glaucoma, and our goal for this proposal is to establish this as a new disease gene. The gene functions as a chaperone protein complex and regulates a key signaling pathway that has already been linked to glaucoma. In this proposal, our first major goal is to determine the molecular consequences of these gene variants on the function of the chaperone complex and downstream gene expression using cell-based model. Our second aim is to evaluate the contribution of this gene and other complex members to early onset forms of glaucoma, with a special focus on those resulting from normal eye pressure. We will use existing whole genome sequencing data from a cohort of 133 families with early onset glaucoma, along with evaluation of biobank genetic data and clinical information available at the University of Michigan and from the UK Biobank to evaluate representation from these genes. The results from this proposal will establish chaperone proteins as a new molecular class of variants implicated as strong risk factors for glaucoma and inform the specific molecular pathways that they may regulate. In turn, these will provide a new pathway to target for glaucoma therapies.

This research project will develop and validate a mouse model of Selective Laser Trabeculoplasty (SLT), a first-line treatment for reducing intraocular pressure (IOP) in patients with glaucoma. To better study SLT’s mechanism of action and explore new ways to make it more effective, we need a reliable and reproducible model in the laboratory. Our project aims to develop a mouse model of SLT using a non-contact laser approach allowing us to deliver the laser through the sclera, in a way that closely mimics the clinical procedure. Once the model is validated, it will provide a powerful tool for researchers to investigate how SLT works, ultimately guiding the identification of new therapeutic targets and approaches to improve glaucoma laser technology to lower IOP.

This project seeks to develop cell replacement approaches for retinal ganglion cells. Glaucoma is characterized by degeneration of retinal ganglion cells and eventual loss of vision. At late-stage neurodegeneration there are no options to restore lost vision. Our work provides a novel strategy to replace these neurons by reprogramming retinal glia cells to become neural progenitors capable of regenerating functional neurons. In regenerative species such as zebrafish, glia can regenerate a fully functional retina capable of restoring vision even after full retinal ganglion cell destruction. We have made strides to recapitulate this regenerative phenomenon in mouse. We have developed animal models in which retinal ganglion-like cells can be regenerated in response to acute retinal injury. While these studies represent exciting proof-of-principle for glia-mediated cell replacement, key questions remain. Importantly, we have yet to test our glia-to-neuron regeneration methods in a mouse model of glaucoma where neurodegeneration is slow and chronic. This project will address the feasibility of glia-mediated regeneration in a mouse model of glaucomatous neurodegeneration.

Glaucoma is a leading cause of blindness affecting millions worldwide. It occurs when the optic nerve, which connects the eye to the brain, is damaged and can no longer carry visual information. Current treatments lower eye pressure, which helps slow the disease, but many people continue to lose vision despite therapy. Our project focuses on a different target — a protein called elastin, which normally gives eye tissues flexibility and helps maintain healthy blood flow. With aging and high eye pressure, elastin breaks down and becomes stiff, triggering inflammation and nerve damage. We will test a new therapy that uses nanoparticles carrying a natural compound, pentagalloyl glucose (PGG), which binds to and stabilizes elastin. By protecting elastin, we hope to keep eye tissues flexible, reduce harmful inflammation, and ultimately prevent nerve cell loss. If successful, this approach could open an entirely new way to treat glaucoma, offering hope to patients who still lose vision even after pressure-lowering treatments.