CD38 Enzyme Emerges as Key Target for Protecting Vision in Glaucoma
New research reveals how blocking CD38 boosts NAD+ levels, protecting retinal cells and offering a fresh therapeutic angle on glaucoma.
Summary
Glaucoma, a leading cause of irreversible blindness, is linked to the degeneration of retinal ganglion cells (RGCs) and mitochondrial dysfunction. This review highlights the CD38/NAD+ axis as a critical pathway in glaucoma progression. CD38, an enzyme that rises with age, depletes NAD+ — a molecule essential for cellular energy and neuroprotection. When CD38 is inhibited, NAD+ levels rise, activating protective enzymes like Sirt1 that shield RGCs from damage. Animal studies show that supplementing NAD+ precursors such as nicotinamide can slow glaucoma progression. The authors argue this axis represents a promising but underexplored therapeutic target, though challenges around drug selectivity and efficacy validation remain.
Detailed Summary
Glaucoma affects millions worldwide and remains a leading cause of permanent vision loss. Unlike many conditions, the retinal damage it causes is irreversible, making early intervention and neuroprotection strategies critically important. This review focuses on a molecular pathway that has gained significant attention in both aging biology and neurodegeneration: the CD38/NAD+ axis.
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme central to energy metabolism, DNA repair, and cellular signaling. Its decline with age is increasingly recognized as a driver of mitochondrial dysfunction and tissue degeneration. CD38, an NAD+-consuming enzyme, is expressed in retinal and immune cells and its activity tends to increase with age — accelerating NAD+ depletion and worsening cellular stress responses.
In glaucoma specifically, the review details how CD38 modulates oxidative stress, inflammation, and apoptosis by regulating NAD+ availability. When CD38 is inhibited or genetically absent in animal models, NAD+ levels recover, leading to enhanced activity of NAD+-dependent enzymes such as Sirt1. This translates into measurable neuroprotection: RGCs are better preserved, and retinal ischemia-reperfusion injury is reduced.
The authors also highlight NAD+ precursor supplementation — particularly nicotinamide — as a practical strategy already showing promise in animal models for delaying glaucoma progression. This approach aligns with broader longevity research exploring NAD+ restoration as a means to counter age-related cellular decline.
Despite exciting preclinical results, the review acknowledges significant hurdles. Current CD38 inhibitors face questions around selectivity and off-target effects. Clinical translation requires better understanding of how this axis behaves specifically within retinal tissue. The authors call for targeted mechanistic studies and rigorous efficacy trials before therapeutic applications can be realized.
Key Findings
- CD38 expression increases with age, depleting NAD+ and accelerating retinal ganglion cell degeneration in glaucoma.
- Inhibiting or deleting CD38 in animal models elevates NAD+ and activates Sirt1, protecting RGCs from injury.
- NAD+ precursor supplementation (e.g., nicotinamide) delays glaucoma progression in preclinical studies.
- The CD38/NAD+ axis regulates oxidative stress, inflammation, and apoptosis in retinal tissue.
- Drug selectivity and clinical validation remain key obstacles to therapeutic use of CD38 inhibitors.
Methodology
This is a narrative review synthesizing existing preclinical and mechanistic literature on the CD38/NAD+ axis in glaucoma. No original experimental data were generated; findings are drawn from animal models and in vitro studies reported in prior publications. The review does not include clinical trial data.
Study Limitations
The review is based primarily on animal and cell-culture studies, limiting direct applicability to human glaucoma patients. Current CD38 inhibitors lack sufficient selectivity, raising concerns about systemic side effects. The precise mechanistic role of the CD38/NAD+ axis within human retinal tissue has not yet been fully characterized.
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