Abstract
Apolipoprotein E (APOE) and Galectin-3 (Gal-3) are markers of activated microglia in neurodegenerative diseases of the central nervous system, whose targeting is protective in mouse models of glaucoma. In this study, we examined levels of APOE and Gal-3 in human aqueous humor (AH) and serum samples. Single-center, cross-sectional study. A total of 100 glaucoma and 110 control patients at Massachusetts Eye and Ear. We enrolled patients with various types and stages of glaucoma undergoing planned ophthalmic surgery as part of their routine care and compared them with patients without glaucoma undergoing phacoemulsification for age-related cataract. At the start of ophthalmic surgery, we collected AH and serum from 100 glaucoma and 110 control patients. APOE and Gal-3 levels were quantified by enzyme-linked immunosorbent assays. APOE and Gal-3 levels in AH and serum. APOE and Gal-3 levels were significantly elevated in the AH of glaucoma patients compared to controls (2.72 vs. 0.85 µg/ml, P < 0.0001 for APOE, and 2.89 vs. 1.45 ng/ml, P < 0.001 for Gal-3). A positive correlation was observed between AH APOE and Gal-3 levels in the glaucoma cohort (R = 0.44, P < 0.0001). While serum Gal-3 levels were similar between groups (25.5 vs. 25.7 ng/ml, P = 0.92), APOE levels were significantly elevated in the serum of glaucoma patients compared to controls (58.7 vs. 30.2 µg/ml, P < 0.0001). Serum APOE levels were not correlated with AH APOE levels in either the glaucoma or the control groups (both R ~ 0, P > 0.05) or dependent on APOE genotype. Our findings demonstrate that AH Gal-3 and APOE are elevated in patients with glaucoma. In contrast, only serum APOE was elevated in our glaucoma cohort, possibly reflecting the known dysregulation of lipid metabolism that occurs in this disease.
Similar content being viewed by others
Data availability
The datasets generated and/or analysed during the current study are not publicly available because they contain patient protected health information but are available in de-identified form from the corresponding author on reasonable request.
References
Soto, I. & Howell, G. R. The complex role of neuroinflammation in glaucoma. Cold Spring Harb Perspect. Med. 4 (8), a017269 (2014).
Zeng, H. L. & Shi, J. M. The role of microglia in the progression of glaucomatous neurodegeneration- a review. Int. J. Ophthalmol. 11, 143–149 (2018).
Wei, X., Cho, K. S., Thee, E. F., Jager, M. J. & Chen, D. F. Neuroinflammation and microglia in glaucoma: time for a paradigm shift. J. Neurosci. Res. 97, 70–76 (2019).
Bosco, A. et al. Complement C3-targeted gene therapy restricts onset and progression of neurodegeneration in chronic mouse glaucoma. Mol. Ther. 26, 2379–2396 (2018).
Chidlow, G., Ebneter, A., Wood, J. P. & Casson, R. J. Evidence supporting an association between expression of major histocompatibility complex II by microglia and optic nerve degeneration during experimental glaucoma. J. Glaucoma. 25, 681–691 (2016).
Bosco, A. et al. Reduced retina microglial activation and improved optic nerve integrity with minocycline treatment in the DBA/2J mouse model of glaucoma. Invest. Ophthalmol. Vis. Sci. 49, 1437–1446 (2008).
Cueva Vargas, J. L., Belforte, N. & Di Polo, A. The glial cell modulator ibudilast attenuates neuroinflammation and enhances retinal ganglion cell viability in glaucoma through protein kinase A signaling. Neurobiol. Dis. 93, 156–171 (2016).
Liu, X. et al. The effect of A2A receptor antagonist on microglial activation in experimental glaucoma. Invest. Ophthalmol. Vis. Sci. 57, 776–786 (2016).
Krasemann, S. et al. The TREM2-APOE pathway drives the transcriptional phenotype of dysfunctional microglia in neurodegenerative diseases. Immunity 47, 566–581e569 (2017).
Keren-Shaul, H. et al. A unique microglia type associated with restricting development of Alzheimer’s disease. Cell 169, 1276–1290e1217 (2017).
Butovsky, O. & Weiner, H. L. Microglial signatures and their role in health and disease. Nat. Rev. Neurosci. 19, 622–635 (2018).
Marschallinger, J. et al. Lipid-droplet-accumulating microglia represent a dysfunctional and proinflammatory state in the aging brain. Nat. Neurosci. 23, 194–208 (2020).
Margeta, M. A. et al. Apolipoprotein E4 impairs the response of neurodegenerative retinal microglia and prevents neuronal loss in glaucoma. Immunity 55, 1627–1644e1627 (2022).
Omodaka, K. et al. Neuroprotective effect against axonal damage-induced retinal ganglion cell death in apolipoprotein E-deficient mice through the suppression of kainate receptor signaling. Brain Res. 1586, 203–212 (2014).
Corder, E. H. et al. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer’s disease in late onset families. Science 261 (5123), 921–923 (1993).
Margeta, M. A. et al. Association of APOE with primary open-angle glaucoma suggests a protective effect for APOE epsilon4. Invest. Ophthalmol. Vis. Sci. 61 (8), 3 (2020).
Lam, C. Y. et al. Association of apolipoprotein E polymorphisms with normal tension glaucoma in a Chinese population. J. Glaucoma. 15, 218–222 (2006).
Mabuchi, F. et al. The apolipoprotein E gene polymorphism is associated with open angle glaucoma in the Japanese population. Mol. Vis. 11, 609–612 (2005).
Tudorache, I. F., Trusca, V. G., Gafencu, A. V., Apolipoprotein, E. & - A Multifunctional Protein with Implications in Various Pathologies as a Result of Its Structural Features. Comput. Struct. Biotechnol. J. 15, 359–365. https://doi.org/10.1016/j.csbj.2017.05.003 (2017).
Tzioras, M., Davies, C., Newman, A., Jackson, R. & Spires-Jones, T. Invited Review: APOE at the interface of inflammation, neurodegeneration and pathological protein spread in Alzheimer’s disease. Neuropathol. Appl. Neurobiol. 45 (4), 327–346. https://doi.org/10.1111/nan.12529 (2019).
Arnaud, L. et al. APOE4 drives inflammation in human astrocytes via TAGLN3 repression and NF-κB activation. Cell Rep. 40 (7), 111200 https://doi.org/10.1016/j.celrep.2022.111200 (2022).
Iannucci, J., Sen, A. & Grammas, P. Isoform-specific effects of apolipoprotein E on markers of inflammation and toxicity in brain glia and neuronal cells in vitro. Curr. Issues Mol. Biol. 43 (1), 215–225. https://doi.org/10.3390/cimb43010018 (2021).
Lee, S. et al. APOE modulates microglial immunometabolism in response to age, amyloid pathology, and inflammatory challenge. Cell. Rep. 42 (3), 112196 (2023).
Giau, V. V., Bagyinszky, E., An, S. S. & Kim, S. Y. Role of apolipoprotein E in neurodegenerative diseases. Neuropsychiatr Dis. Treat. 11, 1723–1737 (2015).
Marais, A. D. Apolipoprotein E in lipoprotein metabolism, health and cardiovascular disease. Pathology 51, 165–176 (2019).
Martinez-Martinez, A. B. et al. Beyond the CNS: the many peripheral roles of APOE. Neurobiol. Dis. 138, 104809 (2020).
Boza-Serrano, A. et al. Galectin-3, a novel endogenous TREM2 ligand, detrimentally regulates inflammatory response in Alzheimer’s disease. Acta Neuropathol. 138, 251–273 (2019).
Siew, J. J. et al. Galectin-3 is required for the microglia-mediated brain inflammation in a model of Huntington’s disease. Nat. Commun. 10, 3473 (2019).
Jiang, H. R. et al. Galectin-3 deficiency reduces the severity of experimental autoimmune encephalomyelitis. J. Immunol. 182, 1167–1173 (2009).
Abreu, C. A., De Lima, S. V., Mendonca, H. R., Goulart, C. O. & Martinez, A. M. Absence of galectin-3 promotes neuroprotection in retinal ganglion cells after optic nerve injury. Histol. Histopathol. 32, 253–262 (2017).
Hirani, N. et al. Target inhibition of galectin-3 by inhaled TD139 in patients with idiopathic pulmonary fibrosis. Eur. Respir J. 57 (5), 2002559 (2021).
Mackinnon, A. C. et al. Regulation of transforming growth factor-beta1-driven lung fibrosis by galectin-3. Am. J. Respir Crit. Care Med. 185, 537–546 (2012).
Delaine, T. et al. Galectin-3-binding glycomimetics that strongly reduce bleomycin-induced lung fibrosis and modulate intracellular glycan recognition. Chembiochem 17, 1759–1770 (2016).
Rombaut, A., Brautaset, R., Williams, P. A. & Tribble, J. R. Intravitreal injection of the Galectin-3 inhibitor TD139 provides neuroprotection in a rat model of ocular hypertensive glaucoma. Mol. Brain. 17 (1), 84. https://doi.org/10.1186/s13041-024-01160-z (2024).
Pitts, K. M. et al. Solá-Del Valle DA. Neurodegeneration markers Galectin-3 and apolipoprotein E Are elevated in the aqueous humor of eyes with glaucoma. Transl Vis. Sci. Technol. 11 (11), 1 (2022).
Lin, J. B. et al. Solá-Del Valle D. Neurofilament light chain in aqueous humor as a marker of neurodegeneration in glaucoma. Clin. Ophthalmol. 17, 2209–2217 (2023).
Lin, J. B. et al. Evaluation of serum and aqueous humor neurofilament light chain as markers of neurodegeneration in glaucoma. Transl Vis. Sci. Technol. 14 (2), 24. https://doi.org/10.1167/tvst.14.2.24 (2025).
Champely, S. & Pwr Basic functions for power analysis. https://CRAN.R-project.org/package=pwr (2020).
American Academy of Ophthalmic Executives. Glaucoma ICD-10-CM Quick Reference Guide (American Glaucoma Society and American Academy of Ophthalmology, 2020).
Margeta, M. A. et al. Association of APOE with primary open-angle glaucoma suggests a protective effect for APOE ε4. Invest. Ophthalmol. Vis. Sci. 61 (8), 3. https://doi.org/10.1167/iovs.61.8.3 (2020).
Woltsche, N. et al. Neurofilament light chain: a new marker for neuronal decay in the anterior chamber fluid of patients with glaucoma. Br. J. Ophthalmol. 107 (10), 1432–1437. https://doi.org/10.1136/bjo-2021-320828 (2023).
Wilson, S. et al. Correlation of aqueous, vitreous, and serum protein levels in patients with retinal diseases. Transl Vis. Sci. Technol. 12 (11), 9 (2023).
Godfrey, C. et al. Obesity and fat metabolism in human immunodeficiency virus-infected individuals: Immunopathogenic mechanisms and clinical implications. J. Infect. Dis. 220 (3), 420–431. https://doi.org/10.1093/infdis/jiz118 (2019).
Madjedi, K. M. et al. The association between serum lipids and intraocular pressure in 2 large United Kingdom cohorts. Ophthalmology 129 (9), 986–996 (2022).
Shao, M., Li, Y., Teng, J., Li, S. & Cao, W. Association between serum lipid levels and patients with primary angle-closure glaucoma in China: A cross sectional, case-control study. Front. Med. (Lausanne). 8, 618970. https://doi.org/10.3389/fmed.2021.618970 (2021).
Wang, S., Bao, X. & Hyperlipidemia blood lipid level, and the risk of glaucoma: A meta-analysis. Invest. ophthalmol. Vis. Sci. 60 (4), 1028–1043. https://doi.org/10.1167/iovs.18-25845 (2019).
Zeleznik, O. A. et al. Plasma metabolite profile for primary open-angle glaucoma in three US cohorts and the UK Biobank. Nat. Commun. 14 (1), 2860. https://doi.org/10.1038/s41467-023-38466-w (2023).
Sumer, F., Subasi, S., Bahceci, I. & Satilmaz, F. Evaluation of serum galectin-3 concentration as a potential biomarker in exudative-type age-related macular degeneration. Sci. Rep. 14 (1), 31957. https://doi.org/10.1038/s41598-024-83499-w (2024).
Funding
M.A.M. was supported by NIH/NEI R01EY035312, the Glaucoma Research Foundation Catalyst for a Cure Award, the Melza M. and Frank Theodore Barr Foundation, the Research to Prevent Blindness Career Development Award, the Alcon Research Institute Young Investigator Award, the Massachusetts Lions Eye Research Fund, the Robert M. Sinskey, MD, Foundation, the Ruettgers Family Charitable Foundation, and the B.L. Manger Foundation. D.S. was supported by donations from Joseph and Cathey Leitch; Chad and Anne Gifford; Stephen Traynor; the Robert M. Sinskey MD Foundation; and Maureen and Michael Ruettgers.
Author information
Authors and Affiliations
Contributions
Conceptualization: El Helwe, Solá-Del Valle, Margeta, Sample Collection: Solá-Del Valle, Margeta, Vasan, Song, Lo, Meeker, Wang, El Helwe, Falah, Investigation: El Helwe, Falah, Baldwin, Xue, Writing—Original Draft: El Helwe, Writing—Review & Editing: El Helwe, Margeta, Solá-Del Valle, Funding Acquisition: Margeta, Solá-Del Valle.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
El Helwe, H., Falah, H., Xue, Y. et al. The utility of aqueous and serum apolipoprotein E and galectin-3 as biomarkers of neuroinflammation in glaucoma. Sci Rep (2026). https://doi.org/10.1038/s41598-026-45007-0
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-45007-0
