Human T cell leukemia virus type 1, the first human retrovirus ever identified, infects an estimated 5 to 10 million people worldwide, a figure extrapolated from surveys covering only about one-seventh of the global population. The virus inserts a DNA copy of its RNA genome into the chromosomes of host T cells, establishing a lifelong infection that can drive a spectrum of diseases, including adult T cell leukemia/lymphoma, HTLV-1-associated myelopathy, and HTLV-1-associated uveitis, a chronic inflammation inside the eye that is particularly common in endemic regions such as Japan. Despite the scale of the problem, coordinated global action has been slow; the World Health Organization only published technical reports aimed at reducing HTLV-1-related morbidity and mortality in 2021, and no broadly effective intervention has emerged in decades of research.

Current treatment for the ocular disease relies heavily on corticosteroids, delivered as topical drops, injections into the eye, or oral prednisone. This approach has serious shortcomings. Studies indicate that 30 to 60 percent of patients with HTLV-1-associated uveitis experience recurrent episodes, and long-term steroid exposure can trigger cataracts, glaucoma, macular edema, epiretinal membranes, retinal degeneration, optic nerve atrophy, and bullous keratopathy. Most importantly, corticosteroids suppress inflammation without reducing the number of virus-infected cells or halting disease progression. Newer molecular targeted agents, including the anti-CCR4 antibody mogamulizumab and the immunomodulatory drug lenalidomide, have been explored, but treatment-related inflammation and adverse effects remain significant obstacles. This therapeutic gap motivated a team led by Yaru Zou and Koju Kamoi of Tokyo Medical and Dental University to investigate whether an epigenetic drug already approved for blood cancer could address the root of the ocular inflammation.

The drug in question is valemetostat, marketed as EZHARMIA, a dual inhibitor of the enzymes EZH1 and EZH2 that was approved in 2022 for adult T cell leukemia/lymphoma. Both enzymes are the catalytic components of polycomb repressive complex 2, a molecular machine that silences genes by adding three methyl groups to lysine 27 on histone H3, producing the repressive chromatin mark known as H3K27me3. Previous work had shown that EZH1 and EZH2 are overexpressed, and H3K27me3 deposition increased, in ATL cells and in cells expressing the viral oncoprotein Tax. Dual EZH1/2 inhibitors have also been reported to curb the spontaneous proliferation and exaggerated immune responses of HTLV-1-infected cells in patients with HTLV-1-associated myelopathy. What remained unknown was whether such inhibition could benefit the inflamed eye.

To find out, the researchers built a series of laboratory models centered on ARPE-19 cells, a human retinal pigment epithelial cell line chosen because the retinal pigment epithelium forms the outer blood-retinal barrier and governs retinal immune homeostasis. They exposed these ocular cells to three kinds of T cells: MT-2 cells, which carry transcriptionally active HTLV-1 and express the viral protein Tax; TL-Om1 cells, an ATL-derived line in which the virus is largely silent and Tax is low or absent; and Jurkat cells, which are uninfected and served as controls. In parallel, they treated the T cell lines themselves. Western blotting and quantitative PCR revealed that HTLV-1 infection drove significant upregulation of both EZH1 and EZH2, along with elevated H3K27me3, in infected retinal pigment epithelial cells and in MT-2 cells, with EZH1 protein rising roughly 2.5-fold in infected ocular cells and six-fold in MT-2 cells. This was the first demonstration that HTLV-1 infection induces polycomb-mediated epigenetic changes in retinal cells.

The team then treated the models with valemetostat at 0.01, 0.1, and 1 micromolar for 96 hours, concentrations selected in preliminary experiments because they harmed infected T cells while leaving normal ocular cells, including primary human trabecular meshwork cells, unaffected below 10 micromolar. The results were strikingly dependent on the model. In co-cultures of retinal cells with Tax-positive MT-2 cells, and in retinal cells directly infected with HTLV-1, the drug produced modest but statistically significant reductions in cell viability at the highest dose, accompanied by small increases in late-stage apoptosis. No such effects appeared in co-cultures with TL-Om1 or Jurkat cells. Crucially, the absolute magnitude of apoptosis remained limited, typically only 1 to 3 percent above baseline, indicating that valemetostat is not broadly toxic to retinal cells, an important safety consideration given their role in maintaining vision.

The virological findings were equally nuanced. Valemetostat did not significantly reduce the HTLV-1 proviral load in co-culture systems or in directly infected retinal pigment epithelial cells. However, in MT-2 cells themselves, 1 micromolar valemetostat significantly lowered proviral load and suppressed the messenger RNA levels of both Tax and HBZ, the two hallmark transcripts of the virus. Because MT-2 cells represent the transcriptionally active, highly infectious state of HTLV-1, while TL-Om1 represents latency, the results suggest that the drug’s antiviral effect is gated by the transcriptional status of the infected cell. Within the four-day treatment window, the authors conclude, valemetostat’s benefit to the ocular environment is likely indirect, acting primarily by quieting the most virally active cells rather than by eradicating provirus everywhere.

The most clinically relevant effects emerged in the inflammatory readouts. HTLV-1-infected T cells recovered from the eyes of patients with uveitis are known to secrete copious interleukin-6, interleukin-8, and interleukin-10, all implicated in disease. In the new study, valemetostat produced a dose-dependent increase in the anti-inflammatory cytokine IL-10 in MT-2-containing conditions, significant at 1 micromolar in the co-culture system and across all doses in MT-2 cells. This fits a mechanistic expectation: blocking EZH1/2 removes H3K27me3 marks that repress the IL-10 gene, and prior genetic studies showed that loss of EZH2 directly activates IL-10 transcription in several CD4-positive T cell subsets. Meanwhile, pro-inflammatory signals fell in a context-dependent pattern. IL-12p70 and the chemokine CXCL-10 dropped in co-cultures, IL-6 and IL-8 declined mainly in MT-2 cells, and CCL-2 fell at low doses in the MT-2 co-culture, whereas the chemokine CCL-5 was unchanged in every model.

The drug’s influence on NF-kappaB, the central inflammatory pathway that Tax hijacks to drive both viral replication and cytokine production, was more subdued. Valemetostat modestly reduced NF-kappaB p65 phosphorylation in the MT-2 co-culture at the lowest dose and slightly decreased the nuclear-to-cytoplasmic ratio of p65 in retinal cells stimulated with TNF-alpha, but it did not abolish nuclear translocation. The authors attribute this to the overwhelming strength of Tax-driven NF-kappaB activation, which a 96-hour course of EZH1/2 inhibition may be insufficient to counteract, and to the fact that NF-kappaB and cytokine networks are regulated by many factors beyond polycomb complexes. Immunofluorescence confirmed that valemetostat significantly lowered H3K27me3 in retinal cells exposed to MT-2 cells or directly infected, but not in cells co-cultured with TL-Om1 or Jurkat cells, again underscoring the model dependence of the epigenetic response.

The study also carries a cautionary note about IL-10. Although the cytokine is anti-inflammatory, it can promote the survival of HTLV-1-infected T cells and facilitate immune evasion by impairing dendritic cell antigen presentation and downregulating MHC class I molecules, and patients with aggressive ATL often show abnormally elevated IL-10. The authors therefore suggest that combining EZH1/2 inhibition with IL-10 pathway blockade could prove more effective, noting evidence that IL-10 neutralization sensitizes ATL cells to standard therapies. In the TL-Om1 model of ATL-related ocular infiltration, valemetostat failed to reduce H3K27me3, proviral load, or NF-kappaB activation within the malignant cells, yet it suppressed TL-Om1-induced CXCL10 secretion and induced dose-dependent apoptosis, pointing to a benefit mediated through the inflammatory microenvironment rather than direct tumor killing.

The authors are candid about the limitations. The work relied entirely on in vitro co-cultures and established cell lines, which cannot reproduce the blood-retinal barrier, retinal architecture, or local immune regulation of a living eye, and the intraocular pharmacokinetics of valemetostat after systemic administration remain undefined. Sex as a biological variable could not be assessed because donor-defined primary cells were not used. Even so, the findings establish a proof of concept that an approved epigenetic therapy can counteract HTLV-1-induced chromatin changes in retinal cells, dampen viral transcription in the most active infected cells, and reshape the cytokine milieu that sustains uveitis. Longer treatment studies, in vivo models, and patient-derived systems will be needed to determine whether these modest, context-dependent effects can be translated into a genuine steroid-sparing therapy for one of the most burdensome manifestations of a virus that medicine has long neglected.

Subject of Research: EZH1/2-targeted epigenetic therapy with valemetostat for HTLV-1-associated uveitis

Article Title: Dual impact of EZH1/2-targeted therapy in HTLV-1-associated inflammation: Direct and indirect mechanisms

Article References: Zou, Y., Kamoi, K., Yang, M., Zong, Y., Zhang, J., & Ohno-Matsui, K. (2026). Dual impact of EZH1/2-targeted therapy in HTLV-1-associated inflammation: Direct and indirect mechanisms. iScience, 29(11), Article 117775. https://doi.org/10.1016/j.isci.2026.117775

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117775

Keywords: HTLV-1, valemetostat, EZH1, EZH2, H3K27me3, uveitis, epigenetics, PRC2, Tax, IL-10, NF-kappaB, retinal pigment epithelium

Fuchs endothelial corneal dystrophy, a progressive disorder that can gradually cloud the cornea and impair vision, may be driven by a cellular process more complex than simple cell loss. A new study published in Cell Death Discovery reports that ultraviolet-A light can induce chronic hyperploidization in corneal endothelial cells, triggering changes associated with fibrosis. The findings connect long-term genome abnormalities in post-mitotic cells to the structural deterioration observed in this increasingly recognized eye disease.

The cornea depends on a thin inner layer of endothelial cells to maintain its transparency. These cells regulate the movement of fluid between the cornea and the anterior chamber of the eye, preventing the tissue from becoming waterlogged. Unlike many cell types, human corneal endothelial cells have limited ability to divide and replenish themselves. When they are damaged or lost, neighboring cells may enlarge and stretch to cover the affected area, but this compensation has limits. In Fuchs endothelial corneal dystrophy, the endothelial layer progressively becomes dysfunctional, allowing fluid accumulation and producing corneal swelling, haze and visual distortion.

The study focuses on hyperploidization, a condition in which cells acquire extra sets or copies of chromosomes. In a healthy cell cycle, DNA is replicated and then evenly distributed when a cell divides. Post-mitotic cells, however, are not expected to continue cycling through repeated rounds of DNA replication. If DNA replication occurs without successful cell division, the result can be a cell with an enlarged genome and multiple chromosome sets. This state, known as polyploidy or hyperploidization depending on its extent and context, can alter cell size, metabolism, gene activity and responses to stress.

The researchers investigated how ultraviolet-A, or UVA, light affects cells associated with Fuchs endothelial corneal dystrophy. UVA has a longer wavelength than ultraviolet-B and can penetrate biological tissues more deeply. Although the eye possesses protective mechanisms, persistent or excessive exposure to light-generated stress can damage cellular components, including DNA, proteins and mitochondria. The study indicates that UVA exposure does not merely cause an acute injury that cells either repair or fail to survive. Instead, it can establish a chronic hyperploid state in cells that no longer divide normally.

That distinction is important because a cell can remain alive while becoming increasingly dysfunctional. Hyperploid cells may continue to produce proteins, communicate with neighboring cells and modify their surrounding environment, even as their enlarged genomes disrupt normal regulation. In the corneal endothelium, such persistent abnormalities could interfere with the machinery responsible for maintaining fluid balance and tissue transparency. The research links this long-lasting cellular state to the activation of fibrotic processes, suggesting that damaged endothelial cells may help remodel the cornea rather than simply disappearing.

Fibrosis is the formation or accumulation of excessive connective-tissue components, particularly extracellular matrix proteins such as collagens. During wound healing, matrix production can provide temporary structural support. When the response persists, however, the tissue can stiffen, become disorganized and lose its normal optical properties. In the context of Fuchs endothelial corneal dystrophy, fibrosis may contribute to the loss of corneal clarity and the progression of visual impairment. The study’s central message is that chronic hyperploidization may act as an upstream signal that pushes post-mitotic cells toward this pathological remodeling.

The findings also help explain why a disease affecting a specialized, non-dividing cell population can progress over time. A conventional view of cellular damage often emphasizes apoptosis, necrosis or the gradual depletion of functional cells. The new work highlights another possibility: injured cells may survive in a permanently altered condition and actively influence disease progression. By retaining metabolic activity while carrying abnormal quantities of DNA, these cells could produce signals that encourage inflammation, matrix deposition or changes in the behavior of nearby cells.

The UVA connection raises questions about how environmental stress interacts with inherited susceptibility. Fuchs endothelial corneal dystrophy has genetic and age-related components, and the disease does not arise from a single universal cause. The study does not establish that UVA exposure alone causes the disorder, but it provides a mechanism through which light-associated stress could worsen cellular instability in vulnerable corneal tissue. This may help researchers examine whether cumulative exposure, cellular antioxidant capacity and pre-existing genetic changes combine to determine how rapidly the disease advances.

From a treatment perspective, the work points toward targets beyond replacing lost endothelial cells. Future strategies might seek to prevent abnormal DNA replication, stabilize genome integrity, suppress the fibrotic signals released by hyperploid cells or protect the corneal endothelium from chronic light-induced stress. Such approaches would require careful testing, because polyploidy can serve useful roles in some normal tissues, and broadly blocking cell-cycle or repair pathways could produce harmful effects. The challenge will be to distinguish pathological hyperploidization from adaptive genome changes that help cells survive.

The study ultimately presents Fuchs endothelial corneal dystrophy as a disease of cellular identity as well as cellular survival. UVA-induced chronic hyperploidization appears to place post-mitotic corneal endothelial cells in a persistent state of genomic imbalance, where they can contribute to fibrosis and tissue failure. By connecting light stress, abnormal DNA content and corneal scarring, the research offers a new framework for understanding why the disease can continue even after the initial injury has passed—and provides a potential roadmap for therapies designed to interrupt the process before vision is permanently compromised.

Subject of Research: Ultraviolet-A light-induced chronic hyperploidization and fibrosis in post-mitotic corneal endothelial cells affected by Fuchs endothelial corneal dystrophy

Article Title: Ultraviolet-A light-induced chronic hyperploidization causes fibrosis in post-mitotic cells affected by Fuchs endothelial corneal dystrophy

Article References: Adhikari, Y., Parekh, M., Deshpande, N. et al. Ultraviolet-A light-induced chronic hyperploidization causes fibrosis in post-mitotic cells affected by Fuchs endothelial corneal dystrophy. Cell Death Discov. (2026). https://doi.org/10.1038/s41420-026-03292-8

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41420-026-03292-8

Keywords: Fuchs endothelial corneal dystrophy, ultraviolet-A, UVA, hyperploidization, polyploidy, corneal endothelial cells, fibrosis, post-mitotic cells, genome instability, corneal disease

It’s the first potentially habitable world known to host an atmosphere, making it a lead contender in the search for life beyond our solar system.

Using spectral data from the Magellan Clay telescope at Las Campanas Observatory, astronomers detected helium escaping from LHS 1140b, a rocky exoplanet that orbits in the habitable zone of the nearby low-mass star LHS 1140.

The post Potential Atmosphere Detected on Habitable-Zone Exoplanet LHS 1140b appeared first on Sci.News: Breaking Science News.

Most of the gas in the Universe is a mixture of hydrogen and helium. It's thought that the initial atmospheres of most planets also start out that way. However, over billions of years, as planets evolve, the composition of their atmospheres may shift. Hydrogen can react with other chemicals, and both it and helium can be lost to space. Venus, Earth, and Mars are thought to have second atmospheres, with their original hydrogen/helium envelopes having been lost and/or transformed.

The dynamics of loss are complicated. Lighter elements are lost more easily, but hydrogen can be protected by being incorporated into molecules like methane and ammonia. The gravity of the body can help retain some molecules, and a magnetic field can limit radiation's ability to blast material out of the atmosphere. Proximity to a star will matter too, both because of the radiation it produces and because it can heat the atmosphere and expand it to where gravity's influence is less substantial.

Given all these complications, it can be difficult to know what to expect to find on exoplanets. But a study in Wednesday's issue of Nature describes observations of helium being lost from the atmosphere of an exoplanet orbiting the star LHS 1140, about 50 light-years away. Based on the rate at which the helium is being lost, we can infer something about the remaining atmosphere.

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