Commentary
Abstract
Uniform radiation therapy (RT) de-escalation in HPV+ oropharyngeal squamous cell carcinoma (OPSCC) has underperformed in clinical trials, likely due to underlying genomic heterogeneity. In this issue of the JCI, Ho et al. evaluated genomic adjusted radiation dose (GARD), which integrates tumor gene expression with RT dose to estimate biological effect. In 191 locoregionally advanced HPV+ OPSCC patients treated with definitive RT with or without chemotherapy, GARD values varied widely, despite uniform dose delivery, and independently predicted overall survival. These data support a genomically informed framework specific for HPV+ OPSCC patients via GARD for guiding radiation dose de-escalation strategies.
Authors
Sandip K. Rath, David S. Yu
Abstract
The numbers of insulin-producing β cells in the pancreas are reduced in people with type 1 or type 2 diabetes, prompting efforts to replace these missing or lost β cells through transplant or regenerative medicine approaches. In this issue of the JCI, Wortham et al. describe a function for the deacetylase enzyme sirtuin 2 (SIRT2) in a novel pathway that acts as a brake on β cell proliferation. They show that inhibiting SIRT2 through pharmacologic or genetic approaches can induce human and mouse β cells to reenter a proliferative cell cycle. A surprising observation that remains unexplained is that the main targets of SIRT2 are mitochondrial oxidative phosphorylation (OxPhos) enzymes. It also remains unknown if and how these unanticipated acetylated OxPhos targets lead to cell-cycle entry. SIRT2 inhibitors will be a welcome addition to the growing repertoire of human β cell–regenerative drugs.
Authors
Liora S. Katz, Donald K. Scott, Andrew F. Stewart
Abstract
Lipids, which constitute half of the brain’s solid matter, are essential for forming specialized membranes of neural cells, providing energy sources, and facilitating cell-to-cell communication. Although the blood-brain barrier restricts lipid movement between peripheral circulation and the brain, multiple mechanisms supply the building blocks necessary to synthesize the diverse lipid species present in the central nervous system (CNS). In this issue of the JCI, Song et al. characterize specialized microvascular niches that metabolize circulating triglyceride-rich lipoproteins (TRLs) to deliver fatty acids into the brain. They located GPIHBP1, an essential chaperone for lipoprotein lipase (LPL) in the fenestrated endothelial cells of the choroid plexus (ChP) and circumventricular organs (CVOs), demonstrating lipolytic processing of peripheral TRLs and brain uptake of fatty acids. This advance implicates the GPIHBP1/LPL lipid metabolic hub in supporting the roles of the ChP and CVO in cerebrospinal fluid composition, immunity, satiety, thirst, and metabolic homeostasis.
Authors
A. Dushani Ranasinghe, Timothy Hla
Abstract
The hallmark feature of metabolic dysfunction-associated steatotic liver disease (MASLD) is hepatic lipid accumulation. A recent search for genes impacting MASLD in mice uncovered the transcriptional repressor T-box 3 (Tbx3) as a top hit. In this issue of the JCI, Mannino et al. investigated the mechanism of action of TBX3 in murine MASLD. Tbx3 deletion protected against MASLD by inducing high density lipoprotein binding protein and stimulating hepatic VLDL secretion. Loss-of-function mutations in human TBX3 identified in MASLD patients displayed a similar protective effect. Collectively, these findings highlight the importance of lipid export in the prevention of MASLD and identify a transcriptional pathway controlling hepatic lipid secretion that is poised for further investigation.
Authors
Jacquelyn J. Maher
Abstract
Accumulation of the light-reactive heme precursor protoporphyrin IX (PPIX) in blood causes protoporphyria, a disease characterized by severe pain resulting from sunlight exposure, as well as by the occurrence of liver failure in some patients. Thus, decreasing PPIX biosynthesis is a promising strategy to treat protoporphyria. In this issue of the JCI, Ducamp et al. report that inhibition of the glycine plasma membrane transporter GLYT1 using bitopertin decreased PPIX accumulation and ameliorated liver disease using human in vitro and mouse in vivo models. Their findings support the ongoing development of bitopertin to treat protoporphyria, while concurrently pointing to underexplored roles of glycine in erythroid cells.
Authors
Marc Liesa
Abstract
Cutaneous melanoma (CM) is known for its aggressive behavior, high metastatic potential, and poor prognosis. Mutations in the BRAF gene are common in CM, and patients with BRAF-mutant melanoma often respond well to combined inhibition of BRAF and MEK (BRAFi + MEKi). Although BRAFi + MEKi therapy provides clinical efficacy, the response durability is limited by persistent drug-tolerant residual cells, culminating in relapse. In this issue of the JCI, Tiago et al. confirmed that NR2F1, a dormancy-associated transcription factor, is a key determinant of therapeutic resistance in melanoma. NR2F1 expression was elevated in transcriptomic datasets from patients with minimal residual disease, and in murine and human melanoma models, NR2F1 overexpression reduced therapeutic efficacy and suppressed tumor proliferation and invasion while sustaining mechanistic target of rapamycin complex 1 (mTORC1) transcriptional regulation of relevant genes. Combining BRAFi + MEKi with the mTORC1 inhibitor rapamycin effectively targeted these resistant melanoma cells, suggesting a potential path forward for targeting NR2F1 and mTORC1 signaling in patients with CM.
Authors
Narsimha Mamidi, Swadesh K. Das, Paul B. Fisher
Abstract
The search for transformative medicines has continuously uncovered select diseases associated with the disruption of the endocannabinoid (eCB) signaling system in the brain and emphasized the therapeutic value of small molecules that rescue this signaling system. In this issue of JCI, Wang et al. report that genetic disruption of PPP2R1A function in mouse forebrain, a preclinical mouse model of neurodevelopmental disorders, resulted in pronounced impairment of eCB signaling. Notably, small-molecule inhibitors of eCB inactivation rescued both eCB signaling and cognitive dysfunction in this model, providing a solid foundation to move such transformative therapeutic approaches based on targeting eCB signaling toward human clinical trial testing.
Authors
Nephi Stella
Abstract
Cerebrospinal fluid dynamics play an important role in maintaining brain health and clearing metabolic waste from the brain. In this issue of the JCI, Gursky et al. investigate how CSF distribution is affected when its primary efflux pathway — the deep cervical lymph nodes — is disrupted by cauterization. This timely study reveals compensatory fluid drainage routes from the skull, age-dependent adaptations in CSF homeostasis, and the emergence of neuroinflammation when an efflux pathway is occluded. The findings underscore the need to better understand the physiological mechanisms governing CSF clearance, how these pathways evolve with aging, and whether CSF influx and efflux exhibit region-specific dynamics shaped by neuroanatomy. Additionally, the study raises important questions about whether peripheral injury can influence central nervous system states. A more complete understanding of CSF flow regulation may offer new perspectives on the origins of neuropathology.
Authors
Lauren M. Hablitz, Maiken Nedergaard
Abstract
Leukocyte-associated Ig-like receptor 1 (LAIR1) is a collagen-binding inhibitory immune receptor that negatively regulates cellular activation. In this issue of the JCI, Tao et al. show that LAIR1-inhibitory signaling plays an important role in immunosuppressive M2-like tumor-associated macrophages (TAMs) in aggressive brain tumors. LAIR1 KO, antibody blockade, and an immunotherapy that incorporates a LAIR1-inhibitory module into a chimeric antigen receptor (CAR) all led to increased antitumor activity by CAR T cells, reduced M2-like TAMs, altered collagen networks, and increased survival rates in mouse tumor models. These findings demonstrate an innovative immunotherapeutic approach for cancer that leverages LAIR1 inhibition to combat multiple tumor immune evasion strategies.
Authors
Ezri P. Perrin, Hannah K. Dorando, Jacqueline E. Payton
Abstract
Platelet hyperreactivity, defined as enhanced sensitivity to activation in response to classical agonists, contributes to the increased risk of arterial thrombosis associated with chronic inflammatory diseases. In this issue of the JCI, Kong and colleagues used an unbiased proteomic approach to identify elevated SEC61B in platelets from patients with diabetes and from hyperglycemic mice. Typically, SEC61B participates in protein transport within the endoplasmic reticulum (ER), but it can also act as an ion channel that allows calcium to leak from ER to cytoplasm. The authors showed that elevated SEC61B expression caused increased calcium leak, elevated basal cytoplasmic calcium concentrations, and platelet hyperreactivity. In vitro and in vivo pharmacological interventions to alter calcium homeostasis through this pathway affected platelet reactivity. The results of this work are consistent with those of previous studies showing that platelets from patients with chronic diseases behaved differently than those from healthy participants. These findings identify potential disease-specific targets to prevent and treat arterial thrombosis.
Authors
Roy L. Silverstein
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