Journal of Clinical Investigation最新文献

Aging commonly causes decline of testosterone or estrogen, leading to overaccumulation of fatness in men and women, respectively. Although such a phenomenon can be readily explained by estrogen's direct action on adipocytes in women, accumulative evidence does not support the direct action of testosterone in adipocyte lipid metabolism, suggesting there is a missing intermediary link. Herein, we propose that glycoprotein hormone β5 (GPHB5) is the intermediary linkage between testosterone and the regulation of adiposity. In clinical samples, blood levels of GPHB5 were correlated negatively with men's ages and positively with circulating testosterone. Testosterone directly stimulated the expression of GPHB5 in cultured cells; pharmacological blockade of androgen receptor (AR) functions abrogated this effect. Knockout of AR led not only to development of obesity but also reduction of GPHB5 expression. Genetic ablation of GPHB5 in men, but not women, reduced the browning of white adipose tissue, diminished energy expenditure, and caused severe obesity. Importantly, elevated blood testosterone levels did not exert catabolic actions in GPHB5-/- mice; yet, recombinant GPHB5 protein could stimulate energy expenditure and reduce adiposity. These results provide strong proof that GPHB5 is the "missing" intermediary hormone linking testosterone (and aging) and its well-known catabolic effect on adipose tissue.

Background: Plasma heparan sulfate, a glycosaminoglycan released during endothelial glycocalyx degradation, predicts sepsis mortality. Chondroitin sulfate is a circulating glycosaminoglycan not specific to glycocalyx degradation; its relevance to sepsis is unknown.

Methods: We studied the associations of plasma chondroitin sulfate with (a) mortality in patients with sepsis-associated hypotension and (b) the relative effectiveness of a randomly-assigned liberal versus restrictive intravenous fluid resuscitation strategy. We selected 574 patients enrolled in the Crystalloid Liberal or Vasopressors Early Resuscitation in Sepsis trial using an outcome-enriched sampling strategy. We used liquid chromatography-mass spectrometry to quantify plasma chondroitin sulfate. In comparison, we measured hyaluronic acid as a glycocalyx degradation marker and IL-6 as an inflammatory biomarker. We conducted Cox proportional hazards regression analyses to examine associations of baseline biomarker concentrations with mortality and resuscitation strategy effectiveness. We used inverse probability of selection weights and generalized raking to account for the non-representative sampling design.

Results: Plasma chondroitin sulfate, hyaluronic acid, and IL-6 were associated with mortality within 90 days. As baseline chondroitin sulfate increased, subsequent randomization to a restrictive strategy was increasingly beneficial (p = 0.022): treatment effect hazard ratio (restrictive versus liberal) for mortality was estimated as 1.49 (95% CI 0.98-2.27), 1.30 (1.00-1.69), 1.09 (0.82-1.44), 0.88 (0.66-1.16), and 0.71 (0.52-0.97) for 10th, 25th, 50th, 75th and 90th percentiles of baseline chondroitin sulfate.

Conclusions: Plasma chondroitin sulfate predicts sepsis mortality and may modify the response to a subsequent liberal vs. restrictive intravenous fluid resuscitation strategy.

Trial:

Clinicaltrials: gov NCT03434028.

Chordomas are rare malignant osseous neoplasms with a striking rate of recurrence. Primary chordomas typically originate from embryonic notochord remnants, whereas recurrent chordomas usually stem from tumor cells infiltrating bone or cartilage after surgery. Clinically, the recurrent chordomas exhibit a stiffer extracellular microenvironment (ECM) than primary tumors. Intriguingly, this study identified cytoskeleton rearrangement, stress fiber reorganization, enhanced stemness, and Notch signaling activation in recurrent chordoma tissues or cell lines surviving stiff substrates, indicating the critical roles of mechanical remodeling and tumor stemness in stiffness resistance. We propose a potentially novel recurrence model where tumor cells experience mechanoadaptive organization, which enables them to resist stiff microenvironment-induced cell death. O-GlcNAcylation of Notch1 intracellular domain (NICD1) is central to this process. Mechanistically, the stiff ECM-driven ligand-independent phosphorylation of EPHA2 sequentially activated LYN kinase and subsequently triggered O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) activity by phosphorylating Y989 and Y418, critical residues for OGT glycosyltransferase activity; this induced NICD1 O-GlcNAcylation at T2063, T2090, and S2162, specifically promoting transcription of mechanical and stemness-related genes. MIR31 deletion upregulated LYN, enhancing stiffness perception and promoting O-GlcNAc addition to NICD1, finally resulting in mechanoadaptation- and tumor stemness-driven recurrence. Consequently, MIR31 deletion is a potential biomarker for recurrence and patient stratification in Notch- or OGT-targeted therapies.

The fingertip is one of the only known complex structures in mammals that can fully regenerate following amputation. This phenomenon can be studied in mice using the amputation of the digit tip, the regenerative success of which has been shown to be reliant on effective bone clearance prior to new bone formation. In this issue of the JCI, Vishlaghi et al. investigated whether local lymphatic vessels are involved in this process. Interestingly, they found that inhibiting lymphangiogenesis resulted in accelerated clearance of damaged tissue and bone, thereby improving subsequent digit regeneration. This study is the first to our knowledge to report lymphatic involvement in digit regeneration and raises questions regarding the underlying mechanisms at play.

TFE3 translocation renal cell carcinoma (tRCC), an aggressive kidney cancer driven by TFE3 gene fusions, is frequently misdiagnosed owing to morphologic overlap with other kidney cancer subtypes. Conventional liquid biopsy assays that detect tumor DNA via somatic mutations or copy number alterations are unsuitable for tRCC since it often lacks recurrent genetic alterations and because fusion breakpoints are highly variable between patients. We reasoned that epigenomic profiling could more effectively detect tRCC because the driver fusion constitutes an oncogenic transcription factor that alters gene regulation. By defining a TFE3-driven epigenomic signature in tRCC cell lines and detecting it in patient plasma using ChIP-seq, we distinguished tRCC from clear-cell RCC (AUC = 0.86) and samples of individuals without evidence of cancer (AUC = 0.92) at low tumor fractions (<1%). This work establishes a framework for noninvasive epigenomic detection, diagnosis, and monitoring of tRCC, with implications for other mutationally quiet, fusion-driven cancers.

Cardiac allograft vasculopathy (CAV) is a fibroproliferative form of transplant rejection with limited treatment options other than retransplantation. In this issue, See and colleagues examined human explanted allografts with CAV. They found that a high proportion of intragraft plasma cells produce antibodies that recognize the heme catabolic end product, bilirubin. Clonotypic profiling revealed that bilirubin-reactive antibody-producing plasma cells develop from graft-infiltrating innate-like B cells, a subset often characterized by their rapid production of polyreactive natural antibodies as an early defense against infection. CAV but not nonrejecting graft tissue contained bilirubin deposits along with macrophages that expressed genes involved in heme catabolism. These findings raise the intriguing possibility that graft-derived bilirubin-specific antibodies target local heme catabolism to promote CAV.

Programmed cell death 1 ligand 1-targeted (PD-L1-targeted) immune checkpoint inhibitors are revolutionizing cancer therapy. However, strategies to induce endogenous PD-L1 degradation represent an emerging therapeutic paradigm. Here, we identified proanthocyanidins (PC) as a potent inducer of PD-L1 degradation through an endoplasmic reticulum-associated degradation (ERAD) mechanism. Mechanistically, PC exerted dual effects: First, it targeted and stabilized LKB1 to activate AMPK in tumor cells, subsequently inducing the phosphorylation of PD-L1 at Ser195 - a disruption that in turn impaired glycosylation of PD-L1 and promoted its retention in the ER. Second, PC directly bound to the E3 ubiquitin ligase SYVN1 to increase its protein stability, which strengthened PD-L1-SYVN1 binding, thereby accelerating K48-linked ubiquitination and proteasomal degradation of ER-retained PD-L1. This cascade culminated in the activation of CD8+ T cell-dominated antitumor immune responses, accompanied by suppression of myeloid-derived suppressor cells and regulatory T cells. In preclinical models of lung and colorectal cancer, PC exhibited synergistic antitumor efficacy when combined with anti-cytotoxic T lymphocyte antigen 4 (anti-CTLA-4) antibodies. Notably, PC also potently inhibited the progression of azoxymethane/dextran sodium sulfate-induced orthotopic colorectal cancer in mice. Collectively, our findings unveil an antitumor mechanism of PC, establishing this small-molecule compound as an ERAD pathway-exploiting immune checkpoint modulator with promising translational potential for cancer therapy.

Circadian clocks govern daily rhythms in cellular and physiological processes, including cell cycle, DNA repair, metabolism, and immune function, that influence cancer development and treatment response. Disruption of circadian regulators either promotes or suppresses malignancy depending on tumor type and biological context. This duality likely reflects systemic rewiring of circadian physiology and direct interactions between clock components and oncogenic pathways. These insights hold clinical relevance for the field of chronotherapy, which seeks to enhance therapeutic efficacy and minimize toxicity by aligning drug administration with circadian rhythms or by targeting elements of the molecular clock. In this Review, we highlight the promise of integrating circadian biology into precision oncology and underscore the importance of cancer type-specific investigations to harness the full therapeutic potential of chronotherapy in cancer.

A major unmet need in estrogen receptor-positive (ER+) breast cancer is understanding the mechanisms that underlie resistance to endocrine therapy. Although accumulating evidence suggests an association between the tumor immune microenvironment (TIME) and endocrine response, the specific role of the TIME in mediating endocrine resistance remains unclear. In this issue of the JCI, Napolitano et al. analyzed tumor biopsies from patients with ER+ breast cancer and reported that endocrine-resistant tumors exhibited heightened CD8+ T cell infiltration and activation of the CXCL11 - CXCR3/-7 axis. Spatial and coculture analyses of these tumors demonstrated that the CD8+ T cell-associated chemokine CXCL11 drove estrogen-independent tumor growth. These findings identify an immune-mediated mechanism of endocrine resistance in breast cancer and identify CXCL11 as a potential biomarker and therapeutic vulnerability.

SCN8A encodes the voltage-gated sodium channel Nav1.6, which plays a key role in facilitating neuronal excitability. Mutations in SCN8A, particularly gain-of-function variants, cause SCN8A developmental and epileptic encephalopathy (DEE), a severe epilepsy syndrome characterized by seizures, cognitive dysfunction, movement disorders, and sudden unexpected death in epilepsy (SUDEP). The recurrent SCN8A variant R1872W impairs channel inactivation, causing neuronal hyperexcitability and seizures. Current treatments, including antiseizure medications, are often ineffective for patients with SCN8A DEE, highlighting the need for targeted therapies. We employed base editing to correct the R1872W SCN8A variant. An adenine base editor and guide RNA (SCN8A-ABE) were packaged within dual PhP.eB-adeno-associated viruses (AAVs) and administered to R1872W mice at P2. SCN8A-ABE significantly increased survival of mice expressing R1872W and either reduced seizure incidence and severity or eliminated seizure occurrence. Electrophysiological recordings revealed a rescue of seizure-associated neuronal hyperexcitability and suppression of the pathogenic persistent sodium current (INaP) in treated mice. Comorbidities, including diminished mobility and anxiety-like behaviors, were improved by SCN8A-ABE. These effects were achieved by a 32% absolute reduction in mutant transcripts, accompanied by conversion to SCN8A WT transcripts. Our findings demonstrate base editing as an effective targeted therapeutic approach for SCN8A DEEs by addressing the underlying genetic cause.