Therapeutic B cell depletion identifies immunoregulatory networks

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Abstract

B cell depletion is a highly effective therapy in multiple sclerosis (MS), reducing inflammation and restoring immune balance. In this issue of the JCI, Wei et al. used single-cell RNA-Seq and flow cytometry, identifying the comprehensive effects of B cell depletion on the immune response, including an increase in antiinflammatory cerebrospinal fluid macrophages and elevated TNF-α expression by peripheral CD16+ monocytes. The authors also detected shifts in T cell populations that resulted in reduced myelin-reactive CD4+ T cells and the expansion of TIGIT+ Tregs. The findings uncover immunoregulatory mechanisms and suggest therapeutic strategies for MS and other autoimmune disorders.

Authors

Carolina M. Polonio, Francisco J. Quintana

The writing on the arterial wall: epigenetic control of blood pressure and vascular remodeling

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Abstract

Hypertension is a leading cause of morbidity and mortality, with pathologic consequences on multiple end-organ systems. Smooth muscle plasticity and its epigenetic regulation promote disease pathogenesis, but the genetic levers that control such activity are incompletely defined. In this issue of the JCI, Mangum et al. utilized high-density genomic data to define the causal and pathogenic role of a variant at the JMJD3 locus — one that is associated with systolic blood pressure and governs an allele-specific molecular mechanism controlling smooth muscle behavior in hypertension. These findings have clinical implications relevant to patient risk stratification and personalized therapeutics.

Authors

Lloyd D. Harvey, Stephen Y. Chan

Another Fanconi anemia gene joins the club

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Abstract

Fanconi anemia (FA) is the most common inherited bone marrow failure disorder, caused by pathogenic variants in genes involved in the FA DNA repair pathway. In this issue of the JCI, two studies report three germline homozygous loss-of-function variants in FAAP100, a key component of the FA core complex, identified in three unrelated families. These variants result in severe developmental phenotypes that are among the most extreme reported in FA to date. Harrison et al. described individuals from two families with recurrent pregnancy loss and neonatal death due to homozygous FAAP100 frameshift and truncating variants, respectively. Kuehl et al. identified a homozygous missense variant in a fetus with congenital malformations consistent with FA. Collectively, both studies provide robust functional evidence from ex vivo and in vitro assays with animal models supporting the pathogenicity of these variants and establish FAAP100 as a causative FA gene.

Authors

Claire C. Homan, Hamish S. Scott, Parvathy Venugopal

Switching on the evolutionary potential of pancreatic cancer: the tumor suppressor functions of PBRM1

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Abstract

Cell plasticity is a hallmark of cancer, enabling tumor cells to acquire multiple phenotypes responsible for tumor progression, metastasis, and therapy resistance. In this issue of the JCI, Kawai and colleagues leveraged genetically engineered mouse models (GEMM) of pancreatic ductal adenocarcinoma (PDAC) to demonstrate that loss of Pbrm1, a member of the SWI/SNF complex, drives dedifferentiation and aggressive tumor features. Pbrm1 loss activated a program of epithelial-to-mesenchymal transition (EMT) and allowed the emergence of poorly differentiated histologies that are commonly associated with high recurrence rate and dismal prognosis. These findings reveal the role of the SWI/SNF complex during PDAC evolution in maintaining cell identity and restraining the progression of this lethal disease.

Authors

Luigi Perelli, Giannicola Genovese

IL-13 priming in precursors drives beige adipogenesis and enhances metabolic homeostasis

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Abstract

Accumulating evidence from rodent and human studies indicates that the activity of thermogenic adipocytes positively correlates with optimal metabolic function. In this issue of the JCI, Yesian et al. uncover a paracrine signaling pathway from type 2 innate lymphoid cells to preadipocytes via IL-13 that increases beige adipogenesis through a PPARγ-dependent pathway. Mice with deletion of Il13ra1 demonstrated glucose dysregulation, and variants near the human IL13RA1 locus were associated with body weight and diabetic status. It is tempting to speculate that targeting IL-13 holds therapeutic potential for improving metabolic fitness in humans.

Authors

Margo P. Emont, Jun Wu

Promoting mucosal healing by targeting TMEM219-dependent intestinal epithelial stem cell defects in inflammatory bowel disease

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Abstract

Inflammatory Bowel Diseases (IBD), including Crohn’s disease and ulcerative colitis, pose challenges due to their complex pathophysiology and high prevalence. Despite advances in immune-targeted therapies, a substantial number of patients fail to achieve mucosal healing, highlighting the need for alternative therapeutic strategies. In this issue of the JCI, D’Addio et al. identified another mechanism underlying impaired epithelial regeneration in Crohn’s disease. They found that abnormal cell death in intestinal epithelial stem cells, mediated by altered TMEM219 signaling, led to impaired mucosal healing. Targeting TMEM219 with ecto-TMEM219, which blocks its activation, restored stem cell function and promoted mucosal healing in vitro and in vivo. These findings suggest a promising therapeutic avenue focusing on epithelial repair. Additionally, patient-derived organoids (PDOs) emerge as a valuable tool for personalized treatment strategies and for advancing the field of IBD research. This study underscores the importance of epithelial cell biology in developing innovative IBD therapies.

Authors

Nicolas Schlegel

Traffic jam in lung capillaries: inter-organ communication impedes gas exchange after acute kidney injury

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Abstract

Acute kidney injury (AKI) is a frequent complication in critically ill patients and triggers a systemic inflammatory response that can contribute to lung injury, ultimately worsening clinical outcomes. However, diagnostic and therapeutic strategies remain unavailable. In this issue of the JCI, Komaru et al. explored leukocyte trafficking and vascular pooling following AKI in mice as an underlying mechanism of acute lung injury. Using intravital microscopy, the authors observed rapid accumulation of neutrophils in pulmonary capillaries within minutes of AKI onset. These neutrophils followed monocytes and slowed blood flow. Notably, disruption of this process improved oxygenation. The findings provide insights into this complex inter-organ crosstalk and open avenues for future research.

Authors

Ulrich Matt, Susanne Herold

GALNT14 deficiency: connecting multiple links in the IgA nephropathy pathogenetic chain

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Abstract

IgA nephropathy (IgAN) is a highly prevalent type of primary glomerulonephritis. IgAN involves mesangial deposition of immune complexes leading to complement activation, inflammation, and glomerular injury. A key hit for pathogenesis involves aberrant O-glycosylation in the hinge region of IgA. Despite its prevalence, however, the mechanisms underlying IgAN remain incompletely understood. In this issue of the JCI, Prakash and colleagues used whole-exome sequencing of two IgAN probands to identify loss-of-function variants in GALNT14 leading to loss of the enzyme GalNAc-T14, which is involved in O-glycosylation. The authors then performed a classical bedside-to-bench investigation using a Galnt14–/– mouse model and connected loss of GalNAc-T14 to excess IgA production, impaired B lymphocyte homing, and defective intestinal mucus production. These findings build a more unified understanding of IgAN pathogenesis from defective O-glycosylation with loss-of-function variants in GALNT14.

Authors

John Pell, Madhav C. Menon

Endothelial dysfunction in patients with type 2 diabetes: the truth is in the blood

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Abstract

Endothelial dysfunction remains a cornerstone of diabetic vascular complications. RBCs emerge as pivotal players in endothelial dysfunction, yet the underlying mechanisms remain elusive. In this issue of the JCI, Collado et al. show that the detrimental action of RBCs on the endothelium is mediated by extracellular vesicles (EVs). EVs derived from RBCs (RBC-EVs) of patients with diabetes were taken up by the endothelium and were able to impair endothelium-dependent relaxation via an EV-mediated transfer of the prooxidant enzyme arginase-1 (Arg1) from RBCs to endothelial cells. These findings reveal events implicated in vascular oxidative stress and set the stage for personalized approaches preventing RBC-EVs’ uptake by the endothelium.

Authors

Sarah Costantino, Shafeeq A. Mohammed, Francesco Paneni

GLP-1 receptor agonists for the treatment of alcohol use disorder

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Abstract

Glucagon-like peptide-1 receptor agonists (GLP-1RAs), such as semaglutide, are widely used in the treatment of metabolic disorders, including type 2 diabetes (T2D) and obesity. These medications primarily function by enhancing insulin secretion; however, emerging evidence suggests that the effects extend beyond metabolic regulation. In this issue of the JCI, Farokhnia et al. evaluated the effects of GLP-1RAs alongside another T2D treatment, dipeptidyl peptidase-4 inhibitors (DPP-4Is), on alcohol consumption in humans and preclinical models. In humans, GLP1-RAs, but not DPP-4Is, were associated with reductions in alcohol consumption. Similarly, DPP-4 inhibition had no effect on alcohol intake in rodents. These findings invite further exploration of the mechanisms by which GLP-1RAs reduce alcohol consumption and redefine our pharmacotherapy approach to alcohol use disorder (AUD) by opening the possibility for application as an early harm-reduction tool.

Authors

Gavin N. Petrie, Leah M. Mayo