Research
Abstract
Iron regulatory protein 1 (IRP1) is a post-transcriptional regulator of cellular iron metabolism. In mice, loss of IRP1 causes polycythemia through translational de-repression of hypoxia-inducible factor 2α (HIF2α) mRNA, which increases renal erythropoietin production. Here we show that Irp1-/- mice develop fasting hypoglycemia and are protected against high-fat diet–induced hyperglycemia and hepatic steatosis. Discovery-based proteomics of Irp1-/- livers revealed a mitochondrial dysfunction signature. Seahorse flux analysis in primary hepatocytes and differentiated skeletal muscle myotubes confirmed impaired respiratory capacity, with a shift from oxidative phosphorylation to glycolytic ATP production. This metabolic rewiring was associated with enhanced insulin sensitivity and increased glucose uptake in skeletal muscle. Under metabolic stress, IRP1 deficiency altered the redox balance of mitochondrial iron, resulting in inefficient energy production and accumulation of amino acids and metabolites in skeletal muscle, rendering them unavailable for hepatic gluconeogenesis. These findings identify IRP1 as a critical regulator of systemic energy homeostasis.
Authors
Wen Gu, Nicole Wilkinson, Carine Fillebeen, Darren Blackburn, Korin Sahinyan, Eric Bonneil, Tao Zhao, Zhi Luo, Vahab Soleimani, Vincent Richard, Christoph H. Borchers, Albert Koulman, Benjamin Jenkins, Bernhard Michalke, Hans Zischka, Judith Sailer, Vivek Venkataramani, Othon Iliopoulos, Gary Sweeney, Kostas Pantopoulos
Abstract
Multisystemic Smooth Muscle Dysfunction Syndrome (MSMDS) is a rare disorder caused by ACTA2 mutations, including the R179H variant, which alters actin filament stability and dynamics and smooth muscle contractility. While cardiovascular complications dominate its clinical presentation, gastrointestinal (GI) dysfunction significantly impacts quality of life. To investigate the structural, functional, and cellular basis of gut dysmotility in MSMDS, we reviewed clinical data from 24 MSMDS patients and studied the ACTA2 R179H mouse model Patients exhibited severe gut dysmotility, with 75% requiring medication for chronic constipation. ACTA2 mutant mice displayed cecal and colonic dilatation, reduced intestinal length, and disrupted colonic migrating motor complexes (CMMCs). Delayed whole-gut transit and impaired contractile responses to electrical and pharmacological stimulation were observed. Transcriptomic analysis revealed significant actin cytoskeleton-related gene changes in smooth muscle cells, and immune profiling identified increased lymphocytic infiltration. Despite functional abnormalities, there were no obvious changes in the enteric nervous system. These findings establish ACTA2 mice as a robust model for studying GI pathology in MSMDS, elucidating the role of smooth muscle dysfunction in gut dysmotility. This model provides a foundation for developing targeted therapies aimed at restoring intestinal motility by directly addressing actin cytoskeletal disruptions in smooth muscle cells.
Authors
Ahmed A. Rahman, Rhian Stavely, Leah C. Ott, Christopher Y. Han, Kensuke Ohishi, Ryo Hotta, Alan J. Burns, Sabyasachi Das, Emily Da Cruz, Diana Tambala, Mark E. Lindsay, Patricia L. Musolino, Allan M. Goldstein
Abstract
Functional antibody responses to malaria transmission-blocking vaccines (TBVs) are assessed using the Standard Membrane Feeding Assay (SMFA). This assay quantifies percentage reduction of oocyst levels in mosquitoes fed gametocytes mixed with antisera/antibodies, referred to as transmission-reducing activity (TRA). As TBVs advance to large clinical trials, new scalable assays are needed to characterize vaccine responses. Here, we developed an epitope-specific competitive ELISA platform (P230Compete) for TBV candidate Pfs230D1, based on single-chain variable fragments (scFv) against epitopes recognized by human monoclonal antibodies with high TRA. We quantified functional epitope-specific antibody responses (F) in Phase 1 Pfs230D1-EPA/AS01 vaccine trial participants, using 171 serum samples collected at two post-vaccination timepoints. Five antibody features were examined by P230Compete including total IgG (reported as ELISA units, EUF), IgG subclasses (IgG1F, IgG3F, IgG4F), and bound complement factor C1q (C1qF). EUF and IgG1F demonstrated strong correlation and excellent prediction of TRA≥80% in logistic regression analysis (AUC of 0.81 for both assays post-dose 3, and 0.80 and 0.76 post-dose 4). Furthermore, combining EUF and IgG1F showed even better predictive performance at each timepoint. P230Compete offers a promising proxy assay to replace SMFA in late-stage Pfs230D1 trials.
Authors
Cristina A. Meehan, Matthew V. Cowles, Robert D. Morrison, Yuyan Yi, Jingwen Gu, Jen C.C. Hume, Mina P. Peyton, Issaka Sagara, Sara A. Healy, Jonathan P. Renn, Patrick E. Duffy
Abstract
This investigation leverages single-cell RNA sequencing (scRNA-Seq) to delineate the contributions of muscle-resident Schwann cells to neuromuscular junction (NMJ) remodeling by comparing a model of stable innervation with models of reinnervation following partial or complete denervation. The study discovered multiple distinct Schwann cell subtypes, including a novel terminal Schwann cell (tSC) subtype integral to the denervation-reinnervation cycle, identified by a transcriptomic signature indicative of cell migration and polarization. The data also characterizes three myelin Schwann cell subtypes, which are distinguished based on enrichment of genes associated with myelin production, mesenchymal differentiation or collagen synthesis. Importantly, SPP1 signaling emerges as a pivotal regulator of NMJ dynamics, promoting Schwann cell proliferation and muscle reinnervation across nerve injury models. These findings advance our understanding of NMJ maintenance and regeneration and underscore the therapeutic potential of targeting specific molecular pathways to treat neuromuscular and neurodegenerative disorders.
Authors
Steve D. Guzman, Ahmad Abu-Mahfouz, Carol S. Davis, Lloyd P. Ruiz, Peter C.D. Macpherson, Susan V. Brooks
Abstract
C-type natriuretic peptide (CNP) is known to promote chondrocyte proliferation and bone formation; however, CNP’s extremely short half-life necessitates continuous intravascular administration to achieve bone-lengthening effects. Vosoritide, a CNP analog designed for resistance to neutral endopeptidase, allows for once daily administration. Nonetheless, it distributes systemically rather than localizing to target tissues, which may result in adverse effects such as hypotension. To enhance local drug delivery and therapeutic efficacy, we developed a novel synthetic protein by fusing a collagen-binding domain (CBD) to CNP, termed CBD-CNP. This fusion protein exhibited stability under heat conditions and retained the collagen-binding ability and bioactivity as CNP. CBD-CNP localized to articular cartilage in fetal murine tibiae and promoted bone elongation. Spatial transcriptomic analysis revealed that the upregulation of chondromodulin expression may contribute to its therapeutic effects. Treatment of CBD-CNP mixed with collagen powder to a fracture site of a mouse model increased bone mineral content and bone volume rather than CNP-22. Intra-articular injection of CBD-CNP to a mouse model of knee osteoarthritis suppressed subchondral bone thickening. By addressing the limitations of CNP’s rapid degeneration, CBD-CNP leverages its collagen-binding capacity to achieve targeted, sustained delivery in collagen-rich tissues, offering a promising strategy for enhancing chondrogenesis and osteogenesis.
Authors
Kenta Hirai, Kenta Sawamura, Ryusaku Esaki, Ryusuke Sawada, Yuka Okusha, Eriko Aoyama, Hiroki Saito, Kentaro Uchida, Takehiko Mima, Satoshi Kubota, Hirokazu Tsukahara, Shiro Imagama, Masaki Matsushita, Osamu Matsushita, Yasuyuki Hosono
Abstract
Clonal haematopoiesis of indeterminate potential (CHIP) is the expansion of blood stem cells and progeny after somatic mutation. CHIP associates with increased cardiovascular disease (CVD) with inflammation from macrophages a proposed common effector. However, mouse CHIP studies are discordant for clonal expansion and inflammation. Similarly, directionality of association between CHIP and CVD remains debated. We investigated effects of three CHIP mutations on macrophage cytokines, clonal expansion and atherosclerosis in parallel. We find that Tet2 and Dnmt3a mutations increase cytokines and inflammasome activation in Tet2 but decrease in Dnmt3a. However, Jak2 mutant macrophages produced equivalent cytokine as wild-type. In mice, Tet2 mutants clonally expanded, but Dnmt3a and Jak2 mutants didn’t. Expansion was unaffected by systemic inflammation, while hyperlipidemia expanded Tet2-/- cells, but not mono-allelic mutants. Similarly, human Mendelian randomisation showed no effect of serum cytokines or CVD on CHIP risk. Experimental atherosclerosis was increased in females with Tet2 and males with Jak2, but unchanged with Dnmt3a mutations. Together, common CHIP mutations have disparate effects on macrophage cytokines and clonal expansion, and sex-dependent effects on atherogenesis, suggesting a common mechanism across CHIP is unlikely. Thus, CHIP mutations differ in pathophysiology and clinical sequalae across sexes and should be treated as different entities.
Authors
Paul R. Carter, Lauren Kitt, Amanda Rodgers, Nichola Figg, Ang Zhou, Chengrui Zhu, Ziyang Wang, Peter Libby, Stephen Burgess, George S. Vassiliou, Murray CH. Clarke
Abstract
Mucosal secretory IgA (sIgA) plays a central role in protecting against the invasion of respiratory pathogen via the upper respiratory tract. To understand how intranasal booster induces mucosal sIgA response in humans, we first used liquid chromatography-tandem mass spectrometry for peptide identification of immunoglobulin (MS Ig-Seq) and single-cell B-cell receptor sequencing (scBCR-seq) to identify mucosal spike-specific sIgA monoclonal antibodies (mAbs) after intranasal booster. These mucosal sIgA mAbs exhibited enhanced neutralization up to 100-fold against SARS-CoV-2 variants compared to their monomeric IgG and IgA isotypes. Deep sequencing and longitudinal analysis of B-cell receptor repertoires revealed that nasal booster re-stimulates memory B cells primed by intramuscularly vaccination to undergo IgA class switching, somatic hypermutation, and clonal expansion. Single-cell sequencing revealed that intranasal booster upregulated the expression of mucosal homing receptors in spike-specific IgA-expressing B cells. This increase coincided with a transient increase of cytokines and chemokines that facilitate B cell recruitment in the nasal mucosa. Our findings demonstrate that intranasal booster can be an effective strategy for inducing upper respiratory mucosal sIgA and establishing mucosal immune protection.
Authors
Si Chen, Zhengyuan Zhang, Zihan Lin, Li Yin, Lishan Ning, Wenming Liu, Qian Wang, Chenchen Yang, Bo Feng, Ying Feng, Yongping Wang, Hengchun Li, Ping He, Huan Liang, Yichu Liu, Zhixia Li, Bo Liu, Yang Li, Diana Boraschi, Linbing Qu, Xuefeng Niu, Nanshan Zhong, Pingchao Li, Ling Chen
Abstract
Pathogenic variants in kinesin KIF11 underlie microcephaly-lymphedema-chorioretinopathy (MLC) syndrome. Although well known for regulating spindle dynamics ensuring successful cell division, the association of KIF11 (encoding EG5) with development of the lymphatic system, and how KIF11 pathogenic variants lead to lymphatic dysfunction and lymphedema remain unknown. Using patient-derived lymphoblastoid cells, we demonstrated that MLC patients carrying pathogenic stop-gain variants in KIF11 have reduced mRNA and protein levels. Lymphoscintigraphy showed reduced tracer absorption, and intestinal lymphangiectasia was detected in one patient, pointing to impairment of lymphatic function caused by KIF11 haploinsufficiency. We revealed that KIF11 is expressed in early human and mouse development with the lymphatic markers VEGFR3, Podoplanin and PROX1. In zebrafish, scRNA-seq identified kif11 specifically expressed in endothelial precursors. In human lymphatic endothelial cells (LECs), EG5 inhibition with Ispinesib, reduced VEGFC-driven AKT phosphorylation, migration and spheroid sprouting. KIF11 knockdown reduced PROX1 and VEGFR3 expression, providing for the first time a link between KIF11 and drivers of lymphangiogenesis and lymphatic identity.
Authors
Kazim Ogmen, Sara E. Dobbins, Rose Yinghan Behncke, Ines Martinez-Corral, Ryan C.S. Brown, Michelle Meier, Sascha Ulferts, Nils Rouven Hansmeier, Ege Sackey, Ahlam Alqahtani, Christina Karapouliou, Dionysios Grigoriadis, Juan C. Del Rey Jimenez, Michael Oberlin, Denise Williams, Arzu Ekici, Kadri Karaer, Steve Jeffery, Peter Mortimer, Kristiana Gordon, Kazuhide S. Okuda, Benjamin M. Hogan, Taija Mäkinen, René Hägerling, Sahar Mansour, Silvia Martin-Almedina, Pia Ostergaard
Abstract
Developing biomarkers to quantitatively monitor disease-specific T cell activity is crucial for assessing type 1 diabetes (T1D) progression and evaluating immunotherapies. This study presents an approach using V-gene targeted sequencing to quantify T cell receptor (TCR) clonotypes as biomarkers for pathogenic T cells in T1D. We identified "public" TCR clonotypes shared among multiple non-obese diabetic (NOD) mice and human organ donors, with a subset expressed exclusively by islet antigen-reactive T cells in those with T1D. Employing V-gene targeted sequencing of only TCRs containing TRAV16/16D allowed quantitative detection of the public islet antigen-reactive TCR clonotypes in peripheral blood of NOD mice. Frequencies of these public TCR clonotypes distinguished prediabetic NOD mice from those protected from diabetes. In human islets, public TCR clonotypes identical to preproinsulin-specific clones were exclusively found in T1D donors. This quantifiable TCR sequencing approach uncovered public, disease-specific clonotypes in T1D, providing biomarker candidates to monitor pathogenic T cell frequencies in blood for assessing disease activity and therapeutic response.
Authors
Laurie G. Landry, Kristen L. Wells, Amanda M. Anderson, Kristen R. Miller, Kenneth L. Jones, Aaron W. Michels, Maki Nakayama
Abstract
Few HIV-specific epitopes restricted by non-classical HLA-E have been described, and even less is known about the functional profile of responding CD8 T cells (CD8s). This study evaluates the functional characteristics of CD8s targeting the Gag epitope KF11 (KAFSPEVIPMF) restricted by either HLA-E (E-CD8s) or HLA-B57 (B57-CD8s). CD8s from eight people with HIV (PWH) were cocultured with KF11 peptide presented by cell lines expressing HLA-B*57:01, HLA-E*01:01 or E*01:03. CD8 responses were analyzed using scRNA-seq and scTCR-seq. Supernatants were also assessed for soluble protein profiling. HLA-I multimers were developed to identify CD8s restricted by HLA-B57 and/or HLA-E ex vivo. B57-CD8s secreted higher levels of cytotoxic cytokines such as IFNγ, whereas E-CD8s produced more chemotactic cytokines, including RANTES, CXCL10 (IP-10), and IL27, findings which were corroborated through scRNA sequencing. TCR clonotypes stimulated by KF11 were cross-restricted by HLA-B*57 and HLA-E*01/03 as demonstrated by in vitro T cell reporter assays and ex vivo multimer screening. Ex vivo CD8s were singly restricted by HLA-B57 and HLA-E, with dual restriction only observed in PWH with lower viral load. These findings demonstrate that certain HIV-specific CD8s in PWH exhibit dual restriction by HLA-B*57 and HLA-E*01/03, leading to functionally distinct immune responses depending upon the restricting allele(s).
Authors
Kevin J. Maroney, Michael A. Rose, Allisa K. Oman, Abha Chopra, Hua-Shiuan Hsieh, Zerufael Derza, Rachel Waterworth, Mark A. Brockman, Spyros A. Kalams, Anju Bansal, Paul A. Goepfert
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