Diabetic nephropathy (DN) arises from systemic and local changes in glucose metabolism and hemodynamics. We have reported that many glycolytic and mitochondrial enzymes, such as pyruvate kinase M2 (PKM2), were elevated in renal glomeruli of DN-protected type 1 and type 2 diabetic patients. Here, mice with PKM2-specific overexpression in podocytes (PPKM2Tg) were generated to uncover its renal protective function as potential therapeutic target, which prevented elevated albumin-creatinine ratio (ACR), mesangial expansion, basement membrane thickness and podocyte foot process effacement after 7-months of STZ-induced diabetes. Further, diabetes-induced impairment of glycolytic rate and mitochondrial function were normalized in diabetic PPKM2Tg glomeruli, in concordance with elevated Ppargc1a and Vegf expressions. Restored VEGF expression improved glomerular maximal mitochondrial function in diabetic PPKM2Tg and WT mice. Elevated VEGF levels were observed in the glomeruli of DN-protected patients with chronic type 1 diabetes, and clinically correlated with estimated GFR, but not glycemic control. Mechanistically, the preservations of mitochondrial function and VEGF expression were dependent on tetrameric structure and enzymatic activities of PKM2 in podocyte. These findings demonstrated that PKM2 structure and enzymatic activation in podocytes can preserve entire glomerular mitochondrial function against toxicity of hyperglycemia via paracrine factors such as VEGF and prevent DN progression.
Jialin Fu, Takanori Shinjo, Qian Li, Ronald St-Louis, Kyoungmin Park, Marc G. Yu, Hisashi Yokomizo, Fabricio Simao, Qian Huang, I-Hsien Wu, George L. King
Primary ovarian insufficiency (POI) affects 1% of women and carries significant medical and psychosocial sequelae. Approximately 10% of POI has a defined genetic cause, with most implicated genes relating to biological processes involved in early fetal ovary development and function. Recently, Ythdc2, an RNA helicase and N6-methyladenosine (m6a) reader, has emerged as a novel regulator of meiosis in mice. Here, we describe homozygous pathogenic variants in YTHDC2 in three women with early-onset POI from two families: c. 2567C>G, p.P856R in the helicase-associated (HA2) domain; and c.1129G>T, p.E377*. We demonstrate that YTHDC2 is expressed in the developing human fetal ovary and is upregulated in meiotic germ cells, together with related meiosis-associated factors. The p.P856R variant results in a less flexible protein that likely disrupts downstream conformational kinetics of the HA2 domain, whereas the p.E377* variant truncates the helicase core. Taken together, our results reveal that YTHDC2 is a key new regulator of meiosis in humans and pathogenic variants within this gene are associated with POI.
Sinead M. McGlacken-Byrne, Ignacio del Valle, Polona Le Quesne Stabej, Laura Bellutti, Luz Garcia-Alonso, Louise A. Ocaka, Miho Ishida, Jenifer P. Suntharalingham, Andrey Gagunashvili, Olumide K. Ogunbiyi, Talisa Mistry, Federica Buonocore, GOSgene, Berta Crespo, Nadjeda Moreno, Paola Niola, Tony Brooks, Caroline E. Brain, Mehul T. Dattani, Daniel Kelberman, Roser Vento-Tormo, Carlos F. Lagos, Gabriel Livera, Gerard S. Conway, John C. Achermann
IgA nephropathy (IgAN) is a leading cause of kidney failure, yet little is known about the immunopathogenesis of this disease. IgAN is characterized by deposition of IgA in the kidney glomeruli, but the source and stimulus for IgA production is not known. Clinical and experimental data suggest a role for aberrant immune responses to mucosal microbiota in IgAN, and in some countries of high disease prevalence tonsillectomy is regarded as standard-of-care therapy. To evaluate the relationship between microbiota and mucosal immune responses we characterized the tonsil microbiota in patients with IgAN versus non-related household-matched control subjects and identified increased carriage of the genus Neisseria and elevated Neisseria-targeted serum IgA in IgAN cases. We reverse-translated these findings in experimental IgAN driven by BAFF overexpression in BAFF-transgenic mice, rendered susceptible to Neisseria infection by introduction of a humanized CEACAM-1 transgene (B x hC-Tg). Colonization of B x hC-Tg mice with Neisseria yielded augmented levels of systemic Neisseria-specific IgA. Using a custom ELISPOT assay, we discovered anti-Neisseria-specific IgA-secreting cells within in the kidneys of these mice. These findings suggest a role for cytokine-driven aberrant mucosal immune responses to oropharyngeal pathobionts such as Neisseria in the immunopathogenesis of IgAN. Furthermore, in the presence of excess BAFF, pathobiont-specific IgA can be produced in situ within the kidney.
Elissa G. Currie, Bryan Coburn, Elisa A. Porfilio, Ping Lam, Olga L. Rojas, Jan Novak, Stuart Yang, Raad B. Chowdhury, Lesley A. Ward, Pauline W. Wang, Khashayar Khaleghi, James An, Sarah Q. Crome, Michelle A. Hladunewich, Sean J. Barbour, Daniel C. Cattran, Rulan S. Parekh, Christoph Licht, Rohan John, Rupert Kaul, Kenneth Croitoru, Scott D. Gray-Owen, David S. Guttman, Jennifer L. Gommerman, Heather N. Reich
Prion protein (PrP) concentration controls the kinetics of prion replication and is a genetically and pharmacologically validated therapeutic target for prion disease. In order to evaluate PrP concentration as a pharmacodynamic biomarker and assess its contribution to known prion disease risk factors, we developed and validated a plate-based immunoassay reactive for PrP across six species of interest and applicable to brain and cerebrospinal fluid (CSF). PrP concentration varies dramatically between different brain regions in mice, cynomolgus macaques, and humans. PrP expression does not appear to contribute to the known risk factors of age, sex, or common PRNP genetic variants. CSF PrP is lowered in the presence of rare pathogenic PRNP variants, with heterozygous carriers of P102L displaying 55% and of D178N just 31% the CSF PrP concentration of mutation-negative controls. In rodents, pharmacologic reduction of brain Prnp RNA is reflected in brain parenchyma PrP, and in turn in CSF PrP, validating CSF as a sampling compartment for the effect of PrP-lowering therapy. Our findings support the use of CSF PrP as a pharmacodynamic biomarker for PrP-lowering drugs, and suggest that relative reduction from individual baseline CSF PrP concentration may be an appropriate marker for target engagement.
Meredith A. Mortberg, Hien T. Zhao, Andrew G. Reidenbach, Juliana E. Gentile, Eric Kuhn, Jill O'Moore, Patrick M. Dooley, Theresa R. Connors, Curt Mazur, Shona W. Allen, Bianca A. Trombetta, Alison J. McManus, Matthew R. Moore, Jiewu Liu, Deborah E. Cabin, Holly B. Kordasiewicz, Joel Mathews, Steven E. Arnold, Sonia M. Vallabh, Eric Vallabh Minikel
BACKGROUND. Accumulation of advanced glycation endproducts (AGEs) may contribute to the pathophysiology of type 2 diabetes and its vascular complications. AGEs are widely present in food, but whether restricting AGE intake improves risk factors for type 2 diabetes and vascular dysfunction is controversial. RESEARCH DESIGN AND METHODS. Abdominally obese but otherwise healthy individuals were randomly assigned to a specifically designed 4-week diet low or high in AGEs in a double blind parallel-design. Insulin sensitivity, secretion, and clearance were assessed by a combined hyperinsulinemic-euglycemic and hyperglycemic clamp. Micro- and macrovascular function, inflammation, and lipid profile were assessed by state-of-art in vivo measurements and biomarkers. Specific urinary and plasma AGEs Nε-(carboxymethyl)lysine (CML), Nε-(1-carboxyethyl)lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were assessed by mass spectrometry. RESULTS. In 73 individuals (22 males, mean ± SD age and BMI 52 y ± 14, 30.6 kg/m2 ± 4.0), intake of CML, CEL, and MG-H1 differed 2.7, 5.3, and 3.7-fold between the low and high AGE diets, which led to corresponding changes of these AGEs in urine and plasma. Despite this, there was no difference in insulin sensitivity, secretion, or clearance, micro- and macrovascular function, overall inflammation, or lipid profile between the low and high dietary AGE groups (all p for treatment effects > 0.05). CONCLUSIONS. This comprehensive RCT demonstrates very limited biological consequences of a 4-week diet low or high in AGEs in abdominally obese individuals. TRIAL REGISTRATION. clinicaltrials.gov: NCT03866343, trialregister.nl: NTR7594. FUNDING. Diabetesfonds and ZonMw.
Armand M A Linkens, Alfons J. Houben, Petra M Niessen, Nicole Wijckmans, Erica de Goei, Mathias D.G. Van den Eynde, Jean L. J. M. Scheijen, Marjo Waarenburg, Andrea Mari, Tos T.J.M. Berendschot, Lukas Streese, Henner Hanssen, Martien C.J.M. van Dongen, Christel van Gool, Coen D.A. Stehouwer, Simone JPM Eussen, Casper Schalkwijk.
SARS-CoV-2 provokes a robust T cell response. Peptide-based studies exclude antigen processing and presentation biology and may influence T cell detection studies. To focus on responses to whole virus and complex antigens, we used intact SARS-CoV-2 and full-length proteins with dendritic cells (DC) to activate CD8 and CD4 T cells from convalescent persons. T cell receptor (TCR) sequencing showed partial repertoire preservation after expansion. Resultant CD8 T cells recognize SARS-CoV-2-infected respiratory tract cells, and CD4 T cells detect inactivated whole viral antigen. Specificity scans with proteome-covering protein/peptide arrays show that CD8 T cells are oligospecific per subject and that CD4 T cell breadth is higher. Some CD4 T cell lines enriched using SARS-CoV-2 cross-recognize whole seasonal coronavirus (sCoV) antigens, with protein, peptide, and HLA restriction validation. Conversely, recognition of some epitopes is eliminated for SARS-CoV-2 variants, including spike (S) epitopes in the alpha, beta, gamma, and delta variant lineages.
Lichen Jing, Xia Wu, Maxwell P. Krist, Tien-Ying Hsiang, Victoria L. Campbell, Christopher L. McClurkan, Sydney M. Favors, Lawrence Hemingway, Charmie Godornes, Denise Q. Tong, Stacy Selke, Angela C. LeClair, Chul-Woo Pyo, Daniel E. Geraghty, Kerry J. Laing, Anna Wald, Michael Gale, Jr., David M. Koelle
Allergens have been identified as potential triggers in patients with atopic dermatitis (AD). AD patients are highly sensitive to cockroach allergen. The underlying mechanism, however, remains undetermined. Here, we established a cockroach allergen-induced AD-like mouse model and demonstrated that repeated exposure to cockroach allergen led to aggravated mouse skin inflammation, characterized by increased type 2 immunity, type 2 innate lymphoid cells (ILC2s), and mast cells. Increased skin mast cells were also observed in AD patients. AD mice with mast cell-deficient mice (kitW-sh/W-sh) showed diminished skin inflammation, suggesting that mast cells are required in allergen-induced skin inflammation. Furthermore, dendritic cell immuno-receptor (DCIR) is up-regulated in skin mast cells of AD patients and mediates allergen binding and uptake. DCIR-/- mice or reconstituted kitW-sh/W-sh mice with DCIR-/- mast cells showed a significant reduction in AD-like inflammation. Both in vitro and in vivo analyses demonstrated that DCIR-/- mast cells had reduced IgE-mediated mast cell activation and passive cutaneous anaphylaxis. Mechanistically, DCIR regulates allergen-induced IgE-mediated mast cell ROS generation and oxidation of calmodulin kinase II (ox-CaMKII). ROS-resistant CaMKII (MM-VVδ) prevents allergen-induced mast cell activation and inflammatory mediator release. Our study reveals a previously unrecognized DCIR-ROS-CaMKII axis that controls allergen-induced mast cell activation and AD-like inflammation.
Xiaoyan Luo, Jingsi Chen, Huan Yang, Xinyue Hu, Martin P. Alphonse, Yingchun Shen, Yuko Kawakami, Xiaoying Zhou, Wei Tu, Toshiaki Kawakami, Mei Wan, Nathan K. Archer, Hua Wang, Peisong Gao
Following myocardial infarction (MI), elderly patients have a poorer prognosis which may belinked to increased coronary microvessel susceptibility to injury. Interleukin-36 (IL-36), anewly discovered pro-inflammatory member of the IL-1 superfamily, may mediate this injurybut its role in the injured heart is currently not known. We firstly demonstrated the presence of IL-36(α/β) and its receptor (IL-36R) in ischaemia-reperfusion (IR) injured mouse hearts and,interestingly, noted that expression of both increased with ageing. An intravital modelfor imaging the adult and aged IR injured beating heart in real-time in vivo was used todemonstrate heightened basal and injury-induced neutrophil recruitment, and poorer bloodflow, in the aged coronary microcirculation when compared to adult hearts. An IL-36Rantagonist (IL-36Ra) significantly decreased neutrophil recruitment, improved blood flow andreduced infarct size in both adult and aged mice. This may be mechanistically explained byattenuated endothelial oxidative damage and VCAM-1 expression in IL-36Ra treated mice.Our findings of an enhanced age-related coronary microcirculatory dysfunction inreperfused hearts may explain the poorer outcomes in elderly patients following MI. Sincetargeting the IL-36/IL-36R pathway was vasculoprotective in aged hearts, it may potentially be a therapy for treating MI in the elderly.
Juma El-Awaisi, Dean P.J. Kavanagh, Marco R. Rink, Chris J. Weston, Nigel E. Drury, Neena Kalia
Infants born prematurely worldwide have up to a 50% chance of developing Bronchopulmonary Dysplasia (BPD), a clinical morbidity characterized by dysregulated lung alveolarization and microvascular development. It is known that Platelet-Derived Growth Factor Receptor Alpha positive (PDGFRA+) fibroblasts are critical for alveolarization, and that PDGFRA+ fibroblasts are reduced in BPD. A better understanding of fibroblast heterogeneity and functional activation status during pathogenesis is required to develop mesenchymal-targeted therapies for BPD. In this study, we utilized a neonatal hyperoxia mouse model (90% O2 PN0-PN7) and performed studies on sorted PDGFRA+ cells during injury and room air recovery. After hyperoxia injury, PDGFRA+ matrix and myofibroblasts decrease and PDGFRA+ lipofibroblasts increase by transcriptional signature and population size. PDGFRA+ matrix and myofibroblast recover during repair (PN10). After 7 days of in vivo hyperoxia, PDGFRA+ sorted fibroblasts have reduced contractility in vitro, reflecting loss of myofibroblast commitment. Organoids made with PN7 PDGFRA+ fibroblasts from hyperoxia mice exhibit reduced alveolar type 1 cell differentiation, suggesting reduced alveolar niche-supporting PDGFRA+ matrix fibroblast function. Pathway analysis predicted reduced WNT signaling in hyperoxia fibroblasts. In alveolar organoids from hyperoxia exposed fibroblasts WNT activation by CHIR increased size and number of alveolar organoids and enhanced alveolar type 2 cell differentiation.
Matthew R. Riccetti, Mereena George Ushakumary, Marion Waltamath, Jenna Green, John Snowball, Sydney E. Dautel, Mehari Endale, Bonny Lami, Jason Woods, Shawn K. Ahlfeld, Anne-Karina T. Perl
The molecular mechanisms that drive the acquisition of distinct neural crest cell (NCC) fates is still poorly understood. Here, we identify Prdm6 as an epigenetic modifier that temporally and spatially regulates the expression of NCC specifiers and determines the fate of a subset of migrating Cardiac NCCs (CNCCs). Using transcriptomic analysis, genetic and fate mapping approaches in transgenic mice, we show that disruption of Prdm6 is associated with impaired CNCC differentiation, delamination, and migration, and leads to patent ductus arteriosus (DA)and ventricular noncompaction. Bulk and single-cell RNA-seq analyses of DA and CNCC identify Prdm6 as a regulator of a network of CNCC specification genes including Wnt1, Tfap2b, and Sox9. Loss of Prdm6 in CNCCs diminishes its expression in pre-EMT cluster, resulting in the retention of NCC in the dorsal neural tube. This defect is associated with diminished H4K20 mono-methylation and G1-S progression and augmented Wnt1 transcript levels in pre-EMT and neural tube clusters, which we show is the major driver of the impaired CNCC migration. Altogether, these findings reveal Prdm6 as a key regulator of CNCC differentiation and migration and identify Prdm6 and its regulated network as potential targets for the treatment of congenital heart diseases.
Lingjuan Hong, Na Li, Victor Gasque, Sameet Mehta, Lupeng Ye, Yinyu Wu, Jinyu Li, Andreas Gewies, Jürgen Ruland, Karen K. Hirschi, Anne Eichmann, Caroline Hendry, David van Dijk, Arya Mani
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