Abstract
Processes that promote white adipocyte inflammatory function remain incompletely defined. Here, we demonstrated that type I interferon–dependent (IFN-I–dependent) skewing of adipocyte glycolysis, nicotinamide adenine dinucleotide (NAD+) utilization, and pyruvate kinase isozyme M2 (PKM2) function may contribute to increased systemic and tissue inflammation and disease severity in obesity. Notably, chemical and/or genetic inhibition of glycolysis, the NAD+ salvage pathway, or PKM2 restricted IFN-I–dependent increase in adipocyte inflammatory cytokine production. Further, genetic or small molecule targeting of PKM2 function in vivo was sufficient to reduce systemic and tissue inflammation and metabolic disease severity in obese mice, in an adipocyte PKM2-dependent manner. Further, white adipose tissue of individuals living with obesity and metabolic disease, compared with metabolically healthy individuals with obesity, showed an increase in expression of inflammatory and metabolic genes, while small molecule targeting of PKM2 function contributed to reduced IFN-I–driven inflammatory cytokine production by primary human adipocytes. Together, our findings invoke the IFN-I/PKM2 axis as a potential target for modulating adipocyte dysregulated inflammation.
Authors
Michelle S.M.A. Damen, Pablo C. Alarcon, Calvin C. Chan, Traci E. Stankiewicz, Hak Chung, Keisuke Sawada, Cassidy J. Ulanowicz, John Eom, Jarren R. Oates, Jennifer L. Wayland, Jessica R. Doll, Rajib Mukherjee, Miki Watanabe-Chailland, Lindsey Romick-Rosendale, Sara Szabo, Michael A. Helmrath, Joan Sanchez-Gurmaches, Maria E. Moreno-Fernandez, Senad Divanovic
Abstract
HOXB13 is a prostate-specific transcription factor best known for its role as an androgen receptor (AR) cofactor. Recent evidence suggests that HOXB13 plays critical AR-independent functions in repressing lipogenic programs and promoting prostate cancer (PCa) metastasis. However, the mechanisms linking HOXB13 loss to tumor metastasis remain unclear. Here, we show that p300 and CBP co-occupy lipogenic enhancers suppressed by HOXB13 and HDAC3 and are essential for enhancer activation and target gene expression following HOXB13 depletion. Loss of HOXB13 induces lipid-sensitive matrix metalloproteinases (MMPs), promoting increased cell motility. Importantly, pharmacological inhibition of p300 and CBP blocks HOXB13-loss-driven lipogenesis, reduces MMP expression, and decreases cell migration in vitro and tumor metastasis in vivo. Analysis of clinical samples revealed that HOXB13 expression is reduced in metastatic hormone-sensitive PCa compared with matched primary tumors, further supporting its role in tumor metastasis. These findings demonstrate that HOXB13 downregulation promotes PCa metastasis through p300- and CBP-dependent lipogenic and motility pathways, which may be targeted by p300 inhibition.
Authors
Xiaodong Lu, Liu Peng, Qi Chu, Samantha Ye, Mingyang Liu, Maha Hussain, Mehmet A. Bilen, Lara R. Harik, Jonathan Melamed, Jonathan C. Zhao, Jindan Yu
Abstract
Fibroblast to myofibroblast transition is a critical event required for effective tissue repair. In pathologic wound repair processes, such as type 2 diabetes (T2D), fibroblast to myofibroblast transition is impaired. The exact factors that control this transition in wounds are unclear. Here, using human tissue and murine transgenic models, we show that the histone methyltransferase SETDB2 is elevated in diabetic wound fibroblasts and TNF-α represses fibroblast to myofibroblast transition via Setdb2. We identified that TNF-α increases Setdb2 in fibroblasts via a JAK1,3/STAT3 signaling pathway, where pharmacologic or genetic manipulation of this pathway altered Setdb2 in fibroblasts. We also found that fibroblasts treated with pro-inflammatory macrophage supernatants displayed increased Setdb2 and downregulated myofibroblast genes; inhibition of the TNF-α receptor reduced the upregulation of Setdb2. In diabetes, we showed that TNF-α signaling was increased in wound fibroblasts, which functions to increase Setdb2 expression and represses fibroblast to myofibroblast transition. Fibroblast-specific knockdown of SETDB2 and therapeutic inhibition of JAK1,3/STAT3 improved diabetic wound repair, where wound fibroblasts expressed increased myofibroblast genes. This study is the first to our knowledge to identify an epigenetic mechanism for reduced fibroblast to myofibroblast transition in diabetic wounds. Therapeutic targeting of the TNF-α/STAT3/SETDB2 axis in wound fibroblasts may improve diabetic wound healing.
Authors
Tyler M. Bauer, Kevin D. Mangum, Samuel D. Buckley, James Shadiow, Amrita D. Joshi, Christopher O. Audu, Jadie Y. Moon, Lindsey D. Hughes, Rachel Bogel, Lam C. Tsoi, Qinmennge Li, He Zhang, Steven Kunkel, Johann E. Gudjonsson, Frank M. Davis, Katherine A. Gallagher
Abstract
Matrix remodeling by metalloproteinases (MMPs) is essential for maintaining muscle homeostasis; however, their dysregulation can drive degenerative processes. By interrogating biopsy RNA-Seq data, we showed that MMP expression correlated with disease severity in facioscapulohumeral muscular dystrophy (FSHD). In the iDUX4pA FSHD mouse model, MMP levels also progressively increased in response to double homeobox 4–induced (DUX4-induced) muscle degeneration. Single-cell RNA-Seq further identified fibroadipogenic progenitors (FAPs) and macrophages as the primary sources of MMPs, particularly MMP2, MMP14, and MMP19, in dystrophic muscle. Treatment with the pan-MMP inhibitor batimastat alleviated inflammation and fibrosis, improved muscle structure, and decreased the number of FAPs and infiltrating macrophages. These findings underscore the role of MMPs in driving muscle degeneration in FSHD, highlight MMPs as functional biomarkers of disease, and support MMP inhibitors as a DUX4-independent therapeutic approach to limit fibroadipogenesis and promote muscle regeneration.
Authors
Usuk Jung, Erdong Wei, Haseeb Ahsan, Ana Mitanoska, Kenric Chen, Michael Kyba, Darko Bosnakovski
Abstract
About one-third of neonatal seizures do not respond to the first-line anticonvulsant phenobarbital, which activates phasic inhibition and whose effectiveness decreases over time. Whether enhancing tonic inhibition can treat refractory seizures or status epilepticus in neonates remains uncertain. We evaluated the effect of recurrent seizure-like events (SLE) on α5– and δ–GABAA receptor (α5- and δ-GABAAR) subunit expression and tonic inhibition in neonatal C57BL/6J mice (P6–9, both sexes) using acute brain slices. We investigated the impact of THIP (gaboxadol) on neonatal behavioral seizures, neuronal apoptosis, and neurodegeneration in vivo. We found neonatal neocortical expression of α5- and δ-GABAAR subunits. Blocking α5-GABAARs with L-655,708 did not affect acute neonatal SLE, whereas enhancing δ-GABAARs with THDOC, a neurosteroid, reduced them. The α5- and δ-GABAAR membrane expression increased after 8 hours of neonatal SLE and correlated with increased δ-mediated conductance but not α5-mediated conductance. Enhancing tonic inhibition was more effective in reducing recurrent neonatal SLE (8 hours) compared with early treatment. Increasing tonic inhibition reduced the duration, severity, and number of kainic acid–induced in vivo neonatal behavioral seizures without increasing neurodegeneration or apoptosis. We conclude that recurrent neonatal seizures increase tonic inhibition. Therefore, enhancing tonic inhibition may be a treatment strategy for prolonged neonatal status epilepticus.
Authors
Gage T. Liddiard, Gordon F. Buchanan, Mark L. Schultz, Joseph Glykys
Abstract
Insulin resistance impairs benefits of lipid-lowering treatment, as evidenced by higher cardiovascular disease risk in individuals with type 2 diabetes versus those without. Because platelet activity is higher in insulin-resistant patients and promotes atherosclerosis progression, we questioned whether platelets impair inflammation resolution in plaques during lipid lowering. In mice with obesity and insulin resistance, we induced advanced plaques and then implemented lipid lowering to promote atherosclerotic plaque inflammation resolution. Concurrently, mice were treated with either platelet-depleting or control antibodies for 3 weeks. Platelet activation and insulin resistance were unaffected by lipid lowering. Both antibody-treated groups showed reduced plaque macrophages, but plaque cellular and structural composition differed. In platelet-depleted mice, single-cell RNA-seq revealed dampened inflammatory gene expression in plaque macrophages and an expansion of a subset of Fcgr4+ macrophages having features of inflammation-resolving, phagocytic cells. Necrotic core size was smaller and collagen content greater, resembling stable human plaques. Consistent with the mouse results, clinical data showed that patients with lower platelet counts had decreased proinflammatory signaling pathways in circulating nonclassical monocytes after lipid lowering. These findings highlight that platelets hinder inflammation resolution in atherosclerosis during lipid-lowering treatment. Identifying novel platelet-targeted therapies following lipid-lowering treatment in individuals with insulin resistance may be a promising therapeutic approach to promote atherosclerotic plaque inflammation resolution.
Authors
Maria Laskou, Sofie Delbare, Michael Gildea, Ada Weinstock, Vitor De Moura Virginio, Maxwell La Forest, Franziska Krautter, Casey Donahoe, Letizia Amadori, Natalia Eberhardt, Tessa J. Barrett, Chiara Giannarelli, Jeffrey S. Berger, Edward A. Fisher
Abstract
Glutaminolysis is enhanced in T cells of patients with lupus and in Tfh cells, a critical subset of CD4+ T cells that provide help to autoreactive B cells, in lupus mice. Glutaminolysis inhibitors reduced lupus activity in association with a decreased frequency of Th17 cells in mice. Here, we thought to determine the role of glutaminolysis in murine Tfh cells. The pharmacological inhibition of glutaminolysis with DON reduced the expression of the critical costimulatory molecule ICOS on lupus Tfh cells, in association with a reduction of autoantibody production and B cell differentiation markers. Accordingly, profound transcriptomic and metabolic changes, including a reduction of glycolysis, were induced by DON in lupus Tfh cells, whereas healthy Tfh cells showed minor changes. The T cell–specific genetic inhibition of glutaminolysis largely phenocopied the effects of DON on Tfh cells and B cells in an autoimmune genetic background with minor changes in Tfh and B cells in healthy controls. Furthermore, we showed that T cell–specific glutaminolysis inhibition impaired T-dependent humoral responses in autoimmune mice as well as their Tfh response to a viral infection. Overall, these results suggest that lupus Tfh cells have a greater intrinsic requirement of glutaminolysis for their helper functions.
Authors
Seung-Chul Choi, Yong Ge, Milind V. Joshi, Damian Jimenez, Abigail Castellanos Garcia, Cassandra LaPlante, Lauren T. Padilla, Chaoyu Ma, Nu Zhang, Jeffrey C. Rathmell, Mansour Mohamadzadeh, Laurence Morel
Abstract
Focal cortical dysplasia (FCD) is a major cause of refractory epilepsy and is associated with pathogenic variants in mTOR pathway genes, including DEPDC5, the most common cause of familial focal epilepsy. The mechanisms of epileptogenesis associated with FCD and hyperactive mTOR signaling remain unclear in DEPDC5-related epilepsy. To test whether DEPDC5 loss leading to seizures requires in utero cortical developmental defects or whether postnatal neuronal dysfunction of mTORC1 is sufficient to drive seizures, we developed a postnatal focal cortical Depdc5-knockout mouse model. Postnatal day 0–1 Depdc5-floxed mice received unilateral motor cortex injections of either AAV-Cre-GFP or control AAV-GFP. The AAV-Cre-GFP–injected hemisphere had decreased DEPDC5 levels with hyperactivation of mTOR that increased with age compared with both the contralateral hemisphere and the AAV-GFP–injected mice. Cortical lamination was not disrupted by postnatal DEPDC5 loss. Pathologic hallmarks of FCDs were identified in the Depdc5-knockout hemisphere, including increased SMI-311 neurofilament staining, hypomyelination, astrogliosis, and microglial activation. Mice with postnatal cortical DEPDC5 loss exhibited lower seizure thresholds, increased focal seizures, and increased rates of seizure-induced death compared with control mice. This study demonstrates that postnatal DEPDC5 loss and subsequent mTOR hyperactivation without disruption of cortical migration is sufficient to cause epilepsy.
Authors
Karenna J. Groff, Yini Liang, Christopher Morici, Jinita B. Modasia, Leena Mehendale, Nishtha Gupta, Angelica D’Amore, Yongho Choe, Mustafa Q. Hameed, Alexander Rotenberg, Mustafa Sahin, Christopher J. Yuskaitis
Abstract
Glomerular inflammation and podocyte loss are the hallmarks of chronic kidney disease (CKD) progression. Understanding how podocytes and their microenvironment regulate inflammation is critical for developing effective therapies. In this study, we identified C-C chemokine ligand 5 (CCL5) as an inflammatory mediator elevated in injured podocytes, based on analyses of both human kidney biopsies and mouse models of CKD. We discovered that CCL5 exerts paradoxical effects in nephropathy; while it protects podocytes in vitro, it exacerbates glomerular injury in vivo. Recombinant CCL5 and podocyte-specific CCL5 overexpression promoted cell survival and reduced apoptosis in cultured podocytes. However, in adriamycin-induced nephropathy, CCL5 worsened glomerular injury, increasing proteinuria, glomerulosclerosis, and podocyte loss. Bone marrow (BM) transplantation experiments revealed that CCL5 in BM-derived cells — not kidney-resident cells — drove disease progression. CCL5 deficiency in BM-derived cells conferred protection by increasing reparative M2 macrophages, whereas endogenous CCL5 promoted M1 polarization, inhibited M2 differentiation, and triggered M2-to-M1 transition. These findings demonstrate that while CCL5 supports podocyte survival, its expression in BM-derived cells promotes inflammatory macrophage phenotypes and glomerular injury. The harmful immune effects of CCL5 in BM-derived cells outweigh its podocyte-protective role, highlighting the importance of cell-targeted strategies to mitigate kidney damage.
Authors
Ika N. Kadariswantiningsih, Issei Okunaga, Kaho Yamasaki, Maulana A. Empitu, Hiroyuki Yamada, Shin-ichi Makino, Akitsu Hotta, Hideo Yagita, Masashi Aizawa, Ryo Koyama-Nasu, Motoko Y. Kimura, Narihito Tatsumoto, Katsuhiko Asanuma
Abstract
Rheumatoid arthritis (RA) is a common systemic autoimmune disorder. Fibroblast-like synoviocytes (FLS) have emerged as an attractive target for nonimmunosuppressive RA therapy, but there are no approved drugs targeting FLS. The receptor protein tyrosine phosphatase sigma (PTPRS) negatively regulates FLS migration and has been proposed as a target for FLS-directed RA therapy. Here we examined the impact of sequence variations on efficacy of an FLS-targeted biologic composed of Fc-fused PTPRS IgG-like domains Ig1 and Ig2 (Ig1&2-Fc). Engineering the linker and Fc tag improved effectiveness of human Ig1&2-Fc in assays of FLS migration and a mouse model of arthritis. Treatment of mice with Ig1&2-Fc over 4 months revealed no signs of toxicity or organ pathology. Finally, we show potential of Ig1&2-Fc coadministration in combination or as a bispecific fusion with a tumor necrosis factor-α inhibitor. Combination treatment of mouse tumor necrosis factor receptor 2 (mTnfr2) with Ig1&2-Fc resulted in increased efficacy in suppressing arthritis beyond single-agent treatment. When administered as a dual-action bispecific, Ig1&2 fused to mTnfr2 proved more efficacious at suppressing arthritis than mTnfr2 alone. This study illustrates the potential of Ig1&2-Fc as a combination or bispecific therapy with disease-modifying antirheumatic drugs to improve patient outcomes in RA.
Authors
Sterling H. Ramsey, Zixuan Zhao, Megan C. Lee, Thales Hein da Rosa, Ava C. Schneider, Miriam Bollmann, Nour Dada, Katie E. Frizzi, May M. Han, Jaeyeon Kim, Martina Zoccheddu, Nigel A. Calcutt, Gary S. Firestein, James W. Bryson, Mattias N.D. Svensson, Eugenio Santelli, Stephanie M. Stanford, Nunzio Bottini
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