Research Article
Abstract
Neutrophil granulocytes form the body’s first line of antibacterial defense, but they also contribute to tissue injury and noninfectious, chronic inflammation. Proteinase 3 (PR3) and neutrophil elastase (NE) are 2 abundant neutrophil serine proteases implicated in antimicrobial defense with overlapping and potentially redundant substrate specificity. Here, we unraveled a cooperative role for PR3 and NE in neutrophil activation and noninfectious inflammation in vivo, which we believe to be novel. Mice lacking both PR3 and NE demonstrated strongly diminished immune complex–mediated (IC-mediated) neutrophil infiltration in vivo as well as reduced activation of isolated neutrophils by ICs in vitro. In contrast, in mice lacking just NE, neutrophil recruitment to ICs was only marginally impaired. The defects in mice lacking both PR3 and NE were directly linked to the accumulation of antiinflammatory progranulin (PGRN). Both PR3 and NE cleaved PGRN in vitro and during neutrophil activation and inflammation in vivo. Local administration of recombinant PGRN potently inhibited neutrophilic inflammation in vivo, demonstrating that PGRN represents a crucial inflammation-suppressing mediator. We conclude that PR3 and NE enhance neutrophil-dependent inflammation by eliminating the local antiinflammatory activity of PGRN. Our results support the use of serine protease inhibitors as antiinflammatory agents.
Authors
Kai Kessenbrock, Leopold Fröhlich, Michael Sixt, Tim Lämmermann, Heiko Pfister, Andrew Bateman, Azzaq Belaaouaj, Johannes Ring, Markus Ollert, Reinhard Fässler, Dieter E. Jenne
Abstract
Disablement of cell death programs in cancer cells contributes to drug resistance and in some cases has been associated with altered translational control. As eukaryotic translation initiation factor 4E (eIF4E) cooperates with c-Myc during lymphomagenesis, induces drug resistance, and is a genetic modifier of the rapamycin response, we have investigated the effect of dysregulation of the ribosome recruitment phase of translation initiation on tumor progression and chemosensitivity. eIF4E is a subunit of eIF4F, a complex that stimulates ribosome recruitment during translation initiation by delivering the DEAD-box RNA helicase eIF4A to the 5′ end of mRNAs. eIF4A is thought to prepare a ribosome landing pad on mRNA templates for incoming 40S ribosomes (and associated factors). Using small molecule screening, we found that cyclopenta[b]benzofuran flavaglines, a class of natural products, modulate eIF4A activity and inhibit translation initiation. One member of this class of compounds, silvestrol, was able to enhance chemosensitivity in a mouse lymphoma model in which carcinogenesis is driven by phosphatase and tensin homolog (PTEN) inactivation or elevated eIF4E levels. These results establish that targeting translation initiation can restore drug sensitivity in vivo and provide an approach to modulating chemosensitivity.
Authors
Marie-Eve Bordeleau, Francis Robert, Baudouin Gerard, Lisa Lindqvist, Samuel M.H. Chen, Hans-Guido Wendel, Brigitte Brem, Harald Greger, Scott W. Lowe, John A. Porco Jr., Jerry Pelletier
Abstract
cGMP-dependent protein kinase II (cGKII; encoded by PRKG2) is a serine/threonine kinase that is critical for skeletal growth in mammals; in mice, cGKII deficiency results in dwarfism. Using radiographic analysis, we determined that this growth defect was a consequence of an elongated growth plate and impaired chondrocyte hypertrophy. To investigate the mechanism of cGKII-mediated chondrocyte hypertrophy, we performed a kinase substrate array and identified glycogen synthase kinase–3β (GSK-3β; encoded by Gsk3b) as a principal phosphorylation target of cGKII. In cultured mouse chondrocytes, phosphorylation-mediated inhibition of GSK-3β was associated with enhanced hypertrophic differentiation. Furthermore, cGKII induction of chondrocyte hypertrophy was suppressed by cotransfection with a phosphorylation-deficient mutant of GSK-3β. Analyses of mice with compound deficiencies in both protein kinases (Prkg2–/–Gsk3b+/–) demonstrated that the growth retardation and elongated growth plate associated with cGKII deficiency were partially rescued by haploinsufficiency of Gsk3b. We found that β-catenin levels decreased in Prkg2–/– mice, while overexpression of cGKII increased the accumulation and transactivation function of β-catenin in mouse chondroprogenitor ATDC5 cells. This effect was blocked by coexpression of phosphorylation-deficient GSK-3β. These data indicate that hypertrophic differentiation of growth plate chondrocytes during skeletal growth is promoted by phosphorylation and inactivation of GSK-3β by cGKII.
Authors
Yosuke Kawasaki, Fumitaka Kugimiya, Hirotaka Chikuda, Satoru Kamekura, Toshiyuki Ikeda, Naohiro Kawamura, Taku Saito, Yusuke Shinoda, Akiro Higashikawa, Fumiko Yano, Toru Ogasawara, Naoshi Ogata, Kazuto Hoshi, Franz Hofmann, James R. Woodgett, Kozo Nakamura, Ung-il Chung, Hiroshi Kawaguchi
Abstract
Cancer is associated with immune deficiency, but the biologic basis of this is poorly defined. Here we demonstrate that impaired actin polymerization results in CD4+ and CD8+ T cells from patients with chronic lymphocytic leukemia (CLL) exhibiting defective immunological synapse formation with APCs. Although this synapse dysfunction was in part a result of the CLL cells having poor APC function, defective actin polymerization was also identified in T cells from patients with CLL. We further demonstrate that, following contact with CLL cells, defects in immune synapse formation were induced in healthy allogeneic T cells. This required direct contact and was inhibited by blocking adhesion molecules on CLL B cells. In T cells from patients with CLL and in T cells from healthy individuals that had been in contact with CLL cells, recruitment of key regulatory proteins to the immune synapse was inhibited. Treatment of autologous T cells and CLL cells with the immunomodulating drug lenalidomide resulted in improved synapse formation. These results define what we believe to be a novel immune dysfunction in T cells from patients with CLL that has implications for both autologous and allogeneic immunotherapy approaches and identifies repair of immune synapse defects as an essential step in improving cancer immunotherapy approaches.
Authors
Alan G. Ramsay, Amy J. Johnson, Abigail M. Lee, Güllü Gorgün, Rifca Le Dieu, William Blum, John C. Byrd, John G. Gribben
Abstract
Stress-induced analgesia (SIA) is a key component of the defensive behavioral “fight-or-flight” response. Although the neural substrates of SIA are incompletely understood, previous studies have implicated the hypocretin/orexin (Hcrt) and nociceptin/orphanin FQ (N/OFQ) peptidergic systems in the regulation of SIA. Using immunohistochemistry in brain tissue from wild-type mice, we identified N/OFQ-containing fibers forming synaptic contacts with Hcrt neurons at both the light and electron microscopic levels. Patch clamp recordings in GFP-tagged mouse Hcrt neurons revealed that N/OFQ hyperpolarized, decreased input resistance, and blocked the firing of action potentials in Hcrt neurons. N/OFQ postsynaptic effects were consistent with opening of a G protein–regulated inwardly rectifying K+ (GIRK) channel. N/OFQ also modulated presynaptic release of GABA and glutamate onto Hcrt neurons in mouse hypothalamic slices. Orexin/ataxin-3 mice, in which the Hcrt neurons degenerate, did not exhibit SIA, although analgesia was induced by i.c.v. administration of Hcrt-1. N/OFQ blocked SIA in wild-type mice, while coadministration of Hcrt-1 overcame N/OFQ inhibition of SIA. These results establish what is, to our knowledge, a novel interaction between the N/OFQ and Hcrt systems in which the corticotropin-releasing factor and N/OFQ systems coordinately modulate the Hcrt neurons to regulate SIA.
Authors
Xinmin Xie, Jonathan P. Wisor, Junko Hara, Tara L. Crowder, Robin LeWinter, Taline V. Khroyan, Akihiro Yamanaka, Sabrina Diano, Tamas L. Horvath, Takeshi Sakurai, Lawrence Toll, Thomas S. Kilduff
Abstract
Type 2 congenital long QT syndrome (LQT-2) is linked to mutations in the human ether a-go-go–related gene (HERG) and is characterized by rate-corrected QT interval (QTc) prolongation, ventricular arrhythmias, syncope, and sudden death. Recognized triggers of these cardiac events include emotional and acoustic stimuli. Here we investigated the repeated occurrence of fever-induced polymorphic ventricular tachycardia and ventricular fibrillation in 2 LQT-2 patients with A558P missense mutation in HERG. ECG analysis showed increased QTc with fever in both patients. WT, A558P, and WT+A558P HERG were expressed heterologously in HEK293 cells and were studied using biochemical and electrophysiological techniques. A558P proteins showed a trafficking-deficient phenotype. WT+A558P coexpression caused a dominant-negative effect, selectively accelerated the rate of channel inactivation, and reduced the temperature-dependent increase in the WT current. Thus, the WT+A558P current did not increase to the same extent as the WT current, leading to larger current density differences at higher temperatures. A similar temperature-dependent phenotype was seen for coexpression of the trafficking-deficient LQT-2 F640V mutation. We postulate that the weak increase in the HERG current density in WT-mutant coassembled channels contributes to the development of QTc prolongation and arrhythmias at febrile temperatures and suggest that fever is a potential trigger of life-threatening arrhythmias in LQT-2 patients.
Authors
Ahmad S. Amin, Lucas J. Herfst, Brian P. Delisle, Christine A. Klemens, Martin B. Rook, Connie R. Bezzina, Heather A.S. Underkofler, Katherine M. Holzem, Jan M. Ruijter, Hanno L. Tan, Craig T. January, Arthur A.M. Wilde
Abstract
Adipose tissue inflammation is a characteristic of obesity. However, the mechanisms that regulate this inflammatory response and link adipose inflammation to systemic metabolic consequences are not fully understood. In this study, we have taken advantage of the highly restricted coexpression of adipocyte/macrophage fatty acid–binding proteins (FABPs) aP2 (FABP4) and mal1 (FABP5) to examine the contribution of these lipid chaperones in macrophages and adipocytes to local and systemic inflammation and metabolic homeostasis in mice. Deletion of FABPs in adipocytes resulted in reduced expression of inflammatory cytokines in macrophages, whereas the same deletion in macrophages led to enhanced insulin signaling and glucose uptake in adipocytes. Using radiation chimerism through bone marrow transplantation, we generated mice with FABP deficiency in bone marrow and stroma-derived elements in vivo and studied the impact of each cellular target on local and systemic insulin action and glucose metabolism in dietary obesity. The results of these experiments indicated that neither macrophages nor adipocytes individually could account for the total impact of FABPs on systemic metabolism and suggest that interactions between these 2 cell types, particularly in adipose tissue, are critical for the inflammatory basis of metabolic deterioration.
Authors
Masato Furuhashi, Raquel Fucho, Cem Z. Görgün, Gürol Tuncman, Haiming Cao, Gökhan S. Hotamisligil
Abstract
Infantile hemangioma is a benign endothelial tumor composed of disorganized blood vessels. It exhibits a unique life cycle of rapid postnatal growth followed by slow regression to a fibrofatty residuum. Here, we have reported the isolation of multipotential stem cells from hemangioma tissue that give rise to hemangioma-like lesions in immunodeficient mice. Cells were isolated based on expression of the stem cell marker CD133 and expanded from single cells as clonal populations. The CD133-selected cells generated human blood vessels 7 days after implantation in immunodeficient mice. Cell retrieval experiments showed the cells could again form vessels when transplanted into secondary recipients. The human vessels expressed GLUT-1 and merosin, immunodiagnostic markers for infantile hemangioma. Two months after implantation, the number of blood vessels diminished and human adipocytes became evident. Lentiviral expression of GFP was used to confirm that the hemangioma-derived cells formed the blood vessels and adipocytes in the immunodeficient mice. Thus, when transplanted into immunodeficient mice, hemangioma-derived cells recapitulated the unique evolution of infantile hemangioma — the formation of blood vessels followed by involution to fatty tissue. In summary, this study identifies a stem cell as the cellular origin of infantile hemangioma and describes for what we believe is the first time an animal model for this common tumor of infancy.
Authors
Zia A. Khan, Elisa Boscolo, Arnaud Picard, Sarah Psutka, Juan M. Melero-Martin, Tatianna C. Bartch, John B. Mulliken, Joyce Bischoff
Abstract
Murine olfactory ensheathing cells (OECs) promote central nervous system axonal regeneration in models of spinal cord injury. We investigated whether OECs could induce a neuroplastic effect to improve the neurological dysfunction caused by hypoxic/ischemic stress. In this study, human OECs/olfactory nerve fibroblasts (hOECs/ONFs) specifically secreted trophic factors including stromal cell–derived factor–1α (SDF-1α). Rats with intracerebral hOEC/ONF implantation showed more improvement on behavioral measures of neurological deficit following stroke than control rats. [18F]fluoro-2-deoxyglucose PET (FDG-PET) showed increased glucose metabolic activity in the hOEC/ONF-treated group compared with controls. In mice, transplanted hOECs/ONFs and endogenous homing stem cells including intrinsic neural progenitor cells and bone marrow stem cells colocalized with specific neural and vascular markers, indicating stem cell fusion. Both hOECs/ONFs and endogenous homing stem cells enhanced neuroplasticity in the rat and mouse ischemic brain. Upregulation of SDF-1α and CXCR4 in hOECs/ONFs promoted neurite outgrowth of cocultured primary cortical neurons under oxygen glucose deprivation conditions and in stroke animals through upregulation of cellular prion protein (PrPC) expression. Therefore, the upregulation of SDF-1α and the enhancement of CXCR4 and PrPC interaction induced by hOEC/ONF implantation mediated neuroplastic signals in response to hypoxia and ischemia.
Authors
Woei-Cherng Shyu, Demeral David Liu, Shinn-Zong Lin, Wen-Wen Li, Ching-Yuan Su, Ying-Chen Chang, Hsiao-Jung Wang, Hsing-Won Wang, Chang-Hai Tsai, Hung Li
Abstract
Diabetes mellitus is the most common and rapidly growing cause of end-stage renal disease in developed countries. A classic hallmark of early diabetes mellitus includes activation of the renin-angiotensin system (RAS), which may lead to hypertension and renal tissue injury, but the mechanism of RAS activation is elusive. Here we identified a paracrine signaling pathway in the kidney in which high levels of glucose directly triggered the release of the prohypertensive hormone renin. The signaling cascade involved the local accumulation of succinate and activation of the kidney-specific G protein–coupled metabolic receptor, GPR91, in the glomerular endothelium as observed in rat, mouse, and rabbit kidney sections. Elements of signal transduction included endothelial Ca2+, the production of NO and prostaglandin (PGE2), and their paracrine actions on adjacent renin-producing cells. This GPR91 signaling cascade may serve to modulate kidney function and help remove metabolic waste products through renal hyperfiltration, and it could also link metabolic diseases, such as diabetes, or metabolic syndrome with RAS overactivation, systemic hypertension, and organ injury.
Authors
Ildikó Toma, Jung Julie Kang, Arnold Sipos, Sarah Vargas, Eric Bansal, Fiona Hanner, Elliott Meer, János Peti-Peterdi
No posts were found with this tag.
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)