The molecular mediators of cell death and inflammation in Alzheimer’s disease (AD) have yet to be fully elucidated. Caspase-8 is a critical regulator of several cell death and inflammatory pathways; however, its role in AD pathogenesis has not yet been examined in detail. In the absence of Caspase-8, mice are embryonic lethal due to excessive RIPK3-dependent necroptosis. Compound RIPK3 and Caspase-8 mutants rescue embryonic lethality, which we leveraged to examine the roles of these pathways in an amyloid beta (Aβ)-mediated mouse model of AD. We find that combined deletion of Caspase-8 and RIPK3, but not RIPK3 alone, leads to diminished Aβ deposition and microgliosis in the 5xFAD mouse model of AD. Despite its well-known role in cell death, Caspase-8 does not appear to impact cell loss in the 5xFAD model. In contrast, we found that Caspase-8 is a critical regulator of Aβ-driven inflammasome gene expression and IL-1β release. Interestingly, loss of RIPK3 had only a modest effect on disease progression suggesting that inhibition of necroptosis or RIPK3-mediated cytokine pathways are not critical during mid stages of Aβ amyloidosis. These findings suggest that therapeutics targeting Caspase-8 may represent a novel strategy to limit Aꞵ amyloidosis and neuroinflammation in AD.
Sushanth Kumar, Sakar Budhathoki, Christopher B. Oliveira, August D. Kahle, O. Yipkin Calhan, John R. Lukens, Christopher D. Deppmann
Cystic fibrosis (CF) is characterized by chronic bacterial infections leading to progressive bronchiectasis and respiratory failure. Pseudomonas aeruginosa (Pa) is the predominant opportunistic pathogen infecting the CF airways. The guanine nucleotide exchange factor Vav3 plays a critical role in Pa adhesion to the CF airways by inducing luminal fibronectin deposition that favors bacteria trapping. Here we report that Vav3 overexpression in CF is caused by upregulation of the mRNA-stabilizing protein HuR. We found that HuR accumulates in the cytoplasm of CF airway epithelial cells, binds to and stabilizes Vav3 mRNA. Interestingly, disruption of HuR-Vav3 mRNA interaction improved the CF epithelial integrity, inhibited the formation of the fibronectin-made bacterial docking platforms and prevented Pa adhesion to the CF airway epithelium. These findings indicate that targeting HuR represents a promising anti-adhesive approach in CF to prevent initial stages of Pa infection in a context of emergence of multidrug resistant pathogens.
Mehdi Badaoui, Cyril Sobolewski, Alexandre Luscher, Marc Bacchetta, Thilo Köhler, Christian van Delden, Michelangelo Foti, Marc Chanson
Although murine models of coronary atherosclerotic disease have been used extensively to determine mechanisms, limited new therapeutic options have emerged. Pigs with familial hypercholesterolemia (FH pigs) develop complex coronary atheromas that are almost identical to human lesions. We reported previously that insulin-like growth factor 1 (IGF-1) reduced aortic atherosclerosis and promoted features of stable plaque in a murine model. We administered human recombinant IGF-1 or saline (control) in atherosclerotic FH pigs for 6 months. IGF-1 decreased relative coronary atheroma in vivo (intravascular ultrasound) and reduced lesion cross-sectional area (postmortem histology). IGF-1 increased plaque’s fibrous cap thickness, and reduced necrotic core, macrophage content, and cell apoptosis consistent with promotion of a stable plaque phenotype. IGF-1 reduced circulating triglycerides, markers of systemic oxidative stress and CXCL12 chemokine levels. We used spatial transcriptomics (ST) to identify global transcriptome changes in advanced plaque compartments and to obtain mechanistic insights into IGF-1 effects. ST analysis shows that IGF-1 suppressed FOS/FOSB factors and gene expression of MMP9 and CXCL14 in plaque macrophages, suggesting possible involvement of these molecules in IGF-1’s effect on atherosclerosis. Thus, IGF-1 reduced coronary plaque burden and promoted features of stable plaque in a pig model, providing support for consideration of clinical trials.
Sergiy Sukhanov, Yusuke Higashi, Tadashi Yoshida, Svitlana Danchuk, Mitzi Alfortish, Traci Goodchild, Amy Scarborough, Thomas E. Sharp III, James S. Jenkins, Daniel Garcia, Jan Ivey, Darla L. Tharp, Jeffrey D. Schumacher, Zach Rozenbaum, Jay K Kolls, Douglas K. Bowles, David Lefer, Patrice Delafontaine
HIV non-progression despite persistent viraemia is rare among antiretroviral therapy (ART)-naïve adults, but relatively common among ART-naïve children. Previous studies indicate that ART-naïve paediatric slow-progressors (PSPs) adopt immune evasion strategies similar to those described in the SIV natural hosts. However, the mechanisms underlying this immunophenotype are not well understood. In a cohort of early-treated infants who underwent analytical treatment interruption (ATI) after 12 months of ART, expression of PD-1 on CD8+ T-cells immediately prior to ATI was the main predictor of slow progression during ATI (r=0.77, p=0.002). PD-1+ CD8+ T-cell frequency was also negatively correlated with CCR5 (r=-0.74, p=0.005) and HLA-DR (r=-0.63, p=0.02) expression on CD4+ T-cells and predicted stronger HIV-specific T-lymphocyte responses. In the CD8+ T-cell compartment of PSPs, we identified an enrichment of stem-like TCF-1+PD-1+ memory cells, whereas paediatric progressors and viraemic adults were populated with a terminally exhausted PD-1+CD39+ population. TCF-1+PD-1+ expression on CD8+ T-cells was associated with higher proliferative activity (r=0.41, p=0.03) and stronger Gag-specific effector functionality. These data prompt the hypothesis that the proliferative burst potential of stem-like HIV-specific cytotoxic cells could be exploited in therapeutic strategies to boost the antiviral response and facilitate remission in early-ART-treated infants with a preserved and non-exhausted T-cell compartment.
Vinicius Adriano Vieira, Nicholas Lim, Alveera Singh, Ellen Leitman, Reena R. D'Souza, Emily Adland, Maximilian Muenchhoff, Julia Roider, Miguel Á. Marín Lopez, Julieta Carabelli, Jennifer Giandhari, Andreas Groll, Pieter Jooste, Julia G. Prado, Christina Thobakgale, Krista Dong, Photini Kiepiela, Andrew J. Prendergast, Gareth Tudor-Williams, John Frater, Bruce D. Walker, Thumbi Ndung'u, Veron Ramsuran, Alasdair Leslie, Henrik N. Kløverpris, Philip Goulder
Pathogenic SOX2 variants typically cause severe ocular defects within a SOX2-disorder spectrum that includes hypogonadotropic hypogonadism (HH). We examined exome sequencing data from a large, well-phenotyped cohort of patients (n=1453) with Idiopathic Hypogonadotropic Hypogonadism (IHH) for pathogenic SOX2 variants to investigate the underlying pathogenic SOX2 spectrum and its associated phenotypes. We identified eight IHH individuals harboring heterozygous pathogenic SOX2 variants with variable ocular phenotypes. These variant proteins were tested in vitro to determine whether a causal relationship between IHH and SOX2 exists. We found that Sox2 is highly expressed in the hypothalamus of adult mice and colocalizes with KISS1 expression in the anteroventral periventricular nucleus of adult female mice. In vitro, shRNA suppression of mouse SOX2 protein in Kiss-expressing cell lines increases the levels of human kisspeptin luciferase transcription (hKISS-luc), while SOX2 overexpression represses hKiss-luc transcription. Further, four of the identified SOX2 variants prevented this SOX2-mediated repression of hKiss-luc. Together these data suggest that pathogenic SOX2 variants contribute to both anosmic and normosmic forms of IHH attesting to hypothalamic defects in the SOX2-disorder spectrum. Our study describes novel mechanisms contributing to SOX2-related disease and highlights the necessity of SOX2 screening in IHH genetic evaluation irrespective of associated ocular defects.
Jessica Cassin, Maria I. Stamou, Kimberly W. Keefe, Kaitlin Sung, Celine Bojo, Karen J. Tonsfeldt, Rebecca A. Rojas, Vanessa Ferreira Lopes, Lacey Plummer, Kathryn B. Salnikov, David L. Keefe Jr., Metin Ozata, Myron Genel, Neoklis A. Georgopoulos, Janet E. Hall, William F. Crowley Jr., Stephanie B. Seminara, Pamela L. Mellon, Ravikumar Balasubramanian
CD4+ cytotoxic T lymphocytes (CTLs) were recently implicated in immune-mediated inflammation and fibrosis progression of Graves’ orbitopathy (GO). However, little is known about therapeutic targeting CD4+ CTLs. Herein, we studied the effect of rapamycin, an approved mTORC1 inhibitor, in GO mouse model, in vitro and in refractory GO patients. In the adenovirus-induced model, rapamycin significantly decreased the incidence of orbitopathy. This was accompanied by reduction of CD4+ CTLs, and improvement of inflammation, adipogenesis and fibrosis in orbits. CD4+CTLs from active GO patients showed upregulation of mTOR pathway, while rapamycin decreased their proportions and cytotoxic function. Low-dose rapamycin treatment substantially improved diplopia and clinical activity score in steroid-refractory GO patients. Single-cell RNA sequencing revealed that eye motility improvement was closely related to suppression of inflammation and chemotaxis in CD4+ CTLs. In conclusion, rapamycin is a promising treatment for CD4+ CTL-mediated inflammation and fibrosis in GO.
Meng Zhang, Kelvin K.L. Chong, Zi-yi Chen, Hui Guo, Yu-feng Liu, Yong-yong Kang, Yang-jun Li, Ting-ting Shi, Kenneth Ka Hei Lai, Ming-qian He, Kai Ye, George J. Kahaly, Bing-yin Shi, Yue Wang
The periodic emergence of SARS-CoV-2 variants of concern (VOCs) with unpredictable clinical severity and ability to escape preexisting immunity emphasizes the continued need for antiviral interventions. Two small molecule inhibitors, molnupiravir (MK-4482), a nucleoside analog, and nirmatrelvir (PF-07321332), a 3C-like protease inhibitor, have recently been approved as monotherapy for use in high risk COVID-19 patients. As preclinical data are only available for rodent and ferret models, we here assessed the efficacy of MK-4482 and PF-07321332 alone and in combination against infection with the SARS-CoV-2 Delta VOC in the rhesus macaque COVID-19 model. Macaques were infected with the SARS-CoV-2 Delta variant and treated with either vehicle, MK-4482, PF-07321332 or a combination of MK-4482 and PF-07321332. Clinical exams were performed at 1, 2 and 4dpi to assess disease and virological parameters. Notably, use of MK-4482 and PF-07321332 in combination improved the individual inhibitory effect of both drugs resulting in milder disease progression, stronger reduction of virus shedding from mucosal tissues of the upper respiratory tract, stronger reduction of viral replication in the lower respiratory tract, and reduced lung pathology. Our data strongly indicate superiority of combined MK-4482 and PF-07321332 treatment of SARS-CoV-2 infections as demonstrated in the closest COVID-19 surrogate model.
Kyle Rosenke, Matthew C. Lewis, Friederike Feldmann, Eric Bohrnsen, Benjamin Schwarz, Atsushi Okumura, W. Forrest Bohler, Julie Callison, Carl Shaia, Catharine Bosio, Jamie Lovaglio, Greg Saturday, Michael Jarvis, Heinz Feldmann
Central integration of peripheral appetite-regulating signals ensures maintenance of energy homeostasis. Thus, plasticity of circulating molecule access to neuronal circuits involved in feeding behavior plays a key role in the adaptive response to metabolic changes. However, the mechanisms involved remain poorly understood despite their relevance for therapeutic development. Here, we investigated the role of median eminence mural cells, including smooth muscle cells and pericytes, in modulating gut hormone effects on orexigenic/anorexigenic circuits. We found that conditional activation of median eminence vascular cells impinged on local blood flow velocity, and altered ghrelin-stimulated food intake by delaying ghrelin access to target neurons. Thus, activation of median eminence vascular cells modulates food intake in response to peripheral ghrelin by reducing local blood flow velocity and access to the metabolic brain.
Nicola Romanò, Chrystel Lafont, Pauline Campos, Anne Guillou, Tatiana Fiordelisio, David J. Hodson, Patrice Mollard, Marie Schaeffer
Most overweight individuals do not develop diabetes due to compensatory islet responses to restore glucose homeostasis. Therefore, regulatory pathways that promote β-cell compensation are potential targets for treatment of diabetes. The melastatin transient receptor potential 7 protein (TRPM7), harboring a cation channel and a serine/threonine kinase, has been implicated in controlling cell growth and proliferation. Here, we report that selective deletion of Trpm7 in β-cells disrupts insulin secretion and leads to progressive glucose intolerance. We indicate that the diminished insulinotropic response in β-cell-specific Trpm7 knockout mice is caused by decreased insulin production due to an impaired enzymatic activity of this protein. Accordingly, high-fat fed mice with a genetic loss of TRPM7 kinase activity (Trpm7R/R) display a marked glucose intolerance accompanied by hyperglycemia. These detrimental glucoregulatory effects are engendered by reduced compensatory β-cell responses due to mitigated AKT/ERK signaling. Collectively, our data identify TRPM7 kinase as a novel regulator of insulin synthesis, β-cell dynamics, and glucose homeostasis under obesogenic diet.
Noushafarin Khajavi, Andreas Beck, Klea Ricku, Philipp Beyerle, Katharina Jacob, Sabrina F. Syamsul, Anouar Belkacemi, Peter S. Reinach, Pascale C.F. Schreier, Houssein Salah, Tanja Popp, Aaron Novikoff, Andreas Breit, Vladimir Chubanov, Timo D. Müller, Susanna Zierler, Thomas Gudermann
Chronic exposure to high-fat diets (HFD) worsens intestinal disease pathology, but acute effects of HFD in tissue damage remain unclear. Here, we used short-term HFD feeding in a model of intestinal injury and found sustained damage with increased cecal dead neutrophil accumulation, along with dietary lipid accumulation. Neutrophil depletion rescued enhanced pathology. Macrophages from HFD treated mice showed reduced capacity to engulf dead neutrophils. Macrophage clearance of dead neutrophils activates critical barrier repair and anti-inflammatory pathways including IL10, which was lost after acute HFD feeding and intestinal injury. IL10 overexpression restored intestinal repair after HFD feeding and intestinal injury. Macrophage exposure to lipids from the HFD prevented tethering and uptake of apoptotic cells and Il10 induction. Milk fat globule-EGF factor-8 (MFGE8) is a bridging molecule that facilitates macrophage uptake of dead cells. MFGE8 also facilitates lipid uptake, and we demonstrate that dietary lipids interfere with MFGE8-mediated macrophage apoptotic neutrophil uptake and subsequent Il10 production. Our findings demonstrate that HFD promotes intestinal pathology by interfering with macrophage clearance of dead neutrophils, leading to unresolved tissue damage.
Andrea A. Hill, Myunghoo Kim, Daniel F. Zegarra-Ruiz, Lin-Chun Chang, Kendra C. Norwood, Adrien Assié, Wan-Jung H. Wu, Michael C. Renfroe, Hyo W. Song, Angela M. Major, Buck S. Samuel, Joseph M. Hyser, Randy S. Longman, Gretchen E. Diehl
No posts were found with this tag.