Huang, Xie, Liu, Zheng et al. report that cryopreservation induces mitochondrial dysfunction in umbilical cord blood-derived hematopoietic stem and progenitor cells that adversely affects reconstitution. The cover art depicts the impact of cryopreservation on hematopoietic cells derived from umbilical cord blood and the mitigating effect of sulforaphane on their regenerative capacity. Image credit: Wenxi Ye.
Alcohol-associated liver disease represents a significant global health challenge, with gut microbial dysbiosis and bacterial translocation playing a critical role in its pathogenesis. Patients with alcohol-associated hepatitis had increased fecal abundance of mammalian viruses including retroviruses. This study investigated the role of endogenous retroviruses (ERVs) in the development of alcohol-associated liver disease. Transcriptomic analysis of duodenal and liver biopsies revealed increased expression of several human ERVs, including HERV-K and HERV-H, in patients with alcohol-associated liver disease compared with controls. Chronic-binge ethanol feeding markedly induced ERV abundance in intestinal epithelial cells, but not the liver of mice. Ethanol increased ERV expression and activated the Z-DNA binding protein 1 (Zbp1)–mixed lineage kinase domain-like pseudokinase (Mlkl) signaling pathways to induce necroptosis in intestinal epithelial cells. Antiretroviral treatment reduced ethanol-induced intestinal ERV expression, stabilized the gut barrier, and decreased liver disease in microbiota-humanized mice. Furthermore, mice with an intestine-specific deletion of Zbp1 were protected against bacterial translocation and ethanol-induced steatohepatitis. These findings indicate that ethanol exploits this pathway by inducing ERVs and promoting innate immune responses, which results in the death of intestinal epithelial cells, gut barrier dysfunction and liver disease. Targeting the ERV-Zbp1 pathway may offer new therapies for patients with alcohol-associated liver disease.
Noemí Cabré, Marcos F. Fondevila, Wenchao Wei, Tomoo Yamazaki, Fernanda Raya Tonetti, Alvaro Eguileor, Ricard Garcia-Carbonell, Abraham S. Meijnikman, Yukiko Miyamoto, Susan Mayo, Yanhan Wang, Xinlian Zhang, Thorsten Trimbuch, Seija Lehnardt, Lars Eckmann, Derrick E. Fouts, Cristina Llorente, Hidekazu Tsukamoto, Peter Stärkel, Bernd Schnabl
Lymphocyte activation gene-3 (LAG3) is a coinhibitory receptor expressed by various immune cells. While immunomodulatory potential of LAG3 is being explored in cancer and autoimmunity, there is no information on its role following organ transplantation. Our study investigated the functions of LAG3 in a mouse model of renal allograft rejection. LAG3-/- recipients rapidly reject MHC-mismatched renal allografts that are spontaneously accepted by WT recipients, with graft histology characteristic of antibody mediated rejection (ABMR). Depletion of recipient B cells but not CD8+ T cells significantly extended kidney allograft survival in LAG3-/- recipients. Treatment of WT recipients with an antagonistic LAG3 antibody enhanced anti-donor immune responses and induced kidney damage associated with chronic rejection. The studies of conditional LAG3-/- recipients and mixed bone marrow chimeras demonstrated that LAG3 expression on either T or B cells is sufficient to regulate anti-donor humoral immunity but not to induce acute allograft rejection. The numbers and proinflammatory functions of graft-infiltrating NK cells were markedly increased in LAG3-/- recipients suggesting that LAG3 also regulates the effector stage of ABMR. These results are the first to identify LAG3 as a regulator of immune responses to kidney allografts and a potential therapeutic target for ABMR prevention and treatment.
Michael Nicosia, Ran Fan, Juyeun Lee, Gabriella L. All, Victoria Gorbacheva, José Ignacio Valenzuela, Yosuke Yamamoto, Ashley Beavers, Nina Dvorina, William M. Baldwin III, Eduardo Chuluyan, Motoo Araki, Brian T. Gaudette, Robert L. Fairchild, Booki Min, Anna Valujskikh
Accumulating evidence implicates the gut microbiome (GMB) in the pathogenesis and progression of Alzheimer’s disease (AD). We recently showed that the GMB regulates reactive astrocytosis and Aβ plaque accumulation in male APPPS1-21 AD model mice. Yet, the mechanism(s) by which GMB perturbation alters reactive astrocytosis in a manner that reduces Aβ deposition remain unknown. Here, we performed metabolomics on plasma from mice treated with antibiotics (abx) and identified a significant increase in plasma propionate, a gut-derived short chain fatty acid, only in male mice. Administration of sodium propionate reduced reactive astrocytosis and Aβ plaques in APPPS1-21 mice, phenocopying the abx-induced phenotype. Astrocyte-specific RNA sequencing on abx and propionate treated mice showed reduced expression of pro-inflammatory and increased expression of neurotrophic genes. Next, we performed flow cytometry experiments where we found abx and propionate decreased peripheral RAR-related orphan receptor-γ (Rorγt)+ CD4+ (Th17) cells and IL-17 secretion, which positively correlated with reactive astrocytosis. Lastly, using an IL-17 monoclonal antibody to deplete IL-17, we found that propionate reduces reactive astrocytosis and Aβ plaques in an IL-17-dependent manner. Together, these results suggest that gut-derived propionate regulates reactive astrocytosis and Aβ amyloidosis by decreasing peripheral Th17 cells and IL-17 release. Thus, propionate treatment or strategies boosting propionate production may represent novel therapeutic strategies for AD.
Sidhanth Chandra, Jelena Popovic, Naveen K. Singhal, Elyse A. Watkins, Hemraj B. Dodiya, Ian Q. Weigle, Miranda A. Salvo, Abhirami Ramakrishnan, Zhangying Chen, James T. Watson, Aashutosh Shetti, Natalie Piehl, Xiaoqiong Zhang, Leah K. Cuddy, Katherine R. Sadleir, Steven J. Schwulst, Murali Prakriya, David Gate, Sangram S. Sisodia, Robert Vassar
Autosomal Dominant Optic Atrophy (ADOA), the most prevalent hereditary optic neuropathy, leads to retinal ganglion cell (RGC) degeneration and vision loss. ADOA is primarily caused by mutations in the OPA1 gene, which encodes a conserved GTPase important for mitochondrial inner membrane dynamics. To date, the disease mechanism remains unclear, and no therapies are available. We generated a mouse model carrying the pathogenic Opa1R290Q/+ allele that recapitulated key features of human ADOA, including mitochondrial defects, age-related RGC loss, optic nerve degeneration, and reduced RGC functions. We identified SARM1, a neurodegeneration switch, as a key driver of RGC degeneration in these mice. Sarm1 knockout nearly completely suppressed all the degeneration phenotypes without reversing mitochondrial fragmentation. Additionally, we showed that a portion of SARM1 localized within the mitochondrial intermembrane space (IMS). These findings indicated that SARM1 was activated downstream of mitochondrial dysfunction in ADOA, highlighting it as a promising therapeutic target.
Chen Ding, Papa S. Ndiaye, Sydney R. Campbell, Michelle Y. Fry, Jincheng Gong, Sophia R. Wienbar, Whitney Gibbs, Philippe Morquette, Luke H. Chao, Michael Tri H. Do, Thomas Schwarz
The nucleolus is a membraneless organelle and an excellent stress sensor. Any changes in its architecture or composition lead to nucleolar stress, resulting in cell cycle arrest and interruption of ribosomal activity, critical factors in aging and cancer. In this study, we identified and described the pivotal role of the RNA-binding protein (RBP) HNRNPK in ribosome and nucleolar dynamics. We developed an in vitro model of endogenous HNRNPK overexpression and an in vivo mouse model of ubiquitous HNRNPK overexpression. These models showed disruptions in translation and caused alterations in the nucleolar structure, resulting in p53-dependent nucleolar stress, cell cycle arrest, senescence, and bone marrow failure phenotype, similar to what is observed in patients with ribosomopathies. Together, our findings identify HNRNPK as a master regulator of ribosome biogenesis (RiBi) and nucleolar homeostasis through p53, providing a new perspective on the orchestration of nucleolar integrity, ribosome function and cellular senescence.
Pedro Aguilar-Garrido, María Velasco-Estévez, Miguel Ángel Navarro-Aguadero, Alvaro Otero-Sobrino, Marta Ibañez-Navarro, Miguel Ángel Marugal, María Hernández-Sánchez, Prerna Malaney, Ashley Rodriguez, Oscar Benitez, Xiaorui Zhang, Marisa J.L. Aitken, Alejandra Ortiz-Ruiz, Diego Megias, Manuel Pérez-Martínez, Gadea Mata, Jesús Gomez, Miguel Lafarga, Orlando Dominguez, Osvaldo Graña-Castro, Eduardo Caleiras, Pilar Ximenez-Embun, Marta Isasa, Paloma J. de Andrés, Sandra Rodriguez-Perales, Raul Torres-Ruiz, Enrique Revilla, Rosa María García-Martín, Daniel Azorín, Josune Zubicaray, Julian Sevilla, Oleksandra Sirozh, Vanesa Lafarga, Joaquín Martinez-Lopez, Sean M. Post, Miguel Gallardo
The complement system executes an evolutionarily ancient innate immune response with important roles in many human diseases, including a variety of conditions involving the kidney, autoimmune disorders, age-related macular degeneration, and more. This series of reviews, curated by Dr. Claudia Kemper, highlights the latest discoveries in complement biology and examines ongoing efforts to target complement therapeutically. From the relatively newly uncovered functions of intracellular complement (complosome) to the complexities involved in using animal models of complementopathies, these reviews convey the challenges of studying complement and developing complement-targeted therapeutics as well as call attention to recent findings that supply momentum to the field.
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