Small extracellular vesicles (SEVs) are functional messengers of certain cellular niches to permit non-contact cell communications. Whether niche-specific SEVs fulfill this role in cancer is unclear. Here, we used seven cell-type specific mouse Cre lines to conditionally knockout Vps33b in Cdh5+ or Tie2+ endothelial cells (ECs), Lepr+ bone marrow perivascular cells, Osx+ osteo-progenitor cells (OPCs), Pf4+ megakaryocytes and Tcf21+ spleen stromal cells. We then examined the effects of reduced SEV secretion on progression of MLL-AF9 induced acute myeloid leukemia (AML) as well as normal hematopoiesis. Blocking SEV secretion from ECs, but not perivascular cells, megakaryocytes or spleen stromal cells, markedly delayed the leukemia progression. Notably, reducing SEV production from ECs had no effect on normal hematopoiesis. Protein analysis showed that EC-derived SEVs contained a high level of ANGPTL2, which accelerated leukemia progression via binding to LILRB2 receptor. Moreover, ANGPTL2-SEVs released from ECs were governed by VPS33B. Importantly, ANGPTL2-SEVs were also required for primary human AML cell maintenance. These findings demonstrate a role of niche-specific SEVs in cancer development and suggest that targeting ANGPTL2-SEVs from ECs might be a potential strategy to interfere certain types of AML.
Dan Huang, Guohuan Sun, Xiaoxin Hao, Xiaoxiao He, Zhaofeng Zheng, Chiqi Chen, Zhuo Yu, Li Xie, Shihui Ma, Ligen Liu, Bo O. Zhou, Hui Cheng, Junke Zheng, Tao Cheng
Zeb1, a zinc finger E-box binding homeobox epithelial-mesenchymal (EMT) transcription factor, confers properties of ‘stemness’, such as self-renewal, in cancer. Yet little is known about the function of Zeb1 in adult stem cells. Here, we used the hematopoietic system, as a well-established paradigm of stem cell biology, to evaluate Zeb1 mediated regulation of adult stem cells. We employed a conditional genetic approach using the Mx1-Cre system to specifically knockout (KO) Zeb1 in adult hematopoietic stem cells (HSCs) and their downstream progeny. Acute genetic deletion of Zeb1 led to rapid onset thymic atrophy and apoptosis driven loss of thymocytes and T cells. A profound cell-autonomous self-renewal defect and multi-lineage differentiation block was observed in Zeb1 KO HSCs. Loss of Zeb1 in HSCs activated transcriptional programs of deregulated HSC maintenance and multi-lineage differentiation genes, and of cell polarity, consisting of cytoskeleton, lipid metabolism/lipid membrane and cell adhesion related genes. Notably, Epithelial cell adhesion molecule (EpCAM) expression was prodigiously upregulated in Zeb1 KO HSCs, which correlated with enhanced cell survival, diminished mitochondrial metabolism, ribosome biogenesis, and differentiation capacity and an activated transcriptomic signature associated with acute myeloid leukemia (AML) signaling. ZEB1 expression was downregulated in AML patients and Zeb1 KO in the malignant counterparts of HSCs - leukemic stem cells (LSCs) - accelerated MLL-AF9 and Meis1a/Hoxa9-driven AML progression, implicating Zeb1 as a tumor suppressor in AML LSCs. Thus, Zeb1 acts as a transcriptional regulator in hematopoiesis, critically co-ordinating HSC self-renewal, apoptotic and multi-lineage differentiation fates required to suppress leukemic potential in AML.
Alhomidi Almotiri, Hamed Ahmad A. Alzahrani, Juan Bautista Menendez-Gonzalez, Ali Abdelfattah, Badi Alotaibi, Lubaid Saleh, Adelle Greene, Mia R. F. Georgiou, Alex Gibbs, Amani Salem Alsayari, Sarab Taha, Leigh-Anne Thomas, Dhruv Shah, Sarah Edkins, Peter J. Giles, Marc P. Stemmler, Simone Brabletz, Thomas Brabletz, Ashleigh S. Boyd, Florian A. Siebzehnrubl, Neil P. Rodrigues
Microglia maintain homeostasis in the brain. However, with age, they become primed and respond more strongly to inflammatory stimuli. We show here that microglia from aged mice upregulated mammalian target of rapamycin (mTOR) complex 1 signaling regulating translation, as well as protein levels of inflammatory mediators. Genetic ablation of mTOR signaling showed a dual, yet contrasting effect on microglia priming: it caused an NF-kB-dependent upregulation of priming genes at mRNA level; however, mice displayed reduced cytokine protein levels, diminished microglia activation and milder sickness behavior. The effect on translation was dependent on reduced phosphorylation of 4EBP1, resulting in decreased binding of eIF4E to eIF4G. Similar changes were present in aged human microglia and in damage-associated microglia, indicating upregulation of mTOR-dependent translation is an essential step licensing microglia priming in aging and neurodegeneration.
Lily Keane, Ignazio Antignano, Sean-Patrick Riechers, Raphael Zollinger, Anaelle A. Dumas, Nina Offermann, Maria E. Bernis, Jenny Russ, Frederike J. Graelmann, Patrick N. McCormick, Julia Esser, Dario Tejera, Ai Nagano, Jun Wang, Claude Chelala, Yvonne Biederbick, Annett Halle, Paolo Salomoni, Michael Thomas Heneka, Melania Capasso
Available evidence suggests significant heterogeneity in the human immune response to SARS-CoV-2. In this Viewpoint, we examine the spectrum of SARS-CoV-2-associated clinical inflammatory syndromes identified in adult and pediatric populations to date. A better understanding of the immunopathologies and related clinical manifestations of these syndromes is necessary to improve their diagnosis and management.
Jill E. Weatherhead, Eva H. Clark, Tiphanie P. Vogel, Robert L. Atmar, Prathit A. Kulkarni
Neurofibromatosis type 1 (NF1) is a common tumor predisposition syndrome, caused by NF1 gene mutation, in which affected patients develop Schwann cell lineage peripheral nerve sheath tumors (neurofibromas). To investigate human neurofibroma pathogenesis, we differentiated a series of isogenic patient-specific NF1-mutant human induced-pluripotent stem cells (hiPSCs) into Schwannian lineage cells (SLCs). We found that while wild-type and heterozygous NF1-mutant hiPSC-SLCs did not form tumors following mouse sciatic nerve implantation, NF1-null SLCs formed bona fide neurofibromas with high levels of SOX10 expression. To confirm that SOX10+ SLCs contain the cells of origin for neurofibromas, both Nf1 alleles were inactivated in mouse Sox10+ cells, leading to classic nodular cutaneous and plexiform neurofibroma formation that completely recapitulate their human counterparts. Moreover, we discovered that NF1 loss impaired Schwann cell differentiation by inducing a persistent stem-like state to expand the pool of progenitors required to initiate tumor formation, indicating that in addition to regulating MAPK-mediated cell growth, NF1 loss also alters Schwann cell differentiation to promote neurofibroma development. Taken together, we established complementary humanized neurofibroma explant and first-in-kind mouse genetically engineered nodular cutaneous neurofibroma models that delineate neurofibroma pathogenesis amenable to future therapeutic target discovery and evaluation.
Juan Mo, Corina Anastasaki, Zhiguo Chen, Tracey Shipman, Jason B. Papke, Kevin Y. Yin, David H. Gutmann, Lu Q. Le
Emerging evidence indicates that early life events can increase the risk for developing chronic obstructive pulmonary disease (COPD). Using an inducible transgenic mouse model for NF-κB activation in the airway epithelium, we found that a brief period of inflammation during the saccular stage [postnatal day (PN)3 - PN5] but not alveolar stage (PN10 - PN12) of lung development disrupts elastic fiber assembly, resulting in permanent reduction in lung function and development of a COPD-like lung phenotype that progresses through 24 months of age. Neutrophil depletion prevented disruption of elastic fiber assembly and restored normal lung development. Mechanistic studies uncovered a role for neutrophil elastase (NE) in downregulating expression of critical elastic fiber assembly components, particularly fibulin-5 and elastin. Further, both purified human NE and NE-containing exosomes from tracheal aspirates of premature infants with lung inflammation down-regulated elastin and fibulin-5 expression by saccular stage mouse lung fibroblasts. Together, our studies define a critical developmental window for assembling the elastin scaffold in the distal lung, which is required to support lung structure and function throughout the lifespan. While neutrophils play a well-recognized role in COPD development in adults, neutrophilic inflammation may also contribute to early life predisposition to COPD.
John T. Benjamin, Erin Plosa, Jennifer Sucre, Riet van der Meer, Shivangi Dave, Sergey S. Gutor, David Nichols, Peter Gulleman, Christopher Jetter, Wei Han, Matthew K. Xin, Peter C. Dinella, Ashley Catanzarite, Seunghyi Kook, Kalsang Dolma, Charitharth V. Lal, Amit Gaggar, J. Edwin Blalock, Dawn C. Newcomb, Bradley W. Richmond, Jonathan A. Kropski, Lisa R. Young, Susan Guttentag, Timothy S. Blackwell
Ongoing observational clinical research has prioritized understanding the human immune response to the SARS-CoV-2 during the COVID-19 pandemic. Several recent studies suggest that immune dysregulation with early and prolonged adaptive immune system activation can result in cellular exhaustion. In this issue of the JCI, Files et al. compared cellular immune phenotypes during the first two months of COVID-19 in hospitalized and less severe, non-hospitalized patients. The authors utilized flow cytometry to analyze circulating peripheral blood mononuclear cells. Both patient-cohorts maintained B and T cell phenotypes consistent with activation and cellular exhaustion throughout the first two months of infection. Additionally, follow-up samples from the non-hospitalized patient cohort showed that activation markers and cellular exhaustion increased over time. These findings illustrate the persistent nature of the adaptive immune system changes that have been noted in COVID-19 and suggest longer-term effects that may shape the maintenance of immunity to SARS-CoV-2.
Philip A. Mudd, Kenneth E. Remy
Diabetes mellitus (DM) is a risk factor for cancer development. However, the role of DM induced hyperglycemic stress (HG) in the development of blood cancer is poorly understood, largely due to lack of appropriate animal models. Epidemiologic studies show that individuals with DM are more likely to possess higher rate of mutations in genes found in pre-leukemic stem and progenitor cells (pre-LHSC/Ps) including in the epigenetic regulator TET2. TET2-mutant pre-LHSC/Ps require additional hits to evolve into a full-blown leukemia and/or aggressive myeloproliferative neoplasm (MPN). Cell intrinsic mutations have been shown to cooperate with Tet2 to promote leukemic transformation. However, the role of extrinsic factors is poorly understood. Utilizing a novel mouse model bearing haploinsufficiency of Tet2, to mimic the human pre-LHSC/P condition and HG stress, in the form of an Ins2Akita/+ mutation, which induces HG and Type-1 DM, we show that the compound mutant mice develop a lethal form of MPN and/or acute myeloid leukemia (AML). RNAseq revealed that this is in part due to upregulation of pro-inflammatory pathways, thereby generating a feedforward loop, including the expression of an anti-apoptotic lncRNA Morrbid. Loss of Morrbid in the compound mutants rescues the lethality and mitigates the development of MPN/AML. Our results describe a novel mouse model for age-dependent AML/MPN and suggest that HG stress acts as an environmental driver for myeloid neoplasm, which could be effectively prevented by reducing the expression of inflammation-related lncRNA Morrbid.
Zhigang Cai, Xiaoyu Lu, Chi Zhang, Sai Nelanuthala, Fabiola Aguilera, Abigail Hadley, Baskar Ramdas, Fang Fang, Kenneth P. Nephew, Jonathan J. Kotzin, Adam Williams, Jorge Henao-Mejia, Laura S. Haneline, Reuben Kapur
Graft-versus-host disease (GVHD) causes failed reconstitution of donor plasmacytoid dendritic cells (pDCs) that are critical for immune protection and tolerance. We used both murine and human systems to uncover the mechanisms whereby GVHD induces donor pDC defects. GVHD depleted Flt3-expressing donor multipotent progenitors (MPPs) that sustained pDCs, leading to impaired generation of pDCs. MPP loss was associated with decreased amounts of MPP-producing hematopoietic stem cells (HSCs) and oxidative stress-induced death of proliferating MPPs. Additionally, alloreactive T cells produced GM-CSF to inhibit MPP expression of Tcf4, the transcription factor essential for pDC development, subverting MPP production of pDCs. GM-CSF did not affect the maturation of pDC precursors. Notably, enhanced recovery of donor pDCs upon adoptive transfer early after allogeneic HSC transplantation repressed GVHD and restored the de novo generation of donor pDCs in recipient mice. pDCs suppressed the proliferation and expansion of activated autologous T cells via a type-I IFN signaling-dependent mechanism. They also produced PD-L1 and LILRB4 to inhibit T cell production of IFN-. We thus demonstrate that GVHD impairs the reconstitution of tolerogenic donor pDCs by depleting DC progenitors rather than by preventing pDC maturation. MPPs are an important target to effectively bolster pDC reconstitution for controlling GVHD.
Yuanyuan Tian, Lijun Meng, Ying Wang, Bohan Li, Hongshuang Yu, Yan Zhou, Tien Bui, Alicia Li, Ciril Abraham, Yongping Zhang, Jian Wang, Chenchen Zhao, Shin Mineishi, Stefania Gallucci, David Porter, Elizabeth Hexner, Hong Zheng, Yanyun Zhang, Shaoyan Hu, Yi Zhang
Human coronaviruses (hCoVs) cause severe respiratory illness in the elderly. Age-related impairments in innate immunity and sub-optimal virus-specific T cell and antibody responses are believed to cause severe disease upon respiratory virus infections. This phenomenon has recently received increased attention, as elderly patients are at substantially elevated risk for severe COVID-19 disease and experience increased rates of mortality following SARS-CoV-2 infection compared to younger populations. However, the basis for age-related fatal pneumonia following pathogenic hCoVs is not well understood. In this review article, we provide an overview of our current understanding of hCoV-induced fatal pneumonia in the elderly. We describe host immune response to hCoV infections derived from studies of young and aged animal models, and discuss the potential role of age-associated increases in sterile inflammation (inflammaging) and virus-induced dysregulated inflammation in causing age-related severe disease. We also highlight the existing gaps in our knowledge about virus replication and host immune responses to hCoV infection in young and aged individuals..
Rudragouda Channappanavar, Stanley Perlman
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