In this issue, Dey et al. report that depletion of miR-29a/b1 cluster exacerbates the pathogenesis of acute pancreatitis in mice due to alterations in fibroinflammatory pathways. The cover image shows the pancreas of a miR-29a/b1–KO mouse with acute pancreatitis, with staining of infiltrating macrophages (brown).
Patients with acute leukemia who are unable to achieve complete remission prior to allogeneic hematopoietic stem cell transplantation (SCT) have dismal outcomes with relapse rates well in excess of 60%. Haplo-identical SCT (haplo-SCT) may allow enhanced graft-versus-leukemia (GVL) effects by virtue of HLA class I/II donor-host disparities but typically requires intensive immune-suppression with post-transplant cyclophosphamide (PT-Cy) to prevent lethal graft-versus-host disease (GVHD). Here we demonstrate in preclinical models that glucocorticoid administration from day -1 to +5 inhibits alloantigen presentation by professional recipient antigen presenting cells in the gastrointestinal tract and prevents donor T-cell priming and subsequent expansion therein. In contrast, direct glucocorticoid signaling of donor T-cells promotes chemokine and integrin signatures permissive of preferential circulation and migration into the bone marrow, promoting donor T-cell residency. This results in significant reductions in GVHD whilst promoting potent GVL effects (relapse in recipients receiving glucocorticoids, vehicle or PT-Cy was 12%, 56% and 100% respectively). Intriguingly, patients with acute myeloid leukemia not in remission that received unmanipulated haplo-SCT and peri-transplant glucocorticoids also had an unexpectedly low relapse rate at 1 year (32%: 95% CI, 18%-47%) with high overall survival at 3 years (58%: 95% CI, 38-74%). These data highlight a potentially simple and effective approach to prevent relapse in patients with otherwise incurable leukemia that could be studied in prospective randomized trials.
Takayuki Inoue, Motoko Koyama, Katsuji Kaida, Kazuhiro Ikegame, Kathleen S. Ensbey, Luke Samson, Shuichiro Takahashi, Ping Zhang, Simone A. Minnie, Satoshi Maruyama, Shinichi Ishii, Takashi Daimon, Takahiro Fukuda, Hirohisa Nakamae, Takahide Ara, Yumiko Maruyama, Ken Ishiyama, Tatsuo Ichinohe, Yoshiko Atsuta, Bruce R. Blazar, Scott N. Furlan, Hiroyasu Ogawa, Geoffrey R. Hill
Genetic variants in Granulin (GRN), which encodes the secreted glycoprotein Progranulin (PGRN), are associated with several neurodegenerative diseases including frontotemporal lobar degeneration, neuronal ceroid lipofuscinosis, and Alzheimer’s disease. These genetic alterations manifest in pathological changes due to a reduction of PGRN expression; therefore, identifying factors that can modulate PGRN levels in vivo would enhance our understanding of PGRN in neurodegeneration, and could reveal novel potential therapeutic targets. Here, we report that modulation of the endocytosis-lysosomal pathway via reduction of Nemo-like kinase (Nlk) in microglia, and not neurons, can alter total brain Pgrn levels in mice. We demonstrate that Nlk reduction promotes Pgrn degradation by enhancing its trafficking through endocytosis-lysosomal pathway, specifically in microglia. Furthermore, genetic interaction studies in mice showed that Nlk heterozygosity in Grn haploinsufficient mice further reduces Pgrn levels and induces neuropathological phenotypes associated with PGRN deficiency. Our results reveal a new mechanism for Pgrn level regulation in the brain through the active catabolism by microglia and provide insights into the pathophysiology of PGRN-associated diseases.
Tingting Dong, Leon Tejwani, Youngseob Jung, Hiroshi Kokubu, Kimberly Luttik, Terri M. Driessen, Janghoo Lim
Influenza A virus (IAV) and SARS-CoV-2 are pandemic viruses causing millions of deaths, yet their clinical manifestations are distinctly different. With the hypothesis that upper airway immune and epithelial cells responses are also distinct, we performed single-cell RNA-sequencing (scRNA-Seq) on nasal wash cells freshly collected from adults with either acute COVID-19 or influenza or from healthy controls. We focused on major cell types and subtypes in a subset of donor samples. Nasal wash cells are enriched for macrophages and neutrophils for both influenza and COVID-19 compared to healthy controls. Hillock-like epithelial cells, M2-like macrophages, and age-dependent B cells are enriched in COVID-19 samples. A global decrease in interferon (IFN)-associated transcripts in neutrophils, macrophages, and epithelial cells is apparent in COVID-19 compared to influenza. The innate immune response to SARS-CoV-2 appears to be maintained in macrophages, despite evidence for limited epithelial immune sensing. Cell-to-cell interaction analyses reveal a decrease in epithelial interactions in COVID-19 and highlight differences in macrophage-macrophage interactions for COVID-19 and influenza. Our study demonstrates that scRNA-Seq can define host and viral transcriptional activity at the site of infection and reveal distinct local epithelial and immune cell responses for COVID-19 and influenza that may contribute to their divergent disease courses.
Kevin M. Gao, Alan G. Derr, Zhiru Guo, Kerstin Nundel, Ann Marshak-Rothstein, Robert W. Finberg, Jennifer P. Wang
A diet high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) (HFM) induces gastrointestinal symptoms in patients with irritable bowel syndrome (IBS) and a diet low in FODMAPs (LFM) improves symptoms in up to 60% of IBS patients. However, the mechanism by which FODMAPs affect IBS symptoms is unclear. We showed that mice fed on an HFM diet have mast cell activation and colonic barrier loss. Using mast cell-deficient mice with/without mast cell reconstitution, we showed that HFM-mediated colonic barrier loss is dependent on TLR4-dependent mast cell activation. In in vitro studies, we demonstrated IBS fecal supernatant stimulates mast cell significantly more compared to fecal supernatant from healthy controls. This effect of IBS fecal supernatant on mast cell stimulation is ameliorated in absence of TLR4 receptor and after an LFM diet. Translating these findings into IBS patients, we found an LFM diet improves colonic barrier function and reduces mast cell activation while decreasing fecal LPS levels. Our findings indicate that a HFM diet causes mast cell activation via LPS which in turn leads to colonic barrier loss and an LFM diet reverses these pathophysiologic mucosal changes.
Prashant Singh, Gintautas Grabauskas, Shi-Yi Zhou, Jun Gao, Yawen Zhang, Chung Owyang
Sarcomas contain a subpopulation of tumor propagating cells (TPCs) with enhanced tumor-initiating and self-renewal properties. However, it is unclear whether the TPC phenotype in sarcomas is stable or a dynamic cell state that can derive from non-tumor propagating cells (non-TPCs). In this study, we utilized a mouse model of undifferentiated pleomorphic sarcoma (UPS) to trace the lineage relationship between sarcoma side population (SP) cells that are enriched for TPCs and non-side population (non-SP) cells. By co-transplanting SP and non-SP cells expressing different endogenous fluorescent reporters, we show that non-SP cells can give rise to SP cells with enhanced tumor propagating potential in-vivo. Lineage trajectory analysis using single-cell RNA sequencing from SP and non-SP cells supports the notion that non-SP cells can assume the SP cell phenotype de novo. To test the effect of eradicating SP cells on tumor growth and self-renewal, we generated mouse sarcomas in which the Diphtheria Toxin Receptor (DTR) is expressed in the SP cells and their progeny. Ablation of the SP population using diphtheria toxin (DT) did not impede tumor growth or self-renewal. Together, we show that sarcoma SP is a dynamic cell state and targeting TPCs alone is insufficient to eliminate tumor progression.
Yuning Jackie Tang, Vijitha Puviindran, Yu Xiang, Yasuhito Yahara, Hongyuan Zhang, Puviindran Nadesan, Yarui Diao, David G. Kirsch, Benjamin A. Alman
JCI This Month is a digest of the research, reviews, and other features published each month.