Hematopoietic stem cells (HSCs) maintain blood production.How often mouse HSCs divide and whether each HSC contributes simultaneously, sequentially, or repetitively to hematopoiesis remains to be determined.We track division of 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled HSC in vivo.We found that, in steady-state mice, bone marrow cells capable of reconstituting lifelong hematopoiesis are found within both fast-cycling (undergoing five or more divisions in 7 wk) and quiescent (undergoing zero divisions in 12-14 wk) lineage marker-negative c-Kit + Sca-1 + populations.The contribution of each population to hematopoiesis can fluctuate with time, and cells with extensive proliferative history are prone to return to quiescence.Furthermore, injection of the bacterial component lipopolysaccharide increased the proliferation and self-renewal capacity of HSCs.These findings suggest a model in which all HSCs undergo dynamic and demandadapted entry into and exit out of the cell cycle over time.This may facilitate a similar degree of turnover of the entire HSC pool at the end of life.

10.1083/jcb1924oia3

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Citations (9)

Distinct immunologic changes in vivo following combination versus individual PD-1 or CTLA-4 checkpoint blockade in human cancer

Journal for ImmunoTherapy of Cancer (2014)

Kavita M. Dhodapkar Rakesh Verma Mario Sznol Chandra Sekhar Boddupalli Scott Gettinger

Meeting abstracts Therapies targeting T cell immune checkpoints such as CTLA4 and PD1/PDL1 axis have shown considerable promise in the therapy of human cancer. Combination therapy with dual immune checkpoint blockade (ICB) was recently shown to be highly active in melanoma. While signaling via both

Immune checkpoint

CTLA-4

10.1186/2051-1426-2-s3-o7

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Citations (0)

Clonal Immunoglobulin against Lysolipids in the Origin of Myeloma

New England Journal of Medicine (2016)

Shiny Nair Andrew R. Branagan Jun Liu Chandra Sekhar Boddupalli Pramod K. Mistry

Summ a

Paraproteinemias

Gammopathy

Immunoglobulin M

10.1056/nejmoa1508808

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Citations (189)

Clinical and Serologic Responses After a Two-dose Series of High-dose Influenza Vaccine in Plasma Cell Disorders: A Prospective, Single-arm Trial

Clinical Lymphoma Myeloma & Leukemia (2017)

Andrew R. Branagan Eamon Duffy Randy A. Albrecht Dennis Cooper Stuart Seropian

Hemagglutination assay

10.1016/j.clml.2017.02.025

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Citations (43)

Association of lysolipids with Gaucher disease - associated and sporadic gammopathies

Molecular Genetics and Metabolism (2017)

Shiny Nair J. E. H. Sng Lin Zhang Andrew R. Branagan Jun Liu

Association (psychology)

10.1016/j.ymgme.2016.11.251

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Citations (0)

Neuroinflammation in neuronopathic Gaucher disease: Role of microglia and NK cells, biomarkers, and response to substrate reduction therapy

eLife (2022)

Chandra Sekhar Boddupalli Shiny Nair Glenn S. Belinsky Joseph H. Gans Erin Teeple

Background: Neuronopathic Gaucher disease (nGD) is a rare neurodegenerative disorder caused by biallelic mutations in GBA and buildup of glycosphingolipids in lysosomes. Neuronal injury and cell death are prominent pathological features; however, the role of GBA in individual cell types and involvement of microglia, blood-derived macrophages, and immune infiltrates in nGD pathophysiology remains enigmatic. Methods: Here, using single-cell resolution of mouse nGD brains, lipidomics, and newly generated biomarkers, we found induction of neuroinflammation pathways involving microglia, NK cells, astrocytes, and neurons. Results: Targeted rescue of Gba in microglia and neurons, respectively, in Gba -deficient, nGD mice reversed the buildup of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph), concomitant with amelioration of neuroinflammation, reduced serum neurofilament light chain (Nf-L), and improved survival. Serum GlcSph concentration was correlated with serum Nf-L and ApoE in nGD mouse models as well as in GD patients. Gba rescue in microglia/macrophage compartment prolonged survival, which was further enhanced upon treatment with brain-permeant inhibitor of glucosylceramide synthase, effects mediated via improved glycosphingolipid homeostasis, and reversal of neuroinflammation involving activation of microglia, brain macrophages, and NK cells. Conclusions: Together, our study delineates individual cellular effects of Gba deficiency in nGD brains, highlighting the central role of neuroinflammation driven by microglia activation. Brain-permeant small-molecule inhibitor of glucosylceramide synthase reduced the accumulation of bioactive glycosphingolipids, concomitant with amelioration of neuroinflammation involving microglia, NK cells, astrocytes, and neurons. Our findings advance nGD disease biology whilst identifying compelling biomarkers of nGD to improve patient management, enrich clinical trials, and illuminate therapeutic targets. Funding: Research grant from Sanofi; other support includes R01NS110354.

10.7554/elife.79830

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Citations (31)

Antigen-mediated regulation in monoclonal gammopathies and myeloma

JCI Insight (2018)

Shiny Nair Joel Sng Chandra Sekhar Boddupalli Anja Seckinger Marta Chesi

A role for antigen-driven stimulation has been proposed in the pathogenesis of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) based largely on the binding properties of monoclonal Ig. However, insights into antigen binding to clonal B cell receptors and in vivo responsiveness of the malignant clone to antigen-mediated stimulation are needed to understand the role of antigenic stimulation in tumor growth. Lysolipid-reactive clonal Ig were detected in Gaucher disease (GD) and some sporadic gammopathies. Here, we show that recombinant Ig (rIg) cloned from sort-purified single tumor cells from lipid-reactive sporadic and GD-associated gammopathy specifically bound lysolipids. Liposome sedimentation and binding assays confirmed specific interaction of lipid-reactive monoclonal Ig with lysolipids. The clonal nature of lysolipid-binding Ig was validated by protein sequencing. Gene expression profiling and cytogenetic analyses from 2 patient cohorts showed enrichment of nonhyperdiploid tumors in lipid-reactive patients. In vivo antigen-mediated stimulation led to an increase in clonal Ig and plasma cells (PCs) in GD gammopathy and also reactivated previously suppressed antigenically related nonclonal PCs. These data support a model wherein antigenic stimulation mediates an initial polyclonal phase, followed by evolution of monoclonal tumors enriched in nonhyperdiploid genomes, responsive to underlying antigen. Targeting underlying antigens may therefore prevent clinical MM.

Polyclonal antibodies

clone (Java method)

Gammopathy

10.1172/jci.insight.98259

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Citations (50)

Interlesional diversity of T cell receptors in melanoma with immune checkpoints enriched in tissue-resident memory T cells

JCI Insight (2016)

Chandra Sekhar Boddupalli Noffar Bar Krishna Kadaveru Michael Krauthammer Natapol Pornputtapong

Heterogeneity of tumor cells and their microenvironment can affect outcome in cancer. Blockade of immune checkpoints (ICPs) expressed only on a subset of immune cells leads to durable responses in advanced melanoma. Tissue-resident memory T (TRM) cells have recently emerged as a distinct subset of memory T cells in nonlymphoid tissues. Here, we show that functional properties and expression of ICPs within tumor-infiltrating lymphocytes (TILs) differ from those of blood T cells. TILs secrete less IL-2, IFN-γ, and TNF-α compared with circulating counterparts, and expression of VEGF correlated with reduced TIL infiltration. Within tumors, ICPs are particularly enriched within T cells with phenotype and genomic features of TRM cells and the CD16+ subset of myeloid cells. Concurrent T cell receptor (TCR) and tumor exome sequencing of individual metastases in the same patient revealed that interlesional diversity of TCRs exceeded differences in mutation/neoantigen load in tumor cells. These findings suggest that the TRM subset of TILs may be the major target of ICP blockade and illustrate interlesional diversity of tissue-resident TCRs within individual metastases, which did not equilibrate between metastases and may differentially affect the outcome of immune therapy at each site.

Immune checkpoint

Tumor-infiltrating lymphocytes

10.1172/jci.insight.88955

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Citations (136)