Insoo Kang

Yale University, New Haven, Connecticut, United States

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Publications (51)220.16 Total impact

  • Insoo Kang

    No preview · Article · Nov 2015 · Arthritis and Rheumatology
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    ABSTRACT: DNA methylation is an epigenetic mechanism that modulates gene expression in mammalian cells including T cells. Memory T cells are heterogeneous populations. Human effector memory (EM) CD8(+) T cells in peripheral blood contain two cell subsets with distinct traits that express low and high levels of the IL-7Rα. However, epigenetic mechanisms involved in defining such cellular traits are largely unknown. In this study, we use genome-wide DNA methylation and individual gene expression to show the possible role of DNA methylation in conferring distinct traits of chemotaxis and inflammatory responses in human IL-7Rα(low) and IL-7Rα(high) EM CD8(+) T cells. In particular, IL-7Rα(low) EM CD8(+) T cells had increased expression of CX3CR1 along with decreased DNA methylation in the CX3CR1 gene promoter compared with IL-7Rα(high) EM CD8(+) T cells. Altering the DNA methylation status of the CX3CR1 gene promoter changed its activity and gene expression. IL-7Rα(low) EM CD8(+) T cells had an increased migratory capacity to the CX3CR1 ligand fractalkine compared with IL-7Rα(high) EM CD8(+) T cells, suggesting an important biological outcome of the differential expression of CX3CR1. Moreover, IL-7Rα(low) EM CD8(+) T cells induced fractalkine expression on endothelial cells by producing IFN-γ and TNF-α, forming an autocrine amplification loop. Overall, our study shows the role of DNA methylation in generating unique cellular traits in human IL-7Rα(low) and IL-7Rα(high) EM CD8(+) T cells, including differential expression of CX3CR1, as well as potential biological implications of this differential expression. Copyright © 2015 by The American Association of Immunologists, Inc.
    Full-text · Article · Aug 2015 · The Journal of Immunology
  • Min Sun Shin · Insoo Kang
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    ABSTRACT: One of the most noticeable changes in T-cell immunity with aging is the expansion of memory CD8+ T cells, with a decline in naïve phenotype T cells that reflects both diminished thymopoiesis and the effects of chronic antigenic stimulation with age. Flow cytometry is a useful tool in evaluating immune cells including the phenotype characteristics of different T-cell subsets. Here, we show flow cytometric methods measuring the different subsets of human CD8+ T cells that change with aging.
    No preview · Article · Jan 2015
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    ABSTRACT: Rationale: Cytokine receptors can be markers defining different T cell subsets and considered as therapeutic targets. The association of IL-6 and IL-6 receptor alpha (IL-6Rα) with asthma was reported, suggesting their involvement in asthma. Objectives: To determine whether and how IL-6Rα defines a distinct effector memory (EM) CD8+ T cell population in health and disease. Methods: EM CD8+ T cells expressing IL-6Rα (IL-6Rαhigh) were identified in human peripheral blood and analyzed for function, gene and transcription factor expression. The relationship of these cells with asthma was determined using blood and sputum. Measurements and Main results: A unique population of IL-6Rαhigh EM CD8+ T cells was found in peripheral blood. These cells that potently proliferated, survived, and produced high levels of the Th2-type cytokines IL-5 and IL-13 had increased levels of GATA3 and decreased levels of T-bet and Blimp-1 in comparison to other EM CD8+ T cells. In fact, GATA3 was required for IL-6Rα expression. Asthmatic patients had an increased frequency of IL-6Rαhigh EM CD8+ T cells in peripheral blood compared to healthy controls. Also, IL-6Rαhigh EM CD8+ T cells exclusively produced IL-5 and IL-13 in response to asthma-associated respiratory syncytial virus and bacterial superantigens. Conclusions: Human IL-6Rαhigh EM CD8+ T cells is a unique cell subset that may serve as a reservoir for effector CD8+ T cells, particularly the ones producing Th2-type cytokines, and expand in asthma.
    Full-text · Article · Nov 2014 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: Rationale: Cytokine receptors can be markers defining different T cell subsets and considered as therapeutic targets. The association of IL-6 and IL-6 receptor alpha (IL-6Rα) with asthma was reported, suggesting their involvement in asthma. Objectives: To determine whether and how IL-6Rα defines a distinct effector memory (EM) CD8+ T cell population in health and disease. Methods: EM CD8+ T cells expressing IL-6Rα (IL-6Rαhigh) were identified in human peripheral blood and analyzed for function, gene and transcription factor expression. The relationship of these cells with asthma was determined using blood and sputum. Measurements and Main results: A unique population of IL-6Rαhigh EM CD8+ T cells was found in peripheral blood. These cells that potently proliferated, survived, and produced high levels of the Th2-type cytokines IL-5 and IL-13 had increased levels of GATA3 and decreased levels of T-bet and Blimp-1 in comparison to other EM CD8+ T cells. In fact, GATA3 was required for IL-6Rα expression. Asthmatic patients had an increased frequency of IL-6Rαhigh EM CD8+ T cells in peripheral blood compared to healthy controls. Also, IL-6Rαhigh EM CD8+ T cells exclusively produced IL-5 and IL-13 in response to asthma-associated respiratory syncytial virus and bacterial superantigens. Conclusions: Human IL-6Rαhigh EM CD8+ T cells is a unique cell subset that may serve as a reservoir for effector CD8+ T cells, particularly the ones producing Th2-type cytokines, and expand in asthma.
    No preview · Article · Nov 2014 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: Analysis of immune cell states is paramount to our understanding of the pathogenesis of a broad range of human diseases. Immunologists rely on fluorescence cytometry for cellular analysis, and while detection of 8 markers is now well established, the overlap of fluorescent signals limits efficiency. Mass cytometry or CyTOF (Cytometry by Time-Of-Flight) is a new technology for multiparameter single cell analysis that overcomes many limitations of fluorescence-based flow cytometry and can routinely detect as many as 40 markers per sample. This technology provides tremendous detail for cellular analysis of multiple cell populations simultaneously and is a powerful technique for translational investigations. Here we present reproducible detection of immune cell subsets starting with as few as 10,000 cells. Our study provides methods to employ CyTOF for small samples, which is especially relevant for investigation of limited patient biopsies in translational and clinical research.
    Full-text · Article · Nov 2014 · Journal of Immunological Methods
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    Jin-Young Choi · Sang Taek Kim · Insoo Kang · Joe Craft

    Preview · Article · Sep 2014 · Arthritis Research & Therapy
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    ABSTRACT: IL-15 is involved in regulating host defense and inflammation. Monocytes produce the biologically active cell surface IL-15 in response to IFN-γ. Although aging can alter the immune system, little is known about whether and how aging affects IFN-γ-mediated IL-15 production in human monocytes. We showed that monocytes of healthy older adults (age ≥ 65) had increased cell surface IL-15 expression in response to IFN-γ compared to those of healthy young adults (age ≤ 40). This finding stems in part from increased IFN-γ receptor (R)1/2 expression on monocytes in older adults, leading to enhanced STAT1 activation and interferon regulatory factor 1 synthesis with increased IL15 gene expression. Our study suggests that with aging the IFN-γ-mediated IL-15 production pathway in human monocytes is uncompromised, but rather augmented, and could be considered as a therapeutic target point to modulate host defense and inflammation in older adults.
    Preview · Article · May 2014 · Clinical Immunology

  • No preview · Poster · May 2013
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    ABSTRACT: Objective: Primary Sjögren's syndrome (SS) is an autoimmune disease associated with a high risk of developing non-Hodgkin's lymphoma. This study was undertaken to determine the nature of B cells driving lymphoproliferation in primary SS. Methods: B cell subsets and function were analyzed in peripheral blood from 66 adult patients with primary SS (including 14 patients with B cell lymphoproliferative disease [LPD]) and 30 healthy donors, using flow cytometry, calcium mobilization, and gene array analysis. The reactivity of recombinant antibodies isolated from single B cells from patients with primary SS and LPD was tested using an enzyme-linked immunosorbent assay. Results: We observed an expansion of an unusual CD21-/low B cell population that correlated with lymphoproliferation in patients with primary SS. A majority of CD21-/low B cells from patients with primary SS expressed autoreactive antibodies, which recognized nuclear and cytoplasmic structures. These B cells belonged to the memory compartment, since their Ig genes were mutated. They were unable to induce calcium flux, become activated, or proliferate in response to B cell receptor and/or CD40 triggering, suggesting that these autoreactive B cells may be anergic. However, CD21-/low B cells from patients with primary SS remained responsive to Toll-like receptor (TLR) stimulation. Molecules specifically expressed in CD21-/low B cells that are likely to induce their unresponsive stage were detected in gene array analyses. Conclusion: Patients with primary SS who display high frequencies of autoreactive and unresponsive CD21-/low B cells are susceptible to developing lymphoproliferation. These cells remain in peripheral blood controlled by functional anergy instead of being eliminated, and chronic antigenic stimulation through TLR stimulation may create a favorable environment for breaking tolerance and activating these cells.
    No preview · Article · Apr 2013 · Arthritis & Rheumatology
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    ABSTRACT: Alterations in T cell immunity occur with aging. Influenza causes significant morbidity and mortality in the elderly. We investigated the relationship of serum IgG responses with hemagglutinin inhibition (HI) antibody titers and the frequency of distinct T cell subsets in young and elderly people who received the inactivated influenza vaccine. Influenza vaccine-specific IgG responses correlated with the increase of HI antibody titers and the frequency of CD4(+) T cells producing IFN-γ and IL-17 in young, but not elderly, people. Also, only in young people, such IgG responses correlated with the frequency of memory T cells, especially central memory cells, CD45RA(-) effector memory CD8(+) T cells and IL-7 receptor alpha high effector memory CD8(+) T cells with potent survival and proliferative capacity. These findings suggest that aging alters the association of influenza-vaccine specific IgG responses with HI antibody titers, cytokine-producing capacity and proportions of memory T cells in humans.
    No preview · Article · Mar 2013 · Clinical Immunology
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    Full-text · Article · Feb 2013 · The Journal of allergy and clinical immunology
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    ABSTRACT: BACKGROUND: Chronic inflammation contributes to the development of pathological disorders including insulin resistance and atherosclerosis. Identification of anti-inflammatory natural products can prevent the inflammatory diseases. METHODS: Anti-inflammatory effects of blue-green algae (BGA), i.e., Nostoc commune var. Sphaeroides Kützing (NO) and Spirulina Platensis (SP), were compared in RAW 264.7 and mouse bone marrow-derived macrophages (BMM) as well as splenocytes from apolipoprotein E knockout (apoE(-/-)) mice fed BGA. RESULTS: When macrophages pretreated with 100 μg/ml NO lipid extract (NOE) or SP lipid extract (SPE) were activated by lipopolysaccharide (LPS), expression and secretion of pro-inflammatory cytokines, such as tumor necrosis factor α (TNFα), interleukin 1β (IL-1β), and IL-6, were significantly repressed. NOE and SPE also significantly repressed the expression of TNFα and IL-1β in BMM. LPS-induced secretion of IL-6 was lower in splenocytes from apoE(-/-) fed an atherogenic diet containing 5% NO or SP for 12weeks. In RAW 264.7 macrophages, NOE and SPE markedly decreased nuclear translocation of NF-κB. The degree of repression of pro-inflammatory gene expression by algal extracts was much stronger than that of SN50, an inhibitor of NF-κB nuclear translocation. Trichostatin A, a pan histone deacetylase inhibitor, increased basal expression of IL-1β and attenuated the repression of the gene expression by SPE. SPE significantly down-regulated mRNA abundance of 11 HDAC isoforms, consequently increasing acetylated histone 3 levels. CONCLUSION: NOE and SPE repress pro-inflammatory cytokine expression and secretion in macrophages and splenocytes via inhibition of NF-κB pathway. Histone acetylation state is likely involved in the inhibition. GENERAL SIGNIFICANCE: This study underscores natural products can exert anti-inflammatory effects by epigenetic modifications such as histone acetylation.
    No preview · Article · Jan 2013 · Biochimica et Biophysica Acta
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    ABSTRACT: The pathogenic hallmark of systemic lupus erythematosus is the autoimmune response against self nuclear Ags, including dsDNA. The increased expression of the proinflammatory cytokine IL-1β has been found in the cutaneous lesion and PBMCs from lupus patients, suggesting a potential involvement of this cytokine in the pathogenesis of lupus. IL-1β is produced primarily by innate immune cells such as monocytes and can promote a Th17 cell response, which is increased in lupus. IL-1β production requires cleaving pro-IL-β into IL-1β by the caspase-1-associated multiprotein complex called inflammasomes. In this study we show that self dsDNA induces IL-1β production from human monocytes dependent on serum or purified IgG containing anti-dsDNA Abs by activating the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Reactive oxygen species (ROS) and K(+) efflux were involved in this activation. Knocking down the NLRP3 or inhibiting caspase-1, ROS, and K(+) efflux decreased IL-1β production. Supernatants from monocytes treated with a combination of self dsDNA and anti-dsDNA Ab(+) serum promoted IL-17 production from CD4(+) T cells in an IL-1β-dependent manner. These findings provide new insights in lupus pathogenesis by demonstrating that self dsDNA together with its autoantibodies induces IL-1β production from human monocytes by activating the NLRP3 inflammasome through inducing ROS synthesis and K(+) efflux, leading to the increased Th17 cell response.
    Preview · Article · Jan 2013 · The Journal of Immunology
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    Insoo Kang
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    ABSTRACT: T cells are an essential cellular component of the immune system. When T cells encounter antigen and receive co-stimulatory signals, they become activated, proliferate and produce cytokines. Flow cytometry is a valuable research tool in analyzing T cell functions including proliferation, survival and cytotoxicity as well as cytokine production and cell signaling. This article has reviewed the utility of flow cytometry in evaluating T cell functions.
    Preview · Article · Jan 2013
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    ABSTRACT: We investigated whether healthy young (age⩽40) and elderly (age⩾65) people infected with cytomegalovirus (CMV) had similar levels of CD8(+) T cell cytokine production and proliferation in response to an immunodominant CMV pp65 peptide pool given the role of CD8(+) T cells in controlling viral infection and the association of CMV with immunosenescence. Plus, we determined the effects of aging and CMV-infectious status on plasma levels of IL-27, an innate immune cytokine with pro- and anti-inflammatory properties, as well as on its relationship to IFN-γ in that IL-27 can promote the production of IFN-γ. The results of our study show that young and elderly people had similar levels of CD8(+) T cell proliferation, and IFN-γ and TNF-α production in response to CMV pp65 peptides. Plasma levels of IL-27 were similar between the two groups although CMV-infected young and elderly people had a trend toward increased levels of IL-27. Regardless of aging and CMV-infectious status, plasma levels of IL-27 correlated highly with plasma levels of IFN-γ. These findings suggest the maintenance of CMV pp65-specific CD8(+) T cell proliferation and cytokine production with aging as well as the sustaining of circulatory IL-27 levels and its biological link to IFN-γ in young and elderly people irrespective of CMV infection.
    No preview · Article · Dec 2012 · Cytokine
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    ABSTRACT: Macrophage migration inhibitory factor (MIF) is involved in tumorigenesis by facilitating tumor proliferation and evasion of apoptosis; however, its role in tumor immunity is unclear. In this study, we investigated the effect of MIF on the progression of the syngenic, CT26 colon carcinoma and the generation of tumor regulatory T cells (Tregs). The results showed that the tumor growth rate was significantly lower in MIF knockout (MIF(-/-)) mice than in wild-type (MIF(+/+)) mice. Flow cytometric analysis of both spleen and tumor cells revealed that MIF(-/-) mice had significantly lower levels of tumor-associated CD4(+)Tregs than MIF(+/+) mice. The splenic cells of MIF(-/-) mice also showed a decrease in CD8(+)Tregs, which was accompanied by an increase in CD8-induced tumor cytotoxicity. Interestingly, the inducible Treg response in spleen cells to anti-CD3/CD28 plus IL-2 plus TGF-β was greater in MIF(-/-) mice than in MIF(+/+) mice. Spleen cells of MIF(-/-) mice, stimulated with anti-CD3/CD28, produced lower levels of IL-2, but not TGF-β, than those of MIF(+/+) mice, which was recovered by the addition of recombinant MIF. Conversely, a neutralizing anti-MIF Ab blocked anti-CD3-induced IL-2 production by splenocytes of MIF(+/+) mice and suppressed the inducible Treg generation. Moreover, the administration of IL-2 into tumor-bearing MIF(-/-) mice restored the generation of Tregs and tumor growth. Taken together, our data suggest that MIF promotes tumor growth by increasing Treg generation through the modulation of IL-2 production. Thus, anti-MIF treatment might be useful in enhancing the adaptive immune response to colon cancers.
    Full-text · Article · Sep 2012 · The Journal of Immunology
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    ABSTRACT: Human effector memory (EM) CD8(+) T cells include IL-7Rα(high) and IL-7Rα(low) cells with distinct cellular characteristics, including the expression of cytotoxic molecules. Both NK cells and the NK cell-associated molecule 2B4 that is expressed on CD8(+) T cells promote cytotoxicity. Here we analysed the expression of 2B4 on IL-7Rα(high) and IL-7Rα(low) EM CD8(+) T cells and its contribution to cytotoxicity. We also analysed the frequency of IL-7Rα(high) and IL-7Rα(low) EM CD8(+) T cells in patients with SLE or lupus and in healthy individuals given the potential role of cytotoxic CD8(+) T cells in the pathogenesis of lupus. We used flow cytometry to measure the expression of 2B4 on IL-7Rα(high) and IL-7Rα(low) EM CD8(+) T cells as well as the frequency of these cell populations in the peripheral blood of healthy individuals and patients with SLE. Also, 2B4-mediated cytotoxicity was quantitated in IL-7Rα(high) and IL-7Rα(low) EM CD8(+) T cells using target cells with CD48 antigen. We found that IL-7Rα(high) EM CD8(+) T cells had higher levels of 2B4 expression compared with IL-7Rα(low) EM CD8(+) T cells. Triggering 2B4 enhanced the cytotoxic function of IL-7Rα(low) EM CD8(+) T cells against target cells. We also noticed that patients with SLE had an increased frequency of IL-7Rα(low) EM CD8(+) T cells that correlated with disease manifestation. Our findings show that SLE patients have increased IL-7Rα(low) EM CD8(+) T cells, possibly contributing to tissue damage through 2B4-mediated cytotoxicity.
    No preview · Article · Jun 2012 · Rheumatology (Oxford, England)
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    ABSTRACT: FOXP3-positive regulatory T (Treg) cells are a unique subset of T cells with immune regulatory properties. Treg cells can be induced from non-Treg CD4(+) T cells (induced Treg [iTreg] cells) by TCR triggering, IL-2, and TGF-β or retinoic acid. 1,25-Dihyroxyvitamin D(3) [1,25(OH)(2)VD(3)] affects the functions of immune cells including T cells. 1,25(OH)(2)VD(3) binds the nuclear VD receptor (VDR) that binds target DNA sequences known as the VD response element (VDRE). Although 1,25(OH)(2)VD(3) can promote FOXP3 expression in CD4(+) T cells with TCR triggering and IL-2, it is unknown whether this effect of 1,25(OH)(2)VD(3) is mediated through direct binding of VDR to the FOXP3 gene without involving other molecules. Also, it is unclear whether FOXP3 expression in 1,25(OH)(2)VD(3)-induced Treg (VD-iTreg) cells is critical for the inhibitory function of these cells. In this study, we demonstrated the presence of VDREs in the intronic conserved noncoding sequence region +1714 to +2554 of the human FOXP3 gene and the enhancement of the FOXP3 promoter activity by such VDREs in response to 1,25(OH)(2)VD(3). Additionally, VD-iTreg cells suppressed the proliferation of target CD4(+) T cells and this activity was dependent on FOXP3 expression. These findings suggest that 1,25(OH)(2)VD(3) can affect human immune responses by regulating FOXP3 expression in CD4(+) T cells through direct VDR binding to the FOXP3 gene, which is essential for inhibitory function of VD-iTreg cells.
    Full-text · Article · Apr 2012 · The Journal of Immunology
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    ABSTRACT: The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is a caspase-1-containing cytosolic protein complex that is essential for processing and secretion of IL-1β. The U1-small nuclear ribonucleoprotein (U1-snRNP) that includes U1-small nuclear RNA is a highly conserved intranuclear molecular complex involved in splicing pre-mRNA. Abs against this self nuclear molecule are characteristically found in autoimmune diseases like systemic lupus erythematosus, suggesting a potential role of U1-snRNP in autoimmunity. Although endogenous DNA and microbial nucleic acids are known to activate the inflammasomes, it is unknown whether endogenous RNA-containing U1-snRNP could activate this molecular complex. In this study, we show that U1-snRNP activates the NLRP3 inflammasome in CD14(+) human monocytes dependently of anti-U1-snRNP Abs, leading to IL-1β production. Reactive oxygen species and K(+) efflux were responsible for this activation. Knocking down the NLRP3 or inhibiting caspase-1 or TLR7/8 pathway decreased IL-1β production from monocytes treated with U1-snRNP in the presence of anti-U1-snRNP Abs. Our findings indicate that endogenous RNA-containing U1-snRNP could be a signal that activates the NLRP3 inflammasome in autoimmune diseases like systemic lupus erythematosus where anti-U1-snRNP Abs are present.
    Preview · Article · Apr 2012 · The Journal of Immunology

Publication Stats

1k Citations
220.16 Total Impact Points

Institutions

  • 2000-2015
    • Yale University
      • • Department of Internal Medicine
      • • Section of Rheumatology
      New Haven, Connecticut, United States
    • Hallym University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 2003-2014
    • Yale-New Haven Hospital
      • Department of Pathology
      New Haven, Connecticut, United States