Excessive expression of miR-27 impairs Treg-mediated immunological tolerance

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Abstract

MicroRNAs (miRs) are tightly regulated in the immune system, and aberrant expression of miRs often results in hematopoietic malignancies and autoimmune diseases. Previously, it was suggested that elevated levels of miR-27 in T cells isolated from patients with multiple sclerosis facilitate disease progression by inhibiting Th2 immunity and promoting pathogenic Th1 responses. Here we have demonstrated that, although mice with T cell–specific overexpression of miR-27 harbor dysregulated Th1 responses and develop autoimmune pathology, these disease phenotypes are not driven by miR-27 in effector T cells in a cell-autonomous manner. Rather, dysregulation of Th1 responses and autoimmunity resulted from a perturbed Treg compartment. Excessive miR-27 expression in murine T cells severely impaired Treg differentiation. Moreover, Tregs with exaggerated miR-27–mediated gene regulation exhibited diminished homeostasis and suppressor function in vivo. Mechanistically, we determined that miR-27 represses several known as well as previously uncharacterized targets that play critical roles in controlling multiple aspects of Treg biology. Collectively, our data show that miR-27 functions as a key regulator in Treg development and function and suggest that proper regulation of miR-27 is pivotal to safeguarding Treg-mediated immunological tolerance.

Authors

Leilani O. Cruz, Somaye Sadat Hashemifar, Cheng-Jang Wu, Sunglim Cho, Duc T. Nguyen, Ling-Li Lin, Aly Azeem Khan, Li-Fan Lu

Targeting type I interferon–mediated activation restores immune function in chronic HIV infection

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Abstract

Chronic immune activation, immunosuppression, and T cell exhaustion are hallmarks of HIV infection, yet the mechanisms driving these processes are unclear. Chronic activation can be a driving force in immune exhaustion, and type I interferons (IFN-I) are emerging as critical components underlying ongoing activation in HIV infection. Here, we have tested the effect of blocking IFN-I signaling on T cell responses and virus replication in a murine model of chronic HIV infection. Using HIV-infected humanized mice, we demonstrated that in vivo blockade of IFN-I signaling during chronic HIV infection diminished HIV-driven immune activation, decreased T cell exhaustion marker expression, restored HIV-specific CD8 T cell function, and led to decreased viral replication. Antiretroviral therapy (ART) in combination with IFN-I blockade accelerated viral suppression, further decreased viral loads, and reduced the persistently infected HIV reservoir compared with ART treatment alone. Our data suggest that blocking IFN-I signaling in conjunction with ART treatment can restore immune function and may reduce viral reservoirs during chronic HIV infection, providing validation for IFN-I blockade as a potential therapy for HIV infection.

Authors

Anjie Zhen, Valerie Rezek, Cindy Youn, Brianna Lam, Nelson Chang, Jonathan Rick, Mayra Carrillo, Heather Martin, Saro Kasparian, Philip Syed, Nicholas Rice, David G. Brooks, Scott G. Kitchen

Biallelic mutations in IRF8 impair human NK cell maturation and function

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Abstract

Human NK cell deficiencies are rare yet result in severe and often fatal disease, particularly as a result of viral susceptibility. NK cells develop from hematopoietic stem cells, and few monogenic errors that specifically interrupt NK cell development have been reported. Here we have described biallelic mutations in IRF8, which encodes an interferon regulatory factor, as a cause of familial NK cell deficiency that results in fatal and severe viral disease. Compound heterozygous or homozygous mutations in IRF8 in 3 unrelated families resulted in a paucity of mature CD56^dim NK cells and an increase in the frequency of the immature CD56^bright NK cells, and this impairment in terminal maturation was also observed in Irf8^–/–, but not Irf8^+/–, mice. We then determined that impaired maturation was NK cell intrinsic, and gene expression analysis of human NK cell developmental subsets showed that multiple genes were dysregulated by IRF8 mutation. The phenotype was accompanied by deficient NK cell function and was stable over time. Together, these data indicate that human NK cells require IRF8 for development and functional maturation and that dysregulation of this function results in severe human disease, thereby emphasizing a critical role for NK cells in human antiviral defense.

Authors

Emily M. Mace, Venetia Bigley, Justin T. Gunesch, Ivan K. Chinn, Laura S. Angelo, Matthew A. Care, Sheetal Maisuria, Michael D. Keller, Sumihito Togi, Levi B. Watkin, David F. LaRosa, Shalini N. Jhangiani, Donna M. Muzny, Asbjørg Stray-Pedersen, Zeynep Coban Akdemir, Jansen B. Smith, Mayra Hernández-Sanabria, Duy T. Le, Graham D. Hogg, Tram N. Cao, Aharon G. Freud, Eva P. Szymanski, Sinisa Savic, Matthew Collin, Andrew J. Cant, Richard A. Gibbs, Steven M. Holland, Michael A. Caligiuri, Keiko Ozato, Silke Paust, Gina M. Doody, James R. Lupski, Jordan S. Orange

MHC class I–associated peptides derive from selective regions of the human genome

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Abstract

MHC class I–associated peptides (MAPs) define the immune self for CD8⁺ T lymphocytes and are key targets of cancer immunosurveillance. Here, the goals of our work were to determine whether the entire set of protein-coding genes could generate MAPs and whether specific features influence the ability of discrete genes to generate MAPs. Using proteogenomics, we have identified 25,270 MAPs isolated from the B lymphocytes of 18 individuals who collectively expressed 27 high-frequency HLA-A,B allotypes. The entire MAP repertoire presented by these 27 allotypes covered only 10% of the exomic sequences expressed in B lymphocytes. Indeed, 41% of expressed protein-coding genes generated no MAPs, while 59% of genes generated up to 64 MAPs, often derived from adjacent regions and presented by different allotypes. We next identified several features of transcripts and proteins associated with efficient MAP production. From these data, we built a logistic regression model that predicts with good accuracy whether a gene generates MAPs. Our results show preferential selection of MAPs from a limited repertoire of proteins with distinctive features. The notion that the MHC class I immunopeptidome presents only a small fraction of the protein-coding genome for monitoring by the immune system has profound implications in autoimmunity and cancer immunology.

Authors

Hillary Pearson, Tariq Daouda, Diana Paola Granados, Chantal Durette, Eric Bonneil, Mathieu Courcelles, Anja Rodenbrock, Jean-Philippe Laverdure, Caroline Côté, Sylvie Mader, Sébastien Lemieux, Pierre Thibault, Claude Perreault

Obesity accelerates T cell senescence in murine visceral adipose tissue

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Abstract

Chronic inflammation in visceral adipose tissue (VAT) precipitates the development of cardiometabolic disorders. Although changes in T cell function associated with visceral obesity are thought to affect chronic VAT inflammation, the specific features of these changes remain elusive. Here, we have determined that a high-fat diet (HFD) caused a preferential increase and accumulation of CD44^hiCD62L^loCD4⁺ T cells that constitutively express PD-1 and CD153 in a B cell–dependent manner in VAT. These cells possessed characteristics of cellular senescence and showed a strong activation of Spp1 (encoding osteopontin [OPN]) in VAT. Upon T cell receptor stimulation, these T cells also produced large amounts of OPN in a PD-1–resistant manner in vitro. The features of CD153⁺PD-1⁺CD44^hiCD4⁺ T cells were highly reminiscent of senescence-associated CD4⁺ T cells that normally increase with age. Adoptive transfer of CD153⁺PD-1⁺CD44^hiCD4⁺ T cells from HFD-fed WT, but not Spp1-deficient, mice into the VAT of lean mice fed a normal diet recapitulated the essential features of VAT inflammation and insulin resistance. Our results demonstrate that a distinct CD153⁺PD-1⁺CD44^hiCD4⁺ T cell population that accumulates in the VAT of HFD-fed obese mice causes VAT inflammation by producing large amounts of OPN. This finding suggests a link between visceral adiposity and immune aging.

Authors

Kohsuke Shirakawa, Xiaoxiang Yan, Ken Shinmura, Jin Endo, Masaharu Kataoka, Yoshinori Katsumata, Tsunehisa Yamamoto, Atsushi Anzai, Sarasa Isobe, Naohiro Yoshida, Hiroshi Itoh, Ichiro Manabe, Miho Sekai, Yoko Hamazaki, Keiichi Fukuda, Nagahiro Minato, Motoaki Sano

The transcription factor NR4A3 controls CD103⁺ dendritic cell migration

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Abstract

The transcription factor NR4A3 (also known as NOR-1) is a member of the Nr4a family of nuclear receptors and is expressed in myeloid and lymphoid cells. Here, we have shown that Nr4a3 is essential for the migration of CD103⁺ dendritic cells (DCs) to lymph nodes (LNs). Nr4a3-deficient mice had very few CD103⁺ migratory DCs (mDCs) present in LNs, and mixed-chimera studies revealed that this migratory defect was cell intrinsic. We further found that CD103⁺ DCs from Nr4a3-deficient mice displayed a marked loss of surface expression of the chemokine CCR7. This defect in CCR7 expression was confined to CD103⁺ DCs, as CCR7 expression on T lymphocytes was unaffected. Moreover, CCR7 was not induced on CD103⁺ DCs from Nr4a3-deficient mice in response to either administration of the TLR7 agonist R848 or infection with Citrobacter rodentium in vivo. The transcription factor FOXO1 has been shown to regulate CCR7 expression. We found that FOXO1 protein was reduced in Nr4a3-deficient DCs through an AKT-dependent mechanism. Further, we found a requirement for NR4A3 in the maintenance of homeostatic mitochondrial function in CD103⁺ DCs, although this is likely independent of the NR4A3/FOXO1/CCR7 axis in the regulation of DC migration. Thus, NR4A3 plays an important role in the regulation of CD103⁺ mDCs by regulating CCR7-dependent cell migration.

Authors

Kiwon Park, Zbigniew Mikulski, Goo-Young Seo, Aleksander Y. Andreyev, Paola Marcovecchio, Amy Blatchley, Mitchell Kronenberg, Catherine C. Hedrick

Guanine nucleotide exchange factor RABGEF1 regulates keratinocyte-intrinsic signaling to maintain skin homeostasis

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Abstract

Epidermal keratinocytes form a structural and immune barrier that is essential for skin homeostasis. However, the mechanisms that regulate epidermal barrier function are incompletely understood. Here we have found that keratinocyte-specific deletion of the gene encoding RAB guanine nucleotide exchange factor 1 (RABGEF1, also known as RABEX-5) severely impairs epidermal barrier function in mice and induces an allergic cutaneous and systemic phenotype. RABGEF1-deficient keratinocytes exhibited aberrant activation of the intrinsic IL-1R/MYD88/NF-κB signaling pathway and MYD88-dependent abnormalities in expression of structural proteins that contribute to skin barrier function. Moreover, ablation of MYD88 signaling in RABGEF1-deficient keratinocytes or deletion of Il1r1 restored skin homeostasis and prevented development of skin inflammation. We further demonstrated that epidermal RABGEF1 expression is reduced in skin lesions of humans diagnosed with either atopic dermatitis or allergic contact dermatitis as well as in an inducible mouse model of allergic dermatitis. Our findings reveal a key role for RABGEF1 in dampening keratinocyte-intrinsic MYD88 signaling and sustaining epidermal barrier function in mice, and suggest that dysregulation of RABGEF1 expression may contribute to epidermal barrier dysfunction in allergic skin disorders in mice and humans. Thus, RABGEF1-mediated regulation of IL-1R/MYD88 signaling might represent a potential therapeutic target.

Authors

Thomas Marichal, Nicolas Gaudenzio, Sophie El Abbas, Riccardo Sibilano, Oliwia Zurek, Philipp Starkl, Laurent L. Reber, Dimitri Pirottin, Jinah Kim, Pierre Chambon, Axel Roers, Nadine Antoine, Yuko Kawakami, Toshiaki Kawakami, Fabrice Bureau, See-Ying Tam, Mindy Tsai, Stephen J. Galli

Antitumor adaptive immunity remains intact following inhibition of autophagy and antimalarial treatment

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Abstract

The rising success of cancer immunotherapy has produced immense interest in defining the clinical contexts that may benefit from this therapeutic approach. To this end, there is a need to ascertain how the therapeutic modulation of intrinsic cancer cell programs influences the anticancer immune response. For example, the role of autophagy as a tumor cell survival and metabolic fitness pathway is being therapeutically targeted in ongoing clinical trials that combine cancer therapies with antimalarial drugs for the treatment of a broad spectrum of cancers, many of which will likely benefit from immunotherapy. However, our current understanding of the interplay between autophagy and the immune response remains incomplete. Here, we have evaluated how autophagy inhibition impacts the antitumor immune response in immune-competent mouse models of melanoma and mammary cancer. We observed equivalent levels of T cell infiltration and function within autophagy-competent and -deficient tumors, even upon treatment with the anthracycline chemotherapeutic doxorubicin. Similarly, we found equivalent T cell responses upon systemic treatment of tumor-bearing mice with antimalarial drugs. Our findings demonstrate that antitumor adaptive immunity is not adversely impaired by autophagy inhibition in these models, allowing for the future possibility of combining autophagy inhibitors with immunotherapy in certain clinical contexts.

Authors

Hanna Starobinets, Jordan Ye, Miranda Broz, Kevin Barry, Juliet Goldsmith, Timothy Marsh, Fanya Rostker, Matthew Krummel, Jayanta Debnath

IL-33 regulates the IgA-microbiota axis to restrain IL-1α–dependent colitis and tumorigenesis

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Abstract

Inflammatory bowel diseases (IBD) affect over 5 million individuals in the industrialized world, with an increasing incidence rate worldwide. IBD also predisposes affected individuals to development of colorectal cancer, which is a leading cause of cancer-related deaths in adults. Mutations in genes encoding molecules in the IL-33 signaling pathway are associated with colitis and colitis-associated cancer (CAC), but how IL-33 modulates gut homeostasis is unclear. Here, we have shown that Il33-deficient mice are highly susceptible to colitis and CAC. Mechanistically, we observed that IL-33 promoted IgA production from B cells, which is important for maintaining microbial homeostasis in the intestine. Il33-deficient mice developed a dysbiotic microbiota that was characterized by increased levels of mucolytic and colitogenic bacteria. In response to chemically induced colitis, this microbial landscape promoted the release of IL-1α, which acted as a critical driver of colitis and CAC. Consequently, reconstitution of symbiotic microbiota or IL-1α ablation markedly ameliorated colitis susceptibility in Il33-deficient animals. Our results demonstrate that IL-33 promotes IgA production to maintain gut microbial homoeostasis and restrain IL-1α–dependent colitis and CAC. This study therefore highlights modulation of IL-33, IgA, IL-1α, and the microbiota as a potential therapeutic approach in the treatment of IBD and CAC.

Authors

Ankit Malik, Deepika Sharma, Qifan Zhu, Rajendra Karki, Clifford S. Guy, Peter Vogel, Thirumala-Devi Kanneganti

MicroRNA-29b mediates altered innate immune development in acute leukemia

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Abstract

Natural killer (NK) cells can have potent antileukemic activity following haplo-mismatched, T cell–depleted stem cell transplantations for the treatment of acute myeloid leukemia (AML), but they are not successful in eradicating de novo AML. Here, we have used a mouse model of de novo AML to elucidate the mechanisms by which AML evades NK cell surveillance. NK cells in leukemic mice displayed a marked reduction in the cytolytic granules perforin and granzyme B. Further, as AML progressed, we noted the selective loss of an immature subset of NK cells in leukemic mice and in AML patients. This absence was not due to elimination by cell death or selective reduction in proliferation, but rather to the result of a block in NK cell differentiation. Indeed, NK cells from leukemic mice and humans with AML showed lower levels of TBET and EOMES, transcription factors that are critical for terminal NK cell differentiation. Further, the microRNA miR-29b, a regulator of T-bet and EOMES, was elevated in leukemic NK cells. Finally, deletion of miR-29b in NK cells reversed the depletion of this NK cell subset in leukemic mice. These results indicate that leukemic evasion of NK cell surveillance occurs through miR-mediated dysregulation of lymphocyte development, representing an additional mechanism of immune escape in cancer.

Authors

Bethany L. Mundy-Bosse, Steven D. Scoville, Li Chen, Kathleen McConnell, Hsiaoyin C. Mao, Elshafa H. Ahmed, Nicholas Zorko, Sophia Harvey, Jordan Cole, Xiaoli Zhang, Stefan Costinean, Carlo M. Croce, Karilyn Larkin, John C. Byrd, Sumithira Vasu, William Blum, Jianhua Yu, Aharon G. Freud, Michael A. Caligiuri