Joanna Halkias, MD
Assistant Professor
Pediatrics
School of Medicine
The Halkias lab studies the cellular and molecular signals that drive human immune development with a focus on understanding how early life host-microbe interactions influence adaptive immune responses to perinatal inflammatory disorders such as preterm birth. Early life is a critical time in immune development marked by rapid exposure to environmental antigens.
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Microbial colonization of mucosal tissues plays a key role in the development and education of the host immune system and influences the susceptibility to immune-mediated disease later in life. Infants born preterm are predisposed to prenatal immune activation and inflammation, critical risk factors underlying much of the pathophysiology in this vulnerable population. In utero infection is the most frequently identified cause of spontaneous preterm birth and fetal T cell activation is associated with severe neonatal disease, yet the signals that drive the activation, differentiation, and regulation of fetal adaptive immunity are not known. We utilize immune and microbial transcriptomics, high parameter flow and mass cytometry, and humanized mouse models to understand the cellular and molecular interactions that instruct human immune cells during this critical window of development.
Education & Training
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- Diversity, Equity, and Inclusion Champion Training University of California 2019
- Postdoc Immunology University of California, Berkeley 2013
- Fellowship Neonatal-Perinatal Medicine Children’s Hospital Los Angeles/University of Southern California 2007
- Residency Pediatric Children’s Hospital Los Angeles 2004
- MD Medicine Albert Einstein College of Medicine 2001
- BA Biology University of Pennsylvania 1995
Interests
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- preterm birth
- host-microbe interactions
- prenatal immune activation
- human immune development
Grants and Projects
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- Harnessing immune regulatory mechanisms to target the fetal inflammatory response in preterm birth, Burroughs Wellcome Fund, 2019-2023
- Intrauterine sex steroids and human fetal T cell development, NIH, 2017-2022
- Intrauterine sex steroids and fetal T cell development., NIH/NIAID, 2017-2022
Publications (12)
Top publication keywords:
Cell MovementThymus GlandThymocytesImmune ToleranceImmune SystemLymphoid TissueNK Cell Lectin-Like Receptor Subfamily BReceptors, CCR7FetusMucous MembraneT-LymphocytesAdaptive ImmunityCD4-Positive T-LymphocytesIntestinesLymphopoiesis
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Opposing chemokine gradients control human thymocyte migration in situ.
The Journal of clinical investigation 2013 Halkias J, Melichar HJ, Taylor KT, Ross JO, Yen B, Cooper SB, Winoto A, Robey EA -
Homeostatic cytokines reciprocally modulate the emergence of prenatal effector PLZF+CD4+ T cells in humans.
JCI insight 2023 Locher V, Park S, Bunis DG, Makredes S, Mayer M, Burt TD, Fragiadakis GK, Halkias J -
Heritable vaginal bacteria influence immune tolerance and relate to early-life markers of allergic sensitization in infancy.
Cell reports. Medicine 2022 McCauley KE, Rackaityte E, LaMere B, Fadrosh DW, Fujimura KE, Panzer AR, Lin DL, Lynch KV, Halkias J, Mendoza VF, Burt TD, Bendixsen C, Barnes K, Kim H, Jones K, Ownby DR, Johnson CC, Seroogy CM, Gern… -
Corroborating evidence refutes batch effect as explanation for fetal bacteria.
Microbiome 2021 Rackaityte E, Halkias J, Fukui EM, Mendoza VF, Hayzelden C, Crawford ED, Fujimura KE, Burt TD, Lynch SV -
Mechanisms of Fetal T Cell Tolerance and Immune Regulation.
Frontiers in immunology 2020 Rackaityte E, Halkias J
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Viable bacterial colonization is highly limited in the human intestine in utero.
Nature medicine 2020 Rackaityte E, Halkias J, Fukui EM, Mendoza VF, Hayzelden C, Crawford ED, Fujimura KE, Burt TD, Lynch SV -
CD161 contributes to prenatal immune suppression of IFNγ-producing PLZF+ T cells.
The Journal of clinical investigation 2019 Halkias J, Rackaityte E, Hillman SL, Aran D, Mendoza VF, Marshall LR, MacKenzie TC, Burt TD -
Studying T Cell Development in Thymic Slices.
Methods in molecular biology (Clifton, N.J.) 2016 Ross JO, Melichar HJ, Halkias J, Robey EA -
Conserved and divergent aspects of human T-cell development and migration in humanized mice.
Immunology and cell biology 2015 Halkias J, Yen B, Taylor KT, Reinhartz O, Winoto A, Robey EA, Melichar HJ -
Tracking migration during human T cell development.
Cellular and molecular life sciences : CMLS 2014 Halkias J, Melichar HJ, Taylor KT, Robey EA -
Motile invaded neutrophils in the small intestine of Toxoplasma gondii-infected mice reveal a potential mechanism for parasite spread.
Proceedings of the National Academy of Sciences of the United States of America 2013 Coombes JL, Charsar BA, Han SJ, Halkias J, Chan SW, Koshy AA, Striepen B, Robey EA -
T cells in cryptopatch aggregates share TCR gamma variable region junctional sequences with gamma delta T cells in the small intestinal epithelium of mice.
Journal of immunology (Baltimore, Md. : 1950) 2006 Podd BS, Thoits J, Whitley N, Cheng HY, Kudla KL, Taniguchi H, Halkias J, Goth K, Camerini V