Biology subjects

Klicznik, M. M.

Publications and source records attributed to Klicznik, M. M..

4 recordsLinked to original sources

bioRxiv2020

Transcriptomic profiling of human effector and regulatory T cell subsets identifies predictive population signatures

After activation, CD4+ T helper (Th) cells differentiate into functionally specialized populations that coordinate distinct immune responses and protect against different types of pathogens. In humans, these effector and memory Th cell subsets can be readily identified in peripheral blood based on their differential expression of chemokine receptors that govern their homeostatic and inflammatory trafficking. Foxp3+ regulatory T (Treg) cells can also be divided into subsets that phenotypically mirror each of these effector populations, and share expression of key transcription factors and effector cytokines. In this study, we performed comprehensive transcriptional profiling of 11 phenotypically distinct Th and Treg cell subsets sorted from peripheral blood of healthy individuals. Despite their shared phenotypes, we found that mirror Th and Treg subsets were transcriptionally dissimilar, and that Treg cell populations showed limited transcriptional diversity compared to Th cells. We identified core transcriptional signatures shared across all Th and Treg cell populations, and unique signatures that define each of the Th or Treg populations. Finally, we applied these signatures to bulk Th and Treg RNA-seq data and found enrichment of specific Th and Treg cell populations in different human tissues. These results further define the molecular basis for the functional specialization and differentiation of Th and Treg cell populations, and provide a new resource for examining Th and Treg specialization in RNA-seq data.

immunology↗

bioRxiv2018

Circulating CD4+ memory T cells give rise to a CD69+ resident memory T cell population in non-inflamed human skin

The blood of human adults contains a pool of circulating CD4+ memory T cells and normal human skin contains a CD4+CD69+ memory T cell population that produce IL17 in response to Candida albicans. Here we studied the generation of CD4+CD69+ memory T cells in human skin from a pool of circulating CD4+ memory T cells.\n\nUsing adoptive transfer of human PBMC into a skin-humanized mouse model we discovered the generation of CD4+CD69+ resident memory T cells in human skin in absence of infection or inflammation. These CD4+CD69+ resident memory T cells were activated and displayed heightened effector function in response to Candida albicans. These studies demonstrate that a CD4+CD69+ T cell population can be established in human skin from a pool of circulating CD4+ memory T cells in absence of infection/inflammation. The described process might be a novel way to spread antigen-specific immunity at large barrier sites even in absence of infection or inflammation.

immunology↗

bioRxiv2018

A novel humanized mouse model to study antigen-specific cutaneous T cell responses in vivo

Human skin contains a population of memory T cells that support tissue homeostasis and provide protective immunity. The study of human memory T cells is often restricted to in vitro studies and to human PBMC serving as primary cell source. Because the tisse environment impacts the phenotype and function of memory T cells, it is crucial to study these cells within their tissue. Here we utilized immunodeficient NOD-scid IL2r{gamma}null (NSG) mice that carried in vivo-generated engineered human skin (ES). ES were generated from human keratinocytes and fibroblasts and is initially devoid of skin-resident immune cells. Upon adoptive transfer of human PBMC this reductionist system allowed to study human T cell recruitment from a circulating pool of T cells into non-inflamed human skin in vivo. Circulating human memory T cells preferentially infiltrated ES and showed diverse functional profiles of T cells found in fresh human skin. The chemokine and cytokine microenvironment of ES closely resembled that of non-inflamed human skin. Upon entering the ES T cells assumed a resident memory T cell-like phenotype in the absence of infection, and a proportion of these cutaneous T cells can be locally activated upon injection of monocyte derived dendritic cells (moDCs) that presented Candida albicans. Interestingly, we found that CD69+ memory T cells produced higher levels of effector cytokines in response to Candida albicans, compared to CD69- T cells. Overall, this model has broad utility in many areas of human skin immunology research, including the study of immune-mediated skin diseases.

immunology↗

bioRxiv2018

Continual exit of human cutaneous resident memory CD4 T cells that seed distant skin sites

Tissue-resident memory T cells (TRM) persist locally in non-lymphoid tissues where they provide front-line defense against recurring insults. TRM at barrier surfaces express the markers CD103 and/or CD69 which function to retain them in epithelial tissues. In humans, neither the long-term migratory behavior of TRM nor their ability to re-enter the circulation and potentially migrate to distant tissue sites have been investigated. Using tissue explant cultures, we found that CD4+CD69+CD103+ TRM in human skin can downregulate CD69 and exit the tissue. Additionally, we identified a skin-tropic CD4+CD69-CD103+ population in human lymph and blood that is transcriptionally, functionally and clonally related to the CD4+CD69+CD103+ TRM population in the skin. Using a skin xenograft model, we confirmed that a fraction of the human cutaneous CD4+CD103+ TRM population can re-enter circulation, and migrate to secondary human skin sites where they re-assume a TRM phenotype. Thus, our data challenge current concepts regarding the strict tissue compartmentalization of CD4+ T cell memory in humans. One Sentence SummaryHuman CD4+CD103+ cutaneous resident memory T cells are found in the circulation of healthy subjects, and these cells can seed distant skin sites.

immunology↗