The importance of T cell based immunity in preventing skin infections is well studied and best exemplified by patients with genetic defects in the CD4+ Th17 pathway (e.g. hyper IgE syndrome). Patients with defects in the generation of antibody responses (e.g. X-linked agammaglobulinemia, hyper IgM syndrome) also suffer from recurrent skin bacterial pyogenic and viral infections. In addition, antibody responses to antigen found in the skin are pathogenic in numerous autoimmune blistering diseases and participate in atopic dermatitis and the atopic march. Despite the clear importance of humoral responses to skin health and disease, the mechanisms that generate antibody responses to cutaneous antigen are very poorly studied. Skin-resident dendritic cells (DC) are professional antigen presenting cells that acquire antigen in the skin. One DC subset, Langerhans cells (LC), form a dense DC network in the epidermis. They extend their dendrites to the upper epidermis and into the stratum corneum where they are able to acquire antigen. We have discovered that LC 1) drive the generation of CD4+ T follicular helper cells (Tfh) that provide T cell help for B cells ad 2) are sufficient to induce humoral response under steady-state conditions. Thus, a major unappreciated function of LC during homeostatic conditions is the generation of Tfh and the associated humoral response. The central hypothesis of this proposal is that LC have a unique role in the generation of antibody responses to cutaneous antigen. In addition to LC in the epidermis, there are 2 major subsets of DC in the dermis. In the setting of a skin infection all 3 DC subsets promote distinct Th subset differentiation. We hypothesize that this distinction occurs during steady-state conditions as well and that only LC have the capacity to differentiate Tfh. We hypothesized that in addition to expanding Tfh, LC also transport intact cutaneous antigen to B cells. Finally, we hypothesize that LC are required to promote antibody responses during pathogen infection and for the generation of antibodies against skin commensal microorganisms. Understanding which DC subset, conditions and pathways drive the formation of antibodies specific for cutaneous antigen is critical to understanding the mechanisms of resistance to skin pathogens and the etiology of antibody-mediated skin diseases. This work has the potential to provide novel therapeutic targets for the modulation of skin immune function.

Public Health Relevance

Despite the clear importance of humoral responses to skin health and disease, the mechanisms that generate antibody responses to cutaneous antigen are very poorly studied. We hypothesize that during both steady-state and inflammatory conditions, LC are a key cell type that drives differentiation of T follicular helper cells and provides intact antigen to B cells. Understanding how antibodies against cutaneous antigen form is critical to understanding immunity to skin pathogens as well as the etiology of antibody- mediated skin diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
7R01AR067187-02
Application #
9151875
Study Section
Special Emphasis Panel (ZRG1-MOSS-U (02))
Program Officer
Cibotti, Ricardo
Project Start
2015-04-06
Project End
2020-03-31
Budget Start
2015-09-17
Budget End
2016-03-31
Support Year
2
Fiscal Year
2015
Total Cost
$195,816
Indirect Cost
$38,396
Name
University of Pittsburgh
Department
Dermatology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Kashem, Sakeen W; Kaplan, Daniel H (2018) Isolation of Murine Skin Resident and Migratory Dendritic Cells via Enzymatic Digestion. Curr Protoc Immunol 121:e45
Yao, Chen; Kaplan, Daniel H (2018) Langerhans Cells Transfer Targeted Antigen to Dermal Dendritic Cells and Acquire Major Histocompatibility Complex II In Vivo. J Invest Dermatol 138:1665-1668
Kaplan, Daniel H (2017) Ontogeny and function of murine epidermal Langerhans cells. Nat Immunol 18:1068-1075
Kashem, Sakeen W; Haniffa, Muzlifah; Kaplan, Daniel H (2017) Antigen-Presenting Cells in the Skin. Annu Rev Immunol 35:469-499
Kashem, Sakeen W; Kaplan, Daniel H (2016) Skin Immunity to Candida albicans. Trends Immunol 37:440-450
Huang, Huizhen; Kuzirian, Marissa S; Cai, Xiaoyun et al. (2016) Generation of a NK1R-CreER knockin mouse strain to study cells involved in Neurokinin 1 Receptor signaling. Genesis 54:593-601
Kumamoto, Yosuke; Hirai, Toshiro; Wong, Patrick W et al. (2016) CD301b(+) dendritic cells suppress T follicular helper cells and antibody responses to protein antigens. Elife 5:
Scholz, Felix; Naik, Shruti; Sutterwala, Fayyaz S et al. (2015) Langerhans Cells Suppress CD49a+ NK Cell-Mediated Skin Inflammation. J Immunol 195:2335-42
Kashem, Sakeen W; Riedl, Maureen S; Yao, Chen et al. (2015) Nociceptive Sensory Fibers Drive Interleukin-23 Production from CD301b+ Dermal Dendritic Cells and Drive Protective Cutaneous Immunity. Immunity 43:515-26