The loss of immune tolerance characterizes the airway inflammation seen in asthma and allergy. This immune dysregulation has been attributed to reduced numbers and function of regulatory T-cells, including FoxP3+ regulatory T-cells (Treg) and IL-10 producing TR1. Strategies to promote their numbers and function would have great therapeutic benefit. Both Treg and TR1 require signaling through the IL-2R and the TCR for their induction and maintenance. However, the availability of IL-2 is tightly regulated and exposure to cognate antigens is often intermittent. Mechanisms that support regulatory T-cells in settings of low IL-2 and low cognate antigen are therefore crucial to immune homeostasis. The PI has identified roles for the extracellular matrix molecule hyaluronan (HA) and its receptor CD44 in promoting the number and function of regulatory T-cells. CD44 crosslinking in the setting of low-dose antigen promotes the function and maintenance of Foxp3+ Treg. The same cues also promote the induction of TR1 from conventional T-cell precursors. Building on this finding, intra-nasal delivery of low dose antigen and HMW- HA was used to induce antigen-specific TR1 in vivo. These responses are mediated through synergistic effects on IL-2R and TCR signaling. Because high molecular weight HA (HMW-HA) but not low molecular weight HA (LMW-HA) is capable of crosslinking CD44, tissue integrity plays a decisive role in these effects.
In Aims 1 and 2 the PI proposes to investigate the natural role of HMW-HA in Treg homeostasis.
In Aim 3 the PI will evaluate whether TR1 induced using intra-nasal vaccination with a HMW-HA adjuvant can prevent inflammation in an antigen-specific mouse model of airway hypersensitivity. This is a novel and highly innovative approach to immune modulation with great potential for the prevention of asthma and allergy.

Public Health Relevance

This work has the potential to greatly advance our understanding of the mechanisms that promote immune homeostasis in peripheral tissues. Moreover, the ability to induce antigen-specific TR1 in situ would be a boon for the treatment of diseases associated with airway inflammation, including asthma and allergy.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL113294-03
Application #
8704995
Study Section
Lung Cellular, Molecular, and Immunobiology Study Section (LCMI)
Program Officer
Noel, Patricia
Project Start
2012-08-15
Project End
2017-05-31
Budget Start
2014-08-08
Budget End
2015-05-31
Support Year
3
Fiscal Year
2014
Total Cost
$385,628
Indirect Cost
$140,628
Name
Stanford University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
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Bogdani, Marika; Johnson, Pamela Y; Potter-Perigo, Susan et al. (2014) Hyaluronan and hyaluronan-binding proteins accumulate in both human type 1 diabetic islets and lymphoid tissues and associate with inflammatory cells in insulitis. Diabetes 63:2727-43
Bollyky, Paul L; Vernon, Robert B; Falk, Ben A et al. (2013) IL-10 induction from implants delivering pancreatic islets and hyaluronan. J Diabetes Res 2013:342479
Bollyky, J B; Long, S A; Fitch, M et al. (2013) Evaluation of in vivo T cell kinetics: use of heavy isotope labelling in type 1 diabetes. Clin Exp Immunol 172:363-74