Regulation of Immune Responsiveness In Vivo by Disrupting an Early T-Cell Signaling Event Using a Cell-Permeable Peptide

Abstract

The inducible T cell kinase (ITK) regulates type 2 (Th2) cytokines that provide defense against certain parasitic and bacterial infections and are involved in the pathogenesis of lung inflammation such as allergic asthma. Activation of ITK requires the interaction of its SH3 domain with the poly-proline region of its signaling partner, the SH2 domain containing leukocyte phosphoprotein of 76 kilodaltons (SLP-76). The specific disruption of the ITK-SH3/SLP-76 poly-proline interaction in vitro by a cell-permeable competitive inhibitor peptide (R9-QQP) interferes with the activation of ITK and the transduction of its cellular functions in T lymphocytes. In the present investigation, we assessed the effects of R9-QQP treatment on the induction of an in vivo immune response as represented by lung inflammation in a murine model of allergic asthma. We found that mice treated with R9-QQP and sensitized and challenged with the surrogate allergen ovalbumin (OVA) display significant inhibition of lung inflammation in a peptide-specific manner. Thus, parameters of the allergic response, such as airway hyper-responsiveness, suppression of inflammatory cell infiltration, reduction of bronchial mucus accumulation, and production of relevant cytokines from draining lymph nodes were significantly suppressed. These findings represent the first demonstration of the biological significance of the interaction between ITK and SLP-76 in the induction of an immune response in a whole animal model and specifically underscore the significance of the ITK-SH3 domain interaction with the poly-proline region of SLP-76 in the development of an inflammatory response. Furthermore, the experimental approach of intracellular peptide-mediated inhibition might be applicable to the study of other important intracellular interactions thus providing a paradigm for dissecting signal transduction pathways.

Multidomain Control Over TEC Kinase Activation State Tunes the T Cell Response

“…Beyond intramolecular interactions, ITK SH3 targets other signaling proteins within the TCR cascade, and binding of the ITK SH3 domain to any exogenous ligand will disfavor the autoinhibited state (compare Figures 2c, 3a). The SLP-76 polyproline region has been implicated as an ITK SH3 target, and use of a cell-permeable competitive inhibitor peptide for the ITK SH3 domain suggests that the ITK SH3/SLP-76 interaction may be necessary for ITK activation (142,143). Since the cell-permeable peptide used in this work targeted the ITK SH3 binding pocket, and not SLP-76 directly, the results might in fact reflect the importance of ITK SH3 domain interactions with exogenous ligands generally rather than the specific proline-rich sequence of SLP-76.…”

A Peptide‐Functionalized Polymer as a Minimal Scaffold Protein To Enhance Cluster Formation in Early T Cell Signal Transduction

“…[28] Gruimond et al [29] subsequently showed that this peptide can reduce inflammation of the lungs in a murine model of allergic asthma. These studies illustrate the potential of bioactive peptides in the preclinical setting.…”

4‐Hydroxycinnamic acid suppresses airway inflammation and mucus hypersecretion in allergic asthma induced by ovalbumin challenge

“…During the development of asthma, Th2 cytokines play important roles in producing symptoms such as AHR, inflammatory response, and mucus hypersecretion (Guimond et al, ). Th2 cytokines cause smooth muscle contraction, inflammatory cell infiltration, and mucus overproduction in the airway (Kudo, Ishigatsubo, & Aoki, ).…”

“…Significantly different from NC, ## p < .01; significantly different from OVA, *p < .05, **p < .01, respectively. [Colour figure can be viewed at wileyonlinelibrary.com] and mucus hypersecretion (Guimond et al, 2013). Th2 cytokines cause smooth muscle contraction, inflammatory cell infiltration, and mucus overproduction in the airway (Kudo, Ishigatsubo, & Aoki, 2013).…”