Regulation of immune responsiveness in vivo by disrupting an early T-cell signaling event using a cell-permeable peptide

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

In this study, we investigated whether 4-hydroxycinnamic acid (HA) has a palliative effect on asthmatic inflammatory responses using a mouse model of ovalbumin (OVA)-induced allergic asthma. The mice were divided into five groups, each consisting of seven females (normal control phosphate-buffered saline); OVA (OVA sensitization/challenge); dexamethasone (DEX, OVA sensitization/challenge + dexamethasone 3 mg/kg); HA-10 and HA-20 OVA sensitization/challenge + HA 10 and 20 mg/kg, respectively). Mice treated with HA showed a reduction in airway hyperresponsiveness and in the number of inflammatory cells in bronchoalveolar lavage fluid (BALF) compared with asthmatic control. HA treatment also reduced the levels of interleukin (IL)-5 and IL-13 in BALF and of OVA-specific immunoglobulin E in the serum compared with asthmatic control. HA treatment relieved airway inflammation and mucus overproduction caused by OVA exposure. Additionally, HA inhibited the increases in levels of nuclear factor kappa B, inducible nitric oxide synthase, and cyclooxygenase-2 that normally occur after OVA exposure. HA treatment also reduced the activity and protein level of matrix metalloproteinase-9. Taken together, HA effectively suppressed asthmatic airway inflammation and mucus production caused by OVA exposure. These findings indicate that HA has the potential to be used as a therapeutic agent for asthma.

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

Signaling through the T cell antigen receptor (TCR) activates a series of tyrosine kinases. Directly associated with the TCR, the SRC family kinase LCK and the SYK family kinase ZAP-70 are essential for all downstream responses to TCR stimulation. In contrast, the TEC family kinase ITK is not an obligate component of the TCR cascade. Instead, ITK functions as a tuning dial, to translate variations in TCR signal strength into differential programs of gene expression. Recent insights into TEC kinase structure have provided a view into the molecular mechanisms that generate different states of kinase activation. In resting lymphocytes, TEC kinases are autoinhibited, and multiple interactions between the regulatory and kinase domains maintain low activity. Following TCR stimulation, newly generated signaling modules compete with the autoinhibited core and shift the conformational ensemble to the fully active kinase. This multidomain control over kinase activation state provides a structural mechanism to account for ITK's ability to tune the TCR signal.

A peptide-functionalized polymer as a minimal scaffold protein to enhance cluster formation in early T cell signal transduction

In cellular signal transduction, scaffold proteins provide binding sites to organize signaling proteins into supramolecular complexes and act as nodes in the signaling network. Furthermore, multivalent interactions between the scaffold and other signaling proteins contribute to the formation of protein microclusters. Such microclusters are prominent in early T cell signaling. Here, we explored the minimal structural requirement for a scaffold protein by coupling multiple copies of a proline-rich peptide corresponding to an interaction motif for the SH3 domain of the adaptor protein GADS to an N-(2-hydroxypropyl)methacrylamide polymer backbone. When added to GADS-containing cell lysates, these scaffolds (but not individual peptides) promoted the binding of GADS to peptide microarrays. This can be explained by the cross-linking of GADS into larger complexes. Furthermore, following import into Jurkat T cell leukemia cells, this synthetic scaffold enhanced the formation of microclusters of signaling proteins.

Discovery of novel irreversible inhibitors of interleukin (IL)-2-inducible tyrosine kinase (Itk) by targeting cysteine 442 in the ATP pocket

IL-2-inducible tyrosine kinase (Itk) plays a key role in antigen receptor signaling in T cells and is considered an important target for anti-inflammatory drug discovery. In order to generate inhibitors with the necessary potency and selectivity, a compound that targeted cysteine 442 in the ATP binding pocket and with an envisaged irreversible mode of action was designed. We incorporated a high degree of molecular recognition and specific design features making the compound suitable for inhaled delivery. This study confirms the irreversible covalent binding of the inhibitor to the kinase by x-ray crystallography and enzymology while demonstrating potency, selectivity, and prolonged duration of action in in vitro biological assays. The biosynthetic turnover of the kinase was also examined as a critical factor when designing irreversible inhibitors for extended duration of action. The exemplified Itk inhibitor demonstrated inhibition of both TH1 and TH2 cytokines, was additive with fluticasone propionate, and inhibited cytokine release from human lung fragments. Finally, we describe an in vivo pharmacodynamic assay that allows rapid preclinical development without animal efficacy models.