The synthesis, characterization, and biomedical application in preparing more thromboresistant polymeric coatings for a series of lipophilic dialkyldiamine-based diazeniumdiolatesare described. Dialkylhexamethylenediamine diazeniumdiolates of the form RN[N(O)NO](-)(CH(2))(6)NH(2)(+)R, where R = CH(3), CH(2)CH(3), (CH(2))(2)CH(3), (CH(2))(3)CH(3), (CH(2))(4)CH(3,) (CH(2))(5)CH(3), and (CH(2))(11)CH(3), are prepared via reaction of the corresponding diamine with NO. The more lipophilic diazeniumdiolates [e.g., R = (CH(2))(3)CH(3)] can be incorporated into hydrophobic polymeric films (e.g., plasticized PVC), and the resulting materials release NO for extended periods of time upon exposure to PBS buffer. The mechanism of NO release from these films is examined in detail. More stable initial NO release can be achieved by adding lipophilic anionic species (e.g., tetraphenylborate derivative) to the polymeric material to buffer the activity of protons within the organic phase. It is shown that the use of these new lipophilic NO-donors in polymers provides the ability to tailor NO release rates for a variety of medical applications. As an example, polymers doped with N,N'-dibutylhexamethylenediamine diazeniumdiolate and a tetraphenylborate derivative are employed as coatings for vascular grafts in sheep. The NO release grafts exhibited enhanced performance and had an average 95% thrombus-free surface area compared to 42% for the corresponding control grafts when examined after 21d of implantation.
CD8+ T cells play a critical role in adaptive immunity, differentiating into CD8+ memory T cells that form the basis of protective cellular immunity. Vaccine efficacy is attributed to long-term protective immunity, and understanding the parameters that regulate development of CD8+ T cells is critical to the design of T cell–mediated vaccines. We show in this study using mouse models that two distinct parameters, TCR signal strength (regulated by the tyrosine kinase ITK) and Ag affinity, play important but separate roles in modulating the development of memory CD8+ T cells. Unexpectedly, our data reveal that reducing TCR signal strength along with reducing Ag affinity for the TCR leads to enhanced and accelerated development of CD8+ memory T cells. Additionally, TCR signal strength is able to regulate CD8+ T cell effector cytokine R production independent of TCR Ag affinity. Analysis of RNA-sequencing data reveals that genes for inflammatory cytokines/cytokine receptors are significantly altered upon changes in Ag affinity and TCR signal strength. Furthermore, our findings show that the inflammatory milieu is critical in regulating this TCR signal strength–mediated increase in memory development, as both CpG oligonucleotide treatment or cotransfer of wild-type and Itk−/− T cells eliminates the observed increase in memory cell formation. These findings suggest that TCR signal strength and Ag affinity independently contribute to CD8+ memory T cell development, which is modulated by inflammation, and suggest that manipulating TCR signal strength along with Ag affinity, may be used to tune the development of CD8+ memory T cells during vaccine development.
CD4+ effector T cells effectuate T cell immune responses, producing cytokines to orchestrate the nature and type of immune responses. The non-receptor tyrosine kinase IL-2 inducible T cell kinase (ITK), a mediator of T cell Receptor signaling, plays a critical role in tuning the development of these effector cells. In this review we discussed the role that signals downstream of ITK, including the Ras/MAPK pathway, play in differentially controlling the differentiation of TH17, Foxp3+ T regulatory (Treg) cells, and Type 1 regulatory T (Tr1) cells, supporting a model of ITK signals controlling a decision point in the effector T cell differentiation process.
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