Dissecting T Cell Contraction In Vivo Using a Genetically Encoded Reporter of Apoptosis

Abstract

Contraction is a critical phase of immunity whereby the vast majority of effector T cells die by apoptosis, sparing a population of long-lived memory cells. Where, when, and why contraction occurs has been difficult to address directly due in large part to the rapid clearance of apoptotic T cells in vivo. To circumvent this issue, we introduced a genetically encoded reporter for caspase-3 activity into naive T cells to identify cells entering the contraction phase. Using two-photon imaging, we found that caspase-3 activity in T cells was maximal at the peak of the response and was associated with loss of motility followed minutes later by cell death. We demonstrated that contraction is a widespread process occurring uniformly in all organs tested and targeting phenotypically diverse T cells. Importantly, we identified a critical window of time during which antigen encounters act to antagonize T cell apoptosis, supporting a causal link between antigen clearance and T cell contraction. Our results offer insight into a poorly explored phase of immunity and provide a versatile methodology to study apoptosis during the development or function of a variety of immune cells in vivo.

Caspase-9 has a nonapoptotic function in Xenopus embryonic primitive blood formation

“…ns, not significant; *P<0.05; **P<0.005 (Student's t-test). Garrod et al, 2012;Hawkins et al, 1999;Johnson et al, 2009;Khanna et al, 2010;Yamaguchi et al, 2011;Zhang et al, 2009). Most of these reporters make use of the fluorescence resonance energy transfer (FRET) technology or a surface plasmon resonance imaging system, in which the fluorescent signal is lost after caspase cleavage (Park et al, 2008).…”

Assessing T lymphocyte function and differentiation by genetically encoded reporter systems

“…Thus, reporter activation has to occur early during the apoptotic cascade. An early event in the apoptotic cascade is the activation of caspase-3, and the proteolytic activity of this caspase has successfully been used to detect apoptotic cells [59]. To this end, a FRET-based reporter was created that comprises CFP and YFP linked by a caspase-3 cleavage sequence.…”

Immunological Response in Bovine Lymph Nodes Stimulated With Subunits Vaccines

“…However, during immune response by synthetic peptide, was observed growth adaptive immune response after levels of γδ WC1 + Tcell decrease in peripheral blood, suggesting that these cells may increase the APCs density in periperical tissues (Patarroyo et al, 2009). Likewise, the aumented of APCs densities with low T cells densities, could also contribute to apoptosis emergence when employed tandem peptide in high antigen dose (Garrod et al, 2012;Celly et al, 2012).…”

“…These fate, could result from cell death activation, which induces effector response interruption, influenced by antigens levels over superior limit capable to induce tolerance and cell proliferation decrease (Garrod et al, 2012). Similarly, in apoptosis made by high antigen doses, the T cell activation started signalization events including dowregulation of growth cytokine synthesis in cell cycle progression and TCR re-engagement (Azar et al, 2010).…”

“…Issue studied by Garrod et al (2012) who observed transient interactions formation between T CD 8+ cells and DCs at low peptide concentrations, followed by stable contacts between themselves cells on same peptide dilution. Moreover, other studies showed that transient interactions were more relevant to beginning antigen response by formation of stable conjugates between T cells-DC with the ability to cell proliferation increase (Hugues, 2010;Azar et al, 2010).…”