MicroRNA-29a attenuates CD8 T cell exhaustion and induces memory-like CD8 T cells during chronic infection.

CD8 T cells mediate protection against intracellular pathogens and tumors. However, persistent antigen during chronic infections or cancer leads to T cell exhaustion, suboptimal functionality, and reduced protective capacity. Despite considerable work interrogating the transcriptional regulation of exhausted CD8 T cells (TEX), the posttranscriptional control of TEX remains poorly understood.

Epigenetic scarring of exhausted T cells hinders memory differentiation upon eliminating chronic antigenic stimulation.

Exhausted CD8 T cells (T) are a distinct state of T cell differentiation associated with failure to clear chronic viruses and cancer. Immunotherapies such as PD-1 blockade can reinvigorate T cells, but reinvigoration is not durable. A major unanswered question is whether T cells differentiate into functional durable memory T cells (T) upon antigen clearance.

Distinct mechanisms govern populations of myeloid-derived suppressor cells in chronic viral infection and cancer.

Myeloid-derived suppressor cells (MDSCs) are major negative regulators of immune responses in cancer and chronic infections. It remains unclear if regulation of MDSC activity in different conditions is controlled by similar mechanisms. We compared MDSCs in mice with cancer and lymphocytic choriomeningitis virus (LCMV) infection.

Inhibitory signaling sustains a distinct early memory CD8 T cell precursor that is resistant to DNA damage.

The developmental origins of memory T cells remain incompletely understood. During the expansion phase of acute viral infection, we identified a distinct subset of virus-specific CD8 T cells that possessed distinct characteristics including expression of CD62L, T cell factor 1 (TCF-1), and Eomesodermin; relative quiescence; expression of activation markers; and features of limited effector differentiation. These cells were a quantitatively minor subpopulation of the TCF-1 pool and exhibited self-renewal, heightened DNA damage surveillance activity, and preferential long-term recall capacity.

The long noncoding RNA regulates CD8 T cells in response to viral infection.

The transcriptional programs that regulate CD8 T-cell differentiation and function in the context of viral infections or tumor immune surveillance have been extensively studied; yet how long noncoding RNAs (lncRNAs) and the loci that transcribe them contribute to the regulation of CD8 T cells during viral infections remains largely unexplored. Here, we report that transcription of the lncRNA is specifically induced by T-cell receptor (TCR) and type I IFN stimulation during the early stages of acute and chronic lymphocytic choriomeningitis virus (LCMV) infection. In response to type I IFN, the RNA and its locus control CD8 T cell expansion, survival, and effector function by regulating the expression of the proapoptotic factor, , and by modulating the strength of the PI3K-AKT signaling pathway.

Long-Term Persistence of Exhausted CD8 T Cells in Chronic Infection Is Regulated by MicroRNA-155.

Persistent viral infections and tumors drive development of exhausted T (T) cells. In these settings, T cells establish an important host-pathogen or host-tumor stalemate. However, T cells erode over time, leading to loss of pathogen or cancer containment.

Bystander chronic infection negatively impacts development of CD8(+) T cell memory.

Epidemiological evidence suggests that chronic infections impair immune responses to unrelated pathogens and vaccines. The underlying mechanisms, however, are unclear and distinguishing effects on priming versus development of immunological memory has been challenging. We investigated whether bystander chronic infections impact differentiation of memory CD8(+) T cells, the hallmark of protective immunity against intracellular pathogens.

Transcription factor T-bet represses expression of the inhibitory receptor PD-1 and sustains virus-specific CD8+ T cell responses during chronic infection.

T cell exhaustion has a major role in failure to control chronic infection. High expression of inhibitory receptors, including PD-1, and the inability to sustain functional T cell responses contribute to exhaustion. However, the transcriptional control of these processes remains unclear.