Direct effects of type I interferons on cells of the immune system

Control of type I interferon-induced cell death by Orai1-mediated calcium entry in T cells

Store-operated Ca(2+) entry (SOCE) is an essential process in T cell activation. SOCE is controlled by the Ca(2+) release-activated Ca(2+) (CRAC) channel encoded by the gene Orai1 that is expressed on the plasma membrane and activated by STIM1 when ER Ca(2+) stores are depleted. Our earlier work showed that a somatic T-cell line Jurkat mutant H123 bearing a defect in Ca(2+) signaling was susceptible to the apoptotic effects of type I interferons (IFN-α/β). The nature of the mutation and whether this mutation was linked to IFN-α/β apoptotic susceptibility was unknown. Here we show that H123 cells lacked Orai1 and exhibit reduced STIM1 protein. Reconstitution of both Orai1 and STIM1 in H123 cells rescued SOCE in response to thapsigargin and ionomycin and abrogated IFN-α/β-induced apoptosis. Reciprocally, overexpression of the dominant negative Orai1-E106A in either parental Jurkat cells or an unrelated human T cell line (CEM391) inhibited SOCE and led to sensitization to IFN-α/β-induced apoptosis. Furthermore, we showed that the Ca(2+) response pathway antagonized the IFN-α/β -induced transcriptional responses; in the absence of SOCE, this negative regulatory effect was lost. However, the inhibitory effect of Ca(2+) on type I IFN-induced gene transcription was diminished by pharmacological inhibition of NF-κB in cells with intact SOCE. Our findings reveal an unexpected and novel regulatory crosstalk mechanism between type I IFNs and store-operated Ca(2+) signaling pathways mediated at least in part by NF-κB activity with significant clinical implications to both viral and tumor immunology.

A temporal role of type I interferon signaling in CD8+ T cell maturation during acute West Nile virus infection

A genetic absence of the common IFN-α/β signaling receptor (IFNAR) in mice is associated with enhanced viral replication and altered adaptive immune responses. However, analysis of IFNAR(-/-) mice is limited for studying the functions of type I IFN at discrete stages of viral infection. To define the temporal functions of type I IFN signaling in the context of infection by West Nile virus (WNV), we treated mice with MAR1-5A3, a neutralizing, non cell-depleting anti-IFNAR antibody. Inhibition of type I IFN signaling at or before day 2 after infection was associated with markedly enhanced viral burden, whereas treatment at day 4 had substantially less effect on WNV dissemination. While antibody treatment prior to infection resulted in massive expansion of virus-specific CD8(+) T cells, blockade of type I IFN signaling starting at day 4 induced dysfunctional CD8(+) T cells with depressed cytokine responses and expression of phenotypic markers suggesting exhaustion. Thus, only the later maturation phase of anti-WNV CD8(+) T cell development requires type I IFN signaling. WNV infection experiments in BATF3(-/-) mice, which lack CD8-α dendritic cells and have impaired priming due to inefficient antigen cross-presentation, revealed a similar effect of blocking IFN signaling on CD8(+) T cell maturation. Collectively, our results suggest that cell non-autonomous type I IFN signaling shapes maturation of antiviral CD8(+) T cell response at a stage distinct from the initial priming event.

Cytokines in cancer immunotherapy

Cytokines are molecular messengers that allow the cells of the immune system to communicate with one another to generate a coordinated, robust, but self-limited response to a target antigen. The growing interest over the past two decades in harnessing the immune system to eradicate cancer has been accompanied by heightened efforts to characterize cytokines and exploit their vast signaling networks to develop cancer treatments. The goal of this paper is to review the major cytokines involved in cancer immunotherapy and discuss their basic biology and clinical applications. The paper will also describe new cytokines in pre-clinical development, combinations of biological agents, novel delivery mechanisms, and potential directions for future investigation using cytokines.