Differential Expression of Proteinase Inhibitor-9 and Granzyme B mRNAs in Activated Immunocompetent Cells

Abstract

The role of proteinase inhibitor (PI)-9 in hematopoietic cells remains unclear. To clarify the role of PI-9 in these cells, we compared the expressions of PI-9 mRNA and antigen with those of granzyme B (GrB). While the strongest expression of PI-9 mRNA was observed in a NK cell line YT-N10, it was also expressed in a B-acute lymphoblastic leukemia cell line U-Tree02, an EpsteinBarr Virus (EBV)-transformed B cell clone, a CD8 + T lymphocyte clone and a megakaryocytic cell line CMK, but not in a T cell line Jurkat. Phorbol 12-myristate 13 acetate (PMA) enhanced PI-9 mRNA expression in the CD8 + T lymphocyte clone and YT-N10 cells prior to GrB mRNA expression. IL-2 and IL-12 also had similar effects. PMA increased PI-9 mRNA expression in the EBV-transformed B cell clone and CMK cells, but IL-6 showed no effect. No changes were noted in PI-9 and GrB antigens after the addition of these agonists. Patients with graft-versus-host disease (GVHD) may have activated CTLs and NK cells. We therefore examined the expression of PI-9 and GrB mRNAs in eight patients after allogeneic hematopoietic stem cell transplantation with GVHD (n = 4) or without chronic GVHD (n = 4). Expression of GrB mRNA was significantly increased in three patients with GVHD and one patient without GVHD. Surprisingly, PI-9 mRNA expression was decreased in the eight patients. These results indicate that earlier synthesis of PI-9 may be essential for the prevention of autolysis of immunocompetent cells, and that the expression of PI-9 and GrB mRNAs may be controlled through different pathways.

Modulation of the granzyme B inhibitor proteinase inhibitor 9 (PI-9) by activation of lymphocytes and monocytes in vitro and by Epstein–Barr virus and bacterial infection

“…In concordance with this, in a recent study [21] constant expression of PI-9 protein − despite up-regulation of PI-9 RNA, which was not analysed in our study − was shown upon stimulation in a CD8-positive T cell clone. Because in NK cells activationinduced death has been shown to be mediated by selfdestructive GrB leaking into the cytosol of the cell [15], here, and also possibly in CTL [16], constant PI-9 protein expression despite stimulation may have a function in homeostasis regulation, leading to the long-term survival of inactive but short-term survival of activated cytotoxic cells.…”

“…Although PI-9 has been analysed in a number of model systems in vitro [2,4,11,20,21], its expression and regulation in clinical conditions such as infections or immune disorders is largely unknown to date.…”

Engineered Versions of Granzyme B and Angiogenin Overcome Intrinsic Resistance to Apoptosis Mediated by Human Cytolytic Fusion Proteins

“…During inflammation it is expressed by pro-inflammatory cells and cells infected by diverse viruses, including cytomegalovirus and EBV [87,90,91]. PI-9 expression can be upregulated by cytokines and inflammatory modulators such as lipopolysaccharides (LPS), interferons (IFNα and IFNγ), TNFα, and interleukins IL-1β and IL-2 [90,92,95], as well as estradiol-17β and other estrogens in the human liver, human HepG2 hepatoblastoma cells and MCF-7 breast cancer cells [75,[96][97][98]. Furthermore, PI-9 expression can be upregulated in renal tubular cells following allograft rejection, suggesting a protective role against granzyme B-mediated cytotoxicity that results in improved graft survival [99].…”

Improving the Therapeutic Potential of Human Granzyme B for Targeted Cancer Therapy

“…PI-9 can be induced in different cell lines by nuclear factor-κB (NF-B), activator protein-1 (AP-1), pro-inflammatory cytokines such as TNFα, and lipopolysaccharides [121,125,127]. PI-9 is also induced by phorbol myristate acetate and interleukin (IL-2) in CD8 + T cells [128,129], by viral dsRNA sensors in human renal tubular epithelial cells [123] and by estrogens and estrogen receptor-α in breast cancer cells [84,114]. The expression of PI-9 in renal tubular cells is upregulated following renal allograft rejection, suggesting that its induction could be used to confer resistance against GrB-mediated cytotoxic effects leading to improved graft survival [130].…”