Administration of either anti-CD40 or interleukin-12 following lethal total body irradiation induces acute lethal toxicity affecting the gut

AbstractInterleukin (IL)-12 and antibodies against CD40 have demonstrated antitumor effects in a variety of in vivo model systems. However, both agents can also mediate significant toxicities either when used following lethal TBI or when administered in combination with other agents such as IL-2. In this study, we assessed the effects of anti-CD40 monoclonal antibody (MoAb) and IL-12 in lethally irradiated mice. Acute lethal toxicity was observed following the administration of either 10 microg anti-CD40 MoAb (FGK45) or 0.5 microg of recombinant murine (rm)IL-12 that resulted in 100% mortality of all mice within 4 to 6 days. Histological evaluation revealed destruction of the normal gut architecture in both anti-CD40 MoAb- and rmIL-12-treated mice. Analysis of serum cytokine levels in the lethally irradiated mice receiving anti-CD40 MoAb demonstrated a marked increase of interferon (IFN)-gamma and IL-12 p40, whereas mice receiving rmIL-12 demonstrated a marked increase of IFN-gamma. Lethally irradiated IL-12 p40 knock-out mice were resistant to anti-CD40-induced toxicity, suggesting that the lack of IL-12 p40 with no possibility of making functional IL- 12 p70 is key for this toxic reaction. Similarly, lethally irradiated IFN-gamma knock-out mice were completely resistant to rmIL-12-induced toxicity, suggesting that IFN-gamma is a major player in IL-12-mediated toxicity. These results suggest that both anti-CD40 MoAb and rmIL-12 induce an acute fatal toxicity characterized by similar intestinal pathology and mediated in part by IFN-gamma.Biol Blood Marrow Transplant 2002;8(6):316-25

Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand (Trail) Contributes to Interferon γ–Dependent Natural Killer Cell Protection from Tumor Metastasis

Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is expressed by in vitro activated natural killer (NK) cells, but the relevance of this observation to the biological function of NK cells has been unclear. Herein, we have demonstrated the in vivo induction of mouse TRAIL expression on various tissue NK cells and correlated NK cell activation with TRAIL-mediated antimetastatic function in vivo. Expression of TRAIL was only constitutive on a subset of liver NK cells, and innate NK cell control of Renca carcinoma hepatic metastases in the liver was partially TRAIL dependent. Administration of therapeutic doses of interleukin (IL)-12, a powerful inducer of interferon (IFN)-γ production by NK cells and NKT cells, upregulated TRAIL expression on liver, spleen, and lung NK cells, and IL-12 suppressed metastases in both liver and lung in a TRAIL-dependent fashion. By contrast, α-galactosylceramide (α-GalCer), a powerful inducer of NKT cell IFN-γ and IL-4 secretion, suppressed both liver and lung metastases but only stimulated NK cell TRAIL-mediated function in the liver. TRAIL expression was not detected on NK cells from IFN-γ–deficient mice and TRAIL-mediated antimetastatic effects of IL-12 and α-GalCer were strictly IFN-γ dependent. These results indicated that TRAIL induction on NK cells plays a critical role in IFN-γ–mediated antimetastatic effects of IL-12 and α-GalCer

The CD95 Receptor: Apoptosis Revisited

CD95 is the quintessential death receptor and, when it is bound by ligand, cells undergo apoptosis. Recent evidence suggests, however, that CD95 mediates not only apoptosis but also diverse nonapoptotic functions depending on the tissue and the conditions

Out-of-Sequence Signal 3 Paralyzes Primary CD4+ T-Cell-Dependent Immunity

SummaryPrimary T cell activation involves the integration of three distinct signals delivered in sequence: (1) antigen recognition, (2) costimulation, and (3) cytokine-mediated differentiation and expansion. Strong immunostimulatory events such as immunotherapy or infection induce profound cytokine release causing “bystander” T cell activation, thereby increasing the potential for autoreactivity and need for control. We show that during strong stimulation, a profound suppression of primary CD4+ T-cell-mediated immune responses ensued and was observed across preclinical models and patients undergoing high-dose interleukin-2 (IL-2) therapy. This suppression targeted naive CD4+ but not CD8+ T cells and was mediated through transient suppressor of cytokine signaling-3 (SOCS3) inhibition of the STAT5b transcription factor signaling pathway. These events resulted in complete paralysis of primary CD4+ T cell activation, affecting memory generation and induction of autoimmunity as well as impaired viral clearance. These data highlight the critical regulation of naive CD4+ T cells during inflammatory conditions

Systemic IL-12 Administration Alters Hepatic Dendritic Cell Stimulation Capabilities

The liver is an immunologically unique organ containing tolerogenic dendritic cells (DC) that maintain an immunosuppressive microenvironment. Although systemic IL-12 administration can improve responses to tumors, the effects of IL-12-based treatments on DC, in particular hepatic DC, remain incompletely understood. In this study, we demonstrate systemic IL-12 administration induces a 2–3 fold increase in conventional, but not plasmacytoid, DC subsets in the liver. Following IL-12 administration, hepatic DC became more phenotypically and functionally mature, resembling the function of splenic DC, but differed as compared to their splenic counterparts in the production of IL-12 following co-stimulation with toll-like receptor (TLR) agonists. Hepatic DCs from IL-12 treated mice acquired enhanced T cell proliferative capabilities similar to levels observed using splenic DCs. Furthermore, IL-12 administration preferentially increased hepatic T cell activation and IFNγ expression in the RENCA mouse model of renal cell carcinoma. Collectively, the data shows systemic IL-12 administration enables hepatic DCs to overcome at least some aspects of the inherently suppressive milieu of the hepatic environment that could have important implications for the design of IL-12-based immunotherapeutic strategies targeting hepatic malignancies and infections

Macrophage-dependent nitric oxide expression regulates tumor cell detachment and metastasis after IL-2/anti-CD40 immunotherapy

Immunotherapy with IL-2 and anti-CD40 induces the expression of NOS2 in tumor-associated macrophages, and its expression is required for the inhibition of tumor metastasis