Tumor-derived Fas ligand induces toxicity in lymphoid organs and plays an important role in successful chemotherapy

 Recent studies have suggested that Fas ligand (FasL⁺) tumor cells can induce apoptosis in Fas⁺ T cells. However, the effect of growth of FasL⁺ tumors in vivo, on lymphoid tissues of the host is not clear and therefore was the subject of this investigation. Injection of FasL⁺ LSA tumor caused a significant decrease in cellularity of the thymus and spleen, resulting from marked apoptosis, in syngeneic C57BL/6+/+ (wild-type) but not C57BL/6-lpr/lpr (Fas-deficient) mice. The tumor-induced toxicity resulted from tumor-derived rather than host-derived FasL, inasmuch as LSA tumor growth in C57BL/6-gld/gld (FasL-defective) mice, induced marked apoptosis and toxicity in the thymus and spleen. The LSA tumor growth induced a significant decrease in the percentage of CD4⁺CD8⁺ T cells in the thymus of C57BL/6+/+ mice and an increase in the percentage of CD4⁺, CD8⁺ and CD4⁻CD8⁻ T cells. Of the four subpopulations tested, the CD4⁺CD8⁺ T cells showed maximum apoptosis. The LSA (FasL⁺) but not P815(FasL⁻) tumor cell lysates and culture supernatants induced marked apoptosis in Fas⁺ thymocytes, when tested both in vitro and in vivo. The LSA-tumor-induced apoptosis in vitro was inhibited by antibodies against FasL or by caspase and other inhibitors of apoptosis. Chemotherapy of LSA-tumor-bearing C57BL/6+/+ mice at advanced stages of tumor growth failed to cure the mice, whereas, more than 80% of LSA-tumor-bearing C57BL/6-lpr/lpr mice, similarly treated, survived. Together, the current study demonstrates that FasL produced by LSA tumor cells is functional in vivo and can cause severe toxicity in lymphoid organs of the host. Also, Fas/FasL interactions may play an important role in the successful chemotherapy of FasL-bearing tumor. Received: 31 August 1999 / Accepted: 12 November 1999     

Gallium arsenide exposure impairs processing of particulate antigen by macrophages: modification of the antigen reverses the functional defect

Gallium arsenide (GaAs), a semiconductor used in the electronics industry, causes systemic immunosuppression in animals. The chemical's impact on macrophages to process the particulate antigen, sheep red blood cells (SRBC), for a T cell response in culture was examined after in vivo exposure of mice. GaAs-exposed splenic macrophages were defective in activating SRBC-primed lymph node T cells that could not be attributed to impaired phagocytosis. Modified forms of SRBC were generated to examine the compromised function of GaAs-exposed macrophages. SRBC were fixed to maintain their particulate nature and subsequently delipidated with detergent. Delipidation of intact SRBC was insufficient to restore normal antigen processing in GaAs-exposed macrophages. However, chemically exposed cells efficiently processed soluble sheep proteins. These findings suggest that the problem may lie in the release of sequestered sheep protein antigens, which then could be effectively cleaved to peptides. Furthermore, opsonization of SRBC with IgG compensated for the macrophage processing defect. The influence of signal transduction and phagocytosis via Fcgamma receptors on improved antigen processing could be dissociated. Immobilized anti-Fcgamma receptor antibody activated macrophages to secrete a chemokine, but did not enhance processing of unmodified SRBC by GaAs-exposed macrophages. Restoration of normal processing of particulate SRBC by chemically exposed macrophages involved phagocytosis through Fcgamma receptors. Hence, initial immune responses may be very sensitive to GaAs exposure, and the chemical's immunosuppression may be averted by opsonized particulate antigens.     

Formation of a protein corona influences the biological identity of nanomaterials

The development and testing of nanomaterials is an area of interest due to promising diagnostic and therapeutic applications in the treatment of diseases like cancer or cardiovascular disease. While extensive studies of the physicochemical properties of nanoparticles (NPs) are available, the investigation of the protein corona (PC) that is formed on NPs in biofluids is a relatively new area of research. The fact that few NPs are in clinical use indicates that the biological identity of NPs, which is in large part due to the PC formed in blood or other bodily fluids, may be altered in ways yet to be fully understood. Herein, we review the recent advances in PC research with the intent to highlight the current state of the field. We discuss the dynamic processes that control the formation of the PC on NPs, which involve the transient soft corona and more stable hard corona. Critical factors, like the environment and disease-state that affect the composition and stability of the PC are presented, with the intent of showcasing promising applications for utilizing the PC for disease diagnosis and the identification of disease-related biomarkers. This review summarizes the unique challenges presented by the nanoparticle corona and indicates future directions for investigation.     

Kinetics and morphology of chemically induced popliteal lymph node reactions compared with antigen-, mitogen-, and graft-versus-host-reaction-induced responses

Changes in the popliteal lymph node (PLN) in mice evoked by a local graft-versus-host (GVH) reaction and by a single injection of various agents into the hind footpad were compared. The drug diphenylhydantoin induced similar weight changes in time as the GVH reaction. More vigorous and protracted reactions were induced by the drug nitrofurantoin and the contact sensitizer dinitrochlorobenzene, whereas the antigens lipopolysaccharide and sheep erythrocytes caused very moderate and short-lasting weight changes. Alterations of lymph node architecture upon injection of diphenylhydantoin resembled those observed during the GVH response. Some quantitative and qualitative differences were noted for nitrofurantoin, but clearly deviant morphological alterations were seen in response to lipopolysaccharide and sheep erythrocytes. The PLN reaction to dinitrochlorobenzene had features of both the GVH reaction and the antigen-induced responses. These findings support the concept that some drugs and chemicals may induce or exacerbate lymphoproliferative disorders by GVH-like mechanisms.     

pDNA bioparticles: comparative heterogeneity, surface, binding, and activity analyses

New applications for nucleic acid-bound micro/nanoparticles are emerging in drug delivery, biocatalysis, diagnostics, and toxicology. Bioactivity of viral or liposomal based technologies is limited by heterogeneity, partitioning, aggregation, and protein binding in physiological fluids, underlying immunotoxicity, and poor in vitro and cell-culture corollaries. Here we have systematically investigated novel pDNA bioparticles formed through complexation to model non-viral/non-lipid materials, peptides, aminoglycans, and small molecules (polybrene, chitosan, butirosin, protamine, Lys10, RGDS, bupivacaine, and chlorpromazine). On the basis of characterization by heterogeneity, kinetics, partitioning in physiological fluid and serum protein-binding, surface, size and electrophoretic behavior, transfection, and immunotoxicity, notably protamine, and chitosan DNA particles gave a long lifetime (12-18h), low protein-binding (<10microg/ml), good transfection activity (10(2)-10(4)RLU/mg cell protein), and low immunotoxicity. Our results support further evaluation of these materials as potential alternatives to viral or liposomal approaches, in combination with pDNA as binding, expression or therapeutic agents.     

Detection of antinuclear and antilaminin antibodies in autistic children who received thimerosal-containing vaccines

Autism, a neurodevelopmental disorder, may involve autoimmune pathogenesis. Since mercury is potentially a risk factor for autoimmunity, we conducted a study of mercury-induced antinuclear and antilaminin antibodies in autistic and normal children who had been pre-administered with thimerosal-containing vaccines. Laboratory analysis by different immunoassays showed that the serum level of these two autoimmune markers did not significantly differ between autistic and normal children. This finding suggests that the mercury as in thimerosal-containing vaccines is likely not related to autoimmune phenomenon in autism.     

In vitro vomitoxin exposure alters IgA and IgM secretion by CH12LX B cells

The CH12LX cell line was used as a clonal model to assess the direct effects of vomitoxin on IgM and IgA secretion in B cells. When vomitoxin was included in LPS-driven CH12LX B cell cultures, it had multiple effects on Ig secretion. Whereas vomitoxin doses of 115 and 120 ng/ml caused 50% inhibition(ID₅₀) of IgA and IgM production, respectively, toxin concentrations in the 5 to 50 ng/ml range slightly stimulated IgA production. However, low vomitoxin doses did not induce switching of membrane IgM+ CH12LX B cells to membrane IgA+. Total cell number was unaffected at vomitoxin concentrations up to 100 ng/ml but dropped markedly at 200 ng/ml (ID₅₀=170 ng/ml). Using the MTT reduction assay as another measure of viability and cell function, vomitoxin was also inhibitory (ID₅₀=130 ng/ml). Both thymidine incorporation and leucine incorporation were also inhibited by the toxin with estimated ID₅₀s being 120 and 110 ng/ml, respectively. The results indicate that although at high doses, vomitoxin inhibits proliferation, Ig secretion and DNA/protein synthesis in the clonal B cell model, the toxin marginally stimulated IgA secretion at lower doses.     

Off-target immune cell toxicity caused by AG-012986, a pan-CDK inhibitor, is associated with inhibition of p38 MAPK phosphorylation

AG-012986 is a pan-CDK (cyclin-dependent kinase) inhibitor that has in vitro and in vivo antitumor properties but was stopped in development due in part to rapid bone-marrow-independent white blood cell toxicity in preclinical studies and the potential for acute and delayed immunosuppression in humans. Because peripheral lymphocytes are largely nonproliferating, it was hypothesized the toxicity of AG-012986 was due to an off-target mechanism and not driven by the intended pharmacology. We show the toxicity mechanism in primary human immune cells is caspase driven. T-cells treated with AG-012986 and acutely stimulated through the T-cell receptor exhibited decreased toxicity while still maintaining cell division inhibition. This indicated that the pharmacology of AG-012986 functioned as expected but the toxicity had now been decoupled through activation. Induced phosphorylation of p38 and IL-2 production was impaired with AG-012986. Thus, AG-012986 could cause apoptosis of T-cells by targeting upstream kinases in the p38 Mitogen-activated protein kinase (MAPK) pathway and impairing cellular survival.     

Engineered metal based nanoparticles and innate immunity

Almost all people in developed countries are exposed to metal nanoparticles (MeNPs) that are used in a large number of applications including medical (for diagnostic and therapeutic purposes). Once inside the body, absorbed by inhalation, contact, ingestion and injection, MeNPs can translocate to tissues and, as any foreign substance, are likely to encounter the innate immunity system that represent a non-specific first line of defense against potential threats to the host. In this review, we will discuss the possible effects of MeNPs on various components of the innate immunity (both specific cells and barriers). Most important is that there are no reports of immune diseases induced by MeNPs exposure: we are operating in a safe area. However, in vitro assays show that MeNPs have some effects on innate immunity, the main being toxicity (both cyto- and genotoxicity) and interference with the activity of various cells through modification of membrane receptors, gene expression and cytokine production. Such effects can have both negative and positive relevant impacts on humans. On the one hand, people exposed to high levels of MeNPs, as workers of industries producing or applying MeNPs, should be monitored for possible health effects. On the other hand, understanding the modality of the effects on immune responses is essential to develop medical applications for MeNPs. Indeed, those MeNPs that are able to stimulate immune cells could be used to develop of new vaccines, promote immunity against tumors and suppress autoimmunity.