Natural resistance against tumors grafted into the brain in association with histocompatibility-class-I-antigen expression

Understanding the molecular pathogenesis of primary central nervous system lymphoma by experimental animal models

Primary central nervous system lymphoma (PCNSL) is a rare and invasive diffuse large B cell lymphoma confined in central nervous system (CNS). The effort to press forward the translational progress has been frustrated by the insufficient understanding of immunophenotype of CNS and tumor genetic alterations of PCNSL, and the lack of validated diagnostic biomarkers. Researchers now have a variety of PCNSL animal models at their disposal that resemble the morphology and immunophenotype of PCNSL, however, a careful and detailed re-examination of these animal models is needed to clarify the differences in genetic alterations, migration capability, and immune status. In this review, we present the knowledge about the phenotypic and genotypic features of PCNSL tumor cells, and compile the preclinical animal models of PCNSL with regard to various injection sites, cell origins, recipient animals, and immune status, and elaborate on the tropism and migration of tumor cells and novel therapeutic strategies for PCNSL. We envisage that the selection of suitable animal models will serve as a well-defined preclinical system to understand the molecular pathogenesis of PCNSL, thereby galvanizing the development of novel and potent therapeutic approaches.

Enhanced Survival of Porcine Neural Xenografts in Mice Lacking CD1d1, But No Effect of NK1.1 Depletion

Transplantation of embryonic porcine neurons may restore neurological function in patients with Parkinson's disease, if immunological rejection could be prevented. This study was performed to investigate the role of natural killer cells (NK cells) and NK1.1+ T cells (NK T cells) in the rejection of neural xenografts. A cell suspension was prepared from the ventral mesencephalon of 26 – 27-day-old pig embryos, and 2 μl was implanted in the right striata of mutant CD1d1 null (CD1.1-/-) mice, NK1.1-depleted mice, and controls. The CD1.1-/- mice are deficient in NK T cells and the antigen-presenting molecule CD1d1. Graft survival and host responses were determined immunohistochemically using markers for dopamine neurons, CD4-, CD8- cells, microglia, and macrophages. At 2 weeks, the grafts were significantly larger in CD1.1-/- mice, 0.09 ± 0.02 μl (mean ± SEM), compared with controls, 0.05 ± 0.01 μl. There was no significant difference between NK1.1-depleted mice, 0.02 ± 0.01 μl, and controls. At 5 weeks, two grafts were still present in the CD1-/- mice, whereas only scars remained in the controls and in the NK1.1-depleted mice. Immune reactions were strong at 2 weeks and less pronounced at 5 weeks in all groups. Microglial activation was lower in NK-depleted mice than in the controls at 2 weeks. In contrast to organ xenografting, NK1.1+ cells do not seem to be important mediators of the rejection of discordant cellular neural xenografts. However, our results suggest that the antigen-presenting molecule CD1d1 may be involved in the rejection process.

Mouse models of primary central nervous system lymphomas: tools for basing funding and therapeutic strategies

Primary central nervous system lymphomas (PCNSL) include ocular and cerebral lymphomas and are rare aggressive malignancies with poor prognoses. Compared with other lymphomas, they are a challenge for clinicians and scientists, for diagnosis and therapeutic progress and their prognosis remains unsatisfactory, because of the lack of molecular and biological knowledge. Indeed, several limitations of human sample present a major obstacle to the identification of the particular microenvironment of the sanctuary sites where these tumor cells grow. In addition, the generally poor overall condition and performance status of patients with PCNSL limit their participation in prospective trials. Therefore, animal models of PCNSL are essential for tumor microenvironment characterization and for antitumor response studying. In this review, we have compiled the B-and T-cell PCNSL mouse models that are used to improve our understanding of the lymphoma microenvironment, tropism and migration and to investigate novel therapeutic strategies.

Genetically based therapeutics for cancer: similarities and contrasts with traditional drug discovery and development

The field of molecular therapeutics is in its infancy and represents a promising and novel avenue for targeted cancer treatments. Like the small-molecule and antibody therapeutics before them, however, the genetic-based therapies will face significant research and development challenges in their maturation toward an approved cancer therapy. To facilitate this process, we outline and examine in this review the drug development process, briefly summarizing the research and development paradigms that have accompanied the recent successes of the small-molecule and antibody-based cancer therapeutics. Using this background, we compare and contrast the research and development experiences of small-molecule and antibody therapeutics with genetic-based cancer therapeutics, using oncolytic viruses as a defined example of an experimental molecular therapeutic for cancer.

High numbers of tumour-infiltrating activated cytotoxic T lymphocytes, and frequent loss of HLA class I and II expression, are features of aggressive B cell lymphomas of the brain and testis

Loss of both HLA class I and class II expression in B cell lymphomas is a mechanism of escape from a cytotoxic T lymphocyte (CTL) immune response and will therefore give a strong selective survival advantage in tumours expressing strong immunogenic antigens. We investigated loss of HLA expression using specific antibodies on tissue sections from 254 B cell lymphomas originating from nodal and different extranodal sites in relation to numbers of tumour-infiltrating T cells. Complete loss of HLA class I and II was observed in a minority of the nodal, stomach, and skin lymphomas but in the majority of the lymphomas originating from the testis and the CNS. Interestingly, relatively high percentages of activated CTLs were detected in both primary testicular and CNS lymphomas compared to lymphomas at other sites, with highest percentages in the testis (p < 0.0001). We conclude that loss of both HLA class I and II expression occurs very frequently in lymphomas originating from the testis and the CNS as compared to nodal and some other extranodal sites. The presence of high percentages of activated CTLs in the testicular and CNS lymphomas suggests that loss of HLA expression provides a strong growth advantage for lymphoma cells in these immune-privileged sites.

Paraoxonase polymorphism and its effect on male reproductive outcomes among Chinese pesticide factory workers

BACKGROUND

Serum paraoxonase has been associated with the metabolism of organophosphate pesticides in humans. Molecular analysis of the human paraoxonase gene (PON1) has revealed that Arg192 homozygotes have a greater detoxifying capability than Gln192 homozygotes. We examined the effects of PON1 genotypes on male reproductive outcomes and its interaction with exposure to organophosphate pesticides.

METHODS

We studied 60 Chinese pesticide-factory workers and 89 textile-factory workers who were unexposed to pesticides. The respective allele frequencies of Arg192 and Gln192 were 0.62 and 0.38. Pesticide exposure among 36 exposed subjects and 12 unexposed subjects, regardless of gender, was assessed by personal measurement of pesticide residues over an entire 8-hr shift and measurement of urinary p-nitrophenol level over a 24-hr period. We analyzed semen and hormone data collected from male subjects.

RESULTS

When the three PON1 genotypes were analyzed separately, a gene dose effect was not detected. We used the unexposed Arg192 homo/heterozygotes as the reference group, and re-analyzed the data. Exposed Arg192 homo/heterozygotes had significantly lower sperm count (chi 2 = 9.01, P < 0.01) and lower percentage of sperm with normal morphology (chi 2 = 4.18, P < 0.05) than the reference group. Both unexposed Gln192 homozygotes (chi 2 = 4.90, P < 0.05) and exposed Arg192 homo/heterozygotes (chi 2 = 10.00, P < 0.01) showed significantly lower sperm concentrations than the reference group. In addition, exposed Arg192 homo/heterozygotes had significantly higher serum LH levels (chi 2 = 7.94, P < 0.01) than the reference group.

CONCLUSIONS

Because of a small sample size, our findings are highly preliminary. Nevertheless, it calls for further investigation of the interaction between the PON1 genotype and organophosphate pesticide exposure on male reproductive outcomes.