Evolutionary origins of the placental expression of chromosome 19 cluster galectins and their complex dysregulation in preeclampsia

INTRODUCTION

The dysregulation of maternal-fetal immune tolerance is one of the proposed mechanisms leading to preeclampsia. Galectins are key regulator proteins of the immune response in vertebrates and maternal-fetal immune tolerance in eutherian mammals. Previously we found that three genes in a Chr19 cluster encoding for human placental galectin-13 (PP13), galectin-14 and galectin-16 emerged during primate evolution and may confer immune tolerance to the semi-allogeneic fetus.

MATERIALS AND METHODS

This study involved various methodologies for gene and protein expression profiling, genomic DNA methylation analyses, functional assays on differentiating trophoblasts including gene silencing, luciferase reporter and methylation assays. These methods were applied on placental specimens, umbilical cord blood cells, primary trophoblasts and BeWo cells. Genomic DNA sequences were analyzed for transposable elements, transcription factor binding sites and evolutionary conservation.

RESULTS AND DISCUSSION

The villous trophoblastic expression of Chr19 cluster galectin genes is developmentally regulated by DNA methylation and induced by key transcription factors of villous placental development during trophoblast fusion and differentiation. This latter mechanism arose via the co-option of binding sites for these transcription factors through promoter evolution and the insertion of an anthropoid-specific L1PREC2 transposable element into the 5' untranslated region of an ancestral gene followed by gene duplication events. Among placental Chr19 cluster galectin genes, the expression of LGALS13 and LGALS14 is down-regulated in preterm severe preeclampsia associated with SGA. We reveal that this phenomenon is partly originated from the dysregulated expression of key transcription factors controlling trophoblastic functions and galectin gene expression. In addition, the differential DNA methylation of these genes was also observed in preterm preeclampsia irrespective of SGA.

CONCLUSIONS

These findings reveal the evolutionary origins of the placental expression of Chr19 cluster galectins. The complex dysregulation of these genes in preeclampsia may alter immune tolerance mechanisms at the maternal-fetal interface.

Enhanced tumor cures after Foscan photodynamic therapy combined with the ceramide analog LCL29. Evidence from mouse squamous cell carcinomas for sphingolipids as biomarkers of treatment response

To improve anticancer therapeutic success of photodynamic therapy (PDT), combination treatments represent a viable strategy. Sphingolipid analogs combined with anticancer drugs can enhance tumor response. We have shown that LCL29, a C6-pyridinium ceramide, promotes therapeutic efficacy of Photofrin-PDT in mouse SCCVII squamous cell carcinoma tumors. The long-term effect of the combination PDT + LCL29 is unknown. In this study we used the same model to test the long-term curative potential of Foscan-PDT + LCL29. We show that treatment of SCCVII tumors with the combination led to enhanced long-term tumor cure compared to PDT alone. LCL29 itself did not prevent tumor growth. All treatments triggered early increases in tumor-associated C16-ceramide, C18-ceramide, dihydrosphingosine, and global levels of dihydroceramides. PDT-evoked increases in tumor-associated sphingosine-1-phosphate and dihydrosphingosine-1-phosphate remained elevated or were attenuated after the combination, respectively; in contrast, LCL29 had no effect on these two sphingolipids. Our data demonstrate that adjuvant LCL29 improves PDT long-term therapeutic efficacy, implying translational potential of the combination. Furthermore, our findings indicate that changes in the sphingolipid profile might serve as predictive biomarkers of tumor response to treatments.

Cellular immune responses in human neurocysticercosis

Studies on the role of cell-mediated immune responses in human neurocysticercosis (NCC) are lacking. Various cell-mediated immune responses such as lymphocyte subpopulation, lymphocyte transformation to cysticercus antigens and cytokine profile were carried out in NCC patients. Lymphocyte transformation assays using larval antigens showed significantly higher (3)H-thymidine uptake. Immunophenotyping analysis showed an insignificant increase in B cells and a decrease in total T cells. However, there was a significant decrease (P < 0.05) in CD8+ T cells whereas there was no change in other cells like CD4+, HLA-DR+ and CD16+/CD56+. Cytokine profile revealed significantly higher (P < 0.01) production of Th1 cytokines (gamma-IFN and IL-2) using cysticercal antigens as stimulants for peripheral blood mononuclear cells, while there was no difference in IL-4 levels between NCC patients and healthy controls. The cytokine profile indicated the involvement of Th-1-like responses in NCC patients.

Kinetics of humoral & cellular immune responses in experimental cysticercosis in pigs infected with Taenia solium

Studies were undertaken to assess the kinetics of antibody responses, lymphocyte transformation to Taenia solium larval antigens (crude soluble extract antigen and antigen B), and T cell subpopulation in piglets following experimental infection. Cysticercosis was established in 1-2 month old piglets after feeding 5,00,000 T. solium eggs per pig. The anti-CD4 and anti-CD8 monoclonal antibodies against swine T cells were raised indigenously. It was observed that at 60 days post infection (PI) there was a significant increase (P < 0.01) in CD4+ T cells without any change in CD8+ T cells. Increased 3H-thymidine uptake was found in infected piglets at 45 days PI using both CSE and antigen B. Kinetics of antibody responses indicated significant increase (P < 0.01) at 15 days PI (with CSE antigen) and 30 days PI (with antigen B) by ELISA. This increase persisted till 90 days PI (the time up to which the animals were followed). It was also observed that the cellular mechanisms were triggered in late stage (60 days PI) as compared to humoral responses (15-30 days PI) and may persist longer as seen by both lymphocyte transformation and T cell subpopulation studies. The study suggests that in cysticercosis, both humoral and cellular mechanisms may play a role in the host defences.

Quantitative estimation of suppressor/cytotoxic and helper T cells during acute and chronic Plasmodium berghei infection

In the present study, the percentage of lymphocyte subpopulations and their relation to T cell subsets was estimated during acute and chronic Plasmodium berghei malaria. During acute infection, a decreased percentage of T lymphocytes was observed, whereas no change was observed during chronic infection. However, no change in the percentage of B cells was observed in both types of infection. The T cell population was characterized by an increased percentage of T suppressor cytotoxic (CD8+) cells and a decreased percentage of T helper cells (CD4+) during acute infection. This resulted in an inversion of the CD8+/CD4+ cell ratio. During chronic infection no change in the CD8+ cell percentage was observed; however some increase in CD4+ cell percentage was observed in later stages. Thus failure of the immune system to overcome acute infection may be due to an increase in T suppressor cells, and maintenance of parasites at subpatent levels during chronic infection may involve the normal CD8+/CD4+ cell ratio with some increase in CD4+ cells.