Novel immune function for the TRPV1 channel in T lymphocytes

TRPM3 has been reported to play an important role in Ca²⁺ homeostasis, but its gating mechanisms and regulation via Ca²⁺ are unknown. Ca²⁺ binding proteins such as calmodulin (CaM) could be probable modulators of this ion channel. We have shown that this protein binds to two independent domains, A35-K124 and H291-G382 on the TRPM3 N-terminus, which contain conserved hydrophobic as well as positively charged residues in specific positions, and that these residues have a crucial impact on its binding. We also showed that another Ca²⁺ binding protein, S100A1, is able to bind to these regions and that CaM and S100A1 compete for these binding sites on the TRPM3 N-terminus. Moreover, our results suggest that another very important TRP channel activity modulator, PtdIns(4,5)P₂, interacts with the CaM/S100A1 binding sites on the TRPM3 N-terminus with high affinity.     

Modulation of GvHD by suicide-gene transduced donor T lymphocytes: clinical applications in mismatched transplantation

In allogeneic hematopoietic cell transplantation (allo-HCT), donor lymphocytes play a central therapeutic role in both GvL and immune reconstitution. However, the full exploitation of these therapeutic properties is limited by the occurrence of GvHD. Different strategies have been investigated to obtain all the benefits derived from donor lymphocytes while avoiding the risk of GvHD. The genetic engineering of donor lymphocytes with the herpes simplex virus-thymidine kinase (HSV-TK) suicide gene confers the ability to modulate GvHD by invivo ganciclovir-induced elimination of the transduced cells. The suicide-gene strategy has applications in both donor lymphocyte infusion (DLI) for disease relapse and in add-back infusions after T-cell depleted allo-HCT. TK cell DLI resulted in anti-tumor activity in a relevant proportion of treated patients. Haplo-identical stem cell transplantation (haplo-HCT) is a promising therapeutic option for patients with high risk hematologic malignancies lacking an HLA-matched donor. However, the profound T-cell depletion required to overcome the risk of lethal GvHD has been associated with a marked delayed T-cell recovery with a prolonged risk of post-transplant viral, fungal and other opportunistic infections. TK cell add-backs efficiently promote early immune reconstitution after haplo-HCT and prevent disease relapse, providing a unique tool for the control of GvHD. The genetic manipulation of donor lymphocytes with a suicide gene is a promising strategy to increase feasibility and safety of allo-HCT.     

Regulatory function of T lymphocytes in the immune response to polyvinyl pyrrolidone. I. Two categories of suppressor T cells.

The regulation of antibody response of mice to polyvinyl pyrrolidone (PVP) was investigated using three preparations of PVP (K90, K30, and K15) differing from each other in molecular weight. The immunogenicity of PVP was higher as the molecular weight increased. The depletion of thymus-derived cells resulted in the augmentation of anti-PVP response. On the other hand, the response of intact mice to the most immunogenic PVP (K90) was suppressed more or less by the injection of any preparation of PVP 4 days prior to K90. This was most pronounced when the smallest PVP (K15) was preinjected. The suppression, however, was not observed in thymectomized-irradiated-bone marrow reconstituted mice.These results indicated that anti-PVP response was regulated by two different categories of thymus-derived cells, that is, “intrinsic” and “induced” suppressor cells. The activity of the latter was transferrable, PVP-specific, and eliminated by anti-Thy 1 serum and complement. In addition, the mean affinity of anti-PVP plaque-forming antibodies was found to be reduced by the action of “induced” suppressor cells.     

Characterization of the spreading process in human T lymphocytes

Substratum-bound concanavalin A (conA) caused attachment and spreading of human T lymphocytes identified by monoclonal anti-T cell antibodies and sheep erythrocyte rosette formation. The simultaneous presence of conA in the medium increased the spreading, whereas preincubation of the cells with conA inhibited spreading. The tendency of conA to induce spreading was dependent on the concentration used, the higher the conA concentration the more pronounced was the spreading. For example, conA at 10 micrograms ml-1 triggered the formation of prominent substratum-attached filopodia with a length of 1-10 micron in 60-80% of T-enriched lymphocytes obtained from separate individuals. At the same conA dose the filopodia were, in 10-20% of the lymphocytes, accompanied by development of lamellipodia. With conA at 100 micrograms ml-1 the number of cells that underwent pronounced spreading was 55-90% in separate individuals. Observation of T-enriched cells fixed at different times after initiation of spreading induced by conA at 100 micrograms ml-1 indicated that filopodia formation represented the initial morphological alteration during the spreading process. This process thereafter proceeded with development of lamellipodia, extensive cytoplasmic spreading and flattening of the central cell mass. Quiescent and mitogen-activated cells exhibited the same sequence of changes during spreading. Spreading led to disappearance of the microvilli with a length of 0.1-0.7 micron present on lymphocytes in suspension, although some microvilli persisted over the cell center.     

Streamlined design of a self-inactivating feline immunodeficiency virus vector for transducing ex vivo dendritic cells and T lymphocytes

Background

Enterovirus 71 (EV71) is a major causative viral agent responsible for large outbreaks of hand, foot and mouth disease (HFMD), a common rash illness in children and infants. There is no effective antiviral treatment for severe EV71 infections and no vaccine is available. The objectives of this study were to design and construct a DNA vaccine against Enterovirus 71 using the viral capsid protein (VP1) gene of EV71 and to verify the functionality of the DNA vaccine in vitro and in vivo.

Methods

The VP1 gene of EV71 from two local outbreak isolates were amplified using PCR and then inserted into a eukaryotic expression vector, pVAX1. The 3.9 kb recombinant constructs were transformed into competent E. coli cells and the positive clones were screened and selected using PCR analysis, restriction digestion analysis and DNA sequencing. The constructs were then tested for protein expression in Vero cells. Subsequently, in the in vivo studies, female Balb/c mice were immunized with the DNA vaccine constructs. Enzyme Linked Immunosorbent Assay (ELISA) and virus neutralizing assay were performed to detect the presence of anti-VP1 IgG in mice and its neutralizing effect against the EV71.

Results

The pVAX1 vector was successfully cloned with the VP1 gene from each of the isolate (S2/86/1 and 410/4) in the correct orientation and in-frame. The DNA vaccine constructs with the VP1 gene were shown to be expressed in a cell-free in vitro expression system. The VP1 protein was successfully expressed in the mammalian cell line and was detected using RT-PCR, Indirect Immunofluorescence Assay (IFA) and western blotting. The anti-VP1 IgG levels in mice immunized with the DNA vaccine constructs increased after the first booster but declined following the second booster. The anti-VP1 IgG in the mice immunized with the DNA vaccine constructs exhibited neutralising activity against EV71.

Conclusion

The promising results obtained in the present study have prompted further testing to improve the expression and immunogenicity of this potential EV71 DNA vaccine.     

Dehydroepiandrosterone restores immune function following trauma-haemorrhage by a direct effect on T lymphocytes.

Although a profound depression in immune function occurs following injury, the mechanism responsible for this is not fully understood. Furthermore, steroid hormones are known to be important mediators in the regulation of immune function. Although dehydroepiandrosterone (DHEA), the most plentiful steroid hormone, has been shown to stimulate immune function in normal animals, it is unknown whether DHEA has any salutary or detrimental effects on immune responses after trauma and haemorrhage. To study this, male mice were subjected to trauma, haemorrhage and resuscitation, following which they received either DHEA or vehicle subcutaneously. DHEA administration restored the normally depressed splenocyte proliferation as well as interleukin 2, interleukin 3, and interferon gamma elaboration following trauma and haemorrhage. In an attempt to determine the mechanisms mediating this effect, T cells were stimulated in vitro in the presence of DHEA and a variety of hormone antagonists. The stimulatory effect of DHEA on splenocyte proliferation was unaltered by the testosterone receptor antagonist flutamide, while the oestrogen antagonist tamoxifen completely abrogated its effect. In addition, DHEA administration normalized the elevated serum corticosterone level typically seen following injury. These results indicate, therefore, that DHEA improves splenocyte function after trauma and haemorrhage by directly stimulating T cells and also by preventing a rise in serum corticosterone.     

Lentiviral and MLV based retroviral vectors for ex vivo and in vivo gene transfer

Retroviral vectors have become an important tool for gene transfer in vitro and in vivo. Classical Moloney murine leukemia virus (MLV) based retroviral vectors have been used for over 20 years to transfer genes into dividing cells. Cell lines for production of retroviral vectors have become commonly available and modifications in retroviral vector design and use of envelope proteins have made the production of high titer, helper-free, infectious virus stocks relatively easy. More recently, lentiviral vectors, another class of retroviruses, have been modified for in vitro and in vivo gene transfer. The ability of lentiviral vectors to transduce non-dividing cells has made them especially attractive for in vivo gene transfer into differentiated, non-dividing tissues. Several improvements in helper plasmids and vectors have made lentivirus a safe vector system for ex vivo and in vivo gene transfer. This review will briefly summarize the background of these vector systems and provide some common protocols available for the preparation of MLV based retroviral vectors and HIV-1 based lentiviral vectors.     

Simulated-physiological loading conditions preserve biological and mechanical properties of caprine lumbar intervertebral discs in ex vivo culture

Low-back pain (LBP) is a common medical complaint and associated with high societal costs. Degeneration of the intervertebral disc (IVD) is assumed to be an important causal factor of LBP. IVDs are continuously mechanically loaded and both positive and negative effects have been attributed to different loading conditions.In order to study mechanical loading effects, degeneration-associated processes and/or potential regenerative therapies in IVDs, it is imperative to maintain the IVDs' structural integrity. While in vivo models provide comprehensive insight in IVD biology, an accompanying organ culture model can focus on a single factor, such as loading and may serve as a prescreening model to reduce life animal testing. In the current study we examined the feasibility of organ culture of caprine lumbar discs, with the hypothesis that a simulated-physiological load will optimally preserve IVD properties.Lumbar caprine IVDs (n = 175) were cultured in a bioreactor up to 21 days either without load, low dynamic load (LDL), or with simulated-physiological load (SPL). IVD stiffness was calculated from measurements of IVD loading and displacement. IVD nucleus, inner- and outer annulus were assessed for cell viability, cell density and gene expression. The extracellular matrix (ECM) was analyzed for water, glycosaminoglycan and total collagen content.IVD biomechanical properties did not change significantly with loading conditions. With SPL, cell viability, cell density and gene expression were preserved up to 21 days. Both unloaded and LDL resulted in decreased cell viability, cell density and significant changes in gene expression, yet no differences in ECM content were observed in any group.In conclusion, simulated-physiological loading preserved the native properties of caprine IVDs during a 21-day culture period. The characterization of caprine IVD response to culture in the LDCS under SPL conditions paves the way for controlled analysis of degeneration- and regeneration-associated processes in the future.     

Serum enhances the ex vivo generation of HIV-specific cytotoxic T cells

The ex vivo expansion of antigen-specific cytotoxic T lymphocyte (CTL) lines is being developed for immunotherapy of viral infections and cancer and is critically dependent on the precise cell expansion and stimulation conditions. In this article, we investigate medium requirements for the development of HIV-specific CTL in cell lines generated from the peripheral blood of seven asymptomatic HIV-infected individuals. We find that HIV-specific CTL do not readily develop in the serum-free medium AIM V but do develop if the medium is supplemented with 1% plasma or serum. T cell lines with antigen-specific cytolytic activity express more cell-surface CD57 than do cell lines grown in the absence of serum or plasma. Three sources of serum (human autologous, human AB, or fetal calf) are comparable. Human plasma is somewhat less effective than serum from an identical source. (c) 1996 John Wiley & Sons, Inc.     

Adoptive transfer of murine autoimmune orchitis to naive recipients with immune lymphocytes

A protocol was developed for reproducibly transferring experimental autoimmune orchitis (EAO) to naive recipient mice. Cell donors were (C57BL/6 x A/J)F1 mice immunized about 14 days earlier with mouse testicular homogenate with Freund's adjuvant and an extract of Bordetella pertussis. Lymphocytes from lymph nodes and spleens were equally capable of transferring disease. As few as 5 X 10(6) cells were able to transfer EAO, which began on Day 5-7 after transfer. Infiltrate of lymphocytes and macrophages in the region of the rete testis and straight tubules was the most reproducible early lesion, suggesting that this is the initial site of T cell-antigen interaction. It was not necessary to use both Mycobacteria and B. pertussis adjuvants in donor immunization to achieve transfer of EAO. Disease transfer was antigen specific since only cells from donors immunized with TH could transfer disease. In vitro stimulation of the cells with testicular antigens and/or concanavalin A was a prerequisite to successful transfer of EAO, which was dependent on the presence of L3T4+ T cells since depletion of these cells greatly diminished EAO in recipients and the lymphocyte proliferation response to testicular antigens. Disease did not depend on an antibody response by the recipients. The results imply that effector cells, once generated by immunization and fully activated or selected by in vitro stimulation, can home to specific locations in the testis, locate relevant autoantigens, and cause disease.     

Adoptive immunotherapy of advanced tumors with CD62 L-selectin(low) tumor-sensitized T lymphocytes following ex vivo hyperexpansion

Tumor-draining lymph nodes (TDLN) contain sensitized T cells with the phenotype CD62 L-selectin(low) (CD62L(low)) that can be activated ex vivo with anti-CD3 mAb and IL-2 to acquire potent dose-dependent effector function manifested upon adoptive transfer to secondary tumor-bearing hosts. In this study advanced tumor models were used as a stringent comparison of efficacy for the CD62L(low) subset, comprising 5-7% of the TDLN cells, vs the total population of TDLN cells following culture in high dose IL-2 (100 U/ml). During the 9-day activation period the total number of CD8+ T cells increased 1500-fold, with equivalent proliferation in the CD62L(low) vs the total TDLN cell cultures. Adoptive transfer of activated CD62L(low) cells eliminated 14-day pulmonary metastases and cured 10-day s.c. tumors, whereas transfer of maximally tolerated numbers of total TDLN cells was not therapeutic. Despite their propagation in a high concentration of IL-2, the hyperexpanded CD62L(low) subset of TDLN cells functioned in vivo without exogenous IL-2, and CD8+ T cells demonstrated relative helper independence. Moreover, the anti-tumor response was specific for the sensitizing tumor, and long term memory was established. The facile enrichment of tumor-reactive TDLN T cells, based on the CD62L(low) phenotype, circumvents the need for prior knowledge of the relevant tumor Ags. Coupling the isolation of pre-effector T cells with rapid ex vivo expansion to >3 logs could overcome some of the shortcomings of active immunotherapy or in vivo cytokine treatment, where selective robust expansion of effector cells has been difficult to achieve.