A noninvasive cell-based assay for monitoring proteolytic activity within a specific subcellular compartment

Protease-deleted adenovirus as an alternative for replication-competent adenovirus vector

For cancer therapy and vaccination an amplified expression of the therapeutic gene is desired. Previously, we have developed a single-cycle adenovirus vector (SC-AdV) by deleting the adenovirus protease (PS) gene. In order to keep the E1 region intact within the PS-deleted adenoviruses, we examined the insertion of two transgenes under the control of a constitutive or inducible promoters. These were inserted between E4 and the right inverted terminal repeat in a wide variety of backbones with various combinations of PS, E3 and E4 deletion. Our data showed that PS-deleted adenoviruses, expressed transgenes as strongly as replication-competent AdVs in HEK293A and a variant of HeLa cells. In a head-to-head comparison in four human cell lines, we demonstrated that SC-AdV, was comparable for transgene expression efficacy with its replication-competent counterpart. However, the SC-AdV expresses its transgene 10 to 16,000 times higher than its replication-defective counterpart.

Amplification of autoimmune response through induction of dendritic cell maturation in inflamed tissues

Dendritic cells (DCs) are essential in T cell-mediated destruction of insulin-producing beta cells in the islets of Langerhans in type 1 diabetes. In this study, we investigated T cell induction of intra-islet DC maturation during the progression of the disease in both autoimmune-prone NOD and resistant C57BL/6 mice. We demonstrated steady-state capture and retention of unprocessed beta cell-derived proteins by semimature intra-islet DCs in both mouse strains. T cell-mediated intra-islet inflammation induced an increase in CD40 and CD80 expression and processing of captured Ag by resident DCs without inducing the expression of the p40 subunit of IL-12/23. Some of the CD40(high) intra-islet DCs up-regulated CCR7, and a small number of CD40(high) DCs bearing unprocessed islet Ags were detected in the pancreatic lymph nodes in mice with acute intra-islet inflammation, demonstrating that T cell-mediated tissue inflammation augments migration of mature resident DCs to draining lymph nodes. Our results identify an amplification loop during the progression of autoimmune diabetes, in which initial T cell infiltration leads to rapid maturation of intra-islet DCs, their migration to lymph nodes, and expanded priming of more autoreactive T cells. Therapeutic interventions that intercept this process may be effective at halting the progression of type 1 diabetes.

Longitudinal profile of retinal ganglion cell damage after optic nerve crush with blue-light confocal scanning laser ophthalmoscopy

PURPOSE

To investigate the long-term longitudinal profile of retinal ganglion cell (RGC) damage after optic nerve crush with a new technique for in vivo imaging of RGCs.

METHODS

A blue-light confocal scanning laser ophthalmoscope (bCSLO; 460 nm excitation, 490 nm detection) was used to image Thy-1 CFP mice aged 6 to 9 months (n = 5) before optic nerve crush, weekly after crush for 3 weeks, and at weeks 10 and 50 after optic nerve crush. A sham procedure was performed in the contralateral eye, and it was imaged as a control. Corresponding retinal areas before and after optic nerve crush were compared, and the fluorescent spots were counted manually. The longitudinal profile of RGC degeneration was modeled and compared with one-phase and two-phase exponential decay equations.

RESULTS

A significant and progressive loss of fluorescent spots was found after optic nerve crush with 18.6% +/- 2.3%, 11.3% +/- 3.4%, 8.8% +/- 5.3%, 4.2% +/- 3.1%, and 3.3% +/- 2.1% of Thy-1-expressing RGCs remaining at weeks 1, 2, 3, 10, and 50, respectively, after optic nerve crush (P < 0.001; n = 5). There was no change in the fluorescence density in the contralateral control (P = 0.893). Two-phase exponential decay (y = 0.03 + 0.83e(-)(2.78t) + 0.14e(-)(0.30t)) was a better fit than one-phase exponential decay (y = 0.94e(-)(1.93t) + 0.06; P = 0.003) equations, with half-lives of fast phase and slow phase of 1.7 days and 16.3 days, respectively.

CONCLUSIONS

The longitudinal profile of RGC degeneration after optic nerve crush is characterized by a two-phase exponential decay model. bCSLO imaging provides an efficient and noninvasive approach to the longitudinal study of progressive RGC damage.

Intraperitoneal Echinococcus multilocularis infection in C57BL/6 mice affects CD40 and B7 costimulator expression on peritoneal macrophages and impairs peritoneal T cell activation

One of the most important immunopathological consequence of intraperitoneal alveolar echinococcosis (AE) in the mouse is suppression of T cell-mediated immune responses. We investigated whether and how intraperitoneal macrophages (MØs) are, respectively, implicated as antigen-presenting cells (APCs). In a first step we showed that peritoneal MØs from infected mice (AE-MØs) exhibited a reduced ability to present a conventional antigen (chicken ovalbumin, C-Ova) to specific responder lymph node T cells. In a subsequent step, AE-MØs as well as naïve MØs (positive control) proved their ability to uptake and process C-Ova fluorescein isthiocyanate (FITC). Furthermore, in comparison with naïve MØs, the surface expression of Ia molecules was up-regulated on AE-MØs at the early stage of infection, suggesting that AE-MØs provide the first signal via the antigen-Ia complex. To study the accessory activity of MØs, AE-MØs obtained at the early and late stages of infection were found to decrease Con A-induced proliferation of peritoneal naïve T cells as well as of AE-sensitized peritoneal T cells, in contrast to stimulation with naïve MØs. The status of accessory molecules was assessed by analysing the expression level of costimulatory molecules on AE-MØs, with naïve MØs as controls. It was found that B7-1 (CD80) and B7-2 (CD86) expression remained unchanged, whereas CD40 was down-regulated and CD54 (= ICAM-1) was slightly up-regulated. In a leucocyte reaction of AE-MØs with naïve or AE-T cells, both types of T cells increased their proliferative response when CD28 - the ligand of B7 receptors - was exposed to anti-CD28 in cultures. Conversely to naïve MØs, pulsing of AE-MØs with agonistic anti-CD40 did not even partially restore their costimulatory activity and failed to increase naïve or AE-T cell proliferation. Neutralizing anti-B7-1, in combination with anti-B7-2, reduced naïve and AE-T cell proliferation, whereas anti-CD40 treatment of naïve MØs increased their proliferative response to Con A. These results point at the key role of B7 receptors as accessory molecules and the necessity of the integrity of CD40-expression by naïve MØs to improve their accessory activity. Taken together, the obstructed presenting-activity of AE-MØs appeared to trigger an unresponsiveness of T cells, contributing to the suppression of their clonal expansion during the chronic phase of AE-infection.

Optimizing techniques for tracking transplanted stem cells in vivo

The potential for bone marrow-derived cells (BMDCs) to contribute to nonhematopoietic tissues has generated considerable debate in recent years. Causes for the controversies include disparities in the techniques used to track engraftment of BMDCs, inappropriate tissue preparation, a lack of appropriate positive and negative controls, and basic misunderstandings about how to properly collect and interpret images from epifluorescent and confocal microscopes. Our laboratory was among the first to use bone marrow transplants from transgenic mice constitutively expressing enhanced green fluorescent protein (GFP) to study the ability of BMDCs to give rise to nonhematopoietic tissue types, a system that is now in widespread use. During our 6 years of experience using GFP, as well as beta-galactosidase and the Y chromosome, to track BMDCs in vivo, we have identified many difficulties and have developed techniques to resolve them. We discuss several of these methods, and, in particular, we describe ratiometric analysis techniques for improving detection of transplanted cells derived from genetically modified bone marrow. Finally, to help resolve reported discrepancies regarding the frequency with which BMDCs contribute to skeletal myofibers, we demonstrate that the pattern of highly autofluorescent myofibers in skeletal muscle is clearly distinct from that of GFP-expressing myofibers and describe how unambiguous conclusions can be drawn from such data.

Within the cell: analytical techniques for subcellular analysis

This review covers recent developments in the preparation, manipulation, and analyses of subcellular environments. In particular, it highlights approaches for (1) separation and detection of individual organelles, (2) preparation of ultra-pure organelle fractions, and (3) utilization of novel labeling strategies. These approaches, based on innovative technologies such as microfluidics, immunoisolation, mass spectrometry and electrophoresis, suggest that subcellular analyses will soon become as commonplace as single cell and bulk cellular assays.