Immune-mediated Recognition Research Articles

Minicircle DNA-based Gene Therapy Coupled With Immune Modulation Permits Long-term Expression of α-L-Iduronidase in Mice With Mucopolysaccharidosis Type I

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disease characterized by mutations to the α-L-iduronidase (IDUA) gene resulting in inactivation of the IDUA enzyme. The loss of IDUA protein results in the progressive accumulation of glycosaminoglycans within the lysosomes resulting in severe, multi-organ system pathology. Gene replacement strategies have relied on the use of viral or nonviral gene delivery systems. Drawbacks to these include laborious production procedures, poor efficacy due to plasmid-borne gene silencing, and the risk of insertional mutagenesis. This report demonstrates the efficacy of a nonintegrating, minicircle (MC) DNA vector that is resistant to epigenetic gene silencing in vivo. To achieve sustained expression of the immunogenic IDUA protein we investigated the use of a tissue-specific promoter in conjunction with microRNA target sequences. The inclusion of microRNA target sequences resulted in a slight improvement in long-term expression compared to their absence. However, immune modulation by costimulatory blockade was required and permitted for IDUA expression in MPS I mice that resulted in the biochemical correction of pathology in all of the organs analyzed. MC gene delivery combined with costimulatory pathway blockade maximizes safety, efficacy, and sustained gene expression and is a new approach in the treatment of lysosomal storage disease.

Adoptive cell therapy of prostate cancer using female mice-derived T cells that react with prostate antigens

In this study, we report a novel treatment strategy that could potentially be used to improve efficacy of adoptive cell therapy for patients with prostate cancer. We show that female C57BL/6 mice are able to effectively reject two syngeneic prostate tumors (TRAMP-C2 and RM1) in a T cell-dependent manner. The protective antitumor immunity appears to primarily involve T cell responses reactive against general prostate tumor/tissue antigens, rather than simply to male-specific H-Y antigen. For the first time we show that adoptive transfer of lymphocytes from TRAMP-C2-primed or naïve female mice effectively control prostate tumor growth in male mice, when combined with host pre-conditioning (i.e., non-myeloablative lymphodepletion) and IL-2 administration. No pathological autoimmune response was observed in the treated tumor-bearing male mice. Our studies provide new insights regarding the immune-mediated recognition of male-specific tissue, such as the prostate, and may offer new immunotherapy treatment strategies for advanced prostate cancer.

Leukocyte Infiltration in Cancer Creates an Unfavorable Environment for Antitumor Immune Responses: A Novel Target for Therapeutic Intervention

The interaction between tumor cells and the nearby environment is being actively investigated to explore how this interplay affects the initiation and progression of cancer. Host-tumor relationship results in the production of pro-inflammatory cytokines and chemokines that promote the recruitment of leukocytes within and around developing neoplasms. Cancer cells, together with newly recruited tumor-infiltrating cells, can also activate fibroblast and vascular responses, thus resulting in a chronic microenvironment perturbation. In this complex scenario, interactions between innate and adaptive immune cells can be disturbed, leading to a failure of immune-mediated tumor recognition and destruction. On the basis of the recent awareness about tumor promotion and immune deregulation by immune/inflammatory cells, novel anti-cancer strategies can be exploited.

Retrovirus-Transduced T Cell Blasts Have Not Only Antigen-Presenting Capabilities but Also Suppressor Regulatory T Cell-Inducing Capability.

EBV-associated T/NK-lymphoproliferative diseases (LPD) are relatively rare but their prognosis is very poor. In order to understand the pathogenesis and rationalize immunotherapy, it is important to know whether EBV-infected T/NK cells have antigen-presenting capacities and how they escape the EBV-specific immunity that controls virus-infected B cells and epithelial cells. As a model for T cell antigen presenting cells (T-APC), we used activated T cells expressing pp65, the immunodominant antigen of CMV, after retroviral transduction. Two to three days after activation with CD3/28, T cells were transduced with retrovirus supernatants for 24h to 48 hr on retronectin-coated plates, and then expanded for one to two weeks with IL-2 before use as APCs or target cells. As control APCs, we used LCLs transduced with a retrovirus vector expressing pp65 (pp65-LCL). Pp65-expressing T cells functioned as target cells, since they were readily killed by pp65-specific cytotoxic T cells (CTL), reactivated using Adenovirus-pp65-pulsed dendritic cells. Furthermore, pp65T-APCs could reactivate pp65-specific CD8+ CTL from autologous PBMC. However, the pp65T-APC could not sustain prolonged pp65-specific CTL expansion. The ratio of CD4+: CD8+ T cells increased in responders after the 2nd stimulation with pp65-T-APC, and after the 3rd stimulation, the CD8+ CTL had virtually disappeared so that most of live cells were CD4+ T cells. The majority of the CD4+ T cells co-expressed CD25, the glucocoticoid-induced TNF receptor (GITR) and intracellular antigen CD152, all markers of T regulatory cells. To determine if they had regulatory function, the CD4+CD25+ population was isolated and shown to inhibit the proliferation of autologous PBMCs stimulated by pp65-LCL. In contrast, the CD4+CD25− fraction did not inhibit proliferation. Transwell experiments revealed that the inhibition required cell-to-cell contact. CFSE analysis showed that the CD4+CD25+ cells expanded while inhibiting the proliferation of stimulated PBMC. Taken together, these findings indicated that T-APC could reactivate antigen specific CD8+ CTL, but at the same time they activated regulatory CD4+ T cells, which prevented the long-term expansion of the CD8+ CTL. Similar results were found when the LMP2 antigen of EBV, which is expressed in T/NK-LPD, was used as antigen. Thus the immune escape of EBV-associated T/NK-LPD might result in part from their induction of regulatory T cells which inhibit T cell-specific CTL generation and function. T cells in general may evade immune-mediated recognition of their “novel” T cell receptors in the same way.

Emerging roles of endothelial cells and smooth muscle cells in transplant vascular disease

The lesion-promoting events and processes involved in the pathogenesis of transplant vascular disease (TVD) are intimately dependent on the interactions of both endothelial cells (EC) and smooth muscle cells (SMC) in the vessel wall of solid organ allografts. Immune-mediated recognition and injury of the endothelial cell layer provide the stimulus for the elaboration of EC-derived cytokines and chemokines, and the upregulation of adhesion molecule expression involved in increased leukocyte recruitment and attachment, altered vascular permeability to lipids and cells, stimulation of SMC migration and proliferation, and activation of apoptosis. T cells and macrophages, subsequent to activation and transendothelial migration, further amplify the concentration of soluble mediators in the allograft microenvironment and, together with activated EC, provide a chemokine gradient leading to SMC migration from the media and subsequent proliferation and extracellular matrix synthesis in the neointimal space. The combination of altered EC permeability and SMC matrix synthesis provides a mechanism for lipoprotein insudation and retention, respectively, in the developing lesion. Such lipid accumulation can lead to oxidative modifications that are potentially proatherogenic. Oxidized lowdensity lipoprotein can contribute to further lipid retention, cell proliferation, foam cell formation, and cell death. Nitric oxide derived from vascular cells is also emerging as an important mediator of atherogenesis and may have both antiatherogenic and proatherogenic capabilities. Thus, the activation, injury, or destruction of ECs and SMCs leads to the expansion of a lipid-, SMC-, and matrix-rich intimai lesion, loss of normal vascular function, and the compromise of allograft viability and performance.

The role of the immune system in anti-tumour responses. Potential for drug therapy.

In the last 5 years significant progress has been made in our understanding of the molecular nature of anti-tumour T cell-mediated responses. This review describes the involvement of the cellular immune system in the recognition and destruction of cancer cells. Four aspects are discussed: (i) the generalized immune activation induced by the systemic administration of cytokines, in particular, interleukin-2; (ii) the specific T cell-mediated reactions against tumour cells through the recognition of tumour-associated molecules, 1) and tyrosinase proteins described in melanomas, and minor histocompatibility antigens in the setting of allogenic bone marrow transplantation for leukaemia; (iii) the potentially significant but still hypothetical immune-mediated recognition of molecules either tumour-associated or transformation-related (including altered oncogenic proteins); and (iv) the role of co-stimulatory molecules in the induction of tumour-specific immunity. The current and future therapeutic applications in cancer treatment and potential limitations in this approach are discussed.

Basis of tetracaine-induced inhibition of phagocytosis by cultured mouse peritoneal macrophages

The inhibition of mouse peritoneal macrophage phagocytosis by the tertiary amine anesthetic, tetracaine, was studied in vitro. By investigating separately the recognition and ingestion phases of phagocytosis using 51Cr-labeled sheep red blood cells (SRBC), the following observations were made. First, immune-mediated recognition of the SRBC via the opsonizing mouse immunoglobulin by the macrophages is inhibited by tetracaine. Second, non-immune recognition of unopsonized SRBC is not inhibited by tetracaine. Third, ingestion of the opsonized SRBC is inhibited by tetracaine to a greater extent than unopsonized SRBC. Fourth, the basis for the inhibition of recognition appears to be steric, probably related to anesthetic-induced clustering of receptors on the macrophage surface. Fifth, the results are discussed in terms of transmembrane control of macrophage receptors.