Enhanced recruitment of genetically modified CX3CR1-positive human T cells into Fractalkine/CX3CL1 expressing tumors: Importance of the chemokine gradient

Background: Adoptive T-cell based immunotherapies constitute a promising approach to treat cancer, however, a major problem is to obtain effective and long-lasting anti-tumor responses. Lack of response may be due to insufficient trafficking of specific T cells to tumors. A key requirement for efficient migration of cytotoxic T cells is that they express chemokine receptors that match the chemokines produced by tumor or tumor-associated cells. Methods: In this study, we investigated whether the in vivo tumor trafficking of activated T cells could be enhanced by the expression of the chemokine receptor CX3CR1. Two human colorectal cancer cell lines were used to set up a xenograft tumor model in immunodeficient mice; the NCI-H630, constitutively expressing the chemokine ligand CX3CL1 (Fractalkine), and the RKO cell line, transduced to express CX3CL1. Results: Human primary T cells were transduced with the receptor CX3CR1-eGFP. Upon in vivo adoptive transfer of genetically modified CX3CR1-T cells in mice bearing NCI-H630 tumors, enhanced lymphocyte migration and tumor trafficking were observed, compared to mice receiving Mock-T cells, indicating improved homing ability towards ligand-expressing tumor cells. Furthermore, significant inhibition of tumor growth was found in mice receiving modified CX3CR1-T cells. In contrast, tumors formed by RKO cells transduced with the ligand (RKO-CX3CL1) were not affected, nor more infiltrated upon transfer of CX3CR1-T lymphocytes, likely because high levels of the chemokine were shed by tumor cells in the systemic circulation, thus nullifying the blood-tissue chemokine gradient. Conclusions: This study demonstrates that ectopic express

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Papillary Carcinoma of the Thyroid : Hepatocyte Growth Factor (HGF) Stimulates Tumor Cells to Release Chemokines Active in Recruiting Dendritic Cells

Tissue distribution of dendritic cells was investigated in eight cases of papillary carcinoma of the thyroid using immunohistochemistry. Most dendritic cells had an immature phenotype (CD1a++, CD11c+, CD40+, CD86−, HLA-DR−) and were located at the invasion edge of the tumor. This pattern of distribution was profoundly different from that of CD68+ macrophages, which were evenly distributed throughout the tumor. The ability of tumor cells to release chemotactic factors active on dendritic cells was investigated in primary cultures of the same cases of papillary carcinoma, and was compared to that of the corresponding normal thyroid cells obtained from the tumor-free contralateral lobe. Chemotactic activity of culture supernatants was tested against dendritic cells in a chemotaxis chamber. It was found that papillary carcinoma cells were active in releasing chemotactic activity, that hepatocyte growth factor (HGF; 100 ng/ml) or interleukin (IL)-1β (103 U/ml) induced a fourfold increase in the amount of chemotactic activity released, and that normal thyroid cells obtained from the same patients were as effective as tumor cells. Characterization of chemokines at RNA level revealed that unstimulated cells contain large amounts of IL-8 and monocyte chemotactic protein (MCP)-1 RNAs, and that stimulation with HGF or IL-1β induced RNAs for regulated upon activation normal T expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-3α, interferon-γ-inducible protein 10 (IP-10), and, to a lesser extent, MIP-1α and MIP-1β. The possibility that HGF/Met interaction has a biological role in vivo was investigated in serial sections of six tumors immunostained for CD1a+, Met protein, and HGF. It was found that all six tumors were intensely and diffusely positive for Met protein, that HGF staining was present in tumor cells of the advancing edge, and that HGF+/Met+ tumor cell nests were infiltrated by CD1a+ dendritic cells. The foregoing observations are consistent with the possibility that HGF stimulation of Met+ tumor cells is one of the molecular mechanisms involved in the recruitment of dendritic cells

Differential Expression and Regulation of Toll-Like Receptors (TLR) in Human Leukocytes: Selective Expression of TLR3 in Dendritic Cells

Members of the Toll-like receptor (TLR) family probably play a fundamental role in pathogen recognition and activation of innate immunity, The present study used a systematic approach to analyze how different human leukocyte populations express specific transcripts for the first five characterized TLR family members. TLR1 was expressed in all leukocytes examined, including monocytes, polymorphonuclear leukocytes, T and B cells, and NK cells. In contrast TLR2, TLR4, and TLR5 were expressed in myelomonocytic elements, Exposure to bacterial products, such as LPS or lipoarabinomannan, or to proinflammatory cytokines increased TLR4 expression in monocytes and polymorphonuclear leukocytes, whereas IL-IO blocked this effect, TLR3 was only expressed in human dendritic cells (DC) wherein maturation induced by bacterial products or cytokines was associated with reduced expression. TLR3 mRNA expression was detected by in situ hybridization in DC and lymph nodes. These results demonstrate that TLR1 through TLR5 mRNAs are differentially expressed and regulated in human leukocytes. In particular, expression of TLR3 transcripts is restricted to DC that are the only elements which express the full TLR repertoire. These data suggest that TLR can be classified based on expression pattern as ubiquitous (TLR1), restricted (TLK2, TLR4, and TLR5 in myelomonocytic cells), and specific (TLR3 in DC) molecules