The redox state of the lung cancer microenvironment depends on the levels of thioredoxin expressed by tumor cells and affects tumor progression and response to prooxidants.

Here we report that human nonsmall cell lung carcinomas overexpress macrophage migration inhibitory factor (MIF) and thioredoxin (Trx), 2 oxidoreductases with cytokine function, and contain more abundant nonprotein thiols (glutathione and cysteine) than nonneoplastic lung tissues. Cell clones derived from the same lung carcinoma cell lines but expressing different levels of Trx and/or MIF displayed growth rates in vitro and in vivo correlating with Trx but not with MIF. Interestingly, the different clones generate extracellularly reduced nonprotein thiols, in amounts related to the Trx content and inhibited by inhibitors of Trx function. Each clone also showed distinct responses to the prooxidant compound arsenic trioxide. Cells with a strongly antioxidant and aggressive phenotype were more susceptible to the cytotoxic effect of the drug than cells expressing little Trx. The latter counteracted the oxidative stress by increasing Trx expression and thiol release. Together these results indicate that different human lung cancer cell lines have distinct redox properties defined by the levels of Trx and nonprotein thiols, the higher antioxidant phenotype correlating with the higher aggressiveness. Moreover, the redox phenotype dictates their response to prooxidant drugs and must be taken into account when therapeutic interventions with redox active substances are considered.

TTF-1/NKX2.1 up-regulates the in vivo transcription of nestin.

TTF-1/NKX2.1, also known as T/EBP, is a homeodomain-containing gene involved in the organogenesis of the thyroid gland, lung and ventral forebrain. We have already reported that in 3T3 cells, TTF-1/NKX2.1 up-regulates the transcription of nestin, an intermediate filament protein expressed in multipotent neuroepithelial cells, by direct DNA-binding to a HRE/CRE-like site (NestBS) within a CNS-specific enhancer. Here, we demonstrate that TTF-1/NKX2.1 is co-expressed with nestin in the embryonal forebrain. We also performed a transgenic mouse embryo analysis in which NestBS was replaced by the canonical TTF-1/NKX2.1 consensus DNA-binding site (as identified in many thyroid- and lung-specific genes and very divergent from NestBS) or a random mutation. We observed beta-galactosidase expression in forebrain regions where TTF-1/NKX2.1 is expressed in wild-type embryos, and -to a minor extent- in rostralmost telencephalic regions and thalamus, whereas no beta-galactosidase expression was detected in forebrains of embryos bearing the random mutation. These data show that TTF-1/NKX2.1 regulates the transcription of the nestin gene in vivo through the NestBS site, suggesting that nestin might be at least one of the effectors of TTF-1/NKX2.1 during forebrain development. Finally, we have shown that the transactivating effect of TTF-1/NKX2.1 on the CNS-specific enhancer is unaffected by Retinoic Acid Receptor-alpha.

Stem cells in inflammatory demyelinating disorders: a dual role for immunosuppression and neuroprotection.

In recent years much excitement has been generated over the possibility that adult stem cells may attempt repair of the injured central nervous system (CNS), thus setting the stage for their utilisation in the treatment of neurodegenerative disorders. Recent studies have shown that some subsets of stem cells can also modulate the (auto)immune response, thus providing a rationale for their use as therapy for experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis (MS). This article reviews the scientific evidence supporting the possible use of neural stem cells (NSCs) and mesenchymal stem cells (MSCs) for the treatment of MS. In addition, possible mechanisms sustaining the beneficial mode of action of haematopoietic stem cells (HSCs) following transplantation in MS individuals are discussed. Overall, it is proposed that limited subsets of adult stem cells may have a dual function that may be effective for the treatment of MS, an autoimmune disease of the CNS where degeneration of neural cells follows inflammation.

Mesenchymal stem cells ameliorate experimental autoimmune encephalomyelitis inducing T-cell anergy.

We studied the immunoregulatory features of murine mesenchymal stem cells (MSCs) in vitro and in vivo. MSCs inhibited T-cell receptor (TCR)-dependent and -independent proliferation but did not induce apoptosis on T cells. Such inhibition was paired with a decreased interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha production and was partially reversed by interleukin-2 (IL-2). Thus, we used MSCs to treat myelin oligodendrocyte glycoprotein (MOG)35-55-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6J mice. We injected intravenously 1 x 10(6) MSCs before disease onset (preventive protocol) and at different time points after disease occurrence (therapeutic protocol). MSC administration before disease onset strikingly ameliorated EAE. The therapeutic scheme was effective when MSCs were administered at disease onset and at the peak of disease but not after disease stabilization. Central nervous system (CNS) pathology showed decreased inflammatory infiltrates and demyelination in mice that received transplants of MSCs. T-cell response to MOG and mitogens from MSC-treated mice was inhibited and restored by IL-2 administration. Upon MSC transfection with the enhanced green fluorescent protein (eGFP), eGFP(+) cells were detected in the lymphoid organs of treated mice. These data suggest that the immunoregulatory properties of MSCs effectively interfere with the autoimmune attack in the course of EAE inducing an in vivo state of T-cell unresponsiveness occurring within secondary lymphoid organs.

Recapitulation of B cell differentiation in the central nervous system of patients with multiple sclerosis.

Clonally expanded populations of B cells carrying somatic mutations of Ig variable (V) region genes have been detected in the CNS of subjects with multiple sclerosis (MS), suggesting that a process of B cell affinity maturation with ensuing production of potentially pathogenic autoantibodies may occur inside the CNS. Here, we have characterized the B cell subsets present in the cerebrospinal fluid (CSF) of MS patients and of individuals with other inflammatory neurological disorders by flow cytometry. CD19(+)CD38(high+)CD77(+), Ki67(+), Bcl-2(-) centroblasts, i.e., a B cell subset found exclusively in secondary lymphoid organs, were detected in the CSF but not in paired peripheral blood from both patient groups. CD27(+)IgD(-) memory B cells, i.e., cells with hyper-mutated IgV genes, were significantly increased in the CSF vs. paired peripheral blood and displayed up-regulation of the CD80 and CD86 costimulatory molecules and of CC chemokine receptor (CCR) 1, CCR2, and CCR4 in both patient groups. Lymphotoxin-alpha, CXC ligand (CXCL) 12, and CXCL13, key mediators of lymphoid neogenesis, were present in the CSF from patients with MS and other inflammatory neurological disorders and were expressed in MS brain tissue, with selective localization in the outer layer of the capillary vessel wall. In conclusion, this study suggests that a compartmentalized B cell response occurs within the CNS during an ongoing inflammatory reaction, through a recapitulation of all stages of B cell differentiation observed in secondary lymphoid organs. The presence of lymphotoxin-alpha, CXCL12, and CXCL13 in the CNS may provide favorable microenvironmental conditions for these events.