Altered M1/M2 activation patterns of monocytes in severe relapsing experimental rat model of multiple sclerosis. Amelioration of clinical status by M2 activated monocyte administration.

OBJECTIVES: We investigated proinflammatory M1 and immunomodulatory M2 activation profiles of circulating monocytes in relapsing experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis, and tested whether altered M1/M2 equilibrium promotes CNS inflammation. RESULTS: Approaches of MRI macrophage tracking with USPIO nanoparticles and expression patterns of M1/M2 macrophages and microglia in brain and M1/M2 monocytes in blood samples at various disease stages revealed that M1/M2 equilibrium in blood and CNS favors mild EAE, while imbalance towards M1 promotes relapsing EAE. We consequently investigated whether M2 activated monocyte restoration in peripheral blood could cure acute clinical EAE disease. Administration of ex vivo activated M2 monocytes both suppressed ongoing severe EAE and increased immunomodulatory expression pattern in lesions, confirming their role in the induction of recovery. CONCLUSION: We conclude that imbalance of monocyte activation profiles and impaired M2 expression, are key factors in development of relapses. Our study opens new perspectives for therapeutic applications in MS.

Predicting drug response based on gene expression.

Predicting drug response is a challenging problem in oncology. In the 1975-1985 decade, important efforts were devoted to the generation of cellular assays able to predict, on an individual basis, the in vitro response of tumour cells to chemotherapeutic agents, but such methods could not be adopted in routine. Numerous mechanisms of resistance to anticancer agents have been identified in cultured cell lines selected for growth in the presence of infratoxic, increasing doses of anticancer agents. They mainly concern drug transport, drug activation or detoxification, target quantitative or qualitative alterations, DNA repair efficiency, and alterations in signalling and/or execution of cell death programmes. New molecular biology techniques have been developed in order to identify the genes involved in drug resistance; they mainly involve differential expression techniques, but functional approaches may also prove informative. The availability of techniques of gene expression profiling has allowed to establish correlations between gene expression and drug sensitivity of tumour cells or human cancers. This type of approach has been initiated on in vitro systems by the National Cancer Institute (NCI) in the USA and is pursued by a growing number of public and private laboratories around the world. In the clinical setting, a number of genes or proteins have been identified as potential predictive markers of drug activity and their use could be progressively implemented for drug selection in patients receiving chemotherapy, allowing thus more rational and individualised treatments.

Molecular determinants of the cytotoxicity of platinum compounds: the contribution of in silico research.

Gene expression profiling of tumors allows the establishment of relationships between gene expression profiles and sensitivity to anticancer drugs. In an attempt to study the molecular determinants of the activity of platinum compounds, we explored the publicly available databases of the National Cancer Institute (NCI; http://dtp.nci.nih.gov), which allow access to the gene expression profiles of the 60 cell lines for which drug cytotoxicity patterns already existed. Using this database, we have conducted an in silico research to identify the genes the expression of which was positively or negatively correlated to the sensitivity to four platinum compounds (cisplatin, carboplatin, oxaliplatin and tetraplatin). Important similarities were noticed between cisplatin and carboplatin on one hand, and tetraplatin and oxaliplatin on the other hand. In the restricted panel of 1416 genes and molecular markers, we identified 204 markers, among which 120 corresponded to identified genes, that significantly correlated (P < 0.001) with the cytotoxicity of at least one platinum compound. For example, the functionality of the p53-activated pathway appeared positively correlated with the cytotoxicity of all platinum compounds. More specific are the positive correlations between RAS gene mutations and MYC expression and the cellular sensitivity to oxaliplatin. Among the parameters already known as related to the sensitivity to platinum compounds, we identified, in the complete set of 9400 genes, numerous significant relationships, such as the negative correlations between ERB-B2 and BCL-X(L) expressions and the cytotoxicity of the platinum compounds. Public databases mining, therefore, appears to be a valuable tool for the identification of determinants of anticancer drug activity in tumors.

Comparison of antisense oligonucleotides and siRNAs in cell culture and in vivo.

Efficiencies of a nuclease resistant antisense oligonucleotide and of siRNA both being targeted against the green fluorescent protein stably expressed in HeLa cells are compared in cell cultures and in xenografted mice. Using Cytofectin GSV to deliver both inhibitors, the siRNAs appear to be quantitatively more efficient and its effect is lasting for a longer time in cell culture. In mice, we observed an activity of siRNAs but not of antisense oligonucleotides. The absence of efficiency of antisense oligonucleotides is probably due to their lower resistance to nuclease degradation.