Microarray analysis of multiple sclerosis (MS) lesions obtained at autopsy revealed increased transcripts of genes encoding inflammatory cytokines, particularly interleukin-6 and -17, interferon-gamma and associated downstream pathways. Comparison of two poles of MS pathology--acute lesions with inflammation versus 'silent' lesions without inflammation--revealed differentially transcribed genes. Some products of these genes were chosen as targets for therapy of experimental autoimmune encephalomyelitis (EAE) in mice. Granulocyte colony-stimulating factor is upregulated in acute, but not in chronic, MS lesions, and the effect on ameliorating EAE is more pronounced in the acute phase, in contrast to knocking out the immunoglobulin Fc receptor common gamma chain where the effect is greatest on chronic disease. These results in EAE corroborate the microarray studies on MS lesions. Large-scale analysis of transcripts in MS lesions elucidates new aspects of pathology and opens possibilities for therapy.

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Summary Collagen (10-40 μg kg−1), thrombin (1-10 units kg−1), adenosine diphosphate (ADP; 3-300 pμ kg−1), 1-0-hexadecyl Paf-acether and 1-0-octadecyl Paf-acether (1-300 ng kg−1) administered by bolus intravenous injection each caused dose-dependent thrombocytopoenia accompanied by marked hypotension in anaesthetized rabbits. Responses to ADP and the Paf-acether derivatives were transient in nature (3-8 min) whereas those induced by collagen and thrombin were always of longer duration (5-20 min) and frequently fatal at high doses. Responses to collagen, thrombin, and the Paf-acether derivatives were invariably accompanied by substantial, dose-related increases in plasma levels of thromboxane B2 in samples obtained 30 s after agonist administration, whereas following ADP, no change in plasma thromboxane B2 was detected at any dose level. Indomethacin (3.0 mg kg−1 by infusion) had no effect on responses to thrombin or Paf-acether, partially inhibited collagen-induced thrombocytopenia, and potentiated responses to ADP. In contrast, dazoxiben (10 mg kg−1 by infusion) partially but significantly inhibited responses to thrombin, whereas those induced by collagen, Paf-acether or ADP were unchanged. These results indicate that in this model of intravascular aggregation, whilst platelet responses to collagen and thrombin appear partially dependent on intact cyclic endoperoxide and thromboxane A2 synthetic capacity respectively, responses to ADP and Paf-acether are independent of arachidonate metabolism via cyclo-oxygenase despite measurably increased TXB2 formation in the latter case.

A series of substituted omega-[2-(1H-imidazol-1-yl)ethoxy]alkanoic acid derivatives were synthesized and evaluated for their ability to inhibit thromboxane synthase both in vitro and in vivo. Compound 13 was identified as a potent and selective competitive inhibitor of human platelet thromboxane synthase having a Ki value of 9.6 X 10(-8) M. In collagen-treated human whole blood, 13 potentiated levels of 6-keto PGF1 alpha. Enantiospecific syntheses afforded the R and S enantiomers of 13, of which the S enantiomer 13b was the more potent. Compounds 13 and 13b were potent in vivo inhibitors of thromboxane synthase with good oral activity and duration of action.