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Statins, inhibitors of HMG CoA reductase, have pleiotropic effects independent of their capacity to lower cholesterol. Heme-oxygenase-1(HO-1) plays an important role as an anti-oxidant and anti-inflammatory enzyme. In the present study, we used NIH 3T3 cells which express HO-1 to investigate the molecular mechanisms of HO-1 induction by statins. Simvastatin or fluvastatin induced a significant increase in HO-1 protein expression and mRNA levels. Both statins stimulated activity of a mouse HO-1 promoter (-1,287 to +73 bp)/luciferase reporter gene, 3.25 ± 0.23 (Mean ± S.E.M., n = 15, P < 0.001, t-test) and 3.13 ± 0.33 (Mean ± S.E.M., n = 6, P < 0.001, t-test), respectively. This effect was more pronounced in the short proximal promoter than the full promoter of HO-1. Gel retardation experiments for C/EBP and upstream stimulatory factor (USF) DNA-binding activities using simvastatin- or fluvastatin-treated cells showed significant nuclear protein-DNA complexes which were supershifted with antibodies specific for C/EBP β and δ or USF-1 and USF-2. Point mutations of the proximal HO-1 promoter (-149 to +73 bp) for the myc/max which binds USF or the C/EBP binding sequences showed a reduction in statin-induced reporter activity whereas no role of the distal C/EBP binding elements located at -4 kb was observed. Moreover, overexpression of mutated C/EBP β and USF factor or the siRNA for both factors supported a role of these transcription factors in statin-dependent induction of HO-1, with a clearer effect for C/EBP.

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ObjectiveTo investigate in a cross-sectional study the effect of serum-derived exosomes on primary human blood monocyte-derived macrophages (MDMs) comparing exosomes from healthy donors vs patients with relapsing-remitting multiple sclerosis in remission and in relapse and to assess whether the response correlates with exosomal Epstein-Barr virus (EBV) protein expression.MethodsA total of 45 serum-derived exosome preparations were isolated from patients and healthy controls and verified for the expression of exosomal and EBV markers. MDMs were differentiated from monocytes for 7 days and incubated for 24 hours with exosomes, and then, cell supernatants were collected for cytokine measurement by cytometric bead array. Cells were immunophenotyped before and after differentiation.ResultsSerum-derived exosomes of patients with multiple sclerosis (MS) expressed higher levels of EBV proteins than healthy controls. Of interest, expression of EBV nuclear antigen EBNA1 and latent membrane proteins LMP1 and 2A was higher on exosomes derived from patients with active RRMS compared with healthy controls and stable patients. After data normalization, we observed that incubation with EBV(+) exosomes induced CXCL10 and CCL2 secretion by MDMs. MDMs differentiated from patients with active disease were better secretors of CXCL10 and other interferon-γ–inducible chemokines, including CCL2 and CXCL9, than MDMs from healthy and stable MS groups. MDMs from active patients had a higher frequency of a CD14(++) subset that correlated with the secreted CXCL10.ConclusionExosomes expressing EBV proteins correlate with disease activity and induce an inflammatory response in MDMs that is compounded by the origin of the responder cells.