S-adenosyl-L-methionine (SAMe) halts the autoimmune response in patients with primary biliary cholangitis (PBC) via antioxidant and S-glutathionylation processes in cholangiocytes.

S-adenosyl-L-methionine is an endogenous molecule with hepato-protective properties linked to redox regulation and methylation. Here, the potential therapeutic value of SAMe was tested in 17 patients with PBC, a cholestatic disease with autoimmune phenomena targeting small bile ducts. Nine patients responded to SAMe (SAMe responders) with increased serum protein S-glutathionylation. That posttranslational protein modification was associated with reduction of serum anti-mitochondrial autoantibodies (AMA-M2) titers and improvement of liver biochemistry. Clinically, SAMe responders were younger at diagnosis, had longer duration of the disease and lower level of serum S-glutathionylated proteins at entry. SAMe treatment was associated with negative correlation between protein S-glutathionylation and TNFα. Furthermore, AMA-M2 titers correlated positively with INFγ and FGF-19 while negatively with TGFß. Additionally, cirrhotic PBC livers showed reduced levels of glutathionylated proteins, glutaredoxine-1 (Grx-1) and GSH synthase (GS). The effect of SAMe was also analyzed in vitro. In human cholangiocytes overexpressing miR-506, which induces PBC-like features, SAMe increased total protein S-glutathionylation and the level of γ-glutamylcysteine ligase (GCLC), whereas reduced Grx-1 level. Moreover, SAMe protected primary human cholangiocytes against mitochondrial oxidative stress induced by tBHQ (tert-Butylhydroquinone) via raising the level of Nrf2 and HO-1. Finally, SAMe reduced apoptosis (cleaved-caspase3) and PDC-E2 (antigen responsible of the AMA-M2) induced experimentally by glycochenodeoxycholic acid (GCDC). These data suggest that SAMe may inhibit autoimmune events in patients with PBC via its antioxidant and S-glutathionylation properties. These findings provide new insights into the molecular events promoting progression of PBC and suggest potential therapeutic application of SAMe in PBC.

The effect of the nitroxide pirolin on oxidative stress induced by doxorubicin and taxanes in the rat brain.

The anticancer drugs doxorubicin (DOX), paclitaxel (PTX) and docetaxel (DTX) have been proven to induce oxidative stress (OS)-dependent side-effects in non-targeted tissues. In normal conditions, the blood-brain barrier (BBB) prevents these drugs from penetrating into the brain. However, some studies have demonstrated that small amounts of DOX can penetrate the brain via an oxidatively impaired BBB and cause damage, which suggests that including antioxidants in chemotherapy could possibly protect the brain against the toxicity of anticancer drugs. We investigated whether DOX, DTX and PTX can induce oxidative damage in rat brains in vivo and whether inclusion of the nitroxyl antioxidant Pirolin (PL) to DOX/taxane chemotherapy can protect the brain from the OS toxicity of these drugs. Wistar rats received i.p. a single dose (10 mg/kg b.w.) of DOX, DTX, PTX or PL alone or a combination of a drug + PL. After four days, the rats were anesthetized, the brains were excised, homogenized and used for the measurements of lipid peroxidation (LPO), thiol groups, activities of antioxidant enzymes, DNA damage and tumor necrosis factor-α (TNF-α), neuronal nitric oxide synthase (nNOS) and poly (ADP-ribose) polymerase-1 (PARP-1) expression. The results were analyzed using the Kruskal-Wallis and Conover-Inman tests or ANOVA and the Tukey-Kramer test. Doxorubicin, PTX and DTX induced OS, DNA damage and changes in expression of TNF-α, nNOS and PARP-1 in the rat brain. Pirolin alone increased LPO, manganese superoxide dismutase (MnSOD) and catalase (CAT) activities and the expression of PARP-1 but decreased TNF-α expression. PL, in combination with anticancer drugs, partially protected the rat brain against the toxic effects of DOX and taxanes. The best protective effects of PL were obtained with PTX. Pirolin partially attenuated brain damage caused by DOX/taxanes, highlighting its potential application in protecting the brain against DOX-, DTX- and PTX-evoked OS.

The effect of Pycnogenol on the erythrocyte membrane fluidity.

In the present study, the in vitro effect of polyphenol rich plant extract, flavonoid--Pycnogenol (Pyc), on erythrocyte membrane fluidity was studied. Membrane fluidity was determined using 1-[4-trimethyl-aminophenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH), 1,6-diphenyl-1,3,5-hexatriene (DPH) and 12-(9-anthroyloxy) stearic acid (12-AS) fluorescence anisotropy. After Pyc action (50 microg/ml to 300 microg/ml), we observed decreases in the anisotropy values of TMA-DPH and DPH in a dose-dependent manner compared with the untreated erythrocyte membranes. Pyc significantly increased the membrane fluidity predominantly at the membrane surface. Further, we observed the protective effect of Pyc against lipid peroxidation, TBARP generation and oxidative hemolysis induced by H2O2. Pyc can reduce the lipid peroxidation and oxidative hemolysis either by quenching free radicals or by chelating metal ions, or by both. The exact mechanism(s) of the positive effect of Pyc is not known. We assume that Pyc efficacy to modify effectively some membrane dependent processes is related not only to the chemical action of Pyc but also to its ability to interact directly with cell membranes and/or penetrate the membrane thus inducing modification of the lipid bilayer and lipid-protein interactions.