Biomedical subjects
Reiner Thomssen
Publications and source records attributed to Reiner Thomssen.
Oxidative injury to endothelial cells due to Epstein-Barr virus-induced autoantibodies against manganese superoxide dismutase.
During the course of acute Epstein-Barr virus (EBV) infection, there is a rise of oxygen radical production. As a consequence, the production of the oxygen radical scavenger manganese superoxide dismutase (MnSOD) is increased. Patients with acute EBV infections regularly develop autoantibodies against MnSOD that are able to inhibit the enzyme activity in vitro. To elucidate the origin of the autoantibodies, the epitopes on MnSOD were determined. The entire sequence of MnSOD was synthesized as overlapping pentadecapeptides, which were scanned for their reactivity with sera of patients with acute EBV infections. Sera as well as affinity-purified anti-MnSOD antibodies reacted with the peptides p(no15) (amino acids 47-61) and p(no30) (amino acids 122-136) lying in crucial parts of the MnSOD tetramer. The two main epitopes p(no15) and p(no30) showed sequence homologies with EBV-encoded proteins. Reactivity of affinity-purified antibodies with a peptide of the homologous BGLF4 points to a molecular mimicry causing the occurrence of anti-MnSOD antibodies. Anti-MnSOD antibodies were able to block the protective effects of MnSOD in a model for oxidative damage produced by xanthine/xanthine oxidase in EAhy926 endothelial cells. Thus, these autoantibodies may contribute in vivo to the clinical symptoms by accumulation of toxic oxygen radicals.
Virolytic action of lipoprotein lipase on hepatitis C virus in human sera.
In most sera of hepatitis C virus (HCV)-infected patients beta-lipoproteins are bound to HCV RNA-carrying material, most often simultaneously with immunoglobulins (IgG, IgM) and sometimes additionally with high-density lipoproteins, forming complexes of low density (1.04-1.06 g/ml). To separate HCV particles from bound material, we tried to destroy the lipoprotein enzymatically by incubating HCV-positive human sera with lipoprotein lipase derived from Pseudomonas spp. (LPL-Ps). After this treatment, titers of HCV RNA in human sera (determined by a simple semiquantitative reverse transcription-PCR assay) were strongly reduced, regardless of whether primers of the NTR or NS5 region were used. Inactivation of HCV RNA could be inhibited by the addition of RNAguard to the serum-enzyme mixture. The lytic effect of the LPL-Ps preparation could be inhibited by tetrahydrolipstatin. Hence LPL-Ps seems to disrupt the HCV particle structure, including the putative core of the virus, and makes HCV RNA sensitive for RNase present in the reaction mixture. HBV was not destroyed by LPL-Ps. Porcine pancreatic lipase had no effect on HCV. The implications of these observations for the structure and biology of HCV and for its stability and inactivation in human sera are discussed.