Superoxide release in human fibroblasts upon treatment with culture supernatants of the arthritogenic bacteria Erysipelothrix rhusiopathiae and Mycoplasma arthritidis

Abstract

Culture supernatants of the arthritogenic bacteria Mycoplasma pneumonia, Mycoplasma arthritidis, Borrelia burgdorferi and Erysipelothrix rhusiopathiae stimulated primary cultures of human fibroblasts to release reactive oxygen species into the environment, whereas cell walls and membranes of these bacteria had no effects. Lipopolysaccharides of various gram-negative bacteria and lipid A, the lipid moiety of endotoxines, also failed to stimulate the release of reactive oxygen species by fibroblasts. The stimulatory fractions of the culture supernatants of Mycoplasma arthritidis and Erysipelothrix rhusiopathiae exhibited a molecular weight of about 9.5 kDa. After an induction period of 5 min the presence of the stimulant was not necessary any more. The primary radical released by the fibroblasts was the superoxide anion O2. Radical formation took place continuously over some hours. Additionally, low-level chemiluminescence of fibroblasts was increased upon stimulation with culture supernatants of Mycoplasma arthritidis and Erysipelothrix rhusiopathiae. No irreversible injury of the fibroblast was caused upon stimulation and the cells exhibited normal proliferation pattern after replacing them to the culture medium.