Decreased Plasma Myeloperoxidase Associated with Probiotic Therapy in Autistic Children

AIM: To assess plasma myeloperoxidase (MPO) levels in autistic children and to test the hypothesis that there is an association between decreased MPO concentration and probiotic therapy. SUBJECTS AND METHODS: Plasma from 49 autistic children (39 males; mean age 11.4 years) (17 with diagnosed gastrointestinal (GI) disease – chronic diarrhea and/or constipation (10 of these GI patients were taking probiotics) and 26 receiving probiotic therapy) and 36 neurotypical controls (29 males; mean age 10.2 years; controls were not assessed for GI disease) were tested for MPO plasma concentration using Enzyme Linked Immunosorbent Assays (ELISAs). Plasma concentration of MPO in autistic individuals was compared to plasma concentration of copper and zinc. RESULTS: We found that individuals with autism, receiving no therapy, did not have significantly lower plasma MPO levels when compared to controls. In the autistic group, MPO levels were significantly lower in individuals taking probiotic therapy. In addition, plasma copper levels were significantly lower in autistic individuals taking probiotics compared to those not taking probiotics, but plasma zinc levels were not different in the probiotic group. DISCUSSION: These results suggest a relationship between low MPO levels found in a group of autistic individuals and probiotic therapy. By possibly changing gut bacterial flora and thereby changing absorption properties in the gut, probiotic therapy was also associated with lower copper levels.