Salivary antioxidant capacity in graft versus host disease

Stem cell transplantation (SCT)-related salivary gland injury and dysfunction result in local and systemic manifestations that may be long lasting and are associated with a high rate of morbidity and increased risk of infection. The salivary antioxidant system may have a major protective role. We, therefore, assessed salivary antioxidant capacity and function in 30 patients who had undergone SCT: 18 males and 12 females whose median age was 36 years (range: 7-58). Salivary gland function was assessed by sialometric and biochemistry means, which included measuring total protein, secretory IgA (SIgA) and the antioxidants peroxidase, uric acid (UA), and total antioxidant status (TAS) in the collected saliva. In patients who developed graft versus host disease (GVHD), we observed a significant decrease of the salivary flow rate, from 0.74 +/- 0.14 ml/minute to 0.19 +/- 0.08 ml/min, pre- and post-SCT, respectively (p < 0.01) with no recovery. In contrast, in patients who underwent autologous or allogeneic SCT and did not develop GVHD, salivary flow rates returned to normal 3-5 months posttransplantation. GVHD also resulted in a concomitant reduction of the salivary protein content and the salivary antioxidant capacity. The TAS levels in the saliva of the GVHD patients were found to be significantly reduced, to about one-third of the base-line value (P < 0.02). The concomitant reduction in salivary flow rate, protein content, and antioxidant capacity may well explain the GVHD-induced oral and gastrointestinal tract (GIT) mucositis, as the saliva constantly swallowed into the GIT losses its usual antioxidant protective roles. In conclusion, our findings may point at a possible new mechanism for the pathogenesis of oral and intestinal mucositis in pre-GVHD patients. Therapy with artificial saliva and free radical scavengers and/or antioxidants (administered either systemically or via oral rinses) thus, may be of clinical relevance.