Abstract
BACKGROUND/AIM: Pulmonary arterial hypertension (PAH) is a severe complication of systemic lupus erythematosus (SLE), marked by vascular remodeling, immune dysregulation, and progressive right heart failure. Molecular hydrogen therapy, a selective antioxidant and anti-inflammatory agent, has the capacity to modulate immune responses in these autoimmune disease patients. This case report details the clinical improvement in an SLE patient with PAH after starting adjunctive hydrogen capsule therapy, highlighting its potential as a novel approach for this challenging complication. CASE REPORT: A 45-year-old Taiwanese woman with SLE-PAH who received hydrogen capsule therapy, during which serial immunophenotyping revealed dynamic changes in T cell exhaustion markers, regulatory T cell (Treg) subsets, and regulatory B cells (Breg). Notably, KLRG1+ T cells and CD39+Helios- Tregs were suppressed during therapy but rebounded after cessation, suggesting transient immune suppressing followed by regulatory rebalancing. Bregs also showed a similar pattern, declining during therapy and recovering after discontinuation. CONCLUSION: These findings suggest a biphasic immunomodulatory effect of hydrogen therapy, that is, initially dampening immune activation, followed by a regulatory rebound after hydrogen therapy.