This Special Issue will explore the interplay between hydrogen metabolism and the human microbiome, focusing on how microbial hydrogen production influences immune modulation, inflammation regulation, and gut health. The scope of the issue will include both foundational research on microbial hydrogenases and applied studies on hydrogen’s therapeutic potential for immune-related conditions, metabolic disorders, and gut-brain axis communication. By investigating the biochemical and physiological roles of hydrogen in microbial communities, this issue will offer new insights into microbial ecology, immune homeostasis, and clinical applications in disease management. The issue could be explored:

• How hydrogen affects gut microbiota composition and diversity
• The impact of microbial hydrogen production on immune modulation
• The role of hydrogen in maintaining gut barrier integrity and reducing inflammation
• Therapeutic applications of hydrogen in gut health and immune regulation
• The mechanisms by which hydrogen-producing gut microbes regulate immune responses
• The potential of microbial-derived hydrogen as a novel anti-inflammatory agent
• The role of gut microbiota in hydrogen production and immune regulation
• Hydrogen's effects on innate and adaptive immunity through microbial pathways
• Hydrogen as an antioxidant and its role in reducing inflammation via microbial metabolites
• The gut-liver and gut-brain axes: Hydrogen's role in systemic immune responses
• Potential therapeutic applications of hydrogen and microbial interactions in disease