Restoration of the human skin microbiome following immune recovery after hematopoietic stem cell transplantation.

The human skin microbiome is intricately intertwined with host immunity. While studies have elucidated microbial influences on immunity, understanding how immune alterations modulate this equilibrium remains limited. We investigated the dual impact of immune deficiency and hematopoietic stem cell transplantation (HSCT) on the skin microbiome in 24 patients with dedicator of cytokinesis 8 (DOCK8) deficiency, a rare inborn error of immunity. Analyzing 590 metagenomic and 534 16S rDNA sequencing samples across eight skin sites, we observed disrupted microbiota pre-HSCT (median eukaryotic viruses 67.6% vs. 0.04% in controls), with extremely diverse human papillomaviruses (HPVs) and polyomaviruses-including oncogenic viruses. Specific bacterial species markedly changed, including decreased Staphylococcus aureus post-HSCT. DNA eukaryotic viruses dramatically decreased (79.7% ± 28.3% to 4.9% ± 8.6%; p < 0.01) 12 months post-HSCT. Recovered microbial communities remained relatively stable through 1-year follow-up with clearance of oncogenic HPV and no convergence with transplant donors. These results highlight the immune system's critical role in restoring microbial balance and skin health.