Washed microbiota transplantation is associated with short-term changes in selected spirometric parameters in...

Gut microbiota may modulate pulmonary inflammation through the gut-lung axis. This study investigated the association between washed microbiota transplantation (WMT) and short-term changes in pulmonary function, inflammatory markers, and gut microbiota in patients with abnormal spirometric patterns. A total of 110 patients who underwent fecal microbiota transplantation, also referred to as WMT, were consecutively screened between March 2023 and January 2025. Of these, 47 patients with paired baseline and post-WMT spirometric data were included in the primary spirometric analysis. According to baseline spirometric patterns, WMT recipients were classified into an abnormal spirometric-pattern group (DG, n = 19) and a normal spirometric-pattern WMT-recipient group (HC, n = 28; HC denotes WMT recipients with normal spirometry rather than healthy community controls). In addition, 43 patients receiving conventional treatment without WMT were included as a non-WMT comparison group (CON). The WMT group underwent multi-course interventions with longitudinal monitoring of pulmonary function parameters, inflammatory markers, breath-holding time (BHT), and 36-Item Short Form Health Survey scores (SF-36). Gut microbiota composition and predicted functional profiles were analyzed using 16S rRNA gene sequencing. After one WMT course, DG patients showed increases in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). Compared with the non-WMT comparison group, the change in FVC was greater in WMT recipients, whereas the between-group difference in FEV1 change was not statistically significant. Other spirometric indices, BHT, inflammatory markers, SF-36 scores, and microbiome-related findings were considered exploratory. Exploratory 16S rRNA gene sequencing identified differences in selected gut microbial taxa between WMT recipients with abnormal and normal spirometric patterns, including differences in Firmicutes, Faecalibacterium, and Alistipes. Predicted functional profiling suggested changes in glycerolipid metabolism-, Nod-like receptor signaling-, and bacterial chemotaxis-related functional potentials. WMT was associated with short-term changes in selected spirometric parameters, particularly FVC and FEV1, in patients with abnormal spirometric patterns. Changes in inflammatory markers, BHT, SF-36 scores, and microbiome-related findings were exploratory and hypothesis-generating. Further randomized, disease-specific studies with standardized pulmonary function testing and mechanistic validation are needed.