An integrated study of gut microbiota and serum metabolites in T2DM-ED rats after fecal microbiota transplantation

Erectile dysfunction (ED) is a highly prevalent and refractory complication of type 2 diabetes mellitus (T2DM), with penile cavernosal dysfunction, inflammation, apoptosis, and fibrosis as core pathological features. Here we identify gut microbiota dysbiosis and its downstream metabolite arachidonic acid (AA) as critical mediators of T2DM-associated erectile dysfunction (T2DM-ED) through a systemic gut-penis axis. Gut dysbiosis is sufficient to induce an ED phenotype, as demonstrated by fecal microbiota transplantation (FMT) from T2DM-ED rats into pseudo-germ-free recipients, which successfully transferred the erectile impairment with significantly decreased ICP/MAP ratios. Recipient rats showed impaired colonic barrier integrity, mucosal damage, goblet cell depletion, and downregulated tight junction proteins (Occludin, Claudin-4). Multi-omics integration of 16S rRNA sequencing and serum metabolomics identified AA as a key elevated metabolite that drives inflammatory signaling via the HIF-1α and NF-κB pathways. In penile corpus cavernosum tissue, ED-FMT rats displayed smooth muscle loss, fibrosis, increased apoptosis, and hyperactivation of the TLR4—MyD88—NF-κB—HIF-1α axis. In primary corpus cavernosum smooth muscle cells (CCSMCs), AA stimulation recapitulated pathological activation, including a pro-apoptotic shift in the Bax/Bcl-2 ratio, elevated Cleaved Caspase-3, reduced α-SMA, increased COX-2, stabilized HIF-1α, and excessive PGE 2 production; these effects were abolished by pharmacological inhibition of NF-κB. Mechanistically, gut dysbiosis-induced systemic AA accumulation triggers inflammatory damage, apoptosis, and functional impairment in penile smooth muscle via the TLR4—MyD88—NF-κB/HIF-1α cascade. These findings define a gut—AA—NF-κB—penis axis that drives T2DM-ED pathogenesis, highlighting AA and its downstream signaling as promising therapeutic targets for diabetic erectile dysfunction. Establishes Causal Evidence for a Gut-Penis Axis This study provides direct experimental evidence via fecal microbiota transplantation (FMT) that gut dysbiosis from type 2 diabetic erectile dysfunction (T2DM-ED) rats is sufficient to induce ED in recipient animals, confirming a causal “gut-penis axis” in T2DM-ED pathogenesis. 1. Integrates Multi-omics to Identify a Key Mediator Using integrated 16S rRNA sequencing and broad-targeted serum metabolomics, we identified prominent pro-inflammatory metabolic disturbances in ED-FMT rats and recognized arachidonic acid (AA) as a critical microbiota-dependent metabolite driving systemic inflammation. 2. Elucidates a Novel Mechanistic Pathway from Gut to Penis We define a complete pathogenic cascade: impaired intestinal barrier → elevated circulating AA → activation of the TLR4-MyD88-NF-κB-HIF-1α axis in cavernosal smooth muscle cells → COX-2/PGE2 overproduction → enhanced apoptosis and phenotypic dysfunction. This pathway was fully validated in vivo, in vitro, and further confirmed by bioinformatic analysis of human T2DM-ED cavernosal datasets from the GEO database. 3. Reveals Translational Potential for T2DM-ED Therapy AA-induced inflammation and apoptosis were markedly reversed by NF-κB inhibition, highlighting the AA-TLR4-MyD88-NF-κB-PGE 2 axis as a promising therapeutic target. Our findings also support serum AA and PGE 2 as candidate biomarkers for clinical translation in T2DM-ED.