Gut dysbiosis-driven butyrate deficiency contributes to renal fibrosis progression, and butyrate supplementation represents a promising therapeutic strategy acting dually by restoring gut barrier integrity and directly suppressing the renal pro-fibrotic TGF-β1/Smad3 pathway via its HDAC inhibitory function.
Key Findings
Results
Both CKD patients and UUO mice exhibited gut dysbiosis characterized by depletion of the butyrate-producing bacterium Faecalibacterium prausnitzii.
Gut microbiota analysis was performed in CKD patients and a unilateral ureteral obstruction (UUO) mouse model
F. prausnitzii is identified as a key butyrate-producer that was specifically depleted in both human and animal subjects
The depletion of F. prausnitzii was associated with systemic butyrate deficiency
Targeted metabolomics was used to confirm butyrate deficiency in these subjects
Results
CKD patients and UUO mice showed compromised gut barrier integrity associated with butyrate deficiency.
Gut barrier function was assessed in both CKD patients and UUO mice
The compromise in gut barrier integrity was linked to the gut dysbiosis and resulting butyrate deficiency
The gut-kidney axis was implicated in the pathophysiology of progressive renal fibrosis
Systemic butyrate deficiency was identified as a consequence of the observed gut dysbiosis
Results
Oral sodium butyrate administration significantly ameliorated renal fibrosis and improved renal injury in UUO mice.
Therapeutic effects were evaluated in vivo using the UUO mouse model
Oral sodium butyrate supplementation was the intervention tested
Butyrate treatment significantly reduced markers of renal fibrosis in treated animals
Renal injury parameters were improved following butyrate administration
Results
Oral sodium butyrate administration restored gut barrier integrity in UUO mice.
Gut barrier integrity was assessed before and after oral sodium butyrate treatment in UUO mice
Butyrate supplementation reversed the gut barrier compromise observed in the UUO model
This finding supports a dual mechanism of action for butyrate in protecting against renal fibrosis
Restoration of gut barrier integrity represents one of two major therapeutic pathways identified for butyrate
Results
Butyrate attenuated TGF-β1-induced fibrotic responses in vitro by inhibiting Smad3 phosphorylation.
In vitro experiments used TGF-β1-stimulated HK-2 renal tubular cells
Butyrate directly inhibited phosphorylation of Smad3, a key mediator of the pro-fibrotic TGF-β1 signaling pathway
This effect on Smad3 phosphorylation was mimicked by a histone deacetylase (HDAC) inhibitor
The HDAC inhibitory function of butyrate was identified as the mechanism underlying its suppression of the TGF-β1/Smad3 pathway
These direct cellular mechanisms were explored separately from the in vivo gut barrier effects
Results
The anti-fibrotic effect of butyrate on the TGF-β1/Smad3 pathway is mediated through its function as a histone deacetylase (HDAC) inhibitor.
An HDAC inhibitor mimicked the effect of butyrate in inhibiting Smad3 phosphorylation in TGF-β1-stimulated HK-2 cells
Butyrate is characterized as an immunomodulatory metabolite with HDAC inhibitory properties
This mechanism represents a direct renal protective action independent of gut barrier restoration
The dual mechanism of butyrate includes both gut barrier restoration and direct HDAC inhibition in renal cells
What This Means
This research suggests that an imbalance in gut bacteria (dysbiosis) plays an important role in the progression of chronic kidney disease (CKD) by reducing levels of a beneficial molecule called butyrate. Butyrate is normally produced by certain gut bacteria, particularly Faecalibacterium prausnitzii, and researchers found that both CKD patients and mice with kidney obstruction had significantly less of this bacterium and lower butyrate levels. This shortage of butyrate was linked to a leakier gut barrier, which may allow harmful substances to pass from the intestines into the bloodstream and worsen kidney damage.
When researchers gave oral sodium butyrate supplements to mice with kidney disease, the treatment reduced kidney scarring (fibrosis), improved kidney function, and repaired the damaged gut barrier. In laboratory experiments using kidney cells, butyrate also directly blocked a key molecular pathway (TGF-β1/Smad3) that drives the formation of scar tissue in the kidneys. This blocking effect appeared to work through butyrate's ability to inhibit enzymes called histone deacetylases (HDACs), which regulate gene activity inside cells.
This research suggests that butyrate works through two complementary mechanisms to protect against kidney fibrosis: repairing the gut barrier to reduce the flow of harmful substances into the body, and directly switching off pro-scarring signals within kidney cells. These findings point to butyrate supplementation as a potential therapeutic approach for slowing kidney disease progression, though further research in human clinical trials would be needed to confirm these benefits in patients.
Liu G, Sun Q, Yan Q, Tang F, Lai L, De Li X. (2026). The immunomodulatory metabolite butyrate ameliorates renal fibrosis by restoring gut barrier integrity and suppressing the TGF-β1/Smad3 pathway.. International immunopharmacology. https://doi.org/10.1016/j.intimp.2026.116557