Inulin-linked postoperative nutrition accompanies improved colonic healing in mice

In a two-experiment study of female mice, postoperative exclusive enteral nutrition supplemented with inulin was associated with stronger colonic anastomoses and improved recovery after lipopolysaccharide-induced inflammatory priming. The intervention also coincided with changes in microbial communities and short-chain fatty acids, but the experiments were not designed to establish that either microbes or metabolites caused the observed healing outcomes. After surgery, inulin was associated with 12.08 kPa higher anastomotic burst pressure at postoperative day 5, while LPS was associated with 8.86 kPa lower pressure compared with the relevant factorial contrasts.

Histological assessments, inflammatory-cell staining, proliferation and apoptosis measurements, and recovery scores were also consistent with better early tissue repair in animals receiving the supplemented formula. These observations describe associations in an animal model rather than a proven effect of inulin in people, and several design limitations constrain interpretation. The researchers conducted two independent animal studies and did not pool their data.

The first compared control and LPS-primed mice through postoperative day 14, using different animals at each scheduled sampling point to characterize microbiota and tissue-transcription changes. The second used the 2 × 2 factorial design described above. A dedicated longitudinal cohort included 10 mice per group and was followed for survival, body weight, and recovery through day 5.

A separate terminal cohort was enrolled sequentially to obtain six day-5 survivors per group for burst-pressure testing, histology, and immunofluorescence analyses. Because mice that died or reached a humane endpoint were unavailable for these terminal measurements, the day-5 tissue results are survivor analyses and may be affected by survivorship bias. All animals were eight-week-old female C57BL/6J mice weighing 18–20 grams.

The researchers selected females for consistency with pilot experiments and related murine work and to reduce intermale aggression, but this restriction limits generalizability to males. Each mouse received a sublethal intraperitoneal injection of 2 mg/kg LPS or sterile saline 24 hours before surgery. Surgeons then performed a standardized distal-colon transection and end-to-end anastomosis using interrupted 9–0 nylon sutures.

Group assignment used a random-number table, surgical order was interleaved across groups, and outcome assessors and image quantifiers were blinded to group labels. Postoperative samples were processed in one batch. The LPS model represents acute systemic inflammatory priming rather than the full range of factors that can contribute to anastomotic leakage in patients, including obstruction, ischemia, fecal contamination, malnutrition, inflammatory bowel disease, and neoadjuvant treatment.

In LPS-primed mice, early postoperative deterioration was followed by multiple signs of impaired repair. Histological maturation was delayed, with impaired mucosal continuity during days 3–7 and persistent structural abnormalities at day 14. Masson’s trichrome staining showed reduced and disorganized collagen deposition.

Protein measurements also showed lower TGF-β, a lower phosphorylated-Akt-to-total-Akt ratio, and lower Bcl-2 in the LPS group. These associations within the inflammatory model do not show that one molecular pathway was responsible for reduced mechanical strength. RNA sequencing of 41 independently collected anastomotic-tissue samples showed changes in host programs associated with the transition from inflammation to regeneration.

Control tissues shifted toward cell adhesion, collagen-containing extracellular-matrix organization, cell migration, extracellular-matrix–receptor interaction, and TGF-β signaling. LPS-primed tissues instead showed enrichment of cytokine–cytokine receptor pathways early after surgery and, by day 5, prominent leukocyte-trafficking and inflammatory-signaling programs, including JAK–STAT and MAPK pathways, alongside lower representation of PI3K–Akt and cell-adhesion programs. Quantitative polymerase chain reaction confirmed unusual cytokine trajectories: IL-6, tumor necrosis factor-alpha, and IL-1 were lower during the initial phase but exceeded control levels by day 7, while IL-10 rose at day 7.

This pattern was consistent with delayed resolution of inflammation, although the later samples represented surviving animals and might also reflect survivor bias. The microbial results indicated that inflammatory stress did not produce a uniform change throughout the gastrointestinal tract. Community structure was strongly associated with anatomical niche, accounting for 29.1% of the variation in the global analysis.

Within anastomotic tissue, colonic contents, and cecal contents, postoperative succession followed different trajectories in LPS and control animals, with the greatest separation occurring around day 5. During the early postoperative period, LPS-primed animals had higher relative abundances of taxa including Enterococcus, Escherichia–Shigella, Klebsiella, and Proteus, together with lower relative abundances of Akkermansia, Dubosiella, and Lactobacillus. Scanning electron microscopy and fluorescence in situ hybridization also showed focal bacterial clustering near sutures and necrotic debris in LPS-primed wounds.

The imaging demonstrated bacterial localization and aggregation, however, not viable species-specific biofilm formation, and the relative sequencing data could not establish absolute bacterial loads because no absolute-load measurements were performed. Postoperative inulin-supplemented nutrition was associated with several recovery and tissue-repair measures. In the factorial analysis, inulin increased day-5 anastomotic burst pressure by 12.08 kPa, with a 95% confidence interval of 7.47–16.70 kPa.

Hematoxylin-and-eosin findings and healing scores were consistent with improved repair, while MPO and CD45 staining showed lower inflammatory infiltration. Multiplex fluorescence imaging indicated a higher CD206-positive-to-CD86-positive marker ratio in the LPS-plus-inulin group than in the LPS group. The investigators described this as a repair- and inflammation-associated marker profile rather than evidence for discrete macrophage-polarization states.

Ki67 measurements showed a main effect of inulin on proliferation-associated staining, while TUNEL staining showed an LPS-by-inulin interaction, including lower apoptosis-associated positivity in LPS-primed mice receiving inulin. Whole-tissue iNOS abundance increased with inulin in the LPS background, showing that the treatment-associated molecular profile was not uniformly anti-inflammatory across every marker. Recovery outcomes were favorable but did not establish a specific survival benefit.

The global four-group survival comparison was marginal, with a log-rank p value of 0.0499, but the prespecified LPS-plus-inulin versus LPS comparison was not significant after Holm correction. Its estimated hazard ratio was 0.162, with a wide 95% confidence interval of 0.019–1.391. Body weight showed a significant LPS-by-inulin-by-time interaction, including a 26.44-percentage-point day-5 advantage for LPS-plus-inulin over LPS, and inulin was associated with a mean reduction of 0.564 points in the Murine Sepsis Score.

These findings support better recovery measures in the model but do not demonstrate that inulin prevented death. The tissue endpoints also require caution because formula intake was not recorded, pair-feeding and viscosity- or osmolality-matched controls were absent, and the numbers of animals per assay were limited. Microbial and metabolite measurements changed alongside the healing outcomes.

At day 5, overall community structure differed across the four groups, and inulin had a negative main effect on Shannon diversity, with an estimate of −1.129 and a 95% confidence interval of −1.693 to −0.566. Neither the LPS effect nor the interaction was significant for diversity. In colonic contents, inulin was associated with an acetate increase of 6.64 mmol/L and a butyrate increase of 4.56 mmol/L, while LPS was associated with an acetate decrease of 4.06 mmol/L. The LPS-plus-inulin group had 6.96 mmol/L more acetate than the LPS group after Tukey adjustment, but its butyrate comparison was not significant.

Sequencing-based functional predictions from PICRUSt2 represented inferred genetic potential rather than measured microbial activity, and the analysis lacked negative extraction and PCR controls, dedicated contaminant filtering, preintervention microbiome measurements, and comprehensive control for cage effects. Overall, the experiments identify an association between brief postoperative inulin supplementation and better early colonic repair after systemic inflammatory priming. The intervention coincided with greater mechanical strength, improved recovery measures, reduced inflammatory infiltration, higher proliferation-associated staining, lower apoptosis-associated staining in the LPS background, altered microbial relative abundance, and higher acetate.

It did not establish that microbiota remodeling or short-chain fatty acids mediated the outcomes, and higher burst pressure occurred despite a lower collagen-positive fraction within the measured granulation-tissue region, leaving the structural mechanism unresolved. The female-only mouse model, standardized LPS challenge, unrecorded formula intake, survivor-based terminal analyses, and limited microbial controls make the findings hypothesis-generating. Determining whether inulin acts through the microbiome, acetate, butyrate, or another mechanism would require direct perturbation and mediation experiments in more clinically representative models.

Subject of Research: Mouse study of postoperative inulin-supplemented enteral nutrition, gut microbiota, short-chain fatty acids, and colonic anastomotic healing after inflammatory priming

Article Title: Postoperative inulin supplementation is associated with microbiota remodeling and improved colonic anastomotic healing in LPS-primed mice

Article References: Shen, Y., Zhao, J., Gan, H., Wu, L., Hu, X., Wang, J., He, Z., Yao, F., Tao, W., Shang, J., Chen, Y., Wang, C., & Wang, G. (2026). Postoperative inulin supplementation is associated with microbiota remodeling and improved colonic anastomotic healing in LPS-primed mice. Frontiers in Microbiology, 17, Article 1895439. https://doi.org/10.3389/fmicb.2026.1895439

Image Credits: AI Generated

DOI: 10.3389/fmicb.2026.1895439

Keywords: inulin, colonic anastomosis, gut microbiota, short-chain fatty acids, dietary fiber, inflammatory priming, wound healing, enteral nutrition, mouse model, Postoperative, supplementation, associated