Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: DPP4 expression is upregulated in intestinal fibro-stenotic areas of CD patients. (A) Volcano plot showing differentially expressed genes (DEGs) between stenotic (B2) and non-stenotic (B1) CD tissues ( GSE66207 dataset). Red dots indicate DEGs with |log2FC| >1 and p < 0.05. (B, C) Hub genes identified using the MCODE and CytoHubba plugins, respectively. (D) RT-qPCR analysis of DPP4 mRNA levels in intestinal tissues. (E) Western blot analysis of DPP4 protein expression in colonic tissues from healthy controls, non-stenotic, and stenotic regions of CD patients. (F) Densitometric quantification of DPP4 protein normalised to GAPDH (corresponding to panel E). (G) Representative endoscopic images of healthy controls, non-stenotic, and stenotic intestinal regions in CD patients, illustrating macroscopic features of stricture. Corresponding immunohistochemical (IHC) images show DPP4 expression in colonic tissues from the same groups. Adjacent serial sections stained with Masson’s trichrome highlight fibrotic areas. (H) Quantification of IHC DPP4 staining (IOD/area) across groups. * p < 0.05; ** p < 0.01; *** p < 0.001.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Expressing, Quantitative RT-PCR, Western Blot, Immunohistochemical staining, Staining

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Elevated DPP4 expression contributes to fibrotic remodelling in a chronic colitis model. (A) Colon length quantification in control ( n = 6) and DSS-treated ( n = 6) mice. (B) Representative H&E-stained colon sections (left) and histologic inflammation scores (right). (C) Representative Masson’s trichrome-stained colon sections and quantification of collagen volume fraction. (D) Immunofluorescence images and quantification of α -SMA⁺ fibrotic thickness in the muscularis propria. (E) qRT-PCR analysis of Col1a1 mRNA levels in colon tissues. (F) qRT-PCR analysis of Col6a1 mRNA levels in colon tissues. (G) Western blot analysis of DPP4 protein expression in control and DSS-treated mice. (H) Representative IHC staining of DPP4 expression in control and DSS-treated colons, with semiquantitative analysis. (I) Schematic overview of the chronic DSS-induced colitis model and pharmacological intervention. Mice received three cycles of 1.5% DSS (7 days per cycle), each followed by a 14-day recovery phase. The DPP4 inhibitor sitagliptin was administered via oral gavage for 21 days during the final cycle of the experiment. (J) Colon length quantification in the DSS group ( n = 6) and DSS + DPP4i group ( n = 6). (K) Representative H&E-stained colon sections (left) and histologic inflammation scores (right). (L) Representative Masson’s trichrome-stained colon sections and quantification of collagen volume fraction. (M) Immunofluorescence images and quantification of α -SMA⁺ fibrotic thickness in the muscularis propria. ( N ) RT-qPCR analysis of Col1a1 mRNA levels in colon tissues. (O) RT-qPCR analysis of Col6a1 mRNA levels in colon tissues. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Expressing, Control, Staining, Immunofluorescence, Quantitative RT-PCR, Western Blot, Immunohistochemistry

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Membrane-bound DPP4 in fibroblasts drives intestinal myofibroblast activation and migration. (A) Multiplex IHC staining of FFPE colonic sections from healthy controls, non-stenotic, and stenotic regions of CD patients. (B) Volcano plot showing DEGs in fibroblasts isolated from paired stenotic and normal CD tissues ( GSE90607 dataset, left), with DPP4 mRNA expression levels specifically highlighted (right). (C) Western blot analysis of membrane-bound DPP4 and α -SMA protein in primary HIMFs. (D) Western blot analysis and quantification of DPP4 and α -SMA expression in TGF-β–stimulated HIMFs with or without DPP4 inhibitor. (E) qRT-PCR analysis of COL1A1 mRNA expression in HIMFs. (F) qRT-PCR analysis of ACTA2 mRNA expression in HIMFs. (G) Immunofluorescence staining and quantification of Ki67⁺ proliferating HIMFs. (H) Representative images and quantification of HIMF migration in scratch wound healing assays. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Membrane, Activation Assay, Migration, Multiplex Assay, Immunohistochemistry, Isolation, Expressing, Western Blot, Quantitative RT-PCR, Immunofluorescence, Staining

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Soluble DPP4 (sDPP4) promotes intestinal myofibroblast activation, proliferation, and migration. (A) ELISA-based quantification of soluble DPP4 (sDPP4) levels in plasma from healthy controls ( n = 10), CD patients without stenosis ( n = 20), and with stenosis ( n = 20). (B) RT-qPCR analysis of COL1A1 mRNA expression in HIMFs treated with sDPP4 in the presence or absence of DPP4 inhibitor. (C) RT-qPCR analysis of ACTA2 mRNA expression in HIMFs treated with sDPP4 in the presence or absence of DPP4 inhibitor. (D) Western blot of α -SMA protein expression in HIMFs treated with sDPP4 in the presence or absence of DPP4 inhibitor. (E) Immunofluorescence staining and quantification of Ki67⁺ proliferating HIMFs treated with sDPP4 in the presence or absence of DPP4 inhibitor. (F) Scratch wound healing assay evaluating HIMF migration at 0 and 24 hours following sDPP4 stimulation, with or without DPP4 inhibitor. Wound closure was quantified using ImageJ. * p < 0.05; ** p < 0.01; *** p < 0.001.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Activation Assay, Migration, Enzyme-linked Immunosorbent Assay, Clinical Proteomics, Quantitative RT-PCR, Expressing, Western Blot, Immunofluorescence, Staining, Wound Healing Assay

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: DPP4 drives intestinal myofibroblast activation via the PI3K-AKT pathway. (A) Western blot analysis of canonical (SMAD3) and non-canonical (PI3K-AKT, ERK, JNK, and p38) signalling pathways in TGF- β -stimulated HIMFs, treated with or without DPP4 inhibitor (sitagliptin, 20 nM). (B) Western blot analysis of p -PI3K, PI3K, p -AKT, AKT, and α -SMA expression in HIMFs treated with TGF- β , in the presence or absence of DPP4 inhibitor (20 nM) and the PI3K activator 740Y- P (10 μM). (C) Western blot analysis of p -ERK, ERK, and α -SMA expression in HIMFs treated with TGF- β , in the presence or absence of DPP4 inhibitor (20 nM) and the MEK/ERK activator C16-PAF (1 μM). (D) Scratch wound healing assay of HIMF migration at 0 and 24 hours following TGF- β stimulation with or without DPP4 inhibitor (20 nM) and the PI3K activator 740Y- P (10 μM). Wound closure was quantified using ImageJ. Ki67 immunofluorescence staining and quantification of proliferating HIMFs are shown in the lower panels. (E) Scratch wound healing assay of HIMF migration at 0 and 24 hours following TGF- β stimulation with or without DPP4 inhibitor (20 nM) and the MEK/ERK activator C16-PAF (1 μM). Wound closure was quantified using ImageJ. Ki67 immunofluorescence staining and quantification are shown in the lower panels. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Activation Assay, Western Blot, Expressing, Wound Healing Assay, Migration, Immunofluorescence, Staining

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Gut microbiota-derived DPP4 is enriched in stenotic CD and associated with fibrotic remodelling. (A) Schematic overview of the faecal metagenomic sequencing strategy in controls ( n = 10), CD without stenosis ( n = 20), and CD with stenosis ( n = 20). (B) Relative abundance of microbial Dpp4 genes across the three groups, as determined by metagenomic sequencing. (C) Species-level contributions of microbial Dpp4 genes in CD patients with stenosis, showing the top five contributing species ranked by relative abundance. (D) Differential abundance of microbial Dpp4 genes assigned to four Bacteroides species in faecal metagenomes from healthy controls, non-stenotic CD, and stenotic CD patients. (E) Total faecal DPP4 enzymatic activity was measured by Gly-Pro-pNA assay in controls, CD patients without stenosis, and those with stenosis. (F) Faecal DPP4 enzymatic activity was measured in control mice and those with DSS-induced chronic colitis. (G) Time-dependent increase in DPP4 activity measured in the culture supernatants of B. thetaiotaomicron grown under anaerobic conditions. (H–I) RT-qPCR analysis of COL1A1 (H) and ACTA2 (I) mRNA levels in HIMFs treated with increasing concentrations of recombinant btDPP4 (0–400 ng/mL). (J) Western blot analysis of α -SMA protein expression in HIMFs treated with 200 ng/mL btDPP4. (K) Ki67 immunofluorescence staining and quantification of proliferating HIMFs following treatment with 200 ng/mL btDPP4. (L) Scratch wound healing assay of HIMF migration at 0 and 24 hours following treatment with 200 ng/mL btDPP4. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Derivative Assay, Sequencing, Activity Assay, Control, Quantitative RT-PCR, Recombinant, Western Blot, Expressing, Immunofluorescence, Staining, Wound Healing Assay, Migration

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Colonisation with engineered bacteria overexpressing DPP4 worsens fibrotic remodelling in DSS-induced chronic colitis. (A) Schematic illustration of engineered E. coli btDPP4 construction. (B) PCR validation of btDPP4 genomic integration in engineered E. coli strains. (C) Growth curves comparing E. coli btDPP4 and wild-type (WT) strains under standard conditions. (D) Secreted DPP4 enzymatic activity measured in the culture supernatants of E. coli btDPP4 and E. coli WT. (E) Experimental design of the chronic DSS colitis model with oral gavage of PBS, E. coli WT, or E. coli btDPP4. (F) Relative faecal E. coli load in mice treated with PBS, E. coli WT, or E. coli btDPP4. (G) Expression of btDPP4 gene in faeces from mice treated with PBS, E. coli WT, or E. coli btDPP4. (H) Faecal DPP4 enzymatic activity in mice treated with PBS, E. coli WT, or E. coli btDPP4. (I) Colon length was measured and compared across groups. (J) Representative H&E-stained colon sections and quantification of histological inflammation scores. (K) Representative Masson’s trichrome-stained sections and quantification of collagen volume fraction. (L) Immunofluorescence staining of α -SMA⁺ fibrotic areas and quantification of fibrotic thickness. (M–N) RT-qPCR analysis of Col1a1 (M) and Col6a1 ( N ) mRNA levels in mouse colon tissues. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Bacteria, Biomarker Discovery, Activity Assay, Expressing, Staining, Immunofluorescence, Quantitative RT-PCR

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Microbial-derived DPP4 inhibitor Dau-d4 suppresses intestinal myofibroblast activation. (A-B) RT-qPCR analysis of COL1A1 and ACTA2 mRNA expression in HIMFs treated with increasing concentrations of recombinant microbial DPP4 (btDPP4, hereafter referred to as mDPP4), with or without the microbial DPP4 inhibitor Dau-d4 (0–200 nM). (C) Western blot analysis of α -SMA protein expression in HIMFs stimulated with mDPP4, with or without 100 nM Dau-d4. (D) Ki67 immunofluorescence staining and quantification of proliferating HIMFs stimulated with mDPP4, with or without 100 nM Dau-d4. (E) Scratch wound healing assay showing HIMF migration at 0 and 24 hours following treatment with mDPP4, in the presence or absence of 100 nM Dau-d4. (F) Western blot analysis of p -PI3K, PI3K, p -AKT, AKT, and α -SMA expression in HIMFs treated with vehicle control, mDPP4 (200 ng/mL), mDPP4 + Dau-d4 (100 nM), or mDPP4 + Dau-d4 + PI3K activator 740Y- P (10 μM) for 24 hours. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Derivative Assay, Activation Assay, Quantitative RT-PCR, Expressing, Recombinant, Western Blot, Immunofluorescence, Staining, Wound Healing Assay, Migration, Control

Journal: Gut Microbes

Article Title: Dual-source DPP4 drives intestinal fibrosis in Crohn’s disease: synergistic therapeutic targeting of host and microbiota pathways

doi: 10.1080/19490976.2025.2593119

Figure Lengend Snippet: Dual inhibition of bacterial- and host-derived DPP4 synergistically attenuates intestinal fibrosis in vivo. (A) Schematic of the experimental design showing late-phase intervention with the microbiota-derived DPP4 inhibitor Dau-d4 (10 mg/kg), alone or in combination with the host-derived DPP4 inhibitor sitagliptin, during the final cycle of DSS-induced chronic colitis. (B) DPP4 activity was measured in the murine faeces following treatment. (C) Colon length was measured and compared across groups. (D) Representative H&E-stained colon sections and quantification of histological inflammation scores. (E) Representative images of Masson’s trichrome staining and quantification of collagen volume fraction. (F) Immunofluorescence staining of α -SMA⁺ areas and quantification. (G-H) RT-qPCR analysis of Col1a1 and Col6a1 mRNA expression in murine colonic tissues. * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

Article Snippet: Following wounding, the cells were treated with TGF- β (10 ng/mL, Novoprotein, China), the DPP4 inhibitor sitagliptin (20 nmol/L, MCE, USA), sDPP4 (200 ng/mL, MCE, USA), mDPP4 (200 ng/mL), or the mDPP4 inhibitor Dau-d4 (100 nmol/L, MCE, USA).

Techniques: Inhibition, Derivative Assay, In Vivo, Activity Assay, Staining, Immunofluorescence, Quantitative RT-PCR, Expressing