Identification of Lipid Biomarkers of Human Inflammatory Bowel Disease Using Imaging Mass Spectrometry

Significance of the Topic

Inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease impose severe clinical challenges due to their chronic nature and unknown etiology. Rapid and accurate subtype classification is critical for guiding therapy and minimizing adverse outcomes. Imaging mass spectrometry enables the molecular mapping of tissue sections, offering direct insight into lipid alterations associated with inflammation and neoplasia at high spatial resolution.

Objectives and Overview of the Study

This study aimed to identify distinct lipid biomarkers of human inflammatory bowel disease by applying high-resolution MALDI imaging of endoscopic biopsy sections. Three patient cohorts were compared: IBD, hereditary colorectal cancer, and healthy controls. Optimization of matrix deposition and imaging parameters was performed on murine colon sections before analysis of human samples at 10 micrometer spatial resolution.

Methodology and Instrumentation

• Sample preparation: 10 micrometer cryosections of frozen colon biopsies.
• Matrix application: 1,5-diaminonaphthalene deposited by glass sublimation (89 ug/cm2), optimized at 10 minutes to achieve homogeneous ∼3 micrometer crystals.
• Imaging mass spectrometry: Shimadzu MALDI-7090 TOF-TOF instrument with 355 nm UV laser (10 micrometer spot, up to 2 kHz repetition), linear and reflectron modes, negative ion detection, mass range 200–2000 Da.
• Data processing: IonView software for image reconstruction and ROI extraction.

Main Results and Discussion

• Distinct lipid distributions delineated epithelium, lamina propria, and muscularis mucosae in human colon based on species such as Cer-PE 38:1 (m/z 715.6), plasmalogen PE, phosphatidylserine, and phosphatidylinositol variants.
• Optimization experiments demonstrated that a 10 minute sublimation of 1,5-DAN provided the best signal intensity and morphological detail compared to 8 and 12 minute deposition times.
• Region of interest analysis revealed that PI 16:0/18:1 (m/z 835.5) and PI 36:2 (m/z 861.5) were enriched in colonocytes, while PI 18:0/20:4 (m/z 885.5), an arachidonic acid reservoir linked to inflammation, was more abundant in lamina propria and muscularis mucosae.
• Comparative profiling indicated that IBD-derived lamina propria exhibits a lipid signature distinct from both healthy and hereditary colorectal cancer tissues, suggesting potential markers for inflammatory lesions.

Benefits and Practical Applications

Direct visualization of lipid biomarkers in situ can enhance diagnostic precision and support personalized treatment strategies for inflammatory bowel disease. The method combines high spatial resolution with minimal sample preparation, enabling correlation of molecular changes with histological features and accelerating biomarker discovery.

Future Trends and Applications

• Integration of MS/MS on tissue for definitive lipid identification and validation of candidate biomarkers.
• Advanced statistical and machine learning approaches to classify patient cohorts based on lipidomic patterns.
• Expansion to other tissue types and incorporation into routine clinical workflows for real time diagnostics.
• Combination with proteomic and genomic imaging to provide a comprehensive molecular histology platform.

Conclusion

Imaging mass spectrometry using optimized 1,5-DAN matrix deposition on human colon biopsies enables the discrimination of tissue types and patient cohorts by their lipid fingerprints. Key PI species serve as candidate biomarkers differentiating inflammatory from neoplastic and healthy tissues, highlighting the potential of this approach for improved diagnosis and therapeutic monitoring in IBD.