Assessment of renal fibrosis and anti-fibrotic agents using a novel diagnostic and stain-free second-harmonic generation platform.

Abstract

Current histological measurement techniques for interstitial collagen, the basis of interstitial fibrosis, are semi-quantitative at best and only provide a ratio of collagen levels within tissues. The Genesis200 imaging system and supplemental image analysis software, FibroIndex from HistoIndex, is a novel, automated platform that uses second-harmonic generation (SHG) for imaging and characterization of interstitial collagen deposition and additional characteristics, in the absence of any staining. However, its ability to quantify renal fibrosis requires investigation. This study compared SHG imaging of renal fibrosis in mice with unilateral ureteric obstruction (UUO), to that of Masson's trichrome staining (MTS) and immunohistochemistry (IHC) of collagen I. Additionally, the platform generated data on collagen morphology and distribution patterns. While all three methods determined that UUO-injured mice underwent significantly increased renal fibrosis after 7 days, the HistoIndex platform additionally determined that UUO-injured mice had a significantly increased collagen-to-tissue cross reticulation ratio (all P < .001 vs sham group). Furthermore, in UUO-injured mice treated with the relaxin family peptide receptor-1 agonists, relaxin (0.5 mg/kg/day) or B7-33 (0.25 mg/kg/day), or angiotensin converting enzyme-inhibitor, perindopril (1 mg/kg/day) over the 7-day period, only the HistoIndex platform determined that the drug-induced prevention of renal fibrosis correlated with significantly reduced collagen fiber thickness and collagen-to-tissue cross reticulation ratio, but increased collagen fiber counts. Relaxin or B7-33 treatment also increased renal matrix metalloproteinase-2 and reduced tissue inhibitor of metalloproteinase-1 levels (all P < .01 vs UUO alone). This study demonstrated the diagnostic value of the HistoIndex platform over currently used staining techniques.

• Authors: Sadman Bhuiyan, Matthew Shen, Sharenya Chelvaretnam, Andre Y Tan, Gideon Ho, Mohammed Akhter Hossain, Robert E Widdop, Chrishan S Samuel
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 35 Issue 5 Pg. e21595 (05 2021) ISSN: 1530-6860 [Electronic] United States
• PMID: 33908676 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2021 Federation of American Societies for Experimental Biology.

Chemical References

• Angiotensin-Converting Enzyme Inhibitors
• B7-33 peptide
• Peptide Fragments
• Relaxin

Topics

• Angiotensin-Converting Enzyme Inhibitors (pharmacology)
• Animals
• Fibrosis (drug therapy, etiology, pathology)
• Kidney Diseases (drug therapy, etiology, pathology)
• Male
• Mice
• Mice, Inbred C57BL
• Peptide Fragments (pharmacology)
• Relaxin (pharmacology)
• Ureteral Obstruction (complications)