Serum and Hepatic Autofluorescence as a Real-Time Diagnostic Tool for Early Cholestasis Assessment

Abstract

While it is well established that various factors can impair the production and flow of bile and lead to cholestatic disease in hepatic and extrahepatic sites, an enhanced assessment of the biomarkers of the underlying pathophysiological mechanisms is still needed to improve early diagnosis and therapeutic strategies. Hence, we investigated fluorescing endogenous biomolecules as possible intrinsic biomarkers of molecular and cellular changes in cholestasis. Spectroscopic autofluorescence (AF) analysis was performed using a fiber optic probe (366 nm excitation), under living conditions and in serum, on the livers of male Wistar rats submitted to bile duct ligation (BDL, 24, 48, and 72 h). Biomarkers of liver injury were assayed biochemically. In the serum, AF analysis distinctly detected increased bilirubin at 24 h BDL. A continuous, significant increase in red-fluorescing porphyrin derivatives indicated the subversion of heme metabolism, consistent with an almost twofold increase in the serum iron at 72 h BDL. In the liver, changes in the AF of NAD(P)H and flavins, as well as lipopigments, indicated the impairment of mitochondrial functionality, oxidative stress, and the accumulation of oxidative products. A serum/hepatic AF profile can be thus proposed as a supportive diagnostic tool for the in situ, real-time study of bio-metabolic alterations in bile duct ligation (BDL) in experimental hepatology, with the potential to eventually translate to clinical diagnosis.

Light and Autofluorescence, Multitasking Features in Living Organisms

“…These insights derive from the central role of liver in providing for the storage, mobilization and systemic homeostasis of these biomolecules, and the consequent biological effects. These may depend on the balance between the possible antioxidant or toxic effects of vitamin A, and on the involvement of arachidonic and other fatty acid derivatives, namely the eicosanoids prostanoids, lipoxins, leukotrienes and the n-HETE series of hydroxyeicosatetraenoic, in sensing the regulation of protective or damaging, anti-or pro-inflammatory, pathways following hazardous stimuli such as oxidative stress [47,343].…”

Recent Advances and the Potential for Clinical Use of Autofluorescence Detection of Extra-Ophthalmic Tissues

“…In the future, technical advancements will allow high-resolution AF detection, the specific excitation of fluorophores, and detection of emitted light within narrow wavelength ranges. In addition, experimental studies also already found that metabolic processes can be tracked by changing AF characteristics, caused, for example, by changing fluorescence spectra of NAD(P)H in its bound or free form or redox state [171]. A summary of the experimental advancements and first translational results on AF-based metabolic imaging was recently presented by Croce et al [172].…”

Cell Interactions in Biliary Diseases: Clues from Pathophysiology and Repair Mechanisms to Foster Early Assessment

“…Using real-time spectroscopic autofluorescence analysis of serum and liver tissue in experimental cholestasis (rats undergoing bile duct ligation), Croce and colleagues observed distinctive changes in some endogenous fluorophores. In serum, they found a significant increase in porphyrin derivatives, indicating perturbation of the heme metabolism, while in liver tissue, they described dramatic changes in the content of NAD(P)H, flavins, and lipofuscin-like lipopigments, reflecting mitochondrial dysfunction, oxidative stress, and accumulation of oxidized species [18]. Altogether, these molecular alterations may be regarded as chemical footprints of the initial events occurring in cholestasis, possibly to take advantage of for early diagnosis.…”