New whole slide image analysis method for detection and quantification of hepatocellular vacuolization in European flounder (Platichthys flesus) in multipollutant exposure context

A new whole slide image analysis method was developed for hepatocellular vacuolization detection and quantification in European flounder (Platichthys flesus) liver. Histopathological quantification allows a better understanding of how contaminants and biotic factors might influence lesion pathogenesis in a multipollutant exposure context. One of the main findings is the significant difference in the extent of the pathology between the polluted and the control sites,with P. flesus sampled in the Seine estuary presenting a higher proportion of tissue affected by hepatocellular vacuolation (6.88 sd. 3.01%) compared to fish sampled in the Canche estuary (5.46 sd. 2.86%). This result is coherent with the previous qualitative histological assessment done on the same histological samples, it helps validate the method and brings new insight into the pathology intensity level with the level of contamination on each site. The other main finding is the potential synergetic effect of the pollutant mixture on the pathology. The multipollutant analysis showed a positive mixture effect on the proportion of tissue affected by hepatocellular vacuolation in fish from the Seine estuary, while this effect is not observed in fish sampled in the Canche estuary. This study highlights the benefits of developing novel bio-image analysis methods for environmental research. Histopathological diagnostic quantification allows a better understanding of the potential factors inducing and exacerbating the pathology, as well as the potential mixture effect in a context of multipollutant contamination.