Mitochondrial toxicity
is a significant concern in the drug discovery
process, as compounds that disrupt the function of these organelles
can lead to serious side effects, including liver injury and cardiotoxicity.
Different in vitro assays exist to detect mitochondrial toxicity at
varying mechanistic levels: disruption of the respiratory chain, disruption
of the membrane potential, or general mitochondrial dysfunction. In
parallel, whole cell imaging assays like Cell Painting provide a phenotypic
overview of the cellular system upon treatment and enable the assessment
of mitochondrial health from cell profiling features. In this study,
we aim to establish machine learning models for the prediction of
mitochondrial toxicity, making the best use of the available data.
For this purpose, we first derived highly curated datasets of mitochondrial
toxicity, including subsets for different mechanisms of action. Due
to the limited amount of labeled data often associated with toxicological
endpoints, we investigated the potential of using morphological features
from a large Cell Painting screen to label additional compounds and
enrich our dataset. Our results suggest that models incorporating
morphological profiles perform better in predicting mitochondrial
toxicity than those trained on chemical structures alone (up to +0.08
and +0.09 mean MCC in random and cluster cross-validation, respectively).
Toxicity labels derived from Cell Painting images improved the predictions
on an external test set up to +0.08 MCC. However, we also found that
further research is needed to improve the reliability of Cell Painting
image labeling. Overall, our study provides insights into the importance
of considering different mechanisms of action when predicting a complex
endpoint like mitochondrial disruption as well as into the challenges
and opportunities of using Cell Painting data for toxicity prediction.