biomedicines Article Mitochondrial Alterations in Fibroblasts of Early Stage Bipolar Disorder Patients Ana P. Marques 1,2,3,4,† , Rosa Resende 1,2,3,4, * ,† , Diana F. Silva 1,2,3,4 , Mariana Batista 4,5 , Daniela Pereira 4,6,7 , Brigite Wildenberg 4,6,7 , Sofia Morais 4,6,7 , António Macedo 4,6,7,8 , Cláudia Pais 9 , Joana B. Melo 1,4,6,9,10 , Nuno Madeira 4,6,7,8 and Cláudia F. Pereira 1,2,4,6, *   Citation: Marques, A.P.; Resende, R.; Silva, D.F.; Batista, M.; Pereira, D.; Wildenberg, B.; Morais, S.; Macedo, A.; Pais, C.; Melo, J.B.; et al. Mitochondrial Alterations in Fibroblasts of Early Stage Bipolar Disorder Patients. Biomedicines 2021, 9, 522. https://doi.org/10.3390/ biomedicines9050522 Academic Editor: Alessandro Rimessi Received: 29 March 2021 Accepted: 29 April 2021 Published: 7 May 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3004-504 Coimbra, Portugal; apatriciabmarques@gmail.com (A.P.M.); dianaffsilva@gmail.com (D.F.S.); mmelo@fmed.uc.pt (J.B.M.) 2 Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal 3 Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3030-789 Coimbra, Portugal 4 Clinical Academic Cener of Coimbra (CACC), 3004-561 Coimbra, Portugal; sousabatistamariana@gmail.com (M.B.); dsmpereira4@gmail.com (D.P.); brigitewildenberg@hotmail.com (B.W.); sofiamorais86@gmail.com (S.M.); amacedo@ci.uc.pt (A.M.); nmadeira@uc.pt (N.M.) 5 Department of Dermatology, Centro Hospitalar e Universitário de Coimbra (CHUC), 3004-561 Coimbra, Portugal 6 Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal 7 Department of Psychiatry, Centro Hospitalar e Universitário de Coimbra (CHUC), 3004-561 Coimbra, Portugal 8 Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal 9 Cytogenetics and Genomics Laboratory, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; claudypais@gmail.com 10 Coimbra Institute for Clinical and Biomedical Research (iCBR), Center of Investigation in Environment, Genetics and Oncobiology (CIMAGO), 3000-548 Coimbra, Portugal * Correspondence: rresende@cnc.uc.pt (R.R.); cpereira@cnc.cj.uc.pt (C.F.P.) † These authors contributed equally to this work. Abstract: This study aims to evaluate whether mitochondrial changes occur in the early stages of bipolar disorder (BD). Using fibroblasts derived from BD patients and matched controls, the levels of proteins involved in mitochondrial biogenesis and dynamics (fission and fusion) were evaluated by Western Blot analysis. Mitochondrial membrane potential (MMP) was studied using the fluorescent probe TMRE. Mitochondrial morphology was analyzed with the probe Mitotracker Green and mitophagy was evaluated by quantifying the co-localization of HSP60 (mitochondria marker) and LC3B (autophagosome marker) by immunofluorescence. Furthermore, the activity of the mitochondrial respiratory chain and the glycolytic capacity of controls and BD patients-derived cells were also studied using the Seahorse technology. BD patient-derived fibroblasts exhibit fragmented mitochondria concomitantly with changes in mitochondrial dynamics and biogenesis in comparison with controls. Moreover, a decrease in the MMP and increased mitophagy was observed in fibroblasts obtained from BD patients when compared with control cells. Impaired energetic metabolism due to inhibition of the mitochondrial electron transport chain (ETC) and subsequent ATP depletion, associated with glycolysis stimulation, was also a feature of BD fibroblasts. Overall, these results support the fact that mitochondrial disturbance is an early event implicated in BD pathophysiology that might trigger neuronal changes and modification of brain circuitry. Keywords: bipolar disorder; mitochondrial dysfunction; mitochondrial biogenesis; mitophagy; bioenergetics; fibroblasts Biomedicines 2021, 9, 522. https://doi.org/10.3390/biomedicines9050522 https://www.mdpi.com/journal/biomedicines