Lemieux 2019a MiP2019

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Hélène Lemieux
Partial prevention of oxidative stress damage to mitochondria with photobiomodulation.

Link: MiP2019

Lemieux H, Han WH, Lessard M, Mast H, Anfray A, Holody C (2019)

Event: MiP2019

COST Action MitoEAGLE

Mitochondrial dysfunction is now recognized as an important factor in the pathogenesis of multiple diseases. In the past decades, photobiomodulation (PBM) has gained increasing interest as a potential mitochondria-targeting therapy. PBM involves the administration of a single or series of near-infrared (NIR) light exposures at low intensity. It has a great advantage of being a non-invasive treatment. Multiple beneficial effects of PBM have been reported in the literature which include a reduction in pain, inflammation, and edema, a regeneration of damaged tissues, a neuroprotective effect, an increase in toxin resistance and some anti-oxidative attributes [1, 2]. The currently accepted model proposes that functional changes in mitochondria have a strong involvement in the mechanism. While there has been a great amount of research on the clinical observations and biochemical pathway activations of PBM (i.e. secondary effects), the direct changes to mitochondria (i.e. primary effect) are not as well studied and remain somewhat controversial. Consequently, the present study is aimed at providing a more accurate understanding of the functional changes to mitochondria in response to NIR light exposure in normal conditions or as a protection against oxidative stress injuries.

The planarian flatworm Dugesia Tigrina is used as the animal model [3]. It has the advantages of being small and translucent, offering the possibility to study the effects on the whole organism. In 6-well plates, the animals were either kept under normal conditions (control) or exposed to NIR light (78 s; 0.5 J/cm2). The light exposure did not alter the temperature of the plates, and was followed by one hour at room temperature. Then, some wells were exposed to oxidative stress using 10 mM hydrogen peroxide (H2O2) for 1 min. Mitochondrial function was measured using high-resolution respirometry (Oxygraph 2k; Oroboros Instruments Inc.). Four treatment groups were included: (1) control, without NIR and H2O2, (2) NIR without H2O2 (3) H2O2 without NIR, and (4) treated with both NIR and H2O2. The multiple substrate-inhibitor protocol allowed for the measurement of three states: LEAK respiration (before the addition of ADP), OXPHOS capacity (in the ADP-activated state, coupled oxidative phosphorylation) and ET capacity (electron transfer capacity after uncoupling). The capacities of different pathways and steps were included in the protocol, i.e., the NADH pathway (with NADH-linked substrates giving electrons into complex I), the Succinate pathway (with succinate providing electrons into complex II), the NS-pathway (with complex I- and II-linked substrates simultaneously), and the complex IV. Respiratory capacities were expressed in flux per mass or in flux control ratio (FCR), relative to the maximal ET-capacity. ANOVA’s with post-hoc Tukey tests were carried out and a p<0.05 was considered significant (N=22 per group).

Exposure of the live planarian to 10 mM of H2O2 causes changes in the mitochondrial respiratory capacity, especially a reduction in NADH pathway OXPHOS capacity (p˂0.001) and in the Succinate pathway ET-capacity (p=0.005), as well as a slight increase in LEAK respiration (p=0.010). The OXPHOS limitation by the phosphorylation system was also increased in the group treated with H2O2 compared to the control (p˂0.001). This suggests that there is an effect produced by H2O2 exposure on component(s) of the phosphorylation system. In contrast, the hydrogen peroxide treatment had no effect on complex IV capacity. Without exposure to hydrogen peroxide, PBM did not affect significantly any of the mitochondrial parameters measured. PMB therapy applied to the planarian previous to H2O2 exposure successfully restored the Succinate pathway capacity to the level of the control. Furthermore, treatment with NIR decreases the sensitivity of the mitochondrial outer membrane to damage when exposed to H2O2 (p=0.026), even if the membrane sensitivity was not affected by H2O2 exposure alone (p=0.835). In contrast, the NADH-pathway relative capacity and the limitation of OXPHOS by the phosphorylation system remained compromised by H2O2 treatment even with pre-exposure to PBM.

Our study points toward a potential new targets of PBM therapy on mitochondrial function, including the complex II and outer mitochondrial membrane fragility. More studies are needed to increase our knowledge of the function of PBM treatment in rescuing damaged mitochondria under various conditions, and to reach a better understanding of the mechanism of this promising therapy.


Bioblast editor: Plangger M, Tindle-Solomon L O2k-Network Lab: CA Edmonton Lemieux H


Labels: MiParea: Respiration, mt-Medicine 

Stress:Oxidative stress;RONS  Organism: Other invertebrates 



Coupling state: LEAK, OXPHOS, ET  Pathway: N, S, CIV, NS  HRR: Oxygraph-2k 


Affiliations

Lemieux H(1,2,3), Han WH(1), Lessard M(1), Mast H(1), Anfray A(1), Holody C(1,2)
  1. Fac Saint-Jean,
  2. Women and Children’s Health Research Inst (WCHRI),
  3. Dept Medicine, Univ Alberta. - Helene.lemieux@ualberta.ca

References

  1. Hamblin MR (2018) Mechanisms and mitochondrial redox signaling in photobiomodulation. Photochem Photobiol 94:199-212.
  2. Hennessy M, Hamblin MR (2017) Photobiomodulation and the brain: a new paradigm. J Opt 19:013003.
  3. Lemieux H, Warren B (2012) An animal model to study human muscular diseases involving mitochondrial oxidative phosphorylation. J Bioenerg Biomembr 44:503-12.