Despite the progresses performed in the field of radiotherapy, toxicity to the healthy tissues remains a major limiting factor. The aim of this work was to highlight blood biomarkers whose variations could predict the occurrence of late cutaneous side effects. Two groups of nine patients treated for Merkel Cell Carcinoma (MCC) were established according to the grade of late skin toxicity after adjuvant irradiation for MCC: grade 0, 1 or 2 and grade 3 or 4 of RTOG (Radiation Therapy Oncology Group)/EORTC (European Organization for Research and Treatment of Cancer). To try to discriminate these 2 groups, biomarkers of interest were measured on the different blood compartments after ex vivo irradiation. In lymphocytes, cell cycle, apoptosis and genotoxicity were studied. Oxidative stress was evaluated by the determination of the erythrocyte antioxidant capacity (superoxide dismutase, catalase, glutathione peroxidase, reduced and oxidized glutathione) as well as degradation products (protein carbonylation, lipid peroxidation). Inflammation was assessed in the plasma by the measurement of 14 cytokines. The most radiosensitive patients presented a decrease in apoptosis, micronucleus frequency, antioxidant enzyme activities, glutathione and carbonyls; and an increase in TNF-α (Tumor Necrosis Factor α), IL-8 (Interleukin 8) and TGF-β1 (Transforming Growth Factor β1) levels. These findings have to be confirmed on a higher number of patients and before radiotherapy and could allow to predict the occurrence of late skin side effects after radiotherapy.

Side effects of proton therapy are poorly studied. Moreover, the differences in the method of dose delivery on normal tissues are not taken into account when proton beams are scanned instead of being scattered. We proposed here to study the effects of both modalities of proton beam delivery on blood; skin; lung and heart in a murine model. In that purpose; C57BL/6 mice were total body irradiated by 190.6 MeV proton beams either by Double Scattering (DS) or by Pencil Beam Scanning (PBS) in the plateau phase before the Bragg Peak. Mouse survival was evaluated. Blood and organs were removed three months after irradiation. Biomarkers of genotoxicity; oxidative stress and inflammation were measured. Proton irradiation was shown to increase lymphocyte micronucleus frequency; lung superoxide dismutase activity; erythrocyte and skin glutathione peroxidase activity; erythrocyte catalase activity; lung; heart and skin oxidized glutathione level; erythrocyte and lung lipid peroxidation and erythrocyte protein carbonylation even 3 months post-irradiation. When comparing both methods of proton beam delivery; mouse survival was not different. However, PBS significantly increased lymphocyte micronucleus frequency; erythrocyte glutathione peroxidase activity and heart oxidized glutathione level compared to DS. These results point out the necessity to take into account the way of delivering dose in PT as it could influence late side effects.

Proton therapy allows to avoid excess radiation dose on normal tissues. However, there are some limitations. Indeed, passive delivery of proton beams results in an increase in the lateral dose upstream of the tumor and active scanning leads to strong differences in dose delivery. This study aims to assess possible differences in the transcriptomic response of skin in C57BL/6 mice after TBI irradiation by active or passive proton beams at the dose of 6 Gy compared to unirradiated mice. In that purpose, total RNA was extracted from skin samples 3 months after irradiation and RNA-Seq was performed. Results showed that active and passive delivery lead to completely different transcription profiles. Indeed, 140 and 167 genes were differentially expressed after active and passive scanning compared to unirradiated, respectively, with only one common gene corresponding to RIKEN cDNA 9930021J03. Moreover, protein–protein interactions performed by STRING analysis showed that 31 and 25 genes are functionally related after active and passive delivery, respectively, with no common gene between both types of proton delivery. Analysis showed that active scanning led to the regulation of genes involved in skin development which was not the case with passive delivery. Moreover, 14 ncRNA were differentially regulated after active scanning against none for passive delivery. Active scanning led to 49 potential mRNA-ncRNA pairs with one ncRNA mainly involved, Gm44383 which is a miRNA. The 43 genes potentially regulated by the miRNA Gm44393 confirmed an important role of active scanning on skin keratin pathway. Our results demonstrated that there are differences in skin gene expression still 3 months after proton irradiation versus unirradiated mouse skin. And strong differences do exist in late skin gene expression between scattered or scanned proton beams. Further investigations are strongly needed to understand this discrepancy and to improve treatments by proton therapy.

Obstructive sleep apnea syndrome (OSA) is a common clinical condition produced by episodes of repeated upper airways obstruction resulting in airflow blockade (apnea) during sleep. OSA is defined as a frequent chronic disease, which is highly prevalent in the population (affecting 9% of women and 24% of men) and which increases linearly with age. Chronic intermittent hypoxia (IH), the main pathogenic consequence related to OSA, is responsible for cardiovascular morbidity, including systemic arterial hypertension, cardiac infarct, atherosclerosis, and muscular remodeling in OSA patients.Systemic hypertension is the first cardiovascular disease related to OSA, thus 50% to 90% of patients with OSA develop hypertension. The mechanisms by which intermittent hypoxia induces the hypertension are not fully explained; we still don't know exactly the cause of hypertension, which make it a difficult medical condition to control, and make standard pharmacological interventions ineffective. Thus in order to found an effective treatment for hypertension induced by IH, we have to seek a non‐pharmacological intervention.While IH is known to contribute to hypertension, physical intensive training (IT) wields beneficial effects on the cardiovascular system and is known to reduce the hypertension risk in adults. Since physical exercise decreases the risk of cardiovascular events, the magnitude of this benefit can be also used as an anti‐hypertensive intervention.We choses a high‐intensity exercise protocol (exercise sessions during 21 days, 5 times/week on rats as a double fast 24 min‐walk with a speed progressively rising from 16 to 30 m/min), to prevent the IH‐impact and examine if IT can reverse or reduce the deleterious effects of IH (alternating normoxia (21%O2) and hypoxia (5%O2) every 30 sec in the cages for 8 h/day during 3 weeks) on the vascular reactivity, muscular remodeling and prevents the occurrence of hypertension.As expected, we found beneficial effects of training on physiological parameters (heart rate, arterial pressure), but also on vascular remodeling of several vessels (thoracic, abdominal, carotidal and pulmonary arteries); in addition we were able to observe opposite effects between IH and IT on gene transcription (Q‐PCR) and protein production (western blot) of several channels associated to calcium signaling (e.g. RyR, IP3R, SERCA, TRP) in cardiovascular system. We also compared calcium transient (ΔF/F0) from sarcoplasmic reticulum between normoxic and hypoxic smooth muscle cells and the significant difference (respectively 0,69±0,15 vs 1,01±0,21, p<0,05) was abolished in cells from trained rats. Taken together, these results suggest that IT could decrease the adverse effects of IH on the cardiovascular system by acting from molecular to physiological organizations of muscular tissue. These data support the hypothesis that intensive exercise training may represent a promising non‐invasive, non‐pharmacological and complementary approach for the treatment of systemic hypertension.Support or Funding InformationINSERM, University of Grenoble Alps, University of Lebanon, AUF (PCSI)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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