Yann Lacoume

Université de Rouen, Mont-Saint-Aignan, Upper Normandy, France

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Publications (12)22.34 Total impact

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    ABSTRACT: Muscle potentially represents the most abundant source of autoantigens of the body and can be targeted by a variety of severe autoimmune diseases. Yet, the mechanisms of immunological tolerance toward muscle autoantigens remain mostly unknown. We investigated this issue in transgenic SM-Ova mice that express an ovalbumin (Ova) neo-autoantigen specifically in skeletal muscle. We previously reported that antigen specific CD4(+) T cell are immunologically ignorant to endogenous Ova in this model but can be stimulated upon immunization. In contrast, Ova-specific CD8(+) T cells were suspected to be either unresponsive to Ova challenge or functionally defective. We now extend our investigations on the mechanisms governing CD8(+) tolerance in SM-Ova mice. We show herein that Ova-specific CD8(+) T cells are not detected upon challenge with strongly immunogenic Ova vaccines even after depletion of regulatory T cells. Ova-specific CD8(+) T cells from OT-I mice adoptively transferred to SM-Ova mice started to proliferate in vivo, acquired CD69 and PD-1 but subsequently down-regulated Bcl-2 and disappeared from the periphery, suggesting a mechanism of peripheral deletion. Peripheral deletion of endogenous Ova-specific cells was formally demonstrated in chimeric SM-Ova mice engrafted with bone marrow cells containing T cell precursors from OT-I TCR-transgenic mice. Thus, the present findings demonstrate that immunological tolerance to muscle autoantigens involves peripheral deletion of autoreactive CD8(+) T cells.
    PLoS ONE 01/2012; 7(5):e36444. · 3.53 Impact Factor
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    ABSTRACT: Introduction: Olfactory ensheathing cells (OECs) hold promise for cell therapy because they may promote regeneration of the central nervous system. However, OECs have been less studied after peripheral nerve injury (PNI). The purpose of this investigation was to determine the effect of OEC transplantation on a severe sciatic nerve (SN) lesion. Methods: OECs were injected in rats after section and 2-cm resection of the SN. Results: Three months after therapy, muscle strength and morphometric studies showed complete restoration of the contractile properties of the gastrocnemius and complete repair of the SN. Immunohistochemistry and RT-PCR studies indicated an increase in the presence of neurotrophic factors. Interestingly, tracking of green fluorescent protein (GFP)-positive OECs showed that no OECs were present in the SN. Discussion: Our results demonstrate that, after severe PNI, OECs have remarkable potential for nerve regeneration by creating a favorable microenvironment. Muscle Nerve, 2011
    Muscle & Nerve 02/2011; 43(4):543 - 551. · 2.31 Impact Factor
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    ABSTRACT: Olfactory ensheathing cells (OECs) hold promise for cell therapy because they may promote regeneration of the central nervous system. However, OECs have been less studied after peripheral nerve injury (PNI). The purpose of this investigation was to determine the effect of OEC transplantation on a severe sciatic nerve (SN) lesion. OECs were injected in rats after section and 2-cm resection of the SN. Three months after therapy, muscle strength and morphometric studies showed complete restoration of the contractile properties of the gastrocnemius and complete repair of the SN. Immunohistochemistry and RT-PCR studies indicated an increase in the presence of neurotrophic factors. Interestingly, tracking of green fluorescent protein (GFP)-positive OECs showed that no OECs were present in the SN. Our results demonstrate that, after severe PNI, OECs have remarkable potential for nerve regeneration by creating a favorable microenvironment.
    Muscle & Nerve 02/2011; 43(4):543-51. · 2.31 Impact Factor
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    ABSTRACT: Although polypropylene (PP) is the most common biomaterial used for ventral and inguinal hernia repairs, its mechanical properties remain obscure. Retraction, solidity, and elasticity of 3 large pore-size monofilament PP prostheses, 1 heavy-weight PP (HWPP), a second low-weight PP, and a third coated with atelocollagen were evaluated in a rabbit incisional hernia model. A small pore-size multifilament PP implant (MPP) also was tested. Unlike pore size, the weight of the prosthesis was not an influencing factor for retraction. Atelocollagen coating reduced retraction (P < .05). HWPP and MPP were less likely to rupture (P < .05). HWPP had comparatively better elasticity (P < .05), whereas MPP supported the greatest elastic force (P < .05). Nevertheless, the amount of shrinkage of MPP (30% of the original size) made this prosthesis unusable. In this study, HWPP presented the most advantageous biomechanical compromise for hernia surgery.
    American journal of surgery 09/2010; 200(3):406-12. · 2.36 Impact Factor
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    ABSTRACT: To evaluate the biomechanical properties of the principal prosthetic materials currently used in genital prolapse surgery. Based on an animal model of incisional abdominal hernia, 40 adult rabbits were implanted. Four 2.5 cm x 2.5 cm parietal defects, were created in the abdominal fascia and muscles while respecting the peritoneum. For each rabbit, the defect was repaired by four different large pore size prostheses which varied according to the material used: two with monofilament of heavy (75 g/m(2)) or low (38 g/m(2)) weight polypropylene (PP), and two with multifilament of heavy (115 g/m(2)) or low (59 g/m(2)) weight polyethylene-terephthalate (PET). Animals were sacrificed in groups of 10 after 14, 30, 90 and 180 days to evaluate contraction, solidity and elasticity of the prostheses. PP and PET retracted, independently of their weight, in 81.25% and 20% respectively. Intensity of contraction was not predictable but median value of retracted surface was 14% with PP, none with PET. Contraction settled quickly after tissue integration and did not subsequently occur. Heavyweight PET was considered the most solid material (70 N cm(-1)), low-weight PP the most fragile (20 N cm(-1)). Heavy forms of PP or PET resisted better to the rupture than the light forms which were sometimes insufficient to resist the extreme values of the human abdominal pressure (16 N cm(-1)). PP was more flexible than PET, but PET was the only form which was able to support extreme values of the abdominal pressure and remain in the elastic range. Duration of implantation did not modify solidity or elasticity of the prostheses. In our abdominal rabbit model, as regards mechanical properties, heavyweight PET seems to be the optimal biomaterial.
    European journal of obstetrics, gynecology, and reproductive biology 09/2009; 147(1):106-10. · 1.97 Impact Factor
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    ABSTRACT: Although polypropylene (PP) is the most common biomaterial used to repair genital prolapse via vaginal route, its mechanical properties however remain obscure. An abdominal hernia rabbit model was used to evaluate retraction, solidity, and elasticity of the principal types of PP prostheses currently available, i.e., three large pore size monofilament prostheses, one heavy weight (HWPP), a second low weight (LWPP), and a third coated with atelocollagen (CPP). A small pore size multifilament PP (MPP) implant was also tested. In comparison with HWPP (12%), LWPP (15%), and MPP (30%), CPP had less retraction (8% of the original size). Unlike pore size, weight prosthesis is not an influencing factor for retraction. Atelocollagen coating reduced retraction. HWPP and MPP were the most solid prostheses. MPP supported the greatest elastic force. When the biomechanical parameters were comparatively assessed, HWPP was considered to have the most advantageous properties for prolapse surgery.
    International Urogynecology Journal 03/2009; 20(5):597-604. · 2.17 Impact Factor
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    ABSTRACT: To assess the possibilities of restoring laryngeal sensation in an animal model by way of the internal branch of the superior laryngeal nerve (ibSLN) bilateral section and anastomosis to itself or to transposition nerves (i.e., lingual, glossopharyngeal, and great auricular nerves). Prospective study using New Zealand rabbits. Six groups of rabbits were operated on and evaluated: healthy controls (n = 6); section without reinnervation (denervated group, n = 7); section and reinnervation with ibSLN (SLN-SLN group, n = 9); and section and anastomosis with the lingual nerve (lingual group, n = 7), the glossopharyngeal nerve (glossopharyngeal group, n = 6), and the great auricular nerve (GA group, n = 7). After 9 months, recovery of a laryngeal closure reflex was assessed by stimulation of the epiglottis and nerve anastomosis. Laryngeal sensation was restored in 14.3% in the denervated group, 66.6% in the SLN-SLN group, 71.4% in the lingual group, 100% in the GA group (P < .001), 50% in glossopharyngeal group. Some anastomoses were severed. When anastomosis was intact, a laryngeal closure reflex was observed in 91.7% of the rabbits of the SLN-SLN group (P < .001), 80% in the lingual group (P < .001), 100% in the GA group (P < .05) and 100% of the glossopharyngeal group. Rehabilitation of supraglottic laryngeal sensation is feasible by way of anastomosis of the ibSLN to itself, but also to the lingual, glossopharyngeal, and great auricular nerves. These results suggest that this type of procedure may be useful in humans to prevent aspiration and subsequent pneumonia as related to lesions of the laryngeal reflex pathway. It could also be considered one stage toward the functional rehabilitation of a transplanted larynx.
    The Laryngoscope 06/2007; 117(5):897-902. · 1.98 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the effects on the diaphragm of upper phrenic nerve root resections in dogs. During laryngeal reinnervation, selective resections of the upper phrenic nerve root (C5) were performed unilaterally (right side, n=7; Group A) and bilaterally (n=6; Group B) and compared to non denervated animals (n=5). After 8 months, a diaphragmatic evaluation was performed: X-ray, EMG, transdiaphragmatic pressure (Pdi) after ipsi- and bilateral tetanic stimulation of the phrenic nerves and a bilateral histological study of five hemidiaphragmatic regions. EMG alterations were significantly more severe in Group B than in Group A, for the left (p<0.05) and right hemidiaphragms (p<0.01). No differences in the X-rays were noted between the three groups. The Pdi of the three groups after occlusion and phrenic nerve stimulations (unilateral and bilateral) were not statistically different. Histological data demonstrated that there were no differences in fibre irregularity, predominant fibre type or fibrosis between the three groups. Macroscopic and microscopic atrophy, which was mainly present on the anterior regions of the hemidiaphragms, was significantly higher in Group B than in Group A and undenervated dogs (p<0.05). In conclusion, resection of the upper phrenic nerve root of one phrenic nerve (right side) have limited effect on the diaphragm in dogs. However, resection of the upper phrenic nerve root on both sides resulted in a significant effect on the EMGs and histology of the entire diaphragm without any significant consequences on transdiaphragmatic pressure.
    Respiratory Physiology & Neurobiology 01/2007; 154(3):419-30. · 2.05 Impact Factor
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    ABSTRACT: To assess the possibilities of reinnervation in a paralyzed hemidiaphragm via an anastomosis between phrenic nerve and inferior laryngeal nerve in rabbits. Reinnervation of a paralyzed diaphragm could be an alternative to treat patients with ventilatory insufficiency due to upper cervical spine injuries. Rabbits were divided into five groups of seven rabbits each. Groups I and II were respectively the healthy and the denervated control groups. The 3 other groups were all reinnervated using three different surgical procedures. In groups III and IV, phrenic nerve was respectively anastomosed with the abductor branch of the inferior laryngeal nerve and with the trunk of the inferior laryngeal nerve. In group V, the fifth and fourth cervical roots were respectively anastomosed with the abductor branch of the inferior laryngeal nerve and with the nerve of the sternothyroid muscle (originating from the hypoglossal nerve). Animals were evaluated 4 months later using electromyography, transdiaphragmatic pressure measurements, sonomicrometry and histological examination. A poor inspiratory activity was found in quiet breathing in the reinnervated groups, with an increasing pattern of activity during effort. In the reinnervated groups, transdiaphragmatic pressure measurements and sonomicrometry were higher in group III with no significant difference with groups IV and V. Inspiratory contractility of an hemidiaphragm could be restored with immediate anastomosis after phrenic nerve section between phrenic nerve and inferior laryngeal nerve.
    Respiratory research 02/2006; 7:17. · 3.64 Impact Factor
  • Revue Neurologique - REV NEUROL. 01/2004; 160(8):850-850.
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    ABSTRACT: Upper airway (UA) anatomical abnormalities are frequently observed in obstructive sleep apnea syndrome (OSAS). The correspondence between UA anatomical modifications and UA resistance (UAR) had not been studied. We aimed to determine if cephalometric characteristics could be related to segmental UAR. In twenty-five patients (21 males) (15 OSAS patients, 10 snorers) and 10 control subjects (8 males), segmental UAR were measured in supine position and cephalometry was performed. Inspiratory and expiratory UAR were calculated at peak flow. Length of the soft palate (LP), posterior airway space (PAS), distance from hyoid bone to mandibular plane and to posterior pharyngeal wall were different between the groups (P<0.01). Inspiratory and expiratory, total and segmental, UAR were higher in OSAS (P<0.001). Segmental UAR were correlated with PAS and distance from hyoid bone to mandibular plane and to pharyngeal posterior wall (P<0.05). In conclusion, OSAS patients had higher UAR depending on anatomical variables, especially the place of the hyoid bone.
    Respiration Physiology 01/2002; 129(3):335-43.
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    ABSTRACT: Ventilatory motor output is known to influence the upper airway. Although inspiratory upper airway resistance decreases during progressive hypoxia or hypercapnia, the effects of hypoxia and hypercapnia on expiratory upper airway resistance remain unknown. In the present study, we attempted to examine whether the expiratory and the inspiratory upper airway resistances were modified in the same way by progressive hyperoxic hypercapnia or by progressive normocapnic hypoxia. Nine healthy subjects (five males, four females, 33+/-9 years) participated in the study. Inspiratory upper airway (iUAR) and expiratory upper airway resistances (eUAR) were calculated at flow 300 ml x s(-1). Both resistances were obtained during a baseline period and during progressive hyperoxic hypercapnia or progressive normocapnic hypoxia. In all subjects, iUAR and eUAR decreased significantly during hypercapnic or hypoxic challenge (P<0.05). eUAR was always lower than iUAR during hypercapnic challenge (P<0.0001) and during hypoxic challenge (P<0.0001). The authors conclude that expiratory upper airway resistance, as with inspiratory resistance, decreases during progressive hypercapnia or during progressive hypoxia. Pharyngeal dilator or constrictor muscle activities may be implicated.
    Respiration Physiology 01/2001; 124(1):35-42.