Surcharges en fer rares d'origine génétique (caractérisation clinique, fonctionnelle, et biologique)

L'hémochromatose génétique liée au gène HFE (HG) se caractérise par une augmentation de la saturation de la transferrine plasmatique, qui entraîne une surcharge en fer. Ces anomalies sont dues à une sécrétion basse d'hepcidine, le régulateur principal du métabolisme du fer, et définissent le phénotype d'hepcidino déficience. De nouvelles formes de surcharges en fer ayant un phénotype similaire ont été identifiées. Les mécanismes moléculaires en sont parfois mal compris. L'objectif général de ce travail a été de caractériser sur le plan clinique, fonctionnel, et biologique, des surcharges en fer rares d'origine génétique ayant pour point commun un phénotype d'hepcidino-déficience. Nous avons d'abord analysé une cohorte de patients porteurs d'une HG, forme type de l'hepcidino-déficience, et montré que la transplantation hépatique normalisait le métabolisme du fer, montrant ainsi le rôle majeur du foie dans le phénotype d'hepcidino-déficience de l'HG. Nous avons ensuite caractérisé des surcharges en fer à saturation de la transferrine élevée liées à des anomalies de transport du fer : i) nous avons rapporté un cinquième cas de mutations du gène DMT1 et montré le caractère pathogène de la mutation p.Asn491Ser ; ii) nous décrivons un groupe de 12 patients qui présentent une mutation hétérozygote du gène TF, l'augmentation de la saturation de la transferrine ne semblant pas être en rapport avec une hepcidino-déficience, et l'existence de cofacteurs pouvant faciliter la surcharge en fer. Nous avons ensuite décrit l'impact de mutations du gène TFR2, qui sont responsables d'une hepcidino déficience dont l'expression clinique est hétérogène mais qui peut être très précoce. Nous avons alors, pour préciser les mécanismes liant les mutations du gène TFR2 à une diminution anormale de l'hepcidine, montré in vitro que les mutations p.Asn12Ile et p.Gly430Arg altèrent l'adressage cellulaire de TFR2 tandis que la mutation p.Arg768Pro altère son interaction avec la transferrine. N'ayant pu parvenir à induire l'expression d'hepcidine sous l'effet de la transferrine, au contraire de certaines équipes mais en accord avec d'autres, nous n'avons pu analyser l'impact des mutations sur la transduction du signal liant TFR2 et hepcidine. Nos résultats contribuent à préciser les mécanismes impliqués dans l'apparition de surcharges en fer rares à saturation élevée de la transferrine.HFE related hemochromatosis (HH) is characterized by an increased plasma transferrin saturation level, which causes iron overload. These anomalies are due to low hepcidin secretion, the key regulator of iron metabolism, and define the hepcidin deficiency phenotype. New forms of iron overload with similar phenotype were identified, but their molecular mechanisms remain unclear. The main objective of this work was to characterize the clinical, functional, and biological aspects of rare genetic iron overload with an hepcidin deficiency phenotype. We firstly analyzed a cohort of HH patients, archetype of hepcidin-deficiency and showed that liver transplantation cured the disease, demonstrating the major role of the liver in the phenotype. We then characterized iron overloads with high transferrin saturation related to abnormalities of iron transport: i) we reported a fifth case of patient with DMT1 gene mutations and demonstrated the pathogenicity of the mutation p.Asn491Ser; ii) we described 12 patients with heterozygous mutation of the TF gene, leading to serum transferrin decrease. The increase of transferrin saturation associated to the disease does not seem to be related to a hepcidin-deficiency, and the presence of cofactors may facilitate iron overload. We then described the impact of mutations in the TFR2 gene, which induce hepcidin-deficiency whose expression is heterogeneous but that can occur in young peoples. Then we tried to clarify in vitro the mechanisms linking mutations in the TFR2 gene to an abnormal decrease of hepcidin and showed that the p.Asn12Ile and p.Gly430Arg mutations alter the TFR2 protein intracellular trafficking while the p.Arg768Pro mutation alters its interaction with transferrin. Being unable to induce expression of hepcidin in response to transferrin, unlike some authors, but in agreement with others, we were not able to analyze the impact of mutations on signal transduction toward hepcidin. Our results help to clarify the mechanisms involved in the development of iron overload in rare high saturation of transferrin.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Mouse genetic background impacts both on iron and non-iron metals parameters and on their relationships

International audienceIron is reported to interact with other metals. In addition, it has been shown that genetic background may impact iron metabolism. Our objective was to characterize, in mice of three genetic backgrounds, the links between iron and several non-iron metals. Thirty normal mice (C57BL/6, Balb/c and DBA/2; n = 10 for each group), fed with the same diet, were studied. Quantification of iron, zinc, cobalt, copper, manganese, magnesium and rubidium was performed by ICP/MS in plasma, erythrocytes, liver and spleen. Transferrin saturation was determined. Hepatic hepcidin1 mRNA level was evaluated by quantitative RT-PCR. As previously reported, iron parameters were modulated by genetic background with significantly higher values for plasma iron parameters and liver iron concentration in DBA/2 and Balb/c strains. Hepatic hepcidin1 mRNA level was lower in DBA/2 mice. No iron parameter was correlated with hepcidin1 mRNA levels. Principal component analysis of the data obtained for non-iron metals indicated that metals parameters stratified the mice according to their genetic background. Plasma and tissue metals parameters that are dependent or independent of genetic background were identified. Moreover, relationships were found between plasma and tissue content of iron and some other metals parameters. Our data: (i) confirms the impact of the genetic background on iron parameters, (ii) shows that genetic background may also play a role in the metabolism of non-iron metals, (iii) identifies links between iron and other metals parameters which may have implications in the understanding and, potentially, the modulation of iron metabolis

Pretransplant renal function according to CKD-EPI cystatin C equation is a prognostic factor of death after liver transplantation

International audienceBackground & aims - In patients with cirrhosis, cystatin C (CystC) based equations may be more accurate indicators of glomerular filtration rate (GFR) than creatinine (Pcr) based equations. Renal function before liver transplantation (LT) is thought to impact survival after LT. We aimed at assessing pretransplant creatinine and CystC based equations with respect to their predictive value on long-term survival after LT. Methods - From 2001 to 2011, CystC was determined at pre-LT evaluation in 682 patients together with GFR assessed using MDRD-4, MDRD-6, CKD-EPI-cystatin C, CKD-EPI-creatinine and CKD-EPI-creatinine-cystatin C equations. Patients were classified according to the Kidney Disease Outcomes Quality Initiative classification (KDOQI). Results - Median age at LT was 55 [49-60] years with a median MELD score of 13.5 [8.3-19.2] and a median post-transplant follow-up of 60 [26-89] months. Using CKD-EPI Cystatin C and the KDOQI classification, 21.1% of patients were stage 1, 43.1% stage 2, 29.1% stage 3 and 6.5% stage 4. Kaplan-Meier survival estimates were significantly different between KDOQI stages when determined using the CKD-EPI-CystatinC equation. This was not the case when using the other equations. At multivariate analysis, GFR and KDOQI estimated using the CKD-EPI-CystatinC equation were significantly associated with death (HR: 0.992; CI95%: 0.986-0.999 and 1.24; CI95%: 1.02-1.50 respectively). When assessed using the MDRD-4, MDRD-6, CKD-EPI-Creatinine-CystatinC and CKD-EPI-Creatinine equations GFR was not significantly associated with death. Conclusions - Estimated pre-LT renal function is predictive of post-LT survival only when assessed using the CKD-EPI cystatin C equation. This supports the use of Cystatine C and of its related equation for the assessment of renal function before liver transplantation

Comparison of reconstruction methods used during liver transplantation in case of a graft with replaced or accessory right hepatic artery:A retrospective study

Variations in graft arterial anatomy can increase the risk of postoperative hepatic arterial thrombosis (HAT), especially in presence of a replaced or accessory right hepatic artery (RHA). We retrospectively analyzed 223 cases of liver transplantations with the presence of an RHA on the graft. Patient outcomes were compared according to the four different reconstruction methods used: (i) the re-implantation of the RHA into the splenic or gastroduodenal artery (n = 106); (ii) the interposition of the superior mesenteric artery (SMA) (n = 83); (iii) dual anastomosis (n = 24); (iv) use of an aortic patch including the origins of both the SMA and the coeliac trunk (n = 10). A competing risk analysis and Inverse Probability Weighting (IPW) were used. We found that the interposition of the SMA method was associated with a significantly lower incidence of HAT, at 4.8% compared to the re-implantation method at 17.9%, dual anastomosis at 12.5%, and aortic patch at 20%, p =.03. In the competing risk analysis with IPW, the only risk factor for RHA thrombosis was the type of reconstruction. Taking the SMA interposition group as the reference, the sub-hazard ratio (sHR) was 5.05 (CI 95 [1.72; 14.78], p &lt;.01) for the re-implantation group, sHR = 2.37 (CI 95 [0.51; 11.09], p =.27) for the dual anastomosis group and sHR = 2.24 (CI 95 [0.35; 14.33], p =.40) for the aortic patch group. There were no differences for intraoperative transfusion, hospitalization duration (p =.37) or incidence of severe complications (p =.1). The long-term graft (p =.69) and patient (p =.52) survival was not different. In conclusion, the SMA interposition method was associated with a lower incidence of RHA thrombosis.</p

Comparison of reconstruction methods used during liver transplantation in case of a graft with replaced or accessory right hepatic artery:A retrospective study

Variations in graft arterial anatomy can increase the risk of postoperative hepatic arterial thrombosis (HAT), especially in presence of a replaced or accessory right hepatic artery (RHA). We retrospectively analyzed 223 cases of liver transplantations with the presence of an RHA on the graft. Patient outcomes were compared according to the four different reconstruction methods used: (i) the re-implantation of the RHA into the splenic or gastroduodenal artery (n = 106); (ii) the interposition of the superior mesenteric artery (SMA) (n = 83); (iii) dual anastomosis (n = 24); (iv) use of an aortic patch including the origins of both the SMA and the coeliac trunk (n = 10). A competing risk analysis and Inverse Probability Weighting (IPW) were used. We found that the interposition of the SMA method was associated with a significantly lower incidence of HAT, at 4.8% compared to the re-implantation method at 17.9%, dual anastomosis at 12.5%, and aortic patch at 20%, p =.03. In the competing risk analysis with IPW, the only risk factor for RHA thrombosis was the type of reconstruction. Taking the SMA interposition group as the reference, the sub-hazard ratio (sHR) was 5.05 (CI 95 [1.72; 14.78], p &lt;.01) for the re-implantation group, sHR = 2.37 (CI 95 [0.51; 11.09], p =.27) for the dual anastomosis group and sHR = 2.24 (CI 95 [0.35; 14.33], p =.40) for the aortic patch group. There were no differences for intraoperative transfusion, hospitalization duration (p =.37) or incidence of severe complications (p =.1). The long-term graft (p =.69) and patient (p =.52) survival was not different. In conclusion, the SMA interposition method was associated with a lower incidence of RHA thrombosis.</p

Therapeutic anticoagulation after liver transplantation is not useful among patients with pre-transplant Yerdel-grade I/II portal vein thrombosis:A two-center retrospective study

BACKGROUND: Portal vein thrombosis (PVT) is no longer a contraindication for liver transplantation (LT). While therapeutic anticoagulation (tAC) is recommended during the waiting period, there is no evidence for its usefulness in the prevention of PVT recurrence after LT. OBJECTIVES: The aim of our study was to evaluate the role of tAC post-LT in the prevention of PVT recurrence. PATIENTS/METHODS: All adult LTs performed in 2 high volume centres between 2003 and 2018, were retrospectively analysed. Only patients with PVT classified as Yerdel grade I or II and with standard portal reconstruction were included. PVT recurrence and tAC-associated morbidity within 1 year were compared between patients receiving tAC or not. RESULTS: During the study period, out of 2612 LTs performed, 235 (9%) patients with PVT were included. 113 patients (48.1%) received post-LT tAC (tAC group) while 122 (51.9%) did not (non-tAC group). The incidence of bleeding events was significantly higher in the tAC group (26 (23%) vs. 5 (4.1%), p<0.01) and the initial hospitalization duration was longer (21 vs. 17.5 days, p<0.01). Within the first year, PVT recurrence was observed for 9 (3.8%) patients without any difference between the tAC and non-tAC groups (6 (5.1%) vs. 3 (2.5%), p=0.39). The only identified risk factor for PVT recurrence was the recipients' age (OR=0.94, p=0.03). Graft (p=0.11) and patient (p=0.44) survival were similar between the 2 groups. CONCLUSION: Therapeutic anticoagulation is not necessary in the prevention of grade I/II PVT recurrence and is associated with higher morbidity and longer hospital stay

Therapeutic recommendations in HFE hemochromatosis for p.Cys282Tyr (C282Y/C282Y) homozygous genotype

Although guidelines are available for hereditary hemochromatosis, a high percentage of the recommendations within them are not shared between the different guidelines. Our main aim is to provide an objective, simple, brief, and practical set of recommendations about therapeutic aspects of HFE hemochromatosis for p.Cys282Tyr (C282Y/C282Y) homozygous genotype, based on the published scientific studies and guidelines, in a form that is reasonably comprehensible to patients and people without medical training. This final version was approved at the Hemochromatosis International meeting on 12th May 2017 in Los Angeles

Clinical, biological and functional characterization of rare iron overload of genetic origin

L'hémochromatose génétique liée au gène HFE (HG) se caractérise par une augmentation de la saturation de la transferrine plasmatique, qui entraîne une surcharge en fer. Ces anomalies sont dues à une sécrétion basse d'hepcidine, le régulateur principal du métabolisme du fer, et définissent le phénotype d'hepcidino déficience. De nouvelles formes de surcharges en fer ayant un phénotype similaire ont été identifiées. Les mécanismes moléculaires en sont parfois mal compris. L'objectif général de ce travail a été de caractériser sur le plan clinique, fonctionnel, et biologique, des surcharges en fer rares d'origine génétique ayant pour point commun un phénotype d'hepcidino-déficience. Nous avons d'abord analysé une cohorte de patients porteurs d'une HG, forme type de l'hepcidino-déficience, et montré que la transplantation hépatique normalisait le métabolisme du fer, montrant ainsi le rôle majeur du foie dans le phénotype d'hepcidino-déficience de l'HG. Nous avons ensuite caractérisé des surcharges en fer à saturation de la transferrine élevée liées à des anomalies de transport du fer : i) nous avons rapporté un cinquième cas de mutations du gène DMT1 et montré le caractère pathogène de la mutation p.Asn491Ser ; ii) nous décrivons un groupe de 12 patients qui présentent une mutation hétérozygote du gène TF, l'augmentation de la saturation de la transferrine ne semblant pas être en rapport avec une hepcidino-déficience, et l'existence de cofacteurs pouvant faciliter la surcharge en fer. Nous avons ensuite décrit l'impact de mutations du gène TFR2, qui sont responsables d'une hepcidino déficience dont l'expression clinique est hétérogène mais qui peut être très précoce. Nous avons alors, pour préciser les mécanismes liant les mutations du gène TFR2 à une diminution anormale de l'hepcidine, montré in vitro que les mutations p.Asn12Ile et p.Gly430Arg altèrent l'adressage cellulaire de TFR2 tandis que la mutation p.Arg768Pro altère son interaction avec la transferrine. N'ayant pu parvenir à induire l'expression d'hepcidine sous l'effet de la transferrine, au contraire de certaines équipes mais en accord avec d'autres, nous n'avons pu analyser l'impact des mutations sur la transduction du signal liant TFR2 et hepcidine. Nos résultats contribuent à préciser les mécanismes impliqués dans l'apparition de surcharges en fer rares à saturation élevée de la transferrine.HFE related hemochromatosis (HH) is characterized by an increased plasma transferrin saturation level, which causes iron overload. These anomalies are due to low hepcidin secretion, the key regulator of iron metabolism, and define the hepcidin deficiency phenotype. New forms of iron overload with similar phenotype were identified, but their molecular mechanisms remain unclear. The main objective of this work was to characterize the clinical, functional, and biological aspects of rare genetic iron overload with an hepcidin deficiency phenotype. We firstly analyzed a cohort of HH patients, archetype of hepcidin-deficiency and showed that liver transplantation cured the disease, demonstrating the major role of the liver in the phenotype. We then characterized iron overloads with high transferrin saturation related to abnormalities of iron transport: i) we reported a fifth case of patient with DMT1 gene mutations and demonstrated the pathogenicity of the mutation p.Asn491Ser; ii) we described 12 patients with heterozygous mutation of the TF gene, leading to serum transferrin decrease. The increase of transferrin saturation associated to the disease does not seem to be related to a hepcidin-deficiency, and the presence of cofactors may facilitate iron overload. We then described the impact of mutations in the TFR2 gene, which induce hepcidin-deficiency whose expression is heterogeneous but that can occur in young peoples. Then we tried to clarify in vitro the mechanisms linking mutations in the TFR2 gene to an abnormal decrease of hepcidin and showed that the p.Asn12Ile and p.Gly430Arg mutations alter the TFR2 protein intracellular trafficking while the p.Arg768Pro mutation alters its interaction with transferrin. Being unable to induce expression of hepcidin in response to transferrin, unlike some authors, but in agreement with others, we were not able to analyze the impact of mutations on signal transduction toward hepcidin. Our results help to clarify the mechanisms involved in the development of iron overload in rare high saturation of transferrin