PIK3CA gain-of-function mutation in adipose tissue induces metabolic reprogramming with Warburg-like effect and severe endocrine disruption.

PIK3CA-related overgrowth syndrome (PROS) is a genetic disorder caused by somatic mosaic gain-of-function mutations of PIK3CA. Clinical presentation of patients is diverse and associated with endocrine disruption. Adipose tissue is frequently involved, but its role in disease development and progression has not been elucidated. Here, we created a mouse model of PIK3CA-related adipose tissue overgrowth that recapitulates patient phenotype. We demonstrate that PIK3CA mutation leads to GLUT4 membrane accumulation with a negative feedback loop on insulin secretion, a burst of liver IGFBP1 synthesis with IGF-1 sequestration, and low circulating levels. Mouse phenotype was mainly driven through AKT2. We also observed that PIK3CA mutation induces metabolic reprogramming with Warburg-like effect and protein and lipid synthesis, hallmarks of cancer cells, in vitro, in vivo, and in patients. We lastly show that alpelisib is efficient at preventing and improving PIK3CA-adipose tissue overgrowth and reversing metabolomic anomalies in both animal models and patients.

Alpelisib administration reduced lymphatic malformations in a mouse model and in patients.

Lymphatic cystic malformations are rare genetic disorders mainly due to somatic gain-of-function mutations in the PIK3CA gene. These anomalies are frequently associated with pain, inflammatory flares, esthetic deformities, and, in severe forms, life-threatening conditions. There is no approved medical therapy for patients with lymphatic malformations. In this proof-of-concept study, we developed a genetic mouse model of PIK3CA-related lymphatic malformations that recapitulates human disease. Using this model, we demonstrated the efficacy of alpelisib, an approved pharmacological inhibitor of PIK3CA in oncology, in preventing lymphatic malformation occurrence, improving lymphatic anomalies, and extending survival. On the basis of these results, we treated six patients with alpelisib, including three children, displaying severe PIK3CA-related lymphatic malformations. Patients were already unsuccessfully treated with rapamycin, percutaneous sclerotherapies, and debulking surgical procedures. We assessed the volume of lymphatic malformations using magnetic resonance imaging (MRI) for each patient. Alpelisib administration was associated with improvements in the six patients. Previously intractable vascular malformations shrank, and pain and inflammatory flares were attenuated. MRI showed a decrease of 48% in the median volume of lymphatic malformations over 6 months on alpelisib. During the study, two patients developed adverse events potentially related to alpelisib, including grade 1 mucositis and diarrhea. In conclusion, this study supports PIK3CA inhibition as a promising therapeutic strategy in patients with PIK3CA-related lymphatic anomalies.

[Renal transplantation: Procedure and early follow-up]. / Transplantation rénale : réalisation et suivi précoce.

More than fifty years after the success of the two first renal transplantations in Boston and in Necker hospital in Paris, renal transplantation became the treatment of choice of end stage renal failure, because it improves not only the quality of life of the patients but also their long-term survival. In France, more than 3,700 kidney transplantations are performed every year and more than 40,000 patients are living with a functioning kidney allograft. This treatment of end stage renal disease requires a fine-tuned pre-transplant evaluation and a multidisciplinary post-transplant care in order to prevent, to detect and to treat comorbidities and complications of immunosuppression. The ambition of this manuscript is not to describe in an exhaustive way all the aspects of renal transplantation but starting from the experience of a team, recently published data, and national and international guidelines, to try to provide a synthetic and chronological view of the early post-transplant monitoring.

Targeted therapy in patients with PIK3CA-related overgrowth syndrome.

CLOVES syndrome (congenital lipomatous overgrowth, vascular malformations, epidermal naevi, scoliosis/skeletal and spinal syndrome) is a genetic disorder that results from somatic, mosaic gain-of-function mutations of the PIK3CA gene, and belongs to the spectrum of PIK3CA-related overgrowth syndromes (PROS). This rare condition has no specific treatment and a poor survival rate. Here, we describe a postnatal mouse model of PROS/CLOVES that partially recapitulates the human disease, and demonstrate the efficacy of BYL719, an inhibitor of PIK3CA, in preventing and improving organ dysfunction. On the basis of these results, we used BYL719 to treat nineteen patients with PROS. The drug improved the disease symptoms in all patients. Previously intractable vascular tumours became smaller, congestive heart failure was improved, hemihypertrophy was reduced, and scoliosis was attenuated. The treatment was not associated with any substantial side effects. In conclusion, this study provides the first direct evidence supporting PIK3CA inhibition as a promising therapeutic strategy in patients with PROS.

[Current aspects of acute humoral rejection]. / Aspects actuels des rejets aigus humoraux.

Acute clinical antibody-mediated rejection is currently defined by (1), an acute renal failure occurring during the first months following transplantation, (2), at least a microcirculation inflammation (glomerulitis and peritubular capillaritis) on kidney biopsy and (3), the presence in peripheral blood of donor specific antibodies, mostly anti-human leukocyte antigen (HLA) antibodies. The prognosis of this rejection is scored using the severity of vascular lesions and the positivity of C4d on peritubular capillaries. Recently, a subclinical variety of antibody-mediated rejection was recognized as an entity because, as the clinical rejection, it leads to chronic antibody-mediated rejection, currently the most frequent cause of graft loss. The description of these various aspects of antibody-mediated rejection allowed a better understanding of its pathophyiology that may lead in a near future to a more specific treatment.

Patchy distribution of mucosal lesions in ileal Crohn's disease is not linked to differences in the dominant mucosa-associated bacteria: a study using fluorescence in situ hybridization and temporal temperature gradient gel electrophoresis.

BACKGROUND: The mucosa-associated bacteria (MAB) are suspected of being involved in the pathogenesis of Crohn's disease. We analyzed and compared the MAB in noninflamed and inflamed ileal mucosa of Crohn's disease patients (n = 22). METHODS: Tissue samples from the inflamed ileal mucosa and from the adjacent noninflamed ileal mucosa were taken from surgical resection specimens. The MAB were investigated using fluorescence in situ hybridization with 7 group-specific probes and temporal temperature gradient gel electrophoresis (TTGE). RESULTS: Samples from both noninflamed and inflamed mucosa were obtained from 15 patients. The distribution of the bacterial populations was not different between noninflamed and inflamed mucosa. The Bacteroidetes phylum was dominant and accounted for 29% of MAB (0%-74%) in noninflamed tissues and 32% (0%-70%) in inflamed areas. The gamma Proteobacteria represented 12% (0%-70%) of MAB both in noninflamed and inflamed areas. The Clostridium coccoides group (Firmicutes phylum) represented 15% of MAB in noninflamed tissues versus 7% in inflamed areas. For most of the patients the similarity index between TTGE paired profiles was very high. CONCLUSION: The dominant MAB do not differ between noninflamed and inflamed ileal mucosa in Crohn's disease. This argues against a localized dysbiosis to explain the patchy distribution of mucosal lesions.

Differentiated thick ascending limb (TAL) cultured cells derived from SV40 transgenic mice express functional apical NHE2 isoform: effect of nitric oxide.

Studying the apical Na/H exchanger NHE2 is difficult in the intact thick ascending limb (TAL) because of its weak expression and transport activity compared with the co-expressed NHE3. From a mouse transgenic for a recombinant plasmid adeno-SV(40) (PK4), we developed an immortalized TAL cell line, referred to as MKTAL, which selectively expresses NHE2 protein and activity. The immortalized cells retain the main properties of TAL cells. They have a stable homogeneous epithelial-like phenotype, express SV(40) T antigen and exhibit polarity with an apical domain bearing few microvilli and separated from lateral domains by typical epithelial-type junctional complexes expressing ZO1 protein. Tamm-Horsfall protein is present on the apical membrane. MKTAL cells express NHE2 and NHE1 proteins but not NHE3 and NHE4, whereby NHE2 protein is expressed selectively in the apical domain of the plasma membrane. NHE2 contributed about half of the total Na/H exchange activity. mRNAs for the Na-K-2Cl cotransporter-2 (NKCC2) and the anion exchangers AE2 and AE3 were also present. While acute exposure to NO donors did not alter NHE2 activity, chronic exposure inhibited NHE2 activity selectively and down-regulated NHE2 mRNA abundance. In conclusion, MKTAL cells retain structural and functional properties of their in vivo TAL counterparts and express functional NHE2 protein in the apical membrane, which may be inhibited by NO. Thus, MKTAL cells may be an appropriate model for studying the cellular mechanisms of NHE2 regulation.