Clinical and MRI Evolution After Local Injection of Bone Marrow-Derived Mesenchymal Stem Cells in Perianal Fistulae in Crohn's Disease: Results From a Prospective Monocentric Study.

BACKGROUND: Local injection of adipose tissue-derived mesenchymal stem cells [MSCs] is effective in fistulizing perianal Crohn's disease [CD]. Less is known about bone marrow-derived MSCs and little is known about predictive factors of response and magnetic resonance imaging [MRI] evolution of the fistulae after MSC injection. Our aims were to evaluate the safety and clinical outcome of bone marrow-derived MSC injection for perianal fistulizing CD, to evaluate the MRI evolution of the fistulae and to identify factors associated with fistula closure. PATIENTS AND METHODS: All CD patients with perianal fistula and appropriate drainage with a seton without abscess at MRI were eligible. Clinical examination, biomarkers and pelvic MRI were performed at weeks 0, 12 and 48. The clinical outcome was assessed by closure of the treated external openings at clinical examination and MRI exploration. RESULTS: Sixteen patients with a median age of 49 years and a median duration of perianal CD of 8 months were included. No unexpected safety event occurred. At weeks 12 and 48, 9/16 and 8/16 patients had complete fistula[e] closure, respectively, whereas 11/16 patients had at least partial closure. At MRI, the degree of fibrosis increased significantly after MSC injection. In total, 86% of patients with >80% of fibrosis of the fistula tract at week 48 had fistula closure. Fistula closure at week 12 was predictive of fistula closure at week 48. The MAGNIFI-CD did not change significantly over time. CONCLUSION: Open-label injection of bone marrow-derived MSCs was safe and was effective in half of the patients in fistulizing perianal CD and induced significant MRI changes associated with favourable clinical outcome.

Mesenchymal Stem Cell Injection in Crohn's Disease Strictures: A Phase I-II Clinical Study.

BACKGROUND AND AIM: Mesenchymal stem cells [MSCs] have anti-inflammatory and anti-fibrotic properties and could be a potential therapy for Crohn's disease [CD] strictures. In this phase I-II pilot trial, we assessed safety and efficacy of local MSC injection to treat CD strictures. METHODS: CD patients with a short [less than 5 cm in length] non-passable stricture accessible by ileocolonoscopy were included. Allogenic bone-marrow derived MSCs were injected in the four quadrants of the stricture. Adverse events and clinical scores were evaluated at each follow-up visit and endoscopy and magnetic resonance enterography were performed at baseline, Week [W]12 and W48. The main judgement criterion for efficacy was the complete [defined by the ability to pass the ileocolonoscope] or partial [defined by a diameter increase] resolution of the stricture at W12. Second efficacy criteria included assessment of the stricture at W48 and evolution of clinical scores at W12 and W48. RESULTS: We performed 11 MSC injections in 10 CD patients [three primary and seven anastomotic strictures; one stricture injected twice]. MSC injections were well tolerated but four hospitalisations for occlusion were reported. At W12, five patients presented a complete or partial resolution of the stricture [two complete and three partial]. Seven patients were re-evaluated at W48 [one dilated, one operated, and one lost to follow-up] and four patients had a complete resolution. The evolution of clinical scores between W0, W12, and W48 was not statistically significant. CONCLUSIONS: MSCs injection in CD stricture was well tolerated and may offer a benefit.

Biology and signal transduction pathways of the Lymphotoxin-αß/LTßR system.

This review focuses on the biological functions and signalling pathways activated by Lymphotoxin α (LTα)/Lymphotoxin ß (LTß) and their receptor LTßR. Genetic mouse models shed light on crucial roles for LT/LTßR to build and to maintain the architecture of lymphoid organs and to ensure an adapted immune response against invading pathogens. However, chronic inflammation, autoimmunity, cell death or cancer development are disorders that occur when the LT/LTßR system is twisted. Biological inhibitors, such as antagonist antibodies or decoy receptors, have been developed and used in clinical trials for diseases associated to the LT/LTßR system. Recent progress in the understanding of cellular trafficking and NF-κB signalling pathways downstream of LTα/LTß may bring new opportunities to develop therapeutics that target the pathological functions of these cytokines.

Induction of the alternative NF-κB pathway by lymphotoxin αß (LTαß) relies on internalization of LTß receptor.

Several tumor necrosis factor receptor (TNFR) family members activate both the classical and the alternative NF-κB pathways. However, how a single receptor engages these two distinct pathways is still poorly understood. Using lymphotoxin ß receptor (LTßR) as a prototype, we showed that activation of the alternative, but not the classical, NF-κB pathway relied on internalization of the receptor. Further molecular analyses revealed a specific cytosolic region of LTßR essential for its internalization, TRAF3 recruitment, and p100 processing. Interestingly, we found that dynamin-dependent, but clathrin-independent, internalization of LTßR appeared to be required for the activation of the alternative, but not the classical, NF-κB pathway. In vivo, ligand-induced internalization of LTßR in mesenteric lymph node stromal cells correlated with induction of alternative NF-κB target genes. Thus, our data shed light on LTßR cellular trafficking as a process required for specific biological functions of NF-κB.

The ARG9 gene encodes the plastid-resident N-acetyl ornithine aminotransferase in the green alga Chlamydomonas reinhardtii.

Here we report the characterization of the Chlamydomonas reinhardtii gene ARG9, encoding the plastid resident N-acetyl ornithine aminotransferase, which is involved in arginine synthesis. Integration of an engineered ARG9 cassette in the plastid chromosome of the nuclear arg9 mutant restores arginine prototrophy. This suggests that ARG9 could be used as a new selectable marker for plastid transformation.

In Chlamydomonas, the loss of ND5 subunit prevents the assembly of whole mitochondrial complex I and leads to the formation of a low abundant 700 kDa subcomplex.

In the green alga Chlamydomonas reinhardtii, a mutant deprived of complex I enzyme activity presents a 1T deletion in the mitochondrial nd5 gene. The loss of the ND5 subunit prevents the assembly of the 950 kDa whole complex I. Instead, a low abundant 700 kDa subcomplex, loosely associated to the inner mitochondrial membrane, is assembled. The resolution of the subcomplex by SDS-PAGE gave rise to 19 individual spots, sixteen having been identified by mass spectrometry analysis. Eleven, mainly associated to the hydrophilic part of the complex, are homologs to subunits of the bovine enzyme whereas five (including gamma-type carbonic anhydrase subunits) are specific to green plants or to plants and fungi. None of the subunits typical of the beta membrane domain of complex I enzyme has been identified in the mutant. This allows us to propose that the truncated enzyme misses the membrane distal domain of complex I but retains the proximal domain associated to the matrix arm of the enzyme. A complex I topology model is presented in the light of our results. Finally, a supercomplex most probably corresponding to complex I-complex III association, was identified in mutant mitochondria, indicating that the missing part of the enzyme is not required for the formation of the supercomplex.