Immune Responses Elicited in Tertiary Lymphoid Tissues Display Distinctive Features

During chronic inflammation, immune effectors progressively organize themselves into a functional tertiary lymphoid tissue (TLT) within the targeted organ. TLT has been observed in a wide range of chronic inflammatory conditions but its pathophysiological significance remains unknown. We used the rat aortic interposition model in which a TLT has been evidenced in the adventitia of chronically rejected allografts one month after transplantation. The immune responses elicited in adventitial TLT and those taking place in spleen and draining lymph nodes (LN) were compared in terms of antibody production, T cell activation and repertoire perturbations. The anti-MHC humoral response was more intense and more diverse in TLT. This difference was associated with an increased percentage of activated CD4+ T cells and a symmetric reduction of regulatory T cell subsets. Moreover, TCR repertoire perturbations in TLT were not only increased and different from the common pattern observed in spleen and LN but also “stochastic,” since each recipient displayed a specific pattern. We propose that the abnormal activation of CD4+ T cells promotes the development of an exaggerated pathogenic immune humoral response in TLT. Preliminary findings suggest that this phenomenon i) is due to a defective immune regulation in this non-professional inflammatory-induced lymphoid tissue, and ii) also occurs in human chronically rejected grafts

Antibody Vh Repertoire Differences between Resolving and Chronically Evolving Hepatitis C Virus Infections

Despite the production of neutralizing antibodies to hepatitis C virus (HCV), many patients fail to clear the virus and instead develop chronic infection and long-term complications. To understand how HCV infection perturbs the antibody repertoire and to identify molecular features of antibody genes associated with either viral clearance or chronic infection, we sequenced the V(D)J region of naïve and memory B cells of 6 persons who spontaneously resolved an HCV infection (SR), 9 patients with a newly diagnosed chronically evolving infection (CE), and 7 healthy donors. In both naïve and memory B cells, the frequency of use of particular antibody gene subfamilies and segments varied among the three clinical groups, especially between SR and CE. Compared to CE, SR antibody genes used fewer VH, D and JH gene segments in naïve B cells and fewer VH segments in memory B cells. SR and CE groups significantly differed in the frequency of use of 7 gene segments in naïve B cell clones and 3 gene segments in memory clones. The nucleotide mutation rates were similar among groups, but the pattern of replacement and silent mutations in memory B cell clones indicated greater antigen selection in SR than CE. Greater clonal evolution of SR than CE memory B cells was revealed by analysis of phylogenetic trees and CDR3 lengths. Pauciclonality of the peripheral memory B cell population is a distinguishing feature of persons who spontaneously resolved an HCV infection. This finding, previously considered characteristic only of patients with HCV-associated lymphoproliferative disorders, suggests that the B cell clones potentially involved in clearance of the virus may also be those susceptible to abnormal expansion

Theoretical and experimental study of the methane-water mixture adsorption in micropores

COMInternational audienc

Modélisation de l’adsorption de fluides dans des micropores par couplage des théories NLDFT et SAFT-VR

COMInternational audienc

A Non-Local DFT using the SAFT-VR equation of state to describe non-associating and associating monomers in confined media

COMInternational audienc

Modélisation de l’adsorption d’eau dans des micropores par couplage des théories NLDFT et SAFT-VR

COMInternational audienc

Water Vapor Adsorption/Desorption on Two Fully Characterized Commercial Activated Carbons

COMInternational audienc

Experimental and Theoretical Studies on the Mechanism of the C-S Bond Activation of PdII Thiolate/Thioether Complexes

International audienceTwo equivalents of L (L = 4-methylthio-2-thioxo-1,3-dithiole-5-thiolate or Medmit) react with cis-Pd(PR3)2Cl2 (R = Ph and Et) to afford Pd(PR3)(η1-L)(η2-L) (R = Et: 1 ; R = Ph: 2) complexes, which have been characterized by X-ray crystallography. These compounds are dynamic in solution due to an exchange of the thiomethyl groups on palladium. Variable-temperature 1H NMR spectroscopy reveals a low coalescence temperature (173 K). Treatment of Pd(diphos)Cl2 (diphos = dppe or dppm) with 2 equiv of L affords thiolato complexes Pd(dppe)(η1-L)2 (3) and Pd(dppm)(η1-L)2 (4). Whereas 3 is rigid in solution with firm η2-coordination of dppe and η1-coordination of the thiolate, two linkage isomers Pd(η2-dppm)(η1-L)2 and Pd(η1-dppm)(η1-L)(η2-L) coexist in a solution of 4. L coordinated on PdII undergoes a S-demethylation reaction leading to dithiolene complexes and MeL. This transformation requires high temperature, and its efficiency depends on the nature of the phosphines as well as the nature of the metal (Pd vs Pt). DFT calculations reveal that the most likely mechanism depends on the lability of phosphines. Starting from M(PR3)2(η1-L)2 (M= Pd and Pt; R = Ph and Et), the favored sequence implies decoordination of one triethyl phosphine (M(PEt3)(η1-L)(η2-L)2 as intermediate) or two triphenylphosphines (Pd(η2-L)2 as intermediate) followed by oxidative addition and reductive elimination (OA/RE) reactions. In the case of PEt3, this OA/RE sequence can also compete with an intramolecular nucleophilic addition (AN), which can be described as an attack of a thiolate sulfur atom on a CH3+ carbocation. An intramolecular SN2 process was found to be the most feasible, starting from M(dppe)(η1-L)2 (M= Pd and Pt), with the nucleophile approaching the thiomethyl group at an angle of 180° with respect to the CCH3–S bond. The influence of the coligand has also been studied experimentally. Structurally characterized disulfide L–L dimer has been isolated upon reaction of 2 equiv of L with MCl2 (M = Pd and Pt)

Coordination of a diphosphine-phosphine oxide to Au, Ag and Rh: When polyfunctionality rhymes with versatility

cited By 6International audienceGold, silver and rhodium complexes of the diphosphine-phosphine oxide DPPO = [o-iPr2P-(C6H4)]2P(O)Ph have been prepared and characterized. Thanks to its polyfunctional character, DPPO features versatile coordination properties. According to crystallographic data, only one phosphine moiety is engaged in coordination towards (AuCl) and [RhCl(nbd)]. However, NMR data indicate fluxional behavior in solution, as the result of the exchange between the free and coordinated phosphines around the metal. Chelating coordination via the two phosphine sites is observed towards (Au+) and (AgCl) with PMP bite angles varying from 122° to 159°. According to X-ray and theoretical analyses, the oxygen atom of the central phosphine oxide moiety points towards the metal but does not interact significantly with it. Tridentate coordination via the two phosphines as well as the oxygen atom of DPPO occurs with [Rh(CO)+], leading to an original PO(P)P pincer structure. © 2012 The Royal Society of Chemistry