Role of the programmed death-1 pathway in regulation of alloimmune responses in vivo

Programmed death-1 (PD-1), an inhibitory receptor up-regulated on activated T cells, has been shown to play a critical immunoregulatory role in peripheral tolerance, but its role in alloimmune responses is poorly understood. Using a novel alloreactive TCR-transgenic model system, we examined the functions of this pathway in the regulation of alloreactive CD4+ T cell responses in vivo. PD-L1, but not PD-1 or PD-L2, blockade accelerated MHC class II-mismatched skin graft (bm12 (I-Abm12) into B6 (I-Ab)) rejection in a similar manner to CTLA-4 blockade. In an adoptive transfer model system using the recently described anti-bm12 (ABM) TCR-transgenic mice directly reactive to I-Abm12, PD-1 and PD-L1 blockade enhanced T cell proliferation early in the immune response. In contrast, at a later time point preceding accelerated allograft rejection, only PD-L1 blockade enhanced T cell proliferation. In addition, PD-L1 blockade enhanced alloreactive Th1 cell differentiation. Apoptosis of alloantigen-specific T cells was inhibited significantly by PD-L1 but not PD-1 blockade, indicating that PD-1 may not be the receptor for the apoptotic effect of the PD-L1-signaling pathway. Interestingly, the effect of PD-L1 blockade was dependent on the presence of CD4+ CD25+ regulatory T cells in vivo. These data demonstrate a critical role for the PD-1 pathway, particularly PD-1/PD-L1 interactions, in the regulation of alloimmune responses in vivo.     

The homozygous M712T mutation of UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase results in reduced enzyme activities but not in altered overall cellular sialylation in hereditary inclusion body myopathy

In vivo growth of bacterial flagellar filaments by self-assembly of flagellin is promoted by a capping structure composed of a pentameric assembly of hook associated protein 2 (HAP2). Isolated native filaments with intact HAP2 cap exhibited higher melting temperature (deltaTm = 4 degrees C) and significantly increased resistance against heat-induced depolymerization than non-capped ones. Reconstituted filaments were also stabilized by HAP2 binding, but the obtained filament-HAP2 complexes were less stable than native assemblies. Their fast depolymerization at elevated temperatures and sensitivity to proteolysis indicated that native-like filament-HAP2 complexes are rarely obtained by in vitro reconstitution. A procedure was developed to isolate perfectly capped native filaments to facilitate high-resolution structural analysis.     

Characterization of microsatellite DNA markers in a critically endangered species,Mekong giant catfish,Pangasianodon gigas

Microsatellite DNA markers for a critically endangered Mekong giant catfish (Pangasianodon gigas Roberts and Vidthayanon, 1991) were developed from fin clips collected from captive fish using (GT)₁₅ probe. The number of alleles per locus ranged from two to four. The expected heterozygosities ranged from 0.13 to 0.68. Also, these primers were successfully amplified in four closely related species, Pangasius bocourti, Pangasius conchophilus, Pangasius larnaudii and Pangasius sanitwongsei with the number of alleles per locus ranged from 1 to 13, 1 to 16, 1 to 12 and 1 to 4, respectively. These markers should prove to be very useful for the evaluation of genetic diversity for this species and other related Pangasius species.     

Hydrogen peroxide cleavage of the prion protein generates a fragment able to initiate polymerisation of full length prion protein

The prion protein is central to the disease pathogenesis of a variety of neurodegenerative diseases such as CJD. The protein is only able to initiate the disease process following post-translational modification. The main characteristic of this change is the ability of this altered isoform to polymerise. We wish to determine if altered cleavage of the protein could generate a protein fragment able to initiate polymerisation. During normal metabolic breakdown the protein is initially cleaved at a single site at around amino acid residue 111/112 in the mouse sequence. A second site before amino acid residue 90 has been postulated as an alternative cleavage point. We have provided evidence that hydrogen peroxide as low as 50 microM in the presence of copper, iron or manganese (but not nickel, magnesium or zinc) can cleave the recombinant protein near this site and requires a GXXH motif in the protein sequence. This reaction results in the production of 6 and 19 kDa fragments of the protein. This cleavage pattern occurs in prion proteins from different species (mouse, chicken and turtle) and is enhanced by modification of the octameric repeat region. The 19 kDa fragment produced by this reaction is protease sensitive. This fragment in a pure form caused the polymerisation of wild-type prion protein by a seeding mechanism. Therefore our results provide a possible mechanism by which altered cleavage of the prion protein could result in the kind of protein polymerisation associated with prion diseases.     

FOXP3+ cell density in lymphoid follicles from histologically normal mucosa is a strong prognostic factor in early stage colon cancer

There are few clearly established prognostic factors available to guide the use of adjuvant chemotherapy in early stage colon cancer patients. Some of the most promising candidates include the invasion of extramural blood vessels by tumour cells and the densities of FOXP3+ T regulatory cells (Tregs) in tumour and adjacent normal colonic mucosal tissue. The aim of our study was to evaluate the prognostic significance of these markers in AJCC stage II colon cancer, with particular reference to lymphoid follicles in the mucosa. Histopathological review for the presence of vascular and serosal invasion was conducted on a series of 165 stage II colon cancers treated by surgery alone. Immunohistochemical staining for FOXP3 was performed on tumour tissue and histologically normal colonic mucosa from the surgical margin. Image analysis software was used to evaluate the density of FOXP3+ cells in the tumour core, invading margin and lymphoid follicles from the colonic mucosa. For survival analysis, cases were classified into high- or low-density of FOXP3+ cells according to the median value. The mean density of FOXP3+ Tregs in lymphoid follicles was twofold and fivefold higher than in the invading margin and tumour core, respectively. Multivariate analysis identified extramural vascular invasion (HR, 2.47; 95% CI: 1.00-6.07; P?=?0.05) and high FOXP3+ cell density in lymphoid follicles (HR, 4.22; 95% CI: 1.49-11.91; P?=?0.007) as independent factors for worse survival, whereas a high frequency of lymphoid follicles in histologically normal colonic mucosa was associated with better survival (HR, 0.31; 95% CI: 0.12-0.79; P?=?0.014). Our data suggest that host factors related to the immune system have major prognostic significance in early stage colon cancer. The density of FOXP3+ cells within lymphoid follicles and the frequency of these structures in normal colonic mucosa represent novel and independent prognostic factors.     

Magnetic configuration model for the multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis

Candidatus Magnetoglobus multicellularis (CMm) is a multicellular organism in which each constituent cell is a magnetotactic bacterium. It has been observed that disaggregation of this organism provokes the death of the individual cells. The observed flagellar movement of the CMm indicates that the constituent cells move in a coordinated way, indicating a strong correlation between them and showing that this aggregate could be considered as an individual. As every constituent cell is a magnetotactic bacterium, every cell contributes with a magnetic moment vector to the resultant magnetic moment of the CMm organism that can be calculated through the vectorial sum of all the constituent magnetic moments. Scanning electron microscopy images of CMm organisms have shown that the constituent cells are distributed on a helix convoluted on a spherical surface. To analyze the magnetic properties of the distribution of magnetic moments on this curve, we calculated the magnetic energy numerically as well as the vectorial sum of the magnetic moment distribution as a function of the number of cells, the sphere radius and the number of spiral loops. This distribution proposes a magnetic organization not seen in any other living organism and shows that minimum energy configurations of magnetic moments are in spherical meridian chains, perpendicular to the helix turns. We observed that CMm has a high theoretical degree of magnetic optimization, showing that its geometrical structure is important to the magnetic response. Our results indicate that the helical structure must have magnetic significance.     

Intérêt de la ponction épididymaire et de la biopsie testiculaire systématique dans la prise en charge de l’azoospermie obstructive

Introduction

In obstructive azoospermia (OA), even if spermatozoa recovery rate are high, pregnancy rates could be lower as expected. When almost surgeons stop if they could find motile spermatozoa in the epididymis after microsurgical epididymal sperm aspiration (MESA), in our center, we add systematically a testicular biopsy with testicular sperm extraction (TESE). What are our sperm extraction rates in MESA or TESE? Are pregnancy and miscarriage rates different regarding the sperm origin?

Material and methods

A retrospective study including 48 infertile couples with ICSI because of OA. Between 2003 and 2011, each patient had a complete aetiological exploration and a surgery with the association of MESA and TESE. ICSI were asynchronous. Each time it was possible, ICSI was realized first with epididymal spermatozoa.

Results

For 48 couples, 99 ICSI were realized. Fifteen couples had 24 ICSI-TESE because no spermatozoon was found in MESA. Eleven couples had 20 ICSI-TESE because of bad quality of sperm recovered with MESA. Twenty-two couples had 22 ICSI-MESA in first intention. If failed, 11 couples had continued with 12 ICSI-MESA and 10 with 20 ICSI-TESE. Although the number of injected oocytes (7,1±4,1 vs 6,9 ±3,6 P: 0,8) and embryos (4,5±3,0 vs 4,7±2,7; P: 0,7) were not significantly different in the two ICSI groups, the number of top quality embryos (2,4±1,9 vs 3,6±2,0 P: 0,005) and frozen embryos (0,9±1,8 vs 1,7±1,9 P: 0,04) were higher in the ICSI-TESE group. Pregnancy rate per punction (58,5% vs 26,5%, P: 0,002) was higher when testicular spermatozoa were used.

Conclusion

Our approach is original with the systematic association of MESA and TESE for each OA man, when others stop surgery when they can find spermatozoa with MESA. We found that more than the half of epididymal explorations were not useful because negative or of bad quality. Embryo quality and per punction pregnancy rate were better with testicular spermatozoa. Association of MESA and TESE could improve the management of these infertile men without exposing them to an over surgical risk.     

大苞藤黄化学成分研究及其互变异构体超高效液相色谱质谱联用分析

从大苞藤黄枝叶的混合粉碎物中分离到11个化合物,运用光谱手段分别鉴定为neobractatin(1),brasixanthone B (2),5-O-methylxanthone V1 (3),10-O-methylmacluraxanthone (4),isobractatin (5),xanthone V1(6),xerophenone A (7),xerophenone B (8),bractatin (9),macluraxanthone (10)和3-O-methylneobractatin (11).本文首次应用超高效液相色谱-质谱联用技术分离了异构体7和8并测定了其精确分子量.其中化合物6～8为首次从该植物中发现.