FIZZ1 potentiates the carbachol-induced tracheal smooth muscle contraction.

FIZZ1 is an adipokine highly expressed under inflammatory conditions, and yet, little is known of its function. In this study we examine the expression and function of FIZZ1 in an ovalbumin mouse model of asthma. Trachea from naïve or ovalbumin-sensitised and -challenged mice were compared for transcriptional, functional and proteomic differences using gene microarrays, ex vivo tracheal contraction, immunohistochemistry and Western blot analysis. FIZZ1 was expressed in ovalbumin-treated, but not naïve, trachea. Naïve trachea incubated with recombinant FIZZ1 exhibited denuded epithelium and contractile hyperresponsiveness. The FIZZ1-incubated trachea also exhibited an associated increased expression of phospho-c-Raf, phospho-extracellular signal-regulated kinase 1/2, phospho-p38, MLCK and MLC-20. These data demonstrate that FIZZ1 regulates tracheal smooth muscle contraction through impairment of the epithelium and activation of the mitogen-activated protein kinase pathway in muscle.

Engagement of the PD-1 immunoinhibitory receptor by a novel B7 family member leads to negative regulation of lymphocyte activation.

PD-1 is an immunoinhibitory receptor expressed by activated T cells, B cells, and myeloid cells. Mice deficient in PD-1 exhibit a breakdown of peripheral tolerance and demonstrate multiple autoimmune features. We report here that the ligand of PD-1 (PD-L1) is a member of the B7 gene family. Engagement of PD-1 by PD-L1 leads to the inhibition of T cell receptor-mediated lymphocyte proliferation and cytokine secretion. In addition, PD-1 signaling can inhibit at least suboptimal levels of CD28-mediated costimulation. PD-L1 is expressed by antigen-presenting cells, including human peripheral blood monocytes stimulated with interferon gamma, and activated human and murine dendritic cells. In addition, PD-L1 is expressed in nonlymphoid tissues such as heart and lung. The relative levels of inhibitory PD-L1 and costimulatory B7-1/B7-2 signals on antigen-presenting cells may determine the extent of T cell activation and consequently the threshold between tolerance and autoimmunity. PD-L1 expression on nonlymphoid tissues and its potential interaction with PD-1 may subsequently determine the extent of immune responses at sites of inflammation.

Comparison of staples and sutures for cardiorrhaphy in traumatic puncture wounds of the heart.

The purpose of this study was to compare the traditional method for repair of cardiac lacerations using sutures and pledgets (S/P) with repair using a skin stapling device (SSD) performed by emergency medicine residents. In a prospective, randomized, non-blinded animal study, 20 anesthetized mongrel dogs were instrumented and underwent left lateral thoracotomy, pericardiotomy, and cardiac exposure. In set 1, a standardized 8-mm right ventricular stab wound was made with a #10 scalpel; emergency medicine residents then immediately performed emergent cardiorrhaphy by either S/P (n = 5) or SSD (n = 5) technique. In set 2, 10 dogs received standardized 8-mm right ventricular stab wounds followed by repair and then received a second stab wound to the same right ventricle that was subsequently repaired by the same operator using the alternate technique. All dogs were observed for 60 min for gross blood loss, hemodynamic instability, and integrity of repair. The results demonstrate that SSD cardiorrhaphy was significantly faster (29 +/- 11 sec in set 1; 14 +/- 6 sec in set 2) than S/P repair (201 +/- 10 sec in set 1; 196 +/- 59 sec in set 2). No appreciable differences in blood loss or repair integrity were noted in either group. Two operators in the S/P group suffered needle puncture injuries. In conclusion, cardiorrhaphy by SSD is faster to perform, has similar repair integrity, and has less risk of accidental contaminated needle injury than does traditional S/P repair when performed by emergency medicine residents.

The cloning of CD70 and its identification as the ligand for CD27.

CD70 is a surface Ag found on activated but not resting T and B lymphocytes. The biologic activity of this Ab-defined cell surface molecule on lymphocytes has not been established. Therefore, in an effort to understand the function of the CD70 protein, a mAb defining the CD70 Ag was used to isolate by expression cloning the cDNA responsible for the CD70 molecule. The predicted protein product is a type II transmembrane protein. Bioassays demonstrated that the CD70 cDNA clone expressed in African green monkey kidney cells would induce the proliferation of PHA-costimulated T cells. Comparison with known sequences indicates identity with the CD27 ligand. Therefore the molecule defining the CD70 Ag is identical to the recently defined ligand for CD27.

Identification and structural analysis of residues in the V1 region of CD4 involved in interaction with human immunodeficiency virus envelope glycoprotein gp120 and class II major histocompatibility complex molecules.

The human CD4 molecule binds both human immunodeficiency virus envelope protein gp120 and class II major histocompatibility complex (MHC) molecules. We have studied a series of mutants in the region of amino acids 42-49 of CD4 for their ability to bind gp120, to interact with class II MHC, to enhance T-cell activation, and to bind a panel of anti-CD4 antibodies. The mutation Q40P (Gln40----Pro) and the deletion d42-49 were found to disrupt most antibody epitopes in the V1 domain of CD4, suggesting major conformational changes, whereas mutants F43L, G47R, and P48S retained the binding of most of the anti-CD4 antibodies tested. The mutants d42-49, Q40P, F43L, and G47R lost both gp120 and class II MHC binding as well as the ability to enhance T-cell activation. In contrast, the mutation P48S affected neither gp120 binding, nor class II MHC binding, nor T-cell activation. We conclude that within this region the binding sites for gp120 and for class II MHC molecules overlap and that amino acids Phe43 and Gly47 comprise an intimate part of both binding sites. These observations are consistent with a three-dimensional model of the V1 domain of CD4 that was developed in order to understand the structural basis for binding to CD4.

Possible mechanisms by which the H-2Kbm3 mutation may decrease cytotoxic T-lymphocyte recognition of vesicular stomatitis virus nucleoprotein antigen.

Spleen cells from C57BL/6 (B6) mice generate a strong in vitro cytotoxic T-lymphocyte (CTL) response specific for vesicular stomatitis virus (VSV). Spleen cells from VSV-primed B6-H-2bm3 (bm3) mice, which have a mutation in H-2Kb, require approximately 10-fold more UV-inactivated VSV to generate in vitro secondary anti-VSV CTL, compared with spleen cells from primed B6 mice. Anti-VSV CTL elicited in both bm3 and B6 mice are primarily specific for the viral nucleocapsid protein (N protein), as demonstrated by using recombinant vaccinia viruses that express the VSV N protein. bm3 CTL were found to exhibit only a very low level of lytic activity when tested against autologous VSV-infected concanavalin A spleen cell blasts as well as several H-2b tumor cell lines. The weak anti-VSV response of bm3 CTL was found to be the result of a combination of inefficient recognition of VSV-infected target cells and decreased elicitation of secondary effector cells. VSV-infected bm3 target cells were not killed as well as B6 targets by either bm3 or B6 effectors. This is because of the inefficient recognition of targets, as demonstrated by the fact that VSV-infected bm3 cells were unable to competitively inhibit the lysis of VSV-infected B6 target cells by either bm3 or B6 effectors. By using cells from recombinant mice, it was shown that the CTL response restricted by H-2Kb was low in the bm3 mice, compared with that of the B6 mice. However, the H-2Db-restricted CTL activity was similarly low in both the B6 and bm3 mice. The possibility that the low response to VSV-infected bm3 cells is caused by differences between the bm3 and B6 cells in expression of either viral antigens or H-2K was investigated by radiolabeling and immunoprecipitation. VSV-infected B6 and bm3 cells were found to express equivalent levels of both viral antigens and H-2K. These results indicate that the bm3 mutation alters a functional site on the H-2Kb molecule that is involved in the recognition of VSV-infected cells. The observation that elicitation of bm3 CTL can occur at high antigen doses further suggests that the bm3 mutation results in a lower affinity of H-2K either for viral antigen or for receptor sites on the CTL.