Human alveolar macrophages infected by virulent bacteria expressing SipB are a major source of active interleukin-18.

Recent publications have demonstrated that the protease caspase-1 is responsible for the processing of pro-interleukin 18 (IL-18) into the active form. Studies on cell lines and murine macrophages have shown that the bacterial invasion factor SipB activates caspase-1, triggering cell death. Thus, we investigated the role of SipB in the activation and release of IL-18 in human alveolar macrophages (AM), which are the first line of defense against inhaled pathogens. Under steady-state conditions, AM are a more important source of IL-18 than are dendritic cells (DC) and monocytes. Cytokine production by AM and DC was compared after both types of cells had been infected with a virulent strain of Salmonella enterica serovar Typhimurium and an isogenic sipB mutant, which were used as an infection model. Infection with virulent Salmonella led to marked cell death with features of apoptosis while both intracellular activation and release of IL-18 were demonstrated. In contrast, the sipB mutant did not induce such cell death or the release of active IL-18. The specific caspase-1 inhibitor Ac-YVAD-CMK blocked the early IL-18 release in AM infected with the virulent strain. However, the type of Salmonella infection did not differentially regulate IL-18 gene expression. We concluded that the bacterial virulence factor SipB plays an essential posttranslational role in the intracellular activation of IL-18 and the release of the cytokine in human AM.

Exhaustion of tumor-specific CD8⁺ T cells in metastases from melanoma patients.

In chronic viral infections, CD8⁺ T cells become functionally deficient and display multiple molecular alterations. In contrast, only little is known of self- and tumor-specific CD8⁺ T cells from mice and humans. Here we determined molecular profiles of tumor-specific CD8⁺ T cells from melanoma patients. In peripheral blood from patients vaccinated with CpG and the melanoma antigen Melan-A/MART-1 peptide, we found functional effector T cell populations, with only small but nevertheless significant differences in T cells specific for persistent herpesviruses (EBV and CMV). In contrast, Melan-A/MART-1-specific T cells isolated from metastases from patients with melanoma expressed a large variety of genes associated with T cell exhaustion. The identified exhaustion profile revealed extended molecular alterations. Our data demonstrate a remarkable coexistence of effector cells in circulation and exhausted cells in the tumor environment. Functional T cell impairment is mediated by inhibitory receptors and further molecular pathways, which represent potential targets for cancer therapy.

Peptides from Lactobacillus hydrolysates of bovine milk caseins inhibit prolyl-peptidases of human colon cells.

Prolyl-rich peptides derived from hydrolysates of bovine caseins have been previously shown to inhibit angiotensin converting enzyme (ACE) activity, suggesting that they may also be able to inhibit the enzymatic activities of prolyl-specific peptidases. This study shows that peptides derived from α(S1)-casein and β-casein inhibited the enzymatic activities of purified recombinant matrix metalloprotease (MMP)-2, MMP-7, and MMP-9. The inhibitory efficacy was sequence-dependent. These peptides also selectively inhibited the enzymatic activities of prolyl-amino-peptidases, prolyl-amino-dipeptidases, and prolyl-endopeptidases in extracts of HT-29 and SW480 human colon carcinoma cells, but not in intact cells. They were not cytotoxic or growth inhibitory for these cells. Thus, the prolyl-rich selected peptides were good and selective inhibitors of MMPs and post-proline-cleaving proteases, demonstrating their potential to control inadequate proteolytic activity in the human digestive tract, without inducing cytotoxic effects.

Therapeutic cancer vaccines based on molecularly defined human tumor antigens.

The results of numerous phases I and II clinical trials testing the safety and immunogenicity of various cancer vaccine formulations based on cytolytic T lymphocytes (CTLs)-defined tumor antigens have been reported recently. Specific T cell responses can be detected in only a fraction of immunized patients. A smaller but significant fraction of these patients have objective tumor responses. Efficient therapeutic vaccination should aim at boosting naturally occurring anti-tumor responses and at sustaining a large contingent of tumor antigen-specific and fully functional effector T cells at tumor sites.

Use of transgenic mice for the characterization of human alpha 1-acid glycoprotein (orosomucoid) variants.

Sera from transgenic mice (TM) carrying human genes of alpha 1-acid glycoprotein (orosomucoid or ORM) have been analyzed by isoelectrofocusing and subsequent immunoblotting with antihuman ORM antibodies. With this technique it is possible to reveal selectively the human protein secreted in the TM sera. Orosomucoid bands present in TM sera have been compared with those of the most common human ORM phenotypes to correlate the products of specific genes to previously identified genetic variants. In this paper, we report the identification of the genes encoding for variants ORM1 F1 and ORM2 A, which are genes AGP-A and AGP-B/B' respectively. The nucleotide sequences of these genes are known; therefore a direct correlation between variants and specific amino acid sequences can be established.

Role of hemodynamic forces in the ex vivo arterialization of human saphenous veins.

BACKGROUND: Human saphenous vein grafts are one of the salvage bypass conduits when endovascular procedures are not feasible or fail. Understanding the remodeling process that venous grafts undergo during exposure to arterial conditions is crucial to improve their patency, which is often compromised by intimal hyperplasia. The precise role of hemodynamic forces such as shear stress and arterial pressure in this remodeling is not fully characterized. The aim of this study was to determine the involvement of arterial shear stress and pressure on vein wall remodeling and to unravel the underlying molecular mechanisms. METHODS: An ex vivo vein support system was modified for chronic (up to 1 week), pulsatile perfusion of human saphenous veins under controlled conditions that permitted the separate control of arterial shear stress and different arterial pressure (7 mm Hg or 70 mm Hg). RESULTS: Veins perfused for 7 days under high pressure (70 mm Hg) underwent significant development of a neointima compared with veins exposed to low pressure (7 mm Hg). These structural changes were associated with altered expression of several molecular markers. Exposure to an arterial shear stress under low pressure increased the expression of matrix metalloproteinase (MMP)-2 and MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-1 at the transcript, protein, and activity levels. This increase was enhanced by high pressure, which also increased TIMP-2 protein expression despite decreased levels of the cognate transcript. In contrast, the expression of plasminogen activator inhibitor-1 increased with shear stress but was not modified by pressure. Levels of the venous marker Eph-B4 were decreased under arterial shear stress, and levels of the arterial marker Ephrin-B2 were downregulated under high-pressure conditions. CONCLUSIONS: This model is a valuable tool to identify the role of hemodynamic forces and to decipher the molecular mechanisms leading to failure of human saphenous vein grafts. Under ex vivo conditions, arterial perfusion is sufficient to activate the remodeling of human veins, a change that is associated with the loss of specific vein markers. Elevation of pressure generates intimal hyperplasia, even though veins do not acquire arterial markers. CLINICAL RELEVANCE: The pathological remodeling of the venous wall, which leads to stenosis and ultimately graft failure, is the main limiting factor of human saphenous vein graft bypass. This remodeling is due to the hemodynamic adaptation of the vein to the arterial environment and cannot be prevented by conventional therapy. To develop a more targeted therapy, a better understanding of the molecular mechanisms involved in intimal hyperplasia is essential, which requires the development of ex vivo models of chronic perfusion of human veins.

Simultaneous coexpression of memory-related and effector-related genes by individual human CD8 T cells depends on antigen specificity and differentiation.

Phenotypic and functional cell properties are usually analyzed at the level of defined cell populations but not single cells. Yet, large differences between individual cells may have important functional consequences. It is likely that T-cell-mediated immunity depends on the polyfunctionality of individual T cells, rather than the sum of functions of responding T-cell subpopulations. We performed highly sensitive single-cell gene expression profiling, allowing the direct ex vivo characterization of individual virus-specific and tumor-specific T cells from healthy donors and melanoma patients. We have previously shown that vaccination with the natural tumor peptide Melan-A-induced T cells with superior effector functions as compared with vaccination with the analog peptide optimized for enhanced HLA-A*0201 binding. Here we found that natural peptide vaccination induced tumor-reactive CD8 T cells with frequent coexpression of both memory/homing-associated genes (CD27, IL7R, EOMES, CXCR3, and CCR5) and effector-related genes (IFNG, KLRD1, PRF1, and GZMB), comparable with protective Epstein-Barr virus-specific and cytomegalovirus-specific T cells. In contrast, memory/homing-associated and effector-associated genes were less frequently coexpressed after vaccination with the analog peptide. Remarkably, these findings reveal a previously unknown level of gene expression diversity among vaccine-specific and virus-specific T cells with the simultaneous coexpression of multiple memory/homing-related and effector-related genes by the same cell. Such broad functional gene expression signatures within antigen-specific T cells may be critical for mounting efficient responses to pathogens or tumors. In summary, direct ex vivo high-resolution molecular characterization of individual T cells provides key insights into the processes shaping the functional properties of tumor-specific and virus-specific T cells.

Regulation of nonphosphorylated and phosphorylated forms of neurofilament proteins in the prefrontal cortex of human opioid addicts.

The neurofilament (NF) proteins (NF-H, NF-M, and NF-L for high, medium, and low molecular weights) play a crucial role in the organization of neuronal shape and function. In a preliminary study, the abundance of total NF-L was shown to be decreased in brains of opioid addicts. Because of the potential relevance of NF abnormalities in opioid addiction, we quantitated nonphosphorylated and phosphorylated NF in postmortem brains from 12 well-defined opioid abusers who had died of an opiate overdose (heroin or methadone). Levels of NF were assessed by immunoblotting techniques using phospho-independent and phospho-dependent antibodies, and the relative (% changes in immunoreactivity) and absolute (changes in ng NF/microg total protein) amounts of NF were calculated. Decreased levels of nonphosphorylated NF-H (42-32%), NF-M (14-9%) and NF-L (30-29%) were found in the prefrontal cortex of opioid addicts compared with sex, age, and postmortem delay-matched controls. In contrast, increased levels of phosphorylated NF-H (58-41%) and NF-M (56-28%) were found in the same brains of opioid addicts. The ratio of phosphorylated to nonphosphorylated NF-H in opioid addicts (3.4) was greater than that in control subjects (1.6). In the same brains of opioid addicts, the levels of protein phosphatase of the type 2A were found unchanged, which indicated that the hyperphosphorylation of NF-H is not the result of a reduced dephosphorylation process. The immunodensities of GFAP (the specific glial cytoskeletol protein), alpha-internexin (a neuronal filament related to NF-L) and synaptophysin (a synapse-specific protein) were found unchanged, suggesting a lack of gross changes in glial reaction, other intermediate filaments of the neuronal cytoskeletol, and synaptic density in the prefrontal cortex of opioid addicts. These marked reductions in total NF proteins and the aberrant hyperphosphorylation of NF-H in brains of opioid addicts may play a significant role in the cellular mechanisms of opioid addiction.

Identification of muscle-specific calpain and beta-sarcoglycan genes in progressive autosomal recessive muscular dystrophies.

The autosomal recessive forms of limb-girdle muscular dystrophies are encoded by at least five distinct genes. The work performed towards the identification of two of these is summarized in this report. This success illustrates the growing importance of genetics in modern nosology.

Comparison of aminolevulinic acid and hexylester aminolevulinate induced protoporphyrin IX distribution in human bladder cancer.

PURPOSE: Successful photodynamic therapy of epithelial cancer requires a specific photosensitization of malignant tissue. We evaluate the intensity and localization of protoporphyrin IX (PpIX) in superficial transitional cell carcinoma and nonmalignant cells of the human bladder following topical administration of its precursor, either aminolevulinic acid (ALA) or hexylester aminolevulinate (HAL). MATERIALS AND METHODS: Solutions of ALA or HAL were instilled into the bladder of 18 patients presenting with recurrent transitional cell carcinoma. The distribution of PpIX through the bladder wall was studied on frozen biopsies using fluorescence microscopy and correlated with pathological findings. RESULTS: Topical bladder instillation with 180 mmol (3%) ALA administered for 6 hours or 8 mmol (0.2%) HAL administered for 4 hours gave similar results regarding intensity and tissue distribution of PpIX fluorescence, whereas 8 mmol HAL administered for 2 hours followed by 2 hours of resting time (2+2 hours concept) induced a PpIX fluorescence twice as high. The fluorescence remained limited to cancer cells. Only a trace of PpIX fluorescence was observed in suburothelial connective tissue, that is chorion, but none in the bladder smooth muscle regardless of experiment conditions. CONCLUSIONS: HAL is an excellent precursor for PpIX synthesis in bladder cancer. With the 2+2 hour topical administration condition it yielded the highest PpIX fluorescence intensity and fluorescence contrast between normal and malignant urothelial cells. This approach allows us to optimize PpIX tissue distribution for photodynamic therapy in superficial bladder cancer.

Expression of intercellular adhesion molecule-1 in UVA-irradiated human skin cells in vitro and in vivo.

Ultraviolet A (UVA) radiation represents an important oxidative stress to human skin and certain forms of oxidative stress have been shown to modulate intercellular adhesion molecule-1 (ICAM-1) expression. ICAM-1 has been shown to play an important part in many immune reactions and the perturbations of this molecule by ultraviolet radiation could have implications in many inflammatory responses. An enhancement immunohistochemical method with avidin/biotin was used for analysing the early effects of UVA radiation on human cell cultures and human skin (340-400 nm). Both in vitro and in vivo data show that ICAM-1 staining in epidermal keratinocytes, which was expressed constitutively, decreased in a UVA dose-dependent manner. The decrease was most noted at 3-6 h following UVA radiation with some ICAM-1 staining returning by 48 h post-UVA. ICAM-1 positive staining in the dermis was specific for vascular structures and was increased 24 h after UVA radiation. Cultured dermal fibroblasts exhibited ICAM-1 staining which increased slightly within 6-48 h post-UVA radiation. As epidermal ICAM-1 expression is depleted following UVA radiation and dermal expression increases due to an increase in the vascular structures, ICAM-1 provides a valuable marker following UVA radiation in human skin that can be readily measured in situ.

Characterization of alternatively spliced products and tissue-specific isoforms of USP28 and USP25

Background: The ubiquitin-dependent protein degradation pathway is essential for the proteolysis of intracellular proteins and peptides. Deubiquitinating enzymes constitute a complex protein family involved in a multitude of cellular processes. The ubiquitin-specific proteases (UBP) are a group of enzymes whose predicted function is to reverse the ubiquitinating reaction by removing ubiquitin from a large variety of substrates. We have lately reported the characterization of human USP25, a specific-ubiquitin protease gene at 21q11.2, with a specific pattern of expression in murine fetal brains and adult testis. Results: Database homology searches at the DNA and protein levels and cDNA library screenings led to the identification of a new UBP member in the human genome, named USP28, at 11q23. This novel gene showed preferential expression in heart and muscle. Moreover, cDNA, expressed sequence tag and RT-PCR analyses provided evidence for alternatively spliced products and tissue-specific isoforms. Concerning function, USP25 overexpression in Down syndrome fetal brains was shown by real-time PCR. Conclusions: On the basis of the genomic and protein sequence as well as the functional data, USP28 and USP25 establish a new subfamily of deubiquitinating enzymes. Both genes have alternatively spliced exons that could generate protein isoforms with distinct tissue-specific activity. The overexpression of USP25 in Down syndrome fetal brains supports the gene-dosage effects suggested for other UBP members related to aneuploidy syndromes.

Similarities and differences of polyadenylation signals in human and fly.

BACKGROUND: Cleavage of messenger RNA (mRNA) precursors is an essential step in mRNA maturation. The signal recognized by the cleavage enzyme complex has been characterized as an A rich region upstream of the cleavage site containing a motif with consensus AAUAAA, followed by a U or UG rich region downstream of the cleavage site. RESULTS: We studied these signals using exhaustive databases of cleavage sites obtained from aligning raw expressed sequence tags (EST) sequences to genomic sequences in Homo sapiens and Drosophila melanogaster. These data show that the polyadenylation signal is highly conserved in human and fly. In addition, de novo motif searches generated a refined description of the U-rich downstream sequence (DSE) element, which shows more divergence between the two species. These refined motifs are applied, within a Hidden Markov Model (HMM) framework, to predict mRNA cleavage sites. CONCLUSION: We demonstrate that the DSE is a specific motif in both human and Drosophila. These findings shed light on the sequence correlates of a highly conserved biological process, and improve in silico prediction of 3' mRNA cleavage and polyadenylation sites.

PPAR alpha structure-function relationships derived from species-specific differences in responsiveness to hypolipidemic agents.

The nuclear receptor PPAR alpha is a key regulatory transcription factor in lipid homeostasis, some liver detoxification processes and the control of inflammation. Recent findings suggest that many hypolipidemic drugs and anti-inflammatory agents can potentially act by binding to PPAR alpha and inducing its activity. Here, we identify some structure-function relationships in PPAR alpha, by using the species-specific responsiveness to the two hypolipidemic agents, Wy 14,643 and 5,8,11,14-eicosatetraynoic acid (ETYA). We first show that the species-specific differences are mediated primarily via the ligand binding domain of the receptor and that these two drugs are indeed ligands of PPAR alpha. By mutagenesis analyses we identify amino acid residues in the ligand binding domains of Xenopus, mouse and human PPAR alpha, that confer preferential responsiveness to ETYA and Wy 14,643. These findings will aid in the development of new synthetic PPAR alpha ligands as effective therapeutics for lipid-related diseases and inflammatory disorders.

O-GlcNAc transferase catalyzes site-specific proteolysis of HCF-1.

The human epigenetic cell-cycle regulator HCF-1 undergoes an unusual proteolytic maturation process resulting in stably associated HCF-1(N) and HCF-1(C) subunits that regulate different aspects of the cell cycle. Proteolysis occurs at six centrally located HCF-1(PRO)-repeat sequences and is important for activation of HCF-1(C)-subunit functions in M phase progression. We show here that the HCF-1(PRO) repeat is recognized by O-linked β-N-acetylglucosamine transferase (OGT), which both O-GlcNAcylates the HCF-1(N) subunit and directly cleaves the HCF-1(PRO) repeat. Replacement of the HCF-1(PRO) repeats by a heterologous proteolytic cleavage signal promotes HCF-1 proteolysis but fails to activate HCF-1(C)-subunit M phase functions. These results reveal an unexpected role of OGT in HCF-1 proteolytic maturation and an unforeseen nexus between OGT-directed O-GlcNAcylation and proteolytic maturation in HCF-1 cell-cycle regulation.