Alternative endogenous protein processing via an autophagy-dependent pathway compensates for Yersinia-mediated inhibition of endosomal major histocompatibility complex class II antigen presentation.

Extracellular Yersinia pseudotuberculosis employs a type III secretion system (T3SS) for translocating virulence factors (Yersinia outer proteins [Yops]) directly into the cytosol of eukaryotic cells. Recently, we used YopE as a carrier molecule for T3SS-dependent secretion and translocation of listeriolysin O (LLO) from Listeria monocytogenes. We demonstrated that translocation of chimeric YopE/LLO into the cytosol of macrophages by Yersinia results in the induction of a codominant antigen-specific CD4 and CD8 T-cell response in orally immunized mice. In this study, we addressed the requirements for processing and major histocompatibility complex (MHC) class II presentation of chimeric YopE proteins translocated into the cytosol of macrophages by the Yersinia T3SS. Our data demonstrate the ability of Yersinia to counteract exogenous MHC class II antigen presentation of secreted hybrid YopE by the action of wild-type YopE and YopH. In the absence of exogenous MHC class II antigen presentation, an alternative pathway was identified for YopE fusion proteins originating in the cytosol. This endogenous antigen-processing pathway was sensitive to inhibitors of phagolysosomal acidification and macroautophagy, but it did not require the function either of the proteasome or of transporters associated with antigen processing. Thus, by an autophagy-dependent mechanism, macrophages are able to compensate for the YopE/YopH-mediated inhibition of the endosomal MHC class II antigen presentation pathway for exogenous antigens. This is the first report demonstrating that autophagy might enable the host to mount an MHC class II-restricted CD4 T-cell response against translocated bacterial virulence factors. We provide critical new insights into the interaction between the mammalian immune system and a human pathogen.

CCR5 status and metastatic progression in colorectal cancer.

Multiple reports have highlighted the importance of the local immunological cellular composition (i.e. the density of effector T cells and macrophage polarization state) in predicting clinical outcome in advanced metastatic stage of colorectal cancer. However, in spite of the general association between a high effector T cell density and improved outcome, our recent work has revealed a specific lymphocyte-driven cancer cell-supporting signal. Indeed, lymphocyte-derived CCL5 supports CCR5-positive tumor cell proliferation and thereby fosters tumor growth in metastatic liver lesions. Upon systematic analysis of CCR5 expression by tumor cells using immunohistochemistry, we observed that the intensity of CCR5 increases with primary tumor size and peaks in T4 tumors. In liver metastases however, though CCR5 expression intensity is globally heightened compared to primary tumors, alterations in the expression patterns appear, leading to "patchiness" of the stain. CCR5 patchiness is, therefore, a signature of liver metastases in our cohort (n = 97 specimens) and relates to globally decreased expression intensity, but does not influence the extent of the response to CCR5 inhibitor Maraviroc in patients. Moreover, CCR5 patchiness relates to a poor immune landscape characterized by a low cytotoxic-to-regulatory T cell ratio at the invasive margin and enriched cellular and molecular markers of macrophage M2 polarization. Finally, because higher numbers of PD-1- and CTLA-4-positive cells surround tumors with patchy CCR5 expression, one can speculate that these tumors potentially respond to immune checkpoint blockade. This hypothesis is corroborated by the prolonged disease-free survival and disease-specific survival observed in patients with low gene expression of CCR5 in metastases from two publically available cohorts. These observations highlight the complex role of the CCL5-CCR5 axis in CRC metastatic progression and warrant further investigations.

Comparative integromics on the breast cancer-associated gene KIAA1632: clues to a cancer antigen domain.

Sequence analysis of protein-coding human genes in human breast and colorectal cancer recently identified the KIAA1632 gene as a potential contributor to neoplastic processes in breast cancer. In the present study, we characterized the KIAA1632 gene by computational methods: detailed investigation of the genomic structure, protein prediction, identification of orthologs in other species and phylogenetic analysis. The human KIAA1632 gene was located within human genome sequence AC090355 and consists of 44 exons. KIAA1632 is located on chromosome 18q12.3-q21.1. These findings were determined by aligning the potential full-length transcript NM_020964 to the genomic sequence. The existing predicted gene model could be refined based on these alignments (using additional EST data). Protein sequence was predicted from the full-length transcript and possible orthologs in other species were identified. Using rigorous phylogenetic methods we were able to draw conclusions about the evolutionary history of these proteins. Comparison of the protein sequences of KIAA1632 and its orthologs revealed a shared 'signature motif'. This 'signature motif' was found in three well-characterized cancer antigens, raising the hypothesis of a common 'signature motif' for a certain group of cancer antigens.

Rapid genotyping of lipopolysaccharide-binding protein (LBP) C(1341)-->T (Leu(436)-->Phe) polymorphism by LightCycler real-time PCR.

Lipopolysaccharide (LPS) is an exdotoxin found in the outer membrane of gram-negative bacteria. In circulation, LPS is bound by LPS-binding protein (LBP), which participates in cell activation by transferring LPS to CD14 and Toll-like receptor 4. A high LPS concentration may give rise to an exaggerated immune response, which may lead to septic shock during septicemia. However, LBP also neutralizes and removes LPS by transferring it to plasma lipoproteins. Recently, the presence of an amino acid-changing polymorphism in the LBP gene was reported, which, in men, was associated with sepsis and its severity and with myocardial infarction. Here, we describe a new LightCycler real-time PCR method for genotyping this LBP C(1341)-->T (Leu(436)-->Phe) polymorphism. In our study population of 393 Finnish blood donors, the genotype frequencies were: 86% TT, 13% CT and 1% CC.

Identification and characterization of the human StARD9 gene in the LGMD2A-region on chromosome 15q15 by in silico methods.

StAR (steroidogenic acute regulatory) proteins and proteins with StAR-related lipid transfer (START) domains are involved in lipid transport and metabolism, signal transduction, and transcriptional regulation. In this present study we characterized the StARD9 gene by bioinformatical methods. The human StARD9 gene (syn. KIAA1300), consisting of 11 exons, was located within human genome sequence CTD-2036P10 (AC090510). The complete coding sequence of human StARD9 cDNA was determined by DKFZp781J069 cDNA (CR749416), which was identified by using a partial coding sequence of human StARD9 cDNA (AB037721) as a query. The existing predicted gene model could be refined based on EST-analysis. Comparison of the human protein sequence with chimpanzee, rat, mouse and chicken homologs showed a 98% (chimpanzee), 60% (rat), 60% (mouse) and 45% (chicken) amino-acid identity respectively. A lipid-binding START domain was identified within StARD9 protein. This is the first report on characterization of the StARD9 gene.

Familial clustering of Leiomyomatosis peritonealis disseminata: an unknown genetic syndrome?

BACKGROUND: Leiomyomatosis peritonealis disseminata (LPD) is defined as the occurrence of multiple tumorous intraabdominal lesions, which are myomatous nodules. LPD is a rare disease with only about 100 cases reported. The usual course of LPD is benign with the majority of the patients being premenopausal females. Only two cases involving men have been reported, no syndrome or familial occurrence of LPD has been described. CASE PRESENTATION: We describe a Caucasian-American family in which six members (three men) are diagnosed with Leiomyomatosis peritonealis disseminata (LPD) and three deceased family members most likely had LPD (based on the autopsy reports). Furthermore we describe the association of LPD with Raynaud's syndrome and Prurigo nodularis. CONCLUSION: Familial clustering of Leiomyomatosis peritonealis disseminata (LPD) has not been reported so far. The etiology of LPD is unknown and no mode of inheritance is known. We discuss possible modes of inheritance in the presented case, taking into account the possibility of a genetic syndrome. Given the similarity to other genetic syndromes with leiomyomatosis and skin alterations, we describe possible similar genetic pathomechanisms.

Linkage of bacterial protein synthesis and presentation of MHC class I-restricted Listeria monocytogenes-derived antigenic peptides.

The processing and MHC class I-restricted presentation of antigenic peptides derived from the p60 protein of the facultative intracellular bacterium Listeria monocytogenes is tightly linked to bacterial protein synthesis. We used non-linear regression analysis to fit a mathematical model of bacterial antigen processing to a published experimental data set showing the accumulation and decay of p60-derived antigenic peptides in L. monocytogenes-infected cells. Two alternative models equally describe the experimental data. The simulation accounting for a stable and a hypothetical rapidly degraded form of antigen predicts that the antigenic peptides p60 217-225 and p60 449-457 are derived from a putative instable form of p60 with an average intracellular half-life of approximately 3 minutes accounting for approximately 31% of all p60 molecules synthesized. The alternative model predicts that both antigenic peptides are processed from p60 degraded intracellularly with a half-life of 109 min and that antigen processing only occurs as long as bacterial protein synthesis is not inhibited. In order to decide between both models the intracellular accumulation of p60 in infected cells was studied experimentally and compared with model predictions. Inhibition of p60 degradation by the proteasome inhibitor epoxomicin revealed that during the first 3 h post infection approximately 30% of synthesized p60 molecules were degraded. This value is significantly lower than the approximately 50% degradation of p60 that would be expected in the presence of the predicted putative short-lived state of p60 and also fits precisely with the predictions of the alternative model, indicating that the tight connection of bacterial protein biosynthesis and antigen processing and presentation of L. monocyctogenes-derived antigenic peptides is not caused by the presence of a highly instable antigenic substrate.

Quantification of prognostic immune cell markers in colorectal cancer using whole slide imaging tumor maps.

OBJECTIVE: To analyze intratumoral heterogeneity of immune cells and the resulting impact of heterogeneity on the level of individual patient prediction. STUDY DESIGN: Using whole slide imaging by virtual microscopy, we present the first spatial quantitative study of immune cells in a set of colorectal cancer primary tumors. We generated "tumor maps" based on cell densities in fields of 1 mm2, visualizing intratumoral heterogeneity. In this example, cutoffs of marker-based cell stains identified by tissue microarray (TMA) led to ambiguous decisions in 11 of the 20 patients studied. Classic TMA analysis can be used in large patient cohorts to generate clinically significant predictors. The transfer of these predictors from large-scale TMA to individualized predictions thus far has not been investigated. In colorectal cancer, TMA-based quantitative immune cell counts using immune cell surface molecules (CD3, CD8, Granzyme B, and CD45RO) have been shown to be potentially better predictors for patient survival than the classical TNM system. RESULTS: Our results make clear that for individualized prognostic evaluations, whole slide imaging by virtual microscopy is irreplaceable during identification of prognostic markers as well as in their subsequent application. CONCLUSION: In the future, spatial marker signatures could contribute to individual patient classifiers.

Role of tripeptidyl peptidase II in the processing of Listeria monocytogenes-derived MHC class I-presented antigenic peptides.

The effective control of the infection of mice with the facultatively intracellular bacterium Listeria monocytogenes requires CD8 T cells which recognize bacterial antigenic peptides presented in the context of host MHC class I molecules. It is generally accepted that bacterial antigens are processed by the proteasome, a proteolytic cytoplasmic multiprotein complex. We observed that presentation of the L. monocytogenes-derived CD8 T cell epitope LLO 91-99 by infected cells can not be totally suppressed by inhibitors of the proteasome alone. Further analysis revealed that inhibitors of the cytoplasmic tripeptidyl peptidase II suppressed the presentation of the epitopes LLO 91-99 and p60 449-457. While significant suppression of the presentation of LLO 91-99 required the simultaneous inhibition of the proteasome and tripeptidyl peptidase II, presentation of p60 449-457 was suppressed by inhibitors of either the proteasome or TPPII alone. Thus, these data indicate that both, the proteasome and tripeptidyl protease II play a role in the processing of L. monocytogenes-derived antigenic peptides.