Project description:The present study describes a novel xenograft-based biomarker discovery platform and proves its usefulness in the discovery of novel serum markers for prostate cancer (PCa). By immunizing immuno-competent mice with serum from nude mice bearing PCa xenografts, an antibody response against xenograft-derived antigens was elicited. By probing protein microarrays with serum from immunized mice, several PCa-derived antigens were identified, of which a subset was successfully retrieved in serum from mice bearing PCa xenografts and validated in human serum samples of PCa patients. In conclusion, this novel method allows for the identification of low abundant cancer-derived serum proteins, circumventing dynamic range and host-response issues in standard patient cohort proteomics comparisons.
Project description:The present study describes a novel xenograft-based biomarker discovery platform and proves its usefulness in the discovery of novel serum markers for prostate cancer (PCa). By immunizing immuno-competent mice with serum from nude mice bearing PCa xenografts, an antibody response against xenograft-derived antigens was elicited. By probing protein microarrays with serum from immunized mice, several PCa-derived antigens were identified, of which a subset was successfully retrieved in serum from mice bearing PCa xenografts and validated in human serum samples of PCa patients. In conclusion, this novel method allows for the identification of low abundant cancer-derived serum proteins, circumventing dynamic range and host-response issues in standard patient cohort proteomics comparisons. To perform a large-scale identification of antibodies generated against human PCa-derived proteins in the serum of immunized mice, sera from mice immunized with either depleted serum, full serum or both from PC346 and PC339-bearing mice as well as preimmune serum and serum from mice immunized with normal mouse serum were incubated onto ProtoArrays. These ProtoArrays contain approximately 8,000 partial and full-length human proteins, expressed as N-terminal glutathione S-transferase (GST) fusion proteins. To detect antibodies bound to spotted proteins, ProtoArrays were developed using a fluorescent labeled secondary antibody. Before being used for immunization, serum from xenografted mice was not treated (full) or depleted for most abundant proteins (depleted). Two arrays were hybridized with pre-immune serum and one array with serum from an immune competent mouse that was immunized with serum from a nude mouse. Six arrays were performed using serum from immune competent mice that were immunized with serum from xenograft-bearing nude mice.
Project description:Staphylococcus aureus is a leading cause of bloodstream infections worldwide. In the United States, many of these infections are caused by a strain known as USA300. Although progress has been made, our understanding of the S. aureus molecules that promote bacteremia and survival in human blood is incomplete. To that end, we analyzed the USA300 transcriptome during culture in human blood, human serum, and trypticase soy broth (TSB), a standard laboratory culture media. Notably, genes encoding several cytolytic toxins were up-regulated in human blood over time, and hlgA, hlgB, and hlgC (encoding gamma-hemolysin subunits HlgA, HlgB, and HlgC) were among the most highly up-regulated genes at all time points. Culture supernatants derived from a USA300 isogenic hlgABC-deletion strain (LAC?hlgABC) had significantly reduced capacity to form pores in human neutrophils and ultimately cause neutrophil lysis. Compared with the wild-type USA300 strain (LAC), LAC?hlgABC had modestly reduced ability to cause mortality in a mouse bacteremia model. On the other hand, wild-type and LAC?hlgABC strains caused virtually identical disease in a mouse skin infection model, and bacterial survival and neutrophil lysis after phagocytosis in vitro was similar between these strains. Comparison of the cytolytic capacity of culture supernatants from wild-type and isogenic deletion strains lacking hlgABC, lukS/F-PV (encoding PVL), and/or lukDE revealed significant functional redundancy among two-component leukotoxins in vitro. These findings may explain in part the apparent limited contribution of any single two-component leukotoxin to USA300 immune evasion and virulence. S. aureus strain USA300 transcriptome during culture in human blood, human serum, and trypticase soy broth (TSB): time course.
Project description:Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is life-threatening and occurs in up to 30% of MRSA bacteremia cases despite appropriate antimicrobial therapy. Isolates of MRSA that cause antibiotic-persistent MRSA bacteremia (APMB) typically have in vitro antibiotic susceptibilities equivalent to those causing antibiotic-resolving MRSA bacteremia (ARMB). Thus, persistence reflects host-pathogen interactions occurring uniquely in context of antibiotic therapy in vivo. However, host factors and mechanisms involved in APMB remain unclear. We compared DNA methylomes in circulating immune cells from patients experiencing APMB vs. ARMB. Overall, methylation signatures diverged in the distinct patient cohorts. Differentially methylated sites intensified proximate to transcription factor binding sites, primarily in enhancer regions. In APMB patients, significant hypo-methylation was observed in binding sites for CCAAT enhancer binding protein (C/EBP) and signal transducer / activator of transcription 1 (STAT1). In contrast, hypo-methylation in ARMB patients localized to glucocorticoid receptor and histone acetyltransferase p300 binding sites. These distinct methylation signatures were enriched in neutrophils and achieved a mean area under the curve of 0.85 when used to predict APMB using a classification model. These findings differentiate epigenotypes in patients experiencing APMB vs. ARMB, and suggest a risk stratification strategy for antibiotic persistence in patients treated for MRSA bacteremia.
Project description:The binding of serum immunoglobulins to proteins was compared using serum from after and before an immunotherapeutic intervention (donor lymphocyte infusion) in two patients who had relapsed chronic lymphocytic leukemia (CLL) after bone marrow transplant. One Invitrogen ProtoArray was used for each sample. Significant interactions were determined by comparing the before and after samples for each patient separately, using the Concentration-Dependent Analysis described in Marina et al., J Proteome Res, 2008. One sample from before and one sample from after immunotherapy were tested for each patient. Keywords: Immune response discovery
Project description:Focusing on host response to infection, we utilized a murine model to develop a blood gene expression signature that accurately classified mice with candidemia and distinguished candidemia from S. aureus bacteremia. Validation of the signature was achieved in an independent cohort of mice.
Project description:CDI HuProt™ (Human Proteome Microarray), was used to study Pituitary Adenomas PAs (Acromegaly, Cushing's and NFPA) using serum samples, from around 14 individuals (4 Healthy control, 4 Acromegaly, 3 Cushing’s and 3 NFPAs patient samples) were used study their autoantibody profiles. Patient serum samples in dilution 1:500 ratio were used for primary incubation. Secondary incubation was performed with anti-human IgG conjugated with Cy5 (Jackson Immuno Research, catalogue number 109-175-064) in 1:5000 dilutions was used. This CDI HuProt™ array was scanned with GenePix 4000B Microarray Scanner (Molecular Devices), with a PMT gain of 500, Scan Power 100 and Laser power of 1.31.
Project description:The binding of serum immunoglobulins to proteins was compared using serum from after and before an immunotherapeutic intervention (donor lymphocyte infusion) in two patients who had relapsed chronic lymphocytic leukemia (CLL) after bone marrow transplant. One Invitrogen ProtoArray was used for each sample. Significant interactions were determined by comparing the before and after samples for each patient separately, using the Concentration-Dependent Analysis described in Marina et al., J Proteome Res, 2008. One sample from before and one sample from after immunotherapy were tested for each patient. Keywords: Immune response discovery One sample from before and one sample from after immunotherapy were tested for each patient.
Project description:The opportunistic pathogen Staphylococcus aureus is carried asymptomatically by about one-third of the human population. Body sites known to be colonized by S. aureus are the skin, nasopharynx and gut. In particular, the mechanisms that allow S. aureus to pass the gut epithelial barrier and to invade the bloodstream are poorly understood. Therefore, our present study was aimed at investigating possible differences between gut-colonizing and bacteremia isolates of S. aureus. To this end, 74 gut-colonizing isolates from healthy individuals and 144 blood-culture isolates were characterized by whole-genome sequencing. Subsequently, the cellular and extracellular proteomes of six representative isolates were examined by mass spectrometry. Lastly, the virulence potential of these isolates was evaluated using infection models based on human gut epithelial cells, blood cells, and a small animal infection model. Intriguingly, our results show that gut-colonizing and bacteremia isolates with the same sequence type (ST1 or ST5) are very similar at the genomic and proteomic levels. Nonetheless, they display differences in virulence, but gut-colonizing isolates may be more virulent than bacteremia isolates and vice versa. Importantly, we show that the main decisive factor preventing infection of gut epithelial cells in vitro is the presence of a tight barrier. Based on our present observations, we propose that the integrity of the gut epithelial layer, rather than the pathogenic potential of a gut-colonizing S. aureus strain, is the main decisive factor that determines whether this colonizer will become an invasive pathogen.