PhD candidate, University of Cape Town
Global proteomics models functional systems biology of healthy/clinically-derived neutrophils.
Our immune system - comprising many different and interacting cell types - is what protects us from disease. It communicates bidirectionally (and powerfully) with all other body systems to determine overall health. The proteins present in an immune cell determine its function.
We identify and quantify all proteins present in an important and under-studied human immune cell type (neutrophils) from both healthy volunteers and TB/HIV-coinfected patients.
This facilitates modelling of the functional state and dynamics of these cells, which helps us to understand how TB/HIV coinfection and co-treatment impact normal neutrophil function. We hope to extend this research to understand neutrophil function as part of the complex immune cell network operating in the body.
We are particularly interested in understanding the role of neutrophils and other immune cells in complex human diseases whose underlying pathogenic mechanisms are not well understood, but are probably rooted in immune dysfunction.
Currently, we are trying to understand a systemic inflammatory syndrome called tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS), which causes significant morbidity and mortality.
TB-IRIS affects up to 50% of patients undergoing co-treatment for both TB and HIV, and neither a reliable diagnostic test nor a specific treatment exist.
Since ~80% of the world's TB/HIV coinfected population resides in sub-Saharan Africa, TB-IRIS is a particularly common problem in local areas with good access to antiretroviral therapy, such as the Western Cape.
We anticipate that an improved understanding of the immune causes of TB-IRIS will facilitate better risk-stratification, prevention, diagnosis, prognostication, and treatment.
However, the impact of research into human immune function has a much broader scope than just TB-IRIS. A deeper understanding of normal dynamic immune functioning and how this becomes dysregulated will enable public health strategies which focus more on prevention than cure, and on extremely early detection and treatment of disease.
Furthermore, given their under-studied status, neutrophils are also excellent candidates in which to observe the remaining human proteins (predicted from the genome) for whose existence experimental evidence has never before been found.
In general, systems biology strategies (such as proteomics) are our best tools for mapping and optimising the complex and dynamic function of the human body.
Abstract: CD4(+) T cells are prominent effector cells in controlling Mycobacterium tuberculosis (Mtb) infection but may also contribute to immunopathology. Studies probing the CD4(+) T cell response from individuals latently infected with Mtb or patients with active tuberculosis using either small or proteome-wide antigen screens so far revealed a multi-antigenic, yet mostly invariable repertoire of immunogenic Mtb proteins. Recent developments in mass spectrometry-based proteomics have highlighted the occurrence of numerous types of post-translational modifications (PTMs) in proteomes of prokaryotes, including Mtb. The well-known PTMs in Mtb are glycosylation, lipidation, or phosphorylation, known regulators of protein function or compartmentalization. Other PTMs include methylation, acetylation, and pupylation, involved in protein stability. While all PTMs add variability to the Mtb proteome, relatively little is understood about their role in the anti-Mtb immune responses. Here, we review Mtb protein PTMs and methods to assess their role in protective immunity against Mtb.
Pub.: 27 Aug '14, Pinned: 31 Jul '17
Abstract: Given the diverse range of transcriptional and post-transcriptional mechanisms of gene regulation, the estimates of the human proteome is likely subject to scientific surprises as the field of proteomics has gained momentum worldwide. In this regard, the establishment of the "Human Proteome Draft" using high-resolution mass spectrometry (MS), tissue microarrays, and immunohistochemistry by three independent research groups (laboratories of Pandey, Kuster, and Uhlen) accelerated the pace of proteomics research. The Chromosome Centric Human Proteome Project (C-HPP) has taken initiative towards the completion of the Human Proteome Project (HPP) so as to understand the proteomics correlates of common complex human diseases and biological diversity, not to mention person-to-person and population differences in response to drugs, nutrition, vaccines, and other health interventions and host-environment interactions. Although high-resolution MS-based and antibody microarray approaches have shown enormous promises, we are still unable to map the whole human proteome due to the presence of numerous "missing proteins." In December 2014, at the Indian Institute of Technology Bombay, Mumbai the 6(th) Annual Meeting of the Proteomics Society, India (PSI) and the International Proteomics Conference was held. As part of this interdisciplinary summit, a panel discussion session on "The Quest of the Human Proteome and Missing Proteins" was organized. Eminent scientists in the field of proteomics and systems biology, including Akhilesh Pandey, Gilbert S. Omenn, Mark S. Baker, and Robert L. Mortiz, shed light on different aspects of the human proteome drafts and missing proteins. Importantly, the possible reasons for the "missing proteins" in shotgun MS workflow were identified and debated by experts as low tissue expression, lack of enzymatic digestion site, or protein lost during extraction, among other contributing factors. To capture the missing proteins, the experts' collective view was to study the wider tissue range with multiple digesting enzymes and follow targeted proteomics workflow in particular. On the innovation trajectory from the proteomics laboratory to novel proteomics diagnostics and therapeutics in society, we will also need new conceptual frames for translation science and innovation strategy in proteomics. These will embody both technical as well as rigorous social science and humanities considerations to understand the correlates of the proteome from cell to society.
Pub.: 02 May '15, Pinned: 31 Jul '17
Abstract: The activation state of an antitumor effector T cell in a tumor depends on the sum of all stimulatory signals and inhibitory signals that it receives in the tumor microenvironment. Accumulating data address the increasing complexity of these signals produced by a myriad of immune checkpoint molecules, cytokines, and metabolites. While reductionist experiments have identified key molecules and their importance in signaling, less clear is the integration of all these signals that allows T cells to guide their responses in health and in disease. Mass spectrometry-based proteomics is well poised to offer such insights, including monitoring emergence of resistance mechanisms to immunotherapeutics during treatments. A major application of this technology is in the discovery and characterization of small-molecule agents capable of enhancing the response to immunotherapeutic agents. Such an approach would reinvigorate small-molecule drug development aimed not at tumor cells but rather at tumor-resident T cells capable of producing dramatic and durable antitumor responses.
Pub.: 18 Jun '15, Pinned: 31 Jul '17
Abstract: Biological systems are composed of numerous components of which proteins are of particularly high functional significance. Network models are useful abstractions for studying these components in context. Network representations display molecules as nodes and their interactions as edges. Because they are difficult to directly measure, functional edges are frequently inferred from suitably structured datasets consisting of the accurate and consistent quantification of network nodes under a multitude of perturbed conditions. For the precise quantification of a finite list of proteins across a wide range of samples, targeted proteomics exemplified by selected/multiple reaction monitoring (SRM, MRM) mass spectrometry has proven useful and has been applied to a variety of questions in systems biology and clinical studies. Here, we survey the literature of studies using SRM-MS in systems biology and clinical proteomics. Systems biology studies frequently examine fundamental questions in network biology, whereas clinical studies frequently focus on biomarker discovery and validation in a variety of diseases including cardiovascular disease and cancer. Targeted proteomics promises to advance our understanding of biological networks and the phenotypic significance of specific network states and to advance biomarkers into clinical use.
Pub.: 23 Jun '15, Pinned: 31 Jul '17
Abstract: Mass spectrometry (MS) -based proteomics has become an indispensable tool with broad applications in systems biology and biomedical research. With recent advances in liquid chromatography (LC) and MS instrumentation, LC-MS is making increasingly significant contributions to clinical applications, especially in the area of cancer biomarker discovery and verification. To overcome challenges associated with analyses of clinical samples (for example, a wide dynamic range of protein concentrations in bodily fluids and the need to perform high throughput and accurate quantification of candidate biomarker proteins), significant efforts have been devoted to improve the overall performance of LC-MS-based clinical proteomics platforms. Reviewed here are the recent advances in LC-MS and its applications in cancer biomarker discovery and quantification, along with the potentials, limitations and future perspectives.
Pub.: 20 Nov '15, Pinned: 31 Jul '17
Abstract: Interconnected molecular networks are at the heart of signaling pathways that mediate adaptive plasticity of eukaryotic cells. To gain deeper insights into the underlying molecular mechanisms, a comprehensive and representative analysis demands a deep and parallel coverage of a broad spectrum of molecular species. Therefore, we introduce a simultaneous metabolite, protein, lipid extraction (SIMPLEX) procedure, a novel strategy for the quantitative investigation of lipids, metabolites, and proteins. Compared with unimolecular workflows, SIMPLEX offers a fundamental turn in study design since multiple molecular classes can be accessed in parallel from one sample with equal efficiency and reproducibility. Application of this method in mass-spectrometry-based workflows allowed the simultaneous quantification of 360 lipids, 75 metabolites, and 3327 proteins from 10(6)cells. The versatility of this method is shown in a model system for adipogenesis- peroxisomal proliferator-activated receptor gamma (PPARG) signaling in mesenchymal stem cells-where we utilized SIMPLEX to explore cross-talk within and between all three molecular classes and identified novel potential molecular entry points for interventions, indicating that SIMPLEX provides a superior strategy compared with conventional workflows.
Pub.: 28 Jan '16, Pinned: 31 Jul '17
Abstract: The fourteenth NETTAB workshop, NETTAB 2014, was devoted to a range of disciplines going from structural bioinformatics, to proteomics and to integrative systems biology. The topics of the workshop were centred around bioinformatics methods, tools, applications, and perspectives for models, standards and management of high-throughput biological data, structural bioinformatics, functional proteomics, mass spectrometry, drug discovery, and systems biology.43 scientific contributions were presented at NETTAB 2014, including keynote, special guest and tutorial talks, oral communications, and posters. Full papers from some of the best contributions presented at the workshop were later submitted to a special Call for this Supplement.Here, we provide an overview of the workshop and introduce manuscripts that have been accepted for publication in this Supplement.
Pub.: 11 Mar '16, Pinned: 31 Jul '17
Abstract: The immune system is unique in its dynamic interplay between numerous cell types. However, a system-wide view of how immune cells communicate to protect against disease has not yet been established. We applied high-resolution mass-spectrometry-based proteomics to characterize 28 primary human hematopoietic cell populations in steady and activated states at a depth of >10,000 proteins in total. Protein copy numbers revealed a specialization of immune cells for ligand and receptor expression, thereby connecting distinct immune functions. By integrating total and secreted proteomes, we discovered fundamental intercellular communication structures and previously unknown connections between cell types. Our publicly accessible (http://www.immprot.org/) proteomic resource provides a framework for the orchestration of cellular interplay and a reference for altered communication associated with pathology.
Pub.: 07 Mar '17, Pinned: 31 Jul '17