Imperial College London

Dr Melissa Shea Hamilton

Faculty of MedicineDepartment of Infectious Disease

Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 3670s.hamilton Website

 
 
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Location

 

125Wright Fleming WingSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
to

8 results found

Jackson H, Menikou S, Hamilton M, McArdle A, Shimizu C, Galassini R, Huang H, Kim J, Tremoulet A, de Jonge M, Kuijpers T, Wright V, Burns J, Casals-Pascual C, Herberg J, Levin M, Kaforou Met al., 2021, Kawasaki Disease patient stratification and pathway analysis based on host transcriptomic and proteomic profiles, International Journal of Molecular Sciences, Vol: 11, Pages: 1-24, ISSN: 1422-0067

The aetiology of Kawasaki Disease (KD), an acute inflammatory disorder of childhood, remains unknown despite various triggers of KD having been proposed. Host ‘omic profiles offer insights into the host response to infection and inflammation, with the interrogation of multiple ‘omic levels in parallel providing a more comprehensive picture. We used differential abundance analysis, pathway analysis, clustering and classification techniques to explore whether the host response in KD is more similar to the response to bacterial or viral infection at the transcriptomic and proteomic levels through comparison of ‘omic profiles from children with KD to those with bacterial and viral infections. Pathways activated in patients with KD included those involved in anti-viral and anti-bacterial responses. Unsupervised clustering showed that the majority of KD patients clustered with bacterial patients on both ‘omic levels, whilst application of diagnostic signatures specific for bacterial and viral infections revealed that many transcriptomic KD samples had low probabilities of having bacterial or viral infections, suggesting that KD may be triggered by a different process not typical of either common bacterial or viral infections. Clustering based on the transcriptomic and proteomic responses during KD revealed three clusters of KD patients on both ‘omic levels, suggesting heterogeneity within the inflammatory response during KD. The observed heterogeneity may reflect differences in the host response to a common trigger, or variation dependent on different triggers of the condition.

Journal article

Morris TC, Hoggart CJ, Chegou NN, Kidd M, Oni T, Goliath R, Wilkinson KA, Dockrell HM, Sichali L, Banda L, Crampin AC, French N, Walzl G, Levin M, Wilkinson RJ, Hamilton MSet al., 2021, Evaluation of host serum protein biomarkers of tuberculosis in sub-Saharan Africa, Frontiers in Immunology, Vol: 12, Pages: 1-12, ISSN: 1664-3224

Accurate and affordable point-of-care diagnostics for tuberculosis (TB) are needed. Host serum protein signatures have been derived for use in primary care settings, however validation of these in secondary care settings is lacking. We evaluated serum protein biomarkers discovered in primary care cohorts from Africa reapplied to patients from secondary care. In this nested case-control study, concentrations of 22 proteins were quantified in sera from 292 patients from Malawi and South Africa who presented predominantly to secondary care. Recruitment was based upon intention of local clinicians to test for TB. The case definition for TB was culture positivity for Mycobacterium tuberculosis; and for other diseases (OD) a confirmed alternative diagnosis. Equal numbers of TB and OD patients were selected. Within each group, there were equal numbers with and without HIV and from each site. Patients were split into training and test sets for biosignature discovery. A nine-protein signature to distinguish TB from OD was discovered comprising fibrinogen, alpha-2-macroglobulin, CRP, MMP-9, transthyretin, complement factor H, IFN-gamma, IP-10, and TNF-alpha. This signature had an area under the receiver operating characteristic curve in the training set of 90% (95% CI 86–95%), and, after adjusting the cut-off for increased sensitivity, a sensitivity and specificity in the test set of 92% (95% CI 80–98%) and 71% (95% CI 56–84%), respectively. The best single biomarker was complement factor H [area under the receiver operating characteristic curve 70% (95% CI 64–76%)]. Biosignatures consisting of host serum proteins may function as point-of-care screening tests for TB in African hospitals. Complement factor H is identified as a new biomarker for such signatures.

Journal article

von Both U, Berk M, Agapow P-M, Wright J, Git A, Hamilton MS, Goldgof G, Siddiqui N, Bellos E, Wright V, Coin L, Newton S, Levin Met al., 2018, Mycobacterium tuberculosis Exploits a Molecular Off Switch of the Immune System for Intracellular Survival, Scientific Reports, Vol: 8, ISSN: 2045-2322

Mycobacterium tuberculosis (M. tuberculosis) survives and multiplies inside human macrophages by subversion of immune mechanisms. Although these immune evasion strategies are well characterised functionally, the underlying molecular mechanisms are poorly understood. Here we show that during infection of human whole blood with M. tuberculosis, host gene transcriptional suppression, rather than activation, is the predominant response. Spatial, temporal and functional characterisation of repressed genes revealed their involvement in pathogen sensing and phagocytosis, degradation within the phagolysosome and antigen processing and presentation. To identify mechanisms underlying suppression of multiple immune genes we undertook epigenetic analyses. We identified significantly differentially expressed microRNAs with known targets in suppressed genes. In addition, after searching regions upstream of the start of transcription of suppressed genes for common sequence motifs, we discovered novel enriched composite sequence patterns, which corresponded to Alu repeat elements, transposable elements known to have wide ranging influences on gene expression. Our findings suggest that to survive within infected cells, mycobacteria exploit a complex immune “molecular off switch” controlled by both microRNAs and Alu regulatory elements.

Journal article

Khara JS, Obuobi S, Wang Y, Hamilton MS, Robertson BD, Newton SM, Yang YY, Langford PR, Ee PLRet al., 2017, Disruption of drug-resistant biofilms using de novo designed short α-helicalantimicrobial peptides with idealized facial amphiphilicity, Acta Biomaterialia, Vol: 57, Pages: 103-114, ISSN: 1878-7568

The escalating threat of antimicrobial resistance has increased pressure to develop novel therapeutic strategies to tackle drug-resistant infections. Antimicrobial peptides have emerged as a promising class of therapeutics for various systemic and topical clinical applications. In this study, the de novo design of α-helical peptides with idealized facial amphiphilicities, based on an understanding of the pertinent features of protein secondary structures, is presented. Synthetic amphiphiles composed of the backbone sequence (X1Y1Y2X2)n, where X1 and X2 are hydrophobic residues (Leu or Ile or Trp), Y1 and Y2 are cationic residues (Lys), and n is the number repeat units (2 or 2.5 or 3), demonstrated potent broad-spectrum antimicrobial activities against clinical isolates of drug-susceptible and multi-drug resistant bacteria. Live-cell imaging revealed that the most selective peptide, (LKKL)3, promoted rapid permeabilization of bacterial membranes. Importantly, (LKKL)3 not only suppressed biofilm growth, but effectively disrupted mature biofilms after only 2 h of treatment. The peptides (LKKL)3 and (WKKW)3 suppressed the production of LPS-induced pro-inflammatory mediators to levels of unstimulated controls at low micromolar concentrations. Thus, the rational design strategies proposed herein can be implemented to develop potent, selective and multifunctional α-helical peptides to eradicate drug-resistant biofilm-associated infections.

Journal article

Lewin A, Hamilton S, Witkover A, Langford P, Nicholas R, Chataway J, Bangham CRet al., 2016, Free serum haemoglobin is associated with brain atrophy in secondary progressive multiple sclerosis [version 1; peer review: 1 approved, 2 approved with reservations], Wellcome Open Research, Vol: 1, ISSN: 2398-502X

Background A major cause of disability in secondary progressive multiple sclerosis (SPMS) is progressive brain atrophy, whose pathogenesis is not fully understood. The objective of this study was to identify protein biomarkers of brain atrophy in SPMS. Methods We used surface-enhanced laser desorption-ionization time-of-flight mass spectrometry to carry out an unbiased search for serum proteins whose concentration correlated with the rate of brain atrophy, measured by serial MRI scans over a 2-year period in a well-characterized cohort of 140 patients with SPMS. Protein species were identified by liquid chromatography-electrospray ionization tandem mass spectrometry. Results There was a significant (p<0.004) correlation between the rate of brain atrophy and a rise in the concentration of proteins at 15.1 kDa and 15.9 kDa in the serum. Tandem mass spectrometry identified these proteins as alpha-haemoglobin and beta-haemoglobin, respectively.  The abnormal concentration of free serum haemoglobin was confirmed by ELISA (p<0.001). The serum lactate dehydrogenase activity was also highly significantly raised (p<10(-12)) in patients with secondary progressive multiple sclerosis. Conclusions An underlying low-grade chronic intravascular haemolysis is a potential source of the iron whose deposition along blood vessels in multiple sclerosis plaques contributes to the neurodegeneration and consequent brain atrophy seen in progressive disease. Chelators of free serum iron will be ineffective in preventing this neurodegeneration, because the iron (Fe(2+)) is chelated by haemoglobin.

Journal article

Khara JS, Priestman M, Uhia I, Hamilton MS, Krishnan N, Wang Y, Yang YY, Langford PR, Newton SM, Robertson BD, Ee PLRet al., 2016, Unnatural amino acid analogues of membrane-active helical peptides with anti-mycobacterial activity and improved stability, Journal of Antimicrobial Chemotherapy, Vol: 71, Pages: 2181-2191, ISSN: 1460-2091

Objectives The emergence of MDR-TB, coupled with shrinking antibiotic pipelines, has increased demands for new antimicrobials with novel mechanisms of action. Antimicrobial peptides have increasingly been explored as promising alternatives to antibiotics, but their inherent poor in vivo stability remains an impediment to their clinical utility. We therefore systematically evaluated unnatural amino acid-modified peptides to design analogues with enhanced anti-mycobacterial activities.Methods Anti-mycobacterial activities were evaluated in vitro and intracellularly against drug-susceptible and MDR isolates of Mycobacterium tuberculosis using MIC, killing efficacy and intracellular growth inhibition studies. Toxicity profiles were assessed against mammalian cells to verify cell selectivity. Anti-mycobacterial mechanisms were investigated using microfluidic live-cell imaging with time-lapse fluorescence microscopy and confocal laser-scanning microscopy.Results Unnatural amino acid incorporation was well tolerated without an appreciable effect on toxicity profiles and secondary conformations of the synthetic peptides. The modified peptides also withstood proteolytic digestion by trypsin. The all D-amino acid peptide, i(llkk)2i (II-D), displayed superior activity against all six mycobacterial strains tested, with a 4-fold increase in selectivity index as compared with the unmodified L-amino acid peptide in broth. II-D effectively reduced the intracellular bacterial burden of both drug-susceptible and MDR clinical isolates of M. tuberculosis after 4 days of treatment. Live-cell imaging studies demonstrated that II-D permeabilizes the mycobacterial membrane, while confocal microscopy revealed that II-D not only permeates the cell membrane, but also accumulates within the cytoplasm.Conclusions Unnatural amino acid modifications not only decreased the susceptibility of peptides to proteases, but also enhanced mycobacterial selectivity.

Journal article

Anderson ST, Kaforou M, Brent AJ, Wright VJ, Banwell CM, Chagaluka G, Crampin AC, Dockrell HM, French N, Hamilton MS, Hibberd ML, Kern F, Langford PR, Ling L, Mlotha R, Ottenhoff THM, Pienaar S, Pillay V, Scott JAG, Twahir H, Wilkinson RJ, Coin LJ, Heyderman RS, Levin M, Eley Bet al., 2014, Diagnosis of Childhood Tuberculosis and Host RNA Expression in Africa, New England Journal of Medicine, Vol: 370, Pages: 1712-1723, ISSN: 1533-4406

Journal article

Gideon HP, Hamilton MS, Wood K, Pepper D, Oni T, Seldon R, Banwell C, Langford PR, Wilkinson RJ, Wilkinson KAet al., 2013, Impairment of IFN-Gamma Response to Synthetic Peptides of Mycobacterium tuberculosis in a 7-Day Whole Blood Assay, PLOS ONE, Vol: 8, ISSN: 1932-6203

Journal article

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