Meningitis in cell culture
Dr Hadwen Trust Research Fellowship 1999 — 2003
Meningeal-meningococcal interactions in a novel primary human cell culture: the role of differential gene expression
D Ala’Aldeen, K Wooldridge, D Wells and M Taraktsoglou, Molecular Bacteriology and Immunology Group, University of Nottingham
Meningitis, inflammation of the meninges, is caused by infectious micro-organisms. Meningitis following infection by the bacterium Neisseria meningitidis can be severe and life threatening, especially in the young.
A Dr Hadwen Trust grant to Professor Ala’Aldeen’s group enabled the development a novel in vitro system for analysing Neisseria meningitidis interactions with human meningeal cells in culture, as an alternative to animal studies.
N. meningitidis is a human pathogen that does not naturally infect animals, which makes findings from animal-based studies of limited relevance to the human disease. Instead, understanding how N. meningitidis interacts with the natural host cells of the human meninges could provide clues to vital new treatments or prevention strategies.
Research funded by the Dr Hadwen Trust described the adherence of N. meningitidis to human meningeal cells in culture, and the expression of host cell genes in response to incubation with Neisseria and meningococcal secreted proteins. This work showed that pro-inflammatory and apoptosis regulating genes of host cells are affected by meningococcal challenge, and provided the first evidence that the meninges actively resist the effects of pathogenic bacteria [1-2].
Inflammation and apoptosis are key processes in determining the severity of meningitis, so identifying secreted meningococcal virulence factors and host-cell receptors and molecular signalling mechanisms is vital to understanding the disease process; and could form the basis of novel therapies.
An improved in vitro model has subsequently been created, consisting of a bilayer of human brain microvascular endothelial cells and meningeal cells, infected with meningococci. This more realistic model of the blood-brain barrier is now being used to study meningococcal pathogenesis [3].
The research group has identified a T-cell stimulating protein (TspA) of N. meningitidis that is required for optimal adhesion of meningococci to human meningothelial cells and the Hep-2 cell line [4]. They have also characterised MspA, an immunogenic autotransporter protein that mediates adhesion to human epithelial and endothelial cells in Neisseria. Interference with the normal interactions of these proteins with host cells may provide a method for preventing meningococcal disease.
These approaches have demonstrated that it is possible to reveal basic events in bacterial meningitis infection in vitro, and identify potnetial therapeutic targets without recourse to animal experiments.
References
1. Wells D, Tighe PJ, Wooldridge KG et al (2001). Differential gene expression during meningeal-meningococcal interaction: evidence for self-defence and early release of cytokines and chemokines. Infect Immun 69:2718-2722.
2. Robinson K, Taraktsoglou M, Rowe KSJ et al (2004). Secreted proteins from Neisseria meningitidis mediate differential human gene expression and immune activation. Cell Microbiol 6:927-938.
3. Taraktsoglou M, Wooldridge KG, Rittig M et al (2006). An improved in vitro model for the study of meningococcal pathogenesis. Poster at the Society for General Microbiology, 159th Meeting, September 2006.
4. Oldfield NJ, Bland SJ, Taraktsoglou M et al (2007). T-cell stimulating protein A (TspA) of Neisseria meningitidis is required for optimal adhesion to human cells. Cell Microbiol 9:463-478.
Prof Dlawer Ala’Aldeen is Professor of Clinical Microbiology and Head of the Molecular Bacteriology and Immunology Group at the University of Nottingham. He has a long-standing interest in the study of Neisseria meningitidis infections and vaccine development. In particular the pathogenesis of, and human genetic response to, Neisseria and Campylobacter infections. He has discovered and characterised several meningococcal vaccine candidates.