MedicalResearch.com Interview with: Allan G Kermode MBBS MD FRACP FRCP Clinical Professor of Neuroimmunology, Murdoch University Clinical Professor of Neurology, University of Western Australia Head, Department of Neurology and Clinical Neurophysiology SCGH Centre for Neuromuscular and Neurological Disorders Australian Neuromuscular Research Institute  Sir Charles Gairdner Hospital Perth WA Australia Institute of Immunology and Infectious Diseases Murdoch University, Western Australia MedicalResearch: You found that H. pylori sero-positivity was significantly lower in female patients with MS than in female healthy controls, but you didn’t find such a trend in men with Multiple Sclerosis… Briefly, what might explain this association between H. pylori and Multiple Sclerosis in women? (i.e the hygiene hypothesis I suppose?). Prof. Kemode: There are a number of possible explanations, but we believe that the most likely is that helicobacter colonisation is a surrogate marker for the baseline levels of exposure to environmental pathogens and organisms during childhood. We have argued this point of view in our manuscript. It should be emphasised that perhaps not all exposure to infectious agents need necessarily be pathogenic, and the concept of the protobiome is an important one. Every healthy (and unhealthy) individual is host to very many organisms, with the gut having the widest diversity. Other explanations for the association might include that there is some specific antigenic interaction occurring promoting specific immune tolerance to CNS antigens, but I believe that this conclusion would be drawing a very long bow with our current stage of knowledge regarding Multiple Sclerosis. MedicalResearch: Why does this relationship exist in women but not in men? (presumably, they are exposed to the same sanitation, hygiene etc.) Prof. Kemode: This is arguably one of the most fascinating observations of our study. Historically the sex ratio in Multiple Sclerosis was equal, yet in the last 100 years the prevalence of Multiple Sclerosis has increased markedly and the majority of this increase has occurred in women such that in Australia the sex ratio F:M approximates 3:1. The fact that over the same period prevalence of helicobacter in Western countries has declined markedly is a tantalising observation. At this stage scientific knowledge has not explained the changing sex ratios in Multiple Sclerosis nor can we yet explain the strong helicobacter association in females but not males in our study, but our study provides useful navigation to direct further research. (more…)