Infection with Helicobacter pylori might curb the risk of multiple sclerosis (MS), at least in women, according to a new study.
“Our large controlled study indicates a difference in H. pylori seropositivity between Western Australian patients with MS and healthy controls, but only among females. Our observations suggest that infection with H. pylori can be a protective factor against MS risk,” stated the authors, led by Marzena J. Fabis Pedrini, Centre for Neuromuscular and Neurological Disorders, Western Australian Neuroscience Research Institute, The University of Western Australia, Sir Charles Gairdner Hospital, QEII Medical Centre, Nedlands, Australia.
A protective role of H. pylori infection is consistent with the hygiene hypothesis, which postulates that infections in early life may prime the immune system and suppress allergic and autoimmune conditions in later life, the researchers stated.
Recently, many studies have indicated a steady increase in the incidence of autoimmune diseases in developed countries, which could suggest that the concurrent decline in infectious disease prevalence might explain the increased autoimmune disease incidence.
About half of the world’s population is infected with H. pylori. “H. pylori infection is more prevalent in developing countries, while the incidence is decreasing in Western countries. The lower rate of infection with H. pylori in the West is largely attributed to higher hygiene standards and widespread use of antibiotics,” the researchers stated.
Some small studies have suggested a link between MS and early childhood infection. The Australian researchers tested 550 confirmed patients with MS and a group of 299 healthy age- and sex-matched controls for the presence of antibodies to H. pylori. The tests were done between 2007 and 2011.
The results show H. pylori seropositivity was lower in the patients with MS (16%) than in controls (21%); the decrease pertained to females (14% vs 22%) but not males (19% vs 20%). When adjusted for age at onset, year of birth, and disease duration, H. pylori seropositive females presented with a lower disability score than seronegative females; among males, the reverse was true.
There was no significant association between H. pylori seropositivity and relapse rate.
There is no obvious explanation for the gender disparity, the researchers noted, but they added that this warrants further investigation.
Rates of MS are higher in women than they are in men. Most of the increased prevalence of MS in recent years occurred in women.
The protective effects of H. pylori against MS observed only in women might partly explain the recent increase in the female-to-male ratio of MS in developed countries.
The researchers noted that “these findings lend weight to the hypothesis that past infections have a protective effect on autoimmune disease. It has already been hypothesized that should H. pylori be confirmed to have a protective effect against MS, H. pylori pharmaceutical products could provide a novel means of treatment via nanoparticle delivery to neuron-specific targets.”
The researchers published their results online January 19, 2015 in the Journal of Neurology Neurosurgery & Psychiatry.