Infections and allergies: a cross-generational riddle

Summary

Parasites and allergies, parents and children, female and male—in studies led by researchers from the Universities of Bergen, Cape Town, and Southampton, these pairings have been found to interact in some unexpected and as yet unexplained ways. With support from a WUN Sustainability Grant, the group is continuing work to understand how exposure to helminths affects susceptibility to allergies. Their interdisciplinary work blends public health, pulmonary health, immunology, ecology, and epigenetics. Click here to read more about the insights and future plans of the research group on Helminths and Allergy in South Africa and Northern Europe.

Full story 

‘It is all a riddle.’ That is how Professor Cecilia Svanes (University of Bergen) summed up the complexities that the research group on Helminths and Allergy in South Africa and Northern Europe has uncovered. The group formed in 2015 to investigate whether exposure to helminths—parasitic worms that live inside their hosts—might have benefits in reducing allergy rates. Their findings to date suggest the opposite.

Their research addresses pressing global issues by combining health contexts not often studied together. On one hand, some lower-income societies have prominent and severe problems with helminths, but lower allergy rates. On the other, higher-income societies have rapidly rising allergy rates but are often assumed to have broken the chain of helminth infection due to successive public health interventions.

In their study of exposure in Norway to Toxocara, a worm that prefers living in animals, the group found higher levels of Toxocara exposure than expected and a strong association between that exposure and increased susceptibility to allergies. Strikingly, however, Toxocara exposure in parents did not appear to affect their own allergies, but rather was related to aggravated allergies among their offspring. These correlations occurred in a sex-specific pattern: fathers’ exposure was related to an increased risk of allergy in their daughters, and mothers’ exposure to an increased risk of allergy in their sons.

As Svanes indicated, this still suggests that ‘immunity related to helminths is important to understand allergies and changes over time’, with the sex-specific patterns potentially reflecting the impact of infections that parents had prior to having children. The group’s evidence that environmental exposures may contribute to epigenetic markers across generations means that further research is needed. Dr Nils Oskar Jögi’s PhD research is tackling this, studying exposure to helminths across generations in Denmark, Norway, and Estonia, ‘examining change across time and whether, if you are exposed to helminths and you develop antibodies, they will remain for a long period’.

Associate Professor William Horsnell (University of Cape Town) hopes that this field of research will lead to the design of new vaccines that would go to mothers to foster long-term immunity in their children. His study of the effects of pre-pregnancy helminth infection in mice, published in Science, broke new ground: ‘to the best of our knowledge this is the first demonstration that infection prior to pregnancy can transfer lifelong cellular (not antibody mediated) immunity to offspring.’

As an emerging researcher in this area, Jögi argues that interdisciplinarity can generate ‘a different kind of understanding’ of the problem; Svanes agrees this is what makes for the ‘most innovative’ work. The group is refining methodologies to fully isolate helminth exposure from other closely related agents and to distinguish between exposure and infection, a necessary step towards isolating any resulting benefits.

Solutions to the riddle of what Svanes called ‘the useful little things in the worms’ remain some way in the future. But if the health pathways are not yet clear, the potential implications of the research are already evident, ‘of huge importance to understanding the rise of allergies’ globally as well as immune development and lung health.

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Professor Cecilia Svanes is Principal Investigator of the Helminths and Allergies group. Its WUN partner institutions are Maastricht University, the University of Bergen, the University of Cape Town, and the University of Southampton. The group received a WUN Sustainability Fund Grant, to accelerate initiatives with the capacity to attract significant external funding. For more information see their WUN page.