Schistosoma mansoni ‐specific immune responses and allergy in Uganda

SummaryChronic helminth infection with Schistosoma (S.) mansoni protects against allergic airway inflammation (AAI) in mice and is associated with reduced Th2 responses to inhaled allergens in humans, despite the presence of schistosome‐specific Th2 immunity. Schistosome eggs strongly induce type 2 immunity and allow to study the dynamics of Th2 versus regulatory responses in the absence of worms. Treatment with isolated S. mansoni eggs by i.p. injection prior to induction of AAI to ovalbumin (OVA)/alum led to significantly reduced AAI as assessed by less BAL and lung eosinophilia, less cellular influx into lung tissue, less OVA‐specific Th2 cytokines in lungs and lung‐draining mediastinal lymph nodes and less circulating allergen‐specific IgG1 and IgE antibodies. While OVA‐specific Th2 responses were inhibited, treatment induced a strong systemic Th2 response to the eggs. The protective effect of S. mansoni eggs was unaltered in μMT mice lacking mature (B2) B cells and unaffected by Treg cell depletion using anti‐CD25 blocking antibodies during egg treatment and allergic sensitization. Notably, prophylactic egg treatment resulted in a reduced influx of pro‐inflammatory, monocyte‐derived dendritic cells into lung tissue of allergic mice following challenge. Altogether, S. mansoni eggs can protect against the development of AAI, despite strong egg‐specific Th2 responses.

Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Isolated Schistosoma mansoni eggs prevent allergic airway inflammation

Obieglo

Schuijs

Ozir‐Fazalalikhan

et al. 2018

“…Other recent studies have also looked at how helminth‐induced cytokine profiles may influence allergic immune responses. For example, the investigation conducted on islands endemic for S. mansoni in Lake Victoria, Uganda, found that in a subset of participants, reported wheeze was negatively associated with S. mansoni‐ specific cytokine responses . These observations are in line with the protective effects of helminth infection on allergy‐related outcomes.…”

Section: Helminths and Allergy‐related Outcomes: Immune Mechanisms Inmentioning

confidence: 74%

“…Allergen‐specific IgG4 is often considered as a marker of immune modulation while allergen‐specific IgE as a marker of allergic disease . The IgG4 to IgE ratio can be utilized to determine immune modulation over the allergic response.…”

Section: Helminths and Allergy‐related Outcomes: Immune Mechanisms Inmentioning

confidence: 99%

Parasites and allergy: Observations from Africa

Mpairwe

Amoah

2018

Population studies from the African continent have observed a marked increase in the prevalence of allergy-related diseases over the past few decades, but the cause of this rise is not fully understood. The most investigated potential risk factor has been the relationship between exposure to helminths and allergy-related outcomes. Immunologically, parallels exist between responses to helminths and to allergens as both are associated with elevated levels of immunoglobulin E, increased numbers of T helper 2 cells and other immune cells. However, epidemiological studies from the African continent have found inconsistent results. In this review, observations from population studies carried out in Africa over the last decade that focus on the relationship between helminth infections and allergy-related outcomes are examined. How these findings advance our understanding of the complex interactions between helminths and allergies at the population level is also explored as well as some of the underlying immune mechanisms involved. This knowledge is important for better diagnosis, treatment and prevention of allergy-related diseases and has wider global significance.

“…Thus, in this context, its main function appears to be a blocking one, and possibly instrumental in preventing IgE‐mediated inflammation. High levels of anti‐ Ascaris IgG4 have been negatively associated with allergen SPT positivity, while in a S. mansoni ‐endemic area—although higher levels of both IgE and IgG4 were found in infected individuals—a higher ratio of IgE to IgG4 predicted clinical allergic symptoms, just as in allergen‐specific immunotherapy . As many helminth products are homologous to common allergens, IgG4 responses raised against helminth products may also bind and block IgE epitopes on allergens, reducing responses to allergens and directly reducing SPT responses .…”

Section: Helminths and Modulation Of Allergic Disease: The Role Of Immentioning

confidence: 99%

Worms: Pernicious parasites or allies against allergies?

McSorley

Chayé

Smits

2018

Type 2 immune responses are most commonly associated with allergy and helminth parasite infections. Since the discovery of Th1 and Th2 immune responses more than 30 years ago, models of both allergic disease and helminth infections have been useful in characterizing the development, effector mechanisms and pathological consequences of type 2 immune responses. The observation that some helminth infections negatively correlate with allergic and inflammatory disease led to a large field of research into parasite immunomodulation. However, it is worth noting that helminth parasites are not always benign infections, and that helminth immunomodulation can have stimulatory as well as suppressive effects on allergic responses. In this review, we will discuss how parasitic infections change host responses, the consequences for bystander immunity and how this interaction influences clinical symptoms of allergy.