Flu in Pregnancy Linked to Overactive Immune Response

Influenza can lead to life-threatening complications during pregnancy, and it has been discovered that the immune system’s overreaction, triggered by a viral sensor called TLR7, allows the virus to spread into the bloodstream, increasing the risk of severe complications for mothers and babies.

A new preclinical study, led by RMIT University, used animal models to identify the role of TLR7 in amplifying inflammation and spreading disease into the bloodstream during pregnancy. The team found that blocking TLR7 could help protect developing babies by stopping the placenta from becoming overly inflamed during flu infection.

According to the study, published in Science Advances, the discovery redefines how we think about infection during pregnancy. Dr. Stella Liong, lead author from RMIT’s School of Health and Biomedical Sciences, said the findings shift understanding of how respiratory viruses affect pregnancy, showing that harm is not caused by the virus directly reaching the fetus, but by an overactive maternal immune response that disrupts vascular function.

The researchers emphasize the importance of disease prevention, with Dr. Gemma Trollope stating that the best defense against maternal flu complications is immunization. They hope this finding leads to stronger health care messaging and more prevention. They need to invest in developing pregnancy-safe therapies and remind people that getting vaccinated against flu is safe at any stage of pregnancy.

Severe flu in pregnancy can have long-term impacts on babies’ brain development, by inflaming blood vessels and reducing the flow of oxygen and nutrients from mother to baby. This study pinpoints the underlying cause of that damage, reshaping our understanding of flu-related risk in pregnancy and opening the door to more targeted therapies.

Professor Stavros Selemidis said future treatments could focus on the immune system rather than the virus itself. The team is planning further research on how to target TLR7 to reduce the risk of severe influenza and pregnancy complications.

The study’s findings have significant implications for the development of new therapies and clinical guidelines. RMIT University is seeking partners to help develop the next generation of therapies and clinical guidelines. Organizations interested in collaborating can contact [email protected].

The risk of severe complications from influenza during pregnancy is significant, with 20-30% of pregnant women who contract the flu experiencing severe complications, including hospitalization and even death. However, 90% of pregnant women who receive the flu vaccine do not develop severe complications from the flu, highlighting the need for stronger health care messaging and increased prevention efforts.

They are optimistic about the potential for future research, and Dr. Liong noted that they can start to work out how to switch off this TLR7 sensor, which could help prevent the harmful inflammation that makes flu in pregnancy so dangerous. The team’s next steps will involve further research on how to target TLR7 and reduce the risk of severe influenza and pregnancy complications.