A study of pregnant women with SARS-CoV-2 infections, but with mild or no symptoms of COVID-19, found that immunological changes counteract the inflammation associated with the disease.
The worst effects of COVID-19 are usually a result of an immune system response from the body that over-produces an immune-regulating protein molecule called cytokines. This ‘cytokine storm’ leads to inflammation that can cause extensive tissue damage, organ failure and death.
Researchers based in Italy, the United States, and Australia, examined the levels of 62 cytokines in the blood plasma of 14 pregnant women infected with SARS-CoV-2, along with 28 uninfected pregnant women and 15 age-matched women who were not pregnant. They also monitored the levels of key cells of the immune system.
“Pregnant women with SARS-CoV-2 are able to control inflammation through the production of anti-inflammatory molecules that counterbalance the pro-inflammatory ones,” says primary investigator, Andrea Cossarizza, of the University of Modena and Reggio Emilia School of Medicine.
He explains that even with increased levels of neutrophil cells that indicate an inflammatory response, the subjects had normal levels of the interleukin-6 molecule, which is the main cytokine considered responsible for inflammation.
“If pregnancy occurs in healthy women who do not have main risk factors that are pro-inflammatory, like obesity or hypertension, the response to SARS-CoV-2 is well controlled,” Cossarizza adds.
He attributes this to the natural changes in the immune system during pregnancy that protect the developing foetus from immune attack.
The team will continue to follow the women in the study and add others. They also hope to uncover details of the molecular mechanisms behind the protective effects. This could lead to insights that might help treat pregnant women who do experience problems due to COVID-19.
De Biasi, S. et al. Nat. Commun. 12: 4677 (2021).