Prenatal exposure to viruses may cause type 1 diabetes and other autoimmune diseases in children, scientists have found.
The exact cause of juvenile diabetes has eluded scientists, but a new study from Tel Aviv University suggests that the autoimmune disease is initiated in utero.
According to the research, women who contract a viral infection during pregnancy transmit viruses to their genetically susceptible foetuses, sparking the development of type 1 diabetes.
"We knew that type 1 diabetes was associated with other autoimmune diseases like Hashimoto Thyroiditis, celiac disease, and multiple sclerosis, so we investigated the seasonality of birth months for these respective diseases in Israel and other countries," said Zvi Laron, Professor Emeritus of Pediatric Endocrinology at TAU's Sackler Faculty of Medicine.
"We found that the seasonality of the birth of children who went on to develop these diseases did indeed differ from that of the general public.
"In further studies, we found evidence that viral infections of the mother during pregnancy induced damage to the pancreas of the mother and/or the foetus, evidenced by specific antibodies including those affecting the pancreatic cells producing insulin," Laron said.
For the study, Laron and his team of researchers from Israel, the University of Washington, and Lund University, Sweden, conducted blood tests of 107 healthy pregnant women, testing for islet cell autoantibodies - evidence of diabetes that appears years before initial symptoms do.
They also tested for anti-rotavirus and anti-CoxB3 antibodies.
The researchers found a striking difference between women tested in different seasons, suggesting a link to winter epidemics.
The concurrent presence of GAD65 antibodies in cord blood and their mothers indicated autoimmune damage to islet cells during gestation, possibly caused by cross-placental transmission of viral infections and/or antivirus antibodies.
In other words, during viral epidemics of winter months, ten per cent of the healthy pregnant women who had no family background of autoimmune diseases tested positive for damaging antibodies.
In addition, the cord blood antibody concentrations that exceeded those of the corresponding maternal sample, or antibody-positive cord blood samples with antibody-negative maternal samples, implied an in utero immune response by the foetus.
"If our hypothesis can be verified, then preventive vaccine before conception would be useful in stopping the increasing incidence of type 1 diabetes and other autoimmune diseases," said Laron.