Neo-self antibody could be a major cause of recurrent pregnancy loss

A research group centered around Kobe University Graduate School of Medicine's Professor YAMADA Hideto and Associate Professor TANIMURA Kenji (Department of Obstetrics and Gynecology), and Professor ARASE Hisashi et al. of Osaka University's Research Institute for Microbial Diseases (RIMD) have revealed for the first time in the world the high frequency of a novel autoantibody in women suffering from recurrent pregnancy loss.

Joint research by Kobe University and Osaka University in 2015 previously discovered that this autoantibody also causes diseases such as thrombosis.

It is expected that these results will contribute towards the illumination of the underlying mechanisms behind recurrent pregnancy loss, thrombosis and pregnancy complications such as hypertensive disorders; leading to the development of new treatment methods.

The findings were published online on June 25 in the American College of Rheumatology's journal 'Arthritis and Rheumatology'.

Main points

• Those with recurrent pregnancy loss (RPL) experience repeated miscarriages and stillbirths, making them unable to give birth to a healthy baby.

• In Japan, approximately 1,400,000 women are believed to suffer from RPL. In more than half of cases the cause cannot be determined, making it difficult to prescribe a treatment method. This is a big problem, especially in light of Japan's low birthrate and aging population.

• This study was based at Kobe University, which is putting a lot of effort into RPL research, and covered 227 patients in five university hospitals across the country. Approximately a quarter of these patients tested positive for the novel autoantibody (neo-self antibody). Furthermore, almost one fifth tested positive for the neo-self antibody among patients for whom common tests had been unable to determine the cause.

• It is expected that these results can illuminate the underlying mechanisms behind RPL, thrombosis and hypertensive disorders of pregnancy, leading to the development of new treatment methods. Furthermore, it is hoped that these research results can be the key to solving the low birthrate and aging population issues.

Research background

Recurrent pregnancy loss (RPL) is a disorder in which the sufferer is able to get pregnant yet experiences repeated miscarriages and stillbirths, making them unable to give birth to a healthy baby. There is believed to be an estimated 1,400,000 women with RPL in Japan.

Given Japan's low birthrate and aging population, this is an important issue to overcome. However, at present the cause remains unknown in over half of patients, making it difficult to know how to cure RPL in many cases.

However, joint research conducted by RIMD's Professor Arase Hisashi and Kobe University's Associate Professor Tanimura Kenji discovered a completely new autoantibody that causes antiphospholipid syndrome.

This syndrome can lead to the occurrence of thrombosis (in which blood clots can block up blood vessels in vital organs, endangering life such as by causing a stroke), miscarriages, and hypertensive disorders of pregnancy, which can endanger the lives of pregnant women. These findings were published as a thesis in the American Society of Hematology's journal 'Blood' in 2015.

RPL involving repeated miscarriages is also a clinical manifestation of antiphospholipid syndrome. As previously mentioned, the cause of RPL is unknown in over half of cases, however the association between this neo-self antibody and RPL had not been investigated.

This research group hypothesized that the neo-self antibody could be connected to RPL in cases with unexplained causes.

With this in mind, blood samples were collected from RPL patients across five university hospitals (Kobe University, University of Toyama, Okayama University, The University of Tokyo, and Hyogo Medical University), and the samples were tested for neo-self antibodies at RIMD. For the first time in the world, the research group conducted this clinical study to illuminate the association between RPL and the neo-self antibody.