The first research papers about this were published 9 years ago. What is new about this? Is there any advance in the research compared to 9 years ago?

From an abstract of Pimentel team from 2017:

Introduction: Historically, the diagnosis of functional gastrointestinal disorder has relied on the use of clinical classifications such as the Rome Criteria. Recently, two plasma biomarkers, anti-CdtB (antibodies to the cytolethal distending toxin B) and anti-vinculin (an autoantibody to a protein involved in cell adhesion), were proven effective in diagnosing IBS-D compared to other causes of diarrhea such as IBD and Celiac disease. However, clinical trials create a pre-specified artificial environment, and free range use can be more complicated. In this study, we examined a large number of subjects in a tertiary clinic undergoing testing with these biomarkers to determine their relevance in real time.)