Van Wietmarschen found biological evidence for two sub-types of rheumatoid arthritis patients based on a Chinese diagnosis. Gene expression profiling and metabolomics analysis showed that apoptosis was found to be differently regulated in the two groups (joint with Prof Xu). A questionnaire was subsequently developed to standardize and characterize the Chinese diagnosis related to these two groups of patients. Non-linear principal component techniques were used to analyse the data (joint with Prof Meulman). Additional metabolomics analysis showed differences in acylcarnitine excretion in urine between the two groups indicating different muscle turnover rate and/or mass.
Currently, van Wietmarschen is leading a study to see whether differences in response to therapy with TNF-α blocker can be observed in the two groups of patients (joint with Prof Lafeber, Utrecht University). He is leading a study in which biopsychosocial predictors for successful weight loss in type 2 diabetes patients on a very low caloric diet are found. He is now studying the contribution of Chinese diagnosis to the predictive power of the model (joint with Dr Mulder, Erasmus University). This work is part of the Sino Dutch Centre for Preventive and Personalized Medicine of which he is a staff member and is currently supervising 4 PhD students. Two of those PhD students focus on the integration of ultra-weak bioluminiscence measurements with metabolomics data (joint with van Wijk, Leiden University).
Van Wietmarschen is recently involved in a Samueli Institute project which aims to develop tools to measure and model resilience and wellness.