We aim to investigate causes and biomarkers of chronic systemic inflammation in the general adult population. Most research so far has been conducted in model systems, which gives insufficient insight into the system complexity of the human body. Therefore, our research is based on data from the Rhineland Study, a deeply phenotyped population-based cohort of individuals aged 30 years and above. The Rhineland Study is designed to study the complex, high-dimensional nature of health and disease in humans. Participants undergo a regular assessment of their brain, cardio-vascular system, behaviour, lifestyle, senses, and cognitive abilities. With the biomaterial collected, we are currently using multi-omics in subgroups of our participants to get a comprehensive picture of their immune status, their gut composition, and their genetic features. Specifically, we (1) evaluate the impact of lifestyle factors on immune status, considering the influence of underlying (epi)genetic factors, and (2) investigate the role of adipose tissue and gut microbiome composition in that relationship. Additionally, we (3) explore whether the findings can be translated from mice to men and vice versa.