Ecotoxicological assessment of plastic and rubber polymers leachates in the blue mussel Mytilus edulis: cellular and whole-organism responses with a focus on tyre-derived leachates and particles

Sammendrag

The population is getting older, which emphasizes the importance of promoting healthy ageing. WHO defines “Healthy ageing” as maintaining the physiological ability and thereby enable well-being. Contrary, frailty is expressed by a decline in multiple physiological systems and increased vulnerability to adverse health outcomes and death. A long life is not necessarily a good life, and even if life expectancy has increased, the next step will be to facilitate good health in these extra years of life. In this thesis, we have focused on the association between inflammation and frailty and nutrition and frailty. Ageing affects the immune system’s capacity to maintain homeostasis, where an imbalance in the ability to repair damage leads to low-grade chronic inflammation in the body. To ensure an adequate dietary intake is important to prevent under- and malnutrition and to maintain muscle mass in older adults. Eating a healthy diet has previously shown to prevent frailty. This thesis aimed to investigate the association between inflammatory markers and frailty both cross-sectionally (Paper I) and after 8-year follow-up (Paper III) in home-dwelling elderly (≥ 70 years). Also, we wanted to investigate the development of frailty over time and if dietary factors could predict/be correlated with the changes in frailty after 8-year follow-up (Paper II). Finally, we wanted to investigate the association between body composition and frailty, and body composition and inflammatory markers (Paper III). We used data from a cross-sectional study conducted in 2014/2015 (Amarone I) and the follow-up study conducted eight years later (Amarone Follow-up). The participants were ≥ 70 years of age when included in 2014/2015 and still home-dwelling. Frailty was assessed by using Rockwood’s frailty index, which counts the accumulation of health parameters (termed “deficits”). We investigated the inflammatory markers IL-6, CRP, IGF-1, cystatin C, cathepsin S, Gp-acetyls, and PBMC transcriptoms in the cross-sectional analyses, and CRP, IL-6, TNF-α and Gp-acetyls in the longitudinal analyses. The dietary data were collected by 2x24-hour recall interviews, and the dietary factors we investigated were total energy intake, protein intake (total, animal, plant protein), as well as the food groups meat, fish and seafood, and dairy products. We used linear regression (both adjusted and unadjusted) and Spearman’s rank correlation coefficient to consider significant associations in this thesis. In this thesis, we showed that higher levels of inflammatory markers were associated with frailty (Paper I) and that CRP levels at baseline were associated to the change in frailty after the 8-year follow-up (Paper III). In some additional analyses of this thesis, the association between CRP and frailty disappeared after adjusted for education. The prevalence and degree of frailty increased after the 8-year follow-up, however, the dietary factors were not associated with the change in frailty (Paper II). Neither did we find an association between body composition and the change in frailty, while the change in fat mass and waist circumference were significantly correlated with change in inflammatory markers after the 8-year follow-up (Paper III). In this thesis, we showed that even in a relatively homogenous group of home-dwelling elderly, which may be healthier than the mean of people of their chronological age, frailty changed after the 8-year follow-up. The frailest subjects expressed the highest levels of inflammatory markers, and in this study population, CRP levels were associated to the development of frailty over time. Neither dietary factors nor body composition variables were associated with frailty.