TNF and obesity due to melanocortin 4 receptor deficiency: Mechanical abnormalities, e.g., due to overload from obesity or insufficient load from bed rest, increase catabolic effects and thus favor cartilage degradation.[37] Using our in vitro approach, we administered TNF‐α – one of the most important pro‐inflammatory cytokines in arthritis[38] – in a high but non‐cytotoxic dose (100 ng ml−1) during the respective non‐perfusing incubation phase for three days.