9. Germinal centre innervation of bovine and human tonsils related to prion diseases

Abstract

A number of immunological functions in CD4+ T cells are dependent on the circadian rhythm as we and others could previously demonstrate. Little is known about the underlying mechanisms. One possibility could be the circadian rhythm of the molecular clock in T cells. The molecular clock is known to control the circadian rhythm in the brain and several peripheral organs. To address this question we analyzed the expression of five clock genes (Bmal1, Per2, Cry1, Rev-erba, Dbp), the production of cytokines and the CD40L expression in CD4+ T cells from human volunteers. A total of 15 healthy young men were examined under defined conditions over 24 h in the sleep lab. Venous blood was drawn periodically every 3 h, CD4+ T cells were isolated. T cells were split: one fraction was used for the investigation of clock gene expression and the second fraction was polyclonally stimulated and analyzed applying FACS. We found that on average 32% of polyclonally stimulated highly purified CD4+ T cells express CD40L at 15:00 h whereas only 2% of the CD4+ T cells express CD40L at 6:00 h. Additionally there is also a strong rhythm for the production of INF-g. Furthermore, we have preliminary data demonstrating the rhythmic expression of the core clock genes Bmal1and Cry1 in CD4+ T cells. These findings demonstrate that highly purified CD4+ T cells have a strong functional circadian rhythm and that a possible underlying mechanism could be the molecular clock. It is well demonstrated that norepinephrine can influence the immune response [1]. We already demonstrated that in RA synovial tissue there are cells producing catecholamines. To study the role of local catecholamine production in the inflammatory process in arthritis. Synovial samples were obtained from 21OA and 10RA patients who underwent knee joint replacement. Synovial cells were cultured with reserpine (10-6 to 10-8 M), OR486 (10-5 or 10-6 M) or medium (control) for 24 h. TNF, IL-8 and IL-6 were determined by Luminex and ELISA. For in vivo experiments, collagen type-II arthritis in DBA-1J mice was elicited. Thirty-one days after arthritis induction, mice were injected with 300 mg/kg reserpine or with NaCl (control) in the dorsum of one hind paw. Arthritis score was daily evaluated until day 47. The blockade of catecholamine by reserpine 10-6 M caused a strong reduction of TNF both in OA and RA. IL-6 is significantly lower in reserpine-treated cells of OA, whereas there is a reduction of IL-8 production only in reserpine-treated RA cells. The effects on cytokines were even stronger if reserpine was used in combination with OR486, an inhibitor of catecholamine degradation. Also in vivo caused reserpine a strong anti-inflammatory effect. In fact, 16 days after reserpine treatment the clinical score was lower in reserpinetreated mice compared to controls. We hypothesize that the local production of catecholamines in the synovial tissue plays a crucial role in the inflammatory process in arthritis. Therefore, modulation of catecholamine release by reserpine could be useful in t...