G(alpha)S-to-G(alpha)i switch of G protein-coupled receptor signalling in arthritis

分子心脏病学和肺炎学的研究已经确定了β1/2肾上腺素能受体(也与其他类似类型的受体相关)的一个重要的脱敏机制，这与临床药物(心力衰竭、哮喘)有关。脱敏将细胞内环磷酸腺苷(CAMP)升高的典型GalphaS信号转换为cAMP和MAPK活性低的Galphai信号。当转换发生时，磷酸二酯酶抑制剂如阿司米司特、罗力普兰或罗氟司特不起作用。尽管apremilast已经在使用，但这种转换并没有在风湿性疾病的免疫学背景下进行研究。类风湿性关节炎(RA，我们的目标疾病)似乎也会发生类似的变化，结果是促炎事件，这可能是apremilast不起作用的重要原因(显示在RA中)。我们在RA中的初步结果清楚地表明，这种转换是一种伴随着TNF增加的促炎事件的迹象。该项目将在RA发作之前、早期RA和晚期RA(时间进程和细胞类型)中研究这种转换的时间和促炎后果；它将研究在小鼠出现II型胶原诱导的关节炎(CIA)期间不同时间点和不同细胞类型的转换；它将利用HIF-1α调节剂研究缺氧的强烈影响，并研究与蛋白激酶A和ERK1/2的串扰；它将仔细研究如何在RA滑膜细胞中逆转这种开关，以及逆转是否对RA滑膜细胞有抗炎作用。动物模型用于比较RA和CIA的情况，以确定所涉及的通路的潜在差异。这些项目将超越我们的初步工作，以展示在RA和CIA中促炎症GalphaS到Galphai开关的全貌。

Research in molecular cardiology and pneumology has identified an important desensitization mechanism of the Beta1/2 adrenergic receptor (also pertinent for other receptors of similar type), which is relevant in clinical medicine (heart failure, asthma). The desensitization switches canonical GalphaS signaling with increased intracellular cyclic AMP (cAMP) to Galphai signaling with low cAMP and MAP kinase activation. Phosphodiesterase inhibitors like apremilast, rolipram, or roflumilast do not work when the switch has happened. This switch was not studied in the context of immunology in rheumatic diseases, although apremilast is already in use. A similar switch seems to happen in rheumatoid arthritis (RA, our target disease), and the outcome is a proinflammatory event, which can be the important reason why apremilast does not work (shown in RA). Our preliminary results in RA clearly demonstrate signs of the switch as a proinflammatory event with increased TNF.This project will address time and proinflammatory consequence of the switch in humans already before outbreak of RA, in early RA, and late RA (time course and cell types); it will investigate the switch at different time points and in different cell types during the manifestation of collagen type II-induced arthritis (CIA) in mice; it will study the strong influence of hypoxia making use of HIF-1alpha modulators and studying the crosstalk with proteinkinase A and Erk1/2; it will scrutinize how the switch can be reverted in RA synovial cells, and whether reversion has anti-inflammatory consequences in RA synovial cells. The animal model is used in order to compare the situation in RA with CIA to define potential differences of involved pathways. These project will go beyond our preliminary work in order to demonstrate the full picture of the proinflammatory GalphaS - to - Galphai switch in RA and CIA.