Regulating fibrocyte differentiation in fibrosis

描述(申请人提供)：硬皮病、严重的慢性哮喘、肺纤维化和心脏纤维化等纤维性疾病每年仅在美国就导致数万人死亡。越来越多的证据表明，在纤维化病变中，血液单核细胞亚群进入组织并分化为成纤维细胞样细胞，称为成纤维细胞，导致组织功能障碍。我们在体外发现一种名为血清淀粉样蛋白P(SAP)的血液蛋白抑制这种分化。注射SAP可预防博莱霉素诱导的大鼠和小鼠肺纤维化以及小鼠缺血再灌流所致的心肌纤维化。一些患有肺纤维化的儿童血清SAP水平较低，一个令人兴奋的可能性是，SAP可能在人类身上用作抗纤维化药物。迫切需要的是能够识别纤维细胞前体、早期纤维细胞和成熟纤维细胞，以便在患者治疗的早期阶段进行活组织检查，并确定治疗是否影响纤维细胞分化。虽然有几种抗原作为成熟纤维细胞的标志，但对早期纤维细胞的表型知之甚少，单核细胞亚群的特性也是未知的。我们提出了三个特定的目标来阐明纤维细胞的分化。首先，我们将确定已知的纤维细胞标记物在人、大鼠和小鼠体外成纤维细胞分化过程中出现的时间进程，以确定可能的早期标记物。然后，我们将使用这些信息来确定SAP抑制纤维细胞分化的阶段。其次，我们将确定是否只有一个或几个已知的单核细胞亚群可以分化为纤维细胞，从而确定已知的标志物是否可以作为纤维细胞前体的生物标志物。第三，我们将诱导小鼠肺纤维化，并确定标志物在体内出现的时间过程，并利用这一信息验证SAP抑制纤维细胞分化以抑制纤维化的假说。外行语言：我们预计，识别循环中的纤维细胞前体细胞的标志物可能会导致对有纤维化疾病风险的患者进行诊断分析，确定纤维细胞在其发育过程中的不同时间表达哪些标志物将使人们能够在抗纤维化药物的临床试验早期监测临床疗效，并且阐明SAP在组织中抑制纤维细胞分化的哪个阶段将有助于我们了解我们如何使用SAP来调节患者的纤维化。

DESCRIPTION (provided by applicant): Fibrotic diseases such as scleroderma, severe chronic asthma, pulmonary fibrosis, and cardiac fibrosis kill tens of thousands of people each year in the US alone. Growing evidence suggests that in a fibrotic lesion a subset of blood monocytes enters the tissue and differentiates into fibroblast-like cells called fibrocytes, causing tissue dysfunction. We found that a blood protein called serum amyloid P (SAP) inhibits this differentiation in vitro. Injections of SAP prevent bleomycin-induced lung fibrosis in rats and mice, and ischemia-reperfusion induced cardiac fibrosis in mice. Some children with pulmonary fibrosis have low serum levels of SAP, and an exciting possibility is that SAP might be useful as an anti-fibrotic in humans. A critical need is to be able to identify fibrocyte precursors, early fibrocytes, and mature fibrocytes, so that in the early stages of treating a patient one could take a biopsy and determine if the treatment is affecting fibrocyte differentiation. Although there are several antigens that serve as markers for mature fibrocytes, little is known about the phenotype of early fibrocytes and the identity of the monocyte subset is unknown. We propose three specific aims to elucidate fibrocyte differentiation. First, we will determine the time course of appearance of known fibrocyte markers during human, rat, and mouse fibrocyte differentiation in vitro, to identify the earliest possible markers. We will then use this information to determine the stage at which SAP inhibits fibrocyte differentiation. Second, we will determine whether just one or several known subsets of monocytes can differentiate into fibrocytes, and thus whether known markers can serve as biomarkers of fibrocyte precursors. Third, we will induce pulmonary fibrosis in mice, and determine the timecourse of marker appearance in vivo, and use this information to test the hypothesis that SAP inhibits fibrocyte differentiation to inhibit fibrosis. Lay Language: We anticipate that identification of the markers for the circulating fibrocyte progenitor cells might lead to diagnostic assays for patients at risk for fibrosing diseases, determining what markers are expressed by fibrocytes at different times during their development will allow one to monitor clinical efficacy early in a clinical trial of an anti-fibrotic drug, and that elucidating at what stage SAP inhibits fibrocyte differentiation in a tissue will help us understand how we might use SAP to regulate fibrosis in patients.