全身紅斑性狼瘡 (systemic lupus erythematosus) 是一個慢性的自體免疫性疾病會侵犯全身各種器官，並以其複雜多變的臨床表現而聞名。患者體內存在著一個失衡的生理反應，具有多量的免疫細胞產生凋亡，隨著血液循環系統流竄到全身的組織。另一方面，具有不健全的凋亡細胞清除能力。由於兩種機制的失衡促使自體抗體及免疫複合物的產生，並沉積在標靶器官。雖然這一個失衡機制的理論已經被發表多年，但是凋亡細胞的產生對於全身紅斑性狼瘡疾病病程的影響仍須進一步探討。長鏈非編碼型RNA在近幾年被發現可以在前轉錄及後轉錄時期進行基因調控，而在先前的研究中也發現了一些長鏈非編碼型RNA於自體免疫性疾病中扮演角色。LincRNA-p21是一種長鏈非編碼型RNA，經由活化caspase-3來促進細胞凋亡。由於目前尚未釐清lincRNA-p21的表現是否與全身紅斑性狼瘡具關聯性，因此本研究主要是探討lincRNA-p21在全身紅斑性狼瘡疾病病程中所扮演的角色。從臨床檢體中我們發現紅斑性狼瘡患者的週邊單核球細胞以及CD4+ T細胞中lincRNA-p21分子表現量高於健康受試者。在狼瘡腎炎的病患中lincRNA-p21具有顯著的高量的表現，並且與全身紅斑性狼瘡臨床嚴重度指標 (SLEDAI-2K) 以及腎炎病人每日蛋白尿總量呈正相關。此外，狼瘡肺出血病人相較於健康受試者具有較高的lincRNA-p21表現量。除此之外，在臨床檢體中也證實microRNA-181a可以作為被lincRNA-p21抑制的候選基因。為了探討lincRNA-p21在細胞內的生理表現，我們構築了以clustered regularly interspaced short palindromic repeats interference (CRISPRi) 所介導的基因編輯敲落系統藉以降低細胞內lincRNA-p21的表現，結果發現抑制表達lincRNA-p21的細胞在經過doxorubicin 的誘導後能顯著抑制凋亡細胞的形成，並且回復microRNA-181a的表現。以pristane 腹腔注射誘導出的類紅斑性狼瘡小鼠中發現CD4+ T細胞中lincRNA-p21的表現高於正常小鼠，於狼瘡腎炎小鼠 (BALB/c) 模式中誘導後期腎臟lincRNA-p21 表現量較對照組小鼠高， 而在肺出血小鼠 (C57BL/6) 模式中肺臟的lincRNA-p21 表現量在嚴重肺出血小鼠中明顯高於對照組小鼠。本研究結果顯示lincRNA-p21的表現在全身紅斑性狼瘡中能藉由促進凋亡細胞的生成來影響疾病病程。

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with relapsing/remitting courses and heterogeneous clinical presentations such as lupus nephritis (LN) and pulmonary hemorrhage (PH). The imbalance between accelerated cell apoptosis and clearance deficiency in SLE induce the accumulation of nuclear autoantigens and the production of autoantibodies, resulting in immune complex deposition in miscellaneous organs and tissues. Despite the established character of accelerated apoptosis in the development of SLE, its role in the disease progression remains to be elucidated in such patients. Previous studies have shown that lincRNA-p21, a pro-apoptotic long non-coding RNA (lncRNA), can up-regulate the pro-apoptotic process through activating caspase-3. We found that elevated levels of lincRNA-p21 in peripheral mononuclear cells and purified CD4+ T cells from SLE patients. Furthermore, its expression levels were higher in LN patients (class IV) and positively correlated with disease activity scores (SLEDAI-2K) and daily proteinuria amounts. In addition, lupus patients with PH had higher lincRNA-p21 expression levels than healthy subjects. From the predicted characters of lincRNA-p21, we examined whether this lncRNA can act as a competitive endogenous RNA to inhibit the microRNA expression. We further knocked down the expression of lincRNA-p21 by using the clustered regularly interspaced short palindromic repeats interference (CRISPRi) system to inhibit the formation of apoptotic cells through reducing caspase-3 activation and rescue the expression of miR-181a. Our animal experiments revealed that pristane-induced BALB/c and C57BL/6 lupus mouse models could exhibit clinicopathological manifestations similar to LN and PH, respectively. Lupus mouse models demonstrated increased levels of lincRNA-p21 in purified peripheral CD4+ T cells. In the LN model, higher renal expression levels of lincRNA-p21 could be detected in pristine-injected mice. In the PH model, there were higher expression levels of lincRNA-p21 in pristine-induced lupus mice with severe bleeding than saline-injected control ones. In conclusion, our in vitro and in vivo results demonstrate that up-regulated pro-apoptotic lincRNA-p21 expression plays a pathogenic role in the disease progression of SLE.

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