Zhang Liwen, Chen Sheng, Liu Yan, Xu Xueqin, Zhang Qianying, Shao Shuxin, Wang Weiming, Li Xiao
Department of Nephrology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin Er Road, Shanghai, 200025, People's Republic of China.
Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.
J Transl Med. 2020 Mar 5;18(1):116. doi: 10.1186/s12967-020-02284-1.
Lupus nephritis is one of the most common and severe complications of systemic lupus erythematosus, of which poor prognosis is indicated by aggravated renal hypoxia and tubulointerstitial fibrosis. Cell adhesion molecules play a key role in the progression of lupus nephritis tubulointerstitial lesion, including P-selectin, which mediates the rolling of leukocytes and subsequent adhesion and infiltration and then initiates the inflammatory immune response and ischemia and hypoxia injury. However, the effects and mechanisms of P-selectin in lupus nephritis remain to be investigated, and a noninvasive measurement of lupus nephritis tubulointerstitial hypoxia and fibrosis remains to be explored.
Thirty-four MRL/lpr mice were randomly divided into the following three groups: MRL/lpr, saline, and anti-P-selectin, which consisted of no treatment, treatment with normal saline, and treatment with anti-P-selectin monoclonal antibody (mAb) from 12 to 16 weeks of age, respectively. Ten male C57BL/6 mice of the same age served as normal controls. 24-h urinary protein, urinary albumin-creatinine ratio, and periodic acid-Schiff were used to assess kidney damage; Western blot or immunohistochemical staining of the hypoxia probe Hypoxyprobe™-1, hypoxia-inducible factor 1α (HIF-1α), and CD31 were used to evaluate hypoxia in renal tissue; and NADPH oxidase subunit gp91phox and p22phox were used to examine renal oxidative stress. The correlation between kidney injury and blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) was calculated to assess the clinical value of BOLD-MRI.
P-selectin is upregulated in lupus nephritis. Blocking P-selectin with mAb alleviated renal tubulointerstitial fibrosis, renal hypoxia, and peritubular capillary loss, without alteration of the levels of lupus activity indicators, anti-dsDNA antibody, or complement C3. BOLD-MRI showed that the reduced R2* values in the renal cortex and medulla of lupus mice were increased when treated with anti-P-selectin mAb as compared with those treated with normal saline, which were negatively correlated with Hypoxyprobe™-1 hypoxia probe and the expression of HIF-1α.
Early intervention of lupus nephritis with anti-P-selectin mAb can significantly improve the hypoxic state of the kidney and reduce the severity of tubulointerstitial lesions. BOLD-MRI techniques are noninvasive and can dynamically evaluate the changes in renal lesions and intrarenal oxygenation levels before and after treatment in lupus nephritis.
狼疮性肾炎是系统性红斑狼疮最常见且严重的并发症之一，肾脏缺氧加重和肾小管间质纤维化提示预后不良。细胞黏附分子在狼疮性肾炎肾小管间质病变进展中起关键作用，包括P-选择素，它介导白细胞的滚动以及随后的黏附与浸润，进而引发炎症免疫反应和缺血缺氧损伤。然而，P-选择素在狼疮性肾炎中的作用及机制仍有待研究，狼疮性肾炎肾小管间质缺氧和纤维化的无创测量方法也有待探索。
将34只MRL/lpr小鼠随机分为以下三组：MRL/lpr组、生理盐水组和抗P-选择素组，分别在12至16周龄时不进行处理、用生理盐水处理以及用抗P-选择素单克隆抗体（mAb）处理。10只同龄雄性C57BL/6小鼠作为正常对照。采用24小时尿蛋白、尿白蛋白-肌酐比值和高碘酸-希夫染色评估肾脏损伤；用缺氧探针Hypoxyprobe™-1、缺氧诱导因子1α（HIF-1α）和CD31的蛋白质印迹或免疫组织化学染色评估肾组织缺氧情况；用NADPH氧化酶亚基gp91phox和p22phox检测肾脏氧化应激。计算肾脏损伤与血氧水平依赖性功能磁共振成像（BOLD-MRI）之间的相关性，以评估BOLD-MRI的临床价值。
狼疮性肾炎中P-选择素上调。用mAb阻断P-选择素可减轻肾小管间质纤维化、肾脏缺氧和肾小管周围毛细血管损失，而狼疮活动指标、抗双链DNA抗体或补体C3水平未发生改变。BOLD-MRI显示，与生理盐水处理组相比，抗P-选择素mAb处理的狼疮小鼠肾皮质和髓质中降低的R2*值升高，且与Hypoxyprobe™-1缺氧探针及HIF-1α的表达呈负相关。
用抗P-选择素mAb对狼疮性肾炎进行早期干预可显著改善肾脏缺氧状态并减轻肾小管间质病变的严重程度。BOLD-MRI技术具有无创性，可动态评估狼疮性肾炎治疗前后肾脏病变及肾内氧合水平的变化。
