McLennan S V, Wang X Y, Moreno V, Yue D K, Twigg S M
Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
Endocrinology. 2004 Dec;145(12):5646-55. doi: 10.1210/en.2004-0436. Epub 2004 Sep 2.
High glucose concentration inhibits matrix degradation and affects the activities of the enzymes responsible, the matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). Connective tissue growth factor (CTGF) expression is increased in diabetic nephropathy and is a downstream mediator of TGF-beta actions. However, whether CTGF regulates matrix degradation and the mechanism of effect in diabetes has not been reported. Human mesangial cells were cultured in media containing 5 or 25 mM glucose and, in some experiments, with recombinant human (rh)CTGF (0-1000 ng/ml) and/or appropriate neutralizing antibodies. Matrix degradation was inhibited by rhCTGF in a dose-dependent manner, and the decrease in matrix degradation caused by high glucose and by TGF-beta was significantly attenuated by addition of CTGF-neutralizing antibody (by 40.2 and 69.1%, respectively). Similar to 25 mM glucose, addition of rhCTGF increased MMP-2, TIMP-1, and TIMP-3 mRNA by 2.5-, 2.1-, and 1.6-fold, respectively (P < 0.05) but had no effect on membrane-type (MT)1-MMP or TIMP-2. Addition of TIMP-1 antibody to conditioned medium abolished the decrease in degradation caused by rhCTGF and partially prevented (by 79%) the glucose-induced inhibition of matrix degradation. In vivo studies of glomeruli from diabetic and control rats showed that intensive insulin treatment prevented the increase in expression of CTGF and TIMP-1 and attenuated the decreased matrix degradation seen in diabetes. In summary, CTGF inhibits matrix degradation by increasing TIMP-1 expression, and by this action it contributes to the inhibition of matrix breakdown by high glucose, implying that CTGF has a role in the reduced matrix degradation observed in diabetic nephropathy.
高糖浓度会抑制基质降解，并影响负责基质降解的酶——基质金属蛋白酶（MMPs）及其组织抑制剂（TIMPs）的活性。结缔组织生长因子（CTGF）在糖尿病肾病中表达增加，是转化生长因子-β（TGF-β）作用的下游介质。然而，CTGF是否调节基质降解以及在糖尿病中的作用机制尚未见报道。将人系膜细胞培养于含5或25 mM葡萄糖的培养基中，在一些实验中，加入重组人（rh）CTGF（0 - 1000 ng/ml）和/或适当的中和抗体。rhCTGF以剂量依赖方式抑制基质降解，添加CTGF中和抗体可显著减弱高糖和TGF-β引起的基质降解减少（分别减少40.2%和69.1%）。与25 mM葡萄糖相似，添加rhCTGF可使MMP - 2、TIMP - 1和TIMP - 3 mRNA分别增加2.5倍、2.1倍和1.6倍（P < 0.05），但对膜型（MT）1 - MMP或TIMP - 2无影响。向条件培养基中添加TIMP - 1抗体可消除rhCTGF引起的降解减少，并部分预防（79%）葡萄糖诱导的基质降解抑制。对糖尿病大鼠和对照大鼠肾小球的体内研究表明，强化胰岛素治疗可防止CTGF和TIMP - 1表达增加，并减弱糖尿病中所见的基质降解减少。总之，CTGF通过增加TIMP - 1表达来抑制基质降解，通过这一作用它有助于高糖对基质分解的抑制，这意味着CTGF在糖尿病肾病中观察到的基质降解减少中起作用。
