Dataset Information

Blockade of myeloid differentiation 2 attenuates diabetic nephropathy by reducing activation of the renin-angiotensin system in mouse kidneys.

ABSTRACT:

Background and purpose

Both innate immunity and the renin-angiotensin system (RAS) play important roles in the pathogenesis of diabetic nephropathy (DN). Myeloid differentiation factor 2 (MD2) is a co-receptor of toll-like receptor 4 (TLR4) in innate immunity. While TLR4 is involved in the development of DN, the role of MD2 in DN has not been characterized. It also remains unclear whether the MD2/TLR4 signalling pathway is associated with RAS activation in diabetes.

Experimental approach

MD2 was blocked using siRNA or the low MW inhibitor, L6H9, in renal proximal tubular cells (NRK-52E cells) exposed to high concentrations of glucose (HG). In vivo, C57BL/6 and MD2^-/- mice were injected with streptozotocin to induce Type 1 diabetes and nephropathy.

Key results

Inhibition of MD2 by genetic knockdown or the inhibitor L6H9 suppressed HG-induced expression of ACE and angiotensin receptors and production of angiotensin II in NRK-52E cells, along with decreased fibrosis markers (TGF-? and collagen IV). Inhibition of the MD2/TLR4-MAPKs pathway did not affect HG-induced renin overproduction. In vivo, using the streptozotocin-induced diabetic mice, MD2 was overexpressed in diabetic kidney. MD2 gene knockout or L6H9 attenuated renal fibrosis and dysfunction by suppressing local RAS activation and inflammation.

Conclusions and implications

Hyperglycaemia activated the MD2/TLR4-MAPKs signalling cascade to induce renal RAS activation, leading to renal fibrosis and dysfunction. Pharmacological inhibition of MD2 may be considered as a therapeutic approach to mitigate DN and the low MW inhibitor L6H9 could be a candidate for such therapy.

SUBMITTER: Wang Y

PROVIDER: S-EPMC6592858 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Publications

Blockade of myeloid differentiation 2 attenuates diabetic nephropathy by reducing activation of the renin-angiotensin system in mouse kidneys.

Wang Yi Y Fang Qilu Q Jin Yiyi Y Liu Zhoudi Z Zou Chunpeng C Yu Weihui W Li Weixin W Shan Xiaoou X Chen Ruijie R Khan Zia Z Liang Guang G

British journal of pharmacology 20190523 14

<h4>Background and purpose</h4>Both innate immunity and the renin-angiotensin system (RAS) play important roles in the pathogenesis of diabetic nephropathy (DN). Myeloid differentiation factor 2 (MD2) is a co-receptor of toll-like receptor 4 (TLR4) in innate immunity. While TLR4 is involved in the development of DN, the role of MD2 in DN has not been characterized. It also remains unclear whether the MD2/TLR4 signalling pathway is associated with RAS activation in diabetes.<h4>Experimental appro ...[more]

PMID: 30959575

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Project description:Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are the cornerstones of pharmacologic therapy in diabetic nephropathy. Mineralocorticoid receptor blockers reduce proteinuria as single agents or add-on therapy to other renin-angiotensin-aldosterone system-inhibiting drugs in these patients. The long-term benefits and ultimate role of mineralocorticoid receptor blockers in diabetic nephropathy remain unknown. A clinical trial previously showed that the kalemic effect of spironolactone is higher than losartan when added to lisinopril in patients with diabetic nephropathy. The purpose of this study was to investigate if renal potassium handling was primarily responsible for that observation.In a blinded, randomized, three-arm placebo-controlled clinical trial, 80 participants with diabetic nephropathy taking lisinopril (80 mg) were randomized to spironolactone (25 mg daily), losartan (100 mg daily), or placebo (trial dates from July of 2003 to December of 2006). Serum potassium, aldosterone, and 24-hour urine sodium, potassium, and creatinine were measured over 48 weeks. Differences were analyzed with repeated measures mixed models.Mean follow-up serum potassium was 5.0 mEq/L for spironolactone, 4.7 mEq/L for losartan (P=0.05 versus spironolactone), and 4.5 mEq/L for placebo (P<0.001 versus spironolactone; P=0.03 versus losartan). The difference in serum potassium was 0.23 mEq/L for losartan versus placebo (P=0.02), 0.43 mEq/L for spironolactone versus placebo (P<0.001), and 0.2 mEq/L for spironolactone versus losartan (P=0.05). Serum and urine potassium excretion and secretion rates were similar between groups throughout the study.Spironolactone raised serum potassium more than losartan in patients with diabetic nephropathy receiving lisinopril, despite similar renal sodium and potassium excretion. This finding suggests that extrarenal potassium homeostasis contributes to hyperkalemia in these patients. A better understanding of extrarenal potassium homeostasis will provide an opportunity to use this drug more safely in patients with diabetic nephropathy as well as other patient populations.

Project description:IntroductionRenin-angiotensin system (RAS) blockade using angiotensin-converting enzyme inhibitor (ACEi)/angiotensin receptor blocker (ARB) is first-line therapy for IgA nephropathy (IgAN). There is a paucity of information on the predictors and magnitude of response to this treatment.MethodsIn a prospective study, treatment-naive patients with IgAN with urinary protein ≥ 1 g/d and estimated glomerular filtration rate (eGFR) ≥ 30 ml/min per 1.73 m2 received supportive treatment including ACEi (ramipril) or ARB (losartan) in patients intolerant to ACEi, and optimal blood pressure (BP) control to ≤130/80 mm Hg, with a follow-up of 6 months. The primary outcome was remission of proteinuria. Complete remission (CR) was defined as proteinuria < 0.5 g/d and partial remission (PR) as proteinuria < 1g/d with at least a 50% decline from the baseline with stable renal function (≤ 25% reduction in eGFR).ResultsA total of 96 patients were analyzed, with a mean age of 33.3 ± 10.2 years, baseline eGFR 74.0 ± 30.9 ml/min per 1.73 m2, and urinary protein 2.6 ± 1.2 g/d. In all, 71.9% patients received ≥ 75% of the maximum approved dose of ACEi/ARB. Remission was observed in 36.5% (CR, 6.3%) patients at 3 months and in 55.2% (CR, 31.3%) at 6 months. Patients who failed to achieve remission had lower baseline eGFR (P = 0.002) and serum albumin levels (P< 0.001), asymptomatic hyperuricemia (P < 0.001), and higher proteinuria (P = 0.076). E1 (P= 0.053) and T1/T2 (P = 0.009) lesions were more frequent on histology. The ACEi/ARB had to be discontinued in 17 (17.7%) patients. These patients were older (P= 0.085) with lower eGFR (P < 0.002) and serum albumin levels (P = 0.001) and more E1 (P = 0.012) and T1/T2 (P = 0.001) lesions on histology.ConclusionMeticulous supportive therapy with optimal use of ACEi/ARB achieved remission in half of IgAN patients in this study. Increasing the treatment duration to 6 months improved remission rates. Patients with severe clinical and histological disease were less likely to tolerate and respond to treatment with RAS blockade.

Dataset Information

Blockade of myeloid differentiation 2 attenuates diabetic nephropathy by reducing activation of the renin-angiotensin system in mouse kidneys.

Background and purpose

Experimental approach

Key results

Conclusions and implications

Publications

Blockade of myeloid differentiation 2 attenuates diabetic nephropathy by reducing activation of the renin-angiotensin system in mouse kidneys.

Similar Datasets

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