Systemic Monocyte Chemotactic Protein-1 Inhibition Modifies Renal Macrophages and Restores Glomerular Endothelial Glycocalyx and Barrier Function in Diabetic Nephropathy

Abstract

Inhibition of monocyte chemotactic protein-1 (MCP-1) with the Spiegelmer emapticap pegol (NOX-E36) shows long-lasting albuminuria-reducing effects in diabetic nephropathy. MCP-1 regulates inflammatory cell recruitment and differentiation of macrophages. Because the endothelial glycocalyx is also reduced in diabetic nephropathy, we hypothesized that MCP-1 inhibition restores glomerular barrier function through influencing macrophage cathepsin L secretion, thus reducing activation of the glycocalyx-degrading enzyme heparanase. Four weeks of treatment of diabetic Apoe knockout mice with the mouse-specific NOX-E36 attenuated albuminuria without any change in systemic hemodynamics, despite persistent loss of podocyte function. MCP-1 inhibition, however, increased glomerular endothelial glycocalyx coverage, with preservation of heparan sulfate. Mechanistically, both glomerular cathepsin L and heparanase expression were reduced. MCP-1 inhibition resulted in reduced CCR2-expressing Ly6C monocytes in the peripheral blood, without affecting overall number of kidney macrophages at the tissue level. However, the CD206/Mac3 cell ratio, as an index of presence of anti-inflammatory macrophages, increased in diabetic mice after treatment. Functional analysis of isolated renal macrophages showed increased release of IL-10, whereas tumor necrosis factor and cathepsin L release was reduced, further confirming polarization of tissue macrophages toward an anti-inflammatory phenotype during mouse-specific NOX-E36 treatment. We show that MCP-1 inhibition restores glomerular endothelial glycocalyx and barrier function and reduces tissue inflammation in the presence of ongoing diabetic injury, suggesting a therapeutic potential for NOX-E36 in diabetic nephropathy.

Salt increases monocyte CCR2 expression and inflammatory responses in humans

“…Furthermore, proinflammatory activation and CCR2 have been implicated in acute and chronic kidney disease (9,40,41) and cardiovascular disease (6,42,43), underlining the relevance of our findings for kidney and cardiovascular patients. Patients with chronic kidney disease show increased arterial inflammation and increased proinflammatory phenotype of monocytes, as displayed by increased CCR7 and CCR2 expression (9).…”

Recent novel approaches to limit oxidative stress and inflammation in diabetic complications

“…Additionally, the observed correlation between the number of interstitial CD68+ macrophages and renal function indicated that macrophages play a role in DN progression 66. Since it is known that MCP‐1 can regulate recruitment of macrophages, a recent study by Boels et al 67. examined the effect of inhibiting MCP‐1 in diabetic mice.…”

“…MCP‐1 inhibition with Spiegelmer emapticap pegol (NOX‐E36) in diabetic mice resulted in reduced CCR2 expression in circulating monocytes and a reduction in albuminuria, the albumin‐to‐creatinine ratio (ACR) and inflammation without changing the overall number of macrophages in the kidney. Instead, it was observed that diabetic mice receiving NOX‐E36 had a switch in macrophage cytokine profile towards an anti‐inflammatory phenotype 67. When NOX‐E36 was given for 3 months in a randomised double‐blind placebo controlled Phase IIa clinical trial, a 29% reduction in ACR was observed with no change to GFR 68…”

“…66 Additionally, the observed correlation between the number of interstitial CD68+ macrophages and renal function indicated that macrophages play a role in DN progression. 66 Since it is known that MCP-1 can regulate recruitment of macrophages, a recent study by Boels et al 67 examined the effect of inhibiting MCP-1 in diabetic mice. MCP-1 inhibition with Spiegelmer emapticap pegol (NOX-E36) in diabetic mice resulted in reduced CCR2 expression in circulating monocytes and a reduction in albuminuria, the albumin-tocreatinine ratio (ACR) and inflammation without changing the overall number of macrophages in the kidney.…”

“…Instead, it was observed that diabetic mice receiving NOX-E36 had a switch in macrophage cytokine profile towards an antiinflammatory phenotype. 67 When NOX-E36 was given for 3 months in a randomised double-blind placebo controlled Phase IIa clinical trial, a 29% reduction in ACR was observed with no change to GFR. 68 Activation and/or enhanced expression of antioxidant defence systems such as GPx-1, catalase, thioredoxin 1 and 2 (TRX1 and TRX2) or SOD1 and SOD2 is another possible strategy to prevent DN.…”