Lipoxins Regulate the Early Growth Response-1 Network and Reverse Diabetic Kidney Disease.

Background The failure of spontaneous resolution underlies chronic inflammatory conditions, including microvascular complications of diabetes such as diabetic kidney disease. The identification of endogenously generated molecules that promote the physiologic resolution of inflammation suggests that these bioactions may have therapeutic potential in the context of chronic inflammation. Lipoxins (LXs) are lipid mediators that promote the resolution of inflammation.Methods We investigated the potential of LXA4 and a synthetic LX analog (Benzo-LXA4) as therapeutics in a murine model of diabetic kidney disease, ApoE-/- mice treated with streptozotocin.Results Intraperitoneal injection of LXs attenuated the development of diabetes-induced albuminuria, mesangial expansion, and collagen deposition. Notably, LXs administered 10 weeks after disease onset also attenuated established kidney disease, with evidence of preserved kidney function. Kidney transcriptome profiling defined a diabetic signature (725 genes; false discovery rate P≤0.05). Comparison of this murine gene signature with that of human diabetic kidney disease identified shared renal proinflammatory/profibrotic signals (TNF-α, IL-1ß, NF-κB). In diabetic mice, we identified 20 and 51 transcripts regulated by LXA4 and Benzo-LXA4, respectively, and pathway analysis identified established (TGF-ß1, PDGF, TNF-α, NF-κB) and novel (early growth response-1 [EGR-1]) networks activated in diabetes and regulated by LXs. In cultured human renal epithelial cells, treatment with LXs attenuated TNF-α-driven Egr-1 activation, and Egr-1 depletion prevented cellular responses to TGF-ß1 and TNF-αConclusions These data demonstrate that LXs can reverse established diabetic complications and support a therapeutic paradigm to promote the resolution of inflammation.

Lipoxins attenuate renal fibrosis by inducing let-7c and suppressing TGFßR1.

Lipoxins, which are endogenously produced lipid mediators, promote the resolution of inflammation, and may inhibit fibrosis, suggesting a possible role in modulating renal disease. Here, lipoxin A4 (LXA4) attenuated TGF-ß1-induced expression of fibronectin, N-cadherin, thrombospondin, and the notch ligand jagged-1 in cultured human proximal tubular epithelial (HK-2) cells through a mechanism involving upregulation of the microRNA let-7c. Conversely, TGF-ß1 suppressed expression of let-7c. In cells pretreated with LXA4, upregulation of let-7c persisted despite subsequent stimulation with TGF-ß1. In the unilateral ureteral obstruction model of renal fibrosis, let-7c upregulation was induced by administering an LXA4 analog. Bioinformatic analysis suggested that targets of let-7c include several members of the TGF-ß1 signaling pathway, including the TGF-ß receptor type 1. Consistent with this, LXA4-induced upregulation of let-7c inhibited both the expression of TGF-ß receptor type 1 and the response to TGF-ß1. Overexpression of let-7c mimicked the antifibrotic effects of LXA4 in renal epithelia; conversely, anti-miR directed against let-7c attenuated the effects of LXA4. Finally, we observed that several let-7c target genes were upregulated in fibrotic human renal biopsies compared with controls. In conclusion, these results suggest that LXA4-mediated upregulation of let-7c suppresses TGF-ß1-induced fibrosis and that expression of let-7c targets is dysregulated in human renal fibrosis.

Lipoxins Protect Against Inflammation in Diabetes-Associated Atherosclerosis.

Increasing evidence points to the fact that defects in the resolution of inflammatory pathways predisposes individuals to the development of chronic inflammatory diseases, including diabetic complications such as accelerated atherosclerosis. The resolution of inflammation is dynamically regulated by the production of endogenous modulators of inflammation, including lipoxin A4 (LXA4). Here, we explored the therapeutic potential of LXA4 and a synthetic LX analog (Benzo-LXA4) to modulate diabetic complications in the streptozotocin-induced diabetic ApoE-/- mouse and in human carotid plaque tissue ex vivo. The development of diabetes-induced aortic plaques and inflammatory responses of aortic tissue, including the expression of vcam-1, mcp-1, il-6, and il-1ß, was significantly attenuated by both LXA4 and Benzo-LXA4 in diabetic ApoE-/- mice. Importantly, in mice with established atherosclerosis, treatment with LXs for a 6-week period, initiated 10 weeks after diabetes onset, led to a significant reduction in aortic arch plaque development (19.22 ± 2.01% [diabetic]; 12.67 ± 1.68% [diabetic + LXA4]; 13.19 ± 1.97% [diabetic + Benzo-LXA4]). Secretome profiling of human carotid plaque explants treated with LXs indicated changes to proinflammatory cytokine release, including tumor necrosis factor-α and interleukin-1ß. LXs also inhibited platelet-derived growth factor-stimulated vascular smooth muscle cell proliferation and transmigration and endothelial cell inflammation. These data suggest that LXs may have therapeutic potential in the context of diabetes-associated vascular complications.

Protective Effect of let-7 miRNA Family in Regulating Inflammation in Diabetes-Associated Atherosclerosis.

The let-7 miRNA family plays a key role in modulating inflammatory responses. Vascular smooth muscle cell (SMC) proliferation and endothelial cell (EC) dysfunction are critical in the pathogenesis of atherosclerosis, including in the setting of diabetes. Here we report that let-7 levels are decreased in diabetic human carotid plaques and in a model of diabetes-associated atherosclerosis, the diabetic ApoE-/- mouse. In vitro platelet-derived growth factor (PDGF)- and tumor necrosis factor-α (TNF-α)-induced vascular SMC and EC activation was associated with reduced let-7 miRNA expression via Lin28b, a negative regulator of let-7 biogenesis. Ectopic overexpression of let-7 in SMCs inhibited inflammatory responses including proliferation, migration, monocyte adhesion, and nuclear factor-κB activation. The therapeutic potential of restoring let-7 levels using a let-7 mimic was tested: in vitro in SMCs using an endogenous anti-inflammatory lipid (lipoxin A4), ex vivo in murine aortas, and in vivo via tail vein injection in a 24-h murine model. Furthermore, we delivered let-7 mimic to human carotid plaque ex vivo and observed significant changes to the secretome in response to let-7 therapy. Restoration of let-7 expression could provide a new target for an anti-inflammatory approach in diabetic vascular disease.

Lipoxin A4 Attenuates Obesity-Induced Adipose Inflammation and Associated Liver and Kidney Disease.

The role of inflammation in obesity-related pathologies is well established. We investigated the therapeutic potential of LipoxinA4 (LXA4:5(S),6(R),15(S)-trihydroxy-7E,9E,11Z,13E,-eicosatetraenoic acid) and a synthetic 15(R)-Benzo-LXA4-analog as interventions in a 3-month high-fat diet (HFD; 60% fat)-induced obesity model. Obesity caused distinct pathologies, including impaired glucose tolerance, adipose inflammation, fatty liver, and chronic kidney disease (CKD). Lipoxins (LXs) attenuated obesity-induced CKD, reducing glomerular expansion, mesangial matrix, and urinary H2O2. Furthermore, LXA4 reduced liver weight, serum alanine-aminotransferase, and hepatic triglycerides. LXA4 decreased obesity-induced adipose inflammation, attenuating TNF-α and CD11c(+) M1-macrophages (MΦs), while restoring CD206(+) M2-MΦs and increasing Annexin-A1. LXs did not affect renal or hepatic MΦs, suggesting protection occurred via attenuation of adipose inflammation. LXs restored adipose expression of autophagy markers LC3-II and p62. LX-mediated protection was demonstrable in adiponectin(-/-) mice, suggesting that the mechanism was adiponectin independent. In conclusion, LXs protect against obesity-induced systemic disease, and these data support a novel therapeutic paradigm for treating obesity and associated pathologies.

Stereospecific synthesis of chiral 2,3-dihydro-1,4-benzodithiine and methyl-2,3-dihydro-1,4-benzodithiine derivatives and their toxic effects on Trypanosoma brucei.

Preparation of chiral 2,3-dihydro-1,4-benzodithiine and methyl-2,3-dihydro-1,4-benzodithiine derivatives with known absolute configurations from the easily accessible chiral synthons benzyl 4-O-trifloxy-2,3-anhydro-beta-L-ribopyranoside and benzyl 4-O-trifloxy-2,3-anhydro-alpha-D-ribopyranoside is described. These compounds showed significant in vitro toxicity of the bloodstream form of Trypanosoma brucei with an IC50 of 11 microM. The parasites' energy metabolism and consumption of oxygen were found to be affected during incubation.