OBJECTIVE: The cannabinoid receptor type 2 (CB2) has protective effects in chronic degenerative diseases. Our aim was to assess the potential relevance of the CB2 receptor in both human and experimental diabetic nephropathy (DN).RESEARCH DESIGN AND METHODS: CB2 expression was studied in kidney biopsies from patients with advanced DN, in early experimental diabetes, and in cultured podocytes. Levels of endocannabinoids and related enzymes were measured in the renal cortex from diabetic mice. To assess the functional role of CB2, streptozotocin-induced diabetic mice were treated for 14 weeks with AM1241, a selective CB2 agonist. In these animals, we studied albuminuria, renal function, expression of podocyte proteins (nephrin and zonula occludens-1), and markers of both fibrosis (fibronectin and transforming growth factor-β1) and inflammation (monocyte chemoattractant protein-1 [MCP-1], CC chemokine receptor 2 [CCR2], and monocyte markers). CB2 signaling was assessed in cultured podocytes.RESULTS: Podocytes express the CB2 receptor both in vitro and in vivo. CB2 was downregulated in kidney biopsies from patients with advanced DN, and renal levels of the CB2 ligand 2-arachidonoylglycerol were reduced in diabetic mice, suggesting impaired CB2 regulation. In experimental diabetes, AM1241 ameliorated albuminuria, podocyte protein downregulation, and glomerular monocyte infiltration, without affecting early markers of fibrosis. In addition, AM1241 reduced CCR2 expression in both renal cortex and cultured podocytes, suggesting that CB2 activation may interfere with the deleterious effects of MCP-1 signaling.CONCLUSIONS: The CB2 receptor is expressed by podocytes, and in experimental diabetes, CB2 activation ameliorates both albuminuria and podocyte protein loss, suggesting a protective effect of signaling through CB2 in DN.

OBJECTIVE: Cannabinoid receptor 1 (CB1) is localized in the central nervous system and in peripheral tissues involved in energy metabolism control. However, CB1 receptors are also expressed at low level within the glomeruli, and the aim of this study was to investigate their potential relevance in the pathogenesis of proteinuria in experimental type 1 diabetes. RESEARCH DESIGN AND METHODS: Streptozotocin-induced diabetic mice were treated with N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,3-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251), a selective CB1-receptor antagonist, at the dosage of 1 mg · kg−1 · day−1 via intraperitoneal injection for 14 weeks. Urinary albumin excretion was measured by enzyme-linked immunosorbent assay. CB1 receptor expression was studied by immunohistochemistry, immunoblotting, and real-time PCR. Expression of nephrin, podocin, synaptopodin, and zonula occludens-1 (ZO-1) was assessed by immunofluorescence and real-time PCR. Fibronectin, transforming growth factor-β1 (TGF-β1), and connective tissue growth factor (CTGF) mRNA levels were quantitated by real-time PCR. RESULTS: In diabetic mice, the CB1 receptor was overexpressed within the glomeruli, predominantly by glomerular podocytes. Blockade of the CB1 receptor did not affect body weight, blood glucose, and blood pressure levels in either diabetic or control mice. Albuminuria was increased in diabetic mice compared with control animals and was significantly ameliorated by treatment with AM251. Furthermore, CB1 blockade completely prevented diabetes-induced downregulation of nephrin, podocin, and ZO-1. By contrast overexpression of fibronectin, TGF-β1, and CTGF in renal cortex of diabetic mice was unaltered by AM251 administration. CONCLUSIONS: In experimental type 1 diabetes, the CB1 receptor is overexpressed by glomerular podocytes, and blockade of the CB1 receptor ameliorates albuminuria possibly via prevention of nephrin, podocin, and ZO-1 loss.

Gastroesophageal reflux disease (GERD) is defined by the presence of symptoms induced by the reflux of the stomach contents into the esophagus. Although clinical manifestations of GERD typically involve the esophagus, extra-esophageal manifestations are widespread and less known. In this review, we discuss extra-esophageal manifestations of GERD, focusing on clinical presentations, diagnosis, and treatment. Common extra-esophageal manifestations of GERD include chronic cough, asthma, laryngitis, dental erosions, and gingivitis. Extra-esophageal involvement can be present also when classic GERD symptoms are absent, making the diagnosis more challenging. Although available clinical studies are heterogeneous and frequently of low quality, a trial with proton pump inhibitors can be suggested as a first-line diagnostic strategy in case of suspected extra-esophageal manifestations of GERD.

Podocyte injury leading to albuminuria is a characteristic feature of diabetic nephropathy (DN). Hyperglycemia and advanced glycation end products (AGEs) are major determinants of DN. However, the underlying mechanisms of podocyte injury remain poorly understood. The cytosolic protein TNFAIP2/M-Sec is required for tunneling nanotubes (TNTs) formation, which are membrane channels that transiently connect cells, allowing organelle transfer. Podocytes express TNFAIP2 and form TNTs, but the potential relevance of the TNFAIP2-TNT system in DN is unknown. We studied TNFAIP2 expression in both human and experimental DN and the renal effect of tnfaip2 deletion in streptozotocin-induced DN. Moreover, we explored the role of the TNFAIP2-TNT system in podocytes exposed to diabetes-related insults. TNFAIP2 was overexpressed by podocytes in both human and experimental DN and exposure of podocytes to high glucose and AGEs induced the TNFAIP2-TNT system. In diabetic mice, tnfaip2 deletion exacerbated albuminuria, renal function loss, podocyte injury, and mesangial expansion. Moreover, blockade of the autophagic flux due to lysosomal dysfunction was observed in diabetes-injured podocytes both in vitro and in vivo and exacerbated by tnfaip2 deletion. TNTs allowed autophagosome and lysosome exchange between podocytes, thereby ameliorating AGE-induced lysosomal dysfunction and apoptosis. This protective effect was abolished by tnfaip2 deletion, TNT inhibition, and donor cell lysosome damage. By contrast, Tnfaip2 overexpression enhanced TNT-mediated transfer and prevented AGE-induced autophagy and lysosome dysfunction and apoptosis. In conclusion, TNFAIP2 plays an important protective role in podocytes in the context of DN by allowing TNT-mediated autophagosome and lysosome exchange and may represent a novel druggable target. Abbreviations: AGEs: advanced glycation end products; AKT1: AKT serine/threonine kinase 1; AO: acridine orange; ALs: autolysosomes; APs: autophagosomes; BM: bone marrow; BSA: bovine serum albumin; CTSD: cathepsin D; DIC: differential interference contrast; DN: diabetic nephropathy; FSGS: focal segmental glomerulosclerosis; HG: high glucose; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; LMP: lysosomal membrane permeabilization; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PI3K: phosphoinositide 3-kinase; STZ: streptozotocin; TNF: tumor necrosis factor; TNFAIP2: tumor necrosis factor, alpha-induced protein 2; TNTs: tunneling nanotubes; WT: wild type.

OBJECTIVE—Heat shock protein 27 (HSP27) is a member of the small heat shock protein family of proteins. HSP27 expression is enhanced in target tissues of diabetic microvascular complications, and changes in circulating serum HSP27 levels (sHSP27) have been reported in patients with macrovascular disease. We investigated whether sHSP27 levels were associated with micro- and macrovascular complications in type 1 diabetic patients. RESEARCH DESIGN AND METHODS—A cross-sectional, nested, case-control study from the EURODIAB Prospective Complications Study of 531 type 1 diabetic patients was performed. Case subjects (n = 363) were defined as those with one or more complications of diabetes; control subjects (n = 168) were defined as those with no evidence of any complication. We measured sHSP27 levels and investigated their associations with diabetes complications. RESULTS—Mean sHSP27 levels were significantly higher in case subjects with distal symmetrical polyneuropathy (DSP) than in control subjects, even after adjustment for age and albumin excretion rate (AER) (785.9 vs. 574.7 pg/ml, P = 0.03). In logistic regression analysis, sHSP27 levels in the upper quartile were associated with a twofold increased odds ratio (OR) of DSP, independently of conventional risk factors, markers of inflammation, and AER (OR 2.41 [95% CI 1.11–5.24]). CONCLUSIONS—In this large cohort of type 1 diabetic subjects, we found an independent association between sHSP27 and DSP. This suggests that sHSP27 levels may be a novel marker for diabetic neuropathy.