The mechanism of atopic march may be the ‘social’ event of cells and molecules (Review)

The skin, the conjunctivae, the airways and the digestive tract compose a huge vulnerable biological surface, which is exposed to the external environment. An allergen can often trigger an allergic reaction at a number of sites or result in an atopic march. However, the mechanism of atopic march remains unclear. Less attention has been paid to the connection between the primary site and the atopic site, because current knowledge is established directly against harmful factors. Allergic hypersensitivity manifests in parts of the human body far away from the allergen. Growing evidence suggests that the epithelial cells serve as the 'engine' which initiates an allergic reaction through the production of large quantities of cytokines, chemokines and growth factors. Because the epithelial cells cover the entire surface of the skin, the conjunctivae, the airways, and the digestive tract, and are positioned at the terminals of neurons and the blood supply, the connection between the primary site and the atopic site can not be easily understood by the current knowledge of anatomy and of the neuroendocrine immune network. What is the linkage between these huge vulnerable biologic surfaces? This article highlights selected frontiers in allergy research of atopic march, and focuses on recently attained insights into the cellular and molecular events of primary and atopic lesions in the allergy progress. Special attention is paid to the homogeneity of the cellular and molecular events on the huge vulnerable surface. Based on currently available data we conclude that the skin, conjunctivae, airways and digestive tract may join together to form the frontier 'commonwealth union' in order to fight the allergen. The epithelial cells are the 'engine' as well as the main target which initiates both primary and atopic inflammatory reactions. The atopic lesion may 'duplicate' the primary contacted site of cellular and molecular events. The atopic march may be due to the intrinsic 'social' involvements of the positioned epithelial cells, but may not be totally controlled by the anatomic connection or the circulating systemic factors involved in allergy pathogenesis

Ecdysone Elicits Chronic Renal Impairment via Mineralocorticoid-Like Pathogenic Activities

Background/Aims: Ecdysteroids are steroidal insect molting hormones that also exist in herbs. Ecdysteroid-containing adaptogens have been popularly used to improve well-being and by bodybuilders for muscle growth. However, the use of ecdysone in mammals is also associated with kidney growth and enlargement, indications of disturbed kidney homeostasis. The underlying pathogenic mechanism remains to be clarified. Methods: Virtual screening tools were employed to identify compounds that are homologous to ecdysone and to predict putative ecdysone-interacting proteins. The kidney effect of ecdysone was examined in vitro and in vivo and compared with that of aldosterone. Cellular apoptosis was estimated by terminal deoxynucleotidyl transferase dUTP nick end labeling. Cell motility was assessed by scratch-wound cell migration assay. Blood urea nitrogen was measured to evaluate renal function. Western immunblot analysis was employed to determine the expression profile of interested proteins. Results: Computational molecular structure analysis revealed that ecdysone is highly homologous to aldosterone. Moreover, virtual screening based on compound-protein interaction profiles identified the Mineralocorticoid Receptor (MR) to potentially interact with ecdysone. Accordingly, to assess potential biological functions of ecdysone in mammals, ecdysone was applied to mineralocorticoid-sensitive inner medullar collecting duct cells. Ecdysone induced mesenchymal accumulation of extracellular matrix and epithelial dedifferentiation characterized by de novo expression of α-smooth muscle actin. In addition, ecdysone elicited cellular apoptosis and retarded cell motility, akin to the effect of aldosterone. In vivo, daily treatment of mice with ecdysone increased cell apoptosis in the kidney, impaired renal function and elicited early signs of renal fibrogenesis, marked by deposition of collagen and fibronectin in tubulointerstitium, reminiscent of the action of aldosterone. The MR signaling pathway is likely responsible for the cellular and pathobiological effects of ecdysone, as evidenced by strong ecdysone-induced MR nuclear translocation in renal tubular cells both in vitro and in vivo, while blockade of MR by concomitant spironolactone treatment largely abolished the detrimental effects of ecdysone. Conclusion: Our findings suggest that ecdysone induces mineralocorticoid-dependent activities that impair renal function and elicit renal injury

Suramin Alleviates Glomerular Injury and Inflammation in the Remnant Kidney

Background: Recently, we demonstrated that suramin, a compound that inhibits the interaction of multiple cytokines/ growth factors with their receptors, inhibits activation and proliferation of renal interstitial fibroblasts, and attenuates the development of renal interstitial fibrosis in the murine model of unilateral ureteral obstruction (UUO). However, it remains unclear whether suramin can alleviate glomerular and vascular lesions, which are not typical pathological changes in the UUO model. So we tested the efficacy of suramin in the remnant kidney after 5/6 nephrectomy, a model characterized by the slow development of glomerulosclerosis, vascular sclerosis, tubulointerstitial fibrosis and renal inflammation, mimicking human disease. Methods/Findings: 5/6 of normal renal mass was surgically ablated in male rats. On the second week after surgery, rats were randomly divided into suramin treatment and non-treatment groups. Suramin was given at 10 mg/kg once per week for two weeks. In the remnant kidney of mice receiving suramin, glomerulosclerosis and vascular sclerosis as well as inflammation were ameliorated. Suramin also attenuated tubular expression of two chemokines, monocyte chemoattractant protein-1 and regulated upon expression normal T cell expressed and secreted (RANTES). After renal mass ablation, several intracellular molecules associated with renal fibrosis, including NF-kappaB p65, Smad-3, signal transducer and activator of transcription-3 and extracellular regulated kinase 1/2, are phosphorylated; suramin treatment inhibited thei

The redox-sensitive GSK3β is a key regulator of glomerular podocyte injury in type 2 diabetic kidney disease

Emerging evidence suggests that GSK3β, a redox-sensitive transducer downstream of insulin signaling, acts as a convergent point for myriad pathways implicated in kidney injury, repair, and regeneration. However, its role in diabetic kidney disease remains controversial. In cultured glomerular podocytes, exposure to a milieu of type 2 diabetes elicited prominent signs of podocyte injury and degeneration, marked by loss of homeostatic marker proteins like synaptopodin, actin cytoskeleton disruption, oxidative stress, apoptosis, and stress-induced premature senescence, as shown by increased staining for senescence-associated β-galactosidase activity, amplified formation of γH2AX foci, and elevated expression of mediators of senescence signaling, like p21 and p16INK4A. These degenerative changes coincided with GSK3β hyperactivity, as evidenced by GSK3β overexpression and reduced inhibitory phosphorylation of GSK3β, and were averted by tideglusib, a highly-selective small molecule inhibitor of GSK3β. In agreement, post-hoc analysis of a publicly-available glomerular transcriptomics dataset from patients with type 2 diabetic nephropathy revealed that the curated diabetic nephropathy-related gene set was enriched in high GSK3β expression group. Mechanistically, GSK3β-modulated nuclear factor Nrf2 signaling is involved in diabetic podocytopathy, because GSK3β knockdown reinforced Nrf2 antioxidant response and suppressed oxidative stress, resulting in an improvement in podocyte injury and senescence. Conversely, ectopic expression of the constitutively active mutant of GSK3β impaired Nrf2 antioxidant response and augmented oxidative stress, culminating in an exacerbated diabetic podocyte injury and senescence. Moreover, IRS-1 was found to be a cognate substrate of GSK3β for phosphorylation at IRS-1S332, which negatively regulates IRS-1 activity. GSK3β hyperactivity promoted IRS-1 phosphorylation, denoting a desensitized insulin signaling. Consistently, in vivo in db/db mice with diabetic nephropathy, GSK3β was hyperactive in glomerular podocytes, associated with IRS-1 hyperphosphorylation, impaired Nrf2 response and premature senescence. Our finding suggests that GSK3β is likely a novel therapeutic target for treating type 2 diabetic glomerular injury

Mineralocorticoid receptor: A hidden culprit for hemodialysis vascular access dysfunction

Hemodialysis vascular access dysfunction is a common and intractable problem in clinical practice with no definitive therapy yet available. As a key mediator of vascular and cardiac maladaptive remodeling, mineralocorticoid receptor (MR) plays a pivotal role in vascular fibrosis and intimal hyperplasia (IH) and is potentiated locally in hemodialysis vascular access following diverse injuries, like barotrauma, cannulation and shear stress. MR-related genomic and non-genomic pathways are responsible for triggering vascular smooth muscle cell activation, proliferation, migration and extracellular matrix overproduction. In endothelial cells, MR signaling diminishes nitric oxide production and its bioavailability, but amplifies reactive oxygen species, leading to an inflammatory state. Moreover, MR favors macrophage polarization towards a pro-inflammatory phenotype. In clinical settings like post-angioplasty or stenting restenosis, the beneficial effect of MR antagonists on vascular fibrosis and IH has been validated. In aggregate, therapeutic targeting of MR may provide a new avenue to prevent hemodialysis vascular access dysfunction. Keywords: Mineralocorticoid receptor, Aldosterone, Arteriovenous fistula failure, Intimal hyperplasia, Hemodialysis vascular access dysfunctio

Tanshinone IIA Attenuates Renal Fibrosis after Acute Kidney Injury in a Mouse Model through Inhibition of Fibrocytes Recruitment

Acute kidney injury (AKI) is associated with an increased risk of developing advanced chronic kidney disease (CKD). Yet, effective interventions to prevent this conversion are unavailable for clinical practice. In this study, we examined the beneficial effects of Tanshinone IIA on renal fibrosis in a mouse model of folic acid induced AKI. We found that Tanshinone IIA treatment significantly attenuated the folic acid elicited kidney dysfunction on days 3, 14, and 28. This effect was concomitant with a much lessened accumulation of fibronectin and collagen in tubulointerstitium 28 days after folic acid injury, denoting an ameliorated renal fibrosis. The kidney protective and antifibrotic effect of Tanshinone IIA was likely attributable to an early inhibition of renal recruitment of fibrocytes positive for both CD45 and collagen I. Mechanistically, Tanshinone IIA treatment not only markedly diminished renal expression of chemoattractants for fibrocytes such as TGFβ1 and MCP-1, but also significantly reduced circulating fibrocytes at the acute phase of kidney injury. These data suggested that Tanshinone IIA might be a novel therapy for preventing progression of CKD after AKI

Microdose Lithium Protects against Pancreatic Islet Destruction and Renal Impairment in Streptozotocin-Elicited Diabetes

Psychiatric use of lithium has been associated with hypoglycemic effects, but its effect on type 1 diabetes mellitus (T1D) is unknown. In streptozotocin (STZ) induced murine models of T1D, microdose lithium therapy improved hyperglycemia, attenuated body weight loss and prevented early signs of diabetic kidney injury. This beneficial effect was associated with preservation of pancreatic islet histology and β-cell production of insulin as well as mitigated oxidative damage of islets. Mechanistically, lithium in islets cells induced inhibitory phosphorylation of glycogen synthase kinase 3β (GSK3β), the major molecular target of lithium that has been recently implicated in non-canonical regulation of Nrf2 activity. In turn, Nrf2 antioxidant response was potentiated in islets, marked by nuclear translocation of Nrf2 and augmented expression of its target antioxidant enzyme heme oxygenase 1 (HO-1). Conversely, cotreatment with trigonelline, a selective blockade of Nrf2, offset the lithium enhanced Nrf2 antioxidant response in islets, blunted the protective effect of lithium on pancreatic islets and β-cells, and abolished the hypoglycemic activity of lithium in STZ-injured mice. Collectively, our findings suggest that microdose lithium confers a protective effect on islet β-cells via targeting the GSK3β-regulated Nrf2 antioxidant response and thereby ameliorates T1D and its related kidney impairment

Smad3-mSin3A-HDAC1 Complex is Required for TGF-β1-Induced Transcriptional Inhibition of PPARγ in Mouse Cardiac Fibroblasts

Background: We have recently demonstrated that activated transforming growth factor-β (TGF-β) signaling suppresses myocardial peroxisome proliferator-activated receptor γ (PPARγ) expression in the pressure overloaded heart. In this study, we aim to further define the molecular mechanisms that underlie TGF-β-induced PPARγ transcriptional inhibition. Methods: Adult mouse cardiac fibroblasts were isolated and cultured. PPARγ promoter activity was measured by the dual-Luciferase reporter assay. Interactions between transcription factors and the target gene were identified. Results: In cultured cardiac fibroblasts transfected with a plasmid containing a human PPARγ promoter, co-transfection of Smad3 and Smad4, but not Smad2, plasmids significantly enhanced TGF-β1-induced inhibition of PPARγ promoter activity. Promoter deletion analysis and site-directed mutagenesis assays defined two Smad binding elements on the promoter of the PPARγ gene. Utilizing chromatin immunoprecipitation analysis and DNA-affinity precipitation methods, we demonstrated that the transcriptional regulatory complex consisting of Smad3, mSin3A and HDAC1 bound to the promoter of the PPARγ gene in cardiac fibroblasts in response to TGF-β1 stimulation. Either silencing endogenous mSin3A expression by Lentivirus-mediated transduction of mSin3A shRNA or pretreatment with the specific HDAC1 inhibitor MS-275 effectively attenuated TGF-β-induced transcriptional suppression of PPARγ. Conclusion: These results suggest that TGF-β1-induced inhibition of PPARγ transcription depends on formation of a functional transcriptional regulatory complex that includes Smad3, mSin3A and HDAC1 at the PPARγ promoter