Epimeric vitamin D and cardiovascular structure and function in advanced CKD and after kidney transplantation.

BACKGROUND: 25-hydroxyvitamin D can undergo C-3 epimerization to produce 3-epi-25(OH)D3. 3-epi-25(OH)D3 levels decline in chronic kidney disease (CKD), but its role in regulating the cardiovascular system is unknown. Herein, we examined the relationship between 3-epi-25(OH)D3, and cardiovascular functional and structural endpoints in patients with CKD. METHODS: We examined n = 165 patients with advanced CKD from the Cardiopulmonary Exercise Testing in Renal Failure and After Kidney Transplantation (CAPER) study cohort, including those who underwent kidney transplant (KTR, n = 76) and waitlisted patients who did not (NTWC, n = 89). All patients underwent cardiopulmonary exercise testing and echocardiography at baseline, 2 months and 12 months. Serum 3-epi-25(OH)D3 was analyzed by liquid chromatography-tandem mass spectrometry. RESULTS: Patients were stratified into quartiles of baseline 3-epi-25(OH)D3 (Q1: <0.4 ng/mL, n = 51; Q2: 0.4 ng/mL, n = 26; Q3: 0.5-0.7 ng/mL, n = 47; Q4: ≥0.8 ng/mL, n = 41). Patients in Q1 exhibited lower peak oxygen uptake [VO2Peak = 18.4 (16.2-20.8) mL/min/kg] compared with Q4 [20.8 (18.6-23.2) mL/min/kg; P = .009]. Linear mixed regression model showed that 3-epi-25(OH)D3 levels increased in KTR [from 0.47 (0.30) ng/mL to 0.90 (0.45) ng/mL] and declined in NTWC [from 0.61 (0.32) ng/mL to 0.45 (0.29) ng/mL; P < .001]. Serum 3-epi-25(OH)D3 was associated with VO2Peak longitudinally in both groups [KTR: ß (standard error) = 2.53 (0.56), P < .001; NTWC: 2.73 (0.70), P < .001], but was not with left ventricular mass or arterial stiffness. Non-epimeric 25(OH)D3, 24,25(OH)2D3 and the 25(OH)D3:24,25(OH)2D3 ratio were not associated with any cardiovascular outcome (all P > .05). CONCLUSIONS: Changes in 3-epi-25(OH)D3 levels may regulate cardiovascular functional capacity in patients with advanced CKD.

Mapping cardiac remodeling in chronic kidney disease.

Patients with advanced chronic kidney disease (CKD) mostly die from sudden cardiac death and recurrent heart failure. The mechanisms of cardiac remodeling are largely unclear. To dissect molecular and cellular mechanisms of cardiac remodeling in CKD in an unbiased fashion, we performed left ventricular single-nuclear RNA sequencing in two mouse models of CKD. Our data showed a hypertrophic response trajectory of cardiomyocytes with stress signaling and metabolic changes driven by soluble uremia-related factors. We mapped fibroblast to myofibroblast differentiation in this process and identified notable changes in the cardiac vasculature, suggesting inflammation and dysfunction. An integrated analysis of cardiac cellular responses to uremic toxins pointed toward endothelin-1 and methylglyoxal being involved in capillary dysfunction and TNFα driving cardiomyocyte hypertrophy in CKD, which was validated in vitro and in vivo. TNFα inhibition in vivo ameliorated the cardiac phenotype in CKD. Thus, interventional approaches directed against uremic toxins, such as TNFα, hold promise to ameliorate cardiac remodeling in CKD.

FGF23 and Cardiovascular Structure and Function in Advanced Chronic Kidney Disease.

Background: Fibroblast growth factor 23 (FGF23) is a bone-derived phosphatonin that is elevated in chronic kidney disease (CKD) and has been implicated in the development of cardiovascular disease. It is unknown whether elevated FGF23 in CKD is associated with impaired cardiovascular functional capacity, as assessed by maximum exercise oxygen consumption (VO2Max). We sought to determine whether FGF23 is associated with cardiovascular functional capacity in patients with advanced CKD and after improvement of VO2Max by kidney transplantation. Methods: We performed secondary analysis of 235 patients from the Cardiopulmonary Exercise Testing in Renal Failure and After Kidney Transplantation (CAPER) cohort, which recruited patients with stage 5 CKD who underwent kidney transplantation or were waitlisted and hypertensive controls. All patients underwent cardiopulmonary exercise testing (CPET) and echocardiography and were followed longitudinally for 1 year after study enrollment. Results: Patients across FGF23 quartiles differed in BMI (P=0.004) and mean arterial pressure (P<0.001) but did not significantly differ in sex (P=0.5) or age (P=0.08) compared with patients with lower levels of FGF23. Patients with higher FGF23 levels had impaired VO2Max (Q1: 24.2±4.8 ml/min per kilogram; Q4: 18.6±5.2 ml/min per kilogram; P<0.001), greater left ventricular mass index (LVMI; P<0.001), reduced HR at peak exercise (P<0.001), and maximal workload (P<0.001). Kidney transplantation conferred a significant decline in FGF23 at 2 months (P<0.001) before improvement in VO2Max at 1 year (P=0.008). Multivariable regression modeling revealed that changes in FGF23 was significantly associated with VO2Max in advanced CKD (P<0.001) and after improvement after kidney transplantation (P=0.006). FGF23 was associated with LVMI before kidney transplantation (P=0.003), however this association was lost after adjustment for dialysis status (P=0.4). FGF23 was not associated with LVMI after kidney transplantation in all models. Conclusions: FGF23 levels are associated with alterations in cardiovascular functional capacity in advanced CKD and after kidney transplantation. FGF23 is only associated with structural cardiac adaptations in advanced CKD but this was modified by dialysis status, and was not associated after kidney transplantation.

Initiation of Dialysis Is Associated With Impaired Cardiovascular Functional Capacity.

Background The transition to dialysis period carries a substantial increased cardiovascular risk in patients with chronic kidney disease. Despite this, alterations in cardiovascular functional capacity during this transition are largely unknown. The present study therefore sought to assess ventilatory exercise response measures in patients within 1 year of initiating dialysis. Methods and Results We conducted a cross-sectional study of 241 patients with chronic kidney disease stage 5 from the CAPER (Cardiopulmonary Exercise Testing in Renal Failure) study and from the intradialytic low-frequency electrical muscle stimulation pilot randomized controlled trial cohorts. Patients underwent cardiopulmonary exercise testing and echocardiography. Of the 241 patients (age, 48.9 [15.0] years; 154 [63.9%] men), 42 were predialytic (mean estimated glomerular filtration rate, 14 mL·min-1·1.73 m-2), 54 had a dialysis vintage ≤12 months, and 145 had a dialysis vintage >12 months. Dialysis vintage ≤12 months exhibited a significantly impaired cardiovascular functional capacity, as assessed by oxygen uptake at peak exercise (18.7 [5.8] mL·min-1·kg-1) compared with predialysis (22.7 [5.2] mL·min-1·kg-1; P<0.001). Dialysis vintage ≤12 months also exhibited reduced peak workload, impaired peak heart rate, reduced circulatory power, and increased left ventricular mass index (P<0.05 for all) compared with predialysis. After excluding those with prior kidney transplant, dialysis vintage >12 months exhibited a lower oxygen uptake at peak exercise (17.0 [4.9] mL·min-1·kg-1) compared with dialysis vintage ≤12 months (18.9 [5.9] mL·min-1·kg-1; P=0.033). Conclusions Initiating dialysis is associated with a significant impairment in oxygen uptake at peak exercise and overall decrements in ventilatory and hemodynamic exercise responses that predispose patients to functional dependence. The magnitude of these changes is comparable to the differences between low-risk New York Heart Association class I and higher-risk New York Heart Association class II to IV heart failure.

Integrin α5 Is Regulated by miR-218-5p in Endothelial Progenitor Cells.

BACKGROUND: Endothelial cell injury is a common nidus of renal injury in patients and consistent with the high prevalence of AKI reported during the coronavirus disease 2019 pandemic. This cell type expresses integrin α5 (ITGA5), which is essential to the Tie2 signaling pathway. The microRNA miR-218-5p is upregulated in endothelial progenitor cells (EPCs) after hypoxia, but microRNA regulation of Tie2 in the EPC lineage is unclear. METHODS: We isolated human kidney-derived EPCs (hkEPCs) and surveyed microRNA target transcripts. A preclinical model of ischemic kidney injury was used to evaluate the effect of hkEPCs on capillary repair. We used a genetic knockout model to evaluate the effect of deleting endogenous expression of miR-218 specifically in angioblasts. RESULTS: After ischemic in vitro preconditioning, miR-218-5p was elevated in hkEPCs. We found miR-218-5p bound to ITGA5 mRNA transcript and decreased ITGA5 protein expression. Phosphorylation of 42/44 MAPK decreased by 73.6% in hkEPCs treated with miR-218-5p. Cells supplemented with miR-218-5p downregulated ITGA5 synthesis and decreased 42/44 MAPK phosphorylation. In a CD309-Cre/miR-218-2-LoxP mammalian model (a conditional knockout mouse model designed to delete pre-miR-218-2 exclusively in CD309+ cells), homozygotes at e18.5 contained avascular glomeruli, whereas heterozygote adults showed susceptibility to kidney injury. Isolated EPCs from the mouse kidney contained high amounts of ITGA5 and showed decreased migratory capacity in three-dimensional cell culture. CONCLUSIONS: These results demonstrate the critical regulatory role of miR-218-5p in kidney EPC migration, a finding that may inform efforts to treat microvascular kidney injury via therapeutic cell delivery.

Two hits to the renin-angiotensin system may play a key role in severe COVID-19.

The spike glycoprotein on the virion surface docking onto the angiotensin-converting enzyme (ACE) 2 dimer is an essential step in the process of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in human cells-involves downregulation of ACE2 expression with systemic renin-angiotensin system (RAS) imbalance and promotion of multi-organ damage. In general, the RAS induces vasoconstriction, hypertension, inflammation, fibrosis, and proliferation via the ACE/Ang II/Ang II type 1 receptor (AT1R) axis and induces the opposite effects via the ACE2/Ang (1-7)/Mas axis. The RAS may be activated by chronic inflammation in hypertension, diabetes, obesity, and cancer. SARS-CoV-2 induces the ACE2 internalization and shedding, leading to the inactivation of the ACE2/Ang (1-7)/Mas axis. Therefore, we hypothesize that two hits to the RAS drives COVID-19 progression. In brief, the first hit originates from chronic inflammation activating the ACE/Ang II/AT1R axis, and the second originates from the COVID-19 infection inactivating the ACE2/Ang (1-7)/Mas axis. Moreover, the two hits to the RAS may be the primary reason for increased mortality in patients with COVID-19 who have comorbidities and may serve as a therapeutic target for COVID-19 treatment.

miR-218 Expressed in Endothelial Progenitor Cells Contributes to the Development and Repair of the Kidney Microvasculature.

Ischemia due to hypoperfusion is one of the most common forms of acute kidney injury. We hypothesized that kidney hypoxia initiates the up-regulation of miR-218 expression in endothelial progenitor cells (EPCs) to guide endocapillary repair. Murine renal artery-derived EPCs (CD34+/CD105-) showed down-regulation of mmu-Mir218-5p/U6 RNA ratio after ischemic injury, while in human renal arteries, MIR218-5p expression was up-regulated after ischemic injury. MIR218 expression was clarified in cell culture experiments in which increases in both SLIT3 and MIR218-2-5p expressions were observed after 5 minutes of hypoxia. ROBO1 transcript, a downstream target of MIR218-2-5p, showed inverse expression to MIR218-2-5p. EPCs transfected with a MIR218-5p inhibitor in three-dimensional normoxic culture showed premature capillary formation. Organized progenitor cell movement was reconstituted when cells were co-transfected with Dicer siRNA and low-dose Mir218-5p mimic. A Mir218-2 knockout was generated to assess the significance of miR-218-2 in a mammalian model. Mir218-2-5p expression was decreased in Mir218-2-/- embryos at E16.5. Mir218-2-/- decreased CD34+ angioblasts in the ureteric bud at E16.5 and were nonviable. Mir218-2+/- decreased peritubular capillary density at postnatal day 14 and increased serum creatinine after ischemia in adult mice. Systemic injection of miR-218-5p decreased serum creatinine after injury. These experiments demonstrate that miR-218 expression can be triggered by hypoxia and modulates EPC migration in the kidney.

Klotho: A Major Shareholder in Vascular Aging Enterprises.

Accelerated vascular aging is a condition that occurs as a complication of several highly prevalent inflammatory conditions such as chronic kidney disease, cancer, HIV infection and diabetes. Age-associated vascular alterations underlie a continuum of expression toward clinically overt cardiovascular disease. This has contributed to the striking epidemiologic transition whereby such noncommunicable diseases have taken center stage as modern-day global epidemics and public health problems. The identification of α-Klotho, a remarkable protein that confers powerful anti-aging properties has stimulated significant interest. In fact, emerging data have provided fundamental rationale for Klotho-based therapeutic intervention for vascular diseases and multiple other potential indications. However, the application of such discoveries in Klotho research remains fragmented due to significant gaps in our molecular understanding of Klotho biology, as well as hurdles in clinical research and experimental barriers that must first be overcome. These advances will be critical to establish the scientific platform from which future Klotho-based interventional trials and therapeutic enterprises can be successfully launched.

Pre-clinical model of severe glutathione peroxidase-3 deficiency and chronic kidney disease results in coronary artery thrombosis and depressed left ventricular function.

Background: Chronic kidney disease (CKD) patients have deficient levels of glutathione peroxidase-3 (GPx3). We hypothesized that GPx3 deficiency may lead to cardiovascular disease in the presence of chronic kidney disease due to an accumulation of reactive oxygen species and decreased microvascular perfusion of the myocardium. Methods. To isolate the exclusive effect of GPx3 deficiency in kidney disease-induced cardiac disease, we studied the GPx3 knockout mouse strain (GPx3-/-) in the setting of surgery-induced CKD. Results. Ribonucleic acid (RNA) microarray screening of non-stimulated GPx3-/- heart tissue show increased expression of genes associated with cardiomyopathy including myh7, plac9, serpine1 and cd74 compared with wild-type (WT) controls. GPx3-/- mice underwent surgically induced renal mass reduction to generate a model of CKD. GPx3-/- + CKD mice underwent echocardiography 4 weeks after injury. Fractional shortening (FS) was decreased to 32.9 ± 5.8% in GPx3-/- + CKD compared to 62.0% ± 10.3 in WT + CKD (P < 0.001). Platelet aggregates were increased in the myocardium of GPx3-/- + CKD. Asymmetric dimethylarginine (ADMA) levels were increased in both GPx3-/- + CKD and WT+ CKD. ADMA stimulated spontaneous platelet aggregation more quickly in washed platelets from GPx3-/-. In vitro platelet aggregation was enhanced in samples from GPx3-/- + CKD. Platelet aggregation in GPx3-/- + CKD samples was mitigated after in vivo administration of ebselen, a glutathione peroxidase mimetic. FS improved in GPx3-/- + CKD mice after ebselen treatment. Conclusion: These results suggest GPx3 deficiency is a substantive contributing factor to the development of kidney disease-induced cardiac disease.

α-Klotho expression determines nitric oxide synthesis in response to FGF-23 in human aortic endothelial cells.

Endothelial cells (ECs) express fibroblast growth factor (FGF) receptors and are metabolically active after treatment with FGF-23. It is not known if this effect is α-Klotho independent or mediated by humoral or endogenous endothelial α-Klotho. In the present study, we aimed to characterize EC α-Klotho expression within the human vascular tree and to investigate the potential role of α-Klotho in determining FGF-23 mediated EC regulation. Human tissue and ECs from various organs were used for immunohistochemistry and Western blot. Primary cultures of human aortic endothelial cells (HAECs) and human brain microvascular endothelial cells (HBMECs) were used to generate in vitro cell models. We found endogenous α-Klotho expression in ECs from various organs except in microvascular ECs from human brain. Furthermore, FGF-23 stimulated endothelial nitric oxide synthase (eNOS) expression, nitric oxide (NO) production, and cell proliferation in HAECs. Interestingly, these effects were not observed in our HBMEC model in vitro. High phosphate treatment and endothelial α-Klotho knockdown mitigated FGF-23 mediated eNOS induction, NO production, and cell proliferation in HAECs. Rescue treatment with soluble α-Klotho did not reverse endothelial FGF-23 resistance caused by reduced or absent α-Klotho expression in HAECs. These novel observations provide evidence for differential α-Klotho functional expression in the human endothelium and its presence may play a role in determining the response to FGF-23 in the vascular tree. α-Klotho was not detected in cerebral microvascular ECs and its absence may render these cells nonresponsive to FGF-23.

Preventive effects of cranberry products on experimental colitis induced by dextran sulphate sodium in mice.

With the prevalence of inflammatory bowel disease (IBD) and its associated risk for development of colorectal cancer, it is of great importance to prevent and treat IBD. However, due to the complexity of etiology and potentially serious adverse effects, treatment options for IBD are relatively limited. Thus, the purpose of this study was to identify a safe food-based approach for the prevention and treatment of IBD. In this study, we tested the effects of cranberry products on preventing dextran sulphate sodium-induced murine colitis. Our results suggest that both cranberry extract and dried cranberries-fed groups had a significantly reduced disease activity index, where dried cranberries were more effective in preventing colitis than cranberry extract. Shortening of colon length, colonic myeloperoxidase activity and production of pro-inflammatory cytokines were attenuated in animals fed dried cranberries compared to the controls. The current report suggests that cranberries can be applied to prevent and reduce the symptoms of IBD.

Polycystin-1 and Gα12 regulate the cleavage of E-cadherin in kidney epithelial cells.

Interaction of polycystin-1 (PC1) and Gα12 is important for development of kidney cysts in autosomal dominant polycystic kidney disease (ADPKD). The integrity of cell polarity and cell-cell adhesions (mainly E-cadherin-mediated adherens junction) is altered in the renal epithelial cells of ADPKD. However, the key signaling pathway for this alteration is not fully understood. Madin-Darby canine kidney (MDCK) cells maintain the normal integrity of epithelial cell polarity and adherens junctions. Here, we found that deletion of Pkd1 increased activation of Gα12, which then promoted the cystogenesis of MDCK cells. The morphology of these cells was altered after the activation of Gα12. By using liquid chromatography-mass spectrometry, we found several proteins that could be related this change in the extracellular milieu. E-cadherin was one of the most abundant peptides after active Gα12 was induced. Gα12 activation or Pkd1 deletion increased the shedding of E-cadherin, which was mediated via increased ADAM10 activity. The increased shedding of E-cadherin was blocked by knockdown of ADAM10 or specific ADAM10 inhibitor GI254023X. Pkd1 deletion or Gα12 activation also changed the distribution of E-cadherin in kidney epithelial cells and caused ß-catenin to shift from cell membrane to nucleus. Finally, ADAM10 inhibitor, GI254023X, blocked the cystogenesis induced by PC1 knockdown or Gα12 activation in renal epithelial cells. Our results demonstrate that the E-cadherin/ß-catenin signaling pathway is regulated by PC1 and Gα12 via ADAM10. Specific inhibition of this pathway, especially ADAM10 activity, could be a novel therapeutic regimen for ADPKD.

The Kidney Disease Screening and Awareness Program (KDSAP): a novel translatable model for increasing interest in nephrology careers.

Despite the increasing prevalence of CKD in the United States, there is a declining interest among United States medical graduates in nephrology as a career choice. Effective programs are needed to generate interest at early educational stages when career choices can be influenced. The Kidney Disease Screening and Awareness Program (KDSAP) is a novel program initiated at Harvard College that increases student knowledge of and interest in kidney health and disease, interest in nephrology career paths, and participation in kidney disease research. This model, built on physician mentoring, kidney screening of underserved populations, direct interactions with kidney patients, and opportunities to participate in kidney research, can be reproduced and translated to other workforce-challenged subspecialties.

Induction of intracellular heat-shock protein 72 prevents the development of vascular smooth muscle cell calcification.

AIMS: Vascular calcification (VC) is a significant contributor to cardiovascular mortality in patients with chronic kidney disease (CKD) and coronary artery disease (CAD). Osteo/chondrocytic transformation and simultaneous dedifferentiation of smooth muscle cells (SMCs) are important in the pathogenesis of VC. Heat-shock protein 72 (HSP72) is a cardioprotective inducible heat-shock protein that functions as a molecular chaperone. However, its role in the development of accelerated vascular dysfunction and calcification is largely unexplored. METHODS AND RESULTS: We describe for the first time marked reduction in HSP72 expression in arteries from patients with CKD and CAD, compared with healthy controls, in vivo. Induction of HSP72 by heat-shock treatment (HST) significantly prevented the development of calcification of human aortic smooth muscle cells (HA-SMCs), in vitro. These anti-calcific effects were abolished following treatment with both quercetin, an HST inhibitor, and HSP72 siRNA knockdown. Induction of HSP72 suppressed Cbfa-1-dependent osteo/chondrocytic transformation and stabilized SMC contractile phenotype through the myocardin-serum response factor (SRF) pathway. Co-immunoprecipitation studies demonstrated physical association between SRF and HSP72. Furthermore, organ culture of arteries from CKD and CAD patients showed that these arteries retained their ability to induce HSP72 following HST, despite initially reduced expression. CONCLUSION: Our study shows for the first time that intracellular HSP72 may function as a central regulator of molecular pathways involved in the development of VC. We suggest treatment strategies that up-regulate HSP72 as a new approach to inhibit VC.

Vascular Klotho deficiency potentiates the development of human artery calcification and mediates resistance to fibroblast growth factor 23.

BACKGROUND: Klotho is known to function as a cofactor for the phosphatonin, fibroblast growth factor (FGF)-23 at the kidney. FGF-23 levels rise in chronic kidney disease (CKD) despite progression of accelerated vascular calcification. There are currently conflicting data on whether FGF-23 may exhibit direct vasculoprotective effects in CKD. METHODS AND RESULTS: In this study, we describe for the first time endogenous Klotho expression in human arteries and human aortic smooth muscle cells. We show that CKD is a state of vascular Klotho deficiency promoted by chronic circulating stress factors, including proinflammatory, uremic, and disordered metabolic conditions. Mechanistic studies demonstrated that Klotho knockdown potentiated the development of accelerated calcification through a Runx2 and myocardin-serum response factor-dependent pathway. Klotho knockdown studies further revealed that vascular cells are a Klotho-dependent target tissue for FGF-23. FGF-23 mediated cellular activation of p-ERK, p-AKT, and cellular proliferative effects, which were abrogated following Klotho knockdown. We next showed that vascular Klotho deficiency driven by procalcific stressors could be restored by vitamin D receptor activators, in vitro and further confirmed using human arterial organ cultures from CKD patients, in vivo. Furthermore, restoration of suppressed Klotho expression by vitamin D receptor activators conferred human aortic smooth muscle cells responsive to FGF-23 signaling and unmasked potential anticalcific effects. CONCLUSIONS: Chronic metabolic stress factors found in CKD promote vascular Klotho deficiency. Mechanistic studies revealed a bifunctional role for local vascular Klotho, first, as an endogenous inhibitor of vascular calcification and, second, as a cofactor required for vascular FGF-23 signaling. Furthermore, vitamin D receptor activators can restore Klotho expression and unmask FGF-23 anticalcific effects.

Interpretation of biological and mechanical variations between the Lowry versus Bradford method for protein quantification.

BACKGROUND: The identification of differences in protein expression resulting from methodical variations is an essential component to the interpretation of true, biologically significant results. AIMS: We used the Lowry and Bradford methods- two most commonly used methods for protein quantification, to assess whether differential protein expressions are a result of true biological or methodical variations. MATERIAL #ENTITYSTARTX00026; METHODS: Differential protein expression patterns was assessed by western blot following protein quantification by the Lowry and Bradford methods. RESULTS: We have observed significant variations in protein concentrations following assessment with the Lowry versus Bradford methods, using identical samples. Greater variations in protein concentration readings were observed over time and in samples with higher concentrations, with the Bradford method. Identical samples quantified using both methods yielded significantly different expression patterns on Western blot. CONCLUSIONS: We show for the first time that methodical variations observed in these protein assay techniques, can potentially translate into differential protein expression patterns, that can be falsely taken to be biologically significant. Our study therefore highlights the pivotal need to carefully consider methodical approaches to protein quantification in techniques that report quantitative differences.

Cannabinoids inhibit HIV-1 Gp120-mediated insults in brain microvascular endothelial cells.

HIV-1 infection has significant effect on the immune system as well as on the nervous system. Breakdown of the blood-brain barrier (BBB) is frequently observed in patients with HIV-associated dementia (HAD) despite lack of productive infection of human brain microvascular endothelial cells (HBMEC). Cellular products and viral proteins secreted by HIV-1 infected cells, such as the HIV-1 Gp120 envelope glycoprotein, play important roles in BBB impairment and HIV-associated dementia development. HBMEC are a major component of the BBB. Using cocultures of HBMEC and human astrocytes as a model system for human BBB as well as in vivo model, we show for the first time that cannabinoid agonists inhibited HIV-1 Gp120-induced calcium influx mediated by substance P and significantly decreased the permeability of HBMEC as well as prevented tight junction protein down-regulation of ZO-1, claudin-5, and JAM-1 in HBMEC. Furthermore, cannabinoid agonists inhibited the transmigration of human monocytes across the BBB and blocked the BBB permeability in vivo. These results demonstrate that cannabinoid agonists are able to restore the integrity of HBMEC and the BBB following insults by HIV-1 Gp120. These studies may lead to better strategies for treatment modalities targeted to the BBB following HIV-1 infection of the brain based on cannabinoid pharmacotherapies.

In vivo heat shock protein assembles with septic liver NF-kappaB/I-kappaB complex regulating NF-kappaB activity.

This study elucidates the mechanism through which heat shock treatment influences the outcome of sepsis. Post-heat shock sepsis was induced in rats by CLP 24 h after whole-body hyperthermia. Liver cytosolic and nuclear fractions were collected and analyzed in early and late sepsis rats (sacrificed 9 and 18 h after CLP, respectively). During sepsis, levels of I-kappaB and nuclear factor-kappaB (NF-kappaB) declined in the cytosol of liver, whereas NF-kappaB increased in nucleus. NF-kappaB activity was significantly enhanced during sepsis, and the products of NF-kappaB target genes, such as TNF-alpha and inducible nitric oxide synthase (iNOS), were overexpressed. Heat shock treatment, inducing heat shock protein synthesis, prevented down-regulation of cytosolic I-kappaB and decreased translocation of NF-kappaB into the nucleus. Therefore, the sepsis-induced acceleration of NF-kappaB activation was inhibited. Expression of TNF-alpha and iNOS mRNA was also down-regulated. Coimmunoprecipitation with anti-NF-kappaB (p65) and anti-IkappaB antibodies verified an assembling phenomenon of heat shock protein (HSP) 72 with NF-kappaB and I-kappaB. We suggest that the mechanism preventing septic activation of NF-kappaB is that oversynthesized HSP72 forms a complex with NF-kappaB/I-kappaB, thus inhibiting nuclear translocation of NF-kappaB. HSP72 appears to play a crucial protective role in modulating the gene expression controlled by NF-kappaB in sepsis.

Effects of hyperthermia pretreatment on expression of heme oxygenase-1 and nitric oxide synthase in rats subjected to experimental anaphylactic shock.

Previous studies have shown that hyperthermia pretreatment results in an attenuation of increased vascular leakage in rats subjected to experimental anaphylactic shock. It is known that both nitric oxide synthase (NOS) and heme oxygenase-1 (HO-1) play a role in the maintenance of microvascular integrity. In the study, we investigated the effect of hyperthermia pretreatment on mRNA expression of endothelial NOS (eNOS), inducible NOS (iNOS), and HO-1 in heated or nonheated rats subjected to anaphylactic shock using a semi-quantitative RT-PCR. Protein contents of eNOS and HO-1 in tissue were also assayed. Plasma nitrite and nitrate before and after induction of anaphylactic shock were quantified using a NO analyzer. The heated, anaphylactic rats showed a significant increase of HO-1 mRNA expression in heart as compared to both non-heated, anaphylactic and control rats. HO-1 protein contents in both heart and lung tissues in the heated, anaphylactic rats were significantly higher than both non-heated, anaphylactic and control rats. Protein contents of eNOS in various tissues appeared to be the same among groups. No significant change of iNOS mRNA expression was detected among groups. Plasma nitrite and nitrate before and after anaphylactic treatment appeared to be the same among groups. These data suggest that reduction of anaphylactic hypotension by hyperthermia pretreatment in rats subjected to anaphylactic shock may be resulted from over-expression of HO-1 rather than NOS in various tissues.

Cytochrome c oxidase as the target of the heat shock protective effect in septic liver.

Liver function failure is one of the characteristics of critically ill, septic patients and is associated with worse outcome. Our previous studies have demonstrated that heat-shock response protects cells and tissue from subsequent insults and improves survival during sepsis. In this study, we have shown that mitochondrial cytochrome c oxidase (CCO) is one of the major sources of that protective effect. Experimental sepsis was induced by the cecal ligation and puncture (CLP) method. Heat-shock treatment was induced in rats by hyperthermia 24 h before CLP operation. The results showed that ATP content of the liver declined significantly, and the enzymatic activity of mitochondrial CCO was apparently suppressed during the late stages of sepsis. The mitochondrial ultrastructure of septic liver showed the deformity, mild swelling and inner membrane budding. Heat-shock treatment led to heat-shock protein 72 overexpression and prevented the downregulation of Grp75 during sepsis. On the contrary, the expression of the enzyme complex and its activity were preserved, associated with the minimization of ultrastructural deformities. In conclusion, the maintenance of mitochondrial function, especially the CCO, may be an important strategy in therapeutic interventions of a septic liver.