Nicotinic Acetylcholine Receptor Agonists Attenuate Septic Acute Kidney Injury in Mice by Suppressing Inflammation and Proteasome Activity

Sepsis is one of the leading causes of acute kidney injury (AKI). Septic patients who develop acute kidney injury (AKI) are at increased risk of death. To date there is no effective treatment for AKI or septic AKI. Based on their anti-inflammatory properties, we examined the effects of nicotinic acetylcholine receptor agonists on renal damage using a mouse model of lipopolysaccharide (LPS)-induced AKI where localized LPS promotes inflammation-mediated kidney damage. Administration of nicotine (1 mg/kg) or GTS-21 (4 mg/kg) significantly abrogated renal leukocyte infiltration (by 40%) and attenuated kidney injury. These renoprotective effects were accompanied by reduced systemic and localized kidney inflammation during LPS-induced AKI. Consistent with these observations, nicotinic agonist treatment significantly decreased renal IκBα degradation and NFκB activation during LPS-induced AKI. Treatment of human kidney cells with nicotinic agonists, an NFκB inhibitor (Bay11), or a proteasome inhibitor (MG132) effectively inhibited their inflammatory responses following stimulation with LPS or TNFα. Renal proteasome activity, a major regulator of NFκB-mediated inflammation, was enhanced by approximately 50% during LPS-induced AKI and elevated proteasome activity was significantly blunted by nicotinic agonist administration in vivo. Taken together, our results identify enhanced renal proteasome activity during LPS-induced AKI and the suppression of both proteasome activity and inflammation by nicotinic agonists to attenuate LPS-induced kidney injury

Contrast-enhanced whole-heart coronary MRA at 3.0T for the evaluation of cardiac venous anatomy

This study was designed to evaluate the value of contrast-enhanced whole-heart coronary MRA (CMRA) at 3.0T in depicting the cardiac venous anatomy. In cardiac resynchronization therapy (CRT), left ventricular (LV) pacing is achieved by positioning the LV lead in one of the tributaries of the coronary sinus (CS). Pre-implantation knowledge of the venous anatomy may help determine whether transvenous LV lead placement for CRT is feasible. Images of 51 subjects undergoing contrast-enhanced whole-heart CMRA at 3.0T were retrospectively analyzed. Data acquisition was performed using electrocardiography-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence. A 32-element cardiac coil was used for data acquisition. The visibility of the cardiac veins was graded visually using a 4-point scale (1: poor–4: excellent). The paired Student t test was used to evaluate differences in diameters of the ostium of the CS in anteroposterior and superoinferior direction. The cardiac veins were finally evaluated in 48 subjects with three anatomic variations. The diameter of the CS ostium in the superoinferior direction (1.13 ± 0.26 cm) was larger than in the anteroposterior direction (0.82 ± 0.19 cm) (P < 0.05). The mean visibility score of CS, posterior interventricular vein, posterior vein of the left ventricle, left marginal vein, and anterior interventricular vein was 4.0 ± 0.0, 3.4 ± 0.5, 3.4 ± 0.5, 3.0 ± 0.8, and 3.3 ± 0.5, respectively. In conclusion, contrast-enhanced whole-heart CMRA at 3.0T can depict the normal and variant cardiac venous anatomy

PGC-1α Inhibits Oleic Acid Induced Proliferation and Migration of Rat Vascular Smooth Muscle Cells

BACKGROUND: Oleic acid (OA) stimulates vascular smooth muscle cell (VSMC) proliferation and migration. The precise mechanism is still unclear. We sought to investigate the effects of peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator-1 alpha (PGC-1alpha) on OA-induced VSMC proliferation and migration. PRINCIPAL FINDINGS: Oleate and palmitate, the most abundant monounsaturated fatty acid and saturated fatty acid in plasma, respectively, differently affect the mRNA and protein levels of PGC-1alpha in VSMCs. OA treatment resulted in a reduction of PGC-1alpha expression, which may be responsible for the increase in VSMC proliferation and migration caused by this fatty acid. In fact, overexpression of PGC-1alpha prevented OA-induced VSMC proliferation and migration while suppression of PGC-1alpha by siRNA enhanced the effects of OA. In contrast, palmitic acid (PA) treatment led to opposite effects. This saturated fatty acid induced PGC-1alpha expression and prevented OA-induced VSMC proliferation and migration. Mechanistic study demonstrated that the effects of PGC-1alpha on VSMC proliferation and migration result from its capacity to prevent ERK phosphorylation. CONCLUSIONS: OA and PA regulate PGC-1alpha expression in VSMCs differentially. OA stimulates VSMC proliferation and migration via suppression of PGC-1alpha expression while PA reverses the effects of OA by inducing PGC-1alpha expression. Upregulation of PGC-1alpha in VSMCs provides a potential novel strategy in preventing atherosclerosis

Lead-Time Trajectory of CA19-9 as an Anchor Marker for Pancreatic Cancer Early Detection

Background & Aims There is substantial interest in liquid biopsy approaches for cancer early detection among subjects at risk, using multi-marker panels. CA19-9 is an established circulating biomarker for pancreatic cancer; however, its relevance for pancreatic cancer early detection or for monitoring subjects at risk has not been established. Methods CA19-9 levels were assessed in blinded sera from 175 subjects collected up to 5 years before diagnosis of pancreatic cancer and from 875 matched controls from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. For comparison of performance, CA19-9 was assayed in blinded independent sets of samples collected at diagnosis from 129 subjects with resectable pancreatic cancer and 275 controls (100 healthy subjects; 50 with chronic pancreatitis; and 125 with noncancerous pancreatic cysts). The complementary value of 2 additional protein markers, TIMP1 and LRG1, was determined. Results In the PLCO cohort, levels of CA19-9 increased exponentially starting at 2 years before diagnosis with sensitivities reaching 60% at 99% specificity within 0 to 6 months before diagnosis for all cases and 50% at 99% specificity for cases diagnosed with early-stage disease. Performance was comparable for distinguishing newly diagnosed cases with resectable pancreatic cancer from healthy controls (64% sensitivity at 99% specificity). Comparison of resectable pancreatic cancer cases to subjects with chronic pancreatitis yielded 46% sensitivity at 99% specificity and for subjects with noncancerous cysts, 30% sensitivity at 99% specificity. For prediagnostic cases below cutoff value for CA19-9, the combination with LRG1 and TIMP1 yielded an increment of 13.2% in sensitivity at 99% specificity ( P = .031) in identifying cases diagnosed within 1 year of blood collection. Conclusion CA19-9 can serve as an anchor marker for pancreatic cancer early detection applications

Nicotinic acetylcholine receptor expression and regulation in the rat kidney after ischemia-reperfusion injury

The cholinergic anti-inflammatory pathway is a mechanism whereby local inflammation is modulated by the brain via the vagus nerve and nicotinic acetylcholine receptors (nAChRs). The nAChR family are ligand-gated ion channels that consist of many different subtypes formed by the specific assembly of five polypeptide subunits including α1–10, β1–4, γ, δ, and ɛ. The α7 receptor (α7nAChR) mediates the anti-inflammatory effects of cholinergic stimulation. We recently demonstrated that cholinergic agonists attenuate renal ischemia-reperfusion (I/R) injury in rats. We also showed that tubular epithelial cells express functional nAChRs in vitro. The current studies report the expression, localization, and regulation of the α7nAChR in the rat kidney after I/R injury. We also examined, in this model, potential interactions between cholinergic stimulation and the STAT3 pathway, a key signaling cascade that has been linked to α7nAChR activation. RT-PCR and immunohistochemistry showed constitutive expression of many nAChR subunits. Immunohistochemistry localized basal α7nAChR expression to the endothelium of cortical peritubular capillaries, and its distribution was upregulated after I/R injury. Western blotting also showed an increase in α7nAChR subunit protein after renal I/R injury. Interestingly, pretreatment with nicotine, which improves the outcome after renal I/R injury, reduced the α7nAChR protein after I/R injury. Finally, we found that I/R injury stimulated the STAT3 pathway, whereas pretreatment with nicotine downregulated its activation. These results suggest that the α7nAChR plays an important role in the pathophysiology of renal I/R injury

Acknowledgments

My sincere thanks to my supervisor Professor Gustavo de Veciana for his tremendous efforts on my behalf over the five years that we have worked together. What I have learnt in these five years is not only how to do pure research, but also being a confident speaker, a rigorous researcher, a responsible instructor, a good collaborator and much more. I would also thank Professors Andrews, Baldick, Shakkottai and Vin for participating my Ph.D. committee and providing me many valuable suggestions and directions on my research. I must particularly thank Professor Andrews and, my former colleague, Professor Weber for their collaboration and contributions to my work. I would not have been able to work on so many interesting problems without them. I also would like to thank my friends Jay, Xun, Jangwon, Seungjun, Alex, Shailesh and Balaji for making a friendly, open minded and creative research group to work in. I also want to thank my former supervising Professors Yujin Zhang, Qingmin Liao and Xinggang Lin, from whom I learnt elements of serious and rigorous research. My special thanks go to Mr. and Mrs. Chujo, Mr. Takeo, Chingfong, Hungying and Richard at Fujitsu Labs of America for their tutoring and collaboration when I was inter

Chromatin-enriched RNAs mark active and repressive cis-regulation: An analysis of nuclear RNA-seq.

Long noncoding RNAs (lncRNAs) localize in the cell nucleus and influence gene expression through a variety of molecular mechanisms. Chromatin-enriched RNAs (cheRNAs) are a unique class of lncRNAs that are tightly bound to chromatin and putatively function to locally cis-activate gene transcription. CheRNAs can be identified by biochemical fractionation of nuclear RNA followed by RNA sequencing, but until now, a rigorous analytic pipeline for nuclear RNA-seq has been lacking. In this study, we survey four computational strategies for nuclear RNA-seq data analysis and develop a new pipeline, Tuxedo-ch, which outperforms other approaches. Tuxedo-ch assembles a more complete transcriptome and identifies cheRNA with higher accuracy than other approaches. We used Tuxedo-ch to analyze benchmark datasets of K562 cells and further characterize the genomic features of intergenic cheRNA (icheRNA) and their similarity to enhancer RNAs (eRNAs). We quantify the transcriptional correlation of icheRNA and adjacent genes and show that icheRNA is more positively associated with neighboring gene expression than eRNA or cap analysis of gene expression (CAGE) signals. We also explore two novel genomic associations of cheRNA, which indicate that cheRNAs may function to promote or repress gene expression in a context-dependent manner. IcheRNA loci with significant levels of H3K9me3 modifications are associated with active enhancers, consistent with the hypothesis that enhancers are derived from ancient mobile elements. In contrast, antisense cheRNA (as-cheRNA) may play a role in local gene repression, possibly through local RNA:DNA:DNA triple-helix formation

Chromatin-enriched RNAs mark active and repressive cis-regulation: An analysis of nuclear RNA-seq

Long noncoding RNAs (lncRNAs) localize in the cell nucleus and influence gene expression through a variety of molecular mechanisms. Chromatin-enriched RNAs (cheRNAs) are a unique class of lncRNAs that are tightly bound to chromatin and putatively function to locally cis-activate gene transcription. CheRNAs can be identified by biochemical fractionation of nuclear RNA followed by RNA sequencing, but until now, a rigorous analytic pipeline for nuclear RNA-seq has been lacking. In this study, we survey four computational strategies for nuclear RNA-seq data analysis and develop a new pipeline, Tuxedo-ch, which outperforms other approaches. Tuxedo-ch assembles a more complete transcriptome and identifies cheRNA with higher accuracy than other approaches. We used Tuxedo-ch to analyze benchmark datasets of K562 cells and further characterize the genomic features of intergenic cheRNA (icheRNA) and their similarity to enhancer RNAs (eRNAs). We quantify the transcriptional correlation of icheRNA and adjacent genes and show that icheRNA is more positively associated with neighboring gene expression than eRNA or cap analysis of gene expression (CAGE) signals. We also explore two novel genomic associations of cheRNA, which indicate that cheRNAs may function to promote or repress gene expression in a context-dependent manner. IcheRNA loci with significant levels of H3K9me3 modifications are associated with active enhancers, consistent with the hypothesis that enhancers are derived from ancient mobile elements. In contrast, antisense cheRNA (as-cheRNA) may play a role in local gene repression, possibly through local RNA:DNA:DNA triple-helix formation