Drew A. Rideout

Deletion of toll-like receptor-4 downregulates protein kinase C-ζ and attenuates liver injury in experimental pancreatitis

BACKGROUND Toll-like receptor-4 (TLR4) and protein kinase C-zeta (PKC-zeta) play a role in macrophage activation. We hypothesized that deletion of TLR4 downregulates PKC-zeta and attenuates liver cell apoptosis in experimental pancreatitis. METHODS Acute pancreatitis was induced by choline-deficient ethionine diet in C57/BL6 (TLR4+/+ and TLR4-/-) mice. RESULTS During pancreatitis, staining for TLR4 and PKC-zeta, which colocalized in Kupffer cells but not in hepatocytes, increased in TLR4+/+ mice and decreased in TLR4-/- mice. In TLR4+/+ mice, pancreatitis increased TLR4 protein and mRNA and PKC-zeta protein and activity, nuclear factor (NF)-kappaB, ERK1/2, caspase-3 cleavage, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining; all P < .01 versus controls. In TLR4-/- mice with pancreatitis, PKC-zeta mRNA and activity were reduced, ERK1/2 and caspase-3 did not increase, and NF-kappaB and TUNEL (mostly in hepatocytes) increased mildly (all P < .01 vs control). PKC-zeta did not interact directly with NF-kappaB; however, during pancreatitis, coimmunoprecipitation of PKC-zeta with ERK1/2 was increased in TLR4+/+ mice and was attenuated in TLR4-/- mice (all P < .01 vs control), indicating that PKC-zeta interacts with ERK1/2. CONCLUSION Acute pancreatitis upregulates TLR4, PKC-zeta, NF-kappaB, and ERK1/2, and increases apoptosis in mice livers. PKC-zeta induces nuclear translocation of NF-kappaB via ERK1/2-dependent mechanisms. Deletion of TLR4 downregulates PKC-zeta, NF-kappaB, and ERK1/2, and attenuates pancreatitis-induced liver cell apoptosis.

Roux-en-Y gastric bypass alters tumor necrosis factor-α but not adiponectin signaling in immediate postoperative period in obese rats

BACKGROUND Adiponectin has anti-inflammatory properties and is increased with weight loss. Tumor necrosis factor (TNF)-α is a pro-inflammatory cytokine that negatively regulates adiponectin. Previously, we have demonstrated that Roux-en-Y gastric bypass (RYGB) induces weight loss and improves steatosis in obese rats. We hypothesized that RYGB would alter the interplay of TNF-α and adiponectin signaling in the postoperative period. METHODS Obese Sprague-Dawley male rats that had undergone RYGB (n = 5) or sham (n = 4) were euthanatized at 9 weeks postoperatively. The adiponectin levels from serial serum samples were measured by enzyme-linked immunosorbent assay. Adiponectin, adiponectin receptor 2, and TNF-α mRNA from adipose and liver samples were quantified by reverse transcriptase-polymerase chain reaction. Data are presented as mean ± standard deviation; using a t test, P <.05 was significant. RESULTS RYGB did not change the serum adiponectin, adipose tissue adiponectin mRNA, or hepatic adiponectin receptor 2 levels compared with the levels in the sham-operated rats (P >.05). However, the TNF-α mRNA levels had decreased in the adipose tissue (P >.05) but remained unchanged in the liver compared with the sham controls (P >.05). CONCLUSION Surgically-induced weight loss in a rat model of RYGB did not increase adiponectin signaling in the immediate postoperative period but was associated with decreased pro-inflammatory signaling in the adipose tissue. During this period, pro-inflammatory signaling might play a more important role than adiponectin. Additional studies with longer follow-up are necessary to determine whether adiponectin plays a role in weight loss and improvement of steatosis after RYGB.

Roux-en-Y gastric bypass attenuates the progression of cardiometabolic complications in obese diabetic rats via alteration in gastrointestinal hormones

BACKGROUND Roux-en-Y gastric bypass (RYGB) ameliorates type 2 diabetes (T2DM) and obesity through alteration in gastrointestinal (GI) hormones. OBJECTIVE The objective of this study was to investigate the effect of RYGB on GI hormones and cardiometabolic parameters in Zucker diabetic fatty (ZDF) rodents. SETTING Winthrop University Hospital, Research and Academic Center METHODS Animals were divided into 3 groups, pair-fed (n = 4), ad lib (n = 4), and RYGB (n = 5). This study was carried out for 4 weeks and all related parameters were measured pre- and postsurgery in fasted obese diabetic Zucker rodents. RESULTS Postoperatively, RYGB significantly decreased fasting blood glucose by 32% compared with ad lib. Plasma insulin and leptin levels were also found to be significantly decreased, by 66% and 38%, respectively, after surgery. Moreover, both glucose-dependent insulinotropic polypeptide (GIP) and peptide tyrosine-tyrosine (PYY) were significantly increased after RYGB-by 300% and 51%, respectively. Glucagon-like peptide-1 (GLP-1) levels were also increased, but the increase was not statistically significant. Total cholesterol levels of the RYGB group remained unchanged for 4 weeks. However, total cholesterol in the ad lib and pair-fed groups increased by 25% and 34%, respectively, compared with initial levels. The cholesterol/high-density lipoprotein (HDL) ratio was decreased in the RYGB group by 14% and 30% compared with the ad lib and pair-fed group, respectively. The RYGB group had a significant decrease in aortic wall thickness of 25% compared with the ad lib and pair-fed groups. Similarly, the RYGB group had a 20-unit (mm Hg) decrease in systolic blood pressure compared with the presurgical value. CONCLUSION RYGB has beneficial cardiometabolic effects through alterations in GI hormones in a severely obese and diabetic rodent model.

Lipocalin-type prostaglandin D2 synthase (L-PGDS) modulates beneficial metabolic effects of vertical sleeve gastrectomy

BACKGROUND Vertical sleeve gastrectomy (VSG) ameliorates metabolic complications in obese and diabetic patients through unknown mechanisms. OBJECTIVE The objective of this study was to investigate the role of lipocalin-type prostaglandin D2 synthase (L-PGDS) in glucose regulation in response to VSG using L-PGDS knock-out (KO), knock-in (KI), and C57BL/6 (wild type) mice. SETTING Winthrop University Hospital Research Institute. METHODS Animals were divided into 6 groups: L-PGDS KO sham/VSG (n = 5), L-PGDS KI sham/VSG (n = 5), and C57BL/6 (wild type) sham/VSG (n = 5). Related parameters were measured in fasting animals after 10 weeks. RESULTS Our intraperitoneal glucose tolerance tests and homeostatic model assessment insulin resistance results showed significant glycemic improvement 10 weeks post-VSG in both C57BL/6 and KI groups compared with the sham group. In contrast, the KO group developed glucose intolerance and insulin resistance similar to or greater than the sham group 10 weeks post-VSG. Interestingly, weight gain was insignificant 10 weeks post-VSG in all the groups and even trended higher in the KO group compared with sham. Peptide YY levels in the KO group post-VSG were slightly increased but significantly less than other groups. Similarly, the KO group showed significantly less leptin sensitivity in response to VSG compared with the KI group. Total cholesterol level remained unchanged in all groups irrespective of sham or surgery but interestingly, the KO group had significantly higher cholesterol levels. In parallel, adipocyte size was also found to be significantly increased in the KO group post-VSG compared with the sham group. CONCLUSION Our findings propose that L-PGDS plays an important role in the beneficial metabolic effects observed after VSG.

Mo1890 Elevation of Bile Acids After Bariatric Surgery May Attenuate Early Atherosclerosis

Introduction: Colorectal cancers (CRC) express Angiogenin (ANG), Galectin-3 (Gal-3) and Activin A (Act-A). The binding of ANG to actin on endothelial cell promote EC migration and angiogenesis. Cellular Gal-3 levels associated with cancer cell invasion, angiogenesis and tumor progression. Act-A act via binding to trans membrane receptors and support cancer cell migration. Blood levels of ANG, Gal-3 and Act-A in colorectal cancer (CRC) have not been well studied. This studys purpose was to measure preoperative (PreOp) plasma ANG, Gal-3 and Act-A levels in CRC and benign pathology (BP) patients (pts.) and to assess the diagnostic efficacy of these proteins alone and together. Method: CRC or BP pts having bowel resection for whom PreOp plasma was available (from IRB approved tissue bank) were studied. Plasma ANG (ng/ml), Gal-3 and Act-A (pg/ml) levels were analyzed in duplicate via ELISA (results: median + 95%CI). Intergroup levels were compared by the Mann-Whitney test (significant;p <0.05). The plasma receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) were used to evaluate single and combined proteins levels. Results: Plasma from 43 BP (polyp 28%, diverticulitis 56%, other 16%) and 120 CRC (83% colon, 17% rectal) pts. were studied. The CRC stage distribution was: Stage1, 25%; Stage-2, 37%, Stage-3, 26%, Stage4, 12%. Median PreOp proteins levels in CRC pts. were significantly higher than BP levels.[ ANG; 390.9,CI: 373.2,405.5 vs 316.8,CI: 297.5,350.9; Gal-3; 12.0,CI: 10.6,13.8 vs 8.9,CI: 7.2,11.1; Act-A; 369.7 CI:349.2,424.0 vs 277.9 CI: 209.3,346.7;P<0.001). Plasma Act-A levels were significantly higher in the Stage 4 pts. than in the stage 1 group ( p=0.001). The single AUC values from the ROC curve for ANG, Gal-3 and Act-A were 0.719, 0.709 and 0.741 with associated 81%, 47% and 42%. The 3 protein combination improved the AUC (0.856) and specificity (90.7%). Conclusion: CRC median ANG, Gal-3 and Act-A levels were significantly higher (23%, 35% & 33% respectively) than BP levels. Although not proven, we believe the plasma elevations are due to the tumor. Higher levels of ANG, Gal-3 and Act-A in plasma of CRC pts. may be related to the tumor cells, stromal cells, and inflammatory cells surrounding the cancer; these elevated levels may related to neovascularization and inflammation-induced tissue remodeling at tumor sites. The 3 protein combination had improved AUC & specificity vs single protein results and may have value as a diagnostic panel. A larger study is needed.