Aim High-fat diets are known to contribute to the development of obesity and related co-morbidities including non-alcoholic fatty liver disease (NAFLD). The accumulation of hepatic lipid may increase endoplasmic reticulum (ER) stress and contribute to non-alcoholic steatohepatitis and metabolic disease. We hypothesized that bariatric surgery would counter the effects of a high-fat diet (HFD) on obesity-associated NAFLD. Methods Sixteen of 24 male Sprague Dawley rats were randomized to Sham (N = 8) or Roux-en-Y gastric bypass (RYGB) surgery (N = 8) and compared to Lean controls (N = 8). Obese rats were maintained on a HFD throughout the study. Insulin resistance (HOMA-IR), and hepatic steatosis, triglyceride accumulation, ER stress and apoptosis were assessed at 90 days post-surgery. Results Despite eating a HFD for 90 days post-surgery, the RYGB group lost weight (−20.7 ± 6%, P < 0.01) and improved insulin sensitivity (P < 0.05) compared to Sham. These results occurred with no change in food intake between groups. Hepatic steatosis and ER stress, specifically glucose-regulated protein-78 (Grp78, P < 0.001), X-box binding protein-1 (XBP-1) and spliced XBP-1 (P < 0.01), and fibroblast growth factor 21 (FGF21) gene expression, were normalized in the RYGB group compared to both Sham and Lean controls. Significant TUNEL staining in liver sections from the Obese Sham group, indicative of accelerated cell death, was absent in the RYGB and Lean control groups. Additionally, fasting plasma glucagon like peptide-1 was increased in RYGB compared to Sham (P < 0.02). Conclusion These data suggest that in obese rats, RYGB surgery protects the liver against HFD-induced fatty liver disease by attenuating ER stress and excess apoptosis.

The rat laryngeal transplant model, introduced in 1992, laid the basic science foundation that contributed to the first successful human larynx transplant in 1998. Over 1,500 rat transplants later, numerous modifications have improved the model, increasing the initially reported evaluability rate of 50% to almost 100%. The observed histologic rejection process has been altered, as well. We report the technique modifications, as well as the results of a new study using nonimmunosuppressed, allogenic transplantations, in order to define a new rejection grading system. Using the updated model, we performed 50 transplantations between LBN(f1) donor rats and Lewis recipients. Larynges from 8 groups of 5 to 10 animals were harvested at intervals between 1 and 20 days after transplantation. The larynges were examined grossly and microscopically in a blinded manner for evidence of rejection. A multivariable linear regression model was used to define a new rejection grading scale. All 50 animals survived their assigned posttransplantation period. No animals exhibited vascular thromboses, for an evaluability rate of 100%. Histologic criteria in 7 categories and gross criteria in 5 categories demonstrated increased rejection proportional to the amount of time after transplantation. The equation [Group = -2.209 + 0.465 x (Size) + 0.901 x (VA Flow) + 0.613 x (Muscle) + 1.040 x (Thyroid)] reproducibly grades rejection on the basis of gross and histologic findings. New modifications to the rat laryngeal transplant model have conferred greatly improved animal survival rates and anastomotic patency rates. Additionally, the observed rates of rejection have been reduced in comparison to those of initial studies. This updated rejection staging system will be used to compare immunosuppressive regimens in future rat laryngeal transplant studies.

ObjectiveObesity is associated with low-grade chronic inflammation. We hypothesized that Roux-en-Y gastric bypass (RYGB) surgery would reduce activation of the NLRP3 inflammasome in metabolically active adipose tissue (AT) of obese rats, and this change would be related to decreases in body weight and improved glycemic control.MethodsOmental, mesenteric and subcutaneous fat depots were collected from Sprague-Dawley rats: Sham control and RYGB; 90-days after surgery. NLRP3, caspase–1, apoptosis-associated speck-like protein (ASC), IL–1β, IL–18, IL–6 and MCP–1 gene and protein expression were quantified. Glucose metabolism was assessed by oral glucose tolerance test (OGTT).ResultsCompared to Sham surgery controls, RYGB surgery decreased IL–6, MCP–1, NLRP3, IL–18, caspase–1 and ASC in omental fat, and decreased IL–6, MCP1, IL–1β, IL–18, caspase–1 and ASC gene expression in mesenteric fat. We observed differential gene expression between visceral and subcutaneous fat for IL–6 and IL–1β, both being downregulated by RYGB in visceral, and upregulated in subcutaneous depots. These changes in gene expression were accompanied by a decrease in NLRP3, ASC, IL–18, caspase–1 and IL–1β protein expression in omental tissue. We found a positive correlation between caspase–1, ASC, MCP–1, IL–18 and IL–6 gene expression following surgery and glucose AUC response in omental fat, while the change in glucose AUC response correlated with caspase–1 gene expression in subcutaneous fat.ConclusionThis study demonstrates that bariatric surgery reverses inflammation in visceral adipose tissue by suppressing NLRP3 inflammasome activation. These are the first data to implicate the NLRP3 inflammasome in diabetes remission after RYGB surgery.

In the rat laryngeal transplantation model, short-term perioperative therapy with everolimus and anti-TCR followed by pulsing is a viable alternative to the concerns associated with continuous, lifelong immunosuppression.

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Objectives/Hypothesis: Development of a rat laryngeal transplantation model allowed for the first total human laryngeal transplantation by the senior author in 1998. In an effort to further our knowledge of the immune system's role in laryngeal rejection, a change to the mouse model was required. Prior to initiating immunosuppressive research protocols, a reliable mouse larynx rejection classification had to be established.Study Design: Animal study. Methods: Thirty-one mouse laryngeal transplants (C57 BL/6 donors to C3H recipients) were performed and allowed to reject. Six time points were evaluated histologically: 1, 3, 5, 7, 9, and 15 days post-transplant. Eight anatomic sites were evaluated and assigned a point value. A linear regression model was constructed using the group number as the response and the scores from the eight histological criteria as predictors. Severity classifications were determined by observing patterns in the sum of scores of variables found to be significant contributors. Group 1 was normal; group 2, minimal rejection; groups 3, 4, and 5, moderate rejection; and group 6, severe rejection.Results: All mice survived the transplants. Of the observed histological changes, cartilage, fat, muscle, and magnitude of lymphocytic infiltration significantly correlated with rejection severity. The rejection model created demonstrated 100% accuracy in predicting the severity classification for the 31 specimens in the study. Conclusions:The model established provides an accurate and reliable way to classify rejection severity in mice receiving laryngeal allografts. This sets the stage for future advanced study of manipulating the immune system as a mechanism for establishing allograft tolerance.

Purpose Diabetes and obesity are associated with inflammasome-mediated low-grade, chronic inflammation that may induce pancreatic beta-cell dysfunction and apoptosis. We examined the effects of Roux-en-Y gastric bypass (RYGB) surgery on NOD-like receptor family, pyrin domain containing-3 (NLRP3) inflammasome-related genes from pancreatic islets of Zucker diabetic fatty rats. Materials and Methods Islets were collected from Zucker diabetic fatty sham control and RYGB, 30 days after surgery. We assessed expression of genes that regulate glucose metabolism and the NLRP3 inflammasome (NLRP3, caspase-1, IL-1β, IL-18, apoptosis-associated speck-like protein), IL-6, and monocyte chemoattractant protein-1. Results Gene expression for NLRP3 (p < 0.02), IL-1β (p < 0.04), and IL-6 (p < 0.01) was reduced by RYGB and positively correlated with change in body weight. IL-1β positively correlated with glucose AUC response. Conclusion Suppression of the NLRP3 inflammasome in pancreatic islets may contribute to improved glycemic control after RYGB.

In this rat laryngeal-transplantation model, functional tolerance was induced under combined tacrolimus and alphabeta TCR protocol. Mechanisms responsible for this tolerance induction require future elucidation.