Epithelial NAD+ depletion drives mitochondrial dysfunction and contributes to intestinal inflammation

IntroductionWe have previously demonstrated that a pathologic downregulation of peroxisome proliferator-activated receptor–gamma coactivator 1-alpha (PGC1α) within the intestinal epithelium contributes to the pathogenesis of inflammatory bowel disease (IBD). However, the mechanism underlying downregulation of PGC1α expression and activity during IBD is not yet clear.MethodsMice (male; C57Bl/6, Villincre/+;Pgc1afl/fl mice, and Pgc1afl/fl) were subjected to experimental colitis and treated with nicotinamide riboside. Western blot, high-resolution respirometry, nicotinamide adenine dinucleotide (NAD+) quantification, and immunoprecipitation were used to in this study.ResultsWe demonstrate a significant depletion in the NAD+ levels within the intestinal epithelium of mice undergoing experimental colitis, as well as humans with ulcerative colitis. While we found no decrease in the levels of NAD+-synthesizing enzymes within the intestinal epithelium of mice undergoing experimental colitis, we did find an increase in the mRNA level, as well as the enzymatic activity, of the NAD+-consuming enzyme poly(ADP-ribose) polymerase-1 (PARP1). Treatment of mice undergoing experimental colitis with an NAD+ precursor reduced the severity of colitis, restored mitochondrial function, and increased active PGC1α levels; however, NAD+ repletion did not benefit transgenic mice that lack PGC1α within the intestinal epithelium, suggesting that the therapeutic effects require an intact PGC1α axis.DiscussionOur results emphasize the importance of PGC1α expression to both mitochondrial health and homeostasis within the intestinal epithelium and suggest a novel therapeutic approach for disease management. These findings also provide a mechanistic basis for clinical trials of nicotinamide riboside in IBD patients

The Surgical Infection Society revised guidelines on the management of intra-abdominal infection

Background: Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations. Methods: Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council. Results: This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included. Summary: The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline

Inguinal hernia: What we have learned from laparoscopic evaluation of the contralateral side

PURPOSE OF REVIEW: The evaluation for and management of a contralateral patent processus vaginalis in children presenting with a unilateral inguinal hernia has been debated for over 60 years. The emergence of transinguinal laparoscopy as an evaluative tool has changed the landscape of the debate, offering a safe and minimally invasive option. The review will highlight some of the significant recent contributions to this debate. RECENT FINDINGS: Recent studies have confirmed the safety of transinguinal laparoscopy, and demonstrated a high level of sensitivity and specificity for it in the evaluation of the contralateral inguinal ring. In comparison, the practice of physical examination under anesthesia for evaluation of the contralateral inguinal region has proven to be ineffective. Further, age and gender differences in the incidence of contralateral patent processus vaginalis have recently been challenged. These data call into question the practices of routine or selective open inguinal exploration and present laparoscopy as the most effective means of evaluation. SUMMARY: Transinguinal laparoscopy offers a safe and effective means of evaluating the contralateral inguinal ring during ipsilateral hernia repair. The relatively high incidences of both contralateral patent processus vaginalis and contralateral metachronous hernia development in children justify the use of routine laparoscopic evaluation. © 2007 Lippincott Williams & Wilkins, Inc

Thoracic neuroblastoma: A retrospective review of our institutional experience with comparison of the thoracoscopic and open approaches to resection

Purpose: Neuroblastoma is the most common extracranial solid tumor in children. Twenty percent of all neuroblastomas arise in the thorax. This study evaluates the open vs thoracoscopic resection of thoracic neuroblastoma. Methods: A retrospective chart review was conducted from the medical records of all children undergoing resection of a thoracic neuroblastoma from 1990 to 2007 at our institution. We evaluated patients who underwent open vs thoracoscopic resection and compared demographics, pathologic condition, stage, operative details, complications, and outcomes between the 2 groups. Results: A total of 149 cases of neuroblastoma were identified during the study period, 36 (24%) of which had tumor located in the thorax. Thirty-six of these patients underwent 37 operations for primary thoracic neuroblastoma. Open thoracotomy was used in 26 cases with the thoracoscopic approach to resection used in the remaining 11. We observed no differences in patient demographics including mean age, sex, or ethnicity. Tumors in both groups were of similar histologic condition, location, surgical margin, lymph node status, and stage. The length of operation was similar between the 2 groups, but length of stay was shorter in the thoracoscopic group (2.0 days; range, 1-7 days vs 3.5 days; range, 2-8 for the open group; P = .01). Estimated blood loss was also less in the minimally invasive group (median, 10 mL; range, 0-75 mL vs 25 mL; 5-650 mL in the open group; P = .02). Review of outcomes showed no significant difference in complications, recurrence, survival, or disease-free survival between these 2 groups. Conclusions: This retrospective review of thoracic neuroblastoma for an 18-year period shows that thoracoscopic resection is an effective approach to this tumor and offers shorter length of stay and decreased blood loss when compared to open thoracotomy. © 2010 Elsevier Inc. All rights reserved

Intestinal epithelial CGAS dampens inflammation by upregulating autophagy

The pathogenesis of intestinal inflammation involves a complex network of cell signaling pathways. CGAS (cyclic GMP-AMP synthase) is a cytoplasmic DNA sensor that is most known for upregulating interferon-mediated inflammation. In this punctum, we discuss our novel finding that in the intestinal epithelium, CGAS binds to BECN1 (beclin 1) to subsequently induce macroautophagy/autophagy and dampen inflammation

Reactive oxygen species are required for driving efficient and sustained aerobic glycolysis during CD4+ T cell activation.

The immune system is necessary for protecting against various pathogens. However, under certain circumstances, self-reactive immune cells can drive autoimmunity, like that exhibited in type 1 diabetes (T1D). CD4+ T cells are major contributors to the immunopathology in T1D, and in order to drive optimal T cell activation, third signal reactive oxygen species (ROS) must be present. However, the role ROS play in mediating this process remains to be further understood. Recently, cellular metabolic programs have been shown to dictate the function and fate of immune cells, including CD4+ T cells. During activation, CD4+ T cells must transition metabolically from oxidative phosphorylation to aerobic glycolysis to support proliferation and effector function. As ROS are capable of modulating cellular metabolism in other models, we sought to understand if blocking ROS also regulates CD4+ T cell activation and effector function by modulating T cell metabolism. To do so, we utilized an ROS scavenging and potent antioxidant manganese metalloporphyrin (MnP). Our results demonstrate that redox modulation during activation regulates the mTOR/AMPK axis by maintaining AMPK activation, resulting in diminished mTOR activation and reduced transition to aerobic glycolysis in diabetogenic splenocytes. These results correlated with decreased Myc and Glut1 upregulation, reduced glucose uptake, and diminished lactate production. In an adoptive transfer model of T1D, animals treated with MnP demonstrated delayed diabetes progression, concurrent with reduced CD4+ T cell activation. Our results demonstrate that ROS are required for driving and sustaining T cell activation-induced metabolic reprogramming, and further support ROS as a target to minimize aberrant immune responses in autoimmunity

Alteration in redox status of CD4⁺ T cells maintains AMPK activation.

<p>(a) Protein lysates were probed with antibodies for phosphorylated AMPK-1α (Thr172; activated), total AMPK, and β actin (loading control). Data are a representative of n = 5 independent experiments.</p

Reducing glycolytic capacity by redox modulation inhibits diabetogenic potential of CD4⁺ T cells.

<p>(a) Schematic of adoptive transfer model of T1D. (b) Survival curve of diabetes free animals following adoptive transfer. Animals were deemed diabetic following 2 consecutive blood glucose readings of >350 mg/dL. Statistical significance of disease progression was calculated using a Kaplan-Meier test (* = p<0.05). (c) T cell activation and prediction of diabetes was measured by serum levels of sLAG-3 by ELISA. Statistical significance was calculated using a Two-way ANOVA with Bonferroni post-hoc analysis. (** = p<0.01). (d) Normalized percent of LAG-3⁺CD25⁺CD4⁺ T cells from spleens of control diabetic and MnP-treated non-diabetic animals (n = 6–8 animals per group; p = 0.0761). (e) Mean fluorescence intensity of pS6 in peripheral blood CD4⁺ T cells from animals at day 4 post-transfer. (f) Representative histograms of S6 phosphorylation from peripheral blood CD4⁺ T cells at day 4 post-transfer from control and MnP treated animals. (g-h) Quantification of frequency of pS6^hi and pS6^lo CD4⁺ T cells. (i) Forward scatter analysis of pS6^lo and pS6^hi CD4⁺ T cells.</p

Mechanism for the effect of ROS inhibition on CD4⁺ T cells during activation-induced metabolic reprogramming.

<p>Upon T cell receptor–MHC interaction, ROS are generated by a functional NOX expressed by T cells. These ROS serve as signaling molecules to help propagate mTOR signaling resulting in Myc upregulation and progression to aerobic glycolysis. Treatment with the ROS-scavenging and potent antioxidant results in inhibition of ROS and maintains potent AMPK activation; thereby, inhibiting mTOR via a two-pronged approach, stabilizing OXPHOS, and limiting T cell proliferation.</p