Evaluating full-thickness skin grafts in intraperitoneal onlay mesh position versus onlay position in mice.

BACKGROUND: Importance: Hernia surgery requires reinforcement material with few side effects when used in the intraperitoneal position. Autologous skin grafting may meet this requirement, but animal experiments are obligatory before being applied in humans. OBJECTIVE: To compare survival and effects of isogeneic full-thickness skin grafts in the intraperitoneal onlay mesh (IPOM) position in mice, with a control group using the onlay position. Primary end point was graft survival and secondary end point adhesion formation and inflammation through NF-κB activity. METHODS: Design: Intervention study with 8-week follow-up in accordance with ARRIVE criteria, performed between 2015 and 2016. SETTING: Animal laboratory. PARTICIPANTS: Transgenic C57BL/6 mice with isogeneic background were used. Recipients were female wild-type phenotype mice >3 mo (n = 24). Donors were male or female mice >7 mo, with phenotype-positive for the luciferase gene (n = 20) or positive for NF-κB-luciferase gene (n = 4). INTERVENTION: Full-thickness skin was grafted in the IPOM position and compared with grafts in the onlay position as controls. Survival was evaluated by regular longitudinal postoperative luminescence imaging over 8 wk. Adherence formation was evaluated macroscopically after sacrifice. Inflammation of full-thickness skin grafts in IPOM position of NF-κB mice was evaluated in four additional mice. Main outcome and measure: Survival of grafts, evaluated by luminescence. RESULTS: Ten animals received grafts in the IPOM position, and 10 in the onlay position as controls. Graft survival after 8 wk was 100% (20/20). Average luminescence at the end of the 8-week period was 999,597 flux (min 162,800, max 2,521,530) in the IPOM group (n = 10) and 769,708 flux (min 76,590, max 2,164,080) in the onlay control group (n = 10). No adhesions requiring sharp dissection (Jenkins' scale >2) were seen. Four animals with grafts in the IPOM position showed peak inflammation (NF-κB activity) 5 d after surgery subsiding toward the end of follow-up. CONCLUSIONS: Full-thickness skin survives as well in the IPOM position as in the onlay control position, and few adherences develop. Further studies are required to fully characterize the tissue remodeling and repair processes associated with IPOM skin grafting. The result is relevant in the search for alternative reinforcement materials to be used in complex hernia surgery in humans.

Survival and Inflammatory Response in Adipose-derived Mesenchymal Stem Cell-enriched Mouse Fat Grafts.

BACKGROUND: Adipose tissue-derived mesenchymal stem cells (ATMSCs) are currently used in grafting procedures in a number of clinical trials. The reconstructive role of such cells in fat graft enrichment is largely unclear. This study was undertaken to assess survival and inflammatory response in fat grafts enriched with ATMSCs in mice. METHODS: ATMSC-enriched adipose tissue was grafted subcutaneously in a clinically relevant manner in mice, and survival and inflammatory response were determined by bioluminescence imaging of transgenic tissue constitutively expressing luciferase or driven by inflammation in wild-type animals. RESULTS: Only a minor fraction of ATMSCs transplanted subcutaneously were found to survive long term, yet fat grafts enriched with ATMSCs showed improved survival for a limited period, compared with no enrichment. NF-κB activity was transiently increased in ATMSC-enriched grafts, and the grafts responded adequately to a proinflammatory stimulus. In one animal, cells originating from the subcutaneous graft were found at a site of inflammation distant from the site of engraftment. CONCLUSION: ATMSCs display limited subcutaneous survival. Still, ATMSC enrichment may improve the outcome of adipose tissue grafting procedures by facilitating short-term graft survival and adequate inflammatory responses. Migration of cells from grafted adipose tissue requires further investigation.

IRF4 Is a Critical Gene in Retinoic Acid-Mediated Plasma Cell Formation and Is Deregulated in Common Variable Immunodeficiency-Derived B Cells.

In the present study, we aimed at identifying the mechanisms whereby the vitamin A metabolite all-trans retinoic acid (RA) promotes the formation of plasma cells upon stimulation of B cells via the innate immunity receptors TLR9 and RP105. Most often, differentiation of B cells involves the sequential events of class switch recombination and somatic hypermutations characteristic of germinal center reactions, followed by plasma cell formation. By studying the regulatory networks known to drive these reactions, we revealed that RA enhances the expression of the plasma cell-generating transcription factors IFN regulatory factor (IRF)4 and Blimp1, and paradoxically also activation-induced deaminase (AID) involved in somatic hypermutations/class switch recombination, in primary human B cells. IRF4 was identified as a particularly important protein involved in the RA-mediated production of IgG in TLR9/RP105-stimulated B cells. Based on kinetic studies, we present a model suggesting that the initial induction of IRF4 by RA favors AID expression. According to this model, the higher level of IRF4 that eventually arises results in sustained elevated levels of Blimp1. Regarded as a master regulator of plasma cell development, Blimp1 will in turn suppress AID expression and drive the formation of IgG-secreting plasma cells. Notably, we demonstrated IRF4 to be deregulated in B cells from common variable immunodeficiency patients, contributing to the observed aberrant expression of AID in these patients. Taken together, the present study both provides new insight into the mechanisms whereby RA induces differentiation of B cells and identifies IRF4 as a key to understand the defective functions of B cells in common variable immunodeficiency patients.

Stress associated gene expression in blood cells is related to outcome in radiotherapy treated head and neck cancer patients.

BACKGROUND: We previously observed that a radiotherapy-induced biochemical response in plasma was associated with favourable outcome in head and neck squamous carcinoma cancer (HNSCC) patients. The aim of the present study was to compare stress associated blood cell gene expression between two sub-groups of HNSCC patients with different biochemical responses to radiotherapy. METHODS: Out of 87 patients (histologically verified), 10 biochemical 'responders' having a high relative increase in plasma oxidative damage and a concomitant decrease in plasma antioxidants during radiotherapy and 10 'poor-responders' were selected for gene-expression analysis and compared using gene set enrichment analysis. RESULTS: There was a significant induction of stress-relevant gene-sets in the responders following radiotherapy compared to the poor-responders. The relevance of the involvement of similar stress associated gene expression for HNSCC cancer and radioresistance was verified using two publicly available data sets of 42 HNSCC cases and 14 controls (GEO GSE6791), and radiation resistant and radiation sensitive HNSCC xenografts (E-GEOD-9716). CONCLUSIONS: Radiotherapy induces a systemic stress response, as revealed by induction of stress relevant gene expression in blood cells, which is associated to favourable outcome in a cohort of 87 HNSCC patients. Whether these changes in gene expression reflects a systemic effect or are biomarkers of the tumour micro-environmental status needs further study. TRIAL REGISTRATION: Raw data are available at ArrayExpress under accession number E-MEXP-2460.

Blood cell gene expression associated with cellular stress defense is modulated by antioxidant-rich food in a randomised controlled clinical trial of male smokers.

BACKGROUND: Plant-based diets rich in fruit and vegetables can prevent development of several chronic age-related diseases. However, the mechanisms behind this protective effect are not elucidated. We have tested the hypothesis that intake of antioxidant-rich foods can affect groups of genes associated with cellular stress defence in human blood cells. TRIAL REGISTRATION NUMBER: NCT00520819 http://clinicaltrials.gov. METHODS: In an 8-week dietary intervention study, 102 healthy male smokers were randomised to either a diet rich in various antioxidant-rich foods, a kiwifruit diet (three kiwifruits/d added to the regular diet) or a control group. Blood cell gene expression profiles were obtained from 10 randomly selected individuals of each group. Diet-induced changes on gene expression were compared to controls using a novel application of the gene set enrichment analysis (GSEA) on transcription profiles obtained using Affymetrix HG-U133-Plus 2.0 whole genome arrays. RESULTS: Changes were observed in the blood cell gene expression profiles in both intervention groups when compared to the control group. Groups of genes involved in regulation of cellular stress defence, such as DNA repair, apoptosis and hypoxia, were significantly upregulated (GSEA, FDR q-values < 5%) by both diets compared to the control group. Genes with common regulatory motifs for aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (AhR/ARNT) were upregulated by both interventions (FDR q-values < 5%). Plasma antioxidant biomarkers (polyphenols/carotenoids) increased in both groups. CONCLUSIONS: The observed changes in the blood cell gene expression profiles suggest that the beneficial effects of a plant-based diet on human health may be mediated through optimization of defence processes.

Polyphenols and glutathione synthesis regulation.

Polyphenols in food plants are a versatile group of phytochemicals with many potentially beneficial activities in terms of disease prevention. In vitro cell culture experiments have shown that polyphenols possess antioxidant properties, and it is thought that these activities account for disease-preventing effects of diets high in polyphenols. However, polyphenols may be regarded as xenobiotics by animal cells and are to some extent treated as such, ie, they interact with phase I and phase II enzyme systems. We recently showed that dietary plant polyphenols, namely, the flavonoids, modulate expression of an important enzyme in both cellular antioxidant defenses and detoxification of xenobiotics, ie, gamma-glutamylcysteine synthetase. This enzyme is rate limiting in the synthesis of the most important endogenous antioxidant in cells, glutathione. We showed in vitro that flavonoids increase expression of gamma-glutamylcysteine synthetase and, by using a unique transgenic reporter mouse strain, we showed increased expression in vivo, with a concomitant increase in the intracellular glutathione concentrations in muscles. Because glutathione is important in redox regulation of transcription factors and enzymes for signal transduction, our results suggest that polyphenol-mediated regulation of glutathione alters cellular processes. Evidently, glutathione is important in many diseases, and regulation of intracellular glutathione concentrations may be one mechanism by which diet influences disease development. The aim of this review is to discuss some of the mechanisms involved in the glutathione-mediated, endogenous, cellular antioxidant defense system, how its possible modulation by dietary polyphenols such as flavonoids may influence disease development, and how it can be studied with in vivo imaging.

In vivo imaging of NF-kappa B activity.

A wide range of human disorders involves inappropriate regulation of NF-kappaB, including cancers and numerous inflammatory conditions. Toward our goal to define mechanisms through which NF-kappaB leads to the development of disease, we have developed transgenic mice that express luciferase under the control of NF-kappaB, enabling real-time in vivo imaging of NF-kappaB activity in intact animals. We show that in the absence of extrinsic stimulation, strong luminescence is evident in lymph nodes in the neck region, thymus, and Peyer's patches. Treating mice with TNF-alpha, IL-1alpha, or LPS increased the luminescence in a tissue-specific manner, with the strongest activity observed in skin, lungs, spleen, Peyer's patches, and the wall of the small intestine. Liver, kidney, heart, muscle, and adipose tissue displayed less intense activities. Also, exposure of skin to a low dose of UV radiation increased luminescence in the exposed areas. Furthermore, induction of chronic inflammation resembling rheumatoid arthritis produced strong NF-kappaB activity in the affected joints, as revealed by in vivo imaging. Thus, we have developed a versatile model for monitoring NF-kappaB activation in vivo.