Real-World Effectiveness of Vedolizumab vs Anti-TNF in Biologic-naïve Crohn's Disease Patients: A 2-year Propensity-score-adjusted Analysis from the VEDOIBD-Study.

BACKGROUND: The aim of this observational, real-world evidence, modified intention-to-treat (mITT) study based on prospectively collected data from the VEDOIBD registry was to compare the effectiveness of vedolizumab (VEDO) vs antitumor necrosis factor (anti-TNF) in biologic-naïve Crohn's disease (CD) patients. METHODS: Between 2017 and 2020, 557 CD patients starting therapy with VEDO or anti-TNF were consecutively enrolled in 45 IBD centers across Germany. Per study protocol, the analysis excluded biologic-experienced patients and those with a missing Harvey-Bradshaw Index score, resulting in a final sample of 327 biologic-naïve CD patients. Clinical remission was measured using the Harvey-Bradshaw Index at the end of induction therapy and after 1 and 2 years. Switching to a different therapy was considered an outcome failure. Propensity score adjustment with inverse probability of treatment weighting was used to correct for confounding. RESULTS: The effectiveness of both VEDO (n = 86) and anti-TNF (n = 241) was remarkably high for induction treatment, but VEDO performed significantly less well than anti-TNF (clinical remission: 56.3% vs 73.9%, P < .05). In contrast, clinical remission after 2 years was significantly better for VEDO compared with anti-TNF (74.2% vs 44.7%; P < .05; odds ratio, 0.45; 95% CI, 0.22-0.94). Remarkably, only 17% of patients switched from VEDO to another biologic vs 44% who received anti-TNF. CONCLUSIONS: The results of this prospective, 2-year, real-world evidence study suggest that the choice of VEDO led to higher remission rates after 2 years compared with anti-TNF. This could support the role of VEDO as a first-line biologic therapy in CD.

Real-world effectiveness of vedolizumab compared to anti-TNF agents in biologic-naïve patients with ulcerative colitis: A two-year propensity-score-adjusted analysis from the prospective, observational VEDOIBD -study.

BACKGROUND: This observational real-world evidence (RWE) study is based on prospectively collected data from the VEDOIBD registry study. AIM: To compare the effectiveness of vedolizumab and anti-TNF agents in biologic-naïve patients with ulcerative colitis (UC) at the end of induction and during maintenance treatment. METHODS: Between 2017 and 2020, we enrolled 512 patients with UC starting therapy with vedolizumab or an anti-TNF agent in 45 IBD centres across Germany. We excluded biologic-experienced patients and those with missing partial Mayo (pMayo) outcomes; this resulted in a final sample of 314 (182 on vedolizumab and 132 on an anti-TNF agent). The primary outcome was clinical remission measured using pMayo score; any switch to a different biologic agent was considered an outcome failure (modified ITT analysis). We used propensity score adjustment with inverse probability of treatment weighting to correct for confounding. RESULTS: During induction therapy, clinical remission was relatively low and similar in vedolizumab- and anti-TNF-treated patients (23% vs. 30.4%, p = 0.204). However, clinical remission rates after two years were significantly higher for vedolizumab-treated patients than those treated with an anti-TNF agent (43.2% vs. 25.8%, p < 0.011). Among patients treated with vedolzumab, 29% switched to other biologics, versus 54% who had received an anti-TNF agent. CONCLUSION: After two years of treatment, vedolizumab resulted in higher remission rates than anti-TNF agents.

Safety of vedolizumab in the treatment of pregnant women with inflammatory bowel disease: a targeted literature review.

BACKGROUND: Crohn's disease (CD) and ulcerative colitis (UC) commonly affect women in their childbearing years. Vedolizumab (VDZ) is approved for treatment of moderate-to-severe CD and UC, but there is a knowledge gap regarding its use during pregnancy. This targeted literature review describes available evidence on safety of VDZ in pregnant patients in order to offer physicians a detailed and balanced view on persistent data during their decision-making process for an individualized treatment concept. METHODS: The search included literature from the MEDLINE database and abstracts of five gastroenterological conferences published until November 2019. Publications were included if pregnancy outcomes in women receiving VDZ or neonatal outcomes in newborns of women previously exposed to VDZ were reported. RESULTS: Out of 196 initially identified records, 18 publications reporting results of five different studies were identified. In total, for 213 of 284 VDZ-exposed documented pregnancies the following pregnancy outcomes were reported: 167 live births (172 infants due to twin births), 1 stillbirth, 35 miscarriages, 10 elective terminations (1 due to detected Down syndrome). Furthermore, during pregnancy, the following complications were observed: seven cases of (pre) eclampsia, three cases of premature rupture of membranes and one case each of placenta previa, chorioamnionitis, pneumonia, first-trimester bleeding, cholestasis, sepsis, or neonatal intraventricular hemorrhage. Based on 172 infants, 30 preterm deliveries (17.4%), 9 cases of low birth weight (5.2%), 5 infections (2.9%), and 6 cases (3.8%) with congenital anomalies were reported. CONCLUSION: There was no evidence for safety concerns regarding pregnancy outcomes associated with VDZ therapy. Due to the limited scope of included records, further research is needed to understand the safety profile regarding the use of VDZ during pregnancy.

Real-world clinical effectiveness and safety of vedolizumab and anti-tumor necrosis factor alpha treatment in ulcerative colitis and Crohn's disease patients: a German retrospective chart review.

BACKGROUND: Real-world comparisons of biologic treatment outcomes for ulcerative colitis (UC) or Crohn's disease (CD) patients are limited. We sought to evaluate the real-world effectiveness of vedolizumab (VDZ) and anti-tumor necrosis factor alpha (anti-TNFα) in UC and CD patients in Germany. METHODS: A retrospective chart review (15 sites) investigated UC and CD patients who were biologic-treatment naïve (biologic-naïve) or had received no more than one prior anti-TNFα before initiating treatment with VDZ or anti-TNFα between 15 July 2014 and 20 October 2015. Kaplan-Meier analyses assessed time to first chart-documented clinical remission (CR) and symptom resolution (UC: rectal bleeding [RB], stool frequency [SF]; CD: abdominal pain [AP], liquid stools [LS]) and outcome duration. RESULTS: A total of 133 UC (76 VDZ; 57 anti-TNFα) and 174 CD (69 VDZ; 105 anti-TNFα) patients were included. By Week 26, estimated cumulative rates of patients achieving CR or symptom resolution with VDZ vs anti-TNFα treatment were for UC: CR, 53.7% vs 31.7%; RB, 66.8% vs 55.8%; and SF, 59.8% vs 50.7%, respectively; and for CD: CR, 14.4% vs 32.8%; AP, 62.5% vs 56.0%; and LS, 29.9% vs 50.3%, respectively. Outcomes were sustained similarly between treatments, except RB (VDZ vs anti-TNFα: median 38.1 vs 15.1 weeks, P = 0.03). Treatment-related adverse events occurred in 5.3% vs 7.0% (UC) and 8.7% vs 19.0% (CD) of VDZ vs anti-TNFα patients, respectively. CONCLUSIONS: Although there were differences in CR, symptom resolution, and safety profiles, real-world data support both VDZ and anti-TNFα as effective treatment options in UC and CD.

Perceived distress, personality characteristics, coping strategies and psychosocial impairments in a national German multicenter cohort of patients with Crohn's disease and ulcerative colitis.

BACKGROUND AND AIMS: This study examined differences in personality, psychological distress, and stress coping in inflammatory bowel disease (IBD) depending on type of disease and disease activity. We compared patients suffering from Crohn's disease (CD) and ulcerative colitis (UC) with controls. While the literature is replete with distinctive features of the pathogenesis of IBD, the specific differences in psychological impairments are not well studied. METHODS: In this German national multicenter study, participants were recruited from 32 centers. Two hundred ninety-seven questionnaires were included, delivering vast information on disease status and psychological well-being based on validated instruments with a total of 285 variables. RESULTS: CD patients were more affected by psychological impairments than patients suffering from UC or controls. Importantly, patients with active CD scored higher in neuroticism (p < 0.01), psychological distress (p < 0.001) and maladaptive stress coping (escape, p = 0.03; rumination, p < 0.03), but less need for social support (p = 0.001) than controls. In contrast, patients suffering from active UC showed psychological distress (p < 0.04) and maladaptive coping (avoidance, p < 0.03; escape, p = 0.01). Patients in remission seemed to be less affected. In particular, patients with UC in remission were not inflicted by psychological impairments. The group of CD patients in remission however, showed insecurity (p < 0.01) and paranoid ideation (p = 0.04). CONCLUSIONS: We identified specific aspects of psychological impairment in IBD depending on disease and disease activity. Our results underscore the need for psychological support and treatment particularly in active CD.

Sustained Clinical Remission With Vedolizumab in Patients With Moderate-to-Severe Ulcerative Colitis.

BACKGROUND: Sustaining clinical remission is an important treatment goal in moderate-to-severe UC. This post hoc exploratory analysis assessed the long-term efficacy of vedolizumab in the subset of patients with UC in the GEMINI 1 study who were in clinical remission by week 14 after 3 induction doses, administered at weeks 0, 2, and 6. METHODS: Sustained clinical remission (primary endpoint) was evaluated using 2 definitions: (1) a partial Mayo Score (pMS) of ≤2 with no subscore >1 and (2) a rectal bleeding subscore (RBS) of 0 throughout weeks 14, 26, 38, and 52. RESULTS: The proportion of patients in clinical remission at week 14 was significantly higher in patients receiving vedolizumab (n = 620) compared with placebo (n = 149) (pMS: 32.7% vs 20.1% [percentage-point difference (∆) 12.6%; 95% confidence interval [CI], 5.2-20.0]; RBS: 47.3% vs 28.9% [∆18.4%; 95% CI, 10.1-26.7]). Of patients in clinical remission at week 14, a significantly higher proportion of vedolizumab-treated patients achieved sustained clinical remission compared with placebo (pMS: 66.5% vs 26.7%; ∆39.8%; 95% CI, 22.7-56.9; RBS: 56.7% vs 20.9%; ∆35.7%; 95% CI, 22.3-49.1). Findings were consistent in tumor necrosis factor (TNF) antagonist-naive and antagonist-failure patients. CONCLUSION: Compared with placebo, 35%-40% more patients receiving a full induction course of vedolizumab had sustained clinical remission after 52 weeks of therapy. This result was observed irrespective of TNF antagonist treatment history. Clinical remission at week 14 may therefore be a predictor for sustained clinical remission with vedolizumab.

The metabolic capacity of lipid droplet localized acyl-CoA synthetase 3 is not sufficient to support local triglyceride synthesis independent of the endoplasmic reticulum in A431 cells.

ACSL3 is the only long chain fatty acyl-CoA synthetase consistently found on growing and mature lipid droplets (LDs), suggesting that this specific localization has biological relevance. Current models for LD growth propose that triglycerides are synthesized by enzymes at the LD surface, with activated fatty acids provided by LD localized ACSL3, thus allowing growth independent of the ER. Here, we tested this hypothesis by quantifying ACSL3 on LDs from human A431 cells. RNAi of ACSL3 reduced the oleoyl-CoA synthetase activity by 83%, suggesting that ACSL3 is by far the dominant enzyme of A431 cells. Molar quantification revealed that there are 1.4 million ACSL3 molecules within a single cell. Metabolic labeling indicated that each ACSL3 molecule contributed a net gain of 3.1 oleoyl-CoA/s. 3D reconstruction of confocal images demonstrated that 530 individual lipid droplets were present in an average oleate fed A431 cell. A representative single lipid droplet with a diameter of 0.66 µm contained 680 ACSL3 molecules on the surface. Subcellular fractionation showed that at least 68% of ACSL3 remain at the ER even during extensive fatty acid supplementation. High resolution single molecule microscopy confirmed the abundance of cytoplasmic ACSL3 outside of LDs. Model calculations for triglyceride synthesis using only LD localized ACSL3 gave significant slower growth of LDs as observed experimentally. In conclusion, although ACSL3 is an abundant enzyme on A431 LDs, the metabolic capacity is not sufficient to account for LD growth solely by the local synthesis of triglycerides.

Stable isotope and high precision concentration measurements confirm that all humans produce and exhale methane.

Mammalian formation of methane (methanogenesis) is widely considered to occur exclusively by anaerobic microbial activity in the gastrointestinal tract. Approximately one third of humans, depending on colonization of the gut by methanogenic archaea, are considered methane producers based on the classification terminology of high and low emitters. In this study laser absorption spectroscopy was used to precisely measure concentrations and stable carbon isotope signatures of exhaled methane in breath samples from 112 volunteers with an age range from 1 to 80 years. Here we provide analytical evidence that volunteers exhaled methane levels were significantly above background (inhaled) air. Furthermore, stable carbon isotope values of the exhaled methane unambiguously confirmed that this gas was produced by all of the human subjects studied. Based on the emission and stable carbon isotope patterns of various age groups we hypothesize that next to microbial sources in the gastrointestinal tracts there might be other, as yet unidentified, processes involved in methane formation supporting the idea that humans might also produce methane endogenously in cells. Finally we suggest that stable isotope measurements of volatile organic compounds such as methane might become a useful tool in future medical research diagnostic programs.

Intestinal cytomegalovirus infection in patients hospitalized for exacerbation of inflammatory bowel disease: a 10-year tertiary referral center experience.

OBJECTIVES: This 10-year retrospective cohort study aims to determine the prevalence and risk factors of cytomegalovirus (CMV) infection in inpatients with exacerbated inflammatory bowel disease (IBD). METHODS: All patients admitted to the Department of Gastroenterology of the University Hospital Heidelberg for IBD exacerbation between January 2004 and June 2013 were enrolled. To identify the risk factors of CMV infection, infected individuals were compared with those with excluded infection. RESULTS: Among 297 patients with exacerbated IBD, 21 had confirmed CMV infection and 79 had excluded CMV infection, whereas the remaining patients had not been sufficiently tested for CMV. Taking into account only sufficiently tested individuals, the prevalence of CMV infection was 22.7% in ulcerative colitis and 16.0% in Crohn's disease. The occurrence of CMV infection was associated with the following variables at admission: age of 30 years or more [odds ratio (OR) 14.29; P=0.004], disease duration less than 60 months (OR 7.69; P=0.011), a blood leukocyte count less than 11/nl (OR 4.49; P=0.041), and immunosuppressive therapy (OR 6.73; P=0.0129). CMV-positive patients remained in the hospital longer than noninfected patients (P=0.0009). In the CMV-positive cohort, a 66-year-old woman died of CMV pneumonia and sepsis, whereas there was no death in the CMV-negative cohort. CONCLUSION: Immunuosuppressive therapy and age older than 30 years were identified as the main risk factors for the development of CMV infection in exacerbated IBD. Because of the risk of death, diagnostics of CMV infection should especially be initiated in older patients on immunosuppressive therapy.

Real-life outcome of anti-tumor necrosis factor α in the ambulatory treatment of ulcerative colitis.

AIM: To evaluate the outcome of anti-tumor necrosis factor alpha (anti-TNFα) therapy in outpatients with ulcerative colitis at a tertiary referral center. METHODS: All patients with a confirmed diagnosis of ulcerative colitis undergoing therapy with infliximab and/or adalimumab at the outpatient clinic for inflammatory bowel diseases at the University Hospital Heidelberg between January 2011 and February 2014 were retrospectively enrolled. Patients with a follow-up period of less than 6 mo from start of anti-TNFα therapy were excluded. Medical records of all eligible individuals were carefully reviewed. Steroid-free clinical remission of a duration of at least 3 mo, colectomy rate, duration of anti-TNFα therapy, need for anti-TNFα dose escalation, and the occurrence of adverse events were evaluated as the main outcome parameters. RESULTS: Seventy-two patients were included (35 treated with infliximab, 17 with adalimumab, 20 with both consecutively). Median follow-up was 27 mo (range: 6-87 mo). Steroid-free clinical remission was achieved by 22.2% of the patients (median duration: 21 mo until end of follow-up; range: 3-66 mo). Patients attaining steroid-free clinical remission displayed lower hemoglobin and albumin blood levels at the start of treatment than those who did not achieve remission. The overall colectomy rate was 20.8%. Nearly 50% of the patients underwent anti-TNFα dose escalation during the follow-up period. For both the infliximab and the adalimumab treated patients, non-response to anti-TNFα therapy was the major reason for treatment discontinuation. 18.2% of the infliximab-treated patients and 13.5% of the adalimumab-treated patients had to discontinue their therapy due to adverse events. CONCLUSION: Real-life remission rates of ulcerative colitis under anti-TNFα are overall low, but some patients have a clear long-term benefit.

Protein mediated fatty acid uptake: synergy between CD36/FAT-facilitated transport and acyl-CoA synthetase-driven metabolism.

The mechanism of cellular fatty acid uptake is highly relevant for basic and clinical research. Previous work has demonstrated that fatty acid uptake is facilitated by cell surface membrane proteins as well as by intracellularly localized enzymes. Here, the exogenous expression of the CD36/FAT glycoprotein and the acyl-CoA synthetases FATP4 and ACSL1 in MDCK cells was quantified by comparison to recombinant proteins, and related to the corresponding increases of fatty acid uptake. At the molecular level, CD36/FAT was 30-fold more efficient than either FATP4 or ACSL1 in enhancing fatty acid uptake. Remarkably, co-expression of CD36/FAT with FATP4 or ACSL1 led to a higher increase of fatty acid uptake than expected from the combined individual contributions, whereas co-expression of FATP4 and ACSL1 did not. Immunofluorescence microscopy confirmed the plasma membrane localization of CD36/FAT and the intracellular localization of FATP4 to the endoplasmic reticulum, and of ACSL1 to mitochondria. Concluding, we suggest that fatty acid uptake in our model system is organized by two spatially distinct but synergistic mechanisms: the cell surface protein CD36/FAT directly facilitates fatty acid transport across the plasma membrane, whereas the intracellular acyl-CoA synthetases FATP4 and ACSL1 enhance fatty acid uptake indirectly by metabolic trapping.

Differentially localized acyl-CoA synthetase 4 isoenzymes mediate the metabolic channeling of fatty acids towards phosphatidylinositol.

The acyl-CoA synthetase 4 (ACSL4) has been implicated in carcinogenesis and neuronal development. Acyl-CoA synthetases are essential enzymes of lipid metabolism, and ACSL4 is distinguished by its preference for arachidonic acid. Two human ACSL4 isoforms arising from differential splicing were analyzed by ectopic expression in COS cells. We found that the ACSL4_v1 variant localized to the inner side of the plasma membrane including microvilli, and was also present in the cytosol. ACSL4_v2 contains an additional N-terminal hydrophobic region; this isoform was located at the endoplasmic reticulum and on lipid droplets. A third isoform was designed de novo by appending a mitochondrial targeting signal. All three ACSL4 variants showed the same specific enzyme activity. Overexpression of the isoenzymes increased cellular uptake of arachidonate to the same degree, indicating that the metabolic trapping of fatty acids is independent of the subcellular localization. Remarkably, phospholipid metabolism was changed by ACSL4 expression. Labeling with arachidonate showed that the amount of newly synthesized phosphatidylinositol was increased by all three ACSL4 isoenzymes but not by ACSL1. This was dependent on the expression level and the localization of the ACSL4 isoform. We conclude that in our model system exogenous fatty acids are channeled preferentially towards phosphatidylinositol by ACSL4 overexpression. The differential localization of the endogenous isoenzymes may provide compartment specific precursors of this anionic phospholipid important for many signaling processes.

CYP3A activity in severe liver cirrhosis correlates with Child-Pugh and model for end-stage liver disease (MELD) scores.

AIMS: Impaired liver function often necessitates drug dose adjustment to avoid excessive drug accumulation and adverse events, but a marker for the extent of the required adjustment is lacking. The aim of this study was to investigate whether Child-Pugh (CP) and model for end-stage liver disease (MELD) scores correlate with drug clearance. METHODS: Midazolam was used as a CYP3A probe and its pharmacokinetics were analyzed in 24 patients with mild to severe liver cirrhosis (n = 4, 10 and 10 with CP class A, B and C, respectively) and six patients without liver disease. RESULTS: Both scores correlated well with unbound midazolam clearance (CLu ), unbound midazolam fraction and half-life (all P < 0.01), whereas the unbound steady-state volume of distribution was not significantly changed. In patients with severe liver cirrhosis unbound midazolam clearance was only 14% of controls (CP C: CLu = 843 ± 346 l h(-1), MELD ≥ 15: CLu = 805 ± 474 l h(-1), controls: CLu = 5815 ± 2649 l h(-1), P < 0.01). CONCLUSION: The correlation with unbound midazolam clearance suggests that either score predicts the metabolic capacity of CYP3A, the most relevant drug metabolizing enzyme subfamily in humans.

Biliary phosphatidylcholine and lysophosphatidylcholine profiles in sclerosing cholangitis.

AIM: To analyze phospholipid profiles in intrahepatic bile from patients with primary sclerosing cholangitis (PSC) and secondary sclerosing cholangitis (SSC). METHODS: Intrahepatic bile specimens collected via endoscopic retrograde cholangiography from 41 patients were analyzed. Fourteen of these patients were diagnosed with PSC, 10 with SSC, 11 with choledocholithiasis or no identifiable biliary disease, and 6 with cholangiocellular carcinoma (CCC). Bile acid, cholesterol, protein, and bilirubin contents as well as pancreas lipase activity in bile were determined by biochemical methods. Phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) species were quantified using nano-electrospray ionization tandem mass spectrometry. RESULTS: Bile from all the examined patient groups showed a remarkably similar PC and LPC species composition, with only minor statistical differences. Total biliary PC concentrations were highest in controls (8030 ± 1843 µmol/L) and lowest in patients with CCC (1969 ± 981 µmol/L) (P = 0.005, controls vs SSC and CCC, respectively, P < 0.05). LPC contents in bile were overall low (4.2% ± 1.8%). Biliary LPC/PC ratios and ratios of biliary PC to bilirubin, PC to cholesterol, PC to protein, and PC to bile acids showed no intergroup differences. CONCLUSION: PC and LPC profiles being similar in patients with or without sclerosing cholangitis, these phospholipids are likely not of major pathogenetic importance in this disease group.

Flotillin-2 expression in the human gut: from a cell model to human tissue in health and inflammatory bowel diseases.

BACKGROUND AND AIMS: The etiopathogenesis of inflammatory bowel diseases (IBD) remains largely unexplained. Flotillins (flotillin-1 and flotillin-2) are ubiquitous proteins which have been linked to inflammation and regeneration. We hypothesized that alterations in the expression of flotillin-2 in enterocytes may be related to the pathogenesis of IBD as a classical example of an inflammatory disorder of mostly unknown origin. METHODS: Cell and tissue localization of flotillin-2 (and -1) were investigated by immunofluorescent staining in 1. polarized and unpolarized CaCo-2w cells as a model of human enterocytes (native and after TNFα stimulation) and 2. intestinal biopsies from controls, patients with ulcerative colitis (UC) and patients with Crohn's disease (CD). For quantification of flotillin-2, we analyzed its expression in ileal and colonic biopsies from controls, UC patients and CD patients using real-time RT-PCR, Western blot and indirect immunofluorescence. RESULTS: In polarized CaCo-2w cells and human enterocytes in biopsies, flotillins were localized at the basolateral membrane and on subapical vesicles, but not in the apical membrane. Flotillin-2 expression did not differ between UC patients, CD patients and controls. However, it was significantly higher in colonic biopsies compared to ileal biopsies in all groups. CONCLUSIONS: By virtue of its abundant expression in enterocytes, flotillin-2 must have an essential function in intestinal physiology, especially in the colon. Yet our data could not link flotillin-2 to the pathogenesis of IBD.

Outlook: membrane junctions enable the metabolic trapping of fatty acids by intracellular acyl-CoA synthetases.

The mechanism of fatty acid uptake is of high interest for basic research and clinical interventions. Recently, we showed that mammalian long chain fatty acyl-CoA synthetases (ACS) are not only essential enzymes for lipid metabolism but are also involved in cellular fatty acid uptake. Overexpression, RNAi depletion or hormonal stimulation of ACS enzymes lead to corresponding changes of fatty acid uptake. Remarkably, ACS are not localized to the plasma membrane where fatty acids are entering the cell, but are found instead at the endoplasmic reticulum (ER) or other intracellular organelles like mitochondria and lipid droplets. This is in contrast to current models suggesting that ACS enzymes function in complex with transporters at the cell surface. Drawing on recent insights into non-vesicular lipid transport, we suggest a revised model for the cellular fatty acid uptake of mammalian cells which incorporates trafficking of fatty acids across membrane junctions. Intracellular ACS enzymes are then metabolically trapping fatty acids as acyl-CoA derivatives. These local decreases in fatty acid concentration will unbalance the equilibrium of fatty acids across the plasma membrane, and thus provide a driving force for fatty acid uptake.

Overexpressed FATP1, ACSVL4/FATP4 and ACSL1 increase the cellular fatty acid uptake of 3T3-L1 adipocytes but are localized on intracellular membranes.

Long chain acyl-CoA synthetases are essential enzymes of lipid metabolism, and have also been implicated in the cellular uptake of fatty acids. It is controversial if some or all of these enzymes have an additional function as fatty acid transporters at the plasma membrane. The most abundant acyl-CoA synthetases in adipocytes are FATP1, ACSVL4/FATP4 and ACSL1. Previous studies have suggested that they increase fatty acid uptake by direct transport across the plasma membrane. Here, we used a gain-of-function approach and established FATP1, ACSVL4/FATP4 and ACSL1 stably expressing 3T3-L1 adipocytes by retroviral transduction. All overexpressing cell lines showed increased acyl-CoA synthetase activity and fatty acid uptake. FATP1 and ACSVL4/FATP4 localized to the endoplasmic reticulum by confocal microscopy and subcellular fractionation whereas ACSL1 was found on mitochondria. Insulin increased fatty acid uptake but without changing the localization of FATP1 or ACSVL4/FATP4. We conclude that overexpressed acyl-CoA synthetases are able to facilitate fatty acid uptake in 3T3-L1 adipocytes. The intracellular localization of FATP1, ACSVL4/FATP4 and ACSL1 indicates that this is an indirect effect. We suggest that metabolic trapping is the mechanism behind the influence of acyl-CoA synthetases on cellular fatty acid uptake.

Results of the 2nd scientific workshop of the ECCO (III): basic mechanisms of intestinal healing.

The second scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal healing for the disease course of inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms, markers for disease prediction, detection and monitoring of intestinal healing, impact of intestinal healing on the disease course of IBD as well as therapeutic strategies. The results of this workshop are presented in four separate manuscripts. This section describes basic mechanisms of intestinal healing, identifies open questions in the field and provides a framework for future studies.