Regional Differences in the Small Intestinal Proteome of Control Mice and of Mice Lacking Lysosomal Acid Lipase.

The metabolic contribution of the small intestine (SI) is still unclear despite recent studies investigating the involvement of single cells in regional differences. Using untargeted proteomics, we identified regional characteristics of the three intestinal tracts of C57BL/6J mice and found that proteins abundant in the mouse ileum correlated with the high ileal expression of the corresponding genes in humans. In the SI of C57BL/6J mice, we also detected an increasing abundance of lysosomal acid lipase (LAL), which is responsible for degrading triacylglycerols and cholesteryl esters within the lysosome. LAL deficiency in patients and mice leads to lipid accumulation, gastrointestinal disturbances, and malabsorption. We previously demonstrated that macrophages massively infiltrated the SI of Lal-deficient (KO) mice, especially in the duodenum. Using untargeted proteomics (ProteomeXchange repository, data identifier PXD048378), we revealed a general inflammatory response and a common lipid-associated macrophage phenotype in all three intestinal segments of Lal KO mice, accompanied by a higher expression of GPNMB and concentrations of circulating sTREM2. However, only duodenal macrophages activated a metabolic switch from lipids to other pathways, which were downregulated in the jejunum and ileum of Lal KO mice. Our results provide new insights into the process of absorption in control mice and possible novel markers of LAL-D and/or systemic inflammation in LAL-D.

Limited Alleviation of Lysosomal Acid Lipase Deficiency by Deletion of Matrix Metalloproteinase 12.

Lysosomal acid lipase (LAL) is the only known enzyme that degrades cholesteryl esters and triglycerides at an acidic pH. In LAL deficiency (LAL-D), dysregulated expression of matrix metalloproteinase 12 (MMP-12) has been described. The overexpression of MMP-12 in myeloid lineage cells causes an immune cell dysfunction resembling that of Lal knockout (Lal KO) mice. Both models develop progressive lymphocyte dysfunction and expansion of myeloid-derived suppressor (CD11b+ Gr-1+) cells. To study whether MMP-12 might be a detrimental contributor to the pathology of LAL-D, we have generated Lal/Mmp12 double knockout (DKO) mice. The phenotype of Lal/Mmp12 DKO mice closely resembled that of Lal KO mice, while the weight and morphology of the thymus were improved in Lal/Mmp12 DKO mice. Cytological examination of blood smears showed a mildly reversed lymphoid-to-myeloid shift in DKO mice. Despite significant decreases in CD11b+ Ly6G+ cells in the peripheral blood, bone marrow, and spleen of Lal/Mmp12 DKO mice, the hematopoietic bone marrow progenitor compartment and markers for neutrophil chemotaxis were unchanged. Since the overall severity of LAL-D remains unaffected by the deletion of Mmp12, we conclude that MMP-12 does not represent a viable target for treating the inflammatory pathology in LAL-D.

Genetic deletion of MMP12 ameliorates cardiometabolic disease by improving insulin sensitivity, systemic inflammation, and atherosclerotic features in mice.

BACKGROUND: Matrix metalloproteinase 12 (MMP12) is a macrophage-secreted protein that is massively upregulated as a pro-inflammatory factor in metabolic and vascular tissues of mice and humans suffering from cardiometabolic diseases (CMDs). However, the molecular mechanisms explaining the contributions of MMP12 to CMDs are still unclear. METHODS: We investigated the impact of MMP12 deficiency on CMDs in a mouse model that mimics human disease by simultaneously developing adipose tissue inflammation, insulin resistance, and atherosclerosis. To this end, we generated and characterized low-density lipoprotein receptor (Ldlr)/Mmp12-double knockout (DKO) mice fed a high-fat sucrose- and cholesterol-enriched diet for 16-20 weeks. RESULTS: DKO mice showed lower cholesterol and plasma glucose concentrations and improved insulin sensitivity compared with LdlrKO mice. Untargeted proteomic analyses of epididymal white adipose tissue revealed that inflammation- and fibrosis-related pathways were downregulated in DKO mice. In addition, genetic deletion of MMP12 led to alterations in immune cell composition and a reduction in plasma monocyte chemoattractant protein-1 in peripheral blood which indicated decreased low-grade systemic inflammation. Aortic en face analyses and staining of aortic valve sections demonstrated reduced atherosclerotic plaque size and collagen content, which was paralleled by an improved relaxation pattern and endothelial function of the aortic rings and more elastic aortic sections in DKO compared to LdlrKO mice. Shotgun proteomics revealed upregulation of anti-inflammatory and atheroprotective markers in the aortas of DKO mice, further supporting our data. In humans, MMP12 serum concentrations were only weakly associated with clinical and laboratory indicators of CMDs. CONCLUSION: We conclude that the genetic deletion of MMP12 ameliorates obesity-induced low-grade inflammation, white adipose tissue dysfunction, biomechanical properties of the aorta, and the development of atherosclerosis. Therefore, therapeutic strategies targeting MMP12 may represent a promising approach to combat CMDs.

Detection rates for adenomas, serrated polyps and clinically relevant serrated polyps can be easily estimated by individually calculated detection rate ratios.

Background and aims: Adenoma detection rate (ADR) is a key quality indicator for colonoscopy; however, it is cumbersome to obtain. We investigated if detection rates (DRs) for adenomas, serrated polyps (SPs) and clinically relevant SP (crSPDR) can be accurately estimated by individualized DR ratios (DRRs) in a multicenter primary colonoscopy screening cohort of average-risk individuals.Methods: DRRs were calculated by dividing DRs for a certain polyp entity by polyp detection rate (PDR) for each endoscopist individually on the basis of his/her first 50 (DRR50) and 100 (DRR100) consecutive colonoscopies. DRs were estimated for each endoscopist by multiplying his/her DRR for a certain polyp entity with his/her PDR of subsequent colonoscopies in groups of 50 (DRR50) and 100 (DRR100) consecutive colonoscopies. Estimated and actual DRs were compared.Results: Estimated DRs showed a strong correlation with actual DRs for adenomas (r = 0.86 and 0.87; each p < .001), SPs (r = 0.85 and 0.91; each p < .001) and crSPs (r = 0.82 and 0.86; each p < .001) using DRRs derived from first 50 and 100 consecutive colonoscopies. Corresponding root mean square error (RMSE) between individual estimated and actual DRs using DRR50 and DRR100 was 5.3(±4.6)% and 4.5(±4.8)% for adenomas, 5.2(±4.1)% and 3.9(±2.8)% for SP, 3.1(±3.1)% and 2.8(±2.5)% for crSP, respectively. RMSE was not significantly different between DRR50 and DRR100 for ADR (p = .445), SPDR (p = .178) and crSP (p = .544).Conclusions: DR for all relevant polyp entities can be accurately estimated by using individual DRRs. This approach may enable endoscopists to easily track their performance measures in daily routine.

Assessing guideline adherence in patients with non-variceal upper gastrointestinal bleeding receiving antiplatelet and anticoagulant therapy.

Background & aims: Non-variceal upper gastrointestinal bleeding (NVUGIB) occurs frequently and is associated with a significant morbidity and mortality, especially in patients receiving antiplatelet or anticoagulant therapy (APT and ACT, respectively). We aimed to evaluate adherence to guideline recommendations published by European Society of Gastrointestinal Endoscopy (ESGE).Methods: Retrospective analysis of patients with NVUGIB und prior exposition to APT or ACT at a single university hospital between 01 January 2016 and 31 December 2017.Results: 270 patients were identified (70.4% male, median age 72 years). 6/17 (35.3%) patients receiving APT for primary cardiovascular prophylaxis, 39/71 (54.9%) and 35 (49.3%) patients receiving APT for secondary cardiovascular prophylaxis (using strict and liberal definition, respectively) and 13/25 (52%) patients receiving dual antiplatelet therapy (DAPT) were not managed according to current recommendations. Management of ACT for secondary thromboembolic prophylaxis did not follow guideline recommendations in 59/93 (63.4%) and 34/93 (36.6%) patients (using strict and liberal definition, respectively). 23.7% of patients with NVUGIB were exposed to combined APT and ACT for whom no guideline recommendations exist. Mortality for any reason was twice as high in patients who were not managed according to guideline recommendations (18.8% vs. 8% using strict definition, 20.5% vs. 10.2% using liberal definition), which did not remain significant after adjusting for comorbidities, whereas cardiovascular events were observed at similar rates.Conclusion: A significant number of patients with NVUGIB receiving APT or ACT is not managed according to current ESGE guideline recommendations. Strategies to implement these guidelines into daily practice need to be developed.

Ileal intubation is not associated with higher detection rate of right-sided conventional adenomas and serrated polyps compared to cecal intubation after adjustment for overall adenoma detection rate.

BACKGROUND: High cecal intubation rate (CIR) is associated with significant improved adenoma detection rate (ADR), however, self-reported CIR may be overestimated and inadequate documentation of cecal intubation is associated with a lower polyp detection rate compared to clear documentation. We aimed to investigate if ileal intubation may be associated with higher detection rates (DR) for right-sided conventional adenomas (cAD) and serrated polyps (SP) compared to cecal intubation in a large screening colonoscopy cohort. MATERIAL AND METHODS: Retrospective analysis of individuals ≥50 years with average risk for colorectal cancer (CRC) who underwent screening colonoscopy between 01/01/2012 and 14/12/2016 at a tertiary academic hospital and six community-based private practices. Exclusion criteria were conditions with increased risk for CRC (e.g. inflammatory bowel disease, history of CRC, hereditary cancer syndromes), previous colonoscopy at the same institution, and incomplete procedures. Right-sided colon was defined as caecum and ascending colon. RESULTS: 4.138 individuals were analysed (mean age 62 years, 52.1% female). DR for right-sided cADs and SPs were significantly higher after ileal compared to cecal intubation in univariate (12.5% vs. 6.8%, p < 0.001, and 6.3% vs. 3.3%, p < 0.001), but not in multivariate analysis (OR 1.025, 95%-CI 0.639-1.646, p = 0.918, and OR 0.937, 95%-CI 0.671-1.309, p = 0.704). DRs did not differ between ileal and cecal intubation for endoscopists with ADR ≥25 and < 25%, respectively. ADR ≥25% was significantly associated with ileal intubation (OR 21.862, 95%-CI 18.049-26.481, p < 0.001). CONCLUSION: Ileal intubation may not provide any benefit over cecal intubation concerning the detection of cADs and SPs in the right-sided colon.

Effects of Antibiotics on Gut Microbiota.

The gut microbiota influences essential human functions including digestion, energy metabolism, and inflammation by modulating multiple endocrine, neural, and immune pathways of the host. Its composition and complexity varies markedly across individuals and across different sites of the gut, but provides a certain level of resilience against external perturbation. Short-term antibiotic treatment is able to shift the gut microbiota to long-term alternative dysbiotic states, which may promote the development and aggravation of disease. Common features of post-antibiotic dysbiosis include a loss of taxonomic and functional diversity combined with reduced colonization resistance against invading pathogens, which harbors the danger of antimicrobial resistance. This review summarizes the antibiotic-related changes of the gut microbiota and potential consequences in health and disease.

Impact of (intestinal) LAL deficiency on lipid metabolism and macrophage infiltration.

OBJECTIVE: To date, the only enzyme known to be responsible for the hydrolysis of cholesteryl esters and triacylglycerols in the lysosome at acidic pH is lysosomal acid lipase (LAL). Lipid malabsorption in the small intestine (SI), accompanied by macrophage infiltration, is one of the most common pathological features of LAL deficiency. However, the exact role of LAL in intestinal lipid metabolism is still unknown. METHODS: We collected three parts of the SI (duodenum, jejunum, ileum) from mice with a global (LAL KO) or intestine-specific deletion of LAL (iLAL KO) and corresponding controls. RESULTS: We observed infiltration of lipid-associated macrophages into the lamina propria, where neutral lipids accumulate massively in the SI of LAL KO mice. In addition, LAL KO mice absorb less dietary lipids but have accelerated basolateral lipid uptake, secrete fewer chylomicrons, and have increased fecal lipid loss. Inflammatory markers and genes involved in lipid metabolism were overexpressed in the duodenum of old but not in younger LAL KO mice. Despite the significant reduction of LAL activity in enterocytes of enterocyte-specific (iLAL) KO mice, villous morphology, intestinal lipid concentrations, expression of lipid transporters and inflammatory genes, as well as lipoprotein secretion were comparable to control mice. CONCLUSIONS: We conclude that loss of LAL only in enterocytes is insufficient to cause lipid deposition in the SI, suggesting that infiltrating macrophages are the key players in this process.