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Background and aims: The anticoagulants, unfractionated heparin and low-molecular-weight heparin, demonstrated anti-inflammatory effects in animal models and in humans. Because of its dual effects, high-dose heparin was proposed as a therapeutic modality for ulcerative colitis. We investigated whether a low dose of low-molecular-weight heparin—enoxaparin (Clexane, Rhone-Poulenc Rorer, France)—ameliorates the inflammatory response in two models of experimental colitis. Methods: Colitis was induced in rats by intrarectal administration of dinitrobenzene sulphonic acid. Enoxaparin (40, 80 and 200 μg/kg) or unfractionated heparin (100, 200 and 400 U/kg) were administered subcutaneously immediately after the induction of damage. Enoxaparin, 80 μg/kg, was also administered after induction of colitis by intrarectal administration of iodoacetamide. Rats were sacrificed 1, 3 or 7 days after induction of injury. Colonic damage was assessed macroscopically and histologically. Mucosal prostaglandin E2 generation, myeloperoxidase and nitric oxide synthase activities and tumour necrosis factor-α levels in blood were determined. Results: Enoxaparin and heparin significantly ameliorated the severity of dinitrobenzene sulphonic acid- and iodoacetamide-induced colitis as demonstrated by a decrease in mucosal lesion area, colonic weight and mucosal myeloperoxidase and nitric oxide synthase activities. The dose–response curve had a bell-shaped configuration: enoxaparin, 80 μg/kg, and unfractionated heparin, 200 U/kg, were the optimal doses. Conclusions: Low-dose enoxaparin and unfractionated heparin ameliorate the severity of experimental colitis. This effect is related to their anti-inflammatory rather than anticoagulant properties.

Ulcerative colitis is a chronic inflammatory bowel disorder of unknown etiology. Treatment of flare-ups is based on mesalamine and steroids. Treatment of moderate to severe ulcerative colitis with high-dose heparin and low-molecular-weight heparin was reported. The mechanism was assumed to be a combination of anti-coagulant and anti-inflammatory effects. Low-molecular-weight heparin is better and safer than unfractionated heparin. Studies of low-dose low-molecular-weight heparin in experimental models of inflammation and in inflammatory diseases demonstrated a beneficial effect. Our aim in this study was to evaluate the effect of low-dose, low-molecular-weight heparin in active ulcerative colitis. Twelve patients with flare-ups of colitis were prospectively enrolled. Subcutaneous injections of 5-mg enoxaparin were administered at weekly intervals for 12 weeks. Mesalamine doses remained unchanged. Clinical, laboratory, endoscopic, histologic, and quality-of-life scores were evaluated at the beginning and end of the study. Ten patients completed the study. Mean age was 40.1; the female-male ratio was 7:3. Mean Mayo scores were 9.0 +/- 0.94 at baseline and 3.4 +/- 2.0 at the end of the study (P = 0.0001). Endoscopic scores decreased from 2.2 +/- 0.4 to 1.2 +/- 1.0 (P = 0.049) and in 7 of 10 patients extent of disease shortened. A significant increase in IBDQL scores from 135.7 +/- 37.17 to 179.6 +/- 45.15 points was demonstrated (P = 0.0117). Adverse events were one hospitalization due to abdominal pain, arthralgia (1), transient peripheral edema (1), and elevation of alkaline phosphatase (1). During follow-up, one patient required colectomy and another experienced an exacerbation. In conclusion, low-dose low-molecular-weight heparin once a week, combined with mesalamine, may be an effective therapy for active ulcerative colitis. It may delay or preclude the need for steroid treatment. Controlled studies to evaluate efficacy are needed.

BACKGROUND Pouchitis may develop in patients with ulcerative colitis undergoing pouch surgery. We aimed to evaluate the de novo inflammation developing in the ileal pouch, hypothesizing that it may be similar to ileitis in Crohn's disease (CD). METHODS Patients with ulcerative colitis pouch were prospectively recruited, stratified according to disease behavior into normal pouch, chronic pouchitis, and Crohn's-like disease of the pouch groups, and compared with controls. Gene expression analysis was performed using microarrays, validated by real-time polymerase chain reaction. Gene ontology and clustering were evaluated using bioinformatic tools. RESULTS Sixty-six subjects were recruited. Although in ulcerative colitis ileum there were no significant gene expression alterations, patients with normal pouch had 168 significant alterations (fold change ≥ 2, corrected P ≤ 0.05). In chronic pouchitis and Crohn's-like disease of the pouch, 490 and 1152 alterations were detected, respectively. High degree of overlap in gene expression alterations between the pouch subgroups was demonstrated. The magnitude of change correlated with pouch disease behavior. Gene expression profiles were more reflective of disease behavior compared with inflammatory indices. CD ileitis had 358 alterations, with a 90% overlap with pouchitis. Gene ontology analyses revealed multiple biological processes associated with pouch inflammation, including response to chemical stimulus, small molecule metabolic and immune system processes, and specific infection-related pathways such as Staphylococcus aureus, leishmaniasis, and tuberculosis. CONCLUSIONS Gene alterations in pouch inflammation and CD overlap, suggesting that inflammatory bowel diseases is a spectrum, rather than distinct diseases. Pouchitis may serve as a model of CD. The novel pathways associated with inflammatory bowel diseases may decipher pathophysiology and suggest targets for intervention.

Background Intraductal papillary mucinous neoplasms (IPMN) represent a spectrum of tumors that range from low-grade (LG) dysplastic tumors to invasive cancer. Identification of IPMN at high risk for malignant transformation is important for the prevention and early treatment of pancreatic cancer. The roles of microRNA expression in the development of IPMN have not been extensively evaluated. Methods Expression patterns of 846 human microRNAs (miRNAs) was analyzed using microRNA microarray in 55 tissues, including LG IPMN (n = 10), moderate-grade (MG) IPMN (n = 5), high-grade (HG) IPMN (n = 5), invasive cancer with IPMN (IPMC; n = 10), pancreatic ductal adenocarcinoma without IPMN (PDA; n = 5), LG IPMN extracted from specimens that contain IPMC (LG_Ca; n = 10), and normal pancreatic tissues (n = 10). Results Fourteen miRNAs were differentially expressed in all IPMN tissues compared with normal pancreatic tissue. Expression level of 3 miRNAs was proportional to dysplasia level. Hierarchical clustering demonstrated grouping of 2 IPMN subgroups: LG and MG IPMN verses HG IPMN and IPMC. Expression of 15 miRNAs was significantly different between these groups. LG_Ca tissues clustered with the HG IPMC group, and 12 miRNAs were differentially expressed in LG_Ca, HG lesions, and IPMC compared with LG lesions. The expression patterns of selected miRNAs were validated using quantitative reverse-transcription real-time polymerase chain reaction. Hierarchical clustering demonstrated microRNA expression profile in IPMC was significantly different from PDA, suggesting that different pathways are involved in these cancer types. Conclusion This study demonstrates that miRNAs are involved in the development and progression of IPMN. We identified potential targets for diagnosis, prognostication, and treatment of IPMN.

Clinical features usually initiate evaluation for Lynch Syndrome (LS) but some colorectal cancer (CRC) histopathology findings are compatible with high microsatellite instability (MSI-H) that also occurs in LS. This led to the suggestion that pathologists request MSI analysis, which is an expensive addition to routine histology. We aimed to see if a Gastrointestinal Pathologist could identify MSI-H features with reproducibility and high (95%) specificity (MSI-H 95%). Histopathology of all CRCs received during 2005 and 4 MSI-H controls were scored using 2 published methods, “MsScore” and “PathScore”. MSI analysis was performed on CRCs scored by either method as probable MSI-H 95% and results compared. To examine reproducibility of histopathology, 100 coded slides, including 25 scored MSI-H 95% and 75 scored low, were re-examined to now identify those needing MSI analysis. Costs were evaluated for identifying MSI-H with or without scoring. All 227 CRCs were scored for possible MSI-H 95%; 24 had high scores and MSI analysis. DNA analysis proved 14 MSI-H, PathScore identified 13 (95%), MsPath identified 9 (64%), histopathology alone identified 7 (50%). Reproducibility for identifying histopathology characteristics of MSI-H at re-examination, without scoring, was “moderate agreement” (Kappa statistic = 0.4615). Costs for identifying MSI-H by PathScore were the lowest, $436/identification. Conclusions; PathScore identified the most proven MSI-H CRCs at lowest cost and even an experienced gastrointestinal pathologist has difficulties identify MSI-H without scoring. So, scoring can be facilitated by a computerized evaluation form for routine CRC histology, prompting score computation and recommendation for MSI analysis with high specificity.

Background Colorectal-cancer (CRC) research has greatly benefited from the availability of small animal tumor models. Spontaneous and chemically-induced CRC models are widely used yet limited in their resemblance to human disease and are often prolonged, not accurately repetitive, and associated with inflammatory side effects. In-situ murine or human tumor implantation in the gastrointestinal tract of mice is extremely challenging, and limited by inter-animal variability and procedure-related complications and mortality. As a result, in frequent studies CRC is implanted in distal sites, most commonly the subcutaneous region, an approach that is greatly limited by the absence of normal gastrointestinal tumor milieu and has substantial effects on tumor development. Aims In this study we aimed to develop a well-tolerated repetitive tool to study CRC in small animals by adapting the murine colonoscopy system to serve as a platform for colonic sub-mucosal orthotopic implantation of human and murine CRC tumor cells. Results We report the establishment of a novel small-animal CRC model that is minimally invasive, rapid, well-tolerated, highly reproducible, and confers precise control of tumor number, location and growth rate. Moreover, we show that this model uniquely allows the side-by-side induction of distinct genetically manipulated tumors, enabling the mechanistic study of tumor interaction and cross-talk within the native intestinal microenvironment. Conclusions Employment of this new approach may represent a major technical advance for the in-vivo study of CRC.

Objective: It was the aim of this study to evaluate the number of 2 lymphoid subpopulations, CD8+ cells and FOXP3+, in the duodenum mucosa from pediatric celiac patients. Methods: Tissue sections prepared from paraffin-embedded biopsies of the descending duodenum of 61 celiac patients with Marsh grade 1 (M1), M2 and M3 disease and biopsies from 21 age-matched non-celiac (NC) patients were immunohistostained with anti-CD8 or FOXP3 antibodies. Results: The histological Marsh grade correlated with the mean number of FOXP3+ cells in the lamina propria (LP) mucosa (8.9 ± 1.1, 6.8 ± 2.4, 24.5 ± 2.6 and 31.1 ± 2.8 for NC, M1, M2 and M3 biopsies, respectively; p < 0.001). Using a cutoff point of 15 cells, 95% of NC and 88% of M1 biopsies had a mean of + cells compared with 14% for M2 and 13% for M3 biopsies. The number of FOXP3+ cells in the epithelial mucosa also correlated with transglutaminase type 2 serum levels from the celiac patients. Unlike the FOXP3+ cells, CD8+ lymphocytes were present in both LP and surface epithelial mucosa and significantly different only in the LP mucosa of the M2 and M3 groups. Conclusion: The number of FOXP3+ cells is substantially increased in the mucosa of celiac patients at advanced stages. Characterization of the activity of these cells in celiac and in other inflammatory bowel diseases will enable us to understand the significance of these cells in celiac disease.

Background: Chemokines regulate the pathways that restrict homing of specific subsets of immune cells, and thereby fine tune the immune response at specific lymphoid and peripheral tissues. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. Previously, we demonstrated that pM levels of CCL2 dramatically inhibit migration of T cells. The aim was to test whether subphysiological doses of CCL2 can ameliorate murine colitis and inflammation-induced colorectal cancer. Methods: TNBS (2,4,6 trinitrobenzene sulfonic acid) colitis and dextran sodium sulfate (DSS) colitis were induced in Balb/c and C57BL/6 mice, respectively. Mice were treated daily with intraperitoneal CCL2 injections. Disease activity was assessed clinically, histologically, and by measuring inflammatory cytokine levels. In addition, an inflammatory cancer model was induced by azoxymethane-DSS (AOM-DSS) in Balb/c mice. Mice were treated daily with CCL2 for 11 weeks and then assessed for number of tumors in the colons. Results: Daily administration of CCL2 (60–120 ng) significantly decreased the development of TNBS- and DSS-induced colitis. In a DSS-AOM model, CCL2-treated mice developed significantly fewer tumors (P < 0.005) at 11 weeks. Chronic inflammation in the CCL2-treated mice was significantly less pronounced as compared to phosphate-buffered saline-treated mice. Conclusions: Administration of pM levels of CCL2 significantly inhibits migration of T cells in amelioration of TNBS and DSS colitis and inhibits development of colorectal cancer in an AOM-DSS colitis model in mice. Thus, pM levels of CCL2 may be clinically beneficial as an antiinflammatory agent in IBD. (Inflamm Bowel Dis 2010)

Preoperative diagnosis of malignancy within intraductal papillary mucinous neoplasm of the pancreas (IPMN) solely by clinical or radiological findings is not always possible. We sought a correlation between preoperative clinico-radiological findings and outcome. A prospective database of pancreatic resections for IPMN (2002–2008) and a retrospective pathological revision of all pancreatic cancer specimens (1995–2001) were analyzed. The patients were grouped into asymptomatic with preoperative diagnosis of IPMN (group 1), symptomatic with a preoperative diagnosis of IPMN (group 2), and those with a preoperative diagnosis of pancreatic cancer whose specimen revealed a background of IPMN (group 3). The groups were compared for demographics, clinical presentation, pathological findings, and outcome. Of the 62 patients with IPMN, 19 were in group 1, 23 in group 2, and 20 in group 3. Their median age (range) was 65.6 (46–80), 67 (50–84), and 73.4 (57–86) years, respectively. The clinical presentation for groups 2 and 3 included abdominal pain (56% vs. 32 %), weight loss (8% vs. 52%), obstructive jaundice (4% vs. 57%), pancreatitis (22% and 5%), and new onset of diabetes (14% and 44%). Invasive cancer was found in one patient in group 1 (5.2%), two patients in group 2 (8.7%), and all patients in group 3. IPMN was present in 23 of 217 (10.6%) of all resected pancreatic cancer specimens. Five year survival for patients with invasive disease was 47% and 92% for patients with noninvasive disease (mean follow-up 37.6 months). Benign IPMN can usually be differentiated from adenocarcinoma preoperatively. The clinical presentation is highly indicative of disease course.

Low 5-fluorouracil (5-FU) concentrations cause a significant increase in DNA synthesis in mitogen-activated human lymphocytes.We explored 2.5 microM 5-FU-induced DNA synthesis by testing 5-FU activity in hypoxanthine-aminopterin-thymidine (HAT)-containing medium, and its effect on thymidylate synthase (TS) activity and CD25 expression in interleukin (IL)-2-activated human peripheral blood mononuclear cells (PBMCs) and the combined effects with prostaglandin E(2) (PGE(2)) and transforming growth factor (TGF)-beta3.The co-stimulatory effect of 2.5 microM 5-FU on DNA synthesis was abrogated in HAT-cultured medium. 5-FU substantially reduced TS activity by 50% in IL-2-activated PBMCs. 5-FU combined with TGF-beta3 and PGE(2) did not alter their inhibitory effects on IL-2-activated natural killer cell cytotoxicity, but substantially affected increased DNA synthesis of cells cultured in IL-2 and co-cultured with 10 ng/ml TGF-beta3 and 10 microM PGE(2).Low 5-FU concentrations increase DNA synthesis in lymphocytes and exert a co-stimulatory activity on TGF-beta3 and PGE(2) modulation of IL-2-activated lymphocytes.

Studies on cancer patients undergoing chemotherapy have shown inhibitory effects of anticancer drugs on certain immune activities.The in vitro effect of 5-(FU) fluorouracil was studied on both lymphocyte proliferation and natural killer (NK) cell antitumor cytotoxicity following incubation of peripheral mononuclear cells (PBMCs) from healthy donors with interleukin (IL)-2, phytohemagglutinin A (PHA) and pokeweed mitogen (PWM).Activation of PBMCs with IL-2, PHA and PWM in the presence of 250 and 2500 microM of 5-FU caused a marked decrease in both the induction of activated natural killer (ANK) cell cytotoxic activity and DNA synthesis, while 2.5 microM increased DNA synthesis by 195%, 58% and 222% for IL-2, PHA and PWM, respectively, more than cells cultured without the drug. No effect of 5-FU was noted on mature ANK cells.5-FU exhibits diverse effects on lymphocyte proliferation and on the generation of ANK antitumor cytotoxic activity.

Quality assurance has become an integral part of surgical pathology. Despite the development of interdisciplinary quality systems, however, the means for objective analysis in surgical pathology are limited. Immunohistostaining is a multi-factorial procedure that depends on the quality of reagents and antibodies employed in the process and on technical methodology. In the present study, we aim to establish a straightforward procedure for objective quality evaluation of the components involved in immunohistostaining. The quality of two of these components, the primary antibody and the automated staining device, was assessed by employing each component from two different sources, one serving as the test substance and the second as the reference. Assessment was performed by at least two pathologists in a blinded fashion using pre-established quality criteria and scores. The quality analysis of two automated devices revealed a significant difference between the reference and tested devices (3.5+/-1.7 and 4.2+/-1.5, respectively, P0.05), while the analysis of two selected antibodies did not reveal any statistical difference. The described method provided objective quality assessment of selected components affecting immunohistostaining by elaborating numeric values that enabled statistical analysis. This approach is applicable to any given component in various surgical pathology procedures.

Objective: Previous studies have demonstrated that CYP2D6 polymorphism is associated with liver cirrhosis. The aim of the present study was to find out whether CYP2D6 n 4, the poor metabolizer allele can predict fibrosis progression rate. Methods: Seventy-five Caucasian patients with chronic hepatitis C infection were recruited. They were divided into two groups, 'fast fibrosers' and 'slow fibrosers', according to Poynard's fibrosis progression curves. Sixty-two patients underwent liver biopsy. Twenty healthy neonates were included as control population. DNA was extracted from peripheral blood and CYP2D6 n 4 was tested by polymer chain reaction using fluorescent hybridization probes in a lightCycler instrument. Results: Forty-two patients were classified as 'fast fibrosers' and 33 patients as 'slow fibrosers'. The frequency of CYP2D6 n 4 allele in the 'fast fibrosers' (34.5%) was significantly higher compared with the 'slow fibrosers' (15%) (P- value 5 0.007). There was no significant difference between the frequency of CYP2D6 n 4 in the 'slow fibrosers' (15%) compared with the controls (12.5%). Carrier state of CYP2D6 n 4 was the only covariate that was significantly positively correlated with fast progression to cirrhosis (odds ratio 5 6.5, P 5 0.01). Conclusion: This study indicates for the first time that CYP2D6 genotype might be a significant predictor of liver fibrosis progression rate in chronic hepatitis C patients.

In 1997, hereditary mixed polyposis syndrome (HMPS) was described in an Ashkenazi pedigree having colorectal polyps with mixed histology and risk for colorectal cancer (CRC). The mutation is now localized to 15q13–14. Since 1980, compliant relatives of an HMPS family were seen annually, tested genetically, and had colonoscopy offered every 1 to 2 yr from age 20 yr. The Israeli pedigree has 37 members (17 clinically affected by CRC or polyps), and seven of 13 available relatives entered our screening program. The others, followed-up elsewhere, provided clinical information. Half of our screened group had rectal bleeding; others were asymptomatic. Colonoscopy, performed a mean of four times, identified polyps in all seven patients (mean age 28 yr). Polyps were removed and included juvenile adenomas, mixed juvenile adenomas, hyperplastic polyps, mixed hyperplastic adenomas, serrated adenomas, and tubular adenomas. None of our screened patients developed CRC or extracolonic neoplasia. Linkage analysis localized their mutation to 15q13–14. This high-penetrance founder mutation so far is described only in Ashkenazim. The CRC pathway seems to be through juvenile and hyperplastic polyps. Mutation identification will aid screening for and evaluation of HMPS prevalence in Jewish and non-Jewish populations. Meanwhile, a cancer pedigree and correct classification of polyps will identify HMPS families. They require early and frequent colonoscopy, polypectomy, and elective extensive colectomy when indicated.

Familial juvenile polyposis (JP) is an uncommon genetic disorder that, if untreated, can lead to gastrointestinal cancer. To evaluate familial JP prevalence, phenotypic manifestations, causative mutations, treatment and compliance for diagnosis and follow-up in our registry. Since 1993 our familial JP patients were registered, followed-up before and/or after surgery and their families encouraged to have mutation analysis, endoscopic screening and treatment. Ten pedigrees were identified, all Jewish, but only one was Ashkenazi, six were Sepharadi and three were Oriental; the only mutation found was BMPR1A in two of six pedigrees examined. Of 139 first-degree relatives at risk for JP, 62 (45%) had JP or cancer; 56 (40.3%) were available for follow-up and 35 entered the registry. Of these, 71% reported rectal bleeding, 40% had20 colonic polyps, 31% had 20-100 polyps; 2 had100 gastric polyps. Cancer occurred in 22.9% (6 colonic, 2 gastric) before familial JP diagnosis or during follow-up elsewhere or non-compliance for follow-up; however, 1 gastric cancer developed during our treatment. In 46% the initial clinical-pathological diagnosis was incorrect. Compliance for evaluation and follow-up of pedigree members and individual familial JP patients was inadequate in 20% and 26%, respectively. Familial JP does not occur in the Israeli Ashkenazi Jewish population at the expected proportion; it is often misdiagnosed and is inadequately recognized in Israeli non-Jews. Mutations were identified in only a minority of pedigrees despite comprehensive screening. The inadequate compliance for screening and follow-up needs to be addressed by educating the public, health care workers and health insurances.

based on the degree of active (polymorphonuclear) and chronic (mononuclear) infiltrates (1-normal, 5-massive infiltrate). Gene expression analysis was performed using microarrays, and validated by real-time PCR. Gene ontology and clustering were evaluated using bioinformatic tools. Results: Thirty six subjects [7 NP, 15 pouchitis (10 CP, 5 CLDP) and 14 NC] were recruited. Significant differences of histopathology scores within the pouch were noticed: median activity scores: 1/5 NP, 2/5 CP, 4/5 CLDP (P=0.001), median chronicity scores 2/ 5 NP, 3/5 CP, 3/5 CLDP (P=0.015). Histopathological differences in the proximal ileum were less pronounced. Nonetheless, significant (fold change ≥2, corrected P≤ 0.05) molecular alterations were detected in the normal appearing proximal ileum of all pouch groups compared with NC: NP (n=9), CP (n=80) and CLDP (n=230). DUOX2 alteration magnitude in the proximal ileum was highest: an increase of 6.0, 9.8 and 21.7 fold change in NP, CP, CLDP respectively, followed by MMP1 and SLC6A14. Moreover, gene alterations in the proximal ileum overlapped with those observed within the pouch: 76% and 97% overlap in CP and CLDP, respectively. Gene ontology analysis for proximal ileal alterations revealed association with multiple biological processes including active and anion transmembrane transporter activity and metallopeptidase activity. Conclusions: Significant gene expression alterations were detected not only within pouches, but also in the proximal ileum. Alterations in the pouch and the proximal ileum were comparable. These findings may suggest that the inflammatory processes occurring in pouch patients are not limited to the surgically manipulated region (the pouch) but rather extend to the proximal ileum, potentially exposing it to further inflammation.

The decrease in glomerular filtration rate that is characteristic of sepsis has been shown to result from the local glomerular inhibition of endothelial nitric oxide synthase (NOS) by nitric oxide (NO) generated from the inducible isoform of NOS (iNOS). iNOS activation depends on de novo synthesis of both RNA and protein. Therefore it is assumed that several hours are required for its full activation. Yet the renal hemodynamic response in sepsis has been documented as early as 60 minutes after lipopolysaccharide (LPS) administration. Experiments were designed to determine the time course of LPS-induced glomerular iNOS mRNA expression and activity in rats. Rats were treated with LPS (2 mg/kg body weight IP ). Kidneys were removed after 1, 2, 4, 6, and 16 hours. Glomeruli were isolated and incubated. Nitric oxide generation was measured with a Griess assay, and iNOS mRNA was studied by reverse transcriptase–polymerase chain reaction. Similar time course experiments were repeated in glomeruli isolated from normal rats and exposed to LPS in vitro. A significant increase in iNOS mRNA expression was evident as early as 60 minutes after both in vivo and in vitro administration of LPS. The quantity of iNOS mRNA reached its peak between 2 to 4 hours after administration and declined to baseline levels after 16 hours. Immunohistochemical studies were remarkable for a significant increase in the staining for iNOS in glomeruli 2 hours after the in vivo administration of LPS. Plasma nitric oxide concentration after the in vivo administration of LPS increased from a baseline level of 11.25 ± 0.8 μmol/L to a peak level of 62.9 ± 3.8 μmol/L (P

Background Current strategies for follow up of murine models of liver disease are flawed by inability to continuously monitor disease progression in the tissue level, and necessitate sacrifice of animals for tissue sampling. Aims In this study we aimed at developing a safe repetitive tool for sampling livers in vivo, by utilization of a miniaturized endoscopy system for laparoscopic liver biopsies and for injection of tumor cells into livers. Results We report the development of a protocol for murine laparoscopy that allows repeated visualization of murine intra-abdominal organs. The system enables safe and repeated liver biopsies in mice and rats, yielding adequate tissue for histological staining and RNA extraction. In addition, injection of tumor cells into livers facilitates under-vision implantation of hepatic tumors in liver, followed by visualization of tumor growth. Conclusions Murine laparoscopy may be employed as a novel imaging modality for continuous assessment and manipulation of chronic liver disease models.

Liver fibrosis is characterized by the excessive accumulation of extracellular matrix (ECM) proteins and enzymes, especially fibrillary collagens, and represents a major cause of morbidity and mortality worldwide. Lysyl oxidases (LOXs) drive covalent crosslinking of collagen fibers, thereby promoting stabilization and accumulation of liver fibrosis while limiting its resolution. Here we show in a carbon tetrachloride (CCl4)-induced liver fibrosis murine model that treatment with a novel anti-lysyl oxidase like 2 (LOXL2) neutralizing antibody, which targets extracellular LOXL2, significantly improves fibrosis resolution. LOXL2 inhibition following the onset of fibrosis accelerated and augmented collagen degradation. This was accompanied by increased localization of reparative monocyte-derived macrophages (MoMFs) in the proximity of fibrotic fibers and their representation in the liver. These cells secreted collagenolytic matrix metalloproteinases (MMPs) and, in particular, the membrane-bound MT1-MMP (MMP-14) collagenase. Inducible and selective ablation of infiltrating MoMFs negated the increased “on-fiber” accumulation of MMP-14-expressing MoMFs and the accelerated collagenolytic activity observed in the anti-LOXL2-treated mice. Many studies of liver fibrosis focus on preventing the progression of the fibrotic process. In contrast, the therapeutic mechanism of LOXL2 inhibition presented herein aims at reversing existing fibrosis and facilitating endogenous liver regeneration by paving the way for collagenolytic macrophages.