Inflamed Regions Research Articles

Transcriptional modulation of pattern recognition receptors in acute colitis in mice

Pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), contribute to the development of intestinal inflammatory diseases, like inflammatory bowel disease (IBD). Supporting investigations of the underlying mechanisms of IBD, this study provides an extensive PRR expression survey together with T-cell associated factors along the murine colon during experimental colitis. 8–12 week-old C57BL/6 mice were treated with dextran sodium sulfate (DSS) to induce colitis. The mRNA expression levels of Tlr1–9, Nod1, Nod2, T cell subset-associated master transcription factors and cytokines were determined using qPCR. The expression of TLR2, 4, 5 and 6 was determined with immunohistochemistry. Th1 and Th17 associated responses were quantified in the mesenteric lymph nodes (mLNs) using flow cytometry. In DSS treated mice, the mRNA expression of the majority of PRRs was increased relative to healthy controls and correlated with the degree of inflammation. The exceptions were Tlr1 and Tlr5, which displayed unchanged and down-regulated transcription, respectively. Furthermore, in healthy animals, there was increased transcription of Tlr2, 3 and 5 near the caecum as opposed the region near the rectum. Within the inflamed regions, the mRNA expression of Th1-, Th17- and regulatory T-cell associated cytokines was enhanced, while there was no change for Th2-associated cytokines. In agreement with the mRNA expression, enhanced IFNγ and IL-17 producing cells were observed in stimulated mLNs. This study provides an extensive expression survey of PRRs along the colon during the acute colitis and shows that the induced inflammation is characterized by a Th1- and IL-17 mediated cytokine response.

Changes in the Expression of Smooth Muscle Contractile Proteins in TNBS- and DSS-Induced Colitis in Mice

Thin filament-associated proteins such as calponin, caldesmon, tropomyosin, and smoothelin are thought to regulate acto-myosin interaction and thus, muscle contraction. However, the effect of inflammation on the expression of thin filament-associated proteins is not known. The aim of the present study is to determine the changes in the expression of calponin, caldesmon, tropomyosin, and smoothelin in colonic smooth muscle from trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulphate (DSS)-induced colitis in mice. Expression of h-caldesmon, h2-calponin, α-tropomyosin, and smoothelin-A was measured by qRT-PCR and Western blot. Contraction in response to acetylcholine in dispersed muscle cells was measured by scanning micrometry. mRNA and protein expression of α-actin, h2-calponin, h-caldesmon, smoothelin, and α-tropomyosin in colonic muscle strips from mice with TNBS- or DSS-induced colitis was significantly increased compared to control animals. Contraction in response to acetylcholine was significantly decreased in muscle cells isolated from inflamed regions of TNBS- or DSS-treated mice compared to control mice. Our results show that increase in the expression of thin filament-associated contractile proteins, which inhibit acto-myosin interaction, could contribute to decrease in smooth muscle contraction in inflammation.

Budesonide-loaded nanostructured lipid carriers reduce inflammation in murine DSS-induced colitis

The challenge for the treatment of inflammatory bowel disease (IBD) is the delivery of the drug to the site of inflammation. Because nanoparticles have the ability to accumulate in inflamed regions, the aim of the present study was to evaluate nanostructured lipid carriers (NLCs) as nanoparticulate drug delivery systems for the treatment of IBD. Budesonide (BDS) was chosen as a candidate anti-inflammatory drug. BDS-loaded NLCs (BDS-NLC) produced by high-pressure homogenization had a size of 200 nm and a negative zeta potential. BDS-NLCs reduced the TNF-α secretion by activated macrophages (J774 cells). BDS-NLCs were more active in a murine model of dextran sulfate-induced colitis when compared with Blank-NLCs or a BDS suspension: BDS-NLCs decreased neutrophil infiltration, decreased the levels of the pro-inflammatory cytokines IL-1β and TNF-α in the colon and improved the histological scores of the colons. These data suggest that NLCs could be a promising alternative to polymeric nanoparticles as a targeted drug delivery system for IBD treatment.

Hydrogen peroxide as a signal induced cellular functions of macrophage in oxidative stress (P5038)

Abstract Experiments performed to show that one of the respiratory oxygen species, hydrogen peroxide was an attractant factor for macrophage that consequently affects the phagocytosis of macrophage and gene expression. Results obtained from the present study also show that LPS-induced inflammation would cause hepatocytes to produce hydrogen peroxide which subsequently attract macrophage migration to the inflamed region and promote scavenging function. Furthermore, this reaction is suggestive of macrophage interacts with oxidative stress which promotes the transcription factors activity to cause inflammation responses and suggested hydrogen peroxide act as cellular messenger to affect permeability of calcium ion channel to increase intracellular Ca2+ concentration as a migration messenger

Sa1186 The Pathological Evaluation of Pancreatic Fibrosis Correlates With Apparent Diffusion Coefficient Values Based on Diffusion-Weighted MRI

Background: 99mTc-Heparin provides contrast for localized inflammation in eosinophilic esophagitis (EoE), because themarkedly basic eosinophil granule proteins deposit in inflamed regions of the esophagus and eosinophil granule proteins, such as major basic protein 1 (MBP-1), bind strongly to heparin (Swaminathan GJ, et al., Biochemistry 44 (2005) 141528). In prior experiments, we tested the ability of 99mTc-heparin to bind to cationic eosinophil granule proteins, and we demonstrated that the 99mTc-heparin binds to Macaca monkey tissues coated with MBP-1. We also demonstrated that radiolabeled heparin binds in vitro to esophageal biopsies from patients with EoE. We are now poised to determine whether radiolabeled heparin localizes specifically to the esophagus of patients with eosinophilic esophagitis by having patients swallow the reagent and image its binding by single-photon emission computed tomography (SPECT). Aim: To evaluate the radiation risk from 99mTcheparin by studying the tissue distribution and calculating the radiation dose from orally administered 99mTc-heparin to mice. Method: 99mTc-Heparin (500 μCi/mouse, 15 mg) was administered to mice (C57-B16) by oral gavage. At each time point (0.75, 1.5, 3, 6, 18, and 30 hours), mice were euthanized with CO2 and positioned prone on the scanner bed. SPECT/CT images of mice were acquired by using an Inveon trimodality PET/SPECT/ CT scanner (Siemens Preclinical Solutions, Knoxville, TN). The activity of the harvested organs was measured in a well counter. Results: 99mTc-Heparin was not absorbed significantly through theGI tract into other bodily tissue. The highest radioactivities occurredmainly in stomach, small and large intestine. Discussion: These proof-of-principle experiments clearly show that 99mTc-heparin stays in GI tract and is not strongly absorbed. Furthermore, because heparin is a physiological substance that has long been used in clinical medicine, we believe that it will be well tolerated in our patients. This finding is important because it initiates a new avenue for clinical detection of EoE associated inflammation.

Sa1813 Peyer's Patches Play a Protective Role in NSAIDs-Induced Enteropathy

G A A b st ra ct s in the mucous gel layer and a corresponding decrease in Bacteroidetes when compared to the luminal communities. The pattern of segregation was less apparent in the distal inflamed regions of the individual with ulcerative colitis and family-level analysis confirmed increased mucosa-associated levels of Clostridiaceae and Peptostreptococcaceae. Conclusion: These results support the concept of a spatially-stable, individual-specific cohort of bacteria with a consistent luminal-mucosal segregation. This provides a platform for the programmed assessment of luminal-mucosal ecology, which may add another dimension to our understanding of the propagation of inflammation in inflammatory bowel disease.

Selective In Vivo Visualization of Immune-Cell Infiltration in a Mouse Model of Autoimmune Myocarditis by Fluorine-19 Cardiac Magnetic Resonance

The goal of this study was to characterize the performance of fluorine-19 ((19)F) cardiac magnetic resonance (CMR) for the specific detection of inflammatory cells in a mouse model of myocarditis. Intravenously administered perfluorocarbons are taken up by infiltrating inflammatory cells and can be detected by (19)F-CMR. (19)F-labeled cells should, therefore, generate an exclusive signal at the inflamed regions within the myocardium. Experimental autoimmune myocarditis was induced in BALB/c mice. After intravenous injection of 2×200 µL of a perfluorocarbon on day 19 and 20 (n=9) after immunization, in vivo (19)F-CMR was performed at the peak of myocardial inflammation (day 21). In 5 additional animals, perfluorocarbon combined with FITC (fluorescein isothiocyanate) was administered for postmortem immunofluorescence and flow-cytometry analyses. Control experiments were performed in 9 animals. In vivo (19)F-CMR detected myocardial inflammation in all experimental autoimmune myocarditis-positive animals. Its resolution was sufficient to identify even small inflammatory foci, that is, at the surface of the right ventricle. Postmortem immunohistochemistry and flow cytometry confirmed the presence of perfluorocarbon in macrophages, dendritic cells, and granulocytes, but not in lymphocytes. The myocardial volume of elevated (19)F signal (rs=0.96; P<0.001), the (19)F signal-to-noise ratio (rs=0.92; P<0.001), and the (19)F signal integral (rs=0.96; P<0.001) at day 21 correlated with the histological myocarditis severity score. In vivo (19)F-CMR was successfully used to visualize the inflammation specifically and robustly in experimental autoimmune myocarditis, and thus allowed for an unprecedented insight into the involvement of inflammatory cells in the disease process.

Improved multi B-value diffusion-weighted MRI of the body by simultaneous model estimation and image reconstruction (SMEIR).

Diffusion-weighted MRI images acquired with multiple b-values have the potential to improve diagnostic accuracy by increasing the conspicuity of lesions and inflammatory activity with background suppression. Unfortunately, the inherently low signal-to-noise ratio (SNR) of DW-MRI reduces enthusiasm for using these images for diagnostic purposes. Moreover, lengthy acquisition times limit our ability to improve the quality of multi b-value DW-MRI images by multiple excitations acquisition and signal averaging at each b-value. To offset these limitations, we propose the Simultaneous Model Estimation and Image Reconstruction (SMEIR) for DW-MRI, which substantially improves the quality of multi b-value DW-MRI images without increasing acquisition times. Our model introduces the physiological signal decay model of DW-MRI as a constraint in the reconstruction of the DW-MRI images. An in-vivo experiment using 6 low-quality DW-MRI datasets of a healthy subject showed that SMEIR reconstruction of low-quality data improved SNR by 55% in the liver and by 41% in the kidney without increasing acquisition times. We also demonstrated the clinical impact of our SMEIR reconstruction by increasing the conspicuity of inflamed bowel regions in DW-MRI of 12 patients with Crohn's disease. The contrast-to-noise ratio (CNR) of the inflamed regions in the SMEIR images was higher by 12.6% relative to CNR in the original DW-MRI images.

Stimulation of Cutaneous Low Threshold Mechanoreceptors in Mice After Intracolonic Capsaicin Increases Spinal c-Fos Labeling in an NKCC1-Dependent Fashion

Stimulation of peripheral nociceptors results in increased c-Fos labeling in spinal cord regions associated with nociceptive processing. Accordingly, intracolonic capsaicin, which generates robust secondary (referred) allodynia on the abdomen of mice, also causes an increased spinal c-Fos labeling. In naïve rodents, low intensity innocuous stimulation does not affect c-Fos labeling in spinal nociceptive regions. However, after persistent noxious input, low intensity stimulation of the inflamed region further enhances c-Fos labeling, suggesting that low threshold mechanosensitive fibers gain access to the nociceptive channel after persistent inflammation. We have previously proposed that afferent activity in low threshold sensory fibers activates nociceptive sensory fibers through Na+-K+-Cl− cotransporter 1 (NKCC1) -mediated enhanced primary afferent depolarization. Here, we show that intracolonic capsaicin enhances spinal c-Fos labeling and secondary allodynia in an NKCC1-dependent manner. Furthermore, we demonstrate that gently brushing the abdomen, the region of secondary allodynia, further increased spinal c-Fos levels, an effect that can be prevented by spinal NKCC1 blockade. These findings provide evidence that increased NKCC1 activity contributes to secondary allodynia and that innocuous touch can access the nociceptive channel in part through enhanced NKCC1 activity. PerspectiveWhile touch normally soothes acute pain, we demonstrate that following peripheral inflammation, touch evokes pain (allodynia) through the switching of a normally inhibitory spinal pathway into an excitatory pathway. Activation of low threshold mechanoreceptors activates spinal nociceptive neurons following inflammation-induced enhancement of NKCC1 expression, as measured by spinal c-Fos labeling.

Peritoneal macrophages mediated delivery of chitosan/siRNA nanoparticle to the lesion site in a murine radiation-induced fibrosis model

Background. Radiation-induced fibrosis (RIF) is a dose-limiting complication of cancer radiotherapy and causes serious problems, i.e. restricted tissue flexibility, pain, ulceration or necrosis. Recently, we have successfully treated RIF in a mouse model by intraperitoneal administration of chitosan/siRNA nanoparticles directed towards silencing TNF alpha in local macrophage populations, but the mechanism for the therapeutic effect at the lesion site remains unclear. Methods. Using the same murine RIF model we utilized an optical imaging technique and fluorescence microscopy to investigate the uptake of chitosan/fluorescently labeled siRNA nanoparticles by peritoneal macrophages and their subsequent migration to the inflamed tissue in the RIF model. Results. We observed strong accumulation of the fluorescent signal in the lesion site of the irradiated leg up to 24 hours using the optical imaging system. We further confirm by immunohistochemical staining that Cy3 labeled siRNA resides in macrophages of the irradiated leg. Conclusion. We provide a proof-of-concept for host macrophage trafficking towards the inflamed region in a murine RIF model, which thereby suggests that the chitosan/siRNA nanoparticle may constitute a general treatment for inflammatory diseases using the natural homing potential of macrophages to inflammatory sites.

Effects of p38 Mitogen-Activated Protein Kinase Inhibition on Vascular and Systemic Inflammation in Patients With Atherosclerosis

This study sought to determine the effects of a p38 mitogen-activated protein kinase inhibitor, losmapimod, on vascular inflammation, by (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography imaging. The p38 mitogen-activated protein kinase cascade plays an important role in the initiation and progression of inflammatory diseases, including atherosclerosis. Patients with atherosclerosis on stable statin therapy (n = 99) were randomized to receive losmapimod 7.5 mg once daily (lower dose [LD]), twice daily (higher dose [HD]) or placebo for 84 days. Vascular inflammation was assessed by FDG positron emission tomography/computed tomography imaging of the carotid arteries and aorta; analyses focused on the index vessel (the artery with the highest average maximum tissue-to-background ratio [TBR] at baseline). Serum inflammatory biomarkers and FDG uptake in visceral and subcutaneous fat were also measured. The primary endpoint, change from baseline in average TBR across all segments in the index vessel, was not significantly different between HD and placebo (ΔTBR: -0.04 [95% confidence interval [CI]: -0.14 to +0.06], p = 0.452) or LD and placebo (ΔTBR: -0.02 [95% CI: -0.11 to +0.06], p = 0.579). However, there was a statistically significant reduction in average TBR in active segments (TBR ≥1.6) (HD vs. placebo: ΔTBR: -0.10 [95% CI: -0.19 to -0.02], p = 0.0125; LD vs. placebo: ΔTBR: -0.10 [95% CI: -0.18 to -0.02], p = 0.0194). The probability of a segment being active was also significantly reduced for HD when compared with placebo (OR: 0.57 [95% CI: 0.41 to 0.81], p = 0.002). Within the HD group, reductions were observed in placebo-corrected inflammatory biomarkers including high-sensitivity C-reactive protein (% reduction: -28% [95% CI: -46 to -5], p = 0.023) as well as FDG uptake in visceral fat (ΔSUV: -0.05 [95% CI: -0.09 to -0.01], p = 0.018), but not subcutaneous fat. Despite nonsignificant changes for the primary endpoint of average vessel TBR, HD losmapimod reduced vascular inflammation in the most inflamed regions, concurrent with a reduction in inflammatory biomarkers and FDG uptake in visceral fat. These results suggest a systemic anti-inflammatory effect. (A Study to Evaluate the Effects of 3 Months Dosing With GW856553, as Assessed FDG-PET/CT Imaging; NCT00633022).

Infections with Avian Pathogenic and Fecal Escherichia coli Strains Display Similar Lung Histopathology and Macrophage Apoptosis

The purpose of this study was to compare histopathological changes in the lungs of chickens infected with avian pathogenic (APEC) and avian fecal (Afecal) Escherichia coli strains, and to analyze how the interaction of the bacteria with avian macrophages relates to the outcome of the infection. Chickens were infected intratracheally with three APEC strains, MT78, IMT5155, and UEL17, and one non-pathogenic Afecal strain, IMT5104. The pathogenicity of the strains was assessed by isolating bacteria from lungs, kidneys, and spleens at 24 h post-infection (p.i.). Lungs were examined for histopathological changes at 12, 18, and 24 h p.i. Serial lung sections were stained with hematoxylin and eosin (HE), terminal deoxynucleotidyl dUTP nick end labeling (TUNEL) for detection of apoptotic cells, and an anti-O2 antibody for detection of MT78 and IMT5155. UEL17 and IMT5104 did not cause systemic infections and the extents of lung colonization were two orders of magnitude lower than for the septicemic strains MT78 and IMT5155, yet all four strains caused the same extent of inflammation in the lungs. The inflammation was localized; there were some congested areas next to unaffected areas. Only the inflamed regions became labeled with anti-O2 antibody. TUNEL labeling revealed the presence of apoptotic cells at 12 h p.i in the inflamed regions only, and before any necrotic foci could be seen. The TUNEL-positive cells were very likely dying heterophils, as evidenced by the purulent inflammation. Some of the dying cells observed in avian lungs in situ may also be macrophages, since all four avian E. coli induced caspase 3/7 activation in monolayers of HD11 avian macrophages. In summary, both pathogenic and non-pathogenic fecal strains of avian E. coli produce focal infections in the avian lung, and these are accompanied by inflammation and cell death in the infected areas.

Systemic Infusion of Bone Marrow-Derived Mesenchymal Stem Cells for Treatment of Experimental Colitis in Mice

The anti-inflammatory and reparative properties of mesenchymal stem cells (MSCs) make them a promising tool for treating immune-mediated and inflammatory disorders. However, whether MSCs can be used for treatment of inflammatory bowel disease (IBD) still remains unclear. In this study, a dextran sulfate sodium (DSS)-induced mouse colitis model was used to test the hypothesis that infused bone marrow-derived MSCs could exert anti-inflammatory effects against experimental colitis. DSS-induced colitis mice were injected with 1 × 10(6) MSCs [in phosphate-buffered saline (PBS)] via the tail vein. Control colitis mice received PBS alone. To trace the injected cells in vivo, MSCs were labeled with chloromethyl-benzamidodialkylcarbocyanine (CM-DiI). On day 15 of the experiment, the colon was sectioned and examined for histopathological changes. Pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β] in the inflamed colon were analyzed by real-time reverse-transcription polymerase chain reaction (RT-PCR). Serum values of TNF-α in mice were evaluated quantitatively by enzyme-linked immunosorbent assay (ELISA) analysis. DSS-induced colitis showed symptoms similar to ulcerative colitis in humans, including body weight loss, bloody diarrhea, mucosal ulceration, and shortening of the colon. Bone marrow-derived MSCs significantly ameliorated the clinical and histopathologic severity of DSS colitis compared with non-MSC control. Pro-inflammatory cytokines in both the inflamed colon (TNF-α, IL-1β) and serum (TNF-α) were downregulated in MSC-treated mice in contrast to control. CM-DiI-labeled MSCs accumulated in inflamed regions of the colon, mainly in the submucosa. Systemic infusion of bone marrow-derived MSCs may exert therapeutic efficacy on acute DSS-induced colitis in mice through their anti-inflammatory effects, which demonstrates the feasibility of using bone marrow-derived MSCs to treat IBD.

By-Passing Large Screening Experiments Using Sequencing as a Tool to Identify scFv Fragments Targeting Atherosclerotic Lesions in a Novel In Vivo Phage Display Selection

Atherosclerosis is a chronic, progressive inflammatory disease that may develop into vulnerable lesions leading to thrombosis. To interrogate the molecular components involved in this process, single-chain variable fragments (scFvs) from a semi-synthetic human antibody library were selected on the lesions induced in a rabbit model of atherosclerosis after two rounds of in vivo phage display. Homing Phage-scFvs were isolated from (1) the injured endothelium, (2) the underlying lesional tissue and (3) the cells within the intima. Clones selected on the basis of their redundancy or the presence of key amino acids, as determined by comparing the distribution between the native and the selected libraries, were produced in soluble form, and seven scFvs were shown to specifically target the endothelial cell surface and inflamed intima-related regions of rabbit tissue sections by immunohistology approaches. The staining patterns differed depending on the scFv compartment of origin. This study demonstrates that large-scale scFv binding assays can be replaced by a sequence-based selection of best clones, paving the way for easier use of antibody libraries in in vivo biopanning experiments. Future investigations will be aimed at characterizing the scFv/target couples by mass spectrometry to set the stage for more accurate diagnostic of atherosclerosis and development of therapeutic strategies.

New Human Antibody Fragments Homing to Atherosclerotic Endothelial and Subendothelial Tissues: An in Vivo Phage Display Targeting Human Antibodies Homing to Atherosclerotic Tissues

In vivo phage display selection is a powerful strategy for directly identifying agents that target the vasculature of normal or diseased tissues in living animals. We describe here a new in vivo biopanning strategy in which a human phage single-chain antibody (scFv) library was injected into high-fat diet-fed ApoE(-/-) mice. Extracellular and internalized phage scFvs were selectively recovered from atherosclerotic vascular endothelium and subjacent tissues. After three successive biopanning rounds, a panel of six clones with distinct gene sequences was isolated. Four scFvs produced and purified in soluble form were shown to interact in vitro with a rabbit atheromatous protein extract by time-resolved fluorescence resonance energy transfer and to target the endothelial cell surface and inflamed intima-related regions of rabbit and human tissue sections ex vivo. These new scFvs selected in a mouse model recognized both rabbit and human tissue, underlying the interspecies similarities of the recognized epitopes. By combining immunoprecipitation and mass spectrometry, one of the selected scFvs was shown to recognize carbonic anhydrase II, an up-regulated enzyme involved in resorption of ectopic calcification. These results show that in vivo biopanning selection in hypercholesterolemic animals makes it possible to identify both scFvs homing to atherosclerotic endothelial and subendothelial tissues, and lesion-associated biomarkers. Such scFvs offer promising opportunities in the field of molecular targeting for the treatment of atherosclerosis.

Relationship between pancreatic and/or extrapancreatic lesions and serum IgG and IgG4 levels in IgG4‐related diseases

We aimed to investigate the relationship between the number of involved organs or regions and serum immunoglobulin G (IgG) and immunoglobulin G4 (IgG4) levels. The number of pancreatic and/or extrapancreatic lesions and serum IgG and IgG4 levels were examined by groups in 46 patients with IgG4-related diseases at diagnosis prior to the initiation of steroid treatment: group A (one region involved, n=7), group B (two regions involved, n=11), group C (three regions involved, n=12), group D (four regions involved, n=9) and group E (five to seven regions involved, n=7). Both serum IgG and IgG4 levels increased with the number of inflamed regions. Mean serum IgG levels were 15.11, 18.65, 20.92, 23.29 and 30.98 g/L while the mean IgG4 levels were 3.99, 4.70, 4.70, 9.86 and 16.49 g/L in group A, B, C, D and E, respectively. Regression analysis also suggested that IgG4 was positively correlated with the number of regions involved. Additionally, serum IgG4 was higher in patients with multiple lesions when accompanied by sclerosing sialadenitis. Patients having IgG4-related disease with high serum IgG and IgG4 levels should be systematically examined for involved lesions.

Interleukin-22 Promotes Proliferation of Liver Stem/Progenitor Cells in Mice and Patients With Chronic Hepatitis B Virus Infection

Proliferation of liver stem/progenitor cells (LPCs), which can differentiate into hepatocytes or biliary epithelial cells, is often observed in chronically inflamed regions of liver in patients. We investigated how inflammation might promote proliferation of LPCs. We examined the role of interleukin (IL)-22, a survival factor for hepatocytes, on proliferation of LPCs in patients with chronic hepatitis B virus (HBV) infection and in mice. Proliferation of LPCs in mice was induced by feeding a diet that contained 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Hepatic expression of IL-22 was increased in patients with HBV and correlated with the grade of inflammation and proliferation of LPCs. Mice on the DDC diet that overexpressed an IL-22 transgene specifically in liver (IL-22TG), or that were infected with an IL-22-expressing adenovirus, had increased proliferation of LPCs. Signal transducer and activator of transcription (STAT) 3, a component of the IL-22 signaling pathway, was activated in LPCs isolated from DDC-fed IL-22TG mice. Deletion of STAT3 from livers of IL-22TG mice reduced proliferation of LPCs. In addition, the receptors IL-22R1 and IL-10R2 were detected on epithelial cell adhesion molecule(+)CD45(-) LPCs isolated from DDC-fed wild-type mice. Culture of these cells with IL-22 activated STAT3 and led to cell proliferation, but IL-22 had no effect on proliferation of STAT3-deficient EpCAM(+)CD45(-) LPCs. IL-22 also activated STAT3 and promoted proliferation of cultured BMOL cells (a mouse LPC line). In livers of mice and patients with chronic HBV infection, inflammatory cells produce IL-22, which promotes proliferation of LPCs via STAT3. These findings link inflammation with proliferation of LPCs in patients with HBV infection.

Ficolin 1 Expression is Elevated in the Peripheral Blood Mononuclear Cells of Takayasu’s Vasculitis Patients

Takayasu’s arteritis (TA), a form of vasculitis (angiitis), is a chronic inflammatory disease involving the large blood vessels. This study reports the identification of genes showing increased mRNA levels in peripheral blood mononuclear cells (PBMCs) from TA patients regardless of symptoms or disease activity/inactivity. Of these, mRNA for Ficolin 1 (FCN1) showed a four-fold increase in all eight TA patients examined. Increased FCN1 mRNA levels observed in cDNA microarrays were confirmed by quantitative reverse transcription polymerase chain reaction. Increased FCN1 protein expression was also observed in inflamed regions of the surgical aorta specimens. Moreover, most FCN1-positive cells were also positive for CD68, indicating the presence of monocytic cells, such as macrophages or dendritic cells, which attack infectious agents within the inflamed regions. Taken together, the results suggest that FCN1 mRNA levels in peripheral blood samples may be a diagnostic marker for TA.

Blunting Half of the Double-Edged Sword

See related article, pages 1280–1289 During a myocardial infarction (MI), tissue damage resulting from the ischemia and subsequent reperfusion injury triggers a complex combination of cellular responses,1 much of which is bone marrow–derived. Some of these responses involve a harmful inflammatory reaction to cytokines released by dying cardiomyocytes that can exacerbate the ongoing local structural damage. Other responses are beneficial, for example, the prohealing arm of the inflammatory response that replaces the necrotic and inflamed region with a fibrous scar. Still other beneficial effects are thought to be mediated by mobilized bone marrow cells (BMCs) of multiple lineages that aid in tissue healing.2,3 Much effort has gone into harnessing this endogenous cellular response by harvesting resident or mobilized bone marrow–derived cells and administering them to post-MI hearts,4–7 with the hope that the cells will regenerate myocardium via differentiation2,8 or will preserve at-risk myocardium by actively9 or passively10 releasing paracrine growth factors or secreting exosomes.11,12 However, the aforementioned inflammatory response can cause problems by creating an environment in the post-MI heart that may be inhospitable for naturally attracted and therapeutically administered BMCs alike. Moreover, the MI-induced inflammatory response transitions the BMCs themselves to a more proinflammatory state, interfering with their therapeutic abilities.13 In this issue of Circulation Research , Krishnamurthy and colleagues14 explore naturally occurring mechanisms of dampening the inflammatory response that could potentially augment the efficacy of cell therapy for MI. Their focus is on a particular subpopulation of BMCs, the endothelial progenitor cells (EPCs). These cells, which were originally discovered in rodents, …

Increased density of sympathetic nerve fibers in metabolically activated fat tissue surrounding human synovium and mouse lymph nodes in arthritis

To investigate the density of sympathetic nerve fibers in and the metabolic activation of fat tissue surrounding human synovium in rheumatoid arthritis (RA)/osteoarthritis (OA) and in the draining lymph nodes of arthritic and normal mice. Using immunofluorescence and immunohistochemistry, the density of sympathetic nerve fibers and the presence of nerve repellent factors were investigated. The metabolic activation of fat tissue was estimated by the occurrence of small-vacuole adipocytes, expression of β3-adrenoceptors, and adipose tissue weight. The density of sympathetic nerve fibers was markedly increased in fat tissue surrounding RA synovium compared with that in fat tissue surrounding OA synovium. In adipose tissue adjacent to draining lymph nodes, the density of sympathetic nerve fibers was higher in arthritic mice compared with normal mice. In human synovium and mouse draining lymph nodes, the 2 sympathetic nerve repellent factors, semaphorin 3C and semaphorin 3F, were highly expressed. In arthritic compared with normal mice, the fat tissue around lymph nodes was markedly lighter, adipocytes had more fragmented lipid droplets, and fat tissue demonstrated high expression of β3-adrenoceptors. This study demonstrated an increased density of sympathetic nerve fibers in metabolically activated fat tissue surrounding human RA synovium and the draining lymph nodes of arthritic mice. Because sympathetic neurotransmitters stimulate lipolysis, the repulsion of sympathetic nerve fibers from inflamed regions and their increased occurrence in fat tissue probably represent an adaptive program to support the proinflammatory process by releasing energy-rich substrates.