Sugar and arginine facilitate oral tolerance by ensuring the functionality of tolerogenic immune cell subsets in the intestine.

Although oral tolerance is a critical system in regulating allergic disorders, the mechanisms by which dietary factors regulate the induction and maintenance of oral tolerance remain unclear. To address this, we explored the differentiation and function of various immune cells in the intestinal immune system under fasting and ad libitum-fed conditions before oral ovalbumin (OVA) administration. Fasting mitigated OVA-specific Treg expansion, which is essential for oral tolerance induction. This abnormality mainly resulted from functional defects in the CX3CR1+ cells responsible for the uptake of luminal OVA and reduction of tolerogenic CD103+ dendritic cells. Eventually, fasting impaired the preventive effect of oral OVA administration on asthma and allergic rhinitis development. Specific food ingredients, namely carbohydrates and arginine, were indispensable for oral tolerance induction by activating glycolysis and mTOR signaling. Overall, prior food intake and nutritional signals are critical for maintaining immune homeostasis by inducing tolerance to ingested food antigens.

Sitafloxacin reduces tumor necrosis factor alpha (TNFα) converting enzyme (TACE) phosphorylation and activity to inhibit TNFα release from lipopolysaccharide-stimulated THP-1 cells.

Sepsis is a systemic reaction to an infection and resulting in excessive production of inflammatory cytokines and chemokines. It sometimes results in septic shock. The present study aimed to identify quinolone antibiotics that can reduce tumor necrosis factor alpha (TNFα) production and to elucidate mechanisms underlying inhibition of TNFα production. We identified quinolone antibiotics reduced TNFα production in lipopolysaccharide (LPS)-stimulated THP-1 cells. Sitafloxacin (STFX) is a broad-spectrum antibiotic of the quinolone class. STFX effectively suppressed TNFα production in LPS-stimulated THP-1 cells in a dose-dependent manner and increased extracellular signal-regulated kinase (ERK) phosphorylation. The percentage of intracellular TNFα increased in LPS-stimulated cells with STFX compared with that in LPS-stimulated cells. TNFα converting enzyme (TACE) released TNFα from the cells, and STFX suppressed TACE phosphorylation and activity. To conclude, one of the mechanisms underlying inhibition of TNFα production in LPS-stimulated THP-1 cells treated with STFX is the inhibition of TNFα release from cells via the suppression of TACE phosphorylation and activity. STFX may kill bacteria and suppress inflammation. Therefore, it can be effective for sepsis treatment.

Symbiotic polyamine metabolism regulates epithelial proliferation and macrophage differentiation in the colon.

Intestinal microbiota-derived metabolites have biological importance for the host. Polyamines, such as putrescine and spermidine, are produced by the intestinal microbiota and regulate multiple biological processes. Increased colonic luminal polyamines promote longevity in mice. However, no direct evidence has shown that microbial polyamines are incorporated into host cells to regulate cellular responses. Here, we show that microbial polyamines reinforce colonic epithelial proliferation and regulate macrophage differentiation. Colonisation by wild-type, but not polyamine biosynthesis-deficient, Escherichia coli in germ-free mice raises intracellular polyamine levels in colonocytes, accelerating epithelial renewal. Commensal bacterium-derived putrescine increases the abundance of anti-inflammatory macrophages in the colon. The bacterial polyamines ameliorate symptoms of dextran sulfate sodium-induced colitis in mice. These effects mainly result from enhanced hypusination of eukaryotic initiation translation factor. We conclude that bacterial putrescine functions as a substrate for symbiotic metabolism and is further absorbed and metabolised by the host, thus helping maintain mucosal homoeostasis in the intestine.

Mast cells play role in wound healing through the ZnT2/GPR39/IL-6 axis.

Zinc (Zn) is an essential nutrient and its deficiency causes immunodeficiency and skin disorders. Various cells including mast cells release Zn-containing granules when activated; however, the biological role of the released Zn is currently unclear. Here we report our findings that Zn transporter ZnT2 is required for the release of Zn from mast cells. In addition, we found that Zn and mast cells induce IL-6 production from inflammatory cells such as skin fibroblasts and promote wound healing, a process that involves inflammation. Zn induces the production of a variety of pro-inflammatory cytokines including IL-6 through signaling pathways mediated by the Zn receptor GPR39. Consistent with these findings, wound healing was impaired in mice lacking IL-6 or GPR39. Thus, our results show that Zn and mast cells play a critical role in wound healing through activation of the GPR39/IL-6 signaling axis.

Contribution of Zinc and Zinc Transporters in the Pathogenesis of Inflammatory Bowel Diseases.

Intestinal epithelial cells cover the surface of the intestinal tract. The cells are important for preserving the integrity of the mucosal barriers to protect the host from luminal antigens and pathogens. The mucosal barriers are maintained by the continuous and rapid self-renewal of intestinal epithelial cells. Defects in the self-renewal of these cells are associated with gastrointestinal diseases, including inflammatory bowel diseases and diarrhea. Zinc is an essential trace element for living organisms, and zinc deficiency is closely linked to the impaired mucosal integrity. Recent evidence has shown that zinc transporters contribute to the barrier function of intestinal epithelial cells. In this review, we describe the recent advances in understanding the role of zinc and zinc transporters in the barrier function and homeostasis of intestinal epithelial cells.

Maintenance of Intestinal Epithelial Homeostasis by Zinc Transporters.

Zinc is an essential micronutrient for normal organ function, and dysregulation of zinc metabolism has been implicated in a wide range of diseases. Emerging evidence has revealed that zinc transporters play diverse roles in cellular homeostasis and function by regulating zinc trafficking via organelles or the plasma membrane. In the gastrointestinal tract, zinc deficiency leads to diarrhea and dysfunction of intestinal epithelial cells. Studies also showed that zinc transporters are very important in intestinal epithelial homeostasis. In this review, we describe the physiological roles of zinc transporters in intestinal epithelial functions and relevance of zinc transporters in gastrointestinal diseases.

Regulatory Role of GRK2 in the TLR Signaling-Mediated iNOS Induction Pathway in Microglial Cells.

G protein-coupled receptor kinase 2 (GRK2) is a ubiquitous member of the GRK family that restrains cellular activation by G protein-coupled receptor (GPCR) phosphorylation leading to receptor desensitization and internalization, but has been identified to regulate a variety of signaling molecules, among which may be associated with inflammation. In this study, we attempted to establish the regulatory role of GRK2 in the Toll-like receptor (TLR) signaling pathway for inducible nitric oxide synthase (iNOS) expression in microglial cells. When mouse MG6 cells were stimulated with the TLR4 ligands lipopolysaccharide (LPS) and paclitaxel, we found that interferon regulatory factor 1 (IRF1) protein expression and activation was upregulated, transcription of interferon-ß (IFN-ß) was accelerated, induction/activation of STAT1 and activation of STAT3 were promoted, and subsequently iNOS expression was upregulated. The ablation of GRK2 by small interfering RNAs (siRNAs) not only eliminated TLR4-mediated upregulation of IRF1 protein expression and nuclear translocation but also suppressed the activation of the STAT pathway, resulting in negating the iNOS upregulation. The TLR3-mediated changes in IRF1 and STAT1/3, leading to iNOS induction, were also abrogated by siRNA knockdown of GRK2. Furthermore, transfection of GRK2 siRNA blocked the exogenous IFN-ß supplementation-induced increases in phosphorylation of STAT1 as well as STAT3 and abrogated the augmentation of iNOS expression in the presence of exogenous IFN-ß. Taken together, our results show that GRK2 regulates the activation of IRF1 as well as the activation of the STAT pathway, leading to upregulated transcription of iNOS in activated microglial cells. Modulation of the TLR signaling pathway via GRK2 in microglia may be a novel therapeutic target for treatment of neuroinflammatory disorders.

Anti-inflammatory properties of cilostazol: Its interruption of DNA binding activity of NF-κB from the Toll-like receptor signaling pathways.

Cilostazol, a selective inhibitor of phosphodiesterase type III with anti-platelet, anti-mitogenic, and vasodilating properties, is widely used to treat ischemic symptoms of peripheral vascular disease. Ample evidence has suggested that cilostazol also exhibits an anti-inflammatory effect, but its anti-inflammatory mechanism is not fully understood. Here, we showed that cilostazol specifically inhibited expression of cytokines, which are induced by nuclear factor-κB (NF-κB) activation, in RAW264.7 macrophage cells stimulated with different Toll-like receptor (TLR) ligands. Cilostazol was found to significantly reduce TLR-4 and TLR-3 ligands-stimulated NF-κB transcriptional activity, which was quantified by luciferase reporter assays. However, cilostazol was without effect on IκBα degradation and NF-κB p65 phosphorylation and nuclear translocation after challenge with the TLR-4 ligand lipopolysaccharide (LPS). Cilostazol did not also prevent the LPS-induced increase in phosphorylated levels of the mitogen-activated protein kinase (MAPK) family. On the other hand, using chromatin immunoprecipitation assays, we demonstrated that cilostazol reduced the LPS-induced transcriptional activities of interleukin-6 and tumor necrosis factor-α by preventing the recruitment of NF-κB p65 to these gene promoters. When cilostazol was given to mice by oral gavage daily for 7 days, LPS-induced aberrant pro-inflammatory cytokine production and end-organ tissue injury were significantly reduced. The results of this study suggest that cilostazol is capable of directly interrupting DNA binding activity of NF-κB proteins from the TLR signaling pathways. The therapy to specifically intervene in this pathway may be potentially beneficial for the prevention of different inflammatory disorders.

Role of G protein-coupled receptor kinase 2 in oxidative and nitrosative stress-related neurohistopathological changes in a mouse model of sepsis-associated encephalopathy.

Sepsis-associated encephalopathy (SAE), characterized as diffuse brain dysfunction and neurological manifestations secondary to sepsis, is a common complication in critically ill patients and can give rise to poor outcome, but understanding the molecular basis of this disorder remains a major challenge. Given the emerging role of G protein-coupled receptor 2 (GRK2), first identified as a G protein-coupled receptor (GPCR) regulator, in the regulation of non-G protein-coupled receptor-related molecules contributing to diverse cellular functions and pathology, including inflammation, we tested the hypothesis that GRK2 may be linked to the neuropathogenesis of SAE. When mouse MG6 microglial cells were challenged with lipopolysaccharide (LPS), GRK2 cytosolic expression was highly up-regulated. The ablation of GRK2 by small interfering RNAs (siRNAs) prevented an increase in intracellular reactive oxygen species generation in LPS-stimulated MG6 cells. Furthermore, the LPS-induced up-regulation of inducible nitric-oxide synthase expression and increase in nitric oxide production were negated by GRK2 inhibitor or siRNAs. However, GRK2 inhibition was without effect on overproduction of tumor necrosis factor-α, interleukin (IL)-6, and IL-1ß in LPS-stimulated MG cells. In mice with cecal ligation and puncture-induced sepsis, treatment with GRK2 inhibitor reduced high levels of oxidative and nitrosative stress in the mice brains, where GRK2 expression was up-regulated, alleviated neurohistological damage observed in cerebral cortex sections, and conferred a significant survival advantage to CLP mice. Altogether, these results uncover the novel role for GRK2 in regulating cellular oxidative and nitrosative stress during inflammation and suggest that GRK2 may have a potential as an intriguing therapeutic target to prevent or treat SAE.

Activator Protein-1 Decoy Oligodeoxynucleotide Transfection Is Beneficial in Reducing Organ Injury and Mortality in Septic Mice.

OBJECTIVES: Inflammation and apoptosis are decisive mechanisms for the development of end-organ injury in sepsis. Activator protein-1 may play a key role in regulating expression of harmful genes responsible for the pathophysiology of septic end-organ injury along with the major transcription factor nuclear factor-κB. We investigated whether in vivo introduction of circular dumbbell activator protein-1 decoy oligodeoxynucleotides can provide benefits for reducing septic end-organ injury. DESIGN: Laboratory and animal/cell research. SETTINGS: University research laboratory. SUBJECTS: Male BALB/c mice (8-10 wk old). INTERVENTIONS: Activator protein-1 decoy oligodeoxynucleotides were effectively delivered into tissues of septic mice in vivo by preparing into a complex with atelocollagen given 1 hour after surgery. MATERIALS AND MAIN RESULTS: Polymicrobial sepsis was induced by cecal ligation and puncture in mice. Activator protein-1 decoy oligodeoxynucleotide transfection inhibited abnormal production of proinflammatory and chemotactic cytokines after cecal ligation and puncture. Histopathologic changes in lung, liver, and kidney tissues after cecal ligation and puncture were improved by activator protein-1 decoy oligodeoxynucleotide administration. When activator protein-1 decoy oligodeoxynucleotides were given, apoptosis induction was strikingly suppressed in lungs, livers, kidneys, and spleens of cecal ligation and puncture mice. These beneficial effects of activator protein-1 decoy oligodeoxynucleotides led to a significant survival advantage in mice after cecal ligation and puncture. Apoptotic gene profiling indicated that activator protein-1 activation was involved in the up-regulation of many of proapoptotic and antiapoptotic genes in cecal ligation and puncture-induced sepsis. CONCLUSIONS: Our results indicate a detrimental role of activator protein-1 in the sepsis pathophysiology and the potential usefulness of activator protein-1 decoy oligodeoxynucleotides for the prevention and treatment of septic end-organ failure.

SKL2001 suppresses colon cancer spheroid growth through regulation of the E-cadherin/ß-Catenin complex.

Aberrant activation of Wnt signaling plays a pivotal role in the development of human cancers including colon cancer. Small compounds that regulate Wnt signaling are attractive candidate for the colon cancer therapy. Here, we showed that SKL2001, which has been identified as an activator for Wnt signaling by disrupting the Axin/ß-Catenin complex, negatively regulates growth of colon cancer spheroids cultured in the 3D condition that simulates tumor microenvironment in vivo. SKL2001 inhibited proliferation of colon cancer cells cultured in 3D spheroid and induced them accumulation in the G0/G1 phase of the cell cycle with a reduced c-myc level. To examine the potential of arrested cells to recover, colon cancer spheroids that were treated with SKL2001 were then cultured in the SKL2001-free medium. We found that SKL2001-treated cells were resumed cell cycle progression and proliferated in the SKL2001-free medium. Notably, SKL2001 facilitated round-shape spheroid formation. This was associated with upregulated expressions of E-cadherin and ß-Catenin. These findings suggest that SKL2001 can suppress colon cancer spheroid growth through regulating cell cycle progression and cadherin/catenin mediated cell-cell contact.

Prostacyclin mimetics afford protection against lipopolysaccharide/d-galactosamine-induced acute liver injury in mice.

Prostacyclin (PGI2) serves as a protective, anti-inflammatory mediator and PGI2 mimetics may be useful as a hepatoprotective agent. We examined whether two PGI2 mimetics, ONO-1301 and beraprost, are beneficial in acute liver injury and attempted to delineate the possible mechanism underlying the hepatoprotective effect. Acute liver injury was induced by lipopolysaccharide/d-galactosamine (LPS/GalN) in mice. Mice were given an intraperitoneal injection of PGI2 mimetics 1h before LPS/GalN challenge. Both ONO-1301 and beraprost significantly declined the LPS/GalN-induced increase in serum aminotransferase activity. ONO-1301 and, to a lesser extent, beraprost inhibited hepatic gene expression levels of pro-inflammatory cytokines, which were sharply elevated by LPS/GalN. The hepatoprotective effects of ONO-1301, to a lesser extent, of beraprost were also supported by liver histopathological examinations. The PGI2 receptor antagonist CAY10441 abrogated their hepatoprotective effects. The mechanisms behind the benefit of PGI2 mimetics in reducing LPS/GalN-induced liver injury involved, in part, their suppressive effects on increased generation of reactive oxygen species (ROS), since their ability to prevent LPS/GalN-induced hepatic apoptosis was mimicked by the antioxidant N-acetyl-l-cysteine. They significantly diminished LPS/GalN-induced activation of signal transducers and activators of transcription 3 (STAT3) in liver tissues, an effect which was highly associated with their hepatoprotective effects. We indicate that IP receptor activation with PGI2 mimetics can rescue the damage in the liver induced by LPS/GalN by undermining activation of STAT3 and leading to a lower production of ROS. Our findings point to PGI2 mimetics, especially ONO-1301, as a potential novel therapeutic modality for the treatment of acute liver injury.

Different effect of resveratrol to induction of apoptosis depending on the type of human cancer cells.

The effect of resveratrol on various human cancer cells was investigated with special focus on apoptotic cell death, in an attempt to further characterize its mechanism of action. There were great differences in the anti-viability effect of resveratrol between different types of human cancer cells. While the inhibition of cell viability by resveratrol was marked in U937 and MOLT-4 leukemia cells, resveratrol moderately inhibited cell viability in MCF-7 breast, HepG2 liver, and A549 lung cancer cells, and the effect was slight on cell viability in Caco-2, HCT116, and SW480 colon cancer cells. Following resveratrol treatment, U937 and MOLT-4 markedly increased the population of late apoptotic cells but MCF-7 and HepG2 underwent apoptosis with an increased population of early apoptosis, and resveratrol-induced DNA fragmentation was observed only in leukemic cells. Activation of sirtuin 1 and adenosine-monophosphate-activated protein kinase was not responsible for resveratrol-induced cancer cell death. Instead, resveratrol significantly reduced Akt activation with the downregulation of H-Ras, resulting in facilitation of Bax translocation to mitochondria in leukemic cells. This study suggests that resveratrol can induce apoptotic cell death in human leukemic cells to a greater extent than in human solid tumor cells via reducing Akt activation due to Ras downregulation.

Critical role of endogenous histamine in promoting end-organ tissue injury in sepsis.

BACKGROUND: Histamine assumes an important role as a major mediator in various pathologic disorders associated with inflammation and immune reactions. However, the involvement of histamine in the pathological conditions and symptoms of sepsis remains entirely unknown. In this study, we establish that histamine is identified as a contributory mediator to promoting the development of organ injury in sepsis. METHODS: Histidine decarboxylase (HDC) gene knockout (HDC-/-) mice, histamine H1-/H2-receptor gene-double knockout (H1R-/-/H2R-/-) mice, and their littermate wild-type (WT) C57BL/6J mice underwent cecal ligation and puncture (CLP) or sham operation. Some WT mice were injected intraperitoneally with d-chlorpheniramine and famotidine 60 min before CLP to block H1- and H2-receptors, respectively. RESULTS: In mice rendered septic by CLP, tissue histamine levels were elevated in association with increased HDC expression. Sepsis-induced abnormal cytokine production and multiple organ injury (lung, liver, and kidney) were significantly less pronounced in HDC-/- mice as compared with WT controls, and HDC deficiency had improved survival in sepsis. This benefit corresponded with a significant reduction in activation levels of the nuclear factor (NF)-κB signaling pathway. H1R-/-/H2R-/- mice apparently behaved similar to HDC knockout mice in reducing sepsis-related pathological changes. Pharmacological interventions with H1- and H2-receptor antagonists indicated that both H1- and H2-receptors were involved in septic lung and liver injury, whereas only H2-receptors contributed to septic kidney injury. CONCLUSIONS: In the setting of sepsis, histamine, through activation of H1- and H2-receptors, serves as an aggravating mediator to contribute to the development of sepsis-driven major end-organ failure.

Zinc Transporter SLC39A7/ZIP7 Promotes Intestinal Epithelial Self-Renewal by Resolving ER Stress.

Zinc transporters play a critical role in spatiotemporal regulation of zinc homeostasis. Although disruption of zinc homeostasis has been implicated in disorders such as intestinal inflammation and aberrant epithelial morphology, it is largely unknown which zinc transporters are responsible for the intestinal epithelial homeostasis. Here, we show that Zrt-Irt-like protein (ZIP) transporter ZIP7, which is highly expressed in the intestinal crypt, is essential for intestinal epithelial proliferation. Mice lacking Zip7 in intestinal epithelium triggered endoplasmic reticulum (ER) stress in proliferative progenitor cells, leading to significant cell death of progenitor cells. Zip7 deficiency led to the loss of Olfm4+ intestinal stem cells and the degeneration of post-mitotic Paneth cells, indicating a fundamental requirement for Zip7 in homeostatic intestinal regeneration. Taken together, these findings provide evidence for the importance of ZIP7 in maintenance of intestinal epithelial homeostasis through the regulation of ER function in proliferative progenitor cells and maintenance of intestinal stem cells. Therapeutic targeting of ZIP7 could lead to effective treatment of gastrointestinal disorders.

Anti-Inflammatory Profile of Levosimendan in Cecal Ligation-Induced Septic Mice and in Lipopolysaccharide-Stimulated Macrophages.

OBJECTIVES: The calcium sensitizer levosimendan is used in treatment of decompensated heart failure and may also exhibit anti-inflammatory properties. We examined whether treatment with levosimendan is substantially beneficial in mice with cecal ligation and puncture-induced polymicrobial sepsis, and its arbitration mechanism was explored in the mouse macrophage cell line RAW264.7. DESIGN: Laboratory and animal/cell research. SETTING: University research laboratory. SUBJECTS: BALB/c mice (8-10 wk old) and mouse macrophage cell line RAW264.7 cells. INTERVENTIONS: Levosimendan (0.5 µg/kg/min) was administered to mice through an osmotic pump that was implanted into the peritoneal cavity immediately following surgery. In RAW264.7 cells, levosimendan was added to the culture medium 30 minutes before lipopolysaccharide. MEASUREMENTS AND MAIN RESULTS: When levosimendan was continuously administered to cecal ligation and puncture-induced septic mice, a significant improvement of left ventricular function was found without any change in heart rate, and hypotension was significantly mitigated. Furthermore, levosimendan conferred substantial protection against sepsis-associated inflammation in mice, as indicated by reduced lung injury and decreased blood proinflammatory and chemotactic cytokine levels. These beneficial effects of levosimendan led to a significant improvement of survival in mice after cecal ligation and puncture. In endotoxin-stimulated RAW264.7 macrophages, treatment with levosimendan and pimobendan suppressed overproduction of proinflammatory and chemotactic cytokines. Levosimendan and pimobendan were without effect on activation of the nuclear factor-κB, mitogen-activated protein kinase, and Akt pathways. Instead, levosimendan and pimobendan prevented high mobility group box 1 release from the nucleus to the extracellular space in macrophages. This was associated with inhibition of the Rho kinase signaling pathway. The elevated serum high mobility group box 1 levels in cecal ligation and puncture-induced septic mice were also inhibited by continued administration of levosimendan and pimobendan. CONCLUSIONS: We define a novel mechanism for the anti-inflammatory action of levosimendan and suggest that the pharmacological profiles of levosimendan as both an inotrope and an anti-inflammatory agent could contribute to its clinical benefit in patients with sepsis with heart problems.

Control of Macrophage Dynamics as a Potential Therapeutic Approach for Clinical Disorders Involving Chronic Inflammation.

Macrophages are a well recognized player of both innate and adaptive immunity and have emerged as a key regulator of systemicmetabolism, hematopoiesis, vasculogenesis, apoptosis, malignancy, and reproduction. Such pleiotropic roles of macrophages are mirrored by their protean features. Upon environmental. challenges, macrophages redistribute and differentiate in situ and contribute to the multiple disease states by exerting protective and pathogenic effects. The environmental challenges include cytokines, chemokines, lipid mediators, and extrinsic insults, such as food and pathogenic bacteria. In addition, homeostasis and the activation state of macrophages are influenced by various metabolites from a commensal microbe that colonizes epithelial and mucosal surfaces, such as the lungs, intestines, and skin. In this review, we describe macrophage differentiation, polarization, and various functions in chronic disease states, including chronic inflammatory bowel disease, tumorigenesis, metabolism and obesity, and central nervous system demyelinating disorders. Controlling the macrophage dynamics to affect the pathologic states is considered to be an important therapeutic approach for many clinical disorders involving chronic inflammation.

Cardiac fibroblasts: contributory role in septic cardiac dysfunction.

BACKGROUND: Cardiac dysfunction is a frequent and severe complication of septic shock and contributes to the high mortality of sepsis. Although several mechanisms have been suspected to be responsible for sepsis-associated cardiac dysfunction, the precise cause(s) remains unclear to date. MATERIALS AND METHODS: We tested the hypothesis that cardiac fibroblasts may play a critical role as a disease modifier involved in sepsis-associated cardiac dysfunction. Human cardiac fibroblasts (HCFs) cultured in vitro were exposed to lipopolysaccharide (LPS). Changes in cardiac morphology and function were assessed in mice with cecal ligation and puncture-induced sepsis. RESULTS: In LPS-stimulated HCFs, messenger RNA and protein levels of proinflammatory molecules, including tumor necrosis factor-α, interleukin-1ß, interleukin-6, and monocyte chemoattractant protein-1, were strikingly upregulated. LPS also increased expression and activity of matrix metalloproteinase (MMP)-9, but not MMP-2. LPS-induced expression of α-smooth muscle actin, a classical marker for myoblast differentiation, which was abrogated when MMP-9 small interfering RNA was transfected into HCFs. High gene expression levels of proinflammatory cytokines and MMP-9 were observed in the heart tissues of cecal ligation and puncture-induced septic mice. Histology sections of the hearts from septic mice showed perivascular and interstitial cardiac fibrosis, and echocardiography demonstrated that septic mice had profound cardiac dysfunction. The broad-spectrum MMP inhibitor ONO-4817 significantly alleviated these histologic and functional changes during the acute phase. CONCLUSIONS: We suggest that cardiac fibroblasts are of pathogenetic importance in inflammation and fibrosis in the heart during sepsis, leading to cardiac dysfunction that would affect the outcome of sepsis syndrome.

In vivo depletion of CD206+ M2 macrophages exaggerates lung injury in endotoxemic mice.

Although phenotypically polarized macrophages are now generally classified into two major subtypes termed proinflammatory M1 and anti-inflammatory M2 macrophages, a contributory role of lung M2 macrophages in the pathophysiological features of acute lung injury is not fully understood. Herein, we show in an endotoxemic murine model that M2 macrophages serve as key anti-inflammatory cells that play a regulatory role in the severity of lung injury. To study whether M2 macrophages can modify inflammation, we depleted M2 macrophages from lungs of CD206-diphtheria toxin (DT) receptor transgenic (Tg) mice during challenge with lipopolysaccharide. The i.p. administration of DT depleted CD206-positive cells in bronchoalveolar lavage fluid. The use of M2 macrophage markers Ym1 and arginase-1 identified pulmonary CD206-positive cells as M2 macrophages. A striking increase in neutrophils in bronchoalveolar lavage fluid cell contents was found in DT-treated CD206-DT receptor Tg mice. In CD206-DT receptor Tg mice given DT, endotoxin challenge exaggerated lung inflammation, including up-regulation of proinflammatory cytokines and increased histological lung damage, but the endotoxemia-induced increase in NF-κB activity was significantly reduced, suggesting that M2 phenotype-dependent counteraction of inflammatory insult cannot be attributed to the inhibition of the NF-κB pathway. Our results indicate a critical role of CD206-positive pulmonary macrophages in triggering inflammatory cascade during endotoxemic lung inflammation.