Stromal Cells Covering Omental Fat-Associated Lymphoid Clusters Trigger Formation of Neutrophil Aggregates to Capture Peritoneal Contaminants.

The omentum is a visceral adipose tissue rich in fat-associated lymphoid clusters (FALCs) that collects peritoneal contaminants and provides a first layer of immunological defense within the abdomen. Here, we investigated the mechanisms that mediate the capture of peritoneal contaminants during peritonitis. Single-cell RNA sequencing and spatial analysis of omental stromal cells revealed that the surface of FALCs were covered by CXCL1+ mesothelial cells, which we termed FALC cover cells. Blockade of CXCL1 inhibited the recruitment and aggregation of neutrophils at FALCs during zymosan-induced peritonitis. Inhibition of protein arginine deiminase 4, an enzyme important for the release of neutrophil extracellular traps, abolished neutrophil aggregation and the capture of peritoneal contaminants by omental FALCs. Analysis of omental samples from patients with acute appendicitis confirmed neutrophil recruitment and bacterial capture at FALCs. Thus, specialized omental mesothelial cells coordinate the recruitment and aggregation of neutrophils to capture peritoneal contaminants.

Complement Factor H Inhibits CD47-Mediated Resolution of Inflammation.

Variants of the CFH gene, encoding complement factor H (CFH), show strong association with age-related macular degeneration (AMD), a major cause of blindness. Here, we used murine models of AMD to examine the contribution of CFH to disease etiology. Cfh deletion protected the mice from the pathogenic subretinal accumulation of mononuclear phagocytes (MP) that characterize AMD and showed accelerated resolution of inflammation. MP persistence arose secondary to binding of CFH to CD11b, which obstructed the homeostatic elimination of MPs from the subretinal space mediated by thrombospsondin-1 (TSP-1) activation of CD47. The AMD-associated CFH(H402) variant markedly increased this inhibitory effect on microglial cells, supporting a causal link to disease etiology. This mechanism is not restricted to the eye, as similar results were observed in a model of acute sterile peritonitis. Pharmacological activation of CD47 accelerated resolution of both subretinal and peritoneal inflammation, with implications for the treatment of chronic inflammatory disease.

The association of TLR4 gene polymorphisms with the severity of peritonitis in acute inflammatory diseases of the abdominal cavity organs.

OBJECTIVE: Aim: To determine the role of TLR4 gene polymorphisms as risk factors for peritonitis severity in patients undergoing surgery for acute inflammatory diseases of the abdominal cavity. PATIENTS AND METHODS: Materials and Methods: The study included 139 patients who were operated on for acute abdominal diseases (acute appendicitis and cholecystitis, perforated gastric or duodenal ulcer, etc.). Depending on the number of points on the modified APACHE II scale, patients were divided into two groups: Group 1 - 1-3 points (63 patients, 45.3%) and Group 2 - 4 or more points (76 patients, 54.7%). Polymorphisms rs1927911, rs2149356 and rs4986790 were determined by polymerase chain reaction. RESULTS: Results: The rs1927911 polymorphism of the TLR4 gene was protective for the development of peritonitis (according to the allelic model, OR 0.48; 95% CI 0.27-0.84; p=0.015). Regression analysis revealed a reduced (p=0.015) risk of severe peritonitis in rs1927911 A/A or G/A genotype carriers (OR 0.42; 95% CI 0.21-0.84) compared with G/G genotype carriers. There was no effect on the severity of peritonitis of TLR4 polymorphisms rs2149356 and rs4986790. There was a tendency to increase the frequency of the mutant G rs4986790 allele in patients with severe peritonitis (χ2=2.17; p<0.001). The analysis of the association of TLR4 gene polymorphisms with the phenotype of patients showed that carriers of mutant homozygotes and heterozygotes in the presence of severe peritonitis were older, had a tendency to coagulopathy, higher leukocytosis and leukocyte clotting rate. CONCLUSION: Conclusions: Thus, the importance of TLR in the development of severe peritonitis was confirmed and the protective role of the rs1927911 promoter polymorphism was established.

Interleukin-6 signaling drives fibrosis in unresolved inflammation.

Fibrosis in response to tissue damage or persistent inflammation is a pathological hallmark of many chronic degenerative diseases. By using a model of acute peritoneal inflammation, we have examined how repeated inflammatory activation promotes fibrotic tissue injury. In this context, fibrosis was strictly dependent on interleukin-6 (IL-6). Repeat inflammation induced IL-6-mediated T helper 1 (Th1) cell effector commitment and the emergence of STAT1 (signal transducer and activator of transcription-1) activity within the peritoneal membrane. Fibrosis was not observed in mice lacking interferon-γ (IFN-γ), STAT1, or RAG-1. Here, IFN-γ and STAT1 signaling disrupted the turnover of extracellular matrix by metalloproteases. Whereas IL-6-deficient mice resisted fibrosis, transfer of polarized Th1 cells or inhibition of MMP activity reversed this outcome. Thus, IL-6 causes compromised tissue repair by shifting acute inflammation into a more chronic profibrotic state through induction of Th1 cell responses as a consequence of recurrent inflammation.

Anthracyclines induce DNA damage response-mediated protection against severe sepsis.

Severe sepsis remains a poorly understood systemic inflammatory condition with high mortality rates and limited therapeutic options in addition to organ support measures. Here we show that the clinically approved group of anthracyclines acts therapeutically at a low dose regimen to confer robust protection against severe sepsis in mice. This salutary effect is strictly dependent on the activation of DNA damage response and autophagy pathways in the lung, as demonstrated by deletion of the ataxia telangiectasia mutated (Atm) or the autophagy-related protein 7 (Atg7) specifically in this organ. The protective effect of anthracyclines occurs irrespectively of pathogen burden, conferring disease tolerance to severe sepsis. These findings demonstrate that DNA damage responses, including the ATM and Fanconi Anemia pathways, are important modulators of immune responses and might be exploited to confer protection to inflammation-driven conditions, including severe sepsis.

PASylation of IL-1 receptor antagonist (IL-1Ra) retains IL-1 blockade and extends its duration in mouse urate crystal-induced peritonitis.

Interleukin-1 (IL-1) is a key mediator of inflammation and immunity. Naturally-occurring IL-1 receptor antagonist (IL-1Ra) binds and blocks the IL-1 receptor-1 (IL-1R1), preventing signaling. Anakinra, a recombinant form of IL-1Ra, is used to treat a spectrum of inflammatory diseases. However, anakinra is rapidly cleared from the body and requires daily administration. To create a longer-lasting alternative, PASylated IL-1Ra (PAS-IL-1Ra) has been generated by in-frame fusion of a long, defined-length, N-terminal Pro/Ala/Ser (PAS) random-coil polypeptide with IL-1Ra. Here, we compared the efficacy of two PAS-IL-1Ra molecules, PAS600-IL-1Ra and PAS800-IL-1Ra (carrying 600 and 800 PAS residues, respectively), with that of anakinra in mice. PAS600-IL-1Ra displayed markedly extended blood plasma levels 3 days post-administration, whereas anakinra was undetectable after 24 h. We also studied PAS600-IL-1Ra and PAS800-IL-1Ra for efficacy in monosodium urate (MSU) crystal-induced peritonitis. 5 days post-administration, PAS800-IL-1Ra significantly reduced leukocyte influx and inflammatory markers in MSU-induced peritonitis, whereas equimolar anakinra administered 24 h before MSU challenge was ineffective. The 6-h pretreatment with equimolar anakinra or PAS800-IL-1Ra before MSU challenge similarly reduced inflammatory markers. In cultured A549 lung carcinoma cells, anakinra, PAS600-IL-1Ra, and PAS800-IL-Ra reduced IL-1α-induced IL-6 and IL-8 levels with comparable potency. In human peripheral blood mononuclear cells, these molecules suppressed Candida albicans-induced production of the cancer-promoting cytokine IL-22. Surface plasmon resonance analyses revealed significant binding between PAS-IL-1Ra and IL-1R1, although with a slightly lower affinity than anakinra. These results validate PAS-IL-1Ra as an active IL-1 antagonist with marked in vivo potency and a significantly extended half-life compared with anakinra.

Control of neutrophil influx during peritonitis by transcriptional cross-regulation of chemokine CXCL1 by IL-17 and IFN-γ.

Neutrophil infiltration is a hallmark of peritoneal inflammation, but mechanisms regulating neutrophil recruitment in patients with peritoneal dialysis (PD)-related peritonitis are not fully defined. We examined 104 samples of PD effluent collected during acute peritonitis for correspondence between a broad range of soluble parameters and neutrophil counts. We observed an association between peritoneal IL-17 and neutrophil levels. This relationship was evident in effluent samples with low but not high IFN-γ levels, suggesting a differential effect of IFN-γ concentration on neutrophil infiltration. Surprisingly, there was no association of neutrophil numbers with the level of CXCL1, a key IL-17-induced neutrophil chemoattractant. We investigated therefore the production of CXCL1 by human peritoneal mesothelial cells (HPMCs) under in vitro conditions mimicking clinical peritonitis. Stimulation of HPMCs with IL-17 increased CXCL1 production through induction of transcription factor SP1 and activation of the SP1-binding region of the CXCL1 promoter. These effects were amplified by TNFα. In contrast, IFN-γ dose-dependently suppressed IL-17-induced SP1 activation and CXCL1 production through a transcriptional mechanism involving STAT1. The SP1-mediated induction of CXCL1 was also observed in HPMCs exposed to PD effluent collected during peritonitis and containing IL-17 and TNFα, but not IFN-γ. Supplementation of the effluent with IFN-γ led to a dose-dependent activation of STAT1 and a resultant inhibition of SP1-induced CXCL1 expression. Transmesothelial migration of neutrophils in vitro increased upon stimulation of HPMCs with IL-17 and was reduced by IFN-γ. In addition, HPMCs were capable of binding CXCL1 at their apical cell surface. These observations indicate that changes in relative peritoneal concentrations of IL-17 and IFN-γ can differently engage SP1-STAT1, impacting on mesothelial cell transcription of CXCL1, whose release and binding to HPMC surface may determine optimal neutrophil recruitment and retention during peritonitis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

MicroRNA Interference in Hepatic Host-Pathogen Interactions.

The liver is well recognized as a non-immunological visceral organ that is involved in various metabolic activities, nutrient storage, and detoxification. Recently, many studies have demonstrated that resident immune cells in the liver drive various immunological reactions by means of several molecular modulators. Understanding the mechanistic details of interactions between hepatic host immune cells, including Kupffer cells and lymphocytes, and various hepatic pathogens, especially viruses, bacteria, and parasites, is necessary. MicroRNAs (miRNAs), over 2600 of which have been discovered, are small, endogenous, interfering, noncoding RNAs that are predicted to regulate more than 15,000 genes by degrading specific messenger RNAs. Several recent studies have demonstrated that some miRNAs are associated with the immune response to pathogens in the liver. However, the details of the underlying mechanisms of miRNA interference in hepatic host-pathogen interactions still remain elusive. In this review, we summarize the relationship between the immunological interactions of various pathogens and hepatic resident immune cells, as well as the role of miRNAs in the maintenance of liver immunity against pathogens.

Effect of murine double-minute 2 inhibitors in preclinical models of advanced clear cell carcinomas originating from ovaries and kidneys.

Advanced clear cell carcinomas originating from both ovaries and kidneys with cancerous peritonitis have poor prognoses. Murine double-minute 2 (MDM2) is a potential therapeutic target for clear cell ovarian carcinomas with WT TP53. Herein, we characterized the antiangiogenic and antitumor effects of the MDM2 inhibitors DS-3032b and DS-5272 in 6 clear cell ovarian carcinoma cell lines and 2 clear cell renal carcinoma cell lines, as well as in clear cell ovarian carcinomas s.c. xenograft and ID8 (murine ovarian cancer cells with WT TP53) cancer peritonitis mouse models. In clear cell ovarian carcinoma s.c. xenograft mouse models, DS-3032b significantly reduced WT TP53 clear cell ovarian carcinoma- and clear cell renal carcinoma-derived tumor volumes. In ID8 mouse models, DS-5272 significantly inhibited ascites production, reduced body weight, and significantly improved overall survival. Additionally, DS-5272 reduced the tumor burden of peritoneal dissemination and decreased CD31+ cells in a dose-dependent manner. Furthermore, DS-5272 significantly decreased vascular endothelial growth factor concentrations in both sera and ascites. Combined therapy with MDM2 inhibitors and everolimus showed synergistic, and dose-reduction potential, for clear cell carcinoma treatment. Our findings suggest that MDM2 inhibitors represent promising molecular targeted therapy for clear cell carcinomas, thereby warranting further studies to evaluate the efficacy and safety of dual MDM2/mTOR inhibitors in clear cell carcinoma patients.

The pro-apoptotic ARTS protein induces neutrophil apoptosis, efferocytosis, and macrophage reprogramming to promote resolution of inflammation.

ARTS (Sept4_i2) is a pro-apoptotic protein and a product of the Sept4 gene. ARTS acts upstream of mitochondria to initiate caspase activation. ARTS induces apoptosis by specifically binding XIAP and allowing de-repression of active caspases required for Mitochondrial Outer Membrane Permeabilzation (MOMP). Moreover, ARTS promotes apoptosis by inducing ubiquitin-mediated degradation of both major anti-apoptotic proteins XIAP and Bcl-2. In the resolution phase of inflammation, the infiltrating leukocytes, which execute the acute innate response, undergo apoptosis and are subsequently cleared by phagocytic macrophages (i.e. efferocytosis). In this course, macrophages undergo reprogramming from inflammatory, to anti-inflammatory, and eventually to resolving macrophages that leave the injury sites. Since engulfment of apoptotic leukocytes is a key signaling step in macrophage reprogramming and resolution of inflammation, we hypothesized that a failed apoptosis in leukocytes in vivo would result in an impaired resolution process. To test this hypothesis, we utilized the Sept4/ARTS-/- mice, which exhibit resistance to apoptosis in many cell types. During zymosan A-induced peritonitis, Sept4/ARTS-/- mice exhibited impaired resolution of inflammation, characterized by reduced neutrophil apoptosis, macrophage efferocytosis and expression of pro-resolving mediators. This was associated with increased pro-inflammatory cytokines and reduced anti-inflammatory cytokines, secreted by resolution-phase macrophages. Moreover, ARTS overexpression in leukocytes in vitro promoted an anti-inflammatory behavior. Overall, our results suggest that ARTS is a key master-regulator necessary for neutrophil apoptosis, macrophage efferocytosis and reprogramming to the pro-resolving phenotype during the resolution of inflammation.

Myosin 1f is specifically required for neutrophil migration in 3D environments during acute inflammation.

Neutrophil extravasation and interstitial migration are important steps during the recruitment of neutrophils to sites of inflammation. In the present study, we addressed the functional importance of the unconventional class I myosin 1f (Myo1f) for neutrophil trafficking during acute inflammation. In contrast to leukocyte rolling and adhesion, the genetic absence of Myo1f severely compromised neutrophil extravasation into the inflamed mouse cremaster tissue when compared with Myo1f+/+ mice as studied by intravital microscopy. Similar results were obtained in experimental models of acute peritonitis and acute lung injury. In contrast to 2-dimensional migration, which occurred independently of Myo1f, Myo1f was indispensable for neutrophil migration in 3-dimensional (3D) environments, that is, transmigration and migration in collagen networks as it regulated squeezing and dynamic deformation of the neutrophil nucleus during migration through physical barriers. Thus, we provide evidence for an important role of Myo1f in neutrophil trafficking during inflammation by specifically regulating neutrophil extravasation and migration in 3D environments.

Deletion of the adenosine A2A receptor increases the survival rate in a mice model of polymicrobial sepsis.

We aim to investigate the role of A2A receptor in peritonitis-related sepsis by injection of a fecal solution (FS) as a model of polymicrobial infection. C57/black J6 wild-type (WT) and A2A-deficient mice (A2AKO) were exposed to sepsis induced by intraperitoneal injection of a FS (FS-induced peritonitis) or instead was injected with saline buffer (Sham). Survival rate and sepsis score were measured up to 48 h. The presence of bacteria in tissue homogenates was analyzed. Telemetry and speckle laser Doppler were used for systemic blood pressure and peripheral blood perfusion analysis, respectively. Histological analysis and identification of active caspase 3 were performed in selected organs, including the liver. The survival rate of A2AKO mice exposed to FS-induced peritonitis was significantly higher, and the sepsis score was lower than their respective WT counterpart. Injection of FS increases (50 to 150 folds) the number of colonies forming units in the liver, kidney, blood, and lung in WT mice, while these effects were significantly attenuated in A2AKO mice exposed to FS-induced peritonitis. A significant reduction in both systolic and diastolic blood pressure, as well as in the peripheral perfusion was observed in WT and A2AKO mice exposed to FS-induced peritonitis. Although, these last effects were significantly attenuated in A2AKO mice. Histological analysis showed a large perivascular infiltration of polymorphonuclear in the liver of WT and A2AKO mice exposed to FS-induced peritonitis, but again, this effect was attenuated in A2AKO mice. Finally, high expression of active caspase 3 was found only in the liver of WT mice exposed to FS-induced peritonitis. The absence of the A2A receptor increases the survival rate in mice exposed to polymicrobial sepsis. This outcome was associated with both hemodynamic compensation and enhanced anti-bacterial response.

Role of ascitic endocan levels in the diagnosis of spontaneous bacterial peritonitis in decompensated cirrhosis.

Objective: To assess the role of ascitic endocan levels in the diagnosis of spontaneous bacterial peritonitis (SBP) in decompensated cirrhosis.Methods: Ascites samples, as well as demographic and laboratory data, were collected at admission from patients with decompensated cirrhosis. Ascitic endocan, tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were measured by ELISA. The influencing factors of SBP, the correlation of ascitic endocan with other inflammatory indicators, and the diagnostic value of ascitic endocan for SBP were analyzed.Results: A total of 167 patients were enrolled, 39 with the SBP group and 128 in the non-SBP group. Ascitic endocan, TNF-α, and IL-6 levels were significantly higher in the SBP group than in the non-SBP group (p < 0.001). Multivariate analysis demonstrated that ascitic endocan was an independent risk factor for SBP [OR = 1.006 (95% CI: 1.002-1.011); p < 0.001]. Endocan was positively correlated with ascites polymorphonuclear leukocytes, TNF-α, and IL-6. ROC curve analysis showed that ascitic endocan had an AUC of 0.805 for the diagnosis of SBP (p < 0.001) and had a sensitivity of 82.1% and specificity of 73.4% when the cut-off value was 295.011 pg/ml.Conclusions: Ascitic endocan level is an independent risk factor and a valuable diagnostic indicator for SBP in decompensated cirrhosis.

A Fundamental Role of Myh9 for Neutrophil Migration in Innate Immunity.

Neutrophils are the first leukocytes to arrive at sites of injury during the acute inflammatory response. To maintain the polarized morphology during migration, nonmuscle myosins class II are essential, but studies using genetic models to investigate the role of Myh9 for neutrophil migration were missing. In this study, we analyzed the functional role of Myh9 on neutrophil trafficking using genetic downregulation of Myh9 in Vav-iCre+/Myh9wt/fl mice because the complete knockout of Myh9 in the hematopoietic system was lethal. Migration velocity and Euclidean distance were significantly diminished during mechanotactic migration of Vav-iCre+/Myh9wt/fl neutrophils compared with Vav-iCre-/Myh9wt/fl control neutrophils. Similar results were obtained for transmigration and migration in confined three-dimensional environments. Stimulated emission depletion nanoscopy revealed that a certain threshold of Myh9 was required to maintain proper F-actin dynamics in the front of the migrating cell. In laser-induced skin injury and in acute peritonitis, reduced Myh9 expression in the hematopoietic system resulted in significantly diminished neutrophil extravasation. Investigation of bone marrow chimeric mice in the peritonitis model revealed that the migration defect was cell intrinsic. Expression of Myh9-EGFP rescued the Myh9-related defects in two-dimensional and three-dimensional migration of Hoxb8-SCF cell-derived neutrophils generated from fetal liver cells with a Myh9 knockdown. Live cell imaging provided evidence that Myh9 was localized in branching lamellipodia and in the uropod where it may enable fast neutrophil migration. In summary, the severe migration defects indicate an essential and fundamental role of Myh9 for neutrophil trafficking in innate immunity.

Proteomic Research in Peritoneal Dialysis.

Peritoneal dialysis (PD) is an established home care, cost-effective renal replacement therapy (RRT), which offers several advantages over the most used dialysis modality, hemodialysis. Despite its potential benefits, however, PD is an under-prescribed method of treating uremic patients. Infectious complications (primarily peritonitis) and bio-incompatibility of PD solutions are the main contributors to PD drop-out, due to their potential for altering the functional and anatomical integrity of the peritoneal membrane. To improve the clinical outcome of PD, there is a need for biomarkers to identify patients at risk of PD-related complications and to guide personalized interventions. Several recent studies have shown that proteomic investigation may be a powerful tool in the prediction, early diagnosis, prognostic assessment, and therapeutic monitoring of patients on PD. Indeed, analysis of the proteome present in PD effluent has uncovered several proteins involved in inflammation and pro-fibrotic insult, in encapsulating peritoneal sclerosis, or even in detecting early changes before any measurable modifications occur in the traditional clinical parameters used to evaluate PD efficacy. We here review the proteomic studies conducted thus far, addressing the potential use of such omics methodology in identifying potential new biomarkers of the peritoneal membrane welfare in relation to dialytic prescription and adequacy.

Dual Effect of Soloxolone Methyl on LPS-Induced Inflammation In Vitro and In Vivo.

Plant-extracted triterpenoids belong to a class of bioactive compounds with pleotropic functions, including antioxidant, anti-cancer, and anti-inflammatory effects. In this work, we investigated the anti-inflammatory and anti-oxidative activities of a semisynthetic derivative of 18ßH-glycyrrhetinic acid (18ßH-GA), soloxolone methyl (methyl 2-cyano-3,12-dioxo-18ßH-olean-9(11),1(2)-dien-30-oate, or SM) in vitro on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and in vivo in models of acute inflammation: LPS-induced endotoxemia and carrageenan-induced peritonitis. SM used at non-cytotoxic concentrations was found to attenuate the production of reactive oxygen species and nitric oxide (II) and increase the level of reduced glutathione production by LPS-stimulated RAW264.7 cells. Moreover, SM strongly suppressed the phagocytic and migration activity of activated macrophages. These effects were found to be associated with the stimulation of heme oxigenase-1 (HO-1) expression, as well as with the inhibition of nuclear factor-κB (NF-κB) and Akt phosphorylation. Surprisingly, it was found that SM significantly enhanced LPS-induced expression of the pro-inflammatory cytokines interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) in RAW264.7 cells via activation of the c-Jun/Toll-like receptor 4 (TLR4) signaling axis. In vivo pre-exposure treatment with SM effectively inhibited the development of carrageenan-induced acute inflammation in the peritoneal cavity, but it did not improve LPS-induced inflammation in the endotoxemia model.

Massive ascites and severe pulmonary hypoplasia in a premature infant with meconium peritonitis and congenital cytomegalovirus infection.

Background: Meconium peritonitis (MP) is an infrequent prenatal complication. Association between MP and pulmonary hypoplasia has never been reported. Case Report: A female infant with antenatally diagnosed MP and ascites was delivered at 36 gestational weeks. She died shortly after birth due to pulmonary insufficiency. Autopsy confirmed the presence of MP and ascites, and additionally revealed intestinal malrotation, volvulus, necrosis and perforation, and pulmonary hypoplasia. Congenital cytomegalovirus (CMV) infection was also noted. This was an unexpected finding as the mother was tested negative for CMV IgM at 26 gestational weeks after sonographic detection of fetal ascites. Conclusions: This is the first reported case of lethal pulmonary hypoplasia in a neonate with MP-associated ascites complicated by congenital CMV infection. This case illustrates that a negative maternal CMV IgM might not be sufficient to rule out congenital CMV, and that a concomitant infectious etiology should always be considered even when a primary cause for fetal ascites (e.g., MP in this case) is identified.

CD146 deficiency promotes plaque formation in a mouse model of atherosclerosis by enhancing RANTES secretion and leukocyte recruitment.

AIMS: The progression of atherosclerosis is based on the continued recruitment of leukocytes in the vessel wall. The previously described role of CD146 in leukocyte infiltration suggests an involvement for this adhesion molecule in the inflammatory response. In this study, we investigated the role of CD146 in leukocyte recruitment by using an experimental model of atherogenesis. METHODS AND RESULTS: The role of CD146 was explored in atherosclerosis by crossing CD146-/- mice with ApoE-/- mice. CD146 -/-/ApoE -/- and ApoE -/- mice were fed a Western diet for 24 weeks and were monitored for aortic wall thickness using high frequency ultrasound. The arterial wall was significantly thicker in CD146-deficient mice. After 24 weeks of Western diet, a significant increase of atheroma in both total aortic lesion and aortic sinus of CD146-null mice was observed. In addition, atherosclerotic lesions were more inflammatory since plaques from CD146-deficient mice contained more neutrophils and macrophages. This was due to up-regulation of RANTES secretion by macrophages in CD146-deficient atherosclerotic arteries. This prompted us to further address the function of CD146 in leukocyte recruitment during acute inflammation by using a second experimental model of peritonitis induced by thioglycollate. Neutrophil recruitment was significantly increased in CD146-deficient mice 12 h after peritonitis induction and associated with higher RANTES levels in the peritoneal cavity. In CD146-null macrophages, we also showed that increased RANTES production was dependent on constitutive inhibition of the p38-MAPK signaling pathway. Finally, Maraviroc, a RANTES receptor antagonist, was able to reduce atherosclerotic lesions and neutrophilia in CD146-deficient mice to the same level as that found in ApoE -/- mice. CONCLUSIONS: Our data indicate that CD146 deficiency is associated with the upregulation of RANTES production and increased inflammation of atheroma, which could influence the atherosclerotic plaque fate. Thus, these data identify CD146 agonists as potential new therapeutic candidates for atherosclerosis treatment.

Emergence of an NDM-5-Producing Hypervirulent Klebsiella pneumoniae Sequence Type 35 Strain with Chromosomal Integration of an Integrative and Conjugative Element, ICEKp1.

Here, we report an NDM-5-producing sequence type 35 (ST35) hypervirulent Klebsiella pneumoniae strain, isolated from the blood of a male patient. It showed a remarkable resistance to serum killing and neutrophil phagocytosis and high virulence in a mouse peritonitis infection model. Instead of carrying a pLVPK-like virulence plasmid, chromosomal integration of ICEKp1 (∼76 kb) was identified in a specific asparagine-tRNA gene, harboring the iron acquisition system salmochelin genes (iroBCDN), a yersiniabactin gene, and a variant of the rmpA gene.

Nonlinear Multimodal Imaging Characteristics of Early Septic Liver Injury in a Mouse Model of Peritonitis.

Sepsis constitutes a life-threatening organ failure caused by a deregulated host response to infection. Identifying early biomolecular indicators of organ dysfunction may improve clinical decision-making and outcome of patients. Herein we utilized label-free nonlinear multimodal imaging, combining coherent anti-Stokes Raman scattering (CARS), two-photon excited autofluorescence (TPEF), and second-harmonic generation (SHG) to investigate the consequences of early septic liver injury in a murine model of polymicrobial abdominal infection. Liver tissue sections from mice with and without abdominal sepsis were analyzed using multimodal nonlinear microscopy, immunofluorescence, immunohistochemistry, and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Twenty-four hours after the induction of sepsis, hepatic mRNA of inflammatory cytokines and acute phase proteins was upregulated, and liver-infiltrating myeloid cells could be visualized alongside hepatocellular cytoplasmic translocation of high mobility group box 1. According to the statistical analysis based on texture feature extraction followed by the combination of dimension reduction and linear discriminant analysis, CARS (AUC = 0.93) and TPEF (AUC = 0.83) showed an excellent discrimination between liver sections from septic mice and sham-treated mice in contrast to SHG (AUC = 0.49). Spatial analysis revealed no major differences in the distribution of sepsis-associated changes between periportal and pericentral zones. These data suggest early alterations in hepatic lipid distribution and metabolism during liver injury and confirm nonlinear multimodal imaging as a promising complementary method for the real-time, label-free study of septic liver damage.