Prominent Macrophage Infiltration Research Articles

The role of hyperglycemia‐evoked intracellular hyaluronan accumulation and its activity on the autophagic and endoplasmic reticulum stress pathways

AbstractMesangial expansion is a hallmark of diabetic nephropathy (DN) that reduces the area for filtration and leads eventually to sclerosis and renal failure. A phenotypic activation and transient proliferation of the glomerular mesangial cells and a subsequent prominent glomerular infiltration of monocytes and macrophages appear to have a key role in the induction of mesangial matrix expansion, hypercellularity, and the onset of proteinuria. The molecular mechanisms underlying glomerular infiltration and activation by monocytes in DN are still unclear. Our previous studies indicate that aberrant intracellular synthesis of hyaluronan (HA) by hyperglycemic dividing mesangial cells is the central mechanism involved. These studies demonstrated that mesangial cells that divided in hyperglycemia activated synthesis of HA in intracellular compartments and induced endoplasmic reticulum (ER) stress/autophagy to secrete and form a monocyte adhesive extracellular HA matrix. This recruits inflammatory cells and establishes a chronic inflammatory fibrosis process that leads to sclerosis and renal failure. Our perspectives for the role of intracellular HA synthesis, ER stress, and autophagy in diabetic nephropathy are described.

Salmonella enterica serovars in absence of ttrA and pduA genes enhance the cell immune response during chick infections

Salmonella spp. is one of the major foodborne pathogens responsible for causing economic losses to the poultry industry and bringing consequences for public health as well. Both the pathogen survival ability in the intestinal environment during inflammation as well as their relationship with the host immune system, play a key role during infections in poultry. The objective of this study was to quantify the presence of the macrophages and CD4+/CD8+ cells populations using the immunohistochemistry technique, in commercial lineages of chickens experimentally infected by wild-type and mutant strains of Salmonella Enteritidis and Salmonella Typhimurium lacking ttrA and pduA genes. Salmonella Enteritidis ∆ttrA∆pduA triggered a higher percentage of the stained area than the wild-type, with exception of light laying hens. Salmonella Typhimurium wild-type strain and Salmonella Typhimurium ∆ttrA∆pduA infections lead to a similar pattern in which, at 1 and 14 dpi, the caecal tonsils and ileum of birds showed a more expressive stained area compared to 3 and 7 dpi. In all lineages studied, prominent infiltration of macrophages in comparison with CD4+ and CD8+ cells was observed. Overall, animals infected by the mutant strain displayed a positively stained area higher than the wild-type. Deletions in both ttrA and pduA genes resulted in a more intense infiltration of macrophages and CD4+ and CD8+ cells in the host birds, suggesting no pathogen attenuation, even in different strains of Salmonella.

Pulmonary Pathology of End-Stage COVID-19 Disease in Explanted Lungs and Outcomes After Lung Transplantation.

ObjectivesPatients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may develop end-stage lung disease requiring lung transplantation. We report the clinical course, pulmonary pathology with radiographic correlation, and outcomes after lung transplantation in three patients who developed chronic respiratory failure due to postacute sequelae of SARS-CoV-2 infection.MethodsA retrospective histologic evaluation of explanted lungs due to coronavirus disease 2019 was performed.ResultsNone of the patients had known prior pulmonary disease. The major pathologic findings in the lung explants were proliferative and fibrotic phases of diffuse alveolar damage, interstitial capillary neoangiogenesis, and mononuclear inflammation, specifically macrophages, with varying numbers of T and B lymphocytes. The fibrosis varied from early collagen deposition to more pronounced interstitial collagen deposition; however, pulmonary remodeling with honeycomb change was not present. Other findings included peribronchiolar metaplasia, microvascular thrombosis, recanalized thrombi in muscular arteries, and pleural adhesions. No patients had either recurrence of SARS-CoV-2 infection or allograft rejection following transplant at this time.ConclusionsThe major pathologic findings in the lung explants of patients with SARS-CoV-2 infection suggest ongoing fibrosis, prominent macrophage infiltration, neoangiogenesis, and microvascular thrombosis. Characterization of pathologic findings could help develop novel management strategies.

Correlation between Peripheral Blood Eosinophilia and the Histopathological Changes in Nasal Mucosal in Chronic Rhinosinusitis

Background: Chronic rhinosinusitis(CRS) has emerged as one of the major causes of significant morbidity in otorhinolaryngology, as it is often noted to be refractory to medical management and has a tendency to recur post-surgery. Limited research has shown that peripheral eosinophilia is related to the presence of nasal polyps, the extent of the mucosal disease, the severity of tissue eosinophilia, and the risk of recurrence.
 Aim: This study aimed to establish the significance of peripheral blood eosinophilia, both differential (EC) and absolute eosinophil counts (AEC) - in adult CRS, to correlate the tissue eosinophilia and peripheral blood eosinophilia, and compare the observations in the two types of CRS with nasal polyp and without nasal polyp.
 Material and Methods: A total of 50 adult patients with CRS who underwent FESS were included in the study and were divided based on the presence (Group 1) or absence (Group 2) of peripheral blood eosinophilia.
 Results: There were equal number of cases of chronic rhinosinusitis with nasal polyp (CRSwNP) and without polyp (CRSsNP); 25 each. With regard to clinical features, Group 1 had a higher number of cases with nasal obstruction (p-value = 0.023), post-nasal drip (p-value = 0.035), and hyposmia (p-value = 0.021) when compared to Group 2. On histopathology, Group 1 had more areas of edema (p-value = 0.027), and mucous gland hyperplasia (p-value = 0.013) while Group 2 had prominent lymphoplasmacytic infiltrates (p-value = 0.035), neutrophilia (p-value = 0.047), and tissue infiltration of macrophages (p-value = 0.027). Tissue eosinophilia was present in 32 out of the total cases; 20 (71.43%) in Group 1 and 12 (53.33%) in Group 2. The group with tissue eosinophilia had significantly higher eosinophil count (9.24 ± 4.26% vs 5.32 ± 2.9%; p-value < 0.01) as well as AEC (823.335 ± 434.357/µl vs 485.128 ± 285/µl. 907; p-value < 0.01).
 Conclusion: The study demonstrated that CRS cases with tissue eosinophilia exhibit an elevated peripheral eosinophil count when compared to non-eosinophilic CRS.

MO021ENHANCED MCP-1 RELEASE IN EARLY AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in either the PKD1 or PKD2 gene. While kidney failure typically occurs in adulthood, the disease starts in utero. The best change of preserving renal function long term might be the use of agents with few side effects as early as possible. For this approach, both better early prognostic stratification and novel treatment options are needed. The pediatric phase of ADPKD, while kidney function is still normal and before significant tissue destruction has occurred could be the best stage both to identify and study prognostic biomarkers as well as to identify novel targets for early treatment. Copeptin (a surrogate for vasopressin), epidermal growth factor (EGF) ( a measure for functional tubular mass) and monocyte chemoattractant protein-1 (MCP-1) ( a chemoattractant for macrophages) are associated with severity and hold prognostic value in adults but remain unstudied in the early disease stage. Kidneys from adults with ADPKD exhibit macrophage infiltration, and a prominent role of MCP-1 secretion by tubular epithelial cells is suggested from rodent models. Method A monocentric cross-sectional study in a tertiary referral center was performed. All consenting genotyped ADPKD patients attending the outpatient pediatric ADPKD clinic of the university hospital of Leuven and age, sex and BMI matched healthy controls were included between June and October 2017. Plasma copeptin, urinary EGF and urinary MCP-1 were evaluated. MCP-1 was studied in mouse collecting duct cells, human proximal tubular cells and fetal kidney tissue. Results 53 genotyped ADPKD patients and 53 controls were included. Mean (SD) age was 10.4 (5.9) vs 10.5 (6.1) years (P=0.543), and eGFR 122.7 (39.8) vs 114.5 (23.1) ml/min/1.73 m2 (P= 0.177) in patients vs controls respectively. Outcome parameters in table. Plasma copeptin and EGF secretion were comparable between both groups. Median (IQR) urinary MCP-1 (pg/mg creatinine) was significantly higher in ADPKD patients (185.4 (213.8)) compared to controls (154.7 (98.0)) (P= 0.010). Human proximal tubular cells with a heterozygous PKD1 mutation and mouse collecting duct cells with a PKD1 knockout exhibited increased MCP-1 secretion triggered by fetal bovine serum. Human fetal ADPKD kidneys displayed prominent MCP-1 immunoreactivity and M2 macrophage infiltration. Conclusion An increase in tubular MCP-1 secretion is an early event in ADPKD, long before kidney function decline and in children with few kidney cysts. MCP-1 is a promising early disease severity marker and a potential treatment target.

Identification of the immune gene expression signature associated with recurrence of high-grade gliomas.

High-grade gliomas (HGGs), the most common and aggressive primary brain tumors in adults, inevitably recur due to incomplete surgery or resistance to therapy. Intratumoral genomic and cellular heterogeneity of HGGs contributes to therapeutic resistance, recurrence, and poor clinical outcomes. Transcriptomic profiles of HGGs at recurrence have not been investigated in detail. Using targeted sequencing of cancer-related genes and transcriptomics, we identified single nucleotide variations, small insertions and deletions, copy number aberrations (CNAs), as well as gene expression changes and pathway deregulation in 16 pairs of primary and recurrent HGGs. Most of the somatic mutations identified in primary HGGs were not detected after relapse, suggesting a subclone substitution during the tumor progression. We found a novel frameshift insertion in the ZNF384 gene which may contribute to extracellular matrix remodeling. An inverse correlation of focal CNAs in EGFR and PTEN genes was detected. Transcriptomic analysis revealed downregulation of genes involved in messenger RNA splicing, cell cycle, and DNA repair, while genes related to interferon signaling and phosphatidylinositol (PI) metabolism are upregulated in secondary HGGs when compared to primary HGGs. In silico analysis of the tumor microenvironment identified M2 macrophages and immature dendritic cells as enriched in recurrent HGGs, suggesting a prominent immunosuppressive signature. Accumulation of those cells in recurrent HGGs was validated by immunostaining. Our findings point to a substantial transcriptomic deregulation and a pronounced infiltration of immature dendritic cells in recurrent HGG, which may impact the effectiveness of frontline immunotherapies in the GBM management. KEY MESSAGES: Most of the somatic mutations identified in primary HGGs were not detected after relapse. Focal CNAs in EGFR and PTEN genes are inversely correlated in primary and recurrent HGGs. Transcriptomic changes and distinct immune-related signatures characterize HGG recurrence. Recurrent HGGs are characterized by a prominent infiltration of immature dendritic and M2 macrophages.

Combined intracavitary thermotherapy with iron oxide nanoparticles and radiotherapy as local treatment modality in recurrent glioblastoma patients

BackgroundThere is an increasing interest in local tumor ablative treatment modalities that induce immunogenic cell death and the generation of antitumor immune responses.MethodsWe report six recurrent glioblastoma patients who were treated with intracavitary thermotherapy after coating the resection cavity wall with superparamagnetic iron oxide nanoparticles (“NanoPaste” technique). Patients underwent six 1-h hyperthermia sessions in an alternating magnetic field and, if possible, received concurrent fractionated radiotherapy at a dose of 39.6 Gy.ResultsThere were no major side effects during active treatment. However, after 2–5 months, patients developed increasing clinical symptoms. CT scans showed tumor flare reactions with prominent edema around nanoparticle deposits. Patients were treated with dexamethasone and, if necessary, underwent re-surgery to remove nanoparticles. Histopathology revealed sustained necrosis directly adjacent to aggregated nanoparticles without evidence for tumor activity. Immunohistochemistry showed upregulation of Caspase-3 and heat shock protein 70, prominent infiltration of macrophages with ingested nanoparticles and CD3+ T-cells. Flow cytometric analysis of freshly prepared tumor cell suspensions revealed increased intracellular ratios of IFN-γ to IL-4 in CD4+ and CD8+ memory T cells, and activation of tumor-associated myeloid cells and microglia with upregulation of HLA-DR and PD-L1. Two patients had long-lasting treatment responses > 23 months without receiving any further therapy.ConclusionIntracavitary thermotherapy combined with radiotherapy can induce a prominent inflammatory reaction around the resection cavity which might trigger potent antitumor immune responses possibly leading to long-term stabilization of recurrent GBM patients. These results warrant further investigations in a prospective phase-I trial.

Clinicopathological Insights From Vessel Wall Imaging of Unruptured Intracranial Aneurysms.

Background and Purpose- The clinical significance of vessel wall imaging (VWI) remains unclear in patients with unruptured intracranial aneurysms. This study was performed to investigate the correlations between aneurysm wall imaging findings and histopathologic aneurysm wall architectures. Methods- A total of 9 aneurysms was evaluated by VWI and subsequently characterized with histopathology. We used VWI to visualize the aneurysm wall and determine if there was aneurysm wall enhancement after gadolinium contrast administration. Results- Aneurysm wall structures were identified in 6 of 9 unruptured intracranial aneurysms by native VWI, and wall enhancement was identified in 5 of these 6 aneurysms. Histopathologic studies revealed that wall thickening accompanied by atherosclerosis, neovascularization, and macrophage infiltration corresponded to visualization of the aneurysm wall by native VWI and to aneurysm wall enhancement. Conclusions- VWI can visualize thickening of the aneurysm wall, and wall enhancement corresponded to histologically confirmed degenerative changes accompanied by neovascularization and prominent macrophage infiltration.

Inhibition of Spleen Tyrosine Kinase Reduces Renal Allograft Injury in a Rat Model of Acute Antibody-Mediated Rejection in Sensitized Recipients.

Organ transplantation into sensitized patients with preexisting donor-specific antibodies (DSA) is very challenging. Spleen tyrosine kinase (Syk) promotes leukocyte recruitment and activation via signaling through various cell surface receptors. We investigated whether a selective Syk inhibitor (GS-492429) could suppress antibody-mediated rejection (AMR) in a rat model of AMR in sensitized recipients. Recipient Lewis rats (RT1) were immunized with donor (Dark Agouti, RT1) spleen cells (day -5). Recipients underwent bilateral nephrectomy and orthotopic renal transplantation (day 0). Cellular rejection was minimized by tacrolimus treatment from day -1. Groups received GS-492429 (30 mg/kg, twice a day) (n = 11) or vehicle (n = 12) from 1 hour before transplantation until being killed on day 3. Vehicle-treated recipients developed graft dysfunction on day 1 which rapidly worsened by day 3. Histology showed severe damage (thrombosis, acute tubular injury, capillaritis) and infiltration of many Syk leukocytes. GS-492429 did not affect graft dysfunction on day 1, but treatment reduced allograft damage and prevented the rapid deterioration of graft function on day 3. GS-492429 reduced the prominent macrophage infiltrate and reduced the M1 proinflammatory response. Neutrophil and NK cell infiltration and capillary thrombosis were also significantly reduced by GS-492429 treatment. Serum DSA levels and the deposition of IgG and C4d in the allograft were equivalent in the 2 groups. Treatment with a Syk inhibitor significantly reduced renal allograft injury in a model of severe antibody-mediated damage in highly sensitized recipients. Further studies are warranted to determine whether Syk inhibition is a potential adjunctive treatment in clinical AMR.

Imaging Macrophage Accumulation in a Murine Model of Chronic Pancreatitis with 125I-Iodo-DPA-713 SPECT/CT.

Pancreatitis remains a diagnostic challenge in patients with mild to moderate disease, with current imaging modalities being inadequate. Given the prominent macrophage infiltration in chronic pancreatitis, we hypothesized that 125I-iodo-DPA-713, a small-molecule radiotracer that specifically targets macrophages, could be used with SPECT/CT to image pancreatic inflammation in a relevant experimental model. Methods: Chronic pancreatitis was induced with cerulein in C57BL/6 mice, which were contrasted with saline-injected control mice. The animals were imaged at 7 wk after induction using N,N-diethyl-2-(2-(3-125I-iodo-4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide (125I-iodo-DPA-713) SPECT/CT or 18F-FDG PET/CT. The biodistribution of 125I-iodo-DPA-713 was determined under the same conditions, and a pair of mice was imaged using a fluorescent analog of 125I-iodo-DPA-713, DPA-713-IRDye800CW, for correlative histology. Results: Pancreatic 125I-iodo-DPA-713 uptake was significantly higher in treated mice than control mice (5.17% ± 1.18% vs. 2.41% ± 0.34% injected dose/g, P = 0.02), as corroborated by imaging. Mice imaged with 18F-FDG PET/CT showed cerulein-enhanced pancreatic uptake in addition to a moderate signal from healthy pancreas. Near-infrared fluorescence imaging with DPA-713-IRDye800CW showed strong pancreatic uptake, focal liver uptake, and gastrointestinal uptake in the treated mice, whereas the control mice showed only urinary excretion. Ex vivo fluorescence microscopy revealed a large influx of macrophages in the pancreas colocalizing with the retained fluorescent probe in the treated but not the control mice. Conclusion: These data support the application of both 125I-iodo-DPA-713 SPECT/CT and DPA-713-IRDye800CW near-infrared fluorescence to delineate pancreatic, liver, or intestinal inflammation in living mice.

Abstract A65: Initiation of pancreatic metaplasia requires ADAM17-mediated autocrine signaling, not paracrine signaling derived from macrophages

Abstract Acinar-to-ductal metaplasia (ADM) has been frequently seen in the damaged pancreatic tissues. It is also associated with PanIN lesions in PDAC samples derived from human and mouse and has been shown to act as a preneoplastic lesion in mice. Therefore, understanding the mechanisms of lesion formation at the earliest phase would provide needed information for studying pancreatic tumorigenesis. Previously, we have shown that EGFR activity is required for metaplastic duct formation and KRas-induced pancreatic tumorigenesis. In addition, a prominent macrophage infiltration has been shown to be important in the early phase of lesion formation. To investigate the origin of EGFR ligands for EGFR activation during ADM formation in vivo, we examined the metaplasia formation by administration of cerulein in the mice with the conditional knockout of a key EGFR ligand sheddase ADAM17 in the pancreas (ADAM17fl/fl;Ptf1aCre/+) or in the myeloid cells (ADAM17fl/fl;LysM-Cre). With 2 weeks cerulein treatment, wild type and ADAM17fl/fl;LysM-Cre mice showed a similar degree of metaplastic and fibrotic response. However, the mice with ADAM17-null pancreas displayed significant protection from chronic pancreatitis induced by cerulein, including a lack of significant macrophage infiltration, making the analysis of any additional contribution from macrophage derived EGFR ligands. To remedy this, we conditionally knocked out HB-EGF (Heparin-binding EGF-like growth factor) one of the most robustly expressed EGFR ligands in macrophages using LysM-Cre. We examined cerulein-induced metaplasia in HB-EGFfl/fl;LysM-Cre mice. Compared to wild type mice, HB-EGFfl/fl;LysM-Cre mice showed a similar degree of metaplastic and fibrotic response and a decrease in cell proliferation; moreover, myeloid cell-specific ablation of HB-EGF dramatically delayed the healing and the restoration of normal pancreatic epithelium after cessation of cerulein treatment. These results indicate that an ADAM17/EGFR ligand/EGFR autocrine loop derived from pancreatic parenchymal cells is required for metaplastic duct formation, and macrophage-derived HBEGF acting in a paracrine fashion contributes to cell survival and tissue remodeling. Citation Format: Hui-Ju Wen, Howard C. Crawford.{Authors}. Initiation of pancreatic metaplasia requires ADAM17-mediated autocrine signaling, not paracrine signaling derived from macrophages. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr A65.

The Diagnostic Impact of C4d, CD68, and NF-κB Expression in the Differentiation Between Recurrent Hepatitis C and Acute Cellular Rejection After Liver Transplantation.

Liver transplantation is the selected treatment for patients with advanced liver disease and cirrhosis, mostly as a complication of hepatitis C virus (HCV). Recurrent HCV and acute cellular rejection (ACR) of the graft are the most common causes of graft failure. The distinction between the 2 conditions is essential because they are managed differently. In some cases, the clinical and histopathologic features may overlap between recurrent hepatitis C and ACR, making differentiation difficult. The aim of this study was to investigate the role of C4d, CD68, and nuclear factor kappa-B (NF-κB) in the differentiation between ACR and recurrent HCV in the post-liver-transplant biopsy using immunohistochemistry. C4d expression in endothelial cells of portal or central veins (P=0.001) and the number of macrophages highlighted by CD68 (P=0.02) were in favor of ACR, whereas NF-κB expression by hepatocytes was in favor of recurrent hepatitis C. Vascular injury demonstrated by endothelial expression of C4d and prominent macrophage infiltration identified by CD68 expression were the distinguishing criteria for ACR and representing humoral and cellular-mediated immunity as evoking factors for graft injury. The upregulation of NF-κB in the hepatocytes of recurrent hepatitis C could be an immune response to infection or it may be induced by HCV itself.

Infiltration of Macrophages Correlates with Severity of Allograft Rejection and Outcome in Human Kidney Transplantation.

ObjectiveDespite substantial progress in recent years, graft survival beyond the first year still requires improvement. Since modern immunosuppression addresses mainly T-cell activation and proliferation, we studied macrophage infiltration into the allografts of 103 kidney transplant recipients during acute antibody and T-cell mediated rejection. Macrophage infiltration was correlated with both graft function and graft survival until month 36 after transplantation.ResultsMacrophage infiltration was significantly elevated in antibody-mediated and T-cell mediated rejection, but not in kidneys with established IFTA. Treatment of rejection with steroids was less successful in patients with more prominent macrophage infiltration into the allografts. Macrophage infiltration was accompanied by increased cell proliferation as well as antigen presentation. With regard to the compartmental distribution severity of T-cell-mediated rejection was correlated to the amount of CD68+ cells especially in the peritubular and perivascular compartment, whereas biopsies with ABMR showed mainly peritubular CD68 infiltration. Furthermore, severity of macrophage infiltration was a valid predictor of resulting creatinine values two weeks as well as two and three years after renal transplantation as illustrated by multivariate analysis. Additionally performed ROC curve analysis showed that magnitude of macrophage infiltration (below vs. above the median) was a valid predictor for the necessity to restart dialysis. Having additionally stratified biopsies in accordance to the magnitude of macrophage infiltration, differential CD68+ cell infiltration was reflected by striking differences in overall graft survival.ConclusionThe differences in acute allograft rejection have not only been reflected by different magnitudes of macrophage infiltration, but also by compartment-specific infiltration pattern and subsequent impact on resulting allograft function as well as need for dialysis initiation. There is a robust relationship between macrophage infiltration, accompanying antigen-presentation and resulting allograft function.

Attenuation of Nitrogen Mustard-Induced Pulmonary Injury and Fibrosis by Anti-Tumor Necrosis Factor-α Antibody.

Nitrogen mustard (NM) is a bifunctional alkylating agent that causes acute injury to the lung that progresses to fibrosis. This is accompanied by a prominent infiltration of macrophages into the lung and upregulation of proinflammatory/profibrotic cytokines including tumor necrosis factor (TNF)α. In these studies, we analyzed the ability of anti-TNFα antibody to mitigate NM-induced lung injury, inflammation, and fibrosis. Treatment of rats with anti-TNFα antibody (15 mg/kg, iv, every 9 days) beginning 30 min after intratracheal administration of NM (0.125 mg/kg) reduced progressive histopathologic alterations in the lung including perivascular and peribronchial edema, macrophage/monocyte infiltration, interstitial thickening, bronchiolization of alveolar walls, fibrin deposition, emphysema, and fibrosis. NM-induced damage to the alveolar-epithelial barrier, measured by bronchoalveolar lavage (BAL) protein and cell content, was also reduced by anti-TNFα antibody, along with expression of the oxidative stress marker, heme oxygenase-1. Whereas the accumulation of proinflammatory/cytotoxic M1 macrophages in the lung in response to NM was suppressed by anti-TNFα antibody, anti-inflammatory/profibrotic M2 macrophages were increased or unchanged. Treatment of rats with anti-TNFα antibody also reduced NM-induced increases in expression of the profibrotic mediator, transforming growth factor-β. This was associated with a reduction in NM-induced collagen deposition in the lung. These data suggest that inhibiting TNFα may represent an efficacious approach to mitigating lung injury induced by mustards.

Effect of exposure to atmospheric ultrafine particles on production of free fatty acids and lipid metabolites in the mouse small intestine.

Background: Exposure to ambient ultrafine particulate matter (UFP) is a well-recognized risk factor for cardiovascular and respiratory diseases. However, little is known about the effects of air pollution on gastrointestinal disorders.Objective: We sought to assess whether exposure to ambient UFP (diameter < 180 nm) increased free fatty acids and lipid metabolites in the mouse small intestine.Methods: Ldlr-null mice were exposed to filtered air (FA) or UFP collected at an urban Los Angeles, California, site that was heavily affected by vehicular emissions; the exposure was carried out for 10 weeks in the presence or absence of D-4F, an apolipoprotein A-I mimetic peptide with antioxidant and anti-inflammation properties on a high-fat or normal chow diet.Results: Compared with FA, exposure to UFP significantly increased intestinal hydroxyeicosatetraenoic acids (HETEs), including 15-HETE, 12-HETE, 5-HETE, as well as hydroxyoctadecadienoic acids (HODEs), including 13-HODE and 9-HODE. Arachidonic acid (AA) and prostaglandin D2 (PGD2) as well as some of the lysophosphatidic acids (LPA) in the small intestine were also increased in response to UFP exposure. Administration of D-4F significantly reduced UFP-mediated increase in HETEs, HODEs, AA, PGD2, and LPA. Although exposure to UFP further led to shortened villus length accompanied by prominent macrophage and neutrophil infiltration into the intestinal villi, administration of D-4F mitigated macrophage infiltration.Conclusions: Exposure to UFP promotes lipid metabolism, villus shortening, and inflammatory responses in mouse small intestine, whereas administration of D-4F attenuated these effects. Our findings provide a basis to further assess the mechanisms underlying UFP-mediated lipid metabolism in the digestive system with clinical relevance to gut homeostasis and diseases.Citation: Li R, Navab K, Hough G, Daher N, Zhang M, Mittelstein D, Lee K, Pakbin P, Saffari A, Bhetraratana M, Sulaiman D, Beebe T, Wu L, Jen N, Wine E, Tseng CH, Araujo JA, Fogelman A, Sioutas C, Navab M, Hsiai TK. 2015. Effect of exposure to atmospheric ultrafine particles on production of free fatty acids and lipid metabolites in the mouse small intestine. Environ Health Perspect 123:34–41; http://dx.doi.org/10.1289/ehp.1307036

The plasticity of inflammatory monocyte responses to the inflamed central nervous system

Over the last three decades it has become increasingly clear that monocytes, originally thought to have fixed, stereotypic responses to foreign stimuli, mediate exquisitely balanced protective and pathogenic roles in disease and immunity. This balance is crucial in core functional organs, such as the central nervous system (CNS), where minor changes in neuronal microenvironments and the production of immune factors can result in significant disease with fatal consequences or permanent neurological sequelae. Viral encephalitis and multiple sclerosis are examples of important human diseases in which the pathogenic contribution of monocytes recruited from the bone marrow plays a critical role in the clinical expression of disease, as they differentiate into macrophage or dendritic cells in the CNS to carry out effector functions. While antigen-specific lymphocyte populations are central to the adaptive immune response in both cases, in viral encephalitis a prominent macrophage infiltration may mediate immunopathological damage, seizure induction, and death. However, the autoimmune response to non-replicating, non-infectious, but abundant, self antigen has a different disease progression, associated with differentiation of significant numbers of infiltrating monocytes into dendritic cells in the CNS. Whilst a predominant presence of macrophages or dendritic cells in the inflamed CNS in viral encephalitis or multiple sclerosis is well described, the way in which the inflamed CNS mobilizes monocytes in the bone marrow to migrate to the CNS and the key drivers that lead to these specific differentiation pathways in vivo are not well understood. Here we review the current understanding of factors facilitating inflammatory monocyte generation, migration and entry into the brain, as well as their differentiation towards macrophages or dendritic cells in viral and autoimmune disease in relation to their respective disease outcomes.

OP0054 Complete freund’s adjuvant induces, in interferon-gamma-deficient mice, a chronic inflammatory disease reminiscent of systemic juvenile idiopathic arthritis

BackgroundSystemic juvenile idiopathic arthritis (sJIA) is a disease characterized by arthritis and systemic features such as fever, rash, lymphadenopathy and leukocytosis. The underlying pathogenic mechanism of sJIA is not understood...

Ribosomal protein S19 is a novel therapeutic agent in inflammatory kidney disease

RPS19 (ribosomal protein S19), a component of the 40S small ribosomal subunit, has recently been identified to bind the pro-inflammatory cytokine macrophage MIF (migration inhibitory factor). In vitro experiments identify RPS19 as the first endogenous MIF inhibitor by blocking the binding of MIF to its receptor CD74 and MIF functions on monocyte adherence to endothelial cells. In the present study, we sought to establish whether recombinant RPS19 can exert anti-inflammatory effects in a mouse model of anti-GBM (glomerular basement membrane) GN (glomerulonephritis) in which MIF is known to play an important role. Accelerated anti-GBM GN was induced in C57BL/6J mice by immunization with sheep IgG followed 5 days later by administration of sheep anti-mouse GBM serum. Groups of eight mice were treated once daily by intraperitoneal injection with 6 mg of RPS19/kg of body weight or an irrelevant control protein (human secretoglobin 2A1), or received no treatment, from day 0 until being killed on day 10. Mice that received control or no treatment developed severe crescentic anti-GBM disease on day 10 with increased serum creatinine, declined creatinine clearance and increased proteinuria. These changes were associated with up-regulation of MIF and its receptor CD74 activation of ERK (extracellular-signal-regulated kinase) and NF-κB (nuclear factor κB) signalling, prominent macrophage and T-cell infiltration, as well as up-regulation of Th1 [T-bet and IFNγ (interferon γ)] and Th17 [STAT3 (signal transducer and activator of transcription 3) and IL (interleukin)-17A] as well as IL-1β and TNFα (tumour necrosis factor α). In contrast, RPS19 treatment largely prevented the development of glomerular crescents and glomerular necrosis, and prevented renal dysfunction and proteinuria (all P<0.001). Of note, RPS19 blocked up-regulation of MIF and CD74 and inactivated ERK and NF-κB signalling, thereby inhibiting macrophage and T-cell infiltration, Th1 and Th17 responses and up-regulation of pro-inflammatory cytokines (all P<0.01). These results demonstrate that RPS19 is a potent anti-inflammatory agent, which appears to work primarily by inhibiting MIF signalling.

Abstract 18331: Systemic Administration of Allogenic Fetal Membrane-derived MSC Ameliorates Experimental Autoimmune Myocarditis via Suppression of Th1/Th17 Immunity

Background: We have reported that systemic administration of autologous bone marrow or allogenic fetal membrane (FM)-derived mesenchymal stem cells (MSCs) similarly attenuated experimental autoimmune myocarditis (EAM) (JMCC 42:88-97 2007, 49:753-61 2010). Since rat EAM is a T-helper (Th) cell-mediated autoimmune disease, and recent evidence has indicated that MSCs exert an immunosuppressive effect on Th cell activity, we focused on Th cell differentiation in allogenic FM-MSC administered EAM rats. Methods and Results: EAM was induced in Lewis rats by injecting porcine cardiac myosin (day 0). Allogenic FM-MSCs, obtained from major histocompatibility complex mismatched ACI rats, were intravenously injected (5×10[[Unable to Display Character: &amp;#8309;]] cells/rat) on day 7, 10, or 14 (MSCd7, MSCd10, or MSCd14 groups, respectively). At day 21, echocardiography confirmed that reduced ejection fraction in the untreated EAM group (63±2%) was significantly improved in the MSCd10 and MSCd14 groups (74±1 and 75±2%, respectively, P&lt;0.01). CD68 immunostaining revealed that prominent macrophage infiltration in the myocardium of the EAM group (1466±93 cells/mm²) was significantly decreased in the MSCd10 group (958±139 cells/mm², P&lt;0.05). To evaluate Th cell differentiation, flow cytometry was performed to determine the percentage of interferon (IFN)-γ positive Th1 and interleukin (IL)-17 positive Th17 cells in peripheral CD4-positive Th cells. The percentage of Th1 cells at day 16 was significantly lower in the MSCd10 (1.3±0.2%) and MSCd14 (1.6±0.3%) groups compared to the EAM group (2.4±0.3%, P&lt;0.05), as was the percentage of Th17 cells in the MSCd10 group (1.9±0.5%) compared to the EAM group (2.2±0.9%, P&lt;0.05). In addition, human CD4+ Th cells co-cultured with human FM-MSCs exhibited reduced Th1 and Th17 cell differentiation and proliferation, with increased expression of immunosuppressive molecules including indoleamine 2,3-dioxygenase 2 and IL-6 in co-cultured FM-MSCs. Conclusion: Our findings demonstrate the protective effects of intravenously administered FM-MSCs in EAM due to profound suppression of Th1/Th17 cells and provide a new perspective for the treatment of acute myocarditis.

Systemic transplantation of allogenic fetal membrane-derived mesenchymal stem cells suppresses Th1 and Th17 T cell responses in experimental autoimmune myocarditis

We have reported that systemic administration of autologous bone marrow or allogenic fetal membrane (FM)-derived mesenchymal stem cells (MSCs) similarly attenuated myocardial injury in rats with experimental autoimmune myocarditis (EAM). Since rat EAM is a T-helper (Th) cell-mediated autoimmune disease, and recent evidence has indicated that both autologous and allogenic MSCs exert an immunosuppressive effect on Th cell activity, we focused on Th cell differentiation in allogenic FM-MSC administered EAM rats. EAM was induced in Lewis rats by injecting porcine cardiac myosin (day 0). Allogenic FM-MSCs, obtained from major histocompatibility complex mismatched ACI rats, were intravenously injected (5×10⁵cells/rat) on days 7, 10, or 14 (MSCd7, MSCd10, or MSCd14 groups, respectively). At day 21, echocardiography confirmed that reduced ejection fraction in the untreated EAM group (63±2%) was significantly improved in the MSCd10 and MSCd14 groups (74±1 and 75±2%, respectively, P<0.01). CD68 immunostaining revealed that prominent macrophage infiltration in the myocardium of the EAM group (1466±93 cells/mm²) was significantly decreased in the MSCd10 group (958±139 cells/mm², P<0.05). To evaluate Th cell differentiation, we used flow cytometry to determine the percentage of interferon (IFN)-γ positive Th1 and interleukin (IL)-17 positive Th17 cells in peripheral CD4-positive Th cells. The percentage of Th1 cells at day 16 was significantly lower in the MSCd10 (1.3±0.2%) and MSCd14 (1.6±0.3%) groups compared to the EAM group (2.4±0.3%, P<0.05), as was the percentage of Th17 cells in the MSCd10 group (1.9±0.5%) compared to the EAM group (2.2±0.9%, P<0.05). At day 21, infiltrating Th17 cells in myocardium were significantly decreased in the MSCd10 group (501±132cells/mm², P<0.05) compared to EAM (921±109cells/mm²). In addition, human CD4+ Th cells co-cultured with human FM-MSCs exhibited reduced Th1 and Th17 cell-differentiation and proliferation, with increased expression of immunosuppressive molecules including indoleamine 2,3-dioxygenase 2 and IL-6 in co-cultured FM-MSCs. These results suggest that intravenous administration of allogenic FM-MSCs ameliorates EAM via the suppression of Th1/Th17 immunity.