New mechanisms and pathways for monocyte recruitment

Activation of CD14+ Monocytes via the IFN-γ Signaling Pathway Is Associated with Immune-Related Adverse Events in Hepatocellular Carcinoma Patients Receiving PD-1 Inhibition Combination Therapy

(1) Background: Immune-related adverse events (irAEs) are a series of unique organ-specific inflammatory toxicities observed in patients with hepatocellular carcinoma (HCC) undergoing PD-1 inhibition combination therapy. The specific underlying mechanisms remain unclear. (2) Methods: We recruited 71 patients with HCC undergoing PD-1 inhibition combination therapy. These patients were then divided into two groups based on irAE occurrence: 34 had irAEs and 37 did not. Using Olink proteomics, we analyzed the aberrant inflammation-related proteins (IRPs) in these patient groups. For single-cell RNA sequencing (scRNA-seq) analysis, we collected peripheral blood mononuclear cells (PBMCs) from two representative patients at the pretreatment, irAE occurrence, and resolution stages. (3) Results: Our study revealed distinct plasma protein signatures in HCC patients experiencing irAEs after PD-1 inhibition combination therapy. We clarified the relationship between monocyte activation and irAEs, identified a strongly associated CD14-MC-CCL3 monocyte subset, and explored the role of the IFN-γ signaling pathway in monocyte activation during irAEs. (4) Conclusions: The activation of monocytes induced by the IFN-γ signaling pathway is an important mechanism underlying the occurrence of irAEs in HCC patients receiving PD-1 inhibition combination therapy.

Immunogenicity and safety in rabbits of a Clostridioides difficile vaccine combining novel toxoids and a novel adjuvant

Clostridioides difficile infection (CDI) is a serious healthcare-associated disease, causing symptoms such as diarrhea and pseudomembranous colitis. The major virulence factors responsible for the disease symptoms are two secreted cytotoxic proteins, TcdA and TcdB. A parenteral vaccine based on formaldehyde-inactivated TcdA and TcdB supplemented with alum adjuvant, has previously been investigated in humans but resulted in an insufficient immune response. In search for an improved response, we investigated a novel toxin inactivation method and a novel, potent adjuvant. Inactivation of toxins by metal-catalyzed oxidation (MCO) was previously shown to preserve neutralizing epitopes and to annihilate reversion to toxicity. The immunogenicity and safety of TcdA and TcdB inactivated by MCO and combined with a novel carbohydrate fatty acid monosulphate ester-based (CMS) adjuvant were investigated in rabbits. Two or three intramuscular immunizations generated high serum IgG and neutralizing antibody titers against both toxins. The CMS adjuvant increased antibody responses to both toxins while an alum adjuvant control was effective only against TcdA. Systemic safety was evaluated by monitoring body weight, body temperature, and analysis of red and white blood cell counts shortly after immunization. Local safety was assessed by histopathologic examination of the injection site at the end of the study. Body weight gain was constant in all groups. Body temperature increased up to 1 ˚C one day after the first immunization but less after the second or third immunization. White blood cell counts, and percentage of neutrophils increased one day after immunization with CMS-adjuvanted vaccines, but not with alum. Histopathology of the injection sites 42 days after the last injection did not reveal any abnormal tissue reactions. From this study, we conclude that TcdA and TcdB inactivated by MCO and combined with CMS adjuvant demonstrated promising immunogenicity and safety in rabbits and could be a candidate for a vaccine against CDI.

Dark red tongue color formation caused by hyperglycemia is attributed to decreased blood flow of tongue tissue partially due to nuclear factor-kappa B pathway activation

OBJECTIVE

To investigate the potential mechanisms underlying the dark red tongue color formation induced by hyperglycemia.

METHODS

A high-fat diet and intraperitoneal injection of streptozotocin were used to establish a diabetes model. The color and blood flow of tongues were analyzed by the Tongue Diagnosis Analysis System and laser Doppler flowmetry, respectively. Inflammatory factors and adhesion factors were measured in the circulation and tongue tissue by an enzyme-linked immunosorbent assay. Western blotting was employed to evaluate nuclear factor-kappa B (NF-κB) p50 and inhibitor of kappa B kinase protein expression levels in the tongue. Then, the NF-κB inhibitor, pyrrolidine dithiocarbamic acid ammonium salt was utilized to repress NF-κB pathway activation to validate that the NF-κB pathway plays a key role in blood flow and dark red tongue color formation.

RESULTS

The diabetic rats displayed a dark red tongue color that was accompanied by NF-κB pathway activation and decreased blood flow in the tongue. These effects could be reversed by the NF-κB inhibitor.

CONCLUSIONS

Our investigation demonstrated that hyperglycemia led to dark red tongue color formation by decreasing blood flow in the tongue, which was partly due to NF-κB pathway activation.

CD31 as a probable responding and gate-keeping protein of the blood-brain barrier and the risk of Alzheimer's disease

Several studies have shown that an abnormal vascular-immunity link could increase Alzheimer's disease (AD) risk; however, the mechanism is unclear. CD31, also named platelet endothelial cell adhesion molecule (PECAM), is a surface membrane protein of both endothelial and immune cells and plays important roles in the interaction between the vascular and immune systems. In this review, we focus on research regarding CD31 biological actions in the pathological process that may contribute to AD based on the following rationales. First, endothelial, leukocyte and soluble forms of CD31 play multi-roles in regulating transendothelial migration, increasing blood-brain barrier (BBB) permeability and resulting in neuroinflammation. Second, CD31 expressed by endothelial and immune cells dynamically modulates numbers of signaling pathways, including Src family kinases, selected G proteins, and β-catenin which in turn affect cell-matrix and cell-cell attachment, activation, permeability, survival, and ultimately neuronal cell injury. In endothelia and immune cells, these diverse CD31-mediated pathways act as a critical regulator in the immunity-endothelia-brain axis, thereby mediating AD pathogenesis in ApoE4 carriers, which is the major genetic risk factor for AD. This evidence suggests a novel mechanism and potential drug target for CD31 in the background of genetic vulnerabilities and peripheral inflammation for AD development and progression.

Molecular Pathogenesis of Human Immunodeficiency Virus-Associated Disease of Oropharyngeal Mucosal Epithelium

The oropharyngeal mucosal epithelia have a polarized organization, which is critical for maintaining a highly efficient barrier as well as innate immune functions. In human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) disease, the barrier and innate immune functions of the oral mucosa are impaired via a number of mechanisms. The goal of this review was to discuss the molecular mechanisms of HIV/AIDS-associated changes in the oropharyngeal mucosa and their role in promoting HIV transmission and disease pathogenesis, notably the development of opportunistic infections, including human cytomegalovirus, herpes simplex virus, and Epstein-Barr virus. In addition, the significance of adult and newborn/infant oral mucosa in HIV resistance and transmission was analyzed. HIV/AIDS-associated changes in the oropharyngeal mucosal epithelium and their role in promoting human papillomavirus-positive and negative neoplastic malignancy are also discussed.

HMGA2 facilitates colorectal cancer progression via STAT3-mediated tumor-associated macrophage recruitment

Rationale: Tumor-associated macrophages (TAMs), generally displaying the pro-tumor M2-like phenotype, strongly influence the progression of colorectal cancer (CRC) via their immunosuppressive activities. The high-mobility gene group A2 (HMGA2), an oncoprotein, is aberrantly overexpressed in CRC cells. However, the mechanisms by which tumor-derived HMGA2 modulates tumor microenvironment in CRC remain poorly understood.

Methods:In vivo subcutaneous tumor xenograft model, azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced tumor mouse model and in vitro co-culture assays were used to investigate the Hmga2 role in TAM recruitment and polarization. Luciferase and chromatin immunoprecipitation (ChIP) assays were applied to examine the mechanism of HMGA2-mediated transcriptional regulation of signal transducer and activator of transcription 3 (STAT3). The CD68 correlation with patient outcome was analyzed in 167 human CRC tissues.

Results: We found that HMGA2 in cancer cells promoted macrophage recruitment and M2 polarization in vitro and in vivo. HMGA2 directly bound to the STAT3 promoter to activate its transcription and subsequently induced CCL2 secretion, thus promoting macrophage recruitment. Our results from human CRC specimens also revealed a strong positive association between HMGA2 expression in tumor cells and CD68 expression in the stroma. We further showed that patients with an elevated CD68 expression had an unfavorable overall survival in all of the patients or in the subgroup with negative distant metastasis.

Conclusion: Our work uncovers new insight into the link between the HMGA2/STAT3/CCL2 axis and macrophage recruitment in CRC. These findings provide a novel therapeutic option for targeting the HMGA2/STAT3/CCL2 axis in CRC.

Overcoming physiological barriers by nanoparticles for intravenous drug delivery to the lymph nodes

The lymph nodes are major sites of cancer metastasis and immune activity, and thus represent important clinical targets. Although not as well-studied compared to subcutaneous administration, intravenous drug delivery is advantageous for lymph node delivery as it is commonly practiced in the clinic and has the potential to deliver therapeutics systemically to all lymph nodes. However, rapid clearance by the mononuclear phagocyte system, tight junctions of the blood vascular endothelium, and the collagenous matrix of the interstitium can limit the efficiency of lymph node drug delivery, which has prompted research into the design of nanoparticle-based drug delivery systems. In this mini review, we describe the physiological and biological barriers to lymph node targeting, how they inform nanoparticle design, and discuss the future outlook of lymph node targeting.

Participation of Monocyte Subpopulations in Progression of Experimental Endotoxemia (EE) and Systemic Inflammation

Systemic inflammation plays a crucial role in formation of various pathological conditions, including sepsis, burns, and traumas. The main effector cells participating in progression of systemic inflammation response and sepsis are monocytes, which regulate both innate and acquired immunity via phagocytosis, synthesis of cytokines and chemokines, antigen presentation, and lymphocyte activation. Thus, the monocytes are considered as a link between innate and acquired immunity. The monocyte subpopulations taken into consideration in the study essentially determine the progression of systemic inflammation and could serve as targets for therapeutic intervention. The complexity of the analysis of pathophysiology of systemic inflammation lies in its high variability conditioned by individual peculiarities of the patients and inflammation progression specifications. To overcome these limitation, model of experimental endotoxemia (EE) is used. The results of EE, in turn, cannot be directly extrapolated on patients with the systemic inflammatory response. This review is dedicated to discussing the role of monocyte subpopulations in progression of systemic inflammation/sepsis and EE.

The HopQ-CEACAM Interaction Controls CagA Translocation, Phosphorylation, and Phagocytosis of Helicobacter pylori in Neutrophils

Helicobacter pylori is highly adapted to humans and evades host immunity to allow its lifelong colonization. However, the H. pylori mouse model is artificial for H. pylori, and few adapted strains allow gastric colonization. Here, we show that human or CEACAM-humanized, but not mouse neutrophils are manipulated by the H. pylori HopQ-CEACAM interaction. Human CEACAMs are responsible for CagA phosphorylation, activation, and processing in neutrophils, whereas CagA translocation and tyrosine phosphorylation in DCs and macrophages is independent of the HopQ-CEACAM interaction. H. pylori affects the secretion of distinct chemokines in CEACAM-humanized neutrophils and macrophages. Most importantly, human CEACAMs on neutrophils enhance binding, oxidative burst, and phagocytosis of H. pylori and enhance bacterial survival in the phagosome. The H. pylori-CEACAM interaction modulates PMNs to reduce the H. pylori CagA translocation efficiency in vivo and to fine-tune the expression of CEACAM receptors on neutrophils to limit translocation of CagA and gastric pathology.

The cag type IV secretion system (cag-T4SS) of Helicobacter pylori exploits specific cellular carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), such as CEACAM1, -3, -5, and -6, as cellular receptors for CagA translocation into human gastric epithelial cells. We studied the interaction of H. pylori with human CEACAM1, CEACAM3, and CEACAM6 receptors (hCEACAMs) expressed on myeloid cells from CEACAM-humanized mice. Human and CEACAM-humanized mouse polymorphonuclear neutrophils (PMNs) allowed a specific HopQ-dependent interaction strongly enhancing CagA translocation. Translocated CagA was tyrosine phosphorylated, which was not seen in wild-type (wt) murine neutrophils. In contrast, human or murine bone marrow-derived macrophages and dendritic cells (DCs) revealed a low hCEACAM expression and bacterial binding. CagA translocation and tyrosine-phosphorylation was low and independent of the HopQ-CEACAM interaction. Neutrophils, but not macrophages or DCs, from CEACAM-humanized mice, significantly upregulated the proinflammatory chemokine MIP-1α. However, macrophages showed a significantly reduced amount of CXCL1 (KC) and CCL2 (MCP-1) secretion in CEACAM-humanized versus wt cells. Thus, H. pylori, via the HopQ-CEACAM interaction, controls the production and secretion of chemokines differently in PMNs, macrophages, and DCs. We further show that upon H. pylori contact the oxidative burst of neutrophils and phagocytosis of H. pylori was strongly enhanced, but hCEACAM3/6 expression on neutrophils allowed the extended survival of H. pylori within neutrophils in a HopQ-dependent manner. Finally, we demonstrate that during a chronic mouse infection, H. pylori is able to systemically downregulate hCEACAM1 and hCEACAM6 receptor expression on neutrophils, probably to limit CagA translocation efficiency and most likely gastric pathology.

Remodeling of reactive lymph nodes: Dynamics of stromal cells and underlying chemokine signaling

Lymph nodes (LNs) are secondary immune organs dispersed throughout the body. They are primarily composed of lymphocytes, "transient passengers" that are only present for a few hours. During this time, they extensively interact with a meshwork of stromal cells. Although these cells constitute less than 5% of all LN cells, they are integral to LN function: Stromal cells create a three-dimensional network that provides a rigid backbone for the transport of lymph and generates "roads" for lymphocyte migration. Beyond structural support, the LN stroma also produces survival signals for lymphocytes and provides nutrients, soluble factors, antigens, and immune cells collectively required for immune surveillance and the generation of adaptive immune responses. A unique feature of LNs is their ability to considerably and rapidly change size: the volume and cellularity of inflamed LNs can increase up to 20-fold before returning to homeostatic levels. This cycle will be repeated many times during life and is accommodated by stromal cells. The dynamics underlying this dramatic remodeling are subject of this review. We will first introduce the main types of LN stromal cells and explain their known functions. We will then discuss how these cells enable LN growth during immune responses, with a particular focus on underlying cellular mechanisms and molecular cues. Similarly, we will elaborate on stromal dynamics mediating the return to LN homeostasis, a process that is mechanistically much less understood than LN expansion.

Human cytomegalovirus infection and coronary heart disease: a systematic review

Background

Human cytomegalovirus (HCMV) infection is closely associated with coronary heart disease.

Main body of the abstract

In 1987, Adam et al. were the first to report an association between HCMV infection and atherosclerosis (AS), and later, many serum epidemiology and molecular biology studies showed that HCMV-infected endothelial cells play an important role in the development of AS. As patients with HCMV are generally susceptible to coronary heart disease, and with the increasing elderly population, a review of recent studies focusing on the relationships of HCMV infection and coronary heart disease is timely and necessary.

Short conclusion

The role of HCMV infection in the development of AS needs further study, since many remaining issues need to be explored and resolved. For example, whether HCMV promotes the development of coronary AS, and what the independent factors that lead to coronary artery AS by viral infection are. A comprehensive understanding of HCMV infection is needed in order to develop better strategies for preventing AS.

The cytokine network in women with an asymptomatic short cervix and the risk of preterm delivery

PROBLEM

To characterize the amniotic fluid (AF) inflammatory-related protein (IRP) network in patients with a sonographic short cervix (SCx) and to determine its relation to early preterm delivery (ePTD).

METHOD OF STUDY

A retrospective cohort study included women with a SCx (≤25 mm; n=223) who had amniocentesis and were classified according to gestational age (GA) at diagnosis and delivery (ePTD <32 weeks of gestation).

RESULTS

(i) In women with a SCx ≤ 22 1/7 weeks, the concentration of most IRPs increased as the cervix shortened; those with ePTD had a higher rate of increase in MIP-1α, MCP-1, and IL-6 concentrations than those delivering later; and (ii) the concentration of most IRPs and the correlation between several IRP pairs were higher in the ePTD group than for those delivering later.

CONCLUSION

Women with a SCx at 16-22 1/7 weeks have a unique AF cytokine network that correlates with cervical length at diagnosis and GA at delivery. This network may aid in predicting ePTD.

An Evaluation of Ischaemic Preconditioning as a Method of Reducing Ischaemia Reperfusion Injury in Liver Surgery and Transplantation

Liver Ischaemia Reperfusion (IR) injury is a major cause of post-operative liver dysfunction, morbidity and mortality following liver resection surgery and transplantation. There are no proven therapies for IR injury in clinical practice and new approaches are required. Ischaemic Preconditioning (IPC) can be applied in both a direct and remote fashion and has been shown to ameliorate IR injury in small animal models. Its translation into clinical practice has been difficult, primarily by a lack of knowledge regarding the dominant protective mechanisms that it employs. A review of all current studies would suggest that IPC/RIPC relies on creating a small tissue injury resulting in the release of adenosine and l-arginine which act through the Adenosine receptors and the haem-oxygenase and endothelial nitric oxide synthase systems to reduce hepatocyte necrosis and improve the hepatic microcirculation post reperfusion. The next key step is to determine how long the stimulus requires to precondition humans to allow sufficient injury to occur to release the potential mediators. This would open the door to a new therapeutic chapter in this field.

Chemokines (CCL3, CCL4, and CCL5) Inhibit ATP-Induced Release of IL-1β by Monocytic Cells

Chemokines and ATP are among the mediators of inflammatory sites that can enter the circulation via damaged blood vessels. The main function of chemokines is leukocyte mobilization, and ATP typically triggers inflammasome assembly. IL-1β, a potent inflammasome-dependent cytokine of innate immunity, is essential for pathogen defense. However, excessive IL-1β may cause life-threatening systemic inflammation. Here, we hypothesize that chemokines control ATP-dependent secretion of monocytic IL-1β. Lipopolysaccharide-primed human monocytic U937 cells were stimulated with the P2X7 agonist BzATP for 30 min to induce IL-1β release. CCL3, CCL4, and CCL5 dose dependently inhibited BzATP-stimulated release of IL-1β, whereas CXCL16 was ineffective. The effect of CCL3 was confirmed for primary mononuclear leukocytes. It was blunted after silencing CCR1 or calcium-independent phospholipase A2 (iPLA2) by siRNA and was sensitive to antagonists of nicotinic acetylcholine receptors containing subunits α7 and α9. U937 cells secreted small factors in response to CCL3 that mediated the inhibition of IL-1β release. We suggest that CCL chemokines inhibit ATP-induced release of IL-1β from U937 cells by a triple-membrane-passing mechanism involving CCR, iPLA2, release of small mediators, and nicotinic acetylcholine receptor subunits α7 and α9. We speculate that whenever chemokines and ATP enter the circulation concomitantly, systemic release of IL-1β is minimized.

Macrophage migration inhibitory factor protects from nonmelanoma epidermal tumors by regulating the number of antigen-presenting cells in skin

The response of the skin to harmful environmental agents is shaped decisively by the status of the immune system. Keratinocytes constitutively express and secrete the chemokine-like mediator, macrophage migration inhibitory factor (MIF), more strongly than dermal fibroblasts, thereby creating a MIF gradient in skin. By using global and epidermis-restricted Mif-knockout (Mif^-/- and K14-Cre^+/tg; Mif^fl/fl) mice, we found that MIF both recruits and maintains antigen-presenting cells in the dermis/epidermis. The reduced presence of antigen-presenting cells in the absence of MIF was associated with accelerated and increased formation of nonmelanoma skin tumors during chemical carcinogenesis. Our results demonstrate that MIF is essential for maintaining innate immunity in skin. Loss of keratinocyte-derived MIF leads to a loss of control of epithelial skin tumor formation in chemical skin carcinogenesis, which highlights an unexpected tumor-suppressive activity of MIF in murine skin.-Brocks, T., Fedorchenko, O., Schliermann, N., Stein, A., Moll, U. M., Seegobin, S., Dewor, M., Hallek, M., Marquardt, Y., Fietkau, K., Heise, R., Huth, S., Pfister, H., Bernhagen, J., Bucala, R., Baron, J. M., Fingerle-Rowson, G. Macrophage migration inhibitory factor protects from nonmelanoma epidermal tumors by regulating the number of antigen-presenting cells in skin.

Evaluation of innate and adaptive immunity contributing to the antitumor effects of PD1 blockade in an orthotopic murine model of pancreatic cancer

Despite the clinical success of anti-PD1 antibody (α-PD1) therapy, the immune mechanisms contributing to the antineoplastic response remain unclear. Here, we describe novel aspects of the immune response involved in α-PD1-induced antitumor effects using an orthotopic Kras (G12D)/p53(R172H)/Pdx1-Cre (KPC) model of pancreatic ductal adenocarcinoma (PDA). We found that positive therapeutic outcome involved both the innate and adaptive arms of the immune system. Adoptive transfer of total splenocytes after short-term (3 d) but not long-term (28 d) PD1 blockade significantly extended survival of non-treated tumor-bearing recipient mice. This protective effect appeared to be mostly mediated by T cells, as adoptive transfer of purified natural killer (NK) cells and/or granulocyte receptor 1 (Gr1)(+) cells or splenocytes depleted of Gr1(+) cells and NK cells did not exhibit transferrable antitumor activity following short-term PD1 blockade. Nevertheless, splenic and tumor-derived CD11b(+)Gr1(+) cells and NK cells showed significant persistence of α-PD1 bound to these cells in the treated primary recipient mice. We observed that short-term inhibition of PD1 signaling modulated the profiles of multifunctional cytokines in the tumor immune-infiltrate, including downregulation of vascular endothelial growth factor A (VEGF-A). Altogether, the data suggest that systemic blockade of PD1 results in rapid modulation of antitumor immunity that differs in the tumor microenvironment (TME) when compared to the spleen. These results demonstrate a key role for early immune-mediated events in controlling tumor progression in response to α-PD1 treatment and warrant further investigation into the mechanisms governing responses to the therapy at the innate-adaptive immune interface.

Curcumin attenuates oxidative stress following downhill running-induced muscle damage

Downhill running causes muscle damage, and induces oxidative stress and inflammatory reaction. Recently, it is shown that curcumin possesses anti-oxidant and anti-inflammatory potentials. Interestingly, curcumin reduces inflammatory cytokine concentrations in skeletal muscle after downhill running of mice. However, it is not known whether curcumin affects oxidative stress after downhill running-induced muscle damage. Therefore, the purpose of this study was to investigate the effects of curcumin on oxidative stress following downhill running induced-muscle damage. We also investigated whether curcumin affects macrophage infiltration via chemokines such as MCP-1 and CXCL14. Male C57BL/6 mice were divided into four groups; rest, rest plus curcumin, downhill running, or downhill running plus curcumin. Downhill running mice ran at 22 m/min, -15% grade on the treadmill for 150 min. Curcumin (3mg) was administered in oral administration immediately after downhill running. Hydrogen peroxide concentration and NADPH-oxidase mRNA expression in the downhill running mice were significantly higher than those in the rest mice, but these variables were significantly attenuated by curcumin administration in downhill running mice. In addition, mRNA expression levels of MCP-1, CXCL14 and F4/80 reflecting presence of macrophages in the downhill running mice were significantly higher than those in the rest mice. However, MCP-1 and F4/80 mRNA expression levels were significantly attenuated by curcumin administration in downhill running mice. Curcumin may attenuate oxidative stress following downhill running-induced muscle damage.

Role of recently migrated monocytes in cigarette smoke-induced lung inflammation in different strain of mice

This study investigates the role of proinflammatory monocytes recruited from blood circulation and recovered in bronchoalveolar lavage (BAL) fluid in mediating the lung damage in a model of acute cigarette smoke (CS)-induced lung inflammation in two strains of mice with different susceptibility to develop emphysema (susceptible -C57BL/6J and non susceptible -129S2/SvHsd). Exposure to whole-body CS for 3 consecutive research cigarettes in one single day induced acute inflammation in the lung of mice. Analysis of BAL fluid showed more influx of recently migrated monocytes at 72 h after CS-exposition in susceptible compared to non susceptible mice. It correlated with an increase in MMP-12 and TNF-α protein levels in the lung tissue, and with an increment of NF-κB translocation to the nucleus measured by electrophoretic mobility shift assay in C57BL/6J mice. To determine the functional role of these proinflammatory monocytes in mediating CS-induced airway inflammation, alveolar macrophages and blood monocytes were transiently removed by pretreatment with intratracheal and intravenous liposome-encapsulated CL2MDP, given 2 and 4 days prior to CS exposure and their repopulation was studied. Monocytes/macrophages were maximally depleted 48 h after last liposome application and subsequently recently migrated monocytes reappeared in BAL fluid of susceptible mice at 72 h after CS exposure. Recently migrated monocytes influx to the lung correlated with an increase in the MMP-12 protein level in the lung tissue, indicating that the increase in proinflammatory monocytes is associated with a major tissue damaging. Therefore our data confirm that the recruitment of proinflammatory recently migrated monocytes from the blood are responsible for the increase in MMP-12 and has an important role in the pathogenesis of lung disease induced by acute lung inflammation. These results could contribute to understanding the different susceptibility to CS of these strains of mice.

Beneficial impact of CCL2 and CCL12 neutralization on experimental malignant pleural effusion

Using genetic interventions, we previously determined that C-C motif chemokine ligand 2 (CCL2) promotes malignant pleural effusion (MPE) formation in mice. Here we conducted preclinical studies aimed at assessing the specific therapeutic potential of antibody-mediated CCL2 blockade against MPE. For this, murine MPEs or skin tumors were generated in C57BL/6 mice by intrapleural or subcutaneous delivery of lung (LLC) or colon (MC38) adenocarcinoma cells. Human lung adenocarcinoma cells (A549) were used to induce MPEs in severe combined immunodeficient mice. Intraperitoneal antibodies neutralizing mouse CCL2 and/or CCL12, a murine CCL2 ortholog, were administered at 10 or 50 mg/kg every three days. We found that high doses of CCL2/12 neutralizing antibody treatment (50 mg/kg) were required to limit MPE formation by LLC cells. CCL2 and CCL12 blockade were equally potent inhibitors of MPE development by LLC cells. Combined CCL2 and CCL12 neutralization was also effective against MC38-induced MPE and prolonged the survival of mice in both syngeneic models. Mouse-specific CCL2-blockade limited A549-caused xenogeneic MPE, indicating that host-derived CCL2 also contributes to MPE precipitation in mice. The impact of CCL2/12 antagonism was associated with inhibition of immune and vascular MPE-related phenomena, such as inflammation, new blood vessel assembly and plasma extravasation into the pleural space. We conclude that CCL2 and CCL12 blockade are effective against experimental MPE induced by murine and human adenocarcinoma in mice. These results suggest that CCL2-targeted therapies may hold promise for future use against human MPE.

Immunological cells and functions in Gaucher disease

The macrophage (MΦ) has been the focus of causality, research, and therapy of Gaucher disease, but recent evidence casts doubt its solitary role in the disease pathogenesis. The excess of glucosylceramide (GC) in such cells accounts for some of the disease manifestations. Evidence of increased expression of C-C and C-X-C chemokines (i.e., CCL2,CXCL1, CXCL8) in Gaucher disease could be critical for monocyte transformation to inflammatory subsets of macrophages and dendritic cells (DC) as well as neutrophil (PMNs) recruitment to visceral organs. These immune responses could be essential for activation of T- and B-cell subsets, and the induction of numerous cytokines and chemokines that participate in the initiation and propagation of the molecular pathogenesis of Gaucher disease. The association of Gaucher disease with a variety of cellular and humoral immune responses is reviewed here to provide a potential foundation for expanding the complex pathophysiology of Gaucher disease.

IL-10 contributes to the suppressive function of tumour-associated myeloid cells and enhances myeloid cell accumulation in tumours

Studies have revealed that tumour-associated myeloid cells (TAMC) are one of the major sources of IL-10 in tumour-bearing mice. However, the significance of TAMC-derived IL-10 in tumour immunity is poorly understood. Here, we show that IL-10 blockade or IL-10 deficiency reduces the capacity of TAMC in suppressing the proliferation of P1A-specific CD8 T cells. In the spleen, IL-10-deficient and wild-type (WT) mice bearing large tumour burdens have similar TAMC populations. The tumours from IL-10-deficient mice, however, have reduced numbers of TAMC compared with tumours from their WT counterparts. IL-10⁻/⁻ RAG-2⁻/⁻ mice also had reduced numbers of TAMC compared with tumours from IL-10⁺/⁺ RAG-2⁻/⁻ mice; therefore, the reduction in TAMC in IL-10-deficient tumours was not because of adaptive immune response in tumours. Adoptively transferred tumour antigen-specific CD8 T cells expanded more efficiently within tumours in IL-10⁻/⁻ RAG-2⁻/⁻ mice than in tumours from IL-10⁺/⁺ RAG-2⁻/⁻ mice. Cytotoxic T lymphocyte adoptive transfer therapy prevented tumour evasion in IL-10⁻/⁻ RAG-2⁻/⁻ mice more efficiently than in IL-10⁺/⁺ RAG-2⁻/⁻ mice. Thus, IL-10 enhances the accumulation of myeloid cells in tumours, and TAMC-derived IL-10 suppresses the activation and expansion of tumour antigen-specific T cells.

The role of the lymphatic system in vaccine trafficking and immune response

The development and improvement of vaccines has been a significant endeavor on the part of the medical community for more than the last two centuries, and the success of these efforts is obvious when one considers the millions of lives that have been saved. Recent work in the field of vaccines, however, indicates that vaccines may be developed for even more challenging diseases than those previously addressed. It will be important in achieving this feat to account for the physical and chemical processes related to vaccine trafficking, rather than solely relying on our knowledge of the pathogen and our empirical experience. A thorough understanding of the lymphatic system is essential considering the role it plays in antigen trafficking and all immunological activity. This review describes the results of recent work that provides insight into the physiological processes of the lymphatic system and its various components with an emphasis on vaccine antigen trafficking from the administration site to secondary lymphoid tissues and the ensuing immune response. The review also discusses current challenges in designing vaccines and presents modern strategies for designing vaccines to better interface with the lymphatic system.

Spiral ligament fibrocyte-derived MCP-1/CCL2 contributes to inner ear inflammation secondary to nontypeable H. influenzae-induced otitis media

Background

Otitis media (OM), one of the most common pediatric infectious diseases, causes inner ear inflammation resulting in vertigo and sensorineural hearing loss. Previously, we showed that spiral ligament fibrocytes (SLFs) recognize OM pathogens and up-regulate chemokines. Here, we aim to determine a key molecule derived from SLFs, contributing to OM-induced inner ear inflammation.

Methods

Live NTHI was injected into the murine middle ear through the tympanic membrane, and histological analysis was performed after harvesting the temporal bones. Migration assays were conducted using the conditioned medium of NTHI-exposed SLFs with and without inhibition of MCP-1/CCL2 and CCR2. qRT-PCR analysis was performed to demonstrate a compensatory up-regulation of alternative genes induced by the targeting of MCP-1/CCL2 or CCR2.

Results

Transtympanic inoculation of live NTHI developed serous and purulent labyrinthitis after clearance of OM. THP-1 cells actively migrated and invaded the extracellular matrix in response to the conditioned medium of NTHI-exposed SLFs. This migratory activity was markedly inhibited by the viral CC chemokine inhibitor and the deficiency of MCP-1/CCL2, indicating that MCP-1/CCL2 is a main attractant of THP-1 cells among the SLF-derived molecules. We further demonstrated that CCR2 deficiency inhibits migration of monocyte-like cells in response to NTHI-induced SLF-derived molecules. Immunolabeling showed an increase in MCP-1/CCL2 expression in the cochlear lateral wall of the NTHI-inoculated group. Contrary to the in vitro data, deficiency of MCP-1/CCL2 or CCR2 did not inhibit OM-induced inner ear inflammation in vivo. We demonstrated that targeting MCP-1/CCL2 enhances NTHI-induced up-regulation of MCP-2/CCL8 in SLFs and up-regulates the basal expression of CCR2 in the splenocytes. We also found that targeting CCR2 enhances NTHI-induced up-regulation of MCP-1/CCL2 in SLFs.

Conclusions

Taken together, we suggest that NTHI-induced SLF-derived MCP-1/CCL2 is a key molecule contributing to inner ear inflammation through CCR2-mediated recruitment of monocytes. However, deficiency of MCP-1/CCL2 or CCR2 alone was limited to inhibit OM-induced inner ear inflammation due to compensation of alternative genes.

c9t11-Conjugated linoleic acid-rich oil fails to attenuate wasting in colon-26 tumor-induced late-stage cancer cachexia in male CD2F1 mice

SCOPE

Cancer cachexia is characterized by muscle and adipose tissue wasting caused partly by chronic, systemic inflammation. Conjugated linoleic acids (CLAs) are a group of fatty acids with various properties including anti-inflammatory cis9, trans11 (c9t11)-CLA and lipid-mobilizing trans10, cis12 (t10c12)-CLA. The purpose of this study was to test whether dietary supplementation of a c9t11-CLA-rich oil (6:1 c9t11:t10c12) could attenuate wasting of muscle and adipose tissue in colon-26 adenocarcinoma-induced cachexia in mice.

METHODS AND RESULTS

Loss of body weight, muscle and adipose tissue mass caused by tumors were not rescued by supplementation with the c9t11-CLA-rich oil. In quadriceps muscle, c9t11-CLA-rich oil exacerbated tumor-induced gene expression of inflammatory markers tumor necrosis factor-α, IL-6 receptor and the E3 ligase MuRF-1 involved in muscle proteolysis. In epididymal adipose tissue, tumor-driven delipidation and atrophy was aggravated by the c9,t11-CLA-rich oil, demonstrated by further reduced adipocyte size and lower adiponectin expression. However, expression of inflammatory cytokines and macrophage markers were not altered by tumors, or CLA supplementation.

CONCLUSION

These data suggest that addition of c9t11-CLA-rich oil (0.6% c9t11, 0.1% t10c12) in diet did not ameliorate wasting in mice with cancer cachexia. Instead, it increased expression of inflammatory markers in the muscle and increased adipose delipidation.

Monocyte-bound PF4 in the pathogenesis of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a life- and limb-threatening thrombotic disorder that develops after exposure to heparin, often in the setting of inflammation. We have shown previously that HIT is associated with antibodies to complexes that form between platelet factor 4 and glycosaminoglycan (GAG) side chains on the surface of platelets. However, thrombosis can occur in the absence of thrombocytopenia. We now show that platelet factor 4 binds to monocytes and forms antigenic complexes with their surface GAG side chains more efficiently than on platelets likely due to differences in GAG composition. Binding to monocytes is enhanced when the cells are activated by endotoxin. Monocyte accumulation within developing arteriolar thrombi was visualized by situ microscopy. Monocyte depletion or inactivation in vivo attenuates thrombus formation induced by photochemical injury of the carotid artery in a modified murine model of HIT while paradoxically exacerbating thrombocytopenia. These studies demonstrate a previously unappreciated role for monocytes in the pathogenesis of arterial thrombosis in HIT and suggest that therapies targeting these cells might provide an alternative approach to help limit thrombosis in this and possibly other thrombotic disorders that occur in the setting of inflammation.

Monocyte-bound PF4 in the pathogenesis of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a life- and limb-threatening thrombotic disorder that develops after exposure to heparin, often in the setting of inflammation. We have shown previously that HIT is associated with antibodies to complexes that form between platelet factor 4 and glycosaminoglycan (GAG) side chains on the surface of platelets. However, thrombosis can occur in the absence of thrombocytopenia. We now show that platelet factor 4 binds to monocytes and forms antigenic complexes with their surface GAG side chains more efficiently than on platelets likely due to differences in GAG composition. Binding to monocytes is enhanced when the cells are activated by endotoxin. Monocyte accumulation within developing arteriolar thrombi was visualized by situ microscopy. Monocyte depletion or inactivation in vivo attenuates thrombus formation induced by photochemical injury of the carotid artery in a modified murine model of HIT while paradoxically exacerbating thrombocytopenia. These studies demonstrate a previously unappreciated role for monocytes in the pathogenesis of arterial thrombosis in HIT and suggest that therapies targeting these cells might provide an alternative approach to help limit thrombosis in this and possibly other thrombotic disorders that occur in the setting of inflammation.

Chemokine CXCL1/KC and its receptor CXCR2 are responsible for neutrophil chemotaxis in adenoviral keratitis

Epidemic keratoconjunctivitis (EKC), caused by human adenovirus (HAdV), is one of the most common ocular infections and results in corneal inflammation and subepithelial infiltrates. Adenoviral keratitis causes significant morbidity to the patients, and is characterized by infiltration of leukocytes in the corneal stroma, and expression of chemokines. The exact role of these chemokines in adenoviral infection has not been studied due to lack of animal models. Here, we have characterized the role of chemokine CXCL1/KC and receptor CXCR2 in adenoviral keratitis using a novel mouse model. Analysis of chemokine expression, leukocyte infiltration, and development of keratitis was performed by ELISA, flow cytometry, and histopathology, respectively. Deficiency of CXCL1 and CXCR2 resulted in delayed infiltration of neutrophils, but not inflammatory monocytes in HAdV-37 corneal infection. CXCL1(-/-) mice showed decreased expression of CXCL2/MIP-2, but not CCL2/MCP-1. CXCR2(-/-) mice showed increased expression of CXCL1 and CXCL2, but not CCL2. Both CXCL1(-/-) and CXCR2(-/-) mice demonstrated keratitis similar to wild-type mice. In conclusion, both CXCL1 and CXCR2 play an important role in chemokine expression and neutrophil infiltration following adenoviral corneal infection, but have a redundant role in the development of keratitis.

CpG and Non-CpG oligodeoxynucleotides induce differential proinflammatory gene expression profiles in liver and peripheral blood leukocytes in mice

Proinflammatory effects caused by oligodeoxynucleotides (ODN) include cytokine production, splenomegaly and infiltration of mononuclear cells into tissues. Presence of one or more CpG motifs in an ODN sequence confers potency for proinflammatory properties. The objective of this research was to characterize the proinflammatory effects produced by CpG containing ODN as compared to non-CpG ODN using gene array analysis. Female CD-1 mice were administered equipotent dose regimens of a CpG ODN (ISIS 12449, 4 mg/kg sc, single or repeat dose for 7 d) or a non-CpG ODN (ISIS 2302, 50 mg/kg sc, q2d for 1 or 3 weeks) and tissues (liver and peripheral blood leukocytes) were harvested for immunohistochemical analysis or gene array analysis. Splenomegaly, a marker of ODN-induced inflammation, was greatest (3-fold above control) with ISIS 12449 when given at multiple doses. Immunohistochemical staining identified mainly monocytes/macrophages as the immune cell infiltrates in the liver following ISIS 12449 or ISIS 2302 treatment. Gene analysis of liver tissue indicated enhanced expression of chemokines (MIG, MIP-2beta, MCP-1, IL-1beta, CCR3), cell surface markers (CD14, CD18, CD86, CD11c, P-selectin), intracellular markers (NF-kappaBp65, MyD88, Survivin) and markers of cell proliferation (PCNA, Ki-67, CD71) was produced with ISIS 12449 or ISIS 2302. Although CpG and non-CpG containing ODN produced similar gene expression profiles, notable differences were observed to suggest that their mechanisms of immune modulation are not completely overlapping. MIG and MIP 1beta were identified as potential biomarker for immune stimulation that may be used to further study the species specificity, sequence/structure dependence and time course of proinflammatory ODN and antisense inhibitors used as therapeutics.

Soluble cell adhesion molecules in monocytes of Alzheimer's disease and mild cognitive impairment

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with characteristic neuropathological features that are accompanied by inflammatory processes and release of pro-inflammatory cytokines. There is evidence that microglial cells are a key mediator of damage in AD. The microglial compartment may arise to a greater part from activation and transmigration of circulating monocytes. The aim of the present pilot study was to explore, if different cell adhesion molecules (ICAM-1 and -3, PECAM-1, VCAM-1, P-, L- and E-selectins, E-cadherin), RAGE and CD14 are affected in monocytes of healthy subjects compared to patients suffering from AD or mild cognitive impairment (MCI). Monocytes were isolated by negative magnetic selection (MACS) from EDTA blood samples, and extracts were analyzed by Searchlight Multiplex ELISAs. When compared to healthy subjects, the ratio of monocytic ICAM-3/CD14 was significantly decreased in MCI and AD patients and the ratio of the monocytic P-selectin/CD14 was specifically decreased in AD patients. In conclusion, our data show that monocytic cell adhesion molecules are decreased in AD and MCI patients. Further larger longitudinal studies should then clarify whether any of these parameters may be useful as a diagnostic biomarker.

Comprehensive amniotic fluid cytokine profile evaluation in women with a short cervix: which cytokine(s) correlates best with outcome?

OBJECTIVE

The objective of this study was to determine whether an expanded amniotic fluid cytokine profile predicts spontaneous preterm birth in patients with short cervix in the midtrimester.

STUDY DESIGN

Amniocentesis was performed on singleton gestations between 16-24 weeks with a cervical length <or=25 mm. Amniotic fluid from patients who received no surgical or hormonal treatment was assayed for 25 cytokines. Univariate analysis identified cytokine(s) that correlated with the interval between amniocentesis to delivery. Stepwise regression identified which cytokine(s) was most predictive of delivery, followed by the generation of receiver-operator characteristic curves. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated.

RESULTS

Forty-four amniotic fluid samples were analyzed. After stepwise regression, only monocyte chemotactic protein-1 remained significant and was the most predictive of early delivery. With a cutoff of 1320 pg/mL, monocyte chemotactic protein-1 had a 69% sensitivity, 83% specificity, 36% positive predictive value, and 87% negative predictive value to predict spontaneous preterm birth within 1 week of amniocentesis (P = .015).

CONCLUSION

Among 25 cytokines, monocyte chemotactic protein-1 was most predictive of spontaneous preterm birth.

Transcriptional profiling reveals developmental relationship and distinct biological functions of CD16+ and CD16- monocyte subsets

BACKGROUND

Human peripheral blood monocytes (Mo) consist of subsets distinguished by expression of CD16 (FCgammaRIII) and chemokine receptors. Classical CD16- Mo express CCR2 and migrate in response to CCL2, while a minor CD16+ Mo subset expresses CD16 and CX3CR1 and migrates into tissues expressing CX3CL1. CD16+ Mo produce pro-inflammatory cytokines and are expanded in certain inflammatory conditions including sepsis and HIV infection.

RESULTS

To gain insight into the developmental relationship and functions of CD16+ and CD16- Mo, we examined transcriptional profiles of these Mo subsets in peripheral blood from healthy individuals. Of 16,328 expressed genes, 2,759 genes were differentially expressed and 228 and 250 were >2-fold upregulated and downregulated, respectively, in CD16+ compared to CD16- Mo. CD16+ Mo were distinguished by upregulation of transcripts for dendritic cell (DC) (SIGLEC10, CD43, RARA) and macrophage (MPhi) (CSF1R/CD115, MafB, CD97, C3aR) markers together with transcripts relevant for DC-T cell interaction (CXCL16, ICAM-2, LFA-1), cell activation (LTB, TNFRSF8, LST1, IFITM1-3, HMOX1, SOD-1, WARS, MGLL), and negative regulation of the cell cycle (CDKN1C, MTSS1), whereas CD16- Mo were distinguished by upregulation of transcripts for myeloid (CD14, MNDA, TREM1, CD1d, C1qR/CD93) and granulocyte markers (FPR1, GCSFR/CD114, S100A8-9/12). Differential expression of CSF1R, CSF3R, C1QR1, C3AR1, CD1d, CD43, CXCL16, and CX3CR1 was confirmed by flow cytometry. Furthermore, increased expression of RARA and KLF2 transcripts in CD16+ Mo coincided with absence of cell surface cutaneous lymphocyte associated antigen (CLA) expression, indicating potential imprinting for non-skin homing.

CONCLUSION

These results suggest that CD16+ and CD16- Mo originate from a common myeloid precursor, with CD16+ Mo having a more MPhi - and DC-like transcription program suggesting a more advanced stage of differentiation. Distinct transcriptional programs, together with their recruitment into tissues via different mechanisms, also suggest that CD16+ and CD16- Mo give rise to functionally distinct DC and MPhi in vivo.

Critical role of CD11b+ macrophages and VEGF in inflammatory lymphangiogenesis, antigen clearance, and inflammation resolution

Using a bacterial pathogen-induced acute inflammation model in the skin, we defined the roles of local lymphatic vessels and draining lymph nodes (DLNs) in antigen clearance and inflammation resolution. At the peak day of inflammation, robust expansion of lymphatic vessels and profound infiltration of CD11b+/Gr-1+ macrophages into the inflamed skin and DLN were observed. Moreover, lymph flow and inflammatory cell migration from the inflamed skin to DLNs were enhanced. Concomitantly, the expression of lymphangiogenic growth factors such as vascular endothelial growth factor C (VEGF-C), VEGF-D, and VEGF-A were significantly up-regulated in the inflamed skin, DLNs, and particularly in enriched CD11b+ macrophages from the DLNs. Depletion of macrophages, or blockade of VEGF-C/D or VEGF-A, largely attenuated these phenomena, and produced notably delayed antigen clearance and inflammation resolution. Conversely, keratin 14 (K14)-VEGF-C transgenic mice, which have dense and enlarged lymphatic vessels in the skin dermis, exhibited accelerated migration of inflammatory cells from the inflamed skin to the DLNs and faster antigen clearance and inflammation resolution. Taken together, these results indicate that VEGF-C, -D, and -A derived from the CD11b+/Gr-1+ macrophages and local inflamed tissues play a critical role in promoting antigen clearance and inflammation resolution.

Is midtrimester short cervix a sign of intraamniotic inflammation?

OBJECTIVE

We sought to determine the relationship between the degree of cervical shortening and intraamniotic inflammation in patients presenting with a midtrimester short cervix.

STUDY DESIGN

Amniocentesis was performed on singleton pregnancies between 16-24 weeks' gestation with a sonographic cervical length (CL) </= 25 mm. The fluid was assayed for 25 cytokines. Spearman correlations were used to determine which cytokines correlate with CL. Stepwise regression identified the most significant cytokine and a receiver operating characteristic curve determined the CL cutoff predictive of intraamniotic inflammation.

RESULTS

In all, 109 amniotic fluid samples were analyzed. Most (21 of 25) cytokines were inversely correlated to CL. Monocyte chemotactic protein (MCP)-1 was the most significant by stepwise regression. Using a cutoff of MCP-1 > 1500 pg/mL, CL of 5 mm had an 86% sensitivity, 85% specificity, 58% positive predictive value, and 96% negative predictive value to predict elevated MCP-1 levels. After excluding patients with intraamniotic infection or labor, findings were similar.

CONCLUSION

CL </= 5 mm is associated with significant increases in amniotic fluid inflammatory cytokines, even in the absence of infection or labor. In the future, differentiation of those with and without inflammation may aid in choosing therapy directed at the cause of cervical shortening.

Leishmania major: recruitment of Gr-1+ cells into draining lymph nodes during infection is important for early IL-12 and IFN gamma production

The production of interleukin-12 and interferon-gamma is a key event for controlling leishmaniasis. Here, we tested the hypothesis that after murine infection with Leishmania major, cell migration into draining lymph nodes is crucial for early production of those cytokines. We showed that inflammatory cells carrying the marker of recently migrated cells, the Gr-1 antigen, including polymorphonuclear and mononuclear cells, migrate rapidly into the site of promastigote infection and, subsequently, into draining lymph nodes. Treatment with RB6-8C5 monoclonal antibody reduced local inflammation and migration of Gr-1+ cells into the draining lymph nodes. This reduction was associated with a decrease of interleukin-12 production by draining lymph node cells from BALB/c mice but not C57BL/6 mice. Additionally, interferon-gamma was also reduced in both mouse strains after depletion of Gr-1+ cells, suggesting that these cells are important for early interleukin-12 and interferon-gamma production. Our findings suggest that recently migrated myeloid cells, more than resident cells, are the major source of the early IL-12 production after L. major infection.

A novel approach for the generation of human dendritic cells from blood monocytes in the absence of exogenous factors

Human dendritic cells (DCs) for research and clinical applications are typically derived from purified blood monocytes that are cultured in a cocktail of cytokines for a week or more. Because it has been suggested that these cytokine-derived DCs may be deficient in some important immunological functions and might not accurately represent antigen presenting cell (APC) populations found under normal conditions in vivo, there is an interest in developing methods that permit the derivation of DCs in a more physiologically relevant manner in vitro. Here, we describe a simple and reliable technique for generating large numbers of highly purified DCs that is based on a one-way migration of blood monocytes through a layer of human umbilical vein endothelial cells (HUVECs) that are cultured to confluency in the upper chamber of a Transwell device. The resultant APCs, harvested from the lower Transwell chamber, resemble other cultured DC populations in their expression of major histocompatibility (MHC) and costimulatory molecules, ability to phagocytose protein antigens and capacity to trigger primary antigen-specific T cell responses. This technique offers several advantages over the standard method of in vitro cytokine-driven DC development, including: (1) the rapidity of this approach, as DC differentiation occurs in only 2 days, (2) the differentiation process itself, which is more akin to the development of DCs under physiologic conditions and (3) the cost-effectiveness of the system, since no monocyte pre-selection is required and DC development occurs in the absence of expensive recombinant cytokines.

Allergen induces the migration of platelets to lung tissue in allergic asthma

RATIONALE

Platelets are essential for pulmonary leukocyte recruitment, airway hyperresponsiveness, and bronchial remodeling in animals with allergic inflammation and can be found in bronchoalveolar lavage of sensitized animals. No studies, however, have explored the direct migration of platelets to lungs.

OBJECTIVES

To assess whether platelets migrate into lung parenchyma in response to inhaled allergen in ovalbumin-sensitized mice; to assess the role of the FcepsilonRI receptor in this phenomenon; and to evaluate whether platelets from patients with asthma, or from sensitized mice, undergo chemotaxis in vitro in response to relevant antigens.

METHODS

Ovalbumin-sensitized wild-type (WT) mice, or FcRgamma(-/-) mice lacking the FcepsilonRIgamma, were challenged with aerosolized allergen and lungs analyzed by platelet-specific immunohistochemistry. In some experiments, mice were depleted of platelets and cross-transfused with either WT or FcRgamma(-/-) platelets to assess the role of platelet FcRgamma(-/-). Chemotaxis of platelets from patients with asthma or from sensitized mice was studied in vitro.

MEASUREMENTS AND MAIN RESULTS

Histology of lungs revealed isolated platelets, migrating out of vessels and localizing underneath the airways after allergen challenge in WT but not in FcRgamma(-/-) mice. Platelets from patients with asthma and from sensitized WT mice, but not from sensitized FcRgamma(-/-) mice, migrated in vitro toward the relevant allergen or an anti-IgE. Platelets from normal mice were found to express FcepsilonRIgamma and platelet-bound IgEs were increased in sensitized mice.

CONCLUSIONS

Platelets migrate extravascularly in response to a sensitizing allergen via a mechanism dependent on the interaction among allergen, allergen-specific IgE, and the FcepsilonRI, and this may allow them to participate directly in allergic tissue inflammation.

Differential activation of mononuclear phagocytes in cerebellar malformation associated with Walker-Warburg syndrome

Walker-Warburg syndrome (WWS) is an autosomal recessive disorder with alterations affecting the CNS that are characteristic of type-II lissencephaly and dysplasia/hypoplasia of the cerebellum. Other than these features, WWS is typically also accompanied by muscular dystrophy and abnormalities affecting the eyes. There is at present little information on the state of microglial and mononuclear phagocytic cell responses within the brain in WWS. In this case report, we present evidence for focal and differential activation of mononuclear phagocytes specifically confined to the dysplastic cerebellum of an infant at 5 months of age, diagnosed with WWS.

CD16+ monocytes produce IL-6, CCL2, and matrix metalloproteinase-9 upon interaction with CX3CL1-expressing endothelial cells

The CD16+ subset of peripheral blood monocytes (Mo) is expanded dramatically during inflammatory conditions including sepsis, HIV-1 infection, and cancer. CD16+ express high levels of CX3CR1, which mediates arrest onto CX3CL1-expressing endothelial cells (EC) under flow conditions. In contrast, attachment of CD16- Mo onto cytokine-activated EC is independent of CX3CL1. Here, we investigate the ability of CD16+ and CD16- Mo to produce proinflammatory cytokines upon interaction with CX3CL1-expressing HUVEC. We demonstrate that CD16+ but not CD16- Mo produce high levels of IL-6, CCL2, and matrix metalloproteinase (MMP)-9 when cocultured with TNF/IFN-gamma-activated HUVEC or nonactivated HUVEC expressing CX3CL1. Furthermore, supernatants from Mo cocultured with cytokine-activated HUVEC induce neuronal death in vitro. These results suggest that membrane-bound CX3CL1 stimulates production of IL-6, CCL2, and MMP-9 by CD16+ Mo, likely via engagement of CX3CR1. Thus, expansion of CD16+ Mo and their accumulation onto CX3CL1-expressing EC may result in recruitment of Mo and T cell subsets at sites of inflammation in response to CCL2, IL-6-induced cell activation and/or differentiation, and MMP-9-mediated vascular and tissue injury.

Comparative protection against liver inflammation and fibrosis by a selective cyclooxygenase-2 inhibitor and a nonredox-type 5-lipoxygenase inhibitor

In this study, we examined the relative contribution of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO), two major proinflammatory pathways up-regulated in liver disease, to the progression of hepatic inflammation and fibrosis. Separate administration of 4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (SC-236), a selective COX-2 inhibitor, and CJ-13,610, a 5-LO inhibitor, to carbon tetrachloride-treated mice significantly reduced fibrosis as revealed by the analysis of Sirius Red-stained liver sections without affecting necroinflammation. Conversely, combined administration of SC-236 and 4-[3-[4-(2-methylimidazol-1-yl)-phenylthio]]phenyl-3,4,5,6-tetrahydro-2H-pyran-4-carboxamide (CJ-13,610) reduced both necroinflammation and fibrosis. These findings were confirmed in 5-LO-deficient mice receiving SC-236, which also showed reduced hepatic monocyte chemoattractant protein 1 expression. Interestingly, SC-236 and CJ-13,610 significantly increased the number of nonparenchymal liver cells with apoptotic nuclei (terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive). Additional pharmacological profiling of SC-236 and CJ-13,610 was performed in macrophages, the primary hepatic inflammatory cell type. In these cells, SC-236 inhibited prostaglandin (PG) E2 formation in a concentration-dependent manner, whereas CJ-13,610 blocked leukotriene B4 biosynthesis. Of note, the simultaneous addition of SC-236 and CJ-13,610 resulted in a higher inhibitory profile on PGE2 biosynthesis than the dual COX/5-LO inhibitor licofelone. These drugs differentially regulated interleukin-6 mRNA expression in macrophages. Taken together, these findings indicate that both COX-2 and 5-LO pathways are contributing factors to hepatic inflammation and fibrosis and that these two pathways of the arachidonic acid cascade represent potential targets for therapy.

Thrombus organization and healing in the swine experimental aneurysm model. Part I. A histological and molecular analysis

Object

The authors describe the process of thrombus organization in the swine surgical aneurysm model.

Methods

Lateral carotid artery aneurysms with immediately induced thrombosis were created in 31 swine for a time-course study. Aneurysms were evaluated at 1, 3, 7, 14, 30, and 90 days after they were created. Histological analyses included quantitative immunohistochemical studies and evaluation of collagen deposition. Complementary DNA microarray analysis was performed for gene expression profiling. The lists of up- and downregulated genes were cross-matched with lists of genes known to be associated with cytokines or the extracellular matrix. The expression of selected genes was quantified using real-time polymerase chain reaction. Functional clustering was performed with the Expression Analysis Systematic Explorer (EASE) bioinformatics package.

Results

Histological analysis demonstrated leukocyte and macrophage infiltration in the thrombus at Day 3, myofibroblast infiltration at Days 7 to 14, and progressive collagen deposition and contraction thereafter. Tissue organization occurred in a centripetal fashion. A previously undescribed reticular network of connective tissue was observed at the periphery of the aneurysm at Day 3. Macrophages appeared critical to this thrombus organization. A total of 1109 genes were significantly changed from reference time zero during the time course: CXCL14, which produces a monocyte-specific chemokine, was upregulated over 100-fold throughout the time course; IGF1 was upregulated fourfold at Day 7, whereas IGFBP2 was downregulated approximately 50% at Days 7 and 14. Osteopontin (SPP1) upregulation increased from 30-fold at Day 30 to 45-fold at Day 14. The EASE analysis yielded eight functional classes of gene expression.

Conclusions

This investigation provides a detailed histological and molecular analysis of thrombus organization in the swine aneurysm model. The companion study will describe the effect of embolic bioabsorbable polymers on this process.

Alteration in the gene expression pattern of primary monocytes after adhesion to endothelial cells

Monocytes originate from precursors made in the bone and remain in the circulation for nearly 24 h. Much effort has been done to identify the molecules regulating transendothelial migration of monocytes during inflammatory conditions. In contrast, considerably less is known about the process of constitutive monocyte emigration although nearly 340 million monocytes leave the circulation each day in healthy individuals. Previous studies indicated that chemokines were up-regulated in monocytes cocultured with endothelial cells that induce the retraction of the latter cell type, thereby increasing vascular permeability. Thus, we hypothesized that the utilities required for efficient constitutive monocyte extravasation are generated by monocytes themselves because of adhesion to naïve endothelial cells. To test this hypothesis, cDNA microarray analysis was performed to determine the changes in the gene expression pattern of primary monocytes that have been attached to endothelial cells compared with monocytes that were held in suspension, and we were able to identify three major groups of genes. The first group includes genes such as matrix metalloproteinase 1, monocyte chemoattractant protein 1, and tissue transglutaminase 2, which are likely required for monocyte extravasation. The second group consists of genes that are expressed in phagocytes such as caveolin-1 and CD74. Finally, the third group comprises genes that are expressed in cells of endothelial tissue and cartilage including E-selectin, fibronectin-1, matrix Gla protein, and aggrecanase-2. In summary, we conclude that adhesion of peripheral blood monocytes to naïve endothelial cells has two effects: mandatory extravasation-specific genes are regulated, and the differentiation program of monocytes is initiated.

Impaired Mononuclear Cell Immune Function in Extreme Obesity Is Corrected by Weight Loss

BACKGROUND

Obesity is associated with an increased prevalence and severity of infections. The mechanism(s) responsible for the increased risk of infections is unclear. We evaluated the effects of excessive adiposity and weight loss on peripheral blood mononuclear cell (PBMC) chemokine (macrophage chemoattractant protein-1 [MCP-1) and cytokine (interferon-gamma [IFNgamma]) production, which is an important component of the immune response to infectious pathogens.

METHODS

Lipopolysaccharide (LPS)and phorbol 12-myristate 13-acetate plus ionomycin (PMA + I)-stimulated PBMC MCP-1 and IFNgamma production were determined in six extremely obese subjects (body mass index [BMI] = 62.4 +/- 8.6 kg/m(2)) before and 1 year after gastric bypass surgery and in six age-matched lean subjects (BMI = 22.7 +/- 1.4 kg/m(2)).

RESULTS

At baseline, LPS-stimulated MCP-1 production and PMAI-stimulated IFNgamma production by PBMCs were 93.6% +/- 4.9% and 88.8% +/- 9.6% lower, respectively, in obese than in lean subjects (p < 0.03). Obese subjects lost 30.3% +/- 10.6% of their body weight at 1 year after gastric bypass surgery (p < 0.001). Weight loss completely restored LPS-stimulated MCP-1 production and PMA+I-stimulated IFNgamma production in obese subjects to normal.

CONCLUSIONS

Agonist-stimulated production of IFNgamma and MCP-1 are markedly suppressed in subjects with extreme obesity. Weight loss completely normalizes the ability of stimulated PBMCs to produce MCP-1 and IFNgamma. These findings could have important implications in understanding the increased risk of infections associated with obesity, and demonstrate a unique beneficial effect of weight loss on immune function.

Differential regulation of tumor necrosis factor-alpha-converting enzyme and angiotensin-converting enzyme by type I and II interferons in human normal and leukemic myeloid cells

The transmembrane metalloproteases angiotensin-converting enzyme (ACE) and tumor necrosis factor-alpha (TNF-alpha)-converting enzyme (TACE/ADAM-17) have been associated with inflammation, cancer progression and angiogenesis. Few investigations into the regulation of these enzymes by physiological stimuli have been reported. In this study, we investigated the influence of interferons (IFNs) type I (alpha, beta) and II (gamma) on ACE and TACE expression of human leukemic NB4 cells and monocytes. We assessed the expression of proteases by reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay and immunofluorescence analyses. IFNgamma, but not type I IFNs, upregulated membrane ACE in a dose- and time-dependency and this was reflected by the increase of ACE enzymatic activity and ACE mRNA. ACE upregulation was dependent on protein synthesis. Treatment of the interferon responsive factor 1 (IRF1)-unresponsive HepG2 cell line with IFNgamma did not affect ACE expression, thus suggesting the participation of the IRF1 signaling pathway in IFNgamma-mediated ACE upregulation in myeloid cells. In contrast, both types of IFNs, in a dose- and time-dependent manner, downregulated surface TACE without affecting TACE transcript. Soluble TACE was not detected in the medium of IFN-treated cells. IFNgamma-mediated decrease of surface TACE in NB4 cells was reversible, and correlated with an increase in intracellular TACE, suggesting that cell surface TACE was internalized in response to IFNs. These findings, showing the presence of IFN-dependent controlled mechanisms by which ACE and TACE levels are regulated in human normal and leukemic myeloid cells, may have implications in the context of current investigations on the therapeutic potential of IFNs.

Monocyte accumulation in mouse atherogenesis is progressive and proportional to extent of disease

Monocytes participate importantly in the pathogenesis of atherosclerosis, but their spatial and temporal recruitment from circulation remains uncertain. This study tests the hypothesis that monocyte accumulation in atheroma correlates with the extent of disease by using a sensitive and simple quantitative assay that allows tracking of highly enriched populations of blood monocytes. A two-step isolation method yielded viable and functionally intact highly enriched peripheral blood monocyte populations (>90%). Recipient mice received syngeneic monocytes labeled in two ways: by transgenically expressing EGFP or with a radioactive tracer [(111)In]oxine. After 5 days, more labeled cells accumulated in the aorta, principally the aortic root and ascending aorta, of 10-wk-old ApoE(-/-) compared with 10-wk-old C57BL/6 mice (223 +/- 3 vs. 87 +/- 22 cells per aorta). Considerably more monocytes accumulated in 20-wk-old ApoE(-/-) mice on either chow (314 +/- 41 cells) or high-cholesterol diet (395 +/- 53 cells). Fifty-week-old ApoE(-/-) mice accumulated even more monocytes in the aortic root, ascending aorta, and thoracic aorta after both chow (503 +/- 67 cells) or high-cholesterol diet (648 +/- 81 cells). Labeled monocyte content in the aorta consistently correlated with lesion surface area. These data indicate that monocytes accumulate continuously during atheroma formation, accumulation increases in proportion to lesion size, and recruitment is augmented with hypercholesterolemia. These results provide insights into mechanisms of atherogenesis and have implications for the duration of therapies directed at leukocyte recruitment.